Virtual image display device and optical unit

Abstract

To prevent an optical system from becoming large overall. [Solution] A direct virtual image type virtual image display device 100A comprises a display element 11, a first lens 30 onto which image light ML from the display element 11 is incident, a first prism 41 onto which image light ML that has passed through the first lens 30 is incident, a second prism 42 joined to the first prism 41, an inclined mirror portion IM provided at the joint between the first prism 41 and the second prism 42 and reflecting at least a portion of the image light ML guided in the first prism 41, a plano-convex second lens 53 arranged opposite the first outer surface 41c of the first prism 41, and a transmissive mirror 56 formed on the convex surface 53g of the second lens 53 and partially reflecting the image light ML, and the second prism 42 has a polarization absorbing member AP on any surface except the second outer surface 42c facing the outside world.

Description

[Technical Field]

[0001] The present invention relates to a virtual image display device and an optical unit that enable viewing of a virtual image. [Background technology]

[0002] A head-mounted display comprising a display device, a projection optical member, a prism member, and a focusing reflective surface, in which image light from the projection optical member enters a first prism of the prism member, is totally reflected by the outer surface, is partially reflected by a semi-transmissive reflective surface formed at the boundary between the first and second prisms of the prism member, then passes through the outer surface of the prism member, is reflected by the focusing reflective surface, is returned to the prism member, passes through the semi-transmissive reflective surface, and further passes through the inner surface facing the pupil, is known (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-08749 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described head-mounted display, an intermediate image is formed in the first prism, which increases the optical path length and causes the overall size of the optical system to increase. [Means for solving the problem]

[0005] A direct virtual image type virtual image display device according to one aspect of the present invention comprises a display element that emits image light, a first lens onto which the image light from the display element is incident, a first prism onto which the image light that has passed through the first lens is incident, a second prism that is joined to the first prism to form a parallel plate-shaped prism light-guiding member, an oblique mirror section that is provided at the joint between the first prism and the second prism and that reflects at least a portion of the image light guided in the first prism, a plano-convex second lens that is arranged opposite a first outer surface of the first prism onto which the image light reflected by the oblique mirror section is incident, and a transmissive mirror that is formed on the convex surface of the second lens and that partially reflects the image light reflected by the oblique mirror section toward the oblique mirror section, and the second prism has a polarization absorbing member on any surface except the second outer surface facing the outside world.

[0006] A direct virtual image type optical unit in one aspect of the present invention comprises a first lens onto which image light from a display element is incident, a first prism onto which the image light that has passed through the first lens is incident, a second prism that is joined to the first prism to form a parallel plate-shaped prism light-guiding member, an oblique mirror section that is provided at the joint between the first prism and the second prism and that reflects at least a portion of the image light guided in the first prism, a plano-convex second lens that is arranged opposite a first outer surface of the first prism onto which the image light reflected by the oblique mirror section is incident, and a transmissive mirror that is formed on the convex surface of the second lens and that partially reflects the image light reflected by the oblique mirror section toward the oblique mirror section, and the second prism has a polarization absorbing member on any surface except for the second outer surface facing the outside world. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an external view illustrating a state in which the virtual image display device of the first embodiment is used. [Figure 2] FIG. 2 is a side cross-sectional view illustrating the internal structure of one of the virtual image display devices. [Figure 3] FIG. 1 is a perspective view of a virtual image display device. [Figure 4] 3 is a diagram illustrating optical paths and the like of the virtual image display device shown in FIG. 2. FIG. [Figure 5]10A and 10B are diagrams illustrating optical paths and the like of a virtual image display device of a comparative example. [Figure 6] 3A to 3C are diagrams illustrating an example of the structure and assembly of a first display unit. [Figure 7] FIG. 10 is a side cross-sectional view illustrating a virtual image display device according to a second embodiment. [Figure 8] FIG. 8 is a perspective view of the first prism and the second prism shown in FIG. 7. [Figure 9] 8 is a diagram illustrating optical paths and the like of the virtual image display device shown in FIG. 7. FIG. [Figure 10] FIG. 10 is a side cross-sectional view illustrating a virtual image display device according to a third embodiment. [Figure 11] 11 is a diagram illustrating the optical paths and the like of the virtual image display device shown in FIG. [Figure 12] FIG. 10 is a side cross-sectional view illustrating a virtual image display device according to a fourth embodiment. [Figure 13] FIG. 13 is a perspective view of the virtual image display device shown in FIG. [Figure 14] FIG. 10 is a side cross-sectional view illustrating a virtual image display device according to a modified example. [Figure 15] 15 is a diagram illustrating optical paths and the like in the virtual image display device shown in FIG. 14. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] [First embodiment] Hereinafter, a first embodiment of a virtual image display device and the like according to the present invention will be described with reference to FIGS.

[0009] FIG. 1 is a diagram illustrating the wearing state of a head-mounted virtual image display device (hereinafter also referred to as a head-mounted display or HMD) 200. The HMD 200 allows an observer or wearer US wearing it to recognize an image as a virtual image. In FIG. 1 and other figures, X, Y, and Z are a Cartesian coordinate system. The +X direction corresponds to the horizontal direction in which the eyes EY of the observer or wearer US wearing the HMD 200 are aligned. The +Y direction corresponds to the upward direction perpendicular to the horizontal direction in which the eyes EY are aligned for the wearer US. The +Z direction corresponds to the forward or front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

[0010] The HMD 200 includes a first virtual image display device 100A for the right eye and a direct virtual image type, a second virtual image display device 100B for the left eye and a direct virtual image type, a pair of temple-shaped support devices 100C that support the virtual image display devices 100A and 100B, and a user terminal 90 that serves as an information terminal. The first virtual image display device 100A functions independently as an HMD and is composed of a first display driver 102a disposed at the top and a first combiner 103a shaped like a pair of glasses that covers the eyes. The second virtual image display device 100B similarly functions independently as an HMD and is composed of a second display driver 102b disposed at the top and a second combiner 103b shaped like a pair of glasses that covers the eyes. The support device 100C is a mounting member that is worn on the head of the wearer US. The support device 100C supports the upper ends of a pair of combiners 103a and 103b via display drive units 102a and 102b, which are integrated in appearance. The first virtual image display device 100A and the second virtual image display device 100B are optically identical or optically reversed. A detailed description of the second virtual image display device 100B will be omitted.

[0011] FIG. 2 is a side cross-sectional view illustrating the internal structure of the first virtual image display device 100A. FIG. 3 is a perspective view of the first virtual image display device 100A. The first virtual image display device 100A includes a first image forming element 11a, a first display unit 20a, and a first circuit member 80a. The first image forming element 11a is also referred to as a display element 11. The first display unit 20a is an imaging optical system IS that directly forms a virtual image without forming an intermediate image. The first display unit 20a is also referred to as a direct virtual image optical system DIS. The imaging optical system IS includes a first lens 30, a first flat-plate member 40, and a second flat-plate member 50. The first lens 30 functions as a protective glass that protects the display surface 11d of the display element 11. A cover glass may be provided between the display element 11 and the first lens 30. The first flat-plate member 40 guides the image light ML emitted from the display element 11 to the second lens 53 of the second flat-plate member 50. The second plate-shaped member 50 reflects the image light ML from the first plate-shaped member 40 toward the pupil position PP or the eye EY so as to partially return the image light ML to the first plate-shaped member 40, and allows external light OL to be incident on the pupil position PP via the first plate-shaped member 40. The first lens 30, the first plate-shaped member 40, and the second plate-shaped member 50 each function as a lens having positive refractive power.

[0012] Although detailed description will be omitted, the second virtual image display device 100B includes a second image forming element 11b, a second display unit 20b, and a second circuit member 80b. The second image forming element 11b is similar to the first image forming element 11a. The second display unit 20b is similar to the first display unit 20a. The second circuit member 80b is similar to the first circuit member 80a.

[0013] In the first virtual image display device 100A, the first image forming element 11a is a self-luminous image light generating device. The first image forming element 11a emits image light ML to the first flat plate-like member 40 via the first lens 30. The first image forming element 11a is housed and supported in a case 71. The first image forming element 11a is, for example, an organic EL (organic electroluminescence) display. The first image forming element 11a forms a color still image or moving image on a two-dimensional display surface 11d. The first image forming element 11a is driven by the first circuit member 80a to perform a display operation. The first image forming element 11a 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 first image forming element 11a is not limited to a self-luminous image light generating device, but 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. Instead of an LCD, LCOS (Liquid Crystal on Silicon, LCoS is a registered trademark) or the like may be used as the first image forming element 11a. In the first virtual image display device 100A, the optical device excluding the first circuit member 80a is referred to as an optical unit 100. The optical unit 100 includes a direct virtual image optical system and can be said to be a part corresponding to the direct virtual image optical system DIS constituting the first virtual image display device 100A.

[0014] The first display unit 20a includes a first lens 30, a first flat-plate member 40, an inclined mirror unit IM, and a second flat-plate member 50. In the first display unit 20a, the first lens 30 has positive refractive power and receives the image light ML from the first image-forming element 11a. The first lens 30 has a flat light-entering surface 30f bonded to the first image-forming element 11a and a convex light-exiting surface 30g. The light-exiting surface 30g is, for example, spherical, but can also be an aspherical surface with an axisymmetric shape. The first lens 30 can be divided into a parallel plate 31 and a lens unit 32. By ensuring that the parallel plate 31 has a predetermined thickness or more, foreign matter adhering to the surface of the first lens 30 becomes less noticeable. The parallel plate 31 functions as a cover glass. The lens unit 32 is a plano-convex lens with positive refractive power. The plano-convex lens has one surface that is flat and the other surface that is convex. The parallel plate 31 and the lens portion 32 may be bonded together or may be spaced apart. The lens portion 32 does not have to be a plano-convex lens, and may be, for example, a biconvex lens. The first lens 30 is made of, for example, fused silica, and has a relatively low refractive index.

[0015] The first flat-plate member 40 has a first prism 41 and a second prism 42, both of which are parallel flat plates. The first prism 41 and the second prism 42 are joined at inclined surfaces 41d and 42d. The first prism 41 and the second prism 42 joined together are called a prism light-guiding member 48. The prism light-guiding member 48 has the appearance of a parallel flat plate. A flat oblique mirror portion IM is formed on the first inclined surface 41d formed on the underside of the first prism 41. The combination of the prism light-guiding member 48 and a second flat-plate member 50, which will be described later, corresponds to a first combiner 103a.

[0016] The first prism 41 has a rectangular prism-like outer shape and a trapezoidal cross section. The first prism 41 guides the image light ML. The first prism 41 has an incident optical surface 41a, a first inner surface 41b, a first outer surface 41c, and a first inclined surface 41d. The first prism 41 also has an upper flat surface 40u and a first lateral surface 41e (see FIG. 3). The first lateral surface 41e corresponds to a part of the fifth lateral surface 40v of the prism light-guiding member 48. Here, the incident optical surface 41a is generally inclined downward in the front direction, and the optical axis passing through the incident optical surface 41a extends in a direction between the +Z direction, which is forward, and the +Y direction, which is upward. This makes it easier to arrange the first image forming element 11a, which is the display element 11, closer to the outside world than the first inner surface 41b, and makes it possible to adjust the angle at which the image light ML propagates in the first prism 41 (inside the first prism 41 or inside the first prism 41). The incident optical surface 41a is a convex surface, for example, a spherical surface, but it can also be an axially symmetric aspherical surface. The first prism 41 can be considered to have a lens portion 44 including the incident optical surface 41a. The lens portion 44 is a convex-plano lens with positive refractive power. The lens portion 44 may be formed directly on the first prism 41 or may be bonded to the first prism 41. The first inner surface 41b and the first outer surface 41c are parallel to each other and extend perpendicular to the optical axis AX between the pupil position PP. The first inner surface 41b and the first outer surface 41c internally reflect the image light ML (i.e., reflect it inside the object surface), but it is particularly desirable that they totally reflect the image light ML. The first inner surface 41b can be hard-coated to improve scratch resistance or abrasion resistance. The first inclined surface 41d is flat. The first inclined surface 41d forms an acute angle with the first outer surface 41c, specifically an angle of 25° to 32°. The distance between the optical axis AX passing through the pupil position PP and the upper end of the first lens 30 is approximately 20 mm. The first prism 41 is made of a resin material.

[0017] The number of reflections of the image light ML in the first prism 41 is once by the first inner surface 41b, once by the first outer surface 41c, and once by an inclined mirror portion IM, which will be described later. By setting the number of internal reflections of the image light ML in the first prism 41 to two, it is possible to increase the angle of view of the image light ML, the pupil position PP, or the aperture PPa, while avoiding the mixing of light that has been reflected a different number of times within the first prism 41. Furthermore, it becomes easy to shorten the distance from the display element 11 to the transmissive mirror 56 of the cover member 52, which will be described later, and it is possible to reduce the size of the prism light-guiding member 48, and it is also easy to reduce the size of the display element 11 and the first lens 30.

[0018] Like the first prism 41, the second prism 42 has a rectangular prism-like outer shape and a trapezoidal cross section. The second prism 42 transmits the image light ML. The second prism 42 has a second inner surface 42b, a second outer surface 42c, a second inclined surface 42d, and a first bottom surface 42f. The first bottom surface 42f corresponds to the fourth bottom surface 40w of the prism light-guiding member 48 or the first flat-plate-like member 40. The first bottom surface 42f is the surface of the prism light-guiding member 48 or the first flat-plate-like member 40 opposite to the incident optical surface 41a. The first bottom surface 42f is the surface of the second prism 42 opposite to the second inclined surface 42d. The second prism 42 also has a second horizontal side surface 42e (see FIG. 3). The second lateral side surface 42e corresponds to a part of the fifth lateral side surface 40v of the prism light-guiding member 48. The second inner side surface 42b and the second outer side surface 42c are parallel to each other and extend perpendicular to the optical axis AX between the pupil position PP. The second inner side surface 42b can be hard-coated to improve scratch resistance. The second prism 42 is formed of a resin material.

[0019] The second prism 42 has a polarization absorbing member AP on any surface thereof except the second outer surface 42c on the outside world side. This suppresses see-through ghosts, which are external light ghosts caused by unwanted external light OL2. The surfaces other than the second outer surface 42c on the outside world side are specifically the second inner surface 42b, the second inclined surface 42d, the second lateral surface 42e, and the first bottom surface 42f. The second inner surface 42b, the second lateral surface 42e, and the first bottom surface 42f are exposed surfaces of the second prism 42 or the prism light-guiding member 48. The second inclined surface 42d is a non-exposed surface of the second prism 42 or the prism light-guiding member 48 that faces the inclined mirror unit IM. The unwanted external light OL2 is external light from an unintended direction, and is light incident from a direction other than the front of the first virtual image display device 100A, i.e., from a direction other than the external-world-facing surface of the second flat-plate-shaped member 50. As will be described in detail later, the unwanted outside light OL2 appears in the field of view as a see-through ghost, which may significantly impair visibility. The polarization absorption member AP is disposed in an appropriate position in the second prism 42, thereby absorbing or blocking a predetermined polarization of the unwanted outside light OL2 and suppressing the effects of the unwanted outside light OL2.

[0020] In this embodiment, the polarization absorption member AP is disposed on the first bottom surface 42f of the second prism 42. That is, the polarization absorption member AP is provided on the first bottom surface 42f of the second prism 42. Unwanted external light OL2 incident from the front diagonally downward side of the second prism 42 or the prism light-guiding member 48 passes through the polarization absorption member AP before entering the diagonal mirror portion IM, thereby suppressing reflection at the diagonal mirror portion IM. This prevents the unwanted external light OL2 from reaching the eye EY of the wearer US. As shown in FIG. 2 and other figures, the polarization absorption member AP is more preferably disposed on the first bottom surface 42f of the second prism 42, the second bottom surface 51f of the quarter-wave plate 51, and the third bottom surface 52f of the cover member 52 including the second lens 53 and the transmissive mirror 56. The second bottom surface 51f and the third bottom surface 52f correspond to the fifth bottom surface 50w of the second flat-plate-shaped member 50. That is, the polarization absorption member AP is disposed across the bottom surfaces 40w, 50w of the first flat plate member 40 and the second flat plate member 50. This makes it possible to further suppress see-through ghosts.

[0021] 3, the second prism 42 has a curved surface 42g at the boundary between the first bottom surface 42f and the second lateral side surface 42e. The polarization absorption member AP preferably extends from the first bottom surface 42f to the curved surface 42g. In other words, the polarization absorption member AP extends to the rounded portion of the boundary between the first bottom surface 42f and the second lateral side surface 42e of the second prism 42. Note that the curved surface 42g is also included in the second lateral side surface 42e. In this case, it can be said that the polarization absorption member AP is provided on the first bottom surface 42f and part of the second lateral side surface 42e.

[0022] The polarization absorbing member AP is an absorptive polarizer APm. The absorptive polarizer APm is a uniaxially stretched polarizer. The surface on which the polarization absorbing member AP is provided does not glare when viewed from the outside. The transmission axis of the polarization absorbing member AP is parallel or approximately parallel to the transmission axis of the polarization splitting film 45 of the inclined mirror unit IM, which will be described later. In other words, the transmission axis of the polarization absorbing member AP coincides or approximately coincides with the transmission axis of the polarization splitting film 45. The transmission axis is a polarization axis that transmits only light vibrating in a specific direction. Furthermore, approximately parallel or approximately coincident means that the deviation of the transmission axes is within 2° to 3°. When the unwanted outside light OL2 passes through the polarization absorbing member AP, the same polarized light as the polarized light reflected by the polarization splitting film 45 is absorbed. The remaining polarized light of the unwanted outside light OL2 that passes through the polarization absorbing member AP is transmitted by the polarization splitting film 45 even if reflected within the second prism 42, and reflection of the unwanted outside light OL2 is suppressed. This prevents unwanted external light OL2 from reaching the eye EY of the wearer US, thereby providing a good field of vision. Since the unwanted external light OL2 entering from the lower side of the prism light-guiding member 48 is significantly affected by see-through ghosts, the polarization absorption member AP is provided on the first bottom surface 42f of the second prism 42, as described above.

[0023] In this embodiment, the polarization absorbing member AP is, for example, a resin member that absorbs or blocks s-polarized light PLs. The polarization absorbing member AP is partially transparent to unwanted external light OL2 by transmitting, for example, p-polarized light PLp. The transmittance of the polarization absorbing member AP is, for example, 40% to 50%. When the transmittance is 40% to 50%, it is possible to ensure a certain degree of see-through property for the surface on which the polarization absorbing member AP is provided. The thickness of the polarization absorbing member AP is, for example, about 0.1 mm. The polarization absorbing member AP may be attached to a substrate with a thickness of, for example, about 1 mm, or may be a film-like member. A hard coat and an anti-reflection film may be applied to the surface of the polarization absorbing member AP.

[0024] When the polarization-absorbing member AP is disposed on the fourth bottom surface 40w of the first flat-plate member 40 and the fifth bottom surface 50w of the second flat-plate member 50, the polarization-absorbing member AP is attached after the first flat-plate member 40 and the second flat-plate member 50 are assembled, with the transmission axis thereof adjusted. At this time, it is preferable to avoid creating a step in the polarization-absorbing member AP. When the polarization-absorbing member AP is disposed only on the fourth bottom surface 40w of the first flat-plate member 40, the polarization-absorbing member AP is attached after the transmission axis thereof is adjusted either before or after the first flat-plate member 40 and the second flat-plate member 50 are assembled. When attaching the polarization-absorbing member AP, an adhesive, a pressure-sensitive adhesive film, or the like can be used.

[0025] The inclined mirror portion IM reflects at least a portion of the image light ML guided through the first prism 41. The inclined mirror portion IM is integrally formed on the first slope 41d of the first prism 41 and is sandwiched between the first slope 41d of the first prism 41 and the second slope 42d of the second prism 42. A bonding adhesive CT is filled between the inclined mirror portion IM and the second slope 42d. The inclined mirror portion IM and the second slope 42d may be bonded not only with the adhesive CT but also with an adhesive film or the like. In this embodiment, the inclined mirror portion IM is a polarization separation film 45. The polarization separation film 45 is, for example, a polarization beam splitter having s-polarized light reflection characteristics. The polarization separation film 45 is formed, for example, of a dielectric multilayer film. When the image light ML contains s-polarized light PLs, the polarization separation film 45 efficiently reflects the s-polarized image light ML. When the image light ML contains p-polarized light PLp, the polarization separation film 45 efficiently transmits the p-polarized image light ML. The polarization separation film 45 may be any film that selectively reflects the image light ML according to the polarization direction, and may be, for example, a multilayer film, a wire grid type polarizer such as a wire grid film, or a reflective polarization element that utilizes film stretching.

[0026] The polarization splitting film 45 may transmit s-polarized light PLs and reflect p-polarized light PLp.

[0027] The inclined mirror portion IM may have a flat surface that does not affect image formation. The inclined mirror portion IM may also have a slightly convex or concave curved surface that does not affect image formation. The space between the inclined mirror portion IM and the first inclined surface 41d may be filled with a light-transmitting filler instead of adhesive CT. In this case, the first prism 41 and the second prism 42 may be supported from the outside by a support member or the like to maintain their bonded state. The inclined mirror portion IM may also be integrally formed on the second inclined surface 42d of the second prism 42, instead of on the first inclined surface 41d of the first prism 41. The scratch or abrasion resistance of the inclined mirror portion IM can be enhanced by applying a hard coating to the surface.

[0028] The second flat member 50 has a thin quarter-wave plate 51 and a cover member 52. The quarter-wave plate 51 is a crystal or the like having an optical axis between the X direction and the Y direction. The quarter-wave plate 51 converts the s-polarized light PLs reflected by the polarization separation film 45 into circularly polarized light PLc, and converts the circularly polarized light PLc reflected by the cover member 52 into p-polarized light PLp. The cover member 52 has a plano-convex second lens 53, a concave-plano compensating lens 54, a compensating plate 55 provided around the compensating lens 54 and extending parallel to the prism light-guiding member 48, and a transmissive mirror 56.

[0029] The second flat plate-shaped member 50 is disposed at a distance of approximately 20 μm to 50 μm from the first flat plate-shaped member 40. The first and second outer surfaces 41 c, 42 c of the first flat plate-shaped member 40 and the third inner surface 50 c of the second flat plate-shaped member 50 may be slightly curved, potentially forming a small step at the boundary between the first and second outer surfaces 41 c, 42 c. However, by setting the distance between the first and second outer surfaces 41 c, 42 c and the third inner surface 50 c to 20 μm or more, more preferably 30 μm or more, these surfaces can be prevented from being excessively close to each other. Conversely, by setting the distance between the first and second outer surfaces 41 c, 42 c and the third inner surface 50 c to 50 μm or less, an increase in the thickness of the first combiner 103 a formed by combining the first flat plate-shaped member 40 and the second flat plate-shaped member 50 can be prevented. A spacer 61 is provided between the first and second outer surfaces 41c, 42c of the first flat plate member 40 and the third inner surface 50c of the second flat plate member 50 to adjust the gap between the first flat plate member 40 and the second flat plate member 50 and fix them in a mutually positioned state. The spacer 61 is not provided around the entire periphery of the second flat plate member 50. In other words, the gap SP between the first flat plate member 40 and the second flat plate member 50 is not sealed and is in communication with the outside world.

[0030] In the cover member 52, the second lens 53 condenses the image light ML. The second lens 53 is a thin plano-convex lens having positive refractive power. A plano-convex or plano-convex lens has one surface that is flat and the other surface that is convex outward. The second lens 53 has a flat surface 53f bonded to the quarter-wave plate 51 and a convex surface 53g that faces the compensation lens 54. The convex surface 53g is, for example, a spherical surface, but can also be an axially symmetric aspherical surface. The convex surface 53g has a circular shape in a planar view. The compensation lens 54 is thin but has positive refractive power. The compensation lens 54 has a concave surface 54f that faces the second lens 53 and a flat surface 54g. The compensation plate 55 is a parallel plate. The compensation plate 55 has a pair of flat surfaces 55f and 55g. Here, the concave surface 54f of the compensating plate 55 has the same shape as the convex surface 53g of the second lens 53. The flat surface 54g of the compensating lens 54 and the flat surface 55g of the compensating plate 55 are coplanar and continuous. The transmissive mirror 56 is a thin film formed on the convex surface 53g of the second lens 53, and has the same shape as the convex surface 53g. The combination of the second lens 53 and the transmissive mirror 56 is called the light-collecting reflector CR.

[0031] The second lens 53, the compensation lens 54, and the compensation plate 55 are formed from a resin material and have the same refractive index. The refractive index of the second lens 53 etc. is lower than the refractive index of the first prism 41. The compensation lens 54 and the compensation plate 55 are an optical element 58 integrally formed from the same resin material.

[0032] The combination of the second lens 53, the compensating lens 54, and the compensating plate 55 functions as a parallel plate. In other words, external light OL incident on the compensating lens 54 or the compensating plate 55 passes through them without being affected by the lens action of the compensating lens 54 or the like or by steps present at the outer edge of the compensating lens 54. In this way, the compensating lens 54 optically compensates for the effect of the second lens 53 on the external light OL. In this sense, the plane 53f of the second lens 53, the plane 54g of the compensating lens 54, and the planes 55f and 55g of the compensating plate 55 are not necessarily limited to strict flat surfaces. For example, they may be approximately flat, or may include curved surfaces partially or entirely. Furthermore, the plane 53f of the second lens 53, the plane 54g of the compensating lens 54, and the planes 55f and 55g of the compensating plate 55 may include curved surfaces for correcting the vision of the wearer US or for design purposes such as sunglasses or fashion glasses, as long as such curved surfaces do not cause any inconvenience in terms of optical performance. The flat surfaces 54g, 55g of the compensating lens 54 and the compensating plate 55 may be coated with an anti-reflection film or a hard coat. The external light OL passing through the compensating plate 55 passes above, below, left, and right of the compensating lens 54. This external light OL is incident from a peripheral region outside the incident region of the image light ML corresponding to the compensating lens 54, that is, from the compensating plate 55. This ensures a wide see-through field of view of the outside world. The field of view of the external light OL is set to, for example, approximately 40° upward and approximately 40° downward.

[0033] The transmissive mirror 56 is a half mirror. The transmissive mirror 56 partially reflects the image light ML that has passed through the second lens 53 and partially transmits the external light OL. The transmissive mirror 56 reflects the image light ML that has been reflected by the inclined mirror portion IM of the first flat plate member 40 or the polarization separation film 45 and passed through the quarter-wave plate 51 and the second lens 53 toward the pupil position PP. The transmissive mirror 56 is a concave mirror that covers the pupil position PP where the eye EY or pupil is located and has a concave shape toward the pupil position PP and a convex shape toward the outside world. The pupil position PP or its opening PPa is called the eyepoint or eyebox and corresponds to the exit pupil EP of the first display unit 20a.

[0034] The transmissive mirror 56 transmits a portion of the external light OL, enabling a see-through view of the external world and superimposing a virtual image on an external image. In this case, the external light OL passes through the first and second flat-plate members 40 and 50, but the flat-plate members 40 and 50 do not act as a lens on the external light OL. The reflectance of the transmissive mirror 56 for the image light ML and the external light OL is set to 10% to 50% within the expected range of incident angles of the image light ML, in order to ensure the brightness of the image light ML and facilitate the observation of the external image via see-through. The transmissive mirror 56 is formed, for example, by a dielectric multilayer film consisting of multiple dielectric layers with adjusted thicknesses. The transmissive mirror 56 may also be a single-layer or multilayer film of a metal, such as Al or Ag, with adjusted thicknesses. The transmissive mirror 56 is formed, for example, by lamination using vapor deposition.

[0035] In the first virtual image display device 100A, the first lens 30, the lens unit 44, the second lens 53, and the transmissive mirror 56 each have a positive refractive power and tend to converge divergent light. The first lens 30, the lens unit 44, the second lens 53, and the transmissive mirror 56, together with the main body of the first prism 41 and the second prism 42, function as an imaging optical system IS, similar to a simple microscope, that forms an erect image, or a direct virtual image optical system DIS. This allows a virtual image to be formed by projecting a real image formed on the display surface 11d of the first image forming element 11a, for example, at infinity, or a virtual image to be formed by projecting a real image formed on the display surface 11d several meters away. Adjusting the refractive powers of the first lens 30, the lens unit 44, the second lens 53, and the transmissive mirror 56 shortens the focal length of the imaging optical system IS, thereby achieving a desired magnification ratio.

[0036] 3, the vertical dimension ay of the first flat plate-shaped member 40 or the second flat plate-shaped member 50 is, for example, 34 mm, and the horizontal dimension ax is, for example, 40 mm. The thickness az of the first flat plate-shaped member 40 in the front-rear direction is, for example, about 7 mm to 8 mm, and the combined thickness of the first flat plate-shaped member 40 and the second flat plate-shaped member 50 is kept to about 7.5 mm to 8.5 mm. The first flat plate-shaped member 40 has upper flat surfaces 40u on the left and right of the incident optical surface 41a. The upper flat surface 40u is a surface that does not allow light to enter. To prevent stray light, a light shielding material (not shown) may be disposed on the upper flat surface 40u so as to face and cover it, or a light shielding material may be applied to the upper flat surface 40u.

[0037] FIG. 4 is a diagram illustrating the optical path and the like of the first virtual image display device 100A. As shown in FIG. 4, the image light ML from the first image forming element 11a passes through the first lens 30 and enters the first prism 41. At this time, the degree of divergence of the image light ML is suppressed due to the positive refractive power of the first lens 30 and the lens unit 44. In the optical path passing through the first prism 41, the image light ML is sequentially reflected by the first inner surface 41b and the first outer surface 41c of the first prism 41 without forming an intermediate image (see FIG. 2), and the s-polarized light PLs of the image light ML is reflected by the polarization separation film 45. The s-polarized light PLs of the image light ML reflected by the polarization separation film 45 is transmitted through the first outer surface 41c of the first prism 41 and passes through the quarter-wave plate 51 of the second flat plate-like member 50, becoming circularly polarized light PLc, and then entering the second lens 53 and the transmissive mirror 56. A portion of the circularly polarized image light ML incident on the transmissive mirror 56 passes through the second lens 53, is reflected by the transmissive mirror 56, and passes through the quarter-wave plate 51 again in a collimated state. As a result, the image light ML passing through the quarter-wave plate 51 becomes p-polarized light PLp and enters the first prism 41 from the first outer surface 41c, transmits through the polarization separation film 45, and is emitted to the outside of the second prism 42 via the second inner surface 42b. The image light ML emitted to the outside of the second prism 42 is incident on a pupil position PP where the eye EY or pupil of the wearer US is located (see FIG. 2). Not only the image light ML reflected by the transmissive mirror 56, but also external light OL transmitted through the transmissive mirror 56 and the external light OL transmitted through the compensation plate 55 are incident on the pupil position PP. In other words, the wearer US wearing the first virtual image display device 100A can observe a virtual image formed by the image light ML superimposed on an external image.

[0038] In this embodiment, when unwanted outside light OL2 that causes see-through ghosts enters the second prism 42 from the first bottom surface 42f of the second prism 42, the s-polarized light PLs is absorbed by the polarization absorption member AP, and only p-polarized light PLp enters. The p-polarized light PLp of the unwanted outside light OL2 is then reflected by the second inner surface 42b of the second prism 42 and reaches the polarization separation film 45, but is not reflected by the polarization separation film 45. Therefore, the unwanted outside light OL2 does not reach the eye EY of the wearer US and does not cause see-through ghosts. This allows the wearer US to have a good field of vision.

[0039] Fig. 5 is a diagram illustrating the optical paths and the like of the virtual image display device of the comparative example. As shown in Fig. 5, in the virtual image display device of the comparative example, unwanted external light OL2 from an unintended direction, specifically, unwanted external light OL2 incident on the prism light-guiding member 48 from the lower side, the inside (pupil position PP side), and the sides of the prism light-guiding member 48, is reflected within the prism light-guiding member 48 and reaches the eye EY of the wearer US. As a result, the unwanted external light OL2 is reflected in the field of view as a see-through ghost, which may impair visibility.

[0040] Specifically, as shown in FIG. 5 , unwanted outside light OL2 incident from the lower side of the prism light-guiding member 48, i.e., from the first bottom surface 42f of the second prism 42, is reflected within the second prism 42 and reaches the polarization separation film 45. S-polarized light PLs of the unwanted outside light OL2 incident on the polarization separation film 45 is reflected by the polarization separation film 45 and reaches the eye EY of the wearer US. In this case, the wearer US sees a see-through ghost in which the wearer's feet and the floor are reflected in the front of their field of vision. Similarly, for unwanted outside light OL2 incident from the inside of the prism light-guiding member 48, i.e., from the second inner surface 42b of the second prism 42, s-polarized light PLs of the unwanted outside light OL2 is reflected by the polarization separation film 45 and reaches the eye EY of the wearer US. In this case, the wearer US sees a see-through ghost in which the wearer US himself is reflected in the front of his field of vision. In this embodiment, in particular, by providing the polarization absorption member AP on the first bottom surface 42f of the second prism 42, it is possible to suppress unwanted external light OL2 from the diagonally downward front side, which is greatly affected by see-through ghosts.

[0041] FIG. 6 is a diagram illustrating an example of the structure and assembly of the first display unit 20a constituting the first virtual image display device 100A. In FIG. 6, areas AR1 to AR5 are perspective views illustrating the assembly process of the first display unit 20a. First, as shown in area AR1, a first prism 41 and a second prism 42 are prepared. The first prism 41 and the second prism 42 are formed, for example, by injection molding of resin. The first prism 41 is formed with an incident optical surface 41a, a first inner surface 41b, a first outer surface 41c, a first inclined surface 41d, a first lateral surface 41e, an upper flat surface 40u, etc. The second prism 42 is formed with a second inner surface 42b, a second outer surface 42c, a second inclined surface 42d, a second lateral surface 42e, a first bottom surface 42f (or a fourth bottom surface 40w), etc. A polarization separation film 45 serving as an inclined mirror portion IM is formed on the first inclined surface 41d of the first prism 41 by vacuum deposition or other techniques. As shown in region AR2, the first prism 41 and the second prism 42 are joined at their inclined surfaces 41d and 42d to obtain a prism light-guiding member 48 or a first flat plate-like member 40. Next, as shown in region AR3, a quarter-wave plate 51 is attached to the outer surfaces 41c and 42c of the first flat plate-like member 40 so as to face the outer surfaces 41c and 42c. At this time, a pair of spacers 61 made of thin adhesive are disposed between the outer surfaces 41c and 42c of the first flat plate-like member 40 and the quarter-wave plate 51, forming a gap SP between the outer surfaces 41c and 42c of the first flat plate-like member 40 and the quarter-wave plate 51. As shown in region AR4, a second lens 53 is attached at an appropriate position on the surface of the quarter-wave plate 51. A transmissive mirror 56 is formed on the surface of the second lens 53. Next, as shown in area AR5, the optical element 58 is bonded to the quarter-wave plate 51 and the like. At this time, the compensation lens 54 and the second lens 53 of the optical element 58 are positioned, fitted, and bonded together. In addition, the compensation plate 55 of the optical element 58 and the quarter-wave plate 51 are bonded together. This completes the assembly of the first flat-plate member 40 and the second flat-plate member 50 of the first display unit 20a. After the assembly is complete, the polarization absorbing member AP is attached so as to straddle the bottom surfaces 40w, 50w of the first flat-plate member 40 and the second flat-plate member 50.

[0042] In the above description, the first display unit 20a is produced by assembling the second flat plate-shaped member 50 on the first flat plate-shaped member 40, but the first flat plate-shaped member 40 and the second flat plate-shaped member 50 may be assembled separately, and then the first flat plate-shaped member 40 and the second flat plate-shaped member 50 may be joined together at the end.

[0043] The polarization absorption member AP may be attached to each component, specifically, the first bottom surface 42f of the second prism 42, the second bottom surface 51f of the quarter-wave plate 51, and the third bottom surface 52f of the cover member 52, before assembling the first display unit 20a. Alternatively, the polarization absorption member AP may be attached only to the first bottom surface 42f of the second prism 42.

[0044] The direct virtual image type virtual image display devices 100A, 100B or the optical unit 100 of the first embodiment described above includes a display element 11 that emits image light ML, a first lens 30 onto which the image light ML from the display element 11 is incident, a first prism 41 onto which the image light ML that has passed through the first lens 30 is incident, a second prism 42 that is joined to the first prism 41 to form a parallel plate-shaped prism light-guiding member 48, and a second prism 42 that is provided at the joint between the first prism 41 and the second prism 42 and that guides the light in the first prism 41. the first prism 41 includes an inclined mirror portion IM that reflects at least a portion of the image light ML reflected by the inclined mirror portion IM; a plano-convex second lens 53 that is arranged opposite the first outer surface 41c of the first prism 41 onto which the image light ML reflected by the inclined mirror portion IM is incident; and a transmissive mirror 56 that is formed on the convex surface 53g of the second lens 53 and that partially reflects the image light ML reflected by the inclined mirror portion IM toward the inclined mirror portion IM, and the second prism 41 has a polarization absorbing member AP on any surface except the second outer surface 42c on the outside world side.

[0045] In the virtual image display devices 100A, 100B or the optical unit 100, in order to form a virtual image directly without forming an intermediate image, the first lens 30, the second lens 53, and the transmissive mirror 56 ensure refractive power, thereby ensuring a magnification while suppressing an increase in the optical path length and avoiding an increase in the size of the optical system. In addition, by allowing the unwanted external light OL2 that causes see-through ghosts to pass through the polarization absorbing member AP of the second prism 42, the see-through property of the field of view of the wearer US is ensured, and the see-through ghosts can be effectively suppressed, resulting in a good field of view.

[0046] Second Embodiment The virtual image display device of the second embodiment will be described below. 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 parts common to the virtual image display device of the first embodiment will be omitted.

[0047] 7 and 8, in this embodiment, the polarization absorption member AP is disposed on the second inclined surface 42d of the second prism 42 facing the inclined mirror portion IM, closer to the second inner surface 42b, opposite the second outer surface 42c, with respect to the polarization separation film 45 of the inclined mirror portion IM. In other words, the polarization absorption member AP is provided on the second inclined surface 42d of the second prism 42, on the wearer US side or the observation side of the inclined mirror portion IM. As a result, unwanted external light OL2 passes through the polarization absorption member AP before entering the inclined mirror portion IM, and reflection at the inclined mirror portion IM is suppressed. Therefore, it is possible to prevent the unwanted external light OL2 from reaching the eye EY of the wearer US.

[0048] Before assembling the first prism 41 and the second prism 42, the polarization absorption member AP is attached to the second inclined surface 42d of the second prism 42 after adjusting the transmission axis. Note that the polarization absorption member AP may also be attached to the surface of the polarization separation film 45 of the inclined mirror portion IM of the first inclined surface 41d of the first prism 41 after adjusting the transmission axis.

[0049] As shown in FIG. 9 , in the virtual image display device 100A of this embodiment, the unwanted external light OL2 that causes see-through ghosts enters the first bottom surface 42f or the second inner surface 42b of the second prism 42. The unwanted external light OL2 enters the second prism 42 from the first bottom surface 42f or the second inner surface 42b. Immediately before entering the polarization separation film 45, i.e., when entering the second prism 42 from the first bottom surface 42f or the second inner surface 42b of the second prism 42, the s-polarized light PLs is absorbed by the polarization absorption member AP, and only the p-polarized light PLp enters. The p-polarized light PLp of the unwanted external light OL2 is reflected within the second prism 42 and reaches the polarization separation film 45, but is not reflected by the polarization separation film 45. Therefore, the unwanted external light OL2 does not reach the eye EY of the wearer US, and does not cause see-through ghosts. This allows the wearer US to obtain a good field of vision.

[0050] Third Embodiment The virtual image display device of the third embodiment will be described below. Note that 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 parts common to the virtual image display device of the first embodiment will be omitted.

[0051] As shown in FIG. 10 , in this embodiment, the polarization absorption member AP is disposed on the second inner surface 42b opposite the second outer surface 42c of the second prism 42. That is, the polarization absorption member AP is provided on the second inner surface 42b of the second prism 42. As a result, unwanted external light OL2 incident from the second inner surface 42b of the second prism 42 passes through the polarization absorption member AP before entering the inclined mirror portion IM, thereby suppressing reflection at the inclined mirror portion IM. This prevents the unwanted external light OL2 from reaching the eye EY of the wearer US. Also, as shown in FIG. 10 , the polarization absorption member AP may be disposed across the first inner surface 41b opposite the first outer surface 41c of the first prism 41. That is, the polarization absorption member AP may be provided on the entire inner surfaces 41b, 42b of the prism light-guiding member 48. This also reduces the influence of unwanted external light OL2 incident from the first inner surface 41b of the first prism 41. In the first prism 41, the polarization absorption member AP is disposed on the first inner surface 41b via an air layer AL. Even if the polarization absorption member AP is provided in the first prism 41, the air layer AL is interposed between the first prism 41 and the polarization absorption member AP, so the reflection of the image light ML within the first prism 41 is not hindered, and the image light ML is totally reflected within the first prism 41. This prevents the image light ML from being incident on the polarization absorption member AP. As a result, the polarization of the image light ML reflected back by the polarization separation film 45, specifically the s-polarized light PLs, is prevented from being absorbed by the polarization absorption member AP, preventing the image from becoming invisible.

[0052] When the polarization absorbing member AP is provided only on the second inner surface 42b of the second prism 42, the polarization absorbing member AP is attached after adjusting the transmission axis thereof before or after assembling the first prism 41 and the second prism 42. Alternatively, the polarization absorbing member AP may be attached after adjusting the transmission axis thereof before or after assembling the first flat plate-shaped member 40 and the second flat plate-shaped member 50. When the polarization absorbing member AP is disposed on the second inner surface 42b of the second prism 42 and the first inner surface 41b of the first prism 41, the polarization absorbing member AP is attached after assembling the first prism 41 and the second prism 42. In this case, an air layer AL is provided between the first prism 41 and the polarization absorbing member AP using a spacer or the like (not shown).

[0053] As shown in FIG. 11 , in the virtual image display device 100A of this embodiment, when unwanted external light OL2 enters the second prism 42 from the second inner surface 42b, the s-polarized light PLs is absorbed by the polarization absorption member AP, and only p-polarized light PLp enters. The p-polarized light PLp of the unwanted external light OL2 is reflected within the second prism 42 and reaches the polarization separation film 45 of the diagonal mirror unit IM, but is not reflected by the polarization separation film 45. Therefore, the unwanted external light OL2 does not reach the eye EY of the wearer US, and does not cause a see-through ghost. This allows the wearer US to have a good field of vision.

[0054] [Fourth embodiment] The virtual image display device of the fourth embodiment will be described below. Note that 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 parts common to the virtual image display device of the first embodiment will be omitted.

[0055] As shown in FIGS. 12 and 13 , in this embodiment, the polarization absorption member AP is disposed on the second lateral side surface 42e of the second prism 42. That is, the polarization absorption member AP is provided on the second lateral side surface 42e of the second prism 42. As a result, the unwanted external light OL2 incident from the second lateral side surface 42e of the second prism 42 passes through the polarization absorption member AP before entering the inclined mirror portion IM, thereby suppressing reflection at the inclined mirror portion IM. This prevents the unwanted external light OL2 from reaching the eye EY of the wearer US. Note that, as shown in FIG. 12 and other figures, the polarization absorption member AP is preferably disposed on the second lateral side surface 42e of the second prism 42, the first lateral side surface 41e of the first prism 41, the third lateral side surface 51e of the quarter-wave plate 51, and the fourth lateral side surface 52e of the cover member 52. That is, it is preferable that the polarization absorption member AP be provided across the fifth lateral side surface 40v of the first flat plate-shaped member 40 and the sixth lateral side surface 50v of the second flat plate-shaped member 50. This can further suppress see-through ghosts.

[0056] When the polarization-absorbing member AP is provided only on the second lateral side surface 42e of the second prism 42, the polarization-absorbing member AP is attached after adjusting the transmission axis thereof before or after assembling the first prism 41 and the second prism 42. Alternatively, the polarization-absorbing member AP may be attached after adjusting the transmission axis thereof before or after assembling the first flat plate-shaped member 40 and the second flat plate-shaped member 50. When the polarization-absorbing member AP is provided on the second lateral side surface 42e of the second prism 42, the first lateral side surface 41e of the first prism 41, the third lateral side surface 51e of the quarter-wave plate 51, and the fourth lateral side surface 52e of the cover member 52, the polarization-absorbing member AP is attached after assembling the first flat plate-shaped member 40 and the second flat plate-shaped member 50.

[0057] In the virtual image display device 100A of this embodiment, when unwanted external light OL2 entering from the side, which causes a see-through ghost, enters the second prism 42 from the second lateral side surface 42e of the second prism 42, the s-polarized light PLs is absorbed by the polarization absorption member AP, and only p-polarized light PLp enters. The p-polarized light PLp of the unwanted external light OL2 is reflected within the second prism 42 and reaches the polarization separation film 45 of the diagonal mirror unit IM, but is not reflected by the polarization separation film 45. Therefore, the unwanted external light OL2 does not reach the eye EY of the wearer US, and does not cause a see-through ghost. This allows the wearer US to obtain a good field of vision.

[0058] [Variations and Others] The present invention has been described above in accordance with the embodiments, but the present invention is not limited to the above embodiments and can be implemented in various forms without departing from the spirit of the invention, and for example, the following modifications are also possible.

[0059] The arrangements of the polarization absorbing members AP shown in the first to fourth embodiments may be combined. By combining multiple arrangements of the polarization absorbing members AP described above, it is possible to more effectively suppress see-through ghosts. The transmission axis of each polarization absorbing member AP is parallel or approximately parallel to the transmission axis of the polarization splitting film 45, so it does not affect the image light ML or the external light OL.

[0060] In the above, the HMD 200 is described as comprising a first virtual image display device 100A and a second virtual image display device 100B, but the HMD 200 may also be configured to support a single first virtual image display device 100A or second display device 100B in front of the eyes by a support device 100C.

[0061] The compensating plate 55 can be omitted from the cover member 52. In this case, the quarter-wave plate 51 is disposed only in the range of the second lens 53, and the second lens 53 is covered by the compensating lens .

[0062] In the second flat plate-shaped member 50, the cover member 52 may be omitted.

[0063] The incident optical surface 41a may be omitted from the first prism 41 of the first flat plate member 40. In this case, the optical system does not include the lens unit 44.

[0064] The first lens 30 is not limited to being bonded to the first image-forming element 11a, but may be disposed separately from the first image-forming element 11a.

[0065] As shown in FIG. 14 , the first virtual image display device 100A may include an s-polarized light transmitting polarizer 12 disposed between the first lens 30 and the display element 11 in the first display unit 20a. The first display unit 20a also includes a third flat-plate member 150 on the external side of the second flat-plate member 50. The third flat-plate member 150 is an image light blocking unit LP. The third flat-plate member 150 includes an outer quarter-wave plate 151 disposed on the external side of the transmissive mirror 56 or the light-collecting reflector CR, and a polarizer 59 disposed on the external side of the outer quarter-wave plate 151. That is, the first display unit 20a has a structure in which the inner quarter-wave plate 51 and the outer quarter-wave plate 151 are disposed between the inner polarization separation film 45 and the outer polarizer 59. The polarizer 59 selectively absorbs the image light ML transmitted through the outer quarter-wave plate 151 according to the polarization direction. In the example of FIG. 14, the polarization absorbing member AP is provided on the bottom surface of the third flat plate member 150 in addition to the bottom surfaces 40w, 50w of the first and second flat plate members 40, 50.

[0066] As shown in FIG. 15 , the image light ML, which is circularly polarized light PLc that has passed through the transmissive mirror 56, becomes p-polarized light PLp by passing through the outer quarter-wave plate 151, and then enters the polarizing plate 59, where most of the light is blocked by the polarizing plate 59. In other words, the image light ML is blocked by the third flat plate-shaped member 150 and does not leak out. This prevents the image light ML from being observed from the outside, ensuring privacy. Meanwhile, the outside light OL that has entered the polarizing plate 59 becomes only s-polarized light PLs by passing through the polarizing plate 59, becomes circularly polarized light PLc by passing through the outer quarter-wave plate 151, and is partially transmitted through the transmissive mirror 56. The outside light OL, which is circularly polarized light PLc that has partially passed through the transmissive mirror 56, becomes p-polarized light PLp by passing through the inner quarter-wave plate 51, passes through the polarization separation film 45, and is incident on the pupil position PP.

[0067] In a specific embodiment, a direct virtual image type virtual image display device includes a display element that emits image light, a first lens onto which the image light from the display element is incident, a first prism onto which the image light that has passed through the first lens is incident, a second prism that is joined to the first prism to form a parallel plate-shaped prism light-guiding member, an oblique mirror section that is provided at the joint between the first prism and the second prism and that reflects at least a portion of the image light guided in the first prism, a plano-convex second lens that is arranged opposite a first outer surface of the first prism onto which the image light reflected by the oblique mirror section is incident, and a transmissive mirror that is formed on the convex surface of the second lens and that partially reflects the image light reflected by the oblique mirror section toward the oblique mirror section, and the second prism has a polarization absorbing member on any surface except the second outer surface facing the outside world.

[0068] In the virtual image display device, in order to form a virtual image directly without forming an intermediate image, the first lens, the second lens, and the transmissive mirror ensure refractive power, ensuring a magnification while suppressing an increase in the optical path length, and thus making it possible to avoid an increase in the size of the optical system. Furthermore, by allowing unwanted external light that causes see-through ghosts to pass through the polarization absorbing member of the second prism, it is possible to effectively suppress see-through ghosts while ensuring the see-through nature of the wearer's field of vision, thereby providing a good field of view.

[0069] In a specific embodiment of the virtual image display device, the polarization absorbing member is an absorptive polarizing plate.

[0070] In a specific embodiment, the virtual image display device further includes a quarter-wave plate disposed between the first outer surface of the first prism and the plane of the second lens, and the oblique mirror portion has a polarization separation film that selectively reflects image light according to its polarization direction, and the transmission axis of the polarization absorption member is parallel to the transmission axis of the polarization separation film. In this case, unwanted external light passes through the polarization absorption member, and the same polarization as that reflected by the polarization separation film is absorbed. The remaining polarized light of the unwanted external light that passes through the polarization absorption member is transmitted by the polarization separation film even if reflected within the second prism, thereby suppressing reflection of the unwanted external light. This prevents unwanted external light from reaching the wearer's eyes, ensuring good visibility.

[0071] In a specific embodiment of the virtual image display device, the polarization absorbing member is disposed on the first bottom surface of the second prism. In this case, unwanted external light incident from the front diagonally downward side passes through the polarization absorbing member before entering the diagonal mirror portion, thereby suppressing reflection at the diagonal mirror portion. As a result, unwanted external light can be prevented from reaching the wearer's eyes.

[0072] In a specific embodiment of the virtual image display device, the polarization absorbing member is disposed on the first bottom surface of the second prism, the second bottom surface of the quarter-wave plate, and the third bottom surface of the cover member including the second lens and the transmissive mirror, thereby further suppressing see-through ghosts.

[0073] In a specific aspect of the virtual image display device, the second prism has a curved surface at the boundary between the first bottom surface and the second lateral side surface, and the polarization absorption member extends from the first bottom surface to the curved surface.

[0074] In a specific embodiment of the virtual image display device, the polarization absorbing member is disposed on the inclined surface of the second prism facing the oblique mirror unit, closer to the second inner surface of the second prism on the side opposite the second outer surface of the oblique mirror unit. In this case, unwanted external light passes through the polarization absorbing member before entering the oblique mirror unit, thereby suppressing reflection at the oblique mirror unit. As a result, unwanted external light can be prevented from reaching the wearer's eyes.

[0075] In a specific embodiment of the virtual image display device, the polarization absorbing member is disposed on the second inner surface of the second prism opposite to the second outer surface. In this case, unwanted external light incident on the second inner surface of the second prism passes through the polarization absorbing member before entering the oblique mirror portion, thereby suppressing reflection at the oblique mirror portion. As a result, unwanted external light can be prevented from reaching the wearer's eyes.

[0076] In a specific embodiment of the virtual image display device, the polarization absorbing member is disposed on a first inner surface of the first prism, opposite to the first outer surface facing the outside world, via an air layer. In this case, the influence of unnecessary outside light entering through the first inner surface of the first prism can also be suppressed. Even if the polarization absorbing member is provided on the first prism, the air layer is interposed between the first prism and the polarization absorbing member, so reflection of the image light within the first prism is not hindered.

[0077] In a specific embodiment of the virtual image display device, the polarization absorbing member is disposed on the second lateral side surface of the second prism. In this case, unwanted external light incident from the second lateral side surface passes through the polarization absorbing member before entering the oblique mirror portion, thereby suppressing reflection at the oblique mirror portion. As a result, unwanted external light can be prevented from reaching the wearer's eyes.

[0078] In a specific embodiment of the virtual image display device, the polarization absorbing member is disposed on the second side surface of the second prism, the first side surface of the first prism, the third side surface of the quarter-wave plate, and the fourth side surface of the cover member including the second lens and the transmissive mirror, thereby further suppressing see-through ghosts.

[0079] In a specific embodiment of the virtual image display device, the transmittance of the polarization absorbing member is 40% or more and 50% or less, which can ensure a certain degree of see-through property of the surface on which the polarization absorbing member is provided.

[0080] In a specific embodiment of the virtual image display device, the first lens, the prism light-guiding member, the oblique mirror portion, the second lens, and the transmissive mirror constitute a simple microscope-type imaging optical system that forms an erect image, and the first prism internally reflects the image light twice while diverging it. In this case, it is easy to shorten the distance from the display element to the transmissive mirror, and it is possible to reduce the size of the prism light-guiding member, as well as the size of the display element and the first lens.

[0081] In a specific embodiment, a direct virtual image type optical unit comprises a first lens onto which image light from a display element is incident, a first prism onto which the image light that has passed through the first lens is incident, a second prism that is joined to the first prism to form a parallel plate-shaped prism light-guiding member, an oblique mirror section that is provided at the joint between the first prism and the second prism and that reflects at least a portion of the image light guided in the first prism, a plano-convex second lens that is arranged opposite a first outer surface of the first prism onto which the image light reflected by the oblique mirror section is incident, and a transmissive mirror that is formed on the convex surface of the second lens and that partially reflects the image light reflected by the oblique mirror section toward the oblique mirror section, and the second prism has a polarization absorbing member on any surface except the second outer surface facing the outside world. [Explanation of symbols]

[0082] 11...display element, 30...first lens, 40...first plate-shaped member, 40v...lateral side, 40w...bottom, 41...first prism, 41a...incident optical surface, 41b...inner surface, 41c...outer surface, 41d...inclined surface, 41e...lateral side, 42...second prism, 42b...inner surface, 42c...outer surface, 42d...inclined surface, 42e...lateral side, 42f...bottom, 42 g...curved surface, 44...lens portion, 45...polarized light separation film, 48...prism light guide member, 50...second flat plate member, 50c...inner surface, 50v...side surface, 50w...bottom surface, 51, 151...quarter wave plate, 51e...side surface, 51f...bottom surface, 52...cover member, 52e...side surface, 52f...bottom surface, 53...second lens, 54...compensating lens, 55...compensating flat plate plate, 56...transmissive mirror, 58...optical element, 59...polarizing plate, 61...spacer, 71...case, 90...user terminal, 100...optical unit, 100A, 100B...virtual image display device, 100C...support device, 102a, 102b...display drive unit, 103a, 103b...combiner, AL...air layer, AP...polarized light absorbing member, APm...absorptive polarizing plate, AX...optical axis, CR...light collecting and reflecting unit, CS...light blocking member, DIS...direct virtual image optical system, EP...exit pupil, EY...eye, IM...diagonal mirror unit, IS...imaging optical system, LP...image light blocking unit, ML...image light, OL...external light, OL2...unwanted external light, PLc...circularly polarized light, PLp...p-polarized light, PLs...s-polarized light, PP...pupil position, US...wearer

Claims

1. a display element that emits image light; a first lens onto which the image light from the display element is incident; a first prism onto which the image light having passed through the first lens is incident; a second prism bonded to the first prism to form a parallel-plate prism light-guiding member; an inclined mirror portion provided at a joint between the first prism and the second prism, the inclined mirror portion reflecting at least a part of the image light guided through the first prism; a plano-convex second lens arranged to face a first outer surface of the first prism onto which the image light reflected by the oblique mirror portion is incident; a transmissive mirror formed on the convex surface of the second lens and configured to partially reflect the image light reflected by the inclined mirror portion toward the inclined mirror portion; Equipped with the second prism has a polarization absorbing member on any surface thereof except for a second outer surface on the outside world side; Direct virtual image type virtual image display device.

2. The polarization absorbing member is an absorptive polarizing plate.

2. The direct virtual image type virtual image display device according to claim 1.

3. a quarter-wave plate disposed between the first outer surface of the first prism and a flat surface of the second lens; the inclined mirror portion has a polarization separation film that selectively reflects the image light in accordance with the polarization direction, The transmission axis of the polarization absorbing member is parallel to the transmission axis of the polarization separating film.

2. The direct virtual image type virtual image display device according to claim 1.

4. the polarization absorption member is disposed on a first bottom surface of the second prism; 2. The direct virtual image type virtual image display device according to claim 1.

5. the polarization absorption member is disposed on a first bottom surface of the second prism, a second bottom surface of the quarter-wave plate, and a third bottom surface of a cover member including the second lens and the transmissive mirror; 4. The direct virtual image type virtual image display device according to claim 3.

6. the second prism has a curved surface at the boundary between the first bottom surface and the second lateral side surface, the polarization absorbing member extends from the first bottom surface to the curved surface; 6. The direct virtual image type virtual image display device according to claim 4 or 5.

7. the polarization absorption member is disposed on the inclined surface of the second prism facing the inclined mirror portion, closer to the second inner surface of the second prism on the side opposite to the second outer surface with respect to the inclined mirror portion; 2. The direct virtual image type virtual image display device according to claim 1.

8. the polarization absorbing member is disposed on a second inner surface of the second prism opposite to the second outer surface; 2. The direct virtual image type virtual image display device according to claim 1.

9. the polarization absorbing member is disposed on a first inner surface of the first prism opposite to the first outer surface on the outside world side, with an air layer interposed therebetween; 9. The direct virtual image type virtual image display device according to claim 8.

10. the polarization absorbing member is disposed on a second lateral side surface of the second prism; 2. The direct virtual image type virtual image display device according to claim 1.

11. the polarization absorbing member is disposed on a second lateral side surface of the second prism, a first lateral side surface of the first prism, a third lateral side surface of the quarter-wave plate, and a fourth lateral side surface of a cover member including the second lens and the transmissive mirror; 4. The direct virtual image type virtual image display device according to claim 3.

12. The transmittance of the polarized light absorbing member is 40% or more and 50% or less.

2. The direct virtual image type virtual image display device according to claim 1.

13. the first lens, the prism light-guiding member, the oblique mirror portion, the second lens, and the transmissive mirror constitute a simple microscope-type imaging optical system that forms an erect image, The first prism internally reflects the image light twice while diverging the image light.

2. The direct virtual image type virtual image display device according to claim 1.

14. a first lens onto which image light from a display element is incident; a first prism onto which the image light having passed through the first lens is incident; a second prism bonded to the first prism to form a parallel-plate prism light-guiding member; an inclined mirror portion provided at a joint between the first prism and the second prism, the inclined mirror portion reflecting at least a part of the image light guided through the first prism; a plano-convex second lens arranged to face a first outer surface of the first prism onto which the image light reflected by the oblique mirror portion is incident; a transmissive mirror formed on the convex surface of the second lens and configured to partially reflect the image light reflected by the inclined mirror portion toward the inclined mirror portion; Equipped with the second prism has a polarization absorbing member on any surface thereof except for a second outer surface on the outside world side; Direct virtual image type optical unit.

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