Virtual image display device and optical unit

Abstract

A virtual image display device and an optical unit are provided. The present invention improves birefringence characteristics of a wavelength plate assembled in an optical system. This virtual image display device is provided with: a display that emits circularly polarized image light; and an optical member that forms a virtual image by folding back the image light twice by reflection, the optical member having: a lens member; a transmission-type reflective optical element provided so as to face a first optical surface of the lens member, said first optical surface being close to the display; a reflection-type polarization optical element that is provided so as to face a second optical surface of the lens member away from the display, and that reflects the first polarized light, i.e., image light of linearly polarized light in the first polarization direction; and a wavelength plate that is provided between the reflective optical element and the polarizing optical element, is formed of a photocrosslinkable polymer liquid crystal material, and converts the image light that has passed through the reflective optical element into first polarized light, i.e., linearly polarized light in a first polarization direction, and converts the image light that has been reflected back and forth by the reflective optical element into second linearly polarized light in a second polarization direction.

Description

Technical Field

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

[0002] As a virtual image display device, the following virtual image display device is known, which includes: an image element that displays an image; a first optical part that is arranged at a position where image light is taken out; a second optical part that is arranged at a position closer to the image element than the first optical part; a Fresnel-type half-mirror that is formed at a junction between the first optical part and the second optical part; and a transmission / reflection selection component that is arranged on the light emitting side of the first optical part and selectively transmits or reflects light according to the polarization state of the light (Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-24246

[0004] In the device of Patent Document 1, a Fresnel-type half mirror is incorporated between the first optical section and the second optical section. This complicates the surface shape of the optical section and may degrade imaging when light is reflected or passes through the half mirror.

[0005] Furthermore, the device described in Patent Document 1 utilizes a flat plate with a built-in Fresnel lens as its imaging system, but it is also possible to use a meniscus lens in place of the flat plate. However, if a meniscus lens is used instead of a flat plate, the quarter-wave plate that constitutes the transmissive / reflective selective element is formed on a curved surface. This curvature changes the birefringence characteristics of the quarter-wave plate, potentially preventing the desired phase difference effect. Furthermore, attaching the quarter-wave plate to the surface may affect the birefringence characteristics. Summary of the Invention

[0006] A virtual image display device according to one aspect of the present invention comprises: a display that emits circularly polarized image light; and an optical component that forms a virtual image by reflecting the image light back twice, the optical component comprising: a lens component; a transmissive reflective optical element that is arranged opposite to a first optical surface of the lens component that is close to the display; a reflective polarization optical element that is arranged opposite to a second optical surface of the lens component that is away from the display and reflects the image light as linearly polarized light in a first polarization direction; and a wavelength plate that is arranged between the reflective optical element and the polarization optical element and is formed of a liquid crystal material, so that the image light that has passed through the reflective optical element becomes linearly polarized light in the first polarization direction, and the image light that has been reflected and reciprocated by the reflective optical element becomes linearly polarized light in a second polarization direction. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0008] Figure 2 It is a side view illustrating the optical structure of the display optical system.

[0009] Figure 3 It is a diagram for explaining the production of the first wave plate and the second wave plate.

[0010] Figure 4 This is a conceptual diagram illustrating the optical operation of the virtual image display device according to the first embodiment.

[0011] Figure 5 It is a diagram for explaining a virtual image display device according to a second embodiment.

[0012] Figure 6 This is a conceptual diagram illustrating the optical operation of the virtual image display device according to the second embodiment.

[0013] Figure 7 It is a diagram for explaining a virtual image display device according to a third embodiment.

[0014] Figure 8 It is a diagram for explaining a virtual image display device according to a fourth embodiment.

[0015] Figure 9 This is a conceptual diagram illustrating the optical operation of the virtual image display device according to the fourth embodiment.

[0016] Figure 10 It is a diagram for explaining a virtual image display device according to a fifth embodiment.

[0017] Figure 11 It is a diagram for explaining a virtual image display device according to a sixth embodiment.

[0018] Description of labels

[0019] 10 display; 11 image display panel; 11c glass cover; 11d display surface; 14 linear polarizing plate; 15 1 / 4 wavelength plate; 20 optical component; 21 lens component; 21A, 21B lens component; 21a, 21b optical surface; 21c, 21d optical surface; 22 reflective optical element; 25 polarization optical element; 80 circuit component; 90 user terminal; 100 optical unit; 100A, 100B virtual image display device; 100C temple; 102 drive device; 102a, 102b display drive unit; 103a, 103b display optical system; 121, 221 lens; 124, 224 wavelength plate; 200 head mounted display device (HMD); AX optical axis; C1 right-handed circularly polarized light; C2 left-handed circularly polarized light; EY eye; HM transmissive reflector; LL1, LL2 liquid crystal material; ML image light; PC1, PC2, PC3 polarization control components; PP pupil position; US wearer. DETAILED DESCRIPTION

[0020] [First embodiment]

[0021] Below, refer to Figures 1 to 3 A virtual image display device and the like according to a first embodiment of the present invention will be described.

[0022] Figure 1 1 is a perspective view illustrating a wearing state of a head-mounted display, namely, a head-mounted display device 200. The head-mounted display device (hereinafter also referred to as HMD) 200 allows an observer or wearer US wearing the head-mounted display device to recognize 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 eyes EY of the observer or wearer US wearing the HMD 200 are aligned. The +Y direction corresponds to the upward direction orthogonal to the lateral direction in which the eyes EY of the wearer US are aligned. The +Z direction corresponds to the front direction or the frontal direction of the wearer US. The ±Y directions are parallel to the vertical axis or the vertical direction.

[0023] HMD 200 includes a first virtual image display device 100A for the right eye, a second virtual image display device 100B for the left eye, a pair of temples 100C supporting the virtual image display devices 100A and 100B, and a user terminal 90 serving as an information terminal. The first virtual image display device 100A comprises a first display driver 102a disposed at the top and a first display optical system 103a covering the front of the eye. The second virtual image display device 100B comprises a second display driver 102b disposed at the top and a second display optical system 103b covering the front of the eye. The HMD 200, which combines the first and second virtual image display devices 100A and 100B, is also a virtual image display device in a broad sense. The pair of temples 100C supports the upper ends of the pair of display optical systems 103a and 103b via the display driver 102a and 102b, which appear to be integrated in appearance. A combination of the pair of display driving units 102 a and 102 b is referred to as a driving device 102 .

[0024] Figure 2 This is a conceptual side view illustrating the structure of the first display optical system 103a. The first display optical system 103a includes: a display 10 that emits circularly polarized image light ML; an optical component 20 that reflects the image light ML twice to form a virtual image; and a circuit component 80 that controls the operation of the display 10 and other components.

[0025] In the first virtual image display apparatus 100A, the optical device (specifically, the display 10 and the optical component 20 ) excluding the circuit component 80 is referred to as an optical unit 100 .

[0026] Although detailed description is omitted, the second display optical system 103b is optically identical to the first display optical system 103a, or is obtained by left-right inverting the first display optical system 103a. Below, the first display optical system 103a is described, and the description of the second display optical system 103b is omitted.

[0027] In the case of the display optical systems 103a and 103b shown in the figure, the FOV reaches 120°, and the thickness of the rear end emission surface from the display 10 to the outer edge of the optical component 20 is 13 mm.

[0028] In the first display optical system 103 a , the display 10 includes an image display panel 11 as a self-luminous image light generating device, and a polarization control member PC1 that converts the image light ML emitted from the image display panel 11 into circularly polarized light.

[0029] The image display panel 11 is, for example, an organic EL (Organic Electro-Luminescence) display, which forms a monochrome or color still image or moving image on a two-dimensional display surface 11d. Image light ML emitted from the image display panel 11 includes randomly polarized light. The image display panel 11 is driven by the circuit component 80 to perform display operations. The image display panel 11 is not limited to an organic EL display and can be replaced with a display device using an inorganic EL, organic LED, LED array, laser array, quantum dot light-emitting element, or the like.

[0030] The image display panel 11 is not limited to a self-luminous image light generating device, but may be formed of other light modulating elements such as an LCD, and an image is formed by illuminating the light modulating element with a light source such as a backlight.

[0031] The polarization control component PC1 includes a linear polarization plate 14 and a quarter-wave plate 15 in this order from the image display panel 11 side.

[0032] The linear polarizing plate 14 is, for example, an absorption-type polarizing plate. In this embodiment, it selectively transmits only the second linearly polarized light (horizontally polarized light) in the horizontal X direction. Specifically, only the linearly polarized light in the X direction of the image light ML emitted from the image display panel 11 passes through the linear polarizing plate 14 and enters the quarter-wave plate 15. The linear polarizing plate 14 is in the form of a sheet and is manufactured by stretching a film made by impregnating polyvinyl alcohol (PVA) with a dichroic dye such as iodine in a specific direction.

[0033] The main axis or fast axis of the quarter-wave plate 15 is set between the vertical and horizontal directions, that is, between the Y and X directions, and converts the second linearly polarized light (horizontally polarized light) that has passed through the linear polarization plate 14 into, for example, right-handed circularly polarized light C1. The quarter-wave plate 15 is formed of a liquid crystal material such as a photo-crosslinkable polymer liquid crystal material, but a birefringent crystal material such as quartz can also be processed into a thin plate. As a specific manufacturing method, a linear polarization plate 14 is set on the glass cover 11c of the image display panel 11, and a quarter-wave plate 15 composed of a UV-curable photo-crosslinkable polymer liquid crystal material is set thereon. The photo-crosslinkable polymer liquid crystal material is applied to the glass cover 11c while controlling the film thickness by spin coating, inkjet coating, etc., and then irradiated with polarized ultraviolet light and then baked, thereby functioning as the quarter-wave plate 15.

[0034] The optical member 20 includes a polarization control member PC2 , a lens member 21 , and a polarization control member PC3 in this order from the image display panel 11 side.

[0035] The imaging optical component 20 comprises only one lens, resulting in an optically very simple structure. Furthermore, since it can be constructed from a single lens, the number of components is reduced, and no lens bonding process is required, significantly reducing costs compared to existing structures. This makes the overall optical system extremely lightweight.

[0036] In the optical component 20, the polarization control component PC2 includes a reflective optical element 22 and a first wave plate 124 in order from the image display panel 11 side. The polarization control component PC3 includes a second wave plate 224 and a reflective polarization optical element 25 in order from the lens component 21 side.

[0037] In the polarization control component PC2, the reflective optical element 22 is a transmissive mirror HM that partially transmits and partially reflects the image light ML. The reflective optical element 22 covers the pupil position PP where the eye EY or pupil is located and has a concave shape facing the pupil position PP and a convex shape facing the outside world. To ensure the brightness of the image light ML, the reflectivity of the reflective optical element 22 for the image light ML is, for example, approximately 50%, but is not limited to this. The reflective optical element 22 is a single-layer film or a multilayer film of a metal such as Al or Ag with adjusted film thickness. The reflective optical element 22 can be formed, for example, by lamination using vapor deposition, but can also be formed by attaching a sheet of reflective film.

[0038] The first wave plate 124 has a major axis or fast axis positioned between the vertical and horizontal directions, that is, between the Y and X directions, and converts circularly polarized light, such as right-handed circularly polarized light C1, that has passed through the lens component 21 into elliptically polarized light. The first wave plate 124 is formed, for example, from a liquid crystal material such as a photo-crosslinkable polymer liquid crystal material. The first wave plate 124 is a flexible, film-like wave plate, specifically formed from a UV-curable, photo-crosslinkable polymer liquid crystal material.

[0039] The lens component 21 is a convex-concave lens with positive refractive power, having a first optical surface 21a on the incident side and a second optical surface 21b on the exit side. The first optical surface 21a and the second optical surface 21b are curved surfaces, specifically spherical or aspherical surfaces. The lens component 21 is formed, for example, from a resin, but may also be made of glass. From the perspective of miniaturization, it is advantageous for the lens component 21 to be made of glass. In addition, the reflective optical element 22 is arranged opposite to the first optical surface 21a, more specifically, it is indirectly formed on the first optical surface 21a via the thin film-like first wave plate 124. That is, the first optical surface 21a and the reflective optical element 22 have the same shape, but the first optical surface 21a functions as a convex refractive surface, and the reflective optical element 22 functions as a concave reflective surface. On the other hand, the polarizing optical element 25 is arranged opposite to the second optical surface 21b, more specifically, it is formed on the second optical surface 21b via the thin film-like second wave plate 224. That is, second optical surface 21 b and polarizing optical element 25 have the same shape, but second optical surface 21 b functions as a concave refractive surface, and polarizing optical element 25 functions as a convex reflective surface.

[0040] In the polarization control component PC3, the major axis or fast axis of the second wavelength plate 224 is set between the vertical and horizontal directions, that is, between the Y and X directions. The retardation of the combined first and second wavelength plates 124 and 224 is equivalent to that of a quarter-wave plate. Specifically, the second wavelength plate 224 converts elliptically polarized light that has passed through the lens component 21 into first vertically polarized light L1 having a first polarization direction corresponding to the vertical or perpendicular direction, that is, the Y direction. The second wavelength plate 224 is formed of a liquid crystal material, such as a photo-crosslinkable polymer liquid crystal material. The second wavelength plate 224 is a flexible, film-like wavelength plate, specifically formed of a UV-curable, photo-crosslinkable polymer liquid crystal material.

[0041] The manufacturing process of the first wave plate 124 and the second wave plate 224 is briefly described. For example, a photo-crosslinkable polymer liquid crystal material is coated on a flexible transparent resin substrate to form a layer, or thin film, of the photo-crosslinkable polymer liquid crystal material. By irradiating the thin film with linearly polarized ultraviolet light of a controlled polarization direction, the thin film of the photo-crosslinkable polymer liquid crystal material is cured, while simultaneously controlling the orientation of the rod-shaped molecular species exhibiting liquid crystal properties (i.e., molecules with a refractive index difference between their major and minor axes). In this process, the ultraviolet light crosslinks the molecular species exhibiting liquid crystal properties that extend in a direction consistent with the polarization direction of the ultraviolet light, fixing their orientation in the same direction as the polarization direction. After ultraviolet light irradiation, the thin film of the photo-crosslinkable polymer liquid crystal material is annealed. Thus, the ultraviolet light can liquid-crystallize the molecular species exhibiting liquid crystal properties that have not changed in their orientation, aligning their orientation with the polymer portion that has already achieved the target orientation. The subsequent cooling fixes this orientation. In other words, a wave plate is obtained, comprising a thin film in which the orientation of the majority of the molecular species exhibiting liquid crystal properties, which constitute the photo-crosslinkable polymer liquid crystal material, are aligned. Such a wavelength plate can adjust retardation by adjusting its thickness. The first wavelength plate 124 and the second wavelength plate 224 thus obtained are attached to the first optical surface 21a and the second optical surface 21b, respectively, using, for example, an adhesive, thereby being fixed to the lens component 21. In the above description, the wavelength plates 124 and 224 are formed by coating a photo-crosslinkable polymer liquid crystal material on a transparent resin substrate. However, the wavelength plates 124 and 224 can also be formed directly on the optical surfaces 21a and 21b of the lens component 21 by coating.

[0042] Liquid crystal optical bodies such as the first wave plate 124 and the second wave plate 224 can also be manufactured by the method for manufacturing a liquid crystal optical body described in Japanese Patent Application Publication No. 2008-501147.

[0043] It can be produced by the method described in https: / / www.jstage.jst.go.jp / article / oubutsu1932 / 70 / 9 / 70_9_1078 / _pdf.

[0044] Reference Figure 3The following describes the research conducted during the manufacture of the first and second wavelength plates 124 and 224. The retardation of the wavelength plates 124 and 224 varies depending on the thickness of the liquid crystal layer. When applying a photocrosslinkable polymer liquid crystal material to the optical surfaces 21a and 21b, a spin coater or other method can be used. However, the liquid crystal material contains a solvent and has low viscosity during application, which may result in uneven film thickness within the optical surfaces 21a and 21b. However, for the first wavelength plate 124, the liquid crystal material LL1 is spin-coated onto the lens component 21A with the convex first optical surface 21a facing upward. For the second wavelength plate 224, the liquid crystal material LL2 is spin-coated onto the lens component 21B with the concave second optical surface 21b facing upward. Therefore, the first wave plate 124 on the convex first optical surface 21a tends to become thinner on the inside and thicker on the outside, while the second wave plate 224 on the concave second optical surface 21b tends to become thicker on the inside and thinner on the outside. As a result, the film thickness distribution of the first wave plate 124 and the film thickness distribution of the second wave plate 224 cancel each other out, allowing the wave plates 124 and 224 to function as a uniform and precise quarter-wave plate in the direction perpendicular to the optical axis AX. Even if the curvatures of the first optical surface 21a and the second optical surface 21b differ significantly, the film thickness distributions of the wave plates 124 and 224 can be canceled out by appropriately adjusting the viscosities of the liquid crystal material applied to the first optical surface 21a and the second optical surface 21b, respectively. Furthermore, if spin coating is used, the film thickness distribution within the lens surface can be controlled by adjusting the rotation speed while taking into account the viscosity of the liquid crystal material, making it easier to cancel out the film thickness distributions of the wave plates 124 and 224.

[0045] return Figure 2The polarization optical element 25 is a wire grid polarizer that selectively reflects the first linear polarized light L1 having the first polarization direction corresponding to the Y direction, which is the vertical or plumb direction, and selectively transmits only the second vertical polarized light L2 having the second polarization direction corresponding to the X direction, which is the horizontal direction. The polarization optical element 25 has, for example, the following structure: a plurality of metal fine wires made of aluminum, nickel, or the like are arranged in parallel on a flexible transparent resin substrate, and the wire grid layer composed of the plurality of metal fine wires is covered with a transparent protective layer. The polarization optical element 25 reflects linear deflection having an electric field component (equivalent to the polarization direction) parallel to the direction in which the plurality of metal fine wires extend and perpendicular to the periodic direction corresponding to the arrangement direction. The main body of the polarization optical element 25 is manufactured as follows: after transferring the concave-convex shape to the surface of a resin film formed of a UV resin or a thermoplastic resin using a mold having a concave-convex structure, aluminum is evaporated from an oblique direction onto the top and side surfaces of the convex portions of the concave-convex shape using a vacuum evaporation method. The main body of the polarizing optical element 25 can also be manufactured by applying a polymer solution on a mold having a concave-convex structure using a spin coating method and solidifying the polymer solution formed on the mold surface (for example, see Japanese Patent Application Publication No. 2011-221334). The polarizing optical element 25 thus obtained is fixed to the lens component 21 by, for example, attaching it to the second wave plate 224 using an adhesive.

[0046] The polarization optical element 25 does not need to be a wire grid polarizer, and may be a type of polarizer in which a plurality of films having anisotropy are laminated, for example.

[0047] Reference Figure 4The image light ML emitted from the display 10 passes through the polarization control component PC1 and becomes right-handed circularly polarized light C1. The right-handed circularly polarized light C1 incident on the optical component 20 from the display 10 partially passes through the reflective optical element 22, but its intensity is attenuated to approximately half during transmission. The image light ML that has passed through the reflective optical element 22 passes through the first wave plate 124, the lens component 21, and the second wave plate 224. At this time, the image light ML is refracted by the lens component 21 and is relatively converged by its positive refractive power. Furthermore, the image light ML passes through the first wave plate 124 and the second wave plate 224 in the forward direction, thereby being converted from right-handed circularly polarized light C1 to first linearly polarized light L1 having a first polarization direction, and then enters the polarization optical element 25. Image light ML incident on the polarizing optical element 25 is efficiently reflected by the polarizing optical element 25 as first linearly polarized light L1. Upon passing through the lens component 21, it passes through the second wave plate 224 and the first wave plate 124 in the opposite direction, thereby being converted into right-handed circularly polarized light C1. Image light ML emitted from the first wave plate 124 is reflected by the reflecting optical element 22, where it is relatively converged by the positive refractive power. However, its intensity is attenuated to approximately half upon reflection. At this point, image light ML is converted from right-handed circularly polarized light C1 to left-handed circularly polarized light C2. Image light ML, as left-handed circularly polarized light C2, reflected by the reflecting optical element 22, passes through the first wave plate 124 and the second wave plate 224 in the forward direction upon passing through the lens component 21, thereby being converted into second linearly polarized light L2 having a second polarization direction, and then incident on the polarizing optical element 25. As described above, the image light ML is reflected by the reflective optical element 22 and travels back and forth in the lens component 21. This travel passes through the lens component 21 twice, and as a result, passes through the lens component 21 three times. The image light ML incident on the polarizing optical element 25 via the lens component 21 is efficiently transmitted through the polarizing optical element 25 as the second linear polarized light L2 in the second polarization direction. The image light ML emitted to the outside of the optical component 20 is collimated by the converging action of the optical component 20 and is incident on the pupil position PP (refer to FIG. 1 ) where the eye EY of the wearer US is located. Figure 2 ) That is, the wearer US wearing the first virtual image display device 100A can observe the virtual image based on the video light ML.

[0048] exist Figure 2 In the case of the display optical systems 103a and 103b shown, since the second optical surface 21b is concave, the ray angle of the image light ML emitted from the image display panel 11 can be tilted inward, i.e., toward the optical axis AX, and the material of the lens component 21 can have a margin in the total reflection angle. Therefore, the lens curvature can be increased, and the image display panel 11 and the optical system as a whole can be miniaturized. Furthermore, the ratio of the curvature R1 of the first optical surface 21a to the curvature R2 of the second optical surface 21b satisfies the following relationship:

[0049] 0.5≤R1 / R2≤1.5

[0050] This allows the ray angle of the image light ML emitted from the image display panel 11 to be approximately parallel to the panel normal direction (a direction parallel to the optical axis AX). Consequently, the image light ML emitted in the direction normal to the panel enters the eye EY when viewed by the user through the display optical systems 103a and 103b, allowing the user to see a virtual image without uneven brightness or color. In particular, the curvature R2 of the second optical surface 21b is preferably between 5 mm and 30 mm.

[0051] The virtual image display devices 100A and 100B and the optical unit 100 of the first embodiment described above include: a display 10 that emits circularly polarized image light ML; and an optical component 20 that forms a virtual image by folding the image light ML back twice by reflection, wherein the optical component 20 includes: a lens component 21; a transmissive reflective optical element 22 that is disposed opposite to a first optical surface 21a of the lens component 21 that is close to the display 10; and a reflective polarizing optical element 25 that is disposed opposite to a second optical surface 21b of the lens component 21 that is far from the display 10. It is arranged opposite to the ground to reflect the first polarized light L1, that is, the image light ML as the linearly polarized light in the first polarization direction; and the wavelength plates 124, 224, which are arranged between the reflecting optical element 22 and the polarization optical element 25, and are formed of a liquid crystal material such as a photo-cross-linkable polymer liquid crystal material, so that the image light ML passing through the reflecting optical element 22 becomes the first polarized light L1, that is, the linearly polarized light in the first polarization direction, and is reflected and traveled back and forth by the reflecting optical element 22, thereby making the image light ML passing through the lens component 21 twice become the second linearly polarized light L2 in the second polarization direction.

[0052] In the virtual image display device described above, the wave plates 124, 224 are formed from a liquid crystal material such as a photo-crosslinkable polymer liquid crystal material. Therefore, while film-like wave plates 124, 224 could be attached to the optical surfaces 21a, 21b, the ability to directly form the film-like wave plates 124, 224 on the optical surfaces 21a, 21b facilitates achieving the desired birefringence characteristics of the wave plates 124, 224. In other words, even if the first optical surface 21a, 21b, or the second optical surface 21b, is curved, achieving the desired birefringence characteristics of the wave plates 124, 224 formed on these optical surfaces 21a, 21b is facilitated.

[0053] In addition, the first polarization direction and the second polarization direction are set for convenience, and the definition of the specific directions can be exchanged. Figure 2 and Figure 4In the example shown, the polarizing optical element 25 reflects the first polarized light L1 having the first polarization direction in the Y direction. However, the polarizing optical element 25 may also reflect the first polarized light L1 having the first polarization direction in the X direction. In this case, the directions of the principal axes of the wave plates 124 and 224 are adjusted to suit the polarizing optical element 25.

[0054] In the virtual image display devices 100A and 100B of the first embodiment, the wave plates 124 and 224 are divided and disposed between the first optical surface 21a and the reflective optical element 22, and between the second optical surface 21b and the polarizing optical element 25. This allows the film thickness distribution of the wave plates 124 and 224 to be offset, facilitating improved precision of the wave plates 124 and 224. Furthermore, the wave plates 124 and 224 are covered by the reflective optical element 22 and the polarizing optical element 25, thereby suppressing degradation due to the external environment.

[0055] In the virtual image display devices 100A and 100B of the first embodiment, the first optical surface 21a is convex, and the second optical surface 21b is concave. When the first optical surface 21a is convex, the reflective optical element 22 can have positive refractive power, and by reducing the distance between the display 10 and the optical component 20, the virtual image display devices 100A and 100B can be easily miniaturized. When the second optical surface 21b is concave, the ray angle of the image light ML emitted from the image display panel 11 can be tilted inward, i.e., toward the optical axis AX. This can reduce the refraction of the principal ray at the second optical surface 21b of the lens component 21 as a whole, thereby easily reducing aberrations in the optical component 20.

[0056] [Second embodiment]

[0057] Hereinafter, a virtual image display device according to a second embodiment will be described. Note that 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 portions common to the virtual image display device according to the first embodiment will be omitted.

[0058] like Figure 5 As shown, the optical component 20 includes, in order from the image display panel 11 side, a reflective optical element 22, a lens component 21, and a polarization control component PC3. Here, the reflective optical element 22 is a transmissive reflector HM formed on the first optical surface 21a of the lens component 21. The polarization control component PC3 includes, in order from the lens component 21 side, a quarter-wave plate 24 and a reflective polarization optical element 25. Specifically, the quarter-wave plate 24 is formed on the second optical surface 21b of the lens component 21 so as to be sandwiched between the curved second optical surface 21b and the polarization optical element 25.

[0059] Figure 6 It is an explanation Figure 5A conceptual diagram of the optical operation of the first display optical system 103a is shown. In this case, image light ML of right-handed circularly polarized light C1 incident on the optical component 20 from the display 10 partially transmits through the reflective optical element 22 and enters the lens component 21. The image light ML that has passed through the lens component 21 passes through the quarter-wave plate 24 in the forward direction. The image light ML that has passed through the quarter-wave plate 24 in the forward direction is converted into first linearly polarized light L1 in the first polarization direction and enters the polarizing optical element 25. The image light ML that has entered the polarizing optical element 25 is efficiently reflected by the polarizing optical element 25 as first linearly polarized light L1 and passes through the quarter-wave plate 24 in the reverse direction. The image light ML that has passed through the quarter-wave plate 24 in the reverse direction is converted into right-handed circularly polarized light C1, passes through the lens component 21, enters the reflective optical element 22, is reflected by the reflective optical element 22, and is subjected to relative convergence due to its positive refractive power. At this time, the image light ML is converted from right-handed circularly polarized light C1 to left-handed circularly polarized light C2. The image light ML of the left-handed circularly polarized light C2 reflected by the reflective optical element 22 passes through the quarter-wave plate 24 in the forward direction via the lens component 21. The image light ML that has passed through the quarter-wave plate 24 in the forward direction is converted into second linearly polarized light L2 in the second polarization direction and enters the polarizing optical element 25. The image light ML that has entered the polarizing optical element 25 efficiently transmits through the polarizing optical element 25 as the second linearly polarized light L2 in the second polarization direction.

[0060] In the case of this embodiment, the quarter-wave plate 24 is provided in the polarization control component PC3 , and only a single wavelength plate needs to be provided in the optical component 20 , which can simplify the manufacturing process of the optical component 20 .

[0061] [Third embodiment]

[0062] Hereinafter, a virtual image display device according to a third embodiment will be described. Note that the virtual image display device according to the third embodiment is a partially modified version of the virtual image display device according to the first embodiment, and description of the parts common to the virtual image display device according to the first embodiment will be omitted.

[0063] like Figure 7 As shown, the optical component 20 includes, in order from the image display panel 11 side, a polarization control component PC2, a lens component 21, and a reflective polarization optical element 25. Here, the polarization control component PC2 includes a reflective optical element 22 and a quarter-wave plate 24. Specifically, the quarter-wave plate 24 is formed on the first optical surface 21a of the lens component 21 so as to be sandwiched between the curved first optical surface 21a and the reflective optical element 22.

[0064] In this embodiment, the polarization control component PC2 is provided with a quarter-wave plate 24. This simplifies the manufacturing process of the optical component 20 by only providing a single wavelength plate. In this case, when forming the quarter-wave plate 24 on the first optical surface 21a, the thickness of the liquid crystal material applied to the first optical surface 21a can also be actively distributed within the plane. In this embodiment, the angle of the image light ML passing through the quarter-wave plate 24 changes and increases depending on the distance from the optical axis AX, i.e., the image height. If the thickness of the liquid crystal material on the peripheral side decreases in accordance with this change in the passing angle, the functional uniformity of the quarter-wave plate 24 can be improved within the plane of the quarter-wave plate 24, thereby suppressing the generation of ghost light. As a method for adjusting the thickness of the liquid crystal material, for example, spraying can be used to adjust the thickness of the liquid crystal material applied to the first optical surface 21a. Specifically, the amount of liquid crystal material applied to the first optical surface 21a can be adjusted by spraying, and UV irradiation can be performed on the spot. This allows liquid crystal films of varying thicknesses to be provided on first optical surface 21 a , forming different phase difference distributions at various locations within the surface, and making the function of quarter-wave plate 24 on image light ML uniform.

[0065] [Fourth embodiment]

[0066] Hereinafter, a virtual image display device according to a fourth embodiment will be described. Note that the virtual image display device according to the fourth embodiment is a partially modified version of the virtual image display device according to the first embodiment, and description of portions common to the virtual image display device according to the first embodiment will be omitted.

[0067] like Figure 8 As shown, in the first display optical system 103 a , the lens component 21 is a meniscus lens having positive refractive power as a whole, and includes a first lens 121 and a second lens 221 , which are bonded together via a quarter-wave plate 24 .

[0068] The optical surface 21c on the emission side of the first lens 121 is concave, while the optical surface 21d on the incident side of the second lens 221 is convex, with both surfaces having the same curvature. In this case, the quarter-wave plate 24 has a shape that mimics the curved optical surfaces 21c and 21d. In other words, the quarter-wave plate 24 is embedded within the lens component 21.

[0069] Figure 9 It is an explanation Figure 8A conceptual diagram of the optical operation of the first display optical system 103a is shown. In this case, image light ML of right-handed circularly polarized light C1 incident on the optical component 20 from the display 10 partially transmits through the reflective optical element 22 and enters the lens component 21. After passing through the first lens 121, the image light ML is converted from the forward direction by the quarter-wave plate 24 into first linearly polarized light L1 in the first polarization direction. The image light ML passes through the second lens 221 and enters the polarizing optical element 25. The image light ML incident on the polarizing optical element 25 is efficiently reflected by the polarizing optical element 25 as first linearly polarized light L1 and passes through the quarter-wave plate 24 in the reverse direction. The image light ML that passes through the quarter-wave plate 24 in the reverse direction is converted into right-handed circularly polarized light C1 and enters the reflective optical element 22. At this point, the image light ML is converted from right-handed circularly polarized light C1 to left-handed circularly polarized light C2. The image light ML of the left-handed circularly polarized light C2 reflected by the reflecting optical element 22, when passing through the lens component 21, is converted from the forward direction to the second linearly polarized light L2 in the second polarization direction by the quarter-wave plate 24, and then enters the polarizing optical element 25. The image light ML entering the polarizing optical element 25 is efficiently transmitted through the polarizing optical element 25 as the second linearly polarized light L2 in the second polarization direction.

[0070] In this embodiment, a liquid crystal material, such as a photo-crosslinkable polymer liquid crystal material, can be applied to either the first lens 121 or the second lens 221, and sealed between the two lenses 121 and 221. In this case, one of the first lens 121 and the second lens 221 serves as the base, while the other functions as a cover lens. This prevents the quarter-wave plate 24 from coming into contact with the user's hand, and by sealing the periphery with an adhesive, moisture intrusion is suppressed, thereby easily preventing degradation of the quarter-wave plate 24.

[0071] Furthermore, if the refractive indices of the first lens 121 and the second lens 221 are different, a lens effect can be generated between the glass materials, thereby achieving further higher resolution and further reducing the size, thickness, and weight of the entire optical system.

[0072] [Fifth embodiment]

[0073] Hereinafter, a fifth embodiment of the virtual image display device will be described. The fifth embodiment of the virtual image display device is a partially modified version of the first embodiment of the virtual image display device, and descriptions of portions common to the first embodiment of the virtual image display device will be omitted.

[0074] like Figure 10As shown, in the first display optical system 103a, the lens component 21 of the optical component 20 is a convex-planar lens. The first optical surface 21a is a spherical surface or an aspherical surface. In this case, the second optical surface 21b is a plane. Therefore, even when the quarter-wave plate 24 and the polarizing optical element 25 are attached to the lens component 21, the quarter-wave plate 24 and the polarizing optical element 25 attached to the optical component 20 do not need to be flexible and do not need to deform accordingly with the second optical surface 21b. Therefore, the quarter-wave plate 24 and the polarizing optical element 25 can be formed on a non-resin substrate such as glass. In addition, the second optical surface 21b is a plane. When the quarter-wave plate 24 is directly formed on the second optical surface 21b, it is relatively easy to adjust the thickness of the liquid crystal material.

[0075] The quarter-wave plate 24 may be formed on the first optical surface 21 a and inside the reflective optical element 22 , or may be formed inside the lens member 21 .

[0076] In the case of the display optical systems 103a and 103b shown in the figure, the FOV reaches 120°, and the thickness from the display 10 to the rear end emission surface at the outer edge of the optical component 20 is 14.8 mm.

[0077] [Sixth embodiment]

[0078] Hereinafter, a virtual image display device according to a sixth embodiment will be described. Note that the virtual image display device according to the sixth embodiment is a partially modified version of the virtual image display device according to the first embodiment, and description of portions common to the virtual image display device according to the first embodiment will be omitted.

[0079] like Figure 11 As shown, in the first display optical system 103a, the lens component 21 of the optical component 20 is a biconvex lens. The first optical surface 21a and the second optical surface 21b are spherical or aspherical. By making the first optical surface 21a and the second optical surface 21b curved, aberrations can be easily reduced.

[0080] The quarter-wave plate 24 may be formed on the first optical surface 21 a and inside the reflective optical element 22 , or may be formed inside the lens member 21 .

[0081] In the case of the display optical systems 103a and 103b shown in the figure, the FOV reaches 120°, and the thickness of the rear end emission surface from the display 10 to the center of the optical component 20 is 14.9 mm.

[0082] [Variations and others]

[0083] 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.

[0084] In the above-described embodiment, the lens member 21 assembled in the optical member 20 is merely an example, and may include one or two lenses in a joined or separated state.

[0085] Although not essential, the optical component 20 preferably has a FOV of 100° or greater, and the thickness of the rear end emission surface from the display 10 to the outer edge or center of the optical component 20 is preferably 20 mm or less.

[0086] The above description assumes that the HMD 200 is worn on the head. However, the virtual image display devices 100A and 100B can also be used as handheld displays for viewing like binoculars. That is, in the present invention, head-mounted displays also include handheld displays.

[0087] The first wave plate 124 and the second wave plate 224 are not limited to the photo-crosslinkable polymer liquid crystal material, but may be various liquid crystal materials, and may be attached to the first optical surface 21 a or the second optical surface 21 b .

[0088] Figure 4 The polarization states shown are examples. For example, the image light ML emitted from the display 10 can be set to left-handed circularly polarized light. In this case, the polarization optical element 25 needs to selectively reflect only the vertically polarized light with a polarization direction corresponding to the X direction as the horizontal direction, and selectively transmit the linearly polarized light with a polarization direction corresponding to the Y direction as the vertical direction.

[0089] The first virtual image display device in the specific embodiment includes: a display, which emits circularly polarized image light; and an optical component, which forms a virtual image by reflecting the image light twice, the optical component including: a lens component; a transmissive reflective optical element, which is arranged opposite to the first optical surface of the lens component close to the display; a reflective polarization optical element, which is arranged opposite to the second optical surface of the lens component away from the display, and reflects the image light as linearly polarized light in the first polarization direction; and a wavelength plate, which is arranged between the reflective optical element and the polarization optical element, and is formed of a liquid crystal material, so that the image light passing through the reflective optical element becomes linearly polarized light in the first polarization direction, and the image light reflected and returned by the reflective optical element becomes linearly polarized light in the second polarization direction.

[0090] In the aforementioned virtual image display device, the wave plate is formed of a liquid crystal material. Therefore, it is easy to attach the film-like wave plate to the optical surface. Alternatively, the film-like wave plate can be formed directly on the optical surface without attachment, making it easy to match the birefringence characteristics of the wave plate to the target. For example, even if the first and second optical surfaces are curved, it is easy to match the birefringence characteristics of the wave plate formed on these optical surfaces to the target.

[0091] In a specific embodiment of the virtual image display device, the liquid crystal material is a photo-crosslinkable polymer liquid crystal material. In this case, the wavelength plate can be manufactured more easily and accurately.

[0092] In a specific embodiment of the virtual image display device, the photo-crosslinkable polymer liquid crystal material is a UV-curable type. In this case, by irradiating a layer of the photo-crosslinkable polymer liquid crystal material coated on an optical surface or a light-transmitting resin substrate with UV light, the alignment state of the molecular species exhibiting liquid crystal properties can be controlled while curing the photo-crosslinkable polymer liquid crystal material layer.

[0093] In a specific embodiment of a virtual image display device, a wavelength plate is formed by irradiating a thin film of a photo-crosslinkable polymer liquid crystal material with ultraviolet light of controlled polarization state and then annealing the film. This allows molecular species whose alignment state is not altered by the ultraviolet light to be liquid-crystallized, resulting in their alignment being aligned with the target alignment state.

[0094] In a specific embodiment of the virtual image display device, the wave plate is provided between the second optical surface and the polarization optical element.

[0095] In a specific embodiment of the virtual image display device, the wave plate is provided between the first optical surface and the reflective optical element.

[0096] In a virtual image display device according to a specific embodiment, the wave plate is provided in a divided manner between the first optical surface and the reflective optical element and between the second optical surface and the polarizing optical element.

[0097] In a specific embodiment of the virtual image display device, the wave plate is embedded in the interior of the lens member.

[0098] In a specific embodiment of the virtual image display device, the polarizing optical element is a reflective polarizer having a wire grid layer. In this case, the polarizing optical element can be attached to an optical surface, and even if the optical surface is curved, the polarizing optical element can be formed relatively easily on the optical surface.

[0099] In a specific embodiment of the virtual image display device, the first optical surface is a convex surface. In this case, the reflective optical element can have a positive refractive power, and the virtual image display device can be easily miniaturized by reducing the distance between the display and the optical components.

[0100] In a specific embodiment of the virtual image display device, the second optical surface is a concave surface. In this case, the refraction of the principal ray at the second optical surface of the lens component can be reduced as a whole, and the aberration of the optical component can be easily reduced.

[0101] The second virtual image display device in a specific embodiment includes: a display, which emits circularly polarized image light; and an optical component, which forms a virtual image by reflecting the image light back twice, the optical component including: a lens component; a transmissive reflective optical element, which is arranged opposite to the first optical surface of the lens component close to the display; a reflective polarization optical element, which is arranged opposite to the second optical surface of the lens component away from the display, and reflects the image light as linearly polarized light in the first polarization direction; and a wavelength plate, which is arranged between the reflective optical element and the polarization optical element, and is formed in a layer on the optical surface of the curved surface of the lens component, so that the image light passing through the reflective optical element becomes linearly polarized light in the first polarization direction, and the image light reflected and traveling back and forth by the reflective optical element becomes linearly polarized light in the second polarization direction.

[0102] In the second virtual image display device according to a specific embodiment, the wave plate is formed by coating the curved optical surface of the lens member.

[0103] The optical unit in the specific embodiment includes: a display, which emits circularly polarized image light; and an optical component, which folds the image light back twice by reflection to form a virtual image, the optical component comprising: a lens component; a transmissive reflective optical element, which is arranged opposite to the first optical surface of the lens component close to the display; a reflective polarization optical element, which is arranged opposite to the second optical surface of the lens component away from the display, and reflects the image light as linearly polarized light in the first polarization direction; and a wavelength plate, which is arranged between the reflective optical element and the polarization optical element, and is formed of a liquid crystal material, so that the image light passing through the reflective optical element becomes linearly polarized light in the first polarization direction, and the image light reflected and returned by the reflective optical element becomes linearly polarized light in the second polarization direction.

Claims

1. A virtual image display device comprising: a display that emits circularly polarized image light; and an optical component that folds the image light back twice by reflection to form a virtual image, The optical component has: lens components; a transmissive reflective optical element disposed opposite the first optical surface of the lens component close to the display; a reflective polarization optical element disposed opposite to the second optical surface of the lens member that is away from the display and reflects image light that is linearly polarized light in a first polarization direction; and The wavelength plate is arranged between the reflective optical element and the polarization optical element and is formed of a liquid crystal material. It makes the image light passing through the reflective optical element become linearly polarized light in a first polarization direction, and makes the image light reflected and traveling back and forth by the reflective optical element become linearly polarized light in a second polarization direction.

2. The virtual image display device according to claim 1, wherein: The liquid crystal material is a photo-crosslinkable polymer liquid crystal material.

3. The virtual image display device according to claim 2, wherein: The photo-crosslinkable polymer liquid crystal material is of ultraviolet curing type.

4. The virtual image display device according to claim 2, wherein: The wavelength plate is formed by irradiating a thin film formed of the photo-crosslinkable polymer liquid crystal material with ultraviolet rays having a controlled polarization state and annealing the thin film.

5. The virtual image display device according to claim 1, wherein: The wave plate is provided between the second optical surface and the polarization optical element.

6. The virtual image display device according to claim 1, wherein: The wave plate is provided between the first optical surface and the reflective optical element.

7. The virtual image display device according to claim 1, wherein: The wave plate is provided in a divided manner between the first optical surface and the reflecting optical element and between the second optical surface and the polarizing optical element.

8. The virtual image display device according to claim 1, wherein: The wave plate is embedded in the lens component.

9. The virtual image display device according to claim 1, wherein: The polarizing optical element is a reflective polarizer having a wire grid layer.

10. The virtual image display device according to claim 1, wherein: The first optical surface is a convex surface.

11. The virtual image display device according to claim 1, wherein: The second optical surface is a concave surface.

12. A virtual image display device comprising: a display that emits circularly polarized image light; and an optical component that folds the image light back twice by reflection to form a virtual image, The optical component has: lens components; a transmissive reflective optical element disposed opposite the first optical surface of the lens component close to the display; a reflective polarization optical element disposed opposite to the second optical surface of the lens member that is away from the display and reflects image light that is linearly polarized light in a first polarization direction; and A wavelength plate is arranged between the reflecting optical element and the polarizing optical element and is formed in a layer on the optical surface of the curved surface of the lens component, so that the image light passing through the reflecting optical element becomes linearly polarized light in the first polarization direction, and the image light reflected and returned by the reflecting optical element becomes linearly polarized light in the second polarization direction.

13. The virtual image display device according to claim 12, wherein: The wave plate is formed by coating the curved optical surface of the lens component.

14. An optical unit comprising: a display that emits circularly polarized image light; and an optical component that folds the image light back twice by reflection to form a virtual image, The optical component comprises: lens components; a transmissive reflective optical element disposed opposite the first optical surface of the lens component close to the display; a reflective polarization optical element disposed opposite to the second optical surface of the lens member that is away from the display and reflects image light that is linearly polarized light in a first polarization direction; and The wavelength plate is arranged between the reflective optical element and the polarization optical element and is formed of a liquid crystal material. It makes the image light passing through the reflective optical element become linearly polarized light in a first polarization direction, and makes the image light reflected and traveling back and forth by the reflective optical element become linearly polarized light in a second polarization direction.

Images