JPH08325023A - Optical element forming die and optical element formed by using this optical element forming die - Google Patents

Abstract

PURPOSE: To press form a flat planar glass optical blank and to obviate the occurrence of trouble in appearance on the formed optical element. CONSTITUTION: A mold 1 for press forming of the flat plant glass optical blank softened by heating is provided with a forming surface 2 having a recessed surface shape and the peak part on the outer periphery of this forming surface 2 is provided with grooves 4. The gases existing between the glass forming blank and the forming surface 2 escape outside the mold 1 from these grooves 4 at the time of press forming the flat planar glass optical blank and the transferability of the forming surface is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element molding die for producing a glass lens by pressure molding without polishing, and an optical element molded using the optical element molding die.

[0002]

2. Description of the Related Art In recent years, the need for aspherical lenses has increased to meet the demands for higher performance of the lenses themselves and reduction of the number of lenses in the lens system. For the production of glass lenses, a method of finishing a glass material by spherical polishing has been used for a long time, but it is very difficult to produce aspherical lenses by polishing with the current technology, and it is not profitable. The current situation. Therefore, it is considered to manufacture an aspherical lens by molding. However, since a plastic material that can be easily molded has a limit in optical performance, a technique for molding glass has been actively developed.

For molding using glass, conventionally, a method has been adopted in which spherical glass which has been previously finished to have a radius of curvature close to a desired shape is softened by heating and then pressure-molded by a mold, but before molding. Since it is necessary to process the glass, the cost becomes high. Therefore, in order to further reduce the manufacturing cost, it was considered to heat and soften the flat glass to form it. But,
In the molding method using flat glass, a phenomenon in which air is often accumulated between the glass softened by heating and the mold has been a problem.

Therefore, in order to solve this problem,
In Japanese Patent Laid-Open No. 62-297230, a minute hole 43 is formed in the center of the molds 41 and 42 as shown in FIG. 11, and air 44 between the glass and the molds 41 and 42 is formed through the hole 43.
Is trying to escape.

[0005]

However, the mold 41 disclosed in the above-mentioned Japanese Patent Laid-Open No. 62-297230,
In 42, the following problems occur. That is, since the hole 43 is provided in the center of the molds 41 and 42, a protrusion is formed on the molded lens. In this case, since the diameter of the hole 43 is very small, there is no problem with a normal glass lens of φ10 to 20, but with a minute lens of φ5 or less, the hole 43 is small.
As a result, the protrusion formed by the method becomes relatively large with respect to the lens, which may cause a problem. Further, if the glass is molded in a low viscosity state, the hole 43 may be closed, and it may not be possible to continuously mold using one mold.

The present invention has been made in view of the above-mentioned problems of the prior art, and an optical element molding die that does not cause a defect in the appearance of a molded optical element and an optical element molded using the optical element molding die. The purpose is to provide.

[0007]

In order to solve the above problems, the present invention has the following constitution. The invention according to claim 1 is an optical element molding die used when press-molding an optical element with a pair of molding dies having a concave molding surface on at least one side after softening a plate-shaped optical molding material by heating. A groove or a protrusion was provided at the outermost apex of the molding die provided with the concave molding surface.

According to a second aspect of the present invention, in an optical element obtained by press-molding a heat-softened flat plate-shaped optical molding material by a pair of molding dies, at least one of the optical element molding dies is used. The optical surface was formed in a convex shape.

According to a third aspect of the present invention, a flat optical molding material is heated and softened, and then a pair of molding dies having a concave molding surface on at least one side and a flat surface on the outer peripheral portion of the concave surface. In the optical element molding die used for press-molding the optical element, a groove or a projection is provided on the outer peripheral flat surface of the molding die having the concave surface.

According to a fourth aspect of the present invention, in an optical element obtained by press-molding a heat-softened flat plate-shaped optical molding material with a pair of molding dies, the optical element according to the third aspect is used, and at least one optical surface is used. Was formed into a convex shape, a flat portion was provided on the outer peripheral portion of the optical surface, and a groove or a depression was formed on the outer peripheral flat portion.

[0011]

According to the structure of claim 1, when the flat optical molding material is press-molded, the flat optical molding material heat-softened by the groove or the projection provided at the outermost vertex of the molding die and the molding. A gap is formed between the outer peripheral surface of the mold molding surface and the gap serves as an escape path for the gas existing between the optical molding material and the molding die at the time of molding to expel the gas to the outside of the molding die.

The function of the second aspect functions to obtain the optical element having good transferability obtained by using the function of the first aspect.

According to the structure of claim 3, in the case of obtaining an optical element having a flat portion outside the optical surface due to the relation of the frame or the like, a groove formed in the concave flat optical portion outside the optical molding surface of the molding die or By the projection, a gap is formed between the flattened optical molding material and the molding die which are heat-softened, and the gap serves as an escape path for the gas existing between the optical molding material and the molding die at the time of molding, It acts to expel the gas out of the mold.

The action of claim 4 is an optical element having good transferability obtained by using the action of claim 3, and has an action of obtaining an optical element having protrusions or depressions in the outer peripheral flat portion of the optical element.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 shows an optical element molding die according to Embodiment 1 of the present invention. FIG. 1 (a) is a plan view seen from the molding surface side, and FIG. 1 (b) is a central longitudinal sectional view. 2 is a side view showing the molded optical element.

In FIG. 1, reference numeral 1 denotes an optical element molding die (hereinafter referred to as a molding die), which is provided with a concave molding surface 2. The molding surface 2 is formed in a desired aspherical shape. The shape of the outer periphery of the molding die 1 (the outer peripheral portion of the molding surface 2) is an acute angle so that the flat glass optical material can easily flow to the molding surface 2 of the molding die 1, and the top portion 3 has a depth. Four semicircular grooves 4 each having a width of 0.2 mm and a width of 0.5 mm are radially provided. For example, when molding a lens 5 having a desired lens outer diameter of φ7 as shown in FIG. 2, the groove 4 does not remain in the lens 5 after the centering of the lens molded by the molding die 1. As described above, the mold diameter is set to φ9 so that it is provided outside φ7.

The lens 5 shown in FIG. 2 has a plano-convex shape in which one surface is molded into a convex surface by the molding die 1 and the other surface is molded into a flat surface with a molding die having a planar molding surface. Then, it is removed at the time of centering so that the portion formed by the groove 4 provided in the molding die 1 does not remain.

Next, a case where an optical element is molded using the molding die 1 of this embodiment will be described with reference to FIG. A mold having a planar molding surface 10 is used as an upper mold 11, and a molding mold 1 having the concave molding surface 2 is used as a lower mold 12, and the upper mold 11 is arranged so that the molding surface 10 and the molding surface 2 face each other. And lower mold 12
Are arranged so as to face each other vertically, and the flat glass optical material 14 which is heated and softened while being placed on the holder 13 is conveyed to a molding position between the upper mold 11 and the lower mold 12 by a conveying device (not shown). After the holder 13 is conveyed to the molding position, the main shaft 15 is driven by a servomotor or the like to move the lower mold 12 upward, and the flat glass optical material 1
4 is lifted so as to be supported by the top portion 3 and is molded by the molding surface 10 and the molding surface 2.

When the flat glass optical material 14 is molded, the groove 4 of the molding die 1 (lower mold 12) is shaped into the molding surface 2 of the molding die 1 and the flat glass optical material at the time of molding, as shown in FIG. It acts to release the gas trapped between the materials 14. FIG. 4A shows the moment when the flat glass optical material 14 comes into contact with the top portion 3 of the molding die 1. At this time, gas is present in the void 16 formed between the mold 1 and the flat glass optical material 14. FIG. 4B shows a process in which the flat glass optical material 14 bites into the molding die 1 during pressing. At this time, the gas in the void 16 escapes from the groove 4 to the outside of the mold 1 along the direction of the arrow. FIG.
In (c), all the gas in the void portion 16 escapes, and the molding die 1
The molding surface 2 of 1 shows the state in which the glass optical material 14 is pressed. In this state, pressure is also applied to the groove 4 so that glass enters the groove 4 and closes the groove 4, but the gap 1 is already formed.
Since there is no gas in 6, the transfer accuracy of the molding surface 2 is improved.
Although the groove 4 is transferred during molding, it is removed by centering, so that no problems occur in the optical performance of the lens and the frame.

When the surface accuracy of the optical element molded by using the molding die 1 of this embodiment was measured, no deterioration of the surface accuracy due to the entrainment of gas was observed, and transfer was performed almost as the molding surface 2 of the molding die 1. Was there.

[Second Embodiment] FIG. 5 shows a second embodiment according to the present invention.
FIG. 5A is a plan view seen from the molding surface side, FIG. 5B is a central longitudinal sectional view, and FIG.
FIG. 4 is a side view showing a molded optical element.

In the second embodiment of the present invention, a molding die for molding the lens 21 having a shape as shown in FIG. 6 will be described. As shown in FIG. 6, this lens 21 has a plano-convex shape in which one surface is an aspherical convex surface and the other surface is a flat surface, and a flat portion 22 is provided on the outer periphery of the optical surface 21a of the lens 21. . The flat portion 22 is an indispensable portion in terms of the framework of the lens, and if it is formed by post-processing, problems will occur in cost and accuracy, so it must be formed at the same time as the optical surface 21a. However, if there is a flat portion 22 on the outer circumference of the optical surface 21a, the flat glass optical material 1
Since the contact area between the flat portion 22 and the flat portion 22 is large, the gas existing between the optical molding surface of the molding die and the glass optical material 14 is hard to escape, and the transferability is significantly impaired.

As shown in FIG. 5, the molding die of this embodiment has
Four protrusions 26 were provided on the flat portion 25 outside the optical molding surface 24 having the concave shape of the molding die 23. The height of the protrusion 26 was 0.3 mm and the diameter was 0.8 mm. Other configurations are the same as those in the first embodiment.

The operation of this embodiment will be described. Note that only the differences from the first embodiment are shown. The protrusion 26 of the molding die 23 is a flat portion 25 outside the optical molding surface 24 of the molding die 23 during molding.
And a flat glass optical material 14 (see FIG. 3), a gap is created, and the gas existing between the optical molding surface 24 and the glass optical material 14 is released from the gap. Although the projection 24 is transferred to the flat portion 22 during molding, it is formed in a concave shape, so that the optical element does not cause any trouble on the framework of the lens.

When the surface accuracy of the molded product molded using the molding die 23 of this embodiment was measured, as shown in FIG. 7, no deterioration of the surface accuracy due to the entrainment of gas was observed, and PV =
It was 0.1 μm, which was transferred almost as the molding surface 24 of the molding die 23. For comparison, FIG. 8 shows the surface accuracy of the optical element in the case of using a conventional molding die having no protrusion under the same conditions. In this case, the gas could not escape and remained,
= 1.3 μm, the surface accuracy is extremely poor.

[Third Embodiment] FIG. 9 shows a third embodiment according to the present invention.
9A is a plan view seen from the optical molding surface side, and FIG. 9B is a central longitudinal sectional view. The molding die of this embodiment molds the same lens shape as that of the second embodiment shown in FIG. 5, and only the points different from the second embodiment are shown. As shown in FIG. 9, the molding die 31 has a molding die 31.
The optical molding surface 32 is extended by 0.2 mm, and the flat portion 33 outside the optical molding surface 32 has a width of 2 mm and a depth of 0.2 mm.
The groove 34 of No. 4 was provided at four positions in the cross direction. That is, the groove 3
The bottom surface of No. 4 serves as a convex portion (not shown) of the molded product flat portion 22 (see FIG. 6), and the portion of this convex portion serves as a contact portion with the lens frame.

The operation of this embodiment will be described. Note that only the differences from the first embodiment are shown. The groove 34 of the molding die 31 is formed in the flat portion 33 and the glass optical material when the flat portion 33 outside the optical molding surface 32 of the molding die 31 and the flat glass optical material 14 (see FIG. 3) come into contact with each other during molding. A gap is created between the gaps 14, and the gas trapped between the optical molding surface 32 and the glass optical material 14 is released from the gap.

The groove 34 is transferred in molding, but the groove 3
Since the bottom surface of 4 serves as a convex portion (not shown) of the flat portion 22 of the molded product, and this convex portion serves as a contact portion with the lens frame, there is no problem in terms of the framework.

When the surface accuracy of the optical element molded by using the molding die 31 according to this example was measured, as shown in FIG. 10, no deterioration of the surface accuracy due to the entrainment of gas was observed, and the molding accuracy of the molding die 31 was almost the same. The transfer was performed as in the optical molding surface 32. Further, since the flat portion 33 of the molding die 31 is processed only by the groove, the flat portion 33 is easier to process than the projection of the second embodiment, and it is highly accurate and inexpensive.

In the embodiments of the present invention, the plano-convex lens was described. However, not only the plano-convex lens, but also the bi-convex lens, the convex meniscus lens, and all other lenses having a convex portion are flat glass optical materials. Needless to say, it is possible to obtain the same action and effect as those of the above-mentioned respective examples even if it is formed by using.

[0031]

As described above, according to the present invention, the following effects can be obtained. According to the invention of claim 1, in the case where the flat optical molding material is softened by heating and molded, a gap can be formed between the molding die and the optical molding material by the groove or the protrusion provided in the molding die. It is possible to perform molding while eliminating the gas existing between the molding die and the optical molding material. As a result, the entrainment of gas can be formed in the molded optical element and the defective shape is prevented.

According to the second aspect of the present invention, it is possible to obtain an inexpensive optical element in which the molding surface of the molding die is accurately transferred without gas entrapment by using the heated flat plate-shaped optical molding material.

According to the invention of claim 3, when an optical element having a flat surface on the outer circumference of the optical surface is molded by heating and softening a flat optical molding material, a groove or a protrusion provided in the flat portion of the molding die. Thus, a gap can be formed between the molding die and the optical molding material, and the molding can be performed while eliminating the gas existing between the molding die and the optical molding material. As a result, it is possible to form a molded optical element with gas entrapment and prevent a defective shape, and to form an inexpensive and high-precision optical element in one shot without causing problems on the framework of the flat surface. it can.

According to the fourth aspect of the present invention, the heat-softened flat plate-shaped optical molding material is used to have a flat surface on the outer circumference of the optical surface, and the molding surface of the molding die is accurately transferred without gas entrapment. It is possible to obtain an inexpensive optical element that does not have a defect on the framework of the flat surface.

[Brief description of drawings]

FIG. 1 shows an optical element molding die of Example 1 according to the present invention, FIG. 1 (a) is a plan view seen from the molding surface side, and FIG. 1 (b).
Is a central longitudinal sectional view.

FIG. 2 is a side view showing an optical element molded by using the optical element molding die of Example 1 according to the present invention.

FIG. 3 is a view schematically showing an optical element molding die for molding the optical element shown in FIG.

FIG. 4 is an explanatory view showing a molding process of an optical element using the optical element molding die of Example 1 according to the present invention, and FIG. 4 (a) is a glass optical material having a flat top portion of the optical element molding die. Fig. 4 (b) shows the process in which the glass optical material bites into the optical element molding die during pressing, and Fig. 4 (c) shows the molding surface of the optical element molding die as the glass optical material. It shows the state of applying pressure.

5 shows an optical element molding die of Example 2 according to the present invention, FIG. 5 (a) is a plan view seen from the molding surface side, and FIG. 5 (b).
Is a central longitudinal sectional view.

FIG. 6 is a side view showing an optical element molded by using the optical element molding die of Example 2 according to the present invention.

FIG. 7 is a diagram showing the surface accuracy of an optical element molded using the optical element molding die of Example 2 according to the present invention.

FIG. 8 is a diagram showing surface accuracy of an optical element molded using a conventional optical element molding die.

9 shows an optical element molding die of Example 3 according to the present invention, FIG. 9 (a) is a plan view seen from the molding surface side, and FIG. 9 (b).
Is a central longitudinal sectional view.

FIG. 10 is a diagram showing the surface accuracy of an optical element molded by using the optical element molding die of Example 3 according to the present invention.

FIG. 11 is a central longitudinal cross-sectional view showing a conventional optical element molding die.

[Explanation of symbols]

 1, 23, 31 Optical element molding die 2, 24, 32 Molding surface 3 Top part 4, 34 Groove 5, 21 Lens 14 Glass optical material 16 Void part 22, 25, 33 Flat part 26 Protrusion

Claims (4)

[Claims] 1. An optical element molding die used when press-molding an optical element with a pair of molding dies having a concave molding surface on at least one side after softening a flat optical molding material by heating and softening the concave shape. An optical element molding die, characterized in that a groove or a protrusion is provided at the outermost apex of the molding die having the molding surface. 2. An optical element obtained by press-molding a heat-softened flat plate-shaped optical molding material with a pair of molding dies, wherein at least one optical surface is formed in a convex shape. An optical element molded using a molding die. 3. A flat optical molding material is heated and softened, and then an optical element is pressed by a pair of molding dies having a concave molding surface on at least one side and a flat surface on the outer periphery of the concave surface. An optical element molding die used for molding, characterized in that a groove or a protrusion is provided on a flat outer peripheral surface of the molding die having the concave surface. 4. An optical element obtained by press-molding a heat-softened flat plate-shaped optical molding material with a pair of molding dies, wherein at least one optical surface is formed into a convex shape, and a flat portion is formed on an outer peripheral portion of the optical surface. An optical element formed by using the optical element according to claim 3, wherein a groove or a depression is formed in the flat portion while providing a portion.