Liquid crystal display device and virtual image display device

Abstract

A liquid crystal display device of the present disclosure includes a backlight, a lens member, a diffusion plate, and a liquid crystal panel. The backlight includes a substrate having a first surface, and a plurality of light-emitting elements disposed on the first surface. The lens member is configured so as to anisotropically diffuse light emitted from the backlight. The diffusion plate is configured to diffuse light emitted from the lens member. The liquid crystal panel is configured to receive light emitted from the diffusion plate. The distance between the lens member and the diffusion plate is set to 0 mm or more and 72 mm or less.

Description

Technical Field

[0001] The present disclosure relates to a liquid crystal display device and a virtual image display device. Background Art

[0002] Conventionally, for example, a liquid crystal display device described in Patent Document 1 is known.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2019 / 138722 Summary of the Invention

[0006] The liquid crystal display device disclosed herein comprises:

[0007] A backlight comprising: a substrate having a first surface, and a plurality of light-emitting elements arranged on the first surface;

[0008] a lens member configured to anisotropically diffuse light emitted from the backlight;

[0009] a diffuser plate configured to diffuse light emitted from the lens member; and

[0010] A liquid crystal panel configured to receive light emitted from the diffusion plate

[0011] The distance between the lens member and the diffuser plate is set to be greater than or equal to 0 mm and less than or equal to 72 mm.

[0012] The virtual image display device disclosed herein comprises:

[0013] The above-mentioned liquid crystal display device; and

[0014] The optical system is configured to allow a user to visually recognize the image light emitted from the liquid crystal display device as a virtual image. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The objects, features and advantages of the present disclosure will become more apparent from the following detailed description and accompanying drawings.

[0016] Figure 1 It is a plan view showing a liquid crystal display device according to one embodiment of the present disclosure.

[0017] Figure 2 It is along Figure 1 Sectional view taken along the cutting line II-II.

[0018] Figure 3 It is a diagram illustrating the half-value angle of light emitted from a lens member.

[0019] Figure 4This is a graph showing the relationship between the brightness of light emitted from a backlight and the driving current applied to each light-emitting element.

[0020] Figure 5 This is a diagram schematically showing a virtual image display device according to one embodiment of the present disclosure.

[0021] Figure 6A This is a photograph of a virtual image formed by the virtual image teaching device of the embodiment, taken with a camera.

[0022] Figure 6B Yes Figure 6A A graph showing the brightness distribution at line AB of the captured image.

[0023] Figure 7 This is a diagram showing the directional characteristics of the light source used in the brightness uniformity and brightness simulation.

[0024] Figure 8 It is a diagram showing the arrangement of light sources and illuminated surfaces in a simulation of luminance uniformity and luminance.

[0025] Figure 9 It is a cross-sectional view showing a liquid crystal display device according to another embodiment of the present disclosure.

[0026] Figure 10 It schematically indicates that Figure 9 Diagram of a virtual image display device of a liquid crystal display device.

[0027] Figure 11 Yes Figure 10 FIG. 1 is a diagram showing an example of a virtual image visually recognized by a user of a virtual image display device. DETAILED DESCRIPTION

[0028] In the past, various virtual image display devices have been proposed that allow a user to visually recognize image light emitted from a display device as a virtual image. In the case where the display device is a liquid crystal display device including a backlight and a liquid crystal panel, by performing local dimming control on the backlight, the user can visually recognize a virtual image with improved contrast. However, in the case where the light source of the backlight is a highly directional light source such as a light emitting diode element, the brightness uniformity of the light emitted from the backlight is reduced, and as a result, the local dimming control sometimes becomes ineffective. Patent document 1 discloses a liquid crystal display device that uses a light guide that makes the brightness of light emitted from multiple point light sources uniform, thereby suppressing the reduction in the brightness uniformity of the light emitted from the backlight.

[0029] Conventional liquid crystal display devices have room for improvement in terms of increasing the brightness of light emitted from a backlight and improving the brightness uniformity of the light emitted from the backlight.

[0030] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the figures used in the following description are schematic diagrams. The dimensional ratios in the drawings may not necessarily be consistent with the actual dimensional ratios. In this specification, in some of the drawings, for convenience, an orthogonal coordinate system xyz is defined, with the positive direction of the z-axis being the top, and terms such as upper surface or lower surface are used. The x-axis direction, the y-axis direction, and the z-axis direction are referred to as the first direction, the second direction, and the third direction, respectively. The first direction is also referred to as the horizontal direction, and the second direction is also referred to as the vertical direction.

[0031] Figure 1 is a plan view showing a liquid crystal display device according to one embodiment of the present disclosure, Figure 2 Therefore Figure 1 The sectional view taken along the cutting line II-II, Figure 3 is a diagram illustrating the half-value angle of light emitted from a lens component, Figure 4 This is a graph showing the relationship between the brightness of light emitted from a backlight and the driving current applied to each light-emitting element. Figure 5 This is a diagram schematically showing a virtual image display device according to one embodiment of the present disclosure. Figure 6A This is a photograph of a virtual image formed by the virtual image teaching device of the embodiment, taken with a camera. Figure 6B Yes Figure 6A The brightness distribution diagram at line AB of the photograph is shown in the figure. Figure 7 : is a diagram showing the directional characteristics of the light source used in the brightness uniformity and brightness simulation. Figure 8 : is a diagram showing the arrangement of the light source and the illuminated surface in the simulation of brightness uniformity and brightness. Figure 1 In the top view of FIG, optical components such as the liquid crystal panel, the diffuser plate, the lens component, and the backlight are omitted.

[0032] like Figure 1 、 Figure 2 As shown, a liquid crystal display device 1 according to one embodiment of the present disclosure includes a backlight 2 , a lens member 7 , a diffusion plate 8 , and a liquid crystal panel 9 .

[0033] The backlight 2 includes a substrate 3 and a plurality of light emitting elements 4. The substrate 3 can be made of, for example, glass, ceramic, resin, metal, or semiconductor material. The substrate 3 has a first surface 3a on which the plurality of light emitting elements 4 are arranged. The first surface 3a can be perpendicular to the third direction. Figure 1 As shown, a plurality of light emitting elements 4 are arranged in a matrix at a predetermined pitch P. Although not shown, electrode pads connected to the light emitting elements 4 and wiring conductors for driving the light emitting elements 4 are provided on the first surface 3 a .

[0034] When substrate 3 is made of a metal material or a semiconductor material, a plurality of light-emitting elements 4 can be arranged on first surface 3a via an insulating layer (not shown). The insulating layer can be made of, for example, an inorganic insulating material such as SiO2 (silicon oxide) or Si3N4 (silicon nitride), or an organic insulating material such as acrylic resin or polycarbonate resin.

[0035] The light-emitting element 4 may be, for example, a self-luminous element such as a light-emitting diode (LED), an organic light-emitting diode (OLED), or a semiconductor laser (LD). In the following description, the light-emitting element 4 is an LED. The light-emitting element 4 may be a mini-LED or a micro-LED. The light-emitting element 4 may be composed of a white LED that emits white light. Alternatively, each light-emitting element 4 may include a red LED that emits red light, a green LED that emits green light, and a blue LED that emits blue light.

[0036] like Figure 2 As shown, the backlight 2 may include an optical component 5 for focusing light emitted from a plurality of light-emitting elements 4. The optical component 5 is located above the first surface 3a, and the distance between the optical component 5 and the substrate 3 may be, for example, about 1 to 10 mm, or about 5 mm. The optical component 5 may be composed of a microlens array having a plurality of microlenses arranged in a two-dimensional manner. Each microlens may be, for example, a biconvex lens, a plano-convex lens, a convex meniscus lens, or the like. The optical component 5 may also be composed of a combination of cylindrical lenses. The thickness of the optical component 5 may be about 0.1 to 3 mm, or about 1 mm. In addition, the optical component 5 may be a brightness enhancement film, or the BEF series of prism films manufactured by Sumitomo 3M Co., Ltd. may be used. A prism sheet is an optical component that focuses light by utilizing the double reflection of light passing through the film and the refractive index of light. The prism sheet may also be arranged in a stacked configuration. In the case of a stacked configuration, the prisms may also be arranged so that the ridges are orthogonal.

[0037] like Figure 1 、 Figure 2 As shown, the backlight 2 may include a reflector 6 located on the first surface 3a of the substrate 3. Figure 1As shown, the reflector 6 has a lattice pattern, with one light-emitting element 4 located in each area partitioned by the reflector 6. The upper end 6a of the reflector 6, which is furthest from the first surface 3a in the third direction (z-axis direction), can be in contact with the optical member 5. This prevents light emitted from the emitting light-emitting elements 4 from entering the areas of the liquid crystal panel corresponding to the non-emitting light-emitting elements 4 during local dimming control, thereby reducing the possibility of reduced effectiveness of local dimming control. The side surfaces 6b of the reflector 6 facing the light-emitting elements 4 can be light-reflective. The side surfaces 6b of the reflector 6 can be made of a metal material such as aluminum (Al) or silver (Ag). Local dimming control divides the backlight 2 into multiple blocks and independently controls the brightness of each block based on the image displayed by the liquid crystal panel 9. For example, if a certain area of ​​the liquid crystal panel 9 displays a dark image, the brightness of the block corresponding to that area can be reduced, allowing the darker image to be displayed. In this way, local dimming control can improve the display performance and contrast of the liquid crystal display device 1. Furthermore, by allowing high-brightness light with improved brightness uniformity to enter the liquid crystal panel 9 , the effectiveness of local dimming control can be enhanced, allowing the user to visually recognize a clear image (virtual image).

[0038] The lens member 7 anisotropically diffuses the light emitted from the backlight 2. The diffusion capability of the lens member 7 in the first direction (x-axis direction) is different from the diffusion capability in the second direction (y-axis direction), so that the incident light is anisotropically diffused and emitted. In the case where the backlight 2 includes the optical member 5, the light focused by the optical member 5 is incident on the lens member 7, so the lens member 7 can diffuse the incident light at a designed diffusion angle (also called a light distribution angle). The diffusion capability of the lens member 7 in the first direction and the diffusion capability of the lens member 7 in the second direction can be combined with the virtual image display device 10 (see Figure 5 ) is determined accordingly. For example, when displaying virtual image 10Q in a horizontally long orientation, the diffusivity in the first direction can be increased, while the diffusivity in the second direction can be lower than that in the first direction. In particular, in virtual image display devices used in head-up displays, the brightness uniformity in the first direction can be higher than that in the second direction. Therefore, the diffusivity in the first direction is set within a specific range.

[0039] The lens component 7 can be a component having a plurality of microlenses regularly arranged on the light incident surface of a plate-shaped or sheet-shaped component made of transparent resin. The lens component 7 can also be a microlens array having a plurality of microlenses arranged two-dimensionally. The microlenses only need to be configured to have a diffusion peak in a specific direction, such as the first direction. In other words, the shape of the microlenses only needs to be configured to have a strong diffusion ability in the x-axis direction and a smaller diffusion ability in the y-axis direction than in the x-axis direction. Each microlens can be composed of, for example, a biconcave lens, a plano-concave lens, a concave meniscus lens, etc. The lens component 7 can be in contact with the optical component 5 in the third direction or can be separated from the optical component 5. The thickness of the lens component 7 can be approximately 0.5 to 2 mm, or can be approximately 1 mm. The diffusivity and anisotropy of the lens component 7 are controlled by the microstructure of the microlenses. In other words, the desired anisotropic diffusion ability can be obtained by adjusting the pitch between the concave and convex parts of the microlenses and the height of the concave and convex parts. For example, when the anisotropic diffusion capacity is represented by a numerical value such as H20 V13, the diffusion capacity in the horizontal direction (in the case of this embodiment, the x-axis direction) is 20, and the diffusion capacity in the vertical direction (in the case of this embodiment, the y-axis direction) is 13. The diffusion capacity in the x-axis direction and the y-axis direction are different, and diffusion is easier in the x-axis direction.

[0040] The lens member 7 is configured so that the light emitted from the lens member 7 in a direction with high diffusion power has a predetermined half-value angle θ. Figure 3 As shown, the half-value angle θ refers to the width of the polar angle θ at which the normalized luminance NL of the light emitted from the lens component 7 becomes greater than or equal to 0.5 when only one light-emitting element 4 is set to the emitting state and the normalized luminance NL is expressed as a function of the polar angle θ. The polar angle θ can be the angle between the propagation direction of each portion of light emitted from the lens component 7 and the z-axis. The smaller the half-value angle θ, the narrower the directivity of the lens component 7. The larger the half-value angle θ, the wider the directivity of the lens component 7.

[0041] The diffuser plate 8 diffuses light emitted from the lens member 7. The diffuser plate 8 can be composed of, for example, a base composed of a transparent resin, glass, or the like, and light-diffusing particles composed of, for example, silicone resin, polystyrene resin, silicon dioxide, or calcium carbonate dispersed within the base. The thickness of the diffuser plate 8 can be approximately 0.05 to 0.3 mm, or even approximately 0.1 mm.

[0042] The diffuser plate 8 is configured to have a predetermined haze value H (%). The haze value H is obtained by multiplying the value Td / Tt obtained by dividing the diffuse transmittance Td by the total transmittance Tt by 100. The diffuse transmittance Td and the total transmittance Tt are measured using a known measurement method.

[0043] The liquid crystal panel 9 is positioned above the diffuser plate 8. The liquid crystal panel 9 has a display surface 9a. The display surface 9a is the surface of the liquid crystal panel 9 opposite the surface facing the backlight 2. The liquid crystal panel 9 uses light emitted from the diffuser plate 8 to display an image based on an externally input image signal on the display surface 9a. In other words, the liquid crystal panel 9 emits image light from the display surface 9a based on the externally input image signal. The display surface 9a of the liquid crystal panel 9 also serves as the display surface 9a of the liquid crystal display device 1.

[0044] The liquid crystal panel 9 may be a known liquid crystal panel, such as IPS (In-Plane Switching), FFS (Fringe Field Switching), VA (Vertical Alignment), and ECB (Electrically Controlled Birefringence) liquid crystal panels.

[0045] The liquid crystal display device 1 includes a controller (not shown). The controller controls the backlight 2 and the liquid crystal panel 9. Based on the image displayed on the liquid crystal panel 9, the controller can switch each of the plurality of light-emitting elements 4 between an emitting state and a non-emitting state. If the liquid crystal display device 1 is included in a virtual image display device, the controller can control the brightness of the light-emitting elements 4 switched to the emitting state based on the background brightness in the user's field of view. In this case, the brightness and contrast of the virtual image perceived by the user can be improved.

[0046] The controller may be configured as a processor, for example. The controller may include one or more processors. Processors may include general-purpose processors that read specific programs and execute specific functions, as well as dedicated processors dedicated to specific processing. Dedicated processors may include ICs (Application Specific Integrated Circuit: ASICs) for specific purposes. Processors may include programmable logic devices (PLDs). PLDs may include FPGAs (Field-Programmable Gate Arrays). The controller may be either an SoC (System-on-a-Chip) or a SiP (System in a Package) in which one or more processors work together. The controller may include a storage unit that stores various information or programs for operating the various components of the liquid crystal display device 1. The storage unit may be configured, for example, from a semiconductor memory. The storage unit may function as a temporary storage area used during data processing by the controller.

[0047] In the liquid crystal display device 1, the distance L between the lens member 7 and the diffuser plate 8 is set to be between 0 mm and 72 mm based on the half-value angle θ of the light emitted from the lens member 7, the haze value H of the diffuser plate 8, and the pitch P. This allows the liquid crystal display device 1 to improve the luminance uniformity of the light incident on the liquid crystal panel 9, thereby enhancing the effectiveness of local dimming control. Furthermore, in the liquid crystal display device 1, by setting the distance L based on the half-value angle θ, the haze value H, and the pitch P, the brightness of the light incident on the liquid crystal panel 9 can be increased, and the luminance uniformity of the light incident on the liquid crystal panel 9 can be improved, thereby further enhancing the effectiveness of local dimming control.

[0048] In this specification, brightness uniformity (%) is defined as follows: In the brightness distribution of light emitted from the diffuser 8 (i.e., light incident on the liquid crystal panel 9), the maximum brightness at a position directly above the light-emitting element 4 is defined as Ia, the maximum brightness at a position other than directly above the light-emitting element 4 is defined as Ib, and the minimum brightness at a position other than directly above the light-emitting element 4 is defined as Ic. The value obtained by multiplying the value (Ib / Ia) obtained by dividing Ib by Ia and the value (Ic / Ia) obtained by dividing Ic by Ia, whichever deviates more from 1, by 100. Therefore, brightness uniformity can be less than 100% or greater. It can be said that the closer the brightness uniformity (%) is to 100%, the more uniform the brightness of the light incident on the liquid crystal panel 9 is.

[0049] The distance L between the lens member 7 and the diffuser plate 8 is set within a range of 0 to 72 mm. However, when distance L is set to a relatively small value (e.g., approximately 0 to 36 mm), light emitted from the emitting light-emitting elements 4 during local dimming control is less likely to enter the areas of the liquid crystal panel 9 corresponding to the non-emitting light-emitting elements 4, thereby improving contrast. Furthermore, when distance L is set to a relatively small value, the liquid crystal display device 1 can be miniaturized. Furthermore, when distance L is set to a relatively large value (e.g., approximately 36 to 72 mm), the distance between the backlight 2 and the liquid crystal panel 9 increases, thereby reducing the possibility that heat generated by the backlight 2 will affect the alignment of the liquid crystal molecules contained in the liquid crystal panel 9. As a result, the reliability of the liquid crystal display device 1 can be improved.

[0050] By increasing the half-value angle θ of the lens component 7, the brightness uniformity of the light incident on the liquid crystal panel 9 can be improved, but there is a tendency for the brightness of the light incident on the liquid crystal panel 9 to decrease. The half-value angle θ can be greater than 20° and less than 39°. In this case, the light incident on the liquid crystal panel 9 can be made brighter and the brightness uniformity of the light incident on the liquid crystal panel 9 can be further improved. As a result, the effectiveness of the local dimming control can be further improved. For the brightness uniformity of the light incident on the liquid crystal panel 9 and the dependence of the brightness on the half-value angle θ, please refer to the embodiments described below.

[0051] By increasing the haze value H of the diffuser 8, the brightness uniformity of the light incident on the liquid crystal panel 9 can be improved, but there is a tendency for the brightness of the light incident on the liquid crystal panel 9 to decrease. The haze value H can be greater than 35% and less than 76%. In this case, the light incident on the liquid crystal panel 9 can be made brighter and the brightness uniformity of the light incident on the liquid crystal panel 9 can be further improved. As a result, the effectiveness of the local dimming control can be further improved. For the brightness uniformity of the light incident on the liquid crystal panel 9 and the dependence of the brightness on the haze value H, please refer to the embodiments described below.

[0052] The pitch P between the plurality of light-emitting elements 4 can be greater than or equal to 4 mm and less than or equal to 6 mm. In this case, the number of light-emitting elements 4, or in other words, the number of regions where the light emitted by the backlight 2 can be independently controlled, can be increased to a level sufficient to achieve the effects of local dimming control. As a result, the effectiveness of local dimming control can be further enhanced.

[0053] Next, a virtual image display device according to one embodiment of the present disclosure will be described. The virtual image display device 10 of this embodiment is also referred to as a head-up display (HUD). The virtual image display device 10 can be mounted on a mobile object 13. Mobile objects 13 include vehicles, ships, and aircraft. Vehicles include, but are not limited to, automobiles and industrial vehicles. They may also include rail vehicles, consumer vehicles, and fixed-wing aircraft traveling on runways. Automobiles include, but are not limited to, passenger cars, trucks, buses, two-wheeled vehicles, and trolleybuses. They may also include other vehicles traveling on roads. Industrial vehicles include, but are not limited to, those used in agriculture and construction. Industrial vehicles include, but are not limited to, forklifts and golf carts. Agricultural industrial vehicles include, but are not limited to, tractors, tillers, transplanters, reaper-balers, combine harvesters, and mowers. Construction industrial vehicles include, but are not limited to, bulldozers, shovels, forklifts, cranes, dump trucks, and load rollers. Vehicles include human-powered vehicles. The classification of vehicles is not limited to the above. For example, a car may include an industrial vehicle that can travel on a road, and the same vehicle may be included in multiple categories. A ship in the present disclosure includes a ship nozzle, a ship, and a tanker. An aircraft in the present disclosure includes a fixed-wing aircraft and a rotary vane aircraft.

[0054] like Figure 5 As shown, the virtual image display device 10 includes a liquid crystal display device 1 and an optical system 11. The optical system 11 allows the user 12 to visually recognize the image light emitted from the display surface 9a of the liquid crystal display device 1 as a virtual image 10Q. The optical system 11 is located in the optical path of the image light emitted from the liquid crystal display device 1 and reaching the eyes of the user 12. The optical system 11 can enlarge or reduce the image displayed on the display surface 9a of the liquid crystal display device 1 so that it is formed in the eyes of the user 12. Figure 5 As shown, the optical system 11 includes a first optical component 11a and a second optical component 11b. The number of optical components constituting the optical system 11 is not limited to two, and may be one, or may be three or more. In the case where the virtual image display device 10 is mounted on a moving body 13, the windshield of the moving body 13 may also serve as the second optical component 11b. The optical components constituting the optical system 11 may include a reflective component having a convex mirror or a concave mirror, and may also include a refractive component having a convex lens or a concave lens. The convex lens includes a biconvex lens, a plano-convex lens, and a convex meniscus lens. The concave lens includes a biconcave lens, a plano-concave lens, and a concave meniscus lens. The optical components constituting the optical system 11 are not limited to reflective components or refractive components, and may also include various other optical components.

[0055] Because the virtual image display device 10 includes the liquid crystal display device 1, it enables the user 12 to visually recognize a high-contrast, high-brightness virtual image 10Q. Therefore, the virtual image display device 10 enables the user 12 to visually recognize the virtual image 10Q regardless of the time of day (daytime, nighttime, etc.) or the surrounding weather (sunny, cloudy, rainy, snowy, etc.).

[0056] The virtual image display device 10 can be configured to allow the user 12 to visually perceive a stereoscopic image. The liquid crystal display device 1 can be configured to display a mixed image including a left-eye image and a right-eye image having parallax with respect to the left-eye image on the display surface 9a of the liquid crystal panel 9. The virtual image display device 10 can be configured to include an optical element that separates image light emitted from the display surface 9a of the liquid crystal panel 9 into left-eye image light representing the left-eye image and right-eye image light representing the right-eye image. The optical element can be configured as a parallax barrier (parallax barrier) or a lenticular lens. The parallax barrier can be configured to include a liquid crystal panel.

[0057] Example

[0058] In order to confirm the effectiveness of the liquid crystal display device 1, the brightness uniformity and brightness of the light incident on the liquid crystal panel 9 were calculated by simulation. The backlight 2 is constructed so that 220 light-emitting elements 4 are arranged in a matrix of 10 rows and 22 columns in an area where the diagonal length of the first surface 3a is 4.1 inches. The reflector 6 is configured so that the upper end 6a is 5 mm high from the first surface 3a. The optical component 5 is a microlens array with a thickness of 1 mm, and is configured so that the distance from the substrate 3 is 5 mm. The lens component 7 is a microlens array with a thickness of 1 mm, and is configured so that the distance from the optical component 5 is 0 mm, that is, the lens component 7 is in contact with the optical component 5. The diffuser 8 is configured so that the thickness of the diffuser 8 is 0.1 mm and the distance from the lens component 7 is L.

[0059] The inventor calculated the brightness uniformity and brightness through self-made simulation software. Figure 7 as well as Figure 8 Create simulation software. Figure 7 The light emission angle characteristics of NSPWR70CSS-K1 (hereinafter referred to as light source 14) manufactured by Nichia Corporation are shown, and it is possible to calculate at what angle and at what rate energy is emitted from the light source 14. Figure 8 : is a diagram showing the arrangement of the light source 14 and the illuminated surface 15 in the simulation. Figure 8 The arrangement shown can be calculated based on the emission angle characteristic C of the light source 14 and the distance L between the light source surface 14a of the light source 14 and the illuminated surface 15 to determine the spacing d at which adjacent light sources 14 are arranged. Figure 8In FIG. 1 , Q0 represents a position where the illuminance distribution has a peak in the illuminated surface 15 , and Q represents a position where the illuminance distributions of adjacent light sources 14 overlap.

[0060] Will Figure 8 The light source 14 shown is assumed to be a completely diffuse surface light source. The brightness of the light source 14 is set to B. When irradiating the illuminated surface 15 parallel to the light source surface 14 a of the light source 14 , the illuminance E0 in the area dQ within the illuminated surface 15 satisfies the formula (1).

[0061] E0=B(dQ / L 2 )・ds・(1 / dQ)=B・(ds / L 2 )…(1)

[0062] In equation (1), d represents the spacing between adjacent light sources 14, and ds represents the area within light source surface 14a. The illuminance E of illuminated surface 15, which forms an angle Φ with light source surface 14a of light source 14, is compressed by an amount (cosΦ) in the Φ direction, thus satisfying the relationship in equation (2).

[0063] E=B・{dQcosΦ / (L / cosΦ) 2}・ds・cosΦ・(1 / dQ)

[0064] =B・(ds / L 2 )・cos 4 Φ… (2)

[0065] Therefore, the relationship becomes formula (3).

[0066] E=E0cos 4 Φ… (3)

[0067] In addition, the light source 14 is not a completely diffuse surface light source, but the luminous intensity I is directed in the direction of the angle Φ relative to the normal line of the light source surface 14a. Φ In the case of a light source such as the one in which the ratio of the luminosity I0 toward the center is expressed by equation (4), the relational expression of equation (5) can be derived.

[0068] I(Φ)=I Φ / I0…(4)

[0069] E0=kI0・(dQ / L 2 )ds・(1 / dQ)=kI0・(ds / L 2 )…(5)

[0070] In equation (5), k is a proportionality constant. The illuminance E of the illuminated surface 15 in the direction forming an angle Φ with the light source surface 14 a satisfies equation (6).

[0071] E=kI Φ・{dQcosΦ / (L / cosΦ) 2}・ds・(1 / dQ)

[0072] =kI Φ ・(ds / L 2 )・cos 3 Φ… (6)

[0073] Formula (7) is derived based on formula (5) and formula (6).

[0074] E=E0・I(Φ)・cos 3 Φ… (7)

[0075] To be Figure 7 The distribution exemplified in FIG is applied to I(Φ) in equation (7) to create simulation data.

[0076] [Table 1]

[0077]

[0078] [Table 2]

[0079]

[0080] [Table 3]

[0081]

[0082] [Table 4]

[0083]

[0084] [Table 5]

[0085]

[0086] [Table 6]

[0087]

[0088] Tables 1 to 6 show the luminance uniformity (%) of the light incident on the liquid crystal panel 9 and the luminance (cd / m²) of the light incident on the liquid crystal panel 9 when the distance L between the lens member 7 and the diffuser plate 8 is changed. 2 ). Tables 1 and 2 show the results when the spacing P is set to 4.2 mm, Tables 3 and 4 show the results when the spacing P is set to 5.0 mm, and Tables 5 and 6 show the results when the spacing P is set to 6.0 mm. Figure 4As shown, the brightness of the light emitted from the backlight 2 increases approximately in proportion to the drive current applied to each light-emitting element 4. Tables 1 and 2 show the results when the drive current applied to each light-emitting element 4 is set to 65 mA, Tables 3 and 4 show the results when the drive current applied to each light-emitting element 4 is set to 65 mA, and Tables 5 and 6 show the results when the drive current applied to each light-emitting element 4 is set to 65 mA.

[0089] In the "Simulation Number" of Tables 1 to 6, "1" represents the result when the half-value angle θ was set to 20° and the haze value H was set to 35%, "2" represents the result when the half-value angle θ was set to 30° and the haze value H was set to 35%, and "3" represents the result when the half-value angle θ was set to 39° and the haze value H was set to 35%. In addition, "4" represents the result when the half-value angle θ was set to 20° and the haze value H was set to 52%, "5" represents the result when the half-value angle θ was set to 30° and the haze value H was set to 52%, and "6" represents the result when the half-value angle θ was set to 39° and the haze value H was set to 52%. In addition, "7" represents the result when the half-value angle Θ is set to 20° and the haze value H is set to 76%, "8" represents the result when the half-value angle Θ is set to 30° and the haze value H is set to 76%, and "9" represents the result when the half-value angle Θ is set to 39° and the haze value H is set to 76%.

[0090] As shown in Tables 1 to 6, according to the liquid crystal display device 1, by setting the distance L to a predetermined value, i.e., 0 mm or greater and 72 mm or less, based on the half-value angle θ, the haze value H, and the pitch P, the brightness of the light incident on the liquid crystal panel 9 can be increased, and the brightness uniformity of the light incident on the liquid crystal panel 9 can be improved. Furthermore, as shown in Tables 1 to 6, increasing the distance L can improve the brightness uniformity of the light incident on the liquid crystal panel 9, but there is a tendency for the brightness of the light incident on the liquid crystal panel 9 to decrease. Furthermore, by setting the upper limit of the distance L to 57 mm or less, the brightness can be further increased.

[0091] Next, an example of a design method for a liquid crystal display device 1 is described with reference to Tables 1 and 2. For example, in a liquid crystal display device with a design pitch P of 4.2 mm, the brightness uniformity of light incident on the liquid crystal panel 9 is 95% or higher, and the brightness is 13,000 cd / m 2 In the case of the above-described liquid crystal display device 1, multiple combinations of distance L, half-value angle θ, and haze value H that satisfy these conditions can be found as shown by the bold lines. By selecting one of the multiple combinations and setting the distance L, half-value angle θ, and haze value H based on the selected combination, it is possible to design a device in which the brightness uniformity of light incident on the liquid crystal panel 9 is 95% or higher and the brightness is 13,000 cd / m 2The above liquid crystal display device 1. If a combination with a relatively small distance L is selected from the plurality of combinations, the contrast of the liquid crystal display device can be improved, and the liquid crystal display device 1 can be miniaturized. If a combination with a relatively large distance L is selected from the plurality of combinations, the possibility of the orientation of the liquid crystal molecules contained in the liquid crystal panel 9 being uncontrolled due to the heat generated by the backlight 2 can be reduced, thereby improving the reliability of the liquid crystal display device 1.

[0092] In practice, the evaluation results for a 4.1-inch FFS-type TFT (Thin Film Transistor) liquid crystal panel using a transverse electric field method are shown as liquid crystal panel 9. A liquid crystal display device was prepared in which LED elements were used as the light source for the backlight 2, and the pitch P between the LED elements was 4.2 mm. This liquid crystal display device was configured such that a lens member 7 with a half-value angle θ of 20° and a diffuser plate 8 with a haze value H of 35% were arranged above the backlight 2, with a distance L between the lens member 7 and the diffuser plate 8 being 45 mm.

[0093] Figure 6A 、 6B A diagram illustrating a virtual image formed by a virtual image display device using the manufactured liquid crystal display device. Figure 6A This is a photo of a virtual image formed by a virtual image display device using a manufactured liquid crystal display device, taken with a CCD camera. Figure 6B : is a graph showing the brightness distribution of line AB in the obtained captured image.

[0094] Figure 6A The captured image is a virtual image captured when the entire display area of ​​the liquid crystal display device is set to ON display and all the LED elements serving as the light source of the backlight 2 are lit. Figure 6B , it can be seen that local peaks and valleys are generated, and these peaks and valleys are simply numbered. Brightness uniformity shows that the brightness difference between peak and valley areas is small. Brightness uniformity U can be expressed as Equation (8) using the brightness V1 of a specific valley area 1, the brightness V2 of valley area 2 adjacent to valley area 1, and the brightness Peak of the peak area between valley areas 1 and 2.

[0095] U={(V1+V2) / 2} / Peak…(8)

[0096] [Table 7]

[0097]

[0098] Table 7 shows Figure 6BThe brightness uniformity and virtual image brightness of the virtual image at the position shown are substantially the same as the simulation results shown in Tables 1 and 2. Based on Tables 1 to 6, the distance L, half-value angle θ, and haze value H can be easily combined.

[0099] The structures disclosed herein are not limited to the embodiments described above and are capable of various modifications and variations. For example, the functions of various components can be rearranged to ensure logical consistency, and multiple components can be combined or separated. For example, the backlight 2 can be configured to include only the lens component 7 or to include only the lens component 7 and the diffuser 8.

[0100] In Tables 1 to 6, decreasing the haze value H of the diffuser plate 8 increases the brightness of the light incident on the liquid crystal panel 9, while increasing the haze value H tends to improve the brightness uniformity of the light incident on the liquid crystal panel 9. Furthermore, increasing the half-value angle θ tends to improve brightness uniformity.

[0101] Next, a liquid crystal display device according to another embodiment of the present disclosure will be described. Figure 9 is a cross-sectional view showing a liquid crystal display device according to another embodiment of the present disclosure, Figure 10 It schematically indicates that Figure 9 a diagram of a liquid crystal display device and a virtual image display device, Figure 11 Yes Figure 10 FIG. 1 is a diagram showing an example of a virtual image visually recognized by a user of a virtual image display device. Figure 9 The cross-sectional view shown is Figure 2 Hereinafter, the same reference numerals are given to the same structures as those in the above-mentioned embodiment, and detailed description thereof will be omitted.

[0102] The liquid crystal display device 1A of this embodiment includes a backlight 2, a lens member 7, a diffusion plate 8, and a liquid crystal panel 9. Figure 9 As shown, the liquid crystal display device 1A has a structure in which the display surface 9a of the liquid crystal panel 9 is tilted relative to the first surface 3a of the substrate 3 of the backlight 2. The tilt angle α of the display surface 9a relative to the first surface 3a can be, for example, about 10° to 45°. The tilt angle α is the angle between the normal line of the display surface 9a and the normal line of the first surface 3a. According to the virtual image display device 10 (see FIG. 1 ) having the liquid crystal display device 1A, Figure 10 ),like Figure 11 As shown, the user 12 can visually recognize the virtual image 10Q having a sense of depth. Figure 9 The display surface 9a of the liquid crystal panel 9 is shown as being tilted relative to the first surface 3a of the substrate 3 of the backlight 2, but the present invention is not limited thereto. For example, the display surface 9a of the liquid crystal panel 9 may have a curved portion.

[0103] The liquid crystal display device 1A includes multiple regions 16. Each of the multiple regions 16 includes a portion of a backlight 2 including at least two light-emitting elements 4, a portion of a lens member 7 through which light emitted from the portion of the backlight 2 passes, a portion of a diffuser plate 8, and a portion of a liquid crystal panel 9. The distance L between the portion of the lens member 7 and the portion of the diffuser plate 8 in each of the multiple regions 16 varies. The distance L can be a distance perpendicular to the first surface 3a of the substrate 3. The distance L can be the shortest distance between the portion of the lens member 7 and the portion of the diffuser plate 8, the longest distance between the portion of the lens member 7 and the portion of the diffuser plate 8, or the average of the shortest and longest distances.

[0104] The plurality of regions 16 may be arranged in a horizontal direction (with Figure 9 、 Figure 10 The vertical direction of the plurality of regions 16 ( Figure 9 、 Figure 10 The positions in the up and down directions (in the image) can be different from each other. Figure 9 The liquid crystal display device 1A is shown as having three regions 161 , 162 , and 163 , but the present invention is not limited thereto. The liquid crystal display device 1A may have two regions 16 or four or more regions 16 .

[0105] The pitch P between the at least two light-emitting elements 4 in each region 16, the half-value angle θ of the light emitted from a portion of the lens member 7, and the haze value H of a portion of the diffuser plate 8 can be determined based on the distance L between a portion of the lens member 7 and a portion of the diffuser plate 8. In this case, the brightness uniformity of each region 16 can be improved, and the effectiveness of the local dimming control can be improved. In addition, the liquid crystal display device 1A can be configured to set the drive current supplied to the multiple light-emitting elements 4 for each region 16. The drive current supplied to the multiple light-emitting elements 4 set for each region 16 can be determined based on, for example, the distance L between a portion of the lens member 7 and a portion of the diffuser plate 8. In this case, the brightness of the light emitted from the multiple regions 16 can be made uniform or substantially uniform, resulting in further improvement in the effectiveness of the local dimming control.

[0106] Next, the design and driving of the liquid crystal display device 1A will be described. Figure 9 As shown, the liquid crystal display device 1A includes three regions 161, 162, and 163. Hereinafter, the region 161, the region 162, and the region 163 are also referred to as the first region, the second region, and the third region, respectively.

[0107] Table 8 shows an example of the design and driving of the liquid crystal display device 1A. In Table 8, "Region" represents each region 161, 162, and 163 of the liquid crystal display device 1A. "L" represents the distance (mm) between a portion of the lens component 7 and a portion of the diffuser plate 8 in each region 161, 162, and 163. "Brightness Uniformity" represents the brightness uniformity (%) described using equation (8). "Brightness" represents the brightness of light emitted from each region 161, 162, and 163 (cd / mm2). "P" represents the spacing (mm) between the configurations of at least two light-emitting elements 4 in each region 161, 162, and 163. "Θ" represents the half-value angle (°) of light emitted from a portion of the lens component 7 in each region 16a, 16b, and 16c. "H" represents the haze value (%) of a portion of the diffuser plate 8 in each region 161, 162, and 163. "Driving current" indicates the driving current value (mA) applied to the light emitting element 4 in each region 161, 162, and 163. The same applies to Tables 9 to 11. The "brightness uniformity" and "brightness" in Table 8 are as shown in Tables 1 to 6. Figure 4 As shown, the brightness of light emitted from each region 161 , 162 , and 163 increases substantially in proportion to the driving current of the light emitting element 4 applied to each region 161 , 162 , and 163 .

[0108] [Table 8]

[0109]

[0110] The LCD device 1A shown in Table 8 is designed such that the half-value angles θ differ between the first region 161, the second region 162, and the third region 163, and the haze values ​​H differ between the first region 162, the second region 162, and the third region 163. As shown in Table 8, the LCD device 1A can improve luminance uniformity in each region 161, 162, and 163 by appropriately determining the pitch P, half-value angle θ, and haze value H in each region 161, 162, and 163 based on the distance L between a portion of the lens member 7 and a portion of the diffuser plate 8, even when the LCD panel 9 is tilted relative to the backlight 2. Consequently, the effectiveness of local dimming control can be enhanced.

[0111] [Table 9]

[0112]

[0113] Table 9 shows the drive currents supplied to the plurality of light-emitting elements 4 for each of the regions 161, 162, and 163 in the liquid crystal display device 1A shown in Table 8. As shown in Table 9, by reducing the drive current supplied to the light-emitting elements 4 included in the first region 161 and the light-emitting elements 4 included in the second region 162 compared to the drive current supplied to the light-emitting elements 4 included in the third region 163, it is possible to maintain brightness uniformity across the first, second, and third regions 161, 162, and 163, and to make the brightness of the first and second regions 161, 162, and third region 163 equal or substantially equal. As a result, the effectiveness of local dimming control can be further enhanced.

[0114] Table 9 shows an example of reducing the luminance of first region 161 and second region 162 so that the luminance of first region 161 and second region 162 is equal to or substantially equal to the luminance of third region 163, but the present invention is not limited thereto. Alternatively, the luminance of second region 162 and third region 163 may be increased so that the luminance of second region 162 and third region 163 is equal to or substantially equal to the luminance of first region 161. Alternatively, the luminance of first region 161 may be reduced while the luminance of third region 163 is increased so that the luminance of first region 161 and third region 163 is equal to or substantially equal to the luminance of second region 162.

[0115] [Table 10]

[0116]

[0117] Table 10 shows another example of the design and driving of a liquid crystal display device 1A. The liquid crystal display device 1A shown in Table 10 has a design in which the pitch P between the first region 161 and the third region 163 and the second region 162 differs, the half-value angle θ between the first region 161, the second region 162, and the third region 163 differs, and the haze value H between the first region 162 and the second region 162 and the third region 163 differs. As shown in Table 10, the liquid crystal display device 1A improves brightness uniformity across the regions 161, 162, and 163 even when the liquid crystal panel 9 is tilted relative to the backlight 2 by appropriately determining the pitch P, half-value angle θ, and haze value H in each region 161, 162, and 163 based on the distance L between a portion of the lens member 7 and a portion of the diffuser plate 8. Consequently, the effectiveness of local dimming control can be enhanced.

[0118] [Table 11]

[0119]

[0120] Table 11 shows the drive currents supplied to the plurality of light-emitting elements 4 for each of the regions 161, 162, and 163 in the liquid crystal display device 1A of Table 10. As shown in Table 11, the drive current supplied to the light-emitting elements 4 included in the first region 161 is lowered compared to the drive current supplied to the light-emitting elements 4 included in the third region 163, while the drive current supplied to the light-emitting elements 4 included in the second region 162 is increased compared to the drive current supplied to the light-emitting elements 4 included in the third region 163. This maintains brightness uniformity across the first, second, and third regions 161, 162, and 163, and makes the brightness of the first and second regions 161, 162, and third region 163 equal or substantially equal. As a result, the effectiveness of local dimming control can be further enhanced.

[0121] Table 11 shows an example of reducing the brightness of first region 161 and increasing the brightness of second region 162, thereby making the brightness of first and second regions 161, 162, equal or substantially equal to the brightness of third region 163. However, the present invention is not limited to this example. Alternatively, the brightness of second and third regions 162, 163 may be increased, making the brightness of second and third regions 162, 163 equal or substantially equal to the brightness of first region 161. Alternatively, the brightness of first and third regions 161, 163 may be reduced, making the brightness of first and third regions 161, 163 equal or substantially equal to the brightness of second region 162.

[0122] As described above, when the liquid crystal panel 9 is tilted relative to the backlight 2, in each of the multiple areas 16, the spacing P, the half-value angle Θ and the haze value H are appropriately determined based on the distance L between a portion of the lens component 7 and a portion of the diffuser plate 8. In addition, by setting the driving current supplied to the multiple light-emitting elements 4 according to each area 16, the effectiveness of the local dimming control can be improved, and the user 12 can visually recognize a clear virtual image 10Q with a sense of depth.

[0123] According to the present disclosure, high-brightness light with improved brightness uniformity can be incident on the liquid crystal panel, thereby improving the effectiveness of local dimming control and allowing users of the virtual image display device to visually recognize clear virtual images.

[0124] In this disclosure, the x-axis, y-axis, and z-axis are provided for ease of description and can be interchanged. The structures involved in this disclosure are described using an orthogonal coordinate system consisting of the x-axis, y-axis, and z-axis. The positional relationship of the various structures involved in this disclosure is not limited to being in an orthogonal relationship.

[0125] The present disclosure can be implemented in the following embodiments (1) to (12).

[0126] (1) A liquid crystal display device comprising:

[0127] A backlight comprising: a substrate having a first surface, and a plurality of light-emitting elements arranged on the first surface;

[0128] a lens member configured to anisotropically diffuse light emitted from the backlight;

[0129] a diffuser plate configured to diffuse light emitted from the lens member; and

[0130] The liquid crystal panel is configured to receive light emitted from the diffusion plate.

[0131] The distance between the lens member and the diffuser plate is set to be greater than or equal to 0 mm and less than or equal to 72 mm.

[0132] (2) In the liquid crystal display device according to (1) above, the distance is determined based on a pitch between the plurality of light emitting elements, a half-value angle of light emitted from the lens member, and a haze value of the diffuser plate.

[0133] (3) In the liquid crystal display device according to (2) above, the half-value angle is not less than 20° and not more than 39°.

[0134] (4) The liquid crystal display device according to (2) or (3) above, wherein the haze value is 35% or more and 76% or less.

[0135] (5) In the liquid crystal display device according to any one of (2) to (4) above, the pitch is not less than 4 mm and not more than 6 mm.

[0136] (6) In the liquid crystal display device according to any one of (1) to (5) above, the backlight further includes an optical member configured to collect light emitted from the plurality of light emitting elements.

[0137] (7) In the liquid crystal display device according to any one of (1) to (6) above, the display surface of the liquid crystal panel is inclined with respect to the first surface.

[0138] (8) A liquid crystal display device according to any one of (1) to (7) above, wherein the liquid crystal display device has a plurality of regions, each of which includes: a portion of the backlight including at least two light-emitting elements, and a portion of the lens component through which light emitted from the portion of the backlight passes, a portion of the diffuser plate, and a portion of the liquid crystal panel, wherein the distances between the portion of the lens component and the portion of the diffuser plate in the plurality of regions are different from each other.

[0139] (9) In the liquid crystal display device described in (8) above, the pitch of the arrangement of the plurality of light-emitting elements, the half-value angle of light emitted from the lens member, and the haze value of the diffuser plate are determined for each of the regions based on the distance between the portion of the lens member and the portion of the diffuser plate.

[0140] (10) The liquid crystal display device according to (8) or (9) above, wherein the drive current supplied to the plurality of light emitting elements is set for each of the regions.

[0141] (11) A virtual image display device comprising: a liquid crystal display device according to any one of (1) to (10) above; and an optical system configured to allow a user to visually recognize image light emitted from the liquid crystal display device as a virtual image.

[0142] (12) The virtual image display device according to (11) above, wherein local dimming control is performed on the plurality of light emitting elements based on the display of the liquid crystal display device.

[0143] -Explanation of Symbols-

[0144] 1.1A liquid crystal display device

[0145] 2 backlight

[0146] 3 substrate

[0147] 3a Side 1

[0148] 4 Light-emitting elements

[0149] 5 Optical components

[0150] 6 Reflectors

[0151] 6a Upper

[0152] 6b Side

[0153] 7 Lens components

[0154] 8 Diffuser Plate

[0155] 9 LCD panel

[0156] 9a Display surface

[0157] 10 Virtual Image Display Device

[0158] 10Q virtual image

[0159] 11 Department of Optics

[0160] 11a First optical member

[0161] 11b Second optical member

[0162] 12 Users

[0163] 13 Moving Object

[0164] 14 Light Source

[0165] 14a Light source surface

[0166] 15 Irradiated surface

[0167] Areas 16, 161, 162, and 163.

Claims

1. A liquid crystal display device, comprising: A backlight comprising: a substrate having a first surface, and a plurality of light-emitting elements arranged on the first surface; a lens member configured to anisotropically diffuse light emitted from the backlight; a diffuser plate configured to diffuse light emitted from the lens member; as well as The liquid crystal panel is configured to receive light emitted from the diffusion plate. The distance between the lens member and the diffuser plate is set to be greater than or equal to 0 mm and less than or equal to 72 mm.

2. The liquid crystal display device according to claim 1, wherein The distance is determined based on the arrangement pitch of the plurality of light emitting elements, the half-value angle of light emitted from the lens member, and the haze value of the diffuser plate.

3. The liquid crystal display device according to claim 2, wherein The half-value angle is greater than or equal to 20° and less than or equal to 39°.

4. The liquid crystal display device according to claim 2 or 3, wherein: The haze value is 35% or more and 76% or less.

5. The liquid crystal display device according to any one of claims 2 to 4, wherein The distance is greater than or equal to 4 mm and less than or equal to 6 mm.

6. The liquid crystal display device according to any one of claims 1 to 5, wherein The backlight further includes an optical member configured to focus light emitted from the plurality of light emitting elements.

7. The liquid crystal display device according to any one of claims 1 to 6, wherein The display surface of the liquid crystal panel is inclined relative to the first surface.

8. The liquid crystal display device according to any one of claims 1 to 7, wherein The liquid crystal display device has multiple areas, and the multiple areas respectively include: a part of the backlight including at least two light-emitting elements, and a part of the lens component through which light emitted from the part of the backlight passes, a part of the diffuser plate, and a part of the liquid crystal panel. The distances between the part of the lens component and the part of the diffuser plate in the multiple areas are different from each other.

9. The liquid crystal display device according to claim 8, wherein The arrangement pitch of the plurality of light emitting elements, the half-value angle of light emitted from the lens member, and the haze value of the diffuser plate are determined for each of the regions based on the distance between the portion of the lens member and the portion of the diffuser plate.

10. The liquid crystal display device according to claim 8 or 9, wherein: The liquid crystal display device is configured to set a driving current supplied to the plurality of light emitting elements for each of the regions.

11. A virtual image display device, comprising: The liquid crystal display device according to any one of claims 1 to 10; as well as The optical system is configured to allow a user to visually recognize the image light emitted from the liquid crystal display device as a virtual image.

12. The virtual image display device according to claim 11, wherein: The virtual image display device performs local dimming control on the plurality of light emitting elements based on the display of the liquid crystal display device.

Images