Method for manufacturing prism array

Abstract

To provide a method for manufacturing a prism array, which can efficiently mass-produce high-quality prism arrays.SOLUTION: A method for manufacturing a prism array 1 according to the present invention, which comprises a plurality of irregularly shaped cells 11, each of which constitutes a discontinuous prism, arranged in a two-dimensional array, includes: a mold design step S1 in which a mold model M1 having an inverted shape of a molded product model M0 is designed based on the molded product model M0 of a pre-designed prism array 1; a mold machining step S2 in which a mold base material W is machined based on the mold model M1 designed in the mold design step S1 to produce a mold 51 having a concave-convex structure; and a molding step S3 in which a resin as a molding material is molded into the prism array 1 using a mold device 60 having the mold 51.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a prism array. [Background technology]

[0002] Conventionally, an optical element called a prism array has been proposed. A prism array is an optical element formed by arranging prisms in a two-dimensional array, and can project a desired graphic pattern by irradiating light from a light source. One method proposed for manufacturing such a prism array is to apply an electroplating technique called electroforming to form a mold with a textured surface, and then press the mold into a heated and softened resin (see, for example, Non-Patent Documents 1 and 2). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Collection of Research Results (Reiwa 4)" Shizuoka Prefectural Industrial Technology Research Institute, April 2023 [Non-patent document 2] "Shizuoka Prefectural Industrial Technology Research Institute Research Report No. 16, November 2023" Shizuoka Prefectural Industrial Technology Research Institute ISSN 1883-2350 CODEN:SKGKBP Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional technologies have problems such as the tendency for the molded product to have a defective shape due to peeling of the plating during mold formation, and the fact that molds made by electroforming are not suitable for mass production because the molded product has poor releasability.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a prism array that can efficiently mass-produce high-quality prism arrays. [Means for solving the problem]

[0006] The method for manufacturing a prism array according to the present invention is a method for manufacturing a prism array comprising a plurality of irregularly shaped cells, each of which constitutes a discontinuous prism, arranged in a two-dimensional array, and includes the following steps: a mold design process for designing a mold model having an inverted shape of a pre-designed molded product model of the prism array, based on the mold model designed in the mold design process, by cutting a mold base material to produce a mold having a concave-convex structure, based on the mold model designed in the mold design process; and a molding process for molding a molding material into the prism array using a mold device having the mold.

[0007] According to this method, in the mold processing step, an irregular uneven structure is formed by cutting the mold base material to produce the mold, and in the molding step, a mold device equipped with the mold is used to mold the molding material into a prism array, thereby achieving the effect of efficiently mass-producing high-quality prism arrays.

[0008] The mold processing step is a step in which a three-axis or more processing device having at least three mutually perpendicular linear axes, X, Y, and Z, is used to perform cutting processing on the mold base material W with a tool to form a two-dimensional array of cell molding surfaces that have two opposing sides parallel to the X direction and two opposing sides parallel to the Y direction and are rectangular when viewed in the Z direction, and includes a step of performing scanning line processing in which the tool is moved relatively in the Z direction based on the Z height corresponding to the XY position of each cell molding surface, and the tool is repeatedly fed in the X direction and pick-fed in the Y direction.

[0009] This method has the advantage that a mold having an irregular concave-convex structure can be manufactured with high precision by scanning line processing.

[0010] The die machining step also includes a step of performing finish machining using a ball end mill as the tool.

[0011] This method has the advantage that a mold having an uneven structure consisting of a plurality of irregular cell molding surfaces can be manufactured with high precision by scanning line machining using a ball end mill.

[0012] The tool also has a cutting edge made of diamond.

[0013] According to this method, by performing cutting processing using a tool having a diamond cutting edge, it is possible to achieve a polish-free mirror finish on each cell molding surface.

[0014] The die machining step also includes a step of performing finish machining using the tool having a blade with an effective area of ​​64% or more within one cell.

[0015] This method has the effect of preventing breakage of the tool due to the processing load, minimizing the corner R portion in the irregular concave-convex structure, and forming the cell molding surface with high precision.

[0016] The die machining step also includes a step of performing finish machining by setting the cutting speed to 15 m / min to 20 m / min and the Y direction pitch to 5% or less of the cutting edge diameter of the tool.

[0017] This method has the effect of more reliably minimizing the corner rounding in the irregular concave-convex structure and forming the cell molding surface with high precision.

[0018] Furthermore, the processing device is a four-axis or more processing device having at least one rotational axis in addition to the three linear axes, and the mold processing process includes a process of tilting the tool relative to the mold base material to perform cutting.

[0019] This method has the advantage that when processing the corner R portions of the irregular concave-convex structure of the cell molding surface, the corner R portions can be minimized by cutting the mold base material with a tool from an oblique angle, thereby enabling the cell molding surface to be formed with high precision. In addition, it is possible to shorten the effective length of the tool, which has the advantage of more effectively preventing tool breakage due to processing load.

[0020] The die machining step also includes a step of performing a hail cutting using a hail bit as the tool.

[0021] This method has the advantage that a mold having an irregular concave-convex structure can be manufactured with high precision by cutting.

[0022] The molding step is injection molding or compression molding.

[0023] This method has the effect of enabling efficient mass production of high-quality prism arrays. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a perspective view showing an example of a prism array (molded product model) manufactured by a manufacturing method for a prism array according to an embodiment of the present invention. [Figure 2] FIG. 1 is a plan view showing the entire prism array (molded product model). [Figure 3] FIG. 2 is an enlarged plan view showing a part of the prism array (molded product model). [Figure 4] FIG. 1 is a schematic diagram showing a projection optical system using a prism array. [Figure 5] 1 is a flowchart showing a flow of a manufacturing method of a prism array according to the present embodiment. [Figure 6] FIG. 2 is a cross-sectional view showing an example of a mold model (mold). [Figure 7] FIG. 1 is a perspective view showing an example of a processing device (three-axis processing machine) used in a mold processing step. [Figure 8]FIG. 1 is a front view showing an example of a tool used in a mold machining process. [Figure 9] 10 is a flowchart showing the flow of a mold machining process. [Figure 10] FIG. 10 is a perspective explanatory view schematically showing a state in which a mold is machined by a machining device. [Figure 11] FIG. 10 is another perspective explanatory view schematically showing the state of die machining by the machining device. [Figure 12] FIG. 2 is an enlarged explanatory view schematically showing a state of mold machining by the machining device. [Figure 13] FIG. 2 is a perspective view showing an example of a mold device used in a molding process (injection molding). [Figure 14] 10 is a cross-sectional view showing a mold clamping process in which a movable mold and a fixed mold are butted together in a mold device to form a cavity. FIG. [Figure 15] FIG. 4 is an enlarged cross-sectional view showing a main part of a mold device in an injection process. [Figure 16] 10A and 10B are cross-sectional views showing an ejection step of releasing the prism array from the mold device. [Figure 17] 1 is a flowchart showing the flow of a molding process (injection molding). [Figure 18] FIG. 10 is a perspective view showing an example of a machining device (a five-axis machining device) used in a die machining step in the first modified example. [Figure 19] FIG. 10 is a perspective explanatory view schematically showing a state of die machining by a machining device (a five-axis machining device) in a first modified example. [Figure 20] FIG. 11 is a perspective explanatory view schematically showing a state of die machining (cutting by hay bite) by a machining device in a second modified example. [Figure 21] FIG. 10 is an explanatory diagram schematically showing the principle of the molding step (compression molding) in the third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, a specific embodiment of a method for manufacturing a prism array according to an embodiment of the present invention will be described with reference to the drawings.

[0026] <Explanation of Prism Array 1> First, a prism array 1 manufactured by a prism array manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing an example of a prism array 1 (molded product model M0) manufactured by the prism array manufacturing method. FIG. 2 is a plan view showing the entire prism array 1 (molded product model M0). FIG. 3 is a plan view showing an enlarged portion of the prism array 1 (molded product model M0). FIG. 4 is a schematic diagram showing a projection optical system 2 using the prism array 1.

[0027] Prism array 1 is an optical component made of a transparent resin material, and as shown in Fig. 1, is composed of a plurality of irregularly shaped cells 11 arranged in a two-dimensional array, each of which constitutes a discontinuous prism. Specific examples of resin materials suitable for use in prism array 1 include PMMA (polymethyl methacrylate) and PC (polycarbonate). In this specification, "discontinuous prisms" means that the boundaries between adjacent prisms are discontinuous.

[0028] As shown in FIGS. 2 and 3, the prism array 1 has a square shape in a plan view with a side length of a. A plurality of cells (b × c cells) are arranged in a two-dimensional array, and the entire prism array 1, consisting of b × c cells, is formed into a rectangular shape (including a square) with one side a × b = B and the other side a × c = C. Each cell 11 can be set to any size depending on the application. For example, the cell 11 may be a minute prism with a side length a of less than 1.0 mm, or a prism with a length a of several millimeters or more. When each cell 11 is made up of minute prisms, the prism array 1 is sometimes called a microprism array. Furthermore, each cell 11 is not limited to a square shape with the same length and width in a plan view, but may also be a rectangular shape with different length and width in a plan view.

[0029] The prism array 1 is designed to project predetermined figures or characters using a plurality of cells 11, which are discontinuous prisms, and has an irregular uneven shape in which the thickness of the prism, the inclination angle and direction of the exit surface, etc. differ for each cell 11.

[0030] 4, the projection optical system 2 includes a prism array 1, a light source 3, and a screen 4. The projection optical system 2 is an optical system for projecting predetermined figures or characters onto the screen 4.

[0031] The light source 3 is configured, for example, by an LED light source. The prism array 1 is disposed on the optical path of the light source 3 between the light source 3 and the screen 4. When the light emitted from the light source 3 enters the prism array 1, it is refracted in a predetermined two-dimensional pattern by each cell 11, and is projected onto the screen 4 as a predetermined figure or character. FIG. 4 shows an example in which an arrow figure is projected onto the screen 4.

[0032] <Explanation of Prism Array Manufacturing Method> Next, a method for manufacturing a prism array according to an embodiment of the present invention will be described with reference to FIGS. 5 to 17. FIG. 5 is a flowchart showing the flow of the manufacturing method of the prism array 1 according to this embodiment. FIG. 6 is a cross-sectional view showing an example of a mold model M1 (mold 51). FIG. 7 is a perspective view showing an example of a processing device 20 (a three-axis processing machine) used in the mold processing step S2. Jigs and other devices for fixing the mold base material W are omitted from FIG. 7. FIG. 8 is a front view showing an example of a tool 21 used in the mold processing step S2. FIG. 9 is a flowchart showing the flow of the mold processing step S2. FIG. 10 is a perspective explanatory view schematically showing the mold processing by the processing device 20. FIG. 11 is another perspective explanatory view schematically showing the mold processing by the processing device 20. FIG. 12 is an enlarged explanatory view schematically showing the mold processing by the processing device 20. FIG. 13 is a perspective view showing an example of a mold device 60 used in the molding step S3 (injection molding). FIG. 14 is a cross-sectional view showing the mold clamping step S31 in which a fixed mold 61 and a movable mold 62 are butted together in the mold device 60 to form a cavity CV. Fig. 15 is an enlarged cross-sectional view showing a main part of mold device 60 in injection step S32. Fig. 16 is a cross-sectional view showing ejection step S36 for releasing prism array 1 from mold device 60. Fig. 17 is a flowchart showing the flow of molding step S3 (injection molding).

[0033] It is assumed that the prism array 1 to be manufactured in this embodiment is designed in advance as a molded product model M0, which is a numerical model that defines data such as the number, shape, and dimensions of the cells 11.

[0034] In the method for manufacturing a prism array according to this embodiment, as shown in the flowchart of FIG. 5, first, in step 1 (hereinafter abbreviated as S1, the same applies to the other steps) of the mold design process, a mold model M1 having an inverted shape of a molded product model M0 of a pre-designed prism array 1 is designed based on the molded product model M0. The mold model M1 is a numerical model that defines data such as the shape and dimensions of a mold 51, which will be described later. The mold 51 is a core mold that is fitted into a fixed mold 61 of a mold device 60 for injection molding, which will be described later. The mold model M1 (mold 51) has cell molding surfaces 511, as shown in FIG. 6. Each cell molding surface 511 has the inverted shape of each cell 11 in the molded product model M0.

[0035] Next, in the mold machining step S2, a mold base material W is machined based on the mold model M1 designed in the mold design step S1 to produce a mold 51 having an irregular concave-convex structure consisting of multiple cell molding surfaces 511. In the mold machining step S2, a machining device 20 shown in FIG. 7 is used. The machining device 20 is a three-axis machining device having three linear axes, X, Y, and Z. The mold base material W to be machined is machined using a tool 21. As shown in FIG. 8, the tool 21 is a ball end mill equipped with a cutting tool 211. In FIG. 8, L represents the effective length of the tool 21, D represents the diameter of the cutting tool 211, and R represents the radius of curvature of the cutting tool 211. A ball end mill equipped with a cutting tool 211 made of diamond can be suitably used as the tool 21. Since the tool 21 needs to avoid interference with the unevenness of each cell molding surface 511 and be less likely to break, it is preferable that the effective length L is longer than the maximum value T of the Z height of each cell molding surface 511 (see Figures 6 and 12) and as short as possible.

[0036] The mold machining step S2 is a step in which a machining device 20 having three linear axes, X, Y, and Z, perpendicular to each other is used to perform cutting on the mold base material W with a tool 21, thereby forming a plurality of cell molding surfaces 511 in a two-dimensional array, each having two opposing sides parallel to the X direction and two opposing sides parallel to the Y direction and exhibiting a rectangular shape when viewed in the Z direction. Specifically, as shown in Figures 10 to 12, scanning line machining is performed in which the tool 21 is moved relatively in the Z direction based on the Z height corresponding to the XY position of each cell molding surface 511, while repeatedly feeding in the X direction and pick-feeding in the Y direction.

[0037] Specifically, the die machining step S2 is performed according to the flow shown in the flowchart of Fig. 9. First, in S21, rough machining is performed.

[0038] Subsequently, in S22, semi-rough machining is carried out.

[0039] Furthermore, in S23, semi-finishing is performed. Each of the roughing S21, semi-roughing S22, and semi-finishing S23 steps is performed under appropriate conditions using an appropriate tool 21 (blade 211) in consideration of the tool load as a step leading to the finishing S24.

[0040] Finally, in S24, finishing processing is performed. In finishing processing S24, the die base material W is cut by scanning line processing using the tool 21. The cutting conditions are set, for example, such that the cutting speed is 15 m / min to 20 m / min and the Y direction pitch is 5% or less of the cutting tool diameter D of the tool 21. By the above cutting processing, the production of the die 51 is completed.

[0041] Each step from rough machining S21 to finish machining S24 can be configured as a mold machining program that can be executed by a control unit (not shown) of the processing device 20. That is, it is configured as a mold machining program that causes a computer constituting the control unit to set a movement path of the tool 21 in the mold base material W based on shape data (mold model M1) of the mold 51. By executing the above mold machining program, the mold 51 can be manufactured at high speed and with high precision.

[0042] Returning to the flowchart of FIG. 5, in the molding step S3, resin is filled into cavity CV of mold device 60 having mold 51 produced in mold processing step S2, and prism array 1 is injection molded.

[0043] Here, the configuration of the mold device 60 used in the molding step S3 will be described with reference to Figures 13 to 16. The mold device 60 is configured to include a fixed mold 61, a movable mold 62, and an ejector pin 63.

[0044] The fixed mold 61 has a nesting structure, and the mold 51 serving as a core mold is fitted into the fixed mold 61. The mold 51 is fixed with the cell molding surface 511 facing the side opposite the movable mold 62.

[0045] The movable mold 62 is a mold that moves by mold opening and closing operations, has a nesting structure, and mold 52 as a cavity mold is fitted into it. Mold 52 is fixed at a position facing mold 51 on the fixed mold 61 side. Mold 52 has recesses 521 that correspond to the external shape of the prism array 1 excluding each cell 11.

[0046] Next, the flow of the molding step S3 (injection molding) will be described with reference to the flowchart in Fig. 17. Specifically, the molding step S3 includes a mold clamping step S31, an injection step S32, a pressure holding step S33, a cooling step S34, a mold opening step S35, and an ejection step S36, in that order, and injection molding of the prism array 1 is completed through this series of steps.

[0047] In the mold clamping process S31, as shown in FIG. 14, the movable mold 62 is moved and butted against the fixed mold 61, thereby sealing the recess 521 of the mold 52 and forming a cavity CV between the cell molding surface 511 of the mold 51.

[0048] Next, in the injection step S32, as shown in FIG. 15, molten resin is injected from the nozzle NZ of the injection cylinder, passes through the sprue SP, runner RN, and gate GT, and fills the cavity CV.

[0049] Next, in a pressure holding step S33, pressure is continuously applied to the molten resin injected into the mold device 60 to compensate for the decrease in the volume of the resin that progresses as it cools.

[0050] Next, in the cooling step S34, the molded product (prism array 1) is cooled in the mold device 60 until it reaches a temperature at which it can be removed.

[0051] When the resin material has cooled sufficiently after a predetermined time has passed, a mold opening step S35 is executed, in which the movable mold 62 is moved to separate it from the fixed mold 61. At this time, the prism array 1 as a molded product is stuck to the movable mold 62.

[0052] Finally, in the ejection step S36, the ejector pins 63 are advanced from the movable mold 62, whereby the prism array 1 is released and ejected as shown in FIG. 16, and the molding step S3 is completed.

[0053] As described above, the manufacture of the prism array 1 is completed through the mold design step S1, mold machining step S2, and molding step S3.

[0054] <Summary of the embodiment> As is clear from the above detailed description, the method for manufacturing a prism array according to this embodiment is a method for manufacturing a prism array 1 comprising a plurality of irregularly shaped cells 11, each of which constitutes a discontinuous prism, arranged in a two-dimensional array, and includes a mold design process S1 in which a mold model M1 having an inverted shape of a molded product model M0 is designed in advance based on a molded product model M0 of the prism array 1; a mold processing process S2 in which a mold base material W is cut based on the mold model M1 designed in the mold design process S1 to produce a mold 51 having a concave-convex structure; and a molding process S3 in which a mold device 60 having the mold 51 is used to mold a resin as a molding material into the prism array 1.

[0055] According to this method, in the mold processing step S2, an irregular uneven structure is formed by cutting the mold base material W to produce the mold 51, and in the molding step S3, a mold device 60 equipped with the mold 51 is used to mold resin as a molding material into the prism array 1, thereby achieving the effect of efficiently mass-producing high-quality prism arrays 1.

[0056] In addition, the mold processing step S2 is a step in which a processing device 20, which is a three-axis processing machine having three linear axes, X, Y, and Z, which are perpendicular to each other, is used to perform cutting processing on the mold base material W with a tool 21, to form a plurality of irregular cell molding surfaces 511 in a two-dimensional array, each having two opposing sides parallel to the X direction and two opposing sides parallel to the Y direction and having a rectangular shape when viewed in the Z direction, and includes a step of performing scanning line processing in which the tool 21 is moved relatively in the Z direction based on the Z height corresponding to the XY position of each cell molding surface 511, and the tool 21 is repeatedly fed in the X direction and picked in the Y direction.

[0057] This method has the effect of enabling a mold 51 having an uneven structure consisting of a plurality of irregular cell molding surfaces 511 to be manufactured with high precision by scanning line processing.

[0058] The die machining step S2 also includes a step of performing a finishing step S24 using a ball end mill as the tool 21.

[0059] This method has the effect of enabling a mold 51 having an uneven structure consisting of a plurality of irregular cell molding surfaces 511 to be manufactured with high precision by scanning line machining using a ball end mill.

[0060] The tool 21 also has a cutting tool 211 made of diamond.

[0061] According to this method, by performing cutting processing using a tool 21 having a cutting tool 211 made of diamond, it is possible to achieve a mirror finish on each cell molding surface 511 without polishing.

[0062] The die machining step S2 also includes a step of performing a finishing step S24 using a tool 21 having a blade 211 whose effective area within one cell is 64% or more.

[0063] This method has the effect of preventing breakage of the tool 21 due to the processing load, minimizing the corner R portion in the irregular concave-convex structure, and forming the cell molding surface 511 with high precision.

[0064] The die machining step S2 also includes a step of setting the cutting speed to 15 m / min to 20 m / min and the Y direction pitch to 5% or less of the cutting edge diameter D of the tool 21 to perform finish machining S24.

[0065] This method has the effect of more reliably minimizing the corner rounding in the irregular concave-convex structure and forming the cell molding surface 511 with high precision.

[0066] <First Modification> In the above embodiment, an example was shown in which a three-axis machining device was used as the processing device 20 used in the mold machining process S2, but the processing device 20 may be a three-axis or more machining device, such as a four-axis or five-axis machining device. A first modified example will be described below with reference to FIGS. 18 and 19. FIG. 18 is a perspective view showing an example of the processing device 20 (a five-axis machining device) used in the mold machining process S2 in the first modified example. Jigs and the like for fixing the mold base material W are omitted from FIG. 18. FIG. 19 is a perspective explanatory view schematically showing the state of mold machining by the processing device 20 in the first modified example.

[0067] As shown in Fig. 18, the processing device 20 according to this modification is a five-axis processing machine equipped with three linear axes, X, Y, and Z, as well as two rotational axes, A and C (the A axis is a rotational axis about the X axis, and the C axis is a rotational axis about the Z axis). According to the method according to this modification, when processing the corner R portions of the irregular concave-convex structure of the cell molding surface 511, as shown in Fig. 19, cutting is performed obliquely with the tool 21 against the mold base material W, thereby minimizing the corner R portions and forming the cell molding surface 511 with high precision. In addition, since it is possible to shorten the effective length L of the tool 21, it is possible to more effectively prevent breakage of the tool 21 due to the processing load.

[0068] <Second Modification> In the above embodiment and the first modified example, an example was shown in which a ball end mill, which is a rotary tool, was used as the tool 21 used in the mold machining step S2, but this is not limited to this. Below, a second modified example will be described with reference to Fig. 20. Fig. 20 is a perspective explanatory view that schematically shows the state of mold machining (cutting by hay bite) by the machining device 20 in the second modified example.

[0069] In this modified example, in the finishing process S24, as shown in Fig. 20, the cell molding surface 511 is finished by hail cutting using a hail bit as the tool 21. In Fig. 20, the arrow indicates the relative moving direction of the tool 21 with respect to the mold base material W (the X direction, which is one of the arrangement directions of the cell molding surface 511). The method according to this modified example has the effect of being able to manufacture a mold 51 having an irregular concave-convex structure with high precision by cutting, similar to the above embodiment.

[0070] <Third Modification> In the above embodiment, an example in which injection molding is performed in the molding step S3 has been described, but the present invention is not limited to this. A third modified example will be described below with reference to Fig. 21. Fig. 21 is an explanatory diagram that schematically shows the principle of the molding step S3 (compression molding) in the third modified example.

[0071] 21, in molding step S3, a molding material such as a rubber material or a thermoplastic resin is poured into the recess of mold 52 of mold device 60, and mold 51 and mold 52 are brought relatively close to each other to pressurize the molding material, thereby producing a molded product of prism array 1. The method according to this modification has the effect of enabling efficient mass production of high-quality prism arrays 1, as in the above embodiment.

[0072] <Other variations> The present invention is not limited to the above-described embodiment and first to third modified examples, and various modifications can be made without departing from the spirit of the present invention. For example, the shape and material of the tool 21 and the processing conditions in the mold processing step S2 in the above-described embodiment are merely examples, and the present invention is not limited to these. [Explanation of symbols]

[0073] 1 Prism Array 11 cells 20 Processing equipment 21 Tools 211 Cutlery 51 Mold 511 Cell molding surface 60 Mold equipment W mold base material M0 Molded product model M1 mold model CV cavity S1 Mold design process S2 Mold processing process S24 Finishing S3 Molding process

Claims

1. A method for manufacturing a prism array comprising a plurality of irregularly shaped cells, each of which constitutes a discontinuous prism, arranged in a two-dimensional array, the method comprising: a mold design step of designing a mold model having an inverted shape of a molded product model of a predesigned prism array based on the molded product model; a die processing step of manufacturing a die having a concave-convex structure by performing cutting processing on a die base material based on the die model designed in the die design step; a molding step of molding a molding material into the prism array using a mold device having the mold; A method for manufacturing a prism array having the above structure.

2. The mold processing step is a step of performing cutting processing on the mold base material with a tool using a three-axis or more processing device having at least three linear axes, X, Y, and Z, which are orthogonal to each other, to form a plurality of irregular cell molding surfaces in a two-dimensional array, each having two opposing sides parallel to the X direction and two opposing sides parallel to the Y direction and exhibiting a rectangular shape when viewed in the Z direction, 2. The method for manufacturing a prism array according to claim 1, further comprising a step of performing scanning line processing in which the tool is moved relatively in the Z direction based on a Z height corresponding to an XY position on each of the cell molding surfaces, while repeatedly feeding the tool in the X direction and pick-feeding the tool in the Y direction.

3. The method for manufacturing a prism array according to claim 2 , wherein the die machining step includes a step of performing a finishing process using a ball end mill as the tool.

4. The method for manufacturing a prism array according to claim 3 , wherein the tool has a cutting edge made of diamond.

5. 5. The method for manufacturing a prism array according to claim 2, wherein the die machining step includes a step of performing a finishing process using the tool having a blade with an effective area within one cell of 64% or more.

6. The method for manufacturing a prism array according to any one of claims 2 to 4, wherein the mold machining process includes a step of performing finishing processing by setting the cutting speed to 15 m / min to 20 m / min and the Y-direction pitch to 5% or less of the cutting edge diameter of the tool.

7. the processing device is a four-axis or more processing device having at least one rotation axis in addition to the three linear axes, The method for manufacturing a prism array according to claim 2 , wherein the die machining step includes a step of performing cutting by tilting the tool with respect to the die base material.

8. The method for manufacturing a prism array according to claim 1 , wherein the die machining step includes a step of performing hail cutting using a hail bit as the tool.

9. 9. The method for manufacturing a prism array according to claim 1, wherein the molding step is injection molding or compression molding.

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