JP2012158088A - Method of manufacturing optical element, and molding die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical element which makes appropriate the mold release resistance of a molded article with respect to a movable die, and prevents the deformation of the molded article when releasing the molded article from a die.SOLUTION: The mold release resistance of the resin molded article MP with respect to the movable die 42 is appropriately adjusted. Thereby, when opening a mold, the resin molded article MP can be released from a fixed die 41 while holding the whole resin molded article MP at the movable die 42 side. In addition, because the mold release resistance of the resin molded article MP with respect to the movable die 42 is appropriate, an excessive force is not required for releasing the resin molded article MP from the movable die 42, and the resin molded article MP can be released from the movable die 42. Thus, the deformation of the resin molded article MP can be prevented, and the defective appearance and performance of a lens LP occurring in releasing from the die can be prevented.

Description

  The present invention relates to a method for manufacturing an optical element incorporated in an optical pickup device and a molding die used in the manufacturing method.

  As a method for manufacturing an optical element, there is a method in which a molded product in which a runner is connected to an optical element is formed by injection molding, and the molded product is taken out from a mold (see Patent Document 1). At this time, after the molded product is released from the fixed mold in the mold opening in which the movable mold is moved relative to the fixed mold, the molded product remaining in the movable mold is released from the movable mold.

  However, if the mold release resistance of the molded product against the movable mold, such as cold slag and runner, is small, the molded product's sprue is pulled to the fixed mold side when the mold is opened, causing the molded product's cold slug, runner, etc. The molded product is deformed by being peeled off from the movable mold. For example, in the case of lens molding, since the mold release resistance of the lens is relatively larger than the mold release resistance of cold slag, runner or the like, the molded product is bent with the lens attached to the movable mold. As a result, the optical surface is rubbed against the movable mold at the time of mold release, and the optical element is scratched, causing problems of poor appearance and poor performance.

  Also, if the mold release resistance of the molded product against the movable mold is too large, there will be no problem when opening the mold, but the molded product will be removed from the movable mold, for example, when ejected by the ejector pin. It becomes difficult to sufficiently release the mold. For this reason, the molded product cannot be easily taken out by the take-out machine. Even when the molded product can be taken out, the runner or the like vibrates and the optical surface is rubbed against the movable mold, and the optical element may be damaged, resulting in a problem of poor appearance and poor performance.

JP 2005-288940 A

  Accordingly, an object of the present invention is to provide a method of manufacturing an optical element that makes it possible to appropriately set the release resistance of a molded product with respect to a movable mold and prevent the molded product from being deformed when the molded product is released. To do.

  Moreover, an object of this invention is to provide the shaping die for using with the manufacturing method of the said optical element.

  In order to solve the above problems, a method for manufacturing an optical element according to the present invention includes a movable mold having a first transfer surface for forming one optical surface of the optical elements, and the other optical surface of the optical elements. A first step of molding a molded article including an optical element in the molding space in a state where the molding space is formed by combining the stationary mold having the second transfer surface for forming the mold, the movable mold and the stationary mold The second step of releasing the molded product from the fixed mold while the molded product is stuck to the movable mold by opening the mold away from the mold, and after the second step, the molded product is released from the movable mold. A third step of molding, and the mold release resistance of the molded product is adjusted by adjusting means provided on the movable mold.

  In the optical element manufacturing method, by appropriately adjusting the mold release resistance of the molded product with respect to the movable mold, molding is performed from the fixed mold while holding the entire molded product on the movable mold side when the mold is opened. The product can be released. Also, since the release resistance of the molded product to the movable mold is appropriate, it is not necessary to use excessive force when releasing the molded product from the movable mold, and the molded product should be released from the movable mold. Can do. Thereby, it can prevent that a molded article deform | transforms and can prevent that an external appearance defect and a performance defect arise in an optical element at the time of mold release.

  In a specific aspect or aspect of the present invention, in the optical element manufacturing method, the fixed mold has a sprue channel that forms a sprue of a molded product, and the adjusting means is provided on an extension of the sprue channel. The mold release resistance is adjusted by changing the shape of the sprue lock pin. Here, the shape of the sprue lock pin includes a size such as a diameter. In this case, the mold release resistance of the molded product with respect to the movable mold can be adjusted by appropriately changing the shape of the sprue lock pin, for example, the diameter. For example, the release resistance of the cold slug to the movable mold can be increased by making the diameter of the sprue lock pin relatively large. Further, by reducing the diameter of the sprue lock pin, it is possible to reduce the mold release resistance of the cold slug with respect to the movable mold.

  In yet another aspect of the present invention, the adjusting means includes an ejector pin for ejecting the molded product in the third step, and the mold release resistance is adjusted by changing the length of the ejector pin. In this case, the release resistance of the molded product with respect to the movable mold can be adjusted by appropriately changing the length of the ejector pin. For example, by making the ejector pin shorter than the molding surface of the molded product, for example, the runner can bite into the movable mold, and the release resistance of the runner can be increased. Moreover, by making the ejector pin longer than the molding surface of the molded product, the ejector pin can bite into the runner, for example, and the release resistance of the runner can be increased.

  In still another aspect of the present invention, the fixed mold and the movable mold each have a runner flow path that forms a runner of the molded product, and the adjusting means includes the runner flow path, and the runner flow path of the movable mold The mold release resistance is adjusted by changing the curvature of the runner flow path of the fixed mold and the runner flow path of the fixed mold. In this case, the mold release resistance of the molded product with respect to the movable mold can be adjusted by appropriately changing the curvature of the runner flow path. For example, by making the curvature of the runner flow path of the movable mold larger than the curvature of the runner flow path of the fixed mold, the runner can bite into the movable mold, and the release resistance of the runner can be increased. Further, by making the curvature of the runner flow path of the movable mold the same as that of the runner flow path of the fixed mold, the mold release resistance of the runner can be made relatively small.

  In still another aspect of the present invention, the optical element is an optical element for an optical pickup device that records and / or reproduces information on an optical information recording medium. In this case, the optical element for the optical pickup device is small, and the release resistance of the lens of the optical element is relatively larger than the release resistance of cold slag, runner, etc., so that the release resistance of cold slag, runner, etc. If it is small, deformation of the molded product at the time of mold release tends to occur. Therefore, by adjusting the mold release resistance of the molded product with respect to the movable mold, deformation of the molded product at the time of mold release can be prevented.

  In still another aspect of the invention, the optical element is an objective lens of an optical pickup device.

  In still another aspect of the present invention, the curvature of the first transfer surface of the movable mold is larger than the curvature of the second transfer surface of the fixed mold. In this case, since the mold release resistance of the lens of the optical element on the first transfer surface having a large curvature is larger than the mold release resistance of the cold slug, runner, etc., when the mold release resistance of the cold slug, runner, etc. is small, The deformation of the molded product is more likely to occur. Therefore, by adjusting the mold release resistance of the molded product with respect to the movable mold, deformation of the molded product at the time of mold release can be prevented.

  In yet another aspect of the present invention, the distance from the parting surface, which is the mating surface of the movable mold and the fixed mold, to the apex of the first transfer surface of the movable mold is the first distance of the fixed mold from the parting surface. 2 Longer than the distance to the apex of the transfer surface.

  In yet another aspect of the present invention, the optical element satisfies 0.75 ≦ NA ≦ 0.90, where NA is the numerical aperture.

  In still another aspect of the present invention, when the thickness of the optical element on the optical axis is d and the focal length of the optical element in a light beam having a wavelength of 500 nm or less is f, 0.8 ≦ d / f ≦ 2 .0 is satisfied.

  In order to solve the above problems, a molding die according to the present invention forms a movable die having a first transfer surface for forming one optical surface of optical elements and the other optical surface of optical elements. And a fixed mold having an adjusting means for adjusting the mold release resistance of the molded product including the optical element.

  In the molding die, the mold release resistance of the molded product with respect to the movable mold can be adjusted appropriately, and the molded product can be released from the fixed die and the fixed die while preventing the deformation of the molded product. it can. Thereby, it is possible to prevent the appearance failure and the performance failure from occurring in the optical element at the time of release.

  In another aspect of the present invention, the fixed mold has a sprue channel that forms a sprue of the molded product, and the adjusting means includes a sprue lock pin provided on an extension of the sprue channel.

  In yet another aspect of the present invention, the sprue lock pin is replaceable with the movable mold incorporated in the injection molding apparatus. In this case, the sprue lock pin can be exchanged without taking down the movable mold from the injection molding apparatus or disassembling, and the mold release resistance of the molded product can be easily adjusted.

  In yet another aspect of the present invention, the adjusting means includes an ejector pin for ejecting the molded product.

  In yet another aspect of the present invention, the ejector pin is replaceable with the movable mold incorporated in the injection molding apparatus. In this case, the ejector pin can be replaced without taking down the movable mold from the injection molding apparatus or disassembling, and the mold release resistance of the molded product can be easily adjusted.

  In still another aspect of the present invention, the fixed mold and the movable mold each have a runner flow path that forms a runner of the molded product, and the adjusting means includes the runner flow path.

  In yet another aspect of the invention, the curvature of the runner channel of the movable mold is the same as the curvature of the runner channel of the fixed mold. In this case, the mold can be easily manufactured by making the cross sections of the runner flow paths of the movable mold and the fixed mold the same. In addition, a mass-produced mold can be used, and the cost can be reduced. Further, the cross section of the runner channel at the time of mold matching is circular, the cross sectional area of the runner channel is large, and the surface area is small. Therefore, the heat of the resin is difficult to escape to the mold, and the fluidity of the resin can be improved.

  In yet another aspect of the present invention, the curvature of the runner channel of the fixed mold is smaller than the curvature of the runner channel of the movable mold. In this case, the mold release resistance of the molded product with respect to the fixed mold is smaller than the mold release resistance of the molded product with respect to the movable mold, and the molded product can be reliably left in the movable mold when the mold is opened. Moreover, since the curvature of the runner flow path of the movable mold is relatively large, the fluidity of the resin is good.

It is a sectional side view explaining the structure of the shaping die concerning a 1st embodiment. (A) is the conceptual diagram which expanded a part of metal mold | die shown in FIG. 1, (B) is the conceptual diagram of the partial cross section of the resin molded product shape | molded by the metal mold | die shown in FIG. It is a partially expanded sectional view of the metal mold | die shown in FIG. (A) is a diagram for explaining after the resin molded product is protruded, and (B) is a diagram for explaining after the resin molded product is taken out. (A)-(C) is a figure explaining adjustment of mold release resistance by a sprue lock pin. (A), (B) is a figure explaining the modification of the engaging part provided in the front-end | tip of a sprue lock pin. (A)-(D) is a figure explaining adjustment of mold release resistance by a runner ejector pin. (A), (B) is a figure explaining adjustment of mold release resistance by setting of the depth ratio of a runner crevice. It is a conceptual diagram of the injection molding apparatus incorporating the metal mold | die shown in FIG. It is a flowchart explaining operation | movement of the injection molding apparatus of FIG. It is a flowchart explaining adjustment of operation | movement of the injection molding apparatus of FIG. (A), (B) is a figure explaining the shaping die concerning a 2nd embodiment.

[First Embodiment]
Hereinafter, an optical element manufacturing method and a molding die according to a first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the molding die 40 includes a fixed die 41 and a movable die 42. As shown in an enlarged view in FIG. 2A, the fixed mold 41 and the movable mold 42 are mold-matched with the parting surfaces PS1 and PS2, and the product portion of the resin molded product MP is shown. Cavities CV, which are mold spaces for molding the lens, are formed at a plurality of locations, and flow path spaces FC for supplying resin to the cavities CV are formed. The flow path space FC includes a sprue flow path and a runner flow path, and is a space for forming the sprue SP, the cold slug CP, and the runner RP of the resin molded product MP shown in FIG. Are respectively communicated with the cavity CV through the gate portion GS that forms the gate GP of the resin molded product MP. A lock hole 91 is formed in the cold slug CP of the resin molded product MP as a trace of a sprue lock pin described later.

  A fixed mold 41 shown in FIG. 1 has a parting surface PS1, a mold plate 51 for forming the flow path space FC in FIG. 2A, and a mounting plate 53 that supports the mold plate 51 from behind. Prepare.

  As shown in FIG. 3 in an enlarged manner, the template 51 forms a sprue bush hole 51a into which the tip end side of the sprue bush 71, which is a mold part for forming the sprue SP, is inserted, and a runner RP of the resin molded product MP. A runner recess 58b, a gate recess 58c for forming the gate GP, and a lens recess 58d for forming the lens LP are provided. A portion of the runner recess 58b, the gate recess 58c, and the lens recess 58d as a set is a shape transfer portion 51z for giving the outer shape of the resin molded product MP. The gate recess 58c and the lens recess 58d are formed by the leading end surface of the transfer member 55 that is inserted into and fixed to the core hole 51b formed in the template 51.

  The mounting plate 53 shown in FIG. 1 has a through hole 53 a into which the base of the sprue bush 71 is inserted, and supports and fixes the sprue bush 71 together with the template 51. At the time of injection molding, melted and fluid resin is introduced into the flow path 71a from the through hole 53a, that is, the base side of the sprue bush 71. The channel 71a communicates with the channel space FC in FIG.

  A movable mold 42 shown in FIG. 1 has a parting surface PS2 and a mold plate 61 for forming the flow path space FC of FIG. 2A, a receiving plate 62 that supports the mold plate 61 from behind, And a mounting plate 63 that supports the receiving plate 62 from behind.

  As shown in FIG. 3 in an enlarged manner, the template 61 includes a cold slug recess 68a that forms a cold slug CP, a runner recess 68b that forms a runner RP, a gate recess 68c that forms a gate GP, and a lens LP. A lens recess 68d to be formed. A portion of the cold slug recess 68a, the runner recess 68b, the gate recess 68c, and the lens recess 68d as a set serves as a shape transfer portion 61z for giving the outer shape of the resin molded product MP. The cold slug recess 68a is formed by a distal end surface of a cylindrical sprue ejector 65 that is inserted into an ejector hole 61a formed in the template 61 and can be displaced in the axis AX direction. Here, a sprue lock pin 69 is inserted into a pin hole 61 f formed at the center of the sprue ejector 65, and is fixed to the receiving plate 62. Even if the sprue ejector 65 is displaced in the axis AX direction with respect to the mold plate 61, the sprue lock pin 69 is not displaced with respect to the mold plate 61. It moves so as to be accommodated in the ejector 65. On the other hand, the lens recess 68 d is formed in a front end surface of the outer cylindrical peripheral member 66 inserted and fixed in the transfer member hole 61 b formed in the template 61 and a core hole 61 c formed in the center of the peripheral member 66. The core rod 67 is inserted and displaced in the direction of the axis AX.

  The body portion 62a of the receiving plate 62 is used to advance and retract the rod holes 62d through which the plurality of sprue rods 72 for advancing and retracting the sprue ejector 65 in the axis AX direction and the plurality of runner ejector pins 73 in the axis AX direction, respectively. The plurality of pin holes 62e and the plurality of core rods 74 for moving the core rod 67 back and forth are respectively provided with a plurality of rod holes 62f for moving back and forth in the axis AX direction.

  As shown in FIG. 1, the receiving plate 62 has a support portion 62b that supports the plate-like main body portion 62a from the back, and the ejector plate 76 is accommodated in a recess 62h formed on the back side of the support portion 62b. is doing. The ejector plate 76 supports the sprue rod 72, the runner ejector pin 73, and the core rod 74 from the root side, and advances and retreats in the axis AX direction together with these members 72, 73, and 74.

  The ejector plate 76 is urged toward the mounting plate 63 by an urging means (not shown). When the ejector plate 76 is pushed to advance toward the fixed mold 41 side by receiving an external force from the rear, the ejector plate 76 is shown in FIG. As shown, the actuator moves forward against the biasing means, moves the sprue rod 72 and the core rod 74 to the distal end side, and moves the sprue ejector 65 and the core rod 67 to the distal end side. As a result, in the resin molded product MP, the cold slug CP that contacts the sprue ejector 65 via the advancing sprue ejector 65 is pushed out of the cold slug recess 68a, and the lens LP that abuts the core rod 67 via the advancing core rod 67. Is pushed out of the lens recess 68d. At this time, the runner RP is pushed out of the runner recess 68b by the runner ejector pin 73 directly driven by the ejector plate 76. That is, the resin molded product MP is removed from the template 61 uniformly. Since the sprue lock pin 69 is maintained as it is even if the runner ejector pin 73 moves forward, the sprue lock pin 69 is pulled out from the cold slug CP as the runner ejector pin 73 moves forward.

  On the other hand, when the external force is no longer applied, the ejector plate 76 is retracted by the biasing means as shown in FIG. 4B, so that the sprue rod 72, the runner ejector pin 73, and the core rod 74 are at the root. Back to the side and returned to the respective retracted position. That is, the sprue ejector 65, the runner ejector pin 73, and the core rod 67 are housed in the template 61. However, the engaging portion 69 b of the sprue lock pin 69 is in a state of protruding from the end surface of the sprue ejector 65. As will be described in detail later, the engaging portion 69b is a means for leaving the resin molded product MP on the movable mold 42 side when the mold is opened. When the ejector plate 76 is retracted, the resin molded product MP is held by the chuck 21a of the hand 21 of the take-out device to be described later, so that it does not drop even if the resin molded product MP is released from the movable mold 42. It has become.

  The mounting plate 63 shown in FIG. 1 has an opening 63a connected to an ejector driving mechanism, which will be described later, and an ejector plate by a driving member 45a (see FIGS. 4A and 4B) provided in the ejector driving mechanism. An external force of a moderate magnitude that advances forward along the axis AX direction from behind can be applied to 76 at an appropriate timing.

  In the resin molded product MP shown in FIG. 2B, the lens LP as a main body is made of resin, and is provided on the outer side in the radial direction from the optical function unit OP having an optical function and the outer edge of the optical function unit OP. And a substantially annular flange portion FL. The lens LP is a thick-type optical pickup objective lens having a large protrusion on the first optical surface OS1 side. Specifically, the lens LP enables reading or writing of optical information corresponding to a BD (Blu-ray Disc) having a wavelength of 405 nm and a numerical aperture (NA) of 0.85, for example. Here, the optical specification of the lens LP is not limited to NA 0.85. For example, NA of 0.75 or more, specifically, 0.75 ≦ NA ≦ 0.90 can be used for various optical pickup objective lenses. It can correspond to a standard.

  The lens LP is 0.8 ≦ d / f ≦ 2.0, where d is the thickness of the lens LP on the optical axis OA and f is the focal length of the lens LP in a light beam having a wavelength of 500 nm or less. Meet.

  In the optical function unit OP of the lens LP, one first optical surface OS1 is disposed on the laser light source side, and is more than the other second optical surface OS2 disposed on the optical disk side that is an optical information recording medium. Also has a large curvature. In other words, the distance h1 from the parting surfaces PS1 and PS2 which are the mating surfaces of the fixed mold 41 and the movable mold 42 shown in FIG. 2A to the apex Q of the first transfer surface S1 of the movable mold 42 is The distance h2 from the parting surfaces PS1 and PS2 to the apex P of the second transfer surface S2 of the fixed mold 41 is longer.

  The flange portion FL is provided in a substantially annular shape outside the optical function portion OP in the radial direction. The flange portion FL includes a first flange surface FLa extending in the direction perpendicular to the optical axis OA on the first optical surface OS1 side, and a second flange surface FLb extending in the direction perpendicular to the optical axis OA on the second optical surface OS2 side. Have

  With reference to FIGS. 5A to 5C, the function and setting of the sprue lock pin 69 will be described. The sprue lock pin 69 has a spindle-shaped engagement portion 69b that fits into a lock hole 91 provided at the bottom of the cold slug CP of the resin molded product MP at the tip of the shaft portion 69a. The engaging portion 69b has a large diameter in the middle between both ends in the axial direction, and requires a predetermined force or more when the resin molded product MP is pulled out from the lock hole 91. That is, when the fixed mold 41 and the movable mold 42 are separated from each other and the mold is opened, the resin molded product MP is not only pulled to the movable mold 42 side, but the sprue SP of the resin molded product MP is fixed to the fixed mold. Since it is in close contact with the mold 41, it is also pulled to the fixed mold 41 side. When such a pulling force on the fixed mold 41 side, that is, a release resistance is increased, the resin molded product MP does not remain on the movable mold 42 side, and the resin molded product MP remains on the fixed mold 41 side. It becomes difficult to take out the resin molded product MP. For this reason, the resin molded product MP is left on the movable mold 42 side by providing the sprue lock pin 69 and strongly connecting the resin molded product MP to the engaging portion 69b. The sprue lock pin 69 is fixed to the main body portion 62a of the receiving plate 62, but is replaceable. By changing the sprue lock pin 69 and adjusting the shape of the engaging portion 69b, the adhesion force or release of the cold slug CP of the resin molded product MP to the cold slug recess 68a provided in the mold plate 61 of the movable mold 42 is achieved. The resistance can be adjusted. That is, the sprue lock pin 69 is an adjusting means for adjusting the mold release resistance of the resin molded product MP.

  For example, as shown in FIG. 5A, when the shape of the engaging portion 69b provided at the tip of the sprue lock pin 69, for example, the diameter is a reference value d0, the sprue lock pin that locks the resin molded product MP. The connection force of 69 becomes standard, and when the mold is opened, the resin molded product MP can be left on the movable mold 42 side, and the mold release resistance F20 for separating the resin molded product MP from the movable mold 42 is After mold opening, it will be slightly lower, but it will be moderate.

  As shown in FIG. 5B, when the diameter of the engaging portion 69b provided at the tip of the sprue lock pin 69 is a value d1 (d1> d0) slightly larger than the reference, the sprue lock pin for the resin molded product MP. The connecting force 69 is greater than the reference value. Also in this case, the resin molded product MP can be left on the movable mold 42 side when the mold is opened, but the mold release resistance F21 for separating the resin molded product MP from the movable mold 42 is shown in FIG. It becomes somewhat larger than the release resistance F20 in this case, and the resin molded product MP becomes somewhat difficult to separate from the movable mold 42.

  As shown in FIG. 5C, when the diameter of the engaging portion 69b provided at the tip of the sprue lock pin 69 is a value d3 (d3 <d0) slightly smaller than the reference, the sprue lock pin for the resin molded product MP. The connecting force 69 is smaller than the reference value. Also in this case, the resin molded product MP can be left on the movable mold 42 side when the mold is opened, but the mold release resistance F23 for separating the resin molded product MP from the movable mold 42 is shown in FIG. In this case, the resin molded product MP is somewhat easily separated from the movable mold 42.

  As described above, the resin molded product MP is released from the movable mold 42 using the sprue ejector 65 or the like by adjusting the shape, for example, the diameter, of the engaging portion 69b provided at the tip of the sprue lock pin 69. The mold release resistance can be adjusted. In the above description, the diameter of the engaging portion 69b of the sprue lock pin 69 is changed stepwise, but the diameter of the engaging portion 69b of the sprue lock pin 69 can be changed continuously. . In a specific example, the diameter of the engaging portion 69b was increased or decreased within a range of up to about 5% with respect to the reference value.

  In the above description, the diameter of the engaging portion 69b of the sprue lock pin 69 is adjusted, but the shape of the engaging portion 69b can be changed. For example, as shown in FIG. 6A, a flat surface 69c may be provided at the tip of the engaging portion 69b of the sprue lock pin 69. Thereby, the surface area which resin adheres to the engaging part 69b increases, and mold release resistance can be increased. As shown in FIG. 6B, the sprue lock pin 69 may have a conical shape, specifically, a flat surface 69c and a taper 69d that narrows from the flat surface 69c toward the sprue ejector 65.

  With reference to FIGS. 7A to 7D, functions and settings of the runner ejector pins 73 will be described. The runner ejector pin 73 is fixed to the ejector plate 76, but is replaceable. By changing the runner ejector pin 73 and adjusting its length, the adhesion force or release resistance of the resin molded product MP to the runner recess 68b provided on the end surface of the mold plate 61 of the movable mold 42 can be adjusted. it can. That is, the runner ejector pin 73 is an adjusting means for adjusting the mold release resistance of the resin molded product MP.

  For example, as shown in FIG. 7A, when the runner ejector pin 73 has a standard length, the tip end surface 73a of the runner ejector pin 73 coincides with the bottom surface BF that is the molding surface of the runner recess 68b. Become. In this case, no special projection is formed on the runner RP, and the mold release resistance F10 corresponding to the adhesion force of the runner RP to the runner recess 68b is minimized. It becomes most easily separated from the mold 42.

  As shown in FIG. 7B, when the runner ejector pin 73 is slightly shorter than the standard, the tip end surface 73a of the runner ejector pin 73 is smaller by a distance k1 inside the template 61 than the bottom surface BF of the runner recess 68b. Retracted. In this case, a low convex portion 92 is formed on the runner RP, and the convex portion 92 and the surface side of the runner concave portion 68b are fitted together. Therefore, the release resistance F11 corresponding to the adhesion force of the runner RP to the runner concave portion 68b is standard. Therefore, the runner RP and thus the resin molded product MP are somewhat difficult to separate from the movable mold 42.

  As shown in FIG. 7C, when the runner ejector pin 73 is considerably shorter than the standard, the tip end surface 73a of the runner ejector pin 73 has a larger distance k2 (inside of the bottom surface BF of the runner recess 68b, inside the template 61. Only k2> k1) is retracted. In this case, a high convex portion 192 is formed on the runner RP, and the convex portion 192 and the surface side of the runner concave portion 68b are fitted, so that the release resistance F12 (F12) corresponding to the adhesion force of the runner RP to the runner concave portion 68b. > F10, F11) becomes considerably large, and it becomes difficult to separate the runner RP and the resin molded product MP from the movable mold 42.

  As shown in FIG. 7D, when the runner ejector pin 73 is slightly longer, the tip end surface 73a of the runner ejector pin 73 protrudes from the bottom surface BF of the runner recess 68b by a distance k3. In this case, a shallow concave portion 93 is formed in the runner RP, and the concave portion 93 and the runner ejector pin 73 are fitted to each other. Therefore, a release resistance F13 corresponding to the adhesion force of the runner RP to the runner concave portion 68b and the runner ejector pin 73 is obtained. The runner RP and the resin molded product MP are somewhat difficult to separate from the movable mold 42. In this case, the resin molded product MP has an adhesive force to the runner ejector pins 73, and such an adhesive force becomes a resistance when the resin molded product MP is taken out from the movable mold 42.

  As described above, by adjusting the length of the runner ejector pin 73, the mold release resistance when the resin molded product MP is released from the movable mold 42 using the runner ejector pin 73 or the like can be adjusted. it can. Further, when the mold opening is performed with the fixed mold 41 and the movable mold 42 separated from each other, the ease with which the resin molded product MP remains on the movable mold 42 can also be adjusted. In the above description, the length of the runner ejector pin 73 has been described as being changed stepwise, but the length of the runner ejector pin 73 can also be changed continuously. In a specific example, the length of the runner ejector pin 73 was increased or decreased from the standard position in a range up to about 1.5 times the diameter of the runner ejector pin 73.

  With reference to FIG. 8 (A) and 8 (B), the setting of the runner recessed parts 58b and 68b formed in the template 51 and 61 is demonstrated. The runner recesses 58b and 68b are flow paths as runner flow paths corresponding to the runner RP of the resin molded product MP in the flow path space FC when the fixed mold 41 and the movable mold 42 are closed and clamped. Part FC1 is formed. Since both runner recesses 58b and 68b are in close contact with the runner RP when the mold is opened, adjusting the balance of the depths of both runner recesses 58b and 68b can easily leave the resin molded product MP in the movable mold 42. It is possible to adjust the height and to adjust the ease of taking out the resin molded product MP from the movable mold 42. That is, by adjusting the balance of the depths of the runner recesses 58b and 68b by exchanging the mold plates 51 and 61, etc., the adhesion force or release resistance of the resin molded product MP to the runner recesses 68b of the movable mold 42 can be reduced. Can be adjusted.

  For example, as shown in FIG. 8A, the depth p01 of the runner recess 58b provided in the fixed mold 41 is equal to the depth p02 of the runner recess 68b provided in the movable mold 42, that is, the fixed mold. When the curvature of the flow path portion FC1 on the 41 side and the curvature of the flow path portion FC1 on the movable mold 42 side are substantially the same, the mold release resistance F31 corresponding to the adhesion force of the runner RP to the movable runner recess 68b is The release resistance F32 corresponding to the adhesion force of the runner RP to the runner recess 58b on the fixed side is substantially equal. In this case, the mold release resistance F31 for separating the resin molded product MP from the movable mold 42 is slightly lowered after the mold is opened, but is moderate.

  As shown in FIG. 8B, the depth p11 of the runner recess 58b provided in the fixed mold 41 is shallower than the depth p12 of the runner recess 68b provided in the movable mold 42, that is, the fixed mold 41 side. When the curvature of the flow path portion FC1 is smaller than the curvature of the flow path portion FC1 on the movable mold 42 side, the release resistance F33 corresponding to the adhesion force of the runner RP to the runner recess 68b on the movable side is fixed to the runner RP fixed side. Becomes larger than the release resistance F34 corresponding to the adhesion force to the runner recess 58b and the balance is lost. In this case, the mold release resistance F33 for separating the resin molded product MP from the movable mold 42 is relatively large, although it slightly decreases after the mold is opened.

  FIG. 9 is a conceptual diagram of an injection molding apparatus incorporating the molding die 40 of the embodiment shown in FIG. The illustrated molding apparatus 100 includes an injection molding machine 10 that is a main body part that performs injection molding to produce a resin molded product MP, a take-out device 20 that is an accessory part that takes out the resin molded product MP from the injection molding machine 10, and molding. And a control device 30 that comprehensively controls the operation of each unit constituting the device 100.

  The injection molding machine 10 includes a fixed platen 11, a movable platen 12, a mold clamping plate 13, and an opening / closing drive device 15. The injection molding machine 10 enables molding by sandwiching a fixed mold 41 and a movable mold 42 between the fixed platen 11 and the movable platen 12 and clamping both the molds 41 and 42.

  The fixed platen 11 is fixed to the center of the support frame 14 and supports the take-out device 20 on the top thereof. The stationary platen 11 detachably supports the stationary mold 41. Note that the fixed platen 11 is fixed to the mold clamping plate 13 via a tie bar so that it can withstand the pressure of mold clamping during molding.

  The movable platen 12 is disposed so as to face the fixed platen 11, and is supported by the slide guide 15a so as to be movable forward and backward. The movable platen 12 detachably supports the movable mold 42. Note that an ejector drive mechanism 45 is incorporated in the movable platen 12. The ejector drive mechanism 45 is a part that operates the ejector plate 76 shown in FIG. 1, and the shape transfer of the movable mold 42 is performed by projecting the sprue rod 72, the runner ejector pin 73, and the core rod 74. This is for extruding the resin molded product MP held by the portion 61z toward the fixed mold 41 and releasing the molded product MP, and allows the resin molded product MP to be transferred by the take-out device 20.

  The mold clamping machine 13 is fixed to the end of the support frame 14. The mold clamping machine 13 supports the movable board 12 from the back via the power transmission part 15d of the opening / closing drive device 15 at the time of mold clamping.

  The opening / closing drive device 15 includes a slide guide 15a, a power transmission unit 15d, and an actuator 15e. The slide guide 15 a supports the movable platen 12 and enables a smooth reciprocating movement in the advancing and retreating direction with respect to the fixed platen 11. The power transmission unit 15 d expands and contracts by receiving a driving force from an actuator 15 e that operates under the control of the control device 30. As a result, the movable platen 12 moves close to and away from the mold clamping plate 13 and moves freely. As a result, the movable platen 12 and the fixed platen 11 are moved closer to and away from each other, and the fixed mold 41 Clamping and mold opening with the movable mold 42 are performed.

  The injection device 16 includes a raw material storage unit, a cylinder, a screw drive unit, and the like (not shown), and can inject molten resin in a temperature-controlled state from the resin injection nozzle 16a under the control of the control device 30. In the state where the fixed mold 41 and the movable mold 42 are clamped, the injection device 16 brings the resin injection nozzle 16a into contact with the sprue bush 71 shown in FIG. 1, and the flow path space FC (see FIG. 2A). The molten resin set at an appropriate temperature and pressure can be supplied at a desired timing.

  The take-out device 20 includes a hand 21 that can hold the resin molded product MP and a three-dimensional drive device 22 that moves the hand 21 three-dimensionally. The take-out device 20 operates at an appropriate timing under the control of the control device 30, and after the mold is opened with the fixed mold 41 and the movable mold 42 separated from each other, the resin molded product remaining in the movable mold 42 It has the role of holding the MP and carrying it out.

  The control device 30 includes an opening / closing control unit 31, an ejector control unit 33, a take-out device control unit 34, and the like. The opening / closing control unit 31 enables the molds 41 and 42 to be clamped and opened by operating the actuator 15e. The ejector control unit 33 operates the ejector drive mechanism 45 to push out the resin molded product MP remaining in the movable mold 42 when the mold is opened from the movable mold 42. The take-out device control unit 34 operates the take-out device 20 to grip the resin molded product MP remaining in the movable mold 42 after mold opening and mold release and carry it out of the injection molding machine 10.

  Although not described above, the control device 30 controls the operation of the injection device 16 to enter a cavity formed between the molds 41 and 42 from the resin injection nozzle 16a via the sprue bush 71. The resin is injected at the desired pressure. Further, the control device 30 operates the mold temperature controller (not shown) as appropriate so as to control the temperatures of the fixed mold 41 attached to the fixed platen 11 and the movable mold 42 attached to the movable platen 12. Keep it in proper condition.

  FIG. 10 is a flowchart conceptually illustrating the basic operation of the molding apparatus 100 shown in FIG.

  First, both molds 41 and 42 are heated to a temperature suitable for molding by a mold temperature controller (not shown) (step S10). Thereby, the temperature of the surface of the mold forming the cavity CV in both the molds 41 and 42 and the temperature in the vicinity thereof are 50 ° C. lower than the glass transition temperature of the molten resin supplied from the injection device 16 and the same. It is set as the state heated and maintained below the temperature 10 degreeC higher than a glass transition temperature. At this time, preferably, the temperature of the surface of the mold forming the cavity CV in both the molds 41 and 42 and the temperature in the vicinity thereof are at least 10 ° C. lower than the glass transition temperature of the molten resin supplied from the injection device 16. In this state, the temperature is kept below 10 ° C. higher than the glass transition temperature.

  Next, the opening / closing drive device 15 is operated to advance the movable platen 12 to start mold closing (step S11). By continuing the closing operation of the opening / closing drive device 15, the movable platen 12 moves to the fixed platen 11 side to the die contact position where the fixed die 41 and the movable die 42 come into contact with each other, and the die closing is completed. By further continuing the closing operation of the device 15, mold clamping is performed to clamp the fixed mold 41 and the movable mold 42 with necessary pressure (step S12).

  Next, in the injection molding machine 10, the injection device 16 is operated to inject the molten resin into the cavity CV between the fixed mold 41 and the movable mold 42 that are clamped at a required pressure. (Step S13). The injection molding machine 10 maintains the resin pressure in the cavity CV. At this time, the cavity CV and the flow path space FC (see FIG. 2) are appropriately heated by a mold temperature controller (not shown), and the molten resin supplied from the injection device 16 is slowly cooled, and the cavity CV A moderate cooling of the resin can be achieved. Note that, after the molten resin is introduced into the cavity CV, the molten resin in the cavity CV is gradually cooled by heat dissipation, so that the molten resin is solidified with the cooling and waits for completion of molding (step S14). .

  Next, in the injection molding machine 10, the opening / closing drive device 15 is operated to perform mold opening for retracting the movable platen 12 (step S15). Along with this, the movable mold 42 moves backward, and the fixed mold 41 and the movable mold 42 are separated. As a result, the resin molded product MP, that is, the lens LP is released from the fixed mold 41 while being held by the movable mold 42.

  Next, in the injection molding machine 10, the ejector drive mechanism 45 is operated, and the resin molded product MP including the lens LP and the like is ejected by the advancement of the sprue ejector 65, the core rod 67, etc. (step S16). As a result, the lens LP of the resin molded product MP is urged toward the tip surface of the core rod 67 and pushed out toward the fixed mold 41, and is released from the movable mold 42.

  Finally, the take-out device 20 is operated, and a hand 21 is used to place the resin molded product MP projected by the sprue rod 72, the runner ejector pin 73, and the core rod 74 driven by the ejector drive mechanism 45. It is gripped and carried outside (step S17).

  In the movable side mold release step (step S16) described above, the resin molded product MP is ejected by the sprue ejector 65, the core rod 67, and the runner ejector pin 73, but the cold slug recess 68a of the movable mold 42, When the adhesion force of the resin molded product MP to the runner recess 68b, the lens recess 68d, etc. is excessively large, the release resistance is increased, and the release of the resin molded product MP tends to be insufficient. When the resin molded product MP is forcibly taken out by the take-out device 20 in such a state that the mold release is insufficient, the runner RP is bent with respect to the sprue SP or the cold slug CP of the resin molded product MP, and the resin molded product MP. However, the so-called inverted umbrella shape causes damage and deformation of the lens LP, which causes the lens LP to become an unnecessary product and causes a decrease in yield. Therefore, in the present embodiment, by adjusting the shape of the engaging portion 69 b provided on the sprue lock pin 69, the resin molded product MP is removed from the movable die 42 while leaving the resin molded product MP in the movable die 42. The mold release resistance at the time of mold release is adjusted. Further, in the present embodiment, by adjusting the length of the runner ejector pin 73, the resin molded product MP is released from the movable mold 42 while leaving the resin molded product MP in the movable mold 42. The mold resistance will be adjusted. Further, in the present embodiment, the resin molded product MP is left in the movable mold 42 by adjusting the balance of the depths of the pair of runner recesses 58b and 68b provided in the mold plates 51 and 61. The mold release resistance when the MP is released from the movable mold 42 is adjusted.

  FIG. 11 is a flowchart conceptually illustrating the mold release state, that is, the adjustment of the mold release resistance of the movable mold 42. In the following, the deformed resin molded product MP is properly ejected and taken out from the movable mold 42, and the resin molded product MP that has not been deformed when the mold is opened is ejected from the movable mold 42 and taken out. This is called sticking out or taking out books.

  First, as shown in FIG. 5A, the sprue lock pin 69 in which the diameter of the engaging portion 69b is the reference value d0, and as shown in FIG. The runner ejector pin 73 coinciding with the bottom surface BF of 68b is incorporated into the movable mold 42 and injection molding is performed (step S20). In addition, as shown in FIG. 8A, in the flow path portion FC1 forming the runner RP, the depths p01 and p02 of the runner recesses 58b and 68b are substantially equal.

  After the injection molding in step S20, only the lens LP remains in the movable mold 42 when the mold is opened, and the runner RP and the cold slug CP of the resin molded product MP are released from the movable mold 42, so that the resin molded product MP is obtained. When deformed into a so-called inverted umbrella shape (Y in step S21), the sprue lock pin 69 has a diameter d1 (d1> d0) where the diameter of the engaging portion 69b is slightly larger than the reference, as shown in FIG. The sprue lock pin 69 is replaced to increase the mold release resistance, and injection molding is performed (step S22). In step S22, as shown in FIGS. 7B to 7D, the release resistance may be increased by replacing the runner ejector pins 73 with different lengths. Further, as shown in FIG. 8B, the depth p02 of the runner recess 68b is replaced with the mold plate 61 that becomes the flow path portion FC1 smaller than the runner recess 58b depth p01, and the separation on the fixed mold 41 side is changed. The mold resistance may be reduced.

  After the injection molding in step S22, when the resin molded product MP is deformed in a so-called inverted umbrella shape when the mold is opened (Y in step S23), the process returns to step S22.

  After the injection molding in step S20 or step S22, when the resin molded product MP is not deformed into a so-called inverted umbrella shape when the mold is opened (N in step S21 or N in step S23), The book is taken out (step S24).

  If a defective appearance or the like occurs in the lens LP of the resin molded product MP after the main protrusion / main extraction in step S24 (Y in step S25), as shown in FIG. 5D, the diameter of the engaging portion 69b is the reference. The sprue lock pin 69 having a slightly smaller value d3 is replaced with a smaller release resistance, and injection molding is performed (step S26).

  After the molding in step S26, when the resin molded product MP is deformed in a so-called inverted umbrella shape when the mold is opened (Y in step S27), the process returns to step S22.

  After the molding in step S26, when the resin molded product MP is not deformed in a so-called inverted umbrella shape when the mold is opened (N in step S27), the process returns to step S24.

  If no appearance defect or the like has occurred in the lens LP of the resin molded product MP after the main protrusion and main extraction in step S24 (N in step S25), the adjustment of the mold release resistance is finished.

  According to the manufacturing method and the molding die of the optical element of the present embodiment described above, the movable mold is opened when the mold is opened by appropriately adjusting the mold release resistance of the resin molded product MP with respect to the movable mold 42. The resin molded product MP can be released from the fixed mold 41 while holding the entire resin molded product MP on the 42 side. Further, since the mold release resistance of the resin molded product MP with respect to the movable mold 42 is appropriate, an excessive force is not required when releasing the resin molded product MP from the movable mold 42, and the The resin molded product MP can be released. Thereby, it is possible to prevent the resin molded product MP from being deformed, and it is possible to prevent appearance defects and poor performance from occurring in the lens LP at the time of mold release.

[Second Embodiment]
Hereinafter, an optical element manufacturing method and a molding die according to the second embodiment will be described. The manufacturing method of the optical element according to the second embodiment is a modification of the manufacturing method of the first embodiment, and items not specifically described are the same as those of the first embodiment.

  As shown in FIG. 12A, the sprue lock pin 169 has a screw 81 on the bottom, that is, on the receiving plate 62 side. A connection portion of the main body portion 62 a of the receiving plate 62 with the sprue lock pin 169 is provided with a screw (not shown) that is screwed into the screw 81. Thereby, the sprue lock pin 169 can be replaced without taking down the movable mold 42 from the injection molding machine 10 or disassembling it. An attaching / detaching tool fitting portion 169c for exchanging the sprue lock pin 169 from the end surface side of the movable mold 42, that is, the shape transfer portion 61z side is provided on the distal end side of the shaft portion 69a of the sprue lock pin 169. Yes.

  As shown in FIG. 12B, the runner ejector pin 173 has a screw 82 on the bottom, that is, on the ejector plate 76 side. A connection portion of the ejector plate 76 to the runner ejector pin 173 is provided with a screw (not shown) that is screwed into the screw 82. Thereby, the runner ejector pin 173 can be replaced without taking down or disassembling the movable mold 42 from the injection molding machine 10. An attaching / detaching tool fitting portion 173c for exchanging the runner ejector pin 173 from the end surface side of the movable mold 42, that is, from the shape transfer portion 61z side, is provided on the tip end surface 73a side of the runner ejector pin 173.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications are possible. For example, in the above-described embodiment, the shape of the cavity CV provided in the injection mold including the fixed mold 41 and the movable mold 42 can be various shapes. That is, the shape of the cavity CV formed by the lens recesses 58d, 68d and the like is merely an example, and can be appropriately changed according to the use of the lens LP and other optical elements.

  In the above embodiment, the first transfer surface S1 may be provided with a fine shape so as to form various diffractive structures or the like according to the application in the optical function part OP of the lens LP.

  Moreover, in the said embodiment, the mold release resistance of the resin molded product MP with respect to the movable metal mold | die 42 can be adjusted also by changing the depth of the cold slug recessed part 68a. For example, the mold release resistance can be increased by making the cold slug recess 68a relatively deep from the parting surface PS2. Further, the mold release resistance can be reduced by making the cold slug recess 68a relatively shallow from the parting surface PS2.

  In the above-described embodiment, the first optical surface OS1 having a large curvature in the lens LP is formed by the movable mold 42, but may be formed by the fixed mold 41. In this case, after the mold opening, the first optical surface OS1 is released from the fixed mold 41 in a state where the second optical surface OS2 of the lens LP is held on the movable mold 42.

DESCRIPTION OF SYMBOLS 10 ... Injection molding machine, OP ... Optical function part, 11 ... Fixed board, FL ... Flange part, 12 ... Movable board, 13 ... Clamping board, 15 ... Opening / closing drive device, 16 ... Injection device, 20 ... Extraction device, 21 ... hand, 30 ... control device, 40 ... molding die, 41 ... fixed die, 42 ... movable die, 45 ... ejector drive mechanism, 51,61 ... template, 62 ... receiving plate, 53,63 ... mounting plate 58b, 68b ... runner recess, 58c, 68c ... gate recess, 58d, 68d ... lens recess, 65 ... sprue ejector, 66 ... peripheral member, 67 ... core rod, 68a ... cold slug recess, 69, 169 ... sprue lock pin, 69b ... engaging portion, 71 ... sprue bush, 72 ... sprue rod, 73, 173 ... runner ejector pin, 74 ... core rod, 6 ... Ejector plate, 100 ... Molding device, AX ... Shaft, CP ... Cold slug, CV ... Cavity, FC ... Channel space, FC1 ... Channel part, GP ... Gate, GS ... Gate part, LP ... Lens, MP ... Plastic molded product, OA ... optical axis, OS1, OS2 ... optical surface, PS1, PS2 ... parting surface, RP ... runner, SP ... sprue

Claims (22)

A movable mold having a first transfer surface for forming one optical surface of the optical elements is matched with a fixed mold having a second transfer surface for forming the other optical surface of the optical elements. A first step of forming a molded product including the optical element in the molding space in a state where the molding space is formed,
A second step of releasing the molded product from the fixed mold in a state where the molded product is stuck to the movable mold by a mold opening for separating the movable mold and the fixed mold;
A third step of releasing the molded product from the movable mold after the second step;
With
A method for manufacturing an optical element, wherein a mold release resistance of the molded product is adjusted by adjusting means provided on the movable mold. The fixed mold has a sprue channel that forms a sprue of the molded product,
The adjusting means includes a sprue lock pin provided on an extension of the sprue channel,
The method for manufacturing an optical element according to claim 1, wherein the mold release resistance is adjusted by changing the shape of the sprue lock pin. The adjusting means includes an ejector pin for protruding the molded product in the third step,
The method for manufacturing an optical element according to claim 1, wherein the mold release resistance is adjusted by changing a length of the ejector pin. The fixed mold and the movable mold each have a runner flow path that forms a runner of the molded product,
The adjusting means includes the runner flow path,
The mold release resistance is adjusted by changing the curvature of the runner flow path of the movable mold and the curvature of the runner flow path of the fixed mold. The manufacturing method of the optical element of description.   The optical element according to any one of claims 1 to 4, wherein the optical element is an optical element for an optical pickup device that records and / or reproduces information on an optical information recording medium. Manufacturing method.   The method of manufacturing an optical element according to claim 5, wherein the optical element is an objective lens of the optical pickup device.   The optical element according to any one of claims 1 to 6, wherein a curvature of the first transfer surface of the movable mold is larger than a curvature of the second transfer surface of the fixed mold. Manufacturing method.   The distance from the parting surface that is the mating surface of the movable mold and the fixed mold to the apex of the first transfer surface of the movable mold is the second transfer of the fixed mold from the parting surface. The method for manufacturing an optical element according to any one of claims 1 to 7, wherein the distance is longer than a distance to a vertex of the surface.   9. The method of manufacturing an optical element according to claim 1, wherein the optical element satisfies 0.75 ≦ NA ≦ 0.90 when the numerical aperture is NA.   When the thickness on the optical axis of the optical element is d and the focal length of the optical element in a light beam having a wavelength of 500 nm or less is f, 0.8 ≦ d / f ≦ 2.0 is satisfied. The method for producing an optical element according to any one of claims 1 to 9. A movable mold having a first transfer surface for forming one optical surface of the optical elements;
A fixed mold having a second transfer surface for forming the other optical surface of the optical element, and an adjusting means for adjusting a mold release resistance of a molded product including the optical element;
A molding die comprising: The fixed mold has a sprue channel that forms a sprue of the molded product,
The molding die according to claim 11, wherein the adjusting means includes a sprue lock pin provided on an extension of the sprue channel.   The molding die according to claim 12, wherein the sprue lock pin is replaceable in a state where the movable die is incorporated in an injection molding apparatus.   14. The molding die according to claim 11, wherein the adjusting means includes an ejector pin for projecting the molded product.   The molding die according to claim 14, wherein the ejector pin is replaceable in a state where the movable die is incorporated in an injection molding apparatus. The fixed mold and the movable mold each have a runner flow path that forms a runner of the molded product,
The molding die according to claim 11, wherein the adjusting unit includes the runner flow path.   The molding die according to claim 16, wherein a curvature of the runner flow path of the movable mold is the same as a curvature of the runner flow path of the fixed mold.   The molding die according to claim 16, wherein a curvature of the runner flow path of the fixed mold is smaller than a curvature of the runner flow path of the movable mold.   19. The optical element according to claim 11, wherein the optical element is an optical element for an optical pickup device that records and / or reproduces information on an optical information recording medium. Manufacturing of.   20. The molding die according to claim 11, wherein a curvature of the first transfer surface of the movable die is larger than a curvature of the second transfer surface of the fixed die. Type.   21. The molding die according to claim 11, wherein the optical element satisfies 0.75 ≦ NA ≦ 0.90 when the numerical aperture is NA.   When the thickness on the optical axis of the optical element is d and the focal length of the optical element in a light beam having a wavelength of 500 nm or less is f, 0.8 ≦ d / f ≦ 2.0 is satisfied. The molding die according to any one of claims 11 to 21.

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