JP2011168411A - Preform for molding optical element and method of molding optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preform for molding an optical element which allows a high quality optical element to be molded inexpensively in a simple manner, and to provide a method of molding an optical element using such a preform. <P>SOLUTION: The preform for molding an optical element includes: an element body forming part 12; an annular flange forming part 14 arranged in the outer peripheral part of the element body forming part 12; and an annular edge forming part 16 which is arranged on the outer peripheral part of the flange forming part 14 and forms annular level difference S1, S2 on both peripheral parts of a front surface side and a rear surface side of the flange forming part 14, wherein the outer peripheral part of the edge forming part 16 is abutted on the inner peripheral surface of a drum mold while leaving both of the level difference when heated, compressed and deformed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical element molding preform as an intermediate in an optical element molding method for molding an optical element by compression molding, and an optical element molding method using the preform.

  For example, Patent Document 1 discloses a conventional method for manufacturing an optical element such as a lens or a prism used in an optical apparatus. As shown in FIG. 14, after making the preform 1 from an optical material such as plastic or glass, the preform 1 is subjected to heat compression molding inside a mold 2 corresponding to the optical element, for example, As shown in FIG. 15, the optical element 5 having the optical element body 3 and the flange portion 4 that supports the optical element body 3 is manufactured.

  However, in the conventional method, the preform 1 constitutes the clearance of the mold 2, that is, the mold 2 at the time of heating and compression due to excessive or insufficient amount of the preform 1 or deviation of the installation position in the mold 2. The upper die 6, the lower die 7 and the barrel die 8 flow into each other's joints to generate burrs B, or the flange portion 4 does not reach the barrel die 8 but forms the edge portion. There was a risk of not being able to. In such a case, the molded optical element cannot be accurately positioned on a device such as a camera.

  In recent years, in particular, there is an increasing demand for miniaturized camera lenses such as digital cameras built into mobile phones and cameras used in medical devices, and thus lenses used in mobile phones and medical devices are It is an ultra-compact lens and requires high optical accuracy.

For this reason, optical elements with reduced quality that cannot be accurately positioned within the instrument cause significant defects in optical accuracy.
In particular, a plurality of lenses mounted on an ultra-compact camera or the like are often used in combination, and if there is a burr, the positioning reference plane of the lens shifts, making it difficult to align the optical axes of the lenses.

  In view of this, Patent Documents 2 and 3 propose methods for solving the problem that the lens is molded with burrs. In the method disclosed in Patent Document 2, the occurrence of burrs is prevented by controlling the deformation speed of the preform by adjusting the temperature and pressure of the preform. On the other hand, Patent Document 3 adopts a method in which the linear expansion coefficient of the upper mold and the lower mold constituting the mold and the linear expansion coefficient of the body mold are different from each other.

JP-A-5-177725 JP-A-8-127077 JP 2000-326354 A

  However, the methods of Patent Documents 2 and 3 have a problem that the molding conditions and the configuration of the mold are complicated, and it takes a lot of time and money to mold the optical element.

  In order to solve the above-mentioned problems of the prior art, the present invention provides an optical element molding preform capable of molding a high-quality optical element easily and inexpensively, and an optical element molding method using such a preform. Is to provide.

  An optical element molding preform according to the present invention is a preform that is placed in a space surrounded by an upper mold, a lower mold, and a body mold, and is molded into an optical element by being heated and compressed. An element main body forming portion for forming an element main body, an annular flange forming portion having a first thickness disposed on the outer peripheral portion of the element main body forming portion, and an outer peripheral portion of the flange forming portion And an annular edge forming portion having a second thickness smaller than the first thickness and forming an annular step on each of the peripheral portions of the front surface side and the back surface side of the flange forming portion. When deformed by being heated and compressed, the outer peripheral portion of the edge forming portion abuts against the inner peripheral surface of the barrel mold while leaving both the steps.

  The element body molding portion has a front surface and a back surface corresponding to the optical surface of the optical element, and at least one of them can be a convex surface, a concave surface, or a flat surface.

  The preform for molding an optical element according to the present invention includes a plurality of abutting portions in which the outer peripheral portion of the edge forming portion abuts on the inner peripheral surface of the trunk mold when deformed by heat compression, It is preferable to form a plurality of non-contact portions that do not contact the inner peripheral surface.

  Further, the optical element molding method according to the present invention includes arranging the optical element molding preform in a space surrounded by an upper mold, a lower mold, and a body mold, and leaving the step on both sides. In this method, the preform for molding an optical element is deformed by heating and compressing so that the outer peripheral part of the optical element is in contact with the inner peripheral surface of the body mold.

  By disposing a spacer between the upper mold and the lower mold, the deformation amount of the preform for molding an optical element when heated and compressed can be regulated.

  When at least one of the upper mold and the lower mold has a convex molding surface that protrudes with respect to the space, the optical element molding preform disposed in the space faces the convex molding surface. It is preferable to have a concave portion.

  When at least one of the upper mold and the lower mold has a concave molding surface that is recessed with respect to the space, the optical element molding preform disposed in the space faces the concave molding surface. It is preferable to have a convex portion.

  Further, when at least one of the upper mold and the lower mold has a planar molding surface, the optical element molding preform disposed in the space has a planar portion facing the planar molding surface. It is preferable.

  According to the present invention, a high-quality optical element can be molded easily and inexpensively without complicating molding conditions and the mold configuration.

It is a figure which shows the preform for optical element shaping | molding which concerns on one embodiment of this invention. 1 is an overall view of a preform compression molding machine used in an optical element molding method according to an embodiment of the present invention. It is a side view before compression molding of the preform concerning an embodiment of the invention. It is a side view at the time of completion of compression molding of a preform according to an embodiment of the present invention. FIG. 5 is an overall view of an optical element produced by compression-molding a preform according to an embodiment of the present invention as shown in FIGS. 3 and 4. It is a side view before compression molding in the case where the preform according to the embodiment of the present invention is arranged with its center shifted from the center of the molding surface of the upper mold and the lower mold. It is a side view at the time of completion of compression molding when the preform according to the embodiment of the present invention is arranged with its center shifted from the center of the molding surface of the upper die and the lower die. FIG. 8 is an overall view of an optical element produced by compression-molding a preform according to an embodiment of the present invention as shown in FIGS. 6 and 7. It is a modification of the preform which concerns on embodiment of this invention, Comprising: It is side surface sectional drawing in case the molding surface of an upper mold is convex and the surface corresponding to the molding surface of a preform is concave. FIG. 10 is another side modification of the preform according to the embodiment of the present invention, and is a side cross-sectional view when the molding surface of the upper mold is concave and the surface corresponding to the molding surface of the preform is convex. FIG. 10 is a side cross-sectional view showing still another modified example of the preform according to the embodiment of the present invention, in which the molding surface of the upper mold is a flat surface and the surface corresponding to the molding surface of the preform is a flat surface. . FIG. 6 is a plan view showing a preform in which the flange forming portion and the edge forming portion are triangular when viewed from the compression direction, which is a modification of the optical element molding preform according to the embodiment of the present invention. It is a top view which shows the mode at the time of completion of compression molding of the preform for optical element shaping | molding shown in FIG. It is side surface sectional drawing at the time of arrange | positioning the conventional preform for optical element shaping | molding to the preform compression molding machine. It is an expanded side sectional view at the time of completion of compression molding of a conventional preform.

FIG. 1 shows an optical element molding preform 10 according to an embodiment of the present invention. The preform 10 has an element body forming portion 12 having an approximately spherical surface and a first thickness disposed on the outer periphery of the element body forming portion 12 for forming an element body having an optical surface. An annular flange forming portion 14 having a thickness T1 and an annular edge forming portion 16 having a second thickness T2 disposed on the outer peripheral portion of the flange forming portion 14 are provided.
The second thickness T2 of the edge forming portion 16 is thinner than the first thickness T1 of the flange forming portion 14, and the edge forming portion 16 is formed on the peripheral portions on both the front surface side and the back surface side of the flange forming portion 14. Annular steps S1 and S2 are formed respectively.

  The material of the optical element molding preform 10 is not particularly limited, and various optical materials corresponding to the optical element to be molded, such as a thermoplastic plastic material and glass, can be used.

  Next, a method for forming the preform 10 into an optical element will be described.

  For forming the preform 10, a preform compression molding machine 30 as shown in FIG. 2 is used. The molding machine 30 includes a lower mold 34 that is fixed in position, and an upper mold 32 that is arranged so as to be movable in the vertical direction with respect to the lower mold 34. A cylindrical body mold 36 is disposed on the outer periphery of the lower mold 34 and the upper mold 32 so as to surround the lower mold 34 and the upper mold 32, and the movement amount of the upper mold 32 is disposed on the outer periphery of the body mold 36. A cylindrical spacer 38 is disposed to regulate the above.

First, the preform 10 shown in FIG. 1 is placed in a cavity 40 that is a space formed by the molding surfaces of the upper mold 32 and the lower mold 34 and the inner peripheral surface of the body mold 36.
The preform 10 is disposed such that the front and back surfaces of the element body forming portion 12 are opposed to substantially the center of the molding surfaces of the upper mold 32 and the lower mold 34, and is heated by a heater (not shown) built in the molding machine 30. .

  When the preform 10 is sufficiently heated to be deformable, the upper die 32 is lowered toward the lower die 34 as shown in FIG. Compression molding of the reform 10 is performed.

  The size of the spacer 38 is determined in advance according to the shape and thickness of the optical element to be molded, and the upper mold 32 is lowered until it abuts against the spacer 38, so that the deformation of the preform 10 due to compression is reduced. Completed and the shape of the optical element is formed.

  As shown in FIG. 4, after the compression deformation of the preform 10 is completed, the deformed preform 10 is cooled to manufacture an optical element. The optical element can be taken out with the upper mold 32 raised and the mold opened.

  The optical element 20 thus manufactured is shown in FIG. The optical element 20 has an element body 22, and an annular flange 24 for supporting the element body 22 is disposed on the outer periphery of the element body 22. Further, an annular edge portion 26 is formed on the outer peripheral portion of the flange 24. When the optical element 20 is installed in an optical device such as a camera, the element body 22 is supported by the flange 24 and the element body 22 is positioned by the outer surface of the edge portion 26.

  A thickness T12 of the edge portion 26 is thinner than a thickness T11 of the flange 24, and the edge portion 26 forms annular steps S11 and S12 on the peripheral portions on both the front surface side and the back surface side of the flange 24, respectively. .

Next, referring to FIG. 3, the compression molding will be described in detail with attention paid to the molding surfaces of the upper mold 32 and the lower mold 34 and the body mold 36.
Since the preform compression molding machine 30 is configured by combining a plurality of different mold members, between the adjacent mold members and the mold members, in particular, between the upper mold 32 and the lower mold 34 and the trunk mold 36. A gap called a clearance 60 is inevitably formed.

  After the preform 10 is sufficiently heated and can be deformed, the upper mold 32 moves toward the lower mold 34.

  Here, as the upper mold 32 moves, the element body forming portion 12 of the preform 10 is compressed by the molding surfaces of the upper mold 32 and the lower mold 34. By this compression, the preform 10 is deformed along the molding surface, and an optical surface starts to be molded on the element body forming portion 12.

  Further, the flange forming portion 14 of the preform 10 is compressed by the molding surfaces of the upper mold 32 and the lower mold 34. By this compression, the flange forming portion 14 is deformed along the molding surfaces of the upper die 32 and the lower die 34 while being thinned, and spreads radially toward the body die 36.

Further, the edge forming portion 16 of the preform 10 approaches the body mold 36 direction without substantially changing the thickness according to the spread of the flange forming portion 14, but on the front surface side and the back surface side of the flange forming portion 14. Since the annular steps S1 and S2 are formed on both peripheral portions, the edge portion 26 is formed by contacting the body die 36 without contacting the molding surfaces of the upper die 32 and the lower die 34.
In other words, the flange forming portion 14 of the preform 10 extends in the direction of the body mold 36 while leaving the annular steps S1 and S2 formed on the peripheral portions on both the front surface side and the back surface side, and as the flange portion 24 Molded.

  Thus, the edge forming portion 16 of the preform 10 does not contact the molding surfaces of the upper mold 32 and the lower mold 34, but the outer surface contacts the body mold 36 to form the edge portion 26, and the flange forming portion 14 forms the flange portion 24 without coming into contact with the body mold 36, so that the material of the preform 10 does not enter the clearance 60 between the upper mold 32 and the lower mold 34 and the body mold 36. It becomes possible to manufacture the optical element 20 having no surface.

  Further, when the preform 10 of the present invention is disposed in the cavity 40 that is a space formed by the upper mold 32, the lower mold 34, and the body mold 36, the arrangement position thereof is the upper mold 32 and the lower mold 34. Even if it is slightly deviated from the approximate center of the molding surface, the element body 22 having the optical surface and the edge portion 26 for positioning the optical surface can be accurately formed.

  As shown in FIG. 6, it is assumed that the center of the preform 10 is shifted to the right by ΔX from the center of the molding surface of the upper mold 32 and the lower mold 34.

As in the case where there is no deviation, the preform 10 is compressed by the upper mold 32 and the lower mold 34 when the preform 10 is heated by a heater (not shown) built in the molding machine 30 and can be deformed.
As shown in FIG. 7 in the same manner as in the above-described embodiment, the element body forming portion 12 is deformed in contact with the molding surfaces of the upper die 32 and the lower die 34, and as shown in FIG. An element body 22 having a surface is formed.

Further, since the preform 10 is arranged slightly shifted to the right, the flange 24 is formed slightly offset to the right as shown in FIG.
The flange 24 is sufficient if it can support the element body 22 and be positioned in the optical axis direction.
Even when the center of the preform 10 is shifted, the edge forming portion 16 abuts on the inner peripheral surface of the body mold 36 during compression molding to form the edge portion 26, and the outer peripheral surface of the edge portion 26 forms an element. Since the positioning of the main body 22 is performed and the annular steps S11 and S12 are formed in the peripheral portions on both the front surface side and the back surface side of the flange 24, the positioning reference surface of the optical element 20 after molding does not shift, Optical accuracy is not affected.

  In the preform 10 shown in the above embodiment, both the front surface and the back surface of the element body forming portion 12 are flat surfaces, but the present invention is not limited to this.

  As shown in FIG. 9, when at least one of the upper mold 32 and the lower mold 34 has a convex molding surface 42 protruding with respect to the cavity 40, the preform 10 disposed in the cavity 40 has a convex shape. It is preferable to have the recessed part 44 with a large curvature radius with respect to the molding surface 42 of this. In that case, the amount of deformation at the time of compression molding is reduced, and the distortion can be reduced. In addition, air traps that occur between the molding surface 42 and the recess 44 during compression molding can be more easily avoided.

  Similarly, as shown in FIG. 10, when at least one of the upper mold 32 and the lower mold 34 has a concave molding surface 46 that is recessed with respect to the cavity 40, the preform 10 disposed in the cavity 40 is It is preferable to have a convex portion 48 having a small curvature radius with respect to the concave molding surface 46. In that case, the amount of deformation at the time of compression molding is reduced, and the distortion can be reduced. In addition, air traps that occur between the molding surface 46 and the projections 48 during compression molding can be more easily avoided.

  In addition, as shown in FIG. 11, when at least one of the upper mold 32 and the lower mold 34 has a planar molding surface 50, the preform 10 disposed in the cavity 40 is formed on the planar molding surface 50. On the other hand, it is preferable to have the planar part 52 which is narrow and high. In that case, the amount of deformation at the time of compression molding is reduced, and the distortion can be reduced. In addition, air traps that occur between the molding surface 50 and the flat portion 52 during compression molding can be more easily avoided.

  9 to 11, only the molding surface of the upper mold of the molding machine 30 is described, and only the upper surface of the element main body forming portion 12 is specifically shown for the preform 10.

  By using the optical element molding preform 10 having a shape corresponding to the molding surface of the mold, the amount of deformation of the preform 10 at the time of molding is reduced, and the optical element 20 that is less prone to burrs and significant deviation is formed. can do.

In the preform 10 shown in FIG. 1, the flange forming portion 14 and the edge forming portion 16 have a circular planar shape, but the present invention is not limited to this.
For example, as shown in FIG. 12, when the planar shape of the flange forming portion 14 and the edge forming portion 16 is triangular, and compression deformation is completed in the mold of the compression molding machine, as shown in FIG. The edge forming portion 16 with the step left remains, the three contact portions 17 that respectively contact the inner peripheral surface of the body mold 36 at the apex portion of the triangle, and the three non-contact portions that do not contact the inner peripheral surface of the body mold 36. The contact portion 18 may be formed.

  An optical element molded using such a preform 10 includes three edge portions corresponding to the contact portions 17, and the element body is positioned by these three edge portions. When the compressive deformation is completed, a gap where no resin is present is formed between the non-contact portion 18 of the preform 10 and the inner peripheral surface of the body mold 36. Even if it exists, it becomes possible to manufacture the high quality optical element without a burr | flash.

  Note that the shapes of the flange forming portion 14 and the edge forming portion 16 are not limited to a triangle, and a pair of circular arc portions facing in opposite directions of a square, a rhombus, a pentagon or more polygon, an ellipse, or a circle are cut out. Various shapes such as a shape can be used.

  Further, in the preform 10 shown in FIG. 1, the element body forming portion 12 has a cylindrical shape. However, the shape is not limited to this, and various shapes are formed corresponding to the optical element to be manufactured. Can do.

DESCRIPTION OF SYMBOLS 10 Preform for optical element shaping | molding 12 Element main body formation part 14 Flange formation part 16 Edge formation part 17 Contact part 18 Non-contact part 20 Optical element 22 Element main body 24 Flange 26 Edge part 30 Preform compression molding machine 32 Upper mold | type 34 Lower mold 36 Body mold 38 Spacer 40 Cavity 42 Convex shaped surface 44 Concave portion 46 Concave shaped surface 48 Convex portion 50 Flat shaped surface 52 Flat portion 60 Clearance

Claims (10)

A preform formed into an optical element by being placed in a space surrounded by an upper mold, a lower mold, and a body mold and heated and compressed,
An element body forming portion for forming an element body having an optical surface;
An annular flange forming portion having a first thickness disposed on the outer periphery of the element body forming portion;
An annular step is formed on each of the peripheral portions on the front side and the back side of the flange forming portion, which is disposed on the outer peripheral portion of the flange forming portion and has a second thickness smaller than the first thickness. An annular edge forming portion, and when deformed by being heated and compressed, the outer peripheral portion of the edge forming portion abuts against the inner peripheral surface of the body mold while leaving both the steps. Element molding preform.   2. The optical element molding preform according to claim 1, wherein the element body molding portion has a front surface and a back surface corresponding to the optical surface of the optical element, and at least one of them is a convex surface.   2. The optical element molding preform according to claim 1, wherein the element body molding portion has a front surface and a back surface corresponding to the optical surface of the optical element, and at least one of them is a concave surface.   2. The optical element molding preform according to claim 1, wherein the element body molding portion has a front surface and a back surface corresponding to the optical surface of the optical element, and at least one of them is a flat surface.   When deformed by heat compression, the outer peripheral portion of the edge forming portion has a plurality of contact portions that contact the inner peripheral surface of the barrel mold and a plurality of non-appropriate portions that do not contact the inner peripheral surface of the barrel mold. The optical element molding preform according to any one of claims 1 to 4, wherein the optical element molding preform forms a contact portion. The optical element molding preform according to any one of claims 1 to 5 is disposed in a space surrounded by an upper mold, a lower mold, and a trunk mold,
An optical element molding method, wherein the optical element molding preform is heated and compressed to deform so that an outer peripheral portion of the edge forming portion abuts against an inner peripheral surface of the body mold while leaving both the steps. .   The optical element molding according to claim 6, wherein a deformation amount of the optical element molding preform when heated and compressed is regulated by disposing a spacer between the upper mold and the lower mold. Method. At least one of the upper mold and the lower mold has a convex molding surface protruding with respect to the space,
The optical element molding method according to claim 6, wherein the preform for molding an optical element disposed in the space has a concave portion facing the convex molding surface. At least one of the upper mold and the lower mold has a concave molding surface that is recessed with respect to the space,
The optical element molding method according to claim 6 or 7, wherein the optical element molding preform disposed in the space has a convex portion opposed to the concave molding surface. At least one of the upper mold and the lower mold has a flat molding surface,
The optical element molding method according to claim 6, wherein the preform for molding an optical element disposed in the space has a planar portion facing the planar molding surface.

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