Reflection polarization optical element, optical apparatus, display device, and method of manufacturing reflection polarization optical element

Abstract

To reduce partial deterioration of polarization transmission characteristics in a reflection polarization optical element composed of a curved substrate.SOLUTION: The reflective polarizing optical element includes a substrate having a curved surface part in which a surface forms a curved surface, and when viewed in a plan view in an optical axis direction, the curved surface part has a shape surrounded by a plurality of arcs each forming a part of the same circle in the plan view and a line connecting ends of adjacent arcs of the plurality of arcs, and a reflective polarizing film for a polarizing beam splitter having a wire grid structure, in which the shortest diameter among diameters passing through a center point of the circle in the plan view is defined as a short diameter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reflective polarizing optical element, an optical instrument, a display device, and a method for manufacturing a reflective polarizing optical element. [Background technology]

[0002] In recent years, head-mounted displays have been used in various fields, including virtual reality (VR), augmented reality (AR), and mixed reality (MR). A head-mounted display has an optical system that focuses the image displayed on the display at the user's eye position. A head-mounted display achieves a compact, lightweight, and high-quality optical system by folding the optical path using circularly polarized light and a half mirror. Furthermore, in head-mounted displays, the shape of each optical element is often not axially symmetrical like a digital camera, but rather asymmetrical, with at least one side cut off, and with a major and minor axis.

[0003] To provide such optical elements with suitable polarization properties, films with optical properties, such as polarizing films, polarizing beam splitter (PBS) films, and retardation films, are laminated to curved substrates. In head-mounted displays, optical elements obtained in this way make it possible to make them smaller and lighter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-075746 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 discloses a reflective polarizing optical element in which a film having a wire grid structure is attached as a polarizing beam splitter film to a curved substrate having a shape similar to that of an eyeglass lens, for example. However, it is becoming increasingly recognized that when a wire grid film is attached to a curved substrate, the polarized light transmission characteristics of the reflective polarizing optical element may be partially reduced.

[0006] The present invention has been made in response to this recognition, and one of its objects is to reduce the partial degradation of the polarization transmission characteristics in a reflective polarization optical element made of a curved substrate. [Means for solving the problem]

[0007] In order to solve the above problems, an optical element according to one aspect of the present invention comprises: a substrate having a curved surface portion that forms a curved surface, wherein, in a plan view seen in the optical axis direction, when the curved surface portion has a shape surrounded by a plurality of arcs each forming a part of the same circle in the plan view and a line connecting ends of adjacent arcs among the plurality of arcs, the shortest diameter among diameters passing through the center point of the circle in the plan view is defined as the minor diameter, and when the curved surface portion has a shape formed by an outline including a plurality of arcs with different curvatures, the shortest diameter among diameters passing through the centroid point of the outline in the plan view is defined as the minor diameter; a reflective polarizing film for a polarizing beam splitter having a wire grid structure, the reflective polarizing film being attached to the curved surface portion such that the angle between the arrangement direction of the wires in the reflective polarizing film and the extension direction of the minor axis of the substrate is within 45°; Equipped with. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to reduce partial deterioration in the polarization transmission characteristics of a reflective polarization optical element made of a curved substrate. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a schematic diagram illustrating the structure of an example of a reflective polarization optical element according to a first embodiment. [Figure 2] 2A to 2C are schematic diagrams showing examples of the shape of a substrate of the reflective polarization optical element according to the first embodiment. [Figure 3] 1A and 1B are diagrams illustrating the stretching of a wire grid film used in the present invention. [Figure 4] 10A and 10B are diagrams illustrating the relationship between the minor axis and the major axis of a curved surface portion and the half-open angle. [Figure 5] 1 is a graph showing the transmission characteristics of a wire grid film used in the present invention. [Figure 6] 1 is a schematic view showing the structure of an example of a manufacturing apparatus according to a first embodiment. [Figure 7] 10A and 10B are diagrams showing examples of a wire grid film to be attached and accompanying configurations. [Figure 8] 1A to 1C are diagrams illustrating an example of a method for manufacturing a reflective polarization optical element. [Figure 9] FIG. 1 is a schematic diagram showing the shape of a substrate used in Example 1. [Figure 10] FIG. 1 is a schematic view showing an example of a wire grid film used in Example 1. [Figure 11] 3A to 3C are diagrams illustrating a method for manufacturing a reflective polarization optical element in Example 1. [Figure 12] FIG. 10 is a schematic diagram showing the shape of a substrate used in Example 7. [Figure 13] FIG. 10 is a schematic diagram showing the shape of the substrate used in Example 8. [Figure 14] FIG. 1 is a schematic diagram showing the shape of a substrate used in Comparative Example 1. [Figure 15] 10A to 10C are diagrams illustrating another example of a method for manufacturing a reflective polarization optical element. [Figure 16] FIG. 10 is a schematic diagram illustrating an example of an optical device (display device) according to a second embodiment. [Figure 17] FIG. 10 is a schematic diagram showing another example of the optical device (display device) according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments and examples will be described in detail below with reference to the drawings. In the following description, common components are designated by common reference numerals across multiple drawings. Therefore, the common components will be described with mutual reference to multiple drawings, and descriptions of components designated by common reference numerals will be omitted as appropriate. Furthermore, the dimensions, materials, shapes, and relative positions of components illustrated in the following embodiments and examples are arbitrary and can be changed depending on the configuration of the device to which the present invention is applied or various conditions.

[0011] [First embodiment] A reflective polarization optical element and a manufacturing method thereof according to a first embodiment of the present invention will be described below with reference to Figures 1 to 8(d). Figure 1 is a schematic diagram showing an example of a polarization optical element according to this embodiment, where Figure 1(a) is a plan view of the reflective polarization optical element 10 as seen from the direction in which light is incident, and Figure 1(b) is a cross-sectional view of the reflective polarization optical element 10 taken along a wire arrangement direction 12a, which will be described later.

[0012] As shown in FIG. 1 , a reflective polarizing optical element 10 according to this embodiment includes a substrate 11 and a wire grid film 12. The wire arrangement direction 12a and the wire extension direction 12b of the wire grid film 12 will be described later. The illustrated substrate 11 has a curved surface portion 11a, a peripheral edge portion 11b, and a step portion 11e. In a plan view, the curved surface portion 11a has a shape obtained by connecting two sides that do not face each other at the center with an arc, or a shape obtained by removing two regions of a circle with non-opposing straight lines. Note that the two non-opposing sides or two straight lines may be formed by curves. The peripheral edge portion 11b is formed adjacent to the outer periphery of the curved surface portion 11a so as to surround the periphery of the curved surface portion. The step portion 11e is arranged to connect the curved surface portion 11a and the peripheral edge portion 11b, and is formed to have a surface parallel to the direction of light incidence.

[0013] In the substrate 11 illustrated in FIG. 1, the curved surface portion 11a has an asymmetric shape in plan view, with a minor axis 11c and a major axis 11d. Here, the major axis corresponds to the length of the longest axis passing through the center point O calculated from the arc portion of the curved surface portion 11a in plan view, and the minor axis corresponds to the length of the shortest axis passing through the center point O calculated from the arc portion of the curved surface portion 11a in plan view. Therefore, the major axis and the minor axis are not necessarily perpendicular to each other, and multiple minor axes and major axes can be selected depending on the shape of the curved surface portion 11a in plan view. Furthermore, the curved surface portion 11a may have a convex or concave shape, or may be aspherical.

[0014] The peripheral edge portion 11b is an optically ineffective region and is provided, for example, to serve as a mold release margin when manufacturing the substrate 11, particularly when manufactured by injection molding. It may also be provided so that the completed reflective polarization optical element 10 can be attached to the housing of an optical device such as a head-mounted display. Therefore, its shape may be either curved or flat, and may be either axially symmetric or non-axially symmetric. Furthermore, the peripheral edge portion 11b does not need to exist along the entire periphery of the curved portion 11a; it may exist only partially. Furthermore, the peripheral edge portion 11b may be absent.

[0015] It should be noted that the shape of the substrate when viewed in plan, which is assumed when carrying out the present invention, is not limited to the shape exemplified in Fig. 1. Other examples of the shape of the substrate will be described with reference to Fig. 2(a) to Fig. 2(c). Fig. 2(a) to Fig. 2(c) are plan views showing other examples of the shape of the substrate when viewed in plan in the optical axis direction of the substrate.

[0016] 2(a), the curved surface portion 11a-2 has a partially cut circular shape in plan view, with two opposing sides and two arcs connecting the two sides. The two arcs are positioned facing each other on the circumference of the same circle, and two straight lines are provided as two opposing parallel sides connecting the two opposing sets of ends of the two arcs. The illustrated substrate 11-2 has a peripheral edge portion 11b-2 with the same width provided on the outer periphery of the curved surface portion 11a-2, which has a circular outer shape in plan view.

[0017] In the example of substrate 11-2, minor axis 11c corresponds to the distance between two straight line segments passing through center point O, and major axis 11d corresponds to the distance between two arcs passing through center point O and perpendicular to minor axis 11c. Center point O is defined as a reference point for identifying minor axis 11c and major axis 11d of substrate 11-2, and is the center point O of the circle that makes up the two arcs in plan view.

[0018] 2(b), in plan view, the curved surface portion 11a-3 has a shape similar to that of a segmented circle, with a portion of the circle removed by a straight line. The peripheral edge portion 11b-3 is disposed so as to surround the outer periphery of the curved surface portion 11a-3. In the example of the substrate 11-3, the minor axis 11c is the diameter that passes through the center point O and defines the shortest distance in plan view, and the major axis 11d is the diameter that passes through the center point O and defines the longest distance in a direction perpendicular to the minor axis 11c.

[0019] 2(a) or 2(b) shows the case where the curved surface portion has two straight lines in a plan view. However, the number of straight lines constituting the curved surface portion is not limited to two, and the curved surface portion may have three or more straight lines in a plan view of the substrate. In this case, the curved surface portion may have three or more arcs in a plan view, each arc being part of the circumference of the same circle, and two adjacent ends of the straight lines may be connected by an arc.

[0020] 2(c), the curved surface 11a-4 has a shape formed by a plurality of arcs with different curvatures, such as a spectacle lens, in a plan view. As shown in the example, the substrate 11-4 can be configured without a peripheral edge, unlike the substrates shown in FIGS. 1 to 2(b).

[0021] Furthermore, in the illustrated substrate 11-4, since no identical circle exists, it is not possible to determine the center point in a planar view of the substrate 11-4. In such a case, the centroid C of the curved surface portion 11a-4 in a planar view of the substrate 11-4 can be used as a reference point. The centroid C of the shape of the curved surface portion 11a in a planar view is used as the reference point, and the shortest diameter passing through this is the minor diameter 11c, while the longest diameter passing through the centroid C is the major diameter 11d.

[0022] Optical devices using the reflective polarizing optical element 10, particularly head-mounted displays, are expected to be worn on the user's face, particularly around the eyes and nose, which imposes size restrictions on the device. Therefore, in order to provide a nose guard for the user and ensure installation space for electronic devices such as motors and sensors, the shape of the substrate is often not axially symmetric but rather asymmetric, with a minor axis and a major axis. In such cases, the substrate shape shown in FIG. 2(c) is expected. For such substrates and curved surfaces, the minor axis and major axis can be determined by using the centroid C as the reference point, as described above.

[0023] The substrate material described above can be plastic or glass, as long as it is transparent and transmissive to light, such as visible light, targeted by the reflective polarization optical element 10. When using plastic, it is preferable to use a material that can be formed by injection molding and is used for optical purposes. Examples of materials that can be used include polycarbonate (PC), polyester (PEs), polymethyl methacrylate (PMMA), cycloolefin polymer (COP), and cycloolefin copolymer (COC). When using glass, the material is not particularly limited, but examples include synthetic quartz and the common glass material BK-7.

[0024] Next, the wire grid film used in the present invention will be described with reference to Fig. 3. Fig. 3(a) is a plan view of the wire grid film seen from above, showing the structure of the wire grid film in a simplified manner. The wire grid film 32 has a base resin film 32a made of resin and having a fine concave-convex pattern extending periodically in a certain direction on its surface, and wires 32b made of a metal layer formed on the convex portions of the fine concave-convex pattern and extending in the same direction as the convex portions.

[0025] The optical properties of the wire grid film 32 are such that, due to electromagnetic interaction between incident light and the wires having a fine concave-convex shape, light polarized parallel to the arrangement direction 31a of the wires 32b is transmitted and light polarized parallel to the extension direction 31b of the wires 32b is reflected. In order for the wire grid film 32 to exhibit polarized light transmission properties for visible light, the spacing 33 between the periodically arranged wires must be sufficiently smaller than the wavelength of visible light. For this reason, the inventors have recognized that as the spacing 33 between the wires increases, the polarized light transmittance for visible light deteriorates.

[0026] Here, the effects of the wire grid film 32 stretched in the extension direction of the wires 32b and in the arrangement direction are explained using the wire grid films shown in Figures 3(b) and 3(c). For example, as shown in Figure 3(b), even when the wire grid film 32 is stretched along the extension direction 31b of the wires 32b, the spacing between the wires 32b does not increase significantly, and therefore the change in polarized light transmittance is small. In contrast, as shown in Figure 3(c), when the wire grid film 32 is stretched along the arrangement direction 31a of the wires 32b, the spacing 33 between the wires 32b increases. This results in a significant deterioration in polarized light transmittance.

[0027] Methods for attaching a wire grid film to a curved substrate to form a reflective polarizing optical element include, for example, vacuum forming, pressure forming, and insert molding. To attach a planar wire grid film 32 to a curved substrate using these methods, the film must be stretched. During this process, it is expected that the wire grid film 32 will be stretched to a greater extent toward the periphery of the curved substrate. As described above, this stretching of the film causes an increase in the wire spacing in the wire alignment direction of the wire grid film 32. Based on these findings, the inventors discovered that significant stretching of the wire grid film 32 occurs near the periphery of the element and that a significant deterioration in polarized light transmittance can occur in the region stretched along the wire alignment direction of the wires 32b.

[0028] Here, referring again to FIG. 1, a reflective polarizing optical element 10 according to a first embodiment of the present invention will be described. In the reflective polarizing optical element 10 shown in FIG. 1, the arrangement direction 12a of the wires in the wire grid film 12 is arranged so as to be substantially parallel to the extension direction of the minor axis 11c of the substrate 11. Furthermore, the extension direction 12b of the wires is arranged so as to be perpendicular to the arrangement direction 12a. By attaching the wire grid film 12 to the substrate 11 in this arrangement, it is possible to reduce the area in which the spacing between the wires significantly increases when the wire grid film 12 is attached. Therefore, it is possible to reduce partial deterioration in the polarization transmission characteristics of the reflective polarizing optical element, particularly deterioration in the outer periphery of the element.

[0029] The extension direction of the minor axis 11c and the arrangement direction 12a are preferably parallel. However, depending on the shape of the substrate, it may not be easy to clearly define the minor axis 11c. Therefore, when attaching the wire grid film 12 to the curved surface portion 11a, it may not be possible to align the extension direction of the wire grid film 12 with the direction in which the wire grid film 12 is most stretched. Even in such cases, by setting the angle φ between the extension direction of the minor axis 11c and the arrangement direction 12a to φ<45°, it is possible to roughly align the region in which the wire grid film has a relatively small amount of stretch with the arrangement direction 12a. Furthermore, if the angle is greater than 45°, it is more likely that the curved surface portion 11a will include a region with a large amount of stretch that results in a decrease in polarization transmission characteristics. By specifying these conditions, it is possible to reduce local degradation of the polarization transmission characteristics of the reflective polarization optical element, especially at the periphery of the element.

[0030] As described above, to obtain the effect of suppressing the deterioration of polarized light transmittance in the peripheral area of ​​the element, it is sufficient that φ≦45°. However, to more effectively realize the effects of the present invention, it is preferable that φ≦30°. By roughly matching the wire arrangement direction 12a, which is significantly affected by the stretching of the wire grid film, with the extension direction of the minor axis 11c, in which the amount of stretching is minimized, it is possible to suppress the increase in wire spacing and improve the deterioration of polarized light transmittance in the peripheral area of ​​the element.

[0031] The optical performance of the reflective polarizing optical element 10 can be evaluated by measuring the polarized light transmittance at the peripheral portion of the element. For example, for the polarized light transmittance of light in a desired wavelength range, such as the wavelength range from 420 nm to 700 nm, if the change in the polarized light transmittance at the peripheral portion of the element compared to the design value is 8% or less, the function as a reflective polarizing optical element is not impaired. Therefore, if the change in the polarized light transmittance at the peripheral portion of the element compared to the design value is 8% or less, the optical performance of the reflective polarizing optical element can be evaluated as good.

[0032] Furthermore, the optical performance of the reflective polarizing optical element 10 can also be evaluated by directly measuring the wire spacing. For example, if the minimum wire spacing between adjacent wires in the curved surface portion 11a of the reflective polarizing optical element 10 is p1 and the maximum wire spacing is p2, then if p2 / p1≦1.18, the change in wire spacing due to extension is suppressed, and the optical performance can be evaluated as good. Similarly, if the wire spacing at the center of the element is q1 and the wire spacing at the outer periphery of the element is q2, then the optical performance of the curved surface portion 11a can be evaluated as good if q2 / q1≦1.18.

[0033] The optical performance of the reflective polarization optical element 10 can also be controlled by appropriately setting the half-angle of the substrate 11. This will be explained with reference to Fig. 4. Fig. 4 shows cross sections along the minor axis 11c and major axis 11d of the curved surface portion 11a of the substrate 11, and the half-angles θ1 and θ2 obtained from the cross sections. The half-angles θ1 and θ2 are obtained by bisecting the angle defined by the center of a sphere obtained from the curvature R of the arc along the minor axis 11c and major axis 11d on the curved surface portion 11a and the arc (the optimal value obtained by the least squares method in the case of an aspheric surface).

[0034] Here, the influence of the half-angle setting on the optical performance of a reflective polarizing optical element will be described with reference to Figures 5(a) and 5(b). Figure 5(a) shows the maximum change in polarized light transmittance along the wire arrangement direction and the wire extension direction when a wire grid film 12 is bonded to various curved substrates with different half-angles. The maximum change in transmittance (Δtransmittance (%)) is calculated as [(measured transmittance) - (transmittance of reflective polarizing optical element on flat substrate)] / (transmittance of reflective polarizing optical element on flat substrate) × 100. Figure 5(a) shows that even with the same half-angle, the wire spacing is more likely to increase in the wire arrangement direction than in the wire extension direction when the film is bonded to a substrate, resulting in a significant deterioration in transmittance.

[0035] Figure 5(b) shows the range where deterioration of polarized light transmittance can be particularly suppressed when the wire grid film is attached so that the minor axis 11c coincides with the wire arrangement direction, reflecting the difference in transmittance change depending on the half aperture angle. Here, the range in Figure 5(b) is expressed by the following equations 1 and 2. θ1<θ2, 0°≦θ1≦12°, and 5°≦θ2≦20° (Equation 1) When θ1<θ2, 0°≦θ1≦12° and 5°≦θ2≦20° (Equation 2) When formula 1 is satisfied, the deterioration in polarized light transmittance at the peripheral portion of the element is a maximum of 8%, so the optical performance of the element can be evaluated as good (region 51). When formula 2 is satisfied, the deterioration in polarized light transmittance at the peripheral portion of the element is a maximum of 3%, so the optical performance of the element can be evaluated as very good (region 52). Note that in the range of 0°<θ2<5°, the half-open angle is small, so the shape of the reflective polarizing optical element is unsuitable for the optical device assumed in this case.

[0036] As mentioned above, the extension direction of the minor axis 11c and the wire arrangement direction 12a do not necessarily need to coincide. When the angle φ between them satisfies φ<45°, the deterioration of the polarized light transmittance can be suppressed, and when φ<30°, the effect of suppressing the deterioration of the polarized light transmittance is further improved.

[0037] Note that if the angle between the extension direction of the minor axis 11c and the wire arrangement direction 12a satisfies φ<45° but these directions do not match (φ≠0°), a different half-angle can be specified to establish conditions equivalent to the above formulas 1 and 2. In this case, the extension position of the maximum diameter along the wire arrangement direction 12a on the curved surface portion 11a and the extension position of the maximum diameter along the wire extension direction 12b are defined. Then, half-angles θ1' and θ2' are defined for the arcs drawn on the curved surface portion 11a at both extension positions, similar to the half-angles θ1 and θ2. In this case, the range expressed in formulas 1 and 2 using half-angle θ1' instead of half-angle θ1 and half-angle θ2' instead of half-angle θ2 is the range in which deterioration of polarized light transmittance can be particularly suppressed.

[0038] Next, a manufacturing apparatus for a reflective polarization optical element 10 according to this embodiment will be described with reference to Fig. 6. Fig. 6(a) is a cross-sectional view showing a schematic configuration of the manufacturing apparatus and a substrate 61 held therein. Fig. 6(b) is a top view showing the positional relationship between the substrate placed in the manufacturing apparatus and the wire grid film placed thereon, as seen through from above.

[0039] As shown in FIG. 6(a) and other figures, the manufacturing apparatus used in this embodiment includes a first chamber 63, a second chamber 64, and a stage 65. The first chamber 63 and the second chamber 64 can be independently evacuated and depressurized. An opening that can connect to each other is provided at the top of the first chamber 63 and the corresponding bottom of the second chamber 64. Note that, although an example in which these chambers are arranged vertically is shown here, this arrangement is merely an example, and they can also be arranged horizontally or upside down.

[0040] A stage 65 is disposed inside the first chamber 63, capable of supporting the substrate 61 and moving up and down toward the second chamber 64. The substrate 61, which has a curved surface portion 61a and a peripheral portion 61b similar to the substrate 11 illustrated in FIG. 1, and in which a minor axis 61c and a major axis 61d are defined by the curved surface portion 61a, is disposed on the stage 65. The wire grid film 62 is disposed between the first chamber 63 and the second chamber 64, which are connected via the opening described above. As shown in FIG. 6(b), the substrate 61 having the curved surface portion 61a and the peripheral portion 61b faces the wire grid film 62 in a plan view, and is disposed such that the wire arrangement direction 62a coincides with the extension direction of the minor axis 61c of the substrate 61. Similarly, the substrate 61 is disposed such that the angle between the wire extension direction 62b and the extension direction of the major axis 61d of the substrate 61 is 30° or less in a plan view.

[0041] It should be noted that, when manufacturing the reflective polarization optical element 10, other configurations may be added to the wire grid film 62. These configurations will be described with reference to Fig. 7. Figures 7(a) to 7(c) each show a schematic cross section of a wire grid film or the like used in the attachment process.

[0042] As shown in FIG. 7( a), a uniform adhesive layer 75 can be provided on the surface of the wire grid film 62 facing the substrate. Furthermore, a protective film 76 for protecting the surface of the wire grid film 62 can be provided on the surface of the wire grid film 62 facing away from the substrate (the surface opposite the adhesive layer 75). The glass transition temperature of the protective film 76 is required to be lower than the glass transition temperature of the wire grid film 62. This increases the strength of the wire grid film 62, making it less likely to tear when attached to the substrate 61.

[0043] Furthermore, the wire grid film 62 is more expensive than general films. Therefore, from the viewpoint of reducing manufacturing costs, it is not appropriate to use a wire grid film 62 that is much larger than the area of ​​the curved surface portion 61a of the substrate 61. In other words, the wire grid film 62 only needs to be slightly larger than the surface area of ​​the curved surface portion 61a of the substrate 61. Specifically, for example, the wire grid film 62 only needs to have an area that is 1.5 to 2.5 times the area of ​​the curved surface portion 61a in a plan view of the substrate 61 in the optical axis direction.

[0044] Here, if the size of the wire grid film 62 is made as small as possible, it is necessary to ensure the size necessary for holding the wire grid film 62 between the first chamber 63 and the second chamber 64. For this reason, as shown in FIG. 7(b), a support film 77 made of a material separate from the wire grid film 62 may be attached to the wire grid film 62. In this case, in order to ensure uniform deflection of the film when heated, it is preferable that the glass transition temperature of the support film 77 be equal to or about 20°C lower than the glass transition temperature of the wire grid film 62.

[0045] 7(c), a support film 77 may be attached only to the outer periphery of the wire grid film 62. After the wire grid film 62 is attached to the substrate 61, the support film 77 can be peeled off from the wire grid film 62 at an appropriate timing.

[0046] In the step of attaching the wire grid film 62, the wire grid film 62 and the like described above are held between a first chamber 63 and a second chamber 64. In the manufacturing apparatus described in this embodiment, a stage 65 is provided to tilt the substrate 61 so that a tangent to the center point of the minor axis 61c of the substrate 61 is parallel to the wire grid film 62. As a result, the stretching state of the wire grid film 62 along the extension direction of the minor axis 61c of the substrate 61 becomes symmetrical about the center point of the minor axis 61c. This prevents the occurrence of regions with large stretching due to the attachment of the wire grid film 62, and enables the wire grid film 62 to be attached with a small maximum stretch ratio.

[0047] Next, with reference to FIGS. 8( a) to 8(d), a process for attaching a wire grid film 62 to a substrate 61 using the manufacturing apparatus described with reference to FIG. 6 will be described. After the substrate 61 and wire grid film 62 are placed in the manufacturing apparatus as shown in FIG. 6, a first chamber 63 and a second chamber 64 are evacuated as shown in FIG. 8(a). The wire grid film 62 is then heated, for example, using a heater or the like installed in the second chamber 64. After the wire grid film 62 has been heated to a desired temperature, the stage 65 is raised as shown in FIG. 8(b) to bring the curved surface portion 61a of the substrate 61 into contact with the wire grid film 62. By further raising the stage 65, the wire grid film 62 is attached to the front surface of the curved surface portion 61a.

[0048] 8(c), only the second chamber 64 is opened to the atmosphere to increase the pressure, and if necessary, high-pressure gas is introduced to pressurize the wire grid film 62 and press it against the substrate 61. At this time, the heating and pressurization of the wire grid film 62 may be continued for a certain period of time if necessary.

[0049] Here, the wire grid film 62 is typically heated using an infrared heater that directly heats the film, but there is also the option of heating the entire first chamber 63 and second chamber 64 using a heater or the like. In this case, the substrate 61 is also heated. In particular, if the substrate 61 is made of a plastic material, there is a concern that it may deform due to heat. For this reason, it is important to provide a thermal insulating structure for the stage 65 that supports the substrate 61, or for the pedestal that directly supports the substrate 61. In other words, regardless of the temperature of the wire grid film 62, it is preferable that the temperature of the substrate 61 be kept below 120°C.

[0050] Thereafter, the heating and pressurization of the wire grid film 62 are stopped, the second chamber 64 is returned to atmospheric pressure, and the first chamber 63 is also opened to the atmosphere. Then, the substrate 61 with the wire grid film 62 attached thereto is removed. Next, as shown in FIG. 8( d ), the unnecessary wire grid film 62 d is cut away so that the wire grid film 62 c remains only on the curved surface portion 61 a of the substrate 61. The cutting method can be a method of cutting away the unnecessary wire grid film 62 d by applying a blade along the outer edge of the curved surface portion 61 a, or a method of cutting away the unnecessary wire grid film 62 d by applying laser light along the outer edge of the curved surface portion 61 a. In this manner, a reflective polarizing optical element 60 is manufactured in which the wire grid film 62 is attached to the curved surface portion 61 a of the substrate 61.

[0051] Here, examples of actually manufacturing reflective polarizing optical elements according to this embodiment will be described below. The optical performance evaluation of the reflective polarizing optical element described below involves measuring polarized light transmittance and evaluating the results. In the evaluation of optical performance, if the change in polarized light transmittance at the peripheral portion of the element compared to the design value is 3% or less, the optical performance is not significantly affected, and the evaluation result is A, indicating that the optical performance is very good. If the change in polarized light transmittance at the peripheral portion of the element compared to the design value is 8% or less, the optical performance is not significantly affected, and the evaluation result is B, indicating that the optical performance is good. Furthermore, if the change in polarized light transmittance at the peripheral portion of the element compared to the design value is more than 8%, the deterioration of optical performance along the extension direction of the minor axis of the element is not negligible, and the evaluation result is C, indicating that the optical performance is poor.

[0052] Example 1 In Example 1, the substrate 91 used had the shape shown in FIGS. 9(a) and 9(b) and was injection molded. The substrate 91 was made of a plastic primarily composed of cycloolefin copolymer (COC). Specifically, as shown in FIG. 9(a), the shape of the substrate 91 in plan view had a curved surface 91a in which two non-opposing sides were connected by a circular arc. The curved surface 91a of the substrate 91 formed a convex lens with a minor axis 91c length L1 of 26.7 mm, a major axis 91d length L2 of 40.0 mm, a half aperture angle θ1 of 15°, and a half aperture angle θ2 of 22°, and had no peripheral edge.

[0053] The wire grid film 92 and other components attached to the substrate 91 had the shape shown in the plan view of Fig. 10(a) and the cross-sectional view of Fig. 10(b). Specifically, the component consisted of a wire grid film 92 with a thickness of approximately 0.1 mm and an adhesive layer 95, and had a size of 80 mm x 80 mm.

[0054] The substrate 91 and the wire grid film 92, etc., were positioned in the plan view as shown in Fig. 11 and placed in the manufacturing apparatus illustrated in Fig. 6(a). When the substrate 91 was placed in the first chamber 63, the substrate 91 was tilted so that the tangent to the center point of the minor axis 91c was parallel to the wire grid film 92. The substrate 91 was also placed so that the extension direction of the minor axis 91c of the curved surface portion 91a of the substrate 91 and the wire arrangement direction 92a of the wire grid film 92 were approximately parallel (within ±2°). In the step illustrated in Fig. 8(a), the wire grid film 92, etc., were heated to a desired temperature (140°C) using an infrared heater.

[0055] After heating the wire grid film 92, etc., the curved surface 91a of the substrate 91 is brought into contact with the wire grid film 92, etc. (adhesive layer 95) in the process illustrated in Fig. 8(b). Thereafter, in the process illustrated in Fig. 8(c), only the inside of the second chamber 64 is opened to the atmosphere, and compressed air is further introduced into the second chamber 64 to increase the pressure to 0.3 MPa, pressurizing the wire grid film 92, etc. and pressing it against the substrate 91 for 10 seconds. Then, the heating and pressurization of the wire grid film 92, etc. are stopped, the second chamber 64 is returned to atmospheric pressure, and then the first chamber 63 is also opened to the atmosphere.

[0056] 8(d), unnecessary wire grid film was cut away by applying a blade along the outer edge of curved portion 91a so as to leave only the wire grid film 92 on the curved portion 91a of substrate 91. In this way, a reflective polarization optical element in which wire grid film 92 was attached to the curved portion 91a of substrate 91 was manufactured.

[0057] The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned methods and criteria, and as a result, it was confirmed that the optical performance of the reflective polarizing optical element of this example was good, as shown in Table 1.

[0058] Example 2 In Example 2, the shape (dimensions, etc.) of the substrate 91 used in Example 1 was changed. Specifically, a reflective polarizing optical element was manufactured in the same manner as in Example 1, except that the length L1 of the minor axis 91c of the curved portion 91a of the substrate 91 was 35.7 mm, the length L2 of the major axis 91d was 60.0 mm, the half aperture angle θ1 was 12°, and the half aperture angle θ2 was 20°. The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned method and criteria, and as a result, as shown in Table 1, it was confirmed that the optical performance of the reflective polarizing optical element according to this example was good, as in Example 1.

[0059] Example 3 In Example 3, the shape of the substrate 91 used in Example 1 was changed. Specifically, the dimensions of the substrate 91 were the same as those of the substrate 91 in Example 1, except that the curved surface portion 91a was a concave lens, and a reflective polarizing optical element was manufactured in the same manner as in Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned method and criteria, and as a result, as shown in Table 1, it was confirmed that the optical performance of the reflective polarizing optical element according to this example was good, similar to that of Example 1.

[0060] Example 4 In Example 4, the shape (dimensions, etc.) of the substrate 91 used in Example 1 was changed. Specifically, for the substrate 91, the length L1 of the minor axis 91c of the curved portion 91a was 32.9 mm, the length L2 of the major axis 91d was 40.0 mm, the half aperture angle θ1 was 12°, and the half aperture angle θ2 was 20°. A reflective polarizing optical element was manufactured in the same manner as in Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned method and criteria, and as a result, as shown in Table 1, it was confirmed that the optical performance of the reflective polarizing optical element according to this example was good, as in Example 1.

[0061] Example 5 In Example 5, the shape (dimensions, etc.) of the substrate 91 used in Example 1 was changed. Specifically, for the substrate 91, the length L1 of the minor axis 91c of the curved portion 91a was 39.9 mm, the length L2 of the major axis 91d was 60.0 mm, the half aperture angle θ1 was 4°, and the half aperture angle θ2 was 6°. A reflective polarizing optical element was manufactured in the same manner as in Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned method and criteria. As shown in Table 1, when the polarized light transmittance of the peripheral portion of the element was measured, the change in polarized light transmittance compared to the design value was within 3%, confirming that the reflective polarizing optical element according to this example had good optical performance.

[0062] Example 6 In Example 6, the shape (dimensions, etc.) of the substrate 91 used in Example 1 was changed. Specifically, for the substrate 91, the length L1 of the minor axis 91c of the curved portion 91a was 25.0 mm, the length L2 of the major axis 91d was 40.0 mm, the half aperture angle θ1 was 5°, and the half aperture angle θ2 was 8°. A reflective polarizing optical element was manufactured in the same manner as in Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned method and criteria. As shown in Table 1, when the polarized light transmittance of the peripheral portion of the element was measured, the change in polarized light transmittance compared to the design value was within 3%, confirming that the reflective polarizing optical element according to this example had good optical performance.

[0063] Example 7 In Example 7, the shape of the substrate 91 used in Example 1 was changed. Specifically, as shown in the plan view of FIG. 12(a) and the cross-sectional view of FIG. 12(b), when viewed in plan, the curved surface portion 121a has a partially cut-out circular shape with two opposing sides missing from the circle, and has a peripheral edge portion 121b adjacent to and surrounding the curved surface portion 121a. The length L1 of the minor axis 121c of the curved surface portion 121a was 36.5 mm, the length L2 of the major axis 121d was 60.0 mm, the half-open angle θ1 was 12°, and the half-open angle θ2 was 20°, and the flat peripheral edge portion 121b had a diameter of 62 mm. A reflective polarizing optical element was then manufactured using the same method as in Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned method and criteria. As a result, as shown in Table 1, it was confirmed that the optical performance of the reflective polarizing optical element of this Example was good, as in Example 1.

[0064] Example 8 In Example 8, the shape of the substrate 91 used in Example 1 was changed. Specifically, as shown in the plan view of FIG. 13 , when viewed in plan, the curved surface portion 131a of the substrate 131 had a partially cut-out circular shape with one side missing a circle, and had a peripheral edge portion 131b adjacent to the curved surface portion 131a and similar in shape to the curved surface portion 131a. The length L1 of the minor axis 131c of the curved surface portion 131a was 26.8 mm, the length of the major axis 131d was 40.0 mm, the half-opening angle θ1 was 10°, and the half-opening angle θ2 was 15°, and the flat peripheral edge portion 131b had a width of 2 mm. A reflective polarizing optical element was then manufactured using the same method as in Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned method and criteria. As shown in Table 1, when the polarized light transmittance of the peripheral portion of the element was measured, the change in polarized light transmittance compared to the design value was within 8%, confirming that the optical performance of the reflective polarizing optical element of this example was good.

[0065] Example 9 In Example 9, the shape (dimensions, etc.) of the substrate 91 used in Example 1 was changed. Specifically, the length L1 of the minor axis 91c of the curved surface portion 91a of the substrate 91 was 40.2 mm, the length L2 of the major axis 91d was 50 mm, the half aperture angle θ1 was 12°, and the half aperture angle θ2 was 15°. This substrate 91 was placed in the manufacturing apparatus illustrated in FIG. 6( a) and the like, and the corresponding wire grid film 92 and the like were arranged as illustrated in FIG. 8( a). Furthermore, as the wire grid film 92 and the like, a wire grid film 92 having, for example, an adhesive layer 75 attached thereto was used. The substrate 91 and the wire grid film 92 were arranged so that the angle between the arrangement direction of the wires in the wire grid film 92 and the extension direction of the minor axis 91c of the curved surface portion 91a of the substrate 91 was 30°. Then, a reflective polarization optical element was manufactured using a method similar to that of Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-mentioned methods and criteria. As a result, it was confirmed that the optical performance of the reflective polarizing optical element of this example was good, as in Example 1, as shown in Table 1.

[0066] (Comparative Example 1) In Comparative Example 1, the shape of the substrate 91 used in Example 1 was changed. Specifically, as shown in the plan view of FIG. 14(a) and the cross-sectional view of FIG. 14(b), the curved surface portion 141a of the substrate 141 was circular in plan view, with the length L1 of the minor axis 141c and the length L2 of the major axis 141d being the same, 40.0 mm. The half-open angles θ1 and θ2 were set to 22°. A reflective polarizing optical element was then manufactured using the same method as in Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-described method and criteria. As shown in Table 1, when the polarized light transmittance at the peripheral portion of the element was measured, the change in polarized light transmittance compared to the design value was 8% or more. This deterioration in polarized light transmittance was determined to be problematic in optical performance, and the optical performance was evaluated as poor.

[0067] (Comparative Example 2) In Comparative Example 2, the shape of the substrate 91 used in Example 1 was unchanged. The length L1 of the minor axis 91c of the curved portion 91a of the substrate 91 was 26.7 mm, the length L2 of the major axis 91d was 40.0 mm, and the half-angles θ1 and θ2 were 15° and 22°, respectively. This substrate 91 was placed in the manufacturing apparatus illustrated in FIG. 6( a) and elsewhere. In this comparative example, a wire grid film 92, for example, provided with an adhesive layer 75, was used. The substrate 91 and the wire grid film 92 were arranged such that the angle between the extension direction of the minor axis 91c of the curved portion 91a of the substrate 91 and the wire arrangement direction 92a of the wire grid film 92 was 50°. A reflective polarizing optical element was then manufactured using the same method as in Example 1. The optical performance of this reflective polarizing optical element was evaluated based on the above-described method and criteria. As shown in Table 1, when the polarized light transmittance of the peripheral area of ​​the element was measured, the change in polarized light transmittance compared to the design value was 8% or more, and the polarized light transmittance had deteriorated, which was judged to be a problem with optical performance and was evaluated as poor optical performance.

[0068] [Table 1]

[0069] The evaluation results of the examples and comparative examples described above support the inventor's finding that the wire grid film stretches toward the periphery of the curved substrate, deteriorating the polarization transmission characteristics of the reflective polarization optical element. By implementing the present invention, it is possible to reduce the partial deterioration of the polarization transmission characteristics of a reflective polarization optical element made of a curved substrate, and in particular, to some extent avoid deterioration in the periphery in the direction perpendicular to the wires.

[0070] In the above-described comparative example 1, a substrate 141 is used whose curved surface is circular in a plan view. In this case, the region where the polarization transmittance is deteriorated is present at an end portion in the extension direction of the wire arrangement direction 92a of the wire grid film 92 attached to the substrate 141. Therefore, for example, after attachment, it is possible to obtain a reflective polarization optical element with a uniform polarization transmittance as a whole by removing at least one portion of the substrate and wire grid film within an angular range of ±22.5° with respect to the wire arrangement direction 92a.

[0071] A method for manufacturing such a reflective polarizing optical element will be described below as another embodiment of the present invention. Fig. 15 is a diagram schematically illustrating the final step in the manufacturing method, with Fig. 15(a) showing a plan view and a cross-sectional view of an example of a reflective polarizing optical element after the wire grid film existing outside the curved surface portion has been cut away. Fig. 15(b) shows a plan view and a cross-sectional view of an example of a reflective polarizing optical element after further removing portions with reduced polarization optical properties. Note that the step of attaching the wire grid film to the substrate is the same as the step described with reference to Fig. 8, and therefore will not be described here.

[0072] FIG. 15(a) shows a reflective polarizing optical element 150′ in which a wire grid film 92 is simply attached to a curved surface portion 141a of a substrate 141 that is circular in plan view. The wire grid film 92 has a wire arrangement direction 92a and an extension direction 92b. As shown in FIG. 15(a), characteristic-deteriorating regions 92e exist at both ends of the arrangement direction 92a on the curved surface portion 141a. If the arrangement direction 92a is defined as a direction passing through the center of the circle that defines the curved surface portion 141a, these regions correspond to the region outside the chord that defines a range of ±22.5° centered on the arrangement direction 92a of the circle. Therefore, by removing the region outside the chord, the remaining reflective polarizing optical element 150 can be treated as having favorable polarization optical properties.

[0073] 15(b) schematically shows a reflective polarizing optical element 150 in a state in which two portions have been removed in a range of ±22.5° with respect to the wire arrangement direction 92a. As shown in FIG. 15(b), the wire arrangement direction 92a roughly coincides with the extension direction of the minor axis 151c in a planar view of the substrate 151 of the reflective polarizing optical element 150 after the removal step. Furthermore, the wire extension direction 92b roughly coincides with the major axis 151d in a planar view of the substrate 151. By performing the steps described above, a reflective polarizing optical element according to one embodiment of the present invention can be obtained.

[0074] [Second embodiment] The reflective polarizing optical element according to the first embodiment described above can be applied to various devices and apparatuses such as optical instruments, display devices, and imaging devices. Specifically, it can be used in optical instruments such as head-mounted displays, digital cameras, and video cameras. In this embodiment, optical instruments and display devices will be described as specific application examples of the reflective polarizing optical element according to the first embodiment.

[0075] (optical equipment) Specific application examples of the reflective polarizing optical element according to the first embodiment include lenses constituting optical devices (photography optical systems) for cameras and video cameras, and lenses constituting optical devices (projection optical systems) for liquid crystal projectors. Fig. 16 is a schematic diagram showing an example of a preferred embodiment of optical device 160 using the reflective polarizing optical element according to the first embodiment. The optical system of optical device 160 includes multiple lenses arranged in a housing 161, and the reflective polarizing optical element 10 according to the first embodiment can be used for at least one of these lenses.

[0076] (display device) 17(a) to 17(c) are schematic diagrams showing the configuration of a head-mounted display (HMD) 170, which is an example of a preferred embodiment of a display device using the reflective polarization optical element 10 according to the first embodiment. FIG. 17(a) is a side view showing the HMD 170. FIG. 17(b) is a front view showing the HMD 170. FIG. 17(c) is a schematic diagram showing the optical system of the HMD 170.

[0077] 17(a) and 17(b), the HMD 170 has a housing 171, a wearing device 172, and display units 173 for the left and right eyes that are disposed within the housing 171. The HMD 170 is worn on the user's head by the wearing device 172 so that the display units 173 for the left and right eyes are positioned corresponding to the user's left and right eyes, respectively.

[0078] As shown in FIG. 17( c), each display unit 173 includes a display panel 174 and optical elements 10, 175, and 176. The optical system may include, for example, the reflective polarizing optical element 10 according to the first embodiment. The display panel 174 is a display unit including an organic electroluminescence (EL) panel, a liquid crystal panel, or the like, and displays an image for the corresponding left or right eye. The optical elements 10, 175, and 176 focus the image light emitted from the display panel 174 at the position of the user's eye E. Depending on the design of the HMD 170, the optical elements 10, 175, and 176 may include a transmissive optical element such as a convex lens or a concave lens, a reflective optical element such as a concave mirror, a mirror, a light path changing element such as a half mirror, or a phase difference optical element. The reflective polarizing optical element 10 is installed so as to be positioned between the optical element 175, the optical element 176, and the eye E. The reflective polarizing optical element 10, together with optical elements 175 and 176, constitutes an optical system that guides image light, which is light emitted from the display panel 174, to the user's eyes, and functions as at least one of the optical elements, i.e., lenses, in the optical system.

[0079] Although the embodiment using an HMD has been described as a display device to which the reflective polarizing optical element is applied, the display device according to the present embodiment is not limited to this example. For example, the reflective polarizing optical element 10 according to the present embodiment can also be used in a display device such as a projector, as in the above-described example.

[0080] As described above, a reflective polarizing optical element according to one embodiment of the present invention includes a substrate and a reflective polarizing film having a wire grid structure, such as the wire grid film 12. For example, the substrate 11 has a curved surface portion 11a whose surface forms a curved surface. The curved surface portion can have a shape surrounded by multiple arcs, each of which forms part of the same circle, and lines connecting the ends of adjacent arcs in a planar view in the optical axis direction, as in the substrates 11-2 and 11-3 illustrated in FIG. 2(a) or 2(b). In such a case, the shortest diameter passing through the center of the circle in a planar view is defined as the minor diameter. Furthermore, the curved surface portion can have a shape formed by an outline including multiple arcs with different curvatures in a planar view in the optical axis direction, as in the substrate 11-4 illustrated in FIG. 2(c). In such a case, the shortest diameter passing through the centroid of the outline in a planar view is defined as the minor diameter. The reflective polarizing film is attached to the curved surface so that the angle between the arrangement direction of the wires in the wire grid and the extension direction of the minor axis of the substrate is within 45°. By achieving this positional relationship between the extension direction of the minor axis of the substrate and the arrangement direction of the wires, it is possible to reduce the areas where the spacing between the wires is widened, and to reduce partial deterioration of the polarization transmission characteristics of the reflective polarizing optical element.

[0081] To achieve the effects of the present invention, it is more preferable that the angle between the wire arrangement direction and the extension direction of the minor axis of the substrate be within 30°. By making the wire arrangement direction and the extension direction of the minor axis closer to parallel, partial degradation of the polarization transmission characteristics can be more effectively reduced. To achieve the effects of the present invention, it is also preferable that the half-angle defined by the minor axis and the major axis defined relative to the minor axis be within a predetermined range. In this case, θ1 is the half-angle at the position where the minor axis of the curved surface portion 11a is defined. The major axis is the longest diameter among the diameters passing through the center point of a circle constituting part of the contour of the curved surface portion in a planar view, or the longest diameter among the diameters passing through the centroid of the contour. The half-angle at the position of the curved surface portion where the major axis is defined in a planar view is θ2. By satisfying the conditions 0°<θ1≦12° and 5°≦θ2≦20° for θ1<θ2, the polarization transmission characteristics of the reflective polarization optical element can be more effectively maintained. It is more preferable that the half aperture angle of the substrate satisfies 0°<θ1≦5° and 5°≦θ2≦11°.

[0082] In the present invention, the spacing between wires in the wire grid film also determines a more favorable condition from the viewpoint of maintaining polarized light transmission characteristics. That is, when the reflective polarizing film is attached to a substrate, the minimum wire spacing between adjacent wires is p1 and the maximum wire spacing is p2, and it is more preferable that p2 / p1≦1.18. Furthermore, when the spacing between adjacent wires in the central region of the curved surface portion is q1 and the wire spacing in the region close to the outer periphery of the curved surface portion is q2, it is more preferable that q2 / q1≦1.18.

[0083] In the present invention, for example, the substrate 11 can have a peripheral portion 11b provided on the periphery of the curved portion 11a, as illustrated in Fig. 1. Having such a peripheral portion 11b provides the advantage of improving the degree of freedom when fixing the reflective polarizing optical element to an optical device. Furthermore, as illustrated in Fig. 7, the reflective polarizing film can be attached to the curved portion via an adhesive layer 75. This reduces material constraints that may arise when heating the reflective polarizing film.

[0084] The present invention can also provide an optical device (160, 170) including a housing (161, 171) and an optical system disposed within the housing and having at least one optical element including, for example, the above-described reflective polarization optical element 10. Furthermore, the present invention can provide a display device including a housing 171, an optical system (10, 175, 176) disposed within the housing and having at least one optical element, and a display unit (174) that emits light guided by the optical system.

[0085] A method for manufacturing a reflective polarizing optical element according to one embodiment of the present invention includes attaching a reflective polarizing film for a polarizing beam splitter having a wire grid structure to a substrate having a curved surface portion that forms a curved surface. In this case, when viewed in a plan view along the optical axis, if the curved surface portion has a shape as exemplified in FIG. 2(a) or 2(b), the shortest diameter among the diameters passing through the center point of a single circle that constitutes multiple arcs in the plan view can be defined as the minor diameter. Furthermore, if the curved surface portion has a shape as exemplified in FIG. 2(c), the shortest diameter among the diameters passing through the centroid point in the plan view of an outline including multiple arcs with different curvatures can be defined as the minor diameter. The reflective polarizing film is attached to the curved surface such that the angle between the wire arrangement direction and the extension direction of the minor diameter of the substrate is within 45°. Furthermore, for example, if the curved surface portion has a convex shape, the extension direction of the minor diameter can also be defined as the extension direction in a plan view of a line connecting the point on the curved surface where the reflective polarizing film first comes into contact and the point on the circumference of the curved surface where the reflective polarizing film first arrives. Furthermore, when the curved surface portion is concave, the extension direction of the minor axis can also be defined as the direction that forms the shortest distance between the point on the circumference of the curved surface that the reflective polarizing film first comes into contact with when attached, and a point on the curved surface at the time attachment is completed, such as the centroid of the curved surface portion.

[0086] When attaching the reflective polarizing film to the curved surface, as described with reference to Fig. 8(a), the substrate 61 can be positioned so that the tangent at the center point of the minor axis 61c of the curved surface 61a is parallel to the reflective polarizing film (62). Specifically, a tilted platform with a triangular cross section is added between the stage 65 and the substrate 61, so that the substrate 61 is supported at an angle. This allows the points where the reflective polarizing film first and last contact the curved surface to be half the minor axis during attachment, making it possible to stretch the film in the minor axis direction to the desired length.

[0087] When attaching a reflective polarizing film to a curved surface, the effect of the present invention can be more suitably achieved by making the angle between the arrangement direction of the wires and the extension direction of the minor axis of the substrate 30° or less.

[0088] The reflective polarizing optical element according to one embodiment of the present invention can also be obtained by other methods. For example, a reflective polarizing film for a polarizing beam splitter having a wire grid structure may be attached to the curved surface of a substrate, and then the portion with poor polarization transmission characteristics may be removed. In this case, the portion with poor polarization transmission characteristics is located at an angle of ±22.5° or less with respect to the wire arrangement direction of the reflective polarizing film. Therefore, the reflective polarizing optical element according to one embodiment of the present invention can be obtained by removing at least one edge of the curved portion corresponding to this portion. In this case, a more suitable reflective polarizing optical element can be obtained by removing at least one edge of the substrate at an angle of ±15° or less with respect to the wire arrangement direction of the reflective polarizing film.

[0089] The reflective polarizing film can be attached to the curved surface by pressing the reflective polarizing film against the substrate. The reflective polarizing film can also be attached to the curved surface in a heated state.

[0090] The above-mentioned invention includes the following configurations and methods. (Configuration 1) a substrate having a curved surface portion that forms a curved surface, wherein, in a plan view seen in the optical axis direction, when the curved surface portion has a shape surrounded by a plurality of arcs each forming a part of the same circle in the plan view and a line connecting ends of adjacent arcs among the plurality of arcs, the shortest diameter among diameters passing through the center point of the circle in the plan view is defined as the minor diameter, and when the curved surface portion has a shape formed by an outline including a plurality of arcs with different curvatures, the shortest diameter among diameters passing through the centroid point of the outline in the plan view is defined as the minor diameter; a reflective polarizing film for a polarizing beam splitter having a wire grid structure, the reflective polarizing film being attached to the curved surface portion such that the angle between the arrangement direction of the wires in the reflective polarizing film and the extension direction of the minor axis of the substrate is within 45°; A reflective polarizing optical element comprising: (Configuration 2) 2. The reflective polarizing optical element according to configuration 1, wherein the angle formed between the arrangement direction of the wires and the extension direction of the minor axis of the substrate is within 30°. (Configuration 3) The reflective polarizing optical element according to configuration 1 or 2, wherein θ1 is the half-angle at the position where the minor axis of the curved surface portion is defined, and θ2 is the half-angle at the position of the curved surface portion where the major axis is defined in the planar view as the longest diameter among the diameters passing through the center point of the circle or the longest diameter among the diameters passing through the centroid point of the outer shape, and the relationship 0°<θ1≦12° and 5°≦θ2≦20° is satisfied in θ1<θ2. (Configuration 4) 4. The reflective polarizing optical element according to configuration 3, wherein the half aperture angles of the substrates satisfy the conditions 0°<θ1≦5° and 5°≦θ2≦11°. (Configuration 5) A reflective polarizing optical element according to any one of configurations 1 to 4, wherein, when the minimum wire spacing between adjacent wires in the reflective polarizing film in an attached state is p1 and the maximum wire spacing is p2, p2 / p1≦1.18. (Configuration 6) 6. The reflective polarizing optical element according to any one of configurations 1 to 5, wherein, in the reflective polarizing film in an attached state, when the distance between adjacent wires in the central region of the curved portion is q1 and the distance between wires in the region of the curved portion close to the outer periphery of the shape is q2, q2 / q1≦1.18. (Configuration 7) 7. The reflective polarizing optical element according to any one of configurations 1 to 6, wherein the substrate has a peripheral portion provided on the periphery of the curved surface portion. (Configuration 8) 8. The reflective polarizing optical element according to any one of configurations 1 to 7, wherein the reflective polarizing film is attached to the curved surface portion via an adhesive layer. (Configuration 9) The housing and an optical system having at least one optical element disposed within the housing; The optical device includes the reflective polarizing optical element according to any one of the first to eighth aspects. (Configuration 10) The housing and an optical system having at least one optical element disposed within the housing; a display unit that emits light guided by the optical system, 9. A display device, wherein the optical element includes the reflective polarizing optical element according to any one of configurations 1 to 8. (Method 1) In a substrate having a curved surface portion whose surface forms a curved surface, when the curved surface portion has a shape surrounded by a plurality of arcs each forming a part of the same circle in the plan view as seen in the optical axis direction and a line connecting ends of adjacent arcs among the plurality of arcs, the shortest diameter among diameters passing through the center point of the circle in the plan view is defined as the minor diameter, and when the curved surface portion has a shape formed by an outline including a plurality of arcs with different curvatures, the shortest diameter among diameters passing through the centroid point of the outline in the plan view is defined as the minor diameter; a reflective polarizing film for a polarizing beam splitter having a wire grid structure is attached to the curved surface portion so that the angle between the arrangement direction of the wires in the reflective polarizing film and the extension direction of the minor axis of the substrate is within 45°; A method for manufacturing a reflective polarizing optical element, comprising: (Method 2) The method for manufacturing a reflective polarizing optical element described in Method 1, wherein, when the reflective polarizing film is attached to the curved surface portion, the substrate is positioned so that a tangent to the center point of the minor axis of the curved surface portion is parallel to the reflective polarizing film. (Method 3) A method for manufacturing a reflective polarizing optical element described in Method 1 or 2, wherein when the reflective polarizing film is attached to the curved surface portion, the angle between the arrangement direction of the wires and the extension direction of the minor axis of the substrate is within 30°. (Method 4) A reflective polarizing film for a polarizing beam splitter having a wire grid structure is attached to a curved surface portion of a substrate having a curved surface; After the attachment, removing at least one end of the curved surface portion at an angle of ±22.5° or less with respect to the wire arrangement direction of the reflective polarizing film; A method for manufacturing a reflective polarizing optical element, comprising: (Method 5) A method for producing a reflective polarizing optical element according to Method 4, wherein the removal of at least one edge of the substrate is performed on the edge of the curved portion at an angle of within ±15° with respect to the wire arrangement direction of the reflective polarizing film. (Method 6) 6. A method for producing a reflective polarizing optical element according to any one of methods 1 to 5, comprising pressing the reflective polarizing film against the substrate to attach the reflective polarizing film to the curved surface portion. (Method 7) The method for producing a reflective polarizing optical element according to any one of Methods 1 to 6, wherein the reflective polarizing film is attached to the curved surface portion in a heated state. (Method 8) The method includes attaching a reflective polarizing film for a polarizing beam splitter having a wire grid structure to a substrate having a curved surface portion that forms a curved surface, A method for manufacturing a reflective polarizing optical element, wherein, when attaching the reflective polarizing film, the angle formed by the extension direction of a line connecting a point on the curved surface where the reflective polarizing film first comes into contact and a point on the circumference of the curved surface where the reflective polarizing film first arrives, in a planar view of the substrate viewed in the optical axis direction, and the arrangement direction of wires in the wire grid structure is within 45°.

[0091] Although the present invention has been described above with reference to embodiments and examples, the present invention is not limited to the above-described embodiments and examples. Inventions modified within the scope of the present invention and inventions equivalent to the present invention are also included in the present disclosure. Furthermore, the above-described examples can be combined as appropriate within the scope of the present invention. [Explanation of symbols]

[0092] 10 60 150: Polarized optical elements 11 61 91 121 131 141: PCB 11a 61a 91a 121a 141a: Curved part 11b 61b 121b 131b: Periphery of the substrate 11c 61c 91c 121c 131c 141c: Minor diameter 11d 61d 91d 121d 131d 141d: Major diameter 12 32 62 92: Wire grid film 12a 32a 62a 92a: Wire arrangement direction 12b 32b 62b 92b: Wire extension direction 63: First Chamber 64: Second Chamber 65: Stage 75: Adhesive layer 76: Protective film 77: Support Film 170: Head-Mounted Display (HMD) 171: HMD housing 172: HMD mounting device 173: HMD display unit 174: HMD display panel 175 176: HMD optical system E: User's Eyes

Claims

1. a substrate having a curved surface portion that forms a curved surface, wherein, in a plan view seen in the optical axis direction, when the curved surface portion has a shape surrounded by a plurality of arcs each forming a part of the same circle in the plan view and a line connecting ends of adjacent arcs among the plurality of arcs, the shortest diameter among diameters passing through the center point of the circle in the plan view is defined as the minor diameter, and when the curved surface portion has a shape formed by an outline including a plurality of arcs with different curvatures, the shortest diameter among diameters passing through the centroid point of the outline in the plan view is defined as the minor diameter; a reflective polarizing film for a polarizing beam splitter having a wire grid structure, the reflective polarizing film being attached to the curved surface portion such that an angle between an arrangement direction of wires in the reflective polarizing film and an extension direction of the minor axis of the substrate is within 45°; A reflective polarizing optical element comprising:

2. 2. The reflective polarizing optical element according to claim 1, wherein the angle formed between the arrangement direction of the wires and the extension direction of the minor axis of the substrate is within 30 degrees.

3. 2. The reflective polarizing optical element of claim 1, wherein, when θ1 is the half-angle at the position where the minor axis of the curved surface portion is defined, and θ2 is the half-angle at the position of the curved surface portion where the major axis is defined in the planar view as the longest diameter among the diameters passing through the center point of the circle or the longest diameter among the diameters passing through the centroid point of the outline, the reflective polarizing optical element satisfies 0°<θ1≦12° and 5°≦θ2≦20° in θ1<θ2.

4. 4. The reflective polarizing optical element according to claim 3, wherein the half aperture angles of the substrates satisfy 0°<θ1≦5° and 5°≦θ2≦11°.

5. 2. The reflective polarizing optical element of claim 1, wherein, when the minimum wire spacing between adjacent wires in the reflective polarizing film in the attached state is p1 and the maximum wire spacing is p2, p2 / p1≦1.

18.

6. The reflective polarizing optical element of claim 1, wherein when the reflective polarizing film is attached, the distance between adjacent wires in the central region of the curved portion is q1, and the distance between wires in the region close to the outer periphery of the shape of the curved portion is q2, and q2 / q1 is 1.

18.

7. The reflective polarizing optical element according to claim 1 , wherein the substrate has a peripheral edge portion provided on a peripheral edge of the curved surface portion.

8. The reflective polarizing optical element according to claim 1 , wherein the reflective polarizing film is attached to the curved surface portion via an adhesive layer.

9. The housing and an optical system having at least one optical element disposed within the housing; An optical instrument, wherein the optical element comprises a reflective polarizing optical element according to any one of claims 1 to 8.

10. The housing and an optical system having at least one optical element disposed within the housing; a display unit that emits light guided by the optical system, A display device, wherein the optical element comprises a reflective polarizing optical element according to claim 1 .

11. In a substrate having a curved surface portion whose surface forms a curved surface, when the curved surface portion has a shape surrounded by a plurality of arcs each forming a part of the same circle in the planar view as seen in the optical axis direction and a line connecting ends of adjacent arcs among the plurality of arcs, the shortest diameter among diameters passing through the center point of the circle in the planar view is defined as the minor diameter, and when the curved surface portion has a shape formed by an outline including a plurality of arcs with different curvatures, the shortest diameter among diameters passing through the centroid point of the outline in the planar view is defined as the minor diameter; a reflective polarizing film for a polarizing beam splitter having a wire grid structure is attached to the curved surface portion such that the angle between the arrangement direction of the wires in the reflective polarizing film and the extension direction of the minor axis of the substrate is within 45°; A method for manufacturing a reflective polarizing optical element, comprising:

12. The method for manufacturing a reflective polarizing optical element described in claim 11, wherein when the reflective polarizing film is attached to the curved surface portion, the substrate is positioned so that a tangent to the center point of the minor axis of the curved surface portion is parallel to the reflective polarizing film.

13. The method for manufacturing a reflective polarizing optical element described in claim 11, wherein when the reflective polarizing film is attached to the curved surface portion, the angle between the arrangement direction of the wires and the extension direction of the minor axis of the substrate is within 30°.

14. A reflective polarizing film for a polarizing beam splitter having a wire grid structure is attached to a curved surface portion of a substrate having a curved surface; After the attachment, removing at least one end of the curved surface portion at an angle of ±22.5° or less with respect to the wire arrangement direction of the reflective polarizing film; A method for manufacturing a reflective polarizing optical element, comprising:

15. The method for manufacturing a reflective polarizing optical element described in claim 14, wherein the removal of at least one edge of the substrate is performed on the edge of the curved portion at an angle of within ±15° with respect to the wire arrangement direction of the reflective polarizing film.

16. The method for manufacturing a reflective polarizing optical element according to claim 11 , further comprising: attaching the reflective polarizing film to the curved surface portion by pressing the reflective polarizing film against the substrate.

17. The method for manufacturing a reflective polarizing optical element according to claim 11 , wherein the reflective polarizing film is attached to the curved surface portion in a heated state.

18. The method includes attaching a reflective polarizing film for a polarizing beam splitter having a wire grid structure to a substrate having a curved surface portion that forms a curved surface, A method for manufacturing a reflective polarizing optical element, wherein, when attaching the reflective polarizing film, the angle formed by the extension direction of a line connecting a point on the curved surface where the reflective polarizing film first comes into contact and a point on the circumference of the curved surface where the reflective polarizing film first arrives, in a planar view when the substrate is viewed in the optical axis direction, and the arrangement direction of wires in the wire grid structure is within 45°.

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