JP2000344533A - Production of optical element blank and apparatus for production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing optical element blanks which does not require the installation of many and diversified equipment for the manufacture of glass wires, is high in the weight accuracy of the optical element blanks and allows automation. SOLUTION: A bundle of glass rod materials 1 is formed as a glass wire 2. This glass wire 2 is held by a holding jig 6 and the position of the glass wire 2 is regulated in a vertical direction by a drive section 5. The bottom end of the glass wire 2 is put into a tubular furnace 7 and is heated. When the bottom end of the glass wire 2 is melted, a glass liquid drop 3 is formed. The shape and weight of the glass liquid drop 3 are determined by the surface tension of the glass and the external shape of the glass wire. The glass liquid drop 3 is dropped and is received in the form of spherical glass by a receiving tray 8. This spherical glass is used as the optical element blank 4. Also, a series of the stages from the manufacture of the glass rod materials 1 to the glass liquid drop 3 are automated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an optical element material used for a pickup optical system and a camera lens of an optical disk device, and more particularly to a method for forming a small glass lens and an apparatus for manufacturing the same. Things.

[0002]

2. Description of the Related Art Heretofore, as a method of manufacturing glass spheres as a material of an optical element, a method of obtaining glass spheres by thermal processing utilizing surface tension is known. This technology is disclosed in, for example, Japan Glass Products Industry Association: “Field Technology of Glass Manufacturing”, Vol. As one type of this manufacturing method, there is a technique disclosed in Japanese Patent Application Laid-Open No. 5-43258, which is referred to as a so-called fluidized firing method (processing by surface tension). This fluidized firing method is shown in FIG.
As shown in (1), the lower part of the glass rod 21 is locally heated by the heating device 22 to melt only the glass of the heated portion. Then, the tip of the glass rod 21 is made spherical, and a glass droplet 23 is formed. Next, the glass droplet 23 is allowed to fall naturally and collected by a collecting jig 24. Thus, the spherical glass 25 is obtained by the surface tension of the molten glass.

[0003] The mass m of the spherical glass 25 is obtained by using the above-mentioned known processing method using surface tension.
The relationship πrγ holds. Here, m is the mass of the glass droplet, g is the gravitational acceleration, 2πr is the outer peripheral length of the glass rod, and γ is the surface tension of the molten glass. Such a conventional technique depends on how to stabilize the physical properties of the glass, that is, the surface tension γ of the glass. In the manufacturing apparatus shown in FIG. 5, the glass rod 21 is
It is important to control the mass (hereinafter, referred to as weight) of the spherical glass 25 to a constant value. Further, by adjusting the wire diameter of the glass rod 21, the surface tension is adjusted to obtain a spherical glass 25 having a desired weight.

[0004]

As a conventional processing method for obtaining the glass rod 21, a method called a centering method or a heat processing method is generally used. However, each processing method has a limit in a shape that can be processed. The centering method is to machine by lathe or outer periphery polishing, etc., and is suitable for a glass rod 21 having a large diameter, but a thin glass rod 21 is easily broken by vibration or the like at the time of processing. In particular, it is not suitable for long ones. Further, even if processing is possible, there is a disadvantage that processing time is extremely long and processing cost is high.

On the other hand, in the thermal processing method, a molten glass is pulled up to produce a glass rod 21. However, contrary to the centering method, it is suitable for a thin or long one. However, this method takes a lot of processing time for thick objects,
Poor workability and large variation in diameter. In addition, in any of the processing methods, the finished wire diameter varies. Even if the temperature is controlled to a more precise melting temperature, the weight or shape of the spherical glass 25 varies.

On the other hand, when molding a high-precision glass lens, especially when the lens outer shape is finished to a predetermined shape simultaneously with molding, the weight accuracy of the spherical glass 25 becomes severe. For example, assuming that the molding volume of the lens mold of the design target is 100%, the allowable volume of the spherical glass is preferably 98% to 99% of the molding volume of the mold. Generally, the volume value of the spherical glass 25 is controlled by its weight value.

To ensure such weight accuracy, for example, when the weight of the spherical glass 25 is set to 100 mg or less, the roundness of the glass rod 21 needs to be set to several μm or less. Therefore, it is difficult to achieve such weight accuracy with the glass rod 21 manufactured with normal processing accuracy. It should be noted, however, that a small diameter obtained by the thermal processing method can achieve weight accuracy, but the required weight of the glass droplet is limited. Therefore, the processing means of the glass rod 21 differs depending on the desired weight. For this reason, a large number of processing equipment is required, and a dedicated machine is required, so that the entire equipment cost is increased. In the case of producing a stable and highly accurate spherical glass 25 with weight accuracy, the processing accuracy of the glass rod 21 is increased, and the equipment cost is further increased. Therefore, forming a glass lens using such a processing method is extremely expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In particular, a small glass lens can be molded with a desired weight accuracy, and an optical element material excellent in versatility can be obtained. It is an object to realize a manufacturing method and a manufacturing apparatus thereof.

[0009]

According to a first aspect of the present invention, an optical element member is formed by melting a glass wire while passing the glass wire through a tube furnace, and dropping and fixing glass droplets formed by the melting. In the method for producing the above, a bundle of glass rods is used as the glass wire.

According to a second aspect of the present invention, in the method for producing an optical element material according to the first aspect, the glass wire is formed by combining same or different-shaped glass rods.

The invention of claim 3 of the present application is directed to claim 1 or 2
In the method for producing an optical element material according to the above, the glass wire is obtained by bundling a plurality of glass fibers.

[0012] The invention according to claim 4 of the present application is characterized in that the glass material is melted and the melted glass material is shaped into a rod having a predetermined diameter, and the glass rod manufactured by the glass material manufacturing means. Bundling control means for bundling the material, processing means for fusing the glass rods bundled by the bundling control means to each other to form a glass wire, and holding and lowering a part of the glass wire processed by the processing means A driving means for heating, a heating means for heating and melting the lower end of the glass wire held by the driving means to form glass droplets, and dropping the glass droplets heated and melted by the heating means to form a falling glass ball. And a collecting means for collecting the water.

According to a fifth aspect of the present invention, in the apparatus for manufacturing an optical element material according to the fourth aspect, the bundling control means controls a bundling amount by a bundling weight of the glass rods. is there.

According to a sixth aspect of the present invention, in the optical element material manufacturing apparatus of the fourth aspect, the bundling control means controls the amount of bundling by the number of the glass rods to be bound. is there.

According to a seventh aspect of the present invention, in the apparatus for manufacturing an optical element material according to the fourth aspect, the bundling control means controls the amount of bundling based on the outer diameter of the glass wire bundled. is there.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing an optical element material and an apparatus for manufacturing the same in an embodiment will be described with reference to FIGS. (Embodiment 1) FIG. 1 is a sectional view of an essential part showing a method for manufacturing an optical element material and an apparatus for manufacturing the same in Embodiment 1 of the present invention. This manufacturing apparatus is an apparatus that manufactures an optical element material 4 by melting a glass wire 2 to form a glass droplet 3 and solidifying the glass droplet 3. Here, a bundle of glass rods 1 is used as a glass wire 2 to form a glass droplet 3. For this reason, the jig 6 is attached to the drive unit 5 which can move vertically.
Is attached, and the glass wire 2 is held by the jig 6. next,
The glass wire 2 is moved downward by the drive unit 5 and guided into the tubular furnace 7. Then, the lower end of the glass wire 2 is melted by heating to form a glass droplet 3. Eventually, the glass droplet 3 naturally falls on the tray 8. The material cooled in the tray 8 becomes the optical element material 4.

As the glass rod 1 used in the present embodiment, a glass fiber having good productivity and small variation in wire diameter was used. Glass fiber is φ0.1 (m
m) ± 0.001, L = 300 (mm). A glass wire 2 was obtained by bundling ten of these. The tubular furnace 7 was maintained at 1200 ° C., and the lowering speed of the glass wire 2 by the driving unit 5 was 140 mm / min. As a result of confirming the weight of n = 100 optical element materials 4 under these conditions, 52.5 mg ± 0.3%
Met.

As described above, according to the method of manufacturing the optical element material of the present embodiment, in lens molding, when the outer diameter is regulated at the same time as the molding, the weight variation required is ± 0.
Since it is within 5%, it can be said that it can be used sufficiently. As fine adjustment of the desired weight, a glass fiber having a smaller diameter, for example, φ0.05 (mm) ± 0.0
1. It has been confirmed that when L = 300, the variation in weight variation is further reduced. When the secondary processing is performed using such an optical element material 4, a highly accurate optical lens having a desired shape can be obtained without any variation. Further, the same or different shape glass fiber may be used in combination as the glass rod 1.

(Embodiment 2) Next, a method for manufacturing an optical element material and an apparatus for manufacturing the same according to Embodiment 2 of the present invention will be described with reference to FIGS. The manufacturing apparatus according to the present embodiment includes the manufacturing apparatus used in the first embodiment, and is an apparatus for manufacturing an optical element material in which a series of steps from the manufacturing of the glass rod 1 is continuously performed. Specifically, the means for producing the glass rod 1 shown in FIG. 2, the control means for controlling the amount of bundling a plurality of glass rods 1 as shown in FIG. 3, and the production of the glass rod 1 as shown in FIG. Processing means for bundling and processing the glass wire 2 is newly provided. The above-described manufacturing apparatus shown in FIG. 1 includes a driving unit that lowers the glass wire 2, a heating unit that melts the glass wire 2 into glass droplets 3, and collects the glass droplets 3. It can be said that it has a collecting means.

Here, the means for producing the glass rod 1 of FIG. 2 will be described. FIG. 2 is a cross-sectional view of a main part of a glass drawing apparatus which is a general construction method.
Used for the production of Put the glass material 9 in the crucible 10,
It is melted by the heater 11a. Then, the molten glass is applied to a roller 1 from a nozzle 12 provided below the crucible 10.
3 and cut into a predetermined length using a cutting jig 14. Thus, the glass bar 1 having a predetermined outer shape is manufactured.

In the control means for controlling the bundle amount shown in FIG. 3, the glass rods 1 produced by the producing means shown in FIG. Then, the weight that becomes the outer diameter of the required glass wire 2 is obtained in advance, and when the loaded weight becomes a desired weight, the plurality of glass rods 1 are collectively transferred to the next step.

The processing means shown in FIG. 4 performs processing for bundling the glass rods 1. As this processing method, the measured glass bar 1 is set in a cylindrical half processing jig 16. Heater 11b and pressure cylinder 17 provided on processing jig 16
By the operation described above, the glass bar 1 is not deformed and the glass bars 1 are welded together. Thus, a glass wire 2 having a predetermined diameter
Is prepared. The glass wire 2 manufactured here is supplied to the manufacturing apparatus shown in FIG. 1, and the optical element material 4 is manufactured by the method described in the first embodiment. Although the method of transporting the glass rod 1 and the glass wire 2 to each means is not shown, it is not particularly necessary to limit the method of transport between the means if there is no problem with each means.

As described above, according to the apparatus for manufacturing an optical element material of the present embodiment, a series of steps from the production of the glass rod 1 to the production of the optical element material 4 can be made unmanned and inexpensive. The optical element material 4 can be provided. The control means and the processing means for bundling the glass rods 1 do not necessarily have to be limited to the structure shown in the figure.
Either structure may be used.

[0024]

According to the manufacturing method of claims 1 to 3,
All you have to do is bundle the glass rods to the desired outer diameter,
The weight of the glass droplet can be controlled with high precision without requiring many different facilities. Also, various types of optical element materials can be manufactured using the same equipment.

Further, according to the manufacturing apparatus of claims 4 to 7,
Since the weight of the glass droplet can be finely adjusted, an optical element material controlled to a predetermined weight accuracy can be obtained.

In particular, according to the second aspect of the present invention, the glass rods can be realized in a combination of the same shape or a different shape.

In particular, according to the third aspect of the present invention, an optical element material controlled with even higher weight accuracy can be obtained by using a glass fiber which can be produced with high precision as a glass rod.

In particular, according to the fourth aspect of the present invention, a series of steps from the production of the glass rod to the means for collecting the glass droplets can be unmanned. Therefore, the optical element material can be manufactured at low cost.

In particular, according to the invention as set forth in claims 5 to 7, the bundle control means for controlling the amount of the glass rod material is controlled by controlling the weight to be bundled, the number of bundles, and the outer diameter of the glass wire bundle. The weight of the drops can be managed with high precision.

[Brief description of the drawings]

FIG. 1 is a fragmentary cross-sectional view showing a structure of an apparatus for producing an optical element material from a glass wire in a method for producing an optical element material according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of a means for manufacturing a glass rod in a method for manufacturing an optical element material according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part of a control unit for controlling the amount of glass bars bundled in the method for manufacturing an optical element material according to the second embodiment.

FIG. 4 is a cross-sectional view of a main part of a glass wire processing means in the method for manufacturing an optical element material according to the second embodiment.

FIG. 5 is a cross-sectional view of a main part showing a conventional method for manufacturing an optical element material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass rod material 2 Glass wire material 3 Glass droplet 4 Optical element material 5 Driving part 6 Holding jig 7 Tube furnace 8 Receiving tray 9 Glass material 10 Crucibles 11a, 11b Heater 12 Nozzle 13 Roller 14 Cutting jig 15 Metering 16 Processing jig Tool 17 Cylinder 21 Glass rod 22 Heating device 23 Glass droplet 24 Collection jig 25 Spherical glass

Continuing on the front page (72) Inventor Tomoaki Shimazaki 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A manufacturing method for manufacturing an optical element member by melting a glass wire while passing the glass wire through a tubular furnace, and dropping and fixing glass droplets formed by melting, wherein glass rods are bundled. A method for producing a material for an optical element, characterized in that the material is used as the glass wire. 2. The method for manufacturing an optical element material according to claim 1, wherein the glass wire is a combination of same or different-shaped glass rods. 3. The method according to claim 1, wherein the glass wire is a bundle of a plurality of glass fibers. 4. A glass rod producing means for melting a glass material and making the molten glass material into a rod having a predetermined diameter, and a bundling control means for bundling the glass rod produced by the glass rod producing means. Processing means for fusing the glass rods bundled by the bundle control means to each other to form a glass wire; driving means for holding and lowering a part of the glass wire processed by the processing means; Heating means for heating and melting the lower end portion of the glass wire held by the means, to form a glass droplet; and dropping the glass droplet heated and melted by the heating means,
An apparatus for manufacturing an optical element material, comprising: a collecting means for collecting falling glass balls. 5. The apparatus for manufacturing an optical element material according to claim 4, wherein said bundling control means controls a bundling amount by a bundling weight of said glass rods. 6. The optical element material manufacturing apparatus according to claim 4, wherein the bundling control means controls the amount of bundling by the number of the glass rods to be bundled. 7. The optical element material manufacturing apparatus according to claim 4, wherein the bundling control means controls a bundling amount based on an outer diameter of the glass wire bundle.