Projection device

Abstract

To provide a projection device capable of improving image quality. [Solution] A projection device according to one embodiment of the present disclosure comprises an image display device, a pupil replication device that replicates the pupil conjugate point of the image light emitted from the image display device, a separation unit disposed between the image display device and the pupil replication device, which separates the image light into a plurality of optical paths and causes them to enter the pupil replication device, and a retroreflector that reflects the image light emitted from the pupil replication device in the direction of incidence.

Description

Technical Field

[0001] The present disclosure relates to a projection device used, for example, as a head-up display.

Background Art

[0002] For example, Patent Document 1 discloses an edge mount display that attempts to enlarge the eyebox by using a first light guide plate and a second light guide plate in which the respective replication directions of the image light from the image display unit form an angle of less than 90 degrees.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a head-up display in which the eyebox is enlarged by using a light guide plate, improvement in image quality is required.

[0005] [[ID=�9]]It is desirable to provide a projection device capable of improving image quality.

Means for Solving the Problems

[0006] The projection device according to an embodiment of the present disclosure includes an image display device, a pupil replication device that replicates the pupil conjugate point of the image light emitted from the image display device, a separation unit that is disposed between the image display device and the pupil replication device and separates the image light into a plurality of optical paths and causes the separated image light to enter the pupil replication device, and a retroreflective plate that reflects the image light emitted from the pupil replication device in the incident direction.

[0007] In one embodiment of the projection apparatus of this disclosure, a separation unit is placed between the image display device and a pupil replication device that replicates the pupil conjugate point of the image light emitted from the image display device. The separation unit separates the image light into multiple optical paths and directs them into the pupil replication device. This reduces the light and dark stripes within the eye box range expanded by the pupil replication device. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of a projection device according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a functional block diagram showing the configuration of the video display device shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram showing an example of the configuration of the pupil replication device shown in Figure 1. [Figure 4] Figure 4 shows the configuration of the image light incident on the pupil replicating device shown in Figure 3. [Figure 5] Figure 5 is a perspective view showing an example of the configuration of the separation unit shown in Figure 1. [Figure 6] Figure 6 is a perspective view showing an example of the arrangement of the separation unit shown in Figure 5 and the pupil replication device shown in Figure 3. [Figure 7] Figure 7 is a diagram illustrating the positional relationship between the separation unit shown in Figure 5 and the pupil replication device shown in Figure 3. [Figure 8] Figure 8 is a schematic plan view of the retroreflector shown in Figure 1. [Figure 9] Figure 9 is a schematic diagram illustrating the retroreflective elements that make up the retroreflective plate shown in Figure 8. [Figure 10] Figure 10 is a diagram illustrating the retroreflector shown in Figure 8. [Figure 11A] Figure 11A illustrates the pupil position at which a wide-angle image can be viewed. [Figure 11B] Figure 11B is a diagram illustrating the incidence of each type of light shown in Figure 11A onto the human eye. [Figure 12] Figure 12 is a schematic diagram illustrating the eyebox in a typical projection device. [Figure 13]FIG. 13 is a schematic diagram for explaining an enlargement of an eyebox in a general projection device with pupil replication. [Figure 14] FIG. 14 is a diagram for explaining the light and dark stripes confirmed in the eyebox of the projection device shown in FIG. 13. [Figure 15] FIG. 15 is a diagram for explaining an example of the configuration of the separation unit of the projection device shown in FIG. 1 and the mode of separation of image light. [Figure 16] FIG. 16 is a diagram for explaining another example of the configuration of the separation unit of the projection device shown in FIG. 1 and the mode of separation of image light. [Figure 17] FIG. 17 is a diagram for explaining the eyebox of the projection device shown in FIG. 1. [Figure 18] FIG. 18 is a diagram for explaining the relationship between the pitch of the separation element constituting the separation unit shown in FIG. 5 and the pitch of the reflecting surface of the pupil replication device shown in FIG. 3. [Figure 19] FIG. 19 is a diagram for explaining a configuration example of the separation unit according to Modification Example 1 of the present disclosure and the mode of separation of image light. [Figure 20] FIG. 20 is a diagram for explaining an example of the configuration of the separation unit according to Modification Example 2 of the present disclosure and the mode of separation of image light. [Figure 21] FIG. 21 is a diagram for explaining another example of the configuration of the separation unit according to Modification Example 2 of the present disclosure and the mode of separation of image light. [Figure 22] FIG. 22 is a diagram for explaining an example of the configuration of the separation unit according to Modification Example 3 of the present disclosure and the mode of separation of image light. [Figure 23] FIG. 23 is a diagram for explaining another example of the configuration of the separation unit according to Modification Example 3 of the present disclosure and the mode of separation of image light. [Figure 24] FIG. 24 is a diagram for explaining a configuration example of the separation unit according to Modification Example 4 of the present disclosure and the mode of separation of image light. [Figure 25] FIG. 25 is a schematic diagram showing a configuration example of the image display device according to Modification Example 5 of the present disclosure.

Mode for Carrying Out the Invention

[0009] The embodiments described below will be explained in detail with reference to the drawings. The following description is one specific example of the disclosure, and the disclosure is not limited to the following embodiments. Furthermore, the disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc., of each component shown in each drawing. The order of explanation is as follows. 1. Embodiment (Example of a projection device in which a separation unit is placed between the image display device and the pupil replication device) 2. Variations 2-1. Variation 1 (Another example of the configuration of the separation section) 2-2. Variation 2 (Another example of the configuration of the separation section) 2-3. Modification 3 (Another example of the configuration of the separation section) 2-4. Modification 4 (Another example of the configuration of the separation section) 2-5. Variation 5 (Another example of a display device configuration)

[0010] <1. Embodiment> Figure 1 shows a schematic configuration of a projection device (projection device 1) according to one embodiment of the present disclosure. The projection device 1 is used in a head-up display (HUD) system that displays speed, navigation, etc., to the driver (user 100) in the front seat of a vehicle, and displays a virtual image including driving support information and warning information using light reflection from the windshield.

[0011] The projection device 1 comprises an image display device 10, a pupil replication device 20, a separation unit 30, a retroreflector 40, and reflective mirrors 50, 60. The separation unit 30 is positioned between the image display device 10 and the pupil replication device 20, and separates the image light L emitted from the image display device 10 into multiple optical paths and directs them into the pupil replication device 20, thereby increasing the number of ejected pupils P replicated by the pupil replication device 20.

[0012] Here, the image display device 10 corresponds to a specific example of the "image display device" in one embodiment of the present disclosure. The pupil replication device 20 corresponds to a specific example of the "pupil replication device" in one embodiment of the present disclosure. The separation unit 30 corresponds to a specific example of the "separation unit" in one embodiment of the present disclosure. The retroreflector 40 corresponds to a specific example of the "retroreflector" in one embodiment of the present disclosure. The reflective mirror 50 corresponds to a specific example of the "reflective mirror" in one embodiment of the present disclosure.

[0013] [Video display device] Figure 2 is a functional block diagram showing an example of the configuration of the video display device 10. The video display device 10 projects a virtual image in front of the user 100. The video display device 10 is connected to an external image supply device, such as a computer (not shown) or various image players, via an I / F (interface), and projects a virtual image based on the image signal input to this interface.

[0014] The video display device 10 includes, for example, a light source device 11, a control unit 12, a light source drive unit 13, a light modulation device 14, an image processing unit 15, a frame memory 16, a panel drive unit 17, a projection optical system drive unit 18, and a projection optical system 19.

[0015] The light source device 11, although not shown in the diagram, includes a light source driver for driving the light sources and a current value setting unit for setting the current values ​​used when driving the light sources. The light source driver generates a current with the current value set by the current value setting unit, synchronized with the signal input from the light source drive unit 13, based on the power supply from a power supply circuit (not shown). The generated current is supplied to each light source.

[0016] The control unit 12 controls the light source drive unit 13, the image processing unit 15, the panel drive unit 17, and the projection optical system drive unit 18.

[0017] The light source drive unit 13 outputs a signal for controlling the light emission timing of the light source located in the light source device 11. This light source drive unit 13 includes, for example, a PWM setting unit, a PWM signal generation unit, and a limiter (not shown), and controls the light source driver of the light source device 11 based on the control of the control unit 12, and controls the light source with PWM to turn the light source on and off, or adjust the brightness.

[0018] The optical modulator 14 generates image light by modulating the light (illumination light) output from the light source 11 based on the image signal. The optical modulator 14 is composed of, for example, three light bulbs corresponding to each of the RGB colors described later. Examples of the optical modulator 14 include a liquid crystal display panel (panel (B)) that modulates blue light (B), a liquid crystal display panel (panel (R)) that modulates red light (R), and a liquid crystal display panel (panel (G)) that modulates green light (G). The RGB colors of light modulated by the optical modulator 14 are combined by a cross dichroic prism or the like (not shown) and guided to the projection optical system 19.

[0019] The image processing unit 15 acquires an image signal input from an external source and performs functions such as determining the image size, resolution, and whether it is a still image or a moving image. If it is a moving image, it also determines the attributes of the image data, such as the frame rate. Furthermore, if the resolution of the acquired image signal differs from the display resolution of the optical modulator 14, it performs a resolution conversion process. The image processing unit 15 then expands the processed images into the frame memory 16 frame by frame and outputs the images of each frame expanded in the frame memory 16 as a display signal to the panel drive unit 17.

[0020] The panel drive unit 17 drives the optical modulator 14. The driving of this panel drive unit 17 changes the light transmittance at each pixel in the optical modulator 14, thereby forming an image.

[0021] The projection optical system drive unit 18 includes a motor that drives the lens arranged in the projection optical system 19. This projection optical system drive unit 18 drives the projection optical system 19 according to the control of the control unit 12, and performs operations such as zoom adjustment, focus adjustment, and aperture adjustment.

[0022] The projection optical system 19 includes a group of lenses and the like for imaging the light modulated by the light modulation device 14.

[0023] In addition to the three-panel system using the three liquid crystal display panels described above, the video display device 10 may also be configured as a single-panel time-division projector using one liquid crystal display panel as the optical modulation device 14.

[0024] [Eye duplication device] Figure 3 schematically shows the planar configuration (A) and cross-sectional configurations (B) and (C) of the pupil replication device 20. The pupil replication device 20 includes, for example, an incident section 21 and a light guide plate 22. The light guide plate 22 has a light guide section 22A that reflects the image light L incident through the incident section 21 into the interior of the light guide plate 22, and a light guide section 22B that causes the image light L reflected by the light guide section 22A to be emitted to the retroreflector plate 40.

[0025] The incident section 21 corresponds to one specific example of the "incident section" as one embodiment of the present disclosure, and is a member to which the image light L emitted from the separation section 30 is incident. The incident section 21 is composed of a triangular prism such as a right-angle prism. The incident section 21 is arranged on one of a pair of opposing surfaces of the light guide section 22A (for example, surface 22AS1), as shown in Figure 3(B), for example, and one surface of the triangular prism becomes the incident surface 21S1 for the image light L emitted from the separation section 30.

[0026] The light guide section 22A corresponds to a specific example of the "first light guide section" as one embodiment of the present disclosure. The light guide section 22A is a plate-shaped member having a pair of opposing surfaces 22AS1 and 22AS2, and the incident section 21 is arranged on surface 22AS1 as described above. The light guide section 22A has a total reflection region 23 formed by a plurality of half mirrors 231 (half mirrors 231H1, ..., 231HM) arranged in the X-axis direction, each having a predetermined inclination (for example, about 45° with respect to the body axis direction (X-axis direction) of the user 100), as shown in Figures 3(A) and (B).

[0027] The light guide section 22B corresponds to a specific example of the "second light guide section" as one embodiment of the present disclosure. The light guide section 22B is a plate-shaped member having a pair of opposing surfaces 22BS1 and 22BS2. The light guide section 22B has an emission region 24 in which a plurality of half mirrors 241 (half mirrors 241V1, ..., 241VN) extending in the X-axis direction are arranged in the Y-axis direction, as shown in Figures 3(A) and (C), for example.

[0028] Multiple half mirrors 231 (half mirrors 231H1, ..., 231HM) and multiple half mirrors 241 (half mirrors 241V1, ..., 241VN) may each have their reflectivity adjusted in stages. The reflectivity of each half mirror will be explained below using the multiple half mirrors 231 that constitute the light guide section 22A as an example. For example, among the half mirrors 231H1, ..., 231HM arranged in the X-axis direction, by setting the reflectivity of the first-stage half mirror 231H1 to (M-1) / M and the reflectivity of the second-stage and subsequent half mirrors 231 to 1 / (M-m+1), the amount of light reflected by each half mirror 231H1, ..., 231HM will be equal. For example, if the amount of light incident on the light guide section 22A is Q, and M stages of half mirrors 231 are arranged, the amount of light reflected from the m-th stage half mirror 231Hm is expressed by the following formula (1).

[0029]

number

[0030] The same applies to the multiple half-mirrors 241 (half-mirrors 241V1, ..., 241VN) that constitute the light guide section 22B.

[0031] The light guide portion 22A further has a side surface 22AS3 perpendicular to a pair of opposing surfaces 22AS1 and 22AS2. The light guide portion 22B further has a side surface 22B3 perpendicular to a pair of opposing surfaces 22BS1 and 22BS2. Surface 22AS3 of the light guide portion 22A and surface 22BS3 of the light guide portion 22B are directly opposite each other. The light guide portion 22A and the light guide portion 22B are integrated by bonding surfaces 22AS3 and 22BS3 together, for example as shown in Figures 3(A) and (C). Furthermore, surface 22AS1 of the light guide portion 22A and surface 22BS1 of the light guide portion 22B form a continuous, identical surface, for example as shown in Figure 3(C). Similarly, the surface 22AS2 of the light guide portion 22A and the surface 22BS2 of the light guide portion 22B form a continuous, identical surface, as shown in Figure 3(C), for example.

[0032] Here, surface 22AS1 of the light guide section 22A corresponds to a specific example of the "first surface" in one embodiment of the present disclosure, and surface 22AS3 corresponds to a specific example of the "second surface" in one embodiment of the present disclosure. Surface 22BS3 of the light guide section 22B corresponds to a specific example of the "third surface" in one embodiment of the present disclosure, and surface 22BS2 corresponds to a specific example of the "fourth surface" in one embodiment of the present disclosure. Furthermore, the plurality of half mirrors 231 (half mirrors 231H1, ..., 231HM) that constitute the total reflection region 23 of the light guide section 22A correspond to a specific example of the "first group of half mirrors" in one embodiment of the present disclosure. The plurality of half mirrors 241 (half mirrors 241V1, ..., 241VN) that constitute the emission region 24 of the light guide section 22B correspond to a specific example of the "second group of half mirrors" in one embodiment of the present disclosure. Note that M and N are integers of 2 or more.

[0033] The image light L that enters the light guide section 22A via the incident section 21 propagates through the total reflection region 23 and is reflected in the Y-axis direction by a plurality of half mirrors 231 (half mirrors 231H1, ..., 231HM) arranged in the X-axis direction, and exits from the surface 22AS3 of the light guide section 22A. The image light L that exits from the surface 22AS3 of the light guide section 22A enters from the surface 22BS3 of the opposite light guide section 22B and is reflected in the Z-axis direction by a plurality of half mirrors 241 (half mirrors 241V1, ..., 241VN) arranged in the Y-axis direction, and exits from the surface 22BS2 of the light guide section 22B, for example, as shown in Figure 4.

[0034] If the pupil duplication device 20 has a light guide section 22A with, for example, 10 half-mirrors 231 arranged in the X-axis direction, and a light guide section 22B with, for example, 5 half-mirrors 241 arranged in the Y-axis direction, then the image light L incident on the incident section 21 is expanded (duplicated) into 10 rays in the total reflection region 23, and further expanded (duplicated) into 50 rays in the exit region 24 before being emitted. In other words, 50 pupil conjugate points are duplicated in the X-axis and Y-axis directions.

[0035] [Separation section] Figure 5 is a schematic perspective view showing an example of the configuration of the separation unit 30. The separation unit 30 has a pair of opposing surfaces 30S1 and 30S2. The separation unit 30 is composed of, for example, a plurality of separation elements (here, three separation elements 31A, 31B, and 31C).

[0036] The separation elements 31A, 31B, and 31C each have a reflective surface 31S and are arranged in parallel in a uniaxial direction (for example, the Y-axis direction). The separation elements 31A, 31B, and 31C are, for example, polarized beam splitters (PBS) that separate incident light according to its polarization component. The PBS is composed of, for example, an optically functional film (PBS film 331) that reflects or transmits incident light according to its polarization component, and two prisms bonded together with the PBS film 331 in between. The PBS film 331 forms the reflective surface 31S shown in Figure 5 and is configured to reflect the S-polarized component and transmit the P-polarized component (see, for example, Figures 16 and 17).

[0037] Figure 6 is a schematic perspective view showing an example of the arrangement of the pupil replication device 20 and the separation unit 30. Figure 7 illustrates the positional relationship between the pupil replication device 20 and the separation unit 30. The separation unit 30 is positioned in front of the pupil replication device 20. Specifically, as shown in Figures 6 and 7, the separation unit 30 is positioned so that the incident surface 21S1 of the incident section 21 of the pupil replication device 20 and the surface 30S2 face each other directly. The incident section 21 and the separation unit 30 may be positioned spaced apart, or they may be positioned so that the incident surface 21S1 and the surface 30S2 are in contact.

[0038] Furthermore, at this time, the separation elements 31A, 31B, and 31C constituting the separation unit 30 are arranged to be perpendicular to the direction of the light rays of the image light L emitted from the image display device 10 and incident on the surface 30S1, and to be arranged in parallel along the incident surface 21S1 of the incident unit 21. In other words, the reflective surfaces 31S provided on each of the multiple separation elements constituting the separation unit 30 are arranged to be parallel to each other in a direction perpendicular to the direction of the light rays of the image light L incident on the surface 30S1, and to be arranged in parallel along the incident surface 21S1 of the incident unit 21. Note that the reflective surfaces 31S provided on each of the multiple separation elements constituting the separation unit 30 have an angle of approximately 45° with respect to the direction of the light rays of the image light L incident on the surface 30S1.

[0039] [Retroreflective panel] The retroreflector 40 is an optical component that has a mechanism to return reflected light directly to the optical axis of the incident light. The retroreflector 40 has multiple retroreflecting elements 41 arranged periodically in a two-dimensional array.

[0040] Figure 8 schematically shows the planar configuration of the retroreflector 40. Figure 9 schematically shows the configuration of the multiple retroreflective elements 41 that make up the retroreflector 40. The retroreflective element 41 is, for example, made by combining three plane mirrors with their reflective surfaces facing inward and perpendicular to each other, like the vertices of a cube. Specifically, as shown in Figure 9, the retroreflective element 41 has a triangular pyramidal recess 41c on the inside of the three surfaces 41S1, 41S2, and 41S3 by combining the three surfaces 41S1, 41S2, and 41S3 so that they are orthogonal to each other. When viewed from directly above, the retroreflector 40, in which such retroreflective elements 41 are arranged in a two-dimensional array, has equilateral triangles arranged in the closest possible density, as shown in Figure 8, for example. Light that reaches any of the reflective surfaces is reflected by the three corner deflectors and returns in the direction from which it was incident (retroreflection).

[0041] Figure 10 schematically shows the cross-sectional configuration of the retroreflector 40 corresponding to the line I-I' shown in Figure 8. The retroreflector 40 has a pair of opposing surfaces 40S1 and 40S2. The light ray (incident light L0) incident on each retroreflector 41 undergoes sequential specular reflection on a reflective surface consisting of three surfaces 41S1, 41S2, and 41S3 that are arranged perpendicular to each other, as shown in Figure 10, and as a result, it eventually returns in the direction of incidence as reflected light L1.

[0042] [Reflective mirror] The reflective mirror 50 reflects the image light L emitted from the retroreflector 40 in a predetermined direction. Here, the reflective mirror 50 reflects the image light L emitted from the retroreflector 40 towards the area around the user 100's eyes, for example, by partial reflection. The reflective mirror 50 is made of, for example, the windshield of a vehicle (windshield 51, see Figure 11A).

[0043] The reflective mirror 60 reflects the image light L emitted from the pupil replicating device 20 in a predetermined direction. Here, the reflective mirror 60 reflects the image light L emitted from the pupil replicating device 20 toward the retroreflector 40. The reflective mirror 60 is composed of, for example, a vehicle mirror device (mirror device 61, see Figure 11A).

[0044] In the projection device 1 of this embodiment, the image light L emitted from the image display device 10 positioned above the user 100 via the separation unit 30 and the pupil duplication device 20 enters the retroreflector 40 positioned below the user 100 via the reflection mirror 60. The light from each image height enters the retroreflector 40 before converging as image, and after repeated specular reflection at each retroreflector element 41, it returns to the incident direction as divergent light. The divergent light emitted from the retroreflector 40 is partially reflected by the reflection mirror 50 positioned diagonally in front of the user 100 and enters the area around the user 100's eyes. As a result, a distant virtual image with a wide field of view (wide FOV) is displayed in front of the user 100.

[0045] [Example of installation in a vehicle] When the projection device 1 is mounted on a vehicle, for example, the image display device 10, the pupil replication device 20, and the separation unit 30 are arranged outside the vehicle (for example, on the roof) together with the mirror device 61. The retroreflective plate 40 is placed on the dashboard. The windshield 51 is used as the reflective mirror 50. Alternatively, the image display device 10, the pupil replication device 20, and the separation unit 30 are installed on the ceiling inside the vehicle, and the retroreflective plate 40 is placed on the dashboard. In that case, the windshield 51 also serves as the mirror device 61 (reflective mirror 60).

[0046] Figure 11A illustrates the pupil position at which a wide-angle image can be viewed, using projection device 1000A as an example. Figure 11B illustrates the incidence of each light shown in Figure 11A onto the eye of user 100. Note that projection device 1000A has the same configuration as projection device 1, except that the pupil replication device 20 and the separation unit 30 are omitted.

[0047] Consider the conjugate point of the light entering the eye of user 100. Light emitted from each image height (hereinafter referred to as image heights A, B, and C) of the optical modulator 14 is emitted from the image display device 10 via a polarizing beam splitter (PBS) 141 and multiple projection lenses 191A, 191B, as shown in Figure 11A. The light emitted from each image height A, B, and C is reflected by the mirror device 61 and propagates through space, and is returned approximately in the direction of incidence by the retroreflector 40. The light returned from the retroreflector 40 is partially reflected by the windshield 51 and heads towards the eye of user 100. At that time, as shown in Figure 11B, the light emitted from each image height A, B, and C overlaps again at the pupil position of user 100's eye, forms an image on the retina, and a virtual image is perceived. In other words, the point where the light overlaps is the only point (eyebox) from which the entire image can be seen, and if the eyebox is outside the position of the pupil of the user's eye, the image becomes invisible.

[0048] However, the position of each user's pupils changes due to vehicle vibrations during driving and individual differences such as sitting height. Therefore, an enlarged eye box is required.

[0049] Figure 12 shows a schematic configuration of projection device 1000A before the eye box is enlarged. Figure 13 shows a schematic configuration of projection device 1000B after the eye box is enlarged. Projection device 1000B has the same configuration as projection device 1, except that the separation unit 30 is omitted.

[0050] For example, in a projection device 1000B that uses a pupil replication device 20 to replicate the pupil conjugate point (exit pupil P) of the image light L emitted from the image display device 10, the replicated exit pupil P is also arranged around the user 100's eye, as shown in Figure 13. This expands the eye box.

[0051] However, if the exit pupil P of the image light L emitted from the image display device 10 is directly replicated by the pupil replication device 20, light and dark stripes will appear within the eye box range. These light and dark stripes are caused by the spacing between the light rays of the image light L replicated by the multiple half mirrors 231 (half mirrors 231H1, ..., 231HM) that constitute the light guide section 22A of the pupil replication device 20, as shown in Figure 14, for example. The image light L incident on the incident section 21 of the pupil replication device 20 is replicated by the half mirrors 231H1, ..., 231HM of the light guide section 22A and reflected toward the light guide section 22B. Each light ray of the image light L incident on the light guide section 22B is further replicated by the multiple half mirrors 241 (half mirrors 241V1, ..., 241VN) arranged in the propagation direction (for example, the Y-axis direction) and emitted from the surface 22BS2 of the light guide section 22B. The groups of light rays L that are duplicated and reflected (emitted) in each of these half mirrors 231H1, ..., 231HM and half mirrors 241V1, ..., 241VN form the bright areas B shown in Figure 14, and the areas between them where no light L is emitted form the dark areas D shown in Figure 14, thus forming stripes of light and dark within the eyebox range.

[0052] The stripes of light and dark within the eye box range can be improved by placing a separation unit 30 between the image display device 10 and the pupil replication device 20.

[0053] Figure 15 schematically shows the configuration of the separation unit 30 and the manner of separation of the image light L when the pupil diameter P1 of the exit pupil P of the image light L emitted from the image display device 10 is smaller than the separation pitch P2 of the separation unit 30 (arrangement pitch of the reflective surfaces 31S). Figure 16 schematically shows the configuration of the separation unit 30 and the manner of separation of the image light L when the pupil diameter P1 of the exit pupil P of the image light L emitted from the image display device 10 is larger than the separation pitch P2 of the separation unit 30.

[0054] As described above, the separation unit 30 is composed of a plurality of separation elements 31, each having a reflective surface 31S. The plurality of separation elements 31 are, for example, PBS, and the reflective surface 31S is, for example, an optically functional film (PBS film 331) that reflects or transmits incident light according to its polarization component. When the pupil diameter P1 of the exit pupil P of the image light L is smaller than the separation pitch P2 of the separation unit 30, the separation unit 30 is composed of two separation elements 31, as shown in Figure 15. When the pupil diameter P1 of the exit pupil P of the image light L is larger than the separation pitch P2 of the separation unit 30, the separation unit 30 is composed of three separation elements 31, as shown in Figure 16. The image light L incident on the separation unit 30 is separated into two rays, a P-polarized component and an S-polarized component, by the reflective surface 31S of each separation element 31, and emitted separately. Specifically, the P-polarized component and the S-polarized component are emitted with a separation in the Y-axis direction equal to the separation pitch P2 of the separation unit 30.

[0055] The P-polarized and S-polarized components of the image light L emitted from the separation unit 30 are incident on the light guide unit 22A via the incident unit 21, shifted in the Y-axis direction by the separation pitch P2 of the separation unit 30. As a result, the P-polarized component (Lp) of the image light L transmitted through the reflective surface 31S is emitted from the bright area B shown in Figure 14, for example, as shown in Figure 17, through replication and reflection at the half mirrors 231H1,...,231HM of the light guide unit 22A and the half mirrors 241V1,...,241VN of the light guide unit 22B, similar to the image light L shown in Figure 14. On the other hand, the S-polarized component (Ls) of the image light L reflected at the reflective surface 31S is incident on the light guide section 22A with a separation pitch P2 of the separation section 30. As a result, it is replicated at positions different from those where the P-polarized component is replicated in the half mirrors 231H1, ..., 231HM of the light guide section 22A, and reflected toward the light guide section 22B. Similar to the P-polarized component, it is replicated and reflected by the half mirrors 241V1, ..., 241VN of the light guide section 22B, and is emitted from the dark section D to fill the gaps between adjacent bright sections B in the X-axis direction shown in Figure 14, as shown in Figure 17. This reduces the light and dark stripes within the eye box range.

[0056] In this case, it is preferable that the half mirrors 231H1,...,231HM of the light guide section 22A and the half mirrors 241V1,...,241VN of the light guide section 22B have matching reflection characteristics for P-polarized and S-polarized light, respectively. This reduces the light and dark stripes within the eye box range caused by the intensity difference between the P-polarized component (Lp) and the S-polarized component (Ls).

[0057] Furthermore, it is preferable to design the separation pitch P2 of the separation unit 30 according to the inclination of the multiple half mirrors 231 constituting the light guide unit 22A with respect to the direction of the light ray L incident on the incident unit 21, and the arrangement pitch of the multiple half mirrors 231. For example, as shown in Figure 18, when the inclination of the multiple half mirrors 231 constituting the light guide unit 22A is θ° and the arrangement pitch of the multiple half mirrors 231 is P3, it is preferable to set the separation pitch P2 of the separation unit 30 to 1 / 2 × tanθ of the arrangement pitch P3 of the multiple half mirrors 231 (P2 = P3 / 2 × tanθ). As an example, when the inclination of the multiple half mirrors 231 constituting the light guide unit 22A is 45°, the separation pitch P2 of the separation unit 30 is set to 1 / 2 of the arrangement pitch P3 of the multiple half mirrors 231 (P2 = P3 / 2). This allows the separated image light L (for example, the S-polarization component Ls) at the reflective surface 31S of the separation unit 30 to be efficiently output to the dark area D between adjacent bright areas B.

[0058] [Effects / Effects] In the projection device 1 of this embodiment, a separation unit 30 is placed between the image display device 10 and the pupil replication device 20 to increase the number of ejected pupils P replicated by the pupil replication device 20. This will be explained below.

[0059] In recent years, development has been progressing on HUD (Head-Up Display) systems that display speed, navigation, and other information to the driver in the front seat of a vehicle, and use light reflection from the windshield to display virtual images including driving support information and warning information.

[0060] In a HUD system, light emitted from each image height of the display device overlaps again at the user's pupil position, forming an image on the retina, allowing the user to see the virtual image projected in front of them. In other words, the position where the light overlaps is the only point (eyebox) where the entire image can be seen, and if the eyebox moves away from the user's pupil position, the image becomes invisible. However, the pupil position of the user's (driver's) eye changes due to vehicle vibrations and individual differences such as sitting height. Therefore, an enlargement of the eyebox is required.

[0061] The eye box can be enlarged, for example, by using a light guide plate with multiple reflective surfaces. However, when observing a large-screen HUD image, as mentioned above, stripes of light and dark appear within the eye box area, resulting in a decrease in image quality.

[0062] The light and dark stripes within this eyebox range can be improved by narrowing the arrangement pitch of the multiple reflective surfaces that make up the light guide plate. However, increasing the number of reflective surfaces leads to increased processing costs.

[0063] In contrast, in this embodiment, a separation unit 30 is placed between the image display device 10 and the pupil replication device 20 to separate the light into multiple optical paths before it enters the pupil replication device 20. As a result, image light L from different optical paths enters the pupil replication device 20, and without increasing the number of half mirrors 231 that constitute the light guide unit 22A of the pupil replication device 20, it becomes possible to increase the number of exit pupils P replicated by the pupil replication device 20, for example, to fill in the dark areas within the eye box range.

[0064] As a result of the above, in the projection device 1 of this embodiment, the stripes of light and dark within the eye box range enlarged by the pupil replication device 20 are reduced, making it possible to improve image quality.

[0065] Next, modified examples 1 to 5 of this disclosure will be described. In the following, components similar to those in the above embodiments will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0066] <2. Variant> (2-1. Variation 1) Figure 19 schematically shows an example of the configuration of the separation unit (separation unit 30A) and the manner of separation of the video light L according to Modification 1 of the present disclosure.

[0067] In the separation unit 30 of the above embodiment, the separation unit 30A of this modified example may have a half-wave plate 332 placed on the surface 30S2 that becomes the light emission surface of the subsequent separation element 31. This makes it possible to unify the polarization of two light rays of image light L with different optical paths that enter the pupil replication device 20 into a P-polarization component or an S-polarization component. The half-wave plate 332 corresponds to one specific example of the "half-wave plate" in one embodiment of this disclosure.

[0068] As a result, in the projection device 1 equipped with the separation unit 30A of this modified example, only one of the polarizations, P-polarized or S-polarized, is incident on each of the half mirrors 231H1,...,231HM of the light guide unit 22A and the half mirrors 241H1,...,241HV of the light guide unit 22B, so that there is no difference in intensity between the P-polarized component (Lp) and the S-polarized component (Ls). Therefore, the stripes of light and dark within the eye box range enlarged by the pupil replication device 20 are further reduced, making it possible to further improve image quality. In addition, since it is no longer necessary to match the reflection characteristics for P-polarized and S-polarized light, the degree of freedom in film design is increased, and it is also possible to reduce film deposition costs.

[0069] (2-2. Variation 2) Figures 20 and 21 schematically represent an example of the configuration of the separation unit (separation unit 30B) and the manner of separation of the video light L according to Modification 2 of the present disclosure. Figure 20 shows the case where the pupil diameter P1 of the exit pupil P of the video light L emitted from the video display device 10 is smaller than the separation pitch P2 (arrangement pitch of the reflective surface 31S) of the separation unit 30B. Figure 21 shows the case where the pupil diameter P1 of the exit pupil P of the video light L emitted from the video display device 10 is larger than the separation pitch P2 of the separation unit 30B.

[0070] In the above embodiment, an example was shown in which the reflective surfaces 31S of the multiple separation elements 31 are composed of a PBS film 331, but the invention is not limited to this. In this modified example, the separation unit 30B is composed of half mirrors 333 for the reflective surfaces 31S of the multiple separation elements 31. The half mirror 333 corresponds to one specific example of the "half mirror" in one embodiment of this disclosure. Except for this point, the separation unit 30B has substantially the same configuration as the separation unit 30 of the above embodiment.

[0071] Thus, in the separation unit 30B of this modified example, the reflective surfaces 31S of the multiple separation elements 31 are made of half mirrors 333. As a result, the image light L containing P-polarized and S-polarized components is separated at the reflective surface 31S of each separation element 31. Therefore, in the projection device 1 equipped with the separation unit 30B of this modified example, the half mirrors 333 can be realized with a simpler film structure than the PBS film 331, thus reducing costs.

[0072] (2-3. Variation 3) Figures 22 and 23 schematically represent an example of the configuration of the separation unit (separation unit 30C) and the manner of separation of the video light L according to Modification 3 of the present disclosure. Figure 22 shows the case where the pupil diameter P1 of the exit pupil P of the video light L emitted from the video display device 10 is smaller than the separation pitch P2 (arrangement pitch of the reflective surface 31S) of the separation unit 30C. Figure 23 shows the case where the pupil diameter P1 of the exit pupil P of the video light L emitted from the video display device 10 is larger than the separation pitch P2 of the separation unit 30C.

[0073] In the above modified example 2, an example was shown in which all of the reflective surfaces 31S of the multiple separation elements 31 are made of half mirrors 333, but the invention is not limited to this. In this modified example, the separation unit 30C has the reflective surface 31S of the last stage separation element 31 made of a mirror 334. The mirror 334 corresponds to one specific example of a "total reflection mirror" in one embodiment of the present disclosure. Except for this point, the separation unit 30C has substantially the same configuration as the separation unit 30B of the above modified example 2.

[0074] Thus, in the separation unit 30C of this modified example, the reflective surface 31S of the last stage separation element 31 is made of a mirror 334. As a result, the separation unit 30C of this modified example has improved optical efficiency compared to the separation unit 30B of the modified example 2, and it is possible to reduce the light loss caused by the image light L passing through the reflective surface 31S in the separation unit 30B.

[0075] (2-4. Modification 4) Figure 24 schematically shows an example of the configuration of the separation unit (separation unit 30D) and the manner of separation of the video light L according to Modification 4 of the present disclosure.

[0076] The separation unit 30D in this modified example is constructed of a uniaxial medium. By using a uniaxial medium and appropriately aligning the direction of the incident light with the Z-axis (crystal system) or the slow-phase axis (film system, etc.), the image light L can be angularly separated into abnormal rays and ordinary rays. Furthermore, the separation unit 30D made of a uniaxial medium can separate the emission positions of each separated ray while aligning the ray angles.

[0077] As a result, the separation section 30D of this modified example has no reflective interface, making it possible to improve optical efficiency compared to the separation section 30 of the above embodiment.

[0078] (2-5. Modification 5) Figure 25 shows a schematic configuration of the video display device (video display device 10A) according to Modification 5 of this disclosure.

[0079] The projection device of this disclosure (for example, projection device 1) uses an image display device that emits light that is approximately parallel to the field of view at each angle of view. However, by using an infinite focus projection lens 19A, which is constructed by combining a number of lenses as shown in Figure 25, for example, as the projection optical system 19, the degree of parallelism of the projected light at each angle of view is improved. This makes it possible to provide a projection device that can display a more in-focus virtual image.

[0080] Furthermore, when using the infinity focus projection lens 19A, it is preferable to position the front lens reference plane S and the incident surface 21S1 of the incident section 21 as close together as possible. In other words, when using the image display device 10A in the projection device 1, it is preferable to position the front lens reference plane S and the surface 30S1 of the separation section 30 as close together as possible, and further, it is preferable to position the surface 30S2 of the separation section 30 and the incident surface 21S1 of the incident section 21 as close together as possible, for example, they may be touching each other. In addition, it is preferable that the optical axis of the lens substantially coincides with the center of the incident surface of the incident section 21, which is composed of a triangular prism.

[0081] Although embodiments and modifications 1 to 5 have been described above, this disclosure is not limited to the above embodiments, and various modifications are possible. For example, the arrangement and number of optical system components illustrated in the above embodiments are merely examples, and it is not necessary to include all components, and other components may also be included.

[0082] Furthermore, the effects described herein are merely examples and are not limited to those described; other effects may also occur.

[0083] This technology can also be configured as follows. According to this configuration, the light and dark stripes within the enlarged eyebox area by the pupil replicator are reduced. Therefore, image quality can be improved. (1) Video display device and A pupil duplication device that duplicates the pupil conjugate point of the image light emitted from the aforementioned image display device, A separation unit is positioned between the image display device and the pupil replicating device, and separates the image light into multiple optical paths for incidence on the pupil replicating device. A retroreflector that reflects the image light emitted from the pupil replicating device in the direction of incidence, A projection device equipped with a projection system. (2) When the axis of the human body is defined as the X-axis and the direction of both human eyes is defined as the Y-axis, The projection apparatus according to (1), wherein the pupil duplication apparatus duplicates the pupil conjugate point in at least one of the X-axis direction and the Y-axis direction. (3) The pupil duplication device has an incident section into which the image light enters from the separation section, a first light guide section, and a second light guide section. The first light guide unit has a first group of half mirrors including a plurality of half mirrors arranged in the X-axis direction or the Y-axis direction, and reflects the image light incident through the incident unit inward. The projection apparatus according to (2), wherein the second light guide unit has a second half-mirror group including a plurality of half-mirrors arranged in the Y-axis direction when the plurality of half-mirrors of the first half-mirror group are arranged in the X-axis direction, and a plurality of half-mirrors arranged in the X-axis direction when the plurality of half-mirrors of the first half-mirror group are arranged in the Y-axis direction, and the projection apparatus according to (2) above, which causes the image light reflected in the first light guide unit to be emitted to the retroreflector. (4) The separation section has two or more reflective surfaces, The projection apparatus according to (3), wherein when the plurality of half mirrors constituting the first half mirror group have an inclination of θ° with respect to the direction of the light rays of the image light incident through the incident part, the two or more reflective surfaces of the separation part are arranged at a pitch of 1 / 2 × tanθ of the pitch of the plurality of half mirrors. (5) The separation section has two or more reflective surfaces, The projection apparatus according to (3), wherein the plurality of half mirrors constituting the first half mirror group are inclined at 45° with respect to the direction of the light rays of the image light incident through the incident part, and the two or more reflective surfaces of the separation part are arranged at a pitch of half the pitch of the plurality of half mirrors. (6) The separation unit has two or more separation elements arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection apparatus according to any one of (1) to (5), wherein the two or more separation elements are polarizing beam splitters that separate incident light based on the polarization direction. (7) The projection apparatus according to (6), wherein the separation unit further has a half-wave plate in front of the last reflective surface among the two or more reflective surfaces. (8) The separation unit has two or more reflective surfaces arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection apparatus according to any one of (1) to (7) above, wherein the two or more reflective surfaces are made of half-mirrors. (9) The separation unit has two or more reflective surfaces arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection apparatus according to any one of (1) to (8) above, wherein, of the two or more reflective surfaces, the reflective surface located in the last stage is made of a total reflection mirror, and one or more reflective surfaces located in front of the reflective surface located in the last stage are made of half mirrors. (10) The projection apparatus according to any one of (1) to (3) above, wherein the separation section is composed of a uniaxial medium. (11) The separation unit has two or more reflective surfaces arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection apparatus according to any one of (1) to (9), wherein the exit pupil diameter of the image light emitted from the image display device is smaller than the arrangement pitch of the two or more reflective surfaces. (12) The separation unit has two or more reflective surfaces arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection device according to any one of (1) to (9), wherein the exit pupil diameter of the image light emitted from the image display device is larger than the arrangement pitch of the two or more reflective surfaces. (13) The projection apparatus according to any one of (3) to (12), wherein the incident part is a triangular prism. (14) The pupil duplication device has an incident section into which the image light enters from the separation section, a first light guide section, and a second light guide section. The first light guide unit has a first surface on which the incident unit is arranged, and a second surface perpendicular to the first surface and on which the image light incident through the incident unit is emitted. The projection apparatus according to any one of (2) to (13), wherein the second light guide portion has a third surface facing the second surface and into which the image light emitted from the second surface is incident, and a fourth surface perpendicular to the third surface and from which the image light is emitted. (15) The projection apparatus according to (14), wherein the fourth surface of the second light guide portion forms a continuous surface with the first surface of the first light guide portion or a continuous surface with the surface opposite to the first surface of the first light guide portion. (16) The projection apparatus according to any one of (1) to (15), further comprising a reflective mirror that reflects the image light reflected by the retroreflective plate. (17) The projection apparatus according to (16), wherein the reflective mirror causes the image light reflected by the retroreflective plate to be incident around the user's eyes. (18) The projection device according to (16) or (17), wherein the reflective mirror is the windshield of a vehicle. (19) The image display device is a projection device according to any one of (1) to (18) above, which emits substantially parallel image light. (20) The projection device according to any one of (1) to (19) above, wherein the image display device includes an infinite focus projection lens. [Explanation of Symbols]

[0084] 1, 1000A, 1000B... Projection device, 10... Image display device, 11... Light source device, 12... Control unit, 13... Light source drive unit, 14... Light modulation device, 15... Image processing unit, 16... Frame memory, 17... Panel drive unit, 18... Projection optical system drive unit, 19... Projection optical system, 20... Pupil duplication device, 21... Incident unit, 22... Light guide plate, 22A, 22B... Light guide unit, 23... Total reflection area, 24... Emission area, 30, 30A, 30B, 30C, 30D... Separation unit, 31, 31A, 31B, 31C... Separation element, 40... Retroreflective plate, 41... Retroreflective element, 50, 60... Reflective mirror, 51... Windshield, 61... Mirror device, 100... User.

Claims

1. Video display device and A pupil duplication device that duplicates the pupil conjugate point of the image light emitted from the aforementioned image display device, A separation unit is positioned between the image display device and the pupil replicating device, and separates the image light into multiple optical paths for incidence on the pupil replicating device. A retroreflector that reflects the image light emitted from the pupil replicating device in the direction of incidence, A projection device equipped with a projection system.

2. When the axis of the human body is defined as the X-axis and the direction of both human eyes is defined as the Y-axis, The projection apparatus according to claim 1, wherein the pupil duplication apparatus duplicates the pupil conjugate point in at least one of the X-axis direction and the Y-axis direction.

3. The pupil duplication device has an incident section into which the image light enters from the separation section, a first light guide section, and a second light guide section. The first light guide unit has a first half-mirror group including a plurality of half-mirrors arranged in the X-axis direction or the Y-axis direction, and reflects the image light incident through the incident unit inward. The projection apparatus according to claim 2, wherein the second light guide unit has a second half-mirror group including a plurality of half-mirrors arranged in the Y-axis direction when the plurality of half-mirrors of the first half-mirror group are arranged in the X-axis direction, and a plurality of half-mirrors arranged in the X-axis direction when the plurality of half-mirrors of the first half-mirror group are arranged in the Y-axis direction, and the projection apparatus according to claim 2, wherein the image light reflected in the first light guide unit is emitted to the retroreflector.

4. The separation section has two or more reflective surfaces, The projection apparatus according to claim 3, wherein when the plurality of half mirrors constituting the first half mirror group have an inclination of θ° with respect to the direction of the light rays of the image light incident through the incident part, the two or more reflective surfaces of the separation part are arranged at a pitch of 1 / 2 × tanθ of the pitch of the plurality of half mirrors.

5. The separation section has two or more reflective surfaces, The projection apparatus according to claim 3, wherein when the plurality of half mirrors constituting the first half mirror group are inclined at 45° with respect to the direction of the light rays of the image light incident through the incident part, the two or more reflective surfaces of the separation part are arranged at a pitch of half the pitch of the plurality of half mirrors.

6. The separation unit has two or more separation elements arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection apparatus according to claim 1, wherein the two or more separation elements are polarizing beam splitters that separate incident light based on its polarization direction.

7. The projection apparatus according to claim 6, wherein the separation unit further has a half-wave plate in front of the last reflective surface among the two or more reflective surfaces.

8. The separation unit has two or more reflective surfaces arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection apparatus according to claim 1, wherein the two or more reflective surfaces are composed of half-mirrors.

9. The separation unit has two or more reflective surfaces arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection apparatus according to claim 1, wherein, of the two or more reflective surfaces, the reflective surface located in the last stage is made of a total reflection mirror, and one or more reflective surfaces located in front of the reflective surface located in the last stage are made of half mirrors.

10. The projection apparatus according to claim 1, wherein the separation section is composed of a uniaxial medium.

11. The separation unit has two or more reflective surfaces arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection device according to claim 1, wherein the exit pupil diameter of the image light emitted from the image display device is smaller than the arrangement pitch of the two or more reflective surfaces.

12. The separation unit has two or more reflective surfaces arranged in parallel in a direction perpendicular to the direction of the light rays of the image light incident from the image display device, The projection device according to claim 1, wherein the exit pupil diameter of the image light emitted from the image display device is larger than the arrangement pitch of the two or more reflective surfaces.

13. The projection apparatus according to claim 3, wherein the incident part is a triangular prism.

14. The pupil duplication device has an incident section into which the image light enters from the separation section, a first light guide section, and a second light guide section. The first light guide unit has a first surface on which the incident unit is arranged, and a second surface perpendicular to the first surface on which the image light incident through the incident unit is emitted. The projection apparatus according to claim 2, wherein the second light guide portion has a third surface facing the second surface and into which the image light emitted from the second surface is incident, and a fourth surface perpendicular to the third surface and from which the image light is emitted.

15. The projection apparatus according to claim 14, wherein the fourth surface of the second light guide portion forms a continuous surface with the first surface of the first light guide portion or a continuous surface with the surface opposite to the first surface of the first light guide portion.

16. The projection apparatus according to claim 1, further comprising a reflective mirror that reflects the image light reflected by the retroreflective plate.

17. The projection apparatus according to claim 16, wherein the reflective mirror causes the image light reflected by the retroreflective plate to be incident on the area around the user's eyes.

18. The projection device according to claim 16, wherein the reflective mirror is the windshield of a vehicle.

19. The projection device according to claim 1, wherein the image display device emits substantially parallel image light.

20. The projection apparatus according to claim 1, wherein the image display device includes an infinite focus projection lens.

Images