JP4930774B2 - Manufacturing method of optical element manufacturing mold and optical element manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a mold for manufacturing an optical element and a method for manufacturing an optical element.

  As a method of manufacturing a micro optical element array in which a large number of micro optical elements (micro convex lenses, concave lenses, prisms, etc.) are arranged, a micro optical element array having a shape in which irregularities are alternately continued on a molding surface (cavity surface) A method is known in which a resin is molded by injection molding, compression molding, cast molding, or the like using a mold having an inverted shape. Typical examples of the processing method of the molding surface of the mold include a cutting method and an indentation method.

  However, in the cutting method, only inversion shapes corresponding to one micro optical element can be processed at a time, and an enormous amount of time is required to form an array, and therefore indentation processing is frequently used.

Japanese Patent Application Laid-Open No. 11-142609 discloses an indentation processing method in which an indenter is pressed against a molding surface with a predetermined pressure to form a large number of indentations at predetermined intervals.
Japanese Patent Laid-Open No. 11-142609

  However, in the above indentation processing method, the indentation previously formed is deformed by the indenter when forming the indentation next to the indentation. Was difficult.

  The present invention has been made in view of such circumstances, and an object thereof is to make it possible to accurately form a shape in which irregularities are alternately continued by an indentation processing method.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes a first step of forming a molding surface on a mold base material for mold production and forming a plurality of recesses by indenting the molding surface; A second step of creating a mold base material for manufacturing an optical element using a mold for mold manufacturing created in one step, and a mold base material for manufacturing an optical element prepared in the second step Reversing the optical element by indenting a plurality of planar portions located between a plurality of convex portions corresponding to the plurality of concave portions of the mold for manufacturing the mold produced in the first step, which is a molding surface And a third step of forming the shape.

  According to a second aspect of the present invention, in the method for manufacturing a mold for manufacturing an optical element according to the first aspect, the second step is performed by an electroforming method.

  According to a third aspect of the present invention, in the method for manufacturing a mold for manufacturing an optical element according to the first or second aspect, in the first step, before the molding surface of the mold base material for the mold manufacturing is indented. Further, the molding surface is mirror-polished.

  According to a fourth aspect of the present invention, there is provided an optical material manufacturing method using the optical element manufacturing mold manufactured by the optical element manufacturing mold manufacturing method according to any one of the first to third aspects. It is a manufacturing method of the optical element characterized by transferring the shape of the molding surface of the metal mold.

  According to this invention, it is possible to accurately form a shape in which irregularities are alternately continued by an indentation processing method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an optical element manufacturing mold manufactured by the manufacturing method according to the first embodiment of the present invention.

  This optical element manufacturing mold 1 is for manufacturing a microprism array (not shown).

  A reverse surface of the microprism array is formed on the molding surface 1a of the optical element manufacturing mold 1. In addition, the pitch of the convex part 1b is 0.1 mm, and the height of the convex part 1b is 0.03 mm.

  Although not shown in FIG. 1, in addition to the inverted shape of the microprism array, inverted shapes of a number of micro optical elements (for example, convex lenses, concave lenses, etc.) are formed on the molding surface 1a by an indentation processing method.

  The optical element manufacturing mold 1 is manufactured using an indentation processing machine. As the indenting machine, a modified Vickers hardness tester (Matsuzawa Seiki, MV-1S) was used.

  Next, a method for manufacturing an optical element manufacturing mold according to the first embodiment of the present invention will be described.

  FIG. 2 is a cross-sectional view for explaining the first step.

  FIG. 2A shows a state in the middle of forming the inverted shape of the microprism array by pressing the indenter 5 against the molding surface 2a of the base material (die base material for mold manufacture) 2. FIG. Indicates the state after the inverted shape of the prism array is formed.

  The molding surface 2a of the base material 2 is polished to a mirror finish before being indented. As the material of the base material 2, martensitic stainless steel which is a crystalline material is used. Martensitic stainless steel has properties of high strength and high hardness. Note that brass, nickel or the like may be used instead of martensitic stainless steel.

  The indenter 5 is an indenter made of a diamond tip having a wedge-shaped tip.

  The tip of the indenter 5 is applied to the molding surface 2a of the base material 2 and pressed to form the recess 2b (FIG. 2 (a)). The indentation depth of the indenter 5 is set so that the previously formed indentation is not deformed by the indenter when the indentation is formed next to the indentation. For example, trial placement is performed in advance using a test piece made of the same material as that used for the base material 2 to confirm the supply power necessary to obtain a predetermined indentation depth (the supply power is the hardness of the base material 2). It depends on the load applied to the base material 2).

  Thereafter, the base material 2 is moved by a predetermined distance in the X-axis and Y-axis directions (see FIG. 1) to form a predetermined number of recesses 2b on the molding surface 2a, thereby completing the mold manufacturing mold 2A (see FIG. 2 (b)).

  FIG. 3 is a cross-sectional view for explaining the second step.

  FIG. 3A shows before electroforming, FIG. 3B shows the middle of electroforming, and FIG. 3C shows after electroforming.

  Electroforming is performed, for example, by the following steps.

  First, the pre-plating process (water washing etc.) of the metal mold | die 2A for metal mold | die manufacture is performed (refer Fig.3 (a)).

Next, the mold manufacturing mold 2A is immersed in a nickel plating tank (not shown), and nickel electroforming is performed. The electroforming conditions of pH, temperature, current density and time are pH 3 to 4.5, 40 to 50 ° C., 5 to 30 A / dm ² and 10 days (216H), respectively.

  As a result, a plating layer 1A having a thickness of about 5 mm is formed on the surface of the mold manufacturing mold 2A made of martensitic stainless steel (see FIG. 3B).

  Thereafter, a jig (not shown) such as a wedge is inserted between the plating layer 1A and the mold manufacturing mold 2A to separate the plating layer 1A from the mold manufacturing mold 2A. The plating layer 1A separated from the mold 2A for mold manufacture is the mold base material 1B for optical element manufacture (see FIG. 3C). Flat portions 1d and convex portions 1b are alternately arranged on the molding surface 1a of the optical element manufacturing mold base material 1B.

  FIG. 4 is a cross-sectional view for explaining the third step.

  4A shows before indentation processing, FIG. 4B shows in the middle of indentation processing, and FIG. 4C shows after indentation processing.

  The indenter 5 is pressed (indented) on the flat surface portion 1d located between the convex portion 1b and the convex portion 1b of the molding surface 1a of the optical element manufacturing mold base material 1B (see FIG. 4A) ( FIG. 4 (b)). At this time, trial placement is performed in advance using a test piece made of the same material as that used for the mold base material 1B for manufacturing the optical element, and the supply power necessary to obtain a predetermined indentation depth is confirmed. By indenting all the flat portions 1d, the inverted shape of the microprism array is formed on the molding surface 1a, and the optical element manufacturing mold 1 is completed (see FIG. 4C).

  Thereafter, for example, a plastic raw material (for example, acrylic resin) that can be an optical material is put into an injection molding machine, heated to a melting temperature, plasticized, and the plastic raw material is put into a mold in which the optical element manufacturing mold 1 is incorporated. After being filled and cooled and solidified, it is separated from the optical element manufacturing mold 1. As a result, a microprism array having an inverted shape of the molding surface 1a of the optical element manufacturing mold 1 is completed.

  According to this embodiment, not only when the indenter 5 has an obtuse tip, but also when the acute indenter 5 is used, the molding surface 1a of the optical element manufacturing die base material 1B is used. Since the previously formed indentation (recess 1c) is not deformed by the indenter 5 when the indentation (another recess 1c) is formed next to the indentation, the inversion of the microprism array in which the protrusions 1b and the recesses 1c continue alternately The shape can be accurately formed on the molding surface 1a of the mold base material 1B for manufacturing an optical element by an indentation method.

  Next, a method for manufacturing a microlens array will be described.

  FIG. 5 is a view for explaining a method of manufacturing an optical element manufacturing mold according to the second embodiment of the present invention.

  5A corresponds to the first step, FIGS. 5B and 5C correspond to the second step, and FIG. 5D corresponds to the third step.

  An indenter (not shown) used in the first step is an indenter having a hemispherical tip corresponding to the shape of the microlens.

  First, recesses are formed at equal intervals on the molding surface of a mirror-finished mold base material (not shown) by an indentation method. The indentation depth of the indenter is set so that the previously formed indentation is not deformed by the indenter when the indentation is formed next to the indentation. At this time, trial placement is performed in advance using a test piece made of the same material as that used for the mold base material for mold manufacture, and the supply power necessary to obtain a predetermined indentation depth is confirmed.

  A predetermined number of recesses 12b are formed on the molding surface 2a to complete the mold for manufacturing a mold 12A. (See FIG. 5A).

  Next, after pre-plating (water washing etc.) of the mold 12A for mold manufacture, it is immersed in a nickel plating tank (not shown) and nickel electroforming is performed. The conditions for electroforming are the same as those described above.

  As a result, a plating layer 11A having a thickness of about 5 mm is formed on the molding surface 2a of the mold for mold production 12A (see FIG. 5B).

  Thereafter, similarly to the first embodiment, the plating layer 11A is separated from the mold for manufacturing the mold 12A. The plating layer 11A separated from the mold for manufacturing mold 12A is the optical element manufacturing mold base material 11B (see FIG. 5C). Flat portions 11d and convex portions 11b are alternately arranged on the molding surface 11a of the optical element manufacturing die base material 11B.

  Next, an indenter is pressed (indented) into the flat surface portion 11d located between the convex portion 11b and the convex portion 11b of the molding surface 11a of the optical element manufacturing die base material 11B. At this time, trial placement is performed in advance using a test piece made of the same material as that used for the mold base material 11B for manufacturing the optical element, and supply power necessary for obtaining a predetermined indentation depth is confirmed. By indenting all the flat portions 11d, the inverted shape of the microlens array in which hemispherical concave portions 11c and convex portions 11b are alternately arranged is formed on the molding surface 11a, and the optical element manufacturing die 11 is completed. (See FIG. 5 (d)).

  Thereafter, for example, a plastic raw material (for example, acrylic resin) that can be an optical material is put into an injection molding machine, heated to a melting temperature and plasticized, and the plastic raw material is a mold (not shown) in which an optical element manufacturing mold 11 is incorporated. And after cooling and solidifying, it is separated from the mold 11 for manufacturing an optical element. As a result, a microlens array having a reverse shape of the molding surface 11a of the optical element manufacturing mold 11 is completed.

  Convex lenses (corresponding to the concave portions 11c) and concave lenses (corresponding to the convex portions 11b) are alternately arranged on the surface of the microlens array.

  According to this embodiment, the same effects as those of the first embodiment can be obtained.

  In the first embodiment, the same indenter 5 is used in the first step and the third step. However, in the first embodiment, the top of the convex portion 1b is changed by changing the indenter used in the first step and the third step. The corner and the apex angle of the recess 1c can be made different. In the second embodiment, the curvature radius of the projection 11b and the curvature radius of the recess 1c can be made different.

FIG. 1 is a perspective view showing an optical element manufacturing mold manufactured by the manufacturing method according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view for explaining the first step. FIG. 3 is a cross-sectional view for explaining the second step. FIG. 4 is a cross-sectional view for explaining the third step. FIG. 5 is a view for explaining a method of manufacturing an optical element manufacturing mold according to the second embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,11: Optical element manufacturing metal mold | die, 1B, 11B: Optical element manufacturing metal mold | die 1a, 2a: Molding surface, 1b, 11b: Convex part, 1c, 2b, 11c: Concave part, 1d, 11d: Plane part, 2: Base material (mold base material for mold manufacture), 2A, 12A: Mold for mold manufacture.

Claims (4)

A first step of forming a molding surface on a mold base material for mold production and creating a plurality of recesses by indenting the molding surface;
A second step of creating a mold base material for producing an optical element using the mold for producing a mold produced in the first step;
A plurality of convex portions corresponding to the plurality of concave portions of the mold manufacturing die formed in the first step, which are molding surfaces of the optical element manufacturing die base material created in the second step. And a third step of forming an inverted shape of the optical element by performing indentation in a plurality of flat portions positioned therebetween.   The method for manufacturing a mold for manufacturing an optical element according to claim 1, wherein the second step is performed by an electroforming method.   3. The optical element manufacturing die according to claim 1, wherein in the first step, the molding surface is mirror-polished before the molding surface of the mold base material for mold production is indented. Mold manufacturing method.   The shape of the molding surface of the optical element manufacturing mold is applied to an optical material using the optical element manufacturing mold manufactured by the method for manufacturing an optical element manufacturing mold according to claim 1. A method for producing an optical element, wherein the optical element is transferred.

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