CN119213758A - Stereoscopic display device and stereoscopic display method - Google Patents

Abstract

The present disclosure optimizes and displays a clear stereoscopic image while ensuring depth. A stereoscopic display device is provided. The stereoscopic display device includes a display section, a display driving section that displays an element image of a stereoscopic image on the display section, a light source control section that includes a first lens array that is arranged on a back side of the display section and includes a plurality of first cylindrical lenses arranged at a predetermined pitch, a second lens array that is arranged on a back side of the first lens array and includes a plurality of condenser lenses arranged at a pitch wider than the first cylindrical lenses, a plurality of light sources that are arranged on a back side of each condenser lens, a diffusion sheet that is arranged between the display section and the first lens array and is arranged at a position including each focal position of each first cylindrical lens, and a light source driving section that drives a line light source that irradiates the element image.

Description

Stereoscopic display device and stereoscopic display method

Technical Field

The present disclosure relates to a stereoscopic display device and a stereoscopic display method.

Background Art

Technologies for displaying stereoscopic images have been proposed for a long time (see, for example, Patent Document 1), and light field technology has attracted attention as a technology for displaying stereoscopic images (see, for example, Non-Patent Document 1).

The above information is provided as background information only to assist with understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above information might be applicable as prior art related to the present disclosure.

[Prior art literature]

Patent Document 1: Japanese Patent No. 5760428

Patent Document 2: Japanese Patent No. 6791058

Non-patent literature 1: BoyangLiu, XinzhuSang, XunboYu, XinGao, LiLiu, ChaoGao,PeirenWang, YangLe, and JingyanDu, “Time-multiplexed light field display with120-degree wide viewing angle,” Opt. Express (2019) 27, 35728-35739

Summary of the invention

Technical issues

However, light field technology is theoretically limited in terms of resolution, so there is a need for three-dimensional (3D) displays that can increase resolution while ensuring depth or breath.

Various aspects of the present disclosure at least solve the above-mentioned technical problems and/or disadvantages, and at least provide the advantages described below. Therefore, one aspect of the present disclosure is to provide a stereoscopic display device and a stereoscopic display method that appropriately display a more vivid three-dimensional image while ensuring depth.

Additional aspects will be disclosed in part in the description which follows and, in part, will be obvious from the description, or may be learned by the presented embodiments.

Technical Solution

According to one aspect of the present disclosure, a stereoscopic display device is provided. The stereoscopic display device includes: a display unit; a display driving unit, which displays an elemental image of a stereoscopic image on the display unit; a light source control unit, which has a first lens array arranged on the back side of the display unit and including a plurality of first cylindrical lenses arranged at a predetermined pitch, a second lens array arranged on the back side of the first lens array and including a plurality of second cylindrical lenses arranged at a pitch wider than the first cylindrical lenses, a plurality of light sources arranged on the back side of each second cylindrical lens, a diffusion sheet arranged between the display unit and the first lens array and arranged at a position including each focal position of each first cylindrical lens; and a light source driving unit, which drives the plurality of light sources that illuminate the elemental image.

According to another aspect of the present disclosure, a stereoscopic display method using a stereoscopic display device is provided. The stereoscopic display device includes: a display unit; a display driving unit, which displays an elemental image of a stereoscopic image on the display unit; a light source control unit, which has a first lens array arranged on the back side of the display unit and including a plurality of first cylindrical lenses arranged at a predetermined pitch, a second lens array arranged on the back side of the first lens array and including a plurality of second cylindrical lenses arranged at a pitch wider than the first cylindrical lenses, a plurality of light sources arranged on the back side of each second cylindrical lens, a diffusion sheet arranged between the display unit and the first lens array and arranged at a position including each focal position of each first cylindrical lens; and a light source driving unit, which drives the plurality of light sources that illuminate the elemental image, wherein in the stereoscopic display method, the plurality of elemental images are displayed on the display unit, and the plurality of light sources are driven sequentially.

Other aspects, advantages and salient features of the present disclosure will become apparent to those of ordinary skill in the art through the following detailed description of various embodiments of the present disclosure in conjunction with the accompanying drawings.

Technical Effects

According to the present disclosure, a stereoscopic display device and a stereoscopic display method can be provided that can appropriately display a more vivid three-dimensional image while ensuring depth.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram for explaining a display principle of a related stereoscopic display device according to an embodiment of the disclosure.

FIG. 2 is a diagram for explaining a display principle of a related stereoscopic display device according to an embodiment of the disclosure.

FIG. 3 is a diagram for explaining a display principle of a related stereoscopic display device according to an embodiment of the disclosure.

FIG. 4 is a diagram for explaining a field of view of a related stereoscopic display device according to an embodiment of the disclosure.

FIG. 5 is a diagram showing a relationship between a depth and a limit spatial frequency of a related stereoscopic display device according to an embodiment of the disclosure.

FIG. 6 is a diagram for explaining the viewing angle and the distance between lens pixels of a related stereoscopic display device according to an embodiment of the disclosure.

FIG. 7 is a diagram for explaining an observation method in two display modes according to an embodiment of the disclosure.

FIG. 8 is a schematic cross-sectional view of a stereoscopic display device according to an embodiment of the disclosure.

FIG. 9 is a schematic cross-sectional view of a stereoscopic display device according to an embodiment of the disclosure.

FIG. 10 is a cross-sectional view of a second lens element and a light source unit in a corresponding relationship in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 11 is a bird's-eye view of a light source unit according to an embodiment of the disclosure.

FIG. 12 is a diagram for explaining area control according to an embodiment of the disclosure.

FIG. 13 is a diagram for explaining field control of light source driving in a depth area according to an embodiment of the disclosure.

FIG. 14 is a graph showing the relationship between the viewing angle and the lens pitch of the first lens element according to an embodiment of the disclosure.

FIG. 15 is a block diagram showing a functional structure of a stereoscopic display device 1 according to an embodiment of the disclosure.

FIG. 16 is a diagram showing an example of a timing diagram of light source driving and display driving according to an embodiment of the disclosure.

FIG. 17 is a diagram showing an example of a timing diagram of light source driving and display driving according to an embodiment of the disclosure.

FIG. 18 is a diagram for explaining a method for generating a first image from multi-viewpoint images according to an embodiment of the disclosure.

FIG. 19 is a diagram for explaining region segmentation according to an embodiment of the disclosure.

FIG. 20 is a diagram showing the arrangement of a cylindrical lens array and a lens sheet according to a modified example of a disclosed embodiment.

FIG. 21 is a diagram showing the arrangement of first lens elements and parallax images of a lens sheet according to a modified example of a disclosed embodiment.

FIG. 22 is a diagram showing the arrangement of an anisotropic diffuser according to a modified example of a disclosed embodiment.

FIG. 23 is a cross-sectional view schematically showing a stereoscopic display device according to an embodiment of the disclosure.

FIG. 24 is a diagram showing a relationship between a diffusion sheet and element pixels in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 25 is a cross-sectional view schematically showing a shielding plate having slits in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 26 is a top view showing the arrangement of second lens elements of a cylindrical lens array in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 27 is a perspective view showing the arrangement of second lens elements of a cylindrical lens array in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 28 is a top view showing a cylindrical lens array observed through a diffusion sheet in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 29 is a cross-sectional view schematically showing a stereoscopic display device according to an embodiment of the disclosure.

FIG. 30 is a diagram illustrating time multiplexed field control according to an embodiment of the disclosure.

31 is a diagram illustrating the arrangement width of a light source and the focal point displacement width of a light source control unit in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 32 is a diagram illustrating a light-collecting pattern in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 33 is a diagram illustrating a screen display in which a plurality of fields of view are time-multiplexed in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 34 is a diagram illustrating a light-collecting pattern in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 35 is a diagram illustrating a light-collecting pattern in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 36 is a diagram showing the structure of a recording optical system in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 37 is a diagram showing the configuration of a reproduction optical system in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 38 is a diagram illustrating a light-collecting pattern in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 39 is a diagram illustrating a 5-split 2-shift lighting sequence in a stereoscopic display device according to an embodiment of the disclosure.

40 is a plan view showing the arrangement of a lens sheet of a first lens array, a condenser lens of a second lens array, and a light source in a stereoscopic display device according to an embodiment of the disclosure.

41 is a cross-sectional view schematically showing the arrangement of a display unit, a diffusion sheet, a lens sheet of a first lens array, a condenser lens of a second lens array, and a light source in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 42 is a diagram showing a light-collecting pattern on a surface of a diffusion sheet in a stereoscopic display device according to an embodiment of the disclosure.

43 is a plan view showing the arrangement of condenser lenses and light sources of a second lens array in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 44 is a plan view showing the arrangement of lens sheets of a first lens array in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 45 is a graph showing contrast in a stereoscopic display device according to an embodiment of the disclosure, wherein the horizontal axis represents spatial frequency and the vertical axis represents contrast.

FIG. 46 is a cross-sectional view showing a light source control unit in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 47 is a plan view showing a honeycomb lens array as a third lens array in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 48 is a diagram showing a two-layer lens sheet as a third lens array in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 49 is a cross-sectional view showing a light source control unit in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 50 is a cross-sectional view showing a light source control unit in a stereoscopic display device according to an embodiment of the disclosure.

51 is a graph showing the relationship between the position of the cap lens of the third lens array and the amount of light in a stereoscopic display device according to an embodiment of the disclosure, wherein the horizontal axis represents the position of the cap lens and the vertical axis represents the amount of light.

FIG. 52 is a diagram showing the relationship between the distance between light sources and the cap lens in a stereoscopic display device according to an embodiment of the disclosure.

FIG. 53 is a diagram showing the structure of a stereoscopic display device according to an embodiment of the disclosure.

Throughout the drawings, like reference numerals will be understood to refer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. Various specific details are included herein to assist understanding, but these details should be considered as exemplary only. Therefore, one of ordinary skill will recognize that various changes and modifications may be made to the various embodiments described in the present disclosure without departing from the scope and concept of the present disclosure. In addition, descriptions of well-known functions and configurations may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for the purpose of explanation only and is not intended to limit the present disclosure as defined by the appended claims and their equivalents.

It will be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to more than one of such surface.

Throughout the disclosure, the expression "at least one of A, B, or C" means only A, only B, only C, both A and B, both A and C, both B and C, all of A, B, C, or variations thereof.

<Preliminary Examination of Inventors>

A technology for displaying a stereoscopic image (hereinafter referred to as "stereoscopic display technology") has been proposed in the past. Stereoscopic display technology can be classified into a method using glasses and a method not using glasses.

As is known to all, the method of using glasses has problems such as the inconvenience of wearing the glasses or distortion depending on the viewing position.

The method of not using glasses includes a horizontal parallax method and a method that can obtain both horizontal and vertical parallax. The above-mentioned patent document 1 discloses a technology that transmits the light of the backlight source to the left and right eyes in a time-division manner by switching the shutter of the backlight optical system that combines a shutter, a prism, and a lenticular sheet. According to this, a high-definition three-dimensional display without using glasses is realized. However, there is a problem that the efficiency of light is reduced due to the use of a shutter and a problem that natural motion parallax cannot be obtained in a wide range.

Here, with reference to FIG. 1 to FIG. 6 , specific technical issues of a stereoscopic display device that realizes three-dimensional display without glasses will be described.

In the following description, the direction perpendicular to the main surface of the display unit of the stereoscopic image display device (depth direction) is referred to as the Z-axis direction, the left-right direction of the screen which is the direction parallel to the main surface of the display unit is referred to as the X-axis direction, and the up-and-down direction of the screen which is the direction parallel to the main surface of the display unit (also called the vertical scanning direction) is referred to as the Y-axis direction.

FIG. 1 to FIG. 3 are diagrams for explaining the display principle of a related stereoscopic display device according to an embodiment of the disclosure. FIG. 4 is a diagram for explaining the field of view of a related stereoscopic display device according to an embodiment of the disclosure. FIG. 5 is a diagram showing the relationship between the depth and the limit spatial frequency of a related stereoscopic display device according to an embodiment of the disclosure. FIG. 6 is a diagram for explaining the viewing angle and the distance between lens pixels of a related stereoscopic display device according to an embodiment of the disclosure.

1 to 6 , the stereoscopic display device 100 is a light reproduction type stereoscopic display device. For example, the stereoscopic display device 100 is a naked eye 3D display such as an integrated photography display or a light field display. Specifically, the stereoscopic display device 100 generates binocular parallax of the user or motion parallax generated when the user moves the viewpoint by displaying a multi-viewpoint image group, so that the user perceives a stereoscopic image. The stereoscopic display device 100 includes a display unit 10, a lens array 200, and a light source 300.

The lens array 200 is composed of a plurality of lens elements 201 arranged in an array. The lens element 201 is also called an exit pupil and controls the exit direction of light of the elemental image displayed on the display unit 10. An elemental image may represent two images containing different image information for each eye. For example, the two different images may reproduce a stereoscopic effect when the two eyes view from different viewpoints.

The display unit 10 is a liquid crystal display (LCD), an organic light emitting diode (OLED), etc., and its display area is in the shape of a quadrilateral and has a plurality of pixels 11 (display pixels). For example, the display unit 10 includes pixels 11A, 11B, and 11C. Referring to FIG. 1 , in the related stereoscopic display device 100, by arranging a lens element 201 on the pixel 11, the light from the pixel 11 has directionality. For example, in the case where the distance between the pixel 11 and the principal point of the lens element 201 is the focal length of the lens element 201, the light from the pixel 11 is emitted as parallel light through the lens element 201.

In one example of FIG. 1 , below the lens element 201-1, light from the pixel 11A located in the center is emitted upward as indicated by the solid line. Light from the pixel 11B located on the right is emitted toward the upper left as indicated by the dotted line. In addition, light from the pixel 11C located on the left is emitted toward the upper right as indicated by the dotted line. In this way, light from the pixels 11 below the lens element 201 can be presented as light in predetermined directions, respectively.

Referring to FIG. 1 , since the light from the pixel 11 has directionality, referring to FIG. 2 , each pixel 11 can represent a point having a depth of one point as a collection of light rays. For example, point PA is a point where light from the pixel 11A under each lens element 201 is gathered. Point PB is a point where light from the pixel 11B under each lens element 201 is gathered. Here, the pixel 11A under each lens element 201 corresponds to the same position as the object being photographed, and the position is reproduced at point PA. Similarly, the pixel 11B under each lens element 201 corresponds to the same position as the object being photographed, and the position is reproduced at point PB. In this way, the stereoscopic display device 100 represents a point having a three-dimensional depth as light gathered at a certain point in space.

Here, the number of pixels 11 under each lens element 201 is limited. In the example shown in FIG. 3 , for the sake of explanation, it is assumed that there are three pixels 11A, 11B, and 11C under each lens element 201. For example, there are three pixels 11A-1, 11B-1, and 11C-1 under the lens element 201-1. And, in the adjacent lens element 201, the light is represented by the pixel 11 under the adjacent lens element 201. Therefore, in one lens element 201-1, the light is represented within the range of the element image directly under the lens element 201-1. For example, the range of points that can be represented by the lens element 201-1 is the angle range (viewing angle θ) determined by the principal point PC of the lens element 201-1 and the width of the element image. For the outside of the viewing angle θ, the light generated by the element image under the adjacent lens element 201 is represented. Therefore, it is impossible to represent the expected stereoscopic image. Therefore, the overlapping range of the display range displayed from the element image through the lens element 201 becomes the observable range (field of view).

In the example of FIG4 , the shaded area Vr represents the visual field corresponding to the portion overlapping the display range from the end to the end of the screen of the display unit 10. By designing the viewing angles at both ends of the screen to be slightly toward the inside, it is indicated that the light from both ends can be observed in the shaded area. The viewing angle within the screen changes continuously within the screen, and all the light within the screen can be observed in the area where the light from both ends intersects, so this area Vr becomes the display range.

Next, the relationship between the depth amount and the spatial frequency of the stereoscopic image displayed by the stereoscopic display device 100 will be described with reference to FIGS. 5 and 6 .

5 , the three-dimensional image displayed by the stereoscopic display device 100 has the following property: the farther the position where the pixels constituting the three-dimensional image are displayed is from the display unit 10, the coarser the spatial frequency that can be displayed is. This is because the pixels constituting the element image have a width. Here, when the width of the pixel is set to P _p , the distance between the lens element 201 and the pixel displayed in the display unit 10 (hereinafter referred to as the "distance between lens pixels") is set to g, and the spatial frequency is set to v (cycle/mm), the displayed limit depth amount (D _L ) can be expressed by the following formula (1).

[Formula 1]

However, a three-dimensional image cannot be displayed at a spatial frequency finer than the lens width of the lens element 201 of the lens array 200. Therefore, in the portion close to the display unit 10, the spatial frequency of the displayed three-dimensional image is a spatial frequency determined by the lens width of the lens element 201. If it is desired to display a three-dimensional image at a spatial frequency finer than that at a depth away from the display unit 10 (a depth where the spatial frequency is not limited by the lens width), the distance g between the lens pixels can be increased.

Here, referring to FIG. 6 , the relationship between the element image width _Ep , the viewing angle θ, and the distance g between the lens pixels can be expressed by the following equation (2).

[Formula 2]

As can be seen from equation (2), when the element image width _Ep is the same, if the distance g between lens pixels increases, the viewing angle θ becomes narrower. In addition, if the element image width _Ep becomes wider, the lens width also becomes wider, and the spatial frequency (v) becomes rougher. For example, the depth amount ( _DL ), the viewing angle θ, and the maximum spatial frequency (v) are in a balanced relationship. Therefore, in a light reproduction type stereoscopic device with motion parallax in a wide range, it is required to achieve a clear three-dimensional display rather than a stagnant resolution.

In addition, similar to Patent Document 1, the above-mentioned Non-Patent Document 1 discloses a technology for realizing three-dimensional display without glasses by using time division. In the technology described in Non-Patent Document 1, the display range in multiple parallax directions can be expanded by using a backlight of a cylindrical lens that switches multiple light sources by time division and a lens sheet on the front of an LCD. However, there is a problem that the resolution of the displayed field is reduced to 1/the number of parallaxes.

At least one of the following embodiments can solve the above technical problem.

<First Embodiment>

First, the first embodiment is described. The stereoscopic display device of this embodiment includes a cylindrical lens array and a lens sheet on the back of the display unit, so that a plurality of light sources are switched by time division. Thus, the display range of a plurality of parallax directions can be expanded. In addition, the stereoscopic display device of this embodiment can also adopt a high-definition display method that expands the light emitting range of the light source in addition to the parallax display method. In addition, the stereoscopic display device of this embodiment makes the illumination form different for each area (area) or each field of the display unit, and optimizes the display content for each area or each field, so as to appropriately display a more vivid three-dimensional image while ensuring the depth. Figure 7 is a diagram for illustrating the observation method in two display methods according to an embodiment disclosed.

(Observation method of parallax display)

7 , in the parallax display method, the stereoscopic display device 1 displays a stereoscopic image 92. As described above, in the parallax display method, the field of view is limited. Users 96 and 97 observe the stereoscopic image 92 displayed on the stereoscopic display device 1 in a comfortable posture within the field of view.

The stereoscopic image 92 is formed by a collection of light rays from the stereoscopic display device 1. Humans recognize depth by binocular parallax (i.e., the difference between the retinal images of the left eye and the right eye) generated when viewing an object with both eyes. In addition, depth is also recognized by motion parallax (i.e., the change in the retinal image caused by the relative motion of the viewer and the object). Thus, the users 96 and 97 can view the stereoscopic image 92.

When users 96 and 97 move their heads left and right within the field of view, they can observe different stereoscopic images 92 at each position. In FIG. 1 , users 96 and 97 are shown on the left and right. Since users 96 and 97 observe stereoscopic images 92 from different directions, they can observe different stereoscopic images 92. For example, when an apple is displayed as a stereoscopic image 92, user 96 can observe the right side, and user 97 can observe the left side.

Here, the angle at which the users 96 and 97 observe the stereoscopic image 92 is referred to as the "observation angle". The observation angle is the angle formed by the Z-axis direction and the direction in which the users 96 and 97 observe (wherein the absolute value is 90° or less). With the stereoscopic image 92 as a reference, the observation angle of a user (not shown) in the positive direction of the Z-axis is 0°, the observation angle _θa of the user 96 is -45°, and the observation angle _θb of the user 97 is 45°.

The direction in which the users 96 and 97 observe the stereoscopic image 92 is opposite to the direction in which the stereoscopic image 92 is displayed relative to the users 96 and 97 (the display direction of the stereoscopic image 92), so the observation angle is also called the "display angle". The display angle is the angle formed by the Z-axis direction and the display direction of the stereoscopic image 92 (wherein the absolute value is less than 90 degrees).

In addition, according to the first embodiment, the stereoscopic display device 1 displays element images of the depth area in time division (field division) according to the display angle range to express the depth of a scene of the stereoscopic image 92. As an example, the stereoscopic display device 1 divides the fields F1, F2, and F3 into three and displays them. Field F1 is a field that displays a stereoscopic image 92 with a display angle range of -30° to 30°. Field F2 is a field that displays a stereoscopic image 92 with a display angle range of -60° to -30°. Field F3 is a field that displays a stereoscopic image 92 with a display angle range of 30° to 60°. By repeating the three fields at a high speed, users 96 and 97 whose viewing angles are in the range of -60° to 60° can observe the stereoscopic image 92.

The display direction corresponding to the central display angle of the allocated display angle range is referred to as the main display direction. When the display angle range is -30° to 30°, the main display direction is the display direction with a display angle of 0°. When the display angle range is -60° to -30°, the main display direction is the display direction with a display angle of -45°. When the display angle range is 30° to 60°, the main display direction is the display direction with a display angle of 45°.

(Observation method using high-definition display)

In the high-definition display mode, the stereoscopic display device 1 displays the two-dimensional image 94 in the +Z axis direction. Furthermore, the users 96 and 97 recognize the two-dimensional image 94 displayed on the stereoscopic display device 1 as a two-dimensional image. Therefore, the observed two-dimensional image 94 is uniform regardless of the viewing angle.

The first embodiment is characterized in that the stereoscopic display device 1 divides the light emission of the light source into areas, and can select whether to use a parallax display mode or a high-definition display mode in each area. In this way, the method of making the display mode different in each area is called "area division", and the method of implementing display driving and light source driving in a manner corresponding to the area is called "area control".

The stereoscopic display device 1 displays a stereoscopic image 92 for an area where a parallax display method is applied. An area where a parallax display method is applied is also referred to as a depth area. In addition, the stereoscopic display device 1 displays a two-dimensional image 94 for an area where a high-definition display method is applied. An area where a high-definition display method is applied is also referred to as a high-definition area. In the following, the stereoscopic image 92 and the two-dimensional image 94 may also be collectively referred to as a display image.

Next, the structure of the stereoscopic display device 1 that realizes the above two display modes in one device is described with reference to Figures 8 and 9. Figures 8 and 9 are schematic cross-sectional views of the stereoscopic display device 1 according to the first embodiment.

FIG. 8 is a schematic cross-sectional view of a stereoscopic display device according to an embodiment of the disclosure.

8 , there is shown a stereoscopic display device 1 when a parallax display method is applied. The stereoscopic display device 1 further includes a light source control unit 15 in addition to the display unit 10 described above.

When the parallax display method is applied, the display unit 10 displays a plurality of first images that allow the user to recognize the depth component (stereoscopic image 92) of the display image. The first image is a two-dimensional element image synthesized by combining images corresponding to the display angle range of the field corresponding to the first image in the multi-viewpoint image. In the displayed first image, the display direction of the corresponding display image is different depending on the field. The multi-viewpoint image is an image in which a subject is photographed from a plurality of different viewpoints, and includes an image generated by computer graphics (CG).

The light source control unit 15 is a component that controls the emission direction of light and includes a lens sheet 40 , a cylindrical lens array 30 , and a plurality of light source units 50 .

The lens sheet 40 is also referred to as a first lens array. The lens sheet 40 is arranged on the back side of the display unit 10. The lens sheet 40 includes a plurality of first lens elements 41 arranged at a predetermined pitch. The first lens element 41 is an exit pupil, which is also referred to as a first cylindrical lens. The first lens element 41 has a semi-cylindrical shape with a surface parallel to the generatrix cutting the circumference. In the first embodiment, the first lens element 41 is arranged so that the extension direction of the ridge line (i.e., the axial direction of the semi-cylinder) is approximately parallel to the Y-axis direction.

The cylindrical lens array 30 is also referred to as a second lens array. The cylindrical lens array 30 is arranged on the back side of the lens sheet 40.

The cylindrical lens array 30 includes a plurality of second lens elements 31 arranged at a pitch wider than the pitch of the first lens elements 41 included in the lens sheet 40. In other words, the first lens elements 41 are densely arranged, while the second lens elements 31 are relatively sparsely arranged. The second lens element 31 is an exit pupil, which is also referred to as a second cylindrical lens. The second lens element 31 serves as a collimator that converts incident light into parallel light. The second lens element 31 shown in FIG. 8 is a Fresnel lens in which a plurality of fine serrations are formed at both ends in the X-axis direction of the semi-cylindrical surface, but it may also be without the serrations. In the case of using a Fresnel lens, the thickness of the lens can be made thinner.

Each of the plurality of light source units 50 is arranged on the back side of each second lens element 31 included in the cylindrical lens array 30. Each light source unit 50 has a plurality of line light sources 51 and a light shielding wall 52 provided corresponding to each line light source 51. For example, the plurality of line light sources 51 include line light sources 51A, 51B, 51C. The light shielding wall 52 includes light shielding walls 52A, 52B, 52C corresponding to each line light source 51A, 51B, 51C. Each line light source 51A, 51B, 51C includes light sources 51A-1, 51B-1, 51C-1, and each light shielding wall includes light shielding walls 52A-1, 52B-1, 52C-1.

The line light source 51 is also referred to as a single light source. For example, the line light source 51 is an LED. The line light source 51 extends along the vertical direction (i.e., the Y-axis direction) in which the pixels 11 of the display unit 10 are arranged. The line light sources 51 included in one light source unit 50 are respectively equipped corresponding to different angular ranges of display directions (display angle ranges). Specifically, in one light source unit 50, each line light source 51 is arranged at predetermined intervals in the horizontal direction (i.e., the X-axis direction) in which the pixels 11 of the display unit 10 are arranged. When observed in cross section, each line light source 51 is arranged on a concentric circle centered on the principal point PF of the second lens element 31 and spaced from the principal point PF of the second lens element 31 by a distance equivalent to the focal length df. Due to this arrangement, it is difficult to be affected by spherical aberration.

As an example, the stereoscopic display device 1 lights up one linear light source 51 in each field among the linear light sources 51 included in each light source unit 50. As shown in the figure, the light emitted from the linear light source 51A-1 is converted to be parallel to the +Z axis direction by the second lens element 31-1 of the cylindrical lens array 30. The collimated light is gathered to the point PD-1 by the first lens element 41-1 included in the lens sheet 40. Then, the light gathered at the point PD-1 is diffused toward the +Z axis direction to illuminate the display unit 10 arranged in the +Z axis direction relative to the point PD-1. The same is true for the linear light sources 51B-1 and 51C-1.

Therefore, point PD plays the same role as point PC which is the principal point of lens element 201 of Fig. 8. Furthermore, point PD can also be regarded as a virtual light source.

Here, the display unit 10 may be arranged at a position spaced apart from the lens sheet 40 by 2 times the focal length of the lens sheet 40. Here, about 2 times may be 2 times, or may be 1.9 times or more and 2.1 times or less. In such an arrangement, different pixels 11 are illuminated according to the direction observed from the relationship between the collected light and the pixels 11. For example, the pixels 11 have directionality.

In the case where the first image is illuminated by one linear light source 51 , the stereoscopic display device 1 can display with a resolution depending on the pitch of the first lens elements 41 of the lens sheet 40 .

Generally, when the width of the LED serving as the light source is greater than the width of the pixel 11 and is collimated, there is a tendency for the diffusion of light to become larger. Therefore, by sparsely arranging the pitch of the second lens elements 31 of the cylindrical lens array 30 to increase the focal length, the diffusion of light can be relatively narrowed. Thus, the width of the point PD focused by the first lens element 41 of the lens sheet 40 can be reduced. As a result, the crosstalk of the displayed image can be reduced.

FIG. 9 shows a stereoscopic display device in which a high-definition display method is applied according to an embodiment of the disclosure.

9 , in FIG. 9 , the arrangement of components of the stereoscopic display device 1 is the same as that of FIG. 8 , but the type of image displayed on the display unit 10 , the lighting form of the light source, and the traveling state of light are different from those of FIG. 8 .

When the high-definition display method is applied, the display unit 10 of the stereoscopic display device 1 displays at least one second image that allows the user to recognize the planar component (two-dimensional image 94) of the stereoscopic image 92. The second image is a two-dimensional image.

The stereoscopic display device 1 lights up a wide-width light source included in one light source unit 50 in a high-definition display mode. The wide-width light source has a wider light emission width than a single light source. In the first embodiment, the stereoscopic display device 1 increases the number of line light sources 51 that are lit in the line light sources 51 included in one light source unit 50 compared to the number of line light sources 51 that are lit in a parallax display mode. As an example, the stereoscopic display device 1 lights up three line light sources 51A, 51B, and 51C in the line light sources 51 included in each light source unit 50. Accordingly, the plurality of line light sources 51 play the role of a surface light source that illuminates a wider range. In the case of irradiation with a surface light source, on the focal plane F of the second lens element 31 of the cylindrical lens array 30, light will not be focused at one point, but will be illuminated in a wider range. Therefore, since all pixels 11 are uniformly illuminated, all pixels 11 can be observed from any viewing direction. In this case, the stereoscopic display device 1 can display the second image at the display resolution of the display unit 10. When each light source unit 50 of the stereoscopic display device 1 includes a surface light source different from the line light source 51 , the stereoscopic display device 1 can light up the corresponding surface light source as a wide-width light source in the high-definition display mode.

The stereoscopic display device 1 can combine the above two lighting methods according to regions, thereby displaying high-definition images with depth.

FIG. 10 is a cross-sectional view of a second lens element and a light source unit in a corresponding relationship in a stereoscopic display device according to an embodiment of the disclosure.

10 , the second lens element 31 and the light source unit 50 in a corresponding relationship constitute a system enclosed by the light shielding wall 52 .

The light shielding wall 52 of the light source unit 50 is made of a light shielding material and blocks the incidence of light from the outside. The light shielding wall 52 of the light source unit 50 also serves as a bracket for supporting the plurality of line light sources 51. The light shielding wall 52 supports the line light sources 51 in such a way that the optical axes of the line light sources 51 face the corresponding main display direction.

When observed in section, the light shielding wall 52A is arranged along the X-axis direction. The light shielding wall 52A supports a line light source 51A with a display angle of 0° in the main display direction. The end of the light shielding wall 52A in the +X-axis direction is connected to the light shielding wall 52B, and the end of the light shielding wall 52A in the -X-axis direction is connected to the light shielding wall 52C. When observed in section, the light shielding wall 52B is arranged to be inclined 45° from the X-axis direction. The light shielding wall 52B supports the line light source 51B with a display angle of -45° in the main display direction. When observed in section, the light shielding wall 52C is arranged to be inclined -45° from the X-axis direction. The light shielding wall 52C supports the line light source 51C with a display angle of 45° in the main display direction.

FIG. 11 is a bird's-eye view of a light source unit 50 according to an embodiment of the disclosure.

11 , a plurality of light source units 50 are connected along the X-axis direction similarly to the second lens element 31. The distance between the line light sources 51A in adjacent light source units 50 is the same as the pitch of the second lens element 31 included in the cylindrical lens array 30. The same is true for the distance between the line light sources 51B and the distance between the line light sources 51C.

The end of the light shielding wall 52B in the +X axis direction is connected to the light shielding wall 52C of the adjacent light source unit 50. The end of the light shielding wall 52C in the -X axis direction is connected to the light shielding wall 52B of the adjacent light source unit 50. The connected light shielding wall 52B and the light shielding wall 52C are closer to each other in the X axis direction as they move toward the + axis direction.

For example, the light shielding walls 52B and 52C are arranged between the line light source 51A of the own light source unit 50 and the line light source 51A of the adjacent light source unit 50, and are configured to block the light from the adjacent light source unit 50 from being incident on the corresponding cylindrical lens array 30. Thus, the emission of light at non-corresponding angles generated by the light of the non-corresponding light source unit 50 can be prevented. Usually, in the case where the so-called repeated three-dimensional image is formed due to the emission of light at non-corresponding angles, when parallel light is incident at corresponding angles by multiple light source units 50, it will become an obstacle. However, in the case of having the above-mentioned structure, the formation of repeated three-dimensional images can be prevented.

In addition, each of the plurality of light source units 50 includes light source blocks BL1, BL2, ..., BLn arranged along the Y-axis direction of the display unit 10. Specifically, the light source blocks BL included in each light source unit 50 are connected to each other along the Y-axis direction. More specifically, the ends of the light shielding walls 52A, 52B, 52C included in the light source block BL1 in the positive direction of the Y-axis are respectively connected to the ends of the light shielding walls 52A, 52B, 52C included in the light source block BL2 in the negative direction of the Y-axis.

FIG. 12 is a diagram illustrating zone control according to an embodiment of the disclosure.

12 , the stereoscopic display device 1 divides the display unit 10 into a depth region AR1 and a high-definition region AR2 , and displays an image according to the type of region, and drives a light source according to the type of region for illumination.

Specifically, in the depth area AR1, the display unit 10 of the stereoscopic display device 1 displays the first image corresponding to the current field. Also, in the depth area AR1, the light source unit 50 of the stereoscopic display device 1 lights up the line light source 51 corresponding to the current field among the three line light sources 51. In addition, the light source unit 50 includes light sources 51A-1, 51A-2, 51A-3, 51A-4, 51B-1, 51B-2, 51B-3, 51B-4, 51C-1, 51-C2, 51C-3, and 51C-4.

In the high-definition area AR2, the display unit 10 of the stereoscopic display device 1 displays a predetermined second image regardless of the field. Also, in the high-definition area AR2, the light source unit 50 of the stereoscopic display device 1 turns on all three line light sources 51.

FIG. 13 is a diagram for explaining field control of light source driving in the depth area AR1 according to an embodiment of the disclosure.

13, in the field F1, the light emitted from the line light source 51A provided on the back side of the second lens element 31 of the cylindrical lens array 30 becomes parallel light facing (directly facing) the front side of the second lens element 31 of the cylindrical lens array 30. And the parallel light is collected by the first lens element 41 of the lens sheet 40. The light is illuminated to the display unit 10 as light within the display angle range determined by the focal length of the first lens element 41, the pitch of the first lens element 41 and the angle of the parallel light for illumination. For example, the stereoscopic display device 1 can reproduce the light rays representing the stereoscopic image 92 within the display angle range.

Here, for example, the display angle range of the field F1 is set to a range of ±30°=60°. In this case, in the field F2, the line light source 51B is lit at a distance of the focal length _df relative to the second lens element 31 of the cylindrical lens array 30. At this time, the light parallelized by the second lens element 31 has an angle of 45° and is incident on the first lens element 41 of the lens sheet 40. And, the light is illuminated to the display unit 10 as light in the display angle range of -30° to -60°. Therefore, in this case, the stereoscopic display device 1 can reproduce light in the display angle range of -30° to -60°.

In addition, when the line light source 51C is turned on in the field F3, based on the same principle as the field F2, the stereoscopic display device 1 can reproduce light in the display angle range of 30° to 60°. When the display images are synchronized and repeatedly displayed in these three different fields, the stereoscopic display device 1 becomes a display that reproduces an angle range of 120° from -60° to 60°. Here, the angle of 120° is called the viewing angle.

FIG. 14 is a graph showing the relationship between the viewing angle θ and the lens pitch _pi of the first lens element according to an embodiment of the disclosure.

14 , when the field of view is enlarged to N (N is a natural number) fields in order to obtain a viewing angle θ, the focal length of the first lens element 41 of the lens sheet 40 is expressed by the following equation.

[Formula 3]

For example, for the case of three fields, the angular range θ _c of the first lens element 41 at the center is expressed by the following equation.

[Formula 4]

In addition, the angle range _θr of the first lens element 41 on the right side is expressed by the following equation.

[Formula 5]

The angle range θ _l of the first lens element 41 on the left side is also the same as θ _r .

In displays that expand the display angle range by field division, synchronization with the displayed image plays an important role.

FIG. 15 is a block diagram showing a functional structure of a stereoscopic display device 1 according to an embodiment of the disclosure.

14 , the stereoscopic display device 1 includes a display image generating section 16 , a display driving section 17 , and a light source driving section 19 in addition to the light source control section 15 and the display section 10 .

The display image generation section 16 generates a first image and a second image based on the multi-viewpoint images. The display image generation section 16 supplies the generated images to the display drive section 17. For example, the display image generation section 16 is an image reproduction device.

The display driving unit 17 inputs the first image corresponding to the parallax display mode and the second image corresponding to the high-definition display mode to the display unit 10 through area division and displays them. In addition, the display driving unit 17 switches the first image corresponding to each display angle range through field cutting for the area where the first image is displayed, and displays it on the display unit 10.

The light source driving part 19 drives the plurality of light source units 50 by area control so that the number of line light sources 51 included in each light source unit 50 for illuminating the second image is greater than the number of line light sources for illuminating the first image. For example, the light source driving part 19 is an LED lighting circuit.

Here, the angle range corresponding to the first image input to the display unit 10 needs to be consistent with the angle range corresponding to the lit linear light source 51. In order to achieve the consistency of the angle ranges, the display drive unit 17 includes a synchronization unit 18.

The synchronization unit 18 is a synchronization circuit. The synchronization unit 18 detects changes in the image display and supplies a synchronization signal to the light source driving unit 19. In addition, in the parallax display mode, the light source driving unit 19 sends a field signal for driving the line light source 51 corresponding to the display angle range of each field to the light source unit 50. Thus, the light source driving unit 19 can light up the line light source 51 corresponding to the display angle range corresponding to the first image after the switching of the field. Therefore, the first image displayed on the display unit 10 is synchronized with the light source unit 50, so that the display angle range can be expanded.

16 and 17 are diagrams showing an example of a timing chart of light source driving and display driving according to various disclosed embodiments.

Generally, in an LCD, the screen switching timing is staggered at each scanning position from the top to the bottom of the screen (in the first embodiment, from the end to the negative end of the Y axis of the display unit 10). The display drive unit 17 switches the first image displayed on the display unit 10 to the first image corresponding to the field in this vertical scanning cycle. In addition, the light source drive unit 19 switches the lit line light source 51 to the line light source 51 corresponding to the field in the vertical scanning cycle.

16, as an example, the light source driving unit 19 evenly lights the light source blocks BL included in the line light source 51 corresponding to the field regardless of the positions of the light source blocks BL arranged in the Y-axis direction. In the figure, the portion with diagonal lines indicates the time when the light source blocks BL are not lit, and the portion without diagonal lines indicates the time when the light source blocks BL are lit. In this case, as the lighting time increases, the driving timings of the upper and lower ends of the screen are misaligned, thereby causing crosstalk CT.

17 , the synchronization unit 18 synchronizes the position of the vertical scan performed by the display driving unit 17 with the vertical position of the light source block BL lit or extinguished by the light source driving unit 19. Specifically, the light source driving unit 19 turns on the lighting of the line light source 51 corresponding to the next field at the timing of the field switching indicated by the synchronization signal, and sequentially lights the light source blocks BL included in the line light source 51 in the vertical scanning direction based on the synchronization signal. In addition, the light source driving unit 19 sequentially extinguishes the light source blocks BL included in the line light source 51 in the previous field lighting in the vertical scanning direction based on the synchronization signal. Accordingly, even if the lighting time is increased, crosstalk is unlikely to occur.

Fig. 18 is a diagram for explaining a method of generating a first image from multi-viewpoint images according to an embodiment of the disclosure. In the following description, for the sake of clarity, the horizontal direction is described.

Referring to Figure 18, the left side of Figure 18 shows a method for shooting a multi-viewpoint image. The multi-viewpoint image is generated by shooting an object 90 using a number of cameras 60 corresponding to the number of pixels corresponding to the element image width (first image width). For example, when the first image width is equivalent to a length of 11 pixels, multi-viewpoint images in 11 directions are required. Therefore, multi-viewpoint images in 11 directions are captured by shooting the object 90 from 11 directions using cameras 60A~60K that shoot in 11 directions. Similarly, not only in real shooting, but also in computer graphics CG, the same number of cameras 60 as the number of pixels corresponding to the first image width is required.

The right side of FIG. 18 shows a state in which a stereoscopic image V is reproduced by multi-viewpoint images. First, the display image generation unit 16 generates a plurality of first images by rearranging the pixels having directionality of the multi-viewpoint image group. Specifically, the display image generation unit 16 samples the pixels included in the multi-viewpoint image group corresponding to the position of each first lens element 41 of the lens sheet 40, thereby generating a first image. For example, the display image generation unit 16 generates a first image synthesized from a multi-viewpoint image corresponding to -30° to -60°, a first image synthesized from a multi-viewpoint image corresponding to -30° to 30°, and a first image synthesized from a multi-viewpoint image corresponding to 30° to 60°. And, the display unit 10 driven by the display driving unit 17 displays the three kinds of first images in three fields in sequence. And, if the first image E is irradiated during the display period, the light beams 9A to 9K corresponding to the cameras 60A to 60K are emitted from the first image E. Accordingly, the stereoscopic image V is reproduced.

Then, the display driving unit 17 sequentially displays the three first images in three fields on the display unit 10. At this time, the light source driving unit 19 can synchronize the switching of the display by lighting the line light source 51 corresponding to the display angle range of the first image being displayed.

FIG. 19 is a diagram for explaining a region segmentation method according to an embodiment of the disclosure.

19 , if the number of illuminated line light sources 51 of light source unit 50 is increased to expand the illumination range, high-definition display without parallax can be achieved. Display image generation unit 16 divides the display image into a high-definition area and a depth area according to the depth of the display image.

The area is optimized using the depth of the display image. In CG, it is relatively easy to output a depth map. Therefore, the display image generation unit 16 can easily designate an area with a shallow depth relative to the reference plane of the display image (near the display unit 10) as a high-definition area based on the information of the depth map. For example, the display image generation unit 16 can set an image area included in the multi-view image and having a parallax below a predetermined threshold as a high-definition area. In addition, for example, the display image generation unit 16 can also set an image area included in the multi-view image and having a parallax greater than a predetermined threshold as a depth area.

The display image generation unit 16 generates an image obtained by photographing the object from a predetermined viewpoint as a second image for the high-definition region. For example, the predetermined viewpoint is the front. The display image generation unit 16 generates a first image for the depth region using the method described with reference to FIG. 18 .

Furthermore, the light source driving section 19 controls the light source unit 50 based on the area division, so that the high-definition area can be displayed with high definition using all the pixels 11 of the display section 10, and the depth can be expressed in the depth area. The user can perceive that this is a high-definition display with depth.

When creating display data, the display image generation unit 16 may arrange a high-definition display near the reference plane, and may also consider specifying the depth of the high-definition image as the reference plane by analyzing continuous frames.

According to the first embodiment, the stereoscopic display device 1 can utilize a simple structure combining two lens arrays to display the parallax display mode and the high-definition display mode by area division. Thus, the problem of resolution reduction caused by the parallax display mode can be reduced. Therefore, a clearer three-dimensional image can be appropriately displayed while ensuring depth.

The first embodiment can be modified as follows.

<First Modification of the First Embodiment>

FIG. 20 is a diagram showing the arrangement of a cylindrical lens array and a lens sheet according to an embodiment of the disclosure.

20 , basically, the cylindrical lens array 30, the line light source 51, and the lens sheet 40 may also be arranged in a direction perpendicular to the screen of the display unit 10, thereby providing parallax in the horizontal direction. However, if the ridge line of the lens sheet 40 is arranged in the vertical direction, Moire fringes are generated while interfering with the pattern of pixels. The ridge line of the lens sheet 40 is a line parallel to the axis of the semi-cylindrical shape of the first lens element 41.

Therefore, referring to Fig. 20, the stereoscopic display device 1a of this modified example makes the lens sheet 40 slightly tilted relative to the vertical direction to eliminate moiré fringes. Specifically, the ridge line of the cylindrical lens array 30 can be along the vertical direction in which the pixels 11 of the display unit 10 are arranged, and the ridge line of the lens sheet 40 can be tilted at a predetermined angle φ relative to the vertical direction.

Furthermore, the stereoscopic display device 1 a can distribute parallax based on the tilt angle of the lens sheet 40 and the positional relationship of the pixels 11 in the vertical direction.

FIG. 21 is a diagram showing an arrangement of a first lens element and a first image of a lens sheet according to an embodiment of the disclosure.

Referring to FIG. 21 , a pixel 11 has three sub-pixels of RGB. Since each sub-pixel is observed in a different direction, the stereoscopic display device 1 can also allocate parallax to each sub-pixel. In addition, since the ridge line of the cylindrical lens array 30 and the ridge line of the lens sheet 40 are also misaligned relative to the Y-axis direction, so that the light is emitted in different directions, the stereoscopic display device 1a can also allocate parallax for this. In this figure, as an example, the lens sheet 40 having a width of 9 pixels is arranged by tilting tan1/4 in the X-axis direction. Thus, parallax in 36 directions can be allocated. Strictly speaking, the same display direction is allocated to the RGB included in a pixel 11, but it will be offset in the display direction according to the pixel position. Therefore, parallax in 108 directions is actually allocated. The display image generation unit 16 uses 36 multi-viewpoint images to offset the multi-viewpoint images by 1/3 according to RGB, and synthesizes the interpolated images into the first image. Accordingly, 36 multi-viewpoint images can be used to perform more accurate display.

In addition, in the first modified example of the disclosed first embodiment, the stereoscopic display device 1 a may further include an anisotropic diffusion sheet in the light source control unit 15 .

FIG. 22 is a diagram showing the arrangement of an anisotropic diffuser according to an embodiment of the disclosure.

22 , the anisotropic diffusion sheet 80 is arranged on the XY plane between the lens sheet 40 and the display unit 10. Specifically, the anisotropic diffusion sheet 80 is arranged on the imaging surface of the lens sheet 40 (i.e., the position separated from the lens sheet 40 by the approximate focal length of the lens sheet 40 in the Z-axis direction). The approximate focal length may be the focal length, but may be a distance of more than 0.9 times and less than 1.1 times the focal length. In the direction parallel to the main surface of the anisotropic diffusion sheet 80, the anisotropic diffusion sheet 80 has a stronger effect of diffusing light in the ridge direction of the lens sheet 40 than in the direction orthogonal to the ridge of the lens sheet 40. Accordingly, the effect of the light-collecting distribution in the direction orthogonal to the ridge of the lens sheet 40 is reduced, making it difficult for the width in the direction orthogonal to the ridge in the light-collecting distribution to become wider. Therefore, the crosstalk of the displayed image can be reduced. In addition, since the crosstalk of the displayed image has no effect in the direction along the ridge of the lens sheet 40, the light can be actively diffused in the corresponding direction.

Here, in the cylindrical lens array 30, brightness unevenness (mura) is likely to occur around the lenses or on the lens joint surface. However, since the ridge line of the lens sheet 40 is inclined relative to the ridge line of the cylindrical lens array 30, the light is diffused in a direction that can be actively diffused, and thus the brightness unevenness generated around the lenses of the cylindrical lens array 30 or on the lens joint surface can be reduced.

<Second Embodiment>

Next, a stereoscopic display device according to the second embodiment is described. For example, Patent Document 2 discloses a technology that improves light efficiency and reduces crosstalk by combining an optical system of a lens and a diffusion sheet for each pixel, thereby enabling high-definition stereoscopic display without glasses. However, the technology of Patent Document 2 has a technical problem that the resolution of the display is reduced to 1/the number of parallaxes. In addition, the technology of Patent Document 2 is a method of covering the LCD with a lens, so there is a problem that natural motion parallax cannot be obtained in a wider range.

The stereoscopic display device of this embodiment includes a diffusion sheet, so that the display range is wider than the viewing angle of the lens sheet 40 .

FIG. 23 is a cross-sectional view schematically showing a stereoscopic display device according to an embodiment of the disclosure.

23, in the stereoscopic display device 2 of the present embodiment, the light source control unit 15a further includes a diffusion sheet 81. The diffusion sheet 81 is arranged between the display unit 10 and the lens sheet 40, and is arranged at a position including each focal position of each first lens element 41. Specifically, the diffusion sheet 81 is arranged on a plane including each focal position of each first lens element 41. The diffusion sheet 81 isotropically diffuses the transmitted light in the X-axis direction and the Y-axis direction. The diffusion sheet 81 is preferably thin.

Linear light sources 51A to 51C are arranged on the back side of each second lens element 31. For example, light emitted from the line light source 51A is converted into parallel light by each second lens element 31 of the cylindrical lens array 30. Light converted into parallel light by each second lens element 31 is collected by each first lens element 41 of the lens sheet 40. Light collected by each first lens element 41 is collected at each focal position where a diffuser sheet 81 is arranged. Thereafter, the light collected at each focal position travels in a manner in which the luminous flux (light beam) is diffused. A diffuser sheet 81 for diffusing light is arranged at a position including each focal position. Therefore, the diffused light transmitted through the diffuser sheet 81 can expand the luminous flux compared to a state in which there is no diffuser sheet 81. The diffused light transmitted through the diffuser sheet 81 is incident on the display unit 10.

FIG. 24 is a diagram showing the relationship between the diffusion sheet 81 and element pixels in the stereoscopic display device 2 according to an embodiment of the present invention.

24 , the angular range θ of the field of view can be expressed by the above-mentioned formula (2) by means of the distance g between the diffuser 81 and the display unit 10 and the element pixel width _Ep . The element pixel width _Ep is arranged at intervals substantially the same as the pitch q of each first lens element 41 of the lens sheet 40. The distance between the diffuser 81 and the display unit 10 is smaller than the distance between the diffuser 81 and the lens sheet 40. The light diffused from the diffuser 81 illuminates the display unit 10 in a manner that is widened to be larger than the element image width _Ep . By arranging in this way, different pixels are illuminated in a direction observed from the relationship between the collected light and the pixel. In other words, the pixel has directionality, thereby serving as a light reproduction type stereoscopic display device 2 as described above.

Generally, the range in which the lens sheet 40 can focus light is limited to about 45°. Therefore, the display angle range of the stereoscopic display device formed by the lens sheet 40 is limited to 45°. In contrast, the stereoscopic display device 2 of this embodiment includes a diffusion sheet 81. Therefore, the diffusion sheet 81 can be used to widen the light, thereby expanding the display range.

<Third Embodiment>

Next, a third embodiment is described. In this embodiment, a shielding plate is used.

FIG. 25 is a cross-sectional view schematically showing a shielding plate having slits in a stereoscopic display device according to an embodiment of the disclosure.

25, in the stereoscopic display device 3 of the present embodiment, the light source control unit 15b further includes a shielding plate 82. The shielding plate 82 is arranged on the surface of the lens sheet 40. A plurality of slits 83 are provided on the shielding plate 82. Each slit 83 is arranged in the central portion of each first lens element 41. Therefore, the shielding plate 82 shields the light that transmits the peripheral portion of each first lens element 41, and a plurality of slits 83 that transmit the central portion of each first lens element 41 are formed on the shielding plate 82.

In the case of focusing light to the lens sheet 40, due to the aberration of each first lens element 41, the light transmitted through the peripheral portion of each first lens element 41 is not concentrated at the focal position, but diffused to the periphery of the focal position of the diffusion sheet 81. If the periphery of the focal position is irradiated, pixels that do not correspond to the display direction will be irradiated. Therefore, such light transmitted through the peripheral portion of each first lens element 41 causes crosstalk of the stereoscopic image, resulting in deterioration of the quality of the stereoscopic display. Therefore, the shielding plate 82 equipped with the slit 83 is used to limit the light of the peripheral portion of each first lens element 41. Accordingly, the quality of the stereoscopic display can be improved by reducing the crosstalk.

In stereoscopic display using a general barrier, since there is no problem of focusing light, a narrow opening is used to reduce crosstalk. Therefore, the light efficiency of stereoscopic display using a barrier is very poor. In order to achieve a bright display, a light source such as a strong irradiation LED is required, which causes a problem of increased power consumption. In contrast, in the present embodiment, even if the shielding plate 82 is used, each first lens element 41 focuses light, so a focal point narrower than the opening width can be generated. Therefore, power consumption can be reduced by improving light efficiency.

<Fourth Embodiment>

Next, a fourth embodiment is described. This embodiment is an example in which the second lens elements 31 of the cylindrical lens array 30 are arranged in a zigzag arrangement.

Fig. 26 is a top view showing the arrangement of the second lens element of the cylindrical lens array in the stereoscopic display device according to one disclosed embodiment. Fig. 27 is a perspective view showing the arrangement of the second lens element of the cylindrical lens array in the stereoscopic display device according to one disclosed embodiment. Fig. 28 is a top view showing the cylindrical lens array in the stereoscopic display device according to one disclosed embodiment as viewed through a diffuser.

26 and 27, the light source control unit 15c of the present embodiment includes a cylindrical lens array 30, and the cylindrical lens array 30 includes a plurality of second lens elements 31 arranged in a zigzag pattern. For example, in the cylindrical lens array 30, the plurality of second lens elements 31 are arranged in a zigzag pattern in the X-axis direction and the Y-axis direction. For example, each second lens element 31 in a column in which the plurality of second lens elements 31 are arranged in the X-axis direction is staggered by half a pitch relative to each second lens element 31 in an adjacent column in the Y-axis direction.

When the cylindrical lens array 30 is observed from the +Z axis direction, the amount of light at the ridge portion of the second lens element 31 is different from the amount of light at the end portion. Therefore, the in-plane uniformity of the amount of light transmitted through the cylindrical lens array 30 is reduced. However, referring to FIG. 28 , by allowing the light to pass through the diffuser 81, the in-plane uniformity of the amount of light transmitted through the cylindrical lens array 30 is improved. In this way, the stereoscopic display device 3 of the present embodiment utilizes the diffuser 81 to diffuse the light in the horizontal and vertical directions, thereby illuminating the display unit 10. In addition, by arranging a plurality of second lens elements 31 in a zigzag shape and using the diffuser 81, the amount of light at the ridge portion of the second lens element 31 can be utilized to supplement the insufficient amount of light at the end portion of the second lens element 31, thereby improving the in-plane uniformity.

According to the present embodiment, by making the light emitted from each line light source 51 of the light source unit 50 pass through the cylindrical lens array 30, the lens sheet 40 and the diffusion sheet 81, the display range can be made larger than the viewing angle of the lens sheet 40. In addition, through the above-mentioned configuration, high-definition display can be achieved. Therefore, by dividing the light emission of the light source unit 50 into fields and optimizing the display content, a stereoscopic display with high definition and depth can be achieved.

<Fifth Embodiment>

Next, a stereoscopic display device according to a fifth embodiment is described. The stereoscopic display device according to this embodiment displays stereoscopic images by time multiplexing.

FIG. 29 is a cross-sectional view schematically showing a stereoscopic display device according to an embodiment of the disclosure.

29 , the stereoscopic display device 5 of the present embodiment includes a display unit 10 , a display driving unit 17 , a light source control unit 15 d , and a light source driving unit 19 .

The display driving unit 17 displays the element images of the stereoscopic image 92 on the display unit 10. The display driving unit 17 may also display a plurality of element images of different display directions of the stereoscopic image 92 on the display unit 10. The display driving unit 17 may also display a plurality of element images representing different angles or display positions of the stereoscopic image. For example, the plurality of element images may be a plurality of first images. The light source control unit 15d includes a lens sheet 40, a cylindrical lens array 30, a plurality of line light sources 51, and a diffuser sheet 81. The plurality of line light sources 51 are arranged on the back side of each second lens element 31. For example, the plurality of line light sources 51 are arranged in the X-axis direction parallel to the XY plane of the display unit 10. The light source driving unit 19 may also sequentially drive the plurality of line light sources 51 that illuminate each element image. The light source driving unit 19 may also sequentially drive each line light source 51 that illuminates each element image.

The light source driving unit 19 causes the line light sources 51 arranged at the relatively same position on the back of the cylindrical lens array 30 to emit light. For example, the light emitted from the line light source 51A is represented by a solid line in this figure. For example, the light emitted from the line light source 51B is represented by a dotted line. For example, the light emitted from the line light source 51C is represented by a dotted line in this figure.

The light emitted from each line light source 51 is converted into parallel light by each second lens element 31 of the cylindrical lens array 30. The light converted into parallel light by each second lens element 31 is collected by each first lens element 41 of the lens sheet 40. The light collected by each first lens element 41 is collected at each focal position where a diffusion sheet 81 is arranged. The light collected at each focal position then travels in a manner of light flux diffusion. A diffusion sheet 81 for diffusing light is arranged at a position including each focal position. Therefore, the diffused light transmitted through the diffusion sheet 81 can expand the light flux compared to a state without the diffusion sheet 81. The diffused light transmitted through the diffusion sheet 81 is incident on the display unit 10. In this way, a wide range of stereoscopic images can be displayed by using the diffusion sheet 81.

29 , three line light sources 51A to 51C are shown on the back side of one second lens element 31. Here, the number of line light sources 51 arranged on the back side of the second lens element 31 is not limited to three, and may be two or more than four.

If the line light source 51A on the optical axis of the second lens element 31 of the cylindrical lens array 30 is illuminated, the light is focused at the focal point on the optical axis of each first lens element 41 of the lens sheet 40. If the line light source 51B slightly offset from the optical axis of the second lens element 31 is illuminated, the angle of the parallel light is slightly offset. The light is focused at a position offset from the focal point of the above-mentioned line light source 51A. Similarly, if the line light source 51C slightly offset from the optical axis of the second lens element 31 is illuminated, the angle of the parallel light is slightly offset. The light is focused at a position offset from the focal point of the above-mentioned line light sources 51A and 51B.

Therefore, in this embodiment, the points where the lights of the plurality of line light sources 51 are focused on the diffuser 81 are staggered. The light rays of the elemental images are reproduced with these focused points as the center. The stereoscopic image 92 is recognized by using these focused points as focused patterns. The switching display is performed sequentially by synchronizing the light emission of the line light sources 51A to 51C with the display of the display unit 10.

FIG. 30 is a diagram illustrating time multiplexed field control according to an embodiment of the disclosure.

Referring to Figure 30, the horizontal axis represents the passage of time. The upper end represents an observation angle of 0°, and the lower end represents an observation angle of 60°. Referring to Figure 30, the element image of resolution multiplexing (resolutionmultiplex) I generated by the line light source 51A, the element image of resolution multiplexing II generated by the line light source 51B, and the element image of resolution multiplexing III generated by the line light source 51C in the stereoscopic display device 5 are represented in sequence. The focusing pattern of each element image is observed to be misaligned in each field. Referring to Figure 30, for example, the apple stem is visible in the element image of resolution multiplexing I, but the apple stem is hidden in the element image of resolution multiplexing II. As a result, the pixels between the patterns of the element images in the stereoscopic image are interpolated according to the focusing position, so that a resolution multiplexed stereoscopic image 92 can be displayed.

As described above, the display driving unit 17 displays a plurality of element images indicating the display position of the stereoscopic image 92. The display driving unit 17 may also switch a plurality of element images including a first element image and a second element image and display the plurality of element images on the display unit 10. The light source driving unit 19 drives the light source for illuminating the element images. Specifically, the light source driving unit 19 sequentially drives a plurality of light sources for illuminating each element image. The light source driving unit 19 may also sequentially drive a plurality of line light sources 51 including a first line light source 51 illuminating the first element image and a second light source illuminating the second element image. The display driving unit 17 may also switch a plurality of element images by field division and display them. The light source driving unit 19 may also light up the line light source 51 corresponding to the switched element image according to the field switching.

31 is a diagram illustrating an arrangement width d _C and a focal point displacement width d _L of a line light source of a light source control unit in a stereoscopic display device according to an embodiment of the disclosure.

31 , by setting the focal point displacement width d _L as the width that can compensate for the element image width of the lens sheet 40, the focal length f _L of the lens sheet 40 that does not generate crosstalk when the shielding plate 82 is not provided is determined. Furthermore, when the installation width d _C of the line light source 51 is set to the size of the line light source 51, since each triangle has a similar relationship, the focal length f _C of the cylindrical lens array 30 can be expressed by the following equations (6) and (7).

[Formula 6]

[Formula 7]

Thus, the ratio of the setting width _dC between the line light sources 51 at both ends of the plurality of line light sources 51 arranged in a direction (X-axis direction) in the plane parallel to the display unit 10 to the distance _fC between the column of the plurality of line light sources 51 and the cylindrical lens array 30 is the same as the ratio of the focal point displacement width _dL between the focal points at both ends of the focal points of the plurality of line light sources 51 on the diffusion sheet 81 to the distance _fL between the diffusion sheet 81 and the lens sheet 40. The same distance and ratio not only mean being strictly the same, but also being the same within a range including errors caused by the shapes of components and errors in manufacturing.

FIG. 32 is a diagram illustrating a light-collecting pattern in a stereoscopic display device according to an embodiment of the disclosure.

32, the focal point displacement width _dL between the focal points on the diffusion sheet 81 can be represented by the lens pitch _Lp of the lens sheet 40. At this time, in the case of performing time multiplexing in the m field which is an arbitrary integer, the line light sources are arranged at equal intervals by dividing _Lp by m, so that the resolution can be compensated at equal intervals. In this case, since the distance between the line light sources 51 is _dL /(m-1), the focal point displacement width _dL can be represented by equations (8) and (9). In order to design the focusing surface arranged in this way, the focal length of the cylindrical lens is designed by substituting the focal point displacement width _dL obtained by equations (8) and (9) into equation (7).

[Formula 8]

[Formula 9]

When the element pixel pitch is 3 pixels, if the pixels are equally spaced in 3 fields to compensate for the element image width, the stereoscopic display can achieve the same resolution as the display unit 10. In the display unit 10 such as LCD, the response speed of the liquid crystal is limited, and if time multiplexing is performed with field multiplexing, flicker is easily perceived.

FIG. 33 is a diagram illustrating a screen display in which a plurality of fields of view are time-multiplexed in a stereoscopic display device according to an embodiment of the disclosure.

Referring to FIG33, if angle multiplexing is performed with three fields of -30°, 0°, and +30°, the display other than the angle being displayed will be recognized as a black screen. Since the brightness of the entire screen varies greatly, the stereoscopic display device of the comparative example is easy to feel flicker. In addition, referring to FIG30, for the stereoscopic display device 5 of this embodiment as a case of resolution multiplexing, it has the characteristics that the brightness of the entire screen varies little and flicker is difficult to feel in the display using the same field.

According to this embodiment, the resolution can be improved by utilizing time multiplexing based on resolution multiplexing. The configuration and effects of this embodiment other than the above-mentioned contents are included in the description of the first to fourth embodiments.

<Sixth Embodiment>

Next, a stereoscopic display device according to a sixth embodiment is described.

34 and 35 are diagrams showing light-collecting patterns in a stereoscopic display device according to various disclosed embodiments. For example, the stereoscopic display device 6 of this embodiment arranges six line light sources 51A to 51F on the back side of each second lens element 31 of the cylindrical lens array 30. The line light sources 51A to 51F are arranged in this order along the X-axis direction.

Referring to FIG34 , the element image is displayed by making the line light source 51A emit light at a predetermined time. In the next sequence, the element image is displayed by making the line light source 51B next to the +X axis side of the line light source 51A emit light. In this way, when the pitch of the element image is in a state of being divided into six, it can be represented as lighting the spotlight pattern when the field changes to an adjacent position. In this case, since the displacement of the spotlight pattern is small and the speed is slow, it is possible to track the moving line light source 51 with the eyes.

Referring to FIG35 , the element image is displayed by making the line light source 51A emit light at a predetermined time. In the next sequence, the element image is displayed by making the third line light source 51D on the +X axis side of the line light source 51A emit light. In this way, when the pitch of the element image is in a state of being divided into six, the spotlight pattern is represented as being lit at a position of about 1/2 of the pitch of the element image. By lighting in this way, the absolute value of the displacement of the spotlight pattern is maximized, making it difficult to track the moving line light source 51 with the eyes.

For example, when the width between the line light sources 51 at both ends of the plurality of line light sources 51 arranged on the back surface of each second lens element 31 is set to one pitch, the light source driving unit 19 may subsequently drive the line light source 51 located at a position separated from the driven line light source 51 by at least half a pitch. Here, when the light source driving unit 19 sequentially drives the plurality of line light sources 51, it may subsequently drive the line light source 51 located at a position separated from the driven line light source 51 by at least one line light source 51.

By performing the control of the spotlight pattern as described above and performing a display that cannot be tracked by the eye, the effect of resolution multiplexing can be improved. In addition, by controlling the spotlight pattern to discern the movement of the displayed image and applying resolution multiplexing only to the stationary portion, it is possible to prevent the reduction of the resolution of the moving image.

<Seventh Embodiment>

Next, the stereoscopic display device of the seventh embodiment is described. The stereoscopic display device of this embodiment uses a holographic optical element (HOE). As described above, in the case where the stereoscopic display device is formed using an imaging optical system including a cylindrical lens array 30 and a lens sheet 40, in order to improve uniformity, it is necessary to widen the distance between the cylindrical lens array 30 and the lens sheet 40. As a result, the thickness of the light source control unit 15 will increase. Therefore, the imaging optical system including the cylindrical lens array 30 and the lens sheet 40 is replaced by an HOE. The HOE can reversely calculate the unevenness generated during reproduction and record it during recording, so that the unevenness can be reduced during reproduction, thereby reducing the thickness of the light source control unit 15.

Fig. 36 is a configuration diagram showing a recording optical system of a holographic optical element in a stereoscopic display device according to an embodiment of the disclosure. Fig. 37 is a configuration diagram showing a reproduction optical system in a stereoscopic display device according to an embodiment of the disclosure.

36 and 37, the stereoscopic display device 7 of the present embodiment includes a holographic optical element recorded in a recording optical system as a reproducing optical system. For example, the recording optical system records a light-converging pattern formed by a cylindrical lens array 30 and a lens sheet 40 into a HOE such as a photopolymer 73. The reproducing optical system reproduces the light-converging pattern recorded in the HOE through a point light source such as an LED.

36, the recording optical system includes a lens 71, a lens 72, a photopolymer 73, and a half mirror 74. The photopolymer 73 is used as an HOE by recording a hologram. A plurality of line light sources 151 of a light-converging pattern 76 formed by the lens sheet 40 are produced. Then, the object light including the line light source 151 is imaged as a real image 75 on the inner side of the photopolymer 73 by the lens 71. At this time, the light from the lens 71 on the optical axis of the object light including the line light source 151 is interfered with the reference light focused at the point PH by the lens 72 by the photopolymer 73. Thus, the real image 75 of the light-converging pattern of the line light source 151 and the interference fringes of the reference light are recorded on the photopolymer 73. The real image 75 of the line light source is designed to have the same magnification as the light-converging pattern formed by the cylindrical lens array 30 and the lens sheet 40 in the stereoscopic display device 7, and is recorded as the reference light of the convergent light that is the same as the point light source during reproduction, so that the light-converging pattern formed by the cylindrical lens array 30 and the lens sheet 40 is reproduced when the point light source is irradiated.

37 , the reproduction optical system includes an LED 77, a photopolymer 73, and a diffusion sheet 81. In fact, in the stereoscopic display device 7, the reproduction optical system is provided as a backlight on the back of a plurality of display units, and displays a stereoscopic image in the same manner as the stereoscopic display device described so far. In the reproduction optical system, an LED 77 is arranged at a position corresponding to the point PH of the recording optical system. A plurality of LEDs 77 are arranged at approximately the same distance as the point PH. And, each LED 77 is regarded as a point light source for reproducing a real image 75, and irradiates the photopolymer 73. By irradiating the photopolymer 73 with each LED 77, a real image 75 of the line light source 151 recorded on the photopolymer 73 is reproduced. A diffusion sheet 81 is arranged on the +Z axis direction side of the photopolymer 73. The display unit 10 is arranged on the +Z axis direction side of the diffusion sheet 81. Accordingly, the reproduced real image 75 is diffused by combining the image with the diffusion sheet 81, and then irradiates the display unit 10. Since the position of the line light source 151 being reproduced changes according to the lighting position of the LED 77, different condensing pattern positions can be reproduced. Therefore, a stereoscopic display with multiplexing of resolutions can be realized.

When the LED arrangement width of the light source surface where each LED 77 is arranged is set to d _H , when the distance from the photopolymer 73 to the diffuser 81 is set to f _L , and the element image width is set to d _L , the distance f _H from the light source surface to the photopolymer 73 can be expressed by the following equations (10) and (11). At this time, as in the case where it is not a hologram, referring to FIG. 32 , the focal point displacement width d _L between the focal points on the diffuser 81 can be expressed by the lens pitch L _p of the lens sheet 40. At this time, in the case of performing time multiplexing using m fields as an arbitrary integer, the line light sources can be arranged at equal intervals in which L _p is divided into m, thereby compensating the resolution at equal intervals. In this case, since the distance between the line light sources is d _L / (m-1), the focal point displacement width d _L can be expressed by equations (8) and (9). In order to design the light-collecting surface arranged in this way, the focal point displacement width d _L obtained by equations (8) and (9) is substituted into equation (11) to design the focal length of the cylindrical lens.

[Formula 10]

[Formula 11]

If a thick hologram with excellent efficiency is used, the angle selectivity is high and the width of d _H can be narrowed. It is also possible to consider narrowing the light source setting range relative to the width of the HOE. It is also possible to consider using a monolithic micro LED display (Monolithic Micro LED Display) capable of fine control for reproduction. Therefore, the stereoscopic display device 7 of this embodiment records the functions of the first cylindrical lens and the second cylindrical lens to the holographic optical element in a manner that can be reproduced using the light source, and also includes a holographic optical element arranged between the light source and the display unit 10 instead of the first cylindrical lens and the second cylindrical lens. Thus, a holographic optical element can be used for stereoscopic display.

According to the stereoscopic display device of the first to seventh embodiments described above, the display range of the line light source 51 can be made larger than the viewing angle of the lens sheet 40 by means of the cylindrical lens array 30, the lens sheet 40 and the diffusion sheet 81. In addition, different element images can be displayed by using the light from different light-collecting positions irradiated by each line light source 51, and the light emission of each line light source 51 can be divided and displayed by field. Thus, stereoscopic display with high resolution, high definition and depth can be performed.

<Eighth Embodiment>

Next, an eighth embodiment will be described. This embodiment is an example in which the lighting pattern of the light source in the sixth embodiment described above is shifted by a specific amount so that flicker is less noticeable.

FIG. 38 is a diagram showing a light-collecting pattern in a stereoscopic display device 1008 according to an embodiment of the disclosure.

Referring to FIG. 38 , the spotlight pattern is repeatedly illuminated at each interval between the lens sheets 40 and is divided and illuminated according to the number of light sources. Here, the number of divisions is represented by N. That is, it is equivalent to the state where the light source of N columns is located on the back of the spotlight lens. When the illumination is switched and displayed by field division, in the case of irradiation with a light source next to the light source irradiated in the previous field, the left side of FIG. 38 corresponds to the illumination condition of the previous field, and the illumination condition of the next field corresponds to the right side. As a spotlight pattern, since the adjacent light sources divided by N are illuminated, the 1-shift part is illuminated. Here, the displacement amount is referred to as M. Therefore, M and N are integers. FIG. 39 is a diagram showing the lighting order of 5-division 2-shift in the stereoscopic display device 1008 according to the eighth embodiment. The written numbers in the accompanying drawings represent the fields of the lighting order. In this example, it is lit sequentially from No. 1 and lit to No. 5, and then No. 1 is lit again. If the number of displacements is large, the lighting interval between fields becomes larger, so the visual speed increases. Here, referring to FIG. 38 , an N-divided M-shift satisfying the following conditions may be considered.

1) mod(M, N) ≠ 0, that is, the remainder of M/N is not 0.

2) The absolute value of M is the maximum value that is less than or equal to N/2. However, when M>N/2, mod(M, N) is the same as (N-M) and is therefore considered a negative value, and the maximum value of |M| (absolute value) becomes N/2.

It is preferable to satisfy both conditions 1) and 2).

For example, the lighting order of light sources such as 10-division 4-shift, 9-division 4-shift, 8-division 3-shift, 7-division 3-shift, 5-division 2-shift, etc. satisfies this condition. Fig. 39 shows 5-division 2-shift, which is a lighting order that satisfies this condition.

The reason for condition 1) is as follows: For example, if M/N is divisible, the predetermined intervals cannot be lit up, so the speed is discontinuous, and flickering is easily perceived.

The reason for condition 2) is as follows. For example, this is because the larger M is, the greater the visual speed is.

As described above, when there are N light sources within the width between the light sources at both ends of the plurality of light sources arranged in a direction in the plane parallel to the display unit 10, the light source driving unit 19 sequentially drives the light sources at positions separated from the driven light sources by a displacement amount M. However, N is an integer that cannot be divided by M, and the absolute value of M is a maximum value less than N/2. If M is greater than or equal to N/2, M is regarded as a negative integer of (N-M).

According to the stereoscopic display device 1008 of the present embodiment, flicker may be difficult to feel. Usually, people can feel flicker below 50 Hz. However, even in the case of 50 Hz or below, fine patterns below human vision cannot be decomposed, making it difficult to feel flicker. Similarly, motion patterns below dynamic vision cannot be recognized, making it difficult to feel flicker. Usually, if the pattern interval is below the visual acuity (1 minute visual acuity 1.0), it cannot be decomposed. In addition, as dynamic vision, patterns above 5° (Degree)/s cannot be recognized. If the display is observed from a distance, the angular interval of the pattern becomes narrower, and if the display is observed from close, the angular velocity of the pattern becomes faster. Therefore, the visual speed is accelerated by a specified number of displacements, and the pattern is performed at a predetermined speed, making it difficult to feel flicker.

<Ninth Embodiment>

Next, a ninth embodiment will be described.

FIG40 is a plan view showing the arrangement of the lens sheet of the first lens array, the condenser lens of the second lens array, and the light source in the stereoscopic display device according to an embodiment of the disclosure. FIG41 is a cross-sectional view schematically showing the arrangement of the display unit, the diffuser, the lens sheet of the first lens array, the condenser lens of the second lens array, and the light source in the stereoscopic display device according to an embodiment of the disclosure. FIG42 is a diagram showing the condenser pattern of the diffuser surface in the stereoscopic display device according to an embodiment of the disclosure. FIG43 is a plan view showing the arrangement of the condenser lens and the light source of the second lens array in the stereoscopic display device according to an embodiment of the disclosure. FIG44 is a plan view showing the arrangement of the lens sheet of the first lens array in the stereoscopic display device according to an embodiment of the disclosure. FIG45 is a graph showing the contrast (Contrast) in the stereoscopic display device according to an embodiment of the disclosure, wherein the horizontal axis represents the spatial frequency and the vertical axis represents the contrast.

40 and 41 , in the stereoscopic display device 1009 of the present embodiment, the light source control unit 1015 includes a diffuser 81, a lens sheet 40 as a first lens array, a plurality of collimated lenses 1030 as a second lens array, and a plurality of light sources 1051. The second lens array is configured as a honeycomb lens array. The plurality of collimated lenses 1030 included in the second lens array are regular hexagonal lenses 1031. Therefore, the second lens array includes a plurality of regular hexagonal lenses 1031 arranged at a pitch wider than that of the first lens element (first cylindrical lens) 41 of the lens sheet 40. The plurality of regular hexagonal lenses 1031 are arranged in a zigzag arrangement in the pixel arrangement direction of the display unit 10.

In this embodiment, each light source 1051 may also be in a tiny rectangular shape or a point shape. A plurality of light sources 1051 are arranged in a matrix shape into a plurality of rows and columns in a column direction parallel to the surface of the display unit 10 and in a row direction intersecting the column direction. A plurality of light sources 1051 arranged in the same column may also be driven to light up simultaneously. The ridge lines of the plurality of first lens elements (first cylindrical lenses) 41 of the first lens array extend in the column direction. With this configuration, the stereoscopic display device 1009 of this embodiment has the following features.

1) The condenser lenses 1030 of the second lens array are arranged in a honeycomb lens arrangement (ie, an arrangement in a honeycomb shape). Thus, the arrangement of the lenses can be effectively achieved. Therefore, the amount of light can be increased without unevenness.

2) Arrange the light sources 1051 in a direction inclined along the ridge line of the lens sheet 40. Therefore, the amount of light incident on the focusing lens 1030 can be increased. In addition, if the light sources 1051 are arranged along the ridge line of the lens sheet 40, the focusing width will not become wider, so crosstalk can be reduced. Therefore, even if a slit is not used, crosstalk can be reduced. This is because, when the column of light sources 1051 arranged along the ridge line of the lens sheet 40 is arranged at a position approximately at the focal length of the focusing lens 1030, and each of the light sources 1051 irradiates the diffuser 81 arranged at the approximate focal length of the lens sheet 40 with parallel light through the lens sheet 40, the parallel light of each light source will become light concentrated on the ridge line of the lens sheet 40.

As described so far, the plurality of light sources 1051 are arranged at positions approximately at the focal length of the condenser lens 1030, and when irradiation is performed using each light source 1051, irradiation is performed with parallel light, and when the diffusion sheet 81 is arranged at a position approximately at the focal length of the lens sheet 40, the positional relationship between the light source 1051 and the condenser lens 1030 is similar to the positional relationship between the lens sheet 40 and the diffusion sheet 81. Therefore, referring to FIGS. 41 to 44, the ratio (d SW /f C ) of the width d _SW between the light sources 1051 at both ends of the plurality of light sources 1051 arranged in another direction parallel to the plane of the display unit 10 and the distance f _C between the second lens array and the column of the plurality of light sources 1051 is the same as the ratio (d _FW /f _L ) of the width d _FW between the light-converging points at both _ends of the light-converging points of the plurality of light sources 1051 on the diffusion sheet 81 and the distance f _L between the diffusion sheet 81 and the first lens array. For example, the following formula ( ₁₂ ) is satisfied.

[Formula 12]

45 , in the case where the width between the focal points is 1 and 2 times the sub-pixel width of the display unit 10, the contrast ratio increases within the range shown in the figure. In addition, if the width between the focal points increases to more than 3 times the sub-pixel width of the display unit 10, the contrast ratio is maintained (shifted) at a low level. Therefore, if the width d _FW between the focal points is less than 2 times the sub-pixel width of the display unit 10, the contrast ratio can be improved. In this way, a high-definition three-dimensional display can be set as a display with less crosstalk. In addition, as described above, the crosstalk is proportional to the focal width, and the minimum unit of the sampling interval of the display unit 10 is the sub-pixel width, so it will not be proportional below the sub-pixel width in the display unit 10. Therefore, by considering this relationship, the optimal optical design of the focusing lens 32 can be achieved.

<Tenth Embodiment>

Next, a stereoscopic display device according to a tenth embodiment will be described.

Figure 46 is a cross-sectional view showing a light source control unit in a stereoscopic display device according to an embodiment disclosed. Figure 47 is a plan view showing a honeycomb lens array as a third lens array in a stereoscopic display device according to an embodiment disclosed. Figure 48 is a diagram showing a two-layer lens sheet as a third lens array in a stereoscopic display device according to an embodiment disclosed. Figures 49 and 50 are cross-sectional views showing a light source control unit in a stereoscopic display device according to various embodiments disclosed. Figure 51 is a graph showing the relationship between the position of the cap lens of the third lens array in a stereoscopic display device according to an embodiment disclosed and the amount of light, wherein the horizontal axis represents the position of the cap lens and the vertical axis represents the amount of light. Figure 52 is a graph showing the relationship between the distance between the light sources and the distance between the cap lenses in a stereoscopic display device according to an embodiment disclosed.

46 to 50 , in the stereoscopic display device 1010 of the present embodiment, the light source control unit 1015a further includes: a second lens array including a condenser lens 1030; and a third lens array arranged between the plurality of light sources 1051. The third lens array includes a plurality of cap lenses 1020 corresponding to the plurality of light sources 1051.

The hat lens 1020 is arranged near the light source 1051. The hat lens 1020 is arranged so that one hat lens 1020 corresponds to one light source 1051. The hat lens 1020 has a function of collecting light diffused from the light source 1051 to the condenser lens 1030. Accordingly, the amount of light obtained from the light source 1051 can be increased to improve light efficiency.

Referring to Figure 47, in the light source control unit 1015a, the plurality of light sources 1051 may be arranged in a zigzag arrangement along any direction. In addition, the cap-shaped lens 1020 may also be a regular hexagonal lens. As described above, in the case where the plurality of light sources 1051 are arranged in a zigzag arrangement in at least one direction of the column direction parallel to the surface of the display unit 10 and the row direction intersecting the column direction, the plurality of cap-shaped lenses 1020 may also be composed of a honeycomb lens array 1021.

In addition, referring to Figure 48, when the arrangement of multiple light sources 1051 is implemented in a matrix shape in the column direction and the row direction, the multiple cap lenses 1020 can also be a double convex lens sheet in which a lens sheet 1022 including multiple cylindrical lenses with ridges extending along the column direction is overlapped with a lens sheet including multiple cylindrical lenses with ridges extending along the row direction.

Specifically, in the light source control unit 1051a, the third lens array, as a stacked cylindrical lens array with two layers overlapping, may also include an upper cylindrical lens array arranged on the back side of the second lens array and a lower cylindrical lens array arranged on the back side of the upper cylindrical lens array. The multiple light sources 1051 are arranged in a matrix shape into multiple rows and columns in the column direction parallel to the surface of the display unit 10 and in the row direction intersecting the column direction. The ridge line of each cylindrical lens included in the upper cylindrical lens array extends in the column direction or the row direction. The ridge line of each cylindrical lens included in the lower cylindrical lens extends in a direction different from the direction in which the ridge line of each cylindrical lens in the upper cylindrical lens array extends in the column direction and the row direction.

In this case, the cap lens 1020 is a portion where each cylindrical lens included in the upper layer cylindrical lens array overlaps each cylindrical lens included in the lower layer cylindrical lens array.

49, the pitch at which the plurality of cap lenses 1020 are arranged may be matched with the pitch at which the plurality of light sources 1051 are arranged. In addition, referring to FIG50, the pitch at which the plurality of cap lenses 1020 are arranged may be made shorter than the pitch at which the plurality of light sources 1051 are arranged. Referring to FIG50, by making the pitch of the plurality of cap lenses 1020 shorter than the pitch of the plurality of light sources 1051, the amount of light obtained from the light sources 1051 may be increased, thereby improving light efficiency. A method for determining such a pitch is described below.

51 , if the pitch of the cap lens 1024 is changed by moving the position of the cap lens 1020, the illumination distribution that is biased to the left side in case A in the figure changes to the illumination distribution that is extended to the left side in case B in the figure. Also, as in the illumination distribution in case C in the figure, when the pitch of the cap lens 1020 is at an optimal pitch among the pitches shorter than the pitch of the light source 1051, the illumination distribution exhibits an optimal value, and the light amount exhibits a maximum value.

If the position of the cap lens 1020 is further moved so that the pitch of the cap lens 1020 is close to the pitch of the light source 1051, the illumination distribution is biased to the right and the light quantity is reduced as shown in the D to F cases in the figure. Therefore, the pitch of the cap lens 1020 can be determined at the position where the light quantity is maximum.

52, in the light source control unit 1015a, the pitch (pitch) of the light sources 1051 is referred to as the interval _PLED , and the distance between the second lens array including the condenser lens 1030 and the column of the plurality of light sources 1051 is referred to as the distance _fc . In addition, the distance between the third lens array including the cap lens 1020 and the second lens array is referred to as the distance _dcap . In this case, preferably, the pitch (pitch) _Pcap of the cap lens 1020 of the third lens array is determined by the following formula (13).

[Formula 13]

According to the stereoscopic display device 1010 of the present embodiment, since the third lens array including the plurality of cap lenses 1020 is included, light efficiency can be improved by increasing the amount of light obtained from the light source 1051. In addition, by using the third lens array, it can be helpful to uniformly illuminate the condenser lens 1030. In addition, by appropriately determining the pitch of the cap lenses 1020, the amount of light obtained from the light source 1051 can be further increased to improve light efficiency.

<Eleventh Embodiment>

Next, the eleventh embodiment will be described. The eleventh embodiment is an example in which the second lens element (second cylindrical lens) 31 and the regular hexagonal lens 1031 are conceptualized as the condenser lens 1030 in the second lens array.

FIG. 53 is a diagram showing the structure of a stereoscopic display device according to an embodiment of the disclosure.

53 , the stereoscopic display device 1011 includes: a display unit 10; a display driving unit 17, which displays an elemental image of a stereoscopic image on the display unit 10; a light source control unit 1015b, which has a lens sheet 40 as a first lens array arranged on the back side of the display unit 10 and including a plurality of first lens elements (first cylindrical lenses) 41 arranged at a predetermined pitch, a second lens array arranged on the back side of the first lens array and including a plurality of focusing lenses 1030 arranged at a pitch wider than the first cylindrical lenses, a plurality of light sources 1051 arranged on the back side of each focusing lens 1030, etc., a diffusion sheet 81 arranged between the display unit 10 and the first lens array and arranged at a position including each focal position of each first lens element (first cylindrical lens) 41; and a light source driving unit 19, which drives the light source for illuminating the elemental image.

The condenser lens 1030 may also be a second lens element (second cylindrical lens) 31. In this case, the second lens array includes a plurality of second lens elements (second cylindrical lenses) 31 arranged at a pitch wider than that of the first cylindrical lenses.

In addition, the condenser lens 1030 may also be a regular hexagonal lens 1031. In this case, the second lens array includes a plurality of regular hexagonal lenses 1031 arranged at a pitch wider than that of the first cylindrical lenses.

The embodiments of the present disclosure are described above, but the present disclosure is not limited to the first to eleventh embodiments and modified examples, and can be appropriately modified within the scope of the main purpose of the present disclosure. For example, the various components of the first to eleventh embodiments and modified examples can also be appropriately combined. In addition, in the case of combination, each component can also be changed within the scope of the main purpose.

The present disclosure has been illustrated and described with reference to various embodiments, but it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims (15)

1. A stereoscopic display device, comprising: Display unit; a display driving unit, which displays elemental images of a three-dimensional image on the display unit; a light source control section including a first lens array disposed on the back side of the display section and including a plurality of first cylindrical lenses arranged at a predetermined pitch, a second lens array disposed on the back side of the first lens array and including a plurality of condenser lenses arranged at a pitch wider than that of the first cylindrical lenses, a plurality of light sources disposed on the back side of each condenser lens, and a diffusion sheet disposed between the display section and the first lens array and disposed at a position including each focal position of each first cylindrical lens; and The light source driving unit drives the plurality of light sources for irradiating the elemental images. 2. The stereoscopic display device according to claim 1, wherein: The plurality of condenser lenses are second cylindrical lenses, The second lens array includes a plurality of the second cylindrical lenses arranged at a pitch wider than that of the first cylindrical lenses. 3. The stereoscopic display device according to claim 2, wherein: The display driving unit is configured to display a plurality of element images indicating display positions of a stereoscopic image, and to display the plurality of element images including a first element image and a second element image on the display unit while switching the plurality of element images. The light source driving section is configured to sequentially drive the plurality of light sources that illuminate each elemental image, and sequentially drive the plurality of light sources including a first light source that illuminates the first elemental image and a second light source that illuminates the second elemental image. 4. The stereoscopic display device according to claim 2, wherein: The display driving unit is configured to switch and display the plurality of element images by field division, The light source driving unit is configured to light the light source corresponding to the elemental image switched according to switching of fields. 5. The stereoscopic display device according to claim 2, wherein: In the diffusion sheet, points where the lights of the plurality of light sources are concentrated are staggered from each other. 6. The stereoscopic display device according to claim 5, wherein: The ratio of the width between the light sources at both ends of the multiple light sources arranged along a direction within a plane parallel to the display unit to the distance between the second lens array and the column of the multiple light sources is the same as the ratio of the width between the focal points at both ends of the focal points of the multiple light sources on the diffuser to the distance between the diffuser and the first lens array. 7. The stereoscopic display device according to claim 2, wherein: The light source control unit further includes a shielding plate disposed on a surface of each first cylindrical lens, shielding light transmitting a peripheral portion of each first cylindrical lens, and having a slit transmitting a central portion of each first cylindrical lens. 8. The stereoscopic display device according to claim 2, wherein: In the second lens array, a plurality of the second cylindrical lenses are arranged in a zigzag pattern in a vertical direction and a horizontal direction of a pixel arrangement of the display section. 9. The stereoscopic display device according to claim 2, wherein: The light source driving section is configured to drive the plurality of light sources arranged in a direction in a plane parallel to the display section in sequence and to next drive the light source at a position spaced apart from the already driven light source by at least one light source. 10. The stereoscopic display device according to claim 2, wherein: The light source driving unit is configured to drive the light source at a position at least half a pitch away from the already driven light source next time, when the width between the light sources at both ends of the plurality of light sources arranged along a direction within a plane parallel to the display unit is set to one pitch. 11. The stereoscopic display device according to claim 2, wherein: recording the functions of the first cylindrical lens and the second cylindrical lens to a holographic optical element so as to be reproducible by the plurality of light sources, The stereoscopic display device further comprises: The holographic optical element is disposed between the plurality of light sources and the display unit instead of the first cylindrical lens and the second cylindrical lens. 12. The stereoscopic display device according to claim 1, wherein: The multiple focusing lenses are regular hexagonal lenses, The second lens array includes a plurality of the regular hexagonal lenses arranged at a pitch wider than that of the first cylindrical lenses, The plurality of regular hexagonal lenses are arranged in a zigzag pattern in a pixel arrangement direction of the display unit. 13. The stereoscopic display device according to claim 12, wherein: When there are N light sources within the width between the light sources at both ends of the plurality of light sources arranged in a direction in a plane parallel to the display unit, the light source driving unit is configured to drive the light source at a position separated by a displacement amount M from the already driven light source next time, Wherein, N is an integer that cannot be divided by M. If M is greater than n/2, M is regarded as a negative integer of (N-M), and the absolute value of M is the maximum value less than N/2. 14. The stereoscopic display device according to claim 12, wherein: The plurality of light sources are arranged in a matrix shape in a column direction parallel to the surface of the display unit and in a row direction intersecting the column direction into a plurality of rows and columns. wherein the plurality of light sources arranged in the same column are driven to light up simultaneously, The ridge lines of the plurality of first cylindrical lenses of the first lens array extend along the column direction. 15. The stereoscopic display device according to claim 12, wherein: The ratio of the width between the plurality of light sources arranged in a matrix shape in the column direction and the row direction intersecting the column direction at both ends in the row direction to the distance between the second lens array and the column of the plurality of light sources is the same as the ratio of the width between the light focusing points at both ends of the light focusing points of the plurality of light sources on the diffuser to the distance between the diffuser and the first lens array, Wherein, the width between the focal points is less than twice the width of the sub-pixels of the display unit.