JP2001261350A - Method of producing optical element and mold for forming used for production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and inexpensively produce an optical element having good profile irregularity and a small eccentricity. SOLUTION: When forming an optical element by softening a glass raw material by heating and pressing the glass raw material with a pair of forming molds to form an optical element, one face of the glass raw material is formed into an optical functional surface 6a by aspheric surface of lower mold 2 of the pair of forming molds when the glass raw material is pressed and outer peripheral part 6b of the above optical element 6 is formed by cylindrical side 3a integrally provided coaxially to center axis of the optical functional face 6a in a fringe area part 6b of the above aspheric surface 2a and the optical element 6 is held based on the outer peripheral part 6b of the above optical element 6 and a forming face 6c of the optical element 6 press-formed by a forming surface 1a of the upper mold 1 is ground so as to have optical functional surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical element in which a glass material which has been heated and softened is pressed with a pair of molding dies to press and mold one surface of the optical element to an optical functional surface. The present invention relates to a method for manufacturing an optical element for post-processing the other surface of this optical element after molding, and a molding die used for the manufacturing.

[0002]

2. Description of the Related Art In recent years, an aspheric surface has been adopted as an optical function surface of an optical lens in various fields. As a method of forming an aspherical surface as an optical functional surface of a glass optical lens, there is a method of manufacturing by grinding and polishing, but it is not suitable for mass production because it requires time and cost, and is generally used for molding glass. It is made by pressing with a mold. In other words, strict precision is required for the optical function surface of the optical lens, and the glass material that has been heated and softened is pressed by a molding die having a precisely machined aspherical molding surface, and the shape of the molding surface is changed to the glass material. To obtain an optical element having a desired aspherical surface.

As a method of molding the optical element by pressing the heat-softened glass material, for example, Japanese Patent Laid-Open No.
-126232. In this molding method, a glass material is arranged in a space formed by a pair of molding dies and a body mold, and an optical functional surface of an optical element is formed by press molding of the glass material by the molding dies, and rotated. In order to center the outer peripheral surface of the optical element, the outer peripheral surface is formed in a barrel shape.

When the optical element is centered after the press molding, the optical element is taken out of the barrel mold, and FIG.
As shown in FIG. 5, the outer peripheral surface of the optical element 11 is inserted so as to contact the inner peripheral surface 12a of the positioning jig 12,
The optical function surface of the optical element 11 is sandwiched between a pair of holders 13 with the outer peripheral surface of the optical element 11 as a reference, and the optical axis of the optical element 11 and the central axis B of the holder 13 are held in alignment. Thereafter, as shown in FIG. 7 (B), the optical element 11 is taken out of the positioning jig 12, and the optical element 11 is held between the pair of holders 13, and the holder 13 and the center axis B are held together. By rotating the optical element 11 around and applying a grindstone 14 to its outer peripheral surface, the optical element 1
The outer peripheral surface of the optical element 11 is cut with a grindstone 14 to create a new outer peripheral surface of the optical element 11.

[0005]

Generally, optical lenses such as cameras and pickups have a small thickness and a small outside diameter.
The optical function surface is transferred according to the molding surface shape of the molding die and used as an optical element. However, in recent years, special lens shapes have been required due to the high performance of optical lenses and the versatility of fields of use, and there are cases where stable surface accuracy cannot be obtained depending on the shape of the lens by press molding using a molding die. is there. For example, even if a lens having a large outer diameter or a medium thickness is molded, the temperature unevenness of the glass is likely to occur, and the degree of shrinkage of the glass after the press molding is not uniform. Accuracy may not be obtained. In such a case, if it is forcibly attempted to ensure the surface accuracy of both surfaces of the lens by press molding, it takes time until the temperature of the glass becomes constant, and it takes a long time for the molding die to be exposed to a high temperature. The durability of the mold is rapidly deteriorated, and the production cost is increased.

In the method of molding an optical element disclosed in Japanese Patent Application Laid-Open No. 1-126232, the inner peripheral surface 12 of the positioning jig 12
Eccentricity between the central axis of a and the central axis B of the holder 13, for example, eccentricity due to backlash generated between the positioning jig 12 and the holder 13 due to clearance for ensuring relative sliding of the holder 13, and A processing error due to a variation in the shaving amount (feed amount) of the grindstone 14 at the time of centering is added, and by the time the outer periphery of the optical element 11 as a product is formed, the distance between the optical axis of the optical element 11 and the central axis of the outer peripheral surface is increased. An eccentricity error appears in the coaxiality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has a good surface accuracy and a method and a method for manufacturing an optical element capable of stably and inexpensively manufacturing an optical element having small eccentricity. It is an object of the present invention to provide a molding die for use in molding.

[0008]

According to a first aspect of the present invention, there is provided a method of manufacturing an optical element, comprising the steps of: heating and softening a glass material; In the method for manufacturing an optical element, the optical element is formed by pressing the glass material, at the time of pressing the glass material, one of the pair of molding dies and one of the two surfaces of the optical element is formed into an optical functional surface. At the same time, the outer peripheral portion of the optical element was formed.

According to a second aspect of the present invention, there is provided a method of manufacturing an optical element, comprising: after softening a glass material by heating, pressing the glass material with a pair of molding dies to form the optical element. In the manufacturing method, at the time of pressing the glass material, one of the pair of molding dies, one of the two surfaces of the optical element is formed into an optical functional surface, and the outer periphery of the optical element is formed. The optical element was held on the basis of the outer peripheral portion of the element, and the other surface of the optical element was ground and polished to an optically functional surface.

Further, according to a third aspect of the present invention, in the method for manufacturing an optical element according to the first or second aspect, the pressing of the optical functional surface and the outer peripheral surface of the optical element is performed by the optical element. A molding surface for molding the optical function surface of the optical element, and an outer edge of a molding surface for molding the optical function surface coaxially with a central axis of the optical function surface. In this case, a molding die integrally provided is used.

A molding die according to a fourth aspect of the present invention has a molding surface for molding an optically functional surface of an optical element and a cylindrical molding surface for molding an outer peripheral portion of the optical element. Is provided integrally with the outer edge of the molding surface for molding the optical function surface coaxially with the central axis of the optical function surface.

That is, in the method of manufacturing an optical element according to the first aspect of the present invention, one optical function surface and the outer peripheral portion of the optical element are simultaneously molded by one molding die, and the optical function surface is formed. An optical element having little eccentricity with the outer peripheral portion can be stably manufactured at low cost.

According to a second aspect of the present invention, there is provided a method for manufacturing an optical element, wherein one optical function surface and the outer peripheral portion of the optical element are simultaneously molded by one molding die, and thereafter the outer peripheral portion is formed. The other optical functional surface is ground and polished with reference to the portion, and an optical element with less eccentricity between the optical functional surfaces on both surfaces and the outer peripheral portion can be stably manufactured at low cost.

Further, in the method for manufacturing an optical element according to the third aspect of the present invention, the optical function surface and the outer peripheral portion of one of the optical elements are simultaneously formed, and the eccentricity between the optical functional surface and the outer peripheral portion is small. The element can be manufactured stably at low cost.

In the molding die according to a fourth aspect of the present invention, one optical function surface and the outer peripheral portion of the optical element are molded at the same time, and the eccentricity between the optical function surface and the outer peripheral portion is small. Can be manufactured stably at low cost.

[0016]

(Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 3 are schematic cross-sectional views showing a step of pressing and molding one optical function surface and an outer peripheral portion of the optical element. FIGS. 4 to 6 are secondary processing for forming the other optical function surface of the pressed optical element. It is an outline sectional view showing a process.

First, a molding die according to the present embodiment will be described with reference to FIG. 1. A lower die 2 as one of a pair of molding dies is connected to an upper die 1 as the other molding die. , Both types 2,
The lower mold 2 is movable up and down by a drive shaft (not shown) so that the molding surfaces 2a and 1a of the first mold 1 are vertically opposed to each other.

The lower mold 2 presses one surface of the glass material 4 to transfer an aspheric first optical function surface 6a (see FIG. 2) as an optical function surface of the optical element 6 (see FIG. 2). Concave surface 2a (hereinafter, referred to as an aspheric surface 2)
a) is provided inside the distal end side. Furthermore, at the tip of the lower mold 2, the center (center axis) of the cylindrical side surface 3a as a molding surface for molding the outer peripheral portion of the optical element 6 is made coaxial with the central axis A of the aspheric surface 2a, and the cylindrical side surface 3a is aspheric. The molded part 3 is provided integrally with the outer edge part 2b of 2a.
The cylindrical tip surface of the forming part 3 is flat,
Has the same size as the outer periphery of the lower mold 2 having the aspherical surface 2b. In the present embodiment, the diameter of the cylindrical side surface 3a of the forming portion 3 is φ40 mm, and the depth (the height from the outer edge 2b of the aspheric surface 2a to the plane of the forming portion 3) is 5 mm.
mm.

On the other hand, the upper mold 1 has a concave spherical molding surface 1a for press-molding the surface of the optical element 6 opposite to the first optical function surface 6a inside the front end side. A plane is formed between the outer edge 1b of 1a and the outer periphery of the upper die 1. In the present embodiment, the size of this plane is equal to or smaller than the size of the plane of the molded portion 3. Molding surface 1
“a” is formed into a spherical surface that forms a spherical shape with a radius of curvature r of 90 mm on the glass material 4.

The glass material 4 is formed on the molding surface 1 a of the upper mold 1.
And the respective surfaces 4 pressed by the aspherical surface 2a of the lower mold 2
a and the surface 4b are formed as curved surfaces slightly larger than the molding surface 1a and the aspheric surface 2a, respectively. In addition, glass material 4
Is formed in a volume larger than the volume of the desired optical element 8 (see FIG. 6), and is transported between the upper die 1 and the lower die 2 while being held by the transport arm 5 moved by a drive source (not shown). You.

The transfer arm 5 has a holding portion 5a formed of a through hole for holding the glass material 4 at the tip end. The holding portion 5a is composed of a lower small-diameter portion having a size that allows the lower die 2 to pass therethrough and an upper large-diameter portion larger than the outer diameter of the glass material 4, and the difference in diameter between the small-diameter portion and the large-diameter portion. The circular ridge of the step formed by the step supports the lower side near the outer periphery of the surface 4b of the glass material 4 and holds the surface 4a with the surface 4a facing up.

Next, a method for manufacturing an optical element using the upper and lower dies 1 and 2 having the above configuration will be described. First, the glass material 4 made of S-BSL 7 is supplied to the transfer arm 5 by a supply mechanism (not shown) in the transfer step and is held by the holding section 5a (see FIG. 1). Then, the glass material 4 is transferred together with the transfer arm 5 to a heating furnace (not shown), and the glass material 4 is heated and softened to a moldable temperature.

After the heating and softening of the glass material 4 is completed, as shown in FIG. 1, the glass material 4 is transported by the transport arm 5 between the upper mold 1 and the lower mold 2 which have been heated and kept in advance.
The central axis A through which the lower die 2 can be inserted through the small diameter portion of the holding portion 5a.
The glass material 4 is positioned at the upper molding position, and the conveyance is stopped.

Thereafter, the lower mold 2 is moved upward by a drive shaft (not shown), and the glass material 4 is lifted from the transfer arm 5 at the tip of the forming section 3 to approach the upper mold 1, and as shown in FIG. The glass material 4 is pressed and formed by the upper mold 1 and the lower mold 2 in a state where a predetermined interval is provided between the plane 1 and the plane of the forming section 3.

The optical element 6 (hereinafter, referred to as molded lens 6) molded in this molding step has a first optical function surface 6a, which is a transfer surface of the aspheric surface 2a of the lower mold 2, on the surface 4b of the glass material 4.
Is formed, and an outer peripheral portion 6b having a length of 5 mm, which is a transfer surface of the cylindrical side surface 3a having a height of 5 mm of the lower mold 2 and having a length of 5 mm, is connected to the first optical function surface 6a.
The first optical function surface 6a and the outer peripheral portion 6b are formed coaxially. On the other hand, the surface 4a of the glass material 4 is the molding surface 1 of the upper mold 1.
a forms a curved surface 6c (hereinafter, referred to as a forming surface 6c). Furthermore, the molded lens 6 is formed by the plane of the upper mold 1 and the plane of the molded portion 3 to form a circular flat portion 6d extending outward from the outer edge of the molded surface 6c and the outer edge of the outer peripheral portion 6b. Excess glass flows out between the two planes,
An outflow surplus glass portion 6e is formed outside the flat portion 6d.

After the molded lens 6 is cooled to a temperature at which the molded lens 6 can be released, the lower mold 2 is lowered, and as shown in FIG.
The outflow surplus glass portion 6e of the molded lens 6 is supported by the stepped portion, and the molded arm 6 is held by the transfer arm 5. Further, the lower mold 2 is lowered to be separated from the molded lens 6 and returned to the initial position.

Thereafter, the transport arm 5 transports the molded lens 6 to a molded lens unloading position (not shown), the molded lens 6 is removed from the transport arm 5, and the molding process is completed.

Next, the extracted molded lens 6-2
The next processing step will be described with reference to FIGS. As shown in FIG. 4, the outer peripheral portion 6 b having a height of 5 mm of the molded lens 6, which is the transfer surface of the cylindrical side surface 3 a of the lower die 2, is コ (approximately 3.3 mm) of the outer peripheral portion 6 c by the collet chuck 7. From the first optical function surface 6a side. That is, the remaining 1/3 of the outer peripheral portion 6b is removed from the tip of the collet chuck 7 by the flat portion 6d.
Then, as shown in FIG. 5, the molding surface 6c side of the molding lens 6 is ground by a cup-type grindstone 9 of a grinding device (not shown) as shown in FIG.

The molded lens 6 having a height of 5 mm
The outer peripheral portion 6b is ground to form a molding surface 6c so as to have a height of 4 mm.
e is also deleted to obtain a lens 8 having a ground shape that can have a ground surface 8a as shown in FIG. The outer peripheral portion 6b of the optical element 8 is a smooth side surface formed by press molding with the cylindrical side surface 3a of the lower mold 2, and is molded simultaneously with the press molding of the first optical function surface 6a by the aspheric surface 2a of the lower mold 2. The outer diameter of the finished lens. Further, the ground surface 8a is then processed into a lens surface (second optical functional surface) as an optical functional surface of the other surface through a polishing process, and a lens as a final finished product is completed.

According to the present embodiment, it is possible to manufacture a lens having good surface accuracy, and the outer peripheral portion 6b, which is the lens outer diameter, has the first optical function surface 6a formed by the aspheric surface 2a of the lower die 2. Simultaneously with the press forming, the eccentricity can be reduced because the cylindrical side surface 3a of the lower die 2 is formed by press forming coaxially with the first optical function surface 6a, so that the centering step can be omitted in the secondary processing.

In this embodiment, the glass material is S-BL
Although S7 was used, the present invention is not limited to this glass material, and the same operation and effect as in the present embodiment can be obtained for all glass materials. Further, the cylindrical side surface 3a of the lower mold 2 for press-molding the outer peripheral portion 6b serving as the outer diameter surface of the lens is not limited to the configuration parallel to the central axis of the aspheric surface 2a.
In the first embodiment, the tapered surface coaxial with the central axis
The same operation and effect as those described above can be obtained.

The technical idea having the following configuration is derived from the above-described specific embodiment. (Supplementary Note) (1) In the method for manufacturing an optical element, in which the glass material is heated and softened and then the glass material is pressed by a pair of molding dies to form an optical element, Optics characterized in that, on one side of a molding die, one of the two surfaces of the optical element is formed into an optical function surface, and an outer peripheral portion of the optical element is coaxial with a central axis of the optical function surface. Device manufacturing method.

(2) In the method of manufacturing an optical element, in which the glass material is heated and softened and then the glass material is pressed by a pair of molding dies to form an optical element. While molding one side of the optical element on the other side of the molding die into an optical functional surface,
After molding the outer peripheral portion of the optical element coaxial with the central axis of the optical function surface, holding the optical element with reference to the outer peripheral portion,
A method for manufacturing an optical element, comprising grinding and polishing the other surface of the optical element to an optically functional surface.

(3) One of the pair of molding dies has a molding surface for molding the optical function surface of the optical element, and has a tapered molding surface for molding the outer peripheral portion of the optical element. The method of manufacturing an optical element according to (1) or (2), wherein the optical function surface is formed coaxially with a central axis of the surface and integrally provided at an outer edge portion of the molding surface.

(4) After the glass material is heated and softened, the glass material is pressed to form an optical element. The molding die used for manufacturing the optical element has a molding surface for molding the optical functional surface of the optical element. And a tapered forming surface for forming the outer peripheral portion of the optical element is provided coaxially with a central axis of the optical function surface, and integrally with an outer edge of the forming surface for forming the optical function surface. A molding die used for manufacturing an optical element.

According to the method of manufacturing an optical element described in the appendix (1), one molding metal and one outer peripheral portion of the optical element are coaxial with the center axis and the outer peripheral portion of the optical functional surface. By molding simultaneously with a mold, an optical element with good dimensional accuracy and less eccentricity between the optical function surface and the outer peripheral portion can be stably manufactured at low cost.

According to the method of manufacturing an optical element described in Appendix (2), one molding metal is formed by making one optical functional surface and the outer peripheral portion of the optical element coaxial with the central axis and the outer peripheral portion of the optical functional surface. It can be obtained by simultaneously molding with a mold, and then grinding and polishing the other optical functional surface while holding the optical element with reference to the outer peripheral portion. This makes it possible to manufacture an optical element having good dimensional accuracy and low eccentricity between the optical function surfaces on both sides and the outer peripheral portion in a stable and inexpensive manner.

In the method for manufacturing an optical element according to the appendix (3), one of the optical function surfaces of the optical element and the tapered outer peripheral portion are simultaneously formed, so that the optical element has less eccentricity between the optical functional surface and the outer peripheral portion. Can be manufactured stably at low cost.

According to the molding die used in the manufacture of the optical element described in Appendix (4), one of the optical function surfaces of the optical element and the tapered outer peripheral portion are simultaneously molded, and the eccentricity between the optical functional surface and the outer peripheral portion is obtained. The optical element with less number can be stably manufactured at low cost.

[0040]

As described above, according to the first aspect of the present invention,
According to the method for manufacturing an optical element of the above, with one molding die,
One optical function surface and the outer peripheral portion of the optical element can be molded simultaneously. Thus, an optical element having good surface accuracy and less eccentricity between the optical function surface and the outer peripheral portion can be stably manufactured at low cost.

According to the method of manufacturing an optical element of the second aspect of the present invention, one optical function surface and the outer peripheral portion of the optical element are simultaneously molded by one molding die, and thereafter, the outer peripheral portion is formed. And the other optical function surface can be obtained by grinding and polishing while holding the optical element. This makes it possible to manufacture an optical element having good dimensional accuracy and low eccentricity between the optical function surfaces on both sides and the outer peripheral portion in a stable and inexpensive manner.

Further, according to the method for manufacturing an optical element of the third aspect of the present invention, one optical function surface and the outer peripheral portion of the optical element are made coaxial with the center axis and the outer peripheral portion of the optical function surface. By simultaneously molding with a molding die, it is possible to stably and inexpensively manufacture an optical element having good surface accuracy and less eccentricity between the optical function surface and the outer peripheral portion.

According to a fourth aspect of the present invention, there is provided a molding die used for manufacturing an optical element, wherein one of the optical functional surfaces and the outer peripheral portion of the optical element are molded at the same time, so that the optical function having good surface accuracy is obtained. An optical element having less eccentricity between the surface and the outer peripheral portion can be manufactured stably and inexpensively.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an optical element pressing molding step according to Embodiment 1 of the present invention, in a state where a glass material is transported between upper and lower dies.

FIG. 2 is a schematic cross-sectional view showing an optical element pressing molding step according to Embodiment 1 of the present invention, in a state where the glass material is being pressed by an upper and lower mold.

FIG. 3 is a schematic cross-sectional view showing an optical element pressing molding step according to the first embodiment of the present invention, in a state where the optical element that has been pressed is placed on a transport arm.

FIG. 4 is a schematic cross-sectional view showing a secondary processing step of the optical element according to the first embodiment of the present invention, in a state where the optical element that has been pressed is held;

FIG. 5 is a schematic cross-sectional view showing a secondary processing step of the optical element according to Embodiment 1 of the present invention, in which the pressed optical element is being ground.

FIG. 6 is a schematic cross-sectional view showing a secondary processing step of the optical element according to Embodiment 1 of the present invention, in which grinding processing has been completed.

FIG. 7 is a sectional view showing a centering state in a conventional example.

[Explanation of symbols]

 Reference Signs List 1 upper mold 1a molding surface 2 lower mold 2a aspherical surface (molding surface) 2b outer edge 3 molding portion 3a cylindrical side surface 4 glass material 6 molding lens 6a first optical function surface 6b outer peripheral portion 6c molding surface 7 collet chuck 8 lens 8a grinding Surface 9 Cup type whetstone

Claims (4)

[Claims] 1. A method of manufacturing an optical element, wherein a glass material is heated and softened, and then the glass material is pressed by a pair of molding dies to form an optical element. A method of manufacturing an optical element, comprising: molding one of two surfaces of the optical element into an optical functional surface and molding an outer peripheral portion of the optical element. 2. A method of manufacturing an optical element, wherein a glass material is heated and softened, and then the glass material is pressed by a pair of molding dies to form an optical element. On one side of the mold, one of the two surfaces of the optical element is molded into an optical functional surface and the outer peripheral portion of the optical element is molded, and then held on the basis of the outer peripheral portion of the optical element. A method for producing an optical element, characterized in that the other surface is ground and polished to an optical function surface. 3. One of the pair of molding dies has a molding surface for molding an optical function surface of an optical element, and has a cylindrical molding surface for molding an outer peripheral portion of the optical element. 3. The method for manufacturing an optical element according to claim 1, wherein the optical function surface is formed coaxially with the center axis of the optical element and integrally formed on an outer edge of the molding surface. 4. A molding die used for manufacturing an optical element for forming an optical element by pressing a glass material after heating and softening a glass material, comprising a molding surface for molding an optical functional surface of the optical element. ,And,
An optical element, wherein a cylindrical molding surface for molding the outer peripheral portion of the optical element is provided integrally with an outer edge of the molding surface for molding the optical function surface coaxially with a central axis of the optical function surface. Mold for molding used in manufacturing.