JP2000053428A - Production of optical element, its producing device and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the effect in discharging gas in a forming die during the forming and to prevent the generation of an area such as an air reservoir by providing a gas discharge means at a spot corresponding to at least one flat part of a pair of forming dies to form an element having a curved-surface part and the flat part by compacting an optical element material. SOLUTION: An optical element material is compacted between a pair of forming dies to produce an optical element having a curved-surface part and a flat part. In this case, a ventilating groove 4 as a gas discharge means is provided at a flat part 3 corresponding to the flat part on the periphery of an optical face die 2 forming a curved-surface part, in at least one die 1 of the pair of dies to eliminate the generation of an air reservoir. Plural ventilating grooves 4 are preferably furnished in the radical direction of the forming die 1, and the curved-surface part of a formed optical element is desirably used as an optical face and the flat part as a non-optical face. The protrusion of the flat part of the optical element formed at the position of the ventilating groove 4 can be left as such if necessary, or is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for manufacturing an optical element such as a glass lens (particularly, an optical element for preventing air pockets between a lens material and a molding die during lens molding). And an optical element produced thereby.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a glass lens, a pre-measured glass block is plasticized by an induction heating method using a high frequency or the like, instead of a polishing and finishing processing method involving a complicated process. It is known to form an optical element by directly processing into a predetermined shape by a precision press made of a mold.

[0003] Such an optical element molding apparatus includes:
For example, a reheat press as schematically shown in FIG. 8 is used. When a biconvex lens is formed by this reheat press, as shown in FIG. 8, dies 15, 16 connected to heat-insulating joints 17 arranged coaxially and vertically, and supported by the dies 15, 16, respectively. The cavities 13 and 14 forming the concave optical surface mold are vertically arranged opposite to each other, and further, the upper heat insulating joint 17 is connected to the cylinder 18 and moves up and down by the operation of the cylinder 18.

[0004] Then, as shown in FIG. 8 (a), the cylinder 18 is operated in the upward direction, and the two cavities 13, 1 are moved.
A material 19 composed of, for example, a spherical glass lump is put between the four,
The material 19 is heated H to soften it.

[0005] Next, as shown in FIG. 8 (b), the cylinder 18 is actuated downward and pressurized, so that the softened material 19 is filled with the optical surface mold 20 including the cavities 13 and 14 and the outer flat portion 21. The space formed by is filled.

After cooling for a predetermined time, as shown in FIG.
If the molded product is taken out by opening the space between 3 and 14, a biconvex lens 22 in which the optical surface 20A and the outer peripheral flat portion 21A are copied by transfer is formed as shown in FIG. 8D.

FIG. 9 shows a process in which the material 19 shown in FIG. 8 is filled into the molds formed in the upper and lower cavities 13 and 14 by pressurization. When molding from a spherical material, a desired lens can be obtained by gradually contacting the material and the mold from the center to the outside.

[0008]

However, in the conventional lens molding by such a reheat press,
Air may remain inside the product due to the high pressure in the central part and the outer peripheral flat part of the upper and lower molds.

Depending on the shape of the ordinary mold and the material, the pressure gradually decreases from the center to the outside in many cases. In particular, when molding a meniscus lens, the pressure tends to increase at the outer peripheral portion. Since the outer peripheral portion is sealed first, air is easily sealed.

FIG. 10 is a schematic view showing a main part when a convex lens is formed by a reheat press, in which the material 19 is spherical. The optical surface mold 29 is formed by being supported by a die 27 below. Cavity of the lower mold
It may be referred to as a lower mold. ) 25, the upper die 2
(A) in which an upper mold cavity (hereinafter, may be referred to as an upper mold) 26 which is supported by the mold 7 and in which a projection 28 is formed is arranged to face each other, and a material 19 is arranged between the two cavities. Therefore, when the material 19 is heated and softened and then pressurized to the state shown in FIG. 10B, an air pocket 30 is likely to be formed at the boundary between the projection 28 of the upper die 26 and the outer flat portion 33 as shown in the figure. .

Then, even if the pressurization is continued as shown in FIG.
After the pressurization, the air reservoir 30 remains in the mold, and a desired product may not be obtained.

FIG. 11 shows a case where the same reheat press as described above is used and the material 31 is in a plate shape.
In this case, as shown in the figure, at the stage of FIG. 11C, the same phenomenon as in the case of FIG. 10 occurs, but is finally eliminated.

However, in this case, as shown in FIG. 11B, contrary to the case of FIG. 10, the air pocket 3 is formed on the ridge of the optical surface mold 29 near the boundary with the outer peripheral flat portion 32 of the lower mold 25.
0 tends to occur and a desired product may not be obtained in the same manner as described above. Therefore, it is important to prevent the occurrence of such air pockets regardless of the shape of the material.

In such a molding apparatus, as measures for preventing air from being blocked in the molding die or for improving the air flow, for example, Japanese Patent Application Laid-Open Nos.
It is disclosed by JP-A-163029. But,
Each of these has a different purpose and there is no effective solution to the above problem.

Accordingly, an object of the present invention is to provide a method of manufacturing an optical element capable of obtaining a desired optical element by enhancing the effect of discharging gas from a mold during molding and preventing the occurrence of a portion such as an air pocket. It is to provide a manufacturing apparatus and an optical element.

[0016]

That is, the present invention provides a method for manufacturing an optical element having a curved surface portion and a flat portion by pressing an optical element material between a pair of molding dies. In at least one of the above, a gas discharging means is provided at a position corresponding to the flat portion, and gas between the pair of molds is discharged through the gas discharging means (hereinafter referred to as a manufacturing method). It is related.

According to the present invention, at least one of the molding dies is provided with a gas discharging means at a position corresponding to the flat portion, so that the gas in the molding dies can be effectively discharged by the gas discharging means during molding. it can. As a result, it is possible to provide a method for manufacturing a desired optical element without causing a phenomenon such as an air pocket.

Further, the present invention is an apparatus for manufacturing an optical element having a curved portion and a flat portion by pressing an optical element material between a pair of molds, wherein at least one of the pair of molds is used. The present invention relates to an optical element manufacturing apparatus (hereinafter, referred to as a manufacturing apparatus) in which gas discharging means is provided at a position corresponding to the flat portion.

According to the present invention, since the apparatus is based on the above-described manufacturing method, it is possible to provide a manufacturing apparatus capable of manufacturing a desired optical element with good reproducibility.

According to another aspect of the present invention, there is provided an optical element having a curved surface portion and a flat portion, which is manufactured by pressure molding, wherein the convex portion formed at the time of pressurization exists in the flat portion. It relates to an optical element (hereinafter, referred to as an optical element).

According to the present invention, a convex portion is formed on a flat portion during pressurization, and this convex portion can be used for, for example, processing after molding and positioning.

In the optical element of the present invention, the convex portion formed on the flat portion may be left as it is or may be removed. Further, the flat portion including the convex portion may be removed. The element is a concept including any of these forms.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above-described manufacturing method, manufacturing apparatus and optical element, it is desirable to form an optical element with the curved surface as an optical surface and the flat portion as a non-optical surface.

The optical element material is disposed between an upper mold and a lower mold which are coaxially opposed to each other, and the material is pressed by the upper mold and the lower mold while heating this material. In manufacturing an optical element, at least one ventilation recess is provided on a flat surface of an outer peripheral portion of the upper mold and / or the lower mold as the gas discharging means for discharging gas between the upper mold and the lower mold. It is desirable to provide one.

In this case, a groove serving as the ventilation recess may be provided in a radial direction of the mold, and the groove may be provided radially. And it is desirable to use the above-mentioned mold for reheat press.

It is preferable that the formed optical element is post-processed with reference to the convex portion formed integrally with the flat portion at the position of the gas discharging means.

In addition, at the position of the gas discharging means, a convex portion formed integrally with the flat portion may be left as it is, or the convex portion may be removed.

As described above, it is desirable to manufacture a convex lens and a concave lens. Glass, plastic, or the like can be used as a material for these lenses.

Thus, it is possible to suitably manufacture the optical element for the optical pickup and the optical element for the lens barrel.

Hereinafter, the present invention will be described in more detail with reference to embodiments.

FIG. 1 shows a cavity for producing a convex lens serving as a lower mold for a reheat press, (a) is a plan view,
(B) is an Ib-Ib line sectional view of (a). The upper mold cavity is not shown.

As shown in the figure, a concave optical surface mold 2 is formed on the upper surface of the cavity 1, a flat portion 3 is formed on the outer periphery thereof, and a groove 4 is provided in a part of the outer peripheral flat portion 3. I have.

As described above with reference to FIG. 11, when such a meniscus-shaped lens is formed from a plate-like material, there is a high possibility that air pockets remain in the optical surface mold 2 having the convex surface of the lens. This also tends to occur when the pressure between the upper and lower cavities of the outer peripheral flat portion 3 is narrow and the pressure becomes high. In particular, in the case of molding from a plate-like material, the air inside the cavity forming the optical surface of the convex lens is easily sealed by the edges of the optical surface mold 2 and the outer peripheral flat portion 3, so that the probability of occurrence of air pockets is high. .

That is, when the meniscus lens is formed, the pressure increases at the outer peripheral flat portion 3 and air remains in the low pressure portion. This phenomenon rarely occurs even when a spherical material is used. That is, the amount of deformation is too large, so that the material is not gradually filled from the central portion and goes around to the outer peripheral portion first. This phenomenon appears remarkably when a plate-like material is used.

Accordingly, as shown in FIG. 1, by providing the groove 4 in a part of the outer peripheral flat portion 3, air which tends to accumulate on the low pressure ridge portion of the optical surface mold 2 is sealed at this portion. It is not discharged before and remains as an air pocket, which is effective for transferring the shape of the optical surface mold 2 of the cavity 1 as it is.

It is more effective to provide the grooves 4 at a plurality of positions according to the type and size of the lens. FIG. 2 shows grooves 4 in the cross-shaped radial direction provided on the outer peripheral flat portion 3 of the cavity 1A, and FIG. 3 shows grooves 4 provided on the outer peripheral flat portion 3 of the cavity 1B at eight radial positions. Things.

FIGS. 4 to 6 show a convex lens produced by the above-mentioned mold.

First, FIG. 4 shows a convex lens 5 obtained by the molding die shown in FIG.
(A) is a front view, (b) is a bottom view, and (c) is a bottom perspective view. Therefore, a convex portion 9 is formed on the outer peripheral flat portion 7 of the lens 5 corresponding to the groove 4.

FIG. 5 is different from FIG. 4 only in the number of the convex portions 9, and differs from the convex lens 5 obtained by the molding die shown in FIG.
A is shown in FIG. 6, and FIG. 6 shows a convex lens 5B obtained by the molding die shown in FIG. 3. In each case, a convex portion 9 is formed at a position corresponding to the groove 4 provided in each molding die.

However, as already described with reference to FIG. 10, particularly when the meniscus lens is molded from a spherical material, air traps are formed at the boundary between the surface of the upper mold projection 28 and the outer flat portion 33. May remain. This also occurs because the space between the upper and lower cavities is narrow and the pressure tends to increase as in the case of the outer peripheral flat portion 32 on the opposite side.

Therefore, as shown in FIG. 7, it is effective to provide the groove 12 in the outer peripheral flat portion 13 also in the cavity 10 for the upper die, similarly to the lower die shown in FIG. Thus, the projection 1 of the cavity 10 forming the concave surface of the lens
Air that easily accumulates from 1 to the outer peripheral flat portion 13 can be discharged. In this case, of course, a plurality of grooves may be provided.

The convex portion 9 can be used as a reference line for cutting out a large number of lenses simultaneously cut from a plate-like material, as described later, or for positioning at the time of setting. After that, the protrusion 9 may be left as it is, the protrusion 9 may be removed by polishing or the like, and the peripheral flat portion 7 including the protrusion 9 may be removed.

As described above, in order to prevent the formation of air pockets, it is effective to provide means for discharging air. However, the shape of the material for molding the lens is also an important factor for preventing the formation of air pockets. It is. That is, the cause of the formation of the air pocket depends on the shape of the mold and the material.

Conventionally, such a meniscus lens has been formed using an ellipsoidal material. This is because the ellipsoidal material has a shape similar to the shape of the optical surface, and thus is likely to be gradually brought into contact from the center. However, since the positioning of the ellipsoidal material with respect to the mold is difficult, it is difficult to form the ellipsoidal material by regulating the outer peripheral side surface. That is, the mold may be damaged due to excessive filling in only one direction. In order to prevent this, post-processing such as centering is necessary, which causes an increase in cost. In addition, centering is extremely difficult with a lens having a small convexity and a shape close to flat.

Therefore, when one lens is molded by one molding die, it is effective to use a spherical material.

As described above, one optical element can be obtained with one ellipsoidal or spherical material, but a large number of optical surfaces can be formed on one material with a flat material. There is a merit that can be.

Therefore, for example, when manufacturing a large number of lenses of the same shape, use a mold for molding a large number of lenses at the same time.
A flat plate material is used as the material, and a groove for air discharge as in the present embodiment is indispensable for a molding die used for this.

The above embodiment can be variously modified based on the technical idea of the present invention. For example, although the above-described groove for air discharge is provided in the horizontal direction, a vertical groove may be formed in the cavity.

Although all the grooves are provided in the cavity, grooves may be provided in the material itself in advance.

The shape and number of the grooves are not limited to the above-mentioned embodiments, but can be changed as appropriate.

According to the present embodiment, since the air discharging groove is provided at a position communicating with a position where air is likely to be generated during lens molding by reheat press, the groove is located at a position where air is likely to be stored at the time of pressure molding. Air is effectively exhausted.
Therefore, it is possible to form a good lens in which the desired optical surface is duplicated without leaving an air pocket.

The flat part 7 of the lens thus molded
The protrusions 9 corresponding to the above-mentioned grooves can be effectively used as a reference for a cutting position when cutting out a lens group formed for a large number of flat plate materials into individual lens size dimensions, for example. . In addition, it can be used as positioning for lens setting.

[0053]

As described above, according to the present invention, when an optical element having a curved surface portion and a flat portion is manufactured by pressing an optical element material between a pair of molds, at least one of the pair of molds is used. In the above, gas discharging means is provided at a position corresponding to the flat portion, and gas between the pair of molding dies is discharged through the gas discharging means, so that gas in the molding die at the time of molding is effectively discharged by the gas discharging means. can do. As a result, a desired optical element can be obtained without causing a phenomenon such as an air pocket generated between the molded article and the mold.

Further, an optical element having a convex portion corresponding to the gas discharging means on a flat portion of the optical element can be obtained, and this convex portion can be used for post-processing, positioning and the like.

[Brief description of the drawings]

FIG. 1 shows a cavity of a lower die for reheat press according to an embodiment of the present invention, wherein (a) is a plan view and (b) is a cross-sectional view taken along the line Ib-Ib of (a).

FIGS. 2A and 2B show other cavities, wherein FIG. 2A is a plan view and FIG. 2B is a cross-sectional view taken along line IIb-IIb of FIG.

3A and 3B show still another cavity, wherein FIG. 3A is a plan view and FIG. 3B is a sectional view taken along line IIIb-IIIb of FIG. 3A.

4A and 4B show a molded lens, wherein FIG. 4A is a front view, FIG. 4B is a bottom view, and FIG. 4C is a bottom perspective view.

5A and 5B show other lenses, wherein FIG. 5A is a front view,
(B) is a bottom view.

6A and 6B show still another lens, wherein FIG. 6A is a front view,
(B) is a bottom view.

7A and 7B show a cavity of the upper die for reheat press, in which FIG. 7A is a cross-sectional view taken along line aa of FIG. 7B and FIG. 7B is a bottom view.

8A and 8B show a step of forming a biconvex lens by a reheat press, wherein FIG. 8A shows a pre-pressurized state, FIG. 8B shows a pressurized state, FIG. It is the perspective view which fractured | ruptured and showed the part.

FIGS. 9A and 9B are schematic views of a main part in a process of filling a material at the time of forming a biconvex lens by a reheat press, wherein FIG. 9A shows a state before filling, FIG. 9B shows a state during filling, and FIG.

FIGS. 10A and 10B are schematic views of a main part showing the state of generation of air pockets at the time of forming a convex lens from a spherical material by reheat pressing, in which FIG.
(C) shows the progress of pressurization, and (d) shows the end of pressurization.

FIGS. 11A and 11B are schematic views of a main part showing the state of occurrence of air pockets when a convex lens is formed from a plate-like material by a reheat press, wherein FIG.
(C) shows the progress of pressurization, and (d) shows the end of pressurization.

[Explanation of symbols]

1, 1A, 1B, 10, 13, 14 ... cavities, 2
... Optical surface type, 3, 7, 13 ... Flat outer peripheral part, 4, 12
... grooves, 5 5A, 5B ... convex lenses, 6 ... optical surfaces, 8 ... concave portions, 9 ... convex portions, 11 ... projecting portions, 15, 16 ... dies, 17 ...
Insulation joint, 18 ... cylinder, 19 ... material, 22 ... biconvex lens, 30 ... air pocket, H ... heating

Claims (30)

[Claims] When manufacturing an optical element having a curved surface portion and a flat portion by pressing an optical element material between a pair of molding dies, at least one of the pair of molding dies corresponds to the flat portion. A method for manufacturing an optical element, comprising: providing gas discharge means at a location; and discharging gas between the pair of molds through the gas discharge means. 2. The method for manufacturing an optical element according to claim 1, wherein an optical element having the curved surface as an optical surface and the flat portion as a non-optical surface is formed. 3. An optical element material is disposed between an upper mold and a lower mold which are coaxially opposed to each other, and the material is pressed by the upper mold and the lower mold while heating the material. In manufacturing an optical element, at least one ventilation recess is provided on a flat surface of an outer peripheral portion of the upper mold and / or the lower mold as the gas discharging means for discharging gas between the upper mold and the lower mold. The method for manufacturing an optical element according to claim 1, wherein one is provided. 4. The method of manufacturing an optical element according to claim 3, wherein a groove serving as the ventilation recess is provided in a radial direction of the mold. 5. The method for manufacturing an optical element according to claim 4, wherein said grooves are provided radially. 6. The method for manufacturing an optical element according to claim 1, wherein a reheat press mold is used. 7. The method of manufacturing an optical element according to claim 1, wherein the molded optical element is post-processed at a position of the gas discharge unit with reference to a convex part formed integrally with the flat part. 8. A projection formed integrally with the flat portion at the position of the gas discharge means, wherein the projection is left as it is.
4. The method for producing an optical element described in 1. above. 9. The method for manufacturing an optical element according to claim 1, wherein a convex portion formed integrally with the flat portion at the position of the gas discharging means is removed. 10. The method for manufacturing an optical element according to claim 1, wherein a convex lens is manufactured. 11. The method according to claim 1, wherein the concave lens is manufactured. 12. The method for manufacturing an optical element according to claim 1, wherein an optical element for an optical pickup is manufactured. 13. An optical element for a lens barrel is manufactured.
4. The method for producing an optical element described in 1. above. 14. An apparatus for manufacturing an optical element having a curved surface portion and a flat portion by pressing an optical element material between a pair of molds, wherein the flat portion is formed on at least one of the pair of molds. A device for manufacturing an optical element, wherein a gas discharge means is provided at a corresponding position. 15. The apparatus for manufacturing an optical element according to claim 14, wherein an optical element having the curved surface as an optical surface and the flat portion as a non-optical surface is formed. 16. The optical element material is disposed between an upper mold and a lower mold that are coaxially opposed to each other, and the material is pressurized by the upper mold and the lower mold while the material is being heated. Wherein the gas discharging means for discharging gas between the upper mold and the lower mold is provided, and a flat outer peripheral portion of the upper mold and / or the lower mold is provided. The surface is provided with at least one ventilation recess.
2. The apparatus for manufacturing an optical element described in 1. above. 17. The apparatus for manufacturing an optical element according to claim 16, wherein a groove serving as the ventilation recess is provided in a radial direction of the mold. 18. The apparatus according to claim 17, wherein the grooves are provided radially. 19. The apparatus for manufacturing an optical element according to claim 14, wherein a reheat press type is used. 20. The apparatus for manufacturing an optical element according to claim 14, wherein a convex lens is manufactured. 21. The apparatus for manufacturing an optical element according to claim 14, wherein a concave lens is manufactured. 22. The apparatus for manufacturing an optical element according to claim 14, wherein an optical element for an optical pickup is manufactured. 23. The apparatus for manufacturing an optical element according to claim 14, wherein an optical element for a lens barrel is manufactured. 24. An optical element having a curved surface portion and a flat portion and produced by pressure molding, wherein the convex portion formed at the time of pressurization exists in the flat portion. 25. The optical element according to claim 24, wherein the protrusion is provided in a radial direction. 26. The projection is provided radially,
An optical element according to claim 24. 27. The optical element according to claim 24, wherein the optical element is a convex lens. 28. The optical element according to claim 24, wherein the optical element is a concave lens. 29. The optical pickup according to claim 2, which is used for an optical pickup.
4. The optical element according to 4. 30. The optical element according to claim 24, which is for a lens barrel.