JP2012158490A - Apparatus and method for manufacturing optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the unevenness of filling of an optical material in a mold during molding, and to suppress or prevent the occurrence of burn of an optical material surface due to overheating.SOLUTION: The apparatus for manufacturing an optical element includes: an upper mold 11 having a molding surface 11a whose shape corresponds to the upper surface of an optical element to be molded; and a lower mold 12 which has a molding surface 12a whose shape corresponds to the lower surface of the optical element to be molded and which is disposed in such a way that the molding surface 12a is made to face the molding surface 11a of the upper mold 11; wherein an optical material 1 disposed between the upper mold 11 and the lower mold 12 is softened by heating and press-molded to manufacture the optical element. The apparatus is provided with an upper annular member 15 around the molding surface 11a of the upper mold 11, and the upper annular member 15 is disposed so that press molding is started in a state where the optical material 1 is sandwiched between the upper annular member 15 and the lower mold 12 while being in noncontact with the molding surface 11a of the upper mold 11.

Description

  The present invention relates to an optical element manufacturing apparatus and an optical element manufacturing method.

  2. Description of the Related Art Conventionally, a method for manufacturing a high-precision glass optical element by using a mold formed of a precisely processed upper mold and lower mold has been known (for example, see Patent Document 1). In this method, generally, an optical material made of a glass material of a molding material is placed on a lower mold, and the upper mold is brought into contact with the optical material to be positioned and fixed. It is softened and then press-molded to give a predetermined shape to the optical material. Thereafter, the optical material is cooled and solidified to open the mold and obtain an optical element.

  However, in this method, depending on the shape of the optical material and the shape of the optical element to be obtained, the optical material before press molding is held at two points, the center of the lower surface of the upper mold and the center of the upper surface of the lower mold. Therefore, there has been a problem that even if a slight impact is applied, the position shift easily occurs. When the position shift occurs, the filling of the optical material is biased, and there is a possibility that cracking or the like occurs. In addition, since the heat of the upper mold and the lower mold is transferred to the optical material from the above two points, there is a problem that “burn (a phenomenon in which the surface appears white)” due to overheating occurs at the center of the upper surface and the lower surface of the obtained optical element. was there. This burning problem can be improved by, for example, polishing the surface of the optical material after molding, but causes problems such as a decrease in productivity and an increase in cost. In particular, in the case of an optical element having an aspheric surface such as an aspheric lens, the degree of productivity reduction and cost increase is remarkable.

JP 2009-7221 A

  The present invention addresses the above-described conventional circumstances. In a mold used for a method of manufacturing an optical element by heat-softening an optical material and press-molding it, the shape of the optical material or the optical element to be obtained is obtained. Regardless of this, it is possible to provide an optical element manufacturing apparatus and an optical element manufacturing method that can prevent the uneven filling of the optical material in the mold at the time of molding and can suppress or prevent the burning of the optical material surface due to overheating. And

  The optical element manufacturing apparatus of the present invention has an upper mold having a molding surface having a shape corresponding to the upper surface of the optical element to be molded, and a molding surface having a shape corresponding to the lower surface of the optical element to be molded. An apparatus for manufacturing an optical element, comprising: a lower mold disposed with a molding surface facing the molding surface of the upper mold; and heat-softening an optical material disposed between the upper mold and the lower mold and press molding An upper annular member is provided around the molding surface of the upper mold, and the upper annular member is sandwiched between the upper annular member and the lower mold so that the optical material is not in contact with the molding surface of the upper mold. It is characterized by being arranged so that press molding is started in the state.

  The optical element manufacturing method of the present invention also includes an upper mold having a molding surface having a shape corresponding to the upper surface of the optical element to be molded, and a lower mold surface having a shape corresponding to the lower surface of the optical element to be molded. A method of manufacturing an optical element by disposing a mold so that the respective molding surfaces face each other, disposing an optical material between the upper mold and the lower mold, then heat-softening the optical material, and press molding An upper annular member is provided around the molding surface of the upper mold, and the upper annular member is sandwiched between the upper annular member and the lower mold without contacting the optical material with the molding surface of the upper mold. The optical material is heat-softened and press-molded.

  According to the optical element manufacturing apparatus and the optical element manufacturing method of the present invention, it is possible to prevent uneven filling of the optical material in the molding die during molding, regardless of the shape of the optical material or the optical element to be obtained. The occurrence of burns on the surface of the optical material due to overheating can be suppressed or prevented.

It is sectional drawing which shows an example of the shaping | molding die used for one Embodiment of this invention. It is sectional drawing which shows the other example of the shaping | molding die used for one Embodiment of this invention. It is sectional drawing which shows the other example of the shaping | molding die used for one Embodiment of this invention. It is sectional drawing which shows the other example of the shaping | molding die used for one Embodiment of this invention. It is sectional drawing which shows the other example of the shaping | molding die used for one Embodiment of this invention. It is a schematic block diagram which shows the shaping | molding apparatus used for one Embodiment of this invention. It is sectional drawing which shows the further another example of the shaping | molding die used for one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described. Although the description will be made based on the drawings, the drawings are provided for illustration only, and the present invention is not limited to the drawings. In the following description of the drawings, the same reference numerals are given to common parts or parts having the same main function in the same place.

  FIG. 1 is a cross-sectional view showing an example of a molding die used in an optical element manufacturing apparatus according to an embodiment of the present invention, and the right half of the central axis shows a molding die before optical material is press-molded. The left half of the central axis shows the mold after the optical material is press-molded. 2 to 5 and 7 described later, as in FIG. 1, the right half of each central axis indicates the mold before press molding the optical material, and the left half of the central axis indicates The mold after press-molding an optical material is shown.

  As shown in FIG. 1, the mold 10 includes an upper mold 11 that molds the upper surface of the optical element, a lower mold 12 that molds the lower surface of the optical material, and the upper mold 11 and the lower mold 12 are inserted and slid. A cylindrical inner cylinder 13 for aligning the central axes thereof, and a cylindrical outer cylinder 14 which is fitted to the outer periphery of the inner cylinder 13 and regulates the vertical distance between the upper mold 11 and the lower mold 12; It has.

  Each of the upper mold 11 and the lower mold 12 is a member having a cylindrical body as a basic shape. Since the upper mold 11 and the lower mold 12 form an optical element, the upper mold 11 has an upper surface of the optical element. The lower mold 12 has a molding surface 12a that forms the lower surface of the optical element. Hereinafter, the molding surface 11a of the upper mold 11 is referred to as an upper molding surface, and the molding surface 12a of the lower mold 12 is referred to as a lower molding surface. The upper mold 11 and the lower mold 12 are disposed with the upper molding surface 11a and the lower molding surface 12a facing each other.

  The inner cylinder 13 is formed in a hollow cylindrical shape, and the cylindrical part of the upper mold 11 and the lower mold 12 described above can be fitted into the hollow part. When the upper die 11 and the lower die 12 are fitted and pressed, the inner cylinder 13 is inserted into the upper die 11 and the lower die 12 so as to be slidable from the upper and lower openings, and the optical center axis thereof is set. The optical function surface of the optical element to be formed is coaxial so that the optical elements are aligned so as to be regulated coaxially.

  The outer cylinder 14 has a hollow cylindrical shape like the inner cylinder 13, but the inner cylinder 13 is fitted into the hollow portion to regulate the distance between the upper mold 11 and the lower mold 12. Specifically, the outer cylinder 14 is used for pressurizing the optical material 1 placed on the lower mold 12 by pressing the upper mold 11 and the lower mold 12 close to each other during press molding. By restricting the distance between the pressing surfaces of the pressing means (not shown), the distance between the upper die 11 and the lower die 12 is restricted.

  In the present invention, the upper annular member 15 is provided around the upper molding surface 11 a of the upper mold 11. When the upper annular member 15 starts pressurization of the optical material 1 placed on the lower die 12 with the upper die 11 and the lower die 12 approaching each other at the time of press molding, the right half of the central axis in FIG. As shown in FIG. 3, the upper surface of the optical material 1 does not contact the molding surface 11a of the upper mold 11 but contacts the upper annular member 15 only on the surface. That is, the lower surface of the upper annular member 15 is formed with a tapered surface inclined from the inner side toward the lower outer side, and is in contact with the optical material 1 at the surface. Although the taper surface is shown in FIG. 1, the present invention is not limited to this, and can be appropriately changed to a flat surface, a reverse taper surface, or the like. The upper annular member 15 is fixed to the upper die 11 by bringing the upper surface and the inner peripheral surface thereof into close contact with the upper die 11 and inserting the fixing pins 16 in the radial direction from the outer periphery toward the upper die 11. ing. In FIG. 1, reference numeral 17 indicates a through hole for inserting a fixing pin formed in the upper annular member 15 and the upper mold 11.

  In addition, about 0.1-0.3 mm is suitable for the separation distance of the molding surface 11a of the upper mold | type 11 made non-contact, and the optical raw material 1. FIG. If it is less than 0.1 mm, there is a high possibility that the upper mold and the optical material come into contact with each other due to its own weight deformation during heating. On the other hand, if the thickness exceeds 0.3 mm, transfer of the molding surfaces 11a and 11b of the molding die 10A to the optical material 1 may be reduced, or the upper annular member 15 and the lower die 12 may come into contact with each other.

  Further, each member constituting the mold 10, that is, the upper mold 11, the lower mold 12, the inner cylinder 13, the outer cylinder 14, and the upper annular member 15 are all made of a heat-resistant alloy such as cemented carbide or tungsten-based alloy, It can be formed of ceramic or the like. In addition to these, the outer body 14 can be made of a metal such as stainless steel or Inconel (trade name, manufactured by Daido Special Metal Co., Ltd.). Stainless steel is preferable because it is easy to process, has a large amount of thermal expansion, and is inexpensive.

  In FIG. 1, the mold 10 is illustrated for manufacturing a concave meniscus optical element, but the optical element shape is not limited to this, and is a biconcave shape, a biconvex shape, a convex meniscus shape, and a planoconvex shape. A molding die for molding any shape of a plano-concave shape may be used. 2 to 4 show examples thereof. The mold 102 shown in FIG. 2 is an example of a mold for manufacturing a convex meniscus optical element, and the mold 103 shown in FIG. An example of a mold for manufacturing a shaped optical element, the mold 104 shown in FIG. 4, is an example of a mold for manufacturing a biconvex optical element. Although not shown, a deaeration hole communicating with the outside is provided between the upper mold 11 and the upper annular member 15.

  In FIG. 1, the upper annular member 15 is fixed to the upper mold 11 by the fixing pin 16, but can be fixed by screwing as shown in the example of the forming mold 105 of FIG. 5. In FIG. 5, reference numerals 18 a and 18 b indicate thread grooves formed on the outer peripheral surface of the upper mold 11 and the inner peripheral surface of the upper annular member 15, respectively.

  Furthermore, in the example of FIG. 5, an annular spacer 19 is provided between the upper annular member 15 and the upper mold 11. By using such an annular spacer 19, the height of the upper mold 11 in the axial direction of the upper annular member 15 can be adjusted and finely adjusted to an appropriate height. Furthermore, it becomes easy to cope with the case where optical elements having different shapes are molded with one type of upper annular member 15.

Next, a method for manufacturing the optical element of the present invention using the mold 10 will be described.
First, a molding apparatus used for this optical element manufacturing method will be described.

  FIG. 6 is a schematic configuration diagram of an optical element molding apparatus (only the chamber 22 is shown in cross section).

  As shown in FIG. 6, an optical element molding apparatus 20 heats a chamber 22 serving as a molding chamber for molding an optical element, and a molding die containing an optical material provided in the chamber 22 to optically form the optical element. It has a heating stage 23 that softens the material, a press stage 24 that press-molds the heat-softened optical material, and a cooling stage 25 that cools the optical material to which the optical element shape is given by press molding.

  Here, the chamber 22 serving as a molding chamber provides a place for performing a molding operation of the optical element therein. The chamber 22 is provided with an inlet for taking the optical element molding die 10 into the interior and an outlet for taking out the molding die 10 after the molding of the optical element is finished. An intake shutter 26 and an extraction shutter 27 are provided. The mold 10 can be taken in and out of the chamber 22 by opening and closing the shutters 26 and 27 as necessary, and the atmosphere in the chamber 22 is maintained. Further, at the intake port and the take-out port, there are provided molding die mounting tables 28 and 29 on which the molding die 10 can be placed outside the chamber 22, respectively.

  Inside the chamber 22, a heating stage 23, a press stage 24, and a cooling stage 25 for molding the optical element are provided, and a molding operation is performed by these stages 23, 24, 25. Actually, the mold 10 containing the optical material is taken into the chamber 22 from the intake port, and is moved in order while being subjected to predetermined processing in each of the stages 23, 24, 25, and the predetermined processing is performed. When finished, the mold 10 is taken out of the chamber 22 through the take-out port.

  Inside the chamber 22, the mold 10 softens the optical material and facilitates deformation, and is heated to a high temperature. Therefore, the atmosphere in the chamber is inert gas such as nitrogen so that the mold 10 is not oxidized. Can be an atmosphere. This inert gas atmosphere can be achieved by replacing the internal atmosphere with the chamber 22 as a sealed structure, but it is a semi-sealed structure, and the inert gas is constantly supplied into the chamber 22 so that the chamber 22 is positively pressurized. However, an inert gas atmosphere may be maintained by preventing external air from flowing in. The intake shutter 26 and the extraction shutter 27 described above are effective for making the inside of the chamber 22 semi-sealed with a simple configuration. The chamber 22 and the shutters 26 and 27 are preferably made of a material that does not precipitate gas and impurities at a high temperature such as stainless steel or alloy steel.

  Next, each stage that performs the molding operation of the present invention will be described.

  The heating stage 23 softens the optical material accommodated in the mold 10, and is composed of a pair of upper and lower heating plates 23b in which a cartridge heater 23a is embedded. The heating plate 23b can heat the upper mold and the lower mold by bringing a pair of upper and lower heating plates 23b into contact with the upper mold and the lower mold of the molding die, and also has an optical material accommodated inside the molding mold. Can be heated.

  More specifically, in the heating stage 23, the lower heating plate 23 b is fixed to the bottom plate of the chamber 22 by laminating and fixing a heat insulating plate 23 c and a press plate 23 b in this order. Heat is not transferred to the chamber 22.

  The upper heating plate 23b can be moved up and down, and is also connected to a shaft 23d via a heat insulating plate 23c so that the heat of the upper heating plate 23b itself is not transmitted as it is. This shaft 23d is a cylinder (not shown). Thus, the heating plate 23b can be moved up and down. In this way, if the heating plate 23b can be moved up and down, contact / non-contact of the upper heating plate 23b with the upper mold of the mold 10 can be controlled, and the mold 10 and the optical material can be heated at a desired timing. .

  The press stage 24 reduces the distance between the upper and lower press plates 24b to reduce the distance between the upper mold and the lower mold of the mold 10 and presses the optical material accommodated in the mold 10 in a softened state. The optical element is molded by deforming and applying the molding surfaces of the upper mold and the lower mold to the optical material. It is composed of a pair of upper and lower press plates 24b in which a cartridge heater 24a is embedded. The press using the press plate 24b is performed while maintaining the heating temperature in the previous stage.

  More specifically, in this press stage 4, the lower press plate 24b is formed by laminating and fixing a heat insulating plate 24c and a press plate 24b in this order to the bottom plate of the chamber 22, and the lower press plate 24b. This heat is not transferred to the chamber 22.

  The upper press plate 24b can move up and down, and is also connected to a shaft 24d via a heat insulating plate 24c so that the heat of the upper press plate 24b itself is not transmitted as it is. This shaft 24d is a cylinder (not shown). Thus, the press plate 24b can be moved up and down. Thus, if the press plate 24b can be moved up and down, the upper press plate 24b can be lowered and press molding using the molding die 10 placed on the lower press plate 24b can be performed. At this time, press molding can be performed with a predetermined pressure, and the optical element shape can be imparted to the optical material with high accuracy.

  The cooling stage 25 cools and solidifies the optical material to which the optical element shape has been applied by cooling the mold 10, and includes a pair of upper and lower cooling plates 25 b in which cartridge heaters 25 a are embedded. Composed. The cooling plate 25b can cool the upper mold and the lower mold by bringing the pair of upper and lower cooling plates 25b into contact with the upper mold and the lower mold of the mold, and also cools the optical material accommodated in the mold. it can.

  More specifically, in this cooling stage 25, the lower cooling plate 25b is fixed to the bottom plate of the chamber 22 by laminating and fixing the heat insulating plate 25c and the cooling plate 25b in this order. The heat is not transmitted to the chamber 22.

  The upper cooling plate 25b can be moved up and down, and is also connected to a shaft 25d through a heat insulating plate 25c so that the heat of the upper cooling plate 5b itself is not transmitted as it is. This shaft 25d is a cylinder (not shown). Thus, the cooling plate 25b can be moved up and down. In this way, if the cooling plate 25b can be moved up and down, contact / non-contact of the upper cooling plate 25b with the upper mold of the mold 10 can be controlled, and the mold 10 and the optical material can be cooled at a desired timing. it can.

  The solidification of the optical material here may be cooled to the glass transition point or less of the material, more preferably to the strain point or less, and when sufficiently cooled, the shape of the optical material becomes stable and deformation is suppressed. . Cooling here means lowering to a temperature at which the optical material is solidified so that the press shape of the optical material can be stably applied. The temperature is only about 50 to 150 ° C. lower than the press plate, and still remains. Since the temperature is high, a heater 25a is embedded in the cooling plate 25b.

  Further, the heating plate 23b, the press plate 24b, and the cooling plate 25b on the upper side of each stage are fixed to the shaft via the heat insulating plate as described above, and this shaft is connected to the cylinder. The cylinder is only required to move each plate up and down. For example, an air cylinder, an electric servo cylinder, a hydraulic cylinder, an electric hydraulic cylinder, or the like can be used.

  The heating plate 23b, the press plate 24b, and the cooling plate 25b described above have a horizontal contact surface with the mold. In particular, the press plate 24b and the cooling plate 25b include the press plate 24b and the cooling plate 25b. When the contact surface with the mold is inclined, the central axes of the upper mold and the lower mold of the mold 10 do not coincide with each other, and the optical axes of the optical elements manufactured at this time do not coincide with each other, resulting in a defective product. Therefore, the parallelism and flatness of the plate at each stage are strictly managed.

  In each of these stages, the plate is the one in which a cartridge heater is inserted and fixed inside a material such as stainless steel, cemented carbide or alloy steel, and the temperature of the plate is raised by heating the cartridge heater to a desired temperature. Can be maintained.

  Further, the heat insulating plates 23c, 24c, 25c of each stage may be a known heat insulating plate such as ceramics, stainless steel, die steel, high-speed steel, etc., which has high hardness and is difficult to be deformed by pressure during press molding. It is preferable that the ceramic is less likely to cause the occurrence of the problem.

  The heating stage 23, the press stage 4, and the cooling stage 5 described above form stages on which predetermined processing is performed, and the molding die 10 is not shown so that the processing by each stage can be performed smoothly and sequentially. It is controlled by the control means so as to be transferred to and mounted on each stage at a predetermined timing by the transport means.

  More specifically, the processing by the heating plate 23b, the press plate 24b, and the cooling plate 25b is to perform predetermined processing while the mold 10 is sequentially transported and moved onto each plate in the above order. As the stage 10 moves to the next stage, the stage that has been processed becomes vacant, and further, a molding die 10 containing another optical material is transported there to continuously perform molding operations of a plurality of optical elements. It can be carried out.

  The conveying means for performing this processing is not shown, but is constituted by, for example, a robot arm or the like, and is formed from the mold mounting table 28 to the heating plate 23b, from the heating plate 23b to the press plate 24b, and from the press plate 24b. The mold is moved to the cooling plate 25b and from the cooling plate 25b to the mold mounting table 29.

  This control means also controls the temperature of the pair of upper and lower plates in each stage of heating, pressing, and cooling, the timing of vertical movement, etc., so that a series of molding operations can be performed smoothly and continuously. It is controlled to be able to. At this time, the opening and closing of the taking-in shutter and the taking-out shutter are also controlled. Furthermore, it is preferable to control the supply amount and timing of nitrogen so that the atmosphere in the chamber 22 is filled with an inert gas.

  In other words, the optical element molding apparatus 21 is an optical element molding apparatus that carries out a predetermined process while raising and lowering the temperature at one or more positions, by conveying a molding die.

Next, a method for molding the optical element of the present invention will be described.
First, an optical material is accommodated in the mold 10. At this time, as shown in the right half of FIG. 1, the optical material 1 is placed on the lower mold 12 of the mold 10, the upper mold 11 to which the upper annular member 15 is fixed is placed in the inner body 13, and the upper annular member 15 is The mold 10 is assembled by inserting until it contacts the optical material 1.

  Next, the assembled mold 10 is placed on the mold mounting table 28 on the intake port side, the intake shutter 26 is opened to open the intake port, and the mold 10 is conveyed onto the heating plate 23b by the conveying means. To do. When conveyed, the lower mold of the mold 10 is heated to the same temperature as the heating plate 23b because it contacts the lower heating plate 23b. At the same time, the upper die is brought into contact with the upper heating plate 23b from above and heated similarly.

  When the upper mold and the lower mold are heated in this way, the optical material housed therein is also heated, and when this optical material is heated above the yield point, the deformation becomes easy. Generally, the heating temperature is set to a temperature between the yield point (At) and the softening point because the lens surface becomes clouded when the temperature is raised to the softening point. At this time, the temperature rising rate is preferably about 0.5 to 2.5 ° C./sec.

  In this way, the mold 10 and the optical material that are sufficiently heated by the heating stage 23 are conveyed and placed on the lower press plate 24b by the conveying means.

  The press plate 24b is also heated to a temperature similar to that of the heating plate 23b so that the optical material is maintained in a softened state. Further, by lowering the upper press plate 24b and reducing the distance between the press plates 24b, the distance between the upper mold and the lower mold is reduced, and pressure is applied to the optical material accommodated in the mold 10. Can be transformed.

  In this pressing step, as described above, pressure molding is performed on the optical material by applying pressure from above and below the molding die 10, whereby the molding surfaces of the upper die and the lower die are transferred to the optical material, and the optical element shape is imparted. Is done.

In the press in this pressing step, the heating temperature is about the same as the temperature heated in the preceding heating stage, and the pressure during pressing is 2.5 to 37.5 N / mm ² per unit area of the lens molded body. For example, 10 to 20 N / mm ² is particularly preferable.

  And by performing such a press process, the shaping | molding die 10 in which the press cut was completed is conveyed from the press plate 24b to the cooling plate 25b by a conveyance means. This transport means is the same as the transport means described above.

  Next, the mold 10 is cooled by the cooling plate 25b. This is similar to the above heating process. The lower mold is the lower cooling plate 25b, and the upper mold is the upper cooling plate 25b lowered and brought into contact. Cool by. This cools and solidifies the optical material. At this time, the cooling temperature is preferably equal to or lower than the glass transition point (Tg) of the optical material, and more preferably equal to or lower than the strain point of the optical material. At this time, the cooling rate is preferably 0.1 to 2.5 ° C./sec, more preferably 0.5 to 1.0 ° C./sec.

  The heating plate 23b, the press plate 24b, and the cooling plate 25b all have a thermocouple embedded in the plate, and the output from the thermocouple is fed back to control the output of the cartridge heater to maintain a predetermined plate temperature. .

  In the heating process and the cooling process described above, it is preferable to gradually increase or decrease the temperature by changing the temperature stepwise, and by providing one or more heating stages, the temperature of the optical material is increased stepwise. Is raised to the molding temperature in the heating stage immediately before the press stage. Also, in the cooling process, one or more cooling stages are provided, and the temperature of the optical material is lowered stepwise so as to reach a temperature of 200 ° C. or lower. As described above, when heating and cooling are performed step by step, a rapid temperature change of the optical material can be suppressed, and molding can be performed without deteriorating the characteristics of the optical element such as distortion or surface cracking. Here, surface cracking means that when an optical element is released from a mold, only a part is released first, and then the rest is released, and an optical surface with a discontinuous curvature is formed. A mold release abnormality that causes a defect in which the accuracy of the aspheric shape deteriorates.

  In the method of manufacturing an optical element of the present invention, as shown in FIG. 1, the optical material 1 is heated in a state where it is sandwiched between the upper annular member 15 and the lower mold 12 without being in contact with the molding surface 11a of the upper mold 11. Since the press molding is started, there is no occurrence of burning due to overheating on the upper surface of the obtained optical element and no displacement of the optical material 1 as in the prior art.

  That is, when the optical material 1 is heated and softened and press-molded, the upper die 11 and the lower die 12 are heated and the heat is transferred to the optical material 1 to heat the optical material 1. The heat transfer to the optical material 1 is not from the two points of the center of the lower surface of the upper mold and the center of the lower surface of the lower mold as in the prior art, but the upper annular member contacting the heat from the upper mold at the peripheral edge of the optical material 1 Since the heat is transferred through the optical element 15, there is no “burn” due to overheating at the center of the upper surface of the optical element, and the optical material 1 and the upper annular member 15 are in contact with each other on the surface. In addition, the optical material 1 can be quickly heated and softened.

  Further, since the optical material 1 is not three-dimensionally held by the center of the lower surface of the upper mold and the center of the lower surface of the lower mold as in the prior art, the optical material 1 is three-dimensionally held. It is difficult for the optical material 1 to be misaligned during conveyance. For this reason, it becomes difficult for the bias of filling of the optical material 1 due to the positional deviation to occur, and the occurrence of cracks and the like can be prevented.

  In the molding die and the optical element manufacturing method described above, an upper annular member is provided around the upper molding surface of the upper die, and the upper die and the lower die are brought close to each other on the lower die during press molding. When pressing the placed optical material, the upper surface of the optical material is not in contact with the upper molding surface of the upper mold, but only in contact with the upper annular member. A lower annular member is provided around the lower part of the optical material when pressing the optical material placed on the lower die with the upper die and the lower die approaching each other during press molding. You may make it contact only a lower annular member, without contacting a surface.

  FIG. 7 shows an example thereof, which is a mold for manufacturing a biconcave optical element, similar to the mold 103 shown in FIG. The molding die 107 is provided on the lower annular member 55 around the lower molding surface 12a of the lower die 12 in addition to the upper annular member 15, and causes the upper die 11 and the lower die 12 to approach each other during press molding. When pressurization of the optical material 1 placed on the lower mold 12 is started, the lower surface of the optical material 1 does not come into contact with the molding surface 12a of the lower mold 12 and comes into contact only with the lower annular member 55. ing. The lower annular member 55 is fixed to the lower mold 11 by bringing the upper surface and the inner peripheral surface thereof into close contact with the lower mold 12 and inserting a fixing pin 56 radially from the outer periphery toward the lower mold 12. Yes. In FIG. 7, reference numeral 57 indicates a through hole for inserting a fixing pin formed in the lower annular member 55 and the lower mold 12.

  In this case, not only the upper surface of the obtained optical element but also the bottom surface can be prevented from being burned by overheating. That is, when the optical material 1 is heated and softened and press-molded, the upper die 11 and the lower die 12 are heated and the heat is transferred to the optical material 1 to heat the optical material 1. The heat transfer to the optical material 1 is not from the two points of the center of the lower surface of the upper mold and the center of the lower mold surface as in the prior art. The heat from the upper mold 11 is in contact with the upper peripheral edge of the optical material 1. Heat is transferred through the annular member 15, and the heat from the lower mold 12 is transferred through the lower annular member 55 in contact with the lower peripheral edge of the optical material 1. “Burn” does not occur, and “burn” due to overheating does not occur at the center of the lower surface of the optical element. In addition, since the heat transfer efficiency from the upper mold 11 and the heat transfer efficiency from the lower mold 12 are improved, the temperature rise and softening of the optical material 1 can be further promoted.

  In the implementation stage of the present invention, the constituent elements can be modified and embodied without departing from the technical idea of the present invention. In addition, various modifications are possible, such as appropriately combining a plurality of constituent elements shown in the above embodiment, or deleting some constituent elements from all the constituent elements shown in the embodiment. Furthermore, the embodiments of the present invention can be expanded or modified within the scope of the technical idea of the present invention, and these expanded and modified embodiments are also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The optical element manufacturing apparatus and optical element manufacturing method of the present invention are useful for manufacturing an optical element using a mold composed of an upper mold and a lower mold.

  DESCRIPTION OF SYMBOLS 1 ... Optical material 10,102-105,107 ... Mold, 11 ... Upper mold, 11a ... Upper molding surface, 12 ... Lower mold, 12a ... Lower molding surface, 13 ... Inner cylinder, 14 ... Outer cylinder, 15 ... Upper annular member, 20 ... Optical element molding apparatus, 23 ... Heating stage, 24 ... Press stage, 25 ... Cooling stage, 55 ... Lower annular member.

Claims (9)

An upper mold having a molding surface having a shape corresponding to the upper surface of the optical element to be molded, and a molding surface having a shape corresponding to the lower surface of the optical element to be molded, and this molding surface is used as the molding surface of the upper mold. An apparatus for manufacturing an optical element by heat-softening an optical material disposed between the upper mold and the lower mold, press molding,
An upper annular member is provided around the molding surface of the upper mold, and the upper annular member is pressed in a state where the optical material is sandwiched between the upper annular member and the lower mold without being in contact with the molding surface of the upper mold. An apparatus for manufacturing an optical element, wherein the apparatus is arranged to start molding.   The optical element manufacturing apparatus according to claim 1, wherein the upper annular member is detachably fixed to the upper mold.   The optical element manufacturing apparatus according to claim 1, wherein the upper annular member is fixed to the upper mold through a spacer.   A lower annular member is provided around the molding surface of the lower mold, and the lower annular member is sandwiched between the lower annular member and the upper annular member so that the optical material is not in contact with the molding surface of the lower mold. The optical element manufacturing apparatus according to any one of claims 1 to 3, wherein the optical element is arranged so that press molding is started in a closed state.   The optical element manufacturing apparatus according to claim 4, wherein the lower annular member is detachably fixed to the lower mold.   6. The optical element manufacturing apparatus according to claim 4, wherein the lower annular member is detachably fixed to the lower mold via a spacer.   The optical element manufacturing apparatus according to claim 1, wherein the optical element has any one of a biconvex shape, a biconcave shape, a convex meniscus shape, and a concave meniscus shape. An upper mold having a molding surface having a shape corresponding to the upper surface of the optical element to be molded and a lower mold having a molding surface having a shape corresponding to the lower surface of the optical element to be molded so that the molding surfaces face each other. After placing an optical material between these upper mold and lower mold, the optical material is heated and softened, press-molded to produce an optical element,
An upper annular member is provided around the molding surface of the upper mold, and the optical material is sandwiched between the upper annular member and the lower mold in a non-contact manner with the molding surface of the upper mold. The method of manufacturing an optical element is characterized in that the optical material is heat-softened and press-molded.   A lower annular member is provided around the molding surface of the lower mold, and the lower annular member is sandwiched between the lower annular member and the upper annular member so that the optical material is not in contact with the molding surface of the lower mold. The method of manufacturing an optical element according to claim 8, wherein the optical material is heat-softened and press-molded so as to be in a state of being formed.

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