JPH07101736A - Molding glass material and method for manufacturing optical glass element - Google Patents

Abstract

(57) [Abstract] [Purpose] Optical element molding technology (manufacturing of glass material for molding and optical glass element) that enables good optical performance even when eccentricity occurs between the molding glass material and the upper and lower molds. Method). [Structure] Inner diameter of barrel mold is φC, optical effective surface diameter of upper and lower molds is φA, outer diameter of molding glass material is φS, effective surface diameter of molding glass material is φSS When φA <φSS ≦ φS, and φC− [φS
A glass material for molding which satisfies − {(φS−φSS) / 2} ≦ (φC−φA) / 2 is used. [Effect] The surface other than the effective surface of the molding glass material does not wrap around the optically effective surface of the optical glass element, and it is necessary to process the surface other than the effective surface of the molding glass material with the same high precision as the effective surface. It eliminates the need for positioning devices.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding glass material for forming a high-precision optical glass element such as a lens or a prism used in optical equipment by a precision glass molding method, a method for producing an optical glass element, and an optical glass element. Regarding glass elements.

[0002]

2. Description of the Related Art In recent years, many attempts have been made to realize high-precision optical lenses, particularly aspherical glass lenses, etc. by one-shot molding without a polishing step, and these are being realized.

As one of the molding methods, there is a method of heating a glass material to a temperature at which it can be deformed, for example, a temperature near its softening point, and molding it by means such as press molding (see, for example, JP-A-61-161). 21927, JP-A-62-18212.
No. 2).

This method requires a glass molding material having a good surface roughness and an appropriate shape. An example of a conventional method for manufacturing an optical glass element will be described below with reference to the drawings.

FIG. 5 is a cross-sectional view showing a conventional glass material for molding, one surface of which is a flat surface and the other of which is an R-curved surface and the optical glass element is deformed under pressure. Reference numerals 20 and 21 are upper and lower dies, 22 is a barrel die, 25 is an optical glass element, and 23 and 24 are parts of a press head having a heating and pressing mechanism.

The glass material 25 for molding is supplied into the upper mold 20, the lower mold 21, and the body mold 22, and heated by press heads 23 and 24 equipped with a heating and pressing mechanism to press-mold. After the deformation is completed, the upper mold 20, the lower mold 21, the body mold 22, and the optical glass element 25 are gradually cooled, and when the temperature is below the temperature at which the optical glass element 25 can be taken out, the upper mold 20 is opened, and the optical glass element 25 is opened. Take out.

[0007]

In the above molding method, when the outer diameter of the glass material for molding is smaller than the inner diameter of the barrel by a certain degree or more, the glass material for molding and the upper and lower molds are eccentric to each other. When the eccentricity occurs, the surface other than the effective surface of the molding glass material wraps around to the optically effective surface of the optical glass element.

The above-mentioned optically effective surface of the optical glass element is the minimum required optical action surface for producing the optical performance actually required for the optical glass element in the optical glass element, and The effective surface of the optical glass material is a surface having the same surface roughness as that of the optical glass element.

To give a concrete example of the surface roughness, in the case of a polished surface, Rmax = 0.01 μm or less is often used. Of course, since the required surface roughness differs depending on the optical glass element, You can't affirm uniformly.

When a surface other than the effective surface of the glass material for molding is molded as an optically effective surface of the optical glass element, not only the appearance but also the performance of the optical glass element is adversely affected by a decrease in transmittance.

In order to prevent them, a molding glass material and a mold positioning mechanism are provided, and a surface of the molding glass material other than the effective surface is processed to have the same surface roughness as the effective surface. If a material is used, the cost of the glass material for molding and the molded optical glass element increases.

When the difference between the inner diameter of the barrel die and the outer diameter of the forming glass material is so small that there is almost no difference, the optical functional surface of the die and the forming glass may be changed depending on the shape of the die and the forming glass material. There is a problem that the gas in the closed space between the effective surfaces of the material does not escape, or the amount of deformation cannot be secured sufficiently, the transfer of the optically effective surface becomes incomplete, and a good optical glass element can be obtained. I could not do it.

[0013]

In order to solve the above-mentioned problems, the present invention is directed to a cylindrical mold inner diameter of φC, a pair of upper and lower molds having a larger optically effective surface diameter, and an optically effective surface diameter of φA. The outer diameter of the material is φS, and the effective surface diameter of the glass material for molding is φ
When SS, the relation between them is φA <φSS ≦ φS, and φC− [φS − {(φS−φSS) /
2}] ≦ (φC−φA) / 2 is used.

[0014]

[Function] With the molding glass material satisfying the above-mentioned relationship, even when eccentricity occurs between the molding glass material and the upper and lower molds, the wraparound of the surface other than the effective surface of the molding glass material on the optically effective surface of the optical glass element. It is possible to obtain an optical glass element having a good optically effective surface.

[0015]

EXAMPLES Examples of the glass material for molding, the method for producing an optical glass element and the optical glass element of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is an explanatory view of a first embodiment of the present invention, showing a state in which a glass material for molding is held between upper and lower molds and an optical glass element.

In FIG. 1, 1 is an upper mold, 2 is a lower mold, 3 is a barrel mold, 6 is a glass material for molding, 4 and 5 are a part of a press head having a heating and pressing mechanism, and 7 is an optical glass. It is an element.

In the present embodiment, the inner diameter φC of the barrel die for controlling the outer diameter of the molded optical glass element 7 is φ6 mm. Optical functional surface diameter φBu of upper mold 1 and optical functional surface diameter φ of lower mold 2
Bd is φ5.5 mm, the optical effective surface diameter φAu of the upper mold 1 is φ
4.3 mm, lower die 2 has an optically effective surface diameter φAd of φ4.5 m
m.

The radius of curvature of the upper mold 1 is 8 mm, and the lower mold 2 is
Has a radius of curvature of 12 mm and an optical functional surface diameter φBu = φBd =
It is processed up to φ 5.5 mm, and the outer circumference is flat from that.

The above-mentioned upper and lower optically effective surfaces are the minimum required to produce the optical performance actually required for the optical glass element corresponding to the optically effective surface of the molded and transferred optical glass element. It is a face.

Further, the above-mentioned optical function surface is as shown in FIG.
As shown in (a), it is a surface including an optically effective surface and a surface obtained by adding a curved surface from the optically effective surface to a flat surface. If there is no flat surface, the inner diameter of the barrel die and the outer diameter portion of the upper and lower dies that are slidably housed are the optically functional surfaces.

Optical effective surface diameters φAu, φ of the upper mold 1 and the lower mold 2.
Not only Ad but also the optically effective surface diameters φAu and φAd to the optically functional surface diameters φBu and φBd may be processed into aspherical surfaces instead of spherical surfaces.

The shape accuracy is PV = λ / for both the upper mold 1 and the lower mold 2.
It is 8 (λ = 633 nm) or less. Molding glass material 6
4 (a cross-sectional view is shown in FIG. 4A), both end faces are flat and have a surface roughness Rmax = 0.
The outer peripheral surface (the surface other than the effective surface) is a ground surface, and the surface roughness is Rmax = about 1 µm.
m, the outer diameter φS and the effective surface diameter φSS are equal to each other and are made to be φ5.4 mm.

Therefore, in this embodiment, the optical effective surface diameter φAd = φA = φ of the upper and lower dies having the larger optical effective surface diameter.
4.5 mm, of the upper and lower molds, which has a smaller optical function surface diameter, has an optical function surface diameter φBu = φBd = φB = φ5.5 mm, φS
= ΦSS = 5.4 mm and φC = φ6 mm, which are within the range of the dimensional relationship of the present invention.

The center thickness of the optical glass element 7 is 3.0.
mm, and the thickness of the glass material for molding 6 is 3.12 mm.
Has been created in. SF4 (Tg = 430 ° C.) was used as the material of the glass material 6 for molding.

Forming glass material 6 Forming glass material 6
Effective surface diameter φSS and upper and lower optical effective surface diameters φAu, φA
It is arranged between the upper die 1, the lower die 2 and the body die 3 so that d faces each other. The press heads 4, 5 heat them.

When the molding glass material 6 reaches a temperature at which it can be molded, it is pressed by the press heads 4 and 5 to be deformed by a predetermined amount. Molding temperature is 520 ℃, pressure is 450 Kg
It was set to f / cm ² .

The center thickness of the optical glass element 7 is determined by the contact between the end surface of the barrel die 3 and the surfaces of the upper die 1 and the lower die 2 which face the end faces of the barrel die 3. The center thickness of the optical glass element may be determined by other methods.

After the deformation is completed, the press heads 4 and 5 perform cooling. When the temperature at which the optical glass element 7 can be taken out falls below 420 ° C., the upper mold 1 and the barrel mold 3 are disassembled, and the optical glass element 7 is taken out. The shape accuracy of the optical glass element 7 was PV = λ / 5 or less on both upper and lower surfaces, and the mold accuracy was well transferred.

Further, as shown in FIG. 1B, even if the molding glass material 6 is biased to one side and the outer peripheral surface comes into contact with the inner wall of the barrel mold 3, the outer peripheral surface of the molding glass material 6 on the opposite side is opposed. The maximum gap Ls between the inner wall of the body mold 3 and Ls = φC− [φS−
{(ΦS-φSS) / 2}] = 6- [5.4-{(5.
4-5.4) / 2}] = 0.6 mm, and the distance Lku from the inner wall of the barrel die 3 to the optically effective surface diameter φAu of the upper die 1.
= (ΦC−φAu) / 2 = (6−4.3) /2=0.8
5 mm, distance Lkd to the optically effective surface diameter φAd of the lower mold 2
= (ΦC−φAd) / 2 = (6-4.5) /2=0.7
Since it is smaller than 5 mm, that is, because of the dimensional relationship specified in the present invention, the optical effective surface diameters φAu and φAd of the optical glass element 7 are changed to the effective surface diameter φSS of the molding glass material 6 as shown in FIG. It was possible to obtain the optical glass element 7 which always had a good transfer surface without wrapping around other surfaces.

The shapes of the upper mold 1 and the lower mold 2 of this embodiment, the optical function surface diameters φBu and φBd are smaller than the barrel mold inner diameter φC, and the optical function surface diameters φBu and φBd have a concave shape, as shown in FIG. When a glass material for molding whose both end surfaces are flat is used, the optical effective surface diameter φA of the upper and lower molds having the larger optically effective surface diameter, and the optical functional surface of the lower mold having the smaller optically functional surface diameter. The relationship among the diameter φB, the outer diameter φS of the glass material for molding, and the effective surface diameter φSS of the glass material for molding is φA <φSS ≦ φS
It is desirable that ≦ φB.

When φS becomes larger than φB, φS and φC
Is small, the amount of deformation is not sufficient, and the gas in the closed space between the effective surface diameter φSS of the molding glass material 6 and the optically functional surface diameter φB of the mold is difficult to escape, which causes transfer failure.

However, if the glass material for molding having the shape as shown in FIG. 4 (d) is used, the sealed space will not exist, so that transfer failure will not occur even if φA <φSS ≦ φS. There is no.

(Embodiment 2) FIG. 2 is an explanatory view of the second embodiment of the present invention, in which a glass material 13 for molding is used for the upper and lower molds 8,
9 shows a state of being held for 9 seconds. Reference numerals 11 and 12 are parts of a press head provided with a heating / pressurizing mechanism.

The upper mold 8 and the lower mold 9 are processed into convex shapes so that desired optical performance can be obtained (thus, concave lenses are molded). Optical function surface diameter φB of upper mold 8 and lower mold 9
u and φBd have the same diameter φ8 mm as the barrel die inner diameter φC, the radius of curvature of the upper die 8 is 6 mm, and the radius of curvature of the lower die 9 is 7.5.
mm, and the optical effective surface diameters φAu and φAd are smaller than that. Upper die φ6.0 mm, Lower die φ6.2 mm
Is. The shape precision is PV = λ / 8 or less for both the upper mold 8 and the lower mold 9.

The shape of the glass material for molding 13 is flat on both end surfaces, and the flat surface portion is finished to have a surface roughness Rmax = 0.01 μm or less equivalent to that of an optical glass element, but the outer peripheral surface is a ground surface. And the surface roughness is Rmax = approximately 0.
The diameter is 2 μm, the outer diameter φS and the effective surface diameter φSS are equal, and both are formed with φ7.1 mm, which is within the range of the dimensional relationship specified in the present invention.

The center thickness of the optical glass element obtained by molding is 0.8 mm, and the thickness of the molding glass material 13 is 2.6.
It was set to 5 mm.

In this embodiment, an optical glass element is obtained by the same steps as in the first embodiment. In this embodiment, SF8 (Tg = 425 ° C.) is used as the glass material 13 for molding, the molding temperature is 530 ° C., and the pressure is 200 Kgf / cm.
^{2. The} take-out temperature was 420 ° C. or lower.

As a result, the shape accuracy of the obtained optical glass element was PV = λ / 5 or less on both upper and lower surfaces, and the mold accuracy was excellently transferred.

Further, as in the case of FIG. 1B, when the glass material 13 for molding is intentionally biased to one side (in other words,
Even when the molding glass material 13 and the upper mold 8 and the lower mold 9 are decentered), the surfaces other than the effective surface diameter φSS of the molding glass material 13 are the optical effective surface diameters φAu and φAd of the optical glass element.
, The optical effective surface diameter φAu of the optical glass element within the effective surface diameter φSS of the molding glass material 13,
An optical glass element having good optical performance in which φAd was formed could be molded.

In this embodiment, when the forming glass material 13 is biased to one side and the outer peripheral surface of the forming glass material 13 comes into contact with the inner wall of the barrel mold 10, the outer peripheral surface of the forming glass material 13 on the opposite side and the body. The maximum gap with the inner wall of the mold 10 is 0.9 mm, which is the same as the distance 0.9 mm from the inner wall of the barrel mold 10 to the optically effective surface diameter φAd of the lower mold 9.

On the other hand, it has been confirmed that the effective surface diameter φSS of the glass material for molding before molding is largely expanded by the press molding. Therefore, in this embodiment, the glass material for molding is formed on the optically effective surface of the optical glass element. The surface (outer peripheral surface) other than the effective surface of 13 does not go around.

(Embodiment 3) FIG. 3 shows a third embodiment of the present invention.
The state of being held between 15 is shown. Reference numeral 16 is a barrel mold, 19 is a glass material for molding, and 17 and 18 are parts of a press head having a heating and pressing mechanism.

The upper mold 14 is processed into a convex shape having a radius of curvature of 8.0 mm. The optical functional surface diameter φBu of the upper die 14 is 13 mm which is the same as the inner diameter φC of the barrel die 16, and the optically effective surface diameter φA.
u is φ8.24 mm.

The optical functional surface diameter φBd of the lower mold 15 is φ12 m.
m, the optically effective surface diameter φAd is φ10.8 mm, and the radius of curvature is 40.0 mm. Shape accuracy is upper mold 14, lower mold 15
Both are PV = λ / 8 or less.

The shape of the glass material for molding 19 is a disk shape with both end surfaces being flat, and this flat surface portion is finished to have a surface roughness Rmax = 0.01 μm or less equivalent to that of an optical glass element, but the outer peripheral surface. Is a ground surface having a surface roughness of Rmax = 0.8 μm. Further, the outer diameter φS and the effective surface diameter φSS are made equal to each other by φ11.9 mm, which satisfies the dimensional relationship prescribed in the present invention. Center thickness of optical glass element 1.2
In order to obtain mm, the thickness of the glass material for molding 19 is 2.9.
It was 3 mm.

An optical glass element was obtained by the same steps as in the first example. The shape accuracy of the optical glass element is PV on both the upper and lower surfaces.
= Λ / 4 or less, and the mold precision was transferred well.

Further, a glass material for molding having a shape in which the outer peripheral surface and the effective surface shown in FIGS. 4 (b) and 4 (c) were connected by the C surface and the R surface was prepared. In both cases, the outer diameter φS is φ12 mm, and the chamfered portion is 0.1 mm (C0.1 mm, R0.
1 mm), the effective surface diameter φSS is φ11.8 mm, the thickness is 2.88 mm, and the surface roughness of the effective surface diameter is Rmax = 0.0.
The surface roughness is 1 μm or less, and the surface roughness other than the effective surface is Rmax = 3 μm.

Further, a glass material for molding shown in FIG. 4 (d) was prepared, which has a biconvex R shape, and the outer diameter φS and the effective surface diameter φSS are equal to each other and the radius of curvature is 38 mm on both sides. The thickness is 0.0 mm and the center thickness is 3.37 mm.

Molding was performed in the same manner for these glass materials for molding. The optical glass material of any shape satisfies the dimensional relationship specified in the present invention, and even if the molding glass material is intentionally biased to one side, the surface other than the effective surface of the molding glass material is an optical glass element. It was possible to obtain an optical glass element having good optical performance in which the optical effective surface of the optical glass element was formed within the effective surface diameter φSS of the molding glass material without being transferred to the optical effective surface of .

It is needless to say that an optical glass element having a good transfer surface can be obtained even if the shape other than the glass material for molding mentioned in this embodiment satisfies the relationship prescribed in the present invention.

For example, as shown in FIG. 4 (c), in the shape with R chamfering, the R chamfered portion is mirror-finished to obtain an effective surface portion φS.
There is no problem even if S has the same diameter as the outer diameter φS. Further, there is no problem even if the outer diameter of the optical glass element, which is regulated by the inner diameter of the barrel mold, is subjected to centering processing or the like after molding and used as the optical glass element.

[0053]

According to the present invention, even when eccentricity occurs between the molding glass material and the upper and lower molds, a surface other than the effective surface of the molding glass material does not wrap around the optical effective surface of the optical glass element. The optical effective surface of the optical glass element can be formed only by the effective surface of the glass material for molding.

For this reason, it becomes possible to use a glass material for molding in which the surfaces other than the effective surface of the glass material for molding are not processed to the same surface roughness as the effective surface, and the glass material for molding becomes inexpensive.

Further, since a molding glass material positioning device for preventing eccentricity is not required, the process is simplified,
Further, the cost of the optical glass element can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the present invention.

FIG. 4 is a sectional view showing an example of the glass material for molding of the present invention.

FIG. 5 is an explanatory view of a conventional molding technique for an optical glass element.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 3 Body mold 4 Part of press head having heating / pressurizing mechanism 5 Part of press head having heat / pressurizing mechanism 6 Glass material for molding 7 Optical glass element 8 Upper mold 9 Lower mold 10 Body Mold 11 Part of a press head having a heating and pressing mechanism 12 Part of a press head having a heating and pressing mechanism 13 Glass material for molding 14 Upper mold 15 Lower mold 16 Body mold 17 One of press heads having a heating and pressing mechanism Part 18 Part of a press head having a heating and pressing mechanism 19 Glass material for molding 20 Upper mold 21 Lower mold 22 Body 23 A part of a press head having a heating and pressing mechanism 24 A press head having a heating and pressing mechanism Part 25 Optical glass element

Front page continuation (72) Inventor Masaaki Sunohara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. An optical effective surface diameter of a mold having a larger optical effective surface diameter of a pair of upper and lower molds is φA, an inner diameter of a barrel mold is φC, an outer diameter of a molding glass material is φS, and an effective surface diameter of a molding glass material. Φ
When SS, the relation between them is φA <φSS ≦ φS, and φC− [φS − {(φS−φSS) /
2}] ≦ (φC−φA) / 2, a glass material for molding. 2. A mold having a larger optical effective surface diameter of the pair of upper and lower molds has an optical effective surface diameter of φA, and a mold having a smaller optical functional surface diameter of the above-mentioned upper and lower molds has an optical functional surface diameter of φB. The outer diameter of the glass material is φS, and the effective surface diameter of the glass material for molding is φ
The glass material for molding according to claim 1, wherein, when SS, φA <φSS ≦ φS ≦ φB. 3. An optical effective surface diameter of a mold having a larger optical effective surface diameter of a pair of upper and lower molds is φA, an inner diameter of a barrel mold is φC, an outer diameter of a glass material for molding is φS, and an effective surface diameter of a glass material for molding is Φ
When SS, the relation between them is φA <φSS ≦ φS, and φC− [φS − {(φS−φSS) /
2}] ≦ (φC−φA) / 2 is supplied so that the optical effective surface of the mold and the effective surface of the molding glass material face each other between the upper and lower molds, and the molding glass material is An optical device characterized by heating to a temperature near the softening point, press-molding with an upper mold and a lower mold, then cooling the optical glass element to a temperature near the glass transition point, and then taking out the optical glass element. Method for manufacturing glass element. 4. A molding glass having an optical effective surface diameter of a mold having a larger optical effective surface diameter of a pair of upper and lower molds, and an optical functional surface diameter of a mold having a smaller optical functional surface diameter of the aforesaid upper and lower molds, φB. The outer diameter of the material is φS, the effective surface diameter of the glass material for molding is φSS
4. The method for producing an optical glass element according to claim 3, wherein a glass material for molding with φA <φSS ≦ φS ≦ φB is used.