JP7503475B2 - Method for manufacturing an optical reflecting element for use in an optical imaging device - Google Patents

Description

The present invention relates to a method for manufacturing a light reflecting element for use in an optical imaging device in which a pair of light reflecting elements each having a number of light reflecting layers arranged in parallel at a predetermined interval perpendicular to one side of the device are arranged so that the light reflecting layers are perpendicular to each other.

As shown in Patent Document 1, the applicant proposed an optical imaging device that uses first and second light control panels formed by arranging multiple band-shaped planar light reflecting layers at a constant pitch perpendicular to one side of a transparent flat plate inside the transparent flat plate, and forms one side of each of the first and second light control panels facing each other with the planar light reflecting layers perpendicular to each other. Patent Document 2 discloses a manufacturing method for an optical imaging device that forms a real image of an object at a plane-symmetrical position on the opposite side. Patent Documents 3 and 4 disclose large-scale optical imaging devices.

International Publication No. 2009/131128 Patent No. 5085767 International Publication No. 2013/179405 JP 2013-101230 A

However, in the manufacturing methods for optical imaging devices described in Patent Documents 1 and 2, even if the accuracy of the light reflecting elements (light control panels) used in the optical imaging devices differed slightly, no problems arose because the corners of a single optical imaging device were not used.However, when manufacturing a large optical imaging device by bonding (tiling) multiple optical imaging devices together as described in Patent Documents 3 and 4, it was necessary to accurately align the end faces of each optical imaging device.
Furthermore, when the optical imaging device is polished to adjust the length and width after it has been completed, problems occur such as chipping of the light reflecting elements or misalignment of the light reflecting elements that constitute the optical imaging device.

The present invention was made in consideration of these circumstances, and aims to provide a method for manufacturing a light reflecting element for use in an optical imaging device that improves the dimensional accuracy of the end face of the light reflecting element, and that can provide a clear real image by correctly aligning the light reflecting layers of adjacent light reflecting elements or optical imaging devices even when multiple light reflecting elements or optical imaging devices are arranged side by side.

The present invention provides a method for manufacturing an optical reflecting element for use in an optical imaging device that forms an image of an object disposed in one space as a real image in the other space, the method comprising the steps of:
a first step of forming a first laminated block by stacking and fixing a plurality of (usually about 200 to 1000) rectangular (preferably square) transparent plates, each having a light reflecting layer formed on at least one surface, via a first adhesive that is difficult to peel, in a direction perpendicular to the light reflecting layer, and pressing and fixing first to fourth support members, via a second adhesive that is peelable, to surfaces A and B at the top and bottom in the thickness direction of the original laminate, and surfaces C and D opposing the surfaces C and D perpendicularly thereto;
a second step of cutting the first laminated block together with the first to fourth support members at equal intervals in a direction perpendicular to the light reflecting layer to manufacture a light reflecting element raw material;
a third step of polishing the cut surfaces of the cut raw light reflecting element with the cut pieces of the first to fourth support members fixed thereto (the thickness of the raw light reflecting element thus produced is denoted by t);
a fourth step of stacking a plurality of light reflecting element materials, which have been polished in the third step and from which the cut pieces of the first to fourth support members have been removed, and bonding the stacked light reflecting element materials with a third adhesive that is removable, to form a second laminated block;
a fifth step of polishing the opposing surfaces C' and D' of the second laminate block to adjust the width of the light reflecting element material to a specified value;
and a sixth step of removing the third adhesive to form the light reflecting element.

Thereafter, two light reflecting elements can be bonded with a transparent fifth adhesive so that the light reflecting layers of each element are perpendicular to each other in a plan view to form an optical imaging device, or the ends of the light reflecting elements can be joined to form a larger light reflecting element, and then two large light reflecting elements can be bonded with their reflecting surfaces (light reflecting layers) perpendicular to each other to form a large optical imaging device. Also, a large optical imaging device can be formed by arranging a plurality of optical imaging devices with their ends abutting each other.
In the manufacturing method of the light reflecting element of the present invention, after the fourth step and before the fifth step, at least the ends of faces E to H of the second laminate block which are perpendicular to and surround the polished faces C' and D' may be reinforced with a peelable fourth adhesive (reinforcing step 4A around the polished faces).

In the manufacturing method of the light reflecting element according to the present invention, it is preferable to bond fifth to eighth reinforcing support members to faces E to H that are orthogonal to and surround face C' and face D' with a fourth peelable adhesive before the fifth step, thereby preventing the occurrence of scratches in the second laminated block. In this case, the reinforcing step 4A around the polished face is not performed.

In the method for manufacturing a light reflecting element according to the present invention, it is preferable that the opposing sixth and eighth reinforcing support members surrounding or sandwiching the second laminated block are arranged in a state where they sandwich the opposing fifth and seventh reinforcing support members.

In the method for manufacturing a light reflecting element according to the present invention, if the thickness of the original laminate is h, it is preferable that the width w of the light reflecting element obtained from the polished second laminate block is in the range of h±0.5 mm, and the shape of the light reflecting element in a plan view is square. This allows paired light reflecting elements to be used in an optical imaging device to be manufactured simultaneously.

In the method for manufacturing a light reflecting element according to the present invention, the cut pieces of the first and second support members may be removed after the fifth step.
In the present invention, the first adhesive (fifth adhesive) may be, for example, a thermosetting resin-based adhesive having self-hardening or thermosetting properties, an epoxy-based adhesive, an elastomer-based adhesive, or other adhesive that can firmly bond the rectangular transparent plate may be used. In addition, the second to fourth adhesives are preferably a thermoplastic adhesive that melts when heated (for example, heated to 80° C.) or a water-soluble adhesive, but the present invention is not limited to these types of adhesives.

In the manufacturing method of the light reflecting element according to the present invention, when the end of the light reflecting element material is polished, chipping or misalignment of the rectangular transparent plate is unlikely to occur, and a light reflecting element with high dimensional accuracy can be manufactured. This makes it easy to manufacture a large optical imaging device. In other words, since light reflecting elements of the same size can be manufactured, a large light reflecting element can be manufactured by arranging multiple light reflecting elements, and this light reflecting element can be bonded so that each light reflecting layer is perpendicular to each other to form a large optical imaging device.
In addition, because the precision of each light reflecting element is high, for example, 4, 9, or 16 light reflecting elements can be arranged on a plane to form a larger light reflecting element. Furthermore, it is also easy to manufacture a large optical imaging device by tiling optical imaging devices that combine light reflecting elements.

FIG. 2A is an explanatory diagram of a glass plate, and FIG. 2B is an explanatory diagram of a first step of a manufacturing method for a light reflecting element according to one embodiment of the present invention. 4 is an explanatory diagram of a second step of the manufacturing method of the light reflecting element. FIG. 13A and 13B are a perspective view and a side view, respectively, of the light reflecting element raw material manufactured in the second step. (A) is an oblique view of the light reflecting element material from which the cut pieces of the first to fourth support members have been removed, and (B) is an oblique view of a second laminated block formed by stacking multiple sheets of the same light reflecting element material. FIG. 1A is an explanatory diagram of joining the fifth to eighth reinforcing support members to a second laminated block, and FIG. 1B is an oblique view of the second laminated block with the fifth to eighth reinforcing support members joined thereto. 1A is a perspective view of a pair of light reflecting elements, and FIG. 1B is a perspective view of an optical imaging device in which light reflecting elements are bonded together with their light reflecting layers perpendicular to each other. FIG. 11 is a plan view showing a plurality of light reflecting elements arranged and bonded together.

Next, with reference to Figures 1 to 7, a method for manufacturing a light reflecting element used in an optical imaging device according to a first embodiment of the present invention will be described. As shown in Figures 1(A) and (B), in order to finally manufacture a light reflecting element 10 (see Figures 6(A) and (B)), a glass plate material 12a is used, which has a transparent glass plate 11, which is an example of a rectangular transparent plate, and a light reflecting layer 12 provided on one surface of the glass plate 11. The glass plate 11 is, for example, approximately square with sides of approximately 80 to 500 mm, but may also be rectangular. The thickness of the glass plate 11 is, for example, 0.1 to 4.0 mm. The rectangular transparent plate may be formed from a transparent synthetic resin material (plastic), such as acrylic resin.

The glass plate 11 used is flat on both sides and has a uniform thickness to the extent possible. A light reflecting layer 12 is formed on the glass plate 11 by metal deposition of aluminum, silver, etc. Instead of metal deposition, the light reflecting layer 12 may be formed by a method such as sputtering, spraying, or plating. The thickness of the light reflecting layer 12 is preferably about 50 to 400 nm, for example, but is not limited to this value. The light reflecting layer 12 may be formed on both sides of the glass plate 11.

A predetermined number of glass plates 11 (i.e., glass plate materials 12a) on which a light-reflecting layer 12 is formed (for example, 500 to 1000 sheets) are prepared and laminated in a direction perpendicular to the light-reflecting layer 12 via a transparent first adhesive to form the original laminate 13. Before the first adhesive hardens, each glass plate material 12a is pressed with a flat body such as a press with sufficient pressure on faces A and B, and faces C and D to uniformly stretch the first adhesive, and it is preferable to maintain the thickness h (the distance between faces A and B) and the flatness and parallelism of faces C and D as much as possible (not shown). As the first adhesive, it is preferable to use a self-hardening or heat-hardening adhesive that hardens over time (difficult-to-peel adhesive). This determines the height h and width w, which are the dimensions of the original laminate 13 (w>h). Note that the height h does not change, but w becomes smaller by polishing.

Here, the first and second support members 15, 16 are pressed against the upper and lower surfaces A and B of the original laminate 13 in the thickness direction via the second adhesive, and the third and fourth support members 17, 18 are pressed against the opposing surfaces C and D of the original laminate 13 perpendicular to the surfaces A and B via the second adhesive. Here, it is preferable to make the width of the first and second support members 15, 16 smaller than the width between the surfaces C and D of the original laminate 13 so that they are inserted between the third and fourth support members 17, 18 with a gap. Here, it is preferable to use, as the second adhesive, an adhesive that melts (liquefies) when heated (for example, heated to 80° C.) and solidifies firmly at room temperature (usually called wax), or a water-soluble adhesive (the above are peelable adhesives).
The thickness h of the original laminate 13 is adjusted to be smaller than the width (interface distance) w of the faces C and D by adjusting the number of glass plates 12a. This allows the shape of the light reflecting element 10, which is the final product, to be adjusted to a square with h = w (preferably within ±0.1 mm, but this is not an essential requirement). The reason for this is that the width w between the faces C and D can be adjusted in a decreasing direction during the polishing process. This results in the first laminate block 19 shown in Figure 2 (the first step).

Next, the first laminated block 19, in which the first to fourth support members 15 to 18 have been joined (pressed and fixed) to the original laminate 13 to which the glass plate material 12a has been laminated and fixed, is fixed to a mounting table (not shown) with the first support member 15 facing up, and as shown in FIG. 2, the first laminated block 19 is simultaneously cut (sliced) to a predetermined thickness (equally spaced) together with the first to fourth support members 15 to 18 from above the first support member 15 in a direction perpendicular to the light reflecting layer 12 of each glass plate material 12a using a multi-wire saw 20, to form a plurality of light reflecting element original materials 25 with cut pieces 21 to 24 of the first to fourth support members 15 to 18 fixed to the periphery as shown in FIG. 3(A) and (B) (the second step).

Then, the light reflecting element raw material 25 is horizontally aligned, and both sides of the light reflecting element raw material 25 are optically polished (mirror polished) with the surrounding cut pieces 21-24 attached, preferably to a surface arithmetic mean roughness Ra of about 1-0.1 μm or less (the same applies to the following polishing). In this case, since the cut pieces 21-24 of the support members 15-18 are attached to the periphery of the light reflecting element raw material 25, there is an advantage that the glass plate material 12a is not chipped or rolled up during cutting and polishing. The thickness t of each light reflecting element raw material 25 is adjusted to a constant value, taking into account the thickness at the time of cutting and the polishing allowance at the time of polishing (the third step). In the figure, the four consecutive ▽ marks indicate ultra-precise optical polishing.

Next, as shown in FIG. 4(A), the cut pieces 21-24 around the light reflecting element raw material 25 are removed by heating or using a liquid (solvent), and the light reflecting element material 25a is laminated via a peelable third adhesive (same as the second adhesive) as shown in FIG. 4(B) to form a second laminated block 27 (the fourth step). Note that if the light reflecting element material 25a is simply laminated, the flatness of the opposing surfaces C' and D' of the second laminated block 27 is poor, so it is preferable to press the surfaces C' and D' with a flat plate (not shown) before the third adhesive hardens. With the surfaces C' and D' aligned to a certain extent, the opposing surfaces C' and D' of the second laminated block 27 are optically polished as shown in FIG. 4(B). At this time, it is advisable to match the distance w between the optically polished surfaces C'' and D'' (the width of the light reflecting element 10) to the thickness h of the original laminate 13 within a range of ±0.5 mm, preferably within a range of ±0.1 mm (this is the fifth step).

After this, the third adhesive is released to disassemble the second laminated block 27 into a number of light reflecting elements 10. Each light reflecting element 10 has a thickness of t and a square shape with sides of h (=w) in plan view (when the cut surface is viewed from the front) (the sixth step). Therefore, as shown in FIG. 6(A), two light reflecting elements 10 are prepared, and the light reflecting layers 12 are arranged so as to be perpendicular in plan view, and are joined with a transparent fifth adhesive (the same as the first adhesive), completing an optical imaging device 30 with a thickness of 2t. This optical imaging device 30 can form an image of an object placed in one space as a real image in the other space.

In the above embodiment, the surfaces C' and D' were polished without providing a support member (protective member) around the second laminated block 27, but if a reinforcing support member is provided around the second laminated block 27 and polished, chipping during polishing will not occur, so an embodiment that prevents this will be described with reference to Figures 5 (A) and (B). That is, in the fourth step or between the fourth and fifth steps, multiple sheets of light reflection element material 25a are laminated on the fifth reinforcing support member 35 via a third adhesive that is easily peeled off to form the second laminated block 27. The fifth to eighth reinforcing support members 35 to 38 are attached via a fourth adhesive that can be peeled off to the fifth to eighth surfaces (surfaces E to H) 31 to 34 that surround the second laminated block 27 on the side surfaces perpendicular to the surfaces C' and D' of the second laminated block 27 (note that the fifth reinforcing support member 35 becomes the bottom plate). Here, it is preferable that the width of the fifth and seventh reinforcing support members 35, 37 is h (or shorter than h to a small extent) and that they are sandwiched between the sixth and eighth reinforcing support members 36, 38. This prevents scratches and curling of the second laminated block 27 during polishing.

Although the cut pieces 21 to 24 are removed in the third step, it is also possible to remove only the cut pieces 23 and 24.
In the above embodiment, the rectangular transparent plate is a glass plate, but a transparent resin plate can also be used. Also, in the above embodiment, the light reflecting element is square in plan view, but it may be rectangular.
In the above embodiment, a light reflecting layer is provided on each glass plate, but it is also possible not to form a light reflecting layer on the glass plates at the ends.
Furthermore, after the fourth step and before the fifth step, the ends of faces E to H which are perpendicular to faces C' and D' of the second laminate block and surround the second laminate block may be reinforced with a fourth removable adhesive (e.g., wax), and faces C' and D' may be polished in the fifth step. This further reinforces the side faces of the second laminate block, preventing chipping during polishing.

Figure 7 shows a large light reflecting element 40 in which multiple light reflecting elements 10 (four in this embodiment, but nine, sixteen, or other numbers are also acceptable) manufactured by the above process are aligned with the light reflecting layers 12 oriented in the same direction and bonded horizontally side-by-side, and the element is placed on a transparent flat base 41 and held in a predetermined position by two positioning members 43, 44 arranged at right angles and pressure members 45, 46. In this case, since the shape of each light reflecting element 10 is the same, the positions of the light reflecting layers 12 of adjacent light reflecting elements 10 can be aligned, allowing a larger optical imaging device to be manufactured.

10: Light reflecting element, 11: Glass plate, 12: Light reflecting layer, 12a: Glass plate material, 13: Original laminate, 15: First support member, 16: Second support member, 17: Third support member, 18: Fourth support member, 19: First laminate block, 20: Wire saw, 21-24: Cut pieces, 25: Light reflecting element original material, 25a: Light reflecting element material, 27: Second laminate block, 30: Optical imaging device, 31-34: Fifth to eighth surfaces, 35-38: Fifth to eighth reinforcing support members, 40: Large light reflecting element, 41: Planar base, 43, 44: Positioning member, 45, 46: Pressing member

Claims (4)

A method for manufacturing an optical reflecting element for use in an optical imaging device that forms an image of an object placed in one space as a real image in the other space, comprising:
a first step of forming a first laminated block by stacking and fixing a plurality of rectangular transparent plates, at least one of which has a light reflecting layer formed on it, in a direction perpendicular to the light reflecting layer via a first adhesive, and pressing and fixing first to fourth support members to surfaces A and B on the top and bottom in the thickness direction of the original laminate, and surfaces C and D opposing the surfaces C and D perpendicular to the surfaces A and B, respectively, via a peelable second adhesive;
a second step of cutting the first laminated block together with the first to fourth support members at equal intervals in a direction perpendicular to the light reflecting layer to manufacture a light reflecting element raw material;
a third step of polishing the cut surfaces of the cut raw light reflecting element with the cut pieces of the first to fourth support members fixed thereto;
a fourth step of stacking a plurality of light reflecting element materials, which have been polished in the third step and from which the cut pieces of the first to fourth support members have been removed, and bonding the stacked light reflecting element materials with a third adhesive that is removable, to form a second laminated block;
a fifth step of polishing the opposing surfaces C′ and D′ of the second laminate block to adjust the width of the light reflecting element material to a specified value;
and a sixth step of removing the third adhesive to form the light reflecting element. The method for manufacturing a light reflecting element according to claim 1, characterized in that, before the fifth step, fifth to eighth reinforcing support members are bonded to faces E to H that surround face C' and face D' perpendicularly with a fourth peelable adhesive, thereby preventing the occurrence of defects in the second laminated block. The method for manufacturing a light reflecting element according to claim 2, characterized in that the opposing sixth and eighth reinforcing support members surrounding the second laminated block sandwich the opposing fifth and seventh reinforcing support members. The method for manufacturing a light reflecting element according to any one of claims 1 to 3, characterized in that, when the thickness of the original laminate is h, the width w of the light reflecting element obtained from the polished second laminate block is in the range of h ± 0.5 mm, and the shape of the light reflecting element in plan view is square.

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