Virtual image display device and optical unit

Abstract

A virtual image display device and an optical unit. The purpose of the present invention is to reduce the thickness of an imaging optical system disposed between an imaging element and an eye while ensuring resolution. This virtual image display device is provided, in order from the outside world, with: a display which has a pixel region that emits video light, for example, as right circularly polarized light, and which partially transmits outside light; a first optical member that is flat on the display side and has a semi-transmissive reflective optical surface therein, the reflective optical surface having refractive power; a wavelength plate that is a 1 / 4 wavelength plate and converts the polarization state of the image light that has passed through the first optical member into linearly polarized light, i.e., vertically polarized light; and a second optical member including a polarization reflection layer that reflects the image light that has passed through the wavelength plate, and an image forming optical system, in which the first optical member, the wavelength plate, and the second optical member are combined, has substantially no refractive power with respect to left circularly polarized light, which is a polarization component of external light that has passed through the light-transmitting region of the display.

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 perspective virtual image display device capable of seeing an external image and the like. Background Art

[0002] As a virtual image display device, there is known a virtual image display device including: an image element that displays an image; a first optical unit disposed at an extraction position of image light; a second optical unit disposed on the side of the image element with respect to the first optical unit; a Fresnel type half mirror formed at a joint portion between the first optical unit and the second optical unit; and a transmission reflection selection member disposed on a light emission side of the first optical unit that selectively transmits or reflects according to a polarization state of light (Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-24246

[0005] In the above device, although it is possible to eliminate perspective distortion, when attempting to reduce the thickness of the imaging optical system disposed between the image element and the eye, there are problems such as insufficient refractive power with only a Fresnel type half mirror, inability to obtain high resolution, and easy occurrence of color unevenness in the periphery of the field of view. Summary of the Invention

[0006] A virtual image display device and an optical unit according to one aspect of the present invention include, in order from the outside world: a display having a pixel region that emits image light as circularly polarized light and partially transmits external light; a first optical member having a flat surface on the display side and having a semi-transmissive reflective optical surface with refractive power inside; a wavelength plate that converts the polarization state of the image light passing through the first optical member into linearly polarized light or circularly polarized light; and a second optical member including a polarization reflection layer that reflects the image light passing through the wavelength plate, and the imaging optical system formed by combining the first optical member, the wavelength plate, and the second optical member has substantially no refractive power with respect to the polarization component of the external light passing through the light transmissive region of the display. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0008] Figure 2 is a schematic side view for explaining an optical structure of the display optical system.

[0009] Figure 3AIt is a partially enlarged side view showing an example of the specific structure of the first display.

[0010] Figure 3B It is a partially enlarged rear view showing an example of the specific structure of the first display.

[0011] Figure 3C It is for explaining Figure 2 a diagram showing a modification related to the first display of the device shown.

[0012] Figure 4 It is for explaining Figure 2 a schematic diagram showing the polarization state of image light, etc. in the device shown.

[0013] Figure 5 It is for explaining Figure 3C a schematic diagram showing the polarization state in the modification shown.

[0014] Figure 6 It is a schematic diagram showing the polarization state in another modification.

[0015] Figure 7A It is a diagram showing the optical structure of the virtual image display device of the second embodiment.

[0016] Figure 7B It is a partially enlarged view of the center of the first display optical system.

[0017] Figure 8 It is a schematic side view showing the optical structure of the virtual image display device of the third embodiment.

[0018] Figure 9 It is for explaining Figure 8 a schematic diagram showing the polarization state of image light, etc. in the device shown.

[0019] Figure 10 It is for explaining Figure 8 a diagram showing a modification of the virtual image display device shown.

[0020] Figure 11 It is a schematic diagram showing the optical structure of the virtual image display device of the fourth embodiment.

[0021] Reference numeral description

[0022] 10a, 10b: Display; 11: Display panel; 11a: Light modulation element; 11b: Protective glass; 11d: Display surface; 11q: Polarizing element; 13: Polarizing component; 13a: Quarter-wave plate; 13b: Polarizing layer; 21, 22: Optical components; 23: Wave plate (quarter-wave plate); 323: Wave plate (half-wave plate); 90: User terminal; 100: Optical unit; 100A, 100B: Virtual image display device; 100C: Support device; 102a, 102b: Display driving unit; 103a, 103b: Combiner; A1: Pixel area; A2: Light-transmitting area; AX: Optical axis; EY: Eye; IS: Imaging optical system; ML: Image light; OL: Ambient light; P1: Vertically polarized light; P2: Horizontally polarized light; PP: Pupil position; PX: Pixel; Pr, Pg, Pb: Sub-pixels; R1: Reflective optical surface; R2: Polarization reflective layer; R21: Polarizing sheet; R22: Cholesteric liquid crystal layer; S1: Optical surface; S12: Fresnel optical surface; US: Wearer; c1: Right circularly polarized light; c2: Left circularly polarized light; q1: Vertically polarized light; q2: Horizontally polarized light. Detailed implementation mode

[0023] First implementation mode

[0024] Hereinafter, with reference to Figures 1 to 4 , the first implementation mode of the virtual image display device and the like according to the present invention will be described.

[0025] Figure 1 It is a diagram for explaining the wearing state of a head-mounted virtual image display device (hereinafter, also referred to as a head-mounted display or HMD) 200. The HMD 200 enables an observer or wearer US wearing the HMD 200 to recognize an image as a virtual image. In Figure 1 etc., X, Y, and Z are orthogonal coordinate systems. The +X direction corresponds to the horizontal direction in which the eyes EY of the observer or wearer US wearing the HMD 200 are arranged. The +Y direction is equivalent to the upper side perpendicular to the horizontal direction in which the eyes EY of the wearer US are arranged. The +Z direction is equivalent to the front or front direction of the wearer US. The ±Y direction is parallel to the vertical axis or the vertical direction.

[0026] The HMD 200 includes a first virtual image display device 100A of the direct virtual image type for the right eye, a second virtual image display device 100B of the direct virtual image type for the left eye, a pair of temple-like support devices 100C 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 alone as an HMD and is composed of a first display driving unit 102a arranged at the upper part and a first combiner 103a that covers in front of the eyes in the shape of spectacle lenses. Similarly, the second virtual image display device 100B functions alone as an HMD and is composed of a second display driving unit 102b arranged at the upper part and a second combiner 103b that covers in front of the eyes in the shape of spectacle lenses. The support device 100C is a wearing component worn on the head of the wearer US and supports the upper ends of the pair of combiners 103a and 103b by means of the display driving 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 the same or left-right reversed. Detailed description of the second virtual image display device 100B is omitted.

[0027] Figure 2 It is a side view for explaining the internal structure of the first virtual image display device 100A. The first virtual image display device 100A includes a first display 10a, a first display optical system 20a, and a first circuit component 80a. Among them, the first display 10a emits image light ML as circularly polarized light. The first display optical system 20a is an imaging optical system IS that directly forms a virtual image without forming an intermediate image. The first display optical system 20a, that is, the imaging optical system IS has: a first optical component 21 that has a reflective optical surface R1 with refractive power inside; a wavelength plate 23 that converts the polarization state of the image light ML into linearly polarized light or circularly polarized light; and a second optical component 22 that includes a polarization reflection layer R2. That is, the first virtual image display device 100A includes the first display 10a, the first optical component 21, the wavelength plate 23, and the second optical component 22 as optical elements in this order from the outside. The imaging optical system IS has substantially no refractive power with respect to the polarization component, that is, the left circularly polarized light c2, of the external light OL that passes through the light-transmitting regions A2 (refer to Figure 3A ) of the displays 10a and 10b, which will be described in detail below. Here, the imaging optical system IS having substantially no refractive power with respect to a specific polarization component of the external light OL means that the refractive power related to the specific polarization component of the external light OL is less than the refractive power related to the image light ML. More specifically, it means that the focal length of the imaging optical system IS related to the specific polarization component of the external light OL is, for example, about 1 to 2 m or more and below infinity.

[0028] The first optical component 21 and the second optical component 22 emit image light ML toward the pupil position PP or the eye EY via a reciprocating optical path formed by using the reflective optical surface R1 and the polarization reflection layer R2, and allow external light OL to directly pass through and enter the pupil position PP. The first optical component 21 is a semi-transmissive reflective optical element, and functions as an optical element having a positive refractive power with respect to the image light ML by using the reflective optical surface R1. The wavelength plate 23 is a quarter-wave plate. The second optical component 22 is a reflective polarization element, and functions as an optical element having a positive refractive power or a negative refractive power with respect to the image light ML by using the polarization reflection layer R2.

[0029] Although detailed description is omitted, the second virtual image display device 100B includes a second display 10b, a second display optical system 20b, and a second circuit component 80b. The second display 10b is the same as the first display 10a, the second display optical system 20b is the same as the first display optical system 20a, and the second circuit component 80b is the same as the first circuit component 80a. The second display optical system 20b includes the first optical component 21, the wavelength plate 23, and the second optical component 22.

[0030] In addition, in the first virtual image display device 100A, the optical device excluding the first circuit component 80a is referred to as the optical unit 100. Further, in the second virtual image display device 100B, the optical device excluding the second circuit component 80b is referred to as the optical unit 100.

[0031] In the first virtual image display device 100A, for example, the first display 10a emits image light ML, which is right-circularly polarized light, toward the first display optical system 20a, and allows a part of the external light OL including a left-circularly polarized light component to pass through.

[0032] Figure 3A And Figure 3B are a partially enlarged side view and a partially enlarged rear view for explaining an example of the specific configuration of the first display 10a. Refer to Figure 3A The first display 10a has a structure in which the display panel 11 and the polarization member 13 are laminated and integrated. Refer to Figure 3B The first display 10a independently has a quadrilateral pixel region A1 provided in a discrete configuration and a light-transmitting region A2 having light-transmittance. The pixel region A1 corresponds to the pixel PX of the first display 10a and is arranged in a matrix along the XY plane. That is, the pixel region A1 is two-dimensionally arranged periodically in the horizontal direction, i.e., the X direction, and the vertical direction, i.e., the Y direction.

[0033] The display panel 11 is a self-luminous type image light generation device. The display panel 11 has a light modulation element 11a and a protective glass 11b. The display panel 11 is, for example, an organic EL (Organic Electro-Luminescence) display, and forms a color still image or a moving image on the two-dimensional display surface 11d. The display panel 11 emits image light ML to the polarization member 13 in units of pixels PX corresponding to the pixel region A1. The pixel PX includes sub-pixels Pr, Pg, and Pb corresponding to the three colors RGB. The light modulation element 11a has light-shielding properties in the pixel region A1, preventing external light OL from passing through, and has light-transmitting properties in the light-transmitting region A2, allowing external light OL to pass through. The external light OL passes through the light-transmitting region A2 and thus passes through the imaging optical system IS without being affected by the pixel region A1. The display panel 11 is driven by the first circuit component 80a to perform a display operation.

[0034] The polarization member 13 has a quarter-wave plate 13a, and a quadrilateral polarization layer 13b is provided on the display panel 11 side of the quarter-wave plate 13a. Although not shown in the figure, in the entire polarization member 13, a plurality of polarization layers 13b are arranged in a matrix so as to face the pixel PX at the position of the pixel region A1 along the XY plane. The polarization layer 13b is configured to limit the transmitted light, that is, the image light ML, to polarized light having a specified polarization direction, specifically, vertically polarized light P1 having a first polarization direction, and block horizontally polarized light P2 having a second polarization direction perpendicular to the first polarization direction. The quarter-wave plate 13a is a plate-shaped member extending along the XY plane, and its fast axis or slow axis is set, for example, to an intermediate direction between the X direction and the Y direction, and converts the linearly polarized light that has passed through the polarization layer 13b into right-handed circularly polarized light c1. Here, the fact that the image light ML is circularly polarized means that when looking at the vibration of the electric field component or magnetic field component of the image light ML, its vibration direction rotates at the frequency of the image light ML in a plane perpendicular to the light traveling direction, and the amplitude is constant regardless of its orientation. Right-handed circularly polarized light means that when observed from the side of an observer standing in the direction of light propagation, the vibration direction of the electric field component rotates clockwise, and left-handed circularly polarized light is counterclockwise polarized light. However, in this specification, if the image light ML mainly includes right-handed circularly polarized light, for example, even if it includes linearly polarized light in a specific direction, such image light ML is regarded as right-handed circularly polarized light c1. Similarly, if the image light ML mainly includes left-handed circularly polarized light, such image light ML is regarded as left-handed circularly polarized light c2. In this specification, right-handed circularly polarized light c1 is also referred to as right circularly polarized light c1, and left-handed circularly polarized light c2 is also referred to as left circularly polarized light c2.

[0035] Refer to Figure 2, the first optical component 21 is a component with an overall parallel flat plate shape and has no overall refractive power with respect to transmitted light. In the first optical component 21, the first incident surface 31a on the display panel 11 side and the second exit surface 32b on the wavelength plate 23 side are parallel to each other and extend parallel to the XY plane. The first optical component 21 has a first lens element 31 and a second lens element 32 joined with the reflective optical surface R1 interposed therebetween. The first lens element 31 has a first incident surface 31a and a first exit surface 31b. The first incident surface 31a is a plane, and the first exit surface 31b is a continuous concave surface. Specifically, the first exit surface 31b is a concave spherical surface or aspherical surface. The second lens element 32 has a second incident surface 32a and a second exit surface 32b. The second incident surface 32a is a continuous convex surface, and the second exit surface 32b is a plane. On the second incident surface 32a of the second lens element 32, a reflective optical surface R1 composed of a single-layer or multi-layer metal film and having transmissivity is formed by evaporation or the like. The reflective optical surface R1 has the same shape as the second incident surface 32a. That is, the reflective optical surface R1 is an optical surface S1 of a continuous curved surface, which is a spherical surface or aspherical surface recessed with respect to the second exit surface 32b. The reflective optical surface R1 partially transmits the image light ML emitted from the display panel 11 at a prescribed transmittance (specifically, for example, 50%), and partially reflects the image light ML as the return light from the wavelength plate 23 and the second optical component 22 at a corresponding reflectance (specifically, for example, 50%). The first optical component 21 becomes an optical component like a cemented lens in which the continuous reflective optical surface R1 is embedded inside. The fact that the reflective optical surface R1 is semi-transmissive means that, for example, the transmittance can be appropriately set to be less than 100%. The transmittance of the reflective optical surface R1 is usually set in a range of 30% to 70%, but is not limited thereto.

[0036] The first lens element 31 is formed by a plastic material, glass forming, or other methods, and the second lens element 32 is also formed by a plastic material, glass forming, or other methods. The first lens element 31 and the second lens element 32 have equal refractive indices, and are joined to each other, for example, using an adhesive material having a refractive index equal to that of the first lens element 31. The reflective optical surface R1 may also be formed on the first incident surface 31a, and the second lens element 32 may also be a plastic material filled between the first lens element 31 and the wavelength plate 23 and cured.

[0037] The wavelength plate 23 is a quarter-wave plate. The wavelength plate 23 is a component with an overall parallel flat plate shape and has no overall refractive power with respect to transmitted light. The fast axis or slow axis of the wavelength plate 23 is set, for example, in an intermediate direction between the X direction and the Y direction perpendicular to the optical axis AX. The wavelength plate 23 converts the image light ML, which is right-circularly polarized light c1 emitted from the display panel 11 and passed through the first optical component 21, into linearly polarized light parallel to the longitudinal direction, i.e., the Y direction, that is, vertically polarized light q1. When the wavelength plate 23 allows the image light ML reflected by the polarization reflection layer R2 of the second optical component 22 to pass through the first optical component 21, it converts the image light ML into right-circularly polarized light c1. When the wavelength plate 23 allows the image light ML, which is reflected by the polarization reflection layer R2 of the second optical component 22 and then reflected by the reflection optical surface R1 of the first optical component 21 and converted into left-circularly polarized light c2, to pass through the second optical component 22, it converts the image light ML into linearly polarized light parallel to the X direction, that is, horizontally polarized light q2.

[0038] The second optical component 22 is a component with an overall parallel flat plate shape and has no overall refractive power with respect to transmitted light. In the second optical component 22, the third incident surface 33a on the wavelength plate 23 side and the fourth exit surface 34b on the eye EY side are parallel to each other and extend parallel to the XY plane. The second optical component 22 has a third lens element 33 and a fourth lens element 34 joined with the polarization reflection layer R2 interposed therebetween. The third lens element 33 has a third incident surface 33a and a third exit surface 33b. The third incident surface 33a is a plane, and the third exit surface 33b is a continuous curved surface. Specifically, the third exit surface 33b is an aspherical surface. The fourth lens element 34 has a fourth incident surface 34a and a fourth exit surface 34b. The fourth incident surface 34a is a continuous curved surface, and the fourth exit surface 34b is a plane. On the third exit surface 33b of the third lens element 33, as the polarization reflection layer R2, a wire grid and other reflective polarizers R21 are formed by patterning using evaporation, etching, etc. The polarization reflection layer R2 is an aspherical surface having the same shape as the third exit surface 33b. The polarization reflection layer R2 reflects the image light ML that passes through the reflection optical surface R1 and is converted into vertically polarized light q1 via the wavelength plate 23, and selectively allows the return light from the wavelength plate 23 and the first optical component 21 and the image light ML that is converted into horizontally polarized light q2 to pass through. The second optical component 22 becomes an optical component like a cemented lens in which a continuous polarization reflection layer R2 is embedded inside.

[0039] The third lens element 33 is formed by methods such as plastic material or glass molding, and the fourth lens element 34 is also formed by methods such as plastic material or glass molding. The third lens element 33 and the fourth lens element 34 have equal refractive indices, and are joined to each other, for example, using an adhesive material having a refractive index equal to that of the third lens element 33. The third lens element 33 may also be a plastic material filled between the fourth lens element 34 and the wavelength plate 23 and cured.

[0040] In the case where the polarization reflection layer R2 is a wire grid type polarization element, if the curvature of the polarization reflection layer R2 becomes large, the distribution of the extinction ratio in the plane becomes large. Therefore, it is preferable that, for example, the radius of curvature is set to 40 mm or more.

[0041] Refer to Figure 4 , and the polarization state of the image light ML, etc. in the first virtual image display device 100A shown in Figure 2 will be described. The image light ML from the first display 10a is right circularly polarized light c1, enters the first optical component 21 and partially passes through the reflective optical surface R1, and enters the wavelength plate 23 as a quarter-wave plate from the front. The image light ML that has passed through the wavelength plate 23 is converted into vertically polarized light q1 in the longitudinal direction, enters the second optical component 22 and is almost entirely reflected by the polarization reflection layer R2, and enters the wavelength plate 23 again. The image light ML that has passed through the wavelength plate 23 from the reverse direction is converted into right circularly polarized light c1, enters the first optical component 21 and is partially reflected by the reflective optical surface R1. The image light ML reflected by the reflective optical surface R1 is converted into left circularly polarized light c2, and enters the wavelength plate 23 as a quarter-wave plate from the front. The image light ML that has passed through the wavelength plate 23 is converted into horizontally polarized light q2 in the transverse direction, enters the second optical component 22 and passes through the polarization reflection layer R2. The image light ML emitted outside the second optical component 22 enters the eyes EY of the wearer US or the pupil position PP where the pupil is disposed (refer to Figure 2 ).

[0042] The external light OL is randomly polarized light, and the external light OL that has passed through the light transmissive region A2 at the first display 10a contains right circularly polarized light c1 and left circularly polarized light c2. The right circularly polarized light c1 emitted from the light transmissive region A2 of the first display 10a enters the first optical component 21 and partially passes through the reflective optical surface R1, and enters the wavelength plate 23. The external light OL that has passed through the wavelength plate 23 is converted into horizontally polarized light q2 in the transverse direction, enters the second optical component 22 and passes through the polarization reflection layer R2. Thus, although a specific component of the external light OL passes through the first display optical system 20a constituted by the optical components 21, 22, etc., the first display optical system 20a does not exert a lens effect on the external light OL.

[0043] In Figure 2In the first virtual image display device 100A shown, the thickness of the imaging optical system IS, that is, the distance from the first incident surface 31a of the first optical component 21 to the fourth emission surface 34b of the second optical component 22, is 7 mm or less. In addition, the FOV (Field of View) of the imaging optical system IS is set to approximately 100° diagonally. By setting the thickness of the imaging optical system IS to 7 mm or less, the virtual image display devices 100A, 100B, or the optical unit 100 can be made lighter. In this imaging optical system IS, although the thickness is 7 mm or less, the divergence state of the image light ML is accurately adjusted by the reflection of the reflective optical surface R1 and the polarization reflection layer R2, so that the resolution can be improved and color unevenness can be reduced.

[0044] Figure 3C is for explaining Figure 2 a modified example of the first display 10a shown. In this case, in the first display 10a, the display panel 11 has a polarization element 11q, a light modulation element 11a, and a protective glass 11b in this order from the outside. The polarization element 11q restricts the polarized light to a direction different from the polarization layer 13b of the polarization member 13. Specifically, it is configured to restrict the polarized light to the horizontal polarized light P2, which is the polarized light of the second polarization direction, and block the vertical polarized light P1, which is the polarized light of the first polarization direction perpendicular to the second polarization direction.

[0045] As Figure 5 shown, by adding the polarization element 11q to the display panel 11, the external light OL passing through the first display 10a can be restricted to only the left circularly polarized light c2, and the useless external light OL can be prevented from entering the first display optical system 20a.

[0046] In the above description, the displays 10a and 10b emit the image light ML as the right circularly polarized light c1, but the displays 10a and 10b can also emit the image light ML as the left circularly polarized light c2. In this case, the polarization reflection layer R2 selectively reflects the horizontal polarized light q2.

[0047] Figure 6This is a diagram for explaining the case where the first display 10a emits image light ML as left circularly polarized light c2. In this case, the image light ML as left circularly polarized light c2 that has passed through the reflective optical surface R1 of the first optical component 21 passes through the wavelength plate 23, which is a quarter-wave plate, from the front, and thus becomes horizontally polarized light q2, which is linearly polarized light, and is reflected by the polarization reflective layer R2. Then, it passes through the above wavelength plate 23 from the back, and thus becomes the original left circularly polarized light c2 and is partially reflected by the reflective optical surface R1. The image light ML reflected by the reflective optical surface R1 becomes right circularly polarized light c1 with the opposite sense of rotation, passes through the above wavelength plate 23 from the front, and thus becomes vertically polarized light q1, which is linearly polarized light in the cross direction, and passes through the polarization reflective layer R2. On the other hand, the right circularly polarized light c1 of the external light OL is incident on the first optical component 21 and partially passes through the reflective optical surface R1 and is incident on the wavelength plate 23. The external light OL that has passed through the wavelength plate 23 is converted into vertically polarized light q1, is incident on the second optical component 22, and passes through the polarization reflective layer R2.

[0048] The display panel 11 is not limited to a self-luminous type such as an organic EL display, and may also be a light modulation type liquid crystal display. In the case where the display panel 11 is a liquid crystal display, for example, a structure is considered in which a light guide plate is disposed on the external side of the display panel 11 and illumination light is supplied from the end of the light guide plate.

[0049] The display panel 11 can also perform display operations repeatedly at high speed. In this case, the display panel 11 can be, for example, a transmissive device in the pixel region A1, and by making the external light OL pass through during the non-display period, that is, during the gap between display operations, perspective observation can be performed.

[0050] The virtual image display devices 100A and 100B or the optical unit 100 according to the first embodiment described above include, in order from the outside: displays 10a and 10b, which have pixel regions A1 that emit image light ML as, for example, right circularly polarized light c1 and partially transmit the external light OL; a first optical component 21, the side of the first optical component 21 facing the displays 10a and 10b being planar, the first optical component 21 having a semi-transmissive reflective optical surface R1 inside, the reflective optical surface R1 having a refractive power; a wavelength plate 23, which is a quarter-wave plate and converts the polarization state of the image light ML that has passed through the first optical component 21 into linearly polarized light, that is, vertically polarized light q1; and a second optical component 22, which includes a polarization reflective layer R2 that reflects the image light ML that has passed through the wavelength plate 23, and the imaging optical system IS formed by combining the first optical component 21, the wavelength plate 23, and the second optical component 22 has substantially no refractive power with respect to the polarization component, that is, left circularly polarized light c2, of the external light OL that has passed through the light transmission region A2 of the displays 10a and 10b.

[0051] In the above-described virtual image display devices 100A, 100B, etc., the image light ML, such as the right circularly polarized light c1, that has passed through the reflective optical surface R1 passes through the wavelength plate 23 that serves as a quarter-wave plate, thereby becoming linearly polarized light, i.e., vertically polarized light q1, and is reflected by the polarization reflective layer R2. It then passes through the wavelength plate 23 again, thereby becoming the original right circularly polarized light c1 and being partially reflected by the reflective optical surface R1. The image light ML reflected by the reflective optical surface R1 becomes left circularly polarized light c2 with the opposite sense of rotation, passes through the above-described wavelength plate 23, and thereby becomes linearly polarized light in the cross direction, i.e., horizontally polarized light q2, and passes through the polarization reflective layer R2. That is to say, the image light ML is adjusted in the diverging state in two stages by reflection at the reflective optical surface R1 and the polarization reflective layer R2, and the image formed on the display surfaces 11d of the displays 10a, 10b can be observed as a highly accurate virtual image. In addition, the external light OL contains random polarization components, passes through the displays 10a, 10b and the reflective optical surface R1, and becomes linearly polarized light in the cross direction, i.e., horizontally polarized light q2, when passing through the wavelength plate 23, and then passes through the polarization reflective layer R2. At this time, the external light OL passes through the imaging optical system IS substantially without being affected by the lens action of the first optical component 21, the wavelength plate 23, and the second optical component 22. That is to say, it is possible to perform perspective observation of the external image while observing the virtual image with the aid of the imaging optical system IS.

[0052] Second Embodiment

[0053] Hereinafter, the virtual image display device and the like of the second embodiment will be described. In addition, the virtual image display device of the second embodiment is obtained by partially modifying the virtual image display device of the first embodiment, and the description of the parts common to the virtual image display device of the first embodiment will be omitted.

[0054] Figure 7A It is a side view for explaining the first display optical system 20a assembled in the virtual image display device of the second embodiment. Figure 7B It is a partially enlarged view of the center of the first display optical system 20a. The first display optical system 20a, i.e., the imaging optical system IS, includes: a first optical component 21 that has a reflective optical surface R1 with refractive power inside; a wavelength plate 23 that converts the polarization state of the image light ML into linearly polarized light or circularly polarized light; and a second optical component 22 that includes a polarization reflective layer R2.

[0055] The first exit surface 231b of the first lens element 31 provided in the first optical component 21 and the second entrance surface 232a of the second lens element 32 are Fresnel-type optical surfaces, which are equivalent to the first exit surface 31b and the second entrance surface 32a in the first optical component 21 of the first embodiment. Correspondingly, the reflective optical surface R1 built into the first optical component 21 is also a Fresnel optical surface S12 having the same shape as the second entrance surface 232a, and has the same refractive power as the reflective optical surface R1 built into the first optical component 21 of the first embodiment.

[0056] The first lens element 31 of the first optical component 21 is a lens element flattened by filling the second entrance surface 232a formed with the Fresnel optical surface S12 of the second lens element 32 with an adhesive material or a base material having the same refractive index as the second lens element 32. Conversely, the second lens element 32 may be a lens element flattened by filling the first exit surface 231b formed with the Fresnel optical surface S12 of the first lens element 31 with an adhesive material or a base material having the same refractive index as the first lens element 31.

[0057] In the virtual image display devices 100A and 100B of the present embodiment, the reflective optical surface R1 is the Fresnel optical surface S12, and the first optical component 21 has the first lens element 31 and the second lens element 32 joined with the reflective optical surface R1 interposed therebetween. In this case, the first optical component 21 is in the shape of a parallel flat plate as a whole, and the Fresnel optical surface S12 is buried inside. By using the Fresnel optical surface S12, the imaging optical system IS can be made thinner.

[0058] In the present embodiment, the thickness of the imaging optical system IS, that is, the distance from the first entrance surface 31a of the first optical component 21 to the fourth exit surface 34b of the second optical component 22 is 7 mm or less, specifically about 6.7 mm.

[0059] Third Embodiment

[0060] Hereinafter, the virtual image display device and the like of the third embodiment will be described. In addition, the virtual image display device of the third embodiment is a device obtained by partially modifying the virtual image display device of the first embodiment.

[0061] Figure 8 [[ID=]19]It is a side view for explaining the first display optical system 20a assembled in the virtual image display device of the third embodiment. The first display optical system 20a, that is, the imaging optical system IS, includes: a flat first optical component 21 having a reflective optical surface R1 with refractive power inside; a wavelength plate 323 that converts the polarization state of the image light ML into different circularly polarized lights; and a flat second optical component 22 including a planar polarization reflection layer R2.

[0062] The wave plate 323 is a half-wave plate. The wave plate 323 is a component with an overall parallel flat-plate shape and has no overall refractive power with respect to transmitted light.

[0063] In the second optical component 22, as the polarization reflection layer R2, a cholesteric liquid crystal layer R22 is formed on the third light-emitting surface 33b of the third lens element 33. The outer side surface of the polarization reflection layer R2 is a plane having the same shape as the third light-emitting surface 33b. The cholesteric liquid crystal layer R22 maintains the image light ML that has become left-circularly polarized light c2 through the wave plate 323 in the state of left-circularly polarized light c2 and selectively reflects it.

[0064] The cholesteric liquid crystal layer R22 has a layered structure of molecules oriented in a certain direction, and there is a twist in the molecular orientation axes between adjacent layers. As a whole, the orientation direction forms a helical structure around the vertical axis of the layer. The cholesteric liquid crystal layer R22 is composed of a specified liquid crystal material and has the property of transmitting right-circularly polarized light c1 and reflecting left-circularly polarized light c2. The cholesteric liquid crystal layer R22 becomes a liquid crystal material layer with suppressed fluidity and a stable state by the following means: a liquid crystal material containing a liquid crystal material and an additive is sandwiched between the third lens element 33 and the fourth lens element 34, the third lens element 33 and the fourth lens element 34 are relatively fixed, and in this state, UV light or the like is irradiated on the liquid crystal material sandwiched by them, or the solvent is removed from the liquid crystal material sandwiched by them or the solvent is vaporized, or the liquid crystal material sandwiched by them is heated. That is to say, the cholesteric liquid crystal layer R22 is formed by stabilizing the liquid crystal material. It is also possible that the cholesteric liquid crystal layer R22 is cured on the surface of one of the third lens element 33 and the fourth lens element 34, and the other of the third lens element 33 and the fourth lens element 34 is pasted and clamped. In addition, regarding the production of the cholesteric liquid crystal layer R22, the methods described in Japanese Patent Application Laid-Open No. 2008-501147 and Japanese Patent Application Laid-Open No. 2021-532393 can be applied. Regarding the cholesteric liquid crystal layer R22, by rotating the liquid crystal orientation with respect to the optical axis during its production, only one circularly polarized light can be reflected, and a refractive power can be applied during reflection. That is to say, even if the cholesteric liquid crystal layer R22 itself is planar, it can thereby give a lens effect to the reflected image light ML.

[0065] Refer to Figure 9, in the virtual image display devices 100A, 100B, etc., the image light ML, such as the right circularly polarized light c1, that has passed through the reflective optical surface R1 passes through the wavelength plate 323 that acts as a 1 / 2 wavelength plate, thereby becoming circularly polarized light, i.e., left circularly polarized light c2, and is reflected by the polarization reflective layer R2. It then passes through the wavelength plate 323 again, thereby becoming the original right circularly polarized light c1 and being partially reflected by the reflective optical surface R1. The image light ML reflected by the reflective optical surface R1 becomes left circularly polarized light c2 with the opposite sense of rotation, passes through the above-mentioned wavelength plate 323, and thereby becomes the original circularly polarized light, i.e., right circularly polarized light c1, and passes through the polarization reflective layer R2. That is to say, the image light ML is adjusted in the divergent state in two stages by reflection on the reflective optical surface R1 and the polarization reflective layer R2, and the image formed on the display surfaces 11d of the displays 10a, 10b can be observed as a high-precision virtual image. In addition, the external light OL contains random polarization components. After passing through the displays 10a, 10b and the reflective optical surface R1, when passing through the wavelength plate 323, the left circularly polarized light c2 becomes right circularly polarized light c1 and passes through the polarization reflective layer R2. At this time, the external light passes through the imaging optical system IS substantially without being affected by the lens action of the first optical component 21, the wavelength plate 323, and the second optical component 22. That is to say, it is possible to observe the external image through the imaging optical system IS.

[0066] Although detailed description is omitted, similar to the modification Figure 3C shown in the first embodiment, a polarization element 11q can be added to the display panel 11. Thereby, only the left circularly polarized light c2 can be incident on the first display optical system 20a, i.e., the imaging optical system IS.

[0067] In addition, the first display 10a can also emit the image light ML as left circularly polarized light c2. In this case, the polarization reflective layer R2 is a cholesteric liquid crystal layer R22 that transmits the left circularly polarized light c2 and reflects the right circularly polarized light c1.

[0068] Figure 10 is used to illustrate Figure 1 a modification of the first display optical system 20a shown. In this case, the polarization reflective layer R2 is not a plane, but a curved surface such as an aspherical surface, and the cholesteric liquid crystal layer R22 is provided along this curved surface. In addition, the polarization reflective layer R2 is not limited to the illustrated curved surface and can be various curved surfaces considering aberration correction and refractive power.

[0069] Fourth Embodiment

[0070] Hereinafter, the virtual image display device and the like of the fourth embodiment will be described. In addition, the virtual image display device of the fourth embodiment is a device obtained by partially modifying the virtual image display device of the third embodiment.

[0071] Figure 11 This is a side view for explaining the first display optical system 20a assembled in the virtual image display device of the fourth embodiment. Similar to the case of the third embodiment, the first display optical system 20a, i.e., the imaging optical system IS, includes: a first optical component 21 having a reflective optical surface R1 with refractive power inside; a wavelength plate 323 that converts the polarization state of the image light ML into different circularly polarized lights; and a second optical component 22 including a polarization reflection layer R2.

[0072] The first emission surface 231b of the first lens element 31 provided in the first optical component 21 and the second incident surface 232a of the second lens element 32 are Fresnel-type optical surfaces, which are equivalent to the first emission surface 31b and the second incident surface 32a in the first optical component 21 of the third embodiment. Correspondingly, the reflective optical surface R1 built into the first optical component 21 is also a Fresnel optical surface S12 having the same shape as the second incident surface 232a and has the same refractive power as the reflective optical surface R1 built into the first optical component 21 of the third embodiment.

[0073] In the virtual image display devices 100A and 100B of the present embodiment, the reflective optical surface R1 is the Fresnel optical surface S12, and the first optical component 21 has a first lens element 31 and a second lens element 32 joined with the reflective optical surface R1 interposed therebetween. In this case, the first optical component 21 is in the shape of a parallel plate as a whole, and the Fresnel optical surface S12 is embedded inside.

[0074] The first lens element 31 of the first optical component 21 is, for example, a lens element flattened by filling the second incident surface 232a of the second lens element 32, which has the Fresnel optical surface S12, with an adhesive material or a base material having the same refractive index as the second lens element 32.

[0075] In the present embodiment, the thickness of the imaging optical system IS, that is, the distance from the first incident surface 31a of the first optical component 21 to the fourth emission surface 34b of the second optical component 22, is 7 mm or less, specifically about 6.3 mm.

[0076] Modifications and others

[0077] 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 ways without departing from its gist. For example, the following modifications can also be made.

[0078] The above assumes that the HMD 200 is used while being worn on the head. However, the above virtual image display devices 100A and 100B can also be used as a handheld display that is not worn on the head but is peeked through like binoculars. That is, in the present invention, the head-mounted display also includes a handheld display.

[0079] In the above-described embodiment, in the displays 10a and 10b, the arrangement and size of the pixel region A1 can be appropriately changed within the range where there is a sufficient light-transmitting region A2.

[0080] The virtual image display device or the optical unit in the specific embodiment includes, in order from the outside world: a display that has a pixel region that emits image light as circularly polarized light and allows part of the external light to pass through; a first optical component whose display side is flat and which has a semi-transmissive reflective optical surface with a refractive power inside; a wavelength plate that converts the polarization state of the image light that has passed through the first optical component into linearly polarized light or circularly polarized light; and a second optical component that includes a polarization reflection layer that reflects the image light that has passed through the wavelength plate, and the imaging optical system formed by combining the first optical component, the wavelength plate, and the second optical component has substantially no refractive power with respect to the polarization component of the external light that has passed through the light-transmitting region of the display.

[0081] In the above virtual image display device, image light that has passed through the reflective optical surface and is circularly polarized light, for example, passes through a quarter-wave plate, thereby becoming linearly polarized light and being reflected by the polarization reflective layer. It passes through the wavelength plate again, thereby becoming the original circularly polarized light and being partially reflected by the reflective optical surface. The image light reflected by the reflective optical surface becomes circularly polarized light with the opposite sense of rotation, passes through the above-mentioned quarter-wave plate, thereby becoming linearly polarized light in the cross direction and passing through the polarization reflective layer. That is to say, the divergence state of the image light is adjusted in two stages through reflection by the reflective optical surface and the polarization reflective layer, and the image formed on the display surface of the display can be observed as a high-precision virtual image. In addition, image light that has passed through the reflective optical surface and is circularly polarized light, for example, passes through a half-wave plate, thereby becoming circularly polarized light with the opposite sense of rotation and being reflected by the polarization reflective layer. It passes through the wavelength plate again, thereby becoming the original circularly polarized light and being partially reflected by the reflective optical surface. The image light reflected by the reflective optical surface becomes circularly polarized light with the opposite sense of rotation, passes through the above-mentioned half-wave plate, thereby becoming the original circularly polarized light and passing through the polarization reflective layer. That is to say, the divergence state of the image light is adjusted in two stages through reflection by the reflective optical surface and the polarization reflective layer, and the image formed on the display surface of the display can be observed as a high-precision virtual image. In addition, ambient light contains random polarization components, and when passing through the display, the reflective optical surface, and passing through the wavelength plate, it becomes linearly polarized light in the cross direction and circularly polarized light with the opposite sense of rotation and passes through the polarization reflective layer. At this time, the ambient light passes through the imaging optical system substantially without being affected by the lens action of the first optical component, the wavelength plate, and the second optical component. That is to say, it is possible to perform perspective observation of the external image through the imaging optical system.

[0082] In a virtual image display device in a specific embodiment, the thickness of the imaging optical system from the first optical component to the second optical component is 7 mm or less. By setting the thickness of the imaging optical system to 7 mm or less, the virtual image display device or the optical unit can be made lighter. At this time, the divergence state is adjusted with high precision through reflection by the reflective optical surface and the polarization reflective layer, so the resolution can be improved and color unevenness can be reduced.

[0083] In a virtual image display device in a specific embodiment, the reflective optical surface is a continuous curved surface, and the first optical component has a first lens element and a second lens element joined with the reflective optical surface interposed therebetween. In this case, the first optical component becomes an optical component in the form of a parallel flat plate as a whole and having a continuous reflective optical surface embedded therein.

[0084] In a virtual image display device in a specific embodiment, the reflective optical surface is a Fresnel optical surface, and the first optical component has a first lens element and a second lens element joined with the reflective optical surface interposed therebetween. In this case, the first optical component is in the form of a parallel flat plate as a whole and has a Fresnel optical surface embedded therein.

[0085] In the virtual image display device of a specific embodiment, the polarization reflection layer is a continuous curved surface, and the first optical component has a third lens element and a fourth lens element joined with the polarization reflection layer interposed therebetween. In this case, the second optical component is an optical component such as a cemented lens that is entirely in the shape of a parallel plate and has a continuous polarization reflection layer embedded therein.

[0086] In the virtual image display device of a specific embodiment, the wavelength plate is a quarter-wave plate, and the polarization reflection layer is a reflective polarizer. That is, the image light, which is circularly polarized light that has passed through the reflective optical surface, passes through the quarter-wave plate, thereby becoming linearly polarized light and being reflected by the polarization reflection layer. It then passes through the wavelength plate again and becomes the original circularly polarized light, and is partially reflected by the reflective optical surface. The image light reflected by the reflective optical surface becomes circularly polarized light with the opposite sense of rotation, passes through the above-described quarter-wave plate, thereby becoming linearly polarized light in the cross direction and passing through the polarization reflection layer.

[0087] In the virtual image display device of a specific embodiment, the wavelength plate is a half-wave plate, and the polarization reflection layer is a cholesteric liquid crystal layer. That is, the image light, which is circularly polarized light that has passed through the reflective optical surface, passes through the half-wave plate, thereby becoming circularly polarized light with the opposite sense of rotation and being reflected by the polarization reflection layer. It then passes through the wavelength plate again, thereby becoming the original circularly polarized light, and is partially reflected by the reflective optical surface. The image light reflected by the reflective optical surface becomes circularly polarized light with the opposite sense of rotation, passes through the above-described half-wave plate, thereby becoming the original circularly polarized light and passing through the polarization reflection layer.

[0088] In the virtual image display device of a specific embodiment, the above-described cholesteric liquid crystal layer is formed on a plane.

[0089] In the virtual image display device of a specific embodiment, the above-described cholesteric liquid crystal layer is formed by stabilizing a liquid crystal material.

[0090] In the virtual image display device in a specific embodiment, the display independently has a pixel region that obstructs the transmission of external light and a light-transmitting region that is transparent to external light. The external light enters the imaging optical system through the light-transmitting region without being affected by the pixel region and also passes through the imaging optical system.

Claims

1. A virtual image display device, which sequentially includes from the outside: A display having a pixel region that emits image light as circularly polarized light and partially transmits external light; A first optical component, the display side of the first optical component being planar, the first optical component having a semi-transmissive reflective optical surface inside, the reflective optical surface having a refractive power; A wavelength plate that converts the polarization state of the image light that has passed through the first optical component into linearly polarized light or circularly polarized light; and A second optical component that includes a polarization reflection layer that reflects the image light that has passed through the wavelength plate, The imaging optical system formed by combining the first optical component, the wavelength plate, and the second optical component has substantially no refractive power with respect to the polarization component of the external light that has passed through the light-transmitting region of the display.

2. The virtual image display device according to claim 1, wherein The thickness of the imaging optical system from the first optical component to the second optical component is 7 mm or less.

3. The virtual image display device according to claim 1, wherein The reflective optical surface is a continuous curved surface, The first optical component has a first lens element and a second lens element joined with the reflective optical surface interposed therebetween.

4. The virtual image display device according to claim 1, wherein The reflective optical surface is a Fresnel optical surface, The first optical component has a first lens element and a second lens element joined with the reflective optical surface interposed therebetween.

5. The virtual image display device according to claim 1, wherein The polarization reflection layer is a continuous curved surface, The first optical component has a third lens element and a fourth lens element joined with the polarization reflection layer interposed therebetween.

6. The virtual image display device according to claim 1, wherein The wavelength plate is a quarter-wave plate, The polarization reflection layer is a reflective polarizer.

7. The virtual image display device according to claim 1, wherein The wavelength plate is a half-wave plate, The polarization reflection layer is a cholesteric liquid crystal layer.

8. The virtual image display device according to claim 7, wherein The cholesteric liquid crystal layer is formed on a plane.

9. The virtual image display device according to claim 7, wherein The cholesteric liquid crystal layer is formed by stabilizing a liquid crystal material.

10. The virtual image display device according to claim 1, wherein The display independently has the pixel region that obstructs the transmission of the external light and the light-transmitting region that is transparent to the external light.

11. An optical unit, which sequentially includes from the outside: A display having a pixel region that emits image light as circularly polarized light and partially transmits external light; A first optical component, the display side of the first optical component being planar, the first optical component having a semi-transmissive reflective optical surface inside, the reflective optical surface having a refractive power; A wavelength plate that converts the polarization state of the image light that has passed through the first optical component into linearly polarized light or circularly polarized light; and A second optical component that includes a polarization reflection layer that reflects the image light that has passed through the wavelength plate, The imaging optical system formed by combining the first optical component, the wavelength plate, and the second optical component has substantially no refractive power with respect to the polarization component of external light that has passed through the light-transmitting region of the display.

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