JPH092827A - Production of glass lens - Google Patents

Abstract

PURPOSE: To provide a method for producing a glass lens aiming at the prevention of a melt adhesion to a forming surface, a cloudiness and a crack by press forming a material for glass lens forming on which surface where a functional surface is formed, a thin membrane having a peeling off function is formed, after removing the part where the thin membrane is not formed before the press forming. CONSTITUTION: This method for producing a glass lens is constituted by forming a thin membrane material having 10-1000Å thickness and a peeling off function on the surface of a material for glass lens forming prefabricated to the shape approximately resembling to a finished shape. At that time, since a peripheral part for supporting the forming material must be held in the membrane forming device, a non-membrane-coated part where no membrane is formed at the peripheral held part, is produced. After removing this part where no membrane is formed, by grinding to get rid of the part where the material for forming and the surface of the die directly come into contact with each other, the press forming is performed and the melt adhesion to the surface of the die on the surface of the material for the forming, etc., are totally prevented.

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 a glass lens which does not require precision polishing after pressure molding. More specifically, in pressure molding of optical elements such as lenses,
The present invention relates to a method capable of preventing fusion between a glass lens molding material and a mold surface and producing a good glass lens free from fogging and cracks.

[0002]

2. Description of the Related Art The reheat press method has attracted attention as a method for easily molding an optical element such as a lens with high productivity. The reheat press method is a method in which a glass material that has been approximated by melting and solidifying it into a desired glass lens shape in advance is put into a molding die, and the inside of the mold is heated, where the glass material becomes a moldable state. Press this and cool it while the molded glass lens is held in the mold,
This is a method of molding a glass lens.

However, when a glass lens is molded by such a pressure molding method, the glass lens molding material and the surface of the mold for pressure molding the glass lens are in contact with each other at a high temperature for a relatively long period of time. In these respects, alteration and / or fusion due to reaction or heat (hereinafter referred to as fusion, etc.)
Occurred, and the glass lens surface was cracked or fogged, and a good optical lens could not be obtained.

In order to prevent such fusion, etc.
JP-A-53260 discloses a method in which a thin film having a releasing function is provided on a surface of a glass lens molding material on which a functional surface is molded, prior to pressure molding, and the thin film is removed after molding.

Further, Japanese Patent Publication No. 62-50413 discloses a thin film which has a releasing function on the surface on which the functional surface of the glass lens molding material is molded and which can constitute an antireflection film which does not need to be removed. A molding method provided prior to the pressure molding is disclosed.

However, in any case, since a vacuum deposition method, an ion plating method, a sputtering method, or the like is used as a method for forming a thin film on a material for forming a glass lens, it is attempted to efficiently produce a glass lens. In such a case, due to the relationship with the holder that supports the forming material in the apparatus in these film forming methods, the portion of the surface of the forming material that overlaps the holder, that is, the thin film is not formed. Occurrence of a portion (hereinafter referred to as a non-film formation portion) cannot be avoided.

Therefore, during pressure molding, the non-film-forming portion of the outer peripheral portion of the surface of the molding material comes into direct contact with the mold surface to cause fusion and the like, and a glass lens of good quality without cracking or fogging. Couldn't get

Further, in order to eliminate the non-film-forming portion as much as possible, the surrounding of the vapor deposition material is used during the film formation by the ion plating method, the holder is complicatedly rotated during the film formation, and the thickness of the molding material is increased. Although an attempt has been made to hold only by the end face due to the above, in any case, the cost increased and the mass productivity was poor.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in the pressure molding of a glass lens, the fusion of the glass lens molding material and the mold surface, etc. is performed on the entire surface of the molding material. It is an object of the present invention to provide a method for producing a good glass lens which is free from fogging and cracks.

[0010]

According to the present invention, a glass lens molding material having a thin film having a releasing function formed on a surface on which a functional surface is formed is removed from a non-film forming portion prior to pressure molding. After that, the present invention relates to a method for manufacturing a glass lens, which comprises performing pressure molding.

The glass material used in the present invention is not particularly limited, and is usually used as a raw material for glass lenses, for example, heavy flint glass, borosilicate crown glass, flint glass, titanium-containing flint glass, lanthanum flint glass, Although an optical glass such as a lanthanum-based crown glass can be used, the present invention is particularly effective for a glass that easily undergoes alteration or fusion, a glass having a high transition temperature, and the like.

In the present invention, the basic shape that allows the glass material to be formed into a desired finished shape by subsequent pressure molding, for example, when the finished shape is a concave or convex lens, the volume is almost equal to that of the lens. It is preformed into a disk shape, a column shape, a spherical shape, or a spherical shape, preferably a shape that is approximately similar to the finished shape, and used as a glass lens molding material.

Further, in the present invention, a thin film having a releasing function is formed on the preformed glass lens molding material as in the conventional case, and fusion or the like during the subsequent pressure molding is prevented.

The material of the thin film having the releasing function of the present invention is chemically stable, does not cause fusion with the surface of the molding die, and does not cause peeling when removing the non-film-forming portion. It is not particularly limited as long as it has a degree of strength and adhesiveness with the preform, for example, magnesium fluoride, calcium fluoride, cerium fluoride, cerium oxide, aluminum oxide, yttrium oxide, titanium oxide, lanthanum oxide, Carbon, gold, platinum, silver, chrome, copper or the like can be used.

In order to form a thin film of these materials on the surface of the preformed glass lens molding material made of the above-mentioned glass material, a vacuum deposition method, an ion plating method, a sputtering method or the like is usually used. The method used for forming can be used. Although the film thickness of the thin film varies depending on the film material, in general, a release effect of preventing fusion between the molding material and the mold surface can be sufficiently obtained in a wide range of about 10 to 1000Å. An appropriate film thickness can be selected in consideration of the film method and the use of the glass lens obtained by molding. Preferably 10-500
Å, more preferably 20 to 300 Å. When the film thickness is less than 10Å, the releasing effect cannot be obtained, and 1
When it exceeds 000Å, the thin film cannot withstand the deformation of the molding material during pressure molding, and cracks occur.

When a thin film is formed on the glass lens molding material by such a method, the outer peripheral portion of the molding material overlaps with the holding portion that supports it in the film forming apparatus. A part where the thin film is not formed (non-film forming part) occurs in the outer peripheral part.

Specifically, for example, when a thin film is formed on the glass lens molding material (1) by a vacuum vapor deposition method using the apparatus shown in FIG. 3, a holding device installed in the vacuum chamber (9) is used. The tool (8) supports the molding material (1),
The thin film material (10) evaporated from the evaporation board (11) is vapor-deposited on the molding material (1). However, the holding material (8) is provided at the outer peripheral portion so that the molding material (1) does not fall.
Since it is supported by, the portion of the surface of the molding material (1) that is in contact with the holder (8) cannot contact the evaporated thin film material component, and the thin film is not formed. For this reason,
A non-film-forming portion occurs on the outer peripheral portion of the molding material.

In FIG. 1B, when the thin film (2) is formed on the glass lens molding material (1) by such a conventional film forming method, the outer peripheral portion of the molding material is held as described above. A glass lens molding material (5) having a non-film-forming portion (4) formed on the outer peripheral portion thereof due to contact with a tool and contact with a thin film material is exemplified.

Even if a thin film having a releasing function is formed on a glass lens molding material in order to prevent fusion or the like at the time of pressure molding, if the film formation on the outer peripheral portion is insufficient, Since the molding material and the mold surface are in direct contact with each other in the outer peripheral portion, fusion or the like occurs between them, and the glass lens surface is cracked or clouded, so that a good glass lens cannot be obtained.

Therefore, according to the present invention, in the glass lens molding material having the non-film-forming portion on which the thin film is formed by the above-mentioned conventional method, the non-forming of the outer peripheral portion where the thin film is not formed prior to the pressure molding. By removing the film part and eliminating the part where the molding material and the mold surface are in direct contact,
The fusion of the surface of the molding material with the surface of the mold is prevented over the entire surface.

The removing method is not particularly limited as long as the non-film-forming portion is removed, but grinding with a grindstone such as diamond or hard ceramic is effective.

For example, in the case of grinding removal with a diamond grindstone, as shown in FIG. 2, a glass lens molding material (5) having an outer peripheral portion where the thin film (2) is not formed, that is, a non-film forming portion (4) is used. Hold by the holding jig (7),
The non-film-forming portion is ground from the outermost side with a diamond grindstone (6). By rotating the jig, the outer periphery of the molding material can be effectively ground. Even if the vertical cross-sectional shape of the molding material in the thickness direction is not circular or the non-film-forming portion is not donut-shaped, the pressing jig (7)
The non-film-forming portion can be removed by grinding by rotating without rotating, and by operating in a linear, curved, or motion that matches the shape of the forming material or the shape of the non-film-forming portion. However, since the vertical cross-sectional shape in the thickness direction of the preformed molding material is usually circular, the shape of the non-film-forming portion of the glass lens molding material formed by the conventional film-forming method is a donut shape. Since it has a shape, the jig can be rotated for efficient grinding.

As shown in FIG. 1A, the glass lens molding material (3) from which the non-film-forming portion has been removed by such means has a thin film (2) formed on the entire surface on which the functional surface is molded in the molding material. )have. In this way, the entire surface of the molding material that contacts the mold surface is uniformly covered with the thin film having a mold release function, so that even during pressure molding, the fusion between the molding material and the mold surface occurs. Etc. does not occur and a good glass lens can be obtained.

The glass lens molding material from which the non-film-forming portion has been removed as described above is pressure-molded by the reheat press method to obtain an optical lens having a desired functional surface (spherical surface, aspherical surface, etc.). it can.

Specifically, when the molding material is molded by a reheat press method into, for example, a biconcave spherical glass lens, the pressure molding device shown in FIG. 5 is used.

The apparatus has an upper mold (15) having a mold surface that is precision mirror-finished into a convex spherical surface and a holding mold (21) for holding it, and a mold surface that is also precision-machined into a convex spherical shape. Lower mold (16) and holding mold (2
2) and are provided. By the push rod (17), the holding die (21) moves downward together with the upper die (15),
Mates with a holding mold (22) that is integral with the lower mold (16). The above mold structure is heated by the heating light source (19) installed on the outer periphery of the transparent quartz tube (18), and the temperature is measured by the thermocouple (20) buried in the holding mold (22) to obtain the temperature. Controlled.

The glass lens molding material (3) from which the non-film-forming portion is removed is placed in the upper and lower molds (15, 16),
In a nitrogen or argon atmosphere, the heating light source (1
9) upper mold, lower mold (15, 16) and holding mold (2)
1, 22) and the molding material (3) are heated to a softened state, the push rod (17) is lowered, and a load is applied to the upper die (15) and the holding die (21) holding it. Press forming. The molding pressure may be a pressure sufficient to transfer the surface shape of the mold to the preform.

Next, the pressure of the push rod (17) is removed,
The pressure-formed product is cooled while being surrounded in the mold (15, 16, 21, 22), and then the pressure-formed product is taken out.

No fusion was observed between the obtained lens and the mold surface, and the concave spherical shapes corresponding to the convex spherical shapes of the upper and lower mold (15, 16) surfaces were directly transferred to obtain high surface accuracy. It is possible to obtain a biconcave spherical lens having good quality. Since the surface of the mold is transferred to the surface of the molding material in this way to form the glass lens surface, the surface layer of the mold facing the molding material is important, and there are no defects such as pores and it is dense and mirror-like. The material of the base material of the mold and the material of the surface layer of the mold are particularly limited as long as they can be precisely processed to have general conditions as a mold, such as having appropriate hardness and strength against heating. No need.

As described above, in the present invention, it is not necessary to coat the entire surface of the glass lens molding material surface in order to remove the non-filmed portion where the thin film is not formed after the film formation and prior to the pressure molding. As a result, it is not necessary to use a special holder during film formation to form a thin film on the entire surface or to add an extra step, and the mold material can also be silicon carbide, hard carbon, super hard, precious metal, etc. It will be possible to appropriately select from commonly used materials,
The present invention is economically excellent.

Since the above-mentioned thin film remains on the surface of the glass lens obtained after the pressure molding, washing with a commercially available film peeling solution, an acidic aqueous solution such as hydrochloric acid, sulfuric acid, nitric acid or the like or a mixed solution thereof is used. The thin film can be peeled off without adversely affecting the glass lens by a method such as washing with an aqueous solution such as the above, an alkaline aqueous solution such as sodium hydroxide, or finish polishing with a non-woven fabric.

However, without peeling off the thin film,
Alternatively, when one or more thin films are further provided on the thin film to form an antireflection film, or when the thin film can be used as it is as a component of a functional surface, such as a metal mirror, a peeling step of the thin film Is not necessary.

For example, a glass lens having a magnesium fluoride film can be used as it is as a lens having an antireflection function.

The method of manufacturing a glass lens according to the present invention can be applied to various optical elements such as aspherical lenses, prisms, decentering lenses as well as spherical lenses, and can be used for manufacturing a wide range of lenses.

A method of manufacturing a glass lens according to the present invention,
Further, a concrete description will be given based on the following examples.

[0036]

EXAMPLE 1 As a molding material, SiO ₂ —B ₂ O ₃ —La ₂ O ₃ based glass (transition temperature: 623 ° C.) was used as a disk-shaped glass (diameter: 20 m).
m, thickness: 3 mm), and an yttrium oxide thin film (thickness: 200Å) was formed on the upper and lower surfaces of the disk-shaped glass by the vacuum evaporation method using the apparatus shown in FIG.

Specifically, in FIG. 3, the disk-shaped molding material (1) is applied to a holder (8) provided in a vacuum chamber (9) of 1 × 10 ⁻⁴ torr (the molding material (1)). The thin film material (yttrium oxide) (10) evaporated from above the electron beam evaporation source (11) was vapor-deposited on the upper and lower surfaces of the molding material (1).

However, at the time of film formation, the thin film was not formed on the outer peripheral portion (width: 0.5 mm) that was shaded by the holder (8), and the glass surface was exposed. The non-film-forming portion (4) was removed by grinding with a cylindrical grinder (manufactured by Shigiya Seiki Seisakusho Co., Ltd.) as shown in FIG.

That is, the molding material (5) having the non-film-forming portion is held by the pressing jig (2), and the jig (2) is held.
The molding material (5) was rotated by the rotation of, and the non-film-forming portion (4) on the outer peripheral portion of the molding material (5) was ground and removed from the outermost side by the diamond grindstone (6).

A glass lens was produced by the reheat press method using the thus obtained object to be molded by the pressure molding apparatus shown in FIG.

The apparatus comprises an upper die (15) (material: silicon carbide) having a die surface that is precision mirror-finished into a convex spherical surface, and a holding die (21) (material: silicon carbide) that holds it.
And a lower die (16) (material: silicon carbide) and a holding die (22) (material: silicon carbide) for holding the lower die (16), which also has a die surface precisely processed into a convex spherical shape, and a push rod ( 17) (material: stainless steel) holding type (21)
Moves downward together with the upper mold (15), and the lower mold (1
6) Mates with the holding mold (22) which is integrated with. The above mold structure is heated by the heating light source (19) installed on the outer periphery of the transparent quartz tube (18), and the temperature is measured by the thermocouple (20) buried in the holding mold (22) to obtain the temperature. Control is performed.

The above-mentioned molded article (3) is placed on the upper and lower molds (15,
16), placed in a nitrogen atmosphere, and heated to a light source (1
9) upper mold, lower mold (15, 16) and holding mold (2)
1, 22) and the object to be molded (3) are heated to 670 ° C., the push rod (17) is lowered, and a load is applied to the upper die (15) and the holding die (21) holding it to apply pressure. Molded (pressure: 50 kg / cm ² , pressurization time: 30 seconds).

Next, the pressure of the push rod (17) is removed,
The pressure-molded product was cooled while being surrounded in the mold (15, 16, 21, 22), and then the pressure-molded product was taken out.

The obtained molded product was a biconcave spherical glass lens, and no fusion or the like was observed between the lens and the mold surface.
It was confirmed that a concave spherical surface shape corresponding to the convex spherical surface shape of the lower mold (15, 16) was transferred to obtain high surface accuracy, and a glass lens of good quality was obtained.

Comparative Example 1 An yttrium oxide thin film (thickness: 200Å) was formed on the upper and lower surfaces of a disk-shaped molding material (diameter: 20 mm, thickness: 3 mm) obtained in the same manner as in Example 1 It is formed by the vacuum vapor deposition method in the same manner as, and the non-film-forming portion (width:
A molding material having a thickness of 0.5 mm) was obtained.

Then, the non-film-forming portion of the molding material was not removed, and the molding material was used as it was as a molding target, in the same manner as in Example 1 by the pressure molding device shown in FIG. When pressure molding was performed, ring-shaped fusion occurred between the peripheral non-film-forming portion where the glass was exposed and the mold surface, and a glass lens of good quality could not be obtained. .

From Example 1 and Comparative Example 1, by removing the non-film-forming portion from the molding material having the non-film-forming portion produced in the conventional manner, all the surfaces of the molding material surface that come into contact with the mold surface are removed. It was revealed that the film was covered with a thin film having a releasing function, and fusion or the like during the subsequent pressure molding could be prevented.

Example 2 As a material for molding a glass lens, P ₂ O ₃ --Al ₂ O ₃ --R ₂
A disk-shaped glass (diameter: 20) was used in the same manner as in Example 1 except that an OF glass (transition temperature: 480 ° C.) was used.
mm, thickness: 3 mm) was obtained.

Magnesium fluoride thin films (thickness: 50Å) were formed on the upper and lower surfaces of the disk-shaped molding material by the RF magnetron sputtering method using the apparatus shown in FIG.

Specifically, argon is used as the sputter gas, magnesium fluoride is used as the target (12) material, and the glass lens molding material (1) is held at room temperature on the holder (8) at the outer peripheral portion of the molding material. It was installed so that it would be supported by. Then, argon was introduced into the vacuum chamber (9) through the gas introduction valve (13), and the discharge pressure was 7 × 10 ⁻³ Torr,
A magnesium fluoride thin film was formed on the upper and lower surfaces of the molding material (1) at a high frequency of 13.56 MHz and a discharge power of 200 W.

However, as in Example 1, when the film was formed, the thin film was not formed on the outer peripheral portion (width: 0.3 mm) that was shaded by the holder, and the glass surface was exposed. Then, in the same manner as in Example 1, the non-film-forming portion of the forming material was ground and removed by a cylindrical grinding machine to obtain a molding target.

In the pressure molding apparatus shown in FIG. 5, the upper mold material and the lower mold material are superhard, these holding mold materials are high density carbon, the transparent quartz tube (18) is the ceramic tube (2).
8) Using the pressure molding apparatus shown in FIG. 6 in which the heating light source (19) is an induction heating source (29) with a high frequency coil, and the pressure molding conditions are an argon atmosphere and a pressure temperature. A glass lens was produced by a reheat press method using the molding target from which the non-film-forming portion was removed, in the same manner as in Example 1 except that the pressing time was 530 ° C. and the pressing time was 15 seconds.

The obtained molded product was a biconcave spherical glass lens, and no fusion or the like was observed between the lens and the mold surface.
It was confirmed that a concave spherical surface shape corresponding to the convex spherical surface shape of the lower mold (25, 26) was transferred to obtain high surface accuracy, and a glass lens of good quality was obtained.

Comparative Example 2 A magnesium fluoride thin film (thickness: 50Å) was formed on the upper and lower surfaces of a disk-shaped forming material (diameter: 20 mm, thickness: 3 mm) obtained in the same manner as in Example 2. It was formed by the RF magnetron sputtering method in the same manner as in 2, and a molding material having a non-film-forming portion (width: 0.3 mm) on the outer peripheral portion was obtained.

Next, the non-film-forming portion of the molding material was not removed, and the molding material was used as it was as a molding target, in the same manner as in Example 2 by the pressure molding device shown in FIG. When pressure molding was performed, ring-shaped fusion occurred between the peripheral non-film-forming portion where the glass was exposed and the mold surface, and a glass lens of good quality could not be obtained. .

Comparing Example 2 and Comparative Example 2 with Example 1 and Comparative Example 1, the effect of preventing fusion and the like obtained by removing the non-film-forming portion is that the material for molding glass lenses and the thin film material are It turns out that it will be exhibited even if the value changes.

[0057]

According to the present invention, it is possible to prevent fusion of the glass lens molding material and the mold surface during pressure molding, and it is possible to obtain a glass lens of good quality. Further, even if the molding material has a non-film-forming portion, there is no problem as long as the removal step of the portion is passed, so there is no need to use a special holder during film formation or to add an extra step. Since the mold material can be appropriately selected from commonly used materials, the present invention is economically excellent.

[Brief description of drawings]

FIG. 1A is a schematic diagram of a glass lens molding material according to the present invention, in which an outer peripheral portion (referred to as a non-film-forming portion) where a thin film is not formed on the surface of the glass lens molding material is removed. b) is a schematic diagram of a conventional glass lens molding material having a non-film-forming portion.

FIG. 2 is a schematic configuration diagram showing a cylindrical grinder suitable for removing a non-film-forming portion.

FIG. 3 is a schematic configuration diagram showing a film forming apparatus used in Example 1 and Comparative Example 1.

4 is a schematic configuration diagram showing a film forming apparatus used in Example 2 and Comparative Example 2. FIG.

5 is a schematic configuration diagram showing a pressure molding device used in Example 1 and Comparative Example 1. FIG.

6 is a schematic configuration diagram showing a pressure molding device used in Example 2 and Comparative Example 2. FIG.

[Explanation of symbols]

 1: Glass lens molding material 2: Thin film 3: Glass lens molding material from which non-film-forming portion is removed 4: Non-film forming portion 5: Glass lens molding material having non-film forming portion 6: Diamond grindstone 7: Pressing Jig 8: Holder 9: Vacuum chamber 10: Thin film material 11: Electron beam evaporation source 12: Target 13: Gas introduction valve 14: High frequency power supply 15, 25: Upper mold 16, 26: Lower mold 17, 27: Push rod 18: Transparent quartz tube 19: Light source for heating 20, 30: Thermocouple 21, 22, 31, 32: Holding type 28: Ceramic tube 29: Induction heating source

Claims (1)

[Claims] 1. A glass lens molding material having a thin film having a releasing function formed on a surface on which a functional surface is molded, after removing a portion where the thin film is not formed prior to pressure molding, A method of manufacturing a glass lens, which comprises performing pressure molding.