JP2009096675A - Molding unit of optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of reducing lead time and cost by abolishing the lens cut process after molding. <P>SOLUTION: In a molding unit 10 of an optical element, in which a lens 34 is molded by putting a heated and softened molding material 32 between a couple of upper mold 26 and lower mold 28 facing each other and pressing it, this unit is equipped with a side-surface pressing member 38 which is located between the couple of upper mold 26 and lower mold 28 and having a pressing surface 38a which molds the both side-surfaces 34b of the lens to be molded 34 in a flat surface, and an outer circumference regulating member 36 which holds the side-surface pressing member 38 and control the outer circumference surface 34a of the lens to be molded 34. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical element molding apparatus that molds an optical element by pressing and molding a glass or other molding material between a pair of molding dies.

In recent years, with the miniaturization of digital cameras and the like, it is required to reduce the shape of the optical system in accordance with the shape of the CCD or CMOS used in the digital camera.
Therefore, optically unnecessary outer peripheral portions of optical elements used in the optical system are cut to cope with the production of optical elements having a D shape, oval shape, etc., but the number of processing steps increases. There is also a negative effect that man-hours increase and manufacturing costs also increase.

  On the other hand, regarding this type of optical element, a technique has been proposed in which optical elements other than the axially symmetric shape are molded by a molding means. For example, Patent Document 1 discloses a technique related to a resin optical element of an oval pickup in which a part of a peripheral edge of a substantially circular optical functional surface centered on an optical axis is cut out by a straight portion.

Further, in Patent Document 2, in addition to a pair of upper mold and lower mold and body mold, the same outer diameter as the upper mold and lower mold and the same inner diameter as the desired optical element outline (polygon, circle, ellipse, etc.) A technique for forming an optical element having a non-axisymmetric shape using an auxiliary cylinder mold having the above is disclosed.
JP 2004-264538 A JP-A-5-85747

  However, the technique of Patent Document 1 is an effective molding means for a resin optical element that can be filled in a liquid state. However, by heating to a temperature close to liquefaction like optical glass, This method is not applicable to materials whose optical properties are lost.

  Further, in Patent Document 2, although the desired shape of the optical element can be produced by the configuration of the molding die, the desired shape is not obtained due to non-uniform cooling and shrinkage of the glass generated from the non-axisymmetric shape during cooling. There is a risk that the accuracy of the molding surface will not be obtained.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical element molding apparatus capable of reducing the lead time and cost by eliminating the optical element cutting step after molding. .

In order to achieve the object, the invention according to claim 1
In an optical element molding apparatus for molding an optical element by sandwiching and pressing a heat-softened molding material between a pair of opposing molds,
A side surface pressing member that is disposed between the pair of molds and has a pressing surface that molds the side surface of the optical element to be molded into at least one plane;
An outer periphery regulating member that holds the side pressing member and regulates an outer circumferential surface of the optical element to be molded;
An optical element having an outer peripheral side surface having at least one flat portion is molded.

The invention according to claim 2 is the optical element molding apparatus according to claim 1,
The side surface pressing member and the outer periphery regulating member are different in material.
The invention according to claim 3 is the optical element molding apparatus according to claim 1,
The thermal conductivity of the outer periphery regulating member is larger than the thermal conductivity of the side surface pressing member.

The invention according to claim 4 is the optical element molding apparatus according to claim 1,
The side surface pressing member is subjected to a surface treatment.

  According to the present invention, only the molding process is provided by including the side surface pressing member that molds the side surface of the optical element to be molded into at least one flat surface, and the outer circumferential restriction member that regulates the outer circumferential surface of the molded optical element. Since the optical element having at least one flat portion can be molded on the outer peripheral side surface of the desired optical element, the optical element cutting step after molding can be abolished to shorten the lead time and the manufacturing cost. it can.

The configuration of the embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration before molding of an optical element molding apparatus, and FIG. 2 is a diagram showing a schematic configuration after molding.

FIG. 3 is a view showing a cross section taken along line III-III in FIG.
FIG. 4 is a diagram showing the upper end and the molding surface portion of the lower mold 28 by removing the outer periphery regulating member 36 holding the side pressing member 38 in the cross section taken along the line IV-IV in FIG.

5A and 5B show a top view when the outer periphery regulating member 36 holding the side pressing member 38 is installed on the lower mold 28, and a cross section taken along the line AA ′ at that time. .
6A and 6B are diagrams showing details of the configuration of the outer periphery regulating member 36. FIG.

7A and 7B are diagrams showing details of the configuration of the side pressing member 38. FIG.
FIG. 8 is a view showing a molding state of the oval optical element 34 in the mold set 16 after molding.
FIGS. 9A and 9B show an oval glass optical element 34 having two side surfaces 34b and 34b.

FIGS. 10A and 10B show a D-shaped glass optical element 34 ′ having one side surface 34′b.
A molding apparatus 10 shown in FIGS. 1 and 2 includes a pair of an upper heating plate 12 and a lower heating plate 14 that are disposed so as to face each other, and an upper plate support shaft 22 and a lower plate support shaft 24 that fix and support them. And cartridge heaters 18 and 20 built in the upper heating plate 12 and the lower heating plate 14, respectively, an upper plate support shaft 22, and an air cylinder (not shown) that drives the upper heating plate 12 in the vertical (opposite) direction. And a main body (not shown) to which the lower plate support shaft 24 is fixed, and a casing (not shown) that covers the entire apparatus shown in FIGS. 1 and 2 and can replace the oxidizing atmosphere with a non-oxidizing atmosphere. Yes.

The upper heating plate 12 and the plate support shaft 22 are supported by an air cylinder (not shown) so as to be movable up and down.
Instead of attaching an air cylinder to the upper plate support shaft 22, an air cylinder may be attached to the lower plate support shaft 24 side, and an air cylinder is attached to both the upper plate support shaft 22 and the lower plate support shaft 24. May be.

  Further, the fitting portion between the housing (not shown) and the upper and lower plate support shafts 22 and 24 is provided with a seal capable of maintaining the internal airtightness of the housing (not shown). In addition, an unillustrated atmosphere intake / exhaust hole for replacing the atmosphere is provided in the unillustrated casing.

A mold set 16 is placed on the lower heating plate 14 of the molding apparatus.
The mold set 16 includes an upper mold 26, a lower mold 28, and a sleeve 30. The upper mold 26 and the lower mold 28 are formed inside the sleeve 30 so that the molding surfaces 26a and 28a face each other. The upper mold 26 is slidable in the axial direction of the sleeve 30 by being inserted from both ends of the sleeve 30. A molding material 32 is disposed between the molding surfaces 26a and 28a.

The upper die 26 as shown in FIG. 3, a cylindrical portion 26 _1, and a projecting portion 26 ₂ projecting surface facing the lower die 28 from the circular column portion 26 _1. It is formed concave spherical molding surface 26a at the tip of the projecting portion 26 _2. The projecting portion 26 _2, chromatic formed on the same plane as the two flat arc portions 42, 42, and two straight portions 44, 44 for connecting the ends of each of the arcuate portions 42 and 42 is doing.

Lower mold 28, as shown in FIG. 4, closed with two cylindrical portions ₂₈ 1, 28 ₂ of the large and small, and a protruding portion 28 ₃ which projects the surface facing the upper mold 26 from the small diameter cylindrical portion 28 ₂ is doing. The concave spherical molding surface 28a is formed at the tip of the protruding portion 28 _3. The projecting portions 28 _3, chromatic formed on the same plane as the two flat arc portions 46, 46, and two straight portions 48, 48 for connecting the ends of each of the arcuate portions 46, 46 is doing.

  The diameters of the arc portions 42 and 42 of the molding surface 26a of the upper mold 26 and the diameters of the arc portions 46 and 46 of the molding surface 28a of the lower mold 28 are equal, and the straight portions 44 and 44 of the molding surface 26a of the upper mold 26 are equal. The straight portions 48 of the molding surface 28a of the lower mold 28 are set to be equal in length.

  In the above description, the molding surfaces 26a and 28a have been described as concave spherical surfaces, but depending on the desired glass lens shape, either one is a concave aspherical surface and the other is a concave spherical surface. Also, a combination of concave aspheric surfaces on both sides may be used.

As materials for the upper die 26, the lower die 28, and the sleeve 30, a cemented carbide such as tungsten carbide (WC) is ground and polished to a desired shape.
For the molding material 32, a commercially available optical glass material (for example, L-BSL7 (manufactured by OHARA), etc.) is processed into, for example, a spherical shape, a product processed into an optical element shape of an approximate lens, molten glass is dropped, etc. The thing processed into the substantially spherical shape by the means is used.

As shown in FIGS. 5A and 5B, an outer periphery regulating member 36 is installed on the upper end molding surface portion of the lower mold 28.
The outer periphery regulating member 36 has a shape as shown in FIG. 6 and has a substantially cylindrical shape extending in the optical axis direction (Z-axis direction). The outer periphery restricting member 36 communicates with the lower die insertion hole 40 centered on the Z axis at the inner lower portion and the lower die insertion hole 40, and has a smaller diameter and two arc portions 36a facing the Z axis as the center. , 36a. Furthermore, it has two trapezoidal parts 36b and 36b having a substantially trapezoidal shape in a plan view connected to the respective ends of the two arc parts 36a and 36a. These two trapezoidal parts 36b, 36b have an upper base 136b and a lower base 136b ′ extending in parallel to the Y axis perpendicular to the X axis in plan view.

  A projecting piece 36c extending substantially parallel to the straight Y axis passing through the centers of the two arc portions 36a, 36a is formed at the lower portion of the upper base 136b of the trapezoidal portion 36b. The protruding piece 36c restricts the movement of the side surface pressing member 38 held by the outer periphery regulating member 36 in the Z-axis direction downward in the drawing.

  Furthermore, as shown in FIGS. 7A and 7B, the side surface pressing member 38 held by the outer periphery regulating member 36 is fitted and inserted inside the two trapezoidal portions 36 b of the outer periphery regulating member 36. The side surface pressing member 38 includes a pressing surface 38a, a fitting insertion surface 38b, and two inclined surfaces 38c that connect the pressing surface 38a and the fitting insertion surface 38b. Further, a stepped portion 38d extending substantially parallel to the pressing surface 38a is formed in the lower portion of the side pressing member 38.

At the time of assembly of the mold set 16, as shown in FIG. 5 (a) (b), fitting the outer circumference regulating member 36 to the cylindrical portion 28 ₂ diameter of the lower die 28. Next, the side pressing members 38 are fitted into the two trapezoidal portions 36 b of the outer periphery regulating member 36. At this time, the pressing surface 38a of the side pressing member 38 is fitted to the linear portion 48 (see FIG. 4) of the lower mold 28, and the stepped portion 38d of the side pressing member 38 is the protruding piece 36c (FIG. 6). To be engaged.

Furthermore, the sleeve 30 is fitted into a cylindrical portion 28 ₁ of the large diameter of the lower mold 28, the mold sets fitted as molding surface of the upper die 26 is opposite the direction with the lower die 28 from above the sleeve 30 Assemble.
Here, although the circular arc part 36a was illustrated as what regulates the outer peripheral surface (34a) of the optical element 34, it is not restricted to this. For example, instead of the arc portion 36a, a curved portion other than an arc or a straight portion may be used.

  Furthermore, the material of the outer periphery regulating member 36 and the side pressing member 38 are different. For example, when cemented carbide (WC) is used as the outer periphery regulating member 36, a combination using quartz glass or the like is used for the side pressing member 38. is there.

Next, the effect | action at the time of shaping | molding in this Embodiment is demonstrated.
After the molding material 32 is placed on the molding surface 28a of the lower mold 28 of the mold set 16, the upper mold 26 is fitted into the sleeve 30 so as to be sandwiched by the molding surface 26a of the upper mold 26, and the lower part in the casing (not shown) is inserted. It is installed on the heating plate 14.

After sealing the casing (not shown), the atmosphere inside the casing is replaced with a non-oxidizing atmosphere through an atmosphere intake / exhaust hole (not shown).
The upper heating plate 12 is lowered by an air cylinder (not shown) through the upper plate support shaft 22 and brought into contact with one end surface opposite to the molding surface 26a of the upper die 26 as shown in FIG. The cartridge heaters 18 and 20 built in the heating plates 12 and 14 are heated to a temperature near the glass softening point of the molding material 32.

When the molding material 32 reaches a temperature near the glass softening point, a pressing force is applied by an air cylinder (not shown) to lower the upper die 26 through the upper plate support shaft 22 and the upper heating plate 12, and the upper die 26. And the molding material 32 is spread between the lower molds 28 in a desired optical element shape.
By the above operation, the softened glass that has flowed in the direction of the pressing surface 38 a of the side pressing member 38 comes into contact with the pressing surface 38 a before the softened glass that flows in the direction of the arc portion 36 a of the outer periphery regulating member 36. Furthermore, if the pressing is continued to obtain a desired center thickness, the softened glass cannot flow in the direction of the pressing surface 38a, but flows in the direction of the arc portion 36a of the outer periphery regulating member 36, and the desired center thickness. At this point, the pressing is finished in the state shown in FIGS.

  Here, when the slip between the side pressing member 38 and the molding material 32 to be molded is poor, the softened glass being molded contacts the pressing surface 38a of the side pressing member 38, and then the arc portion 36a of the outer periphery regulating member 36. As a result, it does not flow to the circular arc part 36a of the outer periphery regulating member 36, and the molding ends before reaching the desired center thickness. Alternatively, excess softened glass overflows beyond the pressing surface 38a of the side pressing member 38, and a non-defective product cannot be obtained.

  Therefore, in order to obtain the optical element 34 having a desired shape by flowing the softened glass to the arc portion 36a of the outer periphery regulating member 36 by improving the sliding between the side pressing member 38 and the glass, the side pressing member 38 is made of glass. A carbon-based coating (for example, diamond-like carbon (DLC)) may be applied.

Thereby, the slip between the softened glass and the pressing surface 38a of the side pressing member 38 can be secured, and the flow of the outer periphery regulating member 36 to the arc portion 36a is facilitated.
After the molding into the desired shape is completed, the heating of the upper mold 26 and the lower mold 28 is stopped, the cooling of the mold set 16 is started, the temperature is lowered to near room temperature, and the mold set 16 is moved from a housing (not shown). And the molded optical element 36 is taken out.

  At this time, as in the present embodiment, when the shape of the molded product is a non-axisymmetric shape, the cooling rate can be different between the arc portion 36a of the outer periphery regulating member 36 and the pressing surface 38a of the side pressing member 38, As a result, unlike the case of an optical element shape that is axially symmetric (circular outer periphery, etc.), the softened glass cannot be shrunk evenly with respect to the optical element shape, and internal distortion occurs, resulting in a shape of the molding surface. As a result, the surface accuracy may be deteriorated.

  Therefore, by using the outer periphery regulating member 36 having a thermal conductivity larger than that of the side pressing member 38, the difference in temperature distribution between the outer periphery regulating member 36 and the side pressing member 38 is corrected, and it is close to pseudo-axisymmetric molding. The situation is created and the deterioration of the surface accuracy of the molded optical element 34 is prevented.

  For example, when glass such as quartz glass is used as the side pressing member 38 and a metal material such as cemented carbide (WC) having a higher thermal conductivity than glass is used as the outer peripheral regulating member 36, the outer peripheral regulating member 36 is used. The thermal conductivity of cemented carbide (WC) is 29 W / (m · K), whereas the thermal conductivity of quartz glass used for the side pressing member 38 is 1.62 W / (m · K).

If the molding material 32 is L-BSL7 given as an example above, the thermal conductivity of the L-BSL7 is 1.169 (W / (m · K)), so the thermal characteristics of the optical element 34 after molding are pseudo. It becomes a situation close to an axially symmetric shape, creates a uniform glass cooling situation, and can prevent deterioration of surface accuracy.
The relationship of the thermal conductivity of the member is larger in the outer periphery regulating member 36 than in the side pressing member 38. In the above description, the case of cemented carbide (WC) and quartz glass is described. If the material does not cause welding, there is no problem with ceramics.

The effect obtained by the above series of steps will be described.
The optical element 34 has two side surfaces 34b, 34b formed into a flat surface by the pressing surface 38a of the side surface pressing member 38, and an outer peripheral surface formed into an arc shape by the two arc portions 36a, 36a of the outer periphery regulating member 36. .

As a result, as shown in FIGS. 9A and 9B, the optical function surfaces 34 ₁ and 34 ₂ , the two arc portions 34 a and 34 a on the outer peripheral side, and the two arc portions 34 a and 34 a, respectively. The two arcuate portions 34a and 34a have the same radius of curvature with the optical axis as the center, and the two side portions 34b and 34b are connected to each other. Since it is possible to easily obtain the oval lens 34 arranged in parallel to the position symmetrical to the optical axis, the cutting process of the optical element after molding can be abolished, and the lead time is shortened and the manufacturing cost is reduced. Can be reduced.

In the present embodiment, the case where the optical element 34 having the two side surfaces 34b and 34b is molded has been described. However, the present invention is not limited to this. For example, the optical element 34 having the side surface 34b as one flat portion can be molded. In this case, in FIG. 8, one side pressing member 38 is used and connected so that the arc portions of the outer periphery regulating member 36 corresponding to the other side pressing member 38 are connected. 10A and 10B, an optical element 34 ′ (so-called D-shaped optical element) having a side surface 34b ′ as one plane portion can be obtained. In this optical element 34 ', one part of the outer peripheral surface 34a' of the substantially circular optical functional surfaces 34 ₁ 'and 34 ₂ ' centering on the optical axis is cut out by a straight line to form a side surface 34b '. Similarly to the oval shape, the cutting process of the optical element after molding can be abolished, and the lead time can be shortened and the manufacturing cost can be reduced.

It is a figure which shows schematic structure before shaping | molding of the shaping | molding apparatus of an optical element. It is a figure which shows schematic structure after shaping | molding of the shaping | molding apparatus of an optical element. It is a figure which shows the cross section which follows the III-III line | wire of FIG. It is a figure which shows the cross section which follows the IV-IV line of FIG. (A) is a top view of the outer periphery control member holding the side surface pressing member, (b) is sectional drawing which follows the AA. (A) is a top view of an outer periphery control member, (b) is sectional drawing which follows the BB. (A) is a top view of a side pressing member, (b) is the front view. It is a figure which shows the state of the optical element in the type | mold set after shaping | molding. (A) is a top view of the optical element which has two plane parts, (b) is the front view. (A) is a top view of the optical element which has one plane part, (b) is the front view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical element shaping | molding apparatus 12 Upper heating plate 14 Lower heating plate 16 Type set 18 Cartridge heater 20 Cartridge heater 22 Upper plate support shaft 24 Lower plate support shaft 26 Upper die 26 ₁ Cylindrical portion 26 ₂ Protruding portion 26a Molding surface 28 Lower die 28 ₁ cylindrical portion 28 ₂ cylindrical portion 28 ₃ protruding portion 28a molding surface 30 sleeve 32 molding material 34 optical element 34 ₁ optical function surface 34 ₂ optical function surface 34a outer peripheral surface 34b side surface 34 'optical element 34 ₁ ' optical function surface 34 ₂ 'Optical function surface 34a' Outer peripheral surface 34b 'Side surface 36 Outer periphery regulating member 36a Arc portion 36b Trapezoidal portion 36c Projection piece 38 Side pressing member 38a Press surface 38b Fitting insertion surface 38c Inclined surface 38d Step portion 40 Lower mold insertion hole 42 Straight line part 46 Arc part 48 Straight line part

Claims (4)

In an optical element molding apparatus for molding an optical element by sandwiching and pressing a heat-softened molding material between a pair of opposing molds,
A side surface pressing member that is disposed between the pair of molds and has a pressing surface that molds the side surface of the optical element to be molded into at least one plane;
An outer periphery regulating member that holds the side pressing member and regulates an outer circumferential surface of the optical element to be molded;
An optical element molding apparatus for molding an optical element having an outer peripheral side surface having at least one flat portion. The optical element molding apparatus according to claim 1, wherein the side surface pressing member and the outer periphery regulating member are made of different materials. The optical element molding apparatus according to claim 1, wherein a thermal conductivity of the outer periphery regulating member is greater than a thermal conductivity of the side surface pressing member. The optical element molding apparatus according to claim 1, wherein the side pressing member is subjected to a surface treatment.