Projection type display device

Abstract

The present invention provides a projection-type display device that can efficiently utilize light from a light source to create a projected image. [Solution] The projection display device 100 includes a projector 10 having a light emitting unit 10A that emits display light L, and a pair of mirrors 21L, 21R arranged facing the light emitting unit 10A, which reflect the display light L from the projector 10 in directions away from each other to project images VL, VR onto projection surfaces 203L, 203R. The projector 10 includes a laser light source that emits illumination light, a spatial phase modulator that modulates the illumination light into display light by displaying a computer-generated hologram in a CGH modulation region, and a control unit that generates a computer-generated hologram. The control unit generates a computer-generated hologram such that the brightness of the display light L in the area Ar corresponding to the area between the pair of mirrors 21L, 21R becomes zero.

Description

Technical Field

[0006] , , , , ,

[0001] The present disclosure relates to a projection display device.

Background Art

[0002] The projector described in Patent Document 1 projects an image onto a projection target by emitting display light generated based on light from a light source.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1 above, there is a possibility that the light from the light source cannot be effectively used for the projected image.

[0005] In view of the above actual situation, the present disclosure is made, and an object thereof is to provide a projection display device that can efficiently use the light from the light source for the projected image.

Means for Solving the Problems

[0006] To achieve the above object, a projection display device according to a first aspect of the present disclosure includes a projector having a light emitting unit that emits display light, and a pair of mirrors arranged to face the light emitting unit, which reflect the display light from the projector in directions away from each other to project an image onto a projection surface. The projector includes a light source that emits illumination light, and a spatial phase modulator that modulates the illumination light into the display light by displaying a computer-generated hologram in a modulation region. The system comprises a control unit for generating the aforementioned computer-generated hologram, The control unit generates the computer-generated hologram such that the brightness of the display light in the area corresponding to the space between the pair of mirrors becomes zero.

[0007] To achieve the above objective, the projection display device relating to the second aspect of this disclosure is: A projector having a light-emitting section that emits display light, The system comprises a pair of mirrors arranged facing the light emission section, which reflect the display light from the projector away from each other to project an image onto the surface to be projected, The aforementioned projector is A light source that emits illumination light, A spatial phase modulator that modulates the illumination light by displaying a computer-generated hologram in the modulation region, A display element that receives the illumination light from the spatial phase modulator and emits the display light, The system comprises a control unit for generating the aforementioned computer-generated hologram, The control unit generates the computer-generated hologram such that the brightness of the display light in the area corresponding to the space between the pair of mirrors becomes zero. [Effects of the Invention]

[0008] According to this disclosure, light from a light source can be efficiently utilized for the projected image. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic front view of an instrument panel in a vehicle interior equipped with a projection-type display device according to the first embodiment of this disclosure. [Figure 2] This is a schematic bottom view of the projection-type display device according to the first embodiment. [Figure 3] This is a block diagram of a projection-type display device according to the first embodiment. [Figure 4] This is a schematic diagram showing the CGH modulation region according to the first embodiment. [Figure 5]This is a schematic diagram showing the CGH modulation region according to the first embodiment. [Figure 6] This is a block diagram of a projection-type display device according to the second embodiment. [Figure 7] This is a schematic diagram showing the emission pattern of illumination light from a spatial phase modulator to a display element according to the second embodiment. [Modes for carrying out the invention]

[0010] (First Embodiment) A projection-type display device according to the first embodiment of this disclosure will be described with reference to the drawings. As shown in Figure 1, the projection display device 100 is mounted on the vehicle 200. In this example, the projection display device 100 is mounted on the instrument panel 202 where the steering wheel 201 is located inside the vehicle. Specifically, the projection display device 100 is positioned on the back side of the center information display (CID) 205, which is a display that shows vehicle information, as seen from the driver's perspective, on the instrument panel 202. The projection display device 100 is located in the center of the instrument panel 202 in the left-right direction Ld, Rd as seen from the driver (viewer). The projection display device 100 displays projected images VL and VR by projecting display light L onto the projection surfaces 203L and 203R of the instrument panel 202 on both the left and right sides of the projection display device 100. In this embodiment, the projected images VL and VR are three-dimensional images and display patterns, vehicle information, information other than vehicle information, etc.

[0011] As shown in Figure 2, the projection display device 100 comprises a projector 10 and a pair of mirrors 21L and 21R. A pair of mirrors 21L and 21R are arranged facing the light emitting part 10A of the projector 10 with a gap G in the left - right directions Ld and Rd. That is, the side surface of the mirror 21L in the right - hand direction Rd and the side surface of the mirror 21R in the left - hand direction Fd face each other with the gap G. The mirror 21L receives and reflects the left - hand half of the display light L emitted from the light emitting part 10A, and the mirror 21R receives and reflects the right - hand half of the display light L emitted from the light emitting part 10A. The pair of mirrors 21L and 21R respectively reflect the display light L from the projector 10 toward the projection surfaces 203L and 203R on both the left and right sides. The display light L reflected by the mirrors 21L and 21R is split into two in directions away from each other. The pair of mirrors 21L and 21R are each rectangular - plate - shaped plane mirrors, and are provided inclined in the left - right directions Ld and Rd in a direction away from the light emitting part 10A of the projector 10 as they separate from each other in the left - right directions Ld and Rd. Therefore, the optical paths between the pair of mirrors 21L and 21R and the light emitting part 10A become longer as they proceed to both outer sides in the left - right directions Ld and Rd. The gap G is, for example, 8 mm to 12 mm, and as an example, is about 10 mm.

[0012] As shown in FIG. 3, the projector 10 includes a laser light source 11, a spatial light modulator 13, a projection lens 18, a polarization beam splitter 19, and a control unit 15.

[0013] The laser light source 11 is a light source that emits laser light as illumination light IL. For example, it is a laser diode that emits green laser light. Note that the laser light source 11 may emit light of a single (one color) color or light of a plurality of colors. For example, it may be a light source that emits light of three colors, namely R (Red), G (Green), and B (Blue).

[0014] The spatial phase modulator 13 is, for example, a reflective modulator (spatial light modulator) that displays an interference fringe image. The spatial phase modulator 13 receives the illumination light IL and reproduces a three-dimensional video while displaying the interference fringe image (CGH image). The spatial phase modulator 13 emits display light L related to this three-dimensional video. This interference fringe image is, for example, a computer-generated hologram (CGH: Computer-Generated Hologram) generated using computer-generated holography. The spatial phase modulator 13 is, for example, an LCOS-SLM (Liquid Crystal on Silicon - Spatial Light Modulator).

[0015] The polarization beam splitter 19 is an optical device that selectively reflects or transmits only light with a specific polarization state. The polarization beam splitter 19 transmits the illumination light IL from the laser light source 11 toward the spatial phase modulator 13 and reflects the display light L from the spatial phase modulator 13 toward the projection lens 18.

[0016] The projection lens 18 is fitted into the opening of the housing 14 of the projector 10, and the display light L is transmitted toward the outside of the projector 10.

[0017] The control unit 15 is a control computer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 15 includes a CGH generator 15A and a laser controller 15B as a functional configuration realized by the cooperation of hardware and software. The laser controller 15B controls the lighting of the laser light source 11.

[0018] The CGH generator 15A generates a CGH image in the CGH modulation region A to generate the display light L, and displays the generated CGH image (image of interference fringes) on the spatial phase modulator 13. The CGH modulation region A is a rectangle that is long in the left-right direction Ld, Rd and short in the up-down direction Ud, Dd. Here, the left-right direction Ld, Rd of the CGH modulation region A is the same direction as the left-right direction Ld, Rd as seen from the viewer, with respect to the display light L, and the up-down direction Ud, Dd of the CGH modulation region A is the up-down direction or depth direction as seen from the viewer, with respect to the display light L. As shown in Figure 4, the CGH modulation region A comprises a used region A1 and an unused region A2. Unused region A2 is located in the center of the left-right direction Ld, Rd of CGH modulation region A and extends across the entire area of ​​the up-down direction Ud, Dd of CGH modulation region A. Unused region A2 forms a long rectangle in the up-down direction Ud, Dd.

[0019] The unused area A2 corresponds to area Ar (see Figure 2) where the display light L reaches the gap G between the pair of mirrors 21L and 21R. Area Ar is formed such that its cross-sectional area increases as it moves from the light emission section 10A towards the gap G. Interference fringes are generated in the unused area A2 such that the brightness of the display light L within area Ar is zero, i.e., black. Area Ar divides the display light L into two parts in the left-right direction Ld and Rd. The usable area A1 is set on both sides of the unused area A2 in the left-right direction Ld and Rd, and interference fringes are generated that can reproduce the projected images VL and VR. As described above, since no unnecessary brightness increase or light interference occurs in the display light L within area Ar, the brightness of the projected image VL and VR can be increased accordingly. Each usable area A1 is a rectangle in which the lengths of Ud and Dd in the vertical direction are the same as those of the unused area A2, and the lengths of Ld and Rd in the horizontal direction are longer than those of the unused area A2.

[0020] Furthermore, as shown in the upper part of Figure 5, the two usable areas A1 have brightness adjustment patterns P1 to P4 formed therein, in which the brightness of the display light L (projected image VL, VR) increases as you move outwards in the left-right direction Ld, Rd away from the unused area A2. The brightness adjustment patterns P1 to P4 are set in the order P1 → P2 → P3 → P4, starting from the area closest to the unused area A2. Brightness adjustment patterns P1 to P4 of the usable area A1 located to the right of unused area A2 (Rd) correspond to the projected image VR, and brightness adjustment patterns P1 to P4 of the usable area A1 located to the left of unused area A2 (Ld) correspond to the projected image VL. Brightness adjustment pattern P1 is located at the end of the projected image VR on the side of the light emitting part 10A in the left and right directions Ld and Rd, and brightness adjustment pattern P4 is located at the end of the projected image VR on the side furthest from the light emitting part 10A in the left and right directions Ld and Rd. As shown in the lower part of Figure 5, the brightness set by the brightness adjustment patterns P1 to P4 is set in steps so that it increases as it moves further away from the unused area A2. The brightness difference between two adjacent brightness adjustment patterns P1 to P4 is set to a constant value. Furthermore, the brightness difference does not have to be constant; for example, it may be set so that the brightness difference increases as the area moves away from the unused area A2 in the left and right directions Ld and Rd. Also, this brightness is not limited to a step-like change, but may change linearly.

[0021] In order to make the projection display device 100 more compact, it is preferable that the pair of mirrors 21L and 21R be positioned close to the light emission section 10A of the projector 10. However, in this case, the incident angle θ (see Figure 2) of the display light L with respect to the projection surfaces 203L and 203R becomes smaller. The incident angle θ is set, for example, to 5° to 30°. When the incident angle θ becomes smaller in this way, the uniformity of the projected images VL and VR in the left and right directions Ld and Rd decreases, and chromatic aberration increases. Specifically, the magnification of the projected images VL and VR at positions far from the projector 10 is greater than the magnification of the light-emitting part 10A within the projected images VL and VR at positions close to it. Therefore, the brightness of the projected images VL and VR at positions far from the light-emitting part 10A tends to be lower. Consequently, the uniformity tends to decrease in configurations without brightness adjustment patterns P1 to P4. In this embodiment, the brightness adjustment patterns P1 to P4 increase the brightness of the projected images VL and VR at positions far from the light-emitting unit 10A compared to the brightness at positions close to the light-emitting unit 10A. This suppresses a decrease in uniformity. Note that while interference fringes are actually displayed in the CGH modulation region A, they are omitted in Figures 4 and 5.

[0022] (Effects of the first embodiment) The first embodiment described above provides the following effects. (1) The projection display device 100 includes a projector 10 having a light emitting unit 10A that emits display light L, and a pair of mirrors 21L, 21R arranged facing the light emitting unit 10A, which reflect the display light L from the projector 10 in directions away from each other to project images VL, VR onto projection surfaces 203L, 203R. The projector 10 includes a laser light source 11, which is an example of a light source that emits illumination light IL, a spatial phase modulator 13 that modulates the illumination light IL into display light L by displaying a computer-generated hologram (CGH image) in a CGH modulation region A, and a control unit 15 that generates a computer-generated hologram. The control unit 15 generates a computer-generated hologram such that the brightness of the display light L in the area Ar corresponding to the area between the pair of mirrors 21L, 21R becomes zero. This configuration eliminates wasted light in the area Ar corresponding to the pair of mirrors 21L and 21R, allowing for efficient use of light from the laser light source 11. Furthermore, a single projector 10 can display two physically separated projection images, VL and VR.

[0023] (2) The control unit 15 generates a computer-generated hologram in which multiple brightness adjustment patterns P1 to P4 are set within the CGH modulation region A so as to reduce the variation in brightness of the projected images VL and VR depending on the distance from the light emission unit 10A. As mentioned above, this configuration makes it possible to suppress the decrease in uniformity.

[0024] (Second Embodiment) A projection-type display device according to the second embodiment of this disclosure will be described with reference to the drawings. The following description will focus on the differences from the first embodiment.

[0025] As shown in Figure 6, the projector 110 includes a display element 17 in addition to the configuration of the first embodiment, and the control unit 15 includes a display element controller 15C in addition to the configuration of the first embodiment. In this embodiment, the illumination adjustment unit 16 is configured by a spatial phase modulator 13 and a polarizing beam splitter 19. That is, in the first embodiment, the spatial phase modulator 13 generated and emitted display light L, but in this embodiment, the spatial phase modulator 13 generates illumination light IL and emits it to the display element 17, and the display element 17 receives the illumination light IL and generates and emits display light L.

[0026] The display element 17 is a DMD (Digital Micro Mirror Device). The display element 17 receives illumination light IL from the illumination adjustment unit 16, generates display light L, and radiates it toward the projection lens 18. This display light L projects two-dimensional projection images VL and VR. The spatial phase modulator 13 controls the illumination light IL emitted to the display element 17 by generating a CGH image having brightness adjustment patterns P1 to P4 in the CGH modulation region A, similar to the first embodiment described above. Specifically, as shown in Figure 7, the illumination light IL from the spatial phase modulator 13 is split into two beams, Ld and Rd, in the left-right direction and radiated to the display element 17, such that the brightness of region Am, corresponding to area Ar (see Figure 2), is zero. As a result, the brightness of the display light L within area Ar becomes zero, similar to the first embodiment described above. Note that the polarization beam splitter 19 is omitted in Figure 7.

[0027] (Effects of the second embodiment) The second embodiment described above provides the following effects. The projection display device 100 includes a projector 110 having a light emitting unit 10A that emits display light L, and a pair of mirrors 21L, 21R arranged facing the light emitting unit 10A, which reflect the display light L from the projector 110 away from each other to project images VL, VR onto projection surfaces 203L, 203R. The projector 110 includes a laser light source 11 that emits illumination light IL, a spatial phase modulator 13 that modulates the illumination light IL by displaying a computer-generated hologram (CGH image) in a CGH modulation region A, a display element 17 that receives the illumination light IL from the spatial phase modulator 13 and emits display light L, and a control unit 15 that generates a computer-generated hologram. The control unit 15 generates a computer-generated hologram such that the brightness of the display light L in the area Ar corresponding to the pair of mirrors 21L, 21R becomes zero. This configuration eliminates wasted light in the area Ar corresponding to the pair of mirrors 21L and 21R, allowing for efficient use of light from the laser light source 11.

[0028] 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.

[0029] (modified version) In the embodiments described above, the projection-type display device 100 was mounted on the instrument panel 202 inside the vehicle cabin, but it can be mounted in any position inside the vehicle cabin, for example, on the ceiling or door surface. In this case, the projection surfaces 203L and 203R may be surfaces other than the instrument panel 202. The projection-type display device 100 may also be mounted outside the vehicle cabin, for example, on a side mirror. In this case, the projection surfaces 203L and 203R may be the vehicle body or the road surface. Furthermore, the projection display device 100 does not necessarily have to be mounted on a vehicle, and may be configured as a standalone product. In each of the above embodiments, the projection lens 18 can be omitted. In each of the above embodiments, the polarizing beam splitter 19 can be omitted. In each of the above embodiments, the width lengths of the left-right direction Ld and Rd of the brightness adjustment patterns P1 to P4 may be made smaller as they move away from the unused area A2 in the left-right direction Ld and Rd, or conversely, they may be made larger, or the width lengths of each of the brightness adjustment patterns P1 to P4 may be made the same. In each of the above embodiments, the number of brightness adjustment patterns P1 to P4 in the CGH modulation region A is not limited to four, but can be changed as appropriate, and may be three or fewer, or five or more. Furthermore, the brightness adjustment patterns P1 to P4 may be omitted. [Explanation of Symbols]

[0030] 10,110…Projector, 10A…Light emission unit 11… Laser light source 13…Spatial Phase Modulator 14…Cabinet 15...Control unit, 15A...CGH generator, 15B...Laser controller, 15C...Display element controller 16…Lighting adjustment unit 17…Display element 18…Projection lens 19…Polarizing beam splitter 21L, 21R… Mirror 100...Projection display device 200…Vehicle, 201…Steering wheel, 202…Instrument panel, 203L, 203R…Projection surface, 205…Center information display A...CGH modulation area, A1...Used area, A2...Unused area, P1~P4...Brightness adjustment pattern Ar... Area, G... Gap, L... Indication light, IL... Illumination light, VL, VR... Projected image, θ... Incident angle Ud...Upward, Dd...Downward, Ld...Leftward, Rd...Rightward

Claims

1. A projector having a light-emitting section that emits display light, The system comprises a pair of mirrors arranged facing the light emission section, which reflect the display light from the projector away from each other to project an image onto the surface to be projected, The aforementioned projector is A light source that emits illumination light, A spatial phase modulator that modulates the illumination light into the display light by displaying a computer-generated hologram in the modulation region, The system comprises a control unit for generating the aforementioned computer-generated hologram, The control unit generates the computer-generated hologram such that the brightness of the display light in the area corresponding to the space between the pair of mirrors becomes zero. Projection display device.

2. A projector having a light-emitting section that emits display light, The system comprises a pair of mirrors arranged facing the light emission section, which reflect the display light from the projector away from each other to project an image onto the surface to be projected, The aforementioned projector is A light source that emits illumination light, A spatial phase modulator that modulates the illumination light by displaying a computer-generated hologram in the modulation region, A display element that receives the illumination light from the spatial phase modulator and emits the display light, The system comprises a control unit for generating the aforementioned computer-generated hologram, The control unit generates the computer-generated hologram such that the brightness of the display light in the area corresponding to the space between the pair of mirrors becomes zero. Projection display device.

3. The control unit generates the computer-generated hologram in which multiple brightness adjustment patterns are set within the modulation region so that the variation in brightness of the projected image is reduced according to the distance of the projected image from the light-emitting unit. The projection display device according to claim 1 or 2.

Images