Virtual image display devices and optical unit

Abstract

To prevent a decrease in the luminance of an optical system.SOLUTION: Virtual image display devices 100A and 100B respectively include: a display element 11; a first lens 30 on which video light ML from the display element 11 is incident; a first prism 41 on which the video light ML passing through the first lens 30 is incident; a second prism 42 which is joined to the first prism 41 and forms a parallel flat plate-shaped prism light guide member 48; an oblique mirror portion 45 which is provided at a joint between the first prism 41 and the second prism 42 and reflects a first portion of the video light ML guided in the first prism 41; a plano-convex second lens 53; a transmission mirror 56 which is formed at a convex surface 53g of the second lens 53 and reflects part of the video light ML reflected by the oblique mirror portion 45 toward the oblique mirror portion 45; a first quarter-wave plate 51; a compensation lens 54 including a concave surface 54f joined to the convex surface 53g of the second lens 53; a condensing reflection mirror 24; and a second quarter-wave plate 21.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a see-through type 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 collecting 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, passes through the outer surface of the prism member and is reflected by the collecting 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] JP 2020-08749 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned head mounted display, since there are two reflective members in front of the eyes, the luminance of the image light reaching the exit pupil is lower than that of a head mounted display having a single reflective member in total. [Means for solving the problem]

[0005] A virtual image display device according to one aspect of the present invention is a direct virtual image type virtual image display device, comprising: a display element that emits image light; a first lens into which the image light from the display element is incident; a first prism into 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-like prism light-guiding member; an oblique mirror portion provided at the joint between the first prism and the second prism and that reflects a first portion of the image light guided in the first prism; and a plano-convex second lens disposed opposite to the outer surface of the first prism into which the first portion of the image light reflected by the oblique mirror portion is incident. The optical system comprises a transmitting mirror formed on the convex surface of the second lens and reflecting a portion of the image light reflected by the oblique mirror portion toward the oblique mirror portion; a first 1 / 4 wavelength plate arranged between the outer surface of the first prism and the second lens; a compensating lens having a concave surface joined to the convex surface of the second lens via the transmitting mirror and a surface parallel to the outer surface of the first prism; a focusing reflective mirror arranged within the second prism and reflecting a second portion of the image light that passes through the oblique mirror portion and is reflected by the inner surface of the second prism; and a second 1 / 4 wavelength plate arranged between the inner surface of the second prism and the focusing reflective mirror.

[0006] An optical unit according to one aspect of the present invention is a direct virtual image type optical unit, comprising: a first lens onto which image light from a display element that emits image light 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-like prism light-guiding member; an inclined mirror portion that is provided at a joint between the first prism and the second prism and that reflects a first portion of the image light guided in the first prism; a plano-convex second lens that is arranged to face an outer surface of the first prism onto which the first portion of the image light reflected by the inclined mirror portion is incident; a transmitting mirror formed on the convex surface of the first prism and reflecting a portion of the image light reflected by the oblique mirror portion toward the oblique mirror portion; a first 1 / 4 wavelength plate arranged between the outer surface of the first prism and the second lens; a compensating lens having a concave surface joined to the convex surface of the second lens via the transmitting mirror and a surface parallel to the outer surface of the first prism; a collecting reflection mirror arranged within the second prism and reflecting a second portion of the image light that is transmitted through the oblique mirror portion and reflected by the inner surface of the second prism; and a second 1 / 4 wavelength plate arranged between the inner surface of the second prism and the collecting reflection mirror. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an external view illustrating a state in which the virtual image display device according to a first embodiment is used. [Diagram 2] FIG. 4 is a side cross-sectional view illustrating the internal structure of one of the display devices. [Diagram 3] FIG. 2 is a conceptual perspective view illustrating a first display unit. [Figure 4] FIG. 2 is a perspective view illustrating the external structure of a first display unit. [Diagram 5] 3A to 3C are diagrams for explaining the shapes of a first image-forming element and a first lens, etc. FIG. [Figure 6] FIG. 2 is a side cross-sectional view illustrating an optical path inside one of the display devices. [Figure 7] 10 is a side cross-sectional view illustrating a state in which image light emitted from a specific region of a display element in one display device is incident on an exit pupil. FIG. [Figure 8]10 is a side cross-sectional view illustrating a state in which image light emitted from a specific region of a display element in one display device is incident on an exit pupil. FIG. [Figure 9] 10 is a side cross-sectional view illustrating a state in which image light emitted from a specific region of a display element in one display device is incident on an exit pupil. FIG. [Figure 10] FIG. 7 is a diagram in which FIG. 8 and FIG. 9 are superimposed. [Figure 11] 11A and 11B are diagrams illustrating the results of a computer simulation regarding the ray angles of the partial image light shown in FIG. 10. [Figure 12] 4A to 4C are diagrams illustrating calculations of the utilization efficiency of image light and the see-through transmittance in the first embodiment. [Figure 13] 5A to 5C are diagrams illustrating an example of the structure of a prism light-guiding member. [Figure 14] 10A to 10C are diagrams illustrating an example of assembly of a prism light guide member. [Figure 15] 4 is a perspective view for explaining an example of the structure and assembly of a first display unit. FIG. [Figure 16] FIG. 11 is a side cross-sectional view illustrating the internal structure of one display device according to the second embodiment. [Figure 17] 13 is a side cross-sectional view illustrating another internal structure of one display device according to the second embodiment. FIG. [Figure 18] FIG. 13 is a diagram illustrating an example of an optical path of stray light. [Figure 19] FIG. 4 is a diagram showing an observation direction of the light collecting reflecting mirror. [Figure 20] 1A and 1B are diagrams illustrating a structure in which a light-collecting reflecting mirror is divided into a plurality of partially reflecting surfaces. [Figure 21] FIG. 4 is a side cross-sectional view showing the configuration of a second lens made of a plurality of materials. [Figure 22] 11A to 11C are side cross-sectional views showing differences in the paths of light incident on a second lens. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0009] Fig. 1 is a diagram for explaining the wearing state of a head mounted virtual image display device (hereinafter also referred to as a head mounted display or HMD) 200, in which the observer or wearer US wearing the HMD 200 recognizes an image as a virtual image. In Fig. 1 etc., X, Y, and Z are an orthogonal coordinate system, the +X direction corresponds to the lateral 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 lateral direction in which the 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.

[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 is an information terminal. The first virtual image display device 100A functions as an HMD alone and is composed of a first display drive unit 102a arranged at the top and a first combiner 103a that is shaped like a glasses lens and covers the front of the eyes. The second virtual image display device 100B also functions as an HMD alone and is composed of a second display drive unit 102b arranged at the top and a second combiner 103b that is shaped like a glasses lens and covers the front of the eyes. The support device 100C is a mounting member that is mounted on the head of the wearer US, and supports the upper end sides of the pair of combiners 103a and 103b via the display drive units 102a and 102b that are integrated in appearance. The first virtual image display device 100A and the second virtual image display device 100B are optically identical or are left-right inverted versions of each other, and a detailed description of the second virtual image display device 100B will be omitted.

[0011] FIG. 2 is a side cross-sectional view for explaining the internal structure 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 called 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, and is also called 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. The first flat plate member 40 includes a third lens 44 facing the first lens 30. The first flat plate member 40 guides the image light ML emitted from the display element 11 and incident from the third lens 44 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 by partially returning the image light ML from the first plate-shaped member 40 to the first plate-shaped member 40, and also causes external light OL to be incident on the pupil position PP via the first plate-shaped member 40. The first lens 30, the third lens 44, the first plate-shaped member 40, and the second plate-shaped member 50 each function as a lens having a 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, and 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 member 40 through the first lens 30. The first image forming element 11a is housed and supported in the case 71. The first image forming element 11a is, for example, an organic EL (organic electroluminescence) display, and 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, 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 first image forming element 11a, instead of an LCD, LCOS (Liquid crystal on silicon, LCoS is a registered trademark), a digital micromirror device, or the like can be used. In the first virtual image display device 100A, the optical device excluding the first circuit member 80a is called an optical unit 100. The optical unit 100 includes a direct virtual image type 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, a polarization separation film 45A as an oblique mirror unit 45, and a second flat plate member 50. In the first display unit 20a, the first lens 30 has a positive refractive power, and the image light ML from the first image forming element 11a is incident on the first lens 30. The first lens 30 has a flat light entrance surface 30f that is bonded to the first image forming element 11a, and a convex light exit surface 30g. The light exit surface 30g is, for example, a spherical surface, but can be an aspheric surface having an axisymmetric shape. The first lens 30 can be considered as being divided into a parallel plate 31 and a lens portion 32. By ensuring that the thickness of the parallel plate 31 is greater than or equal to a predetermined value, foreign matter attached to the surface of the first lens 30 becomes less noticeable. The lens portion 32 is a plano-convex lens having a positive refractive power. A plano-convex lens has one surface that is planar and the other surface that is convex. 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 third lens 44, which is a plano-convex lens, a first prism 41, which is a parallel flat plate, and a second prism 42, which is a parallel flat plate. The third lens 44 and the first prism 41 are joined at the inclined surfaces 44b and 41a. The first prism 41 and the second prism 42 are joined at the inclined surfaces 41d and 42d. The third lens 44, 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. On the inclined surface 41d formed on the lower side of the first prism 41, a polarization separation film 45A is formed as a flat oblique mirror portion 45. The combination of the prism light-guiding member 48 and the second flat-plate member 50 described later corresponds to the first combiner 103a in FIG. 1.

[0016] The third lens 44 is a plano-convex lens having a positive refractive index, and has an incident optical surface 44a facing the light exit surface 30g of the first lens 30, and an oblique surface 44b coupled to the first prism 41. The incident optical surface 44a is a convex surface, for example a spherical surface, but can be an axially symmetric aspheric surface. The third lens 44 is made of, for example, fused silica, and has a relatively low refractive index. The third lens 44 has a refractive index equivalent to that of the first lens 30.

[0017] 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 and has an inclined surface 41a coupled to the inclined surface 44b of the third lens 44, an inner surface 41b, an outer surface 41c, and an inclined surface 41d. The first prism 41 also has an upper flat surface 40u and a part of a horizontal flat surface 40v (see FIG. 3, etc.) described later. Here, the inclined surface 41a is inclined downward in the front as a whole, and the optical axis passing through the inclined surface 41a extends in a direction between the +Z direction, which is the front, and the +Y direction, which is the upper side. This makes it easier to arrange the first image forming element 11a, which is the display element 11, on the outside side than the inner surface 41b, and the angle at which the image light ML is propagated in the first prism 41 (in the first prism 41 or inside the first prism 41) can be adjusted. The inner surface 41b and the outer surface 41c are parallel to each other and extend perpendicular to the optical axis AX between the pupil position PP. The inner surface 41b and the outer surface 41c internally reflect the image light ML (i.e., reflect it inside the object surface), and it is particularly preferable that they totally reflect the image light ML. The inner surface 41b can be hard-coated to improve scratch resistance or abrasion resistance. The inclined surface 41d is a flat surface. The inclined surface 41d forms an acute angle with the 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 first lens 30 is about 20 mm. The first prism 41 is made of glass or a resin material and has a refractive index higher than that of the first lens 30.

[0018] The number of reflections of the image light ML in the first prism 41 is basically one at the inner surface 41b, one at the outer surface 41c, and one at the polarization separation film 45A described later. By making the number of internal reflections of the image light ML in the first prism 41 two, it is possible to prevent light having different reflections in the first prism 41 from being mixed while increasing the angle of view of the image light ML, the pupil position PP, or the aperture PPa. The image light ML reflected by the inner surface 41b and the outer surface 41c is less divergent than the initial divergent state emitted from the first image forming element 11a because no intermediate image is formed in the first display unit 20a or the imaging optical system IS, but it enters the inner surface 41b and the outer surface 41c in a divergent state and the divergent state is maintained. Here, the divergent state of the image light ML means a state in which the area occupied by the image light ML in any virtual plane perpendicular to the optical axis gradually expands as the image light ML travels along the optical axis. In addition, the degree of divergence of the image light ML is suppressed to at least the extent that, in any imaginary plane perpendicular to the optical axis, the image light ML is contained inside the first prism 41, including before and after reflection at the inner surface 41b and the outer surface 41c.

[0019] The second prism 42, like the first prism 41, has a rectangular prism-like outer shape and a trapezoidal vertical section. The second prism 42 transmits the image light ML and has an inner surface 42b, an outer surface 42c, and an inclined surface 42d. The second prism 42 also has a part of a horizontal plane 40v described later and a lower plane 40w (see FIG. 3, FIG. 4, etc.). Here, the inner surface 42b and the outer surface 42c are parallel to each other and extend perpendicular to the optical axis AX between the pupil position PP. The inner surface 42b can be hard-coated to improve scratch resistance or abrasion resistance. The second prism 42 is made of glass or a resin material and has a refractive index equal to that of the first prism 41.

[0020] The polarization separation film 45A is integrally formed on the inclined surface 41d of the first prism 41 and is sandwiched between the inclined surface 41d of the first prism 41 and the inclined surface 42d of the second prism 42. The space between the polarization separation film 45A and the inclined surface 42d is filled with a bonding adhesive CT. The polarization separation film 45A is formed of a dielectric multilayer film, and when the image light ML contains s-polarized light s, it efficiently reflects the s-polarized image light ML, and when the image light ML contains p-polarized light p, it efficiently transmits the p-polarized image light ML. The polarization separation film 45A may be any film that selectively reflects the image light ML according to the polarization direction, and may be, for example, a wire grid. The polarization separation film 45A may have a flat surface that does not affect the image formation. The polarization separation film 45A may have a slightly convex or concave curved surface that does not affect the image formation. The polarization separation film 45A can have high scratch resistance or abrasion resistance by applying a hard coat to the surface. The space between the polarization separation film 45A and the inclined surface 41d may be filled with a transparent filler instead of the 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 the bonded state. The polarization separation film 45A may be integrally formed on the inclined surface 42d of the second prism 42 instead of on the inclined surface 41d of the first prism 41.

[0021] The inclination angle θ of the polarization splitting film 45A is 90°-β0 or more, assuming that the reflection angle of the image light ML on the optical axis AX in the first prism 41 is β0. Assuming that the polarization splitting film 45A does not obstruct the path of the image light ML, assuming that the maximum reflection angle of the image light ML is βmax, it is desirable that the inclination angle θ of the polarization splitting film 45A is smaller than βmax. The reflection angle β0 of the image light ML corresponds to the angle between the normal to the inner surface 41b and the optical axis AX passing through the incident optical surface 44a, and is an acute angle. In other words, the optical axis AX of the incident optical surface 44a extends in a direction less than 90° with respect to the normal to the inner surface 41b.

[0022] 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, and converts the s-polarized image light ML reflected by the polarization separation film 45A into circularly polarized light c, and converts the circularly polarized image light ML reflected by the cover member 52 into p-polarized light p. 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 transmitting mirror 56.

[0023] The second flat plate member 50 is disposed at a distance of about 20 μm to 50 μm from the first flat plate member 40. The outer side surfaces 41c, 42c of the first flat plate member 40 and the inner side surface 50c of the second flat plate member 50 may be slightly curved, and a minute step may be formed at the boundary between the outer side surfaces 41c, 42c. However, by setting the distance between the outer side surfaces 41c, 42c and the inner side surface 50c to 20 μm or more, more preferably 30 μm or more, it is possible to prevent these surfaces from being excessively close to each other. Conversely, by setting the distance between the outer side surfaces 41c, 42c and the inner side surface 50c to 50 μm or less, it is possible to prevent an increase in the thickness of the first combiner 103a obtained by combining the first flat plate member 40 and the second flat plate member 50. A spacer 61 is provided between the outer surfaces 41c, 42c of the first flat plate member 40 and the inner surface 50c of the second flat plate member 50 to adjust the distance 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.

[0024] In the cover member 52, the second lens 53 is thin but has a positive refractive power, and has a flat surface 53f bonded to the quarter-wave plate 51, and a convex surface 53g facing the compensation lens 54. The convex surface 53g is, for example, a spherical surface, but can be an axially symmetric aspheric surface. The compensation lens 54 is thin but has a positive refractive power, and has a concave surface 54f facing the second lens 53, and a flat surface 54g. The compensation plate 55 is a parallel plate and has a pair of flat surfaces 55f, 55g. Here, the concave surface 54f of the compensation plate 55 has the same shape as the convex surface 53g of the second lens 53. The flat surface 54g of the compensation lens 54 and the flat surface 55g of the compensation plate 55 are on the same plane and are continuous. The transmission 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 transmitting mirror 56 is called a first light collecting reflector CR1.

[0025] The second lens 53, the compensation lens 54, and the compensation plate 55 are formed of a resin material. The second lens 53, the compensation lens 54, and the compensation plate 55 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 optical elements 58 integrally formed from the same resin material.

[0026] The combination of the second lens 53, the compensation lens 54, and the compensation plate 55 functions as a parallel plate as a whole. That is, the external light OL incident on the position of the compensation lens 54 or the compensation plate 55 passes through them without being affected by the lens action of the compensation lens 54 or the like or the step existing at the outer edge of the compensation lens 54. In this way, the compensation 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 compensation lens 54, and the planes 55f, 55g of the compensation plate 55 are not necessarily limited to strict planes, and may be, for example, approximately flat, or may include a curved surface partially or entirely. In addition, the plane 53f of the second lens 53, the plane 54g of the compensation lens 54, and the planes 55f, 55g of the compensation plate 55 may include a curved surface for correcting the eyesight of the wearer US or a curved surface as a design such as sunglasses or fashion glasses, within a range that does not cause inconvenience in terms of optical performance. The flat surfaces 54g, 55g of the compensation lens 54 and the compensation plate 55 may be coated with an anti-reflection film or a hard coat. The outside light OL that has passed through the compensation plate 55 passes above, below, left and right of the compensation lens 54, and is incident on a peripheral area outside the incident area of ​​the image light ML corresponding to the compensation lens 54, that is, from the compensation plate 55. This ensures a wide see-through field of view with respect to the outside world. The field of view of the outside light OL is set, for example, to about 40° upward and about 40° downward.

[0027] The diameter of the second lens 53 is set to 20 mm to 25 mm in order to ensure the angle of view. The thickness in the Z direction of the first flat plate member 40 or the prism light-guiding member 48 is 6 mm to 8 mm, and the distance from the inner surfaces 41b, 42b of the first flat plate member 40 to the pupil position PP is about 12 mm to 13 mm, so that the angle of view (diagonal), which is the angular range in which the image light ML is incident on the pupil position PP, can be set to about 40°.

[0028] The transmission mirror 56 is a half mirror that reflects a part of the image light ML that has passed through the second lens 53 and transmits a part of the outside light OL. The transmission mirror 56 reflects the image light ML that has been reflected by the polarization separation film 45A of the first flat plate-shaped member 40 and passed through the ¼ wavelength plate 51 and the second lens 53 toward the pupil position PP. The transmission mirror 56 is a concave mirror that covers the pupil position PP where the eye EY or the 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, and corresponds to the exit pupil EP of the first display unit 20a.

[0029] The transmission mirror 56 transmits a part of the outside light OL, so that a see-through view of the outside world is possible, and a virtual image can be superimposed on an outside image. At this time, the outside light OL passes through the first flat plate-like member 40 and the second flat plate-like member 50, but the flat plate-like members 40, 50 do not act as a lens on the outside light OL. The reflectance of the transmission mirror 56 for the image light ML and the outside light OL is set to 10% or more and 50% or less in the assumed range of incidence angles of the image light ML, from the viewpoint of ensuring the brightness of the image light ML and facilitating the observation of the outside image by the see-through. The transmission mirror 56 is formed, for example, of a dielectric multilayer film made of a plurality of dielectric layers whose film thicknesses are adjusted. The transmission mirror 56 may be a single layer film or a multilayer film of a metal such as Al or Ag whose film thickness is adjusted. The transmission mirror 56 is formed, for example, by lamination using vapor deposition.

[0030] Fig. 3 is a conceptual perspective view mainly explaining the first display unit 20a. In Fig. 3, area AR1 shows the first display unit 20a when viewed obliquely upward from between the front +Z and the side +X, and area AR2 shows the first display unit 20a when viewed from the front +Z side. Note that in Fig. 3, the transmission mirror 56 of the second flat plate-like member 50 is omitted, and only the second lens 53 is shown.

[0031] In the first virtual image display device 100A, the first lens 30, the third lens 44, the second lens 53, and the transmission mirror 56 each have a positive refractive power and tend to converge divergent light. The first lens 30, the third lens 44, the second lens 53, and the transmission mirror 56, including the main body of the first prism 41 and the second prism 42, function as an imaging optical system IS like a simple microscope type microscope that forms an erect image, or a direct virtual image optical system DIS. This allows the real image formed on the display surface 11d of the first image forming element 11a to be formed as a virtual image projected, for example, at infinity, or the real image formed on the display surface 11d to be formed as a virtual image projected several meters ahead. At this time, by adjusting the refractive power of the first lens 30, the third lens 44, the second lens 53, and the transmission mirror 56, the focal length of the imaging optical system IS can be shortened to achieve a desired magnification ratio.

[0032] 2, the optical path along which a portion of the image light ML is emitted from the display element 11, reflected twice by the inner surface 41b and the outer surface 41c of the first prism 41, reflected by the polarization separation film 45A serving as the diagonal mirror section 45, transmitted through the first quarter-wave plate 51 and the second lens 53, reflected by the transmission mirror 56, transmitted through the second lens 53 and the first quarter-wave plate 51 again, transmitted through the polarization separation film 45A, and reaches the exit pupil EP is referred to as a first optical path P1. A portion of the image light ML having a predetermined polarization may be referred to as a polarized component or simply a component of the image light ML.

[0033] As shown in Fig. 2 and Fig. 3, a second light collecting reflector CR2 is provided in the prism light guiding member 48. The second light collecting reflector CR2 includes a second 1 / 4 wavelength plate 21 and a light collecting reflector 24. By providing the light collecting reflector CR2 in the prism light guiding member 48, a part of the image light ML generated by the display element 11 that is not reflected by the polarization separation film 45A but is transmitted through the polarization separation film 45A can be collimated and emitted toward the exit pupil side. As a result, even if a two-sided reflecting member including the polarization separation film 45A and the transmission mirror 56 is present in front of the eye, the utilization efficiency of the image light generated by the display element 11 can be improved to increase the brightness of the image light ML.

[0034] As shown in FIG. 2, the optical path along which a portion of the image light ML is emitted from the display element 11, is reflected twice by the inner surface 41b and outer surface 41c of the first prism 41, passes through the polarization separation film 45A serving as the diagonal mirror portion 45, is reflected by the inner surface 42b of the second prism 42, passes through the first ¼ wavelength plate 21, is reflected by the focusing reflection mirror 24, is reflected again by the inner surface 42b of the second prism 42, is reflected by the polarization separation film 45A, and travels until it reaches the exit pupil EP is called the second optical path P2.

[0035] With reference to FIG. 4, the vertical size ay of the first flat plate member 40 or the second flat plate member 50 is, for example, 34 mm, and the horizontal size ax is, for example, 40 mm. The thickness az of the first flat plate member 40 in the front-rear direction is, for example, about 7 mm, and the combined thickness of the first flat plate member 40 and the second flat plate member 50 is suppressed to about 7.5 mm. In the first flat plate member 40, an upper flat surface 40u is provided on the left and right of the incident optical surface 44a. No light is incident on the upper flat surface 40u. In order to prevent stray light, a light shielding body (not shown) that faces and covers the upper flat surface 40u may be disposed on the upper flat surface 40u, or a light shielding body may be applied to the upper flat surface 40u. The horizontal flat surface 40v and the lower flat surface 40w may also be provided with a light shielding body or the like that covers them. A light shielding body or the like that covers the periphery of the second flat plate member 50 may also be provided with a light shielding body or the like that covers it.

[0036] The shapes of the first image forming element 11a and the first lens 30 will be described with reference to Fig. 5. In Fig. 5, region BR1 shows the first lens 30 etc. as viewed obliquely upward from the front +Z side, region BR2 shows the first lens 30 etc. as viewed obliquely forward from the lower -Y side, and region BR3 shows the first lens 30 etc. as viewed from the lateral +X side. The thickness or height H of the first lens 30 is, for example, about 2 mm, the width W of the first lens 30 is, for example, about 14 mm, and the depth D of the first lens 30 is, for example, about 7 mm.

[0037] The radius of curvature of the convex light exit surface 30g of the first lens 30 is, for example, 20 mm. Additionally, the radius of curvature of the incident optical surface 44a of the first prism 41 shown in FIG. 2 is, for example, 14 mm, and the radius of curvature of the transmission mirror 56 is, for example, 47 mm.

[0038] 2, the first optical path P1 not affected by the action of the light collecting reflection part CR2 will be described in detail. The image light ML from the first image forming element 11a passes through the first lens 30 and the third lens 44 and enters the first prism 41. At this time, the degree of divergence of the image light ML is suppressed by the positive refractive power of the first lens 30 and the third lens 44. In the optical path passing through the first prism 41, the image light ML is sequentially reflected by the inner surface 41b and the outer surface 41c of the first prism 41 without forming an intermediate image, and the s-polarized s component of the image light ML is reflected by the polarization separation film 45A. The s-polarized s image light ML reflected by the polarization separation film 45A passes through the outer surface 41c of the first prism 41 and passes through the first ¼ wavelength plate 51 included in the second flat plate-like member 50, becoming circularly polarized light c, and entering the transmission mirror 56. A part of the image light ML of the circularly polarized light c that entered the transmission mirror 56 passes through the second lens 53, is reflected by the transmission mirror 56, and passes through the second lens 53 and is collimated and passes through the first quarter-wave plate 51 again. As a result, the image light ML that passed through the first quarter-wave plate 51 becomes p-polarized p and enters the first prism 41 from the outer surface 41c, passes through the polarization separation film 45A, and is emitted to the outside of the second prism 42 through the inner surface 42b. The image light ML that has been emitted to the outside of the second prism 42 enters the pupil position PP where the eye EY or pupil of the wearer US is located. Not only the image light ML reflected by the transmission mirror 56, but also the outside light OL that has passed through the transmission mirror 56 and the compensation plate 55 enter the pupil position PP. In other words, the wearer US wearing the first virtual image display device 100A can observe a virtual image by the image light ML superimposed on an outside image.

[0039] The light-collecting reflector CR2 will be described with reference to Fig. 2 and Fig. 3. As described above, the light-collecting reflector CR2 has the second ¼ wavelength plate 21 and the light-collecting reflecting mirror 24.

[0040] Similar to the first quarter-wave plate 51, the second quarter-wave plate 21 converts the s-polarized s (or p-polarized p) image light ML that passes through the polarization separation film 45A and is reflected by the inner surface 42b of the second prism 42 into circularly polarized light c, and converts the circularly polarized c image light ML that is reflected by the focusing reflection mirror 24 into p-polarized p (or s-polarized s).

[0041] The light collecting reflecting mirror 24 reflects the image light ML, which passes through the quarter-wave plate 21 and proceeds toward the light collecting reflecting mirror 24, toward the quarter-wave plate 21 while collecting the image light ML on a concave surface 24a, which is a reflecting surface of the light collecting reflecting mirror 24.

[0042] The light-collecting reflecting mirror 24 is disposed in the prism light-guiding member 48 so that the length of the first optical path P1 along which the image light ML travels from the display element 11 to the eye EY via the transmission mirror 56 outside the prism light-guiding member 48 and the length of the second optical path P2 along which the image light ML travels from the display element 11 to the eye EY via the light-collecting reflecting mirror 24 inside the prism light-guiding member 48 are approximately the same. Here, the fact that the lengths of the first optical path P1 and the second optical path P2 are approximately the same is one of the conditions for observing the positions and sizes of the pixels of the image light ML at the exit pupil EP so as to match in the first component traveling along the first optical path P1 and the second component traveling along the second optical path P2 of the image light ML that reaches the exit pupil EP. If this condition is satisfied, the lengths of the first optical path P1 and the second optical path P2 do not necessarily have to be the same. Hereinafter, the length of the first optical path P1 may be referred to as a first optical path length, and the length of the second optical path P2 may be referred to as a second optical path length.

[0043] Furthermore, the curvature of the light collecting reflection mirror 24 is approximately the same as that of the transmission mirror 56. The material of the second lens 53 is approximately the same as that of the second prism 42. However, these curvatures and materials do not necessarily have to be the same as long as the condition that the position and size of each pixel of the image light ML are observed to be the same at the exit pupil EP is satisfied. As a result, the image light ML that has passed through the first optical path P1 and the image light ML that has passed through the second optical path P2 are superimposed as viewed from the eye EY of the wearer US. At this time, the luminance of the image light ML is increased by the amount of the image light ML that has passed through the second optical path P2, compared to the luminance when only the image light ML that has passed through the first optical path P1 is viewed.

[0044] The first optical path P1 and the second optical path P2 will be described in detail with reference to Fig. 6. In Fig. 6, the shape and dimensions of each component are shown typically to make it easier to distinguish between the optical paths P1 and P2. In Fig. 6, the length L1 of the first optical path P1 is shown typically with a dashed arrow, and the length L2 of the second optical path P2 is shown typically with a dashed arrow.

[0045] As described above, the first optical path P1 is an optical path along which the image light ML is emitted from the display element 11 as light La1, then reflected a total of two times by the inner surface 41b and the outer surface 41c of the prism light-guiding member 48, and a portion of the light La1 is reflected by the polarization separation film 45A as light Lb2, passes through the first ¼ wavelength plate 51 and the second lens 53, is reflected by the transmitting mirror 56, passes through the second lens 53 and the first ¼ wavelength plate 51 again as light Lb3, passes through the polarization separation film 45A, and is emitted from the inner surface 42b of the prism light-guiding member 48 as light Lb4 before reaching the eye EY.

[0046] In addition, the second optical path P2 is an optical path along which the image light ML is emitted from the display element 11 as light La1, then reflected a total of two times by the inner surface 41b and outer surface 41c of the prism light-guiding member 48, and a portion of the light La1 passes through the polarization separation film 45A as light Lc2, reflected by the inner surface 42b of the prism light-guiding member 48, passes through the second ¼ wavelength plate 21, reflected by the collecting reflection mirror 24, passes through the second ¼ wavelength plate 21 again as light Lc3, reflected again by the inner surface 42b of the prism light-guiding member 48, reflected by the polarization separation film 45A, and emitted from the inner surface 42b of the prism light-guiding member 48 as light Lc4 before reaching the eye EY.

[0047] 7, 8, 9, and 10, a result of confirming by computer simulation how a part of the image light ML emitted from the display element 11 enters the exit pupil EP will be described. Fig. 7 shows how the first image light MLA emitted from the first display region 11A of the display element 11 and the first partial image light MLa included in the first image light MLA, among the image light ML, pass through the first optical path P1 and the second optical path P2 shown in Fig. 6, and reach the exit pupil EP as parallel light. Similarly, Fig. 8 shows how the second image light MLB emitted from the second display region 11B of the display element 11 and the second partial image light MLb included in the second image light MLB, among the image light ML, pass through the first optical path P1 and the second optical path P2 shown in Fig. 6, and reach the exit pupil EP as parallel light. Fig. 9 shows how the third image light MLC emitted from the third display region 11C of the display element 11 and the third partial image light MLc included in the third image light MLC, among the image light ML, pass through the first optical path P1 and the second optical path P2 shown in Fig. 6 and reach the exit pupil EP as parallel light. Fig. 10 shows the first image light MLA, the first partial image light MLa, the second image light MLB, the second partial image light MLb, the third image light MLC, and the third partial image light MLc shown in Figs. 7, 8, and 9, superimposed on each other.

[0048] In the examples shown in Figures 7, 8, 9 and 10, the second partial image light MLb emitted from the second display region 11B, which is the central region of the display element 11, passes through the center of the exit pupil EP, and the first partial image light MLa and the third partial image light MLc emitted from the first display region 11A and the third display region 11C, respectively, which are the peripheral regions of the display element 11, pass through portions outside the center of the exit pupil EP.

[0049] With reference to FIG. 11, the results of confirming the ray angles when the first partial image light MLa, the second partial image light MLb, and the third partial image light MLc shown in FIG. 10 reach the exit pupil EP by computer simulation will be described. Region DR1 shows the distribution of the luminance of the image light observed at the exit pupil EP in logarithmic angles, and region DR2 shows an enlarged view of a central portion DR10 of region DR1. When the display element 11 emits only the first partial image light MLa, the second partial image light MLb, and the third partial image light MLc, the light is incident only on three points shown in FIG. 11. From this, it was confirmed that the first partial image light MLa, the second partial image light MLb, and the third partial image light MLc are kept parallel in the same manner as the first partial image light MLA, the second partial image light MLB, and the third partial image light MLC that pass through the transmission mirror 56 arranged in front of the eye.

[0050] In addition, it is also possible to cause all partial image lights MLa, MLb, and MLc to pass through the center of the exit pupil EP by taking measures such as making the prism light-guiding member 48 thicker or making the focusing reflection mirror 24 larger without changing the thickness of the prism light-guiding member 48.

[0051] A comparison between this embodiment and two comparative examples regarding the utilization efficiency of the image light ML emitted from the display element 11 and the see-through transmittance will be described with reference to Fig. 12. Fig. 12 shows an example of the results of trial calculations of the utilization efficiency of the image light ML and the see-through transmittance in this embodiment. In Fig. 12, the shape and dimensions of each component are shown typically to make it easier to distinguish between each optical path.

[0052] In the display units 20a and 20b according to the present embodiment shown in FIG. 12, the brightness of the image light ML at the time of emission from the display element 11 is set to 100%. The image light ML emitted from the display element 11 is reflected twice by the inner surface 41b and the outer surface 41c of the first prism 41 as light La1 including an s-polarized light component s and a p-polarized light component p, and travels toward the polarization separation film 45A. The s-polarized light component s of the light La1 travels along the first optical path P1 described above, is reflected by the polarization separation film 45A, and travels toward the quarter-wave plate 51 as light Lb2. Here, the brightness of the light Lb2 is 50% of the brightness of the light La1 immediately before being separated by the polarization separation film 45A, and is 50% of the brightness of the image light ML at the time of emission. When the light Lb2 passes through the quarter-wave plate 51, it travels toward the second lens 53 as light Lb3 whose polarization has changed from s-polarized light s to right-rotating circularly polarized light c. Next, the light Lb3 is reflected by the transmission mirror 56 and travels toward the quarter-wave plate 51 as light Lb4. Here, if the transmittance and reflectance of the transmission mirror 56 are 50%, the brightness of the light Lb4 is 50% of the brightness of the light Lb3 immediately before being reflected by the transmission mirror 56, and is 25% of the brightness of the image light ML at the time of emission. The right-handed circularly polarized light c of the light Lb3 is changed to the left-handed circularly polarized light c of the light Lb4 by being reflected by the transmission mirror 56. Furthermore, when the light Lb4 passes through the quarter-wave plate 51 again, it travels toward the polarization separation film 45A as light Lb5 whose polarization has changed from the left-handed circularly polarized light c to p-polarized light p. Next, the light Lb5 passes through the polarization separation film 45A and travels toward the exit pupil EP as light Lb6. Here, the luminance of the light Lb6 is the same as the luminance of the light Lb5 immediately before it passes through the polarization separation film 45A, and is 25% of the luminance of the image light ML at the time of emission.

[0053] 12, the p-polarized light p component of the light La1 travels along the second optical path P2 described above, passes through the polarization separation film 45A, and is reflected as light Lc2 by the inner surface 42b of the second prism 42 and travels toward the quarter-wave plate 21. Here, the brightness of the light Lc2 is 50% of the brightness of the light La1 immediately before being separated by the polarization separation film 45A, and is 50% of the brightness of the image light ML at the time of emission. When the light Lc2 passes through the quarter-wave plate 21, it travels toward the collecting reflection mirror 24 as light Lc3 whose polarization has changed from p-polarized light p to right-rotating circularly polarized light c. Furthermore, when the light Lc3 is reflected by the collecting reflection mirror 24, it travels toward the quarter-wave plate 21 as light Lc4 whose polarization has changed from right-rotating circularly polarized light c to left-rotating circularly polarized light c. When the light Lc4 passes through the quarter-wave plate 21 again, it is reflected by the inner surface 42b of the second prism 42 as light Lc5 whose polarization has changed from right-handed circularly polarized light c to s-polarized light s, and proceeds toward the polarization separation film 45A. Here, the luminance of the light Lc5 is the same as the luminance of the light Lc2, and is 50% of the luminance of the image light ML at the time of emission. Next, the light Lc5 is reflected by the polarization separation film 45A and proceeds toward the exit pupil EP as light Lc6. Here, the luminance of the light Lc6 is the same as the luminance of the light Lc5 reflected by the polarization separation film 45A, and is 50% of the luminance of the image light ML at the time of emission.

[0054] Furthermore, as shown in FIG. 12, the external light OL is incident on the second lens 53 from the transmission mirror 56 as light Le1. The brightness of the external light OL immediately before it is incident on the transmission mirror 56 is 100%. However, the brightness of the image light ML at the time of emission does not necessarily match the brightness of the external light OL immediately before it is incident. The light Le1 passes through the transmission mirror 56 and travels to the quarter-wave plate 51 as light Le2. Here, when the transmittance of the transmission mirror 56 is 50%, the brightness of the light Le2 is 50% of the brightness of the external light OL immediately before it is incident. The light Le1 and the light Le2 include a left-handed circularly polarized light c component and a right-handed circularly polarized light c component. After passing through the quarter-wave plate 51, the light Le2 is incident on the second prism 42 from the outer surface 42c as light Le3 and travels to the polarization separation film 45A. The left-handed circularly polarized light c component and the right-handed circularly polarized light c component of the light Le2 are changed into an s-polarized light s component and a p-polarized light p component of the light Le3 by passing through the quarter-wave plate 51. The p-polarized light p component of the light Le3 passes through the polarization separation film 45A and proceeds to the exit pupil EP as light Le4. Here, the luminance of the light Le4 is 50% of the luminance of the light Le3 immediately before passing through the polarization separation film 45A, and is 25% of the luminance of the external light OL immediately before it is incident.

[0055] From the above calculations, among the lights that reach the exit pupil EP in FIG. 12, the sum of the brightness of light Lb6 and light Lc6 originating from the image light ML is 75% of the brightness of the image light ML at the time of emission, and the brightness of light Le4 originating from the external light OL is 25% of the brightness of the external light OL immediately before incidence.

[0056] The display unit 120 according to the first comparative example corresponds to the display units 20a and 20b according to the present embodiment shown in Fig. 12 with the following modifications: the second ¼ wavelength plate 21 and the light collecting reflection mirror 24 are removed, and the polarization separation film 45A is replaced with a half mirror.

[0057] In the display unit 120 according to the first comparative example, the brightness of the image light ML at the time of emission from the display element 11 is set to 100%. The image light ML emitted from the display element 11 is reflected twice by the inner surface 41b and the outer surface 41c of the first prism 41 as light La1 containing an s-polarized light component s and a p-polarized light component p, and proceeds to the half mirror. A part of the light La1 is reflected by the half mirror and proceeds to the quarter-wave plate 51 as light Lb2, and after passing through the quarter-wave plate 51, proceeds to the transmission mirror 56 as light Lb3. Here, when the reflectance of the half mirror is 50%, the brightness of the light Lb2 and Lb3 is 50% of the brightness of the light La1 immediately before being reflected by the half mirror, and is 50% of the brightness of the image light ML at the time of emission. Next, the light Lb3 is reflected by the transmission mirror 56 and travels as light Lb4 toward the quarter-wave plate 51, and after passing through the quarter-wave plate 51, travels as light Lb5 toward the half mirror. Here, if the transmittance of the transmission mirror 56 is 50%, the luminance of the light Lb4 and Lb5 is 50% of the luminance of the light Lb4 immediately before being reflected by the transmission mirror 56, and is 25% of the luminance of the image light ML at the time of emission. Next, a part of the light Lb5 passes through the half mirror and travels as light Lb6 toward the exit pupil EP. Here, if the transmittance of the half mirror is 50%, the luminance of the light Lb6 is 50% of the luminance of the light Lb5 immediately before being transmitted through the half mirror, and is 12.5% ​​of the luminance of the image light ML at the time of emission.

[0058] Furthermore, in the first comparative example, the external light OL is incident on the second lens 53 from the transmission mirror 56 as light Le1. The brightness of the external light OL immediately before it is incident on the transmission mirror 56 is set to 100%. However, the brightness of the image light ML at the time of emission does not necessarily match the brightness of the external light OL immediately before it is incident. The light Le1 passes through the transmission mirror 56 and travels to the quarter-wave plate 51 as light Le2. Here, when the transmittance of the transmission mirror 56 is 50%, the brightness of the light Le2 is 50% of the brightness of the external light OL immediately before it is incident. The light Le1 and the light Le2 include a left-handed circularly polarized light c component and a right-handed circularly polarized light c component. After passing through the quarter-wave plate 51, the light Le2 is incident on the second prism 42 from the outer surface 42c as light Le3 and travels to the half mirror. The left-handed circularly polarized light c component and the right-handed circularly polarized light c component of the light Le2 are changed into an s-polarized light s component and a p-polarized light p component of the light Le3 by passing through the quarter-wave plate 51. A part of the s-polarized light s component and a part of the p-polarized light p component contained in the light Le3 are transmitted through the half mirror regardless of the polarization direction, and proceed toward the exit pupil EP as light Le4. Here, if the transmittance of the half mirror is 50%, the luminance of the light Le4 is 50% of the luminance of the light Le3 immediately before it passes through the half mirror, and is 25% of the luminance of the external light OL at the time of incidence.

[0059] From the above calculations, of the light rays that reach the exit pupil EP in the first comparative example, the luminance of the light Lb6 originating from the image light ML is 12.5% ​​of the luminance of the image light ML at the time of emission, and the luminance of the light Le4 originating from the external light OL is 25% of the luminance of the external light OL immediately before incidence. Comparing this embodiment shown in Fig. 12 with the first comparative example, the utilization efficiency of the image light ML from the display element 11 according to this embodiment is six times that of the image light ML from the display element 11 according to the first comparative example.

[0060] The display unit 220 according to the second comparative example corresponds to the display units 20a and 20b according to the present embodiment shown in Fig. 12 with the following modifications: the second quarter-wave plate 21 and the light-collecting reflection mirror 24 are removed, and a polarization separation film is added between the lens portion 32 of the first lens 30 and the third lens 44 of the first prism 41.

[0061] In the display unit 220 according to the second comparative example, the brightness of the image light ML at the time of emission from the display element 11 is set to 100%. The image light ML emitted from the display element 11 heads toward the polarization separation film as light La1 including an s-polarized light s component and a p-polarized light p component. The s-polarized light s component of the light La1 passes through the polarization separation film, is reflected twice by the inner surface 41b and the outer surface 41c of the first prism 41, and heads toward the polarization separation film 45A. Here, the brightness of the s-polarized light s component of the light La1 is 50% of the brightness of the light La1 immediately before passing through the polarization separation film 15, and is 50% of the brightness of the image light ML at the time of emission. Next, the s-polarized light s component of the light La1 is reflected by the polarization separation film 45A, heads toward the quarter-wave plate 51 as light Lb2, and heads toward the transmission mirror 56 as light Lb3 that has passed through the quarter-wave plate 51. Here, the brightness of the light Lb3 is the same as the brightness of the s-polarized s component of the light La1 immediately before it is reflected by the polarization separation film 45A, and is 50% of the brightness of the image light ML at the time of emission. The s-polarized s of the light Lb2 is changed to the right-rotating circularly polarized light c of the light Lb3 by passing through the quarter-wave plate 51. Next, the light Lb3 is reflected by the transmission mirror 56 and travels to the polarization separation film 45A as the light Lb4. Here, when the transmittance and reflectance of the transmission mirror 56 are 50%, the brightness of the light Lb4 is 50% of the brightness of the light Lb3 immediately before it is reflected by the transmission mirror 56, and is 25% of the brightness of the image light ML at the time of emission. Moreover, the right-rotating circularly polarized light c of the light Lb3 is changed to the left-rotating circularly polarized light c of the light Lb4 by being reflected by the transmission mirror 56. Furthermore, when the light Lb3 passes through the quarter-wave plate 51 again, it heads toward the polarization separation film 45A as light Lb5 whose polarization has changed from left-handed circularly polarized light c to p-polarized light p. Next, the light Lb5 passes through the polarization separation film 45A and heads toward the exit pupil EP as light Lb6. Here, the luminance of the light Lb6 is the same as the luminance of the light Lb5 immediately before passing through the polarization separation film 45A, and is 25% of the luminance of the image light ML at the time of emission.

[0062] 12, the external light OL is incident on the second lens 53 from the transmission mirror 56 as light Le1, part of the light Le1 travels as light Le2 toward the quarter-wave plate 51, and after passing through the quarter-wave plate 51 travels as light Le3 toward the polarization separation film 45A, part of the light Le3 passes through the polarization separation film 45A as light Le4, and reaches the exit pupil EP. The luminance of the light Le3 in the first comparative example is 25% of the luminance of the external light OL immediately before it is incident, as in the case of the light Le4 shown in FIG.

[0063] From the above calculations, of the light rays that reach the exit pupil EP in the second comparative example, the luminance of the light Lb6 originating from the image light ML is 25% of the luminance of the image light ML at the time of emission, and the luminance of the light Le4 originating from the external light OL is 25% of the luminance of the external light OL immediately before incidence. Comparing this embodiment shown in Fig. 12 with the second comparative example, the utilization efficiency of the image light ML from the display element 11 according to this embodiment is three times that of the image light ML from the display element 11 according to the second comparative example.

[0064] Thus, according to this embodiment, the components of the image light ML emitted by the display element 11 that do not reach the exit pupil EP in each comparative example are effectively utilized by making them reach the exit pupil EP through the second focusing reflector CR2 provided inside the second prism 42, thereby improving the utilization efficiency of the image light ML from the display element 11.

[0065] Fig. 13 is a diagram for explaining an example of the structure of the prism light-guiding member 48. Fig. 14 is a diagram for explaining an example of the assembly of the prism light-guiding member 48. The prism light-guiding member 48 is formed by joining four parts 411, 421, 422, and 423. The number of parts constituting the prism light-guiding member 48 is not limited to four, and the number of parts can be changed appropriately by changing the shapes of the parts. The third lens 44 may be joined in advance to the part 411 constituting the first prism 41.

[0066] The second prism 42 is a combination of an upper second part 421, a lower fourth part 423, and an intermediate third part 422. The second quarter-wave plate 21 may be bonded to the second part 421 in advance. Alternatively, the second quarter-wave plate 21 may be bonded to the third part 422 in advance. The fourth part 423 may have the concave surface 24a of the light-collecting reflection mirror 24 formed in advance. Alternatively, the concave surface 24a of the light-collecting reflection mirror 24 may be formed in the third part 422 in advance. In either case, the prism light-guiding member 48 is formed by bonding the first part 411, the second part 421, the third part 422, and the fourth part 423. These bonding may be performed using an adhesive.

[0067] With reference to FIG. 15, an example of the structure and assembly of the first display unit 20a constituting the first virtual image display device 100A will be described. In FIG. 15, regions ER1 to ER5 are perspective views for explaining the assembly process of the first display unit 20a. First, as shown in region ER1, the first prism 41 and the second prism 42 are prepared as described above. The first prism 41 and the second prism 42 are formed of, for example, glass or resin. The third lens 44 may be bonded to the first prism 41 in advance. A polarization separation film 45A as the inclined mirror unit 45 is formed on the inclined surface 41d of the first prism 41 by vacuum deposition or other techniques. As shown in region ER2, the first prism 41 and the second prism 42 are bonded to each other at the inclined surfaces 41d and 42d to obtain the prism light-guiding member 48 or the first flat-plate member 40. Next, as shown in region ER3, the quarter-wave plate 51 is attached to the outer surfaces 41c, 42c of the first flat-plate member 40 shown in regions ER1, ER2 so as to face each other. At this time, a pair of spacers 61, which are thin adhesives, are disposed between the outer surfaces 41c, 42c of the first flat-plate member 40 and the quarter-wave plate 51, and a gap is formed between the outer surfaces 41c, 42c of the first flat-plate member 40 and the quarter-wave plate 51. As shown in region ER4, the second lens 53 is attached to an appropriate position on the surface of the quarter-wave plate 51. A transmission mirror 56 is formed on the surface of the second lens 53. Next, as shown in region ER5, an optical element 58 is bonded to the quarter-wave plate 51 and the like. At this time, the compensation lens 54 of the optical element 58 and the second lens 53 are positioned and fitted together to be bonded to each other. Also, the compensation plate 55 of the optical element 58 and the quarter-wave plate 51 are bonded to each other. This completes the assembly of the first display unit 20a.

[0068] In the above description, the first display unit 20a is produced by assembling the second flat plate-like member 50 on the first flat plate-like member 40, but the first flat plate-like member 40 and the second flat plate-like member 50 may be assembled separately, and then the first flat plate-like member 40 and the second flat plate-like member 50 may be joined together finally.

[0069] The virtual image display devices 100A, 100B or the optical unit 100 of the first embodiment described above is a direct virtual image type virtual image display device or optical unit, and 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, a polarization separation film 45A that is provided at the joint between the first prism 41 and the second prism 42 and serves as an oblique mirror section 45 that reflects a first portion of the image light ML guided in the first prism 41, and a plano-convex film 45A that is arranged to face an outer surface 41c of the first prism 41 onto which the first portion of the image light ML reflected by the oblique mirror section is incident. the second lens 53, a transmitting mirror 56 formed on a convex surface 53g of the second lens 53 and reflecting a portion of the image light ML reflected by the oblique mirror portion 45 toward the oblique mirror portion, a first ¼ wavelength plate 51 arranged between the outer surface 41c of the first prism 41 and the second lens 53, a compensating lens 54 having a concave surface 54f bonded to the convex surface 53g of the second lens 53 via the transmitting mirror 56 and a plane 55g parallel to the outer surface 41c of the first prism 41, a collecting reflection mirror 24 arranged within the second prism 42 and reflecting a second portion of the image light ML that is transmitted through the oblique mirror portion 45 and reflected by the inner surface 42b of the second prism 42, and a second ¼ wavelength plate 21 arranged between the inner surface 42b of the second prism 42 and the collecting reflection mirror 24.

[0070] In the above virtual image display devices 100A, 100B or the optical unit 100, a virtual image is directly formed without forming an intermediate image, so that the first lens 30, the second lens 53, and the transmitting mirror 56 ensure refractive power, and it is possible to ensure a magnification ratio while suppressing an increase in the optical path length and to avoid an increase in the size of the optical system. Even if a two-sided reflecting member is present in front of the eye, by providing the second light collecting reflecting portion CR2 inside the second prism 42, the utilization efficiency of the image light ML from the display element 11 is improved, the luminance of the image light ML at the exit pupil EP is increased, and the relative luminance of the image light ML to the luminance of the external light OL is also increased.

[0071] In the first embodiment described above, a configuration example has been shown assuming the use of a non-polarized panel such as an organic EL display as the display element 11. As a variation of this configuration example, the display element 11 may be a micro LED or a liquid crystal laser backlight. However, when the light source of the display element 11 emits image light ML in a state other than the non-polarized state, for example, a quarter-wave plate may be added between the first lens 30 and the third lens 44 so that a desired polarization state can be obtained in the polarization separation film 45A or the like.

[0072] In the first embodiment described above, a configuration example in which the reflectance of the collecting reflector 24 is 100% has been shown. As a modified example of this configuration example, the collecting reflector 24 may be a half mirror with a reflectance of less than 100% or an angle selection film with a reflectance that varies depending on the angle of incidence. When an angle selection film is used as the collecting reflector 24, the reflectance of the angle selection film may be increased as the angle of incidence is smaller, such as light incident on the collecting reflector 24 from the front, and the transmittance of the angle selection film may be increased as the angle of incidence is larger, such as light incident on the collecting reflector 24 from a tilted angle. By using such an angle selection film as the collecting reflector 24, it is possible to achieve both the see-through property of the collecting reflector 24 with respect to the outside light OL and high utilization efficiency with respect to the image light ML.

[0073] Second Embodiment Hereinafter, the virtual image display device etc. of the second embodiment 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 the description of the parts common to the virtual image display device of the first embodiment will be omitted.

[0074] As shown in Fig. 16, the virtual image display devices 100A and 100B according to this embodiment include a half mirror 45B as the diagonal mirror section 45 instead of the polarization separation film 45A of the first embodiment. The half mirror 45B reflects and partially transmits a part of the image light ML and a part of the external light OL. As an example, the reflectance and transmittance of the half mirror 45B may be 50%. Hereinafter, the polarization separation film 45A and the half mirror 45B may be collectively referred to as the diagonal mirror section 45.

[0075] The brightness of the image light ML at the time of emission from the display element 11 is 100%. The light La1 as the image light ML emitted from the display element 11 is reflected twice by the inner surface 41b of the first prism 41 and the outer surface 41c of the first prism 41, and heads toward the half mirror 45B. A part of the light La1 is reflected by the half mirror 45B, heads toward the quarter-wave plate 51 as light Lb2, and heads toward the transmission mirror 56 as light Lb3 that has passed through the quarter-wave plate 51. The brightness of the light Lb2 and Lb3 is 50% of the light La1 immediately before being reflected by the half mirror 45B, and is 50% of the brightness of the image light ML at the time of emission. Next, a part of the light Lb3 is reflected by the transmission mirror 56, heads toward the quarter-wave plate 51 as light Lb4, and heads toward the half mirror 45B as light Lb5 that has passed through the quarter-wave plate 51. When the reflectance of the transmission mirror 56 is 50%, the brightness of the light Lb4 and Lb5 is 50% of the brightness of the light Lb3 immediately before it is reflected by the transmission mirror 56, and is 25% of the brightness of the image light ML at the time of emission. Next, a part of the light Lb5 passes through the half mirror 45B and proceeds to the exit pupil EP as light Lb6. The brightness of the light Lb6 is 50% of the brightness of the light Lb5 immediately before it is transmitted through the half mirror 45B, and is 12.5% ​​of the brightness of the image light ML at the time of emission.

[0076] Another part of the light La1 as the image light ML emitted by the display element 11 passes through the half mirror 45B, travels as light Lc2 toward the quarter-wave plate 21, and travels as light Lc3 that has passed through the quarter-wave plate 21 toward the light-collecting reflecting mirror 24. The luminance of the light Lc2 and Lc3 is 50% of the luminance of the light La1 immediately before passing through the half mirror 45B, and is 50% of the luminance of the image light ML at the time of emission. Next, the light Lc3 is reflected by the light-collecting reflecting mirror 24, travels as light Lc4 toward the quarter-wave plate 21, and travels as light Lc5 that has passed through the quarter-wave plate 21 toward the half mirror 45B. The luminance of the light Lc4 and Lc5 is the same as the luminance of the light Lc3 immediately before being reflected by the light-collecting reflecting mirror 24, and is 50% of the luminance of the image light ML at the time of emission. Next, a portion of the light Lc5 is reflected by the half mirror 45B and travels as light Lc6 toward the exit pupil EP. The luminance of the light Lc6 is 50% of the luminance of the light Lc5 immediately before it is reflected by the half mirror 45B, and 25% of the luminance of the image light ML at the time of emission.

[0077] Furthermore, the external light OL is incident on the second lens 53 from the transmission mirror 56 as light Le1. The brightness of the external light OL immediately before it is incident on the transmission mirror 56 is set to 100%. However, the brightness of the image light ML at the time of emission does not necessarily match the brightness of the external light OL immediately before it is incident. Next, the light Le1 passes through the transmission mirror 56, travels toward the quarter-wave plate 51 as light Le2, and travels toward the half mirror 45B as light Le3 that has passed through the quarter-wave plate 51. When the transmittance of the transmission mirror 56 is 50%, the brightness of the light Le2 and Le3 is 50% of the brightness of the light Le1 immediately before it is transmitted through the transmission mirror 56, and is 50% of the brightness of the external light OL immediately before it is incident. Next, a part of the light Le3 passes through the half mirror 45B, and travels toward the exit pupil EP as light Le4. The luminance of the light Le4 is 50% of the luminance of the light Le3 immediately before it passes through the half mirror 45B, and is 25% of the luminance of the external light OL immediately before it is incident thereon.

[0078] From the above calculations, among the lights that reach the exit pupil EP in Figure 16, the sum of the brightness of light Lb6 and light Lc6 originating from the image light ML is 37.5% of the brightness of the image light ML at the time of emission, and the brightness of light Le4 originating from the external light OL is 25% of the brightness of the external light OL immediately before it is incident.

[0079] Fig. 17 shows another example of the configuration of the virtual image display devices 100A and 100B according to the present embodiment shown in Fig. 16. The virtual image display devices 100A and 100B in Fig. 17 correspond to the virtual image display devices 100A and 100B shown in Fig. 16 with the following changes added. That is, a polarization separation film 45C is provided as the diagonal mirror section 45 instead of the half mirror 45B. The polarization separation film 45C reflects 50% of the s-polarized light s component contained in the incident light and transmits the remaining 50%. In addition, the polarization separation film 45C transmits the p-polarized light p component contained in the incident light.

[0080] The brightness of the image light ML at the time of emission from the display element 11 is set to 100%. The light La1 as the image light ML emitted from the display element 11 is reflected twice by the inner surface 41b of the first prism 41 and the outer surface 41c of the first prism 41, and travels toward the polarization separation film 45C. A part of the s-polarized light s component of the light La1 is reflected by the polarization separation film 45C and travels toward the quarter-wave plate 51 as light Lb2. The polarization of the light Lb2 is s-polarized light s, and the brightness of the light Lb2 is 50% of the brightness of the s-polarized light s component contained in the light La1 immediately before it is reflected by the polarization separation film 45C, and is 25% of the brightness of the image light ML at the time of emission. When the light Lb2 passes through the quarter-wave plate 51, it travels toward the transmission mirror 56 as light Lb3 whose polarization has changed from s-polarized light s to circularly polarized light c. Next, a part of the light Lb3 is reflected by the transmission mirror 56 and travels to the quarter-wave plate 51 as light Lb4. When the reflectance of the transmission mirror 56 is 50%, the brightness of the light Lb4 is 50% of the brightness of the light Lb3 immediately before it is reflected by the transmission mirror 56, and is 12.5% ​​of the brightness of the image light ML at the time of emission. Here, when the light Lb4 passes through the quarter-wave plate 51, it travels to the polarization separation film 45C as light Lb5 in which the circularly polarized light c has been converted to p-polarized light p. Next, the light Lb5 passes through the polarization separation film 45C and travels to the exit pupil EP as light Lb6. The brightness of the light Lb6 is the same as the brightness of the light Lb5 immediately before it is transmitted through the polarization separation film 45C, and is 12.5% ​​of the brightness of the image light ML at the time of emission.

[0081] Furthermore, a portion of the s-polarized s component and the p-polarized p component contained in the light La1 as the image light ML emitted by the display element 11 are transmitted through the polarization separation film 45C and proceed as light Lc2 to the quarter-wave plate 21. The brightness of the light Lc2 is the sum of 50% of the brightness of the s-polarized s component contained in the light La1 immediately before it is transmitted through the polarization separation film 45C and 100% of the brightness of the p-polarized p component contained in the light La1 immediately before it is transmitted through the polarization separation film 45C, and is 75% of the brightness of the image light ML at the time of emission. After passing through the quarter-wave plate 21, the light Lc2 proceeds to the collecting reflection mirror 24 as light Lc3 in which the s-polarized s component and the p-polarized p component have been changed into a right-handed circularly polarized c component and a left-handed circularly polarized c component, respectively. The luminance of the light Lc3 is the sum of the luminance of the right-handed circularly polarized light c component and the luminance of the left-handed circularly polarized light c component, and is 75% of the luminance of the image light ML at the time of emission. Next, the light Lc3 is reflected by the collecting reflection mirror 24 and travels to the quarter-wave plate 21 as light Lc4. Due to reflection by the collecting reflection mirror 24, the right-handed circularly polarized light c component contained in the light Lc3 changes to the left-handed circularly polarized light c component contained in the light Lc4, and the left-handed circularly polarized light c component contained in the light Lc3 changes to the right-handed circularly polarized light c component contained in the light Lc4. The luminance of the light Lc4 is the sum of the luminance of the left-handed circularly polarized light c component and the luminance of the right-handed circularly polarized light c component, and is 75% of the luminance of the image light ML at the time of emission. The light Lc5 after the light Lc4 passes through the quarter-wave plate 21 includes a p-polarized p component resulting from a change in the left-handed circularly polarized c component of the light Lc4, and an s-polarized s component resulting from a change in the right-handed circularly polarized c component of the light Lc4. Therefore, the luminance of the p-polarized p and s-polarized s components included in the light Lc5 after passing through the quarter-wave plate 21 is 25% and 50% of the luminance of the image light ML at the time of emission, respectively. Next, a part of the s-polarized s component included in the light Lc5 is reflected by the polarization separation film 45C and travels toward the exit pupil EP as light Lc6. The luminance of the light Lc6 is 50% of the luminance of the s-polarized s component included in the light Lc5 immediately before it is reflected by the polarization separation film 45C, and is 25% of the luminance of the image light ML at the time of emission.

[0082] Furthermore, the external light OL is incident on the second lens 53 from the transmission mirror 56 as light Le1. The brightness of the external light OL immediately before it is incident on the transmission mirror 56 is 100%. However, the brightness of the image light ML at the time of emission does not necessarily match the brightness of the external light OL immediately before it is incident. Next, the light Le1 passes through the transmission mirror 56 and travels to the quarter-wave plate 51 as light Le2. When the transmittance of the transmission mirror 56 is 50%, the brightness of the light Le2 is 50% of the brightness of the light Le1 immediately before it is transmitted through the transmission mirror 56, and is 50% of the brightness of the external light OL immediately before it is incident. The light Le1 and the light Le2 include a left-handed circularly polarized light c component and a right-handed circularly polarized light c component. After passing through the quarter-wave plate 51, the light Le2 is incident on the second prism 42 from the outer surface 42c as light Le3 and travels to the polarization separation film 45C. The left-handed circularly polarized light c component and the right-handed circularly polarized light c component of the light Le2 are changed into an s-polarized light s component and a p-polarized light p component of the light Le3 by passing through the quarter-wave plate 51. Next, a part of the s-polarized light s component contained in the light Le3 and the p-polarized light p component contained in the light Le3 are transmitted through the polarization separation film 45C and proceed to the exit pupil EP as light Le4. The p-polarized light p component of the light Le4 is transmitted through the polarization separation film 45C, and a part of the s-polarized light s component is transmitted through the polarization separation film 45C. When the transmittance of the polarization separation film 45C is 100% for p-polarized light p and 50% for s-polarized light s, the luminance of the p-polarized light p component of the light Le4 is 25% of the luminance of the external light OL immediately before incidence, and the luminance of the s-polarized light s component is 12.5% ​​of the luminance of the external light OL immediately before incidence. The luminance of the light Le4 is 75% of the luminance of the light Le3 immediately before it passes through the polarization separation film 45C, and is 37.5% of the luminance of the external light OL immediately before it is incident thereon.

[0083] From the above calculations, among the lights that reach the exit pupil EP in Figure 16, the sum of the brightness of light Lb6 and light Lc6 originating from the image light ML is 37.5% of the brightness of the image light ML at the time of emission, and the brightness of light Le4 originating from the external light OL is 37.5% of the brightness of the external light OL immediately before it is incident.

[0084] Thus, in this embodiment, in both the configuration examples shown in Figures 16 and 17, compared to the two comparative examples compared with Figure 12, the utilization efficiency of the image light ML from the display element 11 is improved by effectively utilizing the components of the image light ML emitted by the display element 11 that do not reach the exit pupil EP in each comparative example by making them reach the exit pupil EP through the second focusing reflection portion CR2 provided inside the second prism 42.

[0085] In this embodiment, there is a possibility that undesired stray light Ga may be generated by a part of the image light ML traveling along the optical path shown in FIG. 18. In order to suppress the generation of such stray light Ga, an angle-selective mirror having a different transmittance depending on the incident angle of the incident light may be used as a part or all of the reflection areas included in the half mirror 45B in FIG. 16, the polarization separation film 45C in FIG. 17, and the transmission mirror 56 in FIG. 16 and FIG. 17. The angle-selective mirror transmits so-called flat light, that is, light with an incident angle larger than a predetermined threshold, without reflecting it, thereby suppressing the generation of stray light Ga. As an example, the transmittance of the corresponding reflection area is set higher than a predetermined threshold so that a part of the image light that is incident on the oblique mirror section 45 and / or the transmission mirror 56 at an incident angle larger than a predetermined threshold is transmitted without being reflected, thereby suppressing the generation of stray light originating from the image light.

[0086] In addition, in the virtual image display devices 100A and 100B according to the present embodiment shown in Figures 16 and 17, depending on the type of display element 11, for example, a quarter-wave plate may be added between the first lens 30 and the third lens 44 so that a desired polarization state is obtained for the image light ML in the polarization separation film 45A, etc.

[0087] Third Embodiment Hereinafter, the virtual image display device of the third embodiment will be described. Note that the virtual image display device of the third embodiment is a partially modified version of the virtual image display device of the first embodiment, and a description of the parts common to the virtual image display device of the first embodiment will be omitted.

[0088] A case where the collecting reflection mirror 24 of the first and second embodiments described above is divided into a plurality of parts will be described with reference to Fig. 19 and Fig. 20. The result of observing the collecting reflection mirror 24 in the observation direction OD shown in Fig. 19 is shown in Fig. 20.

[0089] Region FR1 in Fig. 20 shows the shape of the collecting reflecting mirror 24 according to the first and second embodiments. The collecting reflecting mirror 24 in Fig. 19 is integrated into one concave surface. Region FR2 in Fig. 20 shows the shape of the collecting reflecting mirror 25 according to this embodiment. The collecting reflecting mirror 25 in Fig. 20 includes a plurality of partially reflecting surfaces 25a, 25b, 25c. The multiple partially reflecting surfaces 25a, 25b, 25c reflect components of the image light ML that have passed through the polarization separation films 45A and 45C or the half mirror 45B as the oblique mirror portion, respectively, to a plurality of regions included in the exit pupil EP.

[0090] By appropriately dividing the light collecting reflection mirror 25 into a plurality of partial reflection surfaces 25a, 25b, and 25c, it is possible to adjust the luminance distribution of the image light ML observed in the exit pupil EP to a desired distribution. In addition, by appropriately setting the positions and shapes of the plurality of partial reflection surfaces 25a, 25b, and 25c, it is also possible to reduce the luminance unevenness of the image light ML observed in the exit pupil EP. As an example, the luminance of the image light ML observed in the exit pupil EP may be adjusted by selectively arranging the partial reflection surfaces 25a, 25b, and 25c at positions where the image light ML is reflected toward a portion of the exit pupil EP where the luminance of the image light ML is relatively low. Furthermore, the distribution of the reflectance and transmittance of each of the plurality of partial reflection surfaces 25a, 25b, and 25c may be set so as to reduce the luminance unevenness. As an example, the luminance of the image light ML observed in the exit pupil EP may be adjusted by setting the reflectance of the area reflecting the image light ML relatively high (or the transmittance relatively low) among the partially reflecting surfaces 25a, 25b, and 25c at a position where the image light ML is reflected toward a portion of the exit pupil EP where the luminance of the image light ML is relatively low. Also, the luminance of the image light ML observed in the exit pupil EP may be adjusted by setting the reflectance of the area reflecting the image light ML relatively low (or the transmittance high) among the partially reflecting surfaces 25a, 25b, and 25c at a position where the image light ML is reflected toward a portion of the exit pupil EP where the luminance of the image light ML is relatively high. Also, the positions of each of the multiple partially reflecting surfaces 25a, 25b, and 25c in the second prism 42 may be finely adjusted in the direction of the observation direction OD. In this way, the positions, shapes, reflectivities and transmittances of the multiple partial reflecting surfaces 25a, 25b, 25c of the focusing reflecting mirror 25 may be appropriately set so as to reduce brightness unevenness when a first portion of the image light ML traveling along the first optical path P1 and a second portion traveling along the second optical path P2 reach the inner surface 42b of the second prism 42, depending on the brightness distribution when a first portion of the image light ML traveling along the first optical path P1 reaches the inner surface 42b of the second prism 42.

[0091] In this way, by replacing the light-collecting reflecting mirror 24 with the light-collecting reflecting mirror 25 having the plurality of partially reflecting surfaces 25a, 25b, and 25c, it becomes possible to adjust the brightness and reduce unevenness in the brightness.

[0092] [Fourth embodiment] Hereinafter, the virtual image display device etc. of the fourth embodiment will be described. 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 the description of the parts common to the virtual image display device of the first embodiment will be omitted.

[0093] 21 and 22, it will be described how chromatic aberration can be corrected by changing the second lens 53 in the first and second embodiments described above to a lens group made of a plurality of materials. Region GR1 in Fig. 22 shows the optical path of light incident on the second lens 53 in the first and second embodiments. Region GR2 in Fig. 22 shows the optical path of light incident on the second lens 530 according to this embodiment.

[0094] As shown in FIG. 21, the second lens 530 according to this embodiment includes a first partial lens 531 and a second partial lens 532. The first partial lens 531 is disposed at a position facing the first quarter-wave plate 51. The second partial lens 532 is disposed between the first partial lens 531 and the transmission mirror 56. The first partial lens 531, the second partial lens 532, and the transmission mirror 56 may be integrated. In this case, the first partial lens 531 is a plano-concave lens having a flat surface and a concave surface, and the second partial lens 532 is a convex lens having two convex surfaces, and the concave surface of the first partial lens 531 and one of the convex surfaces of the second partial lens 532 may be complementary. The shape obtained by bonding the first partial lens 531 and the second partial lens 532 according to this embodiment may be the same as the shape of the second lens 53 according to the first and second embodiments.

[0095] 22, by appropriately selecting the material of the first partial lens 531 and the second partial lens 532, the optical path in the second lens 530 consisting of the first partial lens 531 and the second partial lens 532 can be changed from the second lens 53 consisting of a single material, and as a result, chromatic aberration can be corrected without changing the optical path length. However, from the viewpoint of making the first optical path length and the second optical path length approximately the same, it is preferable that the material of the second partial lens 532 is the same as the material of the second prism 42.

[0096] [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.

[0097] 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 virtual image display device 100B in front of the eyes by a support device 100C.

[0098] The compensation plate 55 may 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 compensation lens .

[0099] In the first flat plate member 40, the third lens 44 may be omitted.

[0100] Instead of bonding the first prism 41 and the third lens 44 together, the first prism 41 may be formed by integrating a lens portion corresponding to the third lens 44.

[0101] 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.

[0102] A polarizing plate may be provided between the first lens 30 and the third lens 44 depending on the type of the first image-forming element 11a that is the light source.

[0103] The first image forming element 11a may be a scanning type display device having a laser light source and a scanner mirror.

[0104] A half mirror may be used in place of the polarization separation film 45A.

[0105] A virtual image display device in a specific aspect is a direct virtual image type virtual image display device, and includes a display element that emits image light, a first lens into which the image light from the display element is incident, a first prism into 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-like prism light-guiding member, an inclined mirror portion that is provided at the joint between the first prism and the second prism and that reflects a first portion of the image light guided in the first prism, a plano-convex second lens that is disposed opposite to the outer surface of the first prism into which the first portion of the image light reflected by the inclined mirror portion is incident, and a second lens that is plano-convex and arranged opposite to the outer surface of the first prism. The optical element includes a transmitting mirror formed on the convex surface of the lens and reflecting a portion of the image light reflected by the oblique mirror portion toward the oblique mirror portion, a first 1 / 4 wavelength plate arranged between the outer surface of the first prism and the second lens, a compensating lens having a concave surface joined to the convex surface of the second lens 53 via the transmitting mirror and a surface parallel to the outer surface of the first prism, a focusing reflective mirror arranged within the second prism and reflecting a second portion of the image light that passes through the oblique mirror portion and is reflected by the inner surface of the second prism, and a second 1 / 4 wavelength plate arranged between the inner surface of the second prism and the focusing reflective mirror.

[0106] In the virtual image display device, since a virtual image is directly formed without forming an intermediate image, the first lens, the second lens, and the transmission mirror ensure refractive power, and the magnification is ensured while suppressing an increase in the optical path length, thereby making it possible to avoid an increase in the size of the optical system. By having a light-collecting reflection mirror and a second 1 / 4 wavelength plate, in addition to the first portion of the image light emitted from the display element that is reflected by the oblique mirror portion, the second portion that passes through the oblique mirror portion can also be made to reach the exit pupil EP and be effectively used. As a result, the utilization efficiency of the image light from the display element is improved, and the brightness of the image light that reaches the exit pupil can be increased even if two-sided reflecting members such as the oblique mirror portion 45 and the transmission mirror 56 are present in front of the eye.

[0107] In a specific embodiment of the virtual image display device, the oblique mirror section includes a polarization separation film that reflects the image light in accordance with the polarization direction, and the first lens, the prism light guide member, the polarization separation film, the second lens, the transmission mirror, and the first quarter-wave plate 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 transmission mirror, and it is possible to reduce the size of the prism light guide member, and it is also easy to reduce the size of the display element and the first lens.

[0108] In a specific embodiment of the virtual image display device, the light-collecting reflection mirror is disposed at a position where the length of a first optical path of a first portion of the image light reflected by the polarizing separation film, reflected by the transmission mirror, transmitted through the polarizing separation film, and reached the inner surface of the second prism is equal to the length of a second optical path of a second portion of the image light transmitted through the polarizing separation film, reflected by the light-collecting reflection mirror, reflected by the polarizing separation film, and reached the inner surface of the second prism. In this case, the magnification ratio of the image light traveling along the first optical path and the image light traveling along the second optical path can be made the same.

[0109] In a specific embodiment of the virtual image display device, the second prism and the second lens are made of substantially the same material, and the light-collecting reflecting mirror collects the second portion of the image light with substantially the same curvature as the curvature of the convex surface of the second lens when reflecting the second portion of the image light. In this case, the magnification ratio of the image light traveling through the first optical path and the image light traveling through the second optical path can be made the same.

[0110] In a specific embodiment of the virtual image display device, a part of the reflective regions of the diagonal mirror portion and the transmission mirror transmits a part of the second portion of the image light. In this case, it is possible to suppress the generation of stray light originating from the image light.

[0111] In a specific embodiment of the virtual image display device, the transmittance when a part of the reflection surface transmits a part of the second part of the image light varies depending on the angle of incidence at which the second part of the image light is incident on the reflection surface. In this case, the transmittance of the corresponding reflection area is set higher than a predetermined threshold so that a part of the image light that is incident on the oblique mirror section and / or the transmission mirror at an angle of incidence larger than a predetermined threshold is transmitted without being reflected, thereby suppressing the generation of stray light originating from the image light.

[0112] In a specific embodiment of the virtual image display device, the light-collecting reflective mirror includes a plurality of partially reflective surfaces that are arranged to reflect the second portion of the image light to different regions of the exit pupil, respectively. In this case, the luminance distribution of the light originating from the image light within the exit pupil can be adjusted.

[0113] In a specific embodiment of the virtual image display device, the reflectance of each of the partially reflective surfaces is set to reduce luminance unevenness when the first and second portions of the image light reach the inner surface of the second prism. In this case, it is possible to reduce unevenness in light caused by the image light in the exit pupil.

[0114] In a specific embodiment of the virtual image display device, the second lens includes a first partial lens facing the first quarter-wave plate and a second partial lens disposed between the first partial lens and the transmission mirror, and the second partial lens is made of the same material as the second prism. In this case, chromatic aberration can be suppressed by appropriately selecting the material of the first partial lens.

[0115] In a specific embodiment of a virtual image display device, the polarization separation film reflects a first portion of the image light arriving from the first prism that is s-polarized light, and transmits the first portion that has become p-polarized light after being reflected by the transmission mirror and passed back through the first quarter-wave plate.

[0116] In a specific embodiment of the virtual image display device, the polarization separation film transmits a second portion of the image light arriving from the first prism that is p-polarized light, and reflects the second portion that has been reflected by the focusing reflection mirror and passed through the second quarter-wave plate to become s-polarized light.

[0117] In a specific embodiment of the virtual image display device, the first quarter-wave plate is disposed at a distance from the outer surface of the first prism, which makes it easier to ensure internal reflection of the image light at the outer surface of the first prism.

[0118] In a specific embodiment, the virtual image display device further includes a compensation plate provided around the compensation lens and extending parallel to the prism light guiding member. In this case, external light incident on the periphery of the compensation lens can be observed in the same manner as external light incident inside the compensation lens.

[0119] In a specific embodiment, the optical unit is a direct virtual image type optical unit, and includes a first lens onto which image light from a display element that emits image light 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-like prism light-guiding member, an inclined mirror portion that is provided at the joint between the first prism and the second prism and that reflects a first portion of the image light guided in the first prism, a plano-convex second lens that is disposed opposite the outer surface of the first prism onto which the image light reflected by the inclined mirror portion is incident, and The optical element includes a transmitting mirror formed on a convex surface that reflects a portion of the image light reflected by the oblique mirror portion toward the oblique mirror portion, a first quarter-wave plate arranged between the outer surface of the first prism and the second lens, a compensating lens having a concave surface joined to the convex surface of the second lens via the transmitting mirror and a surface parallel to the outer surface of the first prism, a focusing reflective mirror arranged within the second prism that reflects a second portion of the image light that transmits through the oblique mirror portion and is reflected by the inner surface of the second prism, and a second quarter-wave plate arranged between the inner surface of the second prism and the focusing reflective mirror. [Explanation of symbols]

[0120] 11...display element, 20a, 20b...display section, 30...first lens, 30f...light entrance surface, 30g...light exit surface, 31...parallel plate, 32...lens section, 40...first plate-shaped member, 41b, 42b...inner surface, 41c, 42c...outer surface, 41d, 42d...inclined surface, 44...third lens, 45...angled mirror section, 45A...polarized light separation film, 45B...half mirror, 45C...polarized light separation film, 48...prism light guide member, 50...second plate-shaped member, 50c...inner surface, 51...quarter-wave plate, 52...cover member, 53f...flat surface, 53g...convex surface, 54...compensation lens, 54f... Concave surface, 54g, 55f, 55g... flat surface, 55... compensation plate, 56... transmission mirror, 58... optical element, 71... case, 90... user terminal, 100... optical unit, 100A... first virtual image display device, 100B... second virtual image display device, 100C... support device, 102a, 102b... display drive unit, 103a, 103b... combiner, AX... optical axis, CR1, CR2... light collecting and reflecting unit, CT... adhesive, DIS... direct virtual image optical system, EP... exit pupil, EY... eye, IS... imaging optical system, ML... image light, OL... external light, PP... pupil position, SS... joint, US... wearer

Claims

1. A direct virtual image type virtual image display device, A display element that emits image light; a first lens onto which the image light from the display element is incident; a first prism into 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-shaped prism light guide member; an inclined mirror portion provided at a joint between the first prism and the second prism, the inclined mirror portion reflecting a first portion of the image light guided through the first prism; a plano-convex second lens arranged to face an outer surface of the first prism onto which the first portion of the image light reflected by the oblique mirror portion is incident; a transmission mirror formed on a convex surface of the second lens and configured to reflect a portion of the image light reflected by the inclined mirror portion toward the inclined mirror portion; a first quarter wave plate disposed between the outer surface of the first prism and the second lens; a compensation lens having a concave surface bonded to the convex surface of the second lens via the transmission mirror and a surface parallel to the outer surface of the first prism; a light-collecting reflecting mirror disposed within the second prism and configured to reflect a second portion of the image light that is transmitted through the inclined mirror portion and reflected by an inner surface of the second prism; a second quarter-wave plate disposed between the inner surface of the second prism and the light-collecting reflecting mirror; A virtual image display device comprising:

2. the diagonal mirror portion includes a polarization separation film that reflects the image light in accordance with a polarization direction, the first lens, the prism light guiding member, the polarization separation film, the second lens, the transmission mirror, and the first quarter-wave plate constitute a simple microscope type imaging optical system that forms an erect image, The virtual image display device according to claim 1 , wherein the first prism internally reflects the image light twice while diverging the image light.

3. The light collecting reflecting mirror is a length of a first optical path of the first portion of the image light from being reflected by the polarization separation film to being reflected by the transmission mirror, transmitting through the polarization separation film, and reaching the inner surface of the second prism; a length of a second optical path of the second portion of the image light, which is transmitted through the polarization separation film, reflected by the light collecting reflection mirror, reflected by the polarization separation film, and reaches the inner surface of the second prism; The virtual image display device according to claim 2 , wherein the first and second electrodes are disposed at positions where the first and second electrodes are substantially equal to each other.

4. 4. The virtual image display device according to claim 3, wherein the second prism and the second lens are formed from approximately the same material, and the focusing reflection mirror, when reflecting the second portion of the image light, focuses the light with approximately the same curvature as the curvature of the convex surface of the second lens.

5. The virtual image display device according to claim 1 , wherein a part of a reflecting surface included in the diagonal mirror portion and / or the transmission mirror transmits a part of the second portion of the image light.

6. 6. The virtual image display device according to claim 5, wherein the transmittance when the portion of the reflective surface transmits the portion of the second portion of the image light varies depending on the angle of incidence at which the second portion of the image light is incident on the portion of the reflective surface.

7. the collecting reflector mirror includes a plurality of partially reflecting surfaces; The virtual image display device according to claim 1 , wherein the plurality of partially reflective surfaces are arranged so as to reflect the second portion of the image light toward different regions of an exit pupil, respectively.

8. 8. The virtual image display device according to claim 7, wherein the reflectivity of each of the plurality of partially reflective surfaces is set so as to reduce brightness unevenness when the first and second portions of the image light reach the inner surface of the second prism, in accordance with a brightness distribution when the first portion of the image light reaches the inner surface of the second prism.

9. The second lens is a first partial lens facing the first quarter-wave plate; a second partial lens disposed between the first partial lens and the transmission mirror; Equipped with The virtual image display device according to claim 1 , wherein the second partial lens is made of the same material as the second prism.

10. 3. The virtual image display device according to claim 2, wherein the polarization separation film reflects the first portion of the image light arriving from the first prism that is s-polarized and transmits the first portion that has become p-polarized by being reflected by the transmission mirror and passing through the first quarter-wave plate and returned.

11. 3. The virtual image display device according to claim 2, wherein the polarization separation film transmits the second portion of the image light arriving from the first prism that is p-polarized and reflects the second portion that has been reflected by the focusing reflection mirror and passed through the second quarter-wave plate to become s-polarized.

12. The virtual image display device according to claim 1 , wherein the first quarter-wave plate is disposed spaced apart from the outer surface of the first prism.

13. The virtual image display device according to claim 1 , further comprising a compensation plate provided around the compensation lens and extending parallel to the prism light guide member.

14. A direct virtual image type optical unit, a first lens having a positive refractive power and on which image light from a display element that emits image light is incident; a first prism into 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-shaped prism light guide member; an inclined mirror portion provided at a joint between the first prism and the second prism, the inclined mirror portion reflecting a first portion of the image light guided through the first prism; a plano-convex second lens arranged to face an outer surface of the first prism onto which the first portion of the image light reflected by the oblique mirror portion is incident; a transmission mirror formed on a convex surface of the second lens and configured to reflect a portion of the image light reflected by the inclined mirror portion toward the inclined mirror portion; a first quarter wave plate disposed between the outer surface of the first prism and the second lens; a compensation lens having a concave surface bonded to the convex surface of the second lens via the transmission mirror and a surface parallel to the outer surface of the first prism; a light-collecting reflecting mirror disposed within the second prism and configured to reflect a second portion of the image light that is transmitted through the inclined mirror portion and reflected by an inner surface of the second prism; a second quarter-wave plate disposed between the inner surface of the second prism and the light-collecting reflecting mirror; An optical unit comprising:

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