Optical sheet manufacturing method and optical sheet manufacturing apparatus

Abstract

The present invention addresses the problem of providing an optical sheet manufacturing method and manufacturing apparatus, whereby cutting out of an optical sheet having a concentric circular pattern from an optical sheet parent material in which the optical sheet is formed can be performed simply, with high precision, and at low cost. The aforementioned problem is solved by detecting the center of the concentric circular pattern of the optical sheet and determining the cut-out position of the optical sheet in the optical sheet parent material in accordance with the center detection result.

Description

Optical sheet manufacturing method and optical sheet manufacturing device

[0001] The present invention relates to a method for manufacturing an optical sheet, in which an optical sheet having a concentric pattern is cut out from an optical sheet base material, and an optical sheet manufacturing apparatus for carrying out this method for manufacturing an optical sheet.

[0002] In the manufacture of sheet-like optical elements such as optical sheets, i.e., optical films, individual optical sheets are cut out from an optical sheet base material on which multiple optical sheets have been formed. In the following description, the "optical sheet base material" will also be referred to simply as the "base material." In the manufacture of these optical sheets, the optical sheets must be cut out from the base material with high precision. To this end, fiducial marks corresponding to the individual optical sheets are provided on the base material, and the cut-out positions of the optical sheets on the base material are determined by detecting these fiducial marks.

[0003] For example, Patent Document 1 describes a method for manufacturing a polarizing plate by cutting a polarizing plate from a base material, which includes sequentially cutting a long polarizing plate (base material) having non-polarizing portions arranged at predetermined intervals in the longitudinal and width directions from one side to the other in the width direction at a predetermined longitudinal feed pitch, and before cutting the long polarizing plate, the positions of the non-polarizing portions are detected and inspected while the long polarizing plate is stopped, and when cutting the long polarizing plate, the detected positions of the non-polarizing portions are used as a reference for positioning, and then the long polarizing plate is cut to obtain sheet polarizing plates each having one non-polarizing portion. That is, in this manufacturing method, non-polarizing portions are provided as reference marks on a base material on which multiple polarizing plates have been formed, and the cut-out positions of the polarizing plates are determined using the non-polarizing portions.

[0004] Patent No. 6695670

[0005] Known methods of forming fiducial marks include coloring with a writing implement such as a magic marker, coloring by printing, punching, punching with an engraving blade, and perforation using a plotter or water jet. Patent Document 1 also describes forming fiducial marks by depolarizing light through chemical dissolution. Laser ablation is also known as a method of forming fiducial marks based on differences in optical properties.

[0006] That is, in the conventional manufacturing of optical sheets by cutting out from a base material, a fiducial mark forming process is essential, and therefore a fiducial mark forming device is required. Furthermore, in order to precisely cut out the optical sheet, it is necessary to form the fiducial marks on the base material sheet with high positional accuracy, which is time-consuming. Therefore, in the conventional manufacturing method of optical sheets, forming the fiducial marks is expensive. Furthermore, it is necessary to also highly accurately position the optical sheet relative to the fiducial marks, which also requires cost and time.

[0007] In addition, in consideration of product quality, fiducial marks may be provided in areas other than the optical sheet formation area. In this case, the base material requires an area for forming the fiducial marks in addition to an area for forming the optical sheet. As a result, the number of products that can be obtained per unit area of ​​the base material decreases.

[0008] Additionally, in the conventional manufacturing method in which an optical sheet is cut out from a base material, detection of the reference marks on the base material and cutting out the optical sheet from the base material are performed by separate devices.

[0009] That is, to determine the cutout position of the optical sheet in the base material, two or more fiducial marks are usually formed on one optical sheet. Therefore, to detect the position of the fiducial mark with high accuracy, two sensors are required to detect the fiducial mark. Furthermore, to detect the position of the fiducial mark with high accuracy, the positional relationship between the two sensors is also important. Here, the optical sheet is cut out from the base material by, for example, punching using a punching die. This cutting of the optical sheet from the base material involves impact. Therefore, if punching and fiducial mark detection are performed using the same device, there is a possibility that an error will occur in the positional relationship between the two sensors due to the impact.

[0010] In consideration of this point, in the conventional manufacturing method of cutting out an optical sheet from a base material, the detection of the reference mark on the base material and the cutting out of the optical sheet are performed using separate devices. This increases the cost of the device and makes the manufacturing of the optical sheet more time-consuming. Furthermore, using separate devices to detect the reference mark, i.e., to determine the cutout position of the optical sheet on the base material, and to cut out the optical sheet from the base material, can cause errors in the cutout position of the optical sheet.

[0011] That is, the conventional manufacturing method in which individual optical sheets are cut out from a base material on which a plurality of optical sheets have been formed has high initial and running costs, and is also time-consuming to manufacture.

[0012] The object of the present invention is to solve the problems of the prior art, and to provide an optical sheet manufacturing method that can cut out an optical sheet from an optical sheet base material having a concentric circular pattern formed thereon, at low cost, easily, and with high precision, and an optical sheet manufacturing apparatus that performs this optical sheet manufacturing method.

[0013] In order to achieve the above-mentioned objects, the present invention has the following configurations. [1] A method for manufacturing an optical sheet, which, when cutting out an optical sheet from an optical sheet base material on which an optical sheet having a concentric circular pattern has been formed, detects the center of the concentric circular pattern of the optical sheet, and determines the cutout position of the optical sheet on the optical sheet base material based on the detection result of the center of the concentric circular pattern. [2] A method for manufacturing an optical sheet according to [1], in which the center of the concentric circular pattern of the optical sheet is detected using light reflected from the optical sheet base material. [3] A method for manufacturing an optical sheet according to [1] or [2], in which the detection of the center of the concentric circular pattern of the optical sheet is performed using an image obtained by irradiating the optical sheet with linearly polarized light. [4] The method for manufacturing an optical sheet according to any one of [1] to [3], wherein the optical sheet is cut out using a die having a through hole in its center, the center of the concentric pattern of the optical sheet is detected through the through hole of the die from the side opposite to the cutting edge of the die, and the position for cutting out the optical sheet on the optical sheet base material using the die is determined by aligning the detected center of the concentric pattern of the optical sheet with the center of the die. [5] The method for manufacturing an optical sheet according to [4], wherein the through hole has a tapered shape that gradually reduces in diameter toward the optical sheet base material. [6] The method for manufacturing an optical sheet according to [4] or [5], wherein the center of the concentric pattern of the optical sheet is detected by image analysis of an image captured by an imaging device. [7] The method for manufacturing an optical sheet according to [6], wherein the optical axis of the imaging device and the center of the through hole are aligned. [8] The method for manufacturing an optical sheet according to any one of [1] to [7], wherein the concentric pattern of the optical sheet is a concentric liquid crystal orientation pattern. [9] A method for manufacturing an optical sheet according to any one of [1] to [8], in which after detecting the center of the concentric pattern of the optical sheet, the optical sheet base material is aligned on the spot with a cutting means for cutting out the optical sheet from the optical sheet base material, and then the optical sheet is cut out from the optical sheet base material by the cutting means.

[10] An optical sheet manufacturing apparatus that cuts out an optical sheet from an optical sheet base material on which an optical sheet having a concentric pattern has been formed, the optical sheet manufacturing apparatus comprising: a table on which the optical sheet base material is placed; a cutting die having a through hole in the center that cuts out the optical sheet from the optical sheet base material; an imaging device that images the optical sheet base material placed on the table through the through hole of the cutting die; an analysis means that detects the center of the concentric pattern of the optical sheet by analyzing the image taken by the imaging device; and an adjustment means that adjusts the positional relationship between the table and the cutting die so that the center of the cutting die and the center of the concentric pattern of the optical sheet coincide with each other, depending on the detection result of the center of the concentric pattern of the optical sheet by the analysis means.

[0014] According to the present invention, cutting out an optical sheet having a concentric pattern from an optical sheet base material can be performed at low cost, simply, and with high accuracy.

[0015] Fig. 1 is a conceptual diagram of an example of an apparatus for manufacturing an optical sheet of the present invention, which performs an example of a method for manufacturing an optical sheet of the present invention. Fig. 2 is a schematic cross-sectional view of an example of a cutting die used in the present invention. Fig. 3 is a conceptual diagram of an example of the configuration of an imaging device used in the present invention. Fig. 4 is a conceptual diagram of an example of a liquid crystal lens. Fig. 5 is a diagram obtained by image processing a photograph of a liquid crystal lens.

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical sheet manufacturing method and optical sheet manufacturing apparatus of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

[0017] The figures described below are illustrative for explaining the present invention, and the present invention is not limited to the figures shown below. Furthermore, all of the figures shown below are conceptual diagrams for explaining the present invention, and the size, shape, and positional relationship of each component may differ from the actual ones. Note that in the following, "to" indicating a numerical range includes the values ​​written on both sides. For example, when ε is between numerical values ​​α and β, the range of ε includes numerical values ​​α and β, and expressed in mathematical notation, α≦ε≦β.

[0018] FIG. 1 conceptually illustrates an example of an optical sheet manufacturing apparatus of the present invention, which implements an example of an optical sheet manufacturing method of the present invention. The optical sheet manufacturing apparatus of the present invention cuts out individual optical sheets from an optical sheet base material W on which an optical sheet having a concentric circular pattern is formed. Note that the optical sheet base material W may have one or more optical sheets formed thereon. In the following description, the "optical sheet base material W" may also be simply referred to as the "base material W." The optical sheet manufacturing apparatus 10 of the illustrated example includes a base 12, a cutting die support table 14, a cutting die 16, a table support table 24, a mounting table 26, a movement mechanism 28, an imaging device 30, and an image analysis device 32. In the following description, the "optical sheet manufacturing apparatus" may also be simply referred to as the "manufacturing apparatus."

[0019] The base 12 supports the die support base 14 and the table support base 24. The die support base 14 is supported by four posts 18. A lifting mechanism for raising and lowering the die support base 14, i.e., the posts 18, is built into the base 12.

[0020] The die support base 14 is a rectangular plate that supports the die 16. The die 16 cuts out the optical sheet from the base material W by punching it out, and a known die can be used. In the illustrated example, the die 16 punches out the optical sheet into a rectangle from the base material W, as an example. In the present invention, a rectangle also includes a square. Note that in the present invention, the shape of the optical sheet cut out from the base material W is not limited to a rectangle. In other words, in the present invention, there is no limitation on the shape of the optical sheet cut out from the base material W, and the optical sheet can be punched out into a circle, for example, from the base material W.

[0021] FIG. 2 conceptually illustrates a cross-sectional view of the die 16. As shown in FIG. 2, the die 16 has a body 40 and a cutting edge 42 for punching an optical sheet from a base material W. In the illustrated example, the die 16 is a so-called engraving blade, fabricated by integrally carving out the body 40 and the cutting edge 42. The die is not limited to this, and various known die types can be used in the present invention, such as a die in which a cutting edge is embedded and fixed in a plywood body, or a die in which a cutting edge is embedded and fixed in a metal body such as stainless steel. However, considering factors such as suppression of dimensional changes due to moisture absorption, durability, dimensional accuracy, positional accuracy of the cutting edge and through holes, and strength against shear stress applied to the die blade, a die in which a cutting edge is embedded and fixed in a metal body is preferred. Among these, an engraving blade such as the illustrated example is more preferred.

[0022] Mounting holes 40a are provided in the main body 40. The punching die 16 is attached to a predetermined position on the punching die support base 14 using these mounting holes 40a, for example, with bolts. Note that the method of attaching the punching die 16 to the punching die support base 14 is not limited to this method, and various known attachment methods can be used.

[0023] In a preferred embodiment, the cutting die 16 has a through hole 46 at the center of the cutting edge 42. The through hole 46 is a cylindrical through hole having a large diameter portion 46a and a small diameter portion 46b on the cutting edge 42 side. The large diameter portion 46a and the small diameter portion 46b are cylindrical and have the same center. In a preferred embodiment, the small diameter portion 46b has a tapered shape that gradually reduces in diameter toward the cutting edge 42 side. In a further preferred embodiment, the cutting die 16 has the center of the cutting edge 42 and the center of the through hole 46 aligned. Note that the center of the cutting edge 42 is usually the center of the cutting die 16. If the center of the cutting edge 42 and the center of the cutting die 16 do not line up, the through hole 46 is formed at the center of the cutting edge 42.

[0024] Furthermore, the die support base 14 also has a cylindrical through-hole 14a that communicates with the large diameter portion 46a of the through-hole 46 of the die 16 and has the same diameter as the large diameter portion 46a.

[0025] As will be described later, the imaging device 30 captures an image of the optical sheet having a concentric pattern formed on the base material W through the through-hole 46. Furthermore, the manufacturing apparatus 10 detects the center of the concentric pattern of the optical sheet by analyzing the captured image. In the following description, the "concentric pattern" is also referred to simply as "concentric circle." Here, as shown in the example, by tapering the small-diameter portion 46b of the through-hole 46 so that the diameter gradually decreases toward the cutting edge 42, the imaging range of the imaging device 30, i.e., the observation range for detecting the center of the concentric circle, can be narrowed. Furthermore, narrowing the imaging range makes it possible to detect the positional relationship between the center of the concentric circle of the optical sheet and the through-hole 46 (small-diameter portion 46b), i.e., the center of the cutting edge 42, closer to the optical sheet. As a result, the center of the concentric circle of the optical sheet can be detected with higher accuracy.

[0026] There is no restriction on the degree of tapering of the small diameter portion 46b, i.e., the through hole 46, and it may be set appropriately depending on the area punched by the cutting edge 42, the size of the through hole 46, the spacing between the light and dark lines at the center of the concentric circles of the optical sheet, etc.

[0027] Here, in order to detect the centers of the concentric circles of the optical sheet, the opening of the small diameter portion 46b on the cutting edge 42 side needs to have a certain area. On the other hand, if the area of ​​the opening of the small diameter portion 46b on the cutting edge 42 side is too large, the strength of the punching die 16 will decrease. Taking this into consideration, the area of ​​the opening of the small diameter portion 46b of the through hole 46 on the cutting edge 42 side is preferably 0.05 to 10% of the punching area by the cutting edge 42, and more preferably 0.5 to 2.5%.

[0028] As described above, the die support base 14 is a rectangular plate that supports the die 16. The die support base 14 is supported on the base 12 by four posts 18 provided near the corners. As described above, the base 12 has a built-in mechanism for lifting and lowering the posts 18. That is, in the manufacturing apparatus 10, by lowering the posts 18, the die support base 14, i.e., the die 16, is lowered and the cutting edge 42 cuts out the optical sheet from the base material W. In the present invention, there are no limitations on the lifting mechanism for the posts 18, and various known mechanisms can be used, such as a hydraulic lifting mechanism, a mechanical lifting mechanism, and a lifting mechanism driven by a motor and hydraulic pressure in combination with a rod-type sliding guide, a rail-type sliding guide, and a mechanical toggle mechanism.

[0029] A table support 24 is fixed to the upper surface of the base 12, and a mounting table 26 is supported on the table support 24. A movement mechanism 28 is also provided on the table support 24. The table support 24 is a base that supports the mounting table 26 so that it can be moved freely.

[0030] The loading table 26 is used to place the base material W from which the optical sheet is to be cut out, and is made of a metal plate such as stainless steel. The loading table 26 is movably supported by the table support base 24 at a position corresponding to the through-hole 46 of the cutting die 16.

[0031] In a preferred embodiment, the loading table 26 has a means for fixing the base material W to prevent unnecessary movement and to suppress deformation such as curling and expansion and contraction of the base material W. There are no limitations on the method for fixing the base material W to the loading table 26, and known methods such as a method using suction (adsorption), a method using magnetic force, and a method using a jig can be used. Among these, fixing the base material W by suction is a preferred example.

[0032] A movement mechanism 28 for adjusting the position of the loading table 26 is provided on the table support 24. The movement mechanism 28 adjusts the position of the loading table 26 by moving the loading table 26 in orthogonal x and y directions. As will be described in detail later, in the manufacturing apparatus 10, the center of the concentric circles of the optical sheet formed on the base material W is detected from an image of the base material W captured by an imaging device 30, which will be described later. Thereafter, the position of the loading table 26 is adjusted by the movement mechanism 28 to align the center of the concentric circles of the optical sheet with the center of the cutting die 16, i.e., the center of the cutting edge 42, and the optical sheet is then cut out from the base material W by the cutting die 16.

[0033] There are no limitations on the moving mechanism 28, and various known mechanisms used in x-y stages, etc., such as a ball screw feed mechanism combined with a rod-type sliding guide and / or a rail-type sliding guide, can be used. Furthermore, the movement of the mounting table 26 by the moving mechanism 28 may be performed manually or automatically. In the illustrated example of the manufacturing apparatus 10, as a preferred embodiment, the moving mechanism 28 automatically moves the mounting table 26 in response to instructions from the image analysis device 32, thereby aligning the center of the concentric circles of the optical sheet with the center of the cutting die 16, i.e., the cutting edge 42.

[0034] The imaging device 30 is provided above the die support base 14 in the drawing. The imaging device 30 is supported by an imaging device support section 48. The imaging device support section 48 is preferably supported independently of the base 12 without being connected to the base 12. By supporting the imaging device support section 48 independently of the base 12, it is possible to suppress mechanical displacement of the fixed imaging device 30 and adverse effects on electronic equipment such as CCD sensors, which are caused by the propagation of impact during cutting.

[0035] The imaging device 30 is an imaging device using a known imaging element such as a CCD sensor. In the manufacturing apparatus 10, the imaging device 30 images the base material W supported on the mounting table 26 from the side opposite the cutting edge 42 through the through hole 14a of the die support base 14 and the through hole 46 of the die 16. In a preferred embodiment, the optical axis of the imaging device 30 is aligned with the center of the die 16, i.e., the cutting edge 42. As described above, the center of the through hole 46 of the die 16 is aligned with the center of the die 16, i.e., the cutting edge 42. In other words, in a more preferred embodiment of the manufacturing apparatus 10, the optical axis of the center of the die 16, the center of the through hole 46 of the die 16, and the center of the imaging device 30 are aligned. Therefore, in the alignment process described below, the optical axis of the image captured by the imaging device 30 is aligned with the center of the detected concentric circles of the optical sheet, thereby allowing the center of the die 16 to be aligned with the center of the concentric circles of the optical sheet.

[0036] It should be noted that the present invention is not limited to imaging the optical sheet through the through-hole 46 of the die 16. For example, an imaging device may be provided on the underside of the die support base 14, and the optical sheet may be imaged using this imaging device. However, in the present invention, as shown in the example, it is preferable to provide a through-hole 46 at the center of the die 16 and image the optical sheet through this through-hole 46. This allows the optical sheet to be imaged from directly above, i.e., from the normal direction, with the centers of the concentric circles approximately aligned with the optical axis, enabling more accurate detection of the centers of the concentric circles through image analysis. The normal direction is a direction perpendicular to the surface direction of the sheet-like object (plate-like object, layer, film).

[0037] In the present invention, there are no limitations on the light used to detect the centers of the concentric circles of the optical sheet formed on the base material W, and various types of light can be used. Furthermore, the light used to detect the centers of the concentric circles of the optical sheet formed on the base material W may be polarized or unpolarized. Here, in the present invention, it is preferable to detect the centers of the concentric circles of the optical sheet formed on the base material W by irradiating linearly polarized light. In the manufacturing apparatus 10, the imaging device 30 preferably irradiates the base material W with linearly polarized light to image the base material W. That is, in a preferred embodiment, the manufacturing apparatus 10 images the base material W using linearly polarized light as imaging light. This makes it possible to more clearly display the concentric circles of the optical sheet, specifically the concentric circles of the optical sheet formed by light and dark lines, in the image of the base material W captured by the imaging device 30. As a result, the accuracy of detecting the centers of the concentric circles of the optical sheet can be improved.

[0038] FIG. 3 conceptually illustrates the configuration of the imaging device 30. As shown in FIG. 3, the imaging device 30 includes an imaging element 50 such as a CCD sensor, a light source 52, a half mirror 54, and a linear polarizer 56. The light source 52 emits white light. The light emitted by the light source 52 is reflected by the half mirror 54 toward the base material W, then passes through the linear polarizer 56, and the linearly polarized light is irradiated onto the base material W. The imaging element 50 uses the linearly polarized light irradiated onto the base material W as imaging light and images the base material W via the half mirror 54. That is, in the illustrated example, the imaging element 50 images the light reflected by the base material W, which is a preferred embodiment that does not require moving the base material W or removing the mounting table 26. However, the present invention is not limited to this, and light transmitted through the base material W may also be imaged.

[0039] There is no limitation on the polarization direction of the linearly polarized light irradiated onto the base material W. Therefore, the linearly polarized light irradiated onto the base material W may be either S-polarized or P-polarized.

[0040] The image analysis device 32 detects the center of one of the concentric circles of the optical sheets having a concentric pattern formed on the base material W from the image of the base material W captured by the imaging device 30. Furthermore, the image analysis device 32 issues a command to the movement mechanism 28 to move the mounting table 26 based on the detection result of the center of the concentric circle. Such an image analysis device 32 may be configured using a general-purpose computer and general-purpose software. Furthermore, the image analysis device 32 may have a display for displaying the image captured by the imaging device 30, etc., as necessary. The image analysis device 32 will be described in detail later.

[0041] As described above, the present invention involves cutting out an optical sheet having a concentric pattern from one or more formed base materials W (optical sheet base materials W). An example of an optical sheet having a concentric pattern (optical pattern) is a liquid crystal lens (liquid crystal diffractive lens).

[0042] An example of a liquid crystal lens is conceptually shown in Fig. 4. The liquid crystal lens 60 shown in Fig. 4 has, for example, a substrate, an alignment film formed on one surface of the substrate, and a liquid crystal layer (optically anisotropic layer) formed on the surface of the alignment film. Fig. 4 shows the surface of the liquid crystal layer.

[0043] The liquid crystal lens 60 (liquid crystal layer) has a liquid crystal orientation pattern in which the orientation of the optical axis derived from the liquid crystal compound 62 changes while continuously rotating in one direction, radially from the inside to the outside. That is, as shown in FIG. 4 , the liquid crystal orientation pattern of the liquid crystal lens 60 is a concentric liquid crystal orientation pattern in which the orientation of the optical axis derived from the liquid crystal compound 62 changes while continuously rotating in one direction, concentrically from the inside to the outside. In other words, the concentric pattern in the liquid crystal lens 60 is a concentric liquid crystal orientation pattern in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating along one in-plane direction, concentrically from the inside to the outside. Note that the liquid crystal compound 62 is fixed in the liquid crystal lens 60.

[0044] The optical axis derived from the liquid crystal compound 62 is the axis along which the refractive index of the liquid crystal compound 62 is highest, and is the so-called slow axis. In Fig. 4, a rod-shaped liquid crystal compound is exemplified as the liquid crystal compound 62. Therefore, the direction of the optical axis derived from the liquid crystal compound 62 is along the long axis direction of the rod shape of the liquid crystal compound 62.

[0045] In the liquid crystal lens 60, the direction of the optical axis of the liquid crystal compound 62 changes while continuously rotating in multiple directions from the center of the liquid crystal lens 60 outward, such as the direction indicated by arrow A1, the direction indicated by arrow A2, the direction indicated by arrow A3, the direction indicated by arrow A4, etc. Therefore, in the liquid crystal lens 60, the rotation direction of the optical axis of the liquid crystal compound 62 is the same in all directions (one direction). In the illustrated example, the rotation direction of the optical axis of the liquid crystal compound 62 is counterclockwise in all directions indicated by arrow A1, the direction indicated by arrow A2, the direction indicated by arrow A3, and the direction indicated by arrow A4. In other words, if arrows A1 and A4 are considered to be a single line, the rotation direction of the optical axis of the liquid crystal compound 62 is reversed at the center of the liquid crystal lens 60 on this line. As an example, the line formed by arrows A1 and A4 is assumed to be directed rightward in the figure (the direction indicated by arrow A1). In this case, the optical axis of the liquid crystal compound 62 initially rotates clockwise from the outside of the liquid crystal lens 60 toward the center, reverses its direction of rotation at the center of the liquid crystal lens 60, and then rotates counterclockwise from the center of the liquid crystal lens 60 toward the outside.

[0046] In this liquid crystal orientation pattern, one period Λ is the length over which the optical axis direction of the liquid crystal compound 62 rotates 180° in one direction in which the direction of the optical axis of the liquid crystal compound 62 changes while continuously rotating. In the liquid crystal lens 60, the shorter the period Λ, the greater the refractive index (diffraction angle) of the lens. Furthermore, the length of one period Λ of the liquid crystal lens 60 becomes shorter from the inside to the outside. This allows the liquid crystal lens 60 to focus incident light.

[0047] Such a liquid crystal lens 60 exhibits refraction (diffraction) mainly for circularly polarized light, and the direction of refraction differs depending on the direction of rotation of the optical axis of the liquid crystal compound 62, which is oriented in one direction, and the rotation direction of the circularly polarized light. That is, the liquid crystal lens 60 focuses right-handed circularly polarized light and diffuses left-handed circularly polarized light. Alternatively, the liquid crystal lens 60 diffuses right-handed circularly polarized light and focuses left-handed circularly polarized light.

[0048] 4, in the concentric liquid crystal orientation pattern of the liquid crystal lens 60, the liquid crystal compounds 62 (optical axes) present on the same circle in each of the concentric circles have the same orientation direction. When the liquid crystal lens 60 is imaged using an imaging device using a CCD sensor or the like, concentric bright and dark lines are observed according to the orientation direction of the liquid crystal compounds 62. Preferably, the concentric bright and dark lines become clear when the image is captured using linearly polarized light, as described above.

[0049] Fig. 5 shows an example of an image captured of the liquid crystal lens 60. Note that this image was captured in accordance with the imaging device 30 shown in Fig. 3 using an STC-MBS500U3V (manufactured by Omron Sentec Co., Ltd.) as the imaging element, a VS-TCH1-110CO (manufactured by VS Technology Co., Ltd.) as the telecentric lens, a PL-27-NL (manufactured by CCS Corporation) as the linear polarizer, an OPS-S20W (manufactured by Optex FA Co., Ltd.) as the light source, and an SV-G533-270 (manufactured by VS Technology Co., Ltd.) as the bandpass filter.

[0050] In the present invention, the concentric optical sheet is not limited to a liquid crystal lens, and the present invention can be used to manufacture various known optical sheets (sheet-like optical elements) such as Fresnel lenses, in addition to liquid crystal lenses.

[0051] Hereinafter, the operation of the manufacturing apparatus 10 will be described to provide a more detailed explanation of the optical sheet manufacturing method and optical sheet manufacturing apparatus of the present invention.

[0052] First, the base material W on which the optical sheets are formed (optical sheet base material W) is placed on the placement table 26 so that the center of the concentric pattern of one optical sheet coincides with the center of the cutting die 16 (cutting edge 42). Preferably, the base material W is then fixed to the placement table 26 by means of suction or the like.

[0053] Next, in the imaging device 30, the light source 52 is turned on to irradiate the optical sheet with linearly polarized light. Furthermore, the imaging device 30 captures an image of the optical sheet. As described above, the image is captured through the through hole 14a of the die support base 14 and the through hole 46 provided at the center of the die 16. As a result, an image of concentric light and dark lines, as shown in FIG. 5 , corresponding to the concentric pattern of the optical sheet is captured, as described above.

[0054] The image (image data) of the concentric circular pattern of the optical sheet captured by the imaging device 30 is sent to the image analyzer 32. The image analyzer 32 performs image analysis on the image of the concentric circular pattern of the optical sheet provided to detect the center of the concentric circle of the optical sheet. As described above, the center of the concentric circle refers to the center of the concentric circular pattern of the optical sheet. The detection of the center of the concentric circle from the captured image of the concentric circular pattern by the image analyzer 32 can be performed using general-purpose image processing software. For example, image processing software having a pattern matching function and performing image analysis to recognize circles and determine their centers can be used. Examples of such image processing software include the CV-X series and XG-X series manufactured by KEYENCE Corporation, with the XG-X series being particularly preferred.

[0055] The image analysis device 32 then calculates the direction and amount of movement of the mounting table 26 to align the center of the concentric circles of the optical sheet with the center of the cutting die 16 (cutting edge 42). As described above, in the manufacturing apparatus 10, the cutting die 16 has a through hole 46 at its center, and the imaging device 30 captures an image of the concentric pattern of the optical sheet through this through hole 46. The positional relationship between the center of the cutting die 16 and the center of the through hole 46 is naturally known, and the image analysis device 32 recognizes this information. Using this positional relationship between the center of the cutting die 16 and the center of the through hole 46, the image analysis device 32 calculates the direction and amount of movement (movement distance) of the mounting table 26 to align the center of the cutting die 16 with the center of the concentric circles of the optical sheet.

[0056] In the illustrated manufacturing apparatus 10, the center of the die 16 and the center of the through-hole 46 preferably coincide. Therefore, the image analysis device 32 need only calculate the direction and amount of movement of the mounting table 26 so that the center of the through-hole 46 coincides with the center of the detected concentric circle of the optical sheet. Therefore, this configuration allows for simpler and more accurate calculation of the direction and amount of movement of the mounting table 26 to coincide with the center of the die 16 and the center of the concentric circle of the optical sheet. Additionally, in the illustrated manufacturing apparatus 10, the optical axis of the imaging device 30 preferably coincides with the center of the through-hole 46. Therefore, the image analysis device 32 need only calculate the direction and amount of movement of the mounting table 26 so that the optical axis of the imaging device, i.e., usually the center of the image, coincides with the center of the detected concentric circle of the optical sheet. Therefore, with this configuration, the direction and amount of movement of the loading table 26 to align the center of the cutting die 16 with the center of the concentric circle of the optical sheet can be calculated more easily and with higher accuracy.

[0057] After calculating the direction and amount of movement of the mounting table 26 that will align the center of the concentric pattern of the optical sheet with the center of the cutting die 16, i.e., the cutting edge 42, the image analyzer 32 instructs the movement mechanism 28 to move the mounting table 26 accordingly. The movement mechanism 28 then moves the mounting table 26 in the X direction and / or Y direction in response to this calculation, so that the center of the concentric pattern of the optical sheet will align with the center of the cutting die 16. This determines the position at which the cutting die 16 will cut out the optical sheet in the base material W.

[0058] As described above, in the present invention, the alignment of the center of the concentric pattern of the optical sheet with the center of the cutting die 16, i.e., the cutting edge 42, is not limited to being performed automatically by the moving mechanism 28, but may also be performed manually. For example, once the image analysis device 32 detects the centers of the concentric circles of the optical sheet, the image (video) captured by the imaging device 30 and the detected positions of the centers of the concentric circles of the optical sheet are displayed on a display provided in the image analysis device 32. Preferably, the center position of the cutting die 16 is also displayed on the display. Next, while observing this image, the operator manually operates the moving mechanism 28 to move the mounting table 26, thereby aligning the centers of the concentric circles of the optical sheet with the center of the cutting die 16.

[0059] When the center of the concentric circles of the optical sheet and the center of the cutting die 16 are aligned, the lifting mechanism built into the base 12 is driven to lower the cutting die support base 14, i.e., the cutting die 16, and cut the optical sheet out of the base material W.

[0060] As is clear from the above description, the present invention uses the centers of the concentric circles of the optical sheet as fiducial marks when cutting out individual optical sheets from a base material W on which an optical sheet having a concentric pattern has been formed. Therefore, the present invention eliminates the fiducial mark forming process and forming device that require high precision, which were essential in conventional manufacturing methods. Moreover, because fiducial marks are not required, space for the fiducial marks on the base material W is also not required. Therefore, the present invention allows for a larger number of optical sheets to be formed per unit area of ​​the base material W, and therefore allows for a larger number of optical sheets, i.e., products, to be obtained from a single sheet of base material W.

[0061] Furthermore, as described above, conventional optical sheet manufacturing methods using fiducial marks require two or more fiducial marks for each optical sheet. Therefore, in conventional manufacturing methods, the fiducial marks are detected using sensors corresponding to the number of fiducial marks formed on each optical sheet. As a result, conventional manufacturing methods require separate devices to detect the fiducial marks and cut out the optical sheet from the base material, which is time-consuming and can cause errors. In contrast, the present invention detects the centers of the concentric circles of the optical sheet, eliminating the need to detect fiducial marks using multiple detection devices. Therefore, according to the present invention, the detection of the concentric centers of the optical sheet and the cutting out of the optical sheet from the base material can be performed continuously using a single device, improving workability and improving the accuracy of cutting out the optical sheet.

[0062] Furthermore, in the illustrated manufacturing apparatus 10, as a preferred embodiment, a through hole 46 is provided in the center of the die 16, and the imaging device 30 captures an image of the optical sheet through the through hole 46 from the side opposite the cutting edge 42. Preferably, the center of the die 16 and the center of the through hole are aligned, and more preferably, the optical axis of the imaging device 30 and the center of the through hole 46 are aligned. That is, the illustrated manufacturing apparatus 10 directly images (observes) the concentric pattern of the optical sheet from directly above, detects the center of the concentric circle of the optical sheet that serves as a reference mark, and further aligns the optical sheet with the die 16. As a result, the manufacturing apparatus 10 can more easily, quickly, and accurately cut out the optical sheet from the base material W. In addition, as a more preferred embodiment, the through hole 46 provided in the die 16 is tapered, gradually decreasing in diameter toward the cutting edge 42. This narrows the imaging area of ​​the imaging device 30, allowing imaging to be performed with the die 16 and the optical sheet (base material W) in close proximity. Therefore, with this configuration, it is possible to detect the center of the concentric pattern more accurately and easily.

[0063] As described above, according to the present invention, in the manufacture of optical sheets by cutting out individual optical sheets from a base material on which the optical sheets are formed, it is possible to improve the precision of cutting out the optical sheets, reduce initial costs and running costs, and also simplify the manufacture of optical sheets.

[0064] The above describes in detail the optical sheet manufacturing method and optical sheet manufacturing apparatus of the present invention, but the present invention is not limited to the above-mentioned examples, and various improvements or modifications may be made within the scope that does not deviate from the gist of the present invention.

[0065] It is suitable for use in the production of optical sheets such as liquid crystal lenses.

[0066] REFERENCE SIGNS LIST 10 Manufacturing device 12 Base 14 Cutting die support base 16 Cutting die 18 Post 24 Table support base 26 Placement table 28 Moving mechanism 30 Imaging device 32 Image analysis device 40 Main body 40a Mounting hole 42 Cutting edge 46 Through hole 46a Large diameter portion 46b Small diameter portion 48 Imaging device support portion 50 Imaging element 52 Light source 54 Half mirror 56 Linear polarizer 60 Liquid crystal lens 62 Liquid crystal compound W (optical sheet) base material

Claims

1. When cutting out an optical sheet having a concentric pattern from an optical sheet base material on which the optical sheet is formed, detecting a center of the concentric pattern of the optical sheet, and determining a cutout position of the optical sheet in the optical sheet base material according to a result of detecting the center of the concentric pattern; A method for manufacturing an optical sheet, comprising: detecting the center of the concentric pattern of the optical sheet using an image obtained by irradiating the optical sheet with linearly polarized light.

2. The method for manufacturing an optical sheet according to claim 1 , further comprising the step of detecting a center of the concentric pattern of the optical sheet by using light reflected from the optical sheet base material.

3. The optical sheet is cut out using a die having a through hole at the center, detecting a center of the concentric pattern of the optical sheet from a side opposite to a cutting edge of the die through the through hole of the die; The method for manufacturing an optical sheet according to claim 1 or 2, further comprising aligning the center of the detected concentric pattern of the optical sheet with the center of the die to determine the cutting position of the optical sheet in the optical sheet base material by the die.

4. The method for producing an optical sheet according to claim 3 , wherein the through holes have a tapered shape in which a diameter gradually decreases toward the optical sheet base material.

5. The method for manufacturing an optical sheet according to claim 3 , wherein the center of the concentric pattern of the optical sheet is detected by performing image analysis on an image captured by an imaging device.

6. The method for manufacturing an optical sheet according to claim 5 , wherein an optical axis of the imaging device and a center of the through hole are aligned.

7. The method for producing an optical sheet according to claim 1 , wherein the concentric pattern of the optical sheet is a concentric liquid crystal alignment pattern.

8. 3. The method for manufacturing an optical sheet according to claim 1 or 2, wherein after detecting the center of the concentric pattern of the optical sheet, the optical sheet base material is aligned on the spot with a cutting means for cutting out the optical sheet from the optical sheet base material, and then the optical sheet is cut out from the optical sheet base material by the cutting means.

9. An optical sheet manufacturing apparatus for cutting out an optical sheet having a concentric circular pattern from an optical sheet base material on which the optical sheet is formed, the optical sheet comprising: a table on which the optical sheet base material is placed; a cutting die having a through hole at its center, which cuts out the optical sheet from the optical sheet base material; an imaging device that images the optical sheet base material placed on the table through the through hole of the die; an analysis unit that detects a center of the concentric pattern of the optical sheet by performing image analysis on the image captured by the imaging device; an adjustment means for adjusting the positional relationship between the table and the die so that the center of the die coincides with the center of the concentric pattern of the optical sheet, in accordance with the detection result of the center of the concentric pattern of the optical sheet by the analysis means.