Virtual image display device and optical unit

Abstract

The invention provides a virtual image display device and an optical unit to prevent an overall optical system from becoming larger. The virtual image display device is a direct virtual image type virtual image display device, and is provided with: a display element; a first lens having a positive refractive power, on which image light from the display element is incident; a second lens having a positive refractive power to which the image light that has passed through the first lens is incident; a parallel plate-shaped prism light guide member that has a first prism and a second prism and guides the image light that has passed through the second lens; a planar polarization separation film which is provided at the joint of the first prism and the second prism and which selectively reflects the image light guided by the first prism in accordance with the polarization direction; a plano-convex third lens disposed so as to face the outer surface of the first prism; a transmissive mirror which is formed on the convex surface of the third lens and partially reflects the image light; and a 1 / 4 wavelength plate disposed between the outer surface and the plane of the third lens.

Description

Technical Field

[0001] The present invention relates to a see-through virtual image display device and an optical unit capable of observing a virtual image. Background Art

[0002] The following head-mounted display is publicly known: the head-mounted display has a display device, a projection optical component, a prism component and a focusing reflection surface, wherein image light from the projection optical component is incident on the first prism of the prism component and is totally reflected on the outer side surface, after being partially reflected by the semi-transmitting reflection surface formed at the boundary between the first prism and the second prism of the prism component, it passes through the outer side surface of the prism component and is reflected by the focusing reflection surface, returns to the prism component and passes through the semi-transmitting reflection surface, and further passes through the inner side surface opposite to the pupil (see patent document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-08749

[0004] In the head mounted display described above, an intermediate image is formed in the first prism, so the optical path length becomes longer and the optical system as a whole becomes larger. In addition, since the projection optical component is arranged in a direction inclined more toward the face than the upper side of the prism component, the projection optical component is arranged near the face and is prone to interference, which places restrictions on the arrangement and size of the projection optical component. Even if a relatively small optical system without forming an intermediate image can be realized by effectively using a focusing reflector, it is difficult to correct chromatic aberration only by the focusing reflector in such an optical system. Summary of the invention

[0005] A virtual image display device according to one aspect of the present invention is a direct virtual image type virtual image display device, which comprises: a display element that emits image light; a first lens having a positive refractive power, the image light from the display element being incident on the first lens; a second lens having a positive refractive power, the image light that has passed through the first lens being incident on the second lens; a parallel flat plate-shaped prism light-guiding component having a first prism and a second prism, which guides the image light that has passed through the second lens; a planar polarization separation film, which is disposed at a junction between the first prism and the second prism, and which selectively reflects the image light that has been guided in the first prism according to a polarization direction light; a plano-convex third lens having a plane, the plane being arranged opposite to the outer side surface of the first prism on which the image light reflected by the polarization separation film is incident; a transmissive reflector formed on the convex surface of the third lens, which partially reflects the image light reflected by the polarization separation film toward the polarization separation film; and a 1 / 4 wavelength plate for the image light, which is arranged between the outer side surface of the first prism and the plane of the third lens, the refractive index of the first prism being higher than the refractive index of the first lens and the third lens, so as to suppress chromatic aberration after combining the first lens, the second lens, the first prism and the third lens as a whole.

[0006] The optical unit of one aspect of the present invention is a direct virtual image type optical unit, which comprises: a first lens having positive refractive power, the image light from the display element emitting image light is incident on the first lens; a second lens having positive refractive power, the image light passing through the first lens is incident on the second lens; a parallel flat plate prism light guide component having a first prism and a second prism, which guides the image light passing through the second lens; a planar polarization separation film, which is arranged at the junction of the first prism and the second prism, and selectively reflects the image light guided in the first prism according to the polarization direction; a planar A plano-convex third lens, the plane being arranged opposite to the outer surface of the first prism on which the image light reflected by the polarization separation film is incident; a transmissive reflector formed on the convex surface of the third lens, which partially reflects the image light reflected by the polarization separation film toward the polarization separation film; and a 1 / 4 wavelength plate for the image light, which is arranged between the outer surface of the first prism and the plane of the third lens, the refractive index of the first prism being higher than those of the first lens and the third lens, so as to suppress chromatic aberration after combining the first lens, the second lens, the first prism and the third lens as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0008] Figure 2 It is a side cross-sectional view illustrating the internal structure of a single display device.

[0009] Figure 3 It is a perspective view for explaining the appearance structure of the first display unit.

[0010] Figure 4 It is a diagram for explaining the shapes of the first image forming element and the first lens, etc.

[0011] Figure 5 This is a perspective view for explaining an example of the structure and assembly of the first display unit.

[0012] Figure 6 This is a diagram for explaining chromatic aberration and suppression of chromatic aberration.

[0013] Figure 7 It is a side cross-sectional view for explaining the internal structure of the virtual image display device according to the second embodiment.

[0014] Figure 8 It is a side cross-sectional view for explaining the virtual image display device according to the third embodiment.

[0015] Fig. 9 Yes Description Figure 8 A conceptual diagram of the operation of the virtual image display device shown.

[0016] Fig.10 Yes Description Figure 8 A conceptual diagram of the operation of a modified example of the virtual image display device shown.

[0017] Description of symbols

[0018] 11: display element; 30: first lens; 30f: light incident surface; 30g: light exit surface; 31: parallel plate; 32: lens portion; 40: first flat plate-shaped member; 41: first prism; 41a: inclined surface; 41b: inner side surface; 41c: outer side surface; 41d: inclined surface; 410a: imaginary boundary surface; 42: second prism; 42b: inner side surface; 42c: outer side surface; 42d: Inclined surface; 44: second lens; 44a: incident optical surface; 44b: inclined surface; 440: lens portion; 440a: incident optical surface; 440b: imaginary boundary surface; 45: polarization separation film; 48: prism light guide component; 50: second flat plate component; 50c: inner side surface; 51: inner 1 / 4 wavelength plate; 151: outer 1 / 4 wavelength plate; 52: cover component; 53: third lens ; 53f: plane; 53g: convex surface; 54: compensation lens; 54f: concave surface; 54g: plane; 55: compensation plate; 56: transmissive reflector; 58: optical element; 59: polarizing plate; 61: spacer; 71: shell; 90: user terminal; 100: optical unit; 100A, 100B: virtual image display device; 100C: supporting device; 102a, 102b: display drive unit; 103a, 103b: combiner; AX: optical axis; B0~B3: wavelength component; CR: focusing reflection unit; CT: adhesive; EP: exit pupil; EY: eye; IF: image frame; IS: imaging optical system; LP: image light shielding unit; ML: image light; OL: external light; PP: pupil position; R0~R3: wavelength component; SP: gap; US: wearer. DETAILED DESCRIPTION

[0019] [First embodiment]

[0020] Below, refer to Figure 1 , Figure 2 etc., a first embodiment of the virtual image display device etc. of the present invention is described.

[0021] Figure 1 1 is a diagram for explaining a wearing state of a head mounted virtual image display device (hereinafter also referred to as a head mounted display or HMD) 200. The HMD 200 allows an observer or wearer US wearing the HMD 200 to recognize a video image as a virtual image. Figure 1 In the above, X, Y, and Z are orthogonal coordinate systems, the +X direction corresponds to the lateral direction in which the two eyes EY of the observer or wearer US wearing the HMD 200 are arranged, the +Y direction corresponds to the upward direction orthogonal to the lateral direction in which the two eyes EY of the wearer US are arranged, and the +Z direction corresponds to the front direction or the front direction of the wearer US. The ±Y directions are parallel to the vertical axis or the vertical direction.

[0022] The HMD 200 includes a first virtual image display device 100A of a direct virtual image type for the right eye, a second virtual image display device 100B of a direct virtual image type for the left eye, a pair of support devices 100C in the shape of temples that support these virtual image display devices 100A and 100B, and a user terminal 90 as an information terminal. The first virtual image display device 100A functions as an HMD alone, and is composed of a first display drive unit 102a arranged at the top and a first combiner 103a that covers the front of the eyes in the shape of a glasses lens. The second virtual image display device 100B also functions as an HMD alone, and is composed of a second display drive unit 102b arranged at the top and a second combiner 103b that covers the front of the eyes in the shape of a glasses lens. The support device 100C is a wearing component worn on the head of the wearer US, and supports the upper end sides of the pair of combiners 103a and 103b via the display drive units 102a and 102b that are integrated in appearance. The first virtual image display device 100A and the second virtual image display device 100B are optically identical or left-right inverted, and detailed description of the second virtual image display device 100B is omitted.

[0023] Figure 2 1 is a side cross-sectional view for explaining the internal structure of the first virtual image display device 100A. The first virtual image display device 100A includes a first image forming element 11a, a first display unit 20a, and a first circuit component 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, and 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-shaped member 40, and a second flat plate-shaped member 50. The first lens 30 has a function as a protective glass for protecting the display surface 11d of the display element 11. The first flat plate-shaped member 40 includes a second lens 44 that is opposite to the first lens 30, and guides the image light ML emitted from the display element 11 and incident from the second lens 44 to the third lens 53 of the second flat plate-shaped member 50. The second flat member 50 reflects the image light ML from the first flat member 40 toward the pupil position PP or the eye EY by returning part of the image light ML to the first flat member 40, and makes the external light incident on the pupil position PP via the first flat member 40. The first lens 30, the second lens 44, the first flat member 40, and the second flat member 50 each function as a lens having a positive refractive power.

[0024] 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 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, and the second circuit component 80b is the same as the first circuit component 80a.

[0025] In the first virtual image display device 100A, the first image forming element 11a is a self-luminous image light generating device. The first image forming element 11a emits the image light ML to the first flat plate-shaped member 40 via the first lens 30. The first image forming element 11a is accommodated and supported by the housing 71. The first image forming element 11a is, for example, an organic EL (Organic Electro-Luminescence) display, which forms a color static image or dynamic image on a two-dimensional display surface 11d. The first image forming element 11a is driven by the first circuit member 80a to perform a display operation. The first image forming element 11a is not limited to an organic EL display, and can be replaced by a display device using an inorganic EL, an organic LED, an LED array, a laser array, a quantum dot light-emitting element, etc. The first image forming element 11a is not limited to a self-luminous image light generating device, and can also be composed of other light modulating elements such as LCDs, and an image is formed by illuminating the light modulating 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), a digital micromirror device, etc. can also be used instead of LCD. In addition, in the first virtual image display device 100A, the optical device other than the first circuit component 80a is referred to as an optical unit 100. The optical unit 100 includes a direct virtual image type optical system, and can also be said to be a part equivalent to the direct virtual image optical system DIS constituting the first virtual image display device 100A.

[0026] The first display unit 20a includes a first lens 30, a first flat plate-shaped member 40, a polarization separation film 45, and a second flat plate-shaped member 50. In the first display unit 20a, the first lens 30 has a positive refractive power, and the image light ML from the first image forming element 11a is incident on the first lens 30. The first lens 30 has a planar light incident surface 30f joined to the first image forming element 11a and a convex light exit surface 30g. The light exit surface 30g is, for example, a spherical surface, but can be set as an aspherical surface having an axisymmetric shape. The first lens 30 can be considered as a parallel plate 31 and a lens portion 32. By ensuring that the thickness of the parallel plate 31 is greater than a predetermined thickness, foreign matter attached to the surface of the first lens 30 is less likely to become conspicuous. 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. The first lens 30 is made of, for example, fused silica, and has a relatively low refractive index. As an example, the refractive index of the first lens 30 is 1.49 or less. It is preferable that the first lens 30 is made of quartz having a refractive index of 1.46.

[0027] The first flat-plate-shaped component 40 has a second lens 44 which is a plano-convex lens, a first prism 41 which is a parallel flat-plate-shaped component, and a second prism 42 which is a parallel flat-plate-shaped component. The second lens 44 and the first prism 41 are joined by inclined surfaces 44b and 41a. The first prism 41 and the second prism 42 are joined by inclined surfaces 41d and 42d. The component formed by joining the second lens 44, the first prism 41, and the second prism 42 is called a prism light-guiding component 48. The prism light-guiding component 48 has the appearance of a parallel flat plate. A planar polarization separation film 45 is formed on the inclined surface 41d formed on the lower side of the first prism 41. The component formed by combining the prism light-guiding component 48 and the second flat-plate-shaped component 50 described later is equivalent to Figure 1 The first combiner 103a.

[0028] The second lens 44 is a plano-convex lens with a positive refractive index, and has an incident optical surface 44a opposite to the light exit surface 30g of the first lens 30 and an inclined surface 44b combined with the first prism 41. As an example, the refractive index of the second lens 44 is less than 1.49. Preferably, the second lens 44 is made of quartz with a refractive index of 1.46. The first prism 41 has a quadrangular prism-shaped appearance and a trapezoidal longitudinal section. The first prism 41 guides the image light ML, and has an inclined surface 41a, an inner side surface 41b, an outer side surface 41c, and an inclined surface 41d combined with the inclined surface 44b of the second lens 44. Here, the incident optical surface 44a is inclined downward in the front direction as a whole, and the optical axis passing through the incident optical surface 44a extends in the direction between the +Z direction as the front and the +Y direction as the top. Thus, it is easy to arrange the first image forming element 11a as the display element 11 at a position closer to the outside than the inner side surface 41b, and it is possible to adjust the angle of the image light ML propagating in the first prism 41 (in the first prism 41 or inside the first prism 41). The incident optical surface 44a is a convex surface, for example, a spherical surface, but can be set as an axisymmetric aspherical surface. The inner side surface 41b and the outer side surface 41c are parallel to each other and extend perpendicularly to the optical axis AX between the pupil position PP. The inner side surface 41b and the outer side surface 41c reflect the image light ML internally (i.e., reflect it on the inner side of the object surface), but it is particularly preferred to perform total reflection. The scratch resistance or abrasion resistance of the inner side surface 41b can be improved by applying a hard coating. The inclined surface 41d is a plane. With respect to the inclined surface 41d, an acute angle is formed relative to the outer side surface 41c, specifically, an angle of 25° to 32°. In addition, the interval between the optical axis AX passing through the pupil position PP and the upper end of the first lens 30 is about 20 mm. The first prism 41 is formed of, for example, an optical glass such as s-NBH51, and has a refractive index higher than that of the first lens 30 .

[0029] The number of times the image light ML is reflected in the first prism 41 is once on the inner side surface 41b, once on the outer side surface 41c, and further reflected once by the polarization separation film 45 described later. By setting the number of internal reflections of the image light ML in the first prism 41 to 2 times, the field angle of the image light ML, the pupil position PP or its opening PPa can be increased, and the mixing of lights having different reflection times in the first prism 41 can be avoided. The image light ML reflected by the inner side surface 41b and the outer side surface 41c does not form an intermediate image in the first display unit 20a or the imaging optical system IS, so the degree of divergence is suppressed compared to the initial divergence state emitted from the first image forming element 11a, but it is incident on the inner side surface 41b and the outer side surface 41c in a still divergent state, and the divergent state is maintained.

[0030] The second prism 42 has a quadrangular prism-shaped outer shape similarly to the first prism 41, and has a trapezoidal longitudinal section. The second prism 42 allows the image light ML to pass through, and has an inner side surface 42b, an outer side surface 42c, and an inclined surface 42d. Here, the inner side surface 42b and the outer side surface 42c are parallel to each other and extend perpendicularly to the optical axis AX between the pupil position PP. For the inner side surface 42b, by implementing a hard coating, it is possible to improve the scratch resistance or abrasion resistance. The second prism 42 is formed of an optical glass such as s-NBH51, for example, and has a refractive index equal to that of the first prism 41. As an example, the difference between the refractive index of the first lens 30 and the second lens 44 and the refractive index of the first prism 41 and the second prism 42 is greater than 0.17. As another example, the refractive index of the first prism 41 and the second prism 42 is greater than 1.67. Preferably, the first prism 41 and the second prism 42 are made of optical glass having a refractive index of 1.67.

[0031] The polarization separation film 45 is integrally formed on the inclined surface 41d of the first prism 41, and is sandwiched between the inclined surface 41d of the first prism 41 and the inclined surface 42d of the second prism 42. The space between the polarization separation film 45 and the inclined surface 42d is filled with an adhesive CT for bonding. The polarization separation film 45 is formed of a dielectric multilayer film, and when the image light ML includes s-polarized light s, the image light ML of s-polarized light s is efficiently reflected, and when the image light ML includes p-polarized light p, the image light ML of p-polarized light p is efficiently transmitted. The polarization separation film 45 only needs to selectively reflect the image light ML according to the polarization direction, for example, it can also be a wire grid type polarizer. The polarization separation film 45 only needs to be a flat surface to the extent that it does not affect the imaging. In addition, the polarization separation film 45 can also have a convex or concave micro-curved surface to the extent that it does not affect the imaging. In addition, a filler with transmittance can also be filled between the polarization separation film 45 and the inclined surface 41d instead of the adhesive CT. In this case, the first prism 41 and the second prism 42 may be supported from the outside by a supporting member or the like to maintain the joined state. In addition, the polarization separation film 45 may be formed integrally on the inclined surface 42d of the second prism 42 instead of being formed on the inclined surface 41d of the first prism 41. The polarization separation film 45 can improve scratch resistance or abrasion resistance by applying a hard coating on the surface.

[0032] When the reflection angle of the image light ML on the optical axis AX in the first prism 41 is β0, the inclination angle θ of the polarization separation film 45 is greater than 90°-β0. As a premise that the polarization separation film 45 does not hinder the path of the image light ML, when the maximum reflection angle of the image light ML is βmax, the inclination angle θ of the polarization separation film 45 is preferably less than βmax. The reflection angle β0 of the image light ML is equivalent to the angle formed by the normal line of the inner side surface 41b and the optical axis AX passing through the incident optical surface 44a, which is an acute angle. That is, the optical axis AX of the incident optical surface 44a extends in a direction less than 90° relative to the normal line of the inner side surface 41b.

[0033] The second flat member 50 includes a thin plate-shaped quarter-wave plate 51 and a cover member 52. The quarter-wave plate 51 is a crystal having an optical axis between the X direction and the Y direction, and converts the image light ML of the s-polarized light s reflected by the polarization separation film 45 into circularly polarized light c, and converts the image light ML of the circularly polarized light c reflected by the cover member 52 into p-polarized light p. The cover member 52 includes a plano-convex third lens 53, a concave-planar compensation lens 54, a compensation plate 55 provided around the compensation lens 54, and a transmissive reflector 56.

[0034] The second flat plate-shaped member 50 is arranged to be separated from the first flat plate-shaped member 40 by about 20 μm to 50 μm. The outer side surfaces 41c and 42c of the first flat plate-shaped member 40 and the inner side surface 50c of the second flat plate-shaped member 50 may be slightly curved, and a small step may be formed at the boundary between the outer side surfaces 41c and 42c. However, by making the interval between the outer side surfaces 41c and 42c and the inner side surface 50c 20 μm or more, more preferably 30 μm or more, it is possible to avoid these surfaces from being too close. On the contrary, by making the interval between the outer side surfaces 41c and 42c and the inner side surface 50c 50 μm or less, it is possible to avoid the thickness of the first combiner 103a formed by combining the first flat plate-shaped member 40 and the second flat plate-shaped member 50 to increase. A spacer 61 is provided between the outer side surfaces 41c, 42c of the first flat plate-shaped member 40 and the inner side surface 50c of the second flat plate-shaped member 50, and the spacer 61 is used to fix the first flat plate-shaped member 40 and the second flat plate-shaped member 50 in a state where the space between them is adjusted and they are positioned relative to each other. The spacer 61 is not provided over the entire circumference of the second flat plate-shaped member 50. That is, the gap SP between the first flat plate-shaped member 40 and the second flat plate-shaped member 50 is not sealed and communicates with the outside.

[0035] In the cover part 52, the third lens 53 is thin but has positive refractive power, and has a flat surface 53f joined to the 1 / 4 wavelength plate 51 and a convex surface 53g opposite to the compensation lens 54. The convex surface 53g is, for example, a spherical surface, but can be set as an axisymmetric aspherical surface. The compensation lens 54 is thin but has positive refractive power, and has a concave surface 54f and a flat surface 54g opposite to the third lens 53. The compensation plate 55 is a parallel plate and has a pair of flat surfaces 55f and 55g. Here, the concave surface 54f of the compensation lens 54 has the same shape as the convex surface 53g of the third lens 53. The flat surface 54g of the compensation lens 54 and the flat surface 55g of the compensation plate 55 are continuous on the same plane. The transmissive reflector 56 is a thin film formed on the convex surface 53g of the third lens 53, and has the same shape as the convex surface 53g. The component in which the third lens 53 and the transmissive reflector 56 are combined is called a focusing reflector CR.

[0036] The third lens 53, the compensation lens 54 and the compensation plate 55 are formed of a resin material and have the same refractive index. The refractive index of the third lens 53 and the like is lower than that of the first prism 41. As an example, the refractive index of the third lens 53 is 1.49. As another example, the difference between the refractive index of the third lens 53 and the refractive index of the first prism 41 is 0.17 or more. It is preferred that the third lens 53 is made of an acrylic resin such as PMMA having a refractive index of 1.49. The compensation lens 54 and the compensation plate 55 are an optical element 58 formed integrally of the same resin material. The combination of the third lens 53, the compensation lens 54 and the compensation plate 55 functions as a parallel plate as a whole. That is, the external light OL incident on the position of the compensation lens 54 and the compensation plate 55 passes through them without being affected by the lens effect of the compensation lens 54 and the like and the step existing at the outer edge of the compensation lens 54. The flat surfaces 54g and 55g of the compensation lens 54 and the compensation plate 55 may be coated with an anti-reflection film or a hard coating. The external light OL that has passed through the compensation plate 55 passes through the compensation lens 54 from the top, bottom, left, and right sides, and enters the compensation plate 55 from the peripheral area outside the incident area of ​​the image light ML corresponding to the compensation lens 54. Thus, a wide perspective field of view can be ensured with respect to the outside world. The field of view of the external light OL is set to, for example, about 40° upward and about 40° downward.

[0037] From the viewpoint of ensuring the viewing angle, the diameter of the third lens 53 is set to 20 mm to 25 mm. In addition, the thickness of the first flat member 40 or the prism light guide member 48 in the Z direction is 6 mm to 8 mm, and the distance from the inner side surfaces 41 b and 42 b of the first flat member 40 to the pupil position PP is about 12 mm to 13 mm. Therefore, the angle range of the image light ML incident on the pupil position PP, that is, the viewing angle (diagonal angle), can be set to about 40°.

[0038] The transmissive reflector 56 is a half mirror that partially reflects the image light ML that has passed through the third lens 53 and partially transmits the external light OL. The transmissive reflector 56 reflects the image light ML that has been reflected by the polarization separation film 45 of the first flat member 40 and has passed through the 1 / 4 wavelength plate 51 and the third lens 53 toward the pupil position PP. The transmissive reflector 56 is a concave mirror that covers the pupil position PP where the eye EY or the pupil is arranged 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 an eye point or an eye box, and corresponds to the exit pupil EP of the first display unit 20a.

[0039] The transmissive reflector 56 transmits a part of the external light OL, so that the external world can be observed in perspective, and the virtual image can be overlapped with the external image. At this time, the external light OL passes through the first flat member 40 and the second flat member 50, but the flat members 40 and 50 do not produce a lens effect on the external light OL. From the viewpoint of ensuring the brightness of the image light ML and facilitating the observation of the external image based on perspective, the reflectivity of the transmissive reflector 56 to the image light ML and the external light OL is greater than 10% and less than 50% within the assumed incident angle range of the image light ML. The transmissive reflector 56 is formed, for example, by a dielectric multilayer film, which is composed of a plurality of dielectric layers with adjusted film thickness. The transmissive reflector 56 can also be a single-layer film or a multilayer film of a metal such as Al or Ag with adjusted film thickness. The transmissive reflector 56 is formed, for example, by lamination using vapor deposition.

[0040] In the first virtual image display device 100A, the first lens 30, the second lens 44, the third lens 53 and the transmissive reflector 56 each have a positive refractive power and have a tendency to converge divergent light. The first lens 30, the second lens 44, the third lens 53 and the transmissive reflector 56, including the main 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 such as a single-type microscope type microscope that forms an erect image. As a result, it is possible to form a virtual image that projects the real image formed on the display surface 11d of the first image forming element 11a to, for example, infinity, or to form a virtual image that projects the real image formed on the display surface 11d to several meters in front. At this time, by adjusting the refractive power of the first lens 30, the second lens 44, the third lens 53 and the transmissive reflector 56, the focal length of the imaging optical system IS can be shortened to achieve a desired magnification. In the first virtual image display device 100A, it is preferable to appropriately set the refractive indexes of the first lens 30, the second lens 44, the first prism 41, and the third lens 53 based on the sizes and shapes of the first lens 30, the second lens 44, the first prism 41, the third lens 53, and the transmissive reflector 56 so as to suppress chromatic aberration as a whole after the combination of the first lens 30, the second lens 44, the first prism 41, and the third lens 53. More specifically, chromatic aberration is suppressed in the entire optical system in which a virtual image is formed by an optical path that passes through the first lens 30, passes through the second lens 44, is bent by the first prism 41, is reflected by the transmissive reflector 56, reciprocates in the 1 / 4 wavelength plate, reciprocates in the third lens 53, and passes through the first and second prisms.

[0041] Reference Figure 3, the longitudinal dimension ay of the first flat plate-shaped component 40 or the second flat plate-shaped component 50 is, for example, 34 mm, and the lateral dimension ax is, for example, 40 mm. The thickness az of the first flat plate-shaped component 40 in the front-to-back direction is, for example, about 7 mm, and the total thickness of the first flat plate-shaped component 40 and the second flat plate-shaped component 50 is suppressed to about 7.5 mm. In the first flat plate-shaped component 40, an upper plane 40u is provided on the left and right of the incident optical surface 44a. Light is not allowed to be incident on the upper plane 40u. On the upper plane 40u, from the viewpoint of preventing stray light, a light-shielding body (not shown) can be arranged to cover it opposite to it, or a light-shielding body can be applied. A light-shielding body or the like that covers it can also be provided on the horizontal plane 40v and the lower plane 40w. A light-shielding body or the like that covers it can also be provided around the second flat plate-shaped component 50.

[0042] Reference Figure 4 , the shapes of the first image forming element 11a and the first lens 30 are described. Figure 4 , region AR1 represents the state of observing the first lens 30 etc. from the front +Z side in an obliquely upward direction, region AR2 represents the state of observing the first lens 30 etc. from the bottom -Y side in an obliquely forward direction, and region AR3 represents the state of observing the first lens 30 etc. from the lateral +X side. The thickness or height H of the first lens 30 is, for example, about 2 mm, the width W of the first lens 30 is, for example, about 14 mm, and the depth D of the first lens 30 is, for example, about 7 mm.

[0043] The curvature radius of the convex light emitting surface 30g of the first lens 30 is, for example, 20 mm. In addition, the curvature radius of the incident optical surface 44a of the first prism 41 is, for example, 14 mm, and the curvature radius of the transmissive reflector 56 is, for example, 47 mm. The surfaces of the incident optical surface 44a of the first prism 41, the transmissive reflector 56, etc. are not limited to spherical surfaces, and may also be coaxial aspherical surfaces.

[0044] The optical path is described. The image light ML from the first image forming element 11a is incident on the first prism 41 via the first lens 30 and the second lens 44. At this time, the image light ML is suppressed from diverging due to the positive refractive power of the first lens 30 and the second lens 44. In the optical path through the first prism 41, the image light ML does not form an intermediate image, but is sequentially reflected by the inner side surface 41b of the first prism 41 and the outer side surface 41c of the first prism 41, and the s component in the image light ML is reflected by the polarization separation film 45. The image light ML of s-polarized light s reflected by the polarization separation film 45 passes through the outer side surface 41c of the first prism 41, passes through the 1 / 4 wavelength plate 51 of the second flat plate-shaped member 50, and becomes circularly polarized light c, which is incident on the transmissive reflector 56. The image light ML of the circularly polarized light c incident on the transmissive reflector 56 passes through the third lens 53 and is partially reflected by the transmissive reflector 56, and passes through the quarter wavelength plate 51 again in a state of being collimated by the third lens 53. Thus, the image light ML that has passed through the quarter wavelength plate 51 becomes p-polarized light p and is incident on the first prism 41 from the outer side surface 41c, passes through the polarization separation film 45, and is emitted to the outside of the second prism 42 via the inner side surface 42b. The image light ML emitted to the outside of the second prism 42 is incident on the pupil position PP where the eye EY or pupil of the wearer US is arranged. At the pupil position PP, not only the image light ML reflected by the transmissive reflector 56 but also the external light OL that has passed through the transmissive reflector 56 and the external light OL that has passed through the compensation plate 55 are incident. That is, the wearer US wearing the first virtual image display device 100A can observe the virtual image based on the image light ML in a superimposed manner with the external image.

[0045] Reference Figure 5 , an example of the structure and assembly of the first display unit 20a constituting the first virtual image display device 100A is described. Figure 5In the figure, regions BR1 to BR5 are stereoscopic diagrams for explaining the assembly process of the first display unit 20a. First, as shown in region BR1, prepare the first prism 41 and the second prism 42. The first prism 41 and the second prism 42 are formed of optical glass such as s-NBH51. The second lens 44 may also be pre-joined to the first prism 41. The first prism 41 is formed with an incident optical surface 44a, an inner side surface 41b, an outer side surface 41c, etc. of the second lens 44. The second prism 42 is formed with an inner side surface 42b, an outer side surface 42c, etc. On the inclined surface 41d of the first prism 41 on one side, a polarization separation film 45 is formed by vacuum evaporation or other methods. As shown in region BR2, the first prism 41 and the second prism 42 are joined at the inclined surfaces 41d and 42d to obtain the first flat plate-shaped component 40. Next, as shown in the area BR3, the quarter wavelength plate 51 is bonded to face the outer side surfaces 41c and 42c of the first flat plate-shaped member 40. At this time, a pair of thin adhesives, i.e., spacers 61, are arranged between the outer side surfaces 41c and 42c of the first flat plate-shaped member 40 and the quarter wavelength plate 51, and a gap is formed between the outer side surfaces 41c and 42c of the first flat plate-shaped member 40 and the quarter wavelength plate 51. As shown in the area BR4, the third lens 53 is bonded to an appropriate position on the surface of the quarter wavelength plate 51. A transmissive reflector 56 is formed on the surface of the third lens 53. Next, the optical element 58 is bonded to the quarter wavelength plate 51 and the like. At this time, the compensation lens 54 and the third lens 53 of the optical element 58 are positioned and fitted to be bonded to each other. In addition, the compensation plate 55 of the optical element 58 and the quarter wavelength plate 51 are bonded to each other. As described above, the assembly of the first display unit 20a is completed.

[0046] In the above description, the first display portion 20 a is manufactured by assembling the second flat member 50 on the first flat member 40 , but the first flat member 40 and the second flat member 50 may be assembled separately and then joined together.

[0047] The virtual image display device 100A, 100B or the optical unit 100 of the first embodiment described above is a direct virtual image type virtual image display device, which comprises: a display element 11, which emits image light ML; a first lens 30, which has a positive refractive power, and the image light ML from the display element 11 is incident on the first lens 30; a second lens 44 on which the image light ML that has passed through the first lens 30 is incident; a first prism 41 that is joined to the second lens 44 and on which the image light ML that has passed through the second lens 44 is incident; a second prism 42 that is joined to the first prism 41 to form a parallel flat plate-shaped prism light guide component 48; a planar polarization separation film 45, which is arranged at the junction of the first prism 41 and the second prism 42, and selectively reflects the light guided in the first prism 41 according to the polarization direction. image light ML; a plano-convex third lens 53 having a plane 53f arranged opposite to the outer side surface 41c of the first prism 41 on which the image light ML reflected by the polarization separation film 45 is incident; a transmissive reflector 56 formed on the convex surface 53g of the third lens 53 and reflecting part of the image light ML reflected by the polarization separation film 45 toward the polarization separation film 45; a quarter wavelength plate 51 for the image light ML, arranged between the outer side surface 41c of the first prism 41 and the plane 53f of the third lens 53; and a compensation lens 54 having a concave surface 54f and a plane 55g parallel to the outer side surface 41c of the first prism 41, the concave surface 54f having a shape that is the inversion of the convex surface 53g of the third lens 53 and being joined to the convex surface 53g via the transmissive reflector 56.

[0048] In the above-mentioned virtual image display device 100A, 100B or optical unit 100, in order to directly form a virtual image without forming an intermediate image, the refractive power is ensured by the first lens 30, the second lens 44, the third lens 53 and the transmissive reflector 56, and the refractive index of the first prism 41 and the second prism 42 is set to be relatively high, which can suppress the increase in the optical path length and ensure the magnification, thereby avoiding the enlargement of the optical system.

[0049] In addition, in the above-mentioned virtual image display device 100A, 100B or optical unit 100, chromatic aberration can be suppressed. Generally speaking, the refractive index of a substance that transmits and refracts light varies according to the wavelength of the light. Even for the same substance, its refractive index is higher for components with longer wavelengths such as red, and lower for components with shorter wavelengths such as blue. Therefore, when light containing multiple different wavelengths passes through a substance and refracts, the imaging position is different according to the wavelength component. Such a phenomenon is called dispersion, and the color deviation caused by dispersion in an image formed by a certain optical system is called the chromatic aberration of the optical system. As an example of an index for evaluating dispersion, there is an Abbe number. For the refractive index and Abbe number of each substance, there is a tendency that the Abbe number of a substance with a lower refractive index is higher and the Abbe number of a substance with a higher refractive index is lower. The Abbe number is defined based on the refractive index, so it varies according to the wavelength. Here, as an example, the refractive index and Abbe number of light with a wavelength of 587.56nm for the d line called Fraunhofer are used.

[0050] As an example, Figure 6 As shown in the region CR1, even in the central part of the image frame IF where the image light ML is observed, the red and other relatively long wavelength components R0 and the blue and other relatively short wavelength components B0 are observed at approximately the same place even when they reach the pupil position PP of the wearer US, and in the peripheral part away from the central part, the red and other relatively long wavelength components R1, R2, R3 and the blue and other relatively short wavelength components B1, B2, B3 may be observed offset. As a result, the image quality of the observed image light ML may be degraded.

[0051] As a method for suppressing such chromatic aberration, there is, for example, a method called achromatization. In achromatization, by combining and using a plurality of optical systems with different refractive indices for the same wavelength, chromatic aberration under at least two different wavelengths can be suppressed. In the present embodiment, when combining a plurality of optical elements, by appropriately setting a combination of the difference between the refractive index and the Abbe number and the difference between the refractive power, for example, chromatic aberration under at least two different wavelengths corresponding to red and blue can be reduced. In this way, in the present embodiment, by utilizing a combination of a plurality of different refractive indices, Abbe numbers and refractive powers between the first lens 30, the second lens 44, the third lens 53, the first prism 41 and the second prism 42, longitudinal and / or lateral chromatic aberration can be at least partially eliminated as a whole optical system.

[0052] More specifically, according to this embodiment, Figure 6As shown in the region CR2 of the image display device 100A, 100B or the optical unit 100, the refractive indexes of the first lens 30, the second lens 44, the first prism 41, the third lens 53 and the transmissive reflector 56 are appropriately set according to the respective sizes and shapes of the first lens 30, the second lens 44, the first prism 41, and the third lens 53, thereby being able to suppress chromatic aberration after the combination of the first lens 30, the second lens 44, the first prism 41, the polarization separation film 45, the third lens 53 and the transmissive reflector 56 as a whole. In this viewpoint, it is preferred that the refractive indexes of the first prism 41 and the second prism 42 are higher than the refractive indexes of the first lens 30, the second lens 44 and the third lens 53. In addition, it is preferred that the Abbe numbers of the first prism 41 and the second prism 42 are lower than the Abbe numbers of the first lens 30, the second lens 44 and the third lens 53. As an example, the Abbe numbers of the first lens 30 , the second lens 44 , and the third lens 53 may be 60 or more and 70 or less, and the Abbe numbers of the first prism 41 and the second prism 42 may be 18 or more and 28 or less.

[0053] [Second embodiment]

[0054] Hereinafter, a virtual image display device according to a second embodiment will be described. The virtual image display device according to the second embodiment is a partially modified version of the virtual image display device according to the first embodiment, and description of the same parts as those of the virtual image display device according to the first embodiment will be omitted.

[0055] Figure 7 The first virtual image display device 100A shown is a device that Figure 2 In the first virtual image display device 100A shown, the bonded first prism 41 and the second lens 44 are replaced with a first prism 410 integrated with a lens unit 440 , and the materials of the first prism 410 and the second prism 42 are changed to plastic. Figure 7 The first prism 410 except the lens portion 440 has the same Figure 2 The first prism 41 has the same shape. Figure 7 The lens portion 440 has Figure 2 The lens portion 440 has the same shape as the second lens 44, but the refractive index and Abbe number of the lens portion 440 are equal to the refractive index and Abbe number of the first prism 410, respectively. Figure 7 The incident optical surface 440a of the lens portion 440 is Figure 2 The second lens 44 corresponds to the incident optical surface 44 a included in the second lens 44 , and faces the first lens 30 . Figure 2 The second lens 44 has an inclined surface 44b and Figure 2 The inclined surfaces 41a of the first prism 41 correspond to Figure 7The imaginary boundary surfaces 440 b and 410 a between the lens portion 440 in the first prism 410 and the portion other than the lens portion 440 .

[0056] In the virtual image display device of the second embodiment, by forming the first prism 410 and the second prism 42 integrated with the lens unit 440 from plastic, it is possible to improve safety related to breakage, etc., and reduce weight and price compared to the case where they are formed from optical glass. On this basis, by selecting plastic having an appropriate refractive index and Abbe number as the material of the first prism 410 and the second prism 42, it is possible to suppress chromatic aberration after the combination of the first lens 30, the second lens 44, the first prism 41, the polarization separation film 45, the third lens 53, and the transmissive reflector 56 as a whole. As an example, the material of the first prism 410 and the second prism 42 can be plastic such as EP9000 with a refractive index of 1.67 and an Abbe number of 19.

[0057] [Third embodiment]

[0058] Hereinafter, a virtual image display device according to a third embodiment will be described. The virtual image display device according to the third embodiment is obtained by partially modifying the virtual image display device according to the first embodiment, and description of the same parts as those of the virtual image display device according to the first embodiment will be omitted.

[0059] exist Figure 8 In the case of the first virtual image display device 100A shown, in the first display unit 20a, for example, an s-polarized light transmitting polarizing plate 12 is arranged between the first lens 30 and the first image forming element 11a. However, the s-polarized light transmitting polarizing plate 12 is not functionally essential. In addition, in the first display unit 20a, a third flat plate-shaped member 150 is added to the outer side of the second flat plate-shaped member 50. The third flat plate-shaped member 150 is an image light shielding portion LP, and includes an outer 1 / 4 wavelength plate 151 provided on the outer side of the light collecting and reflecting portion, and a polarizing plate 59 provided on the outer side of the outer 1 / 4 wavelength plate 151 and selectively absorbing the image light ML transmitted through the outer 1 / 4 wavelength plate 151 according to the polarization direction. That is, in the first display unit 20a, the inner 1 / 4 wavelength plate 51 and the outer 1 / 4 wavelength plate 151 are arranged between the inner polarization separation film 45 and the outer polarizing plate 59.

[0060] Reference Fig. 9 , from the first image forming element 11a (refer to Figure 8) contains only s-polarized light s. The s-polarized light s incident on the polarization separation film 45 is reflected by the polarization separation film 45 without waste, passes through the inner 1 / 4 wavelength plate 51 to become circularly polarized light c, and is incident on the transmissive reflector 56. The circularly polarized light c incident on the transmissive reflector 56 is partially reflected by the transmissive reflector 56, and passes through the inner 1 / 4 wavelength plate 51 again in the reverse direction. The image light ML that passes through the inner 1 / 4 wavelength plate 51 in the reverse direction becomes p-polarized light p and passes through the polarization separation film 45, and is incident on the pupil position PP (refer to Figure 8 ). On the other hand, the image light ML of the circularly polarized light c that has passed through the transmissive reflector 56 becomes the p-polarized light p through the outer 1 / 4 wavelength plate 151, and is incident on the polarizing plate 59, and is almost blocked by the polarizing plate 59. That is, the image light ML is blocked by the third flat plate-shaped member 150 and does not leak to the outside. That is, it is possible to prevent the image light ML from being observed from the outside, so that privacy can be ensured.

[0061] On the other hand, the external light OL incident on the polarizing plate 59 passes through the polarizing plate 59 to become only s-polarized light s, passes through the outer 1 / 4 wavelength plate 151 to become circularly polarized light c, and partially passes through the transmissive reflector 56. The external light OL of the circularly polarized light c that has partially passed through the transmissive reflector 56 passes through the inner 1 / 4 wavelength plate 51 to become p-polarized light p, passes through the polarization separation film 45, and is incident on the pupil position PP (refer to Figure 8 ).

[0062] Fig.10 Yes Description Figure 8 and Fig. 9 FIG. 1 is a diagram showing a modified example of the first virtual image display device 100A. In this case, it is assumed that Figure 8 The polarizing plate 59 of the third flat-plate member 150 shown transmits the s-polarized light s and reflects the p-polarized light p.

[0063] To Fig. 9The difference between the two is described below. The image light ML of circularly polarized light c partially transmitted through the transmissive reflector 56 passes through the outer 1 / 4 wavelength plate 151 to become p-polarized light p, and is mostly reflected by the polarizing plate 59 without leaking out of the polarizing plate 59. In addition, the image light ML of p-polarized light p reflected by the polarizing plate 59 passes through the outer 1 / 4 wavelength plate 151 again in the reverse direction. The image light ML of p-polarized light p that passes through the outer 1 / 4 wavelength plate 51 becomes circularly polarized light c and is partially reflected by the transmissive reflector 56, but does not pass through the polarizing plate 59. The image light ML of circularly polarized light c that partially transmits the transmissive reflector 56 passes through the inner 1 / 4 wavelength plate 51 again in the reverse direction. The image light ML that passes through the inner 1 / 4 wavelength plate 51 becomes s-polarized light s and is reflected by the polarization separation film 45, and returns to the direction of the first image forming element 11a.

[0064] On the other hand, the external light OL incident on the polarizing plate 59 passes through the polarizing plate 59 to become only s-polarized light s, passes through the outer 1 / 4 wavelength plate 151 to become circularly polarized light c, and partially passes through the transmissive reflector 56. The external light OL of the circularly polarized light c that has partially passed through the transmissive reflector 56 passes through the inner 1 / 4 wavelength plate 51 to become p-polarized light p, passes through the polarization separation film 45, and is incident on the pupil position PP (refer to Figure 8 ). In addition, the p-polarized light p in the external light OL is reflected by the polarizing plate 59, but this does not cause any particular problem, and can prevent the surface of the first display portion 20a from being too dark.

[0065] 〔Variations and others〕

[0066] The present invention has been described based on the above embodiments, but the present invention is not limited to the above embodiments, and can be implemented in various forms within the scope not departing from the gist of the present invention. For example, the following modifications are also possible.

[0067] In the above, the HMD 200 includes the first virtual image display device 100A and the second virtual image display device 100B. However, the HMD 200 may support a single first virtual image display device 100A or a single second virtual image display device 100B in front of the eyes via the support device 100C.

[0068] The compensating plate 55 can be omitted from the cover member 52 . In this case, the quarter-wave plate 51 is disposed only within the range of the third lens 53 , and the third lens 53 is covered with the compensating lens 54 .

[0069] The first lens 30 is not limited to being bonded to the first image forming element 11 a , and may be disposed separately from the first image forming element 11 a .

[0070] The first image forming element 11 a may be a scanning type display device including a laser light source and a scanning mirror.

[0071] The virtual image display device in the specific embodiment is a direct virtual image type virtual image display device, which comprises: a display element, which emits image light; a first lens, which has a positive refractive power, and the image light from the display element is incident on the first lens; a second lens, which has a positive refractive power, and the image light passing through the first lens is incident on the second lens; a parallel flat plate prism light guide component, which has a first prism and a second prism, and guides the image light passing through the second lens; a planar polarization separation film, which is arranged on the first prism The first prism is a first prism having a first prism and a second prism having a second prism, wherein the first prism is a first prism and a second prism is a second prism. The first prism is a second prism and a second prism is a second prism. The first prism is a second prism and a second prism is a second prism. The first prism is a second prism and a second prism is a second prism. The first prism is a second prism and a second prism is a second prism. The first prism is a second prism and a second prism is a second prism. The first prism is a second prism and a second prism is a second prism. The first prism is a second prism and a second prism is a second prism. The second prism is a second prism and a second prism is a second prism. The first prism is a second prism and a second prism is a second prism. The second prism is a second prism and a second prism is a second prism. The first prism is a second prism and a second prism. The second prism is a second prism and ... second prism is a second prism and a second prism. The second prism is a second prism and a second prism. The second prism is a second prism and a second prism. The second prism is a second prism and a second prism.

[0072] In the above virtual image display device, in order to form a virtual image directly without forming an intermediate image, the refractive power is ensured by the first lens, the second lens and the transmissive reflector, so that the increase in optical path length can be suppressed and the magnification can be ensured, thereby avoiding the enlargement of the optical system. In the above virtual image display device, chromatic aberration can also be suppressed by combining the first prism with a high refractive index with the first lens and the third lens with a low refractive index.

[0073] In a specific embodiment of the virtual image display device, the Abbe number of the first prism is lower than the Abbe numbers of the first lens and the third lens. In the virtual image display device, chromatic aberration can be suppressed by combining the first prism with the first lens and the third lens having different Abbe numbers.

[0074] In a specific embodiment of the virtual image display device, the difference between the refractive index of the first prism and the second prism and the refractive index of the first lens is greater than 0.17, and the difference between the refractive index of the first prism and the second prism and the refractive index of the third lens is greater than 0.17.

[0075] In a specific embodiment of the virtual image display device, the refractive index of the first lens is 1.49 or less, the refractive indexes of the first prism and the second prism are 1.67 or more, and the refractive index of the third lens is 1.49 or less.

[0076] In a specific form of the virtual image display device, the first lens and the second lens are composed of quartz with a refractive index of 1.46, the first prism and the second prism are composed of optical glass with a refractive index of 1.67, the third lens is composed of acrylic resin with a refractive index of 1.49, and the second lens is bonded to the first prism.

[0077] In a specific embodiment of the virtual image display device, the first lens is composed of quartz with a refractive index of 1.46, the second lens, the first prism and the second prism are composed of plastic with a refractive index of 1.67, the third lens is composed of acrylic resin with a refractive index of 1.49, and the second lens is integrated with the first prism.

[0078] In a specific embodiment of a virtual image display device, the first lens, the prism light guide component, the polarization separation film, the second lens, the transmissive reflector, and the 1 / 4 wavelength plate constitute a single-microscope type imaging optical system that forms an erect image, and the first prism diverges the image light and performs two internal reflections. In this case, it is easy to shorten the distance from the display element to the transmissive reflector, and the prism light guide component can be miniaturized, and the display element and the first lens can also be miniaturized.

[0079] In a specific embodiment of the virtual image display device, the quarter-wave plate for the image light is disposed apart from the outer side surface of the first prism. In this case, it is easy to ensure that the image light is reflected inside the outer side surface of the first prism.

[0080] In a specific embodiment of the virtual image display device, the distance between the quarter-wave plate for image light and the outer side surface of the first prism is 20 μm to 50 μm.

[0081] In a specific embodiment of the virtual image display device, the first lens has a planar light incident surface bonded to the display element and a convex light exit surface. In this case, the first lens can function as a protective glass, and by ensuring that the thickness of the first lens is greater than a predetermined thickness, foreign matter attached to the surface of the first lens, i.e., the convex surface, is less likely to become conspicuous.

[0082] In a virtual image display device of a specific embodiment, the polarization separation film reflects s-polarized image light and transmits image light that is reflected by a transmissive mirror and returns through a quarter-wave plate to become p-polarized light.

[0083] The optical unit in a specific embodiment is a direct virtual image type optical unit, which comprises: a first lens having positive refractive power, onto which image light from a display element emitting image light is incident; a second lens having positive refractive power, onto which image light having passed through the first lens is incident; a parallel flat plate-shaped prism light-guiding component having a first prism and a second prism, for guiding image light having passed through the second lens; a planar polarization separation film, which is disposed at a junction between the first prism and the second prism, for selectively reflecting image light guided in the first prism according to a polarization direction; a planar plano-convex third lens, the plane being arranged opposite to the outer side surface of the first prism onto which image light reflected by the polarization separation film is incident; a transmissive reflector, which is formed on the convex surface of the third lens, for partially reflecting image light reflected by the polarization separation film toward the polarization separation film; and a quarter wavelength plate for image light, which is arranged between the outer side surface of the first prism and the plane of the third lens. The refractive index of the first prism is higher than the refractive indexes of the first lens and the third lens. The optical unit as a whole suppresses chromatic aberration in a combination of the first lens, the second lens, the first prism, and the third lens.

Claims

1. A direct virtual image type virtual image display device, comprising: A display element that emits image light; a first lens having a positive refractive power, the image light from the display element being incident on the first lens; a second lens having positive refractive power, and the image light passing through the first lens is incident on the second lens; a parallel flat plate-shaped prism light guide component having a first prism and a second prism, and guiding the image light having passed through the second lens; A planar polarization separation film, which is disposed at a junction between the first prism and the second prism, and selectively reflects the image light guided in the first prism according to a polarization direction; a plano-convex third lens having a flat surface, the flat surface being arranged opposite to the outer surface of the first prism on which the image light reflected by the polarization separation film is incident; a transmissive reflector formed on a convex surface of the third lens and reflecting part of the image light reflected by the polarization separation film toward the polarization separation film; and The 1 / 4 wavelength plate for the image light is arranged between the outer side surface of the first prism and the plane of the third lens, The refractive index of the first prism is higher than the refractive index of the first lens and the third lens, The virtual image display device suppresses chromatic aberration resulting from the combination of the first lens, the second lens, the first prism, and the third lens as a whole.

2. The virtual image display device according to claim 1, wherein: The Abbe number of the first prism is lower than the Abbe numbers of the first lens and the third lens.

3. The virtual image display device according to claim 1, wherein: The difference between the refractive index of the first prism and the second prism and the refractive index of the first lens is greater than 0.

17. The difference between the refractive index of the first prism and the second prism and the refractive index of the third lens is greater than 0.

17.

4. The virtual image display device according to claim 1, wherein: The refractive index of the first lens is less than 1.49, The refractive index of the first prism and the second prism is greater than 1.67, The refractive index of the third lens is 1.49 or less.

5. The virtual image display device according to claim 1, wherein: The first lens and the second lens are made of quartz with a refractive index of 1.

46. The first prism and the second prism are made of optical glass with a refractive index of 1.

67. The third lens is made of acrylic resin with a refractive index of 1.

49. The second lens is cemented to the first prism.

6. The virtual image display device according to claim 1, wherein: The first lens is made of quartz with a refractive index of 1.

46. The second lens, the first prism and the second prism are made of plastic with a refractive index of 1.

67. The third lens is made of acrylic resin with a refractive index of 1.

49. The second lens and the first prism are integrated.

7. The virtual image display device according to claim 1, wherein: The first lens, the prism light guide member, the polarization separation film, the third lens, the transmissive reflector, and the quarter-wave plate constitute a single-microscope type imaging optical system that forms an erect image. The first prism diverges the image light and causes it to be internally reflected twice.

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

9. The virtual image display device according to claim 8, wherein: The distance between the quarter-wave plate for image light and the outer side surface of the first prism is 20 μm to 50 μm.

10. The virtual image display device according to claim 1, wherein: The first lens has a planar light incident surface and a convex light emitting surface, and the planar light incident surface is bonded to the display element.

11. The virtual image display device according to claim 1, wherein: The polarization separation film reflects the image light of s-polarized light, and transmits the image light that is reflected by the transmissive reflector and returns through the quarter-wave plate to become p-polarized light.

12. A direct virtual image optical unit comprising: a first lens having positive refractive power, the image light from the display element emitting the image light being incident on the first lens; a second lens having positive refractive power, and the image light passing through the first lens is incident on the second lens; a parallel flat plate-shaped prism light guide component having a first prism and a second prism, and guiding the image light having passed through the second lens; A planar polarization separation film, which is disposed at a junction between the first prism and the second prism, and selectively reflects the image light guided in the first prism according to a polarization direction; a plano-convex third lens having a flat surface, the flat surface being arranged opposite to the outer surface of the first prism on which the image light reflected by the polarization separation film is incident; a transmissive reflector formed on a convex surface of the third lens and reflecting part of the image light reflected by the polarization separation film toward the polarization separation film; and The 1 / 4 wavelength plate for the image light is arranged between the outer side surface of the first prism and the plane of the third lens, The refractive index of the first prism is higher than the refractive index of the first lens and the third lens, The optical unit as a whole suppresses chromatic aberration resulting from a combination of the first lens, the second lens, the first prism, and the third lens.

Images