Display device

Abstract

To provide a display device capable of moving a viewpoint range of an image at will without using a large-scale device for moving an optical component mechanically.SOLUTION: A head-up display device H having a space phase modulator 13 for modulating incident light from a light source 11 and forming image light based on a computer generation hologram and a control section 3 for controlling the space phase modulator 13 further includes a micro lens array 20 for refracting image light formed by the space phase modulator 13. The space phase modulator 13 constitutes a phase type hologram capable of concentrating all of incident light from the light source 11 in image light, image light formed by the space phase modulator 13 is formed by multiple pixel spots SP, the size of the pixel spots SP is formed to be smaller than the size of one lens area 20a of the micro lens array 20, and the control section 3 selects irradiation positions of the pixel spots SP in the lens area 20a.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] There is known a display device that uses a spatial light modulator (SLM) to display an image including interference fringes based on a computer-generated hologram (CGH). For example, a projector disclosed in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-151444 A [Patent Document 2] JP 2023-58418 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with this type of display device, it is difficult to make the viewing range (eye box) of the image follow the viewer's viewing position, or to allow different images to be viewed from different viewing ranges. For example, in Patent Document 2, in order to make the viewing range follow the viewer's viewing position, a large-scale device that mechanically moves optical components such as mirrors is required, making it difficult to apply this to in-vehicle products.

[0005] In view of the above, an object of the present disclosure is to provide a display device that can arbitrarily move the viewpoint range of an image without using a large-scale device that mechanically moves optical components. [Means for solving the problem]

[0006] In one aspect, the following solution is provided. A light source that emits light; a spatial phase modulator arranged downstream of the light source and modulating the incident light from the light source to form an image light based on a computer-generated hologram; A control unit for controlling the spatial phase modulator, A display device that projects the image light formed by the spatial phase modulator to display a hologram image, Further comprising a microlens array disposed downstream of the spatial phase modulator and refracting the image light formed by the spatial phase modulator; the spatial phase modulator constitutes a phase hologram capable of concentrating all of the incident light from the light source into image light; The image light formed by the spatial phase modulator is formed by a plurality of pixel spots, The size of the pixel spot is set to be smaller than the size of one lens area of ​​the microlens array; The control unit selects an illumination position of the pixel spot in the lens area. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a display device capable of arbitrarily moving the viewpoint range of an image without using a complex device that mechanically moves optical components. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a side view of a vehicle equipped with a head-up display device according to an embodiment of the present invention. [Figure 1A] 1 is a schematic cross-sectional view of a head-up display device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of a display unit and a control unit. [Diagram 3] FIG. 13 is a diagram showing light use efficiency when the viewing range is large. [Figure 4] 1A and 1B are diagrams showing light utilization efficiency when the viewpoint range is small, where FIG. 1A shows the case when the viewpoint position is high, and FIG. 1B shows the case when the viewpoint position is low. [Diagram 5] 1A and 1B are diagrams showing the function of a microlens array, where (a) shows a case where the size of a pixel spot is approximately the same as the size of one lens area of ​​the microlens array, and (b) shows a case where the size of a pixel spot is smaller than the size of one lens area of ​​the microlens array. [Figure 6] 1A and 1B are diagrams showing the irradiation positions of pixel spots set in one lens area of ​​a microlens array, where (a) is a diagram showing all the irradiation positions set in a matrix, (b) is a diagram showing the state where a pixel spot is irradiated to the upper right irradiation position, and (c) is a diagram showing the state where a pixel spot is irradiated to the central irradiation position. [Figure 7] FIG. 13 is an explanatory diagram of a multiple image display mode, where (a) is a diagram showing the irradiation positions of each image light on a microlens array, and (b) is a diagram showing that different images are viewed from different viewpoint positions. [Figure 8] 1A and 1B are diagrams showing a specific example of a multiple image display mode, in which (a) shows multiple image lights being irradiated onto a microlens array, and (b) shows that different images are viewed from different viewpoint positions. [Figure 9] 1A and 1B are diagrams showing specific examples of the multiple image display mode, in which (a) shows that the navigation screen is viewed when the viewpoint position is high, and (b) shows that the meter screen is viewed when the viewpoint position is low. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. Note that in the drawings, for ease of viewing, only some of the reference symbols may be given to multiple parts having the same attribute.

[0010] [Configuration of head-up display device] Fig. 1 is a schematic diagram of a side view of a vehicle 10 equipped with a head-up display device H according to this embodiment. Fig. 1A is a schematic cross-sectional view of the head-up display device H according to this embodiment. In Fig. 1 and Fig. 1A, three orthogonal axes (X-axis, Y-axis, and Z-axis) are defined in a right-handed coordinate system. Here, the X-axis corresponds to the left-right direction (width direction) of the vehicle 10, the Z-axis corresponds to the front-rear direction of the vehicle 10, and the Y-axis corresponds to the up-down direction of the vehicle 10.

[0011] 1, the head-up display device H is disposed inside an instrument panel 7 of a vehicle 10. The head-up display device H reflects projected display light PL (image light) toward a passenger P (e.g., a driver) of the vehicle 10 by a windshield WS of the vehicle 10, thereby displaying a virtual image V (hologram image). That is, the head-up display device H is a projection-type display device that emits (projects) display light PL emitted from a display 1 (described later) onto the windshield WS (projection member) and allows the passenger P (viewer) to view the display image (virtual image) V obtained by this emission. This allows the passenger P to view the virtual image V superimposed on the scenery.

[0012] 1A, the head-up display device H accommodates a display 1, a reflecting mirror 2, a control unit 3, etc. in a case 4. The case 4 has an emission port 41 on the upper surface side of the instrument panel 7, and display light PL is emitted from inside the case 4 toward the windshield WS through the emission port 41. The emission port 41 may be covered with a transparent dust cover.

[0013] The display device 1 emits display light PL. In this embodiment, the display device 1 emits display light PL including interference fringes that constitute a computer-generated hologram, as described later. In this case, the display light PL forms an image on the retina (screen) of the passenger P, and a virtual image V is seen in front of the windshield WS. Details of the display device 1 will be described later with reference to FIG. 2 and subsequent figures.

[0014] The reflecting mirror 2 is in the form of, for example, a concave mirror, and reflects the display light PL from the display 1 while magnifying the display light PL, and directs the display light PL toward the windshield WS. That is, the reflecting mirror 2 magnifies the display light PL while folding it back.

[0015] The control unit 3 is, for example, in the form of a control circuit board, and controls the display 1. For example, the control unit 3 generates display light PL corresponding to various vehicle information at appropriate timing so that the various vehicle information is transmitted to the passenger P via the virtual image V. The type of vehicle information transmitted via the virtual image V may be arbitrary.

[0016] 1 and 1A, the head-up display device H has a reflecting mirror 2, but the reflecting mirror 2 may be omitted. In addition, other optical systems may be additionally disposed inside the case 4. For example, the display light PL may be projected onto the windshield WS via a screen.

[0017] [Display configuration] FIG. 2 is a schematic diagram showing the configuration of the display device 1 and the control unit 3. As shown in FIG.

[0018] The display 1 includes a light source 11 , a collimator unit 12 , a spatial phase modulator 13 , a half mirror 14 , a telescope optical system 15 , a zero-order light cut mask 16 , and a dichroic mirror 17 .

[0019] In this embodiment, an optical system composed of the light source 11, the collimator unit 12, the spatial phase modulator 13, the half mirror 14, the telescope optical system 15, and the zero-order light cut mask 16 is referred to as a monochromatic optical system 19. The display 1 of this embodiment includes a plurality of light sources 11R, 11G, and 11B that emit light of different wavelengths, and a monochromatic optical system 19R, 19G, and 19B is composed for each of the light sources 11R, 11G, and 11B. However, since the configurations of the monochromatic optical systems 19R, 19G, and 19B are substantially the same, the following description may only describe one of the monochromatic optical systems 19.

[0020] The light source 11 outputs light of a predetermined wavelength. For example, the light source 11 includes an LD (laser diode) that emits laser light. As described above, the display 1 of this embodiment includes a plurality of light sources 11R, 11G, and 11B that emit light of different wavelengths. The light source 11R includes, for example, a red LD that emits red laser light with a wavelength of 630 nm. The light source 11G includes, for example, a green LD that emits green laser light with a wavelength of 532 nm. The light source 11B includes, for example, a blue LD that emits blue laser light with a wavelength of 450 nm. The light source 11 is not limited to an LD. For example, a combination of an LED, a wavelength filter, a polarizing filter, and a pinhole can be replaced with an LD.

[0021] The collimating section 12 collimates the light from the light source 11 and emits the parallel light toward the spatial phase modulator 13. The collimating section 12 may cause the light from the light source 11 to enter the spatial phase modulator 13 in the form of a substantially plane wave.

[0022] The spatial phase modulator 13 is a reflective modulator (spatial light modulator) that modulates incident light and forms image light including interference fringes based on a computer-generated hologram. The spatial phase modulator 13 operates under the control of the above-mentioned control unit 3. For example, an LCOS-SLM (Liquid Crystal on Silicon-Spatial Light Modulator) is used as the spatial phase modulator 13. With such a spatial phase modulator 13, a phase-type hologram (kinoform) that can concentrate all the incident light from the light source 11 into image light can be configured. Note that the light reflected by the spatial phase modulator 13 may include not only light for transmitting vehicle information toward the passenger P, but also zero-order light that is not used for transmitting vehicle information.

[0023] The half mirror 14 is disposed between the collimator unit 12 and the spatial phase modulator 13, with a predetermined angle of inclination with respect to the optical axis. In other words, the half mirror 14 transmits the light emitted by the collimator unit 12 to make it incident on the spatial phase modulator 13, while reflecting the light emitted by the spatial phase modulator 13 to make it incident on the telescope optical system 15.

[0024] The telescope optical system 15 enlarges or reduces the real image IM by the image light of the spatial phase modulator 13. As the telescope optical system 15, a Keplerian telescope optical system or a Galilean telescope optical system can be used. As shown in FIG. 2, the telescope optical system 15 of this embodiment is a Keplerian telescope optical system, and is composed of two lenses 151 and 152 having positive focal lengths f1 and f2. The two lenses 151 and 152 are arranged at a distance equivalent to the sum of the focal lengths f1 and f2 of the lenses 151 and 152. The magnification (magnification ratio) of the telescope optical system 15 can be expressed by the following formula, where the focal length of the lens 151 on the spatial phase modulator 13 side is f1 and the focal length of the lens 152 on the real image IM side is f2. Magnification=f2 / f1

[0025] In the display 1 of this embodiment, the size of the generated real image IM is adjusted for each wavelength by using the telescope optical system 15, and the angle of view and pixel size are adjusted. This makes it possible to suppress image shifts caused by differences in wavelength without changing the resolution.

[0026] The zero-order light cut mask 16 blocks the zero-order light contained in the light emitted from the spatial phase modulator 13, and prevents the zero-order light from reaching the real image IM. In the display 1 of this embodiment, the telescope optical system 15 is a Keplerian telescope optical system, and the zero-order light cut mask 16 is disposed at or near the focal position of the Keplerian telescope optical system. That is, in the Keplerian telescope optical system, an intermediate image is generated at the focal position, so that it is easy to deal with the zero-order light, and the zero-order light can be efficiently removed. A specific example of the zero-order light cut mask 16 is, for example, a transparent slide having a black spot capable of blocking the zero-order light. The position and size of the zero-order light cut mask 16 and the black spot can be empirically adjusted so that the zero-order light is blocked well.

[0027] 2, the dichroic mirror 17 is configured by combining a plurality of mirrors with different wavelengths of transmitted light and reflected light, and combines the light (real images IM_R, IM_G, IM_B) that has passed through the telescope optical system 15 of each of the monochromatic optical systems 19R, 19G, 19B. In other words, the dichroic mirror 17 combines the real images IM_R, IM_G, IM_B of each color that are formed in front of the dichroic mirror 17. The combined real image IM is projected via a microlens array 20 (described later) that is arranged in the rear of the dichroic mirror 17, and is displayed as a virtual image V.

[0028] [Control Unit Configuration] As shown in FIG. 2, the control unit 3 includes, as hardware, a controller IC 31, a driver IC 32, and a microcomputer (not shown), and includes, as software, a CGH engine 33 that operates the controller IC 31.

[0029] The controller IC31 inputs a display image signal and a control signal from the vehicle ECU8. The display image signal includes an image signal related to navigation information and an image signal related to vehicle information. The control signal includes an image display ON / OFF signal, a brightness adjustment signal, and a user operation signal. The controller IC31 generates an image formation pattern based on the display image signal input from the vehicle ECU8 and outputs it to the spatial phase modulator 13. This image formation pattern is a CGH pattern for the spatial phase modulator 13 to form image light including interference fringes based on a computer generated hologram. The controller IC31 also performs ON / OFF control and output control (brightness control) of the light source 11 via the driver IC32.

[0030] The driver IC 32 drives the light source 11 with a predetermined power in response to a drive signal from the controller IC 31. The microcomputer communicates with the vehicle ECU 8 to control the overall operation (including turning the power on / off) of the head-up display device H. The controller IC 31 and the CGH engine 33 may not be one, but may be divided into multiple ones according to their roles (for example, according to the display color).

[0031] [Viewing range and light utilization efficiency] FIG. 3 is a diagram showing the light utilization efficiency when the viewpoint range EB is large, and FIG. 4 is a diagram showing the light utilization efficiency when the viewpoint range EB is small, where (a) is a diagram showing when the viewpoint position EP is high, and (b) is a diagram showing when the viewpoint position EP is low.

[0032] 3 and 4, when the viewpoint position EP is within the viewpoint range EB, the passenger P can view the virtual image V displayed by the head-up display device H. As shown in Fig. 3, when the viewpoint range EB is large, the light diffusion angle from the pixels forming the virtual image V needs to be widened, which results in a lot of wasted light that is not actually viewed, resulting in low light utilization efficiency.

[0033] 4, when the viewpoint range EB is small, the light diffusion angle from the pixels forming the virtual image V can be narrowed, resulting in less wasted light and higher light utilization efficiency. However, when the viewpoint range EB is made small, there is a possibility that the viewpoint position EP of the passenger P may deviate from the viewpoint range EB, so it is desirable to make the viewpoint range EB follow the viewpoint position EP of the passenger P.

[0034] Conventionally, in order to make the viewpoint range EB follow the viewpoint position EP of the passenger P, a large-scale device that mechanically moves optical components such as a mirror was required, making it difficult to apply to an in-vehicle product. Therefore, the head-up display device H of this embodiment makes it possible to arbitrarily move the viewpoint range EB by simply changing the control method (CGH pattern calculation method) in the control unit 3, without using a large-scale device that mechanically moves optical components.

[0035] [Microlens array] As shown in Fig. 2, the display 1 (head-up display device H) of this embodiment further includes a microlens array 20 that is disposed after the spatial phase modulator 13 and refracts the image light formed by the spatial phase modulator 13. The microlens array 20 has a large number of lens areas 20a (see Figs. 5 and 6), and is configured by arranging these lens areas 20a in a matrix shape or the like. Each lens area 20a is, for example, a convex lens having a square, hexagonal, or other shape when viewed from the front.

[0036] Fig. 5 is a diagram showing the function of the microlens array 20. Fig. 5(a) shows a case where the size of the pixel spot SP is approximately the same as the size of one of the lens regions 20a of the microlens array 20. Fig. 5(b) shows a case where the size of the pixel spot SP is smaller than the size of one of the lens regions 20a of the microlens array 20. Fig. 6 is a diagram showing the irradiation positions of the pixel spot SP set in one of the lens regions 20a of the microlens array 20. Fig. 6(a) shows all the irradiation positions set in a matrix, Fig. 6(b) shows a state where the pixel spot SP is irradiated to the upper right irradiation position, and Fig. 6(c) shows a state where the pixel spot SP is irradiated to the central irradiation position.

[0037] The image light formed by the spatial phase modulator 13 is composed of a plurality of pixel spots SP. Fig. 5(a) shows a case where the size of the pixel spot SP irradiated (incident) on the microlens array 20 is approximately the same as or larger than the size of one lens area 20a. In this case, the emission direction of the image light from the microlens array 20 is approximately constant regardless of the irradiation position of the pixel spot SP with respect to the lens area 20a.

[0038] 5(b) shows a case where the size of the pixel spot SP irradiated onto the microlens array 20 is smaller than the size of one lens area 20a. In this case, the emission direction of the image light from the microlens array 20 changes depending on the irradiation position of the pixel spot SP with respect to the lens area 20a. The head-up display device H of this embodiment utilizes this characteristic to control the emission direction of the image light by selecting the irradiation position of the pixel spot SP in the lens area 20a.

[0039] For example, a plurality of irradiation positions arranged in a 3 × 3 matrix are set in the lens area 20a (see FIG. 6(a)). In this case, the control unit 3 can change the emission direction of the image light to nine directions by selecting any one of the irradiation positions (see FIG. 6(b) and (c)).

[0040] With such a head-up display device H, it is possible to arbitrarily move the viewpoint range EB by simply changing the CGH pattern calculation method in the control unit 3, without using a large-scale device that mechanically moves optical components.

[0041] In addition, the spatial phase modulator 13 constitutes a phase hologram capable of concentrating all the incident light from the light source 11 into image light, so that all the light from a plurality of irradiation positions (e.g., 9) set in the lens area 20a can be concentrated into one selected irradiation position. This makes it possible to prevent the generation of wasted light and improve the light utilization efficiency.

[0042] For example, the pixel pitch of the spatial phase modulator 13 is 3.2 μm, the number of pixels is 1080, the projection distance is 100 mm, the image size is 16.7 mm, the size of the pixel spot SP is 15.4 μm, and the size (one side) of the lens area 20a of the microlens array 20 is 50 μm. In this case, the light utilization efficiency is about 13.4 times that of the conventional one, according to the following formula. Light utilization efficiency=(area of ​​lens region 20a) / (area of ​​pixel spot SP) =(50×50) / (7.7×7.7×π) ≒ 13.4

[0043] [Control mode of the control unit] The control unit 3 of this embodiment has two control modes that differ in the display form of the virtual image V. One control mode is a viewpoint tracking mode that makes the viewpoint range EB follow the viewpoint position EP of the passenger P, and the other control mode is a multiple image display mode that makes different virtual images V visible from multiple viewpoint ranges EB.

[0044] In the viewpoint tracking mode, the control unit 3 detects the viewpoint position EP of the passenger P by capturing an image of the passenger P's face using a camera (not shown) arranged on the upper part of the windshield WS and recognizing the position of the passenger's eyes in the captured image. The control unit 3 selects one irradiation position from a plurality of irradiation positions set in the lens area 20a according to the detected viewpoint position EP and irradiates the selected irradiation position with the pixel spot SP. This allows the viewpoint range EB to follow the viewpoint position EP of the passenger P.

[0045] Fig. 7 is an explanatory diagram of the multiple image display mode, where (a) shows the irradiation position of each image light on the microlens array 20, and (b) shows that different virtual images V are viewed from different viewpoint positions EP. Fig. 8 is a diagram showing a specific example of the multiple image display mode, where (a) shows multiple image lights irradiated to the microlens array 20, and (b) shows that different virtual images V are viewed from different viewpoint positions EP. Fig. 9 is a diagram showing a specific example of the multiple image display mode, where (a) shows that the virtual image V of the navigation screen is viewed when the viewpoint position EP is high, and (b) shows that the virtual image V of the meter screen is viewed when the viewpoint position EP is low.

[0046] In the case of the multiple image display mode, the control unit 3 selects multiple irradiation positions from multiple irradiation positions set in the lens area 20a, and irradiates each irradiation position with a pixel spot SP of different image light, thereby allowing different virtual images V to be viewed from multiple viewpoint ranges EB (viewpoint positions EP). For example, as shown in (a) of FIG. 7, among the nine irradiation positions set in a 3×3 array in the lens area 20a, the three irradiation positions arranged on the upper side are irradiated with a pixel spot SP(A) of the third image V3. In addition, the three irradiation positions arranged on the lower side are irradiated with a pixel spot SP(C) of the first image V1, and the three irradiation positions arranged in the vertical center are irradiated with a pixel spot SP(B) of the second image V2. In this way, as shown in (b) of FIG. 7, it becomes possible to view the first image V1 from the upper viewpoint position EP, the second image V2 from the viewpoint position EP in the vertical center, and the third image V3 from the lower viewpoint position EP.

[0047] 8, if the first image V1 is "A", the second image V2 is "I", and the third image V3 is "U", the image light of the three images "A", "I", and "U" is mixed and irradiated onto the microlens array 20. However, the image light of the three images "A", "I", and "U" is distributed in different emission directions according to the irradiation positions of the pixel spots SP in the lens area 20a, and can be viewed from different viewpoint positions EP.

[0048] According to such a multiple image display mode, it is possible to allow multiple passengers P (e.g., the driver and other passengers) to view different virtual images V, or allow one passenger P to view different virtual images V depending on the viewpoint position EP. For example, as shown in Fig. 9, a display mode can be realized in which when the viewpoint position EP of the passenger P is high, the passenger P views a virtual image V1 of the navigation screen, and when the viewpoint position EP of the passenger P is low, the passenger P views a virtual image V2 of the meter screen.

[0049] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments. [Explanation of symbols]

[0050] H Head-up display device (display device) 1 Display 2 reflector 3. Control Unit 31 Controller IC 32 Driver IC 33 CGH engine 4 Cases 41 Exit port 11(11R, 11G, 11B) Light source 12 Collimation section 13 Spatial Phase Modulator 14 Half Mirror 15 Telescope optical system 151, 152 Lenses 16 0th order light cut mask 17 Dichroic mirror 19(19R, 19G, 19B) Monochromatic optical system 20 Microlens Array 20a Lens area EB Viewpoint Range EP Viewpoint Position IM(IM_R, IM_G, IM_B) Real image P Passenger PL Display light (image light) SP pixel spot V Virtual image (hologram image) WS Windshield

Claims

1. A light source that emits light; a spatial phase modulator arranged downstream of the light source and modulating the incident light from the light source to form an image light based on a computer-generated hologram; A control unit for controlling the spatial phase modulator, A display device that projects the image light formed by the spatial phase modulator to display a hologram image, Further comprising a microlens array disposed downstream of the spatial phase modulator and refracting the image light formed by the spatial phase modulator; the spatial phase modulator constitutes a phase hologram capable of concentrating all of the incident light from the light source into image light; The image light formed by the spatial phase modulator is formed by a plurality of pixel spots, The size of the pixel spot is set to be smaller than the size of one lens area of ​​the microlens array; The control unit selects an irradiation position of the pixel spot in the lens area.

2. The display device according to claim 1 , wherein a plurality of the irradiation positions arranged in a matrix are set in the lens area.

3. The holographic image is viewable from a range of viewpoints; The display device according to claim 1 , wherein the control unit moves the viewpoint range based on a selection of the irradiation position of the pixel spot in the lens area.

4. The display device according to claim 3 , wherein the control unit causes the viewpoint range to follow a viewpoint position of a viewer.

5. The holographic image is viewable from a range of viewpoints; The display device according to claim 1 , wherein the control unit selects a plurality of the irradiation positions in the lens area and causes the pixel spots of different image light to be irradiated onto each irradiation position, thereby allowing different hologram images to be viewed from a plurality of the viewpoint ranges.

Images