WO2024257677A1 - Display device and vehicle mounted with same - Google Patents

Abstract

A display device according to the present invention is characterized by being provided with a display panel (11) capable of emitting video light to a windshield (3) of a vehicle (2), and a light source (12) emitting light to the display panel (11), wherein the display panel (11) is directed toward the driver (50) side of the vehicle (2), and the display panel (11) is disposed so as to be inclined with respect to the horizontal surface.

Description

Display device and vehicle equipped with said device

The present invention relates to a display device, a virtual image display device, and a vehicle equipped with the display device.

Virtual image display devices or head-up display (HUD) devices are known that project image light onto the windshield of an automobile to form a virtual image and display, for example, traffic information such as route information and congestion information, and automobile information such as remaining fuel and coolant temperature.

Japanese Patent Application Publication No. 3-169752

The image display section of the display device is placed, for example, on or inside the dashboard of the vehicle. When this happens, external light such as sunlight is reflected off the image display section and enters the eyebox, which can cause unwanted stray light and reduce visibility. One possible solution to this problem is to provide a cover around the display device to prevent sunlight from entering, but blocking the optical path of the image light with a cover or the like will make the virtual image invisible, and it is believed that a complete solution is not easy.

The challenge is to prevent the loss of visibility caused by sunlight without blocking the optical path of the image light.

According to a first aspect of the present invention, there is provided the following display device. The display device includes a display panel capable of projecting image light onto the windshield of a vehicle, and a light source that emits light to the display panel. The display panel is oriented toward the driver of the vehicle, and is disposed at an angle relative to the horizontal plane.

According to the present invention, the display panel can be tilted to prevent the deterioration of visibility caused by sunlight without blocking the optical path of the image light. Problems, configurations, and effects other than those described above will become clear from the description of the embodiment of the invention below.

FIG. 1 is a diagram showing an example of a vehicle equipped with a display device. FIG. 2 is a diagram illustrating an example of a device used to acquire vehicle information. FIG. 1 is a block diagram showing an example of a display device. FIG. 1 is a block diagram showing an example of a display device. FIG. 13 is a diagram for explaining an example of a sunlight countermeasure. FIG. 1 is a diagram illustrating an example of a structure of a display device. FIG. 4 is an enlarged view showing a light reflecting portion of a light guide portion of the display device. FIG. 1 is a diagram illustrating an example of a structure of a display device. FIG. 1 is a diagram illustrating an example of a structure of a display device. FIG. 1 is a diagram illustrating an example of a structure of a display device. 10 is a diagram for explaining angles θ1, θ2, and θ3. FIG. FIG. 11 is a diagram for explaining the angle θ2 more specifically. 11A and 11B are diagrams illustrating an example of a usage state when the inclination of the display panel is small. 11A and 11B are diagrams illustrating an example of a usage situation when the display panel is largely inclined. FIG. 13 is a diagram for explaining the relationship between angles θ1, θ2, and θ3. 11 is a diagram for explaining the relationship between the angle θ1 and the solar light receiving length ratio. FIG. 13 is a diagram for explaining the relationship between the angle θ2 and the rate of reduction in the virtual image size. FIG. 13 is a diagram for explaining a usage situation when angles θ1 and θ3 are in a predetermined relationship. FIG.

Below, an embodiment of the present invention will be described with reference to the drawings. The embodiment is an example for explaining the present invention, and appropriate omissions and simplifications have been made to clarify the explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings. When there are multiple components having the same or similar functions, they may be described by adding different subscripts to the same reference symbol. Furthermore, when there is no need to distinguish between these multiple components, the subscripts may be omitted.

First, an example of the system configuration will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing an example of the configuration of a vehicle 2 equipped with a display device or virtual image display device 1. With respect to the vehicle 2 and the driver, the horizontal direction X is the left-right direction, the lateral direction or width direction of the vehicle, the vertical direction Z is the up-down or longitudinal direction of the vehicle, and the horizontal direction Y, which is perpendicular to the lateral direction of the vehicle, is the front-rear direction of the vehicle or the direction of travel of the vehicle. The display device 1 may be referred to as a virtual image display device. In the following description, the term "display device" will be used.

The display device 1 acquires vehicle information 4 from cameras and various sensors installed in various parts of the vehicle 2. The various sensors, for example, detect various events that occur in the vehicle 2, periodically detect the values of various parameters related to the driving conditions, and acquire information on roads and the like from a navigation device. The vehicle information 4 includes, for example, the speed information and gear information of the vehicle 2, steering wheel steering angle information, lamp illumination information, external light information, distance information, infrared information, engine ON/OFF information, camera image information, acceleration gyro information, GPS (Global Positioning System) information, navigation information, vehicle-to-vehicle communication information, and road-to-vehicle communication information. The camera image information includes in-vehicle camera image information and outside-vehicle camera image information. The GPS information includes latitude and longitude as well as current time information. The vehicle information 4 also includes information input by the driver.

The display device 1 projects/emits image light onto the display area 5 of the windshield 3 based on such vehicle information 4. As a result, the display device 1 superimposes a virtual image corresponding to the displayed image onto the scenery, allowing the driver of the vehicle 2 (the driver's viewpoint) to view it. In this embodiment, projection of image light onto the display area 5 of the windshield 3 is described, but the projection unit that projects the image light may be a projection member such as a combiner.

The display device 1 is connected to the controller 100 of the vehicle 2 using an information transmission path, and the display device 1 and the controller 100 can communicate with each other. The controller 100 of the vehicle 2 is an ECU (Electronic Control Unit). The display device 1 and the controller 100 of the vehicle 2 communicate with each other via the information transmission path, for example, by a CAN (Controller Area Network). The display device 1 and the controller 100 of the vehicle 2 may also communicate with each other via an in-vehicle Ethernet or the like via the information transmission path.

Other connection forms may also be adopted. For example, when all information including video information is transmitted over a single information transmission path, the connection between the controller 100 (the source of video information, etc.) on the vehicle 2 side and the display device 1 (in other words, the connection form of the information transmission path) may be FPD-Link III, GMSL (Gigabit Multimedia Serial Link), etc.

The controller 100 controls the vehicle 2 based on the input and output of data, and is connected to the display device 1 to form an in-vehicle system. The in-vehicle system is a system in which the controller 100 can control the vehicle 2 using the vehicle information 4.

Next, an example of a device used to acquire vehicle information will be described with reference to FIG. 2. Also, control of a display device will be described with reference to FIG. 3 and FIG. 4. FIG. 2 shows an example of a device used to acquire vehicle information. FIG. 3 and FIG. 4 are functional block diagrams showing an example of the configuration of the main control parts in a display device.

The control unit of the display device 1 can acquire vehicle information data based on a communication protocol corresponding to, for example, a CAN (Controller Area Network) interface or a LIN (Local Interconnect Network) interface. The controller 100 of the vehicle 2 can also acquire data in a similar manner.

As shown in FIG. 2, the vehicle information 4 is acquired using devices such as cameras and various sensors connected to the controller 100 or the control device. Note that the various devices in FIG. 2 can be deleted, other types of devices can be added, or other types of devices can be replaced as appropriate. As an example, the controller 100 of the vehicle 2 may have the function of controlling the display device 1.

The vehicle speed sensor 901 detects the speed of the vehicle 2 and is used to generate speed information, which is the detection result. The shift position sensor 902 detects the current gear and is used to generate gear information, which is the detection result. The steering wheel steering angle sensor 903 detects the current steering wheel steering angle and is used to generate steering wheel steering angle information, which is the detection result. The headlight sensor 904 detects whether the headlights are on or off and is used to generate lamp illumination information, which is the detection result.

The illuminance sensor 905 and chromaticity sensor 906 detect external light from the vehicle 2 and are used to generate external light information that is the detection result. The distance measurement sensor 907 detects the distance between the vehicle 2 and an external object or the distance between external objects, and is used to generate distance information that is the detection result. The infrared sensor 908 detects the presence or absence and distance of an object in the vicinity of the vehicle 2, and is used to generate infrared information that is the detection result. The engine start sensor 909 detects whether the engine is ON/OFF, and is used to generate ON/OFF information that is the detection result.

The acceleration sensor 912 and gyro sensor 913 detect the acceleration and angular velocity of the vehicle 2 and are used to generate acceleration gyro information that represents the attitude and behavior of the vehicle 2.

The temperature sensor 914 detects the temperature inside and outside the vehicle, and is used to generate temperature information that is the detection result.

For example, if the display device 1 is stored in the dashboard of the vehicle 2, the temperature sensor 914 may be used to detect the temperature inside the dashboard. Then, if a temperature that may affect the operation of the display device 1 is detected, the display device 1 may stop operating. Here, the temperature sensor 914 may be disposed inside the dashboard, as an example. However, the temperature sensor 914 may also be disposed in another location where the temperature may be similar to that inside the dashboard.

Furthermore, when the display device 1 is not stored in the dashboard, such as on the dashboard, the temperature sensor 914 may be used to detect the temperature in the vicinity where the display device 1 is installed. Then, when a temperature that may affect the operation of the display device 1 due to direct sunlight or the like is detected, the display device 1 may stop operating. Here, the temperature sensor 914 may be disposed on the dashboard, as an example. The temperature sensor 914 may also be disposed outside the vehicle, assuming that the temperature in the vicinity of the display device 1 and the temperature outside the vehicle are similar.

The wireless transceiver 915 for road-to-vehicle communication generates road-to-vehicle communication information by road-to-vehicle communication between the vehicle 2 and roads, signs, signals, etc. The wireless transceiver 916 for vehicle-to-vehicle communication generates vehicle-to-vehicle communication information by vehicle-to-vehicle communication between the vehicle 2 and other vehicles in the vicinity. The wired and wireless communication unit 917 for mobile terminal-to-vehicle communication is a device that acquires information by wired communication or wireless communication from a device (e.g., a WiFi device) that connects to an LTE (Long Term Evolution) network. The controller 100 or the control device can acquire information to be transmitted and received over the LTE network via the wired and wireless communication unit 917 for mobile terminal-to-vehicle communication.

The in-vehicle camera 919 and the exterior camera 920 capture images of the inside and outside of the vehicle, and are used to generate in-vehicle camera image information and exterior camera image information. Specifically, the in-vehicle camera 919 is, for example, a camera for a DMS (Driver Monitoring System) that captures the driver's posture, eye position, movement, etc. In this case, the driver's fatigue level, eye position, etc. can be ascertained by analyzing the captured image.

On the other hand, the exterior camera 920 captures the surrounding conditions, for example, in front of and behind the vehicle 2. In this case, by analyzing the captured image, it becomes possible to ascertain the presence or absence of obstacles such as other vehicles or people in the vicinity, buildings, terrain, road conditions such as rain, snow, ice, unevenness, and road signs. The exterior camera 920 also includes, for example, a drive recorder that records the conditions while driving.

The GPS receiver 921 generates GPS information obtained by receiving GPS signals from GPS satellites. For example, the current time, latitude, and longitude can be obtained by the GPS receiver 921. The VICS (Vehicle Information and Communication System, registered trademark) receiver 922 generates VICS information obtained by receiving VICS signals. The GPS receiver 921 and the VICS receiver 922 may be provided as part of a navigation system.

The driver's voice is input to the voice input device 918, which is used to generate voice information. By speaking, the driver can input operation details via the voice input device 918. The vehicle operation switch 911 is used to generate information on the driver's operation of the steering switch, etc.

In addition, the image generating unit 910 generates image information based on the vehicle information 4 acquired by the controller 100 of the vehicle 2.

FIGS. 3 and 4 are block diagrams that control the entire display device 1 and each part, and mainly control the display of the projected image (virtual image) on the display device 1.

In FIG. 3, the display device 1 includes, for example, a microcontroller (MCU) 1010 mounted on a wiring board or the like, a non-volatile memory 1011, a volatile memory 1012, an image processing unit 1013, a communication processing unit 1014, a display driver 1021, and a light source driving unit 1022. In the example of FIG. 3, the communication processing unit 1014 receives and transmits main vehicle information 4, but may also function as a control unit of the display device 1. The image processing unit 1013 receives image information or image data generated by the image generating unit 910 of the controller 100 of the vehicle 2. The image processing unit 1013 does not generate images, but processes images received from the vehicle 2. The processing of the image processing unit 1013 includes processes such as distortion correction and conversion (e.g., decoding) of images.

In FIG. 4, similarly to FIG. 3, there is provided a microcontroller (MCU) 1010, non-volatile memory 1011, volatile memory 1012, communication processing unit 1014, video processing unit 1015, display driver 1021, light source driving unit 1022, etc., which are mounted on a wiring board. However, in the example of FIG. 4, the video processing unit 1015 has the function of the video generation unit 910, and instead of receiving video information, generates video information using acquired information (e.g., vehicle information 4). In addition, the video processing unit 1015 can perform processes such as distortion correction and conversion on the generated video information.

As is widely known, the MCU 1010 includes a processor such as a CPU (Central Processing Unit), memory, and various peripheral functions. Therefore, each block except for the MCU 1010 may be mounted within the MCU 1010 as appropriate. Furthermore, the display device 1 is not limited to being implemented using the MCU 1010, but may be implemented using an ECU or other semiconductor devices. The control structure shown in Figures 3 and 4 may be, for example, a control unit implemented within the housing of the display device 1, or a control unit implemented outside the housing.

In the example of FIG. 3, the MCU 1010 receives video information via, for example, FPD-Link III or GMSL through the communication processing unit 1014. As a function of the video processing unit 1013, the MCU 1010 may perform distortion correction, conversion, and other processing on the received video information. The video processing unit 1013 is mainly realized by the CPU of the MCU 1010 reading and executing a program stored in the non-volatile memory 1011 or the volatile memory 1012.

In the example of FIG. 4, the MCU 1010 receives vehicle information 4 via the communication processing unit 1014, for example, via CAN or in-vehicle Ethernet. As a function of the video processing unit 1015, the MCU 1010 can generate video data for the video display unit 200 based on the vehicle information 4. The video processing unit 1015 is mainly realized by the CPU of the MCU 1010 reading and executing a program stored in the non-volatile memory 1011 or the volatile memory 1012.

That is, the video processing unit (1013, 1015) processes video data that determines the display content of the display image to be projected onto the display area 5 of FIG. 1, etc., based on the acquired information. The display driver 1021 drives each display element (pixel) included in the display panel 11 based on the video data. As a result, the video display unit 200 or the video display unit 200 creates and displays an image to be projected onto the display area 5 based on the video data.

Specifically, as shown in FIG. 1, distortion correction involves correcting image distortion caused by the curvature of the windshield 3 when an image from the display device 1 is projected onto the display area 5. The display driver 1021 then drives each display element (pixel) included in the display panel 11 based on the corrected image data. As a result, the image display section 200 or the image display unit 200 creates and displays an image to be projected onto the display area 5 based on the corrected image data.

The light source driver 1022 can also adjust the light source, adjusting the brightness of the image forming unit PGU1 or the light source 20 in the image forming unit PGU1. Based on the vehicle information 4 received via the communication processor 1014, the light source driver 1022, which is a driver used to drive the light source, controls the light source 20.

The display device 1 may also protect the display panel 11 based on external light information from the illuminance sensor 905. That is, in order to prevent the display panel 11 from being burned by sunlight hitting it, the display device 1 may perform an operation to protect the panel from sunlight according to the value of the illuminance sensor 905. More specifically, when the intensity of the external light or sunlight acquired by the illuminance sensor 905 is strong and there is a risk of the display panel 11 being burned, the display device 1 reduces the brightness of the light source 20 in the image forming unit PGU1 and suppresses the amount of light from the light source 20 that is incident on the display panel 11, thereby suppressing a rise in temperature of the display panel 11.

The non-volatile memory 1011 mainly stores in advance the programs executed by the CPU in the MCU 1010, the setting parameters used in the processing of each part in the MCU 1010, and specified audio and video data.

The volatile memory 1012 mainly stores acquired information and various data used in the processing of each section in the MCU 1010. The communication processing section 1014 is a device equipped with a communication interface, and communicates with the outside of the display device 1 based on a communication protocol conforming to CAN, LIN, or the like. The communication processing section 1014 may be integrated with the vehicle information acquisition section.

The components of the control device in FIG. 3 and FIG. 4 may be implemented as appropriate by dedicated circuits such as a field programmable gate array (FPGA). In this embodiment, the device is configured to have a non-volatile memory 1011 and a volatile memory 1012, but the above processing may be performed by a single memory.

Next, the video display unit 200 will be described in detail. The video display unit 200 or video display unit 200 includes an image forming unit PGU1 that projects video light. The image forming unit PGU1 displays an image based on video data and projects the video light of the displayed image. The image forming unit PGU1 includes a light source 20 and a display panel 11 such as a liquid crystal panel LCD (Liquid Crystal Display) having video display elements.

The image forming unit PGU1 is a projector (projection type image display device) that projects the image light of an image formed on the display panel 11 using light emitted from a light source 20 (in other words, light source light). The light source 20 is typically configured to include an LED (Light Emitting Diode).

The display panel 11 creates an image based on the image data and displays it on the display screen of the display panel 11. The image data in this embodiment will be described as image data input from the image processing unit (1013, 1015). The display panel 11 forms an image to be projected onto the display area 5 by modulating the transmittance of light from the light source 20 for each pixel according to the image data, and projects it as image light (in other words, projection light).

The display panel 11 is not limited to a liquid crystal panel, but may be a screen plate with a diffusion function. Means for projecting an image onto a screen plate with a diffusion function may include a means for projecting an image of a DMD (Digital Micromirror Device) or a liquid crystal panel in combination with a projection lens, or a means for using Micro Electro Mechanical Systems.

The light source 20 is configured, for example, using a semiconductor light source element, and generates a predetermined light source light and supplies it to the display panel 11. The light source 20 functions as a backlight light source for the display panel 11. A representative semiconductor light source element is an LED (Light Emitting Diode) element. The light source 20 may be configured with an array of multiple light sources.

The backlight section is configured using light sources 20, etc. Specific configuration examples of the backlight section will be described later.

The image light emitted from the display panel 11, in other words the projection light, travels toward the display area 5 of the windshield 3. The user of the display device 1 can therefore view the image light as a virtual image. This allows the driver to view the image light projected onto the display area 5 as a virtual image beyond the transparent windshield 3, superimposed on the scenery outside the vehicle (e.g. roads, buildings, people, etc.). There are various types of virtual images that are projected images, such as road signs, the current speed of the vehicle, and various types of information added to objects in the scenery. This allows for the realization of an augmented reality (AR) function that adds and displays various types of information to objects in the scenery.

However, sunlight may enter the display device 1 and reduce visibility. Next, we will specifically explain the technology that aims to prevent the reduction in visibility caused by sunlight.

In other words, as shown in FIG. 5, an image of information, an alert, etc. to be displayed as a virtual image 10 is generated on a display panel 11 such as an LCD, and the image generated on the display panel 11 is projected as image light rays 13 using a light source in the backlight section. The image light rays 13 are reflected by the windshield 3 and enter the eye box 14, allowing the driver to recognize the virtual image 10.

Here, as an example, the position (X, Y, Z) of the display panel 11 is roughly determined based on the angle of the windshield 3, the depression angle with respect to the virtual image 10 based on the position of the eye box 14, and the virtual image distance, which is the distance between the eye box 14 and the virtual image 10. At this time, the display panel 11 is placed, for example, on or inside the dashboard of the vehicle 2, but when external light such as sunlight is reflected by the display panel 11 and enters the eye box 14, the external light such as sunlight becomes unnecessary stray light, which can deteriorate visibility. Here, for example, if a cover or the like is provided around the display device 1 to prevent sunlight from entering, the cover or the like may block the optical path of the image light 13, making it possible for the virtual image 10 to become invisible, and it is not easy to take complete measures against external light.

As shown in Figure 5, by tilting the display panel 11 toward the driver, the following effects (1) to (3) can be obtained.

(1) By tilting the display panel 11 at an appropriate angle and taking measures to keep external light such as the sun's rays 15 out of the eye box 14, it is possible to prevent external light such as the sun's rays 15 from reflecting off the display panel 11 and causing a deterioration in visibility. In other words, measures are taken to prevent stray light caused by regular reflection.

(2) The energy from the sun 16 and the light from the backlight cause the display panel 11 to heat up, which can lead to component failures such as a decrease in brightness due to temperature characteristics and screen burn. Here, the greater the inclination of the display panel 11, the less solar energy is incident on the display panel 11, and measures against heat exposure to the display panel 11 can be implemented.

(3) By tilting the display panel 11, the length of the display device 1 in the vehicle's fore-and-aft direction is shortened, making it easier to mount the display device 1, for example, on top of or inside a narrow dashboard. In other words, the freedom of layout is improved.

Next, referring to Figures 6 and 7, an example of the configuration of the image forming unit will be described. The image forming unit or image display unit includes a light source unit 12a and a display panel 11. As shown in Figure 6A, the light source unit 12a may be referred to as a backlight unit. The light source unit 12a includes a light source 20, a reflecting mirror 21, a polarization conversion element 22, and a light guide unit 23a, and may also include a diffuser plate 24. The reflecting mirror 21 is used to reflect light from the light source 20 and control it to parallel light. The reflecting surface of the reflecting mirror 21 is a parabolic surface, and may have an asymmetric shape with respect to the optical axis of the light emitted from the light source 20. The reflecting mirror 21 may also be disposed eccentrically with respect to the light source 20. The reflecting mirror 21 may be referred to as a reflecting unit or a reflector. The polarization conversion element 22 is composed of a polarizing beam splitter (PBS) and a phase difference film (1/2λ), and separates the incident light into S-polarized light and P-polarized light, and converts the polarization of either the separated S-polarized light or P-polarized light using a phase difference film (1/2λ), and outputs the randomly polarized light incident on the polarization conversion element 22 as linearly polarized light. In this embodiment, the polarization conversion element 22 aligns the polarization of the light emitted from the light source 20, thereby improving the efficiency of image projection.

The light guide 23a is configured to adjust the angle of incidence of light rays on the display panel 11, and in this example, is configured using a light reflecting section 60 having a prism shape (jagged shape). The light guide 23a may be a prism sheet, for example. In this example, the light rays incident on the light reflecting section 60 of the light guide 23a are adjusted to a predetermined light distribution and reflected toward the display panel 11. The distribution of light incident on the display panel 11 can be adjusted by the shape of the reflecting surface of the light reflecting section 60, the inclination of the reflecting surface, the surface roughness, etc. Therefore, in the structure of FIG. 6A, the direction of the light rays of the light source 20 is as shown in the figure, for example. In this structure, the optical axis of the light source 20 and the optical axis of the light incident on the display panel 11 are parallel or approximately parallel. The light guide 23a is, for example, a resin member having a prism shape, and the prism-shaped part that becomes the reflecting surface is coated with an Al reflective film or the like. As shown in FIG. 6A, the light reflecting section 60 of the light guide section 23a may be configured to have multiple inclinations on one surface in order to adjust the reflected light with higher precision. In addition, the reflecting surface may be configured with multiple or multifaceted surfaces, or may be configured with a curved surface, as shown in FIG. 6B. The diffuser plate 24 uniformly disperses the incident light from the light guide section 23. The diffuser plate 24 has the effect of improving the luminance uniformity within the virtual image plane.

FIG. 6B shows an enlarged view of the light reflecting section 60 of the light guide section 23a. The light reflecting section 60 has a number of reflective surfaces and connecting surfaces formed alternately in a sawtooth shape, and the light incident on the light guide section 23a is reflected on each reflective surface and directed upward, and then enters the display panel 11 after being adjusted to a predetermined light distribution characteristic via the diffuser plate 24. The reflection surface elevation angles α1a, α2a, α3a, α4a... are set arbitrarily to obtain a predetermined light distribution characteristic, while the relative angles β1a, β2a, β3a, β4a... between the reflection surfaces and the connecting surfaces are set to a constant angle regardless of location, and more preferably, to an angle of 90 degrees or more (βna≧90°). When the light guide section 23a is manufactured by injection molding, setting the relative angle βna to 90 degrees or more makes it easier to mold the reflection surfaces and the connecting surfaces.

By appropriately setting the lengths and ratios of the connecting surfaces Lc1a, Lc2a, Lc3a, etc. and the reflecting surfaces Lr1a, Lr2a, Lr3a, etc., it is possible to realize a light source unit that can change the irradiation range of the light reflected by the light guide unit 23a to the size (surface size) required for a device such as the display panel 11. In addition, by appropriately adjusting the ratio Lr/Lc, it is possible to partially strengthen or weaken the reflected light. For example, the ratio Lr/Lc is adjusted according to the intensity distribution of the light incident on the light reflecting unit 60. More specifically, in the places in the light reflecting unit 60 where the intensity of the incident light is strong, the ratio Lr/Lc is made small, that is, the reflecting surface elevation angle αna is set at a fine pitch, thereby precisely controlling the light reflection direction and uniformly adjusting the brightness distribution of the light incident on the display panel 11.

In FIG. 6A, a reflecting mirror 21 is used for parallel light control, but a configuration as shown in FIG. 7 may also be used. That is, as shown in FIG. 7, the light source unit 12b includes a light source 20, a lens 25, a polarization conversion element 22, and a light guide unit 23b. The incident light emitted from the light source 20 and converted into parallel light by the lens 25 is polarized by the action of the polarization conversion element 22 and enters the light guide unit 23b, and the light reflected by the light guide unit 23b is emitted toward the display panel 11. The light source unit 12b includes a lens 25 (collimator lens) for parallel light control instead of the reflecting mirror 21. In addition, in this light source unit 12b, the light source 20 is arranged so as to emit light toward the lens 25. The lens 25 controls the light from the light source 20 to be parallel light.

In addition, in FIG. 6, the light guide 23a is configured to bend the light toward the display panel 11 by a light guide having a prism shape, but the light guide 23a may be configured as shown in FIG. 7. That is, as shown in FIG. 7, the light guide 23b may be configured to be made of a transparent material such as resin or glass, and to include a light entrance section 26, a light reflecting section 27, and a light exit section 28, and to control the light distribution based on the shapes of these three surfaces. In this case, the light from the light source 20 may be reflected by total reflection in the reflecting section 27, or may be reflected by an Al reflective film coated on the reflective surface. In the structure of FIG. 7, the direction 30 of the backlight light is, for example, as shown in the same figure. In this structure, the optical axis of the light source 20 and the optical axis of the light incident on the display panel 11 are approximately perpendicular to each other.

7 has the function of internally reflecting and refracting light taken in from the light source 20 as parallel light through the lens 25 and the polarization conversion element 22 at the entrance 26 and directing it in the desired direction, as well as extracting it as planar light having a desired area. The light guide 23b includes a light entrance 26 of the light guide that faces the exit surface of the polarization conversion element 22, a light reflecting portion 27 that forms an inclined surface, and a light exit 28 that outputs light to the display panel 11. At the light entrance 26 of the light guide 23b, the main light ray is deflected by a predetermined angle in a direction that increases the angle of incidence with respect to the light reflecting portion 27. That is, the light entrance 26 is formed in a curved convex shape that is inclined toward the light source 20. In the light reflecting section 27, a large number of reflecting surfaces and connecting surfaces are alternately formed in a sawtooth shape, and the light incident on the light guiding section 23b is reflected on each reflecting surface and directed upward, and further, is adjusted to a predetermined light distribution characteristic through the light emitting section 28 and the diffusion plate 24 and is incident on the display panel 11. In addition, the reflecting surface elevation angles α1b, α2b, α3b, α4b... are set so that each reflecting surface is an angle equal to or greater than the critical angle with respect to the incident light, while the relative angles β1b, β2b, β3b, β4b... between the reflecting surface and the connecting surface are set to a constant angle regardless of the location, more preferably, an angle equal to or greater than 90 degrees (βnb≧90°). When the light guiding section 23b is manufactured by injection molding, the relative angle βn is set to 90 degrees or more, which makes it easier to mold the reflecting surface and the connecting surface. Since each reflecting surface is configured to always have an angle equal to or greater than the critical angle with respect to the incident light, total reflection is possible without forming a reflective film such as a metal film on the light reflecting portion 27, and a light source device having a light guide portion 27 that guides light in the desired direction and extracts it as a planar light having a desired area can be realized at low cost. On the other hand, in a structure in which a reflective film is formed on the light reflecting portion 27, the angle of incidence on the reflective surface can be set arbitrarily, increasing the degree of freedom in designing the light guide portion 23b.

By appropriately setting the lengths and ratios of the connecting surfaces Lcb1, Lcb2, Lcb3, etc. and the reflecting surfaces Lrb1, Lrb2, Lrb3, etc., the length of the light emitting section 28 in the optical axis direction can be freely changed, so that it is possible to realize a light source section in which the size (surface size) of the light emitting section 28 can be changed to the size (surface size) required for a device such as the display panel 11 with respect to the light incident section 26. In addition, by appropriately adjusting the ratio Lr/Lc, it is also possible to partially strengthen or weaken the reflected light. For example, the ratio Lr/Lc is adjusted according to the intensity distribution of the light incident on the light reflecting section 27. More specifically, in the places in the light reflecting section 27 where the intensity of the incident light is strong, the ratio Lr/Lc is made small, that is, the reflecting surface elevation angle αnb is set at a fine pitch, so that the light reflection direction can be precisely controlled and the luminance distribution of the light incident on the display panel 11 can be uniformly adjusted.

For example, the light source unit may have a structure in which light guide section 23b is provided instead of light guide section 23a in the structure of FIG. 6. Also, the light source unit may have a structure in which light guide section 23a is provided instead of light guide section 23b in the structure of FIG. 7.

In addition, in Figures 6 and 7, angle 40 (θ1) indicates the angle at which display panel 11 is tilted with respect to the horizontal plane when display device 1 is mounted in order to protect against sunlight, and the angle between display panel 11 or diffusion plate 24 and the exit surface of the light guide may be different from this angle 40 (θ1). Therefore, when display device 1 is mounted, the exit portion of the light source does not have to be parallel to the horizontal plane.

Angle 41 (θ2) indicates the emission angle of the image light emitted from the display panel 11, and angle 43 (θ2) indicates the incidence angle of the image light (or backlight light) incident on the display panel 11. These angles (41, 43) are determined based on a perpendicular line 44 of the display panel 11, and angles 41 and 43 are equal. The relationship between angles 40 (θ1), 41 (θ2), 43 (θ2), etc. will be explained in detail later.

As shown in FIG. 8, the light source unit may have a structure including a prism-shaped optical component 31 through which light that has been controlled to be parallel by the lens 25 passes. That is, a structure may be adopted in which the light rays bent by the optical component 31 are incident on the light guide component of the light guide unit 23a or the reflecting surface of the light reflector 27. Also, as shown in FIG. 9, the parallel light control unit including the light source 20 may be tilted, and the angle 32 of the light source 20 may be adjusted (set) to, for example, be an optimal angle. Similarly, the reflecting mirror 21 may be tilted to change its orientation.

Next, angles θ1, θ2, and θ3 will be explained with reference to Figures 10 and 11.

As shown in FIG. 10, the emission surface side of the display panel 11 faces the driver, and the angle between the display panel 11 and a horizontal plane in the horizontal or lateral direction of the vehicle is angle 40 (θ1). That is, angle 40 (θ1) is the inclination of the display panel 11 with respect to the horizontal plane. Angle 41 (θ2) is the emission angle of the image light with respect to a perpendicular line 44 of the display panel 11, and angle 43 (θ2) is the incident angle of the image light (or backlight light) with respect to the perpendicular line of the display panel 11. Angle 42 (θ3) determines the angle of the windshield 3 with respect to the horizontal plane.

In addition, in explaining the angular relationship, as shown in Figures 10 and 11, the emission angle of the image light ray 13 from the display panel 11 when the image light 13 is emitted from the display panel 11 is expressed as a positive numerical value. Also, as shown in Figure 11, the angle 41 (θ2) and the angle 43 (θ2) between the vertical direction (perpendicular line 44) of the display panel 11 and the image light are equal to each other. In other words, there is a relationship of emission angle 41 (θ2) = incidence angle 43 (θ2).

For example, when designing to project a virtual image with FoV: 11 x 4 [deg], virtual image distance: 1100 [mm], depression angle: 5.5 [deg], and eye box 14: 150 x 70 [mm], the angles are set as shown in (1) to (3) below, as an example.
(1) The inclination angle 40 (θ1) of the display panel 11 with respect to the horizontal plane is 60 degrees, and the incidence angle 43 (θ2) of the image light (or backlight light) with respect to the display panel 11 is +26 degrees.
(2) The inclination angle 40 (θ1) of the display panel 11 with respect to the horizontal plane is 31 degrees, and the incidence angle 43 (θ2) of the image light (or backlight light) with respect to the display panel 11 is +2 degrees (almost vertical).
(3) The inclination angle 40 (θ1) of the display panel 11 with respect to the horizontal plane is 14.5 degrees, and the incidence angle 43 (θ2) of the image light (or backlight light) with respect to the display panel 11 is −19 degrees.

As shown in FIG. 10, the inclination of the display panel 11 in the horizontal and vertical directions of the vehicle is the angle between the light incident surface of the display panel 11 and the horizontal plane. If it is desired to increase the inclination of the display panel 11, the backlight unit 12 is designed so that the light incident angle from the backlight unit 12 (in other words, the exit angle from the display panel 11) is in the + direction (the direction indicated by the symbol θ+ in FIG. 11).

Next, an example of the usage of the display device 1 will be described with reference to Figs. 12 and 13. Fig. 12 shows an example of the usage when the inclination of the display panel is small. Fig. 13 shows an example of the usage when the inclination of the display panel is large.

As shown in FIG. 12, when the inclination of the display panel 11 is small, the length 51 of the display panel 11 along the vehicle longitudinal direction, in other words the range of sunlight 15 incident on the display panel 11 or the length of sunlight received, becomes large, and more sunlight enters the display panel 11. As a result, the display panel 11 absorbs sunlight 15 from the sun 16 and image light and becomes hot, which is thought to cause, for example, a decrease in brightness due to temperature characteristics, and failures such as burning.

Furthermore, as the length 51 becomes larger, physical interference 55 occurs in the area 53 where meters, instruments, etc. are arranged, and the placement location of the display device 1 may be limited. Furthermore, as the length 51 becomes larger, interference occurs inside the dashboard 52, and from this viewpoint as well, the placement location of the display device 1 is limited.

For this reason, it is preferable to increase the inclination of the display panel 11 and decrease the length 51 of the display panel 11 along the vehicle longitudinal direction. In the example of FIG. 12, the installation angle (θ1) of the display panel 11 is set to 31 degrees, and the area of the display panel 11 is set to 204 mm × 65 mm. The length 51 of the display panel 11 along the vehicle longitudinal direction is 65 mm × cos(31°), which is approximately 56 mm.

As shown in FIG. 13, when the inclination of the display panel 11 is large, the length 54 of the display panel 11 along the vehicle longitudinal direction, in other words, the range of sunlight 15 incident on the display panel 11, or the length of sunlight reception, becomes small. This reduces the amount of solar energy received by the display panel 11 from the sun 16, and reduces the effect of the sunlight 15 on the display panel 11. In other words, deterioration of the display panel 11 due to sunlight incidence can be suppressed, and the reliability of the display device 1 can be improved.

In addition, by reducing the length 54, it becomes easier to position the display device 1 so that there is no physical interference with the area 53 where meters, instruments, etc. are arranged. It also becomes easier to position the display device 1 so that there is no interference inside the dashboard 52. From this perspective, it is possible to improve the freedom of layout.

For example, by reducing the length 54, the display device 1 can be easily mounted on a narrow dashboard 52 or inside the dashboard 52. Here, the display device 1 may be provided so that the upper surface of the dashboard 52, in which the opening is formed, and the surface of the display panel 11 are flush with each other. Furthermore, when the display panel 11 is disposed inside the dashboard 52, a translucent cover may be provided over the opening of the dashboard 52.

In the example of FIG. 13, the installation angle (θ1) of the display panel 11 is set to 60 degrees, and the area of the display panel 11 is set to 202 mm × 73 mm. The length 54 of the display panel 11 along the vehicle front-rear direction is 73 mm × cos(60°), which is approximately 42 mm.

It is preferable that the display panel 11 of the display device 1 is positioned so that it is not directly visible to the driver 50. Therefore, as shown in Figures 12 and 13, it is preferable that meters, instruments, etc. are positioned in the line of sight 56 of the driver 50 toward the top end of the display panel 11, and the display device 1 is provided so that the display panel 11 is hidden from the line of sight 56 of the driver 50. Alternatively, the HUD device 1 may be stored inside the dashboard 52. In this manner, when the HUD device 1 is positioned so that it is not directly viewed by the driver 50, it is possible to prevent stray light caused by external light entering the HUD device 1 being reflected by the display panel 11 and directly entering the eyes of the driver 50.

Next, the relationship between the angles (θ1, θ2, θ3) will be explained with reference to Figures 14 to 16. The meanings of angles θ1, θ2, and θ3 are as explained above with reference to Figures 10 and 11. Note that the six line graphs shown in Figure 14, from the bottom line graph, are data for θ3=25°, θ3=30°, θ3=35°, θ3=40°, θ3=45°, and θ3=50°.

As shown in FIG. 14, as a sunlight protection measure by tilting the display panel 11, it is preferable that the tilt angle θ1 of the display panel 11 with respect to the horizontal plane is 30° or more. To explain more specifically with reference to FIG. 15, by setting the angle θ1 to 30°, the sunlight receiving length (i.e., the vertical length of the display panel 11 × cos(θ1)) is shortened by about 10% compared to when the display panel 11 is not tilted (θ1 = 0°), and the sunlight energy entering the display panel 11 can be reduced by about 10%. Furthermore, when the angle θ1 is less than 30°, the decrease in the sunlight receiving length is gradual, but when the angle θ1 is 30° or more, the decrease in the sunlight receiving length becomes linear, and good sunlight protection measures can be realized.

By tilting the display panel 11, the virtual image size (FoV) becomes smaller (more specifically, the vertical size of the virtual image becomes smaller). Here, from the viewpoint of suppressing a decrease in FoV, it is preferable that the incident angle or emission angle θ2 of the image light (or backlight light) with respect to the display panel 11 is 40° or less. To explain this in detail with reference to FIG. 16, when the angle θ2 is in the range of 40° or less, the decrease in the virtual image size (FoV) is gradual, but when the angle θ2 is in the range of 40° or more, the decrease in the virtual image size becomes linear, and the decrease in the virtual image size as the angle θ2 increases becomes larger. Therefore, as shown in FIG. 14, it is preferable that the angle θ2 is 40° or less.

Note that when the relationship between the angle θ1 of the display panel 11 with respect to the horizontal plane and the windshield angle θ3 with respect to the horizontal plane shown in FIG. 14 is θ1≧90°-θ3, that is, when the perpendicular line of the display panel 11 intersects with the roof of the vehicle 2, the roof of the vehicle 2 blocks sunlight and sunlight does not enter from the front of the display panel 11. FIG. 17 shows the relationship between the angle θ1 of the display panel 11 with respect to the horizontal plane and the angle θ3 of the windshield with respect to the horizontal plane is θ1=90°-θ3, where the perpendicular line of the display panel 11 and the windshield 3 are parallel or approximately parallel, and the roof of the vehicle 2 blocks sunlight that is incident on the front of the display panel 11. Furthermore, when θ1>90°-θ3, the perpendicular line of the display panel 11 falls toward the rear of the vehicle and intersects with the roof of the vehicle 2. Therefore, when the sun 16 is located in front of the display panel 11, sunlight is blocked by the roof of the vehicle 2.

On the other hand, if the incident angle or exit angle θ2 of the image light (or backlight light) with respect to the display panel 11 becomes too large, the brightness or contrast of the image may decrease due to a decrease in transmittance, due to the characteristics of the display panel 11. Therefore, as shown in FIG. 14(A), it is preferable to set the angle θ2 to 50° or less.

Furthermore, as shown in FIG. 14, the angle θ1 of the display panel 11 relative to the horizontal plane and the angle of incidence or exit θ2 of the image light (or backlight light) relative to the display panel 11 differ depending on the inclination angle θ3 of the windshield relative to the horizontal plane; the smaller the angle θ3, the easier it tends to be to suppress reduction in the FoV; in other words, it was found that the smaller the angle θ2 is and the easier it is to set the angle θ1 large while suppressing reduction in the FoV.

From the above viewpoint, the relationship between the tilt angle θ1 of the display panel 11 with respect to the horizontal plane, the incident angle θ2 of the image light (or backlight light) with respect to the display panel 11 or the exit angle θ3 of the image light, and the angle θ3 of the windshield with respect to the horizontal plane may be, for example, as follows:
(1) Windshield inclination (θ3): When θ3 is 25 to 30 degrees, θ1 is 30 degrees to 80 degrees, and θ2 is −5 degrees to 40 degrees.
(2) Windshield inclination (θ3): 30 to 35 deg, θ1: 30 to 70 deg, θ2: 5 to 50 deg
(3) Windshield inclination (θ3): 35 to 40 [deg], θ1: 30 [deg] to 60 [deg], θ2: 15 [deg] to 50 [deg]
(4) Windshield inclination (θ3): When θ3 is 40 to 45 degrees, θ1 is 30 degrees to 50 degrees, and θ2 is 25 degrees to 50 degrees.
(5) Windshield inclination (θ3): When θ3 is 45 to 50 degrees, θ1 is 30 degrees to 40 degrees, and θ2 is 35 degrees to 50 degrees.

Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and includes various modified examples and equivalent configurations within the spirit of the appended claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to having all of the configurations described. Also, for example, other configurations may be added to, deleted from, or substituted for part of the configuration of the embodiments.

For example, the portion of the windshield 3 onto which the image light is projected may have a black film attached to the inside of the vehicle, or black ceramic may be applied to the inside of the vehicle, so that the background of the projected image is black. Having a black background for the image increases the contrast between the image brightness and the background brightness, improving the driver's visibility of the image. Even in this case, tilting the display panel 11 towards the driver can improve layout freedom by shortening the vehicle's fore-and-aft direction.

The vehicle 2 (vehicle) on which the display device 1 is mounted is typically an automobile.

In the technology of this embodiment, the display panel is tilted toward the driver with respect to the windshield, which provides a solar protection measure, displays a good virtual image, and provides an information display device (head-up display device) that reduces the driver's viewpoint movement and contributes to supporting safe driving, thereby making it possible to prevent traffic accidents. This contributes to the "3 Good Health and Well-Being for All" of the Sustainable Development Goals (SDGs) advocated by the United Nations.

1. Display device (virtual image display device)
11 Display panel

Claims (9)

A display panel capable of emitting image light onto a windshield of a vehicle;
a light source that emits light to the display panel;
the display panel faces a driver's side of the vehicle;
A display device, characterized in that the display panel is disposed at an angle with respect to a horizontal plane. The display device according to claim 1 ,
The angle between the display panel and the horizontal plane is 30° or more.
A display device comprising: The display device according to claim 1 ,
When the emission angle of the image light from the display panel when the image light is emitted from the display panel toward the vehicle front side from the perpendicular line of the display panel, is expressed as a positive numerical value,
The emission angle of the image light from the display panel is equal to or greater than -5° and equal to or less than 50°.
A display device comprising: The display device according to claim 1 ,
When the emission angle of the image light from the display panel when the image light is emitted from the display panel toward the vehicle front side from the perpendicular line of the display panel, is expressed as a positive numerical value,
The emission angle of the image light from the display panel is equal to or greater than -5° and equal to or less than 40°.
A display device comprising: The display device according to claim 3,
The angle of the windshield with respect to the horizontal plane is greater than or equal to 25° and less than or equal to 50°.
A display device comprising: The display device according to claim 4,
The angle of the windshield with respect to the horizontal plane is greater than or equal to 25° and less than or equal to 50°.
A display device comprising: The display device according to claim 1 ,
The display panel is disposed in the vehicle so as to be hidden from the driver's view.
A display device comprising: The display device according to claim 1 ,
The display panel is positioned so that a perpendicular line of the display panel intersects with the roof of the vehicle.
A display device comprising: A vehicle equipped with a display device according to any one of claims 1 to 8.