Projection device

Abstract

A projection device according to an embodiment of the present disclosure comprises: a display device; a reflection mirror that reflects, to a prescribed direction, light which has been emitted from the display device; and a retroreflective plate that reflects, with a prescribed offset angle given to the incident direction, light which is incident thereon via the reflection mirror.

Description

projection device

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

[0002] For example, Patent Document 1 discloses an information display device that uses a reflector having a plurality of unit areas arranged two-dimensionally on its main surface, thereby alleviating restrictions on installation locations.

[0003] International Publication No. 2018 / 061444

[0004] Meanwhile, a projection device that displays driving support information to a vehicle driver is required to display a virtual image with a wide viewing angle.

[0005] It is desirable to provide a projection device capable of displaying a virtual image with a wide viewing angle.

[0006] A projection device according to one embodiment of the present disclosure includes a display device, a reflecting mirror that reflects light emitted from the display device in a predetermined direction, and a retroreflector that reflects light incident through the reflecting mirror at a predetermined offset angle relative to the incident direction.

[0007] In a projection device according to an embodiment of the present disclosure, light emitted from a display device is reflected in a desired direction using a retroreflector that reflects the light at a predetermined offset angle relative to the incident direction, thereby rendering a wide-angle virtual image without using, for example, a huge mirror optical system.

[0008] FIG. 1 is a schematic diagram illustrating an example configuration of a projection device according to an embodiment of the present disclosure. FIG. 2 is a functional block diagram illustrating the configuration of the display device illustrated in FIG. 1. FIG. 3 is a plan view schematic diagram of the special retroreflector illustrated in FIG. 1. FIG. 4 is a diagram illustrating retroreflective elements constituting the special retroreflector illustrated in FIG. 3. FIG. 5 is a cross-sectional schematic diagram illustrating an example configuration of a special retroreflector corresponding to line II' illustrated in FIG. 3. FIG. 6 is a diagram illustrating the reflection of light rays by the special retroreflector illustrated in FIG. 1. FIG. 7A is a cross-sectional schematic diagram illustrating another example configuration of a special retroreflector corresponding to line II' illustrated in FIG. 3. FIG. 7B is a cross-sectional schematic diagram illustrating another example configuration of a special retroreflector corresponding to line II' illustrated in FIG. 3. FIG. 8 is a diagram illustrating an incident light vector (A), a reflected light vector (B), and a difference vector (C). FIG. 9 is a diagram illustrating a rotation axis vector. FIG. 10 is a diagram illustrating the relationship between the tilt plane of a corner reflector, the incident light vector, and the reflected light vector. FIG. 11A is a diagram illustrating the pupil position at which a wide-angle image can be viewed. FIG. 11B is a diagram illustrating the incidence of the light rays shown in FIG. 11A on the human eye. FIG. 12 is a diagram illustrating the retroreflector position in a special retroreflector as a comparative example. FIG. 13 is a diagram illustrating the retroreflector position of light rays at each angle of view in a special retroreflector as a comparative example. FIG. 14 is a diagram illustrating the in-plane configuration of the special retroreflector shown in FIG. 1. FIG. 15A is a perspective view showing a retroreflector element positioned at position A in FIG. 14. FIG. 15B is a perspective view showing a retroreflector element positioned at position B in FIG. 14. FIG. 15C is a perspective view showing a retroreflector element positioned at position C in FIG. 14. FIG. 16 is a diagram illustrating the retroreflector position in the special retroreflector shown in FIG. 1. FIG. 17 is a diagram illustrating the retroreflector position of light rays at each angle of view in the special retroreflector shown in FIG. 1. FIG. 18 is a schematic diagram illustrating an example of the configuration of a display device in the projection device shown in FIG. 1. FIG. 19 is a schematic diagram illustrating another example of the configuration of a display device in the projection device shown in FIG. 1. Fig. 20 is a perspective view showing an example of the configuration of a pupil duplication device. Fig. 21 is a diagram explaining the principle of pupil duplication in the X-axis direction. Fig. 22 is a diagram explaining the compensation relationship between diffraction and chromatic dispersion. Fig. 23 is a diagram explaining the principle of pupil duplication in the Y-axis direction.FIG. 24 is a diagram illustrating a special retroreflector according to Modification 1 of the present disclosure. FIG. 25A is a perspective view illustrating a retroreflector arranged in region A shown in FIG. 24. FIG. 25B is a perspective view illustrating a retroreflector arranged in region B shown in FIG. 24. FIG. 25C is a perspective view illustrating a retroreflector arranged in region C shown in FIG. 24. FIG. 26 is a diagram illustrating the retroreflector position of light rays at each angle of view on the special retroreflector shown in FIG. 24. FIG. 27 is a schematic diagram illustrating a special retroreflector according to Modification 2 of the present disclosure. FIG. 28 is a schematic diagram illustrating a special retroreflector according to Modification 3 of the present disclosure. FIG. 29 is a schematic diagram illustrating an example of the configuration of a projection device according to Modification 4 of the present disclosure. FIG. 30 is a schematic diagram illustrating another example of the configuration of a projection device according to Modification 4 of the present disclosure. FIG. 31 is a schematic diagram illustrating an example of the configuration of a projection device according to Modification 5 of the present disclosure. FIG. 32 is a diagram illustrating an example of a combination of pupil duplication technology and pupil tracking technology. FIG. 33 is a schematic diagram illustrating an example of the configuration of a pupil duplication device according to Modification 6 of the present disclosure. FIG. 34 is a diagram showing the state of light incident on the pupil duplicating device shown in FIG.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description is one specific example of the present disclosure, and the present disclosure is not limited to the following aspects. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of the components shown in the drawings. The description will be given in the following order: 1. Embodiment (Example of a projection device using a special retroreflector) 2. Modifications 2-1. Modification 1 (Another example of a retroreflector) 2-2. Modification 2 (Another example of a retroreflector) 2-3. Modification 3 (Another example of a retroreflector) 2-4. Modification 4 (Another example of a projection device) 2-5. Modification 5 (Another example of a projection device) 2-6. Modification 6 (Another example of a pupil duplication device)

[0010] 1 illustrates an example of the configuration of a projection device (projection device 1) according to an embodiment of the present disclosure. The projection device 1 is used in, for example, a head-up display (HUD) system that displays speed, navigation, and the like to a driver in the front seat of a vehicle and displays virtual images including driving support information and attention-grabbing information by using light reflected on the windshield.

[0011] [Configuration of Projection Device] The projection device 1 includes a display device 10, a reflection mirror 20, and a special retroreflector 30. The special retroreflector 30 reflects light incident via the reflection mirror 20 at a predetermined offset angle relative to the incident direction.

[0012] Here, the display device 10 corresponds to a specific example of a "display device" in one embodiment of the present disclosure. The reflecting mirror 20 corresponds to a specific example of a "reflecting mirror" in one embodiment of the present disclosure. The special retroreflector 30 corresponds to a specific example of a "retroreflector" in one embodiment of the present disclosure.

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

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

[0015] Although not shown, the light source device 11 includes a light source driver that drives the light source and a current value setting unit that sets the current value when driving the light source. The light source driver generates a current having a current value set by the current value setting unit based on power supplied from a power supply circuit (not shown) in synchronization with a signal input from the light source drive unit 13. The generated current is supplied to each of the light sources.

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

[0017] The light source driving unit 13 outputs a signal for controlling the light emission timing of the light source arranged in the light source device 11. The light source driving unit 13 includes, for example, a PWM setting unit, a PWM signal generating 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 PWM controls the light source to turn the light source on and off or adjust the brightness.

[0018] The light modulation device 14 modulates the light (illumination light) output from the light source device 11 based on an image signal to generate image light. The light modulation device 14 is configured to include, for example, three light valves corresponding to the respective colors of RGB (described later). Examples of the light modulation device 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 color lights modulated by the light modulation device 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 outside and performs tasks such as determining the image size, resolution, and whether the image is a still image or a moving image. If the image is a moving image, it also determines image data attributes such as the frame rate. If the resolution of the acquired image signal differs from the display resolution of the light modulation device 14, it performs resolution conversion processing. The image processing unit 15 loads the images after each of these processes into the frame memory 16 for each frame, and outputs the image for each frame loaded in the frame memory 16 to the panel driving unit 17 as a display signal.

[0020] The panel driver 17 drives the light modulation device 14. When the panel driver 17 is driven, the light transmittance of each pixel arranged in the light modulation device 14 changes, and an image is formed.

[0021] The projection optical system driving unit 18 includes a motor that drives a lens arranged in the projection optical system 19. Under the control of the control unit 12, the projection optical system driving unit 18 drives, for example, the projection optical system 19, and performs, for example, zoom adjustment, focus adjustment, and aperture adjustment.

[0022] The projection optical system 19 includes a group of lenses for forming an image using the light modulated by the light modulation device 14 .

[0023] In addition, the display device 10 may be configured as a three-panel type projector using three liquid crystal display panels as the light modulation device 14, as well as a single-panel type time-division projector using one liquid crystal display panel.

[0024] The reflective mirror 20 reflects the light emitted from the display device 10 in a predetermined direction. Here, the reflective mirror 20 reflects the light emitted from the display device 10 toward the special retroreflector 30, and also partially reflects the light reflected by the special retroreflector 30 toward the area around the eyes of the observer 100.

[0025] FIG. 3 is a schematic diagram showing the planar structure of the special retroreflector 30. As shown in FIG.

[0026] First, a typical retroreflector will be described. A typical retroreflector has a mechanism in which reflected light returns directly to the optical axis of the incident light. A retroreflector has multiple retroreflecting elements arranged periodically in a two-dimensional array. A retroreflecting element is generally, for example, three plane mirrors arranged at right angles to each other with their reflective surfaces facing inward, like the vertices of a cube, forming a triangular pyramidal recess. When viewed from directly above, a retroreflector with such retroreflecting elements arranged in a two-dimensional array has a close-packed arrangement of equilateral triangles, as shown in Figure 3, for example. Light that reaches any of the reflective surfaces is reflected by the three corner reflectors and returns to the direction of incidence (retroreflected).

[0027] The special retroreflective plate 30 of this embodiment, like the general retroreflective plate described above, is composed of multiple retroreflective elements 31, each consisting of three reflective surfaces, arranged in a repeated cycle. However, the special retroreflective plate 30 differs from general retroreflective plates in that one of the three surfaces constituting the retroreflective element 31 is tilted by an angle θ from a right angle (90°) with the adjacent surface. Specifically, as shown in FIG. 4, for example, if the three mutually orthogonal surfaces are surface A S1, surface B S2, and surface C S3, respectively, the retroreflective element 31 consists of three surfaces: surface A S1 and surface B S2, which are mutually orthogonal, and surface C' S3', which is tilted inward from surface C S3 by an angle θ toward the inside of the triangular pyramidal recess. The angle θ may be greater or less than 0°. In other words, surface C' S3' may be tilted outward from the triangular pyramidal recess.

[0028] FIG. 5 is a schematic representation of an example of the cross-sectional configuration of the special retroreflective plate 30 corresponding to the line II' shown in FIG. 3. The special retroreflective plate 30 has a pair of opposing surfaces 30S1 and 30S2, and on the surface 30S1 side, multiple triangular pyramidal recesses of each of the multiple retroreflective elements 31 constituting the special retroreflective plate 30 are closely packed. As described above, one of the three surfaces (surface A S1, surface B S2, and surface C' S3') constituting the retroreflective element 31 is a tilted surface inclined by an angle θ from a right angle (90°) with the adjacent surface. The tilted surfaces (surface C' S3') of the multiple retroreflective elements 31 are adjacent to each other in the YZ plane, for example, in the Z-axis direction, which is the direction of travel of the vehicle 40, as shown in FIGS. 3 and 5.

[0029] FIG. 6 is a schematic diagram showing the reflection of light rays incident on the special retroreflective plate 30. Four light rays emitted in the Z-axis direction from the irradiation position X at different angles are incident on different positions on the special retroreflective plate 30 (for example, four retroreflective elements 31 aligned in the Z-axis direction), as shown in FIG. 6. The light rays incident on the four retroreflective elements 31 aligned in the Z-axis direction are each given a predetermined offset angle with respect to the incident direction and are reflected in a direction different from the incident direction. For example, in the case of adjacent retroreflective elements 31 in the Z-axis direction, the polarity of the tilt angles of the adjacent tilt surfaces (C' surfaces S3') is different, being positive (+) and negative (-), but with regard to the returning position, the returning light from each retroreflective element 31 returns to the same focusing point (return position X').

[0030] 7A and 7B are schematic representations of other examples of the cross-sectional configuration of the special retroreflector 30 corresponding to the line II' shown in FIG. 3. In the cross-sectional view shown in FIG. 5, adjacent tilted surfaces (C' surfaces S3') in the Z-axis direction form a plane between them due to the tilt. If light is incident on the plane between these adjacent tilted surfaces (C' surfaces S3') in the Z-axis direction, the incident light will be reflected in an unintended direction. Therefore, adjacent tilted surfaces (C' surfaces S3') may be extended toward the incident surface 30S1, or the amount of recession toward the surface 30S2 opposite the incident surface may be increased so that they are adjacent to each other. If adjacent tilted surfaces (C' surfaces S3') are extended toward the surface 30S1, the adjacent tilted surfaces (C' surfaces S3') will protrude from the surface 30S1, as shown in FIG. 7A. When the amount of digging is increased so that adjacent tilt surfaces (C' surfaces S3') are adjacent to each other, a new surface 30S2' is formed at a position deeper than surface 30S2, as shown in Figure 7B, but a flat incident surface (surface 30S2) is obtained.

[0031] The tilt plane (C' plane) constituting the retroreflective element 31 is defined as follows, for example, using a ray vector.

[0032] Of the three surfaces (surface A S1, surface B S2, and surface C') that make up the retroreflective element 31, when two surfaces (surface A and surface B) meet at right angles and the remaining surface (surface C') has a tilt angle that is inclined by an angle θ from a right angle (90°) formed between it and the other surfaces, θ satisfies the following mathematical formula (1).

[0033]

[0034] At this time, k ｐｒｏ． and k' ＴＧＴ ｐｒｏ． is defined by the following formulas (2) and (3) from the component perpendicular to the rotation axis m of the plane (plane C') that gives the tilt. ＴＧＴ represents the subtraction of a vector whose component is parallel to the rotation axis m from k' ＴＧＴ ｐｒｏ． is perpendicular to the axis of rotation m. The incident light vector -k is also subtracted from the vector of the component parallel to the axis of rotation m, -kｐｒｏ． is perpendicular to the rotation axis m (see (A) to (C) of FIG. 8).

[0035] (m: rotation axis vector of tilt plane, k: incident light vector, k' ＴＧＴ : reflected light vector)

[0036] Here, k is the vector of the incident light direction from the light source to the corner reflector, and k' ＴＧＴ is the vector of the reflected light direction toward the human eye after offset retroreflection by the corner reflector, m is the rotation axis of the tilt plane (plane C'), and n is the normal vector of the plane (plane C) before tilting the tilt plane. ｃ and a unit vector orthogonal to the difference vector Δk (see FIGS. 9 and 10), k, k′ ＴＧＴ , Δk, m are defined by the following equation (4).

[0037] (n ｃ : normal vector of tilt plane, Δk: reflected light vector (-k) and k' when retroreflected by a corner reflector ＴＧＴ (Difference from

[0038] Here, n in formula (4) ｃ and Δk are defined by the following equation (5).

[0039]

[0040] According to the relationships defined by the above formulas (1) to (5), the retroreflective element 31 having a tilted surface (C' surface) obtained by rotating the pre-tilt surface (C surface) by θ around the rotation axis m reflects incident light represented by vector k as vector k' ＴＧＴ It has the effect of reflecting light in the direction of

[0041] In the projection device 1 of this embodiment, light emitted from a display device 10 positioned above an observer 100 is reflected by a reflecting mirror 20 positioned diagonally in front of the observer 100 toward a special retroreflector 30 positioned below the observer 100. Before forming an image as converging light, light from each image height enters the special retroreflector 30, and as a result of repeated specular reflection by each retroreflecting element 31, a predetermined offset angle is imparted to the light, causing it to be reflected as divergent light in a direction different from the incident direction. The divergent light emitted from the special retroreflector 30 is partially reflected by the reflecting mirror 20 and enters the vicinity of the observer 100's eyes. This displays a distant virtual image with a wide field of view (FOV) in front of the observer 100.

[0042] [Example of Installation in a Vehicle] In the projection device 1, for example, the display device 10 is installed on the ceiling inside the vehicle, the special retroreflector 30 is placed on the dashboard 42, and the windshield 41 also serves as the reflecting mirror 20 (see, for example, FIG. 11A).

[0043] FIG. 11A illustrates the pupil position at which a wide-angle image can be viewed. FIG. 11B illustrates the incidence of each light shown in FIG. 11A on the eye of the observer 100. Consider the conjugate points of the light entering the eye of the observer 100. Light emitted from each image height A, B, and C of the light modulation device 14 is emitted from the display device 10 via a polarizing beam splitter (PBS) 141 and multiple projection lenses 191A and 191B, as shown in FIG. 11A. The light emitted from each image height A, B, and C is reflected by the windshield 41, propagates through space, and is reflected by the special retroreflector 30 at a predetermined offset angle in a direction different from the incident direction. The light reflected from the special retroreflector 30 (return light) is partially reflected by the windshield 41 and heads toward the eye of the observer 100. 11B, the light beams emitted from image heights A, B, and C overlap again at the pupil position of the eye of observer 100, forming an image on the retina and causing the observer 100 to view a virtual image. In other words, the position where the light beams overlap is the only point (eye box) from which the entire image can be viewed, and if the eye box is not located at the pupil position of the eye of observer 100, the image cannot be viewed.

[0044] 12 illustrates the retroreflector position of a light beam on a special retroreflector 300 consisting of multiple retroreflector elements 31 with uniform tilt surfaces. When the irradiation position X and the incident positions A, B, and C of light irradiated onto the special retroreflector 300 from the irradiation position X are defined in a three-dimensional orthogonal coordinate system, the angle between the incident light beam and the tilt surface at the incident position C, which has a different Y coordinate from the irradiation position X, is shifted from the angle between the incident light beam and the tilt surface at the incident positions A and B, which have the same Y coordinate as the irradiation position X. This shift appears as a shift in the retroreflector position X'.

[0045] 13 illustrates the retroreflector position of light rays at each angle of view on a special retroreflector 300 consisting of multiple retroreflector elements 31 with uniform tilt surfaces. In order to allow the observer 100 to view a wide-angle virtual image, a retroreflector that extends in the direction of vehicle travel and laterally is placed in front of the observer 100. When the special retroreflector 300 is used in front of the observer 100, the eyebox positions of the light rays emitted from the display device 10 and incident on positions A, B, and C on the special retroreflector 300 vary as shown in FIG. 13, so there is no optimal point at which the entire image can be viewed, and only a portion of the entire image can be viewed.

[0046] Figure 14 explains the in-plane configuration of the special retroreflective plate 30 of this embodiment, and Figures 15A, 15B, and 15C show the retroreflective elements 31A, 31B, and 31C arranged at positions A, B, and C shown in Figure 14. In the special retroreflective plate 30, the angles formed by the mutually orthogonal A-surface S1 and B-surface S2 of the multiple retroreflective elements 31 arranged in the plane and the tilt surface (C'-surface S3') change continuously from the left end to the right end of the special retroreflective plate 30 shown in Figure 14, for example.

[0047] For example, in the retroreflective element 31B positioned at position B, approximately in the center of the longitudinal direction of the special retroreflective plate 30, as shown in FIG. 15B, the C' surface S3' forms a tilted surface inclined by an angle θ approximately parallel to the C surface. The retroreflective elements 31A and 31C positioned at positions A and C, which are approximately symmetrical on both sides of position B, have symmetrical shapes. Specifically, in the retroreflective element 31A positioned at position A, as shown in FIG. 15A, the C' surface S3' shown in FIG. 15B forms a tilted surface rotated clockwise by a predetermined angle. In the retroreflective element 31C positioned at position C, as shown in FIG. 15C, the C' surface S3' shown in FIG. 15B forms a tilted surface rotated counterclockwise by a predetermined angle. In this way, in a special retroreflector 30 in which the angles between the A surface S1 and the B surface S2 and the tilt surface (the C' surface S3') are optimized according to the position within the surface, for example, the angle between the light beam incident at incident position C, which has a Y coordinate different from that of the irradiation position X, and the tilt surface is the same as the angle between the light beam incident at incident positions A and B, which have the same Y coordinate as that of the irradiation position X, and the tilt surface, and the light is concentrated at a single point as shown in Figure 16. In other words, as shown in Figure 17, the eyebox positions of the light beams emitted from the display device 10 and incident at positions A, B, and C on the special retroreflector 30 overlap, so that the optimal point at which the entire image can be viewed is determined to be a single point.

[0048] As described above, the light emitted from each of the image heights A, B, and C of the light modulation device 14 overlaps again at the pupil position of the eye of the observer 100, forming an image on the retina and allowing the observer 100 to view a virtual image. However, the pupil position of the eye of the observer 100 changes due to vehicle vibrations while driving and individual differences such as sitting height. Therefore, it is necessary to expand the point where the light overlaps (the eye box) so that the entire image can be viewed.

[0049] The enlargement of the eyebox can be achieved, for example, as follows.

[0050] FIG. 18 shows an example of a display device configuration (display device 10A) that accommodates expansion of the eyebox in the body axis direction (X-axis direction) of the observer 100. The display device 10A uses, for example, a reflective liquid crystal on silicon (LCOS) or digital lighting processing (DLP) intensity modulation panel 14A to project illumination light (light L) carrying video information. The display device 10A includes, for example, the intensity modulation panel 14A, a PBS 141, a projection lens 192 consisting of multiple lenses with pupils at the exit, and a light guide plate 51 extending in the X-axis direction. A semiconductor laser (laser diode: LD) or a light-emitting diode (light-emitting diode: LED) can be used as the light source. Alternatively, an excitation light source such as a phosphor can be used.

[0051] Light guide plate 51 is, for example, a so-called holographic light guide plate having a light reflecting film 52 on one of a pair of opposing surfaces and holographic optical elements (HOEs) 53A and 53B on the other, and is placed at pupil position X of projection lens 192. HOE 53A is used to propagate incident light into light guide plate 51, and is placed at pupil position X. HOE 53B is used to extract light from light guide plate 51, and is placed at one or more locations after propagation. As a result, multiple pupils X1, X2, and X3 are replicated in the X-axis direction.

[0052] 19 shows another example of the configuration of a display device (display device 10B) that corresponds to the expansion of the eyebox in the body axis direction (X-axis direction) of the observer 100. The display device 10B irradiates, for example, a phase modulation panel 14B with illumination light carrying video information. The display device 10B has, for example, a phase modulation panel 14B, a relay lens 193 consisting of a plurality of lenses, and a light guide plate 51 extending in the X-axis direction. Since the display device 10B uses diffraction of phase modulation, it is preferable to use an LD as the light source. In the display device 10B, first-order diffracted light L whose phase information has been modulated in the phase modulation panel 14B is １ is used. The zero-order reflected light L ０ is removed as unnecessary light as a black wall 142.

[0053] In the display device 10B, the pupil position X is on the surface of the phase modulation panel 14B. １ The first-order diffracted light L incident on the light guide plate 51 is relayed to the pupil conjugate image. １ As in the display device 10A, the light is propagated into the light guide plate 51 by the HOE 53A arranged at the pupil conjugate position Xc, and is extracted from the HOEs 53B arranged at one or more locations after propagation. This results in multiple copies of pupils X1, X2, and X3 being generated in the X-axis direction.

[0054] 20 shows an example of the configuration of a pupil duplicating device that expands the eyebox in the body axis direction (X-axis direction) and in the direction of both eyes (Y-axis direction) of the observer 100. The expansion of the eyebox in the body axis direction (X-axis direction) and in the direction of both eyes (Y-axis direction) of the observer 100 can be achieved by combining a light guide plate 51 that extends in the X-axis direction with a transmittance adjustment prism 54 that is disposed on the HOE 53B and extends in the Y-axis direction.

[0055] Fig. 21 shows the principle of pupil duplication in the X-axis direction by the light guide plate 51. Fig. 22 shows the compensation relationship between diffraction and wavelength dispersion. The wavelength dispersion of light L incident on the light guide plate 51 is compensated for by the in and out HOEs 53A and 53B.

[0056] 23 illustrates the principle of pupil duplication in the Y-axis direction using the transmittance adjusting prism 54. The transmittance adjusting prism 54 is composed of multiple prisms with adjusted transmittances arranged in a single axis direction, such as seven prisms 541, 542, 543, 544, 545, 546, and 547 arranged in a single axis direction. In the transmittance adjusting prism, the n prisms arranged in a single axis direction have their transmittances adjusted in stages. By setting the reflectance of the prism arranged in the first stage to (N-1) / N and the reflectance of the prisms in the second stage and beyond to 1 / (N-n+1), the amount of light emitted from each surface is equal. For example, when the amount of light incident on the transmittance adjusting prism is P and the number of prisms is N, the amount of light emitted from the nth prism surface is expressed by the following equation (6):

[0057]

[0058] By setting these to appropriate values, it is possible to equalize the amount of light emitted from each of the prisms 541, 542, 543, 544, 545, 546, and 547. As a result, an image with a constant intensity can be viewed anywhere in the eyebox.

[0059] [Functions and Effects] In the projection device 1 of this embodiment, the light emitted from the display device 10 is reflected in a desired direction using a special retroreflector 30 that provides a predetermined offset angle with respect to the incident direction. This allows a wide-angle virtual image to be displayed without using, for example, a huge mirror optical system. This will be explained below.

[0060] In recent years, development has been progressing on HUD systems that display speed, navigation, etc. to the driver in the front seat of a vehicle and display virtual images including driving support information and cautionary information using light reflection on the windshield.

[0061] Generally, due to the size constraints of display devices, existing HUDs are limited to displaying only an area with a viewing angle of about 10 degrees (the central area in front). Meanwhile, in the world of computer graphics (CG), there are many examples of warning information and augmented reality (AR) information superimposed over the entire windshield. However, in reality, no device that can achieve this yet exists, and none has been installed in an actual vehicle.

[0062] For example, when a display device is placed in the dashboard area, a method called Pepper's Ghost is used to create a virtual image that appears floating over a wide area. With this method, the virtual image is only visible from the distance between the display device and the windshield, so it is not possible to display a virtual image from a distance. Therefore, conventional technology does not have a technology that can display a virtual image over a wide FOV and at a distance, and there was no technology that could realize the ideal CG world.

[0063] In contrast, in this embodiment, light emitted from the display device 10 and incident via the reflecting mirror 20 is reflected in a desired direction using a special retroreflector 30, which reflects the light at a predetermined offset angle relative to the incident direction. Light from each image height enters the special retroreflector 30 before being formed as converging light, and is reflected as diverging light in a direction different from the incident direction. The diverging light emitted from the special retroreflector 30 is partially reflected by the reflecting mirror 20 and enters the area around the eyes of the observer 100. This creates a wide FOV virtual image in front of the observer 100.

[0064] As a result, it is possible to provide a projection device 1 that can display a wide FOV virtual image.

[0065] In this embodiment, the special retroreflector 30 is configured such that the angle between the mutually orthogonal A-surface S1 and B-surface S2 of the multiple retroreflecting elements 31 arranged in the plane and the tilt surface (C'-surface S3') changes continuously, for example, in a direction orthogonal to the traveling direction of the vehicle 40. This allows the light of the entire field of view emitted from the display device 10 to be focused around the eyes of the observer 100. This makes it possible to view the entire wide FOV virtual image.

[0066] Next, modified examples 1 to 6 of the present disclosure will be described. In the following, the same components as those in the above embodiment will be given the same reference numerals, and the description thereof will be omitted as appropriate.

[0067] <2. Modified Examples> (2-1. Modified Example 1) Figure 24 explains the in-plane configuration of the special retroreflective plate (special retroreflective plate 30A) relating to modified example 1 of the present disclosure, and Figures 25A, 25B, and 25C show the retroreflective elements 31D, 31E, and 31F arranged in each of the regions D, E, and F shown in Figure 24.

[0068] In the above embodiment, an example is shown in which the angle between the mutually perpendicular A-surface S1 and B-surface S2 of multiple retroreflective elements 31 arranged in a plane and the tilt surface (C'-surface S3') changes continuously, for example, in a direction perpendicular to the vehicle's direction of travel, but this is not limited to this.

[0069] The special retroreflective plate 30A of this modified example has its surface divided into, for example, three regions (regions D, E, and F) from the left end to the right end of the special retroreflective plate 30 shown in Figure 24, and the angle between the mutually perpendicular A-surface S1 and B-surface S2 of the retroreflective element 31 and the tilt surface (C'-surface S3') is changed for each region.

[0070] For example, the plurality of retroreflective elements 31E arranged in region E, approximately in the center of the longitudinal direction of the special retroreflective plate 30, form a tilted surface in which the C' surface S3' is inclined by an angle θ approximately parallel to the C surface, as shown in Figure 25B. The plurality of retroreflective elements 31D and 31F arranged in regions D and F on the left and right sides of region E have a bilaterally symmetrical configuration. Specifically, as shown in Figure 25A, the retroreflective element 31D arranged in region D forms a tilted surface in which the C' surface S3' shown in Figure 25B is rotated clockwise by a predetermined angle. The retroreflective element 31F arranged in region F forms a tilted surface in which the C' surface S3' shown in Figure 25B is rotated counterclockwise by a predetermined angle, as shown in Figure 25C.

[0071] In this way, in the special retroreflector 30A of this modified example, the surface is divided into multiple regions, for example, in a direction perpendicular to the direction of travel of the vehicle, and the angle between the mutually perpendicular A-surface S1 and B-surface S2 of the retroreflector 31 and the tilt surface (C'-surface S3') is changed for each region. As a result, although the eye boxes of each light beam emitted from the display device 10 and incident on each position A, B, and C of the special retroreflector 30A are shifted on a region-by-region basis as shown in Figure 26, there are some overlapping regions, so by positioning the eyes of the observer 100 in the overlapping regions, it is possible to view the entire wide FOV virtual image.

[0072] (2-2. Modification 2) FIG. 27 shows a schematic configuration of a special retroreflector (special retroreflector 30B) according to modification 2 of the present disclosure.

[0073] In the above embodiment, the angle between the mutually orthogonal A-side S1 and B-side S2 of the multiple retroreflective elements 31 arranged in a plane and the tilt plane (C'-side S3') changes continuously, for example, in a direction perpendicular to the vehicle's traveling direction, but this is not limited to this. The special retroreflective plate 30B of this modified example is a special retroreflective plate made up of multiple retroreflective elements with uniform tilt planes, and differs from the special retroreflective plate 30 of the above embodiment in that it is curved in the YZ plane direction.

[0074] The special retroreflector 30B is formed, for example, by bending both ends of the special retroreflector 300, which is made up of multiple retroreflector elements with the same uniform tilt surface as described above, in the direction perpendicular to the vehicle's traveling direction (for example, the Y-axis direction shown in Figure 27), toward the observer in the Z-axis direction. As a result, the tilt surfaces (C' surfaces S3') of the retroreflector elements arranged on both ends in the direction perpendicular to the vehicle's traveling direction are rotated to approximately the center of the longitudinal direction of the special retroreflector 30B, as in the special retroreflector 30 of the above embodiment.

[0075] In this way, the special retroreflector 30B of this modified example is made up of multiple retroreflector elements with uniform tilt surfaces, and both ends of the special retroreflector perpendicular to the direction of travel of the vehicle are curved in the Z-axis direction, which is the observer's side. Even with this configuration, the same effects as those of the above embodiment can be obtained.

[0076] (2-3. Modification 3) FIG. 28 shows a schematic configuration of a special retroreflector (special retroreflector 30C) according to modification 3 of the present disclosure.

[0077] In the above embodiment, the angle between the mutually orthogonal A-side S1 and B-side S2 of the multiple retroreflective elements 31 arranged in a plane and the tilt plane (C'-side S3') changes continuously, for example, in a direction perpendicular to the vehicle's traveling direction, but this is not limited to this. The special retroreflective plate 30C of this modified example is a special retroreflective plate made up of multiple retroreflective elements with uniform tilt planes, and differs from the special retroreflective plate 30 of the above embodiment in that it has a warp in the X-axis direction.

[0078] The special retroreflective plate 30C is formed, for example, by bending both ends of the special retroreflective plate 300, which is made up of multiple retroreflective elements with the same uniform tilt surface as described above, in a direction perpendicular to the vehicle's traveling direction (for example, the Y-axis direction shown in Figure 28), toward the vehicle ceiling or tire direction (for example, the X-axis direction shown in Figure 28). As a result, the tilt surfaces (C' surfaces S3') of the retroreflective elements arranged on both ends in a direction perpendicular to the vehicle's traveling direction are rotated to approximately the center of the longitudinal direction of the special retroreflective plate 30C, as in the special retroreflective plate 30 of the above embodiment.

[0079] In this way, the special retroreflective plate 30C of this modified example is made up of multiple retroreflective elements with uniform tilt surfaces, and both ends of the special retroreflective plate perpendicular to the direction of travel of the vehicle are curved toward the roof or tires of the vehicle. Even with this configuration, the same effects as those of the above embodiment can be obtained.

[0080] (2-4. Modification 4) FIG. 29 shows an example of the configuration of a projection device (projection device 1A) according to Modification 4 of the present disclosure.

[0081] In the above embodiment, an example was shown in which pupil duplication was used as a method for enlarging the eyebox in the body axis direction (X-axis direction) of the observer 100. In contrast, the projection device 1A of this modified example shifts the mirror device 21 in the traveling direction of the vehicle (Z-axis direction) to make the eyebox follow the body axis direction (X-axis direction) of the observer 100.

[0082] Like the projection device 1 of the above embodiment, the projection device 1A includes a display device 10 installed on the ceiling of the vehicle, a windshield 41, and a special retroreflector 30 arranged on a dashboard 42. The projection device 1A further includes a detection camera 55 that detects the position of the eyes of the observer 100, and a rotation motor 56 that shifts the mirror device 21 in the traveling direction (Z-axis direction).

[0083] Here, the detection camera 55 corresponds to a specific example of a "pupil position detection camera" in an embodiment of the present disclosure, and the rotation motor 56 corresponds to a specific example of a "first drive unit" in an embodiment of the present disclosure.

[0084] In the projection device 1A, the detection camera 55 obtains information about the eye position (height) of the observer 100, calculates the amount by which the eyebox should be shifted in the X-axis direction, and then tracks the eyebox according to the pupil tracking output. For example, as shown in Figure 29, when the mirror device 21 is moved back and forth in the direction of travel of the vehicle (Z-axis direction), the incident position of the light emitted from the display device 10 onto the special retroreflector 30 and the incident position of the returned light emitted from the special retroreflector 30 onto the windshield 41 shift accordingly in the direction of travel of the vehicle (Z-axis direction). This causes the eyebox to track the body axis direction (X-axis direction) of the observer 100.

[0085] 30, the projection device 1A may be configured to move the position of the special retroreflector 30A in the direction of the body axis (X-axis) of the observer 100 instead of moving the mirror device 21 in the traveling direction (Z-axis direction). This method also allows the eyebox to follow the movement.

[0086] In this modified example, the mirror device 21 is moved in the direction of travel of the vehicle (Z-axis direction) and the position of the special retroreflector 30A is moved in the direction of the body axis (X-axis direction) to allow the eyebox to follow the direction of the observer's 100 body axis (X-axis direction). This configuration also allows for substantial enlargement of the eyebox, similar to the above-described embodiment. This makes it possible to accommodate changes in the pupil position of the observer's 100 due to individual differences in vehicle vibrations during driving, seated height, etc.

[0087] (2-5. Modification 5) FIG. 31 illustrates an example of the configuration of a projection device (projection device 1B) according to Modification 5 of the present disclosure.

[0088] In the above embodiment, an example was shown in which pupil duplication was used as a method for enlarging the eyebox in the direction of both eyes (Y-axis direction) of the observer 100. In contrast, in the projection device 1B of this modified example, the display device 10 is shifted in the direction of both eyes of the observer 100 (Y-axis direction) to make the eyebox follow the direction of both eyes of the observer 100 (Y-axis direction).

[0089] Like the projection device 1 of the above embodiment, the projection device 1B includes a display device 10 installed on the ceiling of the vehicle, a windshield 41, and a special retroreflector 30 arranged on a dashboard 42. The projection device 1B further includes a detection camera 55 that detects the position of the eyes of the observer 100, and a rotary motor 57 that shifts the display device 10 toward the eyes of the observer 100 (in the Y-axis direction).

[0090] Here, the detection camera 55 corresponds to a specific example of a "pupil position detection camera" in an embodiment of the present disclosure. The rotation motor 57 corresponds to a specific example of a "second drive unit" in an embodiment of the present disclosure.

[0091] In this way, in this modification, the display device 10 is moved toward the eyes of the observer 100 (in the Y-axis direction), thereby causing the eyebox to follow the eyes of the observer 100 (in the Y-axis direction). With this configuration, similar to the above embodiment, the eyebox can be substantially enlarged. Therefore, it is possible to accommodate changes in the pupil position of the observer's 100 due to individual differences such as vehicle vibrations while driving and seated height.

[0092] In addition, the projection device 1B of this modification can be combined with modification 4 to further cause the eyebox to follow the body axis direction (X axis direction) of the observer 100 by, for example, moving the mirror device 21 in the traveling direction of the vehicle (Z axis direction). Furthermore, as shown in FIG. 32 , the projection device 1B of this modification may be configured to duplicate the pupil in the Y axis direction using a light guide plate 51 extending in the direction of both eyes (Y axis direction). This expands the eyebox in the direction of the body axis (X axis direction) and the direction of both eyes (Y axis direction) of the observer 100, thereby realizing a compact projection device that can be installed inside a vehicle.

[0093] (2-6. Modification 6) Fig. 33 shows an example of the configuration of a pupil duplicating device (pupil duplicating device 60) according to Modification 6 of the present disclosure. Expansion of the eyebox in the body axis direction (X-axis direction) and in the direction of both eyes (Y-axis direction) of the observer 100 can also be achieved by using the pupil duplicating device 60 shown in Fig. 33 in addition to the pupil duplicating device shown in Fig. 20 .

[0094] 33 is a schematic diagram showing the planar and cross-sectional configurations of the pupil duplication device 60. The pupil duplication device 60 is a light guide plate having a pair of opposing surfaces 61S1 and 61S2. The light guide plate 61 has, for example, a total reflection region 62 in which a plurality of prisms 621 having reflective surfaces tilted in a predetermined direction (e.g., reflective surfaces tilted at approximately 45° with respect to the body axis direction (X-axis direction) of the observer 100) are arranged in the X-axis direction, and an exit region 63 in which a plurality of prisms 631 extending in the X-axis direction are arranged in the Y-axis direction. An incident portion 64 is provided on a surface 61S2 of the light guide plate 61 opposite to the surface 61S1, which serves as the light exit surface.

[0095] The pupil duplication device 60 is disposed at the pupil position of the projection lens 192. Light L incident on the input section 64 from the projection lens 192 propagates through the total reflection region 62 and is reflected in the Y-axis direction by each of the prisms 621 arranged in the X-axis direction. The light L reflected by each of the prisms 621 is reflected in the Z-axis direction by each of the prisms 631 arranged in the Y-axis direction, and is emitted from each of the surfaces 61S1, for example, as shown in FIG. 34 . For example, in a light guide plate 61 having ten prisms 621 arranged in the X-axis direction and five prisms 631 arranged in the Y-axis direction as shown in FIG. 33 , a single incident light ray is expanded (duplicated) into ten light rays in the total reflection region 62, and further expanded (duplicated) into 50 light rays in the output region 63 before being emitted. In other words, 50 pupils are duplicated in the X-axis and Y-axis directions.

[0096] Although the present disclosure has been described above with reference to the embodiment and modifications 1 to 6, various modifications are possible without being limited to the above-described embodiment, etc. For example, the arrangement and number of components of the optical system exemplified in the above-described embodiment, etc. are merely examples, and it is not necessary to include all of the components, and other components may also be included.

[0097] The effects described in this specification are merely examples and are not limited to those described, and other effects may also be obtained.

[0098] The present technology can also be configured as follows. According to the present technology configured as follows, a retroreflector that reflects light at a predetermined offset angle relative to the incident direction is used to output light in a desired direction, making it possible to create a wide-angle virtual image without using, for example, a huge mirror optical system. Therefore, it is possible to provide a projection device that can display a wide-FOV virtual image. [1] A projection device comprising: a display device; a reflecting mirror that reflects light output from the display device in a predetermined direction; and a retroreflector that reflects light incident via the reflecting mirror at a predetermined offset angle relative to the incident direction. [2] The projection device described in [1], wherein the retroreflector has a main surface on which a plurality of retroreflecting elements are arranged in a two-dimensional array, and the plurality of retroreflecting elements include one surface and a plurality of other surfaces adjacent to each other, the plurality of other surfaces abutting each other at an angle of 90°, and the one surface abutting each other at an angle greater than or less than 90°. [3] The projection device according to [1] or [2], wherein the retroreflector has a main surface on which a plurality of retroreflecting elements are arranged in a two-dimensional array, and each of the plurality of retroreflecting elements has a triangular pyramid shape consisting of three surfaces. [4] The projection device according to [3], wherein each of the plurality of retroreflecting elements has, as the three surfaces, a first surface and a second surface that are mutually perpendicularly joined, and a third surface that is a tilted surface inclined by an angle θ from a third' surface that is mutually perpendicularly joined to the first surface and the second surface. [5] The angle θ satisfies the following mathematical formula (1), and k ｐｒｏ and k' ＴＧＴ ｐｒｏ is defined by the following formulas (2) and (3). (m: rotation axis vector of tilt plane, k: incident light vector, k' ＴＧＴ: reflected light vector) [6] The projection device according to [4] or [5], wherein the θ angle of the tilt plane varies depending on the position of the main surface. [7] The projection device according to [4] or [5], wherein the main surface has a plurality of regions, and the θ angle of the tilt plane varies depending on the plurality of regions. [8] The projection device according to any one of [4] to [7], wherein the tilt planes of the plurality of retroreflective elements have the same θ angle, and the retroreflector is curved in an in-plane direction of the main surface. [9] The projection device according to any one of [4] to [7], wherein, when the body axis direction of a human is defined as the X-axis direction, the direction of both eyes is defined as the Y-axis direction, and the direction perpendicular to the X-axis direction and the Y-axis direction is defined as the Z-axis direction, the main surface of the retroreflector substantially coincides with the YZ plane, and both ends in the Y-axis direction are aligned with the X-axis direction.

[10] The projection device according to any one of [1] to [9], wherein the X-axis direction is the direction of a human body axis and the Y-axis direction is the direction of both eyes, and further comprises a pupil duplicating device between the display device and the reflecting mirror that duplicates a pupil conjugate point in at least one of the Y-axis direction and the X-axis direction.

[11] The projection device according to

[10] , wherein the pupil duplicating device includes a light guide plate having a hologram optical element provided on one surface and extending in one of the Y-axis direction and the X-axis direction.

[12] The projection device according to

[11] , further comprises a transmittance adjustment prism disposed on the one surface side of the light guide plate and extending in the other of the Y-axis direction and the X-axis direction.

[13] The projection device according to any one of [1] to

[12] , wherein the X-axis direction is the direction of a human body axis and the Y-axis direction is the direction of both eyes, and further comprises a pupil tracking device between the display device and the reflecting mirror that shifts a viewing area in the X-axis direction or the Y-axis direction according to the position of the human pupil.

[14] The projection device according to

[13] , which has a first drive unit that shifts the reflecting mirror in the Z-axis direction as the pupil tracking device.

[15] The projection device according to

[13] or

[14] , which has a second drive unit that shifts the display device in the Y-axis direction as the pupil tracking device.

[16] The projection device according to any one of [1] to

[15] , wherein the display device has an intensity modulation panel and a projection lens having a pupil at an exit.

[17] The projection device according to any one of

[10] to

[16] , wherein the display device has a phase modulation panel and a relay lens that directs the light to the pupil replication device.

[18] The projection device according to any one of [1] to

[17] , wherein the reflecting mirror is a windshield of a vehicle, and the display device and the retroreflector are disposed inside the vehicle.

[19] The projection device according to any one of [1] to

[18] , further comprising a pupil position detection camera that detects the position of a human pupil.

[0099] This application claims priority based on Japanese Patent Application No. 2024-032405, filed on March 4, 2024, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0100] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. A projection device comprising: a display device; a reflecting mirror that reflects light emitted from the display device in a predetermined direction; and a retroreflector that reflects light incident through the reflecting mirror at a predetermined offset angle relative to the incident direction.

2. The projection device described in claim 1, wherein the retroreflector has a main surface on which a plurality of retroreflecting elements are arranged in a two-dimensional array, the plurality of retroreflecting elements each consisting of one surface and a plurality of other surfaces adjacent to each other, the plurality of other surfaces adjoining each other at an angle of 90°, and the one surface and the plurality of other surfaces adjoining each other at an angle greater than or less than 90°.

3. The projection device according to claim 1, wherein the retroreflector has a main surface on which a plurality of retroreflecting elements are arranged in a two-dimensional array, and each of the plurality of retroreflecting elements has a triangular pyramid shape consisting of three faces.

4. The projection device described in claim 3, wherein each of the plurality of retroreflective elements has, as the three surfaces, a first surface and a second surface that are mutually perpendicular and in contact with each other, and a third surface that is a tilted surface inclined by an angle θ from a third' surface that is mutually perpendicular and in contact with the first surface and the second surface.

5. The θ angle satisfies the following formula (1), and k ｐｒｏ and k' ＴＧＴ ｐｒｏ The projection device according to claim 4 , wherein is defined by the following formulas (2) and (3): (m: rotation axis vector of tilt plane, k: incident light vector, k' ＴＧＴ : reflected light vector) 6. The projection device according to claim 4, wherein the θ angle of the tilt plane varies depending on the position of the main surface.

7. The projection device according to claim 4, wherein the main surface has a plurality of regions, and the θ angle of the tilt surface differs for each of the plurality of regions.

8. The projection device according to claim 4, wherein the tilt surfaces of the plurality of retroreflective elements have the same θ angle, and the retroreflective plate is curved in an in-plane direction of the main surface.

9. The projection device of claim 4, wherein, when the X-axis direction of a human body is defined as the X-axis direction, the Y-axis direction is defined as the direction of both eyes, and the Z-axis direction is defined as the direction perpendicular to the X-axis direction and the Y-axis direction, the main surface of the retroreflector substantially coincides with the YZ plane, and both ends in the Y-axis direction are aligned with the X-axis direction.

10. The projection device according to claim 1, further comprising a pupil duplicating device between said display device and said reflecting mirror, said pupil duplicating device duplicating a pupil conjugate point in at least one of the Y-axis direction and the X-axis direction, said pupil duplicating device being defined as the X-axis direction of a human body and the Y-axis direction of both eyes.

11. The projection device according to claim 10, wherein the pupil replicating device has a light guide plate on one surface of which a hologram optical element is provided and which extends in one of the Y-axis direction and the X-axis direction.

12. The projection device according to claim 11, further comprising a transmittance adjusting prism as the pupil duplication device, the transmittance adjusting prism being disposed on the one surface side of the light guide plate and extending in the other of the Y-axis direction and the X-axis direction.

13. The projection device according to claim 1, further comprising a pupil tracking device between the display device and the reflecting mirror, the X-axis direction being the direction of the human body axis and the Y-axis direction being the direction of both eyes, which shifts the visual recognition area in the X-axis direction or the Y-axis direction depending on the position of the human pupil.

14. The projection device according to claim 13, wherein the pupil tracking device comprises a first drive unit that shifts the reflecting mirror in the Z-axis direction.

15. The projection device according to claim 13, further comprising a second drive unit that shifts the display device in the Y-axis direction as the pupil tracking device.

16. The projection device of claim 1, wherein the display device comprises an intensity modulation panel and a projection lens having a pupil at its exit.

17. The projection device of claim 10, wherein the display device comprises a phase modulation panel and a relay lens that directs the light to the pupil replicator.

18. The projection device according to claim 1, wherein the reflecting mirror is a windshield of a vehicle, and the display device and the retroreflector are disposed inside the vehicle.

19. The projection device according to claim 1, further comprising a pupil position detection camera for detecting the position of a human pupil.

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