JP2000033619A - Mold for molding, its manufacture and method for forming microlens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mold for forming an indentation of an aspherical shape in the same shape with good reproducibility on a surface of the mold even without forming the aspherical shape at an indenter and to provide method for manufacturing a microlens of the aspherical shape even without forming the aspherical shape at the indenter. SOLUTION: This mold for molding forms a shape of an indentation obtained by pressing an indenter on a transfer surface of the mold. In this case, the mold is provided with at least one type of a plurality of types of materials (s, b) having different plastic deformation amounts by a strain given by an indenter in a laminar state on the transfer surface of the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a single-lens reflex camera,
The present invention relates to a mold for molding a microlens array used for a display element such as a focusing plate of a movie camera, a liquid crystal display, and a plasma display.

[0002]

2. Description of the Related Art In a compact camera having a reticle and a real image type finder in a single-lens reflex camera, it is necessary to see a bright and clear image when looking through the camera finder. In a microlens applied to such a focusing screen, it is required that the difference in diffusion due to the wavelength of light is small, and that the brightness of the entire focusing screen does not become uneven.

For example, if there is a difference in the diffusion depending on the wavelength of light, even if the light incident on the reticle is white light, it will appear colored when viewed from a certain direction. In addition, it is very unsightly if unevenness occurs in brightness. Further, it is desirable that the brightness naturally decreases as the diffusion angle increases. In order to satisfy such demands, it is already known to make the shape of the microlens array formed on the focusing screen into an aspherical shape.

As a method of forming a microlens on a reticle or the like, an indentation having the same or inverted shape as the lens is formed in a mold, and injection molding or compression is performed using the mold in which the indentation is formed. A reticle having microlenses formed by molding, casting, or the like is formed. When the microlens has an aspherical shape, the indenter forming the indentation is processed into an aspherical shape to form the indentation.

Since the material of the indenter used is formed of a cemented carbide material or diamond, it is difficult to process the indenter. In the case of forming an aspherical surface, it takes a very long time to process the indenter. Must-have. Further, since the indenter wears as the indentation is repeated, it is necessary to replace the indenter after a predetermined number of indentations.

[0006]

As described above, conventionally, when an aspherical indentation is formed, the tip of the indenter must be formed in an aspherical shape. However, the material used for the indenter is extremely difficult to process because it uses a very hard material. In particular, in the case of an aspherical shape, the technology for processing the indenter into an aspherical shape has not been completed. Obtaining a spherical shape is extremely difficult.

Therefore, if it becomes necessary to replace the indenter, the shape of the impression formed before and after the replacement will change. Therefore, an object of the present invention is to provide a mold capable of forming an aspherical indentation of the same shape with good reproducibility on the surface of the mold without performing aspherical processing on the indenter, and an indenter. It is an object of the present invention to provide a manufacturing method capable of manufacturing an aspherical microlens without subjecting an aspherical surface to machining.

[0008]

Therefore, in order to solve the above-mentioned problems, in a first aspect of the present invention, the shape of an indentation obtained by pressing an indenter is formed on a transfer surface of a mold. In the mold, the mold is made of a plurality of types of materials each having a different amount of plastic deformation with respect to the strain given by the indenter,
At least one of the plurality of materials is provided in a layer on the transfer surface.

A mold is constructed by using a plurality of types of materials having different plastic deformation amounts with respect to the strain given as described above, and one of the used materials is formed in a layer on the surface of the mold. Was used. If the mold is pressed to the extent that plastic deformation occurs with a spherical indenter to form an indentation, for example, a shape generated in a material formed in a layer on the surface,
A difference occurs between the material formed in the layer shape and the shape generated in the adjacent material, and an aspherical indentation different from the shape of the indenter is formed.

According to a second aspect of the present invention, there is provided a method of manufacturing a molding die in which an indenter having an aspherical shape is formed by pressing the indenter onto a transfer surface of the die. A material having an amount of plastic deformation different from the amount of plastic deformation generated in the mold substrate with respect to the strain given by the mold is provided in a layer on the transfer surface of the mold substrate, and an indentation is formed on the transfer surface with a spherical indenter. Is formed to form an indentation having an aspherical shape.

According to a third aspect of the present invention, there is provided a method of manufacturing a molding die for manufacturing a die having an aspherical indentation by pressing an indenter against a transfer surface of the die.
A material different from the mold base material is provided on the transfer surface of the mold base material in the form of a layer to form the first layer, and the amount of plastic deformation generated in the first layer with respect to the strain given by the indenter on the transfer surface. The second layer is formed by providing a material having a different plastic deformation amount from the first layer on the surface of the first layer. After that, indentations are formed with a spherical indenter on the transfer surface on which the first layer and the second layer are formed. In this way, an aspherical indentation is formed.

By forming the first layer made of a substance different from each substance between the mold base material and the second layer formed on the outermost surface, the mold material and the outermost surface are formed. It is possible to select the material of the first layer formed on the substrate as an optimum substance. For example, although a certain degree of mechanical strength is required as a material for forming a mold base material, the material for forming the mold base material is limited. The shape of the indentation is
It is largely determined mainly by the difference in the amount of plastic deformation between the material forming the outermost layer and the underlying material. Therefore, it is necessary to select an optimum material as a material for forming the outermost layer with respect to a material selected as a material of the mold base, and the range of selection is reduced. Therefore, the present invention provides a first layer between the second layer formed on the outermost layer and the mold base material, thereby selecting a material for forming the mold base material and a material for forming the outermost layer. The width can be expanded.

According to a fourth aspect of the present invention, there is provided a method of forming a microlens having an aspherical shape, wherein a mold having a transfer surface for transferring the aspherical lens shape to a material for forming an optical element is provided. A material that causes plastic deformation different from the amount of plastic deformation generated in the mold base for the same strain applied to the base material is provided in a layer on the transfer surface of the base material of the mold, and then the transfer surface The indentation is formed with a spherical indenter, and the shape of the indentation is transferred to the material forming the optical element, thereby forming an aspherical microlens on the material forming the optical element.

According to a fifth aspect of the present invention, there is provided a method for forming a microlens having an aspherical shape, wherein the mold base having a transfer surface for transferring the aspherical lens shape to a material for forming an optical element. A first layer is formed on the transfer surface using a material different from the mold material to form a first layer.
On the surface of the layer, for the same applied strain, a material that causes a plastic deformation different from the amount of plastic deformation generated in the mold base material is provided in a layer on the transfer surface of the base material of the mold, and the second layer is formed. Form. Then, the first layer and the second layer form indentations on the transfer surface with an indenter having a spherical shape, and transfer the shape composed of the indentations to the material forming the optical element, thereby forming a material for forming the optical element. A micro lens having an aspherical shape is formed on the substrate.

Next, the present invention will be described in more detail by way of examples. The present invention is not limited only to the embodiments described below.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a mold according to an embodiment of the present invention will be described with reference to FIG. FIGS. 1A and 1B are diagrams showing a cross-sectional structure of a mold base material according to an embodiment of the present invention.
In each of the molds shown in (b), a layer 2 made of a material different from that of the mold base material 1 is formed on the transfer surface of the mold base material, and an aspherical surface is formed on the transfer surface of the mold base material. Are formed.

In the embodiment of the present invention, the material forming the base material 1 of the mold and the material forming the layer 2 formed on the transfer surface of the mold base material are given a predetermined strain. In this case, different plastic deformation materials are selected. As described above, the use of materials having different plastic deformation amounts with respect to strain allows the use of a spherical indenter.
Even if indentations are formed , a difference occurs between the amount of deformation in the base material 1 of the mold and the amount of deformation formed in the layer 2, so that the obtained indentations can form an aspherical shape.

FIG. 1A and FIG. 1B show the cross-sectional structure of the mold base material on which indentations are formed, respectively. The amount of deformation of the material s used for the base material 1 of the mold is equal to the material b formed of the layer 2.
Is used. Also, the mold base material illustrated in (b) uses the material s for the mold base material 1,
Further, the material b is formed in the layer 2. Further, as can be seen by comparing FIGS. 1A and 1B, the curvature of the formed indentation is different between the central portion and the peripheral portion. For example, in the case of FIG. 1A, when the curvature of the edge is compared with the curvature of the center, the curvature of the center is larger than the curvature of the edge, and FIG.
Has the opposite relationship. Thus, the shape of the indentation formed differs depending on the magnitude relationship of the amount of plastic deformation between the base material 1 and the layer 2 of the mold.

Next, the formation of the aspherical surface by the difference in the deformation amount will be described in detail. Please note that here
1 (a) will be described. FIG. 2 shows a stress σ-strain ε diagram of each material used in the embodiment of the present invention. The curve s is the material s
And the curve b is a stress σ-strain ε diagram of the material b. Further, the yield point of the material b is σeb, and the yield point of the material s is es. And material b
Selects a material that does not reach the yield point unless a strain greater than the material s is given.

In the embodiment of the present invention, an indenter having a spherical tip is used for a transfer surface of a mold base material having the structure shown in FIG. The mold blank is pressed to give greater strain. Then, a strain Q occurs in each of the base material 1 and the layer 2 of the mold. In addition, since the strain generated in the base material 1 and the layer 2 of the mold is formed by the same indenter,
Will be the same.

When the pressing by the indenter is stopped and the indenter is removed, the amount of plastic deformation occurring in each of the base material 1 and the layer 2 of the mold becomes ds and db shown in FIG. Like this
Since the strain at the yield point is different between each layer 2 and the substrate 1 with respect to the applied strain, the amount of plastic deformation formed between the layer 2 and the substrate 1 is different. Therefore, the central portion and the peripheral portion of the indentation have different spherical shapes.

In the mold shown in the embodiment of the present invention, the mold substrate 1 used for the mold base material is:
For example, a material having sufficient strength as a mold, such as a steel material such as tool steel or stainless steel, or a non-ferrous metal material such as copper alloy, aluminum, or aluminum alloy is used.
The layer 2 is formed on the substrate 1 of the mold by plating or coating.

The plating method may be chemical plating or electroplating, and the plating thickness is selected from a range of 1 to 50 micrometers. In addition,
Types of plating include nickel, nickel-phosphorus alloy, copper, chromium, gold, silver, and the like. For example, when quenched steel is used as a mold base material, if copper plating is applied to the surface of the transfer surface, the copper plating reaches the yield point with a strain smaller than that of the quenched steel. Indentations can be formed on the transfer surface of the mold base material.

When a layer of a different substance is formed on the surface of the mold base material by coating, a vacuum evaporation method such as an electron beam evaporation method, an ion assist evaporation method, a sputtering method, or an ion plating evaporation method is used. do it. As described above, in the embodiment of the present invention, an aspherical indentation can be obtained with a spherical indenter.

As the material of the indenter, a super hard material or diamond is usually used. It is very difficult to form an aspherical shape with such a material, and the reproducibility of the shape is poor.
However, if the mold described in the embodiment of the present invention is used, since a spherical indenter can be used, an aspherical indentation can be formed without using an aspherical indenter which is difficult to manufacture. .

In the embodiment of the present invention, a material having a large plastic deformation generated when the same strain is applied is used as the outermost layer or is applied to a layer adjacent to the outermost layer, so that the shape of the indentation is reduced. Can be changed. In addition,
In the mold shown in FIGS. 1 (a) and 1 (b), when the magnitude relationship of the amount of plastic deformation generated by the material used for the base material 1 and the layer 2 of the mold is changed, the shape of the indentation is different. Is shown. When a material having a large amount of plastic deformation is selected when the same strain is applied to the outermost layer, the shape of the indentation becomes the shape shown in FIG. 1A, and the opposite relationship is shown in FIG. The shape shown in FIG.

By the way, in a combination for obtaining a desired shape, a material which is soft and unsuitable for the molding surface is made of the layer 2.
In this case, the resulting shape is copied by applying nickel electroforming, electroless plating, or the like, and then inverted to obtain a mold suitable for the molding surface. In addition,
As described above, the layer 2 and the mold substrate 1 have different 2
Although the description has been given of the mold base material formed of various kinds of materials, the present invention is not limited to this. In addition, mold substrate 1
Alternatively, a mold base material in which a material different from either of the materials used for the layer 2 is provided between the mold base material 1 and the layer 2 may be used. In particular, as the mold, a mold having excellent strength is selected as the base material 1 of the mold, and a mold having excellent mold releasability as the layer 2 is preferable. When the materials are selected in this way, the mold base material 1 and the layer 2
In some cases, the difference in the magnitude of the strain at the yield point of the substance used may take a very small value. In such a case, a material whose strain at the yield point is significantly different from the strain at the yield point of the material applied to the layer 2 is selected, and the selected material is applied to the base material 1 and the outermost layer of the mold. What is necessary is just to form in layer form between the layer 2 formed. By doing so, the selection range of the material applied to the base material 1 of the mold and the layer 2 formed on the outermost layer is expanded, and the present invention can be easily implemented. Further, the number of layers and the thickness of the layers formed on the mold base material may be determined in consideration of the aspherical shape.

When a microlens array is manufactured using the mold base material obtained as described above, injection molding can be used. In this molding method, first, the surface of the mold base material on which the indentations are formed is used as a cavity surface to form a space through which the molten resin that is a material for the microlens array flows, and the molten resin is poured into the space and melted. Leave until the resin hardens. In this way, the aspherical shape formed on the transfer surface of the mold base material can be transferred to the material for the microlens array.

Incidentally, it is also possible to manufacture by applying compression molding by other methods. In this case, first, the material of the hardened microlens array is heated. Then, the mold base material having the aspherical shape formed on the heated material is pressed to transfer the aspherical shape. In this way, a microlens array having an aspherical shape may be manufactured.

[0030]

As described above, if the mold of the present invention is used,
Even if the tip of the indenter has a spherical shape, an indentation having an aspherical shape can be easily formed. Since the aspherical indentation can be formed with the spherical indenter in this manner, the cost of the indenter can be reduced. In addition, if the indenter has a spherical shape, the indenter can be formed with good reproducibility.
Even if the indenter is replaced, an aspherical indentation can be formed with good reproducibility.

[Brief description of the drawings]

FIG. 1 shows a configuration of a mold according to an embodiment of the present invention;
It is a figure showing the shape of the impression formed. (A) is a case where a material s having a large plastic deformation is used for the layer 2 and a material b having a small plastic deformation is used for the substrate 1 of the mold.
Is a case where a material b having a small plastic deformation is used for the layer 2 and a material s having a large plastic deformation is used for the substrate 1 of the mold.

FIG. 2: Stress σ of material s according to an embodiment of the present invention.
−Strain ε diagram and stress σ of material used for material b−
The correlation with the strain ε diagram is shown.

[Explanation of symbols]

 1 mold base material 2 layers σ stress σe elastic limit ε strain Q strain given by indenter

Claims (5)

[Claims] In a molding die formed on a transfer surface of a die, the shape of an indent obtained by pressing the indenter is such that the die has a plastic deformation amount with respect to a strain given by the indenter. Are formed of a plurality of different materials, and at least one of the plurality of materials is provided in a layer on the transfer surface. 2. A method for manufacturing a molding die, wherein a die having an aspherical indentation formed thereon by pressing an indenter onto a transfer surface of the die, wherein the die is subjected to a strain given by the indenter. A material having an amount of plastic deformation different from the amount of plastic deformation generated in the base material of the mold is provided in a layer on the transfer surface of the base material of the mold, by forming an indentation with a spherical indenter on the transfer surface, A method for manufacturing a molding die for forming an indentation having an aspherical shape. 3. A method of manufacturing a molding die for producing a die in which an aspherical indentation is formed by pressing an indenter onto a transfer surface of the die, wherein a material different from the base material of the die is provided. Is formed in a layer on the transfer surface of the substrate of the mold to form a first layer, and further has a plastic deformation amount different from the plastic deformation amount generated in the first layer with respect to the strain given by the indenter. Materials,
Forming a second layer on the surface of the first layer in a layered manner, and forming an indentation with a spherical indenter on the transfer surface on which the first layer and the second layer are formed, thereby forming an aspherical surface. A method for producing a molding die for forming an indentation having: 4. A method for forming a microlens having an aspherical shape, the method comprising the steps of: providing a mold base having a transfer surface for transferring an aspherical lens shape to a material forming an optical element; A material which causes a plastic deformation different from the amount of plastic deformation generated in the mold base material is provided in a layer shape on a transfer surface of the mold base material, and an indent is formed on the transfer surface with a spherical indenter; A method of forming a microlens having an aspherical shape on a material for forming the optical element by transferring a shape including the indentation to a material for forming the microlens. 5. A method for forming a microlens having an aspherical shape, wherein a mold base material having a transfer surface for transferring an aspherical lens shape to a material for forming an optical element includes: A first layer is formed on the transfer surface by using a different material to form a first layer. For the same strain further applied to the surface of the first layer, a plastic deformation amount different from the amount of plastic deformation generated in the first layer is formed. A material causing deformation is provided in layers on the transfer surface of the base material of the mold to form a second layer, and the first layer and the second layer are formed on the transfer surface by an indenter having a spherical shape. Forming an aspherical microlens on the material forming the optical element by transferring the shape of the indentation to the material forming the optical element. .