JP2003063835A - Mold for forming optical element and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mold for forming optical elements having highly precise optically functional part and good reference surfaces. SOLUTION: The heated and softened optical material (10') is sandwiched with a pair of the upper and the lower molds (2, 1) and heated and pressed to form an optical element (10). At least one of the upper and the lower molds (2, 1) are formed by arranging the heated and softened glass of the molding material (1') in a hole (31) of a body mold (3) and heating and pressing with a forming master block (4) to transfer the convex surface (4A) of the master block (4) to the molding material (1'), and to form the concave surface (1A) with the depth (a+α), which is added with a fixed quantity (α) of the depth to the depth (a) corresponding to the thickness of the desired optical element (10), and then cooling and solidification processing, taking the glass mold (1) out from the hole (31) of the body mold (3), polishing the circumferential upper surface of the transferred concave surface (1A) of the mold (1) to shave off the fixed thickness (α), and forming the transferred concave surface (1A) with the depth (a) corresponding to the thickness of the optical element (10).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass optical element molding die in an optical element molding die including a pair of upper and lower molding dies and a barrel die, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, optical materials (or glass materials)
After being softened by heating in a heating furnace, an optical material (or glass material) 10 'disposed in a cavity of a molding die including a body die 3 and a pair of upper and lower molding dies 1 and 2 is used as an upper die 2 and a lower die. 1
In a mold for molding an optical element for molding an optical element 10 (or a glass molded product) by pressing with at least one of a pair of upper and lower molding dies (upper mold 2, lower mold 1), a molding mold material 1 made of glass. A molding die molded in 'has come to be used (see FIG. 1).

For example, in a molding die for manufacturing an optical element such as an aspherical objective lens for an optical pickup, which is required to have a strict shape and surface quality, the molding surface has a high shape accuracy and no variation. Is required to be formed, and a forming die manufactured by grinding or polishing a hard metal member has a limit in a processed shape. On the other hand, the molding die made by pressing the glass molding die material with the molding die while heating it, and transferring the molding die to the molding die material has a free shape of the transfer surface. The degree is wide and there is no variation. Techniques for producing such a molding die by glass molding are known from JP-A-2-267129 and JP-A-64-33022.

FIG. 2 shows a molding die for molding the molding die 1 with a molding die material 1'made of glass. In the prior art, the molding die 4 is pressed to the depth (a) corresponding to the desired thickness of the optical element while heating the molding die material 1 ′ made of heat-softened glass, and the molding die material 1 By transferring the transfer convex surface 4A of the molding mother die 4 to 1 '(press molding), the molding die 1 having the transfer concave surface 1A of depth (a) was molded.

[0005]

FIG. 5 (a) shows a molding die 1 molded by a conventional manufacturing method. When the molding die 1 is molded by the molding die molding die shown in FIG. 2, by transferring the transfer convex surface 4A of the molding mother die 4 to the molding die material 1'made of glass, the transfer concave surface 1A with high shape accuracy is obtained. The formed mold 1 is formed. However, since the transfer concave surface 1A is formed by pressing the molding mother die 4, the material 1 for the molding die present in the concave portion is formed.
′ Is pushed up and rises, and a surplus thickness 1B is formed on the peripheral upper surface of the transfer concave surface 1A. That is, the molding die 1 molded by the conventional technique has the transfer concave surface 1A with high shape accuracy,
The extra thickness 1B formed on the peripheral upper surface thereof.

FIG. 5B shows an optical element 10 molded by a molding die of an optical element having a molding die (see FIG. 5A) manufactured by a conventional technique as a lower die 1. is there. The optical element 10 formed by using the lower mold 1 having the transfer concave surface 1A having a high shape accuracy has a highly accurate optical function portion 10A. However, the surplus 1B formed on the peripheral upper surface of the transfer concave surface 1A causes surface sag in the periphery 10B of the optical function portion, and forms the optical element 10 in which the lens collar has a depression. When the optical element 10 is attached to a lens barrel or the like, the lens collar serves as a reference surface for the lens barrel. Therefore, a sag occurs around the optical function part 10B,
When the optical element 10 in which the lens collar has a depression is attached to a lens barrel or the like, the stability of the optical element 10 with respect to the lens barrel is poor and a problem occurs. Further, since the lens collar has a depression, the lens collar cannot be made thin, and it is necessary to form the lens collar thicker in consideration of the depression.

Therefore, according to the present invention, a highly accurate optical function unit 1 is provided.
In order to mold an optical element having 0A, a molding die in which the shape accuracy of the transfer concave surface is high and there is no variation is provided, and sagging of the surface around the optical function part 10B of the molded optical element is prevented. Provided is a method of manufacturing a mold for forming an optical element having a reference surface formed in a flat shape by forming a lens collar with a constant thickness.

[0008]

To achieve the above object, according to the present invention, an optical element is molded by sandwiching a heat-softened optical material with a pair of upper and lower molds and applying pressure while heating. At least one of the pair of upper and lower molds of the optical element molding mold is provided with a molding mold material made of heat-softened glass in the hole of the body mold and pressed by the molding mother mold while heating. By doing so, after transferring the transfer convex surface of the molding die to the molding material, after forming the transfer concave surface of the depth (a + α) obtained by adding a certain amount of depth to the depth corresponding to the thickness of the desired optical element. The process of cooling and solidifying, taking out the glass mold that has been molded in the holes of the barrel mold, polishing the peripheral upper surface of the transfer concave surface of the mold to scrape a certain amount of thickness (α), and make it as desired Of depth (a) corresponding to the thickness of the optical element And a step of forming a transfer concave surface.

A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an optical element molding die including a molding die (lower die 1) molded from a glass molding die material 1 '. FIG. 1 shows a cross-sectional view of an optical element molding die provided with a glass lower die 1, which is located on the transfer concave surface 1A of the glass lower die 1 arranged in the hole 31 of the body die 3. Optical material (or glass material) softened by heating to 10
′ Is placed, the upper mold 2 which moves up and down while sliding in the hole 31 of the body mold 3 is lowered, and the lower mold 1 and the upper mold 2 are heated while heating the optical material (or glass material) 10 ′. The transfer concave surface 1A of the lower mold 1 and the transfer concave surface 2A of the upper mold 2 are transferred to the optical material (or glass material) 10 'by sandwiching them with each other, and then the transfer concave surface 1A is heated and pressed.
The optical material (or the glass material) on which 2A and 2A are transferred is cooled to mold the optical element (or the glass molded product) 10. The optical element molding die shown in FIG.
A lower mold 1 formed of a glass molding material 1 ',
An upper mold 2 made of cemented carbide is provided, and the upper mold 2 is also made of glass by the same manufacturing method as that of the lower mold 1.
You may form with.

A method for manufacturing the lower mold (molding mold) 1 made of glass will be described below. FIG. 2 is a cross-sectional view of a molding die for molding a glass lower die 1 in the optical element molding die shown in FIG. 1, and is composed of a body die 3 and a molding mother die 4. To be done. In this embodiment, the lower mold 1 having the transfer concave surface 1A of depth (a + α) is molded by the molding mold.

As shown in FIG. 2, a mold material 1'made of heat-softened glass is placed in the hole 31 of the body mold 3,
The molding die 4 that moves up and down while sliding in the hole 31 of the body die 3 is lowered, and the molding die material 1 ′ made of glass is press-molded by the molding die 4 while being heated. 1
After the transfer convex surface 4A of the molding die 4 is transferred to the molding die 4, the molding die material 1'to which the transfer convex surface 4A has been transferred is cooled by heating and pressing, and the lower mold 1 having the transfer concave surface 1A is molded. The forming die shown in FIG. 2 uses a forming mother die 4 made of cemented carbide. Further, when the molding master die 4 is pressed to transfer the transfer convex surface 4A, a depth (a + α) of a depth (a) corresponding to a desired thickness of the optical element 10 and a certain depth (α) is added. The transfer concave surface 1A is formed.

FIG. 3 shows a lower mold 1 molded by the molding mold shown in FIG. By pressing the molding mother die 4 against the molding die material 1 ′ made of glass while heating and transferring the transfer convex surface 4 A, the depth (a +
The transfer concave surface 1A of α) is formed. Further, when the molding mother die 4 is pressed while being heated, the molding die material 1'is pushed up to the periphery to form the concave portion of the transfer concave surface 1A, so that the material 1'is formed on the upper surface around the transfer concave surface 1A. The extra meat 1
B is formed.

Therefore, in this embodiment, after the lower mold 1 made of glass on which the transfer concave surface 1A of depth (a + α) and the surplus thickness 1B are formed is cooled and solidified, the hole of the body mold 3 of the molding mold is formed. The lower mold 1 made of glass molded in 31 is taken out, the peripheral upper surface of the transfer concave surface 1A of the lower mold 1 is subjected to polishing processing, and ground into a flat shape with a certain thickness (α). That is, by polishing the upper surface of the lower die 1 (upper peripheral surface of the transfer concave surface 1A), the extra thickness 1B formed on the upper peripheral surface of the transfer concave surface 1A is removed. The transfer concave surface 1A having the depth (a) is formed by shaving the peripheral upper surface of the transfer concave surface 1A having the depth (a + α) into a flat shape with a certain thickness (α).

FIG. 4 (a) shows the lower mold 1 that has been polished, and the transfer concave surface 1A having the depth (a + α) shown in FIG.
With respect to the lower mold 1 in which the surplus thickness 1B is formed, a desired optical element is formed by polishing the thickness (α) parallel to the bottom surface of the lower mold 1 and planarly from the upper surface of the lower mold 1. A lower mold 1 having a transfer concave surface 1A having a depth (a) corresponding to the thickness of 10 and having a surplus thickness 1B on the upper surface surrounding the transfer concave surface 1A is formed.

In other words, in this embodiment, the transfer convex surface 4A is transferred to the molding die material 1'made of heat-softened glass by pressing the molding mother die 4 while heating it, thereby forming the transfer concave surface 1A with high shape accuracy. While molding the lower mold 1 that has,
After the lower mold 1 is cooled and solidified, the peripheral upper surface of the transfer concave surface 1A is polished to remove the extra thickness 1B formed when the transfer concave surface 1A is formed. Then, the lower mold 1 is attached to the hole 31 of the body mold 3.
By molding the optical element 10 with the optical element molding die disposed inside, the transfer concave surface 1A with strict shape accuracy is formed.
The optical element 10 that has a high-precision optical function portion 10A by being transferred, and has a good reference surface without causing surface sagging of the optical function portion periphery 10B, depression of the lens collar, or the like. The lens brim can be designed thin. (See Fig. 4 (b))

According to this embodiment, the optical element molding die (FIG. 1) is the same as the barrel die 3 used in the molding die molding die (FIG. 2) for molding the glass lower die 1. Are using. The body mold 3 includes a first member 3A having a hole 31, and
It is composed of a second member 3B which closes the lower opening of the hole 31 and supports the lower mold 1 arranged in the hole 31. The lower mold 1 molded in the hole 31 of the molding mold of FIG.
Can be easily taken out by separating the first member 3A and the second member 3B, and the lower die 1 taken out is installed in the hole 31 of the body die 3 again after polishing.

Further, the body mold 3 (the first member 3A and the second member 3
B) is made of cemented carbide, and a heating means such as an electric furnace is provided outside the barrel die 3. When the lower mold 1 is molded by the body mold 3 equipped with a heating means, this heat is applied to the mold material 1.
In addition to the above, the molding die 4 is press-molded in a softened state of the molding die material 1 ', and the glass lower die 1 having the transfer concave surface 1A with high shape accuracy is formed. Further, when the optical element 10 is molded, this heat is applied to the optical material 10 '.
In addition to the above, the upper and lower molds 1 and 2 with the optical material 10 'softened
Then, the transfer concave surfaces 1A and 2A having a high shape accuracy are transferred, and the optical element 10 having the highly accurate optical function part 10A is molded.

In this embodiment, the upper die 2 and the body die 3 for molding the optical element shown in FIG. 1 and the forming mother die 4 and the body die 3 of the molding die shown in FIG. Although the one formed of 1. was used, one formed of ceramics may be used instead of cemented carbide.

That is, in this embodiment, the transfer convex surface 4A of the molding die 4 is transferred to the molding die material 1'made of glass arranged in the hole 31 of the body die 3 and the transfer concave surface 1 having a high shape accuracy is formed.
After forming A, it is cooled and solidified, and the lower mold 1 made of glass is molded in the hole 31 of the barrel mold 3 (FIG. 2).
The first member 3A and the second member 3B are separated from each other, the lower mold 1 made of glass molded in the hole 31 is taken out, and further, the lower mold 1 made of glass is subjected to polishing processing to form a concave transfer surface. The extra thickness 1B formed on the upper surface around the transfer concave surface 1A is removed (FIGS. 3 and 4). Then, the lower mold 1 having the transfer concave surface 1A with high shape accuracy and having the excess thickness 1B removed
Is again placed in the hole 31 of the barrel die 3, the optical material 10 'is placed on the transfer concave surface 1A of the lower die 1 made of glass, and the upper die 2 having the transfer concave surface 2A is slid in the hole 31. As shown in FIG. 4B, the optical element 10 'is pressed to form the optical element (or glass molded article) 10 on which the transfer concave surfaces 1A and 2A are transferred (FIG. 1). , Without forming a chamfer on the periphery 10B of the optical function part,
It is possible to provide an optical element having a good reference surface.

That is, according to the present invention, the heat-softened optical material is placed in the cavity of the optical element molding die including the pair of upper and lower molding dies and the barrel die, and the optical element is pressed by the pair of upper and lower molding dies. For at least one of the pair of upper and lower molds of the optical element molding mold for molding,
The molding mother die is pressed against the molding die material made of heat-softened glass to mold a molding die having a transfer concave surface with high shape accuracy, and the peripheral upper surface of the transfer concave surface of this molding die is polished to be flat. This removes the extra thickness 1B formed on the upper surface around the transfer concave surface when the transfer concave surface is formed. By molding the optical element with the optical element molding die including the above-mentioned molding die, an optical element having a highly accurate optical function portion and a good reference surface can be molded.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold for molding an optical element.

FIG. 2 is a cross-sectional view of a molding die.

FIG. 3 is a sectional view of a molding die molded by the molding die of FIG.

FIG. 4 shows a mold after polishing and an optical element molded by the mold.

FIG. 5 is a molding die according to the related art and an optical element molded by the molding die.

[Explanation of symbols]

1 Lower mold 1A Transfer concave surface 1B extra meat 1'Molding material 2 Upper mold 2A Transfer concave surface 3 body type 31 holes 4 Molding mold 4A Transfer convex surface 10 Optical element 10A Optical function part 10B Optical function area 10 'Optical material (or glass material)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 3/00 G02B 3/00 Z

Claims (2)

[Claims] 1. An optical element molding die for molding an optical element (10) by sandwiching a heat-softened optical material (10 ') between a pair of upper and lower molding dies (1, 2) and applying pressure while heating. In at least one of the pair of upper and lower molds (1, 2), a mold material (1 ') made of heat-softened glass is placed in the hole (31) of the body mold (3). By pressing with the molding mother die (4) while heating, the transfer convex surface (4A) of the molding mother die (4) is transferred to the molding die material (1 ′), and the desired optical element (10) is formed. After forming a transfer concave surface (1A) having a depth (a + α) obtained by adding a certain amount of depth to the depth corresponding to the thickness, the step of cooling and solidifying, and molding in the hole (31) of the barrel die (3) Take out the glass mold (1) and polish the upper surface around the transfer concave surface (1A) of the mold (1). Scraped off a certain amount of thickness (α) and Engineering,
An optical element molding die, which is formed by a step of forming a transfer concave surface (1A) having a depth (a) corresponding to a desired thickness of the optical element (10). 2. An optical element molding die for molding an optical element (10) by sandwiching a heat-softened optical material (10 ′) between a pair of upper and lower molding dies (1 and 2) and applying pressure while heating. At least one of the pair of upper and lower molds (1, 2) is provided with a mold material (1 ') made of heat-softened glass in the hole (31) of the body mold (3). By pressing with the molding mother die (4) while heating, the transfer convex surface (4A) of the molding mother die (4) is transferred to the molding die material (1 ′), and the desired optical element (10) is formed. After forming a transfer concave surface (1A) having a depth (a + α) obtained by adding a certain amount of depth to the depth corresponding to the thickness, the step of cooling and solidifying, and molding in the hole (31) of the barrel die (3) Take out the glass mold (1) and polish the upper surface around the transfer concave surface (1A) of the mold (1). A certain amount of thickness a (alpha) scraping,
And a step of forming a transfer concave surface (1A) having a depth (a) corresponding to a desired thickness of the optical element (10).