Display device

Abstract

To provide a display device that improves the visibility of an aerial image by making an original image less visible.SOLUTION: A display device 100 according to the present invention includes a light source 110, a diffusion plate 120, a polarizing plate 130 disposed on the diffusion plate 120, a polarizing plate 150 disposed on a support member 140, a flat polarizing plate 160, a retroreflective plate 170 disposed on the polarizing plate 160, and a polarizing beam splitter 180 disposed to face the retroreflective plate 170. The polarizing plate 130 includes a region inclined downward, the polarizing plate 150 includes a region inclined upward, and light diffused in various directions from the diffusion plate 120 is effectively polarized.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a display device having a function of displaying an aerial image using retroreflection. [Background technology]

[0002] Aerial imaging by retroreflection (AIRR) is known. For example, Patent Document 1 discloses an image display device that is disposed between a half mirror and an image output device and includes a retroreflection member having a plurality of openings through which at least a portion of light output from the image output device passes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-81138 Summary of the Invention [Problem to be solved by the invention]

[0004] Some AIRR aerial image display systems use LEDs as the light source. In this case, the aerial image is a fixed icon, and a notch is cut into the retroreflective sheeting. In addition, to make the product compact, a structure may be adopted in which the optical components, a polarized beam splitter, light source, and retroreflective sheeting are arranged in parallel. In this case, a method using polarization is used to make it difficult for the viewer to see the light source.

[0005] A method for dimming a light source using polarized light will be described with reference to FIG. 1. A display device 10 includes a light source 20, a diffuser 30, a polarizer 40, and a polarizing beam splitter 50, all arranged parallel to one another. Unpolarized light La emitted from the light source 20 passes through the diffuser 30 and enters the polarizer 40, from which polarized light Lb is emitted. The transmission axis of the polarizer 40 is aligned with the reflection axis of the polarizing beam splitter 50, and the light Lb emitted from the polarizer 40 becomes light Lc reflected by the polarizing beam splitter 50. This makes it difficult for an observer U to see the light from the light source 20.

[0006] 2 is a perspective view showing the exterior configuration of a conventional display device. Display device 10 includes a roughly rectangular housing 60, a polarizing beam splitter 50 attached to the surface of housing 60, and a light source 20, a diffuser 30, a polarizing plate 40, and a retroreflective sheet disposed on polarizing plate 40. A ring-shaped through-hole or cutout that serves as the original image P of aerial image Q is formed in the retroreflective sheet, and the ring-shaped aerial image Q is displayed above housing 60.

[0007] Conventional display devices use polarized light to make the light source (original image P) seen through a polarized beam splitter less visible, but in reality, when viewed from a certain angle, there is a range in which the light source (original image P) appears bright, and in this case the light source (original image P) and aerial image Q are seen at the same time, creating an unnatural appearance of the aerial image Q.

[0008] The present invention aims to solve such conventional problems and provide a display device that makes the original image less visible and improves the visibility of the aerial image. [Means for solving the problem]

[0009] The display device of the present invention is capable of displaying an aerial image using retroreflection, and includes a light source, a diffuser disposed on the light source, a first polarizing plate disposed on the diffuser, a second polarizing plate disposed on the first polarizing plate, a retroreflective member disposed on the second polarizing plate and having a design formed thereon for generating an original image by irradiation with the light source, and a polarizing beam splitter disposed opposite the retroreflective member, and the first polarizing plate includes an area that is inclined with respect to the main surface of the second polarizing plate.

[0010] In one embodiment, the first polarizer includes a first tilted region that tilts downward relative to the major surface of the second polarizer and a second tilted region that tilts upward opposite the first tilted region. In one embodiment, the first tilted region and the second tilted region tilt downward and upward at equal angles, respectively. In one embodiment, the directions of the transmission axes of the first polarizer and the second polarizer are aligned with the direction of the reflection axis of the polarizing beam splitter.

[0011] Furthermore, the display device of the present invention is capable of displaying an aerial image using retroreflection, and includes a light source, a diffuser disposed on the light source, a first polarizing plate disposed on the diffuser, a second polarizing plate disposed on the first polarizing plate, a retroreflective member disposed on the second polarizing plate and having a design formed thereon for generating an original image by irradiation with the light source, and a polarizing beam splitter disposed opposite the retroreflective member, wherein the first polarizing plate has a curved shape.

[0012] In one embodiment, the curved shape of the first polarizing plate matches the design of the retroreflective member. In another embodiment, the directions of the transmission axes of the first polarizing plate and the second polarizing plate match the direction of the reflection axis of the polarizing beam splitter. [Effects of the Invention]

[0013] According to the present invention, the first polarizing plate has an inclined region or a curved shape, which allows the light emitted from the light source to be polarized more effectively than when only the second polarizing plate is provided, thereby making it difficult to see the original image formed on the retroreflective member and improving the visibility of the aerial image. [Brief explanation of the drawings]

[0014] [Figure 1] 1A and 1B are diagrams illustrating a method for dimming a light source using polarized light in a conventional display device. [Figure 2] FIG. 1 is a diagram showing the external configuration of a conventional display device. [Figure 3] FIG. 3(A) is a diagram showing a method for dimming a light source using polarized light of a conventional structure, and FIG. 3(B) is a schematic cross-sectional view showing the configuration of a display device according to a first embodiment of the present invention. [Figure 4] 3B is a perspective view and a plan view showing a specific example of the diffusion plate of FIG. [Figure 5] 3B is a perspective view and a plan view showing a specific example of the support member of FIG. [Figure 6] 1 is a schematic cross-sectional view showing an example of the overall configuration of a display device according to a first embodiment of the present invention. [Figure 7] FIG. 10 is a schematic cross-sectional view showing the configuration of a display device according to a second embodiment of the present invention. [Figure 8] 8A and 8B are a perspective view and a plan view showing a specific example of the diffusion plate of FIG. 7. [Figure 9] FIG. 10 is a schematic cross-sectional view showing an example of the overall configuration of a display device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The display device according to the present invention displays aerial images in three-dimensional space using retroreflection without the need for special glasses. Furthermore, the display device according to the present invention makes it possible to provide a highly interactive non-contact user interface for aerial images. It should be noted that the drawings referred to in the following description of the embodiments include exaggerated representations to facilitate understanding of the invention, and do not directly represent the shape or scale of the actual product. [Example]

[0016] Next, an embodiment of the present invention will be described in detail. Fig. 3(A) is a diagram showing a method for dimming a light source using polarized light of a conventional structure, and Fig. 3(B) is a schematic cross-sectional view showing the configuration of a display device according to a first embodiment of the present invention.

[0017] In the conventional method of dimming a light source in a display device 10, light La emitted from the light source 20 that enters the polarizing plate 40 approximately perpendicularly via the diffuser 30 is polarized in the direction of the transmission axis of the polarizing plate 40, and the polarized light Lb becomes light Lc that is reflected by the polarizing beam splitter 50. On the other hand, light that enters the polarizing plate 40 obliquely via the diffuser 30 in the direction of the transmission axis is not sufficiently polarized by the polarizing plate 40, and the unpolarized light Ld is transmitted through the polarizing beam splitter 50 without being reflected by it.

[0018] Generally, polarizers are most effective when light is incident perpendicularly to the polarizer, but the effect of polarizers is reduced when light is incident obliquely. In other words, the greater the angle of incidence of light, the less effective the polarizer becomes.

[0019] As shown in FIG. 3B, the display device 100 of this embodiment includes a light source 110, a diffuser 120, a polarizer 130, a support member 140, polarizers 150 and 160, a retroreflector 170, and a polarizing beam splitter 180.

[0020] The light source 110 is, but is not limited to, one or more LED light sources. One LED light source includes one or more light-emitting elements. In the figure, two light sources 110 are illustrated below the inclined region 124 of the diffuser plate 120, and each light source 110 emits unpolarized light from its top at a certain radiation angle.

[0021] A diffuser 120 is disposed above the light source 110. The diffuser 120 diffuses the light from the light source 110 in various directions to provide a more uniform light to the polarizer 130. The diffuser 120 has a flat region 122 that is generally perpendicular to the optical axis of the light source 110 and a region 124 that is inclined from the flat region 122.

[0022] 4 shows a specific example of the diffuser plate 120. FIG. 4(A) is a perspective view of the diffuser plate, and FIG. 4(B) is a plan view of the diffuser plate. The diffuser plate 120 has a roughly rectangular outer shape, and in its center, An octagonal flat region 122 and eight inclined regions 124 connected to the flat region 122 are formed. The inclination angle of the inclined regions 124 is not particularly limited, but for example, the flat region is inclined at an angle of 30 to 45 degrees with respect to the main surface of the region 122. The shape of the flat region 122 may be other shapes besides an octagon, such as a triangle, a rectangle, or a hexagon.

[0023] A polarizing plate 130 is disposed on the diffuser plate 120. The polarizing plate 130 is an optical element that converts light incident from the diffuser plate 120 into light polarized in a certain direction. The shape and size of the polarizing plate 130 are not particularly limited, but for example, the polarizing plate 130 is a polarizing film that is attached to the entire surface of the diffuser plate 120 or to the flat region 122 and the inclined region 124. FIG. 4(B) shows an example in which a polarizing film is attached to the flat region 122 and the inclined region 124. In this example, the polarizing plate 130 includes a flat region 132 and an inclined region 134. The dashed-dotted line C1 in the figure represents the transmission axis of the polarizing plate 130, i.e., the polarization direction.

[0024] A support member 140 is disposed on the diffuser plate 120. The support member 140 is made of a light-transmitting material and includes an opening 142 facing the flat region 122 of the diffuser plate 120 and an inclined region 144 facing the inclined region 124 of the diffuser plate 120. The inclined region 144 is not particularly limited, but may be inclined at the same angle as the inclined region 124, for example, on the opposite side. A polarizer 150 is disposed on the inclined region 144 of the support member 140.

[0025] Fig. 5 shows a specific example of a support member. Fig. 5(A) is a perspective view of support member 140, and Fig. 5(B) is a plan view of support member 140. Support member 140 has a roughly rectangular outer shape, and an octagonal opening 142 is formed in the center thereof, and eight upwardly sloping regions 144 are formed so as to connect to opening 142. Opening 142 has a shape and size corresponding to flat region 122 of diffuser plate 120, and the eight sloping regions 144 have shapes and sizes corresponding to the eight sloping regions 124 of diffuser plate 120, respectively.

[0026] The polarizing plate 150 is disposed on the entire surface of the support member 140 or on the inclined region 144. The shape and size of the polarizing plate 150 are not particularly limited. For example, the polarizing plate 150 is a polarizing film. FIG. 5B shows an example in which a polarizing film is attached to the inclined region 144. In this example, the polarizing plate 150 includes an octagonal opening 152 in the center and a downwardly inclined region 154. The dashed-dotted line C2 in the figure represents the transmission axis, i.e., the polarization direction, of the polarizing plate 150. The transmission axis C2 is in the same direction as the transmission axis C1 of the polarizing plate 130. In one embodiment, the downwardly inclined region 154 of the polarizing plate 150 and the upwardly inclined region 134 of the polarizing plate 130 are disposed approximately symmetrically with respect to the flat region 132 of the polarizing plate 130 or the flat region of the diffuser 120.

[0027] The polarizing plate 160 is disposed above the support member 140 and the polarizing plate 150. The polarizing plate 160 has a generally rectangular shape, and its main surface is generally perpendicular to the optical axis of the light source 110. The transmission axis of the polarizing plate 160 is in the same direction as the transmission axes C1 and C2 of the polarizing plates 130 and 150.

[0028] A retroreflector 170 is disposed on the polarizing plate 160. The retroreflector 170 is an optical element that reflects light in the same direction as the incident light, and is composed of, for example, prism-type retroreflectors such as triangular pyramid-type retroreflectors and full cube-corner-type retroreflectors, or bead-type retroreflectors. A phase adjustment film such as a λ / 4 film or a protective film is attached to the surface of the retroreflector 170. The phase adjustment film adjusts the phase between the incident light and the reflected light on the retroreflector 170, allowing the light reflected by the retroreflector 170 to pass through the polarizing beam splitter 180.

[0029] Furthermore, a design that will become the original image of the aerial image is formed on the retroreflector 170. The design is constituted by through-holes or cutouts 172 formed in the retroreflector 170. The back side of the retroreflector 170 is illuminated by light from the light source 110, and a portion of the light passes through the through-holes 172 to generate the design that will become the original image. The design is not particularly limited, but may be, for example, letters, figures, symbols, icons, etc.

[0030] The polarizing beam splitter 180 is disposed so as to face the polarizing plate 160 and the retroreflector 170 in a generally parallel relationship. The reflection axis of the polarizing beam splitter 180 is in the same direction as the transmission axis C1 of the polarizing plate 130, the transmission axis C2 of the polarizing plate 150, and the transmission axis of the polarizing plate 160. As a result, polarized light that has passed from the light source 110 through the polarizing plates 130, 150, and 160 is reflected by the polarizing beam splitter 180. Meanwhile, the polarization direction of the light that is reflected by the polarizing beam splitter 180 and incident on the retroreflector 170 is adjusted by passing through the phase adjustment film. In other words, the polarization direction of the light retroreflected by the retroreflector 170 does not coincide with the reflection axis of the polarizing beam splitter 180, and the light passes through the polarizing beam splitter 180 to form an aerial image. The aerial image is displayed at a position symmetrical to the light source (here, the position where the original image is generated) with respect to the main surface of the polarizing beam splitter 180.

[0031] Next, the operation of the display device according to this embodiment will be described. Unpolarized light emitted radially from the light source 110 is incident on the octagonal diffuser 120 as shown in FIG. 4A. The incident light is diffused in various directions by the diffuser 120, and the diffused light is incident on the polarizer 130. The polarizer 130 effectively polarizes light incident from a generally perpendicular direction, but does not sufficiently polarize light incident from an oblique direction, or polarizes it very little. In other words, the vibration of light in directions other than the transmission axis of the polarizer 130 is not sufficiently attenuated. The light transmitted through the polarizer 130 again enters the polarizer 150, and even light that is not sufficiently polarized by the polarizer 130 and incident on the polarizer 150 in a generally perpendicular direction is polarized by the polarizer 150.

[0032] In this way, by interposing two polarizing plates 130 and 150 with different tilt angles in addition to polarizing plate 160, the proportion of light that enters the polarizing plate perpendicularly increases, and most of the light emitted from light source 110 is polarized. As a result, the proportion of unpolarized light Ld that enters polarizing plate 40 obliquely as shown in FIG. 3(A) can be reduced. As a result, the original image can be made less visible through the polarizing beam splitter, and the visibility of the aerial image can be improved.

[0033] 6A and 6B are diagrams showing the overall configuration of the display device of this embodiment, where FIG. 6A is a diagram showing a vertical cross section of the display device, and FIG. 6B is a perspective view of the display device cut in the vertical direction.

[0034] A circuit board 112 on which a light source 110 is mounted is disposed on the bottom side of the display device 100. A diffuser 120 and a polarizer 130, which are octagonal structures, are disposed on the circuit board 112. A polarizer 150 is disposed on top of that via a support member 140, and a flat polarizer 160 is disposed above that. A retroreflector 170 is disposed on the polarizer 160, and a ring-shaped through-hole 172 is formed in the retroreflector 170 as a design for generating the original image. A polarizing beam splitter 180 is also disposed opposite the retroreflector 170. A pair of inclined retroreflectors 174 and a pair of retroreflectors 176 extending perpendicularly therefrom are attached to both ends of the retroreflector 170 in the longitudinal direction, and a pair of acrylic plates 190 extending perpendicularly are attached to both ends of the retroreflector 170 in the lateral direction. The outer periphery of the polarizing beam splitter 180 is attached to the ends of a pair of retroreflectors 176 and a pair of acrylic plates 190 .

[0035] When light source 110 is driven, polarized light illuminates the rear surface of retroreflector 170, and the light that passes through through-holes 172 in retroreflector 170 displays aerial image Q corresponding to the design of the original image above polarizing beam splitter 180. The use of a pair of polarizing plates 130, 150 with different inclination angles improves polarization efficiency, making it difficult to see the original image inside through polarizing beam splitter 180 and improving the visibility of aerial image Q.

[0036] Next, a second embodiment of the present invention will be described. Fig. 7 is a schematic cross-sectional view showing the configuration of a display device according to the second embodiment, and the same components as those in the first embodiment shown in Fig. 3(A) are given the same reference numerals. In the first embodiment, a pair of polarizers 130 and 150 inclined at different angles are disposed between the light source 110 and the polarizer 160, but in the second embodiment, a curved diffuser 200 and a curved polarizer 210 are disposed between the light source 110 and the polarizer 160.

[0037] The display device 100A of the second embodiment includes a light source 110, a diffuser 200, a polarizer 210, a polarizer 160, a retroreflector 170, and a polarizing beam splitter 180. The diffuser 200 is disposed above the light source 110 and has a flat region 202 that is substantially perpendicular to the optical axis of the light source 110, and a donut-shaped or annular recessed region 204 formed around the flat region 202. The surface of the recessed region 204 has an arc-shaped or curved surface. In a preferred embodiment, the recessed region 204 is aligned with the position of the through-hole 172 of the retroreflector 170; for example, the diffuser 200 is disposed so that the center of the through-hole 172 substantially coincides with the center of the recessed region 204.

[0038] Fig. 8 shows a specific example of a diffuser plate 200. Fig. 8(A) is a perspective view of the diffuser plate, and Fig. 8(B) is a plan view of the diffuser plate. The diffuser plate 200 has a roughly rectangular outer shape, and in its central portion, a circular flat region 202 and an annular recessed region 204 connected to the flat region 202 are formed. The shape of the flat region 202 is not particularly limited to a circle, and may be, for example, a rectangle or a polygon.

[0039] Polarizing plate 210 is disposed on diffuser plate 200. There are no particular limitations on the shape or size of polarizing plate 210, but for example, polarizing plate 210 is a polarizing film, and is attached so as to follow the curved surface of recessed region 204 of diffuser plate 200. Fig. 8(B) shows an example in which a polarizing film is attached on recessed region 204, and dashed dotted line C3 in the figure indicates the transmission axis of polarizing plate 210, i.e., the polarization direction.

[0040] Unpolarized radial light from light source 110, such as an LED, enters diffuser plate 200, and the light that enters diffuser plate 200 is diffused in various directions by diffuser plate 200. In this case, light L1, L2, and L3 that enters polarizer plate 210 from diffuser plate 200 at a substantially right angle are polarized relatively effectively, but light L4 and L5 that enter polarizer plate 210 from an oblique direction are not sufficiently polarized or effectively polarized by polarizer plate 210. Light L4 and L5 that pass through polarizer plate 210 then enter polarizer plate 160 again, and even light that is not polarized by polarizer plate 210 but that enters polarizer plate 160 from a substantially perpendicular direction is polarized there.

[0041] The semicircular polarizer 210 effectively polarizes much of the light diffused by the diffuser 200 by directing it in a generally perpendicular direction, but light that is not polarized by the polarizer 210 can be polarized by the polarizer 160.

[0042] 9A and 9B are diagrams showing the overall configuration of a display device of the second embodiment, where FIG. 9A is a diagram showing a vertical cross section of the display device, and FIG. 9B is a perspective view cut in the vertical direction of the display device, and the same reference numbers are used for the same configurations as in the first embodiment shown in FIG.

[0043] A circuit board 112 on which a light source 110 is mounted is disposed on the bottom side of the display device 100A. A diffuser 200 including a recessed region 204 and a curved polarizer 210 are disposed on the circuit board 112. A flat polarizer 160 is disposed above the diffuser 200 and a retroreflector 170 is disposed above the flat polarizer 160. A ring-shaped through-hole 172 is formed in the retroreflector 170 as a design for generating the original image. A polarizing beam splitter 180 is disposed opposite the retroreflector 170.

[0044] When light source 110 is driven, polarized light illuminates the rear surface of retroreflector 170, and the light that passes through through-holes 172 in retroreflector 170 displays aerial image Q corresponding to the design of the original image above polarizing beam splitter 180. The use of curved semicircular arc polarizing plate 210 improves polarization efficiency, making it difficult to see the original image inside through polarizing beam splitter 180, and improving the visibility of aerial image Q.

[0045] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention described in the claims. [Explanation of symbols]

[0046] 100, 100A: Display device 110: Light source 120, 200: Diffuser 130, 150, 160, 210: Polarizing plate 140: Support member 170, 174, 176: Retroreflective plates 172:Through hole or notch 180: Polarizing beam splitter 190: Acrylic board P: Original image (through hole or notch) Q: Aerial image

Claims

1. A display device capable of displaying an aerial image using retroreflection, A light source and a diffusion plate disposed on the light source; a first polarizing plate disposed on the diffusion plate; a second polarizing plate disposed on the first polarizing plate; a retroreflective member disposed on the second polarizing plate and having a design formed thereon for generating an original image by irradiation with the light source; a polarizing beam splitter disposed opposite the retroreflective member, A display device, wherein the first polarizing plate includes a region that is inclined with respect to a major surface of the second polarizing plate.

2. 2. The display device according to claim 1, wherein the first polarizer includes a first inclined region that is inclined downward with respect to the main surface of the second polarizer, and a second inclined region that faces the first inclined region and is inclined upward.

3. 3. The display device of claim 2, wherein the first and second tilted regions are tilted downward and upward at equal angles, respectively.

4. 2. The display device of claim 1, wherein the directions of the transmission axes of the first polarizer and the second polarizer are aligned with the direction of the reflection axis of the polarizing beam splitter.

5. A display device capable of displaying an aerial image using retroreflection, A light source and a diffusion plate disposed on the light source; a first polarizing plate disposed on the diffusion plate; a second polarizing plate disposed on the first polarizing plate; a retroreflective member disposed on the second polarizing plate and having a design formed thereon for generating an original image by irradiation with the light source; a polarizing beam splitter disposed opposite the retroreflective member, The display device, wherein the first polarizing plate has a curved shape.

6. The display device according to claim 5 , wherein the curved shape of the first polarizing plate matches a design of the retroreflective member.

7. 6. The display device of claim 5, wherein the directions of the transmission axes of the first polarizer and the second polarizer are aligned with the direction of the reflection axis of the polarizing beam splitter.

Images