Method for manufacturing an optical element, optical element, aerial image display device, and spatial input device

Abstract

To provide a method for manufacturing an optical element which is accurate and can be made larger.SOLUTION: The method for manufacturing an optical element according to the present invention includes the steps of: forming an optical element unit made of such an optical material as glass, the optical element unit having an outer shape of a regular triangle or a regular hexagon as a minimum structure (S100); two-dimensionally arranging a plurality of optical element units on a substrate so that a structure which simulates the molecular structure of graphene or carbon nano-tube is formed (S110); and processing the substrate with the optical element units arranged thereon into a desired surface shape (S120).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an optical element, and particularly to a method for manufacturing a retroreflective member used in an aerial image display device. [Background Art]

[0002] Aerial displays that form an image displayed on a display in the air using a retroreflective member or the like have been proposed. For example, the display device of Patent Document 1 uses two retroreflective members and arranges one of the retroreflective members on the exit axis of a light source, so that an image formed in the air can be observed from a wider angle. In the image display device of Patent Document 2, in order to suppress a decrease in image visibility, the number of times light passes through a retardation member (λ / 4 plate) is reduced, and it is made difficult for dust or the like to enter between the retroreflective member and the retardation member. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2017-107165 [Patent Document 2] Japanese Unexamined Patent Publication No. 2019-66833 [Brief Summary of the Invention] [Problem to be Solved by the Invention]

[0004] As a configuration for obtaining a three-dimensional effect in display, there is an aerial image element that enables stereoscopic viewing by providing a lens structure or a prism structure. FIG. 1 shows a schematic cross-section of a display device using a retroreflective member. As shown in the figure, the display device 10 includes a display 20 that outputs an image, a beam splitter 30, and a retroreflective member 40. Light L1 emitted from the display 20 is reflected by the beam splitter 30, and the reflected light L2 travels to the retroreflective member 40. The retroreflective member 40 reflects light L3 in the same direction as the incident light, the reflected light L3 passes through the beam splitter 30, and displays an aerial image 50 in the space in front of the observer's eyes.

[0005] The aerial image 50 that the observer can see is limited to the range in which the observer can see the retroreflective member 40. In other words, the retroreflective member 40 must be within the observer's field of view. Furthermore, the aerial image 50 is formed in a position symmetrical to the display 20 with respect to the surface of the beam splitter 30. If the display 20 is tilted at a 45-degree angle to the beam splitter 30, the aerial image 50 observed by the observer will be an image viewed from a 45-degree oblique angle.

[0006] Conventional display devices have the following challenges: Retroreflection requires highly accurate optical elements, which are formed by lamination of glass or molding using nanoimprint lithography. If the optical elements are made of resin to reduce costs, it becomes difficult to mold them with high precision, and the larger the size of the optical elements, the more difficult the molding becomes. For this reason, the current maximum size of retroreflective elements is generally around 30 cm.

[0007] On the other hand, there have been attempts to solve these problems by molding retroreflective elements or aerial imaging elements from flexible materials and producing them in roll form. However, because of the flexibility, the shape of the optical elements is also easily deformed, which can lead to a decrease in image quality. Thus, there is a trade-off between high-quality aerial imaging and the ability to enlarge optical elements.

[0008] The present invention aims to solve these conventional problems and provide a method for manufacturing an optical element that is highly accurate and can be scaled up, an aerial image display device, and a spatial input device. [Means for solving the problem]

[0009] The present invention relates to a method for manufacturing an optical element, in which an optical element unit is formed as the minimum structure, having an external shape of an equilateral triangle or a regular hexagon, composed of an optical material, a plurality of optical element units are arranged two-dimensionally on a substrate, and the substrate on which the plurality of optical element units are mounted is processed into a desired surface shape.

[0010] In one embodiment, the plurality of optical units are arranged on the substrate to mimic the molecular structure of graphene or carbon nanotubes. In one embodiment, the optical element unit is formed by molding a glass or resin material using a mold or template. In one embodiment, the desired surface shape is a curved surface. In one embodiment, the optical element unit is a retroreflective element. In one embodiment, the optical element unit is a micromirror. In one embodiment, the optical element unit is a microlens.

[0011] The aerial image display device according to the present invention includes a retroreflective member manufactured by the manufacturing method described above, a light source, and a beam splitter that reflects light from the light source toward the retroreflective member and transmits the light reflected by the retroreflective member.

[0012] The spatial input device according to the present invention includes the aerial image display device described above and a detection means for detecting the proximity of an object to an aerial image displayed by the aerial image display device. [Effects of the Invention]

[0013] According to the present invention, since the optical element is manufactured by arranging optical element units with an external shape of an equilateral triangle or a regular hexagon as the minimum structure, it is possible to provide an optical element that is highly accurate and can be scaled up. [Brief explanation of the drawing]

[0014] [Figure 1] This is a cross-sectional view showing the schematic configuration of a conventional retroreflective display device. [Figure 2] This is a flowchart illustrating a method for manufacturing an optical element according to an embodiment of the present invention. [Figure 3] This figure shows a glass retroreflective element molded into a regular hexagon by the manufacturing method of this embodiment. [Figure 4] This is a diagram illustrating a molecular model of graphene. [Figure 5]FIG. 5(A) is a plan view showing an example in which a plurality of optical element units are arranged on a rectangular substrate, and FIG. 5(B) is a plan view showing an example in which a plurality of optical element units are arranged on a circular substrate. [Figure 6] It is a diagram showing an example where a substrate on which a plurality of optical element units are arranged is processed into a curved surface shape. [Figure 7] It is a diagram showing a method for manufacturing an optical element according to another embodiment of the present invention. [Figure 8] It is a diagram showing the configuration of an aerial image display device using a retroreflective member manufactured according to an embodiment of the present invention. [Figure 9] It is a diagram showing the configuration of a spatial input device using a retroreflective member manufactured according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Next, embodiments of the present invention will be described. The method for manufacturing an optical element according to the present invention provides an upsized optical element by molding glass or resin, which are materials of the optical element, into small pieces by pressing or molding, and arranging the small pieces on a plane or a curved surface, thereby solving the trade-off between high quality and upsizing. This realizes an affordable optical element that can be mass-produced while maintaining high quality. The optical element manufactured according to the present invention can be applied to an aerial display or the like that displays an aerial image. Furthermore, such an aerial display can be applied to a spatial input device that enables user input using an image displayed in air.

[0016] It should be noted that the drawings referred to in the following description of embodiments contain exaggerated representations for facilitating understanding of the invention, and do not represent the actual shape and scale of the product as they are. EXAMPLES

[0017] FIG. 2 is a flow chart illustrating a method of manufacturing an optical element according to an embodiment of the present invention. The method of manufacturing an optical element according to the present embodiment comprises: a step (S100) of forming optical element units each having an equilateral triangular or regular hexagonal outer shape as a minimum structure for constituting the optical element; a step (S110) of two-dimensionally arranging a plurality of optical element units on a substrate; and a step (S120) of processing the substrate mounted with the plurality of optical element units into a desired surface shape.

[0018] The optical element unit has a planar shape of an equilateral triangle or a regular hexagon as the minimum structure. When a plurality of optical element units are arranged to form an arbitrary size and an arbitrary surface shape, the planar shape of the optical element unit is geometrically required to be an equilateral triangle, a quadrilateral, or a regular hexagon. In order to form a curved surface, a spherical surface, or an arbitrary surface shape with the optical element units, equilateral triangles or regular hexagons are more advantageous than quadrilaterals.

[0019] The optical element unit is formed by, for example, glass pressing or glass molding. Specifically, glass softened to a high temperature is poured into an equilateral triangular or regular hexagonal mold or casting mold, and pressure is applied to mold the equilateral triangular or regular hexagonal optical element unit. In press molding, if the mold or casting mold is too large, pressure will not be uniformly applied to the glass material, causing shrinkage cavities and voids, which may reduce the precision of the molded optical element unit. Therefore, in order to mold high-precision optical element units, it is necessary to limit the size of the mold or casting mold to a certain range. In addition, when forming a curved surface or the like from an array of a plurality of optical element units, a smaller size of the optical element units can obtain a smoother curved surface. For example, the optical element unit is molded to a size of about 1 cm. A large number of high-precision optical element units can be mass-produced by such glass pressing or glass molding.

[0020] The optical element unit may be made of resin in addition to glass, and in that case, the resin material is poured into a mold and press-molded or mold-molded. As the resin material, for example, polycarbonate or cycloolefin resins used in optical components may be used.

[0021] The optical properties of an optical element unit are configured to match the optical properties of the target optical element. For example, when a retroreflective element is constructed using multiple optical element units, a retroreflective structure is formed on the surface of the optical element unit. Examples of retroreflective structures include DCRA (dihedral corner reflector array) and triangular pyramidal reflectors. Figure 3 illustrates a glass retroreflective element molded into a regular hexagon. Furthermore, when a microlens is constructed using multiple optical element units, the optical element unit is configured to include concave lenses and convex lenses, and when a micromirror is constructed using multiple optical element units, the optical element unit is configured to include a reflective layer.

[0022] The sides of the optical element unit do not necessarily have to be perpendicular to the bottom surface; they may be inclined so that the sides do not interfere with adjacent optical element units when multiple optical element units are arranged together. Alternatively, engaging parts such as recesses or protrusions may be formed on the sides of the optical element unit so that adjacent optical element units can be physically connected to each other. Furthermore, the bottom surface of the optical element unit may be flat so that adhesive or the like can be applied when mounted on a substrate, or it may have recesses or protrusions that engage with the substrate when placed on the substrate.

[0023] Next, multiple optical element units are arranged two-dimensionally on a substrate like tiles. The size of the substrate is appropriately selected according to the size of the desired optical element. When multiple optical element units are arranged on the substrate, they are arranged in a regular manner to mimic the molecular structure of graphene, carbon nanotubes, or fullerene (C60). Figure 4 shows a molecular model of hexagonal graphene.

[0024] Multiple optical element units are fixed to a substrate, for example, by their bottom surfaces using adhesive. The optical element units may be arranged so that a certain gap is formed between adjacent optical element units, or they may be arranged so that the sides of adjacent optical element units are in contact with each other.

[0025] Figure 5(A) is a plan view showing multiple optical element units 100 arranged on a rectangular substrate 110 to mimic the molecular structure of graphene, and Figure 5(B) is a plan view showing multiple optical element units 100 arranged on a circular substrate 120 to mimic the molecular structure of graphene. The shape, thickness, and material of the substrates 110 and 120 are not particularly limited, but it is desirable that the substrates 110 and 120 be made of a flexible material that can be processed into a desired surface shape. It is also desirable that the substrates 110 and 120 have sufficient strength to maintain their surface shape after processing.

[0026] Here, we have shown an example of arranging hexagonal optical element units, but even when using equilateral triangular optical element units, these units are arranged to mimic the molecular structure of graphene or carbon nanotubes. Furthermore, it is possible to arrange both equilateral triangular and hexagonal optical element units on a substrate.

[0027] Next, the substrate on which multiple optical element units are mounted is processed to have a desired surface shape. The desired surface shape can be, for example, a curved surface, a spherical surface, or a stepped surface, and this surface shape matches the shape of the target optical element. When the substrate is processed to the desired surface shape, the optical element units mounted on the substrate themselves do not deform, but the boundaries between the optical element units are displaced, thereby giving the desired surface shape.

[0028] Figure 6(A) shows an example where the substrate 110 in Figure 5(A) is processed to provide a concave curved surface. In other words, the concave curved surface is formed by multiple optical element units on the substrate 110. Figure 6(B) shows an example where the substrate 110 in Figure 5(A) is processed to provide a convex curved surface. In other words, the convex curved surface is formed by multiple optical element units on the substrate 110. Of course, the substrate 110 can be processed into any surface shape other than those shown in Figures 6(A) and (B).

[0029] The above manufacturing method shows an example in which multiple optical element units are arranged on a flat substrate and then the substrate is processed into a desired surface shape. However, the manufacturing method of the present invention is not necessarily limited to this. In other embodiments of the present invention, a substrate processed to have a desired surface shape may be prepared, and multiple optical element units may be arranged on that substrate. Figure 7 shows the cross-sectional structure of a substrate 130 processed into a concave curved surface. Multiple optical element units 100 may be arranged on the concave curved surface of such a substrate 130 in a manner that mimics the molecular structure of graphene or carbon nanotubes.

[0030] When forming optical elements by high-precision molding of glass or resin, it is usually not possible to curve such optical elements. However, as in this embodiment, by precisely molding equilateral triangular or regular hexagonal optical element units and arranging such optical element units on a substrate, it is possible to easily form optical elements with any planar shape, and also to easily achieve larger optical elements.

[0031] Figure 8 shows an aerial image display device having a retroreflective member manufactured by the manufacturing method of this embodiment. In the aerial image display device 200, light from a light source (for example, an image output device that outputs an image) is reflected by a beam splitter 210, the reflected light proceeds to the retroreflective member 220, the light reflected by the retroreflective member 220 passes through the beam splitter 210, and an aerial image 240 is generated in the space in front of the observer's eye 230.

[0032] The aerial image 240 that an observer can see is limited to the range in which the observer can see the retroreflective member 220. However, by making the retroreflective member 220 a curved surface, the field of view θ of the aerial image 240 is secured (starting with a wide field of view, the aerial image can be viewed from a wide angle). Furthermore, by using a highly precise retroreflective member 240 made by molding glass or resin, a high-quality aerial image 240 and a highly reliable optical element can be realized. Moreover, for example, the cost of producing a single sheet is very high with glass lamination, but with glass press or mold, mass production is possible, allowing for a significant cost reduction, and therefore the cost of the optical element for the aerial image can be reduced.

[0033] Furthermore, although not shown in the illustrations, this method can also be applied to aerial image display devices that display aerial images using micromirrors and microlenses manufactured by the manufacturing method of this embodiment.

[0034] Figure 9 shows a schematic configuration of a spatial input device to which the aerial image display device of this embodiment is applied. The spatial input device 300 includes a housing 310 that houses the aerial image display device 200 as shown in Figure 8, a three-dimensional distance sensor 320 that detects objects (for example, a user's finger) in the aerial image 240, and a controller 340 that controls the image output of the light source 330, etc., based on the detection results from the three-dimensional distance sensor 320.

[0035] When a user looks at the aerial image 240 floating in front of them and places their finger over the displayed position to indicate a desired input, the 3D distance sensor 320 detects the 3D distance of the finger and outputs this to the controller 340. Based on the detection result of the 3D distance sensor 320, the controller 340 calculates the position of the user's finger, determines that the user has manipulated an input related to the aerial image 240, and based on this determination result controls the light source 330 to output another image, or outputs the determination result to an external electronic device (not shown).

[0036] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims. [Explanation of symbols]

[0037] 100: Optical element unit; 110, 120: Substrate 200: Aerial video display device 210: Beam splitter 220: Retroreflective material 230: Observer's eye 240: Aerial imagery 300: Spatial input device

Claims

1. A method for manufacturing an optical element used in an aerial image display device, The process involves forming multiple optical element units with an external shape of an equilateral triangle or regular hexagon as the minimum structure by molding a glass or resin material using a mold or cast, wherein each of the multiple optical element units is separated from the others. The back surfaces of each of the plurality of optical element units are fixed to the surface of the substrate via adhesive, and the plurality of optical element units are arranged on the substrate in a regular two-dimensional manner such that the sides of the optical element units face the sides of adjacent optical element units and no defects occur in the optical element units. A manufacturing method for processing a substrate on which the aforementioned plurality of optical element units are mounted into a desired surface shape.

2. A method for manufacturing an optical element used in an aerial image display device, The process involves forming multiple optical element units with an external shape of an equilateral triangle or regular hexagon as the minimum structure by molding a glass or resin material using a mold or cast, wherein each of the multiple optical element units is separated from the others. The substrate is processed to the desired surface shape, A manufacturing method comprising fixing the back surface of each of the plurality of optical element units to the surface of a substrate via an adhesive, and arranging the plurality of optical element units in a regular two-dimensional manner on the substrate processed to the surface shape, such that the side surfaces of the optical element units face the side surfaces of adjacent optical element units and no defects occur in the optical element units.

3. The manufacturing method according to claim 1 or 2, wherein the plurality of optical element units are arranged on the substrate such that the side surfaces of the optical element units are in contact with the side surfaces of adjacent optical element units.

4. The manufacturing method according to claim 1 or 2, wherein the desired surface shape is a curved surface.

5. The manufacturing method according to claim 1 or 2, wherein the optical element unit is a retroreflective element.

6. The manufacturing method according to claim 1 or 2, wherein the optical element unit is a micromirror.

7. The manufacturing method according to claim 1 or 2, wherein the optical element unit is a microlens.

8. A retroreflective member comprising a substrate processed to a desired surface shape and a plurality of retroreflective element units mounted on the substrate, The retroreflective element unit is composed of a single unit having an equilateral triangle or regular hexagonal shape and is separated from adjacent retroreflective element units, and the plurality of retroreflective element units are arranged regularly in two dimensions on the substrate so that the sides of the retroreflective element units face the sides of adjacent retroreflective element units and no defects occur in the retroreflective element units, and the bottom surface of each of the plurality of retroreflective element units is fixed to the substrate with an adhesive, in a retroreflective member.

9. The retroreflective member described in claim 8, Light source and A beam splitter that reflects light from the light source toward the retroreflective member and transmits the light reflected by the retroreflective member, Aerial image display device including

10. An aerial image display device comprising a retroreflective member as described in claim 8, a light source, and a beam splitter that reflects light from the light source toward the retroreflective member and transmits the light reflected by the retroreflective member, A detection means for detecting the proximity of an object to an aerial image displayed by the aerial image display device, A spatial input device that includes [a specific component].

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