Optical element, virtual image display device and manufacturing method of optical element

Abstract

To control the thickness of a film formed on each reflection surface.SOLUTION: A light guide member 1 comprises: a first surface 52; a second surface 62 facing the first surface; and a plurality of reflectors formed on a region between the first surface 52 and the second surface 62 and each including reflection surfaces (3a, 3b) non-parallel to the first surface 52 and the second surface 62. The light guide member 1 includes a first structure 51 and a second structure 61. The first structure 51 includes a first surface 52, a first intermediate surface 55 positioned between the first surface 52 and the second surface 62 and non-vertical to the first surface 52, and a plurality of first protrusions (53a, 53b) respectively protruding from the first surface 52 side to the second surface 62 side. The plurality of first protrusions (53a, 53b) include first inclined surfaces (54a, 54b) inclined with respect to the first surface 52. The second structure 61 includes second inclined surfaces (64a, 64b) facing the first inclined surfaces (54a, 54b) of the first structure 51.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an optical element, a virtual image display device, and a method for manufacturing the optical element. [Background technology]

[0002] Patent Document 1 discloses an optical element in which a unit optical shape portion is formed in a first optical shape layer, a reflective layer is formed on a first inclined surface of the unit optical shape portion of the first optical shape layer, and then an uncured ultraviolet curing resin is applied to the surface of the first optical shape layer on which the unit optical shape portion is provided, and ultraviolet light is irradiated to form a second optical shape layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2017-111321 Summary of the Invention [Problem to be solved by the invention]

[0004] It is difficult to control the thickness of the film formed on each reflecting surface. [Means for solving the problem]

[0005] The optical element of the present invention has a first surface, a second surface opposite to the first surface, and a plurality of reflecting mirrors formed in an area between the first surface and the second surface, each having a reflecting surface non-parallel to the first surface and the second surface, wherein the optical element is characterized in that the optical element is composed of at least a first structure and a second structure, the first structure includes the first surface, a first intermediate surface located between the first surface and the second surface and non-perpendicular to the first surface, and a plurality of first convex portions each protruding from the first surface side to the second surface side, the plurality of first convex portions each having a first inclined surface inclined with respect to the first surface, the second structure includes a second inclined surface opposite to the first inclined surface of the first structure, an optically functional film is provided between the first inclined surface and the second inclined surface, the first intermediate surface is provided between the plurality of first inclined surfaces, and the first intermediate surface and the second structure face each other. Effect of the Invention

[0006] The thickness of the film formed on each reflecting surface can be controlled. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a virtual image display device to which a first embodiment is applied. [Diagram 2] FIG. 2 is a diagram illustrating light propagation in the first embodiment. [Diagram 3] FIG. 1 is a conceptual diagram of a first embodiment. [Figure 4] FIG. 1 is a configuration diagram of a first embodiment. [Diagram 5] 1 is a flowchart of a manufacturing method. [Figure 6A] FIG. 1 is a diagram (first half) explaining a manufacturing method. [Figure 6B] 13 is a diagram (second half) explaining the manufacturing method. [Figure 7] FIG. 2 is a diagram for explaining the shape of the first embodiment. [Figure 8] 1A to 1C are diagrams illustrating an example of an oblique film formation method. [Figure 9] FIG. 13 is a diagram illustrating a comparative example. [Figure 10] 13 is a photograph of a comparative example. [Figure 11] FIG. 13 is a diagram for explaining measurement positions in a comparative example. [Figure 12] 13 shows the measurement results of a comparative example. [Figure 13] FIG. 11 is a diagram illustrating a first modified example. [Figure 14] FIG. 11 is a diagram illustrating a second modified example. [Figure 15] FIG. 11 is a diagram illustrating a second modified example. [Figure 16] FIG. 13 is a diagram illustrating a third modified example. [Figure 17] FIG. 13 is a diagram illustrating the configuration of a third modified example. [Figure 18] FIG. 13 is a diagram for explaining an overview of a second embodiment. [Figure 19] FIG. 11 is a diagram illustrating a configuration of a second embodiment. [Figure 20] 5 is a flowchart of a manufacturing method according to a second embodiment. [Figure 21] 6A to 6C are diagrams illustrating a manufacturing method according to the second embodiment. [Figure 22] FIG. 4 is a diagram illustrating a shape of a second embodiment. [Figure 23] FIG. 13 is a conceptual diagram illustrating a modified example of the manufacturing method. [Figure 24] 13A to 13C are detailed views illustrating a modified example of the manufacturing method. [Diagram 25] 13 is a flowchart illustrating a modified example of the manufacturing method. [Figure 26] FIG. 13 is a conceptual diagram illustrating a modified example (thermal curing) of the manufacturing method. [Figure 27] 13 is a flowchart illustrating a modified example (thermal curing) of the manufacturing method. [Figure 28] FIG. 13 is a diagram illustrating a fourth modified example. [Figure 29] FIG. 13 is a diagram illustrating a fifth modified example. [Diagram 30] FIG. 13 is a diagram illustrating a sixth modified example. [Diagram 31] FIG. 13 is a diagram illustrating a seventh modified example. [Diagram 32]FIG. 13 is a diagram illustrating an eighth modified example. [Diagram 33] FIG. 13 is a diagram illustrating a ninth modified example. [Diagram 34] FIG. 17 is a diagram illustrating a tenth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated description will be omitted.

[0009] <First embodiment> 1 is a schematic diagram of a virtual image display device 6 including a light guiding member 1 according to a first embodiment. The virtual image display device 6 in this embodiment is a smart glass that is a glasses-type wearable terminal, and includes a frame unit and a lens unit 8. The lens unit 8 is transparent and can project light passing through it onto the user's eyeball, allowing the user to see the outside scenery.

[0010] The lens unit 8 has a plurality of reflecting surfaces 3 arranged therein, which correspond to the light guide member 1 in this embodiment. The image light formed by the image display element 7 is emitted in the -Y direction, propagates inside the lens 8, and is converted in direction by the reflecting surface 3 before propagating toward the eyeball in the Z direction. FIG. 2 shows a schematic diagram of light propagation. The image display element 7 is a transmissive liquid crystal element, and has a light source of RGB (red, blue, green) at the rear of the image display element 7. The light source is a light source in which small light emitting points of an LED (Light Emitting Diode) are uniformly distributed and scattered by a scatterer, and can form uniform RGB light. The light emitted from this light source is formed into image light by the image display element 7, and propagates in the -Y direction through the lens unit 8 by the mirror 71. The image light propagating through the light guide member 1, which is a part of the lens unit 8, is converted in direction to the Z direction by the reflecting surface 3 before propagating toward the user's eyeball. The user can recognize the image formed by this image light. The light guiding member 1 of the present invention is not limited to smart glasses, and can also be mounted on other types of virtual image display devices such as a transmissive head mounted display. The light guiding member 1 of the present invention is not limited to use in virtual image display devices, and can also be used in a light source module combined with a light source, a light receiving module combined with a light receiving element, and the like.

[0011] Fig. 3 is an enlarged view of a part of the lens unit 8 of the virtual image display device 6 shown in Fig. 1, which is an example in which the light guide member 1 is used in the virtual image display device 6 according to the first embodiment. Fig. 3 shows a cross section of the YZ plane of the straight line AA' shown in Fig. 1. The light guide member 1, which is a part of the lens unit 8, guides image light 9 from the image display element 7, and has a plurality of reflective surfaces 3 arranged thereon that split the image light 9 into reflected light 10 and transmitted light 11. An optically functional film 2 is formed on the reflective surface 3, and the reflected light 10 reflected by the optically functional film 2 is emitted from the light guide member 1 to the outside.

[0012] Here, the optical function film 2 is a partially reflective film made of a dielectric multilayer film, and can separate the image light 9 into reflected light 10 and transmitted light 11 at a predetermined ratio. The reflective surfaces 3 are inclined with respect to the direction in which the image light 9 is guided, and a plurality of them are arranged at an arbitrary interval D. By arranging a plurality of reflective surfaces 3, the image light 9 is split into a plurality of light beams, and the eye box is expanded. This makes it easier for the wearer, who is the user, to view the virtual image even when he or she moves his or her eyes relative to the virtual image display device 6, and allows the wearer to view a virtual image with a wide angle of view.

[0013] Next, a description will be given of the structure of the light guide member 1. The light guide member 1 is shown in Fig. 4. The light guide member 1 is an example of an optical element.

[0014] The light-guiding member 1 in this embodiment has a first surface 52, a second surface 62 facing the first surface, and a plurality of reflectors formed in an area between the first surface 52 and the second surface 62, each of which has a reflecting surface (3 a, 3 b) non-parallel to the first surface 52 and the second surface 62. The light-guiding member 1 includes at least a first structure 51 and a second structure 61. The first structure 51 includes the first surface 52, a first intermediate surface 55 located between the first surface 52 and the second surface 62 and non-perpendicular to the first surface 52, and a plurality of first protrusions each protruding from the first surface side 52 to the second surface 62 side. (53a, 53b), the plurality of first protrusions (53a, 53b) each have a first inclined surface (54a, 54b) inclined with respect to the first surface 52, the second structure 61 includes a second inclined surface (64a, 64b) facing the first inclined surface (54a, 54b) of the first structure 51, an optical function film (2a, 2b) is provided between the first inclined surface (54a, 54b) and the second inclined surface (64a, 64b), the first intermediate surface 55 is provided between the plurality of first inclined surfaces (54a, 54b), and the first intermediate surface 55 and the second structure 61 face each other. In FIG. 4, the first intermediate surface 55 is formed so as to be parallel to the first surface 52 and the second surface 62, but is not limited thereto, and the first intermediate surface 55 may be inclined with respect to the first surface 52 and the second surface 62. For example, the intermediate surface 55 may be an inclined surface that is an extension of the first inclined surface 54b.

[0015] This makes it possible to control the thickness of the optical function film 2 formed on each reflecting surface 3, and to form the film uniformly.

[0016] <Manufacturing method> Next, a method for manufacturing the light guiding member 1 will be described. Fig. 5 is a flow chart of the method for manufacturing the light guiding member 1 in the first embodiment. Fig. 6A and Fig. 6B are diagrams for explaining this manufacturing method.

[0017] First, a mold 14 is prepared having a transfer surface 13 on which a plurality of inverted shapes 12 of the reflecting surface 3 of the light-guiding member 1 are formed (FIG. 5 (Step S1), FIG. 6A(a)). Here, a plurality of inverted shapes 12 are arranged at intervals of 2 mm, and have a sawtooth wave shape with a width of 1.8 mm and a height of 1.8 mm.

[0018] Here, the interval between the reflecting surfaces 3 is not limited to 2 mm, and does not necessarily have to be the same interval. However, if the interval D between the reflecting surfaces 3 is too small, a large proportion of the obliquely incident film-forming material is blocked in the film-forming process described later, making it impossible to obtain a sufficiently uniform film thickness. Considering the incident direction of the film-forming material, it is desirable to allow the film-forming material to be incident on the reflecting surface 3 at an angle of 20 degrees or more with respect to the vertical direction, as shown in Figure 7. Specifically, it is desirable to satisfy the following formula:

[0019] D≧LTan(20deg) Here, D is the distance between the reflecting surfaces 3, and L is the length of the vertical surface 5 adjacent to the reflecting surface 3. This allows the thickness of the optical function film 2 formed on each reflecting surface 3 to be uniform in the film formation process.

[0020] Next, epoxy-based thermosetting resin 15 is applied onto the transfer surface 13 of the mold 14 (step S2 in FIG. 5, FIG. 6A(b)). The thermosetting resin 15 is in a liquid state before hardening, and is completely filled up to the bottom apex of the sawtooth wave shaped portion of the inverted shape 12.

[0021] Thereafter, the flat mold 16 is brought into complete contact with the upper surface of the thermosetting resin 12. While in contact with the upper surface of the thermosetting resin 12, the thermosetting resin 12 is heated to a gelling temperature or higher by a heating means (not shown) to be solidified (step S3 in FIG. 5, FIG. 6A(c)).

[0022] By releasing the upper and lower molds (14, 16) described above from the thermosetting resin 15, a structure 17 is formed having multiple sawtooth-wave shaped reflective surfaces 3 arranged at intervals of 2 mm (Figure 6A (d)).

[0023] Next, the optical function film 2 is formed on the reflecting surface 3 of the structure 17 by a deposition method (Step S4 in FIG. 5, FIG. 6B(e)).

[0024] FIG. 8 is a diagram showing the arrangement of structures 17 during deposition. When an optically functional film 2 is deposited on an inclined reflecting surface 3, the deposition distance varies depending on the position. This results in a film thickness distribution within the surface (FIG. 8(a)). By arranging structures 17 at an angle during deposition, the inclined reflecting surface 3 can be made perpendicular to the deposition direction A. In this way, the deposition distance becomes equal within the surface, enabling uniform deposition (FIG. 8(b)).

[0025] The optical function film 2 in this embodiment is a partially reflective film made of a dielectric multilayer film, and is configured to separate the image light 9 into reflected light 10 and transmitted light 11. The method for forming the optical function film 2 is not limited to vapor deposition, and other methods such as sputtering may be used. The optical function film 2 is not limited to a partially reflective film, and may be appropriately selected based on design requirements.

[0026] Next, the same epoxy-based thermosetting resin 15' as the resin constituting the structure 17 is applied and laminated on the structure 17 including the optical function film 2 (FIG. 4 (Step S5), FIG. 5B(f)).

[0027] The flat mold 18 is brought into complete contact with the upper surface of the thermosetting resin 15'. The thermosetting resin 15' is heated to a gelling temperature or higher by a heating means (not shown) to solidify and mold (FIG. 4 (step S6), FIG. 5B(g)).

[0028] Finally, the flat mold 18 is released from the thermosetting resin 15′ (FIG. 5B(h)). In this manner, the resin light-guiding member 1 is produced, which is composed of the structures 17 and 19, each having a sawtooth-wave shaped reflective surface 3 arranged at intervals of 2 mm.

[0029] In this embodiment, the structures 17 and 19 are made of a thermosetting resin 15, but the present invention is not limited to this, and other energy curable resins such as ultraviolet curable resins and electron beam curable resins, thermoplastic resins, etc. can also be used. However, it is preferable that the resin constituting the structures 19 is a material that can be cured and molded at a temperature of at least 130 degrees or less. If the resin is molded at a high temperature of 130 degrees or more, problems such as cracks or fissures will occur in the optical function film 2. Thermoplastic resins often require heating to 130 degrees or more for transfer, and therefore, at least as the material constituting the structures 19, it is preferable to use the thermosetting resin used in this embodiment or an energy curable resin such as an ultraviolet curable resin or an electron beam curable resin.

[0030] The constituent materials of the structures 17 and 19 constituting the light guide member 1 are not limited. However, if the difference in refractive index between the two is large, the boundary between the structures 17 and 19 becomes clearly visible, which interferes with the wearer's field of vision. Therefore, it is desirable to make the refractive indexes of the materials constituting the structures 17 and 19 the same or equal, which can improve the above problem.

[0031] The interface between the structure 17 and the structure 19 has a characteristic interface that is generated during the process of thermally curing the structure 19, which is subsequently thermally cured. For this reason, the interface can be confirmed by a transmission electron microscope (TEM) or the like. Another observation method is to observe the distribution of refractive index and birefringence. The resin structure is not completely uniform, and there is a density distribution and a stress distribution inside to some extent. If it is transparent, they can be observed by the distribution of refractive index and birefringence. Usually, the distribution of refractive index and birefringence changes gradually from the center to the outside. In contrast, at the interface formed by bonding, the change in the refractive index and birefringence appears as an inflection point.

[0032] The manufacturing method of this embodiment is a manufacturing method for a light-guiding member having a first surface, a second surface opposite to the first surface, and a plurality of reflectors formed in a region between the first surface and the second surface, each having a reflecting surface non-parallel to the first surface and the second surface, and includes a first step (step S3) of forming a first structure including the first surface, a plurality of first convex portions located between the first surface and the second surface, protruding from the first surface side to the second surface side, and having a first reflecting surface, and a first intermediate surface provided between the plurality of first convex portions, a second step (step S4) of forming an optical function film on the first inclined surface, and a third step (step S6) of forming a second structure including a second inclined surface opposite to the first inclined surface of the first structure, and a surface in contact with the first intermediate surface.

[0033] This makes it possible to control the thickness of the optical function film 2 formed on each reflecting surface 3.

[0034] Next, the results of measuring a comparative example are shown. FIG. 9 is a diagram showing the film formation state of this embodiment and a comparative example. FIG. 9(a) shows this embodiment, with an interval D. FIG. 9(b) shows a comparative example. The light guide member 1 in this embodiment has a sawtooth-shaped reflecting surface 3 arranged at intervals of 2 mm. When the optical function film 2 is formed on the reflecting surface 3, the inclined surface on which the optical function film 2 is formed is not hidden in the shadow of the adjacent vertical surface 5. In addition, the area near the contact point (part B) between the inclined reflecting surface 3 and the adjacent vertical surface 5 is opened widely, which improves the problem that the film formation material is difficult to penetrate. The optical function film 2 can be formed uniformly over the entire surface of the inclined reflecting surface 3.

[0035] Measurements were carried out to confirm the above-described phenomenon. Figure 10 is a photograph of the prepared experimental sample. Figure 11 is a schematic diagram of inclined surface 503 in experimental structure 501. Inclined surface 503a has no adjacent vertical surface on the left side where inclined surface 503a opens. In other words, inclined surface 503a has no structure that blocks the deposition material incident from the left side of the drawing. In contrast, inclined surface 503b has a structure that is in the shadow of inclined surface 503a. A dielectric multilayer film was formed on this sample, and the reflectance of each portion (502a to 502c and 512a to 512c) was measured by microspectroscopy.

[0036] The measurement results are shown in FIG. 12. FIG. 12(a) shows the measurement results at various points on inclined surface 503a that has no adjacent inclined surfaces. FIG. 12(b) shows the measurement results at various points on inclined surface 503b that has adjacent inclined surfaces. Clearly, the measurement results in FIG. 12(b) show large differences at three points. Inclined surface 503b shows non-uniform optical characteristics. This is due to the flying mechanism of the film-forming material during film formation, as explained above.

[0037] By providing the distance D as in this embodiment, it is possible to obtain desired optical characteristics that can reduce unevenness in the amount of light and improve the image quality of the projected image.

[0038] Next, a light guide member 601 according to a first modified example of this embodiment will be described. The light guide member 1 produced in this embodiment has a shape of a parallel plate, but is not limited thereto. By changing the transfer surface of the flat plate mold 16 and the flat plate mold 18 shown in FIG. 6A and FIG. 6B described in the manufacturing method from a flat surface to a curved surface, a light guide member 601 having a curvature 20 in its outer shape can be obtained as shown in FIG. 13. This allows a lens curve to be formed in the light guide member 601 when applied to a glass device or the like, thereby improving the visibility of the wearer. By forming a lens curve, the gap between the face and the glass device can be narrowed, thereby reducing the incidence of unnecessary light from the gap, which has the effect of improving visibility.

[0039] Next, a light guide member 602 of a second modified example will be described. When a thermosetting resin 15 is applied and cured on a structure 17 in which a plurality of reflecting surfaces 3 on which an optical function film 2 is formed are arranged, as in this embodiment, the structure may warp due to the influence of cure shrinkage (FIG. 14). In that case, as shown in FIG. 15, a construction method is used in which the thermosetting resin 15 is sandwiched between separate flat plate structures 21, thereby improving the warping problem described above.

[0040] Next, a light guide member 603 of a third modified example will be described. The reflecting surfaces 3 of the light guide member 1 in this embodiment are arranged in a sawtooth waveform. The present invention is not limited to this, and as a modified example, it is possible to arrange the reflecting surfaces 3 in a triangular waveform such that the interval D is an inclined surface, as shown in FIG. 16. This allows the first structure to be easily and accurately manufactured. When manufactured as shown in FIG. 6A, if the interval D is inclined, it becomes a draft slope, and the mold release resistance is reduced, so that deformation when released from the mold is suppressed. There is also an effect that the shrinkage difference depending on the location is reduced because there is little sudden change in the wall thickness.

[0041] A detailed configuration of this embodiment is shown in Fig. 17. Intermediate surface 55 exists between first convex portion 53a and first convex portion 53b. The difference from Fig. 4 is that intermediate surface 55 is not parallel to first surface 52 and second surface 62, and has an inclination in the opposite direction to first inclined surface 54. In other words, intermediate surface 55 does not need to be parallel to first surface 52 and second surface 62 as in Fig. 4.

[0042] <Second embodiment> Next, a second embodiment will be described. Fig. 18 shows a light guiding member 701 for a virtual image display 6 according to the second embodiment.

[0043] Two structures (17, 17') are prepared, each having a plurality of reflective surfaces 3 arranged at a distance D. These are an example of a first structure and a third structure, respectively. One of the two structures (17, 17'), structure 17, is inverted, and the two structures (17, 17') are stacked and closely adhered to each other to form a light-guiding member 701. The gap between the two structures (17, 17') is filled with an intermediate member 22 (an example of a second structure).

[0044] Here, as in the first embodiment, the light-guiding member 701 guides image light 9 from the image display element 7 and splits the image light 9 into reflected light 10 and transmitted light 11, and the reflected light 10 is guided from the light-guiding member 701 to the outside.

[0045] 19 is a diagram illustrating the configuration of this embodiment in detail. A light guiding member 701 is an example of the light guiding member 701. A light-guiding member 701 of this embodiment has a first surface 102, a second surface 302 facing the first surface 102, and a plurality of reflecting mirrors formed in a region between the first surface 102 and the second surface 302, each of which has a reflecting surface 3 non-parallel to the first surface 102 and the second surface 302. The light-guiding member 701 includes at least a first structure 101, a second structure 201, and a third structure 301. The first structure 101 includes the first surface 102, a first intermediate surface 105 located between the first surface 102 and the second surface 302, and at least one first convex portion 103 each protruding from the first surface side to the second surface 302 side. The at least one first convex portion 103 each has a first inclined surface 104 inclined with respect to the first surface 101. The third structure 301 includes the second surface 302, a second intermediate surface 305 located between the second surface 302 and the first intermediate surface 105, and at least one second convex portion 303 protruding toward the first surface 102, and the at least one second convex portion 303 each has a third inclined surface 304 inclined with respect to the second surface 302, the second structure 201 is provided between the first structure 201 and the third structure 301, and includes a second inclined surface 204a facing the first inclined surface 104 of the first structure and a fourth inclined surface 204b facing the third inclined surface 304 of the third structure 301, and an optical function film 2 is provided between the first inclined surface 104 and the second inclined surface 204a and between the third inclined surface 304 and the fourth inclined surface 204b.

[0046] This makes it possible to appropriately control the thickness of the optical function film 2 formed on each reflecting surface 3.

[0047] <Manufacturing method> Next, a method for manufacturing the light guiding member 701 will be described. A flowchart of this manufacturing method is shown in Fig. 20. Fig. 21 is a diagram for explaining the method for manufacturing the light guiding member 701 in this embodiment.

[0048] Two structures (17, 17') are fabricated in which multiple reflecting surfaces 3 are arranged with a predetermined distance D between them (FIG. 21(a), step S11 in FIG. 20). As shown in FIG. 20, structure 17 is an example of the first structure, and structure 17' is an example of the third structure. Here, the distance D is 3 mm, and the reflecting surfaces 3 have a sawtooth wave shape with a width of 2 mm and a height of 2 mm. The two structures (17, 17') are made of polycarbonate resin, which is a thermoplastic resin, and are molded by injection molding.

[0049] Next, a dielectric multilayer film is formed on the structures 17 and 17' (Step S12 in FIG. 20).

[0050] Next, an epoxy-based thermosetting resin 15 is applied and laminated on the optical function film 2 on the reflecting surface 3 of one of the structures 17' (FIG. 21(b), step S13 in FIG. 20).

[0051] Next, the other structure 17 is turned over and brought into close contact with the upper surface of the thermosetting resin 15 (step S14 in FIG. 20). Thereafter, the thermosetting resin 15 is heated to a gelling temperature or higher by a heating means (not shown) to be solidified (FIG. 21(a), step S15 in FIG. 20).

[0052] As a result of the above, a resin light guide member 701 is produced, which is composed of two structures (17, 17') in which a plurality of inclined reflecting surfaces 3 are arranged, and an intermediate member 22 which is a second structure that bonds the two structures and is made of thermosetting resin 15. The intermediate member 22 is an example of the second structure.

[0053] Since the two structures (17, 17') have the reflecting surfaces 3 arranged at an interval as in the first embodiment, a uniform optical function film 2 can be formed on the reflecting surface 3.

[0054] The manufacturing method of this embodiment is a manufacturing method for a light-guiding member having a first surface, a second surface opposite to the first surface, and a plurality of reflectors formed in an area between the first surface and the second surface, each having a reflecting surface non-parallel to the first surface and the second surface, and is characterized by including a first step (step S11 in FIG. 20) of forming a first structure including the first surface, a plurality of first convex portions located between the first surface and the second surface, protruding from the first surface side to the second surface side, and having a first reflecting surface, and a first intermediate surface provided between the plurality of first convex portions, a second step (step S12 in FIG. 20) of forming an optical function film on the first inclined surface, and a third step (step S15 in FIG. 20) of forming a second structure including a second inclined surface opposite to the first inclined surface of the first structure and a surface in contact with the first intermediate surface.

[0055] In the light guide member 701 of this embodiment, by overlapping two structures (17, 17'), the reflective surfaces 3 on which the optical function films 2 are formed can be arranged more densely or continuously as necessary. In the second example, the interval D between the reflective surfaces 3 of the structures 17 is set to 3 mm, which is larger than the interval D of 2 mm in the first embodiment, but the interval between the reflective surfaces 3 of the fabricated light guide member 701 is narrower in the second embodiment than in the first embodiment.

[0056] In the first embodiment, the larger the interval D between the reflective surfaces 3 of the structure 17, the easier it is to form the optical function film 2 uniformly. On the other hand, if the interval between the array of the reflective surfaces 3 is widened, the interval between the multiple light beams guided from the light guide member 1 becomes large, and when this light guide member is used in smart glasses, a problem occurs in that the virtual image is missing depending on the location in the eye box. In this embodiment, by combining two structures (17, 17') each having a multiple number of reflective surfaces 3, the interval between the array of the reflective surfaces 3 as the light guide member 701 can be narrowed, and the above two problems can be improved at the same time.

[0057] In this embodiment, the intermediate member 22 made of thermosetting resin 15 is sandwiched between two structures (17, 17'), resulting in a configuration similar to that shown in FIG. 15, and warping of the light-guiding member 701 is suppressed for the same reason as in the second modified example.

[0058] As shown in Fig. 22, when the distance between the reflecting surfaces 3 of the two structures (17, 17') is D, D' is the width of the reflecting surface 3, and L' is L, D' satisfies D ≥ L' and D' ≥ L. This makes it possible to prevent the vertices of the reflecting surfaces (3, 3') of the structures (17, 17') from interfering with each other when the two structures 1 (17, 17') are overlapped.

[0059] As described above, in this embodiment, since the film formed on each reflecting surface can be controlled to a desired thickness, a high-quality projected image can be obtained without unevenness in the amount of image light reflected by the light-guiding member 701. A low-cost and lightweight virtual image display device 6 can be created. It is possible to provide various types of virtual image display devices, not limited to general head-mounted displays and smart glasses.

[0060] <First modified example of the manufacturing method> The manufacturing method is not limited to the above-mentioned manufacturing method. A first modified example of the manufacturing method will be described below. A conceptual diagram of the manufacturing method is shown in FIG. 23, a detailed process is shown in FIG. 24, and a flow chart is shown in FIG. 25. In this modified example, an intermediate structure 23 having a parallelogram cross section as shown in FIG. 23(a) is prepared. A pair of two opposing surfaces of the intermediate structure 23 becomes the partial reflection portion 3, and the optical function film 2 is formed. As shown in FIG. 23(b), the light-guiding member 701 is composed of a plurality of intermediate structures 23, two third structures 17, and a first structure 17'.

[0061] A modified manufacturing method of the light guiding member 701 will be described. Figs. 24(a) to (c) are diagrams for explaining the modified manufacturing method. Fig. 24(a) illustrates parts used in the modified manufacturing method. These parts are a third structure 17 having a sawtooth wave shape, a first structure 17', and a plurality of intermediate structures 23 each having a parallelogram cross-sectional shape. All parts are manufactured by injection molding (step S21 in Fig. 25).

[0062] The slopes of the third structure 17 and the first structure 17' are arranged at an arbitrary interval D. On the other hand, the intermediate structure 23 is prepared in the same number as the slopes of the sawtooth wave-shaped structure (four in the drawing). The width dimension d of the intermediate structure 23 is d≦D.

[0063] An optical function film 2 is formed on a pair of two opposing surfaces that will become the partial reflecting portion 3 of the intermediate structure (FIG. 24(b)). This formation method may be a typical deposition method. With this form, problems such as uneven film thickness due to being shaded by adjacent slopes do not occur (step S22 in FIG. 25).

[0064] As shown in FIG. 24(c), an intermediate structure 23 is laminated on the inclined surface of one of the first structures 17', and then the other third structure 17 is inverted and laminated on top of it (step S23 in FIG. 25). At this time, accuracy is improved by butting to prevent misalignment. The two sawtooth-shaped structures (17, 17') and the intermediate structure 23, the cross section of which is a parallelogram, are closely fixed with an adhesive, and at the same time, gaps between the multiple structures are filled in so as not to form any gaps (step S24 in FIG. 25). In this way, a light-guiding member 701 as shown in FIG. 23(b) is produced.

[0065] By making the distance D between the inclined surfaces of the third structure 17' and the first structure 17 larger than the width dimension d of the intermediate structure 23, the intermediate structure 23 and each structure (17, 17') can be stacked without interfering with each other.

[0066] <Second modified example of the manufacturing method> A second modified example of the manufacturing method is shown in Fig. 26 and its flowchart is shown in Fig. 27. In the second modified example of the manufacturing method, as shown in Fig. 26, after an intermediate structure 23 is laminated on the inclined surface of one of the first structures 17' (step S32 in Fig. 27), a thermosetting resin 15 is laminated and applied (step S32 in Fig. 27). The intermediate structure 23 having a parallelogram cross section of the light guide member 702 thus formed has no unevenness such as a sawtooth wave shape on its surface, so that no parts are shaded during film formation, and the optical function film 2 can be formed uniformly on the specified surface.

[0067] Next, a modification of this embodiment will be described. Fig. 28 is a diagram showing a light guide member 604 of a fourth modification. It is characterized in that the first convex portion 103 and the second convex portion 303 are not in contact with each other. The second structure 201 is sandwiched between the first convex portion 103 of the first structure and the second convex portion of the third structure. When arranging the first convex portion 103 and the second convex portion 303 during manufacturing, a large tolerance can be ensured for the positional accuracy of the arrangement, thereby reducing manufacturing costs.

[0068] In addition, in this modified example, the tips of the first convex portion 103 and the second convex portion 303 are flat. Since the flat portions are brought into close contact with each other during manufacturing, the first structure and the third structure can be brought into close contact with high precision. In other words, there is an advantage in that the parallelism of the inclined surface 104 and the inclined surface 304 can be maintained.

[0069] 29 is a diagram showing a light guiding member 605 of the fifth modification. The first convex portion 103 and the second convex portion 303 are in contact with each other, but the sandwiched interface 306 between them is not perpendicular to the first surface 102 or the second surface 302. This configuration has the advantage that the solidified structure can be easily released from the mold during molding.

[0070] 30 is a diagram showing a light guiding member 606 of a sixth modified example. It is characterized in that the first convex portion 103 and the second convex portion 303 are not in contact with each other. It is characterized in that the surface 106 forming the first convex portion is not in contact with the surface 1306 of the second convex portion. When arranging the first convex portion 103 and the second convex portion 303 during manufacturing, a large tolerance can be ensured for the positional accuracy of the arrangement, and manufacturing costs can be reduced.

[0071] 31 is a diagram showing a light-guiding member 607 of a seventh modification. The seventh modification is characterized in that the first inclined surface 104 and the second inclined surface 204 are not parallel to each other. This has the advantage of increasing the degree of freedom in the reflection direction.

[0072] FIG. 32 is a diagram showing a light guide member 608 of the eighth modified example. The optical function film 152 is a partially reflective film made of a dielectric multilayer film, and separates the image light 9 into a reflected light 10 and a transmitted light 11. In this modified example, the partially reflective film changes the ratio of transmittance to reflectance depending on the location. Specifically, the optical function films are arranged in the order 152a, 152b, 152c, 152d, 152e, and 152f from the incident direction of light (-Y direction). The partially reflective film is formed so that the transmittance of each optical function film gradually decreases (the reflectance increases) in the above-mentioned order. This makes it possible to make the amount of light of the multiple light beams guided to the outside approximately uniform.

[0073] 33 is a diagram showing a light guide member 609 of a ninth modified example. The optical function film 162 is a partially reflective film made of a dielectric multilayer film, and is characterized by having a function of changing the reflectance by polarization. This allows the reflectance to be controlled by polarization. In addition, controlling this polarization can reduce ghost images.

[0074] 34 is a diagram showing a light guide member 610 of a tenth modified example. The optical function film 172 is a partially reflective film made of a dielectric multilayer film, and has the function of a wave plate that rotates polarized light. The wave plate function rotates the polarized light of the light that has passed through the partially reflective film. This makes it possible to change the reflectance of the transmitted light when it enters the next partially reflective film. This makes it possible to control the reflectance by polarized light.

[0075] In addition, the fourth modified example (FIG. 28), the fifth modified example (FIG. 29), the sixth modified example (FIG. 30), the seventh modified example (FIG. 31), the ninth modified example (FIG. 33), and the tenth modified example (FIG. 34) show one first convex portion 103 and one second convex portion 303 in the basic form (FIG. 18) of the second embodiment. The light guide members (604, 605, 606, 607, 609, 610) are required to have at least one first convex portion 103 and one second convex portion 303, and may have a plurality of sets of the first convex portion 103 and the second convex portion 303 as shown in FIG. 18. Also, a plurality of each modified example may be combined.

[0076] As described above, one embodiment of the present invention is as follows.

[0077] <1> The light-guiding member 1 of this embodiment has a first surface 52, a second surface 62 facing the first surface, and a plurality of reflectors formed in a region between the first surface 52 and the second surface 62, each of the reflecting mirrors having a reflecting surface (3 a, 3 b) non-parallel to the first surface 52 and the second surface 62. The light-guiding member 1 includes at least a first structure 51 and a second structure 61. The first structure 51 includes the first surface 52, a first intermediate surface 55 located between the first surface 52 and the second surface 62 and non-perpendicular to the first surface 52, and a plurality of first protrusions ( The first structure 61 includes a first protrusion 53a, a second protrusion 53b, each of which has a first inclined surface 54a, a second protrusion 53b, each of which has a first inclined surface 54a, a second protrusion 61, each of which has a second inclined surface 64a, a second protrusion 64b, each of which faces the first inclined surface 54a, a second protrusion 61, each of which has an optical function film 2a, a second protrusion 61, each of which has an optical function film 2b, a first intermediate surface 55, each of which is provided between the first inclined surfaces 54a, a second intermediate surface 55, and each of which faces the second structure 61. This makes it possible to control the thickness of the film formed on each reflecting surface.

[0078] <2> A light-guiding member 701 of this embodiment includes a first surface 102, a second surface 302 opposed to the first surface 102, and a plurality of reflectors formed in an area between the first surface 102 and the second surface 302, each of which has a reflecting surface 3 non-parallel to the first surface 102 and the second surface 302. The light-guiding member 701 includes at least a first structure 101, a second structure 201, and a third structure 301. The first structure 101 includes the first surface 102, a first intermediate surface 305 located between the first surface 102 and the second surface 302, and at least one first convex portion 303 each protruding from the first surface side to the second surface side. The at least one first convex portion 303 each has a first inclined surface 104 inclined with respect to the first surface 101. The third structure 301 includes the second surface 302, a second intermediate surface 305 located between the second surface and the first intermediate surface 105, and at least one second convex portion 303 protruding toward the first surface, and the at least one second convex portion 303 has a third inclined surface 304 inclined with respect to the second surface, and the second structure 201 is provided between the first structure 201 and the third structure 301, and includes a second inclined surface 204a facing the first inclined surface 104 of the first structure and a fourth inclined surface 204b facing the third inclined surface 304 of the third structure 301, and an optical function film 2 is provided between the first inclined surface 104 and the second inclined surface 204a and between the third inclined surface 304 and the fourth inclined surface 204b. This makes it possible to control the thickness of the film formed on each reflecting surface with high precision. Furthermore, compared to the configuration of the first embodiment, the sawtooth waves can be arranged more densely, which has the advantage of making it possible to suppress defects in virtual images.

[0079] <3> The light guiding member 701 of the present embodiment includes a plurality of the first convex portions and a plurality of the second convex portions, the first intermediate surface is provided between the plurality of first convex portions, and the second intermediate surface is provided between the plurality of second convex portions. <1> or <2> The light-guiding member according to claim 1.

[0080] <4> The light-guiding member 701 of this embodiment is characterized in that the third structure is provided in an area between the first reflecting surface and the second reflecting surface. <1> ~ <3> 2. The light-guiding member according to claim 1 .

[0081] <5> The light-guiding member 701 of this embodiment is characterized in that the first convex portion and the second convex portion are in contact with each other. <1> ~ <4> 2. The light-guiding member according to claim 1 .

[0082] <6> The light guiding member 701 of the present embodiment is characterized in that the apex of the first convex portion and the second intermediate surface are in contact with each other, and the apex of the second convex portion and the first intermediate surface are in contact with each other. <1> ~ <5> 2. The light-guiding member according to claim 1 .

[0083] <7> The light-guiding member 701 of this embodiment is characterized in that an optically functional film is provided between the first reflecting surface and the third structure. <1> ~ <6> 2. The light-guiding member according to claim 1 .

[0084] <8> The light guide member 701 of this embodiment is characterized in that the first convex portion has a surface perpendicular to the first intermediate surface. <1> ~ <7> 2. The light-guiding member according to claim 1 .

[0085] <9> The light guide member 701 of this embodiment is characterized in that, when the height of the first convex portion is L and the interval between the first convex portions is D, D≧LTan (20 deg). <1> ~ <8> The light-guiding member according to claim 1.

[0086] <10> The light guide member 701 of this embodiment is characterized in that, when the interval between the first convex portions is D, the interval between the second convex portions is D', the height of the first convex portions is L, and the height of the second convex portions is L, D≧L' and D'≧L are satisfied. <1> ~ <9> The light-guiding member according to claim 1.

[0087] <11> 3. The light guide member according to claim 1, wherein the first structure, the second structure, and the third structure have substantially the same refractive index.

[0088] <12> The virtual image display device and the head mounted display of the present embodiment are: <1> ~ <11> This is characterized by using the light-guiding member 701 described in 1. This makes it possible to provide a high-definition image.

[0089] <13> The manufacturing method of the present embodiment is a manufacturing method of a light guide member 701 having a first surface, a second surface facing the first surface, and a plurality of reflectors formed in an area between the first surface and the second surface, each having a reflection surface non-parallel to the first surface and the second surface, and includes a first step (step S3) of forming a first structure including the first surface, a plurality of first protrusions located between the first surface and the second surface, protruding from the first surface side to the second surface side, and having a first reflection surface, and a first intermediate surface provided between the plurality of first protrusions, a second step (step S4) of forming an optical function film on the first inclined surface, and a third step (step S6) of forming a second structure including a second inclined surface facing the first inclined surface of the first structure, and a surface in contact with the first intermediate surface. This makes it possible to control the thickness of the film formed on each reflection surface with high accuracy. [Explanation of symbols]

[0090] 1 Light guide member according to the first embodiment (an example of an optical element) 2. Optically functional film (an example of a dielectric multilayer film) 3 reflective surface 4. Spacing D 5 Vertical plane 6 Virtual image display device 7 Image forming element 8 Lens section 9. Image Light 10 Reflected light 11 Transmitted light 12 Inverted Shape 13 Transfer surface 14 Mold 15 Thermosetting resin 16 Flat mold (1) 18 Flat mold (2) 20 Curvature 21 Flat plate structure 22 Intermediate member (an example of the second structure) 17, 51, 101 1st structure 52, 102 1st page 53a, 103a First protrusion (1) 53b, 103b First protrusion (2) 54, 104 1st slope 55, 105 First intermediate surface 19, 61, 201 2nd structure 62, 302 2nd page 64, 304 2nd slope 204a Third slope 204b 4th slope 17′, 301 3rd structure 303 Second convex part 305 Second intermediate surface 152 Optically functional film (An example of a dielectric multilayer film with changed reflectance) 162 Optically functional film (An example of a film with reflectance control function by polarization) 172 Optically functional film (an example of a film with polarizing plate function) 701 Light guide member according to the second embodiment (an example of an optical element)

Claims

1. The first page and a second surface opposite the first surface; and a plurality of reflecting mirrors formed in a region between the first surface and the second surface, each of the reflecting mirrors having a reflecting surface non-parallel to the first surface and the second surface, the optical element includes at least a first structure and a second structure, the first structure includes the first surface, a first intermediate surface that is located between the first surface and the second surface and is not perpendicular to the first surface, and a plurality of first protrusions that each protrude from the first surface side to the second surface side, each of the first protrusions has a first inclined surface inclined with respect to the first surface; the second structure includes a second inclined surface facing the first inclined surface of the first structure, an optical function film is provided between the first inclined surface and the second inclined surface; An optical element, wherein the first intermediate surface is provided between the plurality of first inclined surfaces, and the first intermediate surface faces the second structure.

2. The first page and a second surface opposite the first surface; and a plurality of reflecting mirrors formed in a region between the first surface and the second surface, each of the reflecting mirrors having a reflecting surface non-parallel to the first surface and the second surface, the optical element includes at least a first structure, a second structure, and a third structure, the first structure includes the first surface, a first intermediate surface located between the first surface and the second surface, and at least one first protrusion each protruding from the first surface side to the second surface side, the at least one first protrusion has a first inclined surface inclined with respect to the first surface, the third structure includes the second surface, a second intermediate surface located between the second surface and the first intermediate surface, and at least one second convex portion protruding toward the first surface, the at least one second convex portion each having a third inclined surface inclined with respect to the second surface, the second structure is provided between the first structure and the third structure, and includes a second inclined surface facing the first inclined surface of the first structure and a fourth inclined surface facing the third inclined surface of the third structure, An optical element, comprising: an optical function film provided between the first inclined surface and the second inclined surface and between the third inclined surface and the fourth inclined surface.

3. The contact hole includes a plurality of the first convex portions and a plurality of the second convex portions, the first intermediate surface is provided between the plurality of first convex portions, and the second intermediate surface is provided between the plurality of second convex portions.

3. The optical element according to claim 2.

4. The third structure is provided in a region between the first reflecting surface and the second reflecting surface.

3. The optical element according to claim 2.

5. The first protrusion and the second protrusion are in contact with each other.

3. The optical element according to claim 2.

6. An apex of the first convex portion and the second intermediate surface are in contact with each other, and an apex of the second convex portion and the first intermediate surface are in contact with each other.

3. The optical element according to claim 2.

7. An optically functional film is provided between the first reflecting surface and the third structure.

3. The optical element according to claim 2.

8. The first protrusion has a surface perpendicular to the first intermediate surface.

3. The optical element according to claim 1 or 2.

9. When the height of the first protrusion is L and the interval between the first protrusions is D, D≧LTan(20deg) 3. The optical element according to claim 1, wherein

10. When the interval between the first convex portions is D, the interval between the second convex portions is D', the height of the first convex portions is L, and the height of the second convex portions is L, D≧L′ and D′≧L 3. The optical element according to claim 2, wherein

11. The first structure, the second structure, and the third structure have the same refractive index.

3. The optical element according to claim 1 or 2.

12. A virtual image display device comprising the optical element according to claim 1 or 2.

13. The first page and a second surface opposite the first surface; and a plurality of reflecting mirrors formed in a region between the first surface and the second surface, each of the reflecting mirrors having a reflecting surface non-parallel to the first surface and the second surface, the method comprising the steps of: a first step of forming a first structure including the first surface, a plurality of first convex portions located between the first surface and the second surface, protruding from the first surface side toward the second surface side, and having a first reflecting surface, and a first intermediate surface provided between the plurality of first convex portions; a second step of forming an optically functional film on the first inclined surface; a third step of forming a second structure including a second inclined surface facing the first inclined surface of the first structure and a surface in contact with the first intermediate surface; A method for manufacturing an optical element, comprising:

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