Optical system, display device, and head-mount device

Abstract

To provide an optical system that can be downsized, is manufacturable at low cost, and has large positive power, and a display device and a head-mount device provided with the optical system.SOLUTION: The optical system comprises: a half mirror; at least one first optical element including a first film-like optical element which is pasted to a first plain surface; at least one second optical element including a second film-like optical element which is pasted to a second plain surface, located at a position symmetrical to the position where the at least one first optical element is located, with regard to the half mirror, and having a shape symmetrical to the shape of the at least one first optical element, with regard to the half mirror; and a convex lens.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 discloses an optical element. In the optical element, first linearly polarized light is transmitted through a first reflective linear polarizer and then through a first retardation plate to be changed into right-handed circularly polarized light. A part of the right-handed circularly polarized light is reflected by a partial reflection mirror to be changed into left-handed circularly polarized light. A part of the right-handed circularly polarized light is transmitted through the partial reflection mirror.

[0003] The left-handed circularly polarized light reflected by the partial reflection mirror passes through the first retardation plate and is changed into the second linearly polarized light. The second linearly polarized light is reflected by the first reflective linear polarizer, passes through the first retardation plate and is changed into the left-handed circularly polarized light. The left-handed circularly polarized light passes through the partial reflection mirror and the second retardation plate and is changed into the second linearly polarized light. The second linearly polarized light passes through the second reflective linear polarizer.

[0004] The right-handed circularly polarized light that has passed through the partial reflection mirror passes through the second retardation plate and is changed into a first linearly polarized light. The first linearly polarized light is reflected by the second reflective linear polarizer, passes through the second retardation plate and is changed into right-handed circularly polarized light. The right-handed circularly polarized light is reflected by the partial reflection mirror and is changed into left-handed circularly polarized light. The left-handed circularly polarized light passes through the second retardation plate and is changed into a second linearly polarized light. The second linearly polarized light passes through the second reflective linear polarizer.

[0005] As a result, the optical path length can be increased and the optical elements can be made smaller (paragraphs 0016 and 0026-0036). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2021 / 200428 Summary of the Invention [Problem to be solved by the invention]

[0007] A reflective linear polarizing plate is generally a film-like optical element that is attached to the surface of a lens.

[0008] In the optical element disclosed in Patent Document 1, when the reflective linear polarizing plate is attached to the convex lens surface, a bonding device capable of bonding the film-like optical element to the convex lens surface is required. This increases the cost required for the equipment for manufacturing the optical element. In addition, in the optical element disclosed in Patent Document 1, when the reflective linear polarizing plate is attached to the convex lens surface, problems such as air bubbles being trapped between the reflective linear polarizing plate and the convex lens surface, and wrinkles and sagging of the reflective linear polarizing plate are likely to occur. This reduces the yield of the optical element, and increases the cost required for manufacturing the optical element. On the other hand, in the optical element disclosed in Patent Document 1, when the reflective linear polarizing plate is attached to the flat lens surface, the positive power of the optical element is insufficient.

[0009] In view of these problems, one aspect of the present disclosure has been made. An object of one aspect of the present disclosure is to provide, for example, an optical system that can be miniaturized, requires low manufacturing costs, and has a large positive power, as well as a display device and a head-mounted device that include the optical system. [Means for solving the problem]

[0010] The optical system of the first aspect of the present disclosure includes at least one first optical element including a half mirror having a first surface and a second surface on opposite sides, and a first film-like optical element attached to a first plane, the first film-like optical element having a third surface and a fourth surface on opposite sides, the third surface facing the first surface, the first film-like optical element emitting a first circularly polarized light having a first rotation direction from the third surface when a first linearly polarized light having a first polarization direction is incident on the fourth surface, and emitting a third circularly polarized light having the second rotation direction from the third surface when a second circularly polarized light having a second rotation direction different from the first rotation direction is incident on the third surface, and a second film-like optical element attached to a second plane, the first film-like optical element having a fifth surface and a fourth surface on opposite sides, the third surface facing the first surface, the first film-like optical element having a fifth surface and a fourth surface on opposite sides, the third surface facing the first surface, the first film-like optical element having a fifth surface and a fourth surface on opposite sides, the third surface facing the first surface, and a sixth surface, the fifth surface facing the second surface, a fifth circularly polarized light having the first polarization direction is emitted from the fifth surface when a fourth circularly polarized light having the first rotation direction is incident on the fifth surface, and a second linearly polarized light having a second polarization direction perpendicular to the first polarization direction is emitted from the sixth surface when a sixth circularly polarized light having the second rotation direction is incident on the fifth surface, the second linearly polarized light having a second polarization direction perpendicular to the first polarization direction is emitted from the sixth surface, the second at least one optical element being arranged at a position symmetrical to a position at which the first at least one optical element is arranged with respect to the half mirror and having a shape symmetrical to a shape of the first at least one optical element with respect to the half mirror, and a convex lens that transmits the second linearly polarized light.

[0011] A display device according to a second aspect of the present disclosure includes the optical system according to the first aspect of the present disclosure and a display that emits the first linearly polarized light.

[0012] A head-mounted device according to a third aspect of the present disclosure includes the display device according to the second aspect of the present disclosure. [Brief description of the drawings]

[0013] [Figure 1] 1 is a front view showing a schematic diagram of a head-mounted device of a first embodiment and a human head on which the head-mounted device is worn. [Diagram 2]2 is a cross-sectional view illustrating a display device provided in the head-mounted device of the first embodiment. FIG. [Diagram 3] 5A to 5C are diagrams showing changes in the polarization state in a display device provided in the head-mounted device of the first embodiment. [Figure 4] A figure showing the relationship between the first transmission axis and the first reflection axis of a first reflective polarizing plate provided in the head-mounted device of the first embodiment, and the second transmission axis and the second reflection axis of a second reflective polarizing plate provided in the head-mounted device. [Diagram 5] FIG. 1 is a diagram showing the relationship between a first fast axis and a first slow axis of a first quarter-wave plate provided in a head-mounted device of the first embodiment, and a second fast axis and a second slow axis of a second quarter-wave plate provided in the head-mounted device. [Figure 6] 11 is a cross-sectional view illustrating a display device provided in a head-mounted device of a second embodiment. FIG. [Figure 7] 11 is a cross-sectional view illustrating a display device provided in a head-mounted device of a third embodiment. FIG. [Figure 8] 13 shows the relationship between a first rotation direction of a first cholesterol liquid crystal film provided in a head-mounted device of the third embodiment and a second rotation direction of a second cholesterol liquid crystal film provided in the head-mounted device, as well as the relationship between a first rotation direction of a first polarizing volume hologram (PVH) film provided in a head-mounted device of the fourth embodiment and a second rotation direction of a second PVH film provided in the head-mounted device. [Figure 9] 13 is a cross-sectional view illustrating a display device provided in a head-mounted device of a fourth embodiment. FIG. [Figure 10] 13 is a cross-sectional view illustrating a schematic diagram of a display device provided in a head-mounted device of a fifth embodiment. FIG. [Figure 11] 13 is a cross-sectional view illustrating a schematic diagram of a display device provided in a head-mounted device of a sixth embodiment. FIG. [Figure 12] 13 is a cross-sectional view illustrating a schematic diagram of a display device provided in a head-mounted device of a seventh embodiment. FIG. [Figure 13]13 is a cross-sectional view illustrating a schematic diagram of a display device provided in a head-mounted device of an eighth embodiment. FIG. [Figure 14] FIG. 13 is a cross-sectional view illustrating a display device provided in a head-mounted device of a ninth embodiment. [Figure 15] FIG. 1 is a cross-sectional view that diagrammatically illustrates a display device of a first reference example. [Figure 16] FIG. 11 is a diagram showing a change in polarization state in a display device of a first reference example. [Figure 17] FIG. 11 is a cross-sectional view that diagrammatically illustrates a display device of a second reference example. [Figure 18] FIG. 11 is a diagram showing a change in polarization state in a display device of a second reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0015] 1 First reference example In the following, in order to facilitate understanding of the display device provided in the head-mounted device of the first embodiment, a display device of a first reference example will be described.

[0016] Fig. 15 is a cross-sectional view that typically illustrates the display device of the first reference example, and Fig. 16 is a diagram showing changes in the polarization state in the display device of the first reference example.

[0017] A display device 82 of a first reference example shown in Fig. 15 and Fig. 16 includes a thin pancake lens. The pancake lens employs a single-path method in which light is guided to the eye E via a single optical path.

[0018] As shown in FIGS. 15 and 16, the display device 82 includes a display 801 , a quarter-wave plate 802 , a half mirror 803 , a quarter-wave plate 804 , and a reflective polarizing plate 805 .

[0019] A display 801, a quarter wave plate 802, a half mirror 803, a quarter wave plate 804 and a reflective polarizer 805 are arranged in a line in the order listed.

[0020] The display 801 emits linearly polarized light 881 having a first polarization direction D1.

[0021] The quarter-wave plate 802 transmits linearly polarized light 881 and emits circularly polarized light 882 having a first rotation direction DR.

[0022] The half mirror 803 transmits a portion of the circularly polarized light 882 and emits circularly polarized light 883 having a first rotation direction DR.

[0023] The quarter-wave plate 804 transmits the circularly polarized light 883 and emits linearly polarized light 884 having a first polarization direction D1.

[0024] The reflective polarizing plate 805 reflects the linearly polarized light 884 and outputs linearly polarized light 885 having a first polarization direction D1.

[0025] The quarter-wave plate 804 transmits linearly polarized light 885 and emits circularly polarized light 886 having a first rotation direction DR.

[0026] The half mirror 803 reflects a portion of the circularly polarized light 886 and emits circularly polarized light 887 having a second rotation direction DL.

[0027] The quarter-wave plate 804 transmits the circularly polarized light 887 and outputs linearly polarized light 888 having a second polarization direction D2.

[0028] The reflective polarizing plate 805 transmits linearly polarized light 888 and emits linearly polarized light 889 having a second polarization direction D2.

[0029] Linearly polarized light 889 reaches eye E.

[0030] In the display device 82, light travels back and forth between the half mirror 803 and the reflective polarizing plate 805. This makes it possible to lengthen the optical path of the light. As a result, the optical system including the quarter-wave plate 802, the half mirror 803, the quarter-wave plate 804, and the reflective polarizing plate 805 becomes a thin pancake lens.

[0031] In the display device 82, the half mirror 803 reflects a part of the circularly polarized light 882, resulting in a loss of about 50% of the amount of light. Also, the half mirror 803 transmits a part of the circularly polarized light 886, resulting in a loss of about 25% of the amount of light. Therefore, overall, about 75% of the amount of light is lost.

[0032] 15 , a display device 82 includes lenses 811 and 812. A quarter-wave plate 802 is attached to the display surface of the display 801. A half mirror 803 is attached to the convex lens surface of the lens 811. A quarter-wave plate 804 and a reflective polarizing plate 805 are attached to the flat lens surface of the lens 812.

[0033] 2 Second reference example In the following, in order to facilitate understanding of the display device provided in the head-mounted device of the first embodiment, a display device of a second reference example will be described.

[0034] Fig. 17 is a cross-sectional view that illustrates a schematic diagram of a display device of the second reference example, and Fig. 18 is a diagram showing a change in the polarization state in the display device of the second reference example.

[0035] A display device 92 of a second reference example shown in Fig. 17 and Fig. 18 includes a thin pancake lens. The pancake lens employs a double-path method in which light is guided to the eye E via two different optical paths.

[0036] As shown in FIGS. 17 and 18, the display device 92 includes a display 901 , a reflective polarizing plate 902 , a quarter-wave plate 903 , a half mirror 904 , a quarter-wave plate 905 , and a reflective polarizing plate 906 .

[0037] A display 901, a reflective polarizer 902, a quarter-wave plate 903, a half mirror 904, a quarter-wave plate 905, and a reflective polarizer 906 are arranged in the order shown in one example.

[0038] The display 901 emits linearly polarized light 981 having a first polarization direction D1.

[0039] The reflective polarizing plate 902 transmits linearly polarized light 981 and emits linearly polarized light 982 having a first polarization direction D1.

[0040] The quarter-wave plate 903 transmits linearly polarized light 982 and emits circularly polarized light 983 having a first rotation direction DR.

[0041] The half mirror 904 reflects a portion of the circularly polarized light 983 to emit circularly polarized light 984p having a second rotation direction DL. The half mirror 904 also transmits a portion of the circularly polarized light 983 to emit circularly polarized light 984q having a first rotation direction DR.

[0042] The quarter-wave plate 903 transmits the circularly polarized light 984p and outputs linearly polarized light 985p having a second polarization direction D2.

[0043] The reflective polarizer 902 reflects the linearly polarized light 985p and outputs linearly polarized light 986p having a second polarization direction D2.

[0044] The quarter-wave plate 903 transmits the linearly polarized light 986p and emits circularly polarized light 987p having a second rotation direction DL.

[0045] The half mirror 904 transmits a portion of the circularly polarized light 987p and emits the circularly polarized light 988p having the second rotation direction DL.

[0046] The quarter-wave plate 905 transmits the circularly polarized light 988p and outputs linearly polarized light 989p having a second polarization direction D2.

[0047] The reflective polarizing plate 906 transmits the linearly polarized light 989p and outputs linearly polarized light 990p having a second polarization direction D2.

[0048] The quarter-wave plate 905 transmits the circularly polarized light 984q and outputs linearly polarized light 985q having a first polarization direction D1.

[0049] The reflective polarizer 906 reflects the linearly polarized light 985q and outputs linearly polarized light 986q having a first polarization direction D1.

[0050] The quarter-wave plate 905 transmits linearly polarized light 986q and emits circularly polarized light 987q having a first rotation direction DR.

[0051] The half mirror 904 reflects a portion of the circularly polarized light 987q and emits circularly polarized light 988q having a second rotation direction DL.

[0052] The quarter-wave plate 905 transmits the circularly polarized light 988q and outputs linearly polarized light 989q having a second polarization direction D2.

[0053] The reflective polarizing plate 906 transmits linearly polarized light 989q and outputs linearly polarized light 990q having a second polarization direction D2.

[0054] Linearly polarized light 890p and 890q reaches eye E.

[0055] The reflective polarizing plate 902, the quarter-wave plate 903, the half mirror 904, the quarter-wave plate 905, and the reflective polarizing plate 906 are designed to be symmetrical with respect to the half mirror 904. This makes it possible to prevent the image formed on the eye E from becoming a double image.

[0056] In the display device 92, a part of the light travels back and forth between the half mirror 904 and the reflective polarizing plate 902. In addition, a part of the light travels back and forth between the half mirror 904 and the reflective polarizing plate 906. This makes it possible to lengthen the optical path of the light. As a result, the optical system including the reflective polarizing plate 902, the quarter-wave plate 903, the half mirror 904, the quarter-wave plate 905, and the reflective polarizing plate 906 becomes a thin pancake lens.

[0057] In the display device 92, the half mirror 904 reflects a portion of the circularly polarized light 987q, causing a loss of approximately 25% of the amount of light. In addition, the reflective polarizing plate 902 transmits a portion of the linearly polarized light 985p, causing a loss of approximately 25% of the amount of light. As a result, approximately 50% of the amount of light is lost overall. Therefore, the amount of light lost in the display device 92 is less than the amount of light lost in the display device 82.

[0058] As illustrated in FIG. 17, the display device 92 includes a lens 911, a lens 912, and a glass plate 913. The reflective polarizing plate 902 is attached to the convex lens surface of the lens 911. The quarter-wave plate 903, the half mirror 904, and the quarter-wave plate 905 are attached to the main surface of the glass plate 913. The reflective polarizing plate 906 is attached to the convex lens surface of the lens 912. The quarter-wave plate 903 may be disposed between the half mirror 904 and the reflective polarizing plate 902. Therefore, the quarter-wave plate 903 may be attached to the convex lens surface of the lens 911. The quarter-wave plate 905 may be disposed between the half mirror 904 and the reflective polarizing plate 906. Therefore, the quarter-wave plate 905 may be attached to the convex lens surface of the lens 912.

[0059] In the display device 92, the reflective polarizing plates 902 and 906 are attached to the convex lens surfaces of the lenses 911 and 912, respectively. For this reason, a bonding device capable of bonding a film-like optical element to a convex lens surface is required. For this reason, the cost required for the equipment for manufacturing the display device 92 is high. In addition, problems occur such as air bubbles being trapped between the reflective polarizing plate 902 and the lens 911, air bubbles being trapped between the reflective polarizing plate 906 and the lens 912, wrinkles, sagging, etc. occurring in the reflective polarizing plate 902, and wrinkles, sagging, etc. occurring in the reflective polarizing plate 906. For this reason, the yield of the display device 92 is low, and the cost required for manufacturing the display device 92 is high.

[0060] 3. First embodiment 3.1 Head-mounted equipment FIG. 1 is a front view that illustrates a schematic diagram of a head-mounted device of the first embodiment and a human head on which the head-mounted device is worn.

[0061] The head-mounted device 1 shown in FIG. 1 is worn on a human head H. The head-mounted device 1 is a goggle-type head-mounted device. The head-mounted device 1 may be a head-mounted device other than a goggle-type head-mounted device. For example, the head-mounted device 1 may be a headset-type, glasses-type, or other head-mounted device.

[0062] The head-mounted device 1 displays a virtual reality (VR) image. The head-mounted device 1 may display an image other than a VR image. For example, the head-mounted device 1 may display an augmented reality (AR) image, a mixed reality (MR) image, or the like.

[0063] As shown in FIG. 1, the head-mounted device 1 includes a housing 11 and a display device 12 .

[0064] The housing 11 can be attached to and detached from the head H. The housing 11 houses a display device 12 therein.

[0065] The display device 12 faces the eyes in the head H. The display device 12 displays an image toward the facing eye.

[0066] 3.2 Display device Fig. 2 is a cross-sectional view that illustrates a schematic diagram of a display device provided in the head-mounted device of the first embodiment. Fig. 3 is a diagram illustrating a change in the polarization state in the display device provided in the head-mounted device of the first embodiment.

[0067] 2 and 3 includes a thin pancake lens. The pancake lens employs a double-path method in which light is guided to the eye E via two optical paths.

[0068] As shown in FIG. 2, the display device 12 includes a display 101 and an optical system 102 .

[0069] The display 101 emits a first linearly polarized light (linearly polarized light 181). The display 101 emits the first linearly polarized light (linearly polarized light 181) having a distribution of luminance and chromaticity according to an input video signal. In this way, the display 101 displays an image according to the input video signal. The display 101 has a display surface 101a. The display 101 displays the image on the display surface 101a. The display 101 is a liquid crystal display (LCD), a self-luminous display, or the like.

[0070] The optical system 102 focuses the light emitted by the display 101 onto the eye E. In this way, the optical system 102 forms an image on the eye E that corresponds to the video displayed on the display 101.

[0071] 3.3 Optical system As shown in FIGS. 2 and 3, the optical system 102 includes a transparent plate 111, a half mirror 112, at least one first optical element 113, at least one second optical element 114, a polarizing plate 115, and a convex lens 116.

[0072] Transparent plate 111 is disposed between first at least one optical element 113 and second at least one optical element 114. Transparent plate 111 is disposed between first convex lens surface 123a of first lens 123 of first at least one optical element 113 and second convex lens surface 133a of second lens 133 of second at least one optical element 114.

[0073] The transparent plate 111 has one main surface 111a and the other main surface 111b. The one main surface 111a and the other main surface 111b are located on opposite sides to each other.

[0074] The transparent plate 111 is a glass plate or the like.

[0075] The half mirror 112 is disposed on the other main surface 111b of the transparent plate 111. The half mirror 112 may be disposed on one main surface 111a of the transparent plate 111.

[0076] The half mirror 112 has a first surface 112a and a second surface 112b. The first surface 112a and the second surface 112b are located on opposite sides to each other.

[0077] The first at least one optical element 113 has a third surface 1133 and a fourth surface 1134. The third surface 1133 faces the first surface 112a of the half mirror 112. The fourth surface 1134 faces the display surface 101a of the display 101.

[0078] When a first linearly polarized light (linearly polarized light 181) having a first polarization direction D1 is incident on the fourth surface 1134, the first at least one optical element 113 transmits the incident first linearly polarized light (linearly polarized light 181) and emits a first circularly polarized light (circularly polarized light 183) having a first rotation direction DR from the third surface 1133. When a second circularly polarized light (circularly polarized light 184p) having a second rotation direction DL different from the first rotation direction DR is incident on the third surface 1133, the first at least one optical element 113 reflects the incident second circularly polarized light (circularly polarized light 184p) and emits a third circularly polarized light (circularly polarized light 187p) having the second rotation direction DL from the third surface 1133.

[0079] The second at least one optical element 114 has a fifth surface 1145 and a sixth surface 1146. The fifth surface 1145 faces the second surface 112b of the half mirror 112. The sixth surface 1146 faces the third flat lens surface 116a of the convex lens 116.

[0080] When a fourth circularly polarized light (circularly polarized light 184q) having a first rotation direction DR is incident on the fifth surface 1145, the second at least one optical element 114 reflects the incident fifth circularly polarized light (circularly polarized light 184q) and outputs a fifth circularly polarized light (circularly polarized light 187q) having the first rotation direction DR from the fifth surface 1145. When a sixth circularly polarized light (circularly polarized light 188p and 188q) having a second rotation direction DL is incident on the fifth surface 1145, the second at least one optical element 114 transmits the incident sixth circularly polarized light (circularly polarized light 188p and 188q) and outputs a second linearly polarized light (linearly polarized light 190p and 190q) having a second polarization direction D2 perpendicular to the first polarization direction D1 from the sixth surface 1146.

[0081] As a result, the first at least one optical element 113 transmits linearly polarized light 181 having a first polarization direction D1 and emits circularly polarized light 183 having a first rotation direction DR.

[0082] The half mirror 112 reflects a portion of the circularly polarized light 183 to emit circularly polarized light 184p having the second rotation direction DL. The half mirror 112 also transmits a portion of the circularly polarized light 183 to emit circularly polarized light 184q having the first rotation direction DR.

[0083] The first at least one optical element 113 reflects the circularly polarized light 184p and outputs circularly polarized light 187p having a second rotation direction DL.

[0084] The half mirror 112 transmits a portion of the circularly polarized light 187p and emits circularly polarized light 188p having a second rotation direction DL.

[0085] The second at least one optical element 114 transmits the circularly polarized light 188p and outputs linearly polarized light 190p having a second polarization direction D2.

[0086] The second at least one optical element 114 reflects the circularly polarized light 184q and outputs circularly polarized light 187q having a first rotation direction DR.

[0087] The half mirror 112 reflects a portion of the circularly polarized light 187q, and emits circularly polarized light 188q having a second rotation direction DL.

[0088] The second at least one optical element 114 transmits the circularly polarized light 188q and outputs linearly polarized light 190q having a second polarization direction D2.

[0089] The second at least one optical element 114 is disposed at a position symmetrical to the position at which the first at least one optical element 113 is disposed with respect to the half mirror 112. The second at least one optical element 114 has a shape symmetrical to the shape of the first at least one optical element 113 with respect to the half mirror 112. Being symmetrical with respect to the half mirror 112 means being optically symmetrical, and means being symmetrical with respect to optical characteristics that affect the optical path of light, such as the distribution of refractive index. This allows the optical paths of the linearly polarized light 190p and 190q to coincide with each other. This makes it possible to prevent the image formed by the first at least one optical element 113, the half mirror 112, and the second at least one optical element 114 from becoming a double image.

[0090] The polarizing plate 115 is disposed closer to the eye E than the at least one second optical system 102. As a result, the polarizing plate 115 transmits the linearly polarized light 190p and 190q. The polarizing plate 115 prevents reflected light generated by the user's eye E, face, etc. reflecting the linearly polarized light 190p and 190q from being reflected by the second reflective polarizing plate 131 provided in the at least one second optical system 102 and reaching the user's eye E. As a result, the polarizing plate 115 improves the quality of the image displayed by the display device 12. The polarizing plate 115 may be omitted.

[0091] The convex lens 116 is disposed closer to the eye E than the polarizing plate 115 and the at least one second optical system 102. Thus, the convex lens 116 transmits the second linearly polarized light (linearly polarized light 190p and 190q) that has been transmitted through the polarizing plate 115. The second linearly polarized light (linearly polarized light 190p and 190q) that has been transmitted through the convex lens 116 is guided to the eye E.

[0092] The convex lens 116 is disposed outside the first at least one optical element 113, the half mirror 112, and the second at least one optical element 114, which must have symmetry. This makes it possible to increase the positive power of the optical system 102, and to widen the field of view (FOV) of the optical system 102.

[0093] The convex lens 116 is disposed outside the section between the first reflective polarizer 121 provided in the first at least one optical element 113 and the second reflective polarizer 131 provided in the second at least one optical element 114, which performs polarization compensation. For this reason, the convex lens 116 is allowed to be a lens made of a material having residual birefringence.

[0094] 3.4 First at least one optical element Fig. 4 is a diagram showing the relationship between a first transmission axis and a first reflection axis of a first reflective polarizer provided in the head-mounted device of the first embodiment, and a second transmission axis and a second reflection axis of a second reflective polarizer provided in the head-mounted device. Fig. 5 is a diagram showing the relationship between a first fast axis and a first slow axis of a first quarter-wave plate provided in the head-mounted device of the first embodiment, and a second fast axis and a second slow axis of a second quarter-wave plate provided in the head-mounted device.

[0095] As shown in FIGS. 2 and 3, the first at least one optical element 113 includes a first reflective polarizer 121 , a first quarter-wave plate 122 and a first lens 123 .

[0096] The first reflective polarizing plate 121 is a first film-like optical element. The first reflective polarizing plate 121 has a first main surface 121a and a second main surface 121b. The first main surface 121a and the second main surface 121b are on opposite sides to each other. The second main surface 121b becomes a fourth surface 1134 of the first at least one optical element 113.

[0097] As shown in FIG. 4, the first reflective polarizing plate 121 has a first transmission axis 121c and a first reflection axis 121d. The first transmission axis 121c and the first reflection axis 121d are perpendicular to each other. The first polarization direction D1 is parallel to the first transmission axis 121c. The second polarization direction D2 is parallel to the first reflection axis 121d. As a result, the first reflective polarizing plate 121 selectively transmits linearly polarized light 181 having the first polarization direction D1 and emits linearly polarized light 182 having the first polarization direction D1. In addition, the first reflective polarizing plate 121 selectively reflects linearly polarized light 185p having the second polarization direction D2 and emits linearly polarized light 186p having the second polarization direction D2.

[0098] The first quarter-wave plate 122 is disposed between the half mirror 112 and the first reflective polarizing plate 121 .

[0099] The first quarter wave plate 122 has a first surface 122a and a second surface 122b. The first surface 122a and the second surface 122b are on opposite sides of each other. The first surface 122a becomes the third surface 1133 of the first at least one optical element 113.

[0100] As shown in FIG. 5, the first quarter-wave plate 122 has a first fast axis 122e and a first slow axis 122f. The first fast axis 122e and the first slow axis 122f are perpendicular to each other. The first polarization direction D1 forms an angle of 45° with the first fast axis 122e. The second polarization direction D2 forms an angle of 45° with the first fast axis 122e. As a result, the first quarter-wave plate 122 transmits the linearly polarized light 182 having the first polarization direction D1 and outputs the circularly polarized light 183p having the first rotation direction DR. The first quarter-wave plate 122 also transmits the circularly polarized light 184p having the second rotation direction DL and outputs the linearly polarized light 185p having the second polarization direction D2. The first quarter-wave plate 122 also transmits linearly polarized light 186p having a second polarization direction D2 and emits circularly polarized light 187p having a second rotation direction DL.

[0101] As a result, when linearly polarized light 181 having a first polarization direction D1 is incident on the fourth surface 1134, the first at least one optical element 113 transmits the incident linearly polarized light 181 and emits circularly polarized light 183 having a first rotation direction DR from the third surface 1133. When circularly polarized light 184p having a second rotation direction DL is incident on the third surface 1133, the first at least one optical element 113 reflects the incident circularly polarized light 184p and emits circularly polarized light 187p having the second rotation direction DL from the third surface 1133.

[0102] The first lens 123 is a first plano-convex lens. Therefore, the first lens 123 has a positive power. The first lens 123 has a first convex lens surface 123a and a first planar lens surface 123b. The first convex lens surface 123a and the first planar lens surface 123b are on opposite sides to each other. The first convex lens surface 123a faces the first surface 112a of the half mirror 112. The first convex lens surface 123a may be any of a spherical surface, an aspherical surface, and a free-form surface.

[0103] The first reflective polarizing plate 121 and the first quarter-wave plate 122 are attached to the first flat lens surface 123b of the first lens 123, which is the first flat surface. As a result, the first reflective polarizing plate 121 and the first quarter-wave plate 122 have a flat shape.

[0104] By attaching the first reflective polarizing plate 121 to the first flat lens surface 123b of the first lens 123, a bonding device capable of bonding a film-like optical element to a convex lens surface is not required. This reduces the cost required for equipment for manufacturing the optical system 102. In addition, by attaching the first reflective polarizing plate 121 to the first flat lens surface 123b, problems such as air bubbles being trapped between the first reflective polarizing plate 121 and the first lens 123, and wrinkles and sagging of the first reflective polarizing plate 121 are less likely to occur. This increases the yield of the optical system 102, and reduces the cost required for manufacturing the optical system 102.

[0105] By attaching both the first reflective polarizing plate 121 and the first ¼ wavelength plate 122 to the first lens 123, the first reflective polarizing plate 121 and the first ¼ wavelength plate 122 can be attached to the first lens 123 simply by attaching a laminate of the first reflective polarizing plate 121 and the first ¼ wavelength plate 122 to the first lens 123. This laminate can be easily manufactured. This makes it possible to reduce the cost required for attaching the first reflective polarizing plate 121 and the first ¼ wavelength plate 122 to the first lens 123.

[0106] When first lens 123 is a plano-convex lens, the cost of a mold required to manufacture first lens 123 can be reduced, compared to when first lens 123 is a biconvex lens.

[0107] 3.5 Second at least one optical element As shown in FIGS. 2 and 3, the second at least one optical element 114 includes a second reflective polarizer 131 , a second quarter wave plate 132 and a second lens 133 .

[0108] The second reflective polarizing plate 131 is a second film-like optical element. The second reflective polarizing plate 131 has a first main surface 131a and a second main surface 131b. The first main surface 131a and the second main surface 131b are on opposite sides to each other. The second main surface 131b becomes a sixth surface 1146 of the second at least one optical element 114.

[0109] As shown in FIG. 4, the second reflective polarizing plate 131 has a second transmission axis 131c and a second reflection axis 131d. The second transmission axis 131c and the second reflection axis 131d are perpendicular to each other. The first polarization direction D1 is parallel to the second reflection axis 131d. The second polarization direction D2 is parallel to the second transmission axis 131c. As a result, the second reflective polarizing plate 131 selectively reflects the linearly polarized light 185q having the first polarization direction D1 and emits the linearly polarized light 186q having the first polarization direction D1. In addition, the second reflective polarizing plate 131 selectively transmits the linearly polarized light 189p and 189q having the second polarization direction D2 and emits the linearly polarized light 190p and 190q having the second polarization direction D2.

[0110] A second transmission axis 131c of the second reflective polarizing plate 131 is perpendicular to the first transmission axis 121c of the first reflective polarizing plate 121. A second reflection axis 131d of the second reflective polarizing plate 131 is perpendicular to the first reflection axis 121d of the first reflective polarizing plate 121.

[0111] The second quarter-wave plate 132 is disposed between the half mirror 112 and the second reflective polarizing plate 131 .

[0112] The second quarter wave plate 132 has a first surface 132a and a second surface 132b. The first surface 132a and the second surface 132b are opposite each other. The first surface 132a becomes the fifth surface 1145 of the second at least one optical element 114.

[0113] As shown in FIG. 5, the second quarter-wave plate 132 has a second fast axis 132e and a second slow axis 132f. The second fast axis 132e and the second slow axis 132f are perpendicular to each other. The first polarization direction D1 forms an angle of 45° with the second fast axis 132e. The second polarization direction D2 forms an angle of 45° with the second fast axis 132e. The second fast axis 132e is perpendicular to the first fast axis 122e of the first quarter-wave plate 122. The second slow axis 132f is perpendicular to the first slow axis 122f of the first quarter-wave plate 122. As a result, the second quarter-wave plate 132 transmits the circularly polarized light 184q having the first rotation direction DR and emits the linearly polarized light 185q having the first polarization direction D1. The second quarter-wave plate 132 also transmits the linearly polarized light 186q having the first polarization direction D1 and emits the circularly polarized light 187q having the first rotation direction DR. The second quarter-wave plate 132 also transmits the circularly polarized light 188p and 188q having the second rotation direction DL and emits the linearly polarized light 189p and 189q having the second polarization direction D2.

[0114] As a result, when circularly polarized light 184q having the first rotation direction DR is incident on the fifth surface 1145, the second at least one optical element 114 reflects the incident circularly polarized light 184q and emits circularly polarized light 187q having the first rotation direction DR from the fifth surface 1145. Furthermore, when circularly polarized light 188p and 188q having the second rotation direction DL are incident on the fifth surface 1145, the second at least one optical element 114 transmits the incident circularly polarized light 188p and 188q and emits linearly polarized light 190p and 190q having the second polarization direction D2 from the sixth surface 1146.

[0115] The second lens 133 is a second plano-convex lens. Therefore, the second lens 133 has a positive power. The second lens 133 has a second convex lens surface 133a and a second planar lens surface 133b. The second convex lens surface 133a and the second planar lens surface 133b are on opposite sides to each other. The second convex lens surface 133a faces the second surface 112b of the half mirror 112. The second convex lens surface 133a may be any of a spherical surface, an aspherical surface, and a free-form surface.

[0116] The second reflective polarizing plate 131 and the second ¼ wavelength plate 132 are attached to the second flat lens surface 133b of the second lens 133, which is the second flat surface. As a result, the second reflective polarizing plate 131 and the second ¼ wavelength plate 132 have a flat shape.

[0117] By attaching the second reflective polarizing plate 131 to the second flat lens surface 133b of the second lens 133, a bonding device capable of bonding a film-like optical element to a convex lens surface is not required. This reduces the cost required for equipment to manufacture the optical system 102. In addition, by attaching the second reflective polarizing plate 131 to the second flat lens surface 133b, problems such as air bubbles being trapped between the second reflective polarizing plate 131 and the second lens 133, and wrinkles and sagging of the second reflective polarizing plate 131 are less likely to occur. This increases the yield of the optical system 102, and reduces the cost required to manufacture the optical system 102.

[0118] By attaching both the second reflective polarizing plate 131 and the second ¼ wavelength plate 132 to the second lens 133, the second reflective polarizing plate 131 and the second ¼ wavelength plate 132 can be attached to the second lens 133 simply by attaching a laminate of the second reflective polarizing plate 131 and the second ¼ wavelength plate 132 to the second lens 133. This laminate can be easily manufactured. This makes it possible to reduce the cost required for attaching the second reflective polarizing plate 131 and the second ¼ wavelength plate 132 to the second lens 133.

[0119] The second lens 133 is disposed at a position symmetrical to the position at which the first lens 123 is disposed with respect to the half mirror 112. The second lens 133 has a shape symmetrical to the shape of the first lens 123 with respect to the half mirror 112. This makes it possible to prevent the image formed by the optical system 102 from becoming a double image.

[0120] 3.6 Thinner optical system and smaller display and head-mounted devices In the display device 12, a part of the light emitted by the display 101 travels back and forth between the half mirror 112 and the first reflective polarizing plate 121. In addition, a part of the light emitted by the display 101 travels back and forth between the half mirror 112 and the second reflective polarizing plate 131. Therefore, the optical system 102 is a folded optical system. This allows the optical path of the light to be longer. This allows the optical system 102 to be a thin pancake lens. This allows the display device 12 and the head-mounted device 1 equipped with the optical system 102 to be miniaturized.

[0121] In recent years, a virtual space called the metaverse has been attracting attention. For this reason, it is expected that head-mounted devices that provide VR images will become widespread as a tool for accessing a world constructed in the virtual space. One of the reasons that prevents head-mounted devices that provide VR content from becoming widespread is that the housings of the head-mounted devices are large. For this reason, the head-mounted device 1, which can be made compact, can solve one of the reasons.

[0122] 3.7 Optical system power and FOV The first lens 123 and the second lens 133 are plano-convex lenses so that the first reflective polarizing plate 121 and the second reflective polarizing plate 131 can be attached to a flat surface.

[0123] When the first lens 123 and the second lens 133 are plano-convex lenses, the positive power of the first lens 123 and the second lens 133 is smaller than when the first lens 123 and the second lens 133 are biconvex lenses, and the positive power of the optical system 102 is smaller.

[0124] The convex lens 116 increases the positive power of the optical system 102. Therefore, the convex lens 116 compensates for the decrease in the positive power of the first lens 123 and the second lens 133. This makes it possible to increase the positive power of the optical system 102.

[0125] 3.8 Convex Lenses The convex lens 116 is a third plano-convex lens. Therefore, the convex lens 116 has a third plano lens surface 116a and a third convex lens surface 116b. The third plano lens surface 116a and the third convex lens surface 116b are on opposite sides to each other. The third plano lens surface 116a faces the second plano lens surface 133b of the second lens 133. The third convex lens surface 116b may be any of a spherical surface, an aspheric surface, and a free-form surface.

[0126] A second reflective polarizing plate 131 and a second quarter-wave plate 132 may be attached to the third flat lens surface 116a, which is the second flat surface.

[0127] By using the convex lens 116 as a plano-convex lens, the cost of a mold required to manufacture the convex lens 116 can be reduced, compared to when the convex lens 116 is a biconvex lens.

[0128] 4. Second embodiment The following describes the differences between the second embodiment and the first embodiment. For points that are not described, the second embodiment employs the same configuration as that employed in the first embodiment.

[0129] FIG. 6 is a cross-sectional view that illustrates a display device provided in the head-mounted device of the second embodiment.

[0130] 6, in the second embodiment, a first quarter-wave plate 122 is attached to one main surface 111a of a transparent plate 111. Also, a second quarter-wave plate 132 is attached to the other main surface 111b of the transparent plate 111.

[0131] By attaching the first ¼ wavelength plate 122 and the second ¼ wavelength plate 132 to a common element, the transparent plate 111, the accuracy of the polarization compensation performed by the first ¼ wavelength plate 122 and the second ¼ wavelength plate 132 can be improved.

[0132] 5. Third embodiment The following describes the differences between the third embodiment and the first embodiment. For points that are not described, the third embodiment employs the same configuration as that employed in the first embodiment.

[0133] FIG. 7 is a cross-sectional view that illustrates a display device provided in the head-mounted device of the third embodiment.

[0134] 7, the first at least one optical element 113 includes a first cholesteric liquid crystal film 124 instead of the combination of the first reflective polarizer 121 and the first quarter-wave plate 122. The second at least one optical element 114 includes a second cholesteric liquid crystal film 134 instead of the combination of the second reflective polarizer 131 and the second quarter-wave plate 132.

[0135] The combination of a reflective polarizer and a quarter-wave plate has the property of selectively reflecting circularly polarized light having a specific rotation direction and emitting circularly polarized light having the specific rotation direction. The cholesteric liquid crystal film also has the property of selectively reflecting circularly polarized light having a specific rotation direction and emitting circularly polarized light having the specific rotation direction. For this reason, the cholesteric liquid crystal film can be used as a substitute for the combination of a reflective polarizer and a quarter-wave plate.

[0136] The first cholesteric liquid crystal film 124 is a first film-like optical element that is attached to the first flat lens surface 123b of the first lens 123, which is a first plane. The first cholesteric liquid crystal film 124 has a first main surface 124a and a second main surface 124b. The first main surface 124a and the second main surface 124b are on opposite sides to each other. The first main surface 124a becomes the third surface 1133 of the first at least one optical element 113. The second main surface 124b becomes the fourth surface 1134 of the first at least one optical element 113.

[0137] The second cholesteric liquid crystal film 134 is a second film-like optical element that is attached to the third flat lens surface 133b of the second lens 133, which is the second flat surface. The second cholesteric liquid crystal film 134 has a first main surface 134a and a second main surface 134b. The first main surface 134a and the second main surface 134b are on opposite sides to each other. The first main surface 134a becomes the fifth surface 1145 of the second at least one optical element 114. The second main surface 134b becomes the sixth surface 1146 of the second at least one optical element 114.

[0138] Figure 8 is a diagram showing the relationship between the first rotation direction of a first cholesterol liquid crystal film provided in the head-mounted device of the third embodiment and the second rotation direction of a second cholesterol liquid crystal film provided in the head-mounted device.

[0139] 8, the first cholesteric liquid crystal film 124 has a first rotation direction 124h. The liquid crystal molecules contained in the first cholesteric liquid crystal film 124 have a structure in which they are spirally rotated in the first rotation direction 124h. The second rotation direction DL is the same direction as the first rotation direction 124h. Therefore, the first cholesteric liquid crystal film 124 selectively reflects circularly polarized light 184p having the second rotation direction DL.

[0140] The second cholesteric liquid crystal film 134 has a second rotation direction 134h opposite to the first rotation direction 124h. The liquid crystal molecules contained in the second cholesteric liquid crystal film 134 have a structure in which they are spirally rotated in the second rotation direction 134h. The first rotation direction DR is the same direction as the second rotation direction 134h. Therefore, the second cholesteric liquid crystal film 134 selectively reflects the circularly polarized light 184q having the first rotation direction DR.

[0141] 6 Fourth embodiment The following describes the differences between the fourth embodiment and the first embodiment. For points that are not described, the fourth embodiment employs the same configuration as that employed in the first embodiment.

[0142] FIG. 9 is a cross-sectional view that illustrates a display device provided in the head-mounted device of the fourth embodiment.

[0143] 9, the first at least one optical element 113 includes a first polarizing volume hologram (PVH) film 125 instead of the combination of the first reflective polarizer 121 and the first quarter-wave plate 122. The second at least one optical element 114 includes a second PVH film 135 instead of the combination of the second reflective polarizer 131 and the second quarter-wave plate 132.

[0144] The combination of a reflective polarizer and a quarter-wave plate has the property of selectively reflecting circularly polarized light having a specific rotation direction and emitting circularly polarized light having the specific rotation direction. The PVH film also has the property of selectively reflecting circularly polarized light having a specific rotation direction and emitting circularly polarized light having the specific rotation direction. For this reason, the PVH film can be used as a substitute for the combination of a reflective polarizer and a quarter-wave plate.

[0145] The PVH film comprises a large number of cholesteric liquid crystal molecules. The large number of cholesteric liquid crystal molecules are aligned in a direction tilted from the plane direction of the PVH film. Therefore, the PVH film can bend the optical path of circularly polarized light having a specific rotation direction, and can reflect or transmit the circularly polarized light off-axis, and can transmit circularly polarized light having a rotation direction opposite to the specific rotation direction. Reflecting light off-axis means that the reflected light travels in a direction different from the direction in which the reflected light travels when the light is specularly reflected.

[0146] The first PVH film 125 is a first film-like optical element that is attached to the first flat lens surface 123b of the first lens 123, which is a first plane. The first PVH film 125 has a first main surface 125a and a second main surface 125b. The first main surface 125a and the second main surface 125b are on opposite sides to each other. The first main surface 125a becomes the third surface 1133 of the first at least one optical element 113. The second main surface 125b becomes the fourth surface 1134 of the first at least one optical element 113.

[0147] The second PVH film 135 is a second film-like optical element that is attached to the third flat lens surface 133b of the second lens 133, which is the second flat surface. The second PVH film 135 has a first main surface 135a and a second main surface 135b. The first main surface 135a and the second main surface 135b are on opposite sides to each other. The first main surface 135a becomes the fifth surface 1145 of the second at least one optical element 114. The second main surface 135b becomes the sixth surface 1146 of the second at least one optical element 114.

[0148] FIG. 8 is also a diagram showing the relationship between a first pivoting direction of a first PVH film provided in the head-mounted device of the fourth embodiment and a second pivoting direction of a second PVH film provided in the head-mounted device.

[0149] The first PVH film 125 has a first rotation direction 125h. The liquid crystal molecules contained in the first PVH film 125 have a structure in which they are spirally rotated in the first rotation direction 125h. The second rotation direction DL is the same direction as the first rotation direction 125h. Therefore, the first PVH film 125 selectively reflects circularly polarized light 184p having the second rotation direction DL.

[0150] The second PVH film 135 has a second rotation direction 135h opposite to the first rotation direction 125h. The liquid crystal molecules contained in the second PVH film 135 have a structure in which they are spirally rotated in the second rotation direction 135h. The first rotation direction DR is the same direction as the second rotation direction 135h. Therefore, the second PVH film 135 selectively reflects circularly polarized light 184q having the first rotation direction DR.

[0151] Desirably, the orientation of the cholesteric liquid crystal molecules in each of the first PVH film 125 and the second PVH film 135 is changed within the plane of each PVH film so that each PVH film has a positive power similar to a concave mirror. This allows positive power to be imparted to each PVH film having a flat shape. This allows the positive power of the optical system 102 to be increased, allowing the optical system 102 to be made thinner.

[0152] 7 Fifth embodiment The following describes the differences between the fifth embodiment and the first embodiment. For points that are not described, the fifth embodiment employs the same configuration as that employed in the first embodiment.

[0153] FIG. 10 is a cross-sectional view that illustrates a display device provided in the head-mounted device of the fifth embodiment.

[0154] In the fifth embodiment, as shown in FIG.

[0155] The transparent plate 117 has a main surface 117a.

[0156] The transparent plate 117 is a glass plate or the like.

[0157] A first flat lens surface 123b of the first lens 123 faces a first surface 112a of the half mirror 112. The first lens 123 is disposed between the transparent plate 117 and the half mirror 112.

[0158] The second flat lens surface 133 b of the second lens 133 faces the second surface 112 b of the half mirror 112 .

[0159] The half mirror 112 is sandwiched between the first flat lens surface 123b of the first lens 123 and the second flat lens surface 133b of the second lens 133. The half mirror 112 is produced, for example, by depositing metal on one of the flat lens surfaces of the first lens 123 and the second lens 133 to produce a complex of the first lens 123 and one of the second lenses 133 and the half mirror 112, and bonding the produced complex to the other of the first lens 123 and the second lens 133. The bonding between the complex and the other of the first lens 123 and the second lens 133 is performed so that the first lens 123 and the second lens 133 are symmetrical with respect to the half mirror 112. The adhesive or the like is selected so that the symmetry is not substantially lost even if the distance from the half mirror 112 to the second lens 133 becomes different from the distance from the half mirror 112 to the first lens 123 due to the adhesive or the like. The fifth embodiment is employed in the case where the complex body, which is a rigid body, and the other of the first lens 123 and the second lens 133, which are rigid bodies, can be bonded to each other with an adhesive or the like.

[0160] The first reflective polarizing plate 121 and the first quarter-wave plate 122 are attached to the main surface 117a of the transparent plate 117, which is the first flat surface.

[0161] Second reflective polarizing plate 131 and second quarter-wave plate 132 are attached to third flat lens surface 116a of convex lens 116, which is the second flat surface.

[0162] 8 Sixth embodiment The following describes the differences between the sixth embodiment and the fifth embodiment. For points that are not described, the sixth embodiment employs the same configuration as that employed in the fifth embodiment.

[0163] FIG. 11 is a cross-sectional view that illustrates a display device provided in a head-mounted device of the sixth embodiment.

[0164] In the sixth embodiment, as shown in FIG. 11, the optical system 102 includes a transparent plate 111.

[0165] For this reason, the optical system 102 includes a first transparent plate 117 and a second transparent plate 111. The transparent plate 117 has a main surface 117a which is a first main surface, and the transparent plate 111 has the other main surface 111b which is a second main surface.

[0166] Transparent plate 111 is disposed between first planar lens surface 123 b of first lens 123 and second planar lens surface 133 b of second lens 133 .

[0167] The half mirror 112 is disposed on the other main surface 111 b of the transparent plate 111 .

[0168] By attaching the half mirror 112 onto the other main surface 111b of the transparent plate 111, it is possible to improve the flatness of the half mirror 112, which is important in the display device 12 that employs the double-pass system.

[0169] 9 Seventh embodiment The following describes the differences between the seventh embodiment and the fifth embodiment. For points that are not described, the seventh embodiment also employs the same configuration as that employed in the fifth embodiment.

[0170] FIG. 12 is a cross-sectional view that illustrates a display device provided in the head-mounted device of the seventh embodiment.

[0171] 12, in the seventh embodiment, a first ¼ wavelength plate 122 is attached to a first flat lens surface 123b of a first lens 123. A second ¼ wavelength plate 132 is attached to a second flat lens surface 133b of a second lens 133. A half mirror 112 is sandwiched between the first ¼ wavelength plate 122 and the second ¼ wavelength plate 132.

[0172] By attaching the first ¼ wavelength plate 122 and the second ¼ wavelength plate 132 to a common element, the half mirror 112, the accuracy of the polarization compensation performed by the first ¼ wavelength plate 122 and the second ¼ wavelength plate 132 can be improved.

[0173] The seventh embodiment is employed in the case where the half mirror 112 can be disposed on the first ¼ wavelength plate 122 or the second ¼ wavelength plate 132 .

[0174] 10 Eighth embodiment The following describes the differences between the eighth embodiment and the fifth embodiment. For points that are not described, the eighth embodiment also employs the same configuration as that employed in the fifth embodiment.

[0175] FIG. 13 is a cross-sectional view that diagrammatically illustrates a display device provided in a head-mounted device of the eighth embodiment.

[0176] 13, in the eighth embodiment, the first at least one optical element 113 includes a first cholesteric liquid crystal film 124 instead of the combination of the first reflective polarizer 121 and the first quarter-wave plate 122. Also, the second at least one optical element 114 includes a second cholesteric liquid crystal film 134 instead of the combination of the second reflective polarizer 131 and the second quarter-wave plate 132. The first cholesteric liquid crystal film 124 and the second cholesteric liquid crystal film 134 in the eighth embodiment are cholesteric liquid crystal films similar to the first cholesteric liquid crystal film 124 and the second cholesteric liquid crystal film 134 in the third embodiment, respectively.

[0177] 11 Ninth embodiment The following describes the differences between the ninth embodiment and the first embodiment. For points that are not described, the ninth embodiment also employs the same configuration as that employed in the fifth embodiment.

[0178] FIG. 14 is also a cross-sectional view that diagrammatically illustrates a display device provided in the head-mounted device of the ninth embodiment.

[0179] 14, the first at least one optical element 113 includes a first PVH film 125 instead of the combination of the first reflective polarizer 121 and the first quarter-wave plate 122. The second at least one optical element 114 includes a first PVH film 125 instead of the combination of the second reflective polarizer 131 and the second quarter-wave plate 132. The first PVH film 125 and the second PVH film 135 in the ninth embodiment are PVH films similar to the first PVH film 125 and the second PVH film 135 in the fourth embodiment, respectively.

[0180] The present disclosure is not limited to the above-described embodiments, and may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments, a configuration that has the same action and effect, or a configuration that can achieve the same purpose. [Explanation of symbols]

[0181] 1 Head-mounted device, 11 Housing, 12 Display device, 101 Display, 101a Display surface, 102 Optical system, 111 Transparent plate, 111a One main surface, 111b Other main surface, 112 Half mirror, 112a First surface, 112b Second surface, 113 First at least one optical element, 1133 Third surface, 1134 Fourth surface, 114 Second at least one optical element, 1145 Fifth surface, 1146 Sixth surface, 115 Polarizing plate, 116 Convex lens, 116a Flat lens surface, 116b Convex lens surface, 117 Transparent plate, 117a Main surface, 121 First reflective polarizing plate, 121a First main surface, 121b Second main surface, 121c First transmission axis, 121d first reflection axis, 122 first quarter-wave plate, 122a first surface, 122b second surface, 122e first fast axis, 122f first slow axis, 123 first lens, 123a first convex lens surface, 123b first planar lens surface, 124 first cholesteric liquid crystal film, 124a first main surface, 124b second main surface, 124h first rotation direction, 125 first polarizing volume hologram (PVH) film, 125a first main surface, 125b second main surface, 125h first rotation direction, 131 second reflective polarizer, 131a first main surface, 131b second main surface, 131c second transmission axis, 131d second reflection axis, 132 second quarter-wave plate, 132a first surface, 132b second surface, 132e second fast axis, 132f second slow axis, 133 second lens, 133a second convex lens surface, 133b second planar lens surface, 134 second cholesteric liquid crystal film, 134a first main surface, 134b second main surface, 134h second rotation direction, 135 second PVH film, 135a first main surface, 135b second main surface, 135h second rotation direction, 181 linearly polarized light, 182 linearly polarized light, 183 circularly polarized light, 184p circularly polarized light, 185p linearly polarized light, 186p linearly polarized light, 187p circularly polarized light, 188p circularly polarized light, 189p linearly polarized light, 190p linearly polarized light, 184q circularly polarized light, 185q linearly polarized light, 186q Linear polarization, 187q Circular polarization, 188q Circular polarization, 189q Linear polarization, 190p Linear polarization, 82 Display device, 801 Display, 802 1 / 4 wave plate, 803 Half mirror, 8041 / 4 wave plate, 805 Reflective polarizer, 811 Lens, 812 Lens, 881 Linear polarizer, 882 Circular polarizer, 883 Circular polarizer, 884 Linear polarizer, 885 Linear polarizer, 886 Circular polarizer, 887 Circular polarizer, 888 Linear polarizer, 889 Linear polarizer, 92 Display device, 901 Display, 902 Reflective polarizer, 903 1 / 4 wave plate, 904 Half mirror, 905 1 / 4 wave plate, 906 Reflective polarizer, 911 Lens, 912 Lens, 913 Glass plate, 981 Linear polarizer, 982 Linear polarizer, 983 Circular polarizer, 984p Circular polarizer, 985p Linear polarizer, 986p Linear polarizer, 987p Circular polarizer, 988p Circular polarizer, 989p Linear polarizer, 990p Linear polarization, 989q circular polarization, 985q linear polarization, 986q linear polarization, 987p circular polarization, 988p circular polarization, 989p linear polarization, 990p linear polarization, H head, E eye, D1 first polarization direction, D2 second polarization direction, DR first rotation direction, DL second rotation direction.

Claims

1. a half mirror having a first surface and a second surface on opposite sides; at least one first optical element including a first film-like optical element attached to a first plane, having a third surface and a fourth surface on opposite sides, the third surface facing the first surface, outputting a first circularly polarized light having a first rotation direction from the third surface when a first linearly polarized light having a first polarization direction is incident on the fourth surface, and outputting a third circularly polarized light having the second rotation direction from the third surface when a second circularly polarized light having a second rotation direction different from the first rotation direction is incident on the third surface; a second film-like optical element attached to the second plane, having a fifth surface and a sixth surface on opposite sides, the fifth surface facing the second surface, a fifth circularly polarized light having the first polarization direction being emitted from the fifth surface when a fourth circularly polarized light having the first rotation direction is incident on the fifth surface, and a second linearly polarized light having a second polarization direction perpendicular to the first polarization direction being emitted from the sixth surface when a sixth circularly polarized light having the second rotation direction is incident on the fifth surface, the second at least one optical element being disposed at a position symmetrical to the position at which the first at least one optical element is disposed with respect to the half mirror, and having a shape symmetrical to the shape of the first at least one optical element with respect to the half mirror; a convex lens that transmits the second linearly polarized light; An optical system comprising:

2. the first at least one optical element includes a first lens; The at least one second optical element includes a second lens that is disposed at a position symmetrical to a position at which the first lens is disposed with respect to the half mirror and has a shape symmetrical to a shape of the first lens with respect to the half mirror. The optical system of claim 1 .

3. the first lens is a first plano-convex lens having opposed first plano and first convex lens surfaces; The second lens is a second plano-convex lens having opposed second plano and second convex lens surfaces. The optical system according to claim 2 .

4. the first convex lens surface faces the first surface, the second convex lens surface faces the second surface, the first plane is the first flat lens surface; The second plane is the second flat lens surface. The optical system according to claim 3 .

5. a transparent plate having a main surface and disposed between the first convex lens surface and the second convex lens surface; The half mirror is disposed on the main surface.

5. The optical system according to claim 4.

6. the first convex lens surface faces the first surface, the second convex lens surface faces the second surface, the convex lens is a third plano-convex lens having opposed third planar lens surface and third convex lens surface, the third planar lens surface facing the second planar lens surface; the first plane is the first flat lens surface; The second plane is the third flat lens surface. The optical system according to claim 3 .

7. a transparent plate having a main surface and disposed between the first convex lens surface and the second convex lens surface; The half mirror is disposed on the main surface. The optical system according to claim 6.

8. A transparent plate having a main surface, the first plano-convex lens is disposed between the transparent plate and the half mirror, the first flat lens surface faces the first surface; the second planar lens surface faces the second surface; the convex lens is a third plano-convex lens having a third planar lens surface and a third convex lens surface on opposite sides, the third planar lens surface facing the second convex lens surface; the first plane is the main surface, The second plane is the third flat lens surface. The optical system according to claim 3 .

9. The half mirror is sandwiched between the first flat lens surface and the second flat lens surface. The optical system according to claim 8.

10. the transparent plate is a first transparent plate, the main surface is a first main surface, a second transparent plate having a second principal surface and disposed between the first planar lens surface and the second planar lens surface; The half mirror is disposed on the second main surface. The optical system according to claim 8.

11. the first film-like optical element is a first reflective polarizing plate having the fourth surface and having a first transmission axis and a first reflection axis; the first at least one optical element includes a first quarter-wave plate having the third surface and a first fast axis and a first slow axis, the first quarter-wave plate being disposed between the half mirror and the first reflective polarizing plate, the second film-like optical element is a second reflective polarizing plate having the sixth surface, a second transmission axis and a second reflection axis, the second transmission axis being perpendicular to the first transmission axis, and the second reflection axis being perpendicular to the first reflection axis; The second at least one optical element includes a second quarter-wave plate that is disposed between the half mirror and the second reflective polarizing plate, has the fifth surface, has a second fast axis and a second slow axis, and the second fast axis is perpendicular to the first fast axis and the second slow axis is perpendicular to the first slow axis.

11. The optical system according to claim 1 .

12. the first at least one optical element includes a first plano-convex lens having opposed first plano and first convex lens surfaces, the first convex lens surface facing the first surface; the second at least one optical element includes a second plano-convex lens having opposed second plano and second convex lens surfaces, the second convex lens surface facing the second surface; the first plane is the first flat lens surface; the second plane is the second planar lens surface; the first quarter-wave plate is attached to the first flat lens surface; The second quarter-wave plate is attached to the second flat lens surface. The optical system according to claim 11.

13. the first at least one optical element includes a first plano-convex lens having opposed first plano and first convex lens surfaces, the first convex lens surface facing the first surface; the second at least one optical element includes a second plano-convex lens having opposed second plano and second convex lens surfaces, the second convex lens surface facing the second surface; the convex lens is a third plano-convex lens having opposed third planar lens surface and third convex lens surface, the third planar lens surface facing the second planar lens surface; the first plane is the first flat lens surface; the second plane is the third flat lens surface; the first quarter-wave plate is attached to the first flat lens surface; The second quarter-wave plate is attached to the third flat lens surface. The optical system according to claim 11.

14. the first at least one optical element includes a first plano-convex lens having opposed first plano and first convex lens surfaces, the first convex lens surface facing the first surface; the second at least one optical element includes a second plano-convex lens having opposed second plano and second convex lens surfaces, the second convex lens surface facing the second surface; a transparent plate having one principal surface and another principal surface on opposite sides and disposed between the first convex lens surface and the second convex lens surface; the first plane is the first flat lens surface; the second plane is the second planar lens surface; The first quarter-wave plate is attached to the one of the principal surfaces, The second quarter-wave plate is attached to the other main surface, The half mirror is disposed on one of the principal surfaces or the other principal surface. The optical system according to claim 11.

15. the first at least one optical element includes a first plano-convex lens having opposed first plano and first convex lens surfaces, the first convex lens surface facing the first surface; the second at least one optical element includes a second plano-convex lens having opposed second plano and second convex lens surfaces, the second convex lens surface facing the second surface; the convex lens is a third plano-convex lens having opposed third planar lens surface and third convex lens surface, the third planar lens surface facing the second planar lens surface; a transparent plate having one principal surface and another principal surface on opposite sides and disposed between the first convex lens surface and the second convex lens surface; the first plane is the first flat lens surface; the second plane is the third flat lens surface; The first quarter-wave plate is attached to the one of the principal surfaces, The second quarter-wave plate is attached to the other main surface, The half mirror is disposed on one of the principal surfaces or the other principal surface. The optical system according to claim 11.

16. A transparent plate having a main surface, the first at least one optical element includes a first plano-convex lens having a first planar lens surface and a first convex lens surface on opposite sides, the first planar lens surface facing the first surface, and being disposed between the transparent plate and the half mirror; the second at least one optical element includes a second plano-convex lens having opposed second plano and second convex lens surfaces, the second plano lens surface facing the second surface; the convex lens is a third plano-convex lens having a third planar lens surface and a third convex lens surface on opposite sides, the third planar lens surface facing the second convex lens surface; the first plane is the main surface, the second plane is the third flat lens surface; The first quarter-wave plate is attached to the main surface, the second quarter-wave plate is attached to the third flat lens surface; The half mirror is sandwiched between the first flat lens surface and the second flat lens surface. The optical system according to claim 11.

17. A first transparent plate having a first main surface and a second transparent plate having a second main surface, the first at least one optical element includes a first plano-convex lens having a first planar lens surface and a first convex lens surface on opposite sides, the first planar lens surface facing the first surface, and being disposed between the first transparent plate and the half mirror; the second at least one optical element includes a second plano-convex lens having opposed second plano and second convex lens surfaces, the second plano lens surface facing the second surface; the convex lens is a third plano-convex lens having a third planar lens surface and a third convex lens surface on opposite sides, the third planar lens surface facing the second convex lens surface; the second transparent plate is disposed between the first planar lens surface and the second planar lens surface; the first plane is the first main surface, the second plane is the third flat lens surface; The first quarter-wave plate is attached to the first main surface, the second quarter-wave plate is attached to the third flat lens surface; The half mirror is disposed on the second main surface. The optical system according to claim 11.

18. A transparent plate having a main surface, the first at least one optical element includes a first plano-convex lens having a first planar lens surface and a first convex lens surface on opposite sides, the first planar lens surface facing the first surface, and being disposed between the transparent plate and the half mirror; the second at least one optical element includes a second plano-convex lens having opposed second plano and second convex lens surfaces, the second plano lens surface facing the second surface; the convex lens is a third plano-convex lens having a third planar lens surface and a third convex lens surface on opposite sides, the third planar lens surface facing the second convex lens surface; the first plane is the main surface, the second plane is the third flat lens surface; the first quarter-wave plate is attached to the first flat lens surface; the second quarter-wave plate is attached to the second flat lens surface; The half mirror is sandwiched between the first quarter-wave plate and the second quarter-wave plate. The optical system according to claim 11.

19. the first film-like optical element is a first cholesteric liquid crystal film having the third surface and the fourth surface and having a first twist direction; The second film-like optical element has the fifth surface and the sixth surface, and is a second cholesteric liquid crystal film having a second twist direction different from the first twist direction.

11. The optical system according to claim 1 .

20. the first film-like optical element is a first polarizing volume hologram film having the third surface and the fourth surface and having a first rotation direction; The second film-like optical element is a second polarizing volume hologram film having the fifth surface and the sixth surface and having a second rotation direction different from the first rotation direction.

11. The optical system according to claim 1 .

21. An optical system according to any one of claims 1 to 10; a display that outputs the first linearly polarized light; A display device comprising:

22. A head-mounted device comprising the display device of claim 21.

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