JP2010018476A - Molding method of optical element and optical element molding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element molding material which is loaded with high positional accuracy on a lower mold for precision molding so that a highly precise optical element can be produced. <P>SOLUTION: The molding material 4 of glass is loaded on the lower mold 1 having a plurality of concave parts 3, and the optical element molding material, in which a leg 5 formed by the concave part 3 of the lower mold 1 and a glass lump 6 are integrated between the lower mold 1 and an upper mold 2, is formed. When the optical element molding material is loaded on the lower mold 7 for precision molding for press molding the optical element, the leg 5 of the optical element molding material supports the glass lump 6 and therefore the optical element molding material can be held with high positional precision on the lower mold 7 during press molding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical element molding method and an optical element molding material for manufacturing an optical element made of glass.

  As a technique for molding an optical element, for example, as disclosed in Patent Document 1, a technique is known in which an optical glass lump with macroscopic undulation is hot-molded by a mold.

JP-A-1-301528

  In recent years, the use of molded glass optical elements in optical devices has become common, and the development of lens shapes that have not been seen in the past has been progressing. In particular, the development of biconcave shaped glass optical elements has been active recently. is there.

  There are the following problems as an optical element molding material for molding such a biconcave optical element.

  The most inexpensive glass optical element molding material is a glass lump obtained by floating and holding a molten glass lump in a non-contact state by a gas flow from below. However, since the outer shape of the glass lump is formed by the surface tension of the molten glass, the entire surface has a convex shape with a free surface. It is difficult to place such a convex glass lump with high accuracy on a lower mold of a precision mold for molding a biconcave optical element.

  On the other hand, in the method disclosed in Patent Document 1, since a molding material with macroscopic undulation is obtained by molding, it is relatively stable on a lower mold of a precision molding die for molding a biconcave optical element. Can be placed. However, the method disclosed in Patent Document 1 has a problem that the position and size of macroscopic swell are not stable. Therefore, when trying to obtain a biconcave optical element from a molding material having such macroscopic undulations, it is difficult to place the molding material on the convex lower mold with high accuracy. It is.

  In recent years, development of automation and high cycle of an apparatus for molding a glass optical element has been advanced. In such an optical element manufacturing apparatus, there is a case where a process of moving the lower mold of the precision molding die in which the molding material is placed in the apparatus occurs. In this moving process, the optical element molding is performed. It is difficult to hold the material for use on the lower mold of the precision mold with high accuracy.

  In the present invention, an optical element molding material is placed on a lower mold for precision molding with high accuracy, and the positional accuracy (placement accuracy) is maintained even during movement of the lower mold. An object of the present invention is to provide an optical element molding method and an optical element molding material that can be manufactured.

  The optical element molding method of the present invention includes a first step of molding an optical element molding material comprising a glass block and a leg formed integrally with the glass block, a lower mold for precision molding, and an upper A second step of obtaining an optical element by press-molding the optical element molding material with a mold, and in the second step, the glass block of the optical element molding material is It is supported on the lower mold by a leg.

  An optical element molding material of the present invention is an optical element molding material for molding an optical element, and a glass lump and legs formed integrally with the glass lump in order to support the glass lump. , Provided.

  Since the optical element molding material is provided with legs, it can be placed on the lower mold for precision molding for molding the optical element with high placement accuracy.

  In particular, an optical element having a concave lens shape which is difficult to mold can be easily molded with high accuracy, and can contribute to a reduction in manufacturing cost.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  FIGS. 1A to 1C show a first step of an optical element molding method according to an embodiment. First, as shown in FIG. 1A, an optical element molding material is molded. A lower mold 1 and an upper mold 2 are prepared. The lower mold 1 has a recess 3 for forming a leg of an optical element forming material.

  The mold prepared in this step may be a mold that molds only the legs, or a mold that molds both the legs and the glass lump.

  The number and shape of the leg portions and the shape of the mold corresponding thereto are appropriately selected in view of the purpose of stabilizing the optical element molding material on the precision mold.

  The mold prepared in the first step is preferably made of a material having poor wettability with molten glass, and specific materials include carbon and ceramic.

  As shown in FIGS. 1B and 1C, an optical element molding material composed of integrally formed legs 5 and glass lumps 6 is molded from the molding material 4 using the molding die shown in FIG. .

  As for the molding temperature and pressing force in this step, it is desirable that an optimum process is selected from the molding range and the molding material shape in this step.

  In this step, molding in a non-oxidizing atmosphere or molding in an air atmosphere can be selected from the molding process.

  FIG. 1D shows an optical element molding material composed of the glass block 6 and the legs 5 obtained in the first step placed on a lower mold 7 for precision molding. A second step of using the precision molding (press molding) to obtain an optical element is shown. This step is preferably performed in a non-oxidizing atmosphere.

  The mold used in this step is preferably made of a material having high temperature strength such as ceramic.

  As for the molding temperature and pressing force in this step, it is desirable to select an optimum process from the type of glass and the lens shape.

  The shape of the optical element molded in this example is a biconcave shape, and the glass material is an optical glass having a high refractive index of nd1.82. Specific dimensions of the optical element are a biconcave lens having a diameter of 10.0 mm, a center height of 1.5 mm, a concave surface R12 mm, and a concave surface R18 mm.

  The mold for molding the optical element molding material in the first step has a lower mold 1 and an upper mold 2 as shown in FIG. 1A, and molds the legs 5 of the optical element molding material. For this purpose, the molding surface of the lower mold 1 is provided with a recess 3. The outer diameter of the lower mold 1 and the upper mold 2 is 12 mm. The cavity formed by these molds is adjusted to a thickness of 3 mm. The recess 3 for forming the leg has a spherical crown shape with a radius of 4 mm, an opening diameter of 3 mm, and a depth of 0.29 mm. As shown in FIG. 1C, the recesses 3 were provided at three places on a PCD 3 mm pitch circle. This mold was made of cemented carbide, and a carbon-based release film was provided on the molding surface.

  Using this cemented carbide mold, an optical element forming material composed of a glass lump 6 and a plurality of legs 5 is formed.

  As a material used in this step, a convex glass lump consisting of a free surface whose entire surface was smooth was prepared as a molding material 4. This lump of glass is obtained by keeping molten glass in a non-contact state by a gas flow and cooling it. The convex glass lump used in this example has a diameter of 6 mm and a height of 4 mm.

  As shown in FIG. 1A, with the molding material 4 placed on the lower die 1, the lower die 1, the upper die 2, and the molding material 4 are heated to 610 ° C. in a non-oxidizing atmosphere, and molding is performed. After the material 4 was softened, the atmosphere was reduced in pressure and molded with a press force of 2000 N. Then, it cooled and took out the optical element shaping | molding raw material from the shaping | molding die.

  The optical element molding material thus obtained includes a plurality of legs 5 and a glass lump 6 as shown in FIGS. Each leg 5 is formed in a spherical crown shape having a height of 0.28 mm. The glass block 6 is formed in a disk shape having a diameter of 8 mm and a thickness of 3 mm.

  Next, as a second step, the optical element molding material composed of the glass block 6 and the legs 5 was press-molded using the lower mold 7 for precision molding to obtain an optical element. The optical element molding material placed on the precision molding lower mold 7 is in a state where the glass block 6 is supported by the legs 5 on the lower mold.

  The precision mold is made of cemented carbide, the lower mold 7 is a convex spherical surface of R18 mm, and the upper mold (not shown) is a convex spherical surface of R12 mm. A cylindrical side surface mold (not shown) is also provided so that the side surface portion of the optical element can be molded.

  In this embodiment, the lower die 7 is raised on the lower die 7 while the glass block 6 is supported by the legs 5 of the optical element molding material, and is conveyed into the side die and press-molded. The press temperature was 610 ° C., the press force was 3000 N, and press molding was performed in a nitrogen atmosphere.

  The dimensions of the optical element as a molded product were a biconcave lens having a diameter of 10 mm, a center height of 1.5 mm, a concave surface R12 mm, and a concave surface R18 mm. The optical element obtained in this way has high optical performance, and its side surface is molded with high shape accuracy, and can be incorporated into the lens barrel of optical equipment without the need for centering processing. Met.

  According to the present embodiment, the manufacturing cost of an optical element having high optical performance can be greatly reduced.

  In this example, in the step of obtaining an optical element having the same shape (biconcave shape) as in Example 1, only the configuration of the molding die for molding the leg part of the optical element molding material composed of a glass lump and a leg is different.

  As shown in FIG. 2, in this embodiment, a lower mold 11 and an upper mold 12 are prepared which are molding molds whose upper and lower surfaces are flat. The upper mold 12 has a through hole 13 that opens in the molding surface of the upper mold 12 in order to mold the leg portion of the optical element molding material. The outer diameters of the lower mold 11 and the upper mold 12 are 12 mm. The cavity formed by these molds is adjusted to a thickness of 3 mm. The through hole 13 for forming the leg portion has an opening diameter of 3 mm, and is provided at three locations on a PCD 3 mm pitch circle. This mold was made of boron nitride.

  Using this boron nitride mold, an optical element molding material comprising a glass block and legs is molded.

  A disk-shaped glass plate was prepared as the molding material 14. The disk-shaped glass plate has a diameter of 8 mm and a height of 3.2 mm.

  In a state where the glass plate is placed on the lower mold 11, the upper surface of the glass plate is heated with an oxyhydrogen flame in the atmosphere and softened, and the upper surface of the glass plate is heated to 800 ° C. Molded with pressing force. Then, it cooled and took out the optical element shaping | molding raw material obtained by shaping | molding.

  In the optical element molding material thus obtained, as in Example 1, the legs are formed in a spherical crown shape, and the glass block is formed in a disk shape having a diameter of 8 mm and a thickness of 3 mm. .

  Next, as a second step, the optical element forming material composed of the glass block and the legs was precisely molded (press molded) to obtain an optical element. The second step of this example was performed in the same manner as in Example 1.

  The dimensions of the optical element as a molded product were a biconcave lens having a diameter of 10 mm, a center height of 1.5 mm, a concave surface R12 mm, and a concave surface R18 mm. The obtained optical element had no trace of the legs of the optical element molding material and had high quality. In addition, the side surface of the optical element is molded with high shape accuracy, and can be incorporated into a lens barrel of an optical device without requiring centering.

  In this embodiment, an optical element molding material for molding an optical element having high optical performance can be manufactured at a lower cost, and the manufacturing cost can be further reduced.

  The shape of the optical element molded in this example is a concave meniscus shape.

  As a first step, as shown in FIG. 3A, a lower mold 21 and an upper mold 22 are used as molds for molding an optical element molding material. A recess 23 is provided on the molding surface of the lower mold 21. The molding surface of the lower mold 21 has a concave spherical surface of R12 mm, and the molding surface of the upper mold 22 is a convex spherical surface of R9 mm. The diameter of the cavity formed by the lower mold 21 and the upper mold 22 is 12 mm. The thickness of the cavity is adjusted to 3 mm. The recess 23 for forming the leg has a spherical crown shape with a radius of 4 mm, an opening diameter of 3 mm, and a depth of 0.29 mm. The recesses 23 were provided at three locations on a PCD 3 mm pitch circle. This mold was made of graphite.

  Using this graphite mold, as shown in FIG. 3B, an optical element molding material composed of a glass block 26 and legs 25 is molded from molten glass. That is, a molten glass lump is prepared as the molding material 24. The weight of the molten glass lump used in this example is 1.3 g. The molten glass lump is obtained by melting the optical glass in a platinum crucible installed in an electric furnace, allowing the molten glass to flow out from the outflow pipe, and receiving a predetermined amount of the molten glass on the lower mold 21 made of graphite. A molten glass lump having a desired weight is obtained.

  The molten glass lump was placed on the lower mold 21 and immediately molded in the atmosphere with a press force of 100 N. At this time, the temperature of the molten glass block was 800 ° C., and the lower mold 21 and the upper mold 22 were 500 ° C. Then, after holding for 5 seconds, the mold was opened, and the optical element molding material obtained by molding was taken out.

  The optical element molding material thus obtained is composed of a plurality of legs 25 and a glass lump 26 as shown in FIG. Each leg 25 is formed in a spherical crown shape. The glass block 26 is formed in a spherical shell shape having a diameter of 12 mm and a thickness of 3 mm.

  Next, as a second step, the optical element molding material composed of the glass block 26 and the legs 25 was precisely molded to obtain an optical element.

  FIG. 3C shows the optical element molding material placed on the lower mold 27 for precision molding. When the optical element molding material comprising the glass block 26 and the legs 25 is placed on a precision molding lower mold 27 having a concave molding surface, the legs 25 support the glass block 26 on the lower mold.

  The precision mold is made of cemented carbide. The lower die 27 is a concave spherical surface of R28 mm, the upper die (not shown) is a convex spherical surface of R9 mm, and also has a cylindrical side die (not shown) so that the side portion of the molding element can be molded. Yes.

  With the legs 25 of the optical element molding material supporting the glass block 26 on the lower mold 27, the lower mold 27 moves in the lateral direction and rises after reaching the position below the upper mold, so that the side mold It is conveyed to the inside and pressed. In this example, the press temperature was 610 ° C., the press force was 3000 N, and the test was performed in a nitrogen atmosphere.

  The dimensions of the optical element thus obtained were a concave meniscus lens having a diameter of 12.4 mm, a center height of 1.5 mm, a convex surface R28 mm, and a concave surface R9 mm. This optical element has high optical performance, and its side surface is molded with high shape accuracy, and can be incorporated into a lens barrel of an optical apparatus without requiring centering.

  According to the above embodiment, even if the lower mold for precision molding is moved with the optical element molding material placed thereon, it can be placed with high accuracy, so that the manufacturing apparatus system can be made inexpensive. . As a result, an optical element having high optical performance can be manufactured at low cost.

FIG. 5 is a diagram illustrating a method for molding an optical element according to Example 1. 6 is a diagram for explaining a method of molding an optical element according to Example 2. FIG. FIG. 6 is a diagram illustrating a method for molding an optical element according to Example 3.

Explanation of symbols

1, 7, 11, 21, 27 Lower mold 2, 12, 22 Upper mold 3, 23 Recess 4, 14, 24 Molding material 5, 25 Leg 6, 26 Glass lump 13 Through hole

Claims (7)

A first step of forming an optical element molding material comprising a glass lump and legs integrally formed with the glass lump,
A second step of obtaining an optical element by press-molding the optical element molding material between a lower mold and an upper mold for precision molding,
In the second step, the glass lump of the optical element molding material is supported on the lower mold by the legs. A first step of forming an optical element molding material comprising a glass lump and legs integrally formed with the glass lump,
A second step of placing the optical element molding material on a convex lower mold, and press-molding the optical element molding material between the lower mold and the upper mold to obtain an optical element; And
In the second step, the glass lump of the optical element molding material is supported on the lower mold by the legs. An optical element molding material for molding an optical element,
A glass lump,
An optical element molding material comprising: a leg formed integrally with the glass block to support the glass block.   The glass block is supported on the lower mold by the legs in the step of press-molding the optical element molding material between the lower mold and the upper mold for optical element molding. 3. The optical element molding material according to 3.   5. The optical element forming material according to claim 3, wherein a plurality of legs are integrally formed on the glass block.   6. The optical element molding material according to claim 5, wherein each leg has a spherical crown shape.   The optical element molding material according to any one of claims 3 to 6, wherein the legs and the glass lump are integrally formed by molding a softened or molten glass with a molding die.

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