JP2010080012A - Objective lens for optical pickup, method of manufacturing the same, and forming mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens for an optical pickup that facilitates preventing the occurrence of damage and deformation and makes an optical surface with high accuracy. <P>SOLUTION: A protrusion 21 remaining on a first peripheral surface LPa has a striking imprint PS and protrudes near the central side to an outer edge so that the objective lens OL is supported in a comparatively stable manner by the tip of the protruding pin corresponding to the striking imprint PS when demolding the objective lens OL as a molded object from a movable mold in a forming process. Accordingly, the displacement of the objective lens OL is prevented and damage and deformation causing degradation of optical characteristic and accuracy of flatness is prevented on optical surfaces LSa, LSb and end surface EP. Further, as the striking imprint PS protrudes in the central side, a forming burr formed on the outer edge of the protruding part 21 can be lowered than the upper edge of the protruding part 21, thereby preventing the forming burr from becoming a dust through contact with a surrounding area during transportation and in use. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an objective lens for an optical pickup, a manufacturing method thereof, and a molding die, and more particularly, to collect a light beam from a light source on an optical information recording medium or to detect a light beam from an optical information recording medium. The present invention relates to an optical pickup objective lens and the like.

  As a method of manufacturing an optical pickup objective lens, a plurality of pins, which are a plurality of protruding portions provided in the first mold part, are provided after the mold opening for separating the first mold part from the second mold part. The molded product is released from the first mold by pushing the flange formed on the outer periphery of the optical functional surface of the molded product remaining in the first mold part to the second mold side. There is something to be made (see, for example, Patent Document 1).

In the manufacturing method described above, for example, the working distance is increased due to the burr formed in the protruding trace by denting the protruding trace of the pin and the peripheral portion from the surrounding flange surface (see FIG. 6 of Patent Document 1). It is possible to prevent the influence of deformation of the peripheral shape of the protruding trace. Moreover, it is possible to prevent the working distance from increasing due to the burrs formed on the protruding traces by making only the protruding protrusions of the pins recessed from the peripheral flange surface (see FIG. 7 of Patent Document 1).
JP 2007-196665 A

  However, in the above manufacturing method, when the pin is protruded from the inner surface of the second mold, the lens is likely to be displaced, or there is a risk of undesirable deformation around the protruding protrusion of the lens.

  That is, as described above, when the projecting trace of the pin and its peripheral part are recessed from the surroundings, the projecting trace protrudes and the lens is not held by the pin. Arise. This sometimes causes scratches on the optical surface of the lens when the molded product is taken out of the molding machine and transported to the next process. Further, when the molded product is taken out, the molded product and thus the lens may be deformed to deteriorate the optical performance.

  On the other hand, when only the protrusion of the pin is recessed from the surrounding flange surface as described above, the protrusion is recessed and the lens is held by the pin, but when the lens is removed from the pin, the periphery of the protrusion is deformed. It becomes easy to do. If the periphery of the protruding trace is deformed in this way, it leads to deformation of the optical surface of the lens, and when the mirror surface is provided on the flange on the outer periphery of the lens and used for adjustment when incorporated in the reference surface or optical pickup, the flatness thereof Etc., there is a possibility that the accuracy will deteriorate.

  In the case of an objective lens for an optical pickup, in the case of a high NA lens having NA of 0.6 or more, particularly NA of 0.75 to 0.95, the amount of coma generated due to misalignment between molds becomes large. At this time, it is desirable to project the objective lens with the pins rather than operating the core mold for transferring the optical surface to project the objective lens. However, when the objective lens is protruded by a pin, positional displacement of the objective lens and deformation around the protrusion trace become a problem. Particularly, in the case of a high NA lens having a large curvature and a large wall thickness of NA 0.75 to 0.95, separation is difficult. There is a growing need to protect the optical surface by minimizing the displacement of the objective lens during molding to prevent scratches and the like, and to prevent deformation around the protruding trace.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an objective lens for an optical pickup that can easily prevent the occurrence of scratches and deformations and can make the optical surface highly accurate.

  Another object of the present invention is to provide a manufacturing method and a molding die for the optical pickup objective lens as described above.

  In order to solve the above problems, an objective lens for an optical pickup according to the present invention includes (a) a first optical surface disposed on the optical information recording medium side, and (b) a first optical surface on the optical information recording medium side. A first outer peripheral surface provided on the outer peripheral side of the surface and having at least a part of a protruding portion projecting on the center side with respect to the outer edge side as an abutting trace; and (c) a second optical surface disposed on the light source side And (c) a second outer peripheral surface on the light source side and provided on the outer peripheral side with respect to the second optical surface. In addition, the outer edge side with respect to the above-described protrusions means an outline when the protrusion is viewed along a direction parallel to the optical axis or an inner portion close to the outline. Further, the abutting trace is usually formed on the tip side or the whole of the protrusion.

  According to the objective lens described above, the projection having at least a part of the abutting trace remaining on the first outer peripheral surface on the optical information recording medium side protrudes on the center side with respect to the outer edge side. When releasing the objective lens, which is a molded product, from the first mold for transferring the optical surface arranged on the medium side, the objective lens is relatively stabilized by the tip of the protrusion pin corresponding to the contact mark. Will be supported. Therefore, the position shift of the objective lens can be prevented, and the possibility that the optical performance is deteriorated due to scratches or deformations formed on the optical surface can be reduced. In addition, since the protrusion part which has an abutting trace in at least one part protrudes in the center side, the burr | flash at the time of the molding formed in an outer edge side can be made lower than a protrusion part. Therefore, it is possible to prevent the burrs at the time of molding from coming into contact with the surroundings at the time of conveyance and causing dust and the like, and it is not necessary to provide a burr escape structure so that the burrs are lower than the first outer peripheral surface.

  In a specific aspect or viewpoint of the present invention, in the objective lens, the first outer peripheral surface has a plurality of butting marks. In this case, the objective lens can be reliably supported using the protrusions formed on the plurality of butting marks.

  In another aspect of the present invention, a plurality of butting marks are formed at equiangular intervals around the optical axis. In this case, the objective lens can be stably supported with good balance by using the protrusions formed at equal angular intervals around the optical axis.

  In still another aspect of the present invention, the outer edge of the abutting trace is provided so as to protrude from the flat surface around the first outer peripheral surface. Here, the outer edge end of the abutting trace means an annular portion formed by the outer periphery of the tip end portion of the ejection pin. In this case, it is possible to reliably prevent the tip end portion of the protrusion pin corresponding to the abutting trace from being bitten into the first outer peripheral surface of the objective lens. Therefore, when removing the objective lens from the protrusion pin, 1 It can prevent that an outer peripheral surface deform | transforms. In many cases, the first outer peripheral surface is formed with a flat reference surface serving as a reference for alignment of the first optical surface, but the outer edge of the abutting trace is more than the flat surface around the first outer peripheral surface. In the case where the protrusion is provided, it is possible to prevent such deformation of the reference surface.

  In yet another aspect of the present invention, the outer edge of the abutting trace is provided at the same height as the flat surface around the first outer peripheral surface. In this case, it is possible to prevent the tip of the protrusion pin corresponding to the abutting mark from being bitten into the first outer peripheral surface of the objective lens. Therefore, when the objective lens is removed from the protrusion pin, the first outer periphery of the objective lens is removed. It is possible to prevent the surface from being deformed.

  In yet another aspect of the present invention, the outer peripheral portion of the abutting trace is formed on an inclined surface whose protrusion amount increases toward the central portion of the abutting trace. In this case, since the tip part of the protrusion pin and the protrusion part of the contact mark are fitted in a relatively easy state, it is easy to remove the objective lens from the protrusion pin.

  In yet another aspect of the present invention, the central portion of the abutting trace is formed on a flat surface substantially perpendicular to the optical axis. In this case, when the objective lens is stored or the like, the protruding portion of the abutting trace can be used as a support leg that is difficult to generate dust.

  In yet another aspect of the present invention, the abutting trace is formed in a truncated cone shape. In this case, the processing of the protruding pin is relatively easy.

  In yet another aspect of the present invention, the abutting trace is formed in a conical shape protruding toward the central portion. In this case, it is easy to process the protruding pin.

  In yet another aspect of the present invention, the (image side) numerical aperture NA of the objective lens is NA 0.75 or more. In this case, the objective lens for an optical pickup can be manufactured, transported, and stored with a high NA while suppressing the occurrence of scratches and deformation. Therefore, when such an objective lens is incorporated in an optical pickup device capable of reading and writing a BD (Blu-Ray Disc), high-precision reading or writing can be performed.

  An optical pickup objective lens manufacturing method according to the present invention includes: (a) a first step of molding a lens with the first mold and the second mold closed; and (b) a first mold. A second step of releasing the lens from the second mold by separating the second mold; and (c) the lens is separated from the first mold by using an ejection pin provided on the first mold side. And (d) a first mold for transferring a first optical surface disposed on the optical information recording medium side of the lens. Advancing and retreating in the front direction of the second transfer surface through a first transfer surface, a second transfer surface that transfers the first outer peripheral surface provided on the outer peripheral side of the first optical surface, and an opening provided in the second transfer surface (E) the ejection pin has a recess recessed at the center side with respect to the outer edge side. It is characterized in.

  According to the above manufacturing method, since the protruding pin has the recessed portion that is recessed at the center side with respect to the outer edge side, the protrusion having at least a part of the abutting trace remaining on the first outer peripheral surface is on the center side with respect to the outer edge side Will project. Therefore, when the objective lens, which is the molded product, is released from the first mold in order to transfer the optical surface disposed on the optical information recording medium side during molding, the objective is caused by the tip of the ejection pin corresponding to the abutting mark. The lens is supported relatively stably. Therefore, the position shift of the objective lens can be prevented, and the possibility that the optical performance is deteriorated due to the formation of scratches or deformations on the optical surface can be reduced. In addition, since the protrusion part which has an abutting trace in at least one part protrudes in the center side, the burr | flash at the time of shaping | molding formed in an outer edge side can be made lower than an upper end of a protrusion part. Therefore, it is possible to prevent the burrs at the time of molding from coming into contact with the surroundings at the time of conveyance or reading or writing of an optical information recording medium such as an optical disc and causing dust and the like, and the burrs are lower than the first outer peripheral surface. Thus, there is no need to provide a burr escape structure.

  An optical pickup objective lens molding die according to the present invention includes: (a) a first transfer surface for transferring a first optical surface disposed on the optical information recording medium side of the lens, and a first optical surface; A second transfer surface that transfers the first outer peripheral surface provided on the outer peripheral side; and a release pin that can be moved forward and backward in the front direction of the second transfer surface through an opening provided in the second transfer surface. (B) a third transfer surface that transfers a second optical surface provided on the light source side of the lens and a second outer peripheral surface provided on the outer peripheral side with respect to the second optical surface; ) The protruding pin has a concave portion that is recessed on the center side with respect to the outer edge side.

  According to the molding die described above, the protruding pin has a concave portion that is recessed at the center side with respect to the outer edge side, so that the protrusion having at least a part of the abutting trace remaining on the first outer peripheral surface is at the center with respect to the outer edge side Will project on the side. Therefore, when the objective lens, which is a molded product, is released from the first mold for transferring the optical surface disposed on the optical information recording medium side during molding, the tip of the ejection pin corresponding to the abutting trace is used. The objective lens is supported in a relatively stable state, and it is possible to prevent displacement of the objective lens, and scratches and deformations are formed on the optical surface or the mirror surface used for adjustment when incorporated in the optical pickup, resulting in optical performance and flatness. Deterioration of the accuracy of the degree can be reduced.

[First Embodiment]
Hereinafter, an objective lens for an optical pickup which is a first embodiment of the present invention, a manufacturing method thereof, and the like will be described with reference to the drawings.

  1A and 1B are a rear view and a front view of an optical pickup objective lens, FIG. 2 is a side view of the optical pickup objective lens, and FIG. 3 is an optical pickup objective lens. It is CC sectional drawing of.

  The illustrated objective lens OL is made of plastic and includes a circular center part OLa having an optical function and an annular flange part OLb extending in the outer diameter direction from the periphery of the center part OLa. The objective lens OL is an objective lens for BD (Blu-Ray Disc) having an NA of 0.85, for example, and satisfies various standards of BD.

  The center portion OLa of the objective lens OL has a slightly convex first optical surface LSa on the back side and a convex second optical surface LSb having a large curvature on the front side. Among these, the first optical surface LSa is disposed to face the BD that is an optical information recording medium when the objective lens OL is incorporated in the optical pickup device and operated. Further, the second optical surface LSb is disposed on the side closer to the reading or writing laser light source when the objective lens OL is incorporated in the optical pickup device and operated. An annular end surface EP is formed on the outer side of the first optical surface LSa that should be opposed to the BD, away from the optical axis OA, as a boundary portion with a first outer peripheral surface LPa described later. The end surface EP is a region formed of a flat surface that regularly reflects collimated light, for example, and is used when the objective lens OL is aligned.

  The flange portion OLb of the objective lens OL has a back-side annular first outer peripheral surface LPa, a front-side annular second outer peripheral surface LPb, and a cylindrical side surface SS.

  The first outer peripheral surface LPa on the back side is substantially flat, but has four protrusions 21 arranged at equiangular intervals along the circumferential direction. As will be described in detail later, these protrusions 21 are portions formed by transferring the shape of a protruding pin or a pin insertion hole (detailed later) during molding.

  Explaining the specific shape, the four protruding portions 21 are provided as portions protruding in the direction of the optical axis OA from the flat surface F1 spreading around the first outer peripheral surface LPa. Each protrusion 21 has a rotationally symmetric shape, and includes a columnar pedestal portion 21a and a frustoconical fitting portion 21b. The former pedestal portion 21a is formed by the pin insertion hole and has a cylindrical side surface perpendicular to the surrounding flat surface F1, and the latter fitting portion 21b is an abutting mark PS formed by the ejection pin. It protrudes on the center side rather than the peripheral side. That is, the fitting portion 21b has a conical side surface inclined with respect to the flat surface F1 on the peripheral side, and has a flat top surface F3 parallel to the flat surface F1 and the end surface portion EP on the central side. Each top surface F3 is disposed in the same plane perpendicular to the optical axis OA, and is higher than the first optical surface LSa in the optical axis OA direction with respect to the surrounding flat surface F1. As a result, the four protrusions 21 are disposed so as to protrude most toward the BD side so as to surround the first optical surface LSa, and function as a protector of the objective lens OL with respect to the BD. Moreover, since each protrusion part 21 is equally arrange | positioned along the outer periphery of the objective lens OL, and functions as a support leg, even if it is a case where the objective lens OL is set | placed, for example on a flat mounting base, 1st optical surface It is possible to easily prevent the LSa from being damaged. In addition, when the plurality of objective lenses OL are stored and transported side by side on the tray, the upper end of the projection 21 serving as a support leg is a flat top surface F3, so that the tip of the projection 21 is scraped and dust is collected. The possibility of occurrence can be reduced. Further, the fitting portion 21b, that is, the abutting mark PS in the projection portion 21, is fitted to the tip portion of the protruding pin at the time of molding, so that the objective lens OL after the mold release has a role of preventing misalignment including dropping and the like. Fulfill.

  In the flange portion OLb, the second outer peripheral surface LPb on the front side includes an attachment surface F2 that is a ring-shaped plane. The mounting surface F2 is used as a bonding surface for mounting when the objective lens OL is incorporated in the optical pickup device. That is, the objective lens OL is fixed by adhering the mounting surface F2 to a seating surface such as a lens holder via an adhesive. An annular recess 17a is formed inside the mounting surface F2 as a boundary with the second optical surface LSb, and an annular stepped portion 17b as a boundary with the side surface SS is formed outside the mounting surface F2. Is formed.

  In addition, when providing the several protrusion part 21 in the flange part OLb as mentioned above, compared with the case where a hollow is formed in a part of flange part OLb, the rigidity of the flange part OLb can be improved and objective lens OL is improved. The fluidity of the resin in the cavity (described later) of the molding die for molding the resin can be improved.

  FIG. 4 is a view for explaining a molding apparatus for carrying out this manufacturing method. FIG. 5A is a movable mold as a first mold among the molding dies 40 constituting the molding apparatus of FIG. 5B is an end view of the mold 41 as viewed from the A direction, and FIG. 5B is an end view of the fixed mold 42 as the second mold of the molding mold 40 as viewed from the B direction.

  The movable mold 41 and the fixed mold 42 constituting the molding mold 40 can be opened and closed with the parting line PL as a boundary. A cavity CV, which is a space formed between the molds 41 and 42 in the mold closed state shown in FIG. 4, corresponds to the shape of the objective lens OL as a molded product.

  The movable mold 41 corresponds to the first mold constituting the molding mold, and supports the mirror core 52 as the movable core mold and the movable core mold, and is fixed integrally. An outer peripheral mold 51 having a structure capable of moving, a plurality of projecting pins 54 that are released from the movable mold 41 by projecting an objective lens OL as a molded product, and the projecting pins 54 from the outer mold 51 to a fixed mold. And an advancing / retreating drive device 71 that moves forward and backward toward 42.

  In the movable mold 41, the outer peripheral mold 51 has an end face 51c that forms the parting line PL. Further, a second transfer surface 51 a for defining a flange region CVb in the cavity CV is provided on the center side of the outer peripheral mold 51. The second transfer surface 51a is formed by transferring the first outer peripheral surface LPa on the back side of the flange portion OLb of the objective lens OL. In the present embodiment, the side surface SS of the flange portion OLb is also formed by the second transfer surface 51a. In the periphery of the core insertion hole 56, which is a cylindrical cavity provided in the outer peripheral mold 51, there is a pin insertion hole 55 corresponding to the protrusion 21 or the contact mark PS of the objective lens OL, and the axis AX (of the objective lens OL). Four are formed at equiangular intervals around the optical axis OA. These pin insertion holes 55 extend in a direction parallel to the axis AX of the mirror core 52, and guide the protruding pin 54 so as to be slidable in a direction parallel to the axis AX. A first transfer surface 52a for defining a central region CVa of the cavity CV is provided on the distal end side of the mirror core 52 fixed in a state of being inserted into the core insertion hole 56. The first transfer surface 52a is formed to be slightly concave, and the first optical surface LSa of the center portion OLa of the objective lens OL and the end surface portion EP attached to the outer peripheral side are formed by transfer. The mirror core 52 is directly supported and fixed on the base side of the outer peripheral mold 51 by screws or the like (not shown), and the positional relationship between the first transfer surface 52a and the second transfer surface 51a is kept accurate. It is supposed to be.

  The four projecting pins 54 are fixed to the ejector plate on the base side, and are driven by the advance / retreat driving device 71 via the ejector plate so as to be movable along the axis AX1 in the pin insertion hole 55. Thereby, each protrusion pin 54 advances to the fixed mold 42 side when the objective lens OL is released from the movable mold 41 after the mold 40 is opened, and after the mold release until the mold is closed. Retreats to the back side of the movable mold 41 at an appropriate timing. More specifically, the advancing / retreating drive device 71 urges the protruding pin 54 in the forward direction on the distal end side through the ejector plate, so that the protruding pin 54 moves to the operating position, and the distal end portion 54a is moved to the pin insertion hole. The objective lens OL can be pushed out to the fixed mold 42 side, so that the objective lens OL can be pushed out from the movable mold 41 because the protrusion projects from the opening end 55a of 55, that is, the second transfer surface 51a of the outer peripheral mold 51. Can be released. When the forward / backward drive device 71 stops urging the ejector plate and the ejector pin 54 in the forward direction, the ejector pin 54 is moved to the retracted position by a return spring (not shown) provided on the ejector plate, and the tip portion thereof. 54 a retreats to the depth of the pin insertion hole 55, and the protruding pin 54 is accommodated in the outer peripheral mold 51.

  The tip 54a of each protruding pin 54 inserted into the pin insertion hole 55 of the outer peripheral mold 51 is a mortar-shaped recess 31 that is processed so as to be recessed at the center side with respect to the outer edge side. In other words, the recess 31 includes the axis AX1 and the bottom surface 31a around the axis AX1 and perpendicular to the axis AX1, and the conical side surface 31b that is uniformly inclined inwardly away from the axis AX1 by a predetermined distance or more. Note that the tip portions 54a of the four protruding pins 54 have the same shape, and are provided on the flange portion OLb of the objective lens OL by alignment of the retracted positions of the protruding pins 54 in the movable mold 41. All of the two protrusions 21 can have the same shape.

  In the illustrated example, the tip end portion 54 a of the protruding pin 54 is disposed at a position retracted from the inner surface position of the outer peripheral mold 51 of the movable mold 41. That is, the protruding pin 54 is disposed at a position that is retracted by a distance d from the position of the opening end 55 a of the pin insertion hole 55 formed in the outer peripheral mold 51. In this way, by retracting the protrusion pin 54 from the position of the opening end 55a, the height of the plurality of protrusions 21 formed on the back side of the flange portion OLb of the objective lens OL can be easily increased. . At this time, the fitting portion 21 b is formed in the projection 21 corresponding to the recess 31 of the projection pin 54, so that the projection pin 54 and the projection 21 are fitted when the projection pin 54 is released from the movable mold 41. Alignment is ensured, and positional deviation including dropping of the objective lens OL can be prevented. In addition, since the fitting portion 21b has a tapered conical side surface instead of a cylinder, the protrusion pin 54 can be easily separated from the concave portion 31, and the workability in the initial stage of the objective lens OL removal process can be improved. Further, as will be described in detail later by forming the fitting portion 21b on the projection portion 21, the molding burr inevitably formed on the outer periphery (outer edge end) of the pedestal portion 21a is positioned lower than the top surface F3. It is possible to prevent the molding burr from adversely affecting the assembly of the objective lens OL. That is, since the fitting portion 21b also functions as a burr relief structure, it is not necessary to form the burr relief structure specially by processing the outer peripheral mold 51 or the like. Furthermore, the protrusion 21 can also function as a simple support when attaching the protector for the BD of the objective lens OL.

  The protruding pin 54 does not need to have a uniform cross-sectional shape along the entire axis AX1, and may be thin at the tip 54a and thick at the root side, for example. That is, a step or the like for increasing the diameter as appropriate can be provided on the base side of the protruding pin 54.

  The movable mold 41 is moved forward and backward with respect to the fixed mold 42 at an appropriate timing by the mold opening / closing drive device 72. Specifically, the mold opening / closing drive device 72 moves the movable mold 41 close to the fixed mold 42 along the axis AX when the mold is closed, and brings both molds 41 and 42 into close contact with each other. CV is formed. Further, the mold opening / closing drive device 72 performs mold clamping by urging the movable mold 41 to the fixed mold 42 with a necessary pressure when the resin is injected into the cavity CV. On the other hand, the mold opening / closing drive device 72 moves the movable mold 41 so as to be separated from the fixed mold 42 along the axis AX when the mold is opened, and separates the objective lens OL as a molded product from the fixed mold 42. Perform mold and mold opening.

  The fixed mold 42 corresponds to the second mold constituting the molding mold, and supports the mirror core 62 as a fixed-side core mold and the fixed-side core mold and fixes them integrally. And an outer peripheral die 61 having a structure that enables the above.

  The outer peripheral mold 61 has an end face 61c that forms a parting line PL. A transfer surface 61a for defining the outermost periphery of the flange region CVb in the cavity CV is provided on the center side of the outer peripheral die 61, that is, the innermost periphery of the end surface 61c. A transfer surface 62a for defining the central region CVa and the main portion of the flange region CVb of the cavity CV is provided on the distal end side of the mirror core 62 fixed in a state of being inserted into the core insertion hole 66. ing. That is, the transfer surface 62a includes an optical surface transfer surface S2 corresponding to the first optical surface LSa of the center region CVa, a transfer surface S3 corresponding to the mounting surface F2 of the second outer peripheral surface LPb of the flange portion OLb, and the center. A transfer surface S4 corresponding to the concave portion 17a formed at the boundary between the region CVa and the flange portion OLb, and a transfer surface S5 corresponding to the step portion 17b formed at the outer edge of the flange portion OLb. Here, the optical surface transfer surface S2 is a concave surface having a large curvature, and the second optical surface LSb transferred by the optical surface transfer surface S2 is arranged on the laser light source side for reading or writing during the operation. The transfer surface 61a provided on the outer peripheral die 61 and the transfer surface 62a provided on the mirror core 62 cooperate to constitute a third transfer surface for transferring the second optical surface and the second outer peripheral surface. The mirror core 62 is directly supported and fixed on the base side of the outer peripheral mold 61 by screws or the like (not shown) so that the positional relationship between the pair of transfer surfaces 61a and 62a can be maintained precisely. Yes.

  FIG. 6A is an enlarged cross-sectional view for explaining the shape of the abutment mark PS formed on the flange portion OLb shown in FIG. The pedestal portion 21 a of the protrusion 21 is formed by the inner wall surface of the pin insertion hole 55, and the fitting portion 21 b is formed by the recess 31 of the distal end portion 54 a of the protruding pin 54. In other words, the fitting portion 21b of the protrusion 21 is an abutting mark PS itself obtained by transferring the tip portion 54a of the protruding pin 54, and the central portion 21e of the fitting portion 21b corresponds to the bottom surface 31a of the concave portion 31. The outer peripheral portion 21f of the fitting portion 21b is tapered corresponding to the conical side surface 31b of the recess 31, that is, a conical side surface whose projection amount increases in the direction of the axis AX1. Have. Here, a gap G having an appropriate thickness is formed between the protruding pin 54 and the pin insertion hole 55 to ensure sliding. At the time of molding, the resin inevitably flows into the gap G from the opening end 55a. Therefore, in the projection 21 of the objective lens OL that is a molded product, there is a molding burr on the outer periphery of the upper end of the pedestal 21a, that is, the outer edge 21x. 21d is inevitably formed. However, since the position of the outer edge end 21x is retracted to the main body side by the thickness of the fitting portion 21b, the tip of the molding burr 21d extending from the outer edge end 21x protrudes by adjusting the height h1 of the fitting portion 21b. The position can be lower than the top surface F3 of the portion 21. Therefore, since the molding burr 21d is formed in a low state close to the periphery of the protruding portion 21, it is possible to prevent the mounting state from being affected during transportation and storage of the objective lens OL, or to record or reproduce information. Sometimes it is possible to avoid interference with the surface of the BD, and it is possible to prevent dust from being generated by unintentional peeling of the molding burr 21d. Further, the height H of the protrusion 21 with respect to the flat surface F1 is set to a distance d corresponding to the retraction amount of the protrusion pin 54 from the opening end 55a and to the recess 31 formed at the tip 54a of the protrusion pin 54. It is the sum d + h1 with the height h1 of the fitting part 21b formed correspondingly. Here, the distance d corresponds to the height of the pedestal 21a, and is the height from the surrounding flat surface F1 to the outer edge 21x of the protrusion 21 or the distance in the axis AX1 direction. If the height H of each protrusion 21 is larger than the protrusion amount h0 of the first optical surface LSa relative to the flat surface F1, each protrusion 21 protrudes beyond the apex of the first optical surface LSa. Become. In this case, the protrusion 21 functions as a protector of the objective lens OL for BD. If the height H of each projection 21 is made larger than the projection amount h0 of the first optical surface LSa, the four projections 21 serve as support legs or support members for the objective lens OL. Even when placed on a flat mounting table, it is possible to easily prevent the first optical surface LSa from being damaged.

  FIG. 6B is an enlarged cross-sectional view illustrating the function of the protruding portion 21 shown in FIG. In the mold release stage of the objective lens OL, when the movable mold 41 is moved backward to open the mold, the objective lens OL remains on the movable mold 41, that is, the outer peripheral mold 51 side. Therefore, when the protrusion pin 54 is moved forward along the axis AX1 and moved to the operating position (arrow H side), the object lens OL is released from the movable mold 41 by being pushed out by the protrusion pin 54. At this time, the flange portion OLb is supported by the protrusion pins 54 via the contact mark PS of the protrusion 21. In other words, the entire objective lens OL is supported by the tip portions 54a of the four protruding pins 54 in a well-balanced manner. If it demonstrates concretely, the recessed part 31 is formed in the front-end | tip part 54a of the protrusion pin 54 as mentioned above. The concave portion 31 fits closely with the fitting portion 21b of the projection portion 21 formed on the flange portion OLb when the objective lens OL is cured. Since the fitting state between the tip 54a of the protrusion pin 54 and the protrusion 21 of the flange OLb is maintained even after the mold release stage by the protrusion after the mold opening, the objective lens OL is fixed to the movable mold 41. Supported in a precisely positioned state. Thereafter, the objective lens OL is taken out along the path I, for example, using a robot hand (not shown). That is, the objective lens OL can be easily separated from the protrusion pin 54 by first pulling out along the direction of the axis AX1, and thereafter, the protrusion pin 54 is retracted and returned to the original position, and the objective lens is moved by the robot hand. The OL is carried out of the molding die 40. In the above, since the protrusion pin 54 is fitted to the protrusion 21 of the objective lens OL, it is possible to prevent positional deviation including dropping of the objective lens OL. Further, as described above, since the displacement of the objective lens OL is prevented by the protruding pin 54 even after the mold release, the gripping of the objective lens OL by the robot hand is ensured, and the objective lens OL is not moved when the objective lens OL is conveyed. It is possible to reliably prevent the first optical surface LSa and the second optical surface LSb from being damaged. Further, when the objective lens OL is taken out of the mold, it is possible to prevent the objective lens OL from extending and the optical surfaces LSa and LSb from being deformed to deteriorate the optical performance.

  7 (A) and 7 (B) show a modification of the protrusion 21 shown in FIGS. 6 (A) and 6 (B). In this case, the height H = d + h1 of the protrusions 21 is generally low, and the height H of each protrusion 21 is smaller than the protrusion amount h0 of the first optical surface LSa with respect to the flat surface F1. It has become. That is, each protrusion 21 is retracted from the first optical surface LSa, but the molding burr 21d is protected from peeling or the like by the fitting part 21b, and the intention of the molding burr 21d is It is possible to prevent dust from being generated due to peeling. In addition, since each protrusion 21 is closely fitted to the recess 31 at the tip of the protrusion pin 54, the objective lens OL is accurately positioned with respect to the movable mold 41 even in the mold release stage by protrusion. Supported by

  FIG. 8 is a flowchart conceptually illustrating a method of manufacturing the objective lens OL using the molding apparatus shown in FIG. First, the movable mold 41 and the fixed mold 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 metal mold | die part which forms the cavity CV in both metal mold | dies 41 and 42, or its vicinity is made into the temperature state suitable for shaping | molding.

  Next, the mold opening / closing drive device 72 is operated to advance the movable mold 41 toward the fixed mold 42 to start mold closing (step S11). By continuing the closing operation of the mold opening / closing drive device 72, the mold closing state in which the movable mold 41 and the fixed mold 42 are brought into contact with each other, and by further continuing the closing operation of the mold opening / closing drive device 72, the movable mold is performed. Clamping is performed to clamp 41 and the fixed mold 42 with necessary pressure (step S12).

  Next, an injection device (not shown) is operated to inject the molten resin into the cavity CV between the clamped movable mold 41 and the fixed mold 42 with a necessary pressure through a gate or the like. (Step S13).

  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 it waits for the molten resin to solidify and complete molding with the cooling (step S14).

  Next, the mold opening / closing drive device 72 is operated to retract the movable mold 41 and perform mold opening to separate the movable mold 41 from the fixed mold 42 (step S15). As a result, the objective lens OL that is a molded product is released from the fixed mold 42 while being held by the movable mold 41.

  Next, the advancing / retreating drive device 71 is operated to project the objective lens OL by the ejecting pin 54 (step S16). Specifically, the four protruding pins 54 are protruded simultaneously, and the flange portion OLb of the objective lens OL is pushed out along the axis AX with good balance. As a result, the objective lens OL is urged against the distal end surface of the protruding pin 54 and pushed out toward the fixed mold 42, and the objective lens OL is released from the movable mold 41. In this protruding state, the flange portion OLb of the objective lens OL is supported by being aligned with the four protruding pins 54. At this time, the four protruding pins 54 are fitted to the four protruding portions 21 provided on the flange portion OLb, so that the objective lens OL can be prevented from being dropped or displaced.

  The objective lens OL released from both molds 41 and 42 is carried out of the molding apparatus by gripping a sprue portion or the like extending from the gate portion (not shown) of the objective lens OL (step). S17). Further, the objective lens OL after being carried out is subjected to external processing such as removal of the gate portion to be a product for shipment.

  According to the manufacturing method of the present embodiment described above, the protruding portion 21 remaining on the first outer peripheral surface LPa has the abutting mark PS and protrudes on the center side with respect to the outer edge side. When the objective lens OL, which is a molded product, is released from the mold (first mold) 41, the objective lens OL is supported relatively stably by the tip portion 54a of the protrusion pin 54 corresponding to the contact mark PS. It becomes the state. Therefore, it is possible to prevent the positional displacement of the objective lens OL, and it is possible to prevent the optical performance from being deteriorated due to the formation of scratches or deformations on the optical surfaces LSa and LSb. Further, since the abutting mark PS protrudes on the center side, the molding burr 21 d formed on the outer edge side of the protrusion 21 can be made lower than the upper end of the protrusion 21. Therefore, it is possible to prevent the molding burr 21d from coming into contact with the surroundings during transportation and causing dust and the like, and it is not necessary to provide a burr escape structure so that the molding burr 21d is lower than the first outer peripheral surface LPa.

[Second Embodiment]
Hereinafter, an optical pickup objective lens and the like according to the second embodiment will be described. The objective lens of the second embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

  FIG. 9A is an enlarged cross-sectional view for explaining the projections and the like of the objective lens of the second embodiment, and FIG. 9B is an enlarged cross-section for explaining the functions of the projections shown in FIG. 9A. FIG. In the present embodiment, the protruding portion 21 formed on the flange portion OLb of the objective lens OL does not have the pedestal portion 21a, and includes only the fitting portion 21b corresponding to the abutting trace PS. More specifically, in this case, the tip end portion 54a of the protruding pin 54 in the retracted position is arranged so as to coincide with the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. As a result, the protruding portion 21 does not have a portion formed by the inner wall surface of the pin insertion hole 55, and the height H of the protruding portion 21 is the height h1 itself of the fitting portion 21b.

  Also in the case of the objective lens OL of the second embodiment, the molding burr 21d extending from the outer edge 21x of the protrusion 21 is protected from peeling or the like by the fitting portion 21b, and the molding burr 21d is unintentionally peeled off. It is possible to prevent the generation of garbage. Further, since the protruding portion 21 closely fits with the concave portion 31 at the tip of the protruding pin 54, the objective lens OL is accurately positioned with respect to the movable mold 41 even in the mold release stage by protruding. Supported.

  In the case of the objective lens OL of the present embodiment, the height H = h1 of the protrusion 21 is relatively low by the amount that the pedestal 21a is not provided. Therefore, the height H of the protrusion 21 is smaller than the protrusion amount h0 of the first optical surface LSa with respect to the flat surface F1, and the protrusion 21 is retracted from the first optical surface LSa. It will be.

  10 (A) and 10 (B) show a modification of the protrusion 21 shown in FIGS. 9 (A) and 9 (B). In this case, the height H of the protruding portion 21 is still the height h1 of the fitting portion 21b, but the height H of the protruding portion 21 is larger than the protruding amount h0 of the first optical surface LSa. The protrusion 21 protrudes from the apex of the first optical surface LSa. Thereby, the protrusion 21 functions as a protector of the objective lens OL for the BD, and when the objective lens OL is placed on, for example, a flat mounting table, the first optical surface LSa is easily damaged. Can be prevented.

[Third Embodiment]
Hereinafter, an optical pickup objective lens and the like according to the third embodiment will be described. The objective lens of the third embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

  FIG. 11A is an enlarged cross-sectional view for explaining the abutting trace of the objective lens according to the third embodiment or a projection or the like, and FIG. 11B is a diagram of the abutting trace shown in FIG. It is an expanded sectional view explaining a function. In the present embodiment, the abutting trace PS formed on the flange portion OLb of the objective lens OL includes an annular groove portion 321a and a fitting portion 21b corresponding to a protruding portion. Specifically, the groove portion 321a is a circular groove having a V-shaped cross section, and the fitting portion 21b has a truncated cone shape. In the present embodiment, the tip end portion 54 a of the protruding pin 54 in the retracted position is disposed at a position protruding from the inner surface position of the outer peripheral mold 51 of the movable mold 41. That is, the protrusion pin 54 is disposed at a position protruding by a distance d ′ from the position of the opening end 55 a of the pin insertion hole 55 formed in the outer peripheral mold 51. As a result, the height H of the contact mark PS is a difference h1−d ′ obtained by subtracting a distance d ′ corresponding to the protrusion amount of the protrusion pin 54 from the height h1 of the fitting portion 21b.

  Also in the case of the objective lens OL of the third embodiment, the molding burr 21d extending from the outer edge 321x of the groove 321a is protected from peeling or the like by the fitting portion 21b. Can be prevented. Moreover, since the fitting part 21b which comprises the abutting trace PS closely_contact | adheres with the recessed part 31 at the front-end | tip 54 of the protrusion pin 54, objective lens OL is movable with respect to the movable metal mold | die 41 also in the mold release stage by protrusion. And is supported in an accurately positioned state.

  In the case of the objective lens OL of the present embodiment, the height H = h1-d ′ of the abutting trace PS is relatively lowered by the depth of the groove portion 321a. Therefore, the height H of the abutting trace PS is smaller than the protrusion amount h0 of the first optical surface LSa with respect to the flat surface F1, and the abutting trace PS recedes from the first optical surface LSa. Will be.

  12 (A) and 12 (B) show a modification of the butting mark PS shown in FIGS. 11 (A) and 11 (B). In this case, the height H of the butting trace PS is equal to h1−d ′, but the height H of the butting trace PS is larger than the projection amount h0 of the first optical surface LSa. The butting mark PS projects more than the apex of the first optical surface LSa. Thereby, the contact mark PS or the fitting portion 21b constituting the same functions as a protector of the objective lens OL with respect to the BD, and when the objective lens OL is placed on, for example, a flat mounting table, the first optical surface LSa. It is possible to easily prevent scratches and the like from occurring.

[Fourth Embodiment]
Hereinafter, an optical pickup objective lens and the like according to the fourth embodiment will be described. The objective lens of the fourth embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

  FIG. 13A is an enlarged cross-sectional view for explaining the projections and the like of the objective lens of the fourth embodiment, and FIG. 13B is an enlarged cross-section for explaining the functions of the projections shown in FIG. FIG. In the present embodiment, the protruding portion 21 formed on the flange portion OLb of the objective lens OL includes a pedestal portion 21a and a fitting portion 421b corresponding to the abutting mark PS. However, the fitting portion 421b serving as the contact mark PS obtained by transferring the tip portion 54a of the protrusion pin 54 does not have a flat bottom surface but has a conical side surface. The height H of the protrusion 21 can be set in the same manner as in the first embodiment, and although detailed illustration is omitted, the distance d corresponding to the retraction amount of the protrusion pin 54 from the opening end 55a, and the protrusion pin This is the sum of the height h1 of the fitting portion 421b formed corresponding to the concave portion 31 formed at the front end portion 54a of 54.

  Also in the case of the objective lens OL of the fourth embodiment, the molding burr 21d extending from the outer edge 21x of the protrusion 21 is protected from peeling or the like by the fitting portion 421b, and due to unintentional peeling of the molding burr 21d. It is possible to prevent the generation of garbage. Further, since the protruding portion 21 closely fits with the concave portion 31 at the tip of the protruding pin 54, the objective lens OL is accurately positioned with respect to the movable mold 41 even in the mold release stage by protruding. Supported. Further, the recess 31 formed in the protruding pin 54 has a conical shape that is relatively easy to process.

  In forming the objective lens OL of the present embodiment, the retracted position of the tip end portion 54a of the protruding pin 54 can be changed as appropriate. For example, as indicated by a one-dot difference line, the edge of the distal end portion 54a of the protruding pin 54 in the retracted position is arranged so as to coincide with the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. You can also. In this case, the pedestal 21 a does not exist in the protrusion 21. Further, as indicated by the two-dot difference line, the tip end portion 54a of the protruding pin 54 at the retracted position is protruded by an appropriate amount from the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. It can also be arranged. In this case, the fitting portion 421b is partially embedded in the flange portion OLb.

[Fifth Embodiment]
Hereinafter, an optical pickup objective lens and the like according to the fifth embodiment will be described. Note that the objective lens of the fifth embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

  FIG. 14A is an enlarged cross-sectional view for explaining the projections and the like of the objective lens of the fifth embodiment, and FIG. 14B is an enlarged cross-section for explaining the functions of the projections shown in FIG. FIG. In the present embodiment, the protruding portion 21 formed on the flange portion OLb of the objective lens OL includes a pedestal portion 21a and a fitting portion 521b corresponding to the abutting mark PS. However, the fitting portion 521b as the abutting mark PS obtained by transferring the tip portion 54a of the protruding pin 54 does not have a flat bottom surface but has a hemispherical surface. The height H of the protrusion 21 can be set in the same manner as in the first embodiment, and although detailed illustration is omitted, the distance d corresponding to the retraction amount of the protrusion pin 54 from the opening end 55a, and the protrusion pin It is the sum with the height h1 of the fitting part 521b formed corresponding to the recessed part 31 formed in the front-end | tip part 54a of 54. FIG.

  Also in the objective lens OL of the fifth embodiment, the molding burr 21d extending from the outer edge 21x of the protrusion 21 is protected from peeling or the like by the fitting portion 521b, and the molding burr 21d is unintentionally peeled off. It is possible to prevent the generation of garbage. Further, since the protruding portion 21 closely fits with the concave portion 31 at the tip of the protruding pin 54, the objective lens OL is accurately positioned with respect to the movable mold 41 even in the mold release stage by protruding. Supported. Further, the recess 31 formed in the protruding pin 54 is a hemisphere that is relatively easy to process.

  In forming the objective lens OL of the present embodiment, the retracted position of the tip end portion 54a of the protruding pin 54 can be changed as appropriate. For example, as indicated by a one-dot difference line, the edge of the distal end portion 54a of the protruding pin 54 in the retracted position is arranged so as to coincide with the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. You can also. Further, as indicated by a two-dot difference line, a position where the tip end portion 54a of the protruding pin 54 in the retracted position is protruded by a small appropriate amount from the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. It can also be arranged.

[Sixth Embodiment]
The objective lens for an optical pickup according to the sixth embodiment will be described below. The objective lens of the sixth embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

  FIG. 15A is an enlarged cross-sectional view for explaining the protrusions and the like of the objective lens according to the sixth embodiment, and FIG. 15B is an enlarged cross-section for explaining the function of the protrusions shown in FIG. FIG. In the present embodiment, the protruding portion 21 formed on the flange portion OLb of the objective lens OL is composed of a pedestal portion 21a and a fitting portion 621b corresponding to the butting mark PS, and the fitting portion 621b is It has a central portion 21e that is a cylindrical protrusion and a conical outer peripheral portion 21f. The height H of the protrusion 21 can be set similarly to the first embodiment.

  Also in the case of the objective lens OL of the sixth embodiment, the molding burr 21d extending from the outer edge 21x of the protrusion 21 is protected from peeling or the like by the fitting portion 621b, and the molding burr 21d is unintentionally peeled off. It is possible to prevent the generation of garbage. Further, since the protruding portion 21 closely fits with the concave portion 31 at the tip of the protruding pin 54, the objective lens OL is accurately positioned with respect to the movable mold 41 even in the mold release stage by protruding. Supported. Here, the support stability of the objective lens OL can be adjusted by adjusting the height or thickness of the central portion 21e in the direction of the axis AX1.

  In forming the objective lens OL of the present embodiment, the retracted position of the tip end portion 54a of the protruding pin 54 can be changed as appropriate. For example, as indicated by a one-dot difference line, the edge of the distal end portion 54a of the protruding pin 54 in the retracted position is arranged so as to coincide with the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. You can also. Further, as indicated by a two-dot difference line, a position where the tip end portion 54a of the protruding pin 54 in the retracted position is protruded by a small appropriate amount from the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. It can also be arranged.

[Seventh Embodiment]
Hereinafter, an optical pickup objective lens and the like according to the seventh embodiment will be described. The objective lens of the seventh embodiment is a modification of the first embodiment, and the parts that are not particularly described are the same as those of the first embodiment.

  FIG. 16A is an enlarged cross-sectional view for explaining the projections and the like of the objective lens of the seventh embodiment, and FIG. 16B is an enlarged cross-section for explaining the functions of the projections shown in FIG. FIG. In the present embodiment, the protruding portion 21 formed on the flange portion OLb of the objective lens OL is composed of a pedestal portion 21a and a fitting portion 721b corresponding to the butting mark PS, and the fitting portion 721b is It has a central portion 21e that is an annular portion and a conical outer peripheral portion 21f. The height H of the protrusion 21 can be set similarly to the first embodiment.

  Also in the objective lens OL of the seventh embodiment, the molding burr 21d extending from the outer edge 21x of the projection 21 is protected from peeling or the like by the fitting portion 721b, and the molding burr 21d is unintentionally peeled off. It is possible to prevent the generation of garbage. Further, since the protruding portion 21 closely fits with the concave portion 31 at the tip of the protruding pin 54, the objective lens OL is accurately positioned with respect to the movable mold 41 even in the mold release stage by protruding. Supported. Here, the support stability of the objective lens OL can be adjusted by adjusting the depth of the cylindrical depression provided in the central portion 21e in the direction of the axis AX1.

  In forming the objective lens OL of the present embodiment, the retracted position of the tip end portion 54a of the protruding pin 54 can be changed as appropriate. For example, as indicated by a one-dot difference line, the edge of the distal end portion 54a of the protruding pin 54 in the retracted position is arranged so as to coincide with the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. You can also. Further, as indicated by a two-dot difference line, a position where the tip end portion 54a of the protruding pin 54 in the retracted position is protruded by a small appropriate amount from the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. It can also be arranged.

[Eighth Embodiment]
Hereinafter, an optical pickup objective lens and the like according to the eighth embodiment will be described. Note that the objective lens of the eighth embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

  FIG. 17A is an enlarged cross-sectional view for explaining the protrusions and the like of the objective lens of the eighth embodiment, and FIG. 17B is an enlarged cross-section for explaining the functions of the protrusions shown in FIG. FIG. In the present embodiment, the protrusion 21 formed on the flange OLb of the objective lens OL is composed of a pedestal 21a and a frustoconical fitting portion 821b corresponding to the abutting mark PS. The top surface F3 at the upper end of the protrusion 21 is a flat circle, and the height H of the protrusion 21 can be set in the same manner as in the first embodiment.

  Also in the objective lens OL of the eighth embodiment, the molding burr 21d extending from the outer edge 21x of the protrusion 21 is protected from peeling or the like by the fitting portion 721b, and the molding burr 21d is unintentionally peeled off. It is possible to prevent the generation of garbage. Further, since the protruding portion 21 closely fits with the concave portion 31 at the tip of the protruding pin 54, the objective lens OL is accurately positioned with respect to the movable mold 41 even in the mold release stage by protruding. Supported. Here, the support stability of the objective lens OL can be adjusted by adjusting the height or thickness of the fitting portion 821b in the direction of the axis AX1.

  In forming the objective lens OL of the present embodiment, the retracted position of the tip end portion 54a of the protruding pin 54 can be changed as appropriate. For example, as indicated by a one-dot difference line, the edge of the distal end portion 54a of the protruding pin 54 in the retracted position is arranged so as to coincide with the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. You can also. Further, as indicated by a two-dot difference line, a position where the tip end portion 54a of the protruding pin 54 in the retracted position is protruded by a small appropriate amount from the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. It can also be arranged.

[Ninth Embodiment]
The following describes an optical pickup objective lens and the like according to the ninth embodiment. Note that the objective lens of the ninth embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

  FIG. 18A is an enlarged cross-sectional view for explaining the projections and the like of the objective lens of the ninth embodiment, and FIG. 18B is an enlarged cross-section for explaining the functions of the projections shown in FIG. FIG. In the present embodiment, the protruding portion 21 formed on the flange portion OLb of the objective lens OL is configured by a pedestal portion 21a and a fitting portion 921b corresponding to the butting mark PS, and the fitting portion 921b is It has a central portion 21e that is a hemispherical depression and a conical outer peripheral portion 21f. The height H of the protrusion 21 can be set similarly to the first embodiment.

  Also in the objective lens OL of the ninth embodiment, the molding burr 21d extending from the outer edge 21x of the protrusion 21 is protected from peeling or the like by the fitting portion 721b, and the molding burr 21d is not intentionally peeled off. It is possible to prevent the generation of garbage. Further, since the protruding portion 21 closely fits with the concave portion 31 at the tip of the protruding pin 54, the objective lens OL is accurately positioned with respect to the movable mold 41 even in the mold release stage by protruding. Supported.

  In forming the objective lens OL of the present embodiment, the retracted position of the tip end portion 54a of the protruding pin 54 can be changed as appropriate. For example, as indicated by a one-dot difference line, the edge of the distal end portion 54a of the protruding pin 54 in the retracted position is arranged so as to coincide with the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. You can also. Further, as indicated by a two-dot difference line, a position where the tip end portion 54a of the protruding pin 54 in the retracted position is protruded by a small appropriate amount from the inner surface position (position of the opening end 55a) of the outer peripheral mold 51 of the movable mold 41. It can also be arranged.

  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 projecting portion 21, the abutting trace PS, the concave portion 31 and the like have a rotationally symmetric shape.

  Further, the surfaces of the protrusions 21 and the abutting marks PS are not limited to smooth surfaces, and for example, roughening can be performed.

  Moreover, the cross-sectional shape of the protrusion pin 54 is not limited to a circle, and may be a rectangle or other various shapes.

  Further, it is not necessary that all the four protruding pins 54 for releasing the objective lens OL have the shape of the above-described embodiment, and only one or two protruding pins 54 can have the shape of the above-described embodiment.

  Moreover, the number of the projecting pins 54 for release disposed around the objective lens OL is not limited to four, but can be appropriately increased or decreased according to manufacturing conditions, for example, three.

  Further, the number of cavities CV provided in the molding die 40 constituted by the fixed die 42 and the movable die 41 is not limited to one, and a plurality of cavities CV can be provided. That is, for example, a plurality of mirror cores 62 can be embedded in the outer peripheral mold 61, and a plurality of sets of units including the mirror core 52 and the protruding pins 54 can be embedded in the movable mold 41 correspondingly. In this case, a plurality of objective lenses OL can be obtained by one-shot molding using both molds 41 and 42.

  Moreover, the shape of the transfer surfaces 52a and 62a on the front end side of the mirror cores 52 and 62 shown in FIG. 1 and the like is merely an example, and can be appropriately changed according to the detailed use of the objective lens OL.

  Further, the arrangement, the number of components, and the like of the protrusion pins 54 described in the above embodiment are merely examples, and can be changed as appropriate.

  In addition, the molding die 40 of the above embodiment is not limited to the horizontal type, and can be realized as either a horizontal type or a vertical type.

(A) is a rear view of the objective lens of the first embodiment, and (B) is a front view of the objective lens. It is a side view of the objective lens of a 1st embodiment. It is sectional drawing of the objective lens of 1st Embodiment. It is a figure explaining the shaping | molding apparatus for enforcing the manufacturing method of an objective lens. (A) is an end view of a movable mold, and (B) is an end view of a fixed mold. (A), (B) is sectional drawing explaining a shape and a function about the projection part of an objective lens. (A), (B) is sectional drawing explaining a shape and a function about the projection part of a modification. It is a flowchart explaining a manufacturing process. (A), (B) is sectional drawing explaining the shape and function about the projection part of the objective lens of 2nd Embodiment. (A), (B) is sectional drawing explaining a shape and a function about the projection part of a modification. (A), (B) is sectional drawing explaining the shape and function about the projection part of the objective lens of 3rd Embodiment. (A), (B) is sectional drawing explaining a shape and a function about the projection part of a modification. (A), (B) is sectional drawing explaining the shape and function about the projection part of the objective lens of 4th Embodiment. (A), (B) is sectional drawing explaining a shape and a function about the projection part of the objective lens of 5th Embodiment. (A), (B) is sectional drawing explaining a shape and a function about the projection part of the objective lens of 6th Embodiment. (A), (B) is sectional drawing explaining a shape and a function about the projection part of the objective lens of 7th Embodiment. (A), (B) is sectional drawing explaining the shape and function about the projection part of the objective lens of 8th Embodiment. (A), (B) is sectional drawing explaining a shape and a function about the projection part of the objective lens of 9th Embodiment.

Explanation of symbols

  21 ... Projection part, 21a ... Base part, 21b ... Fitting part, 21d ... Molding burr, 21x ... Outer edge end, 31 ... Recessed part, 31a ... Bottom face, 31b ... Conical side face, 40 ... Molding mold, 41 ... Movable mold 42 ... fixed mold, 51a ... second transfer surface, 52, 62 ... mirror core, 52a ... first transfer surface, 54 ... pin, 54a ... tip portion, 55 ... pin insertion hole, 55a ... open end, 61a, 62a ... third transfer surface, 71 ... advance / retreat drive device, 72 ... mold opening / closing drive device, AX ... axis, AX1 ... axis, CV ... cavity, CVa ... center region, CVb ... flange region, EP ... end surface portion, F1 ... flat Surface, F2 ... mounting surface, F3 ... top surface, LPa ... first outer peripheral surface, LPb ... second outer peripheral surface, LSa ... first optical surface, LSb ... second optical surface, OA ... optical axis, OL ... objective lens, OLa ... Heart part, OLb ... flange portion, PS ... abutment mark

Claims (12)

A first optical surface disposed on the optical information recording medium side;
A first outer peripheral surface provided on the outer peripheral side of the first optical surface on the optical information recording medium side, and having at least a part of a protruding portion protruding on the central side with respect to the outer edge side as an abutment trace;
A second optical surface disposed on the light source side;
A second outer peripheral surface on the light source side and provided on the outer peripheral side of the second optical surface;
An optical pickup objective lens comprising:   The objective lens for an optical pickup according to claim 1, wherein the first outer peripheral surface has a plurality of the abutting traces.   The objective lens for an optical pickup according to claim 2, wherein the abutting traces are formed at equiangular intervals around the optical axis.   4. The light according to claim 1, wherein an outer edge of the abutting trace is provided so as to protrude from a flat surface around the first outer peripheral surface. 5. Objective lens for pickup.   4. The outer edge of the abutting mark is provided at the same height position as a flat surface around the first outer peripheral surface, according to claim 1. Objective lens for optical pickup.   The outer peripheral portion of the abutting trace is formed on an inclined surface in which a projection amount increases toward a central portion of the abutting trace, according to any one of claims 1 to 5. The objective lens for optical pickup as described.   The objective lens for an optical pickup according to any one of claims 1 to 6, wherein a central portion of the abutting trace is formed on a flat surface substantially perpendicular to the optical axis.   The objective lens for an optical pickup according to claim 7, wherein the abutting trace is formed in a truncated cone shape.   The objective lens for an optical pickup according to any one of claims 1 to 6, wherein the abutting trace is formed in a conical shape protruding toward a central portion.   The objective lens for an optical pickup according to any one of claims 1 to 9, wherein NA is 0.75 or more. A first step of molding the lens with the first mold and the second mold closed;
A second step of releasing the lens from the second mold by separating the first mold and the second mold;
A third step of releasing the lens from the first mold using a protruding pin provided on the first mold side, and a manufacturing method of an objective lens for an optical pickup comprising:
The first mold includes a first transfer surface for transferring a first optical surface disposed on the optical information recording medium side of the lens, and a first outer peripheral surface provided on the outer peripheral side of the first optical surface. A second transfer surface for transferring the sheet, and a release pin that can be moved forward and backward in the front direction of the second transfer surface through an opening provided in the second transfer surface,
The method of manufacturing an objective lens for an optical pickup, wherein the protrusion pin has a concave portion that is recessed on the center side with respect to the outer edge side. A first transfer surface for transferring a first optical surface disposed on the optical information recording medium side of the lens, and a second transfer surface for transferring a first outer peripheral surface provided on the outer peripheral side of the first optical surface; A first mold having a release pin that can be moved forward and backward in the front direction of the second transfer surface through an opening provided in the second transfer surface;
A second mold having a third transfer surface for transferring a second optical surface provided on the light source side of the lens and a second outer peripheral surface provided on the outer peripheral side of the second optical surface;
The extrusion pin has a concave portion that is depressed on the center side with respect to the outer edge side, and a molding die for an objective lens for an optical pickup.

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