WO2014021093A1 - Display system - Google Patents

Description

Display system

The present invention relates to a display system. More specifically, the present invention relates to a display system suitable for a portable terminal having a touch panel or a protective plate, digital signage, and the like.

In recent years, a display device such as a liquid crystal display device has been developed in various sizes such as a portable terminal to a digital signage, and the use of a display system used outdoors or semi-outdoors has attracted particular attention.

In these display systems, a touch panel as an input device or a protective plate for protecting the display device is often provided on the front side of the display device, that is, the viewer side.

A liquid crystal display device usually includes a pair of linear polarizing plates. Therefore, the light (display light) emitted from the screen of the liquid crystal display device is usually linearly polarized light.

As a conventional liquid crystal display device, for example, a liquid crystal layer, a polarizing plate disposed closer to the display image viewer than the liquid crystal layer, and a fiber and a matrix disposed closer to the display image viewer than the polarizing plate There has been disclosed a liquid crystal display device including a depolarization layer made of a depolarization material containing a material (see, for example, Patent Document 1).

In addition, an optical retardation element having a liquid crystal layer with a high-definition alignment pattern is disclosed (for example, see Patent Document 2).

Further, various electrode patterns in a capacitive touch panel have been disclosed (see, for example, Patent Documents 3 to 5).

Various types of touch panels have been disclosed (see, for example, Non-Patent Document 1).

In addition, the following disclosure is made regarding the birefringence of the resin (for example, see Non-Patent Document 2).
The birefringence of the resin is basically attributed to the structure of the monomer unit, but in the bulk state of a completely amorphous polymer, the structural unit is oriented at random, so it exhibits birefringence on a macro scale. Absent. However, in general, since a polymer material is commercialized through a molding process such as injection molding, it exhibits birefringence due to stress or the like. In this, the orientation birefringence is expressed by the product of the intrinsic birefringence of the polymer (Table 1 below) and the orientation coefficient of the polymer chain (Equation (1)), whereas the birefringence based on stress. The rate is represented by the product of the photoelastic constant and the stress (formula (2)).
Δn = Δn ₀ · f (1)
In the formula (1), Δn represents an orientation birefringence, Δn ₀ represents an intrinsic birefringence, and f represents an orientation distribution function.
Δn = C · σ (2)
In formula (2), Δn represents a stress birefringence, C represents a photoelastic constant, and σ represents stress.

Furthermore, the result of having measured the wavelength dependence of the photoelastic coefficient of various resin materials is disclosed (for example, refer nonpatent literature 3).

And the correlation of the spatial frequency in human visual characteristics and contrast sensitivity is disclosed (for example, refer nonpatent literature 4).

JP 2008-310309 A JP 2005-49865 A JP 2010-61502 A JP 2010-262529 A JP 2011-237839 A

Koji Hattori, “Touch Panel”, p. 4-9, 11, [online], Kyushu University Center for Industry-Academia Collaboration, [Search July 20, 2012], Internet <URL: http://www.astec.kyushu-u.ac.jp/hat-lab /FPD/TouchPanel.pdf> Fumio Ide and 20 others, “Development of the latest optical resins, characteristics and design of high-precision parts, molding technology”, Technical Information Association, September 9, 1993, p. 7-9 “Measurement method of wavelength dependence of photoelastic coefficient”, [online], Oji Scientific Instruments Co., Ltd. [searched on July 20, 2012], Internet <URL: http://www.oji-keisoku.co. jp / products / kobra / img / sample02.pdf> “Spatial frequency characteristics”, “Visual MTF”, [online], Teikyo University, [searched on July 23, 2012], Internet <URL: http://www.med.teikyo-u.ac.jp/ ~ ortho / med / reh / mtf.htm>

Here, the display system of the comparative form 1 examined by the present inventor will be described. As shown in FIG. 24, the display system 101 of the comparative form 1 includes a liquid crystal display device 1010 capable of color display and a capacitive touch panel 1030 disposed on the viewer side of the liquid crystal display device 1010. The display device 1010 includes a pair of substrates 1011 and 1012 and a pair of linearly polarizing plates 1013 and 1014. The touch panel 1030 includes a transparent substrate 1031 such as a glass substrate and a resin substrate, and a polyethylene terephthalate (PET) film 1032. A Y pattern electrode (not shown) formed between the transparent substrate 1031 and the PET film 1032; and an X pattern electrode (not shown) formed on the surface of the PET film 1032 on the liquid crystal display device 1010 side. have.

When the display system 101 is viewed from a specific direction, a colored striped pattern may be observed, and visual recognition of the display screen may be hindered. The colored striped pattern is easy to see especially when displaying white. The cause will be described below.

Since the liquid crystal display device 1010 includes the linearly polarizing plate 1014, the display light emitted from the liquid crystal display device 1010 is linearly polarized light. Further, the reflectance on the surface of the transparent substrate 1031 has polarization dependency, and the reflectance of P-polarized light becomes 0 at a specific incident angle (Brewster angle) as shown in FIG. Therefore, if there is a transparent member having birefringence between the linearly polarizing plate 1014 and the input-side outermost surface of the touch panel 1030, a colored striped pattern is generated in the vicinity of the Brewster angle. Since the PET film 1032 is a material having a large birefringence, the display system 101 visually recognizes a colored stripe pattern in a specific observation direction as described above. This phenomenon corresponds to a phenomenon in which a colored striped pattern occurs when a PET film is sandwiched between a pair of polarizing plates arranged in crossed Nicols. The linear polarizing plate 1014 corresponds to one polarizing plate, and the transparent substrate 1031 whose surface reflection has polarization dependency corresponds to the other polarizing plate. When the liquid crystal display device 1010 is a monochrome display device, a monochrome stripe pattern is visually recognized.

For other types of touch panels, a transparent substrate (for example, a glass substrate, a resin substrate, etc.) is disposed on the liquid crystal display device to protect the liquid crystal display device, and the transparent substrate has an antireflection film, an antifouling film, and scattering prevention. A film such as a film is often pasted. For these films, a PET film is generally used from the viewpoint of cost, which causes a colored stripe pattern.

In paragraph [0019] of Patent Document 1, when a display image is observed through sunglasses having a polarization function by using a depolarization layer made of a depolarization material containing a fiber and a matrix material. It is described that the coloring of the display image caused by the touch panel can be suppressed. Further, paragraph [0057] of Patent Document 1 describes that the fibers having birefringence are preferably dispersed randomly in a non-oriented state in the matrix material. [0030] describes that the average fiber diameter of the fibers is preferably 0.1 to 100 μm. If the fibers can be oriented randomly in this way, random polarized light (natural light) may be obtained by passing display light (linearly polarized light) through the depolarization layer. However, in the case of fibers, when the orientation of one fiber (or a plurality of fibers in a certain fine region) is determined, it is natural that the surrounding fibers are oriented along the direction of the orientation. Therefore, it is difficult to control the fibers so that they are randomly oriented. For this reason, in the Example described in Patent Document 1, it is considered that a large depolarization performance is not obtained. From the above, it is considered that coloring of the display image caused by the touch panel cannot be sufficiently suppressed depending on the technique described in Patent Document 1. It is also considered difficult to control the fiber orientation in accordance with the required performance.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a display system that can suppress the striped pattern from being visually recognized and can easily control the degree to which the striped pattern is viewed. To do.

In view of the above-mentioned present situation, the present inventor has conducted various studies on a display system that can suppress the striped pattern from being visually recognized and can easily control the extent to which the striped pattern is visually recognized. Pay attention. And by arranging a pattern retardation plate between the polarizing plate and the transparent plate having birefringence, the display light emitted from the polarizing plate can be converted into polarized light having a different polarization state for each fine region. Furthermore, the present inventors have found that since the polarized light is mixed with each other and a state in which the polarization state is eliminated can be realized, the occurrence of the above-described stripe pattern can be suppressed. Moreover, according to the pattern phase difference plate, since the optical performance of each fine region can be easily controlled, it has been found that the degree to which the striped pattern is visually recognized can be easily controlled. As a result of the above, the inventors have conceived that the above problems can be solved brilliantly and have reached the present invention.

That is, according to one aspect of the present invention, a display device having a polarizing plate provided on the viewer side,
A transparent plate disposed on the viewer side of the display device and having birefringence;
It is a display system (henceforth the display system which concerns on this invention) provided with the pattern phase difference plate arrange | positioned between the said polarizing plate and the said transparent plate.

The display system according to the present invention is not particularly limited by other components as long as such components are included as essential elements.

Preferred embodiments of the display system according to the present invention will be described below. Note that the following preferred embodiments may be appropriately combined with each other, and an embodiment in which the following two or more preferred embodiments are combined with each other is also one of the preferred embodiments.

The transparent plate preferably contains a transparent resin. This is because the transparent resin is suitable as a material for the transparent plate.

The transparent resin preferably has an intrinsic birefringence of 0.1 or more and −0.1 or less. When the transparent plate contains such a transparent resin in the display system of Comparative Example 1 described above, the orientation birefringence increases as shown in the above formula (1), and the stripe pattern is easily visible. Therefore, according to this embodiment, it can suppress effectively that a striped pattern is visually recognized.

The transparent resin preferably has a photoelastic coefficient of 30 × 10 ⁻³ cm ² / dyn or more. When the transparent plate contains such a transparent resin in the display system of the above-described comparative form 1, the stress birefringence increases as shown in the above formula (2), and the stripe pattern is easily visually recognized. Therefore, according to this embodiment, it can suppress effectively that a striped pattern is visually recognized. As a method for measuring the photoelastic coefficient, the method described in Non-Patent Document 3 can be employed. That is, first, a test piece of 15 mm × 60 mm is set on a sample tension jig. At this time, the test piece is cut out so that the slow axis is in the tensile direction. Then, the change in the in-plane phase difference of the test piece when the tensile load is increased by 50 gf is measured using a phase difference measuring device KOBRA-WR manufactured by Oji Scientific Instruments, and the result is linearly approximated to obtain the inclination. . Then, the photoelastic coefficient is calculated from the following equation.
Photoelastic coefficient (cm ² /dyn)=slope×1.5×10 ⁻⁹ /9.8

The display system includes a touch panel,
The transparent plate may be included in the touch panel. Thereby, various information can be input and / or selected while seeing through a beautiful display screen in which the stripe pattern is suppressed.

The touch panel system may be a capacitive system. Thereby, a transparent plate can be used as a dielectric and / or a support member for the pattern electrode of the touch panel.

The touch panel system may be a resistive film system. Thereby, a transparent board can be utilized as a flexible film of a touch panel.

The transparent plate may protect the display device.

The pattern phase difference plate preferably includes a plurality of first regions and a plurality of second regions that are alternately arranged in a plan view, and preferably converts the light emitted from the polarizing plate into two polarized light having different phases. . Thereby, it can suppress effectively that a striped pattern is visually recognized.

The phases of the two polarized lights are preferably different from each other by π. Thereby, it can suppress especially effectively that a striped pattern is visually recognized. The phase difference between the two polarized lights can be measured using, for example, a small area elliptical polarization measuring device KOBRA-CCD / PR manufactured by Oji Scientific Instruments. What is necessary is just to measure the light quantity of the light which passed each area | region, rotating an analyzer (polarizing plate).

The display panel has a display area having a vertical length of H,
The pitch between the plurality of first regions and the plurality of second regions is preferably less than 0.0131 × H. Thereby, when the display system which concerns on this invention is observed from the optimal viewing distance, it can suppress effectively that a striped pattern is visually recognized.

The pitch between the plurality of first regions and the plurality of second regions is preferably 1.3 mm or less, and more preferably 0.58 mm or less. Thereby, at the time of operation of a touch panel, it can suppress effectively that a striped pattern is visually recognized.

The touch panel system is a capacitive system,
The touch panel includes two layers of pattern electrodes,
The two-layer pattern electrode includes a wiring group formed like a mesh,
The pitch of the plurality of first regions and the plurality of second regions is preferably equal to or less than the pitch of the wiring group. Thereby, the first and second regions can be made less conspicuous than the wiring group, that is, difficult to be visually recognized.

ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a striped pattern is visually recognized and can implement | achieve the display system which can control easily the grade which a striped pattern is visually recognized.

1 is a schematic cross-sectional view of a display system according to Embodiment 1. FIG. 2 is a schematic cross-sectional view of a touch panel included in the display system of Embodiment 1. FIG. 4 is a schematic plan view of a Y pattern electrode included in the display system of Embodiment 1. FIG. 3 is a schematic plan view of an X pattern electrode included in the display system of Embodiment 1. FIG. It is a cross-sectional schematic diagram of the display system of the comparative form 2. 1 is a schematic cross-sectional view of a display system according to Embodiment 1. FIG. 3 is a schematic perspective view of a polarizing plate and a pattern retardation plate included in the display system of Embodiment 1. FIG. 3 is a schematic perspective view of a polarizing plate and a pattern retardation plate included in the display system of Embodiment 1. FIG. 3 is a schematic perspective view of a polarizing plate and a pattern retardation plate included in the display system of Embodiment 1. FIG. 2 is a schematic plan view of a pattern retardation plate included in the display system of Embodiment 1. FIG. It is the schematic diagram which showed the relationship between the screen size of a display apparatus, and the optimal viewing distance. 5 is a graph showing the correlation between spatial frequency and contrast sensitivity in human visual characteristics. It is a cross-sectional schematic diagram of the display system of Embodiment 2. 10 is a schematic cross-sectional view of a touch panel included in the display system of Embodiment 2. FIG. 6 is a schematic plan view of a Y pattern electrode and an X pattern electrode included in the display system of Embodiment 2. FIG. It is a cross-sectional schematic diagram of the display system of the comparative form 3. 6 is a schematic plan view of a pattern retardation plate included in the display system of Embodiment 2. FIG. It is a cross-sectional schematic diagram of the display system of Embodiment 3. 10 is a schematic cross-sectional view of a touch panel included in the display system of Embodiment 3. FIG. It is a cross-sectional schematic diagram of the display system of the comparative form 4. 10 is a schematic plan view of a display system according to Embodiment 4. FIG. 6 is a schematic cross-sectional view of a display system according to Embodiment 4. FIG. It is a cross-sectional schematic diagram of the display system of the comparative form 5. It is a cross-sectional schematic diagram of the display system of the comparative form 1. It is the graph which showed the relationship between an incident angle and a reflectance about S polarized light and P polarized light.

Embodiments will be described below, and the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to these embodiments.

(Embodiment 1)
As shown in FIG. 1, the display system 1 according to the present embodiment includes a liquid crystal display device 10 capable of color display, a pattern retardation plate 20 disposed on the viewer side of the liquid crystal display device 10, and a pattern retardation plate 20. And a capacitive touch panel 30 arranged on the viewer side.

The liquid crystal display device 10 includes a backlight (not shown), a pair of substrates 11 and 12 arranged on the viewer's side (front) of the backlight, and a liquid crystal layer (see FIG. (Not shown) and a pair of polarizing plates 13 and 14. The display mode of the liquid crystal display device 10 is not particularly limited, and can be set as appropriate. Examples of the display mode of the liquid crystal display device 10 include a vertical alignment (VA) mode and a horizontal alignment mode. The driving method of the liquid crystal display device 10 is not particularly limited, and a simple matrix method (passive matrix method), a plasma address method, or the like may be used. Among these, a TFT method (active matrix method) is preferable.

The polarizing plates 13 and 14 are both linear polarizing plates and have a function of extracting polarized light (linearly polarized light) that vibrates in a specific direction from non-polarized light (natural light), partially polarized light, or polarized light. Therefore, the light (display light) emitted from the screen of the liquid crystal display device 10 is polarized light, particularly linearly polarized light. Examples of the polarizing plates 13 and 14 include absorption linear polarizing plates. Typically, an anisotropic material such as an iodine complex having dichroism is adsorbed and oriented on a polyvinyl alcohol (PVA) film, and the PVA film What laminated | stacked protective films, such as a triacetylcellulose (TAC) film, on both surfaces is mentioned. The polarizing plates 13 and 14 are usually arranged in crossed Nicols. That is, the angle formed by the polarization axis of the polarizing plate 13 and the polarization axis of the polarizing plate 14 is generally designed to be 90 °, and the angle formed by both is within the range of 90 ° ± 1 ° (however, the boundary value is The liquid crystal display device 10 is manufactured. However, the arrangement relationship of the polarizing plates 13 and 14 can be set as appropriate in accordance with the display mode of the liquid crystal display device 10, and may be parallel Nicol.

As shown in FIG. 2, the touch panel 30 has a structure in which an X pattern electrode 34, a transparent plate 32, a Y pattern electrode 33, and a transparent substrate 31 are laminated in this order. The touch panel 30 is usually manufactured by bonding a transparent substrate 31 on which a Y pattern electrode 33 is formed and a transparent plate 32 on which an X pattern electrode 34 is formed.

The reflectance on the surface of the transparent substrate 31 shows polarization dependence, and the reflectance of P-polarized light becomes 0 at a specific incident angle (Brewster angle) as shown in FIG. The material of the transparent substrate 31 is preferably a material having high transparency and high mechanical strength. From such a viewpoint, glass such as tempered glass is suitable. From the viewpoint of weight reduction and cracking, resins such as polycarbonate, acrylic, and polystyrene are suitable.

The pattern electrodes 33 and 34 are generally formed of a transparent conductive material such as indium tin oxide (ITO). For example, the Y pattern electrode 33 is formed in a pattern (stripe shape) as shown in FIG. 3, and the X pattern electrode 34 is formed in a pattern (stripe shape) as shown in FIG. The Y pattern electrode 33 and the X pattern electrode 34 extend in the vertical direction and the horizontal direction of the screen of the liquid crystal display device 10, respectively.

The transparent plate 32 is a transparent flat member and has birefringence (optical anisotropy). The transparent plate 32 functions as an insulator (dielectric) that insulates between the electrodes 33 and 34.

The transparency of the transparent plate 32 is not particularly limited and can be set as appropriate. However, the transparent plate 32 preferably has a degree of transparency that does not significantly adversely affect the visibility of the display system of the present embodiment. . Specifically, the transmittance of the transparent plate 32 is preferably 80% or more, and more preferably 90% or more.

The thickness of the transparent plate 32 is not particularly limited, and can be set as appropriate. The transparent plate 32 may be a so-called transparent film.

The material of the transparent plate 32 is not particularly limited, but a transparent resin is suitable. Specific examples include PET.

As shown in FIG. 5, when the touch panel 30 is arranged on the liquid crystal display device 10 without interposing the pattern retardation plate 20, a colored striped pattern is visually recognized in a specific observation direction. This phenomenon corresponds to a phenomenon in which a colored striped pattern occurs when a PET film having a large birefringence is sandwiched between a pair of polarizing plates arranged in crossed Nicols. The polarizing plate 14 corresponds to one polarizing plate, and the transparent substrate 31 having polarization dependency of surface reflection corresponds to the other polarizing plate.

As the transparent resin for the transparent plate 32, a resin having an intrinsic birefringence of 0.1 or more and −0.1 or less and / or a resin having a photoelastic coefficient of 30 × 10 ⁻³ cm ² / dyn or more. When used, colored stripes are particularly easily visible unless any measures are taken. A transparent resin having an intrinsic birefringence of 0.1 or more or −0.1 or less including PET has a large orientation birefringence, and a photoelastic coefficient including PET is 30 × 10 ⁻³ cm ² / This is because a transparent resin of dyn or more has a large birefringence due to stress generated during molding.

As a method for eliminating the colored stripe pattern, a method of inserting a depolarizing element between the transparent plate 32 and the polarizing plate 14 is effective.

Therefore, in this embodiment, in order to cancel the polarization state of the polarized light (display light) from the liquid crystal display device 10, the pattern phase difference plate 20 is pasted on the surface of the polarizing plate 14 on the touch panel 30 side. As shown in FIG. 6, the pattern phase difference plate 20 has fine regions 21 and 22 (regions corresponding to the first and second regions) arranged alternately, and at least one of the fine regions 21 and 22 is And having the optical anisotropy, the fine regions 21 and 22 have different effects on the polarized light passing therethrough. As a result, the polarized light passing through the fine region 21 and the polarized light passing through the fine region 22 have different polarization states. Since these polarized lights are macroscopically mixed with each other and the polarization state is eliminated (natural light state), the occurrence of the above-described colored striped pattern can be suppressed. A colored stripe pattern does not occur just by arranging a linearly polarizing plate on one side of the PET film, but according to the present embodiment, such a state can be realized in a pseudo manner.

Moreover, according to the pattern phase difference plate 20, the optical performance (refractive index anisotropy, axial direction, etc.) of each of the fine regions 21 and 22 can be easily controlled. Therefore, the degree to which the striped pattern is visually recognized can be easily controlled according to the performance required for the display system 1. Usually, the optical performance of each region can be controlled by orienting a resin (polymer layer) having refractive index anisotropy in each of the fine regions 21 and 22 in a specific direction. The pattern phase difference plate 20 can be produced by a general method. For example, the method described in Patent Document 3 may be used.

Furthermore, according to the pattern phase difference plate 20, the areas of the fine regions 21 and 22 can be easily adjusted. Therefore, the intensity of polarized light that has passed through the fine region 21 and the intensity of polarized light that has passed through the fine region 22 can be made substantially equal to each other.

The pattern retardation plate 20 may completely cancel the polarization state of the display light or may not completely cancel the polarization state. The depolarization performance of the pattern retardation plate 20 can be appropriately set according to the performance required for the display system 1. However, from the viewpoint of effectively suppressing the colored striped pattern from being visually recognized, the phase of polarized light that has passed through the fine region 21 and the phase of polarized light that has passed through the fine region 22 are shifted from each other by approximately π. Preferably it is. In this case, among the polarized light that has passed through the fine region 21, the polarized light that is finally emitted from the surface of the transparent substrate 31, and among the polarized light that has passed through the fine region 22, the polarized light that is finally emitted from the surface of the transparent substrate 31 Are complementary to each other. Since these colored polarized lights are macroscopically mixed to become white, it is possible to effectively suppress the colored striped pattern from being visually recognized. In this case, the combination of the polarized light that has passed through the fine area 21 and the polarized light that has passed through the fine area 22 is typically a combination of two linearly polarized lights whose polarization axes are orthogonal to each other, right circularly polarized light and left circularly polarized light. A combination may be mentioned, but a combination of two elliptically polarized lights whose phases are shifted from each other by approximately π may be used.

As shown in FIG. 7, the fine regions 21 and 22 are alternately arranged in a stripe shape in a plan view, a birefringent layer satisfying a λ / 2 condition is arranged in the fine region 21, and the fine region 22 has An isotropic layer may be disposed. At this time, the birefringent layer in the fine region 21 is formed such that the fast axis thereof forms an angle of approximately 45 ° with the polarization axis of the polarizing plate 14. The display light (linearly polarized light) maintains its state (polarization axis) even when it passes through the isotropic layer, but when it passes through the birefringent layer in the fine region 21, the polarization light is converted into linearly polarized light whose polarization axis is rotated by approximately 90 °. Converted. The angle formed by the fast axis of the birefringent layer in the fine region 21 and the polarization axis of the polarizing plate 14 is preferably in the range of 45 ° ± 1 ° (including the boundary value).

As shown in FIG. 8, the fine regions 21 and 22 are alternately arranged in a stripe shape in plan view. In the fine region 21, the first birefringent layer satisfying the λ / 2 condition is arranged, and in the fine region 22. May be provided with a second birefringent layer that satisfies the condition λ / 2. At this time, the first birefringent layer is formed such that the fast axis thereof forms an angle of approximately 22.5 ° with the polarization axis of the polarizing plate 14, and the second birefringent layer has the fast axis of the polarizing plate. It is formed so as to form an angle of about −22.5 ° with the 14 polarization axes. When the display light (linearly polarized light) passes through the first birefringent layer, it is converted into linearly polarized light whose polarization axis is rotated by about 45 °, and when it passes through the second birefringent layer, the linearly polarized light whose polarization axis is rotated by about −45 °. Converted to polarized light. The angle formed by the fast axis of the first birefringent layer and the polarization axis of the polarizing plate 14 is preferably in the range of 22.5 ° ± 1 ° (including the boundary value). The angle formed by the fast axis of the second birefringent layer and the polarization axis of the polarizing plate 14 is preferably in the range of −22.5 ° ± 1 ° (including the boundary value).

As shown in FIGS. 9 and 10, the fine regions 21 and 22 are alternately arranged in a stripe shape in a plan view, and in the fine region 21, the first birefringent layer satisfying the λ / 4 condition is arranged, and the fine region 22 may be provided with a second birefringent layer that satisfies the λ / 4 condition. At this time, the first birefringent layer is formed such that the fast axis thereof forms an angle of approximately 45 ° with the polarization axis of the polarizing plate 14, and the second birefringent layer has the fast axis of the polarizing plate 14. It is formed so as to form an angle of about −45 ° with the polarization axis. When the display light (linearly polarized light) passes through the first birefringent layer, it is converted into right circularly polarized light, and when it passes through the second birefringent layer, it is converted into left circularly polarized light. The angle formed by the fast axis of the first birefringent layer and the polarization axis of the polarizing plate 14 is preferably in the range of 45 ° ± 1 ° (including the boundary value). The angle formed by the fast axis of the second birefringent layer and the polarization axis of the polarizing plate 14 is preferably within a range of −45 ° ± 1 ° (including the boundary value).

The planar pattern of the fine regions 21 and 22 is not particularly limited to a stripe shape, and can be set as appropriate. For example, a checker pattern may be used. Further, the direction in which the fine regions 21 and 22 are alternately arranged (hereinafter also referred to as a repeating direction) is not particularly limited to the vertical direction of the screen, and can be set as appropriate. For example, in the state where the screen of the liquid crystal display device 10 is viewed from the front, the horizontal direction or the diagonal direction may be set.

The birefringent layer satisfying the λ / 4 condition is a layer having a retardation of approximately ¼ wavelength with respect to visible light (light having a wavelength of 400 nm to 800 nm), and an in-plane retardation of 100 nm or more and 200 nm or less. R is included. A layer having a retardation of about ¼ wavelength with respect to light having a wavelength of 500 nm to 600 nm is preferable, and preferably has an in-plane retardation R of 125 nm or more and 150 nm or less.

Further, the birefringent layer satisfying the λ / 2 condition is a layer having retardation of approximately ½ wavelength with respect to visible light (light having a wavelength of 400 nm to 800 nm), and an in-plane retardation of 200 to 400 nm. R is included. Preferably, it is a layer having retardation of approximately ½ wavelength with respect to light having a wavelength of 500 nm to 600 nm, and preferably has an in-plane retardation R of 250 nm or more and 300 nm or less.

The isotropic layer means a layer in which both the in-plane retardation R and the absolute value of the thickness direction retardation Rth have a value of 10 nm or less, and preferably have a value of 5 nm or less. .

The in-plane retardation R defines the main refractive index in the in-plane direction of the birefringent layer as nx and ny, the main refractive index in the out-of-plane direction (thickness direction) is nz, and the thickness of the birefringent layer is d. When defined, R = | nx−ny | × d, the in-plane direction phase difference (unit: nm). In contrast, the thickness direction retardation Rth is an out-of-plane direction (thickness direction) phase difference (unit: nm) defined by Rth = (nz− (nx + ny) / 2) × d. However, the directions of nx and ny are orthogonal to each other.

The pitch of each fine region can be set as appropriate, but is preferably set as follows. As shown in FIG. 11, in general, it is optimal to view the screen from a distance of three times (= 3 × H) with respect to the length H in the vertical direction of the screen of the display device. On the other hand, according to Non-Patent Document 4, human visual characteristics have a correlation between spatial frequency and contrast sensitivity as shown in FIG. The contrast sensitivity represents the reciprocal of the contrast threshold, and the spatial frequency represents the number of stripes per 1 degree of diopter. According to this, the contrast sensitivity becomes the highest when there are four striped patterns within a viewing angle of 1 °. If this case is applied to the optimum viewing distance (= 3 × H) of the display device, it corresponds to a striped pattern with a pitch of 0.0131 × H. Therefore, it can be seen that the pitch of each fine region is preferably less than 0.0131 × H.

Assuming that the viewing distance when operating the touch panel 30 is 300 mm, four striped patterns within a viewing angle of 1 ° correspond to striped patterns with a pitch of 1.3 mm. On the other hand, as shown in FIG. 12, when nine striped patterns exist within a viewing angle of 1 °, the contrast sensitivity is halved compared to the case where four striped patterns exist. If this case is applied to a viewing distance of 300 mm, it corresponds to a striped pattern with a pitch of 0.58 mm. Therefore, by setting the pitch of each fine region to 0.58 mm or less, it is possible to effectively suppress the colored striped pattern from being visually recognized when the touch panel 30 is operated.

By the way, in the 3D system of the passive glasses system, a pattern retardation plate is affixed on the screen of the display device, and the fine area of the pattern retardation plate is arranged corresponding to the pixels of the display device. There is a need. In general, the pitch of the fine regions is set to approximately twice the pixel pitch, and the repetition direction is set to the vertical direction of the screen. Therefore, the bonding accuracy is required.

On the other hand, in the present embodiment, the fine regions 21 and 22 of the pattern retardation plate 20 do not necessarily correspond to the pixels of the liquid crystal display device 10. Therefore, the degree of freedom in designing the pitch of each fine region is high. Also, the repeat direction can be set arbitrarily. Therefore, the pattern phase difference plate 20 can be easily installed.

In the 3D system using passive glasses, it is necessary to visually recognize the right eye image and the left eye image separately with the right eye and the left eye using polarized glasses. A member having birefringence, such as a touch panel, cannot be disposed between them. Therefore, the display system 1 of this embodiment is not normally applied to a passive glasses type 3D system.

Here, the result of actually producing and evaluating the display system according to the present embodiment will be described. Here, as shown in FIG. 10, a pattern phase difference plate having two kinds of minute regions alternately arranged in a stripe shape in plan view was used. A birefringent layer satisfying the λ / 4 condition is formed in each fine region, and the fast axis of the birefringent layer in one fine region has an angle of 45 ° with the polarization axis of the polarizing plate on the viewer side. None, the fast axis of the birefringent layer in the other fine region made an angle of −45 ° with the polarization axis. Therefore, this pattern phase difference plate can convert display light (linearly polarized light) into two polarized light whose phases are shifted by approximately π for each fine region. Further, the pitch of the minute regions was 580 μm. A PET film was used as the transparent plate 32. Hereinafter, this display system is referred to as system A.

In System A, the colored striped pattern caused by the birefringence of the PET film, which occurs when the touch panel is disposed on the liquid crystal display device, can be sufficiently eliminated.

The ability to depolarize can be quantified by a value called a contrast value. The method for measuring this contrast is as follows. That is, a member for which a contrast value is to be obtained is arranged between two polarizing plates arranged with axes orthogonal to each other, and the transmitted light amount A of the light beam at that time is measured. On the other hand, a member for obtaining contrast is arranged between two polarizing plates arranged in parallel with each other, and the transmitted light amount B of the light beam at that time is measured. The contrast value is obtained by the transmitted light amount B / the transmitted light amount A (the transmitted light amount when the polarizing plates are arranged in parallel / the transmitted light amount when the polarizing plates are arranged orthogonally). The closer this contrast value is to 1, the higher the depolarization ability.

The contrast value of the pattern retardation plate used in System A was 1.8 when a pair of polarizing plates having a contrast value of 10,000 without using the pattern retardation plate was used.

On the other hand, the contrast value of the depolarizing layer disclosed in Patent Document 1 is 200 in Example 1, 500 in Example 2, 6 to 40 in Example 3, and 500 in Example 4. The depolarizing layer of Example 3 is obtained by stacking five depolarizing elements of Example 2.

As described above, the pattern retardation plate used in the system A had very good depolarization performance as compared with the depolarization layer disclosed in Patent Document 1. For this reason, it is considered that the system A was able to sufficiently eliminate the colored stripe pattern. That is, in order to sufficiently eliminate the colored stripe pattern, the contrast value is preferably 1 or more and 2 or less.

Moreover, in the said depolarization layer disclosed by patent document 1, as mentioned above, it is difficult to control so that a fiber may orient randomly. For this reason, in the Example described in Patent Document 1, it is considered that a large depolarization performance is not obtained.

(Embodiment 2)
As shown in FIG. 13, the display system 2 of the present embodiment includes a capacitive touch panel 230 instead of the touch panel 30, and the pattern phase difference plate 20 is attached to the touch panel 230 instead of the liquid crystal display device 10. The display system 1 is substantially the same as the display system 1 of Embodiment 1. Therefore, here, the features specific to the present embodiment will be mainly described, and the description overlapping with the first embodiment will be omitted.

As shown in FIG. 14, the touch panel 230 has a structure in which a transparent plate 235, an X pattern electrode 234, a transparent plate 232, a Y pattern electrode 233, and a transparent substrate 231 are laminated in this order. The touch panel 230 is usually formed by bonding a transparent plate 232 on which a Y pattern electrode 233 is formed on a transparent substrate 231 and further bonding a transparent plate 235 on which an X pattern electrode 234 is formed on the transparent plate 232. Produced.

The reflectance on the surface of the transparent substrate 231 shows polarization dependence, and the reflectance of P-polarized light becomes 0 at a specific incident angle (Brewster angle) as shown in FIG. The material of the transparent substrate 231 is preferably a material having high transparency and high mechanical strength. From such a viewpoint, glass such as tempered glass is suitable. From the viewpoint of weight reduction and cracking, resins such as polycarbonate, acrylic, and polystyrene are suitable.

The pattern electrodes 233 and 234 include a wiring group (an assembly of a plurality of wirings) formed like a mesh. For example, the pattern electrodes 233 and 234 may be formed by etching copper foil formed on the transparent plates 232 and 235, sputtering silver on the transparent plates 232 and 235, or silver paste on the transparent plates 232 and 235, respectively. It can be formed by printing. The pattern electrodes 233 and 234 are formed, for example, in a pattern (zigzag shape) as shown in FIG. The Y pattern electrode 233 and the X pattern electrode 234 extend in the vertical direction and the horizontal direction of the screen of the liquid crystal display device 10, respectively.

Since the resistance value of ITO is large (for example, about 100 to 150Ω / □), it is difficult to increase the size of the touch panel 30 of the first embodiment. On the other hand, in the present embodiment, since the pattern electrodes 233 and 234 are formed of a metal material and include a mesh-like wiring group, the resistance of the pattern electrodes 233 and 234 can be reduced. Therefore, the touch panel 230 of the present embodiment can be 20 to 30 or more sizes.

The transparent plates 232 and 235 are transparent flat members and have birefringence (optical anisotropy). The transparent plate 232 functions as an insulator (dielectric) that insulates between the electrodes 233 and 234.

The transparency of each of the transparent plates 232 and 235 is not particularly limited and can be set as appropriate. However, each of the transparent plates 232 and 235 is transparent to the extent that the visibility of the display system of the present embodiment is not significantly affected. It is preferable to have properties. Specifically, the transmittance of each transparent plate 232, 235 is preferably 80% or more, and more preferably 90% or more.

The thickness of each transparent plate 232, 235 is not particularly limited and can be set as appropriate. Each of the transparent plates 232 and 235 may be a so-called transparent film.

The material of each transparent plate 232, 235 is not particularly limited, but a transparent resin is suitable. Specific examples include polyethylene terephthalate (PET).

As shown in FIG. 16, when the touch panel 230 is arranged on the liquid crystal display device 10 without the pattern retardation plate 20, a colored striped pattern is visually recognized in a specific observation direction. In the touch panel 230, two transparent plates 232 and 235 having birefringence are laminated, so that the striped pattern is more strongly colored than when the touch panel 30 including one transparent plate 32 is used (in the case of FIG. 5). Occurs.

As a transparent resin for each transparent plate 232, 235, a resin having an intrinsic birefringence of 0.1 or more and −0.1 or less, and / or a photoelastic coefficient of 30 × 10 ⁻³ cm ² / dyn or more In the case of using a resin having a color, a colored striped pattern is particularly easily visible unless any countermeasure is taken.

Therefore, in order to eliminate this colored stripe pattern, in this embodiment, the pattern phase difference plate 20 is pasted on the surface of the transparent plate 235 on the liquid crystal display device 10 side. Thereby, since the polarization state of the polarized light (display light) from the liquid crystal display device 10 can be eliminated, the generation of colored striped patterns can be suppressed as in the first embodiment.

Here, the result of actually producing and evaluating the display system according to the present embodiment will be described. Here, the pitch of the wiring group of the pattern electrodes 233 and 234 is set to 428 μm. This value was determined in consideration of the relationship between the spatial frequency and the contrast sensitivity described above, together with moire fringes caused by interference between the wiring group and the pixels of the liquid crystal display device 10.

Further, as shown in FIG. 17, a pattern phase difference plate having two kinds of minute regions alternately arranged in a stripe shape in plan view was used. A birefringent layer satisfying the λ / 4 condition is formed in each fine region, and the fast axis of the birefringent layer in one fine region has an angle of 45 ° with the polarization axis of the polarizing plate on the viewer side. None, the fast axis of the birefringent layer in the other fine region made an angle of −45 ° with the polarization axis. Therefore, this pattern phase difference plate can convert display light (linearly polarized light) into right circularly polarized light and left circularly polarized light for each fine region. The right circularly polarized light and the left circularly polarized light are mixed with each other and appear to be depolarized macroscopically. Further, the pitch of the minute regions was set to 420 μm, which was smaller than the pitch of the wiring group of the pattern electrodes 233 and 234. As the transparent plates 232 and 235, PET films were used. Hereinafter, this display system is referred to as a system B.

Also in the system B, the colored striped pattern caused by the birefringence of the PET film, which is generated when the touch panel is disposed on the liquid crystal display device, can be sufficiently eliminated. Further, the depolarization performance of the pattern phase difference plate used in the system B was almost the same as that of the pattern phase difference plate used in the system A.

(Embodiment 3)
As shown in FIG. 18, the display system 3 of the present embodiment includes a resistive film type touch panel 330 instead of the touch panel 30, and the pattern retardation plate 20 is attached to the touch panel 330 instead of the liquid crystal display device 10. The display system 1 is substantially the same as the display system 1 of Embodiment 1. Therefore, here, the features specific to the present embodiment will be mainly described, and the description overlapping with the first embodiment will be omitted.

As shown in FIG. 19, the touch panel 330 includes a transparent substrate 331, an electrode 333 formed on the transparent substrate 331, an insulator 336, a transparent plate 332, and an electrode 334 formed on the transparent plate 332. Have. A transparent plate 332 with an electrode 334 is laminated on a transparent substrate 331 with an electrode 333 via an insulator 336. When the surface of the transparent plate 332 is not touched, a predetermined gap exists between the transparent substrate 331 with the electrode 333 and the transparent plate 332 with the electrode 334.

As a material for the transparent substrate 331, a material having high transparency and high mechanical strength is preferable. From such a viewpoint, glass such as tempered glass is preferable. From the viewpoint of weight reduction and cracking, resins such as polycarbonate, acrylic, and polystyrene are suitable.

The electrodes 333 and 334 are generally formed from a transparent conductive material such as indium tin oxide (ITO). The electrodes 333 and 334 are formed on almost one surface of the transparent substrate 331 and the transparent plate 332 without any breaks.

The transparent plate 332 is a transparent flat member and has birefringence (optical anisotropy) and flexibility. When the surface of the transparent plate 332 is touched, the transparent plate 332 is bent by the pressure, and the electrode 334 is in contact with the electrode 333.

The transparency of the transparent plate 332 is not particularly limited and can be set as appropriate. However, the transparent plate 332 preferably has a degree of transparency that does not significantly adversely affect the visibility of the display system of the present embodiment. . Specifically, the transmittance of the transparent plate 332 is preferably 80% or more, and more preferably 90% or more.

The thickness of the transparent plate 332 is not particularly limited, and can be set as appropriate. The transparent plate 332 may be a so-called transparent film.

The material of the transparent plate 332 is not particularly limited, but a transparent resin is suitable. Specific examples include polyethylene terephthalate (PET).

The reflectance on the surface of the transparent plate 332 shows polarization dependence as in the case of the glass substrate, and the reflectance of P-polarized light becomes 0 at a specific incident angle (Brewster angle) as shown in FIG. .

Therefore, as shown in FIG. 20, when the touch panel 330 is arranged on the liquid crystal display device 10 without the pattern retardation plate 20, a colored striped pattern is visually recognized in a specific observation direction.

Therefore, in order to eliminate this colored stripe pattern, in this embodiment, the pattern phase difference plate 20 is pasted on the surface of the transparent substrate 331 on the liquid crystal display device 10 side. Thereby, since the polarization state of the polarized light (display light) from the liquid crystal display device 10 can be eliminated, the generation of colored striped patterns can be suppressed as in the first embodiment.

Moreover, when a PET film was used as the transparent plate 332 and the same pattern retardation plate as that used in the system A was used as the pattern retardation plate 20, the display system according to this embodiment was actually produced. The colored stripes due to birefringence could be eliminated.

(Embodiment 4)
As shown in FIGS. 21 and 22, the display system 4 of the present embodiment includes an infrared touch panel 430 instead of the touch panel 30, further includes a protection plate 440, and the pattern retardation plate 20 is a liquid crystal display. The display system 1 is substantially the same as the display system 1 of the first embodiment except that it is attached to the protective plate 440 instead of the device 10. Therefore, here, the features specific to the present embodiment will be mainly described, and the description overlapping with the first embodiment will be omitted.

As illustrated in FIG. 21, the touch panel 430 includes a light emitting module 437 and a light receiving module 438. The light emitting module 437 and the light receiving module 438 are arranged on the outer periphery of the liquid crystal display device 10, the light emitting module 437 is arranged along two sides of the liquid crystal display device 10, and the light receiving module 438 is the other two of the liquid crystal display device 10. It is arranged along the side. The light emitting module 437 includes a plurality of infrared LEDs, which are arranged along the outer periphery of the liquid crystal display device 10. The light receiving module 438 includes a plurality of infrared sensors, which are arranged along the outer periphery of the liquid crystal display device 10.

The protection plate 440 is disposed so as to cover the liquid crystal display device 10 and the touch panel 430 and protects them. As illustrated in FIG. 22, the protection plate 440 includes a transparent substrate 431 and a transparent plate 432 attached on the transparent substrate 431.

As a material of the transparent substrate 431, a material having high transparency and high mechanical strength is preferable, and glass such as tempered glass is preferable.

The transparent plate 432 is a transparent flat member and has birefringence (optical anisotropy). The transparent plate 432 functions as a scattering prevention film for preventing fragments from scattering when the transparent substrate 431 is broken. The surface of the transparent plate 432 may be subjected to processing such as anti-glare processing and fingerprint processing.

The transparency of the transparent plate 432 is not particularly limited and can be set as appropriate. However, the transparent plate 432 preferably has a degree of transparency that does not significantly adversely affect the visibility of the display system of the present embodiment. . Specifically, the transmittance of the transparent plate 432 is preferably 80% or more, and more preferably 90% or more.

The thickness of the transparent plate 432 is not particularly limited, and can be set as appropriate. The transparent plate 432 may be a so-called transparent film.

The material of the transparent plate 432 is not particularly limited, but a transparent resin is suitable. Specific examples include polyethylene terephthalate (PET).

The reflectance on the surface of the transparent plate 432 shows polarization dependence as in the case of the glass substrate, and the reflectance of P-polarized light becomes 0 at a specific incident angle (Brewster angle) as shown in FIG. .

Therefore, as shown in FIG. 23, when the protective plate 440 is disposed on the liquid crystal display device 10 without the pattern phase difference plate 20, the colored striped pattern is visually recognized in a specific observation direction.

Therefore, in order to eliminate this colored stripe pattern, in this embodiment, the pattern phase difference plate 20 is pasted on the surface of the transparent substrate 431 on the liquid crystal display device 10 side. Thereby, since the polarization state of the polarized light (display light) from the liquid crystal display device 10 can be eliminated, the generation of colored striped patterns can be suppressed as in the first embodiment.

Moreover, when a PET film was used as the transparent plate 432 and the same pattern retardation plate as that used in the system A was used as the pattern retardation plate 20, the display system according to this embodiment was actually produced. The colored stripes due to birefringence could be eliminated.

Hereinafter, modified examples in each embodiment will be described.

In each embodiment, the case where a liquid crystal display device is used as the display device has been described. However, the type of the display device according to the present invention is not particularly limited to the liquid crystal display device, and the display device includes a polarizing plate on the viewer side. Can be applied. For example, an organic EL display or an inorganic EL display may be used.

In a self-luminous display such as an organic EL display, a circularly polarizing plate may be used in order to reduce reflection generated inside the light emitting element. As the circularly polarizing plate, a laminate of a linearly polarizing plate and a λ / 4 plate is usually used, so that display light emitted from the display is linearly polarized light. Therefore, as in the case of the liquid crystal display device, the occurrence of colored striped patterns is suppressed.

In each embodiment, a transmissive liquid crystal display device has been described. However, each liquid crystal display device may include a reflective display unit that performs display by reflecting external light.

Furthermore, the display device according to the present invention may be a monochrome display device.

And embodiment mentioned above may be combined suitably in the range which does not deviate from the summary of this invention.

1, 2, 3, 4: Display system 10: Liquid crystal display device 11, 12: Substrate 13, 14: Polarizing plate 20: Pattern retardation plate 21, 22: Fine regions 30, 230, 330, 430: Touch panels 31, 231 331, 431: transparent substrate 32, 232, 235, 332, 432: transparent plate 33, 233: Y pattern electrode 34, 234: X pattern electrode 333, 334: electrode 336: insulator 437: light emitting module 438: light receiving module 440: Protection plate

Claims (14)

A display device having a polarizing plate provided on the viewer side;
A transparent plate disposed on the viewer side of the display device and having birefringence;
A display system comprising: a polarizing plate and a pattern retardation plate disposed between the transparent plate and the transparent plate. The display system according to claim 1, wherein the transparent plate includes a transparent resin. The display system according to claim 2, wherein the transparent resin has an intrinsic birefringence of 0.1 or more or -0.1 or less. The display system according to claim 2, wherein the transparent resin has a photoelastic coefficient of 30 × 10 ⁻³ cm ² / dyn or more. The display system includes a touch panel,
The display system according to any one of claims 1 to 4, wherein the transparent plate is included in the touch panel. The display system according to claim 5, wherein a type of the touch panel is a capacitance type. The display system according to claim 5, wherein a type of the touch panel is a resistive film type. The display system according to claim 1, wherein the transparent plate protects the display device. The pattern phase difference plate includes a plurality of first regions and a plurality of second regions that are alternately arranged in a plan view, and converts the light exiting the polarizing plate into two polarizations having different phases. The display system according to any one of 1 to 8. The display system according to claim 9, wherein phases of the two polarized lights are different from each other by π. The display device has a display area having a vertical length of H,
11. The display system according to claim 9, wherein a pitch between the plurality of first regions and the plurality of second regions is less than 0.0131 × H. The display system according to any one of claims 9 to 11, wherein a pitch of the plurality of first regions and the plurality of second regions is 1.3 mm or less. The display system according to claim 12, wherein a pitch of the plurality of first regions and the plurality of second regions is 0.58 mm or less. The touch panel system is a capacitive system,
The touch panel includes two layers of pattern electrodes,
The two-layer pattern electrode includes a wiring group formed like a mesh,
The display system according to any one of claims 9 to 13, wherein a pitch between the plurality of first regions and the plurality of second regions is equal to or less than a pitch of the wiring group.

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