Virtual image display device

Abstract

To provide a virtual image display device which suppresses a glisten caused by reflection of an outside light pattern on a surface.SOLUTION: A virtual image display device 100 includes: a display element 11 as an image light generation unit; a projection optical system 12 which image light ML from the display element 11 enters; a partial transmission mirror 123 for partially reflecting the image light ML from the projection optical system 12 toward a pupil position PP; and a transmission polarizer 30p provided outside the partial transmission mirror 123.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a virtual image display device that enables viewing of a virtual image, and more particularly to a virtual image display device that includes a partially transmitting mirror. [Background technology]

[0002] There is a virtual image display device that has an optically transparent member arranged in front of the eyes, and allows the user to simultaneously observe image light and external light. For example, Patent Document 1 discloses a virtual image display device that includes a transmissive inclined mirror that reflects image light from an image light generating device, and a concave transmissive mirror that reflects the image light reflected by the transmissive inclined mirror toward the transmissive inclined mirror, and that has an absorbent layer arranged on the external side of the concave transmissive mirror. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-008749 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above prior art documents, the absorbent layer can prevent the image being displayed from being seen from the outside, but to an outsider, various light sources existing in the outside world are reflected on the surface of the eyeglass-like concave transmission mirror, and the external light pattern is projected onto the convex surface of the concave transmission mirror, appearing to sparkle. [Means for solving the problem]

[0005] A virtual image display device according to one aspect of the present invention comprises an image light generating device, a projection optical system into which image light from the image light generating device is incident, and a partially transmitting mirror that partially reflects the image light from the projection optical system toward a pupil position, and a transmissive polarizer is arranged outside the partially transmitting mirror. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is an external perspective view illustrating a wearing state of the virtual image display device according to the first embodiment. [Diagram 2] FIG. 2 is a side cross-sectional view illustrating a structure of the virtual image display device. [Diagram 3] 4 is a partially enlarged cross-sectional view illustrating the periphery of a partially transmitting mirror and a cover member. FIG. [Figure 4] FIG. 2 is a conceptual diagram for explaining the polarization state of a light beam in more detail. [Diagram 5] 13 is a cross-sectional view illustrating a modified example of the see-through mirror. FIG. [Figure 6] FIG. 11 is a cross-sectional view illustrating a modified example of the polarizing filter. [Figure 7] FIG. 11 is a side cross-sectional view illustrating the structure of a virtual image display device according to a second embodiment. [Figure 8] FIG. 4 is a partially enlarged cross-sectional view illustrating the periphery of a partially transmitting mirror. [Figure 9] FIG. 11 is a side cross-sectional view illustrating the structure of a virtual image display device according to a third embodiment. [Figure 10] FIG. 4 is a partially enlarged cross-sectional view illustrating the periphery of a partially transmitting mirror. [Figure 11] FIG. 2 is a conceptual diagram for explaining the polarization state of a light beam in more detail. [Figure 12] 11A and 11B are diagrams illustrating a modified example of the see-through mirror shown in FIG. 10 etc. [Figure 13] FIG. 13 is a side cross-sectional view illustrating a virtual image display device according to a fourth embodiment. [Figure 14] FIG. 13 is a side cross-sectional view illustrating a virtual image display device according to a modified example. [Figure 15] FIG. 13 is a side cross-sectional view illustrating a virtual image display device according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [First embodiment] Hereinafter, a virtual image display device according to a first embodiment of the present invention will be described with reference to FIGS.

[0008] Fig. 1 is a diagram for explaining a wearing state of a head mounted display (hereinafter also referred to as HMD) 200, and the HMD 200 allows an observer or wearer US wearing the HMD 200 to recognize an image as a virtual image. In Fig. 1 and the like, X, Y, and Z are an orthogonal coordinate system, and the +X direction corresponds to the lateral direction in which both eyes EY of the observer or wearer US wearing the HMD 200 or virtual image display device 100 are aligned, the +Y direction corresponds to the upward direction perpendicular to the lateral direction in which both eyes EY are aligned for the wearer US, and the +Z direction corresponds to the forward direction or front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

[0009] The HMD 200 includes a first display device 100A for the right eye, a second display device 100B for the left eye, a pair of temple-shaped support devices 100C for supporting the display devices 100A and 100B, and a user terminal 90 that is an information terminal. The first display device 100A functions as a virtual image display device by itself, and is composed of a display drive unit 102 arranged at the top, a combiner 103 shaped like a glasses lens that covers the front of the eyes, and a cover member 104 that covers the combiner 103 from the front. The second display device 100B also functions as a virtual image display device by itself, and is composed of a display drive unit 102 arranged at the top, a combiner 103 shaped like a glasses lens that covers the front of the eyes, and a cover member 104 that covers the combiner 103. The combination of the pair of cover members 104 is called a shade 105. The shade 105 is an integrated member and is detachable from the display drive unit 102 via a support mechanism (not shown). The support device 100C is a mounting member mounted on the head of the wearer US, and supports the upper end side of the combiner 103 via the display drive unit 102. The first display device 100A and the second display device 100B are optically reversed from left to right, and a detailed description of the second display device 100B will be omitted.

[0010] 2 is a side cross-sectional view illustrating the optical structure of the first display device 100A. The first display device 100A includes a display element 11, an imaging optical system 20, a polarizing filter 30, and a display control device 88. The imaging optical system 20 includes a projection lens 21, a prism mirror 22, and a see-through mirror 23. In the imaging optical system 20, the projection lens 21 and the prism mirror 22 function as the projection optical system 12 into which the image light ML from the display element 11, which is an image light generating device, is incident, and the see-through mirror 23 functions as a partial transmission mirror 123 that partially reflects the image light ML emitted from the projection optical system 12 toward the pupil position PP or the eye EY. The projection lens 21 and the prism mirror 22 that constitute the projection optical system 12 correspond to the first optical member and the second optical member into which the video light or the image light ML is incident, respectively. The display element 11, the projection lens 21, and the prism mirror 22 correspond to a part of the display drive unit 102 shown in FIG. 1, and the see-through mirror 23 corresponds to the combiner 103 shown in FIG. 1. The see-through mirror 23 has an outer shape that is convex on the outside, and its external side is partially covered by a polarizing filter 30 provided separately. The projection lens 21 and the prism mirror 22 that constitute the projection optical system 12 are fixed in the case 51 in a state in which they are mutually aligned together with the display element 11. The polarizing filter 30 corresponds to the cover member 104 shown in FIG. 1. The case 51 is a housing or a support member, is formed of a light-shielding material, and supports the display control device 88 that operates the display element 11. The case 51 has an opening 51a, and the opening 51a is closed by a light-transmitting plate 53. The light-transmitting plate 53 enables the projection optical system 12 to emit the image light ML toward the outside of the case 51, and suppresses the intrusion of dust and moisture into the inside of the case 51.

[0011] In the first display device 100A, the display element 11 is a self-luminous image light generating device. The display element 11 is, for example, an organic EL (organic electroluminescence) display, and forms a color still image or moving image on a two-dimensional display surface 11a. The display element 11, which is an image light generating device, is driven by a display control device 88, which is a control unit, to perform a display operation. The display element 11 is not limited to an organic EL display, and can be replaced with a display device using an inorganic EL, an organic LED, an LED array, a laser array, a quantum dot light emitting element, or the like. The display element 11 is not limited to a self-luminous image light generating device, and may be composed of an LCD or other light modulation element, and may form an image by illuminating the light modulation element with a light source such as a backlight. As the display element 11, instead of an LCD, LCOS (Liquid crystal on silicon, LCoS is a registered trademark), a digital micromirror device, or the like can be used.

[0012] When the display element 11 is, for example, an LCD, the image light ML emitted from the display element 11 is generally polarized light. As described later, in this embodiment, the reflective polarizing film 23a of the see-through mirror 23 reflects S-polarized light, so the image light ML emitted from the display element 11 needs to be S-polarized light or include S-polarized light.

[0013] The imaging optical system 20 is an off-axis optical system OS due to the fact that the see-through mirror 23 is a concave mirror. In this embodiment, the projection lens 21, the prism mirror 22, and the see-through mirror 23 are arranged non-axisymmetrically and have a non-axisymmetric optical surface. In this imaging optical system 20, the optical axis AX is bent in an off-axis plane parallel to the YZ plane, and the optical elements 21, 22, and 23 are arranged along the off-axis plane. Specifically, in the off-axis plane parallel to the YZ plane, an optical path P1 from the projection lens 21 to the internal reflection surface 22b, an optical path P2 from the internal reflection surface 22b to the see-through mirror 23, and an optical path P3 from the see-through mirror 23 to the pupil position PP are folded back in two stages in a Z-shape. As a result, the normal to the central location where the optical axis AX intersects in the see-through mirror 23 forms an angle of about θ=40 to 50° with respect to the Z direction. In this imaging optical system 20, the optical elements 21, 22, and 23 constituting the first display device 100A are arranged at different height positions in the vertical direction, so that the width of the first display device 100A can be prevented from increasing. Furthermore, the optical paths P1 to P3 are arranged to be folded back in two stages in a Z-shape by folding the optical paths due to reflection by the prism mirror 22 or the like, and the optical paths P1 and P3 are relatively close to horizontal, so that the imaging optical system 20 can be made compact in the vertical and front-rear directions. In addition, since the inclination angle θ at the center of the see-through mirror 23 is 40 to 50°, if the inclination of the optical path P3 corresponding to the line of sight is constant, the inclination of the optical path P2 with respect to the Z axis is 70° to 90°, so that it is easy to reduce the thickness of the virtual image display device 100 in the Z direction.

[0014] In the imaging optical system 20, the optical path P1 from the projection lens 21 to the internal reflection surface 22b extends in a direction slightly obliquely upward toward the rear with respect to the viewpoint as a reference, or in a direction nearly parallel to the Z direction. The optical path P2 from the internal reflection surface 22b to the see-through mirror 23 extends in a direction obliquely downward toward the front. When the horizontal plane direction (XZ plane) is used as a reference, the inclination of the optical path P2 is greater than the inclination of the optical path P1. The optical path P3 from the see-through mirror 23 to the pupil position PP extends in a direction slightly obliquely upward toward the rear, or in a direction nearly parallel to the Z direction. In the illustrated example, the portion of the optical axis AX corresponding to the optical path P3 is about -10° toward the +Z direction, with downward being negative. In other words, the partially transmitting mirror 123 reflects the image light ML so that the optical axis AX or the optical path P3 is directed upward by a predetermined angle, that is, about 10° upward. As a result, the exit optical axis EX, which is an extension of the portion of the optical axis AX that corresponds to the optical path P3, extends at a downward inclination of about 10° with respect to the central axis HX that is parallel to the forward +Z direction. This is because the human line of sight is stable in a slightly downcast state that is inclined about 10° downward from the horizontal. Note that the central axis HX extending horizontally with respect to the pupil position PP is based on the assumption that the wearer US wearing the first display device 100A is in an upright, relaxed position, facing forward, and gazing horizontally or at the horizon.

[0015] The overall optical path in the imaging optical system 20 is not limited to three optical paths P1, P2, and P3 that form a Z-shape as shown in the figure, but can be changed to various ones including two or four or more optical paths. In the example shown in the figure, the first optical path P1 and the last optical path P3 are closer to horizontal than the intermediate optical path P2, but the angles of the optical paths P1, P2, and P3 can also be set to various ones taking into consideration the use of the virtual image display device 100. However, it is generally desirable to set the last optical path P3 in consideration of the line of sight as described above. The attitude of the partially transmitting mirror 123 is affected by the angle setting of the intermediate optical path P2 and the angle setting of the last optical path P3, especially in the central part where the optical axis AX passes.

[0016] In the imaging optical system 20, the projection lens 21 includes a first lens 21o, a second lens 21p, and a third lens 21q. The projection lens 21 receives the image light ML emitted from the display element 11 and makes it incident on the prism mirror 22. The projection lens 21 condenses the image light ML emitted from the display element 11 into a state close to a parallel light beam. The optical surfaces, i.e., the entrance surface and the exit surface, of the first lens 21o, the second lens 21p, and the third lens 21q constituting the projection lens 21 are free-form surfaces or aspheric surfaces, and have asymmetrical properties across the optical axis AX in the vertical direction parallel to the YZ plane and intersecting the optical axis AX, and have symmetry across the optical axis AX in the horizontal direction or X direction. The first lens 21o, the second lens 21p, and the third lens 21q are formed of, for example, resin, but may also be made of glass. On the optical surfaces of the first lens 21o, the second lens 21p, and the third lens 21q that configure the projection lens 21, an anti-reflection film can be formed.

[0017] The prism mirror 22 is an optical member having a refractive and reflective function that has a function combining a mirror and a lens, and reflects the image light ML from the projection lens 21 while refracting it. The prism mirror 22 has an entrance surface 22a corresponding to the entrance portion, an internal reflection surface 22b corresponding to the reflection portion, and an exit surface 22c corresponding to the exit portion. The prism mirror 22 emits the image light ML incident from the front so as to bend it back in a direction inclined downward with respect to a direction in which the incident direction is reversed (the direction of the light source as seen from the prism mirror 22). The entrance surface 22a, the internal reflection surface 22b, and the exit surface 22c, which are optical surfaces constituting the prism mirror 22, are asymmetrical with respect to the optical axis AX in the vertical direction that is parallel to the YZ plane and intersects with the optical axis AX, and are symmetrical with respect to the optical axis AX in the horizontal direction or X direction. The optical surfaces of the prism mirror 22, that is, the entrance surface 22a, the internal reflection surface 22b, and the exit surface 22c, are, for example, free-form surfaces. The entrance surface 22a, the inner reflection surface 22b, and the exit surface 22c are not limited to free-form surfaces, but may be aspheric surfaces. The prism mirror 22 is formed of, for example, resin, but may also be made of glass. The inner reflection surface 22b is not limited to a surface that reflects the image light ML by total reflection, but may also be a reflection surface made of a metal film or a dielectric multilayer film. In this case, a reflection film made of a single layer or multilayer film made of a metal such as Al or Ag is formed on the inner reflection surface 22b by deposition or the like, or a sheet-like reflection film made of a metal or the like is attached. Although detailed illustration is omitted, an anti-reflection film may be formed on the entrance surface 22a and the exit surface 22c.

[0018] The see-through mirror 23 is a curved, plate-like reflective optical member that functions as a concave surface mirror, and reflects the image light ML from the prism mirror 22 and partially transmits the outside light OL. The see-through mirror 23 reflects the image light ML from the prism mirror 22 arranged in the exit region of the projection optical system 12 toward the pupil position PP. The see-through mirror 23 has a reflective surface 23c and an outer surface 23o.

[0019] The see-through mirror 23 partially reflects the image light ML and magnifies the intermediate image formed on the light exit side of the prism mirror 22. The see-through mirror 23 is a concave mirror that covers the pupil position PP where the eye EY or pupil is located, has a concave shape toward the pupil position PP, and has a convex shape toward the outside world. The pupil position PP or its opening PPa is called the eye point or eye box. The pupil position PP or the opening PPa corresponds to the exit pupil EP on the exit side of the imaging optical system 20. The see-through mirror 23 is a collimator, and converges the chief ray of the image light ML, which is emitted from each point on the display surface 11a and which once spreads due to imaging near the exit side of the prism mirror 22 of the projection optical system 12, to the pupil position PP. As a concave mirror, the see-through mirror 23 makes it possible to enlarge and view an intermediate image (not shown) formed on the display element 11, which is an image light generating device, and re-imaged by the projection optical system 12. More specifically, the see-through mirror 23 functions similarly to a field lens, and collimates image light ML from each point of an intermediate image (not shown) formed behind the exit surface 22c of the prism mirror 22, and causes the image light ML to be incident on the pupil position PP so as to be collected as a whole. In terms of being disposed between the intermediate image and the pupil position PP, the see-through mirror 23 needs to have a width equal to or larger than the effective area EA, which corresponds to the angle of view (a combination of the viewing angles in the up, down, left and right directions based on the optical axis AX extending in the front direction of the eye). In the see-through mirror 23, the outer area extending outward from the effective area EA does not directly affect the image formation, so it can have any surface shape, but from the viewpoint of ensuring an appearance like that of a eyeglass lens, it is preferable that the curvature of the surface shape of the outer edge of the effective area EA is the same as that of the outer edge of the effective area EA, or that it changes continuously from the outer edge.

[0020] The see-through mirror 23 is a semi-transmissive mirror plate having a structure in which a reflective polarizing film 23a is formed on the back surface of a plate-shaped body 23b. The reflecting surface 23c of the see-through mirror 23 is asymmetrical about the optical axis AX in the vertical direction parallel to the YZ plane and intersecting the optical axis AX, and is symmetrical about the optical axis AX in the horizontal direction or X direction. The reflecting surface 23c of the see-through mirror 23 is, for example, a free-form surface. The reflecting surface 23c is not limited to a free-form surface, and can also be an aspheric surface. The reflecting surface 23c needs to have an area equal to or larger than the effective area EA. When the reflecting surface 23c is formed in an outer area wider than the effective area EA, the difference in appearance is unlikely to occur between an external image from behind the effective area EA and an external image from behind the above-mentioned outer area.

[0021] The reflecting surface 23c of the see-through mirror 23 or the reflective polarizing film 23a is formed by a polarizing film that reflects S-polarized light, and functions as a reflective polarizer 23p. The reflective polarizing film 23a has its polarization axis set in the vertical direction. In other words, the reflective polarizing film 23a has its reflection axis set in the horizontal direction, and efficiently reflects S-polarized light polarized in the ±X direction corresponding to the horizontal direction with little attenuation, and transmits almost all P-polarized light polarized in the ±Y direction corresponding to the vertical direction. The transmission axis of the reflective polarizing film 23a is in the vertical direction, that is, the ±Y direction. As a result, the S component of the image light ML is reflected and the P component is transmitted, and the film functions like a half mirror for the image light ML. On the other hand, when the outside light OL passes through the polarizing filter 30, if the transmitted outside light OL is S-polarized, it is blocked by the see-through mirror 23, and if the transmitted outside light OL is P-polarized, it passes through the see-through mirror 23. This makes it possible to see through the outside world, and a virtual image can be superimposed on the outside world image. In this case, if the plate 23b supporting the reflective polarizing film 23a is thin, about a few mm or less, the change in magnification of the outside world image can be kept small. The plate 23b, which is the base material of the see-through mirror 23, is made of, for example, resin, but can also be made of glass. The plate 23b is made of the same material as the support plate 61 that supports it from the periphery, and has the same thickness as the support plate 61. The reflective polarizing film 23a is made of, for example, a dielectric multilayer film consisting of multiple dielectric layers with adjusted film thickness. The reflective polarizing film 23a can be formed by lamination, but can also be formed by attaching a sheet-like reflective film. An anti-reflection film can be formed on the outer surface 23o of the plate 23b.

[0022] The polarizing filter 30 transmits light polarized in a first direction, i.e., P-polarized light, of the outside light OL, and attenuates or blocks light polarized in a second direction, i.e., S-polarized light, of the outside light OL. In the illustrated example, the polarizing filter 30 has a convex shape facing the outside, similar to the see-through mirror 23. The polarizing filter 30 has a structure in which a transmission type polarizing film 30a is formed on the surface of a plate-shaped body 30b. The transmission type polarizing film 30a is formed of a polarizing film that transmits P-polarized light, and functions as a transmission type polarizer 30p. Here, the transmission type polarizer 30p is disposed outside the reflection type polarizing film 23a or the reflection type polarizer 23p of the see-through mirror 23. In other words, the virtual image display device 100 includes a cover member 104 on which the transmission type polarizing film 30a is provided as the transmission type polarizer 30p, outside the partial transmission mirror 123. The polarization axis of the transmission type polarizing film 30a is set in the vertical direction. That is, the transmission polarizing film 30a has a transmission axis set in the vertical direction, and efficiently transmits P-polarized light polarized in the ±Y direction corresponding to the vertical direction with little attenuation, and absorbs and attenuates most of the S-polarized light polarized in the ±X direction corresponding to the horizontal direction. The transmission axis of the transmission polarizing film 30a is in the vertical direction, i.e., the ±Y direction, and coincides with the transmission axis of the reflective polarizing film 23a of the see-through mirror 23. The plate-shaped body 30b supporting the transmission polarizing film 30a is thin, about 1 mm or less, and keeps the magnification change of the external image small. The plate-shaped body 30b, which is the base material of the polarizing filter 30, is made of, for example, resin. The transmission polarizing film 30a is made of a polarizing film obtained by stretching, for example, a polymer material containing an iodine compound or a dye in a specific direction, and can be formed directly on the plate-shaped body 30b, or can be formed into a sheet and attached to the plate-shaped body 30b. The transmissive polarizing film 30a may be provided with a polarizing function by applying a liquid material containing liquid crystal or other absorbent material onto the plate-shaped body 30b and imparting light distribution characteristics by irradiating ultraviolet light in a specific polarized state. An anti-reflection film can be formed on the inner surface 30i of the plate-shaped body 30b.

[0023] Regarding the optical path, the image light ML from the display element 11 enters the projection lens 21 and is emitted from the projection lens 21 in a substantially collimated state. The image light ML that passes through the projection lens 21 enters the prism mirror 22 and passes through the entrance surface 22a while being refracted, is reflected by the internal reflection surface 22b with a high reflectance rate close to 100%, and is refracted again by the exit surface 22c. The image light ML from the prism mirror 22 forms an intermediate image once, then enters the see-through mirror 23 and is reflected by the reflection surface 23c with a reflectance rate of about 50% or less. At this time, mainly S-polarized light is reflected and P-polarized light is transmitted. The image light ML reflected by the see-through mirror 23 enters the pupil position PP where the eye EY or pupil of the wearer US is located. External light OL that has passed through the see-through mirror 23 and the support plate 61 around it also enters the pupil position PP. That is, the wearer US wearing the first display device 100A can observe a virtual image formed by the image light ML superimposed on an image of the outside world. If the transmittance of the reflecting surface 23c of the see-through mirror 23 for P-polarized light is, for example, about 50%, and if the image light ML from the display element 11 has no bias in terms of polarization, the P-polarized image light ML that has passed through the see-through mirror 23 also passes through the polarizing filter 30. If the transmittance of the polarizing filter 30 for P-polarized light is 50%, the polarizing filter 30 can suppress leakage of the image light ML to the outside world by 50%, and the amount of leaking light will be about 25% of the original amount.

[0024] With reference to FIG. 3, a detailed description will be given of the case where external light OL is incident from the outside of the polarizing filter 30. The external light OL includes P polarized light and S polarized light, and when passing through the transmission type polarizing film 30a of the polarizing filter 30, the S polarized light is absorbed and the P polarized light passes with high transmittance. Here, the polarizing filter 30 is a transmission type, and the external light OL is hardly reflected. The light OL1 that passes through the transmission type polarizing film 30a is only P polarized light, and passes through the reflective polarizing film 23a of the see-through mirror 23 with high transmittance. The light OL2 that passes through the reflective polarizing film 23a is incident on the eye EY of the wearer US. This allows the wearer US to observe an image corresponding to the image light ML superimposed on an external image corresponding to the light OL2. At this time, the transmittance of the external light OL through the polarizing filter 30 and the see-through mirror 23 can be about 50%. On the other hand, since the external light OL is hardly reflected by the polarizing filter 30, the phenomenon in which the external light pattern is reflected in a reduced state on the convex surface of the polarizing filter 30 and appears to sparkle is suppressed. This not only prevents the appearance of a high-brightness pattern from being reflected when the HMD 200 or the virtual image display device 100 is worn, but also facilitates eye contact between the wearer and the person facing him / her. Since the transmission axis of the reflective polarizer 23p and the transmission axis of the transmissive polarizer 30p extend in the vertical direction, even if the polarizing filter 30 reflects or transmits a small amount of left-right or horizontal S-polarized light, when the external light OL contains a lot of horizontal polarized light, such as light reflected on the surface of water, the surface of the polarizing filter 30 can be effectively suppressed from sparkling.

[0025] When external light OL is directly incident on the lower part of the see-through mirror 23, P-polarized light of the external light OL passes through the reflective polarizing film 23a of the see-through mirror 23 with high transmittance, and S-polarized light of the external light OL is reflected by the reflective polarizing film 23a with a relatively high reflectance. P-polarized light OL3 transmitted through the reflective polarizing film 23a is incident on the eye EY of the wearer US. On the other hand, when S-polarized light OL4 reflected by the reflective polarizing film 23a is incident on the back side of the polarizing filter 30, it is absorbed by the transmissive polarizing film 30a and is not emitted to the outside world.

[0026] FIG. 4 is a diagram specifically explaining the electric field of the external light OL passing through the polarizing filter 30 and the see-through mirror 23 shown in FIG. 3. In the figure, x, y, and z are a local coordinate system based on the traveling direction of the external light OL, the ±x direction indicates the left-right direction, the ±y direction indicates the up-down direction, and the +z direction indicates the propagation direction of the light. When the external light OL shown in FIG. 3 propagates in the -Z direction, the +x direction corresponds to the -X direction, the +y direction corresponds to the +Y direction, and the +z direction corresponds to the -Z direction. When there is no polarization, the external light OL includes a linearly polarized component having an amplitude parallel to the yz plane, i.e., P-polarized light in the up-down direction, and a linearly polarized component having an amplitude parallel to the xz plane, i.e., S-polarized light in the left-right direction. When external light OL enters the polarizing filter 30 from the external space OA, the light OL1 that passes through the polarizing filter 30 and exits in the +z direction will be only P-polarized light in the vertical direction, or will contain both P-polarized light in the vertical direction and weak S-polarized light in the horizontal direction. When the light OL1 that has passed through the polarizing filter 30 enters the see-through mirror 23, the light OL2 that passes through the see-through mirror 23 and exits into the internal space IA will be only P-polarized light in the vertical direction. Even if weak S-polarized light is reflected in the -z direction by the see-through mirror 23, it is almost entirely absorbed by the polarizing filter 30.

[0027] Returning to FIG. 2, the display control device 88 is a display control circuit, and outputs a drive signal corresponding to an image to the display element 11 to control the display operation of the display element 11. The display control device 88 includes, for example, an IF circuit, a signal processing circuit, and the like, and causes the display element 11 to perform two-dimensional image display in response to image data or an image signal received from the outside. The display control device 88 may include a main board that controls the first display device 100A and the second display device 100B. The main board may have an interface function that communicates with the user terminal 90 shown in FIG. 1 and converts signals received from the user terminal 90, and an integration function that links the display operation of the first display device 100A with the display operation of the second display device 100B. Note that the HMD 200 or the virtual image display device 100 that does not include the display control device 88 or the user terminal 90 is also a virtual image display device.

[0028] FIG. 5 is a diagram for explaining a modified example of the see-through mirror 23 shown in FIG. 3 and the like. In this case, the see-through mirror 23 has a semi-transparent mirror film 23r formed as a reflective surface 23c. The semi-transparent mirror film 23r has non-polarized reflection and transmission characteristics, and is formed of a single-layer film or a multi-layer film of a metal such as Al or Ag with an adjusted thickness. The semi-transparent mirror film 23r may be formed of a dielectric multi-layer film consisting of a plurality of dielectric layers with an adjusted thickness. In this case, the light OL1 from the outside world that has passed through the polarizing filter 30 is partially transmitted through the semi-transparent mirror film 23r and partially reflected. When the transmittance of the semi-transparent mirror film 23r is 50%, the light OL2 that passes through the see-through mirror 23 and is emitted to the pupil position PP side has an intensity of about 1 / 4 of the original outside light OL. In addition, the light OL5 that is reflected by the semi-transparent mirror film 23r, passes through the polarizing filter 30, and is emitted to the outside world side also has an intensity of about 1 / 4 of the original outside light OL. When the image light ML from the display element 11 has no polarization, the P-polarized image light ML that has passed through the see-through mirror 23 also passes through the polarizing filter 30, but the S-polarized image light ML is blocked by the polarizing filter 30. As a result, it is possible to suppress leakage of the image light ML to the outside world.

[0029] 6 is a diagram illustrating a modification of the polarizing filter 30 shown in FIG. 3 etc. The polarizing filter 30 has a flat plate region FA. The transmission polarizing film 30a is formed in the flat plate region FA. In this case, it is easy to form the transmission polarizing film 30a into a sheet shape and attach it to the plate-like body 30b.

[0030] According to the virtual image display device 100 of the first embodiment described above, since the transmission type polarizer 30p is disposed on the outside of the partial transmission mirror 123, the transmission type polarizer 30p allows polarized light in a specific direction of the outside light OL to be transmitted through the partial transmission mirror 123 and enter the pupil position PP, while suppressing the reflection of polarized light in a specific direction of the outside light OL or a direction perpendicular thereto, and therefore it is possible to suppress the outside light pattern from being reflected on the surface of the partial transmission mirror 123 and appearing to sparkle. This makes it possible to facilitate eye contact while preventing any discomfort in appearance when the virtual image display device 100 is worn.

[0031] In particular, in the first embodiment, the partial transmission mirror 123 has a reflective polarizer 23p, and a transmission polarizer 30p whose transmission axis coincides with that of the reflective polarizer 23p is disposed outside the reflective polarizer 23p. In this case, the partial transmission mirror 123 can transmit polarized light in a specific direction out of the outside light without loss.

[0032] In the above embodiment, the transmission axis of the reflective polarizer 23p and the transmission axis of the transmission polarizer 30p are parallel to the vertical direction, i.e., the ±Y direction, but the transmission axis of the reflective polarizer 23p and the transmission axis of the transmission polarizer 30p are made to coincide with each other means that the transmission axis of the reflective polarizer 23p and the transmission axis of the transmission polarizer 30p form an angle of ±45° or less. In other words, even if the transmission axis of the reflective polarizer 23p and the transmission axis of the transmission polarizer 30p form an angle of 45°, the transmission axes of both are coincident. However, from the viewpoint of facilitating observation of the outside light OL, the angle between the transmission axis of the reflective polarizer 23p and the transmission axis of the transmission polarizer 30p is made to be ±20° or less, preferably ±10° or less, so that the outside light OL can be efficiently incident on the pupil position PP. Furthermore, in the above embodiment, the transmission axes of the reflective polarizer 23p and the transmission polarizer 30p are parallel to the vertical direction, i.e., the ±Y direction, but the transmission axes of the reflective polarizer 23p and the transmission polarizer 30p may be parallel to the horizontal direction, i.e., the ±X direction.

[0033] Second Embodiment Hereinafter, a virtual image display device according to a second embodiment of the present invention will be described. Note that the virtual image display device of the second embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of the common parts will be omitted.

[0034] 7 is a side cross-sectional view for explaining the optical structure of the first display device 100A in the virtual image display device of the second embodiment. In this case, the see-through mirror 23 is integrally assembled with the polarizing filter 30 (see FIG. 2) of the first embodiment. Specifically, a reflective polarizing film 23a is formed on the eye EY side of the plate-shaped body 23b, and a transmissive polarizing film 30a is formed on the outside side of the plate-shaped body 23b. In the see-through mirror 23 or the partial transmission mirror 223, the reflective polarizing film 23a provided on the inner side of the plate-shaped body 23b, which is the base material, functions as the reflective polarizer 23p, and the transmissive polarizing film 30a attached to the outer side of the plate-shaped body 23b, which is the base material, functions as the transmissive polarizer 30p.

[0035] As shown in FIG. 8, in the virtual image display device of the second embodiment, when external light OL is incident from the outside of the see-through mirror 23 or the partial transmission mirror 223, when the external light OL passes through the transmission type polarizing film 30a of the polarizing filter 30, S-polarized light is absorbed and P-polarized light passes with high transmittance. In other words, the external light OL is hardly reflected by the polarizing filter 30. As in the present embodiment, the reflection type polarizing film 23a is formed on the surface of the see-through mirror 23, and the partial transmission mirror 223 and the transmission type polarizer 30p are integrated, simplifying the structure of the virtual image display device 100. As in the first embodiment, the light OL1 that passes through the transmission type polarizing film 30a of the see-through mirror 23 is only P-polarized light and passes through the reflection type polarizing film 23a with high transmittance. The light OL2 that passes through the reflection type polarizing film 23a is incident on the eye EY of the wearer US.

[0036] Third Embodiment Hereinafter, a virtual image display device according to a third embodiment of the present invention will be described. The virtual image display device of the third embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of the common parts will be omitted.

[0037] 9 is a side cross-sectional view for explaining the optical structure of the first display device 100A in the virtual image display device of the third embodiment, and FIG. 10 is a partially enlarged cross-sectional view for explaining the see-through mirror 23. In this case, the see-through mirror 23 or the partial transmission mirror 323 includes a plate-shaped body 23b as a base material, a semi-transmitting mirror film 323r provided on the eye EY side of the plate-shaped body 23b, a λ / 4 wave plate 334 provided on the outside world side of the plate-shaped body 23b, and a transmission type polarizing film 30a formed on the outside world side of the λ / 4 wave plate 334. The λ / 4 wave plate 334 is disposed between the semi-transmitting mirror film 323r and the transmission type polarizing film 30a which is the transmission type polarizer 30p. The semi-transmitting mirror film 323r has non-polarized reflection characteristics and transmission characteristics, and is formed of a single layer film or a multilayer film of a metal such as Al or Ag with an adjusted film thickness. The principal axis of the λ / 4 wave plate 334 is set to be between, for example, the -X direction and the +Y direction, and to be at an angle of 45° to both directions. In this case, the transmission polarizer 30p and the λ / 4 wave plate 334 function as a circular polarization filter, and even if the outside light OL enters the partial transmission mirror 323 through the transmission polarizer 30p and is reflected by the semi-transmission mirror film 323r on the back surface to form a reflected light traveling backward, such a reflected light is prevented from passing through the transmission polarizer 30p. That is, when the outside light OL enters from the outside of the see-through mirror 23, the outside light OL becomes only P-polarized light by passing through the transmission polarizing film 30a. The light OL1 that passes through the transmission polarizing film 30a becomes circularly polarized light when passing through the λ / 4 wave plate 334, and is reflected by the semi-transmission mirror film 323r. The light OL1' reflected by the semi-transparent mirror film 323r becomes S-polarized light when passing through the λ / 4 wave plate 334 again, and is therefore absorbed by the transmissive polarizing film 30a and is not emitted to the outside world.

[0038] Of the light OL1 that passes through the transmissive polarizing film 30a, the circularly polarized light that passes through the λ / 4 wave plate 334 and is incident on the semi-transmissive mirror film 323r and partially passes through the semi-transmissive mirror film 323r is incident on the pupil position PP as light OL2.

[0039] FIG. 11 is a diagram specifically explaining the electric field of the outside light OL passing through the see-through mirror 23 or the partial transmission mirror 323 shown in FIG. 10. As shown in the area A1 in FIG. 11, when the outside light OL enters the partial transmission mirror 323, the light OL1 passing through the transmission polarizing film 30a and exiting in the +z direction becomes P-polarized light in the up-down direction. The P-polarized light OL1 enters the λ / 4 wave plate 334, and contains a first component C1 parallel to the fast axis and a second component C2 parallel to the slow axis. When the light OL1 passes through the λ / 4 wave plate 334, a phase difference of π / 2 occurs between the first component C1 and the second component C2 due to the action of birefringence, and the light OL1 becomes circularly polarized light. The light OL1 that has passed through the λ / 4 wave plate 334 enters the semi-transmission mirror film 323r and is partially transmitted therethrough. The light OL2 that passes through the semi-transmission mirror film 323r and exits into the internal space IA is circularly polarized light C.

[0040] As shown in region A2 in Fig. 11, the light OL1' reflected by the semi-transparent mirror film 323r becomes S-polarized light due to a phase difference of π when traveling backward through the λ / 4 wave plate 334, so it is absorbed when passing through the transmissive polarizing film 30a and is not emitted to the external space OA. Note that in region A2 in Fig. 11, the phase of the electromagnetic wave is not inverted by reflection at the semi-transparent mirror film 323r, but even if the phase of the electromagnetic wave is inverted by reflection at the semi-transparent mirror film 323r as shown in region A3 in Fig. 11, the light OL1' reflected by the semi-transparent mirror film 323r similarly becomes S-polarized light when traveling backward through the λ / 4 wave plate 334 and is not emitted to the external space OA.

[0041] In the example shown in FIG. 10, the semi-transparent mirror film 323r is formed on the rear surface of the plate-shaped body 23b. However, the plate-shaped body 23b may be omitted, and the semi-transparent mirror film 323r may be formed on the rear surface of the λ / 4 wave plate 334.

[0042] FIG. 12 is a diagram for explaining a modified example of the see-through mirror 23 shown in FIG. 10 and the like. In this case, the see-through mirror 23 or the partial transmission mirror 323 includes a plate-shaped body 23b, a reflective polarizing film 23a, a λ / 2 wavelength plate 335, and a transmission polarizing film 30a. The transmission axis of the transmission polarizing film 30a is in the left-right direction. As a result, the light OL1 that passes through the transmission polarizing film 30a and is emitted in the +z direction becomes P-polarized light due to the action of birefringence when passing through the λ / 2 wavelength plate 335. Most of the light OL1 that passes through the λ / 2 wavelength plate 335 is transmitted through the reflective polarizing film 23a and is emitted to the inside of the see-through mirror 23 as light OL2. Therefore, the outside light OL is hardly reflected by the see-through mirror 23.

[0043] [Fourth embodiment] Hereinafter, a virtual image display device according to a fourth embodiment of the present invention will be described. The virtual image display device of the fourth embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of common parts will be omitted.

[0044] As shown in FIG. 13, the virtual image display device 100 of the fourth embodiment includes a display element 11, an imaging optical system 20, and a polarizing filter 30. The imaging optical system 20 includes a projection optical system 12, a half mirror 40, and a see-through mirror 23. The half mirror 40 is a mirror film 40a formed on a parallel plate and made of a semi-transparent reflective layer. The mirror film 40a exhibits a reflectance of about 50% for the image light ML. The see-through mirror 23 is formed with a reflective polarizing film 23a, i.e., a reflective polarizer 23p, and the polarizing filter 30 is formed with a transmission polarizing film 30a, i.e., a transmission polarizer 30p. The mirror film 40a of the half mirror 40 can be, for example, a reflective polarizing film, i.e., a reflective polarizer 40p.

[0045] In the virtual image display device 100, the image light ML from the display element 11 passes through the projection optical system 12 to form an image, is reflected by the half mirror 40, and is incident on the see-through mirror 23. Of the image light ML incident on the see-through mirror 23, the S-polarized light is reflected and collimated, transmits through the half mirror 40, and is incident on the pupil position PP.

[0046] In this case, as in the first embodiment and the like, the external light OL is hardly reflected by the polarizing filter 30, so the phenomenon in which the external light pattern is reflected on the convex surface of the polarizing filter 30 and appears to sparkle is suppressed.

[0047] Fig. 14 shows a modified example of the virtual image display device 100 of the fourth embodiment shown in Fig. 13. In this case, the half mirror 40 is omitted, and the image light ML that has passed through the projection optical system 12 is directly incident on the see-through mirror 23. The reflective polarizing film 23a of the see-through mirror 23 may be a hologram mirror.

[0048] Fifth embodiment Hereinafter, a virtual image display device according to a fifth embodiment of the present invention will be described. The virtual image display device of the fifth embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of common parts will be omitted.

[0049] 15, the virtual image display device 100 of the fifth embodiment has a rotation mechanism 70 that rotates the polarizing filter 30 around the Z axis. The rotation axis of the polarizing filter 30 is set perpendicular to the tangent plane at the center of the polarizing filter 30. By adjusting the rotation angle of the polarizing filter 30, the angular relationship between the transmission axis of the reflective polarizing film 23a and the transmission axis of the transmissive polarizing film 30a can be adjusted, and the transmittance of the polarizing filter 30 for external light OL can be adjusted.

[0050] [Variations and Others] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments and can be embodied in various forms without departing from the spirit of the present invention. For example, the following modifications are also possible.

[0051] A depolarizing film may be provided on the outside-side surface of the polarizing filter 30. In this case, even if a display using polarized light exists on the outside side and the absorption axis of the transmissive polarizing film 30a coincides with the polarization direction of the display light of such a display, it becomes possible to view the display content of this type of display through the virtual image display 100.

[0052] The transmission polarizing film 30a of the polarizing filter 30 is not limited to one having an overall uniform extinction ratio characteristic, and may have a distribution pattern of the extinction ratio.

[0053] In the above description, it is assumed that the virtual image display device 100 is used by being mounted on the head, but the virtual image display device 100 can also be used as a handheld display that is not mounted on the head and is peered at like binoculars. In other words, in the present invention, the head mounted display also includes a handheld display.

[0054] In a specific embodiment, the virtual image display device includes an image light generating device, a projection optical system into which image light from the image light generating device is incident, and a partially transmitting mirror that partially reflects the image light from the projection optical system toward a pupil position, and a transmissive polarizer is arranged outside the partially transmitting mirror.

[0055] In the virtual image display device, a transmissive polarizer is disposed outside the partial transmission mirror, and the transmissive polarizer allows polarized light in a specific direction of the outside light to pass through the partial transmission mirror and enter the pupil position, while suppressing the reflection of polarized light in a specific direction or a direction perpendicular thereto, thereby preventing an outside light pattern from being reflected on the surface of the partial transmission mirror and appearing to sparkle. This makes it possible to prevent an uncomfortable appearance when the virtual image display device is worn, while facilitating eye contact.

[0056] In a specific aspect, the partial transmission mirror has a reflective polarizer, and a transmission polarizer whose transmission axis coincides with that of the reflective polarizer is arranged outside the reflective polarizer. In this case, the partial transmission mirror can transmit polarized light in a specific direction out of the outside light without loss.

[0057] In a specific aspect, a cover member having a transmission polarizing film provided thereon as a transmission polarizer is provided on the outer side of the partial transmission mirror. In this case, a cover member that also functions as a support for the transmission polarizing film is provided separately from the partial transmission mirror on the outer side of the partial transmission mirror.

[0058] In a specific aspect, in the partial transmission mirror, the reflective polarizer is a reflective polarizing film provided on the inside of the base material, and the transmission polarizer is a transmission polarizing film attached to the outside of the base material. In this case, the partial transmission mirror and the transmission polarizer are integrated, and the structure of the virtual image display device can be simplified.

[0059] In a specific aspect, the partial transmission mirror has a semi-transmitting mirror film, and a λ / 4 wave plate is disposed between the semi-transmitting mirror film and the transmission polarizer. In this case, the transmission polarizer and the λ / 4 wave plate function as a circular polarizing filter, and even if external light is incident on the partial transmission mirror via the transmission polarizer, the reflected light reflected by the partial transmission mirror and traveling backward is prevented from passing through the transmission polarizer.

[0060] In a specific aspect, the transmission polarizer is a transmission polarizing film attached to the outside of the λ / 4 wave plate. In this case, the partial transmission mirror, the λ / 4 wave plate, and the transmission polarizer are integrated, and the structure of the virtual image display device can be simplified.

[0061] In a specific aspect, the transmission axis of the transmission polarizer extends in the vertical direction. In this case, when there is a lot of horizontal polarization, such as light reflected from the surface of water, it is possible to effectively prevent the partial transmission mirror from sparkling.

[0062] In a specific aspect, the partially transmitting mirror is a concave mirror. In this case, the image formed on the image light generating device or the image re-imaged by the projection optical system can be viewed as an enlarged image by the concave mirror.

[0063] In a specific aspect, the projection optical system includes a first optical member and a second optical member that reflects image light from the first optical member. In this case, the optical system can be easily made compact by folding the optical path by reflection.

[0064] In a specific aspect, the partially transmitting mirror reflects the image light so that the optical axis is directed upward at a predetermined angle. In this case, the projection direction of the virtual image can be set downward in response to the fact that the line of sight of the human eye is stabilized in a state where the human eye is slightly downcast. [Explanation of symbols]

[0065] 11...display element, 12...projection optical system, 20...imaging optical system, 21...projection lens, 23...see-through mirror, 23a...reflective polarizing film, 23c...reflective surface, 23o...outer surface, 23p...reflective polarizer, 23r...semi-transmissive mirror film, 30...polarizing filter, 30a...transmissive polarizing film, 30i...inner surface, 30p...transmissive polarizer, 40...half mirror, 70...rotation mechanism, 88...display control device, 100...virtual image display device, 100C...support device, 102...display drive unit, 103...combiner, 104...cover member, 123, 223, 323...partially transmitting mirror, 323r...semi-transmissive mirror film, 334...lambda / 4 wave plate, AX...optical axis, EY...eye, ML...image light, OL...external light, OS...off-axis optical system, P1, P2, P3...optical path, PP...pupil position

Claims

1. an image light generating device; a projection optical system into which the image light from the image light generating device is incident; a partially transmitting mirror that partially reflects the image light from the projection optical system toward a pupil position; 、 Equipped with A transmission polarizer is disposed on the outer side of the partially transmitting mirror. Virtual image display device.

2. the partially transmitting mirror has a reflective polarizer; A transmission type polarizer whose transmission axis coincides with that of the reflection type polarizer is disposed outside the reflection type polarizer. The virtual image display device according to claim 1 .

3. A cover portion provided with a transmission polarizing film as the transmission polarizer on the outer side of the partial transmission mirror. The virtual image display device according to claim 2 , comprising a material.

4. In the partially transmitting mirror, the reflective polarizer is a reflective polarizer provided on the inner side of a substrate. The transmission polarizer is a transmission polarizing film attached to the outer side of the substrate. The virtual image display device according to claim 2 .

5. the partially transmitting mirror has a semi-transmitting mirror film; a λ / 4 wave plate is disposed between the semi-transmissive mirror film and the transmissive polarizer. Item 2. The virtual image display device according to item 1.

6. The transmission polarizer is a transmission polarizing film attached to the outer side of the λ / 4 wave plate. The virtual image display device according to claim 5 .

7. The transmission axis of the transmission polarizer extends in a vertical direction according to any one of claims 1 to 6. Virtual image display device.

8. The virtual image according to any one of claims 1 to 6, wherein the partially transmitting mirror is a concave mirror. Display device.

9. The projection optical system includes a first optical member and a second optical member that reflects the image light from the first optical member.

7. The virtual image display device according to claim 1, further comprising an optical member.

10. The partially transmitting mirror reflects the image light so that the optical axis is directed upward at a predetermined angle. The virtual image display device according to any one of claims 1 to 6.

Images