JP2000007355A - Glass optical element molding method and molding frame used in the molding method - Google Patents

Abstract

(57) [Abstract] [Purpose] In a glass molding method for obtaining a glass optical element by pressing and molding a glass optical element material in a softened state, centering is unnecessary, molding is easy, and there are few restrictions on optical design. A method for molding a glass optical element having excellent optical performance and a frame used in the molding method are obtained. [Constitution] With a molding frame disposed outside a glass optical element material of a molding die, the glass optical element and the molding frame are joined by press molding with a molding die, and after the molding is completed, the molding frame is made of glass. A method for molding a glass optical element to be separated from the optical element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a molding method for molding a glass optical element and a molding frame used in the molding method.

[0002]

2. Description of the Related Art Conventionally, a molding method for obtaining an optical element by pressing a glass optical element (preform) in a heated and softened state to obtain an optical element is conventionally performed by forming the optical element slightly larger than a required outer diameter and centering (outer diameter rounding). And incorporated into the lens barrel. However, this method was costly due to many post-processing steps after molding. In particular, in the case of microlenses, high-precision centering work is required, and the cost is further increased. Further, there is a problem that a lens having a small centering coefficient or a lens having a low degree of centering cannot perform high-precision centering and cannot be used substantially.

[0003] In consideration of such problems, various lens frame integral molding methods for integrally molding the glass optical element and the outer frame have been tried. There is.

A method of obtaining a lens frame by injecting a resin into the outer periphery of an optical element and curing the resin is disclosed in Japanese Patent Application Laid-Open No. 2-164729. In this method, an injection molding machine must be combined with a glass molding machine, and the apparatus becomes large. Further, it is impossible to simultaneously cool the glass and the resin, and the resin is molded after the glass is cooled after the molding, so that the productivity is reduced. Further, since the material of the lens frame is limited to a resin, it is not suitable for molding a high-precision glass lens which does not like the influence of heat change. Since the resin is injected into the outer periphery of the optical element and cured, the mold to be filled with the resin also requires high-precision processing, and it is difficult to release the resin due to its complicated shape.

A method of integrally molding an optical element and a resin frame to obtain a lens frame is disclosed in Japanese Patent Application Laid-Open No. Hei 1-210334. In this method, since the softening temperature and the heat resistance temperature of the resin and the glass are significantly different, it is actually difficult to mold them at the same time. Since the softening temperature and the heat resistance temperature of the resin are lower than that of the glass, if an appropriate temperature for processing the glass is used, the resin is deformed and deteriorated, the shape cannot be maintained, and the glass cannot be used as a lens frame.

Japanese Patent Laid-Open No. 3-167514 discloses a method for integrally forming an optical element and a metal lens frame to obtain a lens frame. A material must be selected, and is limited to a metal material that can withstand high-temperature molding and also considers thermal expansion. Such metallic materials are expensive. Metal lens frames have a large specific gravity and are not suitable as lens lens frames.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional method of manufacturing a glass optical element, and requires no centering, can be easily molded, has less restrictions on optical design, and has a low optical performance. It is an object of the present invention to obtain a method for molding a glass optical element having excellent characteristics and a frame used in the molding method.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a glass optical element which is simple and has high optical performance can be obtained by integrally molding a glass optical element and a molding frame and then removing the molding frame. It was made by finding.

According to the present invention, in a glass molding method for obtaining a glass optical element by pressing and molding a glass optical element material in a softened state, a step of disposing a molding frame outside the glass optical element material of the molding die; And a step of separating the molding frame from the glass optical element after the molding is completed.

[0010] The molding frame is formed in a required shape, generally an annular (flat cylindrical body), and if the inner surface thereof is processed into an accurate required shape, the glass optical element from which the molding frame is removed can be formed as follows. The frame has the exact shape of the transferred shape, and can be used without any need for post-processing.

[0011] The molding frame is formed in an annular shape and has at least one frame.
If a frame having individual split grooves is used, the molding frame can be cut from the split grooves and easily separated. Also,
If a plurality of segments are formed by joining, they can be separated and separated from the joining portion. Such a molding frame can be made of at least glass having a transition point equal to or higher than the molding temperature of the glass optical element, or ceramic material having a maximum use temperature equal to or higher than the molding temperature of the glass optical element.

[0012]

1 to 6 show an embodiment of a molding frame for a glass optical element used in the method of the present invention. Each molding frame 40 is all annular (flat cylindrical body)
The inner diameter of the glass optical element is formed so as to match the outer diameter of the glass optical element after molding. Based on the required shape of the glass optical element, a contact portion of the molding frame with the glass optical element material (frame body) Is determined.

FIG. 1 shows a molding frame 40 made of a glass material whose transition point is higher than the molding temperature of the glass optical element. FIG. 2 shows a molding frame 40 which has the same shape as that of FIG. 1 but is made of a ceramic material (machinable ceramic) whose maximum use temperature is higher than the molding temperature of the glass optical element. FIG. 3 is a diagram showing a state where the molding frame made of the ceramic material of FIG.
It is a molding frame body 40 in which a split groove 41 is further inserted. The split grooves 41 are used to cut (break) the molding frame 40 after molding.
To facilitate. FIG. 4 shows a molding frame 40 made of a ceramic material having two split grooves 41 as in FIG.
The split groove 41 of this embodiment is provided on the outer peripheral surface of the frame. FIG. 5 shows a molding frame 40 made of a ceramic material provided with two split guide projections 42 at diametrically opposed positions. FIG. 6 shows a half (half circle) frame 40h made of a glass material whose transition point is higher than the molding temperature of the glass optical element, or a ceramic material (machinable ceramic) whose maximum use temperature is higher than the molding temperature of the glass optical element. Are bonded with a heat-resistant ceramic adhesive 43 which does not lose the adhesive force at the molding temperature of the glass optical element to form a molding frame 40.

FIG. 7 shows an example of the steps of the method of the present invention in which a glass optical element is formed using each of the forming frames 40 shown in FIGS. 1 to 5 and then the frame 40 is removed.

The molding device has an upper mold 10 and a lower mold 20.
An annular groove 200 for mounting the molding frame 40 is formed in a fixed portion on the outer periphery of the lower mold 20, and an escape groove 100 for releasing the molding frame 40 is formed on the outer periphery of the upper mold 10. . At the time of molding, the glass optical element material (glass preform) 30 is placed on the lower mold 20, and the molding frame 40 is placed in the annular groove 200.

The upper mold 10 and the lower mold 20 are made of, for example, a cemented carbide (tungsten carbide), silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), a titanium alloy or the like. Molding surface 1
1 and 21 are precisely machined into a molding surface shape, and then, on the surface thereof, in accordance with a conventional method, for the purpose of securing releasability and protecting the mold.
Platinum-based, diamond-like carbon (DIAMOND LIKECA
RBON), a protective film such as Cr ₂ O ₃ is formed alone or in combination.

The glass optical element material (glass preform) 30 inserted between the upper mold 10 and the lower mold 20 is shown in FIG.
A gob shape as shown in FIG.
It is polished in advance to a spherical surface similar to the surfaces 11 and 21 of 0. The molding frame 40 is formed such that the inner diameter thereof matches the outer diameter of the glass optical element 30M after molding, and the glass preform 30 of the molding frame 40 is formed.
Shape of the inner peripheral surface in contact with the glass optical element 30 after molding.
It is set according to the shape of M.

The glass preform 30 and the molding frame 40 set between the upper mold 10 and the lower mold 20 are heated in a non-oxidizing gas atmosphere at a temperature at which the glass preform 30 softens (optimal molding temperature, glass The preform 30 is heated to about 400 to 700 ° C. depending on the material), and a press pressure is applied between the upper mold 10 and the lower mold 20 until the preform 30 comes into close contact with the molding frame 40 under the heating. When the glass is cooled to the glass transition temperature while the pressing pressure is applied, the upper mold 1 is cooled.
The shapes of the molding surface 11 and the molding surface 21 of the lower mold 20 are transferred to the front and back of the glass preform 30, and the glass optical element 3
A glass optical element 50 with a frame in which the 0M and the molding frame 40 are integrated is obtained.

After cooling, the molding frame 40 of the framed glass optical element 50 is released by a method according to the shape of the molding frame 40. The molding frame 40 shown in FIG.
In this case, it is glass cut,
A flaw c is formed on the molding frame 40, and the glass optical element 30M is taken out by breaking along the flaw c. Since the shape of the inner peripheral surface of the frame body 40 is transferred to the glass optical element 30M, the glass optical element 30M does not need to be centered and can be used as it is. In the case where the molding frame 40 has a shape as shown in FIG. 2, the molding frame 40 may be similarly scratched and removed, and the molding frame 40 having the shape shown in FIGS. Then
The frame may be split (divided) along the split groove 41, the split guide projection 42, and the bonding portion 43, and separated from the glass optical element. In order to facilitate removal of the molding frame 40, carbon can be applied to the inner peripheral surface thereof before molding.

According to the method of molding the glass optical element 30M using the molding frame 40 described above,
A glass optical element with high precision can be manufactured. Further, since the glass optical element is molded integrally with the molding frame, the inner diameter of the molding frame becomes the outer diameter of the glass optical element, and centering is not required. In addition, since the element and the frame are integrally formed, handling such as removal and transportation is easy. Further, in the state of the glass optical element 50 with a frame, since the frame 40 for molding is provided, the surface of the glass optical element 30M is not touched, so that it is possible to prevent the occurrence of defects that occur during handling. In particular, a very small glass optical element is very effective in terms of handling. Since the molding frame is separated from the glass optical element in the final step, it can be used in the same manner as a normal lens, and can be used without a lens frame, which is advantageous in reducing the lens diameter.

[Example 1] The glass preform 30
"F2" (trade name, manufactured by Shot Co., transition temperature Tg = 4
35 ° C, yield point At = 480 ° C, coefficient of thermal expansion;
A glass optical element material at 300 ° C. α = 101 × 10 ⁻⁷ ) is used in the gob shape shown in FIG. The material of the molding frame 40 is “L6” (trade name, manufactured by Shot Co., Ltd., transition temperature Tg = 595 ° C., yield point At = 635).
° C, thermal expansion coefficient; 100-300 ° C α = 108 × 1
^0-7 ). The inner diameter of the molding frame 40 is set to match the outer diameter of the glass optical element after molding, and the inner peripheral surface of the molding frame 40 matches the shape of the desired glass optical element. It is an annular shape.

This glass preform 30 is
7 (a), heated to 505 ° C. in a non-oxidizing gas atmosphere, and pressed at that temperature (FIG. 7 (b)), and FIG. 7 (c). A glass optical element 50 with a frame was obtained in which the glass optical element and the molding frame 40 were integrated as shown in FIG. After cooling, as shown in FIG. 7 (d), the molding frame 40 is cut with a glass to make scratches c at two positions substantially opposite to each other in the diametrical direction.
0, the molding frame 40 is detached from the glass optical element 30.
M was taken out (FIGS. 7 (d), (e), (f)). The glass optical element 30M thus obtained did not require centering, and had good optical performance.

[Embodiment 2] The glass preform 30
“PBK40” (trade name, manufactured by Sumita Co., Ltd., transition point temperature T)
g = 501 ° C., yield point At = 549 ° C., coefficient of thermal expansion: 1
A glass optical element material of 00-300 ° C. α = 73 × 10 ⁻⁷ ) is used. The material of the molding frame 40 is machinable ceramics (maximum operating temperature Tg = 1000 ° C., coefficient of thermal expansion; 100-300 ° C. α = 97 × 10 ⁻⁷ ). As the molding frame 40, one having a shape shown in FIG. 3 was used. The inner diameter of the molding frame 40 is set to match the outer diameter of the glass optical element 30M. Using the glass preform 30 and the molding frame 40, a glass optical element 50 with a frame was obtained in the same manner as in Example 1 except that the molding temperature was set to 575 ° C. Thereafter, the frame was split along the two split grooves 41 to release the frame, thereby obtaining a glass optical element 30M. This glass optical element 30M did not require centering and had good optical performance.

[Embodiment 3] The glass preform 30
“LaSF08” (trade name, manufactured by Shot Co., Ltd., transition point temperature Tg = 730 ° C., yield point At = 761 ° C., thermal expansion coefficient;
100-300 ° C. α = 79 × 10 ⁻⁷ ) glass optical element material is used. The frame 40 is made of machinable ceramics (maximum operating temperature Tg = 1000 ° C., thermal expansion coefficient: 1).
00-300 ° C. α = 97 × 10 ⁻⁷ ). The molding frame 40 has the shape shown in FIG. 2 and its inner diameter is set to match the outer diameter of the glass optical element after molding. Using the above glass preform 30 and the molding frame 40, a glass optical element 50 with a frame was obtained in the same manner as in Example 1 except that the molding temperature was set at 785 ° C. Thereafter, the frame was removed to obtain a glass optical element 30M. As with the other examples, the glass optical element 30M did not require centering and had good optical performance. In addition, even when the molding temperature was as high as 785 ° C., there was no change in the properties of the frame mold, and stable use was possible.

Example 4 The glass preform 30
“LaSFn9” (trade name, manufactured by Shot Co., Ltd., transition point temperature Tg = 693 ° C., yield point At = 719 ° C., thermal expansion coefficient;
100-300 ° C. α = 76 × 10 ⁻⁷ ) glass optical element material is used. The material of the molding frame 40 is machinable ceramics (maximum operating temperature Tg = 1000 ° C., coefficient of thermal expansion; 100-300 ° C. α = 97 × 10 ⁻⁷ ). The molding frame 40 has the shape shown in FIG. 5 and its inner diameter is set to match the outer diameter of the glass optical element. Using the above glass preform 30 and the molding frame 40,
A glass optical element 50 with a frame was obtained in the same manner as in Example 1 except that the molding temperature was 750 ° C. Thereafter, the frame body 40 was cleaved by grasping the split guide projections 42 and separated to obtain a glass optical element 30M. This glass optical element 30M
As in the other examples, centering was unnecessary and the optical performance was good.

[0026]

According to the present invention, since the inner peripheral shape of the molding frame becomes the outer peripheral shape of the glass optical element, centering of the glass optical element is unnecessary. Since centering is not required, glass optical elements that are difficult to center can be easily formed, and there are few restrictions on optical design, and glass optical elements with excellent optical performance can be obtained. Further, since the glass optical element is formed integrally with the molding frame, the glass optical element can be handled without touching the optical functional surface of the optical element by gripping the frame. Therefore, handling is facilitated, occurrence of defects during handling can be prevented, and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a frame for molding a glass optical element according to the present invention.

FIG. 2 is a view showing an example of a frame for molding a glass optical element according to the present invention.

FIG. 3 is a view showing an example of a frame for molding a glass optical element according to the present invention.

FIG. 4 is a view showing an example of a frame for molding a glass optical element according to the present invention.

FIG. 5 is a view showing an example of a frame for molding a glass optical element according to the present invention.

FIG. 6 is a view showing an example of a frame for molding a glass optical element according to the present invention.

FIG. 7 is a diagram illustrating a molding method using a molding frame for a glass optical element according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Upper mold 11 Molding surface 20 Lower mold 21 Molding surface 30 Glass optical element material (glass preform) 30M Glass optical element 40 Molding frame 50 Glass optical element with frame

Claims (9)

[Claims] In a glass molding method for obtaining a glass optical element by pressing and molding a glass optical element material in a softened state, a step of disposing a molding frame outside a glass optical element material of a molding die; A method for molding a glass optical element, comprising: a step of joining a glass optical element and a molding frame by molding; and a step of separating the molding frame from the glass optical element after the molding is completed. 2. The method for molding a glass optical element according to claim 1, wherein the molding frame has an annular shape and has at least one split groove. 3. The method of molding a glass optical element according to claim 1, wherein the molding frame is formed by joining a plurality of segments. 4. The method for molding a glass optical element according to claim 1, wherein the molding frame is made of glass having a transition point higher than the molding temperature of the glass optical element. 5. The method for molding a glass optical element according to claim 1, wherein the molding frame is made of a ceramic material having a maximum use temperature equal to or higher than the molding temperature of the glass optical element. 6. A molding frame is arranged outside a glass optical element material of a molding die, and then the glass optical element and the molding frame are joined by press molding with a molding die. The molding frame used in the method for molding a glass optical element, wherein the molding is separated from the glass optical element, wherein the molding frame has an annular shape and has at least one split groove. 7. A molding frame is arranged outside the glass optical element material of the molding die, and then the glass optical element and the molding frame are joined by press molding with the molding die. The molding frame used in the method of molding a glass optical element for separating the glass frame from the glass optical element, the molding frame comprising a joined body of a plurality of segments forming an annular shape as a whole. 8. The molding frame for a glass optical element according to claim 6, which is made of glass having a transition point higher than the molding temperature of the glass optical element. 9. The molding frame for a glass optical element according to claim 6, wherein the frame is made of a ceramic material having a maximum use temperature equal to or higher than the molding temperature of the optical element.