Patent Application
20200031712
The present invention relates to a method for manufacturing a light control panel for use in an optical imaging device that forms an image in the air, and the like.
Conventionally, a light control panel in which a large number of strip-shaped reflective surfaces are formed with a constant pitch in a direction that is perpendicular to a thickness direction of the light control panel is known as an optical element for forming an image in the air. An optical imaging device that forms an image in the air can be configured by using two such light control panels, and stacking the two light control panels one on top of the other such that their strip-shaped reflective surfaces are substantially orthogonal to each other.
Patent Document 1, for example, discloses a method for manufacturing a light control panel. In this manufacturing method, a light control panel is formed by forming a block in which transparent sheets (glass, transparent plastic, etc.) and mirror sheets (mirror sheets to which a UV-curable adhesive is applied) are alternatingly stacked and then cutting the block into a constant thickness along a plane that intersects the transparent sheets. The transparent sheets and the mirror sheets are joined together with the UV-curable adhesive.
Patent Document 1: WO 2014/073650
Incidentally, in the conventional light control panel, adhesive layers (adhesive layers formed of the UV-curable adhesive) are provided between adjacent ones of a large number of glass pieces that are stacked one on top of another. In the light control panel, a large number of adhesive layers are provided. Therefore, a large amount of adhesive is required in order to manufacture a light control panel, and it is difficult to manufacture a light control panel at low cost.
The present invention was made in view of the foregoing circumstances, and it is an object thereof to reduce the manufacturing cost of a light control panel by reducing an adhesive that is used to manufacture the light control panel.
In order to address the above-described problems, a method for manufacturing a light control panel according to the present invention is a method for manufacturing a light control panel in which a large number of strip-shaped reflective surfaces are formed with a constant pitch in a direction that is perpendicular to a thickness direction of the light control panel, the method including a stacking step of directly stacking a large number of elongated flat plate-shaped glass pieces one on top of another, thereby producing a glass stack, which has a flat plate-like shape and in which the large number of glass pieces are lined up in a direction that is perpendicular to a thickness direction of the glass stack, and an integrating step of integrating the large number of glass pieces of the glass stack.
The integrating step of this manufacturing method may include a step of applying a transparent adhesive to at least one of one side of the glass stack and one side of a transparent cover plate, a step of stacking the cover plate on one side of the glass stack such that the adhesive is sandwiched between the glass stack and the cover plate, and a step of forming an adhesive layer by curing the adhesive between the glass stack and the cover plate.
Moreover, this manufacturing method may further include a cutting step of cutting a transparent glass sheet, thereby dividing the transparent glass sheet into a plurality of glass pieces for use in the stacking step, wherein polishing of side surfaces on the long sides of each glass piece may be not performed. In this case, protrusions and depressions remain on the side surfaces of each glass piece of the glass stack as marks that are formed during cutting.
Moreover, a light control panel according to the present invention is a light control panel in which a large number of strip-shaped reflective surfaces are formed with a constant pitch in a direction that is perpendicular to a thickness direction of the light control panel, the light control panel including a glass stack that has a flat plate-like shape and that is constituted by a large number of glass pieces that are directly stacked one on top of another in a direction that is perpendicular to a thickness direction of the glass stack and a fixation portion that integrates the large number of glass pieces of the glass stack, wherein, in each of the glass pieces, one of the principal surfaces of the glass piece that oppose each other in a thickness direction of the glass piece functions as the strip-shaped reflective surface.
Moreover, the fixation portion of this light control panel may have an adhesive layer that is in contact with one side of the glass stack and that is composed of a cured transparent adhesive, and a transparent cover plate that is adhesively bonded to a side of the adhesive layer, the side being opposite to the glass stack, in such a manner as to cover the one side of the glass stack.
Moreover, an optical imaging device according to the present invention includes two of the above-described light control panels, wherein the two light control panels are bonded to each other via a second adhesive layer such that their strip-shaped reflective surfaces are substantially orthogonal to each other, and the glass stacks of the light control panels face each other.
Moreover, an aerial image forming system according to the present invention includes the above-described optical imaging device and a reproducing device that is disposed behind the optical imaging device and that displays an image in a display based on electronic data, wherein an aerial image is formed by forming the image in the display in free space (in the air) in front of the optical imaging device.
According to the present invention, a flat plate-shaped glass stack is produced by directly stacking a large number of elongated flat plate-shaped glass pieces one on top of another. Unlike the conventional method, cutting out light control panels having a constant thickness from a stack of a large number of transparent sheets (a block in which mirror sheets are interposed between the transparent sheets) is not performed, but instead, the large number of glass pieces that are stacked one on top of another constitute a glass stack, which is one element of a light control panel. Moreover, unlike the conventional method, the large number of glass pieces are directly stacked one on top of another in the stacking step. No adhesive is provided between adjacent glass pieces in the stacking step. Accordingly, an adhesive in gaps between adjacent glass pieces 15, where a large amount of adhesive has conventionally been used, can be reduced, so that the manufacturing cost of the light control panel can be reduced.
It should be noted that a transparent glass piece with no metal reflective film (mirror) on either side can be used as each glass piece. Here, when the large number of glass pieces are directly stacked one on top of another, minute gaps are formed between adjacent glass pieces. For this reason, in the glass stack, light that is obliquely incident from side surfaces of the glass pieces is totally reflected by principal surfaces (surfaces opposing each other in the thickness direction of the glass pieces) of the glass pieces due to the difference between the refractive index of the glass pieces and the refractive index of air in the minute gaps. Even though no metal reflective film is provided on either side of each glass piece, light for forming an aerial image is properly reflected, and the light control panel functions properly. In this case, a large number of metal reflective layers (mirror sheets), which have conventionally been used, are no longer necessary, so that the manufacturing cost of the light control panel can be reduced even more.
Moreover, according to the present invention, unlike the conventional method, a block from which a plurality of light control panels are cut out is not produced, but instead, a glass stack used for a single light control panel is produced from a large number of glass pieces. Compared with the block, the glass stack is lightweight. Therefore, although it has conventionally been difficult to increase the size of a light control panel under constraints of the weight of the block, the constraints of the weight are alleviated according to the present invention, so that the size of a light control panel can be increased.
Moreover, the large number of glass pieces of the glass stack can be integrated by fixing the glass pieces to a single cover plate with an adhesive layer. In this case, the adhesive layer comes into intimate contact with a side surface of each glass piece and the cover plate. Therefore, even though polishing of the side surface (cut surface) of each glass piece is not performed, a side surface portion of each glass piece of the glass stack can be made transparent. Accordingly, polishing of the side surface of each glass piece can be omitted, so that the manufacturing cost of the light control panel can be reduced even more.
Hereinafter, an embodiment of the present invention will be described in detail with reference to
A light control panel 10 is an optical element in which a large number of strip-shaped reflective surfaces are formed with a constant pitch in a direction that is perpendicular to a thickness direction of the light control panel 10. As shown in
The glass stack 11 is obtained by stacking the large number of (e.g., 100 or more) elongated rectangular flat plate-shaped glass pieces 15 (glass bars) one on top of another. The large number of glass pieces 15 have the same dimensions (the same shape and the same size) and are stacked one on top of another without displacement. The glass stack 11 has a rectangular flat plate-like shape (is flat rectangular parallelepiped-shaped) (see
For example, the glass pieces 15 each have dimensions of 1.5 mm wide on the short side (width), 300 mm long on the long side (length), and 0.5 mm thick. In the glass stack 11, 600 glass pieces 15, for example, are stacked one on top of another. The glass stack 11 has a rectangular parallelepiped shape having an about 300 mm×about 300 mm square shape in plan view and a thickness of 1.5 mm. It should be noted that the dimensions of the glass pieces 15 and the glass stack 11 are not limited to the dimensions described in this paragraph.
The adhesive layer 12 is a thin transparent layer that is in contact with one of the principal surfaces of the glass stack 11. The adhesive layer 12 is composed of an adhesive that has been applied to that principal surface of the glass stack 11 and cured. The adhesive layer 12 fixes the glass pieces 15 of the glass stack 11 to the cover plate 13. The adhesive layer 12 substantially entirely covers that principal surface of the glass stack 11.
The cover plate 13 is a thin sheet of transparent glass having a rectangular flat plate-like shape. For example, the cover plate 13 has a thickness that is approximately equal to the thickness of the glass pieces 15 and that is smaller than that of the glass stack 11. In plan view, the cover plate 13 has, for example, substantially the same size as the principal surface of the glass stack 11, and is adhesively bonded to a side of the adhesive layer 12 that is opposite to the glass stack 11 in such a manner as to entirely cover the principal surface. The sides of the cover plate 13 are substantially parallel to the respectively corresponding neighboring sides of the principal surface of the glass stack 11.
Here, the side surfaces of each glass piece 15 that constitute the principal surfaces (front and rear surfaces) of the glass stack 11 are cut surfaces that have been cut in a cutting step, which will be described later, and are not polished. Protrusions and depressions, which are marks that are formed during cutting, remain on the side surfaces of each glass piece 15. However, a side surface portion of each glass piece 15 in the glass stack 11 can be made transparent by the adhesive layer 12 coming into intimate contact with that side surface of the glass piece 15 and the cover plate 13. According to the present embodiment, polishing of one of the side surfaces of each glass piece 15 can be omitted.
Moreover, when the large number of glass pieces 15 are directly stacked one on top of another, minute gaps are formed between the glass pieces 15 that are adjacent to each other. Thus, in the glass stack 11, light that is obliquely incident from the side surfaces of the glass pieces 15 is totally reflected by principal surfaces (surfaces opposing each other in a thickness direction of the glass pieces) of the glass pieces 15 due to the difference between the refractive index of the glass pieces 15 and the refractive index of air in the minute gaps. That is to say, in the light control panel 10, light that is obliquely incident from the principal surface of the glass stack 11 is totally reflected by a principal surface of each glass piece 15 that functions as the strip-shaped reflective surface.
As shown in
In the optical imaging device 20, glass stacks 11a and 11b are bonded to each other with an adhesive layer 16 (second adhesive layer) such that the strip-shaped reflective surfaces of the two light control panels 10a and 10b are substantially orthogonal to each other, and the glass stacks 11a and 11b face each other. In the light control panels 10a and 10b, the adhesive layer 16 is in intimate contact with one of the side surfaces of each of the glass pieces 15a and 15b of the glass stacks 11a and 11b. Thus, unpolished side surface portions can be made transparent. According to the present embodiment, polishing of the other side surface of each glass piece 15 can also be omitted. It should be noted that, in plan view, the angle that is formed by the strip-shaped reflective surfaces of the light control panel 10a with the strip-shaped reflective surfaces of the light control panel 10b can be 90°±2°, for example.
Next, an aerial image forming system 25 will be described. As shown in
Light rays A and B from a point X of the display 27 are successively regularly reflected at points P of the strip-shaped reflective surfaces of the light control panel 10a and points Q of the strip-shaped reflective surfaces of the light control panel 10b. Then, the light rays A and B regularly reflected at the points Q converge at a point X′ above the optical imaging device 20. Moreover, light rays C and D from a point Y of the display 27 are successively regularly reflected at points R of the strip-shaped reflective surfaces of the light control panel 10a and points S of the strip-shaped reflective surfaces of the light control panel 10b. Then, the light rays C and D regularly reflected at the points S converge at a point Y′ above the optical imaging device 20. As a result, an image in the display 27 can be formed in free space in front of the optical imaging device 20, and an aerial image can thus be formed.
It should be noted that the “aerial image” can also be called a “floating image”. The aerial image forming system 25 can form a two-dimensional aerial image or can form a three-dimensional aerial image (stereoscopic image) in accordance with the image in the display 27. The aerial image forming system 25 can form an aerial touch screen, for example, as the two-dimensional aerial image or can form a character, for example, as the three-dimensional aerial image.
A method for manufacturing the light control panel 10 includes a cutting step, a washing step, a stacking step, and an integrating step. The method for manufacturing the light control panel 10 will now be described using
In the cutting step, first, as a material plate, a transparent glass sheet 30 (e.g., soda-lime glass substrate) having a rectangular flat plate-like shape is placed on a flat mount surface. A cutter 40 (e.g., laser cutter) is located above the transparent glass sheet 30. A cutter capable of fully cutting the transparent glass sheet 30 at a high speed (e.g., 1 m/second for a straight line portion) is used as the cutter 40. In the following description, as shown in
In the cutting step, in a state in which the transparent glass sheet 30 is fixed on the mount surface, as shown in
It should be noted that after cutting in the first direction, the transparent glass sheet 30, instead of the cutter 40, may also be moved in the second direction (left direction in
Subsequently, the washing step is performed in which glass powder that is generated by cutting is washed away. In the washing step, the surface of each glass piece 15 obtained in the cutting step is washed to remove the glass powder adhering to the glass piece 15. After washing, the glass pieces 15 are heat-dried.
Subsequently, the stacking step of producing a glass stack 11 by directly stacking a large number of elongated flat plate-shaped glass pieces 15 one on top of another is performed. In the stacking step, as shown in
For example, a mold member 41 having at least two wall surfaces 41a and 41b that are orthogonal to each other can be used. In this case, the glass pieces 15 are moved one by one toward the wall surface 41a with end surfaces of the glass pieces 15 being in contact with the wall surface 41b, and in this manner, the glass pieces 15 are stacked one after another. The last glass piece 15 is pressed toward the wall surface 41a using a pressing jig.
Here, with regard to the method for placing the large number of glass pieces 15 upright, a temporary arrangement place with small ridges and troughs can be used. In this case, the large number of glass pieces 15 are placed on the temporary arrangement place in such a manner as to overlap each other, and the large number of glass pieces 15 in a slanting state are pushed in the lateral direction so as to become upright.
Alternatively, a robotic arm can be used. In this case, the robotic arm picks up a glass piece 15 on the mount surface by suction, then rotates the picked-up glass piece 15 by 90°, and places the glass piece 15 upright on a flat surface.
Subsequently, the integrating step of integrating the large number of glass pieces 15 of the glass stack 11 is performed. In the integrating step, first, a step of applying an ultraviolet-curable transparent adhesive (hereinafter referred to as a “UV adhesive”) to substantially the entire upper surface of the glass stack 11 that is placed on a flat surface is performed. Next, a step of stacking the cover plate 13 on the upper surface of the glass stack 11 in such a manner that the applied UV adhesive is sandwiched between the glass stack 11 and the transparent cover plate 13 is performed (see
Then, a step of forming the adhesive layer 12 by curing the adhesive between the glass stack 11 and the cover plate 13 is performed. In this step, as shown in
A light control panel 10 is completed through the above-described steps. It should be noted that in the manufacturing process for the light control panel 10, polishing of the side surfaces of the glass pieces 15 is not performed.
It should be noted that, depending on the flowability of the adhesive that is applied to the principal surface of the glass stack 11, the adhesive prior to being cured may flow into the minute gaps between the glass pieces 15 that are adjacent to each other. For this reason, an adhesive in a gel form or a highly viscous adhesive (adhesive composed of a resin with a high molecular weight) may be used so as not to allow the adhesive to flow into the minute gaps. If the adhesive can be prevented from flowing into the minute gaps, in the glass stack 11, the entire surfaces of the glass pieces 15 that are adjacent to each other directly face each other. However, even if the adhesive enters between adjacent glass pieces 15 on the adhesive layer 12 side of the glass stack 11 with respect to the thickness direction, the light control panel 10 functions properly as long as a certain width of the strip-shaped reflective surfaces is secured. In this case, it is desirable that the entry of the adhesive stops midway on the adhesive layer 12 side so that minute gaps are formed in a range that is half or more of the thickness of the glass stack 11, for example.
Next, a method for manufacturing the optical imaging device 20 will be described. This manufacturing method includes a bonding step of bonding the two light control panels 10a and 10b to each other.
In the bonding step, as shown in
According to the present embodiment, unlike the conventional method, a large number of glass pieces 15 are directly stacked one on top of another in the stacking step. No adhesive is provided between adjacent glass pieces 15 in the stacking step. Instead, the large number of glass pieces 15 are integrated by the adhesive layer 12 and the cover plate 13 that are successively stacked on a principal surface of the glass stack 11. Accordingly, although an adhesive is used on the principal surface of the glass stack 11, an adhesive in gaps between adjacent glass pieces 15, where a large amount of adhesive has conventionally been used, can be reduced, so that the manufacturing cost of the light control panel 10 can be reduced.
Moreover, according to the present embodiment, a transparent glass piece without a metal reflective film (mirror) on either side is used as each glass piece 15. Therefore, a large number of metal reflective layers (mirror sheets or vapor-deposited metal films), which have conventionally been used, are not used, so that the manufacturing cost of the light control panel 10 can be reduced even more.
Moreover, according to the present embodiment, unlike the conventional method, a block from which a plurality of light control panels are cut out is not produced, but instead, a glass stack 11 used for a single light control panel 10 is produced from a large number of glass pieces 15. Compared with the block, the glass stack 11 is lightweight. Therefore, although it has conventionally been difficult to increase the size of a light control panel under constraints of the weight of the block, the constraints of the weight are alleviated according to the present invention, so that the size of the light control panel 10 can be increased.
Moreover, according to the present embodiment, polishing of the side surfaces of each glass piece 15 can be omitted as described above, so that the manufacturing cost of the light control panel 10 can be reduced even more.
According to the foregoing embodiment, the optical imaging device 20 has a rectangular shape in plan view. However, the optical imaging device 20 may have a trapezoidal shape as is the case with an optical imaging device disclosed in WO 2013/145983 or may have other polygonal shapes.
Moreover, according to the foregoing embodiment, a transparent glass piece with no metal reflective film on either side is used as each glass piece 15. However, a glass piece having a metal reflective film on one side may also be used. In this case, prior to the cutting step, a metal reflective film is formed on one side of the transparent glass sheet 30 through vapor deposition of metal or the like, and in the cutting step, the transparent glass sheet 30 on which the metal reflective film is formed is divided into a plurality of glass pieces 15. Then, in the stacking step, a large number of glass pieces 15 are directly stacked one on top of another such that the metal reflective films thereon face the same side. It should be noted that glass pieces 15 each with metal reflective films on both sides may also be used.
Moreover, according to the foregoing embodiment, polishing of the side surfaces of each glass piece 15 is not performed. However, polishing of the side surfaces on the long sides of each glass piece 15 may be performed. In this case, a configuration may also be adopted in which the adhesive layer 12 and the cover plate 13 are not provided, and the large number of glass pieces 15 are integrated using a different means. For example, a fixation portion that integrates the large number of glass pieces 15a of the light control panel 10a may be constituted by the light control panel 10b, to which the light control panel 10a is joined, and the adhesive layer 16. Moreover, the large number of glass pieces 15 may be integrated by bonding a plate to a side surface in which the large number of glass pieces 15 are lined up, of the side surfaces of the glass stack 11 with an adhesive.
Moreover, in the foregoing embodiment, the strip-shaped reflective surfaces may be inclined relative to a plane that is parallel to the thickness direction of the light control panel 10 as in the case of an optical imaging device disclosed in WO 2014/024677. In this case, glass pieces 15 having a parallelogrammic shape when viewed in cross section are stacked one on top of another.
Moreover, in the foregoing embodiment, each light control panel 10 may include a plurality of glass stacks 11 that are stacked one on top of another as in the case of an optical imaging device disclosed in Japanese Patent No. 5646110. The positions of the strip-shaped reflective surfaces of the plurality of glass stacks 11 are shifted against each other in the direction in which the glass pieces 15 are lined up.
Moreover, according to the foregoing embodiment, the stacking step is performed after the cutting step. However, the cutting step may also be performed after the stacking step. Specifically, in a method for manufacturing the light control panel 10 according to a modification, a rectangular parallelepiped-shaped stack 31 (see
The present invention is applicable to a method for manufacturing a light control panel for use in an optical imaging device that forms an image in the air, and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-176322 | Sep 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/076061 | 9/5/2016 | WO | 00 |
