Diffusion member, display device, head-up display device and vehicle

Abstract

To provide a diffusion member, a display device, a head-up display device, and a vehicle which can reduce unevenness of illuminance.SOLUTION: A diffusion member 30 includes an emission surface 30O for diffusing and transmitting light so as to emit the transmitted light to a display panel 13. The emission surface 30O includes: a first area 31a in which a haze value is set as a first haze value; and a second area 31b in which the haze value is set as a second haze value lower than the first haze value.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a diffusion member, a display device, a head-up display device, and a vehicle.

Background Art

[0002] For example, in the transmissive screen described in Patent Document 1, a light diffusion surface is provided on the second surface. For example, the light diffusion member used in the head-up display device described in Patent Document 2 diffuses and emits the light rays incident through the second lens unit toward the liquid crystal display panel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1 above, the haze value of the light diffusion surface is set to be constant. In the configuration described in Patent Document 2 above, the haze value of the diffusion member is set to be constant. For example, in a head-up display device, in order to countermeasure stray light or tilt a virtual image, a display such as a liquid crystal panel may be tilted with respect to the optical axis direction of illumination light. In this case, in a configuration with a constant haze value, unevenness occurs in the illuminance of the illumination light on the display.

[0005] The present disclosure has been made in view of the above actual situation, and an object thereof is to provide a diffusion member, a display device, a head-up display device, and a vehicle capable of reducing unevenness in illuminance.

Means for Solving the Problems

[0006] To achieve the above objective, a diffusion member according to the first aspect of this disclosure is a diffusion member having a diffusion region that diffuses and transmits light, and radiates the transmitted light to a display, wherein the diffusion region comprises a first region in which the haze value is set to a first haze value, and a second region in which the haze value is set to a second haze value lower than the first haze value.

[0007] To achieve the above objective, a display device according to a second aspect of this disclosure is a display device comprising a diffusing member, the diffusing member comprising: an illumination optical system that emits light traveling along the optical axis direction to the diffusing member; and a display panel which is a display that receives the transmitted light that has passed through the diffusing member and emits display light, wherein the diffusing member is provided in a direction that is inclined non-orthogonal to the optical axis direction such that the first region is located closer to the illumination optical system than the second region.

[0008] To achieve the above objective, a head-up display device according to a third aspect of this disclosure is a head-up display device comprising a display device, and further comprising a relay optical system that displays a virtual image by guiding the display light emitted by the display device toward a transmissive reflective member.

[0009] To achieve the above objective, the vehicle relating to the fourth aspect of this disclosure is a vehicle equipped with the head-up display device and comprising the transmissive reflective member. [Effects of the Invention]

[0010] According to this disclosure, it is possible to reduce unevenness in illumination. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a vehicle equipped with a head-up display device according to one embodiment of the present disclosure. [Figure 2] This is a schematic diagram showing the orientation of a display panel with respect to the optical axis according to one embodiment of the present disclosure. [Figure 3] This is a schematic diagram of a display device according to one embodiment of the present disclosure. [Figure 4] This is a front view of a diffusion member according to one embodiment of the present disclosure. [Figure 5] This is a front view of a diffusion member according to a modified example of the present disclosure. [Figure 6] This graph shows the haze values ​​according to the position of the diffusion member in a modified example of this disclosure. [Figure 7] This is a schematic diagram of a diffusion member and a display panel according to a modified example of the present disclosure. [Modes for carrying out the invention]

[0012] A diffusion member, a display device, a head-up display device, and a vehicle according to one embodiment of this disclosure will be described with reference to the drawings. As shown in Figure 1, the head-up display device 100 is installed, for example, in the dashboard of a vehicle 200. The head-up display device 100 emits display light L representing an image toward the windshield 201 of the vehicle 200. The display light L reflected by the windshield 201 reaches the eye box Eb. When the viewer 1 (mainly the driver) is positioned within the eye box Eb, a virtual image V corresponding to the display light L becomes visible to the viewer 1. The virtual image V is displayed on a display surface K, which is a virtual display area. The display surface K is tilted so that it becomes higher as it moves away from the viewer 1. As a result, the virtual image V is displayed so that it appears to follow the road surface from the viewer 1's perspective.

[0013] As shown in Figure 1, the head-up display device 100 comprises a display device 10, a folding mirror 31, a concave mirror 32, and a housing 33.

[0014] The housing 33 is formed in a box shape from a light-shielding resin or the like, and houses the display device 10, the folded mirror 31, and the concave mirror 32. An opening is formed in the housing 33 at a position opposite the windshield 201 (see Figure 1) in the height direction, and a window portion 33a made of a light-transmitting resin such as acrylic is fitted into this opening.

[0015] The display device 10 emits display light L. The specific configuration of the display device 10 will be described later. The folding mirror 31 reflects the display light L from the display device 10 toward the concave mirror 32. The folding mirror 31 is a plane mirror or a concave mirror. The concave mirror 32 reflects the display light L from the folding mirror 31 toward the windshield 201.

[0016] Next, the specific configuration of the display device 10 will be described. As shown in FIG. 3, the display device 10 includes a backlight unit 11, a display panel 13, and a diffusion member 30.

[0017] The backlight unit 11 is a device that illuminates the display panel 13. The backlight unit 11 includes a plurality of light sources 19, a light source substrate 16, a collimating lens 17, and a light distribution lens 20. The light source substrate 16, the collimating lens 17, and the light distribution lens 20 are arranged along the optical axis direction (the left - right direction in FIG. 3) of the light emitted by the light source 19. Hereinafter, this optical axis direction of the light is defined as the Z direction, the longitudinal direction of the light source substrate 16, the collimating lens 17, and the light distribution lens 20 is defined as the X direction, and the short - hand direction is defined as the Y direction. In this example, the X direction is along the vehicle width direction, and the Y direction is along the vehicle front - rear direction.

[0018] Each light source 19 is, for example, composed of an LED (Light Emitting Diode). The plurality of light sources 19 are mounted on the mounting surface 16a of the light source substrate 16 facing the collimating lens 17. The plurality of light sources 19 are arranged in a matrix in the X direction and the Y direction.

[0019] As shown in Figure 3, the collimating lens 17 is a collimating light-generating lens formed from a transparent optical resin or optical glass. The collimating lens 17 receives light emitted from the light source 19 and emits parallel light that is parallelized to travel in the Z direction. The collimating lens 17 comprises a plurality of convex lens portions 17a. The plurality of convex lens portions 17a are arranged in a matrix, similar to the light source 19 described above. In this example, the convex lens portions 17a and the light source 19 are arranged in a one-to-one positional relationship, facing each other in the Z direction.

[0020] The light distribution lens 20 is made of transparent optical resin or optical glass and distributes illumination light to match the display panel 13. The light distribution lens 20 has an emission surface 20t which is a toroidal surface that spreads the illumination light to match the display panel 13. The diffusion member 30 is a diffusion plate that diffuses and transmits the illumination light emitted from the light distribution lens 20. The specific configuration of the diffusion member 30 will be described later.

[0021] As shown in Figure 3, the display panel 13 receives transmitted light that has passed through the diffusion member 30 as illumination light, generates an intermediate image, and emits display light L based on this intermediate image. The display panel 13 is a TFT (Thin Film Transistor) type liquid crystal panel, and the intermediate image is generated on this liquid crystal panel. As shown in Figure 2, the display panel 13 is positioned at a non-orthogonal orientation to the optical axis Lc of the illumination light from the backlight unit 11. In this example, the upper part of the display panel 13 is tilted so that it is closer to the reflective surface of the folded mirror 31 than the lower part of the display panel 13. The angle α of the display panel 13 with respect to the direction perpendicular to the optical axis Lc is set to 30 to 50 degrees. As a result, as shown in Figure 1, the distance difference between the optical path length corresponding to the lower end of the display surface K and the optical path length corresponding to the upper end of the display surface K becomes large, causing the display surface K to tilt along the road surface. Furthermore, the angle of the display panel 13a with respect to the direction perpendicular to the optical axis Lc may be set to an angle β smaller than the angle α of the display panel 13. The angle β is set to 5 to 20 degrees. As a result, as shown in Figure 1, the display surface Ka on which the virtual image Va is displayed is upright with respect to the road surface. In this way, by providing the display panel 13 in an orientation that is not perpendicular to the optical axis Lc, stray light is reflected in a direction different from that of the reflection mirror 31.

[0022] Next, the configuration of the diffusion member 30 will be described. As shown in Figure 3, the diffusion member 30 is located on the light incident surface side of the display panel 13 and is oriented along the display panel 13. The diffusion member 30 is a rectangular plate shape that is long in the X direction and short in the Y direction. The diffusion member 30 diffuses the illumination light and radiates the diffused illumination light (transmitted light) to the display panel 13. By diffusing the illumination light, the diffusion member 30 can suppress uneven illumination on the display panel 13. The diffusion member 30 comprises an incident surface 30I facing the light distribution lens 20 and an exit surface 30O facing the display panel 13.

[0023] The diffusion member 30 comprises a base material made of a resin such as PET (polyethylene terephthalate), a diffusion layer formed on the exit surface 30O side, and a back coat layer formed on the incident surface 30I side. This back coat layer has a glossy surface and prevents static charge buildup. This diffusion layer has a structure with a diffusion surface on which a plurality of acrylic beads are arranged. By changing the diameter and density of the acrylic beads, the haze value can be adjusted between the first region 31a and the second region 31b, which will be described later.

[0024] Furthermore, this diffusion layer is not limited to a configuration in which multiple acrylic beads are arranged. For example, this diffusion layer may be made by transferring microlenses onto a UV resin (ultraviolet curing resin) such as a top-hat diffuser plate, or by varying the transmittance through halftone printing or diffusion printing, or by adding microfabrication to a lens substrate such as glass, PMMA (acrylic), or PC (polycarbonate), and gradually changing the particle size of the microfabrication.

[0025] As shown in Figures 3 and 4, the ejection surface 30O comprises a first region 31a and a second region 31b having different haze values. The first region 31a is set to a constant first haze value H1 throughout its entirety. The second region 31b is set to a constant second haze value H2 throughout its entirety. The second haze value H2 is set to a lower value than the first haze value H1. In other words, the degree of diffusion of illumination light transmitted through the first region 31a is stronger than the degree of diffusion of illumination light transmitted through the second region 31b.

[0026] The first region 31a is located below the emission surface 30O, and the second region 31b is located above the emission surface 30O. In this example, the length (height) of the first region 31a in the Y direction is smaller than the length (height) of the second region 31b in the Y direction. For example, the length (height) of the first region 31a in the Y direction is set to half the length (height) of the second region 31b in the Y direction. The first region 31a and the second region 31b are located adjacent to each other. As shown in Figure 3, the first region 31a is located closer to the backlight unit 11 (the emission surface 20t of the light source 19 or light distribution lens 20) than the second region 31b. The first region 31a and the second region 31b are located at the same distance from each other as the display panel 13.

[0027] The first haze value H1 is set to, for example, 30-80%. The second haze value H2 is set to, for example, 10-50%. As an example, the first haze value H1 is set to 67% and the second haze value H2 is set to 44%. Furthermore, it is preferable that the value obtained by subtracting the second haze value H2 from the first haze value H1 be set to a value greater than 10%. That is, it is preferable that the following equation holds true. H1-H2 > 10% The haze values ​​listed above are examples only and are not limited to these numbers.

[0028] As described above, by creating a difference in haze values ​​between the first region 31a and the second region 31b of the diffusion member 30, variations in the illuminance (brightness) of the illumination light to the display panel 13 caused by the difference in distance between the display panel 13 and the backlight unit 11 (for example, the emission surface 20t) are suppressed. This point will be explained in detail below. As shown in Figure 3, the distance Db between the second region 31b and the light source 19 is set to be greater than the distance Da between the first region 31a and the light source 19. Therefore, the degree of diffusion of the illumination light reaching the second region 31b is more advanced than the degree of diffusion of the illumination light reaching the first region 31a. As a result, the illuminance of the illumination light reaching the second region 31b is lower than the illuminance of the illumination light reaching the first region 31a. To compensate for this difference in illuminance, the second haze value H2 of the second region 31b is set lower than the first haze value H1 of the first region 31a. The lower the haze value, the less likely the illuminance of the illumination light emitted from the diffusion member 30 is to decrease. Therefore, variations in the illuminance of the illumination light irradiated from the diffusion member 30 onto the display panel 13 are suppressed, and more uniform illumination can be achieved. Thus, the display quality, i.e., uniformity, of the image displayed on the display panel 13, and consequently the virtual image V, can be improved. In this regard, in the case of the comparative example, the diffusing member, in which the haze value is constant across the entire emission surface, is unable to compensate for the above-mentioned difference in illuminance, resulting in variations in the illuminance of the illumination light irradiated onto the display panel 13. This leads to a decrease in the display quality and uniformity of the image displayed on the display panel 13, and consequently, the display quality and uniformity of the virtual image V.

[0029] (effect) According to the embodiment described above, the following effects are achieved. (1) The diffusing member 30 has an emitting surface 30O which is an example of a diffusing region that diffuses and transmits light, and radiates the transmitted light to a display panel 13 which is an example of a display. The emitting surface 30O comprises a first region 31a where the haze value is set to a first haze value H1, and a second region 31b where the haze value is set to a second haze value H2 which is lower than the first haze value H1. With this configuration, even if the display panel 13 is tilted with respect to the optical axis Lc of the illumination light, the haze values ​​of the first region 31a and the second region 31b are set to be different in order to reduce unevenness in the illumination light on the display panel 13. This makes it possible to reduce unevenness in the illumination light on the display panel 13.

[0030] (2) The first haze value H1 is set to 30-80%. The difference between the first haze value H1 and the second haze value H2 is set to be greater than 10%. This configuration makes it possible to reduce unevenness in the illumination of the display panel 13.

[0031] (3) The second haze value H2 is set to 10-50%. The value obtained by subtracting the second haze value H2 from the first haze value H1 is set to be greater than 10%. This configuration makes it possible to reduce unevenness in the illumination of the display panel 13.

[0032] (4) The display device 10 equipped with the diffusion member 30 includes a backlight unit 11 which is an example of an illumination optical system that emits illumination light that travels along the optical axis Lc, and a display panel 13 which emits display light L by receiving transmitted light that has passed through the diffusion member 30. The diffusion member 30 faces the display panel 13 so as to be parallel to it and is provided in a direction that is not perpendicular to the optical axis Lc such that the first region 31a is located closer to the backlight unit 11 than the second region 31b. With this configuration, even if the display panel 13 is tilted at a non-orthogonal angle to the optical axis Lc, the diffusion member 30 reduces unevenness in the illumination of the display panel 13.

[0033] (5) The head-up display device 100, which includes the display device 10, is equipped with a folding mirror 31 and a concave mirror 32, which are examples of a relay optical system that display a virtual image V by guiding the display light emitted by the display device 10 toward a windshield 201, which is an example of a transmissive reflective member. This configuration can reduce brightness unevenness in the virtual image V.

[0034] (6) A vehicle 200, which is an example of a vehicle equipped with a head-up display device 100, is equipped with a windshield 201, which is an example of a transmissive reflective member. This configuration can reduce brightness unevenness in the virtual image V.

[0035] This disclosure is not limited to the embodiments and drawings described above. Modifications (including the deletion of components) can be made as appropriate, provided they do not alter the essence of this disclosure. An example of such a modification is described below.

[0036] (modified version) In the above embodiment, the length (height) of the first region 31a in the Y direction was formed to be smaller than the length (height) of the second region 31b in the Y direction. However, it is not limited to this, and it may be formed to be the same length as the length (height) of the second region 31b in the Y direction, or it may be formed to be larger than the length (height) of the second region 31b in the Y direction.

[0037] In the above embodiment, the diffusion member 30 included a first region 31a set to a first haze value H1 and a second region 31b set to a second haze value H2. However, it is not limited to this, and as shown in Figure 5, in addition to the first region 31a and the second region 31b, it may also include a third region 31c set in a gradient where the haze value gradually changes. The third region 31c is located between the first region 31a and the second region 31b, and is adjacent to both the first region 31a and the second region 31b, respectively. As shown in Figure 6, the haze value H3 of the third region 31c is the same as the first haze value H1 at position P1 adjacent to the first region 31a, and the same as the second haze value H2 at position P2 adjacent to the second region 31b. The haze value H3 gradually decreases as you move from position P1 to position P2. In this example, the haze value H3 changes linearly from position P1 to position P2. However, the haze value H3 may also change in a curved or stepwise manner from position P1 to position P2. According to the above modification, the following effects are achieved. The emission surface 30O is provided between the first region 31a and the second region 31b, and includes a third region 31c which is set so that the haze value gradually decreases as it approaches the second region 31b from the first region 31a. This configuration suppresses large changes in illuminance between the first region 31a and the second region 31b.

[0038] Furthermore, although the diffusion member 30 was configured to change the haze value in the Y direction, it may be configured to change the haze value in the X direction instead, or in addition to this. Moreover, the diffusion member 30 may be configured to change the haze value in a direction inclined with respect to the X and Y directions, in other words, in the diagonal direction of the diffusion member 30.

[0039] In the above embodiment, the haze value was set in a two-step stepwise manner between the first region 31a and the second region 31b, but the haze value may be set in a stepwise manner with three or more steps. Also, the haze value may be set in a gradient manner across the entire region instead of in a stepwise manner. In the above embodiment, the diffusion region was formed on the exit surface 30O of the diffusion member 30, but it is not limited to this, and may be formed on the incident surface 30I, or on both the incident surface 30I and the exit surface 30O. In the above embodiment, the diffusion member 30 may be formed integrally with the light distribution lens 20. In this case, for example, a diffusion region having a first region 31a and a second region 31b is formed on the emission surface 20t of the light distribution lens 20.

[0040] In the above embodiment, the diffusion member 30 was composed of a single diffusion plate, but it may be composed of multiple diffusion plates. For example, as shown in Figure 7, the diffusion member 130 comprises a first diffusion plate 131 and a second diffusion plate 132. The first diffusion plate 131 and the second diffusion plate 132 are set to a constant haze value over their entire area. The second diffusion plate 132 faces the first region 131a of the first diffusion plate 131 and is formed to be smaller in size than the first diffusion plate 131. The second diffusion plate 132 is located corresponding to the lower part of the first diffusion plate 131. The second region 131b of the first diffusion plate 131 does not face the second diffusion plate 132. As a result, the total haze value in the first region 131a where the two diffusion plates 131 and 132 overlap is higher than the haze value in the second region 131b. In this modified example, the configuration is simple because the first diffuser plate 131 and the second diffuser plate 132 do not need to have their haze values ​​changed. Furthermore, three or more diffuser plates may be stacked on top of each other.

[0041] In the above embodiment, the head-up display device 100 was mounted on a vehicle 200, but it is not limited to a vehicle 200 and may be mounted on other vehicles such as airplanes or ships. The transmissive reflective member from which the display light L is projected is not limited to the windshield 201, but may be a dedicated combiner.

[0042] In the above embodiment, the relay optical system included two mirrors 31 and 32, but at least one of the two mirrors 31 and 32 may be omitted, or it may include three or more mirrors. In the above embodiment, the display device 10 was applied to a head-up display device 100, but it is not limited to this, and may be a direct-view type display device.

[0043] In the above embodiment, the display device 10 used a liquid crystal panel, but it is not limited to this; it may also use a laser light scanning method using MEMS (Micro Electro Mechanical Systems) or a method using a DMD (Digital Micro Mirror Device). [Explanation of symbols]

[0044] 1. Sighted person 10 Display device 11 Backlight Unit 13,13a Display Panel 16 Light source substrate 16a Mounting surface 17. Collimating lenses 17a Convex lens section 19 Light source 20 Light Distribution Lenses 20t exit surface 30,130 Diffusion member 30I entrance plane 30O output surface 31 Folding mirror 31a,131a 1st area 31b,131b 2nd area 31c 3rd area 32 Concave mirror 33 Housing 33a Window section 100 Head-Up Display Devices 131 First Diffuser 132 Second Diffuser 200 vehicles 201 Windshield α,β angles H1 First Haze Value H2 Second Haze Value H3 haze value K,Ka display surface L display light P1,P2 position V,Va virtual image Da, Db distance Eb ibox Lc optical axis direction

Claims

1. A diffusion member having a diffusion region that diffuses and transmits light, and radiates the transmitted light to a display, The aforementioned diffusion region is The first region in which the haze value is set to the first haze value, A second region is provided in which the haze value is set to a second haze value that is lower than the first haze value, A display device comprising the aforementioned diffusion member, An illumination optical system that emits light traveling along the optical axis direction onto the diffusing member, The system comprises a display panel which is a display device that emits display light upon receiving the transmitted light that has passed through the diffusion member, The diffusion member is provided in a direction that is inclined non-orthogonal to the optical axis direction such that the first region is located closer to the illumination optical system than the second region. Display device.

2. The diffusion region of the diffusion member comprises a third region provided between the first region and the second region, which is set such that the haze value gradually decreases as one approaches the second region from the first region. The display device according to claim 1.

3. The first haze value of the diffusion member is set to 30 to 80%, The value obtained by subtracting the second haze value from the first haze value is set to be greater than 10%. The display device according to claim 1 or 2.

4. The second haze value of the diffusion member is set to 10 to 50%, The value obtained by subtracting the second haze value from the first haze value is set to be greater than 10%. The display device according to claim 1 or 2.

5. A head-up display device comprising the display device described in claim 1, The relay optical system displays a virtual image by guiding the display light emitted by the display device toward a transmissive reflective member. Head-up display device.

6. A vehicle equipped with a head-up display device according to claim 5, The aforementioned transparent reflective member is provided, vehicle.

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