Virtual image display device and optical unit

Abstract

To prevent unwanted light from reaching the eyes. [Solution] The virtual image display device 100A comprises a display element 11, a first prism 41 into which image light ML from the display element 11 is incident, a second prism 42 joined to the first prism 41, a reflective polarizing element 45 provided via an adhesive member AD at the joint JS between the first prism 41 and the second prism 42 and reflecting at least a portion of the image light ML guided in the first prism 41, a lens having positive power and positioned opposite the outer surface of the first prism 41, a transmissive mirror 56 formed on the external side of the lens and partially reflecting the image light ML toward the reflective polarizing element 45, and a quarter-wave plate 51 positioned between the outer surface of the first prism 41 and the lens, wherein the reflective polarizing element 45 has an optical deflection portion LD in the end region EA near the inner surface opposite to the outer surface.

Description

Technical Field

[0001] The present invention relates to a direct virtual image type virtual image display device and an optical unit that enable observation of a virtual image.

Background Art

[0002] As a head-mounted display device, there is known one that includes a liquid crystal image display panel, a first lens, a beam splitter, a concave mirror, a quarter-wave plate, and a second lens, and image light from the liquid crystal image display panel is incident on the beam splitter and reflected by a beam splitting surface that reflects polarized light in a first direction, passes through the quarter-wave plate back and forth when reflected by the concave mirror, and passes through the beam splitter as polarized light in a second direction (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above-described head-mounted display device has a configuration in which an intermediate image is not generated and there is no aperture stop. Therefore, unnecessary light is trapped in the light guide plate, and there is a problem that unnecessary light reaches the eyes.

Means for Solving the Problems

[0005] A virtual image display device in one aspect of the present invention comprises a display element that emits image light, a first prism into which the image light from the display element is incident, a second prism joined to the first prism to form a parallel plate-shaped prism light guide member, a reflective polarizing element provided at the joint between the first prism and the second prism via an adhesive member and which reflects at least a portion of the image light guided in the first prism, a lens having positive power and positioned opposite the outer surface of the first prism into which the image light reflected by the reflective polarizing element is incident, a transmissive mirror formed on the external side of the lens and which partially reflects the image light reflected by the reflective polarizing element toward the reflective polarizing element, and a quarter-wave plate positioned between the outer surface of the first prism and the lens, wherein the reflective polarizing element has a light deflection portion in the end region near the inner surface opposite to the outer surface.

[0006] An optical unit in one aspect of the present invention comprises a first prism into which image light from a display element is incident; a second prism joined to the first prism to form a parallel plate-shaped prism light guide member; a reflective polarizing element provided at the joint between the first prism and the second prism via an adhesive member and reflecting at least a portion of the image light guided in the first prism; a lens having positive power and positioned opposite the first outer surface of the first prism into which the image light reflected by the reflective polarizing element is incident; a transmissive mirror formed on the external side of the lens and partially reflecting the image light reflected by the reflective polarizing element toward the reflective polarizing element; and a quarter-wave plate positioned between the outer surface of the first prism and the lens, wherein the reflective polarizing element has a light deflection portion in the end region near the inner surface opposite to the outer surface. [Brief explanation of the drawing]

[0007] [Figure 1] This is an external view illustrating the usage state of the virtual image display device of the first embodiment. [Figure 2] This is a lateral cross-sectional view illustrating the internal structure of one of the virtual image display devices. [Figure 3] This is a perspective view of a virtual image display device. [Figure 4] This is an exploded view of the first flat plate-shaped member. [Figure 5]This is a view of the second prism and the reflective polarizing element from the outside. [Figure 6] This is a side cross-sectional view of the prism light guide member. [Figure 7] This is a magnified cross-sectional view illustrating the reflective polarizing element before it is attached to the prism. [Figure 8] Figure 2 and other diagrams illustrate the optical path and other aspects of the virtual image display device shown. [Figure 9] This is a conceptual diagram illustrating, in detail, the unwanted light incident on the upper part of the first prism. [Figure 10] This is a conceptual diagram illustrating the optical path of unwanted light entering the first prism. [Figure 11] This is a conceptual diagram illustrating a specific optical path for other unwanted light entering the first prism. [Figure 12] This figure illustrates the projection state of unwanted light in the virtual image display device of the embodiment. [Figure 13] This figure illustrates the projection state of unwanted light in a comparative example virtual image display device. [Figure 14] This figure illustrates the reflective polarizing element of the virtual image display device according to the second embodiment. [Figure 15] Figure 14 illustrates the projection state of unwanted light in the virtual image display device shown. [Figure 16] This is a side cross-sectional view illustrating the virtual image display device of the third embodiment. [Figure 17] This is a lateral cross-sectional view illustrating a modified virtual image display device. [Modes for carrying out the invention]

[0008] [First Embodiment] A first embodiment of the virtual image display device, etc., according to the present invention will be described below with reference to Figures 1 and 2, etc.

[0009] Figure 1 illustrates the wearing state of a head-mounted virtual image display device (hereinafter also referred to as a head-mounted display or HMD) 200. The HMD 200 causes the observer or wearer US to perceive an image as a virtual image. In Figure 1, etc., X, Y, and Z are Cartesian coordinate systems. 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) of the wearer US are aligned. The +Z direction corresponds to the forward or frontal direction in which the wearer US is positioned. The ±Y directions are parallel to the vertical axis or the vertical direction.

[0010] The HMD200 comprises a first virtual image display device 100A for the right eye, which is of the direct virtual image type; a second virtual image display device 100B for the left eye, which is also of the direct virtual image type; a pair of temple-shaped support devices 100C that support these virtual image display devices 100A and 100B; and a user terminal 90, which is an information terminal. The first virtual image display device 100A functions as an HMD on its own and consists of a first display drive unit 102a located at the top and a first combiner 103a that is spectacle-lens-shaped and covers the area in front of the eyes. Similarly, the second virtual image display device 100B also functions as an HMD on its own and consists of a second display drive unit 102b located at the top and a second combiner 103b that is spectacle-lens-shaped and covers the area in front of the eyes. The support devices 100C are mounting members that are attached to the head of the wearer US. The support device 100C supports the upper ends of the pair of combiners 103a and 103b via display drive units 102a and 102b, which are integrated externally. The first virtual image display device 100A and the second virtual image display device 100B are optically identical or horizontally inverted versions thereof.

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

[0012] Although detailed description is 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 the same as the first image forming element 11a. The second display unit 20b is the same as the first display unit 20a. The second circuit member 80b is the same as the first circuit member 80a.

[0013] In the first virtual image display device 100A, the first image forming element 11a is a self-emissive image light generation device. The first image forming element 11a emits image light ML onto the first flat plate member 40 via 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 electroluminescent (OLED) display. The first image forming element 11a forms a color still image or moving image on a two-dimensional display surface 11d. The first image forming element 11a is driven by the first circuit member 80a to perform display operations. The first image forming element 11a is not limited to an OLED display, but can be replaced with a display device using inorganic EL, organic LED, LED array, laser array, quantum dot light-emitting element, etc. The first image forming element 11a is not limited to a self-emissive image light generation device, but may also be composed of an LCD or other light modulation element, and may form an image by illuminating the light modulation element with a light source such as a backlight. Instead of an LCD, an LCOS (Liquid crystal on silicon, LCoS is a registered trademark) or the like can be used as the first image forming element 11a. In the first virtual image display device 100A, the optical device excluding the first circuit member 80a is called the optical unit 100. The optical unit 100 includes a direct virtual image optical system and can be said to be the part corresponding to the direct virtual image optical system DIS that constitutes 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 reflective polarizing element 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 video light ML from the first image forming element 11a is incident thereon. The first lens 30 has a light incident surface 30f on the plane joined to the first image forming element 11a and a convex light emitting surface 30g. The light emitting surface 30g is, for example, spherical, but can be an aspherical surface having an axially symmetric shape. The first lens 30 can be considered as being divided into a parallel flat plate 31 and a lens portion 32. By ensuring that the thickness of the parallel flat plate 31 is a predetermined value or more, foreign matter adhering to the surface of the first lens 30 becomes less noticeable. The parallel flat plate 31 functions as a cover glass. The lens portion 32 is a plano-convex lens having a positive refractive power. A plano-convex lens has one surface with a planar shape and the other surface with a convex shape. Note that the parallel flat plate 31 and the lens portion 32 may be adhered or separated. The lens portion 32 does not have to be a plano-convex lens, and for example, a biconvex lens may be used. Also, the first lens 30 is made of, for example, fused quartz and has a relatively low refractive index.

[0015] The first flat plate member 40 has a parallel flat plate-shaped first prism 41 and a parallel flat plate-shaped second prism 42. The first prism 41 and the second prism 42 are joined at inclined surfaces 41d and 42d with the reflective polarizing element 45 sandwiched therebetween. The combination of the first prism 41 and the second prism 42 joined together is called a prism light guide member 48. The prism light guide member 48 has the appearance of a parallel flat plate. The combination of the prism light guide member 48 and a second flat plate member 50 described later corresponds to the first combiner 103a.

[0016] Figure 4 is an exploded view of the first flat plate member 40. As shown in Figures 2 to 4, the first prism 41 has a rectangular prism shape and a trapezoidal longitudinal cross-section. The first prism 41 guides the image light ML. The first prism 41 has an incident optical surface 41a, a first inner surface 41b, a first outer surface 41c, and a first inclined surface 41d. The first prism 41 also has an upper plane 40u and a first lateral surface 41e. Here, the incident optical surface 41a as a whole is inclined forward and downward, and the optical axis passing through the incident optical surface 41a extends in a direction between the forward +Z direction and the upward +Y direction. This makes it easier to position the first image forming element 11a, which is the display element 11, on the external side of the first inner surface 41b, and allows adjustment of the angle at which the image light ML propagates within the first prism 41 (inside or within the first prism 41). The incident optical surface 41a is a convex surface, for example a sphere, but can be an axially symmetric aspherical surface. The first prism 41 can be considered to include a lens portion 44 that includes the incident optical surface 41a. The lens portion 44 is a convex-flat lens having positive refractive power. The lens portion 44 may be formed directly on the first prism 41, or it may be bonded to the first prism 41. The first inner surface 41b and the first outer surface 41c are parallel to each other and extend perpendicular to the optical axis AX between them and the pupil position PP. The first inner surface 41b and the first outer surface 41c internally reflect the image light ML (i.e., reflect it on the inside of the object surface), and it is particularly desirable that they perform total internal reflection. The first inner surface 41b can be hard-coated to improve scratch resistance or abrasion resistance. The first lateral surface 41e is located between the first outer surface 41c and the first inner surface 41b and is positioned in the lateral direction, i.e., the X direction, which intersects the Y direction, the direction in which the first prism 41 and the second prism 42 are aligned. The first inclined surface 41d is a plane. The first inclined surface 41d forms an acute angle with respect to the first outer surface 41c, specifically an angle of 25° to 32°. The distance between the optical axis AX passing through the pupil position PP and the upper end of the first lens 30 is approximately 20 mm. The first prism 41 is made of a resin material.

[0017] The number of reflections of the image light ML in the first prism 41 is once at the first inner surface 41b, once at the first outer surface 41c, and once at the reflective polarizing element 45, which will be described later. By making the number of internal reflections of the image light ML in the first prism 41 two, it is possible to increase the field of view of the image light ML, the pupil position PP, or its aperture PPa while efficiently avoiding the mixing of light with different reflection counts within the first prism 41. Furthermore, it becomes easier to shorten the distance from the display element 11 to the transmissive mirror 56 of the cover member 52, which will be described later, allowing for miniaturization of the prism light guide member 48, and also making it easy to miniaturize the display element 11 and the first lens 30.

[0018] The second prism 42, like the first prism 41, has a rectangular prism shape and a trapezoidal longitudinal cross-section. The second prism 42 transmits the image light ML. The second prism 42 has a second inner surface 42b, a second outer surface 42c, a second bevel surface 42d, and a bottom surface 42f. The bottom surface 42f is the surface of the prism light guide member 48 or the first flat plate member 40 that is opposite to the incident optical surface 41a. Also, the bottom surface 42f is the surface of the second prism 42 that is opposite to the second bevel surface 42d. The second prism 42 also has a second transverse surface 42e. Here, the second inner surface 42b and the second outer surface 42c are parallel to each other and extend perpendicular to the optical axis AX between them and the pupil position PP. The scratch resistance of the second inner surface 42b can be improved by applying a hard coat. The second lateral surface 42e is positioned between the second outer surface 42c and the second inner surface 42b, and corresponds to the lateral direction, i.e., the X direction, which intersects the Y direction, the direction in which the first prism 41 and the second prism 42 are aligned. The second prism 42 is made of a resin material.

[0019] The beveled portion ST, which is the joint JS between the first prism 41 and the second prism 42, has flat portions FL on the first and second outer surfaces 41c and 42c. Both flat portions FL are formed continuously from the lower ends of the first bevel 41d and the second bevel 42d. Both flat portions FL are obtuse to the first bevel 41d and the second bevel 42d and extend substantially parallel to the XZ plane. The flat portions FL are positioning structures AS provided around the bevels 41d and 42d of the first prism 41 and the second prism 42. When joining the first prism 41 and the second prism 42, by facing and bringing these bevels 41d and 42d close together, the pair of flat portions FL provided adjacent to the bevels 41d and 42d also come into contact with each other as contact surfaces AF extending parallel to each other, and are tightly attached to one another. This allows the first prism 41 and the second prism 42 to be positioned with respect to the inclination direction of their inclined surfaces 41d and 42d, that is, the intermediate direction between the Z and Y directions, and also with respect to an axis perpendicular to the inclined surfaces 41d and 42d. As a result, the flat section FL positions the first prism 41 and the second prism 42 with respect to the +Z direction or the depth direction, and sets their relative rotational orientations as designed. By using the flat section FL as a contact surface AF, not only is the assembly of joining the first prism 41 and the second prism 42 made easier, but it can also function as a misalignment prevention section. This improves the joining accuracy of the first prism 41 and the second prism 42. In the region between the first prism 41 and the second prism 42 where the reflective polarizing element 45 is not provided, a gap PN is formed (see Figure 2 and Figure 6 described later). The distance from the lower end of the reflective polarizing element 45 to the outer surfaces 41c and 42c can be made relatively wide, making it easy to provide a flat section FL, i.e., a positioning structure AS. Furthermore, if a sufficient area that does not reflect light can be secured, the joint JS between the first prism 41 and the second prism 42 may have a flat section as a positioning structure AS on the first and second inner surfaces 41b and 42b sides.

[0020] The reflective polarizing element 45 reflects at least a portion of the image light ML guided in the first prism 41. The reflective polarizing element 45 is provided at the joint JS between the first prism 41 and the second prism 42 via an adhesive member AD. In other words, the reflective polarizing element 45 is attached to the first bevel surface 41d of the first prism 41 and the second bevel surface 42d of the second prism 42 by the adhesive member AD. The reflective polarizing element 45 is formed in a slightly narrower region excluding the outer edges of the bevel surfaces 41d and 42d of the first prism 41 and the second prism 42.

[0021] The reflective polarizing element 45 is, for example, a polarizing beam splitter having s-polarization reflection characteristics. When the image light ML contains s-polarized PLs, the reflective polarizing element 45 efficiently reflects the s-polarized PLs of the image light ML, and when the image light ML contains p-polarized PLp, it efficiently transmits the p-polarized PLp of the image light ML. The reflective polarizing element 45 only needs to selectively reflect the image light ML according to its polarization direction. In addition, the reflective polarizing element 45 may transmit s-polarized PLs and reflect p-polarized PLp.

[0022] Examples of the reflective polarizing element 45 include multilayer films, wire grid type polarizers such as wire grid films, and reflective polarizing elements utilizing film stretching.

[0023] The reflective polarizing element 45 only needs to have a flat surface that does not affect image formation. Alternatively, the reflective polarizing element 45 may have a slightly curved surface that is convex or concave, as long as it does not affect image formation. The scratch resistance or abrasion resistance of the reflective polarizing element 45 can be improved by applying a hard coat to its surface.

[0024] Details regarding the structure of the reflective polarizing element 45 will be described later.

[0025] As shown in Figure 2, the second flat plate member 50 has a thin quarter-wave plate 51 and a cover member 52. The quarter-wave plate 51 is made of a crystal, liquid crystal material, etc., having an optical axis between the X direction and the Y direction. The quarter-wave plate 51 converts the s-polarized PLs image light ML reflected by the reflective polarizing element 45 into circularly polarized PLc, and the circularly polarized PLc image light ML reflected by the cover member 52 into p-polarized PLp. The cover member 52 has a plano-convex second lens 53 with positive power, a concave-flat compensating lens 54, a compensating plate 55 provided around the compensating lens 54 and extending parallel to the prism light guide member 48, and a transmissive mirror 56.

[0026] The second flat plate-shaped member 50 is positioned approximately 20 μm to 100 μm away from the first flat plate-shaped member 40. The first and second outer surfaces 41c, 42c of the first flat plate-shaped member 40 and the third inner surface 50c of the second flat plate-shaped member 50 may be slightly curved, and a minute step may be formed at the boundary between the first and second outer surfaces 41c, 42c. However, by setting the distance between the first and second outer surfaces 41c, 42c and the third inner surface 50c to 20 μm or more, more preferably 30 μm or more, it is possible to avoid these surfaces being excessively close together. Conversely, by setting the distance between the first and second outer surfaces 41c, 42c and the third inner surface 50c to 100 μm or less, it is possible to avoid an increase in the thickness of the first combiner 103a, which is the first flat plate-shaped member 40 and the second flat plate-shaped member 50 combined. A spacer 61 is provided between the first and second outer surfaces 41c, 42c of the first flat plate member 40 and the third inner surface 50c of the second flat plate member 50 to adjust the distance between the first flat plate member 40 and the second flat plate member 50 and fix them in a relative position. The spacer 61 is not provided around the entire circumference 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.

[0027] In the cover member 52, the second lens 53 is positioned opposite the first outer surface 41c of the first prism 41 or the quarter-wave plate 51. The second lens 53 focuses the image light ML. The second lens 53 is a thin but positively refractive plano-convex lens. A plano-convex lens has one surface that is planar and the other surface that is convex outward. The second lens 53 has a plane 53f joined to the quarter-wave plate 51 and a convex surface 53g opposite the compensating lens 54. The convex surface 53g is, for example, a sphere, but can be an axially symmetric aspherical surface. The compensating lens 54 is thin but has positive refractive power. The compensating lens 54 has a concave surface 54f opposite the second lens 53 and a plane 54g. The compensating plate 55 is a parallel plate. The compensating plate 55 has a pair of planes 55f, 55g. Here, the shape of the compensating lens 54 opposite the concave surface 54f is the same as the shape of the convex surface 53g of the second lens 53. The plane 54g of the compensating lens 54 and the plane 55g of the compensating plate 55 are on the same plane and are continuous. The transmissive mirror 56 is a thin film formed on the convex surface 53g on the external side of the second lens 53 and has the same shape as the convex surface 53g. The combination of the second lens 53 and the transmissive mirror 56 is called the light-gathering and reflecting section CR.

[0028] The second lens 53, the compensating lens 54, and the compensating plate 55 are made of resin material and have the same refractive index. The refractive index of the second lens 53, etc., is lower than that of the first prism 41. The compensating lens 54 and the compensating plate 55 are optical elements 58 integrally formed from the same resin material.

[0029] The combination of the second lens 53, the compensating lens 54, and the compensating plate 55 functions as a parallel plate as a whole. In other words, ambient light OL incident at the positions of the compensating lens 54 and the compensating plate 55 passes through them without being affected by the lensing effect of the compensating lens 54, etc., or by the step present on the outer edge of the compensating lens 54. In this way, the compensating lens 54 optically compensates for the effect of the second lens 53 on ambient light OL. In this sense, the plane 53f of the second lens 53, the plane 54g of the compensating lens 54, and the planes 55f, 55g of the compensating plate 55 are not necessarily limited to strictly flat planes, but may be, for example, approximately flat, or may include curved surfaces partially or entirely. Furthermore, the plane 53f of the second lens 53, the plane 54g of the compensating lens 54, and the planes 55f, 55g of the compensating plate 55 may include curved surfaces for correcting the wearer's vision, or curved surfaces as a design element, such as sunglasses or fashion glasses, to the extent that it does not cause any inconvenience in terms of optical performance. The flat surfaces 54g and 55g of the compensating lens 54 and compensating plate 55 can be coated with an anti-reflective film or a hard coating. The ambient light OL passing through the compensating plate 55 passes above, below, to the left and right of the compensating lens 54. This ambient light OL is incident from the peripheral region outside the incident region of the image light ML corresponding to the compensating lens 54, i.e., from the compensating plate 55. This ensures a wide see-through field of view with respect to the outside world. The field of view range of the ambient light OL is set, for example, to about 40° upwards and about 40° downwards.

[0030] The transmissive mirror 56 is a half-mirror. The transmissive mirror 56 partially reflects the image light ML that has passed through the second lens 53 and partially transmits the ambient light OL. The transmissive mirror 56 reflects the image light ML that has been reflected by the reflective polarizing element 45 of the first flat plate member 40 and passed through the quarter-wave plate 51 and the second lens 53 toward the pupil position PP. The transmissive mirror 56 is a concave mirror that covers the pupil position PP where the eye EY or pupil is located and has a concave shape toward the pupil position PP and a convex shape toward the outside world. The pupil position PP or its opening PPa is called the eye point or eye box and corresponds to the exit pupil EP of the first display unit 20a.

[0031] The transmissive mirror 56 transmits some of the ambient light OL, enabling see-through viewing of the outside world and allowing a virtual image to be superimposed on the image of the outside world. In this case, the ambient light OL passes through the first flat plate member 40 and the second flat plate member 50, but the flat plate members 40 and 50 do not produce a lens effect on the ambient light OL. The reflectivity of the transmissive mirror 56 with respect to the image light ML and ambient light OL is set to 10% to 50% within the assumed incident angle range of the image light ML, from the viewpoint of ensuring the brightness of the image light ML and facilitating observation of the outside world image through see-through. The transmissive mirror 56 is formed, for example, from a dielectric multilayer film consisting of multiple dielectric layers with adjusted film thicknesses. The transmissive mirror 56 may also be a single-layer or multilayer film of a metal such as Al or Ag with adjusted film thickness. The transmissive mirror 56 is formed, for example, by lamination using vapor deposition.

[0032] In the first virtual image display device 100A, the first lens 30, lens section 44, second lens 53, and transmissive mirror 56 each have positive refractive power and tend to converge divergent light. The first lens 30, lens section 44, second lens 53, and transmissive mirror 56, along with the body of the first prism 41, the second prism 42, etc., function as an imaging optical system IS or a direct virtual image optical system DIS, similar to a single-lens microscope, that forms an erect image. This makes it possible to form a virtual image by projecting, for example, the real image formed on the display surface 11d of the first image forming element 11a to infinity, or to form a virtual image by projecting the real image formed on the display surface 11d to a distance of several meters. In this case, by adjusting the refractive power of the first lens 30, lens section 44, second lens 53, and transmissive mirror 56, the focal length of the imaging optical system IS can be shortened to achieve a desired magnification.

[0033] The vertical dimensions of the first flat plate member 40 or the second flat plate member 50 are, for example, 34 mm, and the horizontal dimensions are, for example, 40 mm. The front-to-back thickness of the first flat plate member 40 is, for example, about 7 mm to 8 mm, and the combined thickness of the first flat plate member 40 and the second flat plate member 50 is kept to about 7.5 mm to 8.5 mm.

[0034] In the first prism 41 of the first flat plate member 40, the incident optical surface 41a, the first inner surface 41b, and the first outer surface 41c can be sources of stray light caused by the image light ML. That is, since the first virtual image display device 100A or optical unit 100 is a direct virtual image optical system DIS, an aperture diaphragm cannot be provided, and there is a relatively high possibility that the image light ML will bend into an unintended optical path, reach the pupil position PP, and be observed as a ghost. In the prerequisite technology prior to the improvements of this invention, the above-mentioned ghosting is suppressed by providing a light-absorbing layer AL in appropriate places on the first flat plate member 40 or the prism light guide member 48 (see Figure 3).

[0035] Specifically, in the first prism 41, a light-absorbing layer AL is provided on the upper plane 40u. The upper plane 40u corresponds to the peripheral region of the incident optical surface 41a, which is the incident surface 40i of the first prism 41. The light-absorbing layer AL has a contour corresponding to the upper plane 40u, but is not limited to this; for example, it may cover the vicinity of the incident optical surface 41a and expose the upper plane 40u in a region close to the lateral surfaces 41e and 42e. Furthermore, the light-absorbing layer AL provided on the upper plane 40u is not essential.

[0036] Furthermore, a light-absorbing layer AL is also provided on the upper part UP of the first prism 41, more specifically, on the upper end region 41u of the first outer surface 41c of the first prism 41. The light-absorbing layer AL provided on the upper end region 41u is formed as a long, band-shaped region in the lateral X direction at the upper end of the first outer surface 41c.

[0037] Furthermore, a light-absorbing layer AL is also provided on the bottom surface 42f of the prism light guide member 48 or the second prism 42. This light-absorbing layer AL also prevents the image light ML that has passed through the reflective polarizing element 45 from becoming stray light. The second prism 42 has a curved surface 42g at the boundary between the bottom surface 42f and the second lateral surface 42e. It is preferable that the light-absorbing layer AL extends from the bottom surface 42f to the curved surface 42g. In other words, the light-absorbing layer AL extends to the R-shaped portion at the boundary between the bottom surface 42f and the second lateral surface 42e of the second prism 42.

[0038] Furthermore, although not essential, a light-absorbing layer AL may also be provided on the surface of the left and right outer peripheral portions 51f of the quarter-wave plate 51 or on the flat surface 55f on the back side of the compensating plate 55 corresponding to the outer peripheral portions 51f. This light-absorbing layer AL targets the image light ML that is emitted from the prism light guide member 48 via, for example, a reflective polarizing element 45 and incident near the outside of the second lens 53, thereby preventing such unwanted light from causing ghosting.

[0039] As described above, even if a light-absorbing layer AL is provided in the appropriate place on the prism light guide member 48, image light ML that bends into unintended optical paths may remain, leaving a lot of unwanted light outside the image area and potentially causing ghosting. In this embodiment, in order to suppress the above-mentioned ghosting, a reflective polarizing element 45 having a light deflection section LD is provided between the first prism 41 and the second prism 42.

[0040] Figures 5 and 6 illustrate the structure of the reflective polarizing element 45. Figure 5 is a view of the second prism 42 and the reflective polarizing element 45 from the outside. Figure 6 is a side cross-sectional view of the prism light guide member 48. The structure of the reflective polarizing element 45 and its surrounding parts will be explained with reference to Figures 5 and others.

[0041] As shown in Figures 5 and 6, the reflective polarizing element 45 has an optical deflection section LD in the end region EA, which is close to the second inner surface 42b on the opposite side of the second outer surface 42c. The end region EA is the region of the reflective polarizing element 45 that includes the side or end on the pupil position PP side. In other words, the end region EA is the end of the reflective polarizing element 45 that is close to the inner surfaces 41b and 42b of the first prism 41 and the second prism 42, and extends along the inner surfaces 41b and 42b. The optical deflection section LD deflects the incident image light ML from the normal optical path of reflection or transmission. In other words, the reflective polarizing element 45 suppresses ghosting not only when reflecting the image light ML, but also when refracting the image light ML. The area of ​​the reflective polarizing element 45 other than the end region EA is called the main region MA. The main region MA is a region that has a substantial polarization separation function and does not have an optical deflection section LD.

[0042] As shown in Figure 5, the reflective polarizing element 45 has a sawtooth-shaped BD in the end region EA as the light deflection section LD. The sawtooth-shaped BD has the function of preventing image light ghosting. This allows unintended image light ML to be diverted from the optical path leading to the pupil position PP. Specifically, the sawtooth-shaped BD diverts unwanted light to the left and right, reducing the amount of light with high brightness. Diverting unwanted light to the left and right means bending the light in a direction that does not affect image quality, rather than reflecting it back into its original path.

[0043] The saw blade shape BD consists of multiple isosceles triangular saw teeth BDz, each with a tip angle θ of 90°. In Figure 5, the saw blade shape BD is exaggerated for illustrative purposes, but in reality, it is a very fine structure. The width W of a single saw tooth BDz is, for example, about 1 μm.

[0044] The light deflection section LD is not limited to a sawtooth shape BD, but may have other shapes, specifically, uneven shapes or shapes with fine holes, as long as it deflects the image light ML to the left or right. Furthermore, the sawtooth shape BD may have blunted teeth BDz, or it may have a shape where the sharp-angled teeth BDz are slightly flattened.

[0045] As shown in Figure 6, the reflective polarizing element 45 has adhesive members AD on the surface facing the first prism 41 and the surface facing the second prism 42. As a result, the first prism 41 and the second prism 42 are joined by the adhesive members AD provided on the reflective polarizing element 45, eliminating the need for a separate adhesive.

[0046] Figure 7 is an enlarged cross-sectional view illustrating the reflective polarizing element 45 before it is attached to the first prism 41 and the second prism 42. As shown in Figure 7, adhesive members AD are provided on both sides 45j and 45k of the reflective polarizing plate 45a, which is the main body of the reflective polarizing element 45. The reflective polarizing element 45 is a reflective polarizing plate with an adhesive film, composed of a combination of a flat plate or film-shaped reflective polarizing plate 45a and the adhesive member AD. The overall thickness d1 of the reflective polarizing element 45 is, for example, 70 μm to 110 μm, specifically 101 μm. The thickness d2 of the reflective polarizing plate 45a of the reflective polarizing element 45 is, for example, 50 μm to 90 μm, specifically 83 μm. The thickness d3 of the adhesive member AD is, for example, 2 μm to 10 μm, specifically 9 μm.

[0047] The adhesive component AD is, for example, OCA (Optical Clear Adhesive). OCA is a film-like adhesive sheet. OCA has a refractive index close to that of the first prism 41 or second prism 42 to which it is bonded. OCA has a uniform or nearly uniform thickness and low product variation. Also, unlike adhesives, OCA does not overflow with excess adhesive.

[0048] Before the reflective polarizing element 45 is attached, both sides 45m and 45n of the reflective polarizing element 45 are protected by a protective film PF. The reflective polarizing element 45 before molding, protected by the protective film PF, is called a blank member 45x. The reflective polarizing element 45 is formed by cutting out the blank member 45x using a die-cutting die (not shown) to create a sawtooth shape BD.

[0049] As shown in Figure 5, the size of the reflective polarizing element 45 is smaller than the size of the inclined surfaces 41d and 42d of the first prism 41 and the second prism 42 in the direction of inclination of the inclined surfaces 41d and 42d. In other words, the reflective polarizing element 45 is not provided at the lower ends of the inclined surfaces 41d and 42d. As a result, as shown in Figure 6, when the reflective polarizing element 45 is sandwiched between the first and second prisms 41 and 42, a gap PN is formed on the outside side. Due to this gap PN, an inclined surface exposure region RA exists at the joint JS of the prism light guide member 48. The inclined surface exposure region RA limits the reflection area of ​​the image light ML at the reflective polarizing element 45 in the inclined surface ST, allowing unintended image light ML to pass through in the allowable region around the reflective polarizing element 45. In other words, it is possible to prevent unwanted light that causes ghosting from entering the reflective polarizing element 45 and reduce the reflection of unwanted light at the reflective polarizing element 45.

[0050] The reflective polarizing element 45 is positioned, for example, about 3 mm away from the lower end of the first bevel 41d of the first prism 41 or the second bevel 42d of the second prism 42. Alternatively, the reflective polarizing element 45 may be positioned slightly away from the upper end of the first bevel 41d of the first prism 41 or the second bevel 42d of the second prism 42. In this case, the distance from the upper ends of the bevels 41d and 42d should be 1 mm or less. Furthermore, the reflective polarizing element 45 may be positioned from the lower end of the bevels 41d and 42d by adjusting the length of the flat section FL. The reflective polarizing element 45 is positioned, for example, about 1 mm away from the lateral surfaces 41e and 42e of the first prism 41 or the second prism 42. However, the reflective polarizing element 45 does not necessarily have to be positioned away from the lateral surfaces 41e and 42e of the first prism 41 or the second prism 42.

[0051] The reflective polarizing element 45 selectively reflects the image light ML in the main region MA, excluding the edge region EA, according to its polarization direction. Furthermore, as described above, the optical deflection section LD provided in the edge region EA deflects the image light ML away from the optical path that causes ghosting, even if unintended components of the image light ML are incident on the first prism 41. This allows for efficient reflection of the image light ML in the normal optical path while limiting the reflection or transmission of unwanted light that causes ghosting in the edge region EA. As a result, it is possible to suppress the observation of ghosting around the virtual image being observed.

[0052] Figure 8 is a diagram illustrating the optical path of the first virtual image display device 100A. As shown in Figure 8, the image light ML from the first image forming element 11a passes through the first lens 30 and enters the first prism 41. At this time, the degree of divergence of the image light ML is suppressed by the positive refractive power of the first lens 30 and the lens portion 44. In the optical path passing through the first prism 41, the image light ML is sequentially reflected by the first inner surface 41b and the first outer surface 41c of the first prism 41 without forming an intermediate image (see Figure 2), and the s-polarized PLs of the image light ML are reflected by the reflective polarizing element 45. The image light ML of the s-polarized PLs reflected by the reflective polarizing element 45 passes through the first outer surface 41c of the first prism 41 and passes through the quarter-wave plate 51 of the second flat plate member 50, becoming circularly polarized PLc, and enters the second lens 53 and the transmissive mirror 56. A portion of the circularly polarized PLc image light ML incident on the transmissive mirror 56 is reflected by the transmissive mirror 56, passes through the second lens 53, and then passes through the quarter-wave plate 51 again in a collimated state. As a result, the image light ML that has passed through the quarter-wave plate 51 becomes p-polarized PLp and is incident on the first prism 41 from the first outer surface 41c, passes through the reflective polarizing element 45, and is emitted outside the second prism 42 via the second inner surface 42b. The image light ML emitted outside the second prism 42 is incident on the pupil position PP where the wearer's eye EY or pupil is located (see Figure 2). Not only the image light ML reflected by the transmissive mirror 56, but also the ambient light OL that has passed through the transmissive mirror 56 and the ambient light OL that has passed through the compensating plate 55 are incident on the pupil position PP. In other words, the wearer US wearing the first virtual image display device 100A can observe a virtual image of the image light ML superimposed on the ambient image. In this embodiment, the observation of ghosting is suppressed by limiting unwanted light GL1 to GL3, as described below, using the light deflection portion LD and the inclined surface exposure region RA of the reflective polarizing element 45.

[0053] Figure 9 is a conceptual diagram illustrating a specific example of unwanted light GL1 caused by image light ML incident on the upper part UP of the first prism 41 from an unintended optical path. In this case, unwanted light GL1a, a specific component of unwanted light GL1, is sequentially reflected by the first inner surface 41b and the first outer surface 41c at an unexpected location on the upper part UP of the first prism 41. As a result, unwanted light GL1a is reflected twice each by the first inner surface 41b and the first outer surface 41c within the first prism 41, and after passing through the reflective polarizing element 45 and the transmissive mirror 56, it is incident on the pupil position PP (see Figure 2) from a diagonally downward direction at an angle of approximately 17° along with the image light ML from the normal optical path. This unwanted light GL1a is outside the image region of the virtual image and forms a ghost image on the lower side of the image region. Unwanted light GL1b, another component of unwanted light GL, is sequentially reflected by the first inner surface 41b and the first outer surface 41c at an unexpected location on the upper part UP of the first prism 41. This unwanted light GL1b passes through the reflective polarizing element 45 and the transmissive mirror 56 and, together with the image light ML from the normal optical path, is incident on the pupil position PP from an oblique upward direction at an angle of approximately 17°. This unwanted light GL1b is outside the image region of the virtual image and forms a ghost image on the lower side of the image region. However, the passage of such unwanted light GL1, i.e., unwanted light GL1a and GL1b, is restricted by the light deflection part LD of the reflective polarizing element 45 as shown in Figure 5, etc., and the observation of ghosts is suppressed.

[0054] Figure 10 illustrates the optical path of unwanted light GL2 caused by another image light ML that enters the incident optical surface 41a of the first prism 41 from an unintended optical path. In this case, the unwanted light GL2 is reflected at the upper end of the reflective polarizing element 45 at the boundary between the first prism 41 and the second prism 42, deviates from the optical path, passes through the transmissive mirror 56, etc., and enters the pupil position PP (see Figure 2) from an oblique upward direction at an angle of about 20°. This unwanted light GL2 is outside the image region of the virtual image and forms a ghost image on the upper side of the image region. However, the passage of such unwanted light GL2 is restricted by the light deflection section LD provided in the end region EA of the reflective polarizing element 45, and the observation of ghosts is suppressed.

[0055] Figure 11 illustrates the optical path of unwanted light GL3 caused by another image light ML that enters the incident optical surface 41a of the first prism 41 from an unintended optical path. In this case, the unwanted light GL3 is sequentially reflected by the first inner surface 41b and the first outer surface 41c, and is reflected by the first outer surface 41c without entering the transmissive mirror 56 via the reflective polarizing element 45, and enters the pupil position PP (see Figure 2) from a diagonally downward direction at an angle of about 13°. This unwanted light GL3 is outside the image region of the virtual image and forms a ghost image below the image region. However, the passage of such unwanted light GL3 is mainly restricted by the presence of the inclined surface exposure region RA, that is, by limiting the size of the external side of the reflective polarizing element 45 on the external side or by the second lens 53, and the observation of ghosts is suppressed.

[0056] Figure 12 is a diagram illustrating the projection state of unwanted light in the virtual image display device 100A according to this embodiment. Figure 13 is a diagram illustrating the projection state of unwanted light in the virtual image display device of a comparative example. Figure 12 shows the case where the first virtual image display device 100A has a reflective polarizing element 45 as shown in Figure 5, etc. Figure 13 shows the case where the first virtual image display device 100A has a sloped exposed region RA, but the reflective polarizing element 45 does not have a light deflection portion LD. Specifically, the reflective polarizing element 45 of the comparative example is obtained by cutting the end region EA in a straight line from the blank member 45x shown in Figure 7 with a cutter blade or the like.

[0057] In Figures 12 and 13, the upper left region shows a simulated image illustrating the detection state by an angle light receiver positioned at pupil position PP when a full-white image is displayed on the display element 11. To the right of this simulated image, a logarithmic graph of the luminance distribution on the central vertical axis, which is 0° on the H-axis (horizontal axis), is shown. Below the simulated image, a logarithmic graph of the luminance distribution on the central horizontal axis, which is 0° on the V-axis (vertical axis), is shown. As a premise of the simulation, the angle light receiver evaluates the observed image across the entire eye box set at pupil position PP. The numerical values ​​shown in the luminance distribution of the H-axis and V-axis represent the percentage of unwanted light when the luminance of the image region IA visible in the center of the screen in the simulated image is set to 100%. In Figures 12 and 13, a comparison is made between the first type of ghost GH1 and the second type of ghost GH2, which occur above and below the image region IA. The first type of ghost GH1 is formed above the image region IA. The second type of ghost GH2 is formed below the image region IA.

[0058] As shown in Figure 12, in the virtual image display device of the embodiment, the first type of ghost GH1 has a brightness of about 0.6% compared to the central image area IA. The second type of ghost GH2 has a brightness of about 3.3% compared to the central image area IA.

[0059] As shown in Figure 13, in the comparative example of a virtual image display device, the first type of ghost GH1 has a brightness of approximately 3.2% compared to the central image area IA. The second type of ghost GH2 has a brightness of approximately 4.5% compared to the central image area IA.

[0060] From the above, it can be seen that in the virtual image display device of the embodiment, ghosting is further reduced by providing a light deflection section LD in the end region EA of the reflective polarizing element 45. On the other hand, in the virtual image display device of the comparative example, since the end region EA of the reflective polarizing element 45 is linear, unwanted light is generated because the light totally reflected in the end region EA propagates to the lower side of the prism light guide member 48 at a different angle than originally intended.

[0061] An example of the structure and assembly of the first display unit 20a constituting the first virtual image display device 100A will be described. A first prism 41 and a second prism 42 are prepared. A reflective polarizing element 45 is attached between the first prism 41 and the second prism 42 via an adhesive member AD. As a result, the first prism 41 and the second prism 42 are joined at the inclined surfaces 41d and 42d, and a prism light guide member 48 or a first flat plate member 40 is obtained. In parallel with this, a quarter-wave plate 51, a second lens 53 with a transmissive mirror 56 formed thereon, and an optical element 58 are joined together and integrated, and this is attached to the outer surfaces 41c and 42c of the first flat plate member 40 facing each other. In this case, a pair of thin adhesive spacers 61 are placed between the outer surfaces 41c, 42c of the first flat plate member 40 and the quarter-wave plate 51, forming a gap SP between the outer surfaces 41c, 42c of the first flat plate member 40 and the quarter-wave plate 51.

[0062] The light-absorbing layer AL can be provided as appropriate during or after the assembly of the first display unit 20a.

[0063] The first embodiment of the virtual image display device 100A, 100B, or optical unit 100 described above comprises a display element 11 that emits image light ML, a first prism 41 into which the image light ML from the display element 11 is incident, a second prism 42 joined to the first prism 41 and constituting a parallel plate-shaped prism light guide member 48, and a reflector provided at the joint JS between the first prism 41 and the second prism 42 via an adhesive member AD, which reflects at least a portion of the image light ML guided in the first prism 41. The device comprises a polarizing element 45, a lens having positive power positioned opposite the outer surface of the first prism 41 into which the image light ML reflected by the reflective polarizing element 45 is incident, a transmissive mirror 56 formed on the external side of the lens that partially reflects the image light ML reflected by the reflective polarizing element 45 toward the reflective polarizing element 45, and a quarter-wave plate 51 positioned between the outer surface of the first prism 41 and the lens, wherein the reflective polarizing element 45 has an optical deflection portion LD in the end region EA near the inner surface opposite to the outer surface.

[0064] In the above-described virtual image display devices 100A, 100B, or optical unit 100, the reflective polarizing element 45 has an optical deflection section LD in the end region EA near the inner surface. Therefore, even if an unintended component of the image light ML is incident on the upper part of the first prism 41, the light can be deflected by the optical deflection section LD, thereby reducing unwanted light that causes ghosting and degrades image quality. This makes it possible to suppress the observation of ghosting around the virtual image being observed.

[0065] [Second Embodiment] The virtual image display device of the second embodiment will now be described. The virtual image display device of the second embodiment is a modified version of the virtual image display device of the first embodiment, and the parts common to the virtual image display device of the first embodiment will not be described.

[0066] Figure 14 illustrates the reflective polarizing element 45 of the virtual image display device 100A of the second embodiment. As shown in Figure 14, the reflective polarizing element 45 has a scattering shape SD in the end region EA as an optical deflection part LD. This allows unintended image light ML to be diverted from the optical path to the pupil position PP. This reduces the amount of light with high brightness.

[0067] The scattering shape SD is obtained by applying a diffusion treatment to the end face of a straight-cut section. The diffusion treatment involves applying an uneven shape to the end region EA using a spraying method such as a liquid or spray. The diffusion treatment is performed with the protective film PF shown in Figure 7 attached.

[0068] Figure 15 is a diagram illustrating the projection state of unwanted light in the virtual image display device 100A of the second embodiment.

[0069] As shown in Figure 15, in the virtual image display device of the second embodiment, the first type of ghost GH1 has a brightness of about 2.7% compared to the central image area IA. The second type of ghost GH2 has a brightness of about 3.1% compared to the central image area IA.

[0070] [Third Embodiment] The following describes the virtual image display device of the third embodiment. Note that the virtual image display device of the third embodiment is a modified version of the virtual image display device of the first embodiment, and the parts common to both the first embodiment and the third embodiment will not be described.

[0071] Figure 16 is a side cross-sectional view illustrating the virtual image display device 100A of the third embodiment. As shown in Figure 16, the virtual image display device 100A of the third embodiment does not have the flat portion FL shown in Figure 2, etc., on the first inclined surface 41d of the first prism 41 and the second inclined surface 42d of the second prism 42.

[0072] [Variations and other variations] Although the present invention has been described in reference to the embodiments described above, the present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit thereof, for example, the following modifications are also possible.

[0073] In the above description, the HMD200 is assumed to include a first virtual image display device 100A and a second virtual image display device 100B. However, the HMD200 may also be configured to support a single first virtual image display device 100A or a second display device 100B in front of the eyes by a support device 100C.

[0074] The display element 11 may emit linearly polarized image light ML, or a polarizing filter may be provided after the display element 11. This allows s-polarized image light ML to be incident on the reflective polarizing element 45.

[0075] The positioning structure AS is not limited to consisting only of a flat section FL, but may also have a shape that includes, for example, a step that enables positioning. The flat section FL can be provided away from the inclined surfaces 41d and 42d. In this case, a connecting surface consisting of a plane or a curved surface, or a step consisting of multiple surfaces, can be provided between the flat section FL and the inclined surfaces 41d and 42d. The flat section FL may be provided in two or more locations, for example, in the lateral X direction.

[0076] In the cover member 52, the compensating plate 55 can be omitted. In this case, the quarter-wave plate 51 is placed only within the range of the second lens 53, and the second lens 53 is covered by the compensating lens 54.

[0077] In the second flat plate-shaped member 50, the cover member 52 may be omitted.

[0078] The reflective polarizing element 45 may be bonded on one side with an adhesive material AD such as OCA, and on the other side with adhesive, provided that the adhesive does not spread.

[0079] The first lens 30 is not essential and can be omitted. In the first prism 41 of the first flat plate member 40, the incident optical surface 41a can also be omitted. In this case, the optical system will be one in which the lens portion 44 is omitted.

[0080] The first lens 30 is not limited to being bonded to the first image forming element 11a, but may also be arranged separately from the first image forming element 11a.

[0081] The second lens 53 is not limited to a plano-convex lens with positive power, but can be replaced with a diffractive lens, holographic lens, liquid crystal lens, etc., that also has positive power. In this case, the compensating lens 54 can be, for example, a diffractive lens or holographic lens with an inverted shape. In this case, the optical element such as the diffractive lens, holographic lens, or liquid crystal lens used as the second lens 53 can be given the function of partially reflecting the image light ML, but a planar transmissive mirror may be placed on the external side of such an optical element.

[0082] The light-absorbing layer AL may be omitted.

[0083] The lower gap PN formed between the first prism 41 and the second prism 42 may or may not be filled with adhesive.

[0084] The saw blade shape BD of the light deflection section LD is not limited to being formed with a cutter blade such as a Thomson type; it may also be formed by, for example, laser processing.

[0085] As shown in Figure 17, the first virtual image display device 100A may have an s-polarized light transmitting polarizer 12 placed between the first lens 30 and the display element 11 in the first display unit 20a. In addition, a third flat plate member 150 is added to the outer side of the second flat plate member 50 in the first display unit 20a. The third flat plate member 150 is an image light blocking unit LP. The third flat plate member 150 comprises an outer quarter-wave plate 151 provided on the outer side of the transmissive mirror 56 or the light-gathering reflective unit CR, and a polarizer 59 provided on the outer side of the outer quarter-wave plate 151. In other words, in the first display unit 20a, the inner quarter-wave plate 51 and the outer quarter-wave plate 151 are arranged between the inner reflective polarizing element 45 and the outer polarizer 59. The polarizer 59 selectively absorbs the image light ML transmitted through the outer quarter-wave plate 151 according to the polarization direction.

[0086] The circularly polarized image light ML that passes through the transmissive mirror 56 becomes p-polarized after passing through the outer quarter-wave plate 151, and is incident on the polarizing plate 59, where it is almost completely blocked. In other words, the image light ML is shielded by the third flat plate member 150 and does not leak out to the outside. This prevents the image light ML from being observed from the outside, thus ensuring privacy. On the other hand, the ambient light OL incident on the polarizing plate 59 becomes only s-polarized after passing through the polarizing plate 59, becomes circularly polarized after passing through the outer quarter-wave plate 151, and partially passes through the transmissive mirror 56. The circularly polarized ambient light OL that partially passes through the transmissive mirror 56 becomes p-polarized after passing through the inner quarter-wave plate 51, passes through the reflective polarizing element 45, and is incident on the pupil position PP.

[0087] In a specific embodiment, the virtual image display device comprises a display element that emits image light, a first prism into which the image light from the display element is incident, a second prism joined to the first prism to form a parallel plate-shaped prism light guide member, a reflective polarizing element provided at the joint between the first prism and the second prism via an adhesive member and reflecting at least a portion of the image light guided in the first prism, a lens having positive power and positioned opposite the outer surface of the first prism into which the image light reflected by the reflective polarizing element is incident, a transmissive mirror formed on the external side of the lens and partially reflecting the image light reflected by the reflective polarizing element toward the reflective polarizing element, and a quarter-wave plate positioned between the outer surface of the first prism and the lens, wherein the reflective polarizing element has a light deflection portion in the end region near the inner surface opposite to the outer surface.

[0088] In the above-described virtual image display device, the reflective polarizing element has a light deflection portion in the edge region near the inner surface. This allows unintended components of the image light to be deflected by the light deflection portion even if they are incident on the upper part of the first prism, thereby reducing unwanted light that causes ghosting and degrades image quality. As a result, it is possible to suppress the observation of ghosting around the virtual image being observed.

[0089] In a specific embodiment of the virtual image display device, the reflective polarizing element has adhesive members on the surface facing the first prism and the surface facing the second prism. In this case, since the first prism and the second prism are joined by the adhesive members provided on the reflective polarizing element, no separate adhesive is required.

[0090] In a specific embodiment of a virtual image display device, the reflective polarizing element selectively reflects image light in the main region, excluding the edge region, according to the polarization direction. In this case, it is possible to efficiently reflect image light in the normal optical path while limiting the reflection or transmission of unwanted light that causes ghosting in the edge region.

[0091] In a specific embodiment of a virtual image display device, the reflective polarizing element has a sawtooth shape in its end region as a light deflection portion. In this case, unintended image light can be diverted from the optical path leading to the pupil position.

[0092] In a specific embodiment of a virtual image display device, the reflective polarizing element has a scattering shape in its edge region as a light deflection portion. In this case, unintended image light can be diverted from the optical path leading to the pupil position.

[0093] In a specific embodiment of a virtual image display device, the size of the reflective polarizing element is smaller than the size of the inclined planes of the first and second prisms in the direction of inclination. In this case, unwanted light that causes ghosting can be prevented from entering the reflective polarizing element, and the reflection of unwanted light by the reflective polarizing element can be reduced.

[0094] In a specific embodiment of a virtual image display device, the reflective polarizing element is positioned away from the outer surface.

[0095] In a specific embodiment of the virtual image display device, the joint between the first prism and the second prism has a flat portion on the outer surface. In this case, by using the flat portion as a contact surface, the assembly of the first prism and the second prism can be facilitated.

[0096] In a specific embodiment, the optical unit comprises a first prism into which image light from a display element is incident; a second prism joined to the first prism to form a parallel plate-shaped prism light guide member; a reflective polarizing element provided at the joint between the first and second prisms via an adhesive member to reflect at least a portion of the image light guided in the first prism; a lens having positive power, positioned opposite the first outer surface of the first prism into which the image light reflected by the reflective polarizing element is incident; a transmissive mirror formed on the external side of the lens to partially reflect the image light reflected by the reflective polarizing element toward the reflective polarizing element; and a quarter-wave plate positioned between the outer surface of the first prism and the lens, wherein the reflective polarizing element has a light deflection portion in the end region near the inner surface opposite to the outer surface. [Explanation of Symbols]

[0097] 11…Display element, 30…First lens, 40…First flat plate member, 41…First prism, 41a…Incident optical surface, 41b…Inner surface, 41c…Outer surface, 41d…Inclined surface, 41e…Side surface, 42…Second prism, 42b…Inner surface, 42c…Outer surface, 42d…Inclined surface, 42e…Side surface, 42f…Bottom surface, 42g…Curved surface, 44…Lens part, 45…Reflective polarizing element, 45 a...Reflective polarizer, 48...Prism light guide member, 50...Second flat plate member, 50c...Inner surface, 51, 151...Quarter wave plate, 52...Cover member, 53...Second lens, 54...Compensating lens, 55...Compensating plate, 56...Transmitting mirror, 58...Optical element, 59...Polarizer, 61...Spacer, 71...Case, 90...User terminal, 100...Optical unit, 100A ,100B…Virtual image display device, 100C…Support device, 102a,102b…Display drive unit, 103a,103b…Combiner, AD…Adhesive member, AL…Light absorption layer, AX…Optical axis, BD…Saw blade shape, BDz…Saw cut, CR…Light focusing and reflecting part, DIS…Direct virtual image optical system, EA…End area, EP…Exit pupil, EY…Eye, FL…Flat area, GH1,GH2…Ghost, GL1~GL3…Unwanted light, IA…Image area, IS…Imaging optical system, JS…Joint area, LD…Light deflection part, LP…Image light blocking part, MA…Main area, ML…Image light, OL…Outside light, PF…Protective film, PLc…Circular polarization, PLp…p polarization, PLs…s polarization, PN…Gap, PP…Pupil position, RA…Slanted surface exposure area, SD…Scattering shape, ST…Slanted part, US…Wearer

Claims

1. A display element that emits image light, A first prism into which the image light from the display element is incident, A second prism is joined to the first prism to form a parallel plate-shaped prism light guide member, A reflective polarizing element is provided at the joint between the first prism and the second prism via an adhesive member, and reflects at least a portion of the image light guided in the first prism; A lens having positive power is positioned opposite the outer surface of the first prism into which the image light reflected by the reflective polarizing element is incident, A transmissive mirror formed on the external side of the lens, which partially reflects the image light reflected by the reflective polarizing element toward the reflective polarizing element, A quarter-wave plate is disposed between the outer surface of the first prism and the lens, Equipped with, The reflective polarizing element has an optical deflection portion in the end region near the inner surface opposite to the outer surface. Virtual image display device.

2. The reflective polarizing element has the adhesive member on the surface facing the first prism and the surface facing the second prism. The virtual image display device according to claim 1.

3. The reflective polarizing element selectively reflects the image light in the main region excluding the edge region according to the polarization direction. The virtual image display device according to claim 1.

4. The reflective polarizing element has a sawtooth shape in its end region as the light deflection portion. The virtual image display device according to claim 1.

5. The reflective polarizing element has a scattering shape in the end region as the light deflection portion. The virtual image display device according to claim 1.

6. The size of the reflective polarizing element is smaller than the size of the slope in the direction of inclination of the slopes of the first prism and the second prism. The virtual image display device according to claim 1.

7. The reflective polarizing element is positioned away from the outer surface. The virtual image display device according to claim 6.

8. The joint between the first prism and the second prism has a flat portion on the outer surface side. The virtual image display device according to claim 1.

9. A first prism into which the image light from the display element is incident, A second prism is joined to the first prism to form a parallel plate-shaped prism light guide member, A reflective polarizing element is provided at the joint between the first prism and the second prism via an adhesive member, and reflects at least a portion of the image light guided in the first prism; A lens having positive power is positioned opposite the first outer surface of the first prism into which the image light reflected by the reflective polarizing element is incident, A transmissive mirror formed on the external side of the lens, which partially reflects the image light reflected by the reflective polarizing element toward the reflective polarizing element, A quarter-wave plate is disposed between the outer surface of the first prism and the lens, Equipped with, The reflective polarizing element has an optical deflection portion in the end region near the inner surface opposite to the outer surface. Optical unit.

Images