Virtual image display device and optical unit

Abstract

The invention relates to a virtual image display device and an optical unit, which prevent useless light from reaching eyes. A virtual image display device includes: a display element; a first prism on which the image light from the display element is incident; a second prism joined to the first prism; an oblique mirror part which is provided at the joint of the first prism and the second prism and reflects at least a portion of the image light guided by the first prism; a second lens having a positive refractive power, the second lens being disposed so as to face the first outer surface of the first prism; and a transmissive mirror that is formed on the outside side of the second lens and partially reflects the image light reflected by the oblique mirror section toward the oblique mirror section, the oblique mirror section being formed so as to correspond to partial regions of the oblique surfaces of the first prism and the second prism excluding the peripheries thereof.

Description

Technical Field

[0001] This invention relates to a direct virtual image type virtual image display device and optical unit capable of observing virtual images. Background Technology

[0002] As a head-worn display device, there is a known head-worn display device 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. Image light from the liquid crystal image display panel is incident on the beam splitter and reflected by the beam splitting surface of the beam of polarized light in the first direction. When reflected by the concave mirror, it oscillates on the quarter-wave plate and passes through the beam splitter as polarized light in the second direction (see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Publication No. 2003-502710

[0004] The aforementioned head-mounted display device does not generate an intermediate image and lacks an optical aperture. Therefore, it creates a problem where unwanted light is trapped within the light guide plate, resulting in useless light reaching the eye. Summary of the Invention

[0005] A virtual image display device according to one aspect of the present invention includes: a display element that emits image light; a first prism into which the image light from the display element is incident; a second prism that is joined with the first prism to form a parallel plate-shaped prism light guide member; an oblique mirror portion disposed at the joint of the first prism and the second prism, which reflects at least a portion of the image light guided in the first prism; a lens having positive optical power disposed facing the outer side of the first prism into which the image light reflected by the oblique mirror portion is incident; and a transmissive mirror formed on the outer side of the lens, which partially reflects the image light reflected by the oblique mirror portion toward the oblique mirror portion, wherein the oblique mirror portion is formed corresponding to a portion of the oblique surfaces of the first prism and the second prism, excluding the periphery.

[0006] An optical unit according to one aspect of the present invention comprises: a display element that emits image light; a first prism that receives image light from the display element; a second prism that is joined with the first prism to form a parallel plate-shaped prism light guide; an oblique mirror portion disposed at the junction of the first prism and the second prism, which reflects at least a portion of the image light guided in the first prism; a lens having positive optical power disposed facing the outer side of the first prism to receive image light reflected by the oblique mirror portion; and a transmissive mirror formed on the outer side of the lens, which partially reflects the image light reflected by the oblique mirror portion toward the oblique mirror portion, wherein the oblique mirror portion is formed correspondingly to a portion of the oblique surfaces of the first prism and the second prism, excluding the periphery. Attached Figure Description

[0007] Figure 1This is an external view illustrating the usage state of the virtual image display device according to the first embodiment.

[0008] Figure 2 This is a side sectional view illustrating the internal structure of a single-sided virtual image display device.

[0009] Figure 3 It is a three-dimensional view of the virtual image display device.

[0010] Figure 4 This is an exploded view of the first flat plate component.

[0011] Figure 5 It is a conceptual three-dimensional diagram illustrating the formation range of the oblique mirror portion.

[0012] Figure 6 This is a side cross-sectional view of the prism light guide component.

[0013] Figure 7 This is an enlarged cross-sectional view illustrating the reflective polarizing element pasted before the prism.

[0014] Figure 8 Yes Figure 2 The diagram illustrates the optical path of the virtual image display device shown.

[0015] Figure 9 It is a conceptual diagram that specifically illustrates the useless light incident on the upper part of the first prism.

[0016] Figure 10 It is a conceptual diagram that specifically illustrates the optical path of useless light incident on the first prism.

[0017] Figure 11 It is a conceptual diagram that specifically illustrates the optical paths of other useless light incident on the first prism.

[0018] Figure 12 This is a diagram illustrating the projection state of useless light in a device of a prior art or embodiment.

[0019] Figure 13 This is a side sectional view illustrating the virtual image display device of the third embodiment.

[0020] Figure 14 This is a side sectional view illustrating a modified example of a virtual image display device.

[0021] Explanation of reference numerals in the attached figures

[0022] 1…display element, 30…first lens, 40…first flat plate component, 41…first prism, 41a…incident optical surface, 41b…inner surface, 41c…outer surface, 41d…sloping surface, 41e…lateral surface, 42…second prism, 42b…inner surface, 42c…outer surface, 42d…sloping surface, 42e…lateral surface, 42f…bottom surface, 42g…curved surface, 44…lens section, 45…reflective polarizing element, 45 a…reflective polarizing plate, 48…prism light guide component, 48i…central portion, 50…second flat plate component, 50c…inner side surface, 51, 151…1 / 4 wavelength plate, 52…cover component, 53…second lens, 54…compensating lens, 55…compensating plate, 56…transmissive mirror, 58…optical element, 59…polarizing plate, 61…spacer, 71…housing, 90…user terminal, 100…optical unit, 100A 100B…Virtual image display device, 100C…Support device, 102a, 102b…Display driving unit, 103a, 103b…Assembler, IM…Angled mirror unit, RP…Rectangular plane, AA…Partial area, AS…Positioning structure, AD…Adhesive component, AL…Light absorption layer, AX…Optical axis, CR…Condensing reflector, DIS…Direct virtual image optical system, EP…Exit pupil, EY…Eye, FL…Flat area, GH1…Ghosting, GL1~GL3…Useless light, IA…Image area, IS…Imaging optical system, JS…Jointing part, LP…Image light blocking part, ML…Image light, OL…Outer light, PF…Protective film, PLc…Circularly polarized light, PLp…P-polarized light, PLs…S-polarized light, PN1, PN2…Gap, PP…Pupil position, RA…Angled exposed area, ST…Angled surface, US…Wearer. Detailed Implementation

[0023] [First Implementation]

[0024] The following is for reference Figure 1 and Figure 2 The first embodiment of the virtual image display device and the like according to the present invention will be described.

[0025] Figure 1 This diagram 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 enables the observer or wearer US to recognize an image as a virtual image. Figure 1 In this system, X, Y, and Z are orthogonal coordinates. The +X direction corresponds to the horizontal alignment of the EY pairs of the observer's or wearer's eyes (US) when wearing the HMD200. The +Y direction is equivalent to the upward direction orthogonal to the horizontal alignment of the wearer's eyes (US). The +Z direction corresponds to the frontal or facing direction of the wearer's US. The ±Y directions are parallel to the vertical axis or the vertical direction.

[0026] The HMD 200 includes: a first virtual image display device 100A of direct virtual image type for the right eye; a second virtual image display device 100B of direct virtual image type for the left eye; a pair of temple-shaped support devices 100C supporting these virtual image display devices 100A and 100B; and a user terminal 90 serving as an information terminal. The first virtual image display device 100A functions as an HMD independently, consisting of a first display driving unit 102a disposed on the upper part and a first combiner 103a covering the eyes in an eye-like shape. Similarly, the second virtual image display device 100B functions as an HMD independently, consisting of a second display driving unit 102b disposed on the upper part and a second combiner 103b covering the eyes in an eye-like shape. The support devices 100C are wearing components worn on the head of the wearer US. The support devices 100C support the upper sides of the pair of combiners 103a and 103b via the externally integrated display driving units 102a and 102b. The first virtual image display device 100A and the second virtual image display device 100B are optically identical or reversed left and right.

[0027] Figure 2 This is a side sectional view illustrating the internal structure of the first virtual image display device 100A. Figure 3 This 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 component 80a. The first image forming element 11a is also referred to as the 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 component 40, and a second flat plate component 50. The first lens 30 functions as a protective glass for the display surface 11d of the display element 11. Alternatively, a cover glass may be provided between the display element 11 and the first lens 30. The first flat plate component 40 guides the image light ML emitted from the display element 11 to the second lens 53 of the second flat plate component 50. The second plate-shaped member 50 causes the image light ML from the first plate-shaped member 40 to be reflected towards the pupil position PP or the eye EY in a manner that partially returns to the first plate-shaped member 40, and causes external light OL to be incident on the pupil position PP via the first plate-shaped member 40. The first lens 30, the first plate-shaped member 40 and the second plate-shaped member 50 each function as a lens with positive refractive power.

[0028] Detailed description omitted, but the second virtual image display device 100B includes a second image forming element 11b, a second display unit 20b, and a second circuit component 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 component 80b is the same as the first circuit component 80a.

[0029] In the first virtual image display device 100A, the first image forming element 11a is a self-emissive image light generating device. The first image forming element 11a emits image light ML through the first lens 30 onto the first flat panel member 40. The first image forming element 11a is housed and supported in a housing 71. The first image forming element 11a is, for example, an organic EL (organic electro-luminescence) display. The first image forming element 11a forms a colored 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 organic EL display and can be replaced by a display device using inorganic EL, organic LED, LED array, laser array, quantum dot light-emitting elements, etc. The first image forming element 11a is not limited to a self-emissive image light generating device and can also be composed of other light modulation elements such as an LCD, forming an image by illuminating the light modulation element with a light source such as a backlight. As the first image forming element 11a, LCOS (Liquid crystal on silicon; LCoS is a registered trademark) or similar technology can be used instead of LCD. Furthermore, in the first virtual image display device 100A, the optical devices other than the first circuit component 80a are referred to as the optical unit 100. The optical unit 100 includes a direct virtual image type optical system, and can also be considered as part of the direct virtual image optical system DIS constituting the first virtual image display device 100A.

[0030] The first display unit 20a includes a first lens 30, a first flat plate member 40, an oblique mirror portion 1M, and a second flat plate member 50. In the first display unit 20a, the first lens 30 has positive refractive power and is incident on image light ML from the first image forming element 11a. The first lens 30 has a planar light incident surface 30f that is 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 also be an aspherical surface with an axisymmetric shape. The first lens 30 can be considered as consisting of a parallel plate 31 and a lens portion 32. By ensuring that the thickness of the parallel plate 31 is above a specified value, foreign matter attached to the surface of the first lens 30 becomes less noticeable. The parallel plate 31 functions as a cover glass. The lens portion 32 is a plano-convex lens with positive refractive power. One surface of the plano-convex lens has a planar shape, and the other surface has a convex shape. Furthermore, the parallel plate 31 and the lens portion 32 can be bonded together or separated. The lens portion 32 may not be a plano-convex lens; for example, it may be a biconvex lens. Additionally, the first lens 30 may be made of fused silica, which has a relatively low refractive index.

[0031] The first flat plate component 40 has a first parallel plate-shaped prism 41 and a second parallel plate-shaped prism 42. The first prism 41 and the second prism 42 are joined at inclined surfaces 41d and 42d while the inclined mirror portion IM is sandwiched between them. The component formed by joining the first prism 41 and the second prism 42 is called the prism light guide component 48. The prism light guide component 48 has the appearance of a parallel plate. The component formed by combining the prism light guide component 48 with the second flat plate-shaped component 50 (described later) is equivalent to the first combiner 103a.

[0032] Figure 4 This is an exploded view of the first flat plate component 40. (See diagram below.) Figures 2-4As shown, the first prism 41 has a quadrangular prism shape and a trapezoidal longitudinal 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. In addition, the first prism 41 has an upper plane 40u and a first transverse surface 41e. Here, the incident optical surface 41a is inclined downward in the forward direction, and the optical axis through the incident optical surface 41a extends in the direction between the +Z direction as the front and the +Y direction as the top. As a result, the first image forming element 11a, which is the display element 11, can be easily positioned on the outer side of the first inner surface 41b, and the angle at which the image light ML propagates in the first prism 41 (in the first prism 41 or inside the first prism 41) can be adjusted. The incident optical surface 41a is a convex surface, such as a spherical surface, but it can also be an axisymmetric aspherical surface. It can be considered that the first prism 41 has a lens portion 44 including the incident optical surface 41a. Lens portion 44 is a convex planar lens with positive refractive power. Lens portion 44 can be formed directly on the first prism 41 or bonded to the first prism 41. The first inner surface 41b and the first outer surface 41c are parallel to each other and extend perpendicularly to the optical axis AX between the pupil position PP. The first inner surface 41b and the first outer surface 41c internally reflect the image light ML (i.e., reflect it inside the object surface), but total internal reflection is particularly preferred. The first inner surface 41b can be made scratch-resistant or abrasion-resistant by implementing a hard coating. The first transverse surface 41e is disposed opposite the first outer surface 41c and the first inner surface 41b in the transverse direction (X direction) that intersects the Y direction (the direction in which the first prism 41 and the second prism 42 are arranged). 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°. Furthermore, the optical axis AX passing through the pupil position PP is approximately 20mm away from the upper end of the first lens 30. The first prism 41 is formed of resin material.

[0033] The image light ML in the first prism 41 is reflected once on the first inner surface 41b, once on the first outer surface 41c, and once in the oblique mirror portion IM (described later). By setting the number of internal reflections of the image light ML in the first prism 41 to twice, the viewing angle, pupil position PP, or opening PPa of the image light ML can be increased, and the mixing of light with different reflection counts within the first prism 41 can be effectively avoided. In addition, the distance from the display element 11 to the transmissive mirror 56 of the cover member 52 (described later) can be shortened, enabling miniaturization of the prism light guide member 48, as well as the display element 11 and the first lens 30.

[0034] Like the first prism 41, the second prism 42 has a quadrangular prism shape and a trapezoidal longitudinal section. The second prism 42 allows image light ML to pass through. The second prism 42 has a second inner surface 42b, a second outer surface 42c, a second inclined surface 42d, and a bottom surface 42f. The bottom surface 42f is the surface opposite to the incident optical surface 41a in the prism light guide member 48 or the first flat plate member 40. Furthermore, the bottom surface 42f is the surface opposite to the second inclined surface 42d in the second prism 42. Additionally, the second prism 42 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 perpendicularly to the optical axis AX between the pupil position PP. The second inner surface 42b has improved scratch resistance or abrasion resistance by implementing a hard coating. The second prism 42 is formed of resin material. The second transverse side 42e is disposed opposite to the second outer side 42c and the second inner side 42b in the transverse 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 arranged.

[0035] The inclined surface ST of the joint JS of the first prism 41 and the second prism 42 has a flat portion FL on the first and second outer surfaces 41c and 42c. Two flat portions FL are continuously formed from the lower ends of the first inclined surface 41d and the second inclined surface 42d. The two flat portions FL extend approximately parallel to the XZ plane, forming an obtuse angle with respect to the first inclined surface 41d and the second inclined surface 42d. The flat portions FL are positioning structures AS provided around the inclined surfaces 41d and 42d of the first prism 41 and the second prism 42. When the first prism 41 and the second prism 42 are joined, by positioning and bringing these inclined surfaces 41d and 42d close to each other, the pair of flat portions FL adjacent to the inclined surfaces 41d and 42d also abut and adhere tightly to each other as mutually parallel extending abutment surfaces AF. Therefore, the first prism 41 and the second prism 42 can be positioned in the inclination direction of these inclined surfaces 41d and 42d, that is, in the direction between the Z and Y directions, and can be positioned around the axis perpendicular to the inclined surfaces 41d and 42d. As a result, the flat portion FL positions the first prism 41 and the second prism 42 in the +Z direction or the depth direction, and sets their relative rotational postures according to the design. By setting the flat portion FL as the abutment surface AF, not only is the assembly of the first prism 41 and the second prism 42 easier, but it can also function as an offset prevention part. Therefore, the joining accuracy of the first prism 41 and the second prism 42 can be improved. Between the first prism 41 and the second prism 42, gaps PN1 and PN2 are formed in the area where the inclined mirror portion IM is not provided (see reference). Figure 2 And as will be discussed later Figure 6The distance from the lower end of the oblique mirror portion IM to the outer surfaces 41c and 42c is relatively easy to increase, making it easier to provide a flat portion FL, i.e., a positioning structure AS. Furthermore, if the non-reflective area can be sufficiently ensured, the joint portion JS of the first prism 41 and the second prism 42 can also have a flat portion serving as a positioning structure AS on the first and second inner surfaces 41b and 42b.

[0036] The oblique mirror portion IM reflects at least a portion of the image light ML guided in the first prism 41. The oblique mirror portion IM is disposed at the joint portion JS of the first prism 41 and the second prism 42 via the adhesive member AD. That is, the oblique mirror portion IM is adhered to the first inclined surface 41d of the first prism 41 and the second inclined surface 42d of the second prism 42 via the adhesive member AD. Details will be described later, but the oblique mirror portion IM is formed in a narrow ring area of ​​the inclined surfaces 41d and 42d of the first prism 41 and the second prism 42, excluding the outer edges.

[0037] In this embodiment, the oblique mirror portion IM is a reflective polarization element 45. The reflective polarization element 45 is, for example, a polarization beam splitter with s-polarized light reflection characteristics. When the image light ML contains s-polarized light PLs, the reflective polarization element 45 efficiently reflects the image light ML containing s-polarized light PLs; when the image light ML contains p-polarized light PLp, it efficiently transmits the image light ML containing p-polarized light PLp. The reflective polarization element 45 only needs to selectively reflect the image light ML according to the polarization direction. Furthermore, the reflective polarization element 45 can also allow s-polarized light PLs to pass through and reflect p-polarized light PLp.

[0038] Examples of reflective polarizing elements 45 include multilayer films, wire grid films, and other wire grid-type polarizers, as well as reflective polarizing elements that utilize film stretching.

[0039] The slanted mirror portion IM only needs to have a flat surface that does not affect the image formation. Alternatively, the slanted mirror portion IM can also have a slightly curved surface, either convex or concave, that does not affect the image formation. Applying a hard coating to the surface of the slanted mirror portion IM can improve its scratch resistance or abrasion resistance.

[0040] Details regarding the formation range and structure of the oblique mirror portion IM will be described later.

[0041] like Figure 2As shown, the second plate-shaped component 50 has a thin plate-shaped quarter-wavelength plate 51 and a cover component 52. The quarter-wavelength plate 51 is formed of a crystal, liquid crystal material, or the like that having an optical axis between the X and Y directions. The quarter-wavelength plate 51 causes the image light ML of s-polarized light PLs reflected by the oblique mirror portion IM, which serves as a reflective polarizing element 45, to become circularly polarized light PLC, and causes the image light ML of circularly polarized light PLC reflected by the cover component 52 to become p-polarized light PLp. The cover component 52 has: a plano-convex second lens 53 with positive optical power; a concave-flat compensation lens 54; a compensation plate 55 disposed around the compensation lens 54 and extending parallel to the prism light guide component 48; and a transmissive mirror 56.

[0042] The second flat plate member 50 is positioned approximately 20 μm to 100 μm apart from the first flat plate member 40. 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 may be slightly curved, and minute steps may form at the boundaries of the first and second outer surfaces 41c, 42c. However, by setting the interval 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, excessive closeness between these surfaces can be avoided. Conversely, by setting the interval between the first and second outer surfaces 41c, 42c and the third inner surface 50c to 100 μm or less, an increase in the thickness of the first assembler 103a formed by combining the first flat plate member 40 and the second flat plate member 50 can be avoided. A spacer 61 is provided between the first and second outer surfaces 41c and 42c of the first flat plate member 40 and the third inner surface 50c of the second flat plate member 50, for fixing the first flat plate member 40 and the second flat plate member 50 in a mutually positioned state by adjusting the interval between them. The spacer 61 is not provided throughout the entire circumference of the second flat plate member 50. That is, the gap SP between the first flat plate member 40 and the second flat plate member 50 is not sealed and is open to the outside.

[0043] In the cover component 52, the second lens 53 is disposed opposite to 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 plano-convex lens with positive refractive power. One surface of the plano-convex lens has a planar shape, and the other surface has a convex shape on the outer side. The second lens 53 has a plane 53f that engages with the quarter-wave plate 51 and a convex surface 53g that opposes the compensation lens 54. The convex surface 53g is, for example, a spherical surface, but can be an axisymmetric aspherical surface. The compensation lens 54 is thin but has positive refractive power. The compensation lens 54 has a concave surface 54f and a plane 54g that oppose the second lens 53. The compensation plate 55 is a parallel plate. The compensation plate 55 has a pair of planes 55f and 55g. Here, the concave surface 54f of the compensation lens 54 has the same shape as 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 continuous on the same plane. The transmissive mirror 56 is a thin film formed on the convex surface 53g on the outer side of the second lens 53, and has the same shape as the convex surface 53g. The component formed by combining the second lens 53 and the transmissive mirror 56 is called the light-concentrating reflector CR.

[0044] The second lens 53, the compensating lens 54, and the compensating plate 55 are formed 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 of the same resin material.

[0045] The component consisting of the second lens 53, the compensating lens 54, and the compensating plate 55 functions as a parallel plate. That is, external light OL incident on the compensating lens 54 and the compensating plate 55 passes through them without being affected by the lens action of the compensating lens 54 or the step existing on the outer edge of the compensating lens 54. Thus, the compensating lens 54 optically compensates for the influence of the second lens 53 on external light OL. In this sense, the plane 53f of the second lens 53, the plane 54g of the compensating lens 54, and the planes 55f and 55g of the compensating plate 55 are not necessarily strictly planes; for example, they can be approximately planes, or they can partially or entirely include curved surfaces. Furthermore, the planes 53f of the second lens 53, 54g of the compensating lens 54, and 55f and 55g of the compensating plate 55 can also include curved surfaces for correcting the wearer's (US) vision, such as those used in sunglasses or Iida glasses, without causing adverse optical performance. The planes 54g and 55g of the compensation lens 54 and compensation plate 55 can be planes with an anti-reflective film or a hard coating. External light OL passes through the compensation plate 55 and is incident on the compensation lens 54 from the top, bottom, left, and right sides. This external light OL enters from the surrounding area outside the incident area of ​​the image light ML corresponding to the compensation lens 54, i.e., the compensation plate 55. Therefore, a wide field of view relative to the outside world can be ensured. The field of view of the external light OL is, for example, set to approximately 40° upwards and approximately 40° downwards.

[0046] The transmissive mirror 56 is a semi-transparent, semi-reflective mirror. The transmissive mirror 56 partially reflects the image light ML that has passed through the second lens 53, and partially allows external light OL to pass through. The transmissive mirror 56 reflects the image light ML, which has been reflected by the oblique mirror portion IM of the first flat plate member 40 or the reflective polarizing element 45 and passed through the quarter-wave plate 51 and the second lens 53, toward the pupil position PP. The transmissive mirror 56 is a concave mirror that covers the pupil position PP, where the eye EY or pupil is positioned, and has a concave shape toward the pupil position PP and a convex shape toward the outside. The pupil position PP or its opening PPa is called the eyepoint or eye movement range, corresponding to the exit pupil EP of the first display unit 20a.

[0047] The transmissive mirror 56 allows a portion of the external light OL to pass through, thus enabling perspective observation of the outside world and allowing the virtual image to overlap with the external image. At this time, the external light OL passes through the first plate-shaped member 40 and the second plate-shaped member 50, but the plate-shaped members 40 and 50 do not act as lenses for the external light OL. From the viewpoint of ensuring the brightness of the image light ML and facilitating perspective observation of the external image, the reflectivity of the transmissive mirror 56 to the image light ML and the external light OL is between 10% and 50% within the assumed incident angle range of the image light ML. The transmissive mirror 56 is, for example, formed of a dielectric multilayer film consisting of multiple dielectric layers with adjusted film thickness. The transmissive mirror 56 can 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, for example, formed by using vapor deposition layering.

[0048] 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 a tendency to converge divergent light. The first lens 30, lens section 44, second lens 53, and transmissive mirror 56 also include a main body of a first prism 41, a second prism 42, etc., functioning as an imaging optical system IS or a direct virtual image optical system DIS, similar to a single-lens microscope that forms an upright image. Thus, a virtual image can be formed by projecting a real image formed on the display surface 11d of the first image forming element 11a, for example, onto a point at noon, or a virtual image can be formed by projecting a real image formed on the display surface 11d onto a point several meters in front. At this time, 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 the desired magnification.

[0049] The longitudinal dimension of the first flat plate component 40 or the second flat plate component 50 is, for example, 34 mm, and its transverse dimension is, for example, 40 mm. The thickness of the first flat plate component 40 in the front-to-back direction is, for example, about 7 mm to 8 mm, and the thickness after combining the first flat plate component 40 and the second flat plate component 50 is suppressed to about 7.5 mm to 8.5 mm.

[0050] In the first prism 41 of the first flat component 40, the incident optical surface 41a, the first inner surface 41b, and the first outer surface 41c may become 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 stop cannot be provided, and the image light ML is more likely to be observed as a ghost by taking an unwanted optical path to reach the pupil position PP. In the prior art prior to the present invention, by providing a light absorption layer AL at an appropriate location in the first flat component 40 or the prism light guide component 48, the above-mentioned ghosting suppression can be achieved (see reference). Figure 3 ).

[0051] 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 serves as the incident surface 40i of the first prism 41. Furthermore, 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, leaving the upper plane 40u exposed in the region near the lateral sides 41e and 42e.

[0052] Additionally, a light-absorbing layer AL is also provided on the bottom surface 42f of the prism light guide component 48 or the second prism 42. This light-absorbing layer AL also prevents the image light ML passing through the oblique mirror portion IM or 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 transverse side surface 42e. Preferably, 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 transverse side surface 42e of the second prism 42.

[0053] Furthermore, a light-absorbing layer AL is also provided on the upper part 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 strip-shaped region in the horizontal X direction at the upper end of the first outer surface 41c.

[0054] As described above, even if a light-absorbing layer AL is provided at an appropriate location on the prism light guide component 48, image light ML that has bypassed the desired light path may still remain, resulting in a significant amount of useless light remaining outside the image area and causing ghosting. In this embodiment, in order to suppress the aforementioned ghosting, the formation range of the oblique mirror portion IM or the reflective polarizing element 45 is adjusted to efficiently reflect the image light ML of the normal light path and suppress the reflection of components in the image light ML that have passed through the desired light path and become the cause of ghosting.

[0055] Figure 5This is a conceptual perspective view illustrating the formation range of the oblique mirror portion IM. The oblique mirror portion IM is formed in a portion AA of the inclined surfaces 41d and 42d of the first prism 41 and the second prism 42, excluding the periphery or outer periphery. That is, the oblique mirror portion IM is formed in such a way that it covers the main region AI of the inclined surfaces 41d and 42d, excluding the end regions. More specifically, consider an imaginary rectangular plane RP extending between the inner surfaces 41b and 42b and the outer surfaces 41c and 42c along the central portion 48i of the inclined surfaces 41d and 42d of the first prism 41 and the second prism 42, and the portion AA of this rectangular plane RP, excluding the outer periphery, is formed accordingly. Specifically, the portion AA is the region of the rectangular plane RP excluding the outer end region Z1 near the outer surfaces 41c and 42c, the inner end region Z2 near the inner surfaces 41b and 42b, and the transverse end regions Z3 and Z4 near the transverse surfaces 41e and 42e. The outer end region Z1, the inner end region Z2, and the transverse end regions Z3 and Z4 are the sloped exposed regions RA. These regions Z1, Z2, Z3, and Z4 are collectively referred to as the end regions of the slopes 41d and 42d. Assuming that the image light ML is incident on the outer end region Z1, the inner end region Z2, and the transverse end regions Z3 and Z4 via an unwanted optical path and is reflected, it is then reflected by the first outer surface 41c and the transmissive mirror 56, becoming stray light incident on the pupil position PP, thus causing ghosting. That is, if a slanted mirror portion IM is formed in the region AA excluding the outer end region Z1, the inner end region Z2, and the transverse end regions Z3 and Z4, and the sloped exposed regions RA are provided, the generation of ghosting can be suppressed.

[0056] In the above, the width W1 of the outer end region Z1 in the tilt direction is wider than the width W2 of the inner end region Z2 in the tilt direction. Furthermore, the width W1 of the outer end region Z1 in the tilt direction is wider than the width W3 and W4 of the horizontal or X-direction of the horizontal end regions Z3 and Z4. The image light ML in a typical optical path is more affected by the blockage of the inner end region Z2 than the outer end region Z1. Therefore, by making the width W1 of the outer end region Z1 in the tilt direction wider than the width W2 of the inner end region Z2 in the tilt direction, it is easier to prevent the deterioration of the virtual image display state. Furthermore, from the viewpoint of making the prism light guide member 48 thinner, there is a desire to ensure that the lower end of the effective image light ML incident on the first inner surface 41b is incident as close as possible to the upper end of the oblique mirror portion IM, and to prevent the image light ML from passing through the gap between the first inner surface 41b and the upper end of the oblique mirror portion IM. Therefore, it is preferable that the inner end region Z2 is narrower.

[0057] In this embodiment, a flat portion FL serving as a positioning structure AS is provided near the outer end region Z1. Since the oblique mirror portion IM cannot be provided in the flat portion FL, the outer end region Z1 needs to extend upwards beyond the upper end of the flat portion FL.

[0058] Figure 6This is a side sectional view of the prism light guide component 48. (Refer to...) Figure 6 The structure of the oblique mirror section IM and its surrounding parts is explained.

[0059] The oblique mirror portion IM has adhesive members AD on the surface opposite to the first prism 41 and the surface opposite to the second prism 42. Thus, the first prism 41 and the second prism 42 are joined by the adhesive members AD provided on the oblique mirror portion IM, so no additional adhesive is required.

[0060] Figure 7 This is an enlarged cross-sectional view illustrating the oblique mirror section IM pasted before the first prism 41 and the second prism 42. (Example) Figure 7 As shown, the main body of the oblique mirror IM is specifically the reflective polarizing element 45. Adhesive members AD are provided on both sides 45j and 45k of the reflective polarizing plate 45a, which serves as the main body of the reflective polarizing element 45. The reflective polarizing element 45 is a reflective polarizing plate with an adhesive film, constructed by combining a flat or film-shaped reflective polarizing plate 45a with the adhesive members AD. The overall thickness d1 of the reflective polarizing element 45 is, for example, 78 μm to 80 μm. The thickness d2 of the reflective polarizing plate 45a in the reflective polarizing element 45 is, for example, 70 μm to 75 μm. The thickness d3 of the adhesive members AD is, for example, 2 μm to 5 μm.

[0061] 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 the second prism 42 to be bonded. The thickness of OCA is uniform or substantially uniform, with minimal product deviation. In addition, unlike adhesives, excess adhesive will not overflow with OCA.

[0062] 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 referred to as the blank part 45x. The reflective polarizing element 45 is formed by demolding the blank part 45x using a Thomson mold (not shown).

[0063] like Figure 4 As shown, the size of the reflective polarizing element 45 is smaller than the size of the inclined surfaces 41d and 42d in the tilting direction of the first prism 41 and the second prism 42. That is, the reflective polarizing element 45 is not provided at the upper and lower ends of the inclined surfaces 41d and 42d. Therefore, as... Figure 6As shown, when the reflective polarization element 45 is clamped by the first and second prisms 41 and 42, a gap PN1 is formed on the outer side and a gap PN2 is formed on the pupil position PP side. Through these gaps PN1 and PN2, a beveled exposed area RA exists at the joint JS of the prism light guide component 48. Through the beveled exposed area RA, the reflection area of ​​the image light ML on the reflective polarization element 45 in the beveled area ST is limited, allowing unwanted image light ML to pass through in an allowable area around the reflective polarization element 45. That is, unwanted light that causes ghosting can be prevented from incident on the reflective polarization element 45, and the reflection of unwanted light on the reflective polarization element 45 can be reduced.

[0064] The oblique mirror portion IM is positioned approximately 3 mm away from the lower end of the first inclined surface 41d of the first prism 41 or the second inclined surface 42d of the second prism 42. The oblique mirror portion IM is positioned approximately 1 mm away from the upper end of the first inclined surface 41d of the first prism 41 or the second inclined surface 42d of the second prism 42. Furthermore, the oblique mirror portion IM can also be positioned from the lower end of the inclined surfaces 41d and 42d by adjusting the length of the flat portion FL. The oblique mirror portion IM can also be positioned approximately 1 mm away from the transverse sides 41e and 42e of the first prism 41 or the second prism 42.

[0065] Figure 8 This diagram illustrates the optical path, etc., of the first virtual image display device 100A. (For example...) Figure 8 As shown, 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 image light ML's divergence is suppressed by the positive refractive power of the first lens 30 and the lens portion 44. In the optical path through the first prism 41, the image light ML does not form an intermediate image and is sequentially reflected by the first inner surface 41b and the first outer surface 41c of the first prism 41 (see reference). Figure 2The s-polarized light PLs in the image light ML is reflected by the reflective polarization element 45 of the oblique mirror IM. The image light ML of the s-polarized light PLs after being reflected by the reflective polarization element 45 passes through the first outer surface 41c of the first prism 41, passes through the quarter-wave plate 51 of the second flat member 50, and thus becomes circularly polarized light PLC, which is then incident on the second lens 53 and the transmission mirror 56. A portion of the image light ML of the circularly polarized light PLC incident on the transmission mirror 56 is reflected by the transmission mirror 56 after passing through the second lens 53, and passes through the quarter-wave plate 51 again after being collimated by the second lens 53. Thus, the image light ML that has passed through the quarter-wave plate 51 becomes p-polarized light PLp and is incident on the first prism 41 from the first outer surface 41c, passes through the reflective polarization element 45, and exits outside the second prism 42 via the second inner surface 42b. The image light ML that exits outside the second prism 42 is incident on the pupil position PP (refer to the image light ML) for the wearer's eye EY or pupil. Figure 2 Not only the image light ML reflected by the transmissive mirror 56, but also the external light OL that passes through the transmissive mirror 56 and the external light OL that passes through the compensation plate 55 are incident on the pupil position PP. That is, the wearer US wearing the first virtual image display device 100A can observe the virtual image based on the image light ML by superimposing it with the external image. In this embodiment, the useless light GL1 to GL3 described below are limited by the inclined exposed area RA around the reflective polarizing element 45, thereby suppressing the observation of ghosting.

[0066] Figure 9 This is a conceptual diagram illustrating the unwanted light GL1 caused by image light ML incident on the upper part UP of the first prism 41 from an unwanted light path. In this case, the unwanted light GL1 is reflected sequentially by the first inner surface 41b and the first outer surface 41c at a location outside the predetermined area on the upper part UP of the first prism 41. As a result, the unwanted light GL1 is reflected twice by the first inner surface 41b and the first outer surface 41c within the first prism 41, passes through the oblique mirror IM and the transmissive mirror 56, and together with the image light ML from the normal light path, is incident at an angle of approximately 17° from a downward direction onto the pupil position PP (see reference). Figure 2 The light GL1 used forms a ghost image outside the image area of ​​the virtual image and below the image area. However, such a useless light GL1 is set in... Figure 3 The light absorption layer AL restricts the passage of light through the upper region 41u and the upper plane 40u, as shown in the figure, and the observation of ghosting is suppressed.

[0067] Figure 10An example is given of the optical path of unwanted light GL2 caused by other image light ML incident on the incident optical surface 41a of the first prism 41 from an unwanted optical path. In this case, the unwanted light GL2 is reflected at the boundary between the first prism 41 and the second prism 42 and at the upper end of the oblique mirror portion IM, deviating from the optical path. After passing through the transmissive mirror 56, it is incident at an angle of about 20° from an upward direction onto the pupil position PP (see reference). Figure 2 The useless light GL2 forms a ghost image outside the image area of ​​the virtual image and above the image area. However, such useless light GL2 has an exposed area RA due to the slope (refer to...). Figure 4 The presence of (etc.) means that the passage is restricted by limiting the size of the oblique mirror portion IM on the PP side of the pupil position, and the observation of ghosting is suppressed.

[0068] Figure 11 An example is given of the optical path of unwanted light GL3 caused by other image light ML incident on the incident optical surface 41a of the first prism 41 from an unwanted optical path. In this case, the unwanted light GL3 is reflected sequentially by the first inner surface 41b and the first outer surface 41c, and instead of passing through the oblique mirror portion IM, it is incident on the transmissive mirror 56. Instead, it is reflected by the first outer surface 41c and incident at an angle of approximately 13° from the downward direction at the pupil position PP (see reference). Figure 2 The useless light GL3 forms a ghost image outside the image area of ​​the virtual image and below the image area. However, such useless light GL3 has an exposed area RA due to the slope (refer to...). Figure 4 The presence of (etc.) means that by using the outer side or the second lens 53 to limit the size of the outer side of the oblique mirror IM, the observation of ghosting is suppressed.

[0069] Figure 12 This is a diagram illustrating the projection state of useless light in a virtual image display device. Figure 12 Area AR1 in the diagram illustrates the projection state of the useless light in the virtual image display device of the comparative example. Figure 12 Figure AR2 illustrates the projection state of useless light in the virtual image display device 100A of the embodiment related to this embodiment. In the comparative example device, a reflective polarization element 45 is formed integrally on the rectangular plane RP or the inclined surfaces 41d and 42d. On the other hand, in the embodiment device, the reflective polarization element 45 is formed in the area of ​​the inclined surfaces 41d and 42d except for the outer periphery.

[0070] exist Figure 12 In the figure area AR1, the left chart group C1 assumes that an eye EY is positioned above the pupil position PP in the comparative example device; the central chart group C2 assumes that an eye EY is positioned in the center of the pupil position PP; and the right chart group C3 assumes that an eye EY is positioned below the pupil position PP. Similarly, in Figure 12In the diagram area AR2, the left-hand chart group C1 assumes that the eye EY is positioned above the pupil position PP in the device of the embodiment; the central chart group C2 assumes that the eye EY is positioned in the center of the pupil position PP; and the right-hand chart group C3 assumes that the eye EY is positioned below the pupil position PP. Chart group C1 corresponds to the observed... Figure 11 The state of useless light GL3, chart group C3 corresponds to the observed state. Figure 10 The state of useless light GL2.

[0071] In each of the chart groups C1, C2, and C3, a simulated image is shown in the left area. This simulated image represents the detection status of the angled light receivers positioned above and below the pupil position PP when displaying a full white image on the display element 11. On the right side of this simulated image, a chart showing the logarithmic distribution of brightness along the vertical axis centered at 0° on the H-axis (horizontal axis) is shown. As a premise of the simulation, the angled light receivers were evaluated within a 3mm diameter area set above, middle, and below the eye movement range of the pupil position PP. The values ​​shown for the H-axis brightness distribution represent the proportion of useless light when the brightness of the image area IA seen from the center of the simulated image is set to 100%.

[0072] like Figure 12 As shown in region AR1 of the diagram, in the comparative example virtual image display device, a ghost image GH1 is formed on the upper side outside the image region IA, approximately half the vertical viewing angle away. The ghost image GH1 has a brightness of about 10% compared to the central image region IA.

[0073] like Figure 12 As shown in region AR2 of the figure, it can be seen that in the virtual image display device of the embodiment, the brightness of the reflective polarization element 45 formed in the region other than the outer periphery of the inclined surfaces 41d and 42d of the first prism 41 and the second prism 42 is reduced to 2.7% for the ghosting GH1.

[0074] An example of the structure and assembly of the first display section 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 bonded between the first prism 41 and the second prism 42 via an adhesive member AD. Thus, the first prism 41 and the second prism 42 are joined at inclined surfaces 41d and 42d, resulting in a prism light guide member 48 or a first flat plate member 40. Simultaneously, a component integrating a quarter-wave plate 51, a second lens 53 with a transmissive mirror 56, and an optical element 58 is prepared and bonded to the outer surfaces 41c and 42c of the first flat plate member 40. At this time, spacers 61, which are a pair of thin adhesives, are arranged between the outer surfaces 41c and 42c of the first flat plate member 40 and the quarter-wave plate 51, forming a gap SP between the outer surfaces 41c and 42c of the first flat plate member 40 and the quarter-wave plate 51.

[0075] The light-absorbing layer AL can be appropriately set during or after the assembly of the first display unit 20a.

[0076] The virtual image display device 100A, 100B or optical unit 100 of the first embodiment described above includes: a display element 11 that emits image light ML; a first prism 41 that allows the image light ML from the display element 11 to be incident upon; a second prism 42 that is joined with the first prism 41 to form a parallel plate-shaped prism light guide member 48; a slanted mirror portion IM that is disposed at the joint portion JS of the first prism 41 and the second prism 42, so that at least a portion of the image light ML guided in the first prism 41 is reflected; a second lens 53 having positive optical power that is disposed opposite to the first outer surface 41c of the first prism 41 into which the image light ML reflected by the slanted mirror portion IM is incident; and a transmissive mirror 56 that is formed on the outer side of the second lens 53, so that the image light ML reflected by the slanted mirror portion IM is partially reflected toward the slanted mirror portion IM, the slanted mirror portion IM being formed in a portion AA of the inclined surfaces 41d and 42d of the first prism 41 and the second prism 42, excluding the periphery. Specifically, the oblique mirror portion IM is formed correspondingly to a portion AA of the rectangular plane RP extending between the outer surfaces 41c and 42c and the opposing inner surfaces 41b and 42b along the central portion 48i of the oblique surfaces 41d and 42d of the first prism 41 and the second prism 42.

[0077] In the aforementioned virtual image display device, the oblique mirror portion IM is correspondingly formed with a portion AA of the rectangular plane RP extending between the outer surface and the opposing inner surface of the central portion 48i of the oblique surfaces of the first prism 41 and the second prism 42. Therefore, even if an unwanted component in the image light ML is incident on the upper part of the first prism 41, this unwanted light can be prevented from incident on the oblique mirror portion IM and deflected from the light path toward the eye. Thus, unwanted light that causes ghosting and degrades image quality can be reduced. Consequently, ghosting observed around the virtual image being observed can be suppressed.

[0078] [Second Implementation]

[0079] Hereinafter, the virtual image display device of the second embodiment will be described. Furthermore, the virtual image display device of the second embodiment is obtained by partially modifying the virtual image display device of the first embodiment; therefore, the parts common to the virtual image display device of the first embodiment will be omitted from the description.

[0080] Figure 13 This is a side sectional view illustrating the virtual image display device 100A according to the second embodiment. (See attached image.) Figure 13 As shown, the virtual image display device 100A of the second embodiment does not have the following characteristics: the first inclined surface 41d of the first prism 41 and the second inclined surface 42d of the second prism 42. Figure 2 The flat portion FL is shown in the figure.

[0081] [Variations and others]

[0082] The present invention has been described based on the above embodiments, but the present invention is not limited to the above embodiments. It can be implemented in various ways without departing from its spirit, for example, the following modifications can also be made.

[0083] As described above, HMD200 includes a first virtual image display device 100A and a second virtual image display device 100B. However, HMD200 may also be a structure in which a single first virtual image display device 100A or second display device 100B is supported in front of the eyes by a support device 100C.

[0084] The display element 11 can emit linearly polarized image light ML, or a polarizing filter can be provided after the display element 11. Thus, the image light ML of s-polarized light PLs can be incident on the reflective polarizing element 45.

[0085] The region AA forming the oblique mirror portion IM does not need to be the region where the outer end region Z1, the inner end region Z2, and the transverse end regions Z3 and Z4 are completely removed. For example, the oblique mirror portion IM can be formed in the region corresponding to the transverse end regions Z3 and Z4 and the inner end region Z2. Furthermore, in Figure 13 In the case of the structure shown, refer to Figure 5The oblique mirror portion IM can also be formed in a portion of region AA other than the inner end region Z2 and the transverse end regions Z3 and Z4.

[0086] The positioning structure AS is not limited to a structure consisting only of the flat portion FL; for example, it can also be a shape that includes steps capable of positioning. The flat portion FL can be provided separately from the inclined surfaces 41d and 42d. In this case, a connecting surface composed of planes or curved surfaces, or a step composed of multiple surfaces, can be provided between the flat portion FL and the inclined surfaces 41d and 42d. For example, the flat portion FL can also be provided in two or more parts in the transverse X direction.

[0087] In the cover component 52, the compensation plate 55 can be omitted. In this case, a quarter-wave plate 51 is arranged only within the range of the second lens 53, and the second lens 53 is covered by the compensation lens 54.

[0088] In the second flat plate component 50, the cover component 52 may also be omitted.

[0089] If the adhesive does not spread, the reflective polarizing element 45 can also be bonded to one side using an adhesive component AD such as OCA, and to the other side using an adhesive.

[0090] The first lens 30 is not necessary and can be omitted. Similarly, the incident optical surface 41a can be omitted from the first prism 41 of the first flat plate member 40. In this case, it becomes an optical system in which the lens section 44 is omitted.

[0091] The first lens 30 is not limited to being coupled to the first image forming element 11a, but can also be configured separately from the first image forming element 11a.

[0092] The second lens 53 is not limited to a plano-convex lens with positive optical power, and can be replaced with a diffraction lens, holographic lens, etc., with positive optical power. In this case, the compensation lens 54 can be, for example, a diffraction lens, holographic lens, liquid crystal lens, etc., with an inverted shape. At this time, the optical element such as the diffraction lens, holographic lens, liquid crystal lens, etc., which serves as the second lens 53, can itself have the function of partially reflecting the image light ML, but a planar transmissive mirror can also be placed on the outer side of the optical element.

[0093] The light-absorbing layer AL can also be omitted.

[0094] The gaps PN1 and PN2 formed between the first prism 41 and the second prism 42 can be filled with adhesive or left unfilled.

[0095] like Figure 14As shown, the first virtual image display device 100A may also have an s-polarized light transmission polarizing plate 12 disposed between the first lens 30 and the display element 11 in the first display unit 20a, for example. Furthermore, in the first display unit 20a, a third flat plate member 150 is added to the outer side of the second flat plate member 50. The third flat plate member 150 is an image light blocking member LP. The third flat plate member 150 includes a quarter-wave plate 151 disposed on the outer side of the outer side of the transmissive mirror 56 or the light-concentrating reflector CR, and a polarizing plate 59 disposed on the outer side of the outer quarter-wave plate 151. That is, in the first display unit 20a, the inner quarter-wave plate 51 and the outer quarter-wave plate 151 are disposed between the inner reflective polarizing element 45 and the outer polarizing plate 59. The polarizing plate 59 selectively absorbs the image light ML transmitted through the outer quarter-wave plate 151 according to the polarization direction.

[0096] The circularly polarized image light ML, which has passed through the transmissive mirror 56, becomes p-polarized light after passing through the outer quarter-wave plate 151 and is incident on the polarizing plate 59, where it is mostly blocked. That is, the image light ML is blocked by the third flat plate member 150 and does not leak to the outside. This prevents the image light ML from being observed from the outside, thus ensuring privacy. On the other hand, the external light OL, which is incident on the polarizing plate 59, becomes only s-polarized light after passing through the polarizing plate 59, becomes circularly polarized light after passing through the outer quarter-wave plate 151, and partially passes through the transmissive mirror 56. The external light OL, which has partially passed through the transmissive mirror 56, becomes p-polarized light after passing through the inner quarter-wave plate 51, passes through the reflective polarizing element 45, and is incident on the pupil position PP.

[0097] The virtual image display device in a specific embodiment includes: a display element that emits image light; a first prism that allows image light from the display element to enter; a second prism that is joined with the first prism to form a parallel plate-shaped prism light guide; an oblique mirror portion disposed at the joint of the first prism and the second prism, which reflects at least a portion of the image light guided in the first prism; a lens having positive optical power disposed facing the outer side of the first prism to which the image light reflected by the oblique mirror portion enters; and a transmissive mirror formed on the outer side of the lens, which partially reflects the image light reflected by the oblique mirror portion toward the oblique mirror portion, wherein the oblique mirror portion is formed correspondingly to a portion of the oblique surfaces of the first prism and the second prism, excluding the periphery.

[0098] In the aforementioned virtual image display device, the slanted mirror portion is formed corresponding to a portion of a rectangular plane extending between the outer and opposing inner surfaces of the central portion of the slanted surfaces of the first and second prisms. Therefore, even if unwanted components of the image light are incident on the upper part of the first prism, this unwanted light can be prevented from incident on the slanted mirror portion and deflected from the light path toward the eye, thus reducing unwanted light that causes ghosting and degrades image quality. As a result, ghosting observed around the virtual image being observed can be suppressed.

[0099] In the virtual image display device of a specific embodiment, a positioning structure is provided around the inclined surfaces of the first and second prisms, which positions the first and second prisms in the direction of inclination of the inclined surfaces. This allows for easy assembly of the first and second prisms.

[0100] In a specific virtual image display device, the oblique mirror portion is formed in the area of ​​a rectangular plane excluding the outer end region near the outer side. This suppresses ghosting caused by unwanted light reflected from the outer end region.

[0101] In a specific virtual image display device, the oblique mirror portion is formed in a rectangular plane, excluding the inner end region near the inner side. Since unwanted light reflected from the inner end region is more likely to be directed towards the pupil, forming the oblique mirror portion in a region other than the inner end region improves the suppression of ghosting.

[0102] In a specific virtual image display device, the oblique mirror portion is formed in a rectangular plane, excluding the outer end region near the outer side. The width of the outer end region in the oblique direction is wider than the width of the inner end region in the oblique direction. Since the image light in the usual optical path is more affected by the inner end region than the outer end region, by making the width of the outer end region in the oblique direction wider than the width of the inner end region in the oblique direction, it is easier to prevent the virtual image display from deteriorating.

[0103] In a specific virtual image display device, the first prism has a pair of lateral surfaces, which are arranged opposite each other between an outer surface and an opposing inner surface in a direction intersecting the arrangement directions of the first and second prisms. An oblique mirror portion is formed in a rectangular plane, excluding the region near the horizontal ends of the pair of lateral surfaces. This suppresses ghosting caused by unwanted light reflected in the horizontal end regions.

[0104] In a specific virtual image display device, a positioning structure is provided near the outer end region. This positioning structure positions the first and second prisms in the inclined direction of the slope. The outer end region is relatively easy to expand, making it easy to install the positioning structure.

[0105] In a specific virtual image display device, the positioning structure is a flat portion, which is located on the outer side of the joint between the first and second prisms and forms an obtuse angle with respect to the rectangular plane. Such a flat portion is easy to form and can improve the joint accuracy between the first and second prisms.

[0106] In a specific embodiment of the virtual image display device, a quarter-wave plate is further included. This quarter-wave plate is positioned between the outer surface of the first prism and the plane of the second lens. The oblique mirror portion has a polarization separation film that selectively reflects image light according to the polarization direction. In this case, the image light from the first prism is efficiently reflected by the polarization separation film. When reflected by the transmissive mirror, it oscillates back and forth on the quarter-wave plate, transmitting through the polarization separation film with minimal loss.

[0107] The optical unit in the specific embodiment includes: a display element that emits image light; a first prism that allows image light from the display element to enter; a second prism that is joined with the first prism to form a parallel plate-shaped prism light guide; an oblique mirror portion disposed at the joint of the first prism and the second prism, which reflects at least a portion of the image light guided in the first prism; a lens having positive optical power disposed facing the outer side of the first prism into which image light reflected by the oblique mirror portion enters; and a transmissive mirror formed on the outer side of the lens, which partially reflects the image light reflected by the oblique mirror portion toward the oblique mirror portion, wherein the oblique mirror portion is formed correspondingly to a portion of the oblique surfaces of the first prism and the second prism, excluding the periphery.

Claims

1. A virtual image display device, characterized in that, have: Display elements emit image light; A first prism is used to allow the image light from the display element to enter; The second prism, together with the first prism, forms a parallel flat plate-shaped prism light guide component. An oblique mirror portion is disposed at the junction of the first prism and the second prism, so that at least a portion of the image light guided in the first prism is reflected. A lens with positive optical power is disposed facing the outer side of the first prism into which the image light reflected from the oblique mirror portion is incident; and A transmissive mirror is formed on the outer side of the lens, causing the image light reflected by the oblique mirror portion to be partially reflected toward the oblique mirror portion. The oblique mirror portion is formed corresponding to a portion of the oblique surfaces of the first prism and the second prism, excluding the periphery.

2. The virtual image display device according to claim 1, characterized in that, The aforementioned region corresponds to a portion of a rectangular plane extending along the central portion of the slope between the outer and opposite inner surfaces.

3. The virtual image display device according to claim 1, characterized in that, A positioning structure is provided around the inclined surface of the first prism and the second prism, the positioning structure positioning the first prism and the second prism in the inclination direction of the inclined surface.

4. The virtual image display device according to claim 2, characterized in that, The oblique mirror portion is formed in the area of ​​the rectangular plane other than the outer end region near the outer side.

5. The virtual image display device according to claim 2, characterized in that, The oblique mirror portion is formed in the area of ​​the rectangular plane excluding the inner end region near the inner side.

6. The virtual image display device according to claim 5, characterized in that, The oblique mirror portion is formed in the area of ​​the rectangular plane excluding the outer end region near the outer side. The width of the outer end region in the tilt direction is wider than the width of the inner end region in the tilt direction.

7. The virtual image display device according to claim 2, characterized in that, The first prism has a pair of lateral surfaces, which are arranged opposite each other between the outer surface and the opposing inner surface in a direction that intersects the direction in which the first prism and the second prism are arranged. The oblique mirror portion is formed in the rectangular plane in the area excluding the horizontal end region near the pair of horizontal sides.

8. The virtual image display device according to claim 4, characterized in that, A positioning structure is provided near the outer end region, which positions the first prism and the second prism in the inclined direction of the slope.

9. The virtual image display device according to claim 8, characterized in that, The positioning structure is a flat portion, which is located on the outer side of the joint between the first prism and the second prism and forms an obtuse angle with respect to the rectangular plane.

10. The virtual image display device according to claim 1, characterized in that, The virtual image display device further includes a quarter-wave plate, which is disposed between the outer surface of the first prism and the plane of the lens. The oblique mirror portion has a polarization separation film, which selectively reflects the image light according to the polarization direction.

11. An optical unit, characterized in that, have: Display elements emit image light; A first prism is used to allow the image light from the display element to enter; The second prism, together with the first prism, forms a parallel flat plate-shaped prism light guide component. An oblique mirror portion is disposed at the junction of the first prism and the second prism, so that at least a portion of the image light guided in the first prism is reflected. A lens with positive optical power is disposed facing the outer side of the first prism into which the image light reflected from the oblique mirror portion is incident; and A transmissive mirror is formed on the outer side of the lens, causing the image light reflected by the oblique mirror portion to be partially reflected toward the oblique mirror portion. The oblique mirror portion is formed corresponding to a portion of the oblique surfaces of the first prism and the second prism, excluding the periphery.

Images