Optical devices and head-mounted displays

Abstract

Miniaturize optical devices. [Solution] The device comprises a first reflective polarizing layer and a second reflective polarizing layer, a half-mirror located between the first reflective polarizing layer and the second reflective polarizing layer, a first lens located between the first reflective polarizing layer and the half-mirror, and a second lens located between the second reflective polarizing layer and the half-mirror, wherein the first and second lenses are plano-convex lenses, the first reflective polarizing layer is arranged along the convex surface of the first lens, the second reflective polarizing layer is arranged along the convex surface of the second lens, the first reflective polarizing layer transmits first polarized light and reflects second polarized light, and the second reflective polarizing layer reflects one of the first and second polarized light and transmits the other.

Description

Technical Field

[0001] The present disclosure relates to an optical device and a head-mounted display.

Background Art

[0002] Patent Document 1 discloses an optical element having, in this order, a first absorption-type linear polarizer, a first reflection-type linear polarizer, a first retardation plate, a partial reflection mirror, a second retardation plate, and a second reflection-type linear polarizer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the optical element disclosed in Patent Document 1, miniaturization is difficult because the optical system becomes long.

Means for Solving the Problems

[0005] An optical device according to an aspect of the present disclosure includes a first reflective polarizing layer and a second reflective polarizing layer, a half mirror positioned between the first reflective polarizing layer and the second reflective polarizing layer, a first lens positioned between the first reflective polarizing layer and the half mirror, and a second lens positioned between the second reflective polarizing layer and the half mirror. The first lens is a plano-convex lens having a plane surface on the side closer to the half mirror, the second lens is a plano-convex lens having a plane surface on the side closer to the half mirror, the first reflective polarizing layer is disposed along the convex surface of the first lens, the second reflective polarizing layer is disposed along the convex surface of the second lens, the first reflective polarizing layer transmits a first polarization and reflects a second polarization, and the second reflective polarizing layer reflects one of the first polarization and the second polarization and transmits the other. [Effects of the Invention]

[0006] According to one aspect of this disclosure, a compact optical device can be realized. [Brief explanation of the drawing]

[0007] [Figure 1] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 2] This is a schematic diagram showing the two optical paths (double path) of the optical device in Figure 1. [Figure 3] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 4] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 5] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 6] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 7] Figure 6 is a schematic diagram showing the two optical paths (double path) of the optical device. [Figure 8] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 9] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 10] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 11] This is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. [Figure 12] Figure 11 is a schematic diagram showing the two optical paths (double path) of the optical device. [Figure 13] This is a flowchart showing an example of a method for manufacturing an optical device. [Figure 14] This is a cross-sectional view showing an example of a method for manufacturing an optical device. [Figure 15] This is a cross-sectional view showing an example of a method for manufacturing an optical device. [Figure 16]This table shows the relationship between the adhesion accuracy of the reflective polarizing layer and the combination of the thickness of the reflective polarizing layer and the radius of curvature of the lens convex surface. [Figure 17] This is a cross-sectional view showing the total thickness from the display device to the convex surface of the second lens. [Figure 18] This graph shows the relationship between the radius of curvature of a lens convex surface and its total thickness. [Figure 19] This is a side view showing an example configuration of a head-mounted display according to this embodiment. [Modes for carrying out the invention]

[0008] Figure 1 is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. The optical device 10 shown in Figure 1 comprises a first reflective polarizing layer P1 and a second reflective polarizing layer P2, a half mirror HM, a first lens Z1, and a second lens Z2. The half mirror HM is located between the first reflective polarizing layer P1 and the second reflective polarizing layer P2. The first lens Z1 is located between the first reflective polarizing layer P1 and the half mirror HM. The second lens Z2 is located between the second reflective polarizing layer P2 and the half mirror HM. The optical device 10 is located between the display device D and the observer U, and the first reflective polarizing layer P1, the first lens Z1, the half mirror HM, the second lens Z2, and the second reflective polarizing layer P2 are located in this order from the display device D toward the observer U. The half mirror HM is an optical element that has the characteristic of reflecting a portion of the incident light and transmitting the other portion.

[0009] The first lens Z1 is a plano-convex lens in which the surface closer to the half-mirror HM is a flat surface F1 and the surface further away from the half-mirror HM (the surface closer to the display device D) is a convex surface T1. The second lens Z2 is a plano-convex lens in which the surface closer to the half-mirror HM is a flat surface F2 and the surface further away from the half-mirror HM (the surface closer to the observer U) is a convex surface T2. The convex surfaces T1 and T2 may be curved surfaces.

[0010] The first reflective polarizing layer P1 is arranged along the convex surface T1 of the first lens Z1. The second reflective polarizing layer P2 is arranged along the convex surface T2 of the second lens Z2. The first reflective polarizing layer P1 and the convex surface T1 may be in contact or separated. The second reflective polarizing layer P2 and the convex surface T2 may be in contact or separated.

[0011] The first reflective polarizing layer P1 transmits the first polarization and reflects the second polarization. The second reflective polarizing layer P2 reflects one of the first polarization and the second polarization and transmits the other.

[0012] The optical device 10 in FIG. 1 includes first and second lenses Z1 and Z2 that are plano-convex lenses, a half mirror HM positioned between the first and second lenses Z1 and Z2, a first reflective polarizing layer P1 arranged along the convex surface T1 of the first lens Z1, and a second reflective polarizing layer P2 arranged along the convex surface T2 of the second lens Z2. Thereby, while increasing the light extraction efficiency, the optical path can be shortened, and the optical device 10 can be miniaturized.

[0013] In FIG. 1, at least one of the first and second reflective polarizing layers P1 and P2 may include a cholesteric liquid crystal layer. At least one of the first and second reflective polarizing layers P1 and P2 may be a cholesteric liquid crystal layer, and each of the first and second reflective polarizing layers P1 and P2 may be a cholesteric liquid crystal layer. The cholesteric liquid crystal layer has the property of reflecting circularly polarized light while maintaining its rotation direction.

[0014] At least one of the first reflective polarizing layer P1 and the second reflective polarizing layer P2 may be a single-layer reflective polarizing film having both functions of polarizing reflection and polarizing transmission. The first reflective polarizing layer P1 may be a single-layer reflective polarizing film adhered to the convex surface T1 via an adhesive layer (bonding layer) not shown, and the second reflective polarizing layer P2 may be a single-layer reflective polarizing film adhered to the convex surface T2 via an adhesive layer (bonding layer) not shown (the adhesive layer will be described later). The single-layer reflective polarizing film may be a cholesteric liquid crystal layer.

[0015] The thickness of at least one of the first reflective polarizing layer P1 and the second reflective polarizing layer P2 may be 50 μm or less, or the thickness of each of the first reflective polarizing layer P1 and the second reflective polarizing layer P2 may be 50 μm or less. In this way, even if the radius of curvature of the convex surfaces T1 and T2 is reduced, the first and second reflective polarizing layers P1 and P2 will not peel off easily, and further miniaturization of the optical device 10 will be possible.

[0016] For example, by using cholesteric liquid crystal layers for the first and second reflective polarizing layers P1 and P2, the first and second reflective polarizing layers P1 and P2 can be formed thinly (50 μm or less, 20 μm or less, or 10 μm or less), and the first and second reflective polarizing layers P1 and P2 become less likely to peel off even if the radius of curvature of the convex surfaces T1 and T2 is reduced. The cholesteric liquid crystal layer may also be included in the reflective polarizing film.

[0017] As shown in Figure 1, cost reduction can be achieved by bringing the symmetrically arranged first and second lenses Z1 and Z2 into close contact via a half-mirror HM. However, since the contact between the lenses inherently results in insufficient lens power, it is desirable to reduce the radius of curvature of the convex surfaces T1 and T2. For this reason, it is desirable to apply cholesteric liquid crystal layers (cholesteric liquid crystal films) that can be supplied in film form with a thickness of several micrometers to tens of micrometers, rather than general reflective polarizing plates with a thickness exceeding 50 μm, to the first and second reflective polarizing layers P1 and P2.

[0018] As shown in Figure 1, the first reflective polarization layer P1 may be closer to the display device D than the second reflective polarization layer P2. The optical device 10 may include a 1 / 4λ layer Q1 (e.g., a quarter-wave plate) that is closer to the display device D than the first reflective polarization layer P1. The optical device 10 may also include a 1 / 4λ layer Q2 (e.g., a quarter-wave plate) that is closer to the observer U than the second reflective polarization layer P2.

[0019] In the optical device 10, the 1 / 4λ layer Q1, the first reflective polarizing layer P1, the first lens Z1, the half mirror HM, the second lens Z2, the second reflective polarizing layer P2, and the 1 / 2λ layer may be positioned in this order from the display device D side. The optical device 10 may include a polarizing material PA (polarizing film, polarizing plate, etc.) located between the 1 / 4λ layer Q2 and the observer U. The polarizing material PA may have the characteristic of absorbing polarized light other than that emitted from the 1 / 4λ layer Q2.

[0020] The half mirror HM may be in contact with the first lens Z1 and the second lens Z2. For example, the plane F1 of the first lens Z1 and the plane F2 of the second lens Z2 may be in contact with the half mirror HM. The first and second lenses Z1 and Z2 may be arranged symmetrically with respect to the half mirror HM. For example, the first and second lenses Z1 and Z2 may be the same plano-convex lens, and the distance between the half mirror HM and the convex surface T1 may be equal to the distance between the half mirror HM and the convex surface T2.

[0021] In the optical device 10 shown in Figure 1, the first reflective polarizing layer P1 transmits the first polarized light and reflects the second polarized light, and the second reflective polarizing layer P2 reflects the first polarized light and transmits the second polarized light. One of the first and second polarized lights may be left-circularly polarized (counterclockwise circular polarization), and the other may be right-circularly polarized (clockwise circular polarization), and the direction of rotation of the circularly polarized light may be maintained in the reflection by the first reflective polarizing layer P1 and the second reflective polarizing layer P2, respectively.

[0022] Figure 2 is a schematic diagram showing the two optical paths (double path) of the optical device in Figure 1. In Figure 2, the first reflective polarization layer P1 transmits left-circularly polarized light (first polarization) and reflects right-circularly polarized light (second polarization), while the second reflective polarization layer P2 reflects left-circularly polarized light (first polarization) and transmits right-circularly polarized light (second polarization).

[0023] The first path 1 when vertically polarized light V is emitted from the display device D is as follows: The vertically polarized light V from the display device D becomes left-circularly polarized light L by the 1 / 4λ layer Q1, the left-circularly polarized light L passes through the first reflection polarization layer P1 and is reflected by the half mirror HM to become right-circularly polarized light R. The right-circularly polarized light reflected by the half mirror HM is reflected by the first reflection polarization layer P1 (maintaining right-circular polarization). The right-circularly polarized light R reflected by the first reflection polarization layer P1 passes through the half mirror HM and the second reflection polarization layer P2 and becomes vertically polarized light V by the 1 / 4λ layer Q2, and the vertically polarized light V passes through the polarizing material PA and reaches the observer U.

[0024] The second path 2 when vertically polarized light V is emitted from the display device D is as follows: The vertically polarized light V from the display device D becomes left-circularly polarized light L by the 1 / 4λ layer Q1, the left-circularly polarized light L passes through the first reflection polarization layer P1 and the half mirror HM, and is reflected by the second reflection polarization layer P2 (maintaining left-circular polarization). The left-circularly polarized light reflected by the second reflection polarization layer P2 is reflected by the half mirror HM and becomes right-circularly polarized light R. The right-circularly polarized light R reflected by the half mirror HM passes through the second reflection polarization layer P2 and becomes vertically polarized light V by the 1 / 4λ layer Q2, and the vertically polarized light V passes through the polarizing material PA and reaches the observer U.

[0025] In the optical device 10, light emitted from the display device D and reflected by the half-mirror HM and the first reflective polarization layer P1 toward the observer U (light passing through the first path 1) is superimposed on light emitted from the display device D and reflected by the second reflective polarization layer P2 and the half-mirror HM toward the observer U (light passing through the second path 2). This makes it possible to shorten the optical path while increasing the efficiency of light extraction.

[0026] Figure 2 illustrates the case where vertically polarized light is emitted from the display device D, but it is not limited to this. If horizontally polarized light is emitted from the display device D, the first and second reflective polarization layers P1 and P2 can be swapped, with the second reflective polarization layer P2 (which reflects left-circularly polarized light and transmits right-circularly polarized light) positioned on the display device D side and the first reflective polarization layer P1 (which transmits left-circularly polarized light and reflects right-circularly polarized light) positioned on the observer U side. The display device D may be a liquid crystal display device, or it may be a self-emissive display device including, for example, a light-emitting diode (organic LED, inorganic crystal LED, quantum dot LED, etc.).

[0027] Figure 3 is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. As shown in Figure 3, in the optical device 10, PVH layers may be used for both the first reflective polarizing layer P1 (for example, which transmits left circularly polarized light and reflects right circularly polarized light) and the second reflective polarizing layer P2 (for example, which reflects left circularly polarized light and transmits right circularly polarized light). The PVH layer has a structure in which a cholesteric liquid crystal layer is arranged on an alignment film having a periodic pattern due to optical alignment, and has the function of a concave mirror in addition to the function of non-axial reflection. This concave mirror function can increase the design freedom by one plane.

[0028] Figure 4 is a cross-sectional view showing an example of the configuration of the optical device according to this embodiment. As shown in Figure 4, the optical device 10 may include a third lens Z3 that is closer to the observer U than the second reflection polarization layer P2. The third lens Z3 may be positioned between the second reflection polarization layer P2 and the 1 / 4λ layer Q2. The third lens Z3 may be positioned between the 1 / 4λ layer Q2 and the polarizing material PA. The third lens Z3 may be a diffractive lens, and this diffractive lens may be a PB (Pantharatnam Berry) lens. For PB lenses, by forming a non-uniform pattern period, it is possible to give it a function equivalent to an aspherical lens. In addition, an additional lens may be superimposed on the third lens Z3.

[0029] Figure 5 is a cross-sectional view showing an example of the configuration of the optical device according to this embodiment. As shown in Figure 5, the optical device 10 includes a third lens Z3 that is closer to the observer U than the second reflective polarizing layer P2, and the third lens Z3 may be positioned between the polarizing material PA and the observer U. The third lens Z3 may be a plano-convex lens in which the surface closer to the half mirror HM is flat and the surface closer to the observer U is convex.

[0030] Figure 6 is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. The optical device 10 shown in Figure 6 comprises a first reflective polarizing layer P1 and a second reflective polarizing layer P2, a half mirror HM, a first lens Z1, and a second lens Z2. The half mirror HM is located between the first reflective polarizing layer P1 and the second reflective polarizing layer P2. The first lens Z1 is located between the first reflective polarizing layer P1 and the half mirror HM. The second lens Z2 is located between the second reflective polarizing layer P2 and the half mirror HM. The optical device 10 is located between the display device D and the observer U, and the first reflective polarizing layer P1, the first lens Z1, the half mirror HM, the second lens Z2, and the second reflective polarizing layer P2 are located in this order from the display device D toward the observer U.

[0031] The first lens Z1 is a plano-convex lens in which the surface closer to the half-mirror HM is a flat surface F1 and the surface further away from the half-mirror HM (the surface closer to the display device D) is a convex surface T1. The second lens Z2 is a plano-convex lens in which the surface closer to the half-mirror HM is a flat surface F2 and the surface further away from the half-mirror HM (the surface closer to the observer U) is a convex surface T2.

[0032] The first reflective polarizing layer P1 is positioned along the convex surface T1 of the first lens Z1. The second reflective polarizing layer P2 is positioned along the convex surface T2 of the second lens Z2. The first reflective polarizing layer P1 and the convex surface T1 may be in contact or separated. The second reflective polarizing layer P2 and the convex surface T2 may be in contact or separated.

[0033] The optical device 10 in Figure 6 includes first and second lenses Z1 and Z2, which are plano-convex lenses; a half-mirror HM located between the first and second lenses Z1 and Z2; a first reflective polarizing layer P1 arranged along the convex surface T1 of the first lens Z1; and a second reflective polarizing layer P2 arranged along the convex surface T2 of the second lens Z2. This allows for an increased efficiency in light extraction while shortening the optical path, enabling miniaturization of the optical device 10.

[0034] At least one of the first and second reflective polarizing layers P1 and P2 may be a wire grid layer, or each of the first and second reflective polarizing layers P1 and P2 may be a wire grid layer. The wire grid layer can be formed by microfabrication of a metal layer (e.g., dry etching). The wire grid layer has the property of reflecting linearly polarized light while maintaining its polarization direction.

[0035] The optical device 10 in Figure 6 may include a 1 / 4λ layer QX (e.g., a quarter-wave plate) located between the half-mirror HM and the first lens Z1, and a 1 / 4λ layer QY located between the half-mirror HM and the second lens Z2.

[0036] In the optical device 10, the first reflective polarizing layer P1, the first lens Z1, the 1 / 4λ layer QX, the half mirror HM, the 1 / 4λ layer QY, the second lens Z2, and the second reflective polarizing layer P2 may be positioned in this order from the display device D side. The optical device 10 may include a polarizing material PA (polarizing film, polarizing plate, etc.) located between the second reflective polarizing layer P2 and the observer U. The polarizing material PA may have the property of absorbing polarized light other than that emitted from the second reflective polarizing layer P2.

[0037] In the optical device 10 of Figure 6, the first reflective polarization layer P1 may transmit the first polarization and reflect the second polarization, and the second reflective polarization layer P2 may reflect the first polarization and transmit the second polarization. One of the first and second polarizations may be vertically polarized and the other horizontally polarized, and the polarization direction may be maintained in the reflection by the first reflective polarization layer P1 and the second reflective polarization layer P2, respectively.

[0038] Figure 7 is a schematic diagram showing the two optical paths (double path) of the optical device in Figure 6. In Figure 7, the first reflective polarization layer P1 transmits vertically polarized light (first polarization) and reflects horizontally polarized light (second polarization), while the second reflective polarization layer P2 reflects vertically polarized light (first polarization) and transmits horizontally polarized light (second polarization).

[0039] The first path 11 when vertically polarized light V is emitted from the display device D is as follows: The vertically polarized light V from the display device D passes through the first reflection polarization layer P1 and becomes left-circularly polarized light L by the 1 / 4λ layer QX. The left-circularly polarized light L is reflected by the half mirror HM and becomes right-circularly polarized light R. The right-circularly polarized light R reflected by the half mirror HM becomes horizontally polarized light H by the 1 / 4λ layer QX and is reflected by the first reflection polarization layer P1. The horizontally polarized light H reflected by the first reflection polarization layer P1 becomes right-circularly polarized light R by the 1 / 4λ layer QX. The right-circularly polarized light R passes through the half mirror HM and becomes horizontally polarized light H by the 1 / 4λ layer QY. The horizontally polarized light H passes through the second reflection polarization layer P2 and the polarizing material PA and reaches the observer U.

[0040] The second path 12 when vertically polarized light V is emitted from the display device D is as follows: The vertically polarized light V from the display device D passes through the first reflection polarization layer P1 and becomes left circularly polarized light L by the 1 / 4λ layer QX. The left circularly polarized light L passes through the half mirror HM and becomes vertically polarized light V by the 1 / 4λ layer QY, and is reflected by the second reflection polarization layer P2. The vertically polarized light V reflected by the second reflection polarization layer P2 becomes left circularly polarized light L by the 1 / 4λ layer QY. The left circularly polarized light L is reflected by the half mirror HM and becomes right circularly polarized light R. The right circularly polarized light R reflected by the half mirror HM becomes horizontally polarized light H by the 1 / 4λ layer QY. The horizontally polarized light H passes through the second reflection polarization layer P2 and the polarizing material PA and reaches the observer U.

[0041] In the optical device 10 shown in Figure 6, light emitted from the display device D and reflected by the half-mirror HM and the first reflective polarization layer P1 toward the observer U (light passing through the first path 11) is superimposed on light emitted from the display device D and reflected by the second reflective polarization layer P2 and the half-mirror HM toward the observer U (light passing through the second path 12). This allows for a shorter optical path while increasing the efficiency of light extraction.

[0042] Figure 8 is a cross-sectional view showing an example of the configuration of the optical device according to this embodiment. As shown in Figure 8, the optical device 10 may include a third lens Z3 that is closer to the observer U than the second reflective polarizing layer P2. A 1 / 4λ layer QA may be placed between the third lens Z3 and the polarizing material PA, and the third lens Z3 may be placed between the second reflective polarizing layer P2 and the 1 / 4λ layer QA. The third lens Z3 may be a diffractive lens, and this diffractive lens may be a PB (Pantharatnam Berry) lens.

[0043] Figure 9 is a cross-sectional view showing an example of the configuration of the optical device according to this embodiment. As shown in Figure 9, the optical device 10 includes a third lens Z3 that is closer to the observer U than the second reflective polarizing layer P2, and the third lens Z3 may be positioned between the polarizing material PA and the observer U. The third lens Z3 may be a plano-convex lens in which the surface closer to the half mirror HM is flat and the surface closer to the observer U is convex.

[0044] Figure 10 is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. As shown in Figure 10, in the optical device 10, a 1 / 4λ layer QX may be placed between the first lens Z1 and the first reflective polarizing layer P1, and a 1 / 4λ layer QY may be placed between the second lens Z2 and the second reflective polarizing layer P2. For example, from the display device D side, the first reflective polarizing layer P1, 1 / 4λ layer QX, first lens Z1, half mirror HM, second lens Z2, 1 / 4λ layer QY, and second reflective polarizing layer P2 are arranged in this order. In this case, the 1 / 4λ layer QX is arranged along the convex surface T1 of the first lens Z1, and the first reflective polarizing layer P1 is arranged to follow the convex surface T1 via the 1 / 4λ layer QX. Also, the 1 / 4λ layer QY is arranged along the convex surface T2 of the second lens Z2, and the second reflective polarizing layer P2 is arranged to follow the convex surface T2 via the 1 / 4λ layer QY. In Figure 10, a 1 / 4λ layer QX may be applied to the convex surface T1, and a 1 / 4λ layer QY may be applied to the convex surface T2.

[0045] Figure 11 is a cross-sectional view showing an example of the configuration of an optical device according to this embodiment. The optical device 10 shown in Figure 11 includes a 1 / 2λ layer (e.g., a half-wavelength layer, half-wavelength film, half-wavelength plate) located between the first reflective polarizing layer P1 and the half-mirror HM. In the optical device 10 of Figure 11, the 1 / 4λ layer Q1, the first reflective polarizing layer P1, the first lens Z1, the 1 / 2λ layer HX, the half-mirror HM, the second lens Z2, the second reflective polarizing layer P2, and the 1 / 4λ layer Q2 are located in this order from the display device D side. The 1 / 2λ layer may be located between the first reflective polarizing layer P1 and the first lens Z1. In Figure 11, at least one of the first and second reflective polarizing layers P1 and P2 may include a cholesteric liquid crystal layer. At least one of the first and second reflective polarizing layers P1 and P2 may be a cholesteric liquid crystal layer, and each of the first and second reflective polarizing layers P1 and P2 may be a cholesteric liquid crystal layer. The cholesteric liquid crystal layer has the property of reflecting circularly polarized light while maintaining its direction of rotation.

[0046] Figure 12 is a schematic diagram showing the two optical paths (double path) of the optical device in Figure 11. In Figure 12, the first and second reflective polarization layers P1 and P2 have the same optical properties. For example, the first and second reflective polarization layers P1 each transmit left-circularly polarized light (first polarization) and reflect right-circularly polarized light (second polarization).

[0047] The first path 21 when vertically polarized light V is emitted from the display device D is as follows: The vertically polarized light V from the display device D becomes left-circularly polarized light L by the 1 / 4λ layer Q1, and this left-circularly polarized light L is transmitted through the first reflection polarization layer P1 and becomes right-circularly polarized light by the 1 / 2λ layer HX. The right-circularly polarized light from the 1 / 2λ layer HX is reflected by the half mirror HM and becomes left-circularly polarized light L. The left-circularly polarized light L reflected by the half mirror HM becomes right-circularly polarized light by the 1 / 2λ layer HX, and this right-circularly polarized light is reflected by the first reflection polarization layer P1 (maintaining right-circular polarization). The right-circularly polarized light R reflected by the first reflection polarization layer P1 becomes left-circularly polarized light L by the 1 / 2λ layer HX, and this left-circularly polarized light L is transmitted through the half mirror HM and the second reflection polarization layer P2, and becomes vertically polarized light V by the 1 / 4λ layer Q2, and the vertically polarized light V is transmitted through the polarizing material PA and reaches the observer U. The second path 22 when vertically polarized light V is emitted from the display device D is as follows: The vertically polarized light V from the display device D becomes left-circularly polarized light L by the 1 / 4λ layer Q1, and this left-circularly polarized light L passes through the first reflection polarization layer P1 and becomes right-circularly polarized light by the 1 / 2λ layer HX. The right-circularly polarized light from the 1 / 2λ layer HX passes through the half mirror HM and is reflected by the second reflection polarization layer P2 (maintaining right-circular polarization). The right-circularly polarized light R reflected by the second reflection polarization layer P2 is reflected by the half mirror HM and becomes left-circularly polarized light L. The left-circularly polarized light L reflected by the half mirror HM passes through the second reflection polarization layer P2 and becomes vertically polarized light V by the 1 / 4λ layer Q2, and the vertically polarized light V passes through the polarizing material PA and reaches the observer U.

[0048] In the optical device 10 shown in Figure 11, light emitted from the display device D and reflected by the half-mirror HM and the first reflective polarization layer P1 toward the observer U (light passing through the first path 21) is superimposed with light emitted from the display device D and reflected by the second reflective polarization layer P2 and the half-mirror HM toward the observer U (light passing through the second path 22). This allows for a shorter optical path while increasing the efficiency of light extraction. Figure 13 is a flowchart showing an example of a method for manufacturing an optical device according to this embodiment. Figures 14 and 15 are cross-sectional views showing an example of a method for manufacturing an optical device according to this embodiment. As shown in Figures 13 and 14, the method for manufacturing an optical device includes a step S10 of preparing a reflective polarizing film PF (including a base material KS and a first reflective polarizing layer P1), a step S20 of adhering the first reflective polarizing layer P1 to a target convex surface T1 via an adhesive layer C1, and a step S30 of removing the base material KS from the reflective polarizing film PF (Figure 14). As shown in Figure 15, the method may also include a step of preparing a reflective polarizing film PF (including a base material KS and a second reflective polarizing layer P2), a step of adhering the second reflective polarizing layer P2 to a target convex surface T2 via an adhesive layer C2, and a step of removing the base material KS from the reflective polarizing film PF.

[0049] As shown in Figures 14 and 15, the first reflective polarizing layer P1 is bonded to the convex surface T1 of the first lens via the first adhesive layer C1, and the second reflective polarizing layer P2 is bonded to the convex surface T2 of the second lens via the second adhesive layer C2. The thickness of the first and second adhesive layers C1 and C2 may be 25 μm or more.

[0050] In the reflective polarizing film PF, the substrate KS may be arranged on one side or on both sides. The first reflective polarizing layer P1 may be a cholesteric liquid crystal layer (polarization controllable liquid crystal layer) or a wire grid layer (polarization controllable metal layer). The thickness of the cholesteric liquid crystal layer may be 2 μm or more and 5 μm or less. The thickness of the wire grid layer may be 2 μm or more and 5 μm or less. The thickness of the substrate KS may be 50 μm or more and 200 μm or less.

[0051] The first reflective polarizing layer P1 may be monolithically formed on the convex surface T1. If the first reflective polarizing layer P1 is a cholesteric liquid crystal layer, for example, monolithic formation of the first reflective polarizing layer P1 is possible by coating the convex surface T1 with a polyimide film and then UV curing the cholesteric liquid crystal applied on the polyimide film. If the first reflective polarizing layer P1 is a wire grid layer, for example, the wire grid layer can be monolithically formed on the convex surface T1 using a nanoimprint stamper on the convex surface T1.

[0052] Figure 16 is a table showing the relationship between the adhesion accuracy of the reflective polarizing layer and the combination of the thickness of the reflective polarizing layer and the radius of curvature of the lens convex surface. Figure 17 is a cross-sectional view showing the total thickness from the display device to the convex surface of the second lens. Figure 18 is a graph showing the relationship between the radius of curvature of the lens convex surface and the total thickness. The definitions of "good," "slightly poor," and "poor" in Figure 16 are as follows: "Good": The reflective polarizing layer does not detach naturally from the convex surface. "Slightly poor": The reflective polarizing layer detaches naturally from the convex surface after about one day. "Poor": The reflective polarizing layer detaches naturally from the convex surface immediately. In Figures 16 to 18, the material of the plano-convex lenses (Z1 and Z2) is PMMA (polymethyl methacrylate), and the refractive index of PMMA is 1.49.

[0053] Figures 16 to 18 show that thinning the reflective polarizing layer (P1 and P2) is effective in improving adhesion accuracy. When the reflective polarizing layer (P1 and P2) is aligned with the convex surface (T1 and T2), it is preferable that the tensile and compressive stresses acting within the plane of the reflective polarizing layer are made uniform. For this reason, the thickness of the adhesive layer (C1 and C2) is preferably 25 μm or more. Furthermore, heating at least one of the reflective polarizing layer and the convex surface during the process of aligning the reflective polarizing layer with the convex surface is also effective.

[0054] According to Figure 16, if the radius of curvature of the convex surface is 120 mm, the reflective polarizing layer will not detach naturally from the convex surface if its thickness is 50 μm or less. If the radius of curvature of the convex surface is 80 mm, the reflective polarizing layer will not detach naturally from the convex surface if its thickness is 25 μm or less. If the radius of curvature of the convex surface is 40 mm, the reflective polarizing layer will not detach naturally from the convex surface if its thickness is 5 μm or less. From the above, it is preferable that the thickness of the reflective polarizing layer (P1·P2) is 50 μm or less, 25 μm or less, and more preferably 5 μm or less.

[0055] Regarding Figures 17 and 18, in order to achieve a total thickness of 40 mm or less with the Fresnel lens system, the radius of curvature of the convex surface should be 160 mm or less. That is, it is preferable that the radius of curvature of at least one of the convex surfaces of the first lens Z1 and the second lens Z2, which are plano-convex lenses, be 160 mm or less. Lens materials such as PMMA tend to turn yellow due to the absorption of blue light. If the radius of curvature of the convex surface is less than 40 mm, the thickness of the plano-convex lens may be too large, which may cause the image to have a yellowish tint or adversely affect optical aberrations. For this reason, it is preferable that the radius of curvature of at least one of the convex surfaces of the first lens Z1 and the second lens Z2 be 40 mm or more.

[0056] Figure 19 is a schematic cross-section showing an example configuration of a head-mounted display according to this embodiment. As shown in Figure 19, the head-mounted display 20 may include an optical device 10, a display device D, and a mounting part B that is attached to the head of an observer U while holding the optical device 10 and the display device D.

[0057] 〔summary〕 An optical apparatus according to Embodiment 1 of the present disclosure comprises a first reflective polarizing layer and a second reflective polarizing layer, a half-mirror located between the first reflective polarizing layer and the second reflective polarizing layer, a first lens located between the first reflective polarizing layer and the half-mirror, and a second lens located between the second reflective polarizing layer and the half-mirror, wherein the first lens is a plano-convex lens with a flat surface on the side closest to the half-mirror, the second lens is a plano-convex lens with a flat surface on the side closest to the half-mirror, the first reflective polarizing layer is arranged along the convex surface of the first lens, the second reflective polarizing layer is arranged along the convex surface of the second lens, the first reflective polarizing layer transmits first polarized light and reflects second polarized light, and the second reflective polarizing layer reflects one of the first polarized light and transmits the other.

[0058] In the optical apparatus according to embodiment 2 of this disclosure, the thickness of at least one of the first reflective polarizing layer and the second reflective polarizing layer is 50 μm or less, as described in embodiment 1.

[0059] In the optical apparatus according to embodiment 3 of the present disclosure, in embodiment 1 or 2, one of the first polarization and the second polarization is right-circularly polarized and the other is left-circularly polarized, and the rotation direction of the circular polarization is maintained in the reflection by the first reflection polarization layer and the second reflection polarization layer, respectively.

[0060] In the optical apparatus according to embodiment 4 of the present disclosure, in embodiment 3, the second reflective polarizing layer reflects the first polarized light and transmits the second polarized light.

[0061] The optical apparatus according to Embodiment 5 of the present disclosure is, in any of Embodiments 1 to 4, wherein one of the first polarization and the second polarization is right-circularly polarized and the other is left-circularly polarized, and at least one of the first reflective polarization layer and the second reflective polarization layer is a cholesteric liquid crystal layer.

[0062] The optical apparatus according to embodiment 6 of the present disclosure is, in any of embodiments 1 to 4, wherein one of the first polarization and the second polarization is right-circularly polarized and the other is left-circularly polarized, and at least one of the first reflective polarization layer and the second reflective polarization layer is a PVH layer.

[0063] The optical apparatus according to embodiment 7 of the present disclosure is, in any of embodiments 1 to 4, wherein one of the first polarization and the second polarization is horizontally polarized and the other is vertically polarized, and at least one of the first reflective polarization layer and the second reflective polarization layer is a wire grid layer.

[0064] In the optical apparatus according to embodiment 8 of the present disclosure, the half mirror is in contact with the first lens and the second lens in any of embodiments 1 to 7.

[0065] An optical apparatus according to embodiment 9 of the present disclosure comprises, in any of embodiments 1 to 8, at least one of a quarter-λ plate located between the half-mirror and the first lens, and a quarter-λ plate located between the half-mirror and the second lens.

[0066] In the optical apparatus according to aspect 10 of the present disclosure, in any of aspects 1 to 9, the first reflective polarizing layer and the second reflective polarizing layer are arranged between the display device and the observer, and the first reflective polarizing layer is closer to the display device than the second reflective polarizing layer.

[0067] The optical device according to embodiment 11 of the present disclosure comprises a 1 / 4λ plate closer to the display device than the first reflective polarizing layer, in embodiment 10.

[0068] The optical apparatus according to embodiment 12 of the present disclosure comprises a 1 / 4λ plate closer to the observer than the second reflective polarizing layer, in embodiment 10 or 11.

[0069] An optical apparatus according to embodiment 13 of the present disclosure comprises, in any of embodiments 10 to 12, a third lens that is closer to the observer than the second reflective polarizing layer.

[0070] In the optical apparatus according to aspect 14 of this disclosure, the third lens is a diffractive lens in aspect 13.

[0071] In the optical apparatus according to aspect 15 of this disclosure, the diffracting lens is a PB lens in aspect 14.

[0072] In the optical apparatus according to aspect 16 of this disclosure, in aspect 13, the third lens is a plano-convex lens in which the surface on the side closer to the half-mirror is flat.

[0073] An optical apparatus according to embodiment 17 of the present disclosure comprises a 1 / 2λ layer between the first reflective polarizing layer and the half mirror in any of embodiments 1 to 16.

[0074] An optical apparatus according to aspect 18 of the present disclosure, in any of aspects 1 to 17, includes a single-layer thin film having both polarized reflection and polarized transmission functions as at least one of the first reflective polarizing layer and the second reflective polarizing layer.

[0075] The optical apparatus according to aspect 19 of the present disclosure is characterized in that, in any of aspects 1 to 18, the radius of curvature of at least one of the convex surfaces of the first lens and the second lens is 40 mm or more and 160 mm or less.

[0076] In the optical device according to aspect 20 of this disclosure, in any of aspects 10 to 19, the display device is a liquid crystal display device or a self-emissive display device.

[0077] In the optical apparatus according to embodiment 21 of the present disclosure, in any of embodiments 1 to 20, the first reflective polarizing layer is bonded to the convex surface of the first lens via a first adhesive layer, the second reflective polarizing layer is bonded to the convex surface of the second lens via a second adhesive layer, and the thickness of at least one of the first adhesive layer and the second adhesive layer is 25 μm or more.

[0078] In the optical apparatus according to embodiment 22 of this disclosure, in any of embodiments 1 to 21, the first lens and the second lens are arranged symmetrically with respect to the half mirror.

[0079] In the optical apparatus according to aspect 23 of the present disclosure, in any of aspects 10 to 22, light emitted from the display device and reflected by the second reflective polarizing layer and the half mirror toward the observer is superimposed with light emitted from the display device and reflected by the half mirror and the first reflective polarizing layer toward the observer.

[0080] A head-mounted display according to aspect 24 of this disclosure comprises the optical device described in any of aspects 1 to 23.

[0081] The foregoing disclosures are for illustrative and explanatory purposes only, and not for limitation. Many variations will be obvious to those skilled in the art based on these examples and descriptions, and these variations are also included in the embodiments. [Explanation of symbols]

[0082] P1 1st reflective polarizing layer P2 2nd reflective polarizing layer Z1 First Lens Z2 2nd lens HM Half Mirror Q1 1 / 4λ layer Q2 1 / 4λ layer QX 1 / 4λ layer QY 1 / 4λ layer HX 1 / 2λ layer T1 / T2 convex PA polarizing material D Display device U Observer

Claims

1. A first reflective polarizing layer and a second reflective polarizing layer, A half-mirror located between the first reflective polarizing layer and the second reflective polarizing layer, A first lens located between the first reflective polarizing layer and the half mirror, The device comprises a second reflective polarizing layer and a second lens located between the half mirror, The first lens is a plano-convex lens in which the surface closest to the half-mirror is flat. The second lens is a plano-convex lens in which the surface closest to the half-mirror is flat. The first reflective polarizing layer is arranged along the convex surface of the first lens, The second reflective polarizing layer is arranged along the convex surface of the second lens, The first reflective polarizing layer transmits the first polarized light and reflects the second polarized light. The second reflective polarizing layer is an optical device that reflects one of the first polarized light and the second polarized light and transmits the other.

2. The optical apparatus according to claim 1, wherein the thickness of at least one of the first reflective polarizing layer and the second reflective polarizing layer is 50 μm or less.

3. One of the first and second polarizations is right-circularly polarized, and the other is left-circularly polarized. The optical apparatus according to claim 1, wherein the rotation direction of circularly polarized light is maintained in the reflection by the first reflective polarizing layer and the second reflective polarizing layer, respectively.

4. The optical apparatus according to claim 3, wherein the second reflective polarizing layer reflects the first polarized light and transmits the second polarized light.

5. One of the first and second polarizations is right-circularly polarized, and the other is left-circularly polarized. The optical apparatus according to any one of claims 1 to 4, wherein at least one of the first reflective polarizing layer and the second reflective polarizing layer is a cholesteric liquid crystal layer.

6. One of the first and second polarizations is right-circularly polarized, and the other is left-circularly polarized. The optical apparatus according to any one of claims 1 to 4, wherein at least one of the first reflective polarizing layer and the second reflective polarizing layer is a PVH layer.

7. One of the first and second polarizations is horizontally polarized, and the other is vertically polarized. The optical apparatus according to any one of claims 1 to 4, wherein at least one of the first reflective polarizing layer and the second reflective polarizing layer is a wire grid layer.

8. The optical apparatus according to any one of claims 1 to 4, wherein the half-mirror is in contact with the first lens and the second lens.

9. The optical apparatus according to any one of claims 1 to 4, comprising at least one of a 1 / 4λ layer located between the half mirror and the first lens, and a 1 / 4λ layer located between the half mirror and the second lens.

10. The first reflective polarizing layer and the second reflective polarizing layer are placed between the display device and the observer. The optical device according to any one of claims 1 to 4, wherein the first reflective polarizing layer is closer to the display device than the second reflective polarizing layer.

11. The optical device according to claim 10, further comprising a 1 / 4λ layer closer to the display device than the first reflective polarizing layer.

12. The optical apparatus according to claim 10, further comprising a 1 / 4λ layer closer to the observer than the second reflective polarizing layer.

13. The optical apparatus according to claim 10, further comprising a third lens closer to the observer than the second reflective polarizing layer.

14. The optical apparatus according to claim 13, wherein the third lens is a diffractive lens.

15. The optical apparatus according to claim 14, wherein the diffraction lens is a PB lens.

16. The optical apparatus according to claim 13, wherein the third lens is a plano-convex lens whose surface on the side closest to the half-mirror is flat.

17. The optical apparatus according to claim 10, further comprising a 1 / 2λ layer between the first reflective polarizing layer and the half mirror.

18. The optical apparatus according to any one of claims 1 to 4, wherein at least one of the first reflective polarizing layer and the second reflective polarizing layer includes a single-layer thin film that combines both polarized reflection and polarized transmission functions.

19. The optical apparatus according to any one of claims 1 to 4, wherein the radius of curvature of at least one of the convex surfaces of the first lens and the second lens is 40 mm or more and 160 mm or less.

20. The optical device according to claim 10, wherein the display device is a liquid crystal display device or a self-emissive display device.

21. The first reflective polarizing layer is bonded to the convex surface of the first lens via the first adhesive layer. The second reflective polarizing layer is bonded to the convex surface of the second lens via the second adhesive layer. The optical apparatus according to any one of claims 1 to 4, wherein the thickness of at least one of the first adhesive layer and the second adhesive layer is 25 μm or more.

22. The optical apparatus according to any one of claims 1 to 4, wherein the first lens and the second lens are arranged symmetrically with respect to the half mirror.

23. The optical apparatus according to claim 10, wherein light emitted from the display device and reflected by the second reflective polarizing layer and the half mirror toward the observer is superimposed with light emitted from the display device and reflected by the half mirror and the first reflective polarizing layer toward the observer.

24. A head-mounted display comprising the optical device described in any one of claims 1 to 4.

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