JP4946831B2 - Optical element - Google Patents

Description

  The present invention relates to an optical element obtained by molding a resin, and particularly relates to an optical element used as an objective lens or the like incorporated in an optical pickup device.

A conventional mold for resin molding includes a first mold part in which an optical element remains in an opened state and a second mold part in which an optical element does not remain in an opened state. In order to release the optical element from the optical element, there is one in which a protruding part that protrudes the flange part of the optical element is provided in the first mold part (see Patent Document 1). Here, the portion where the contact portion trace is formed in the flange portion of the optical element by the contact of the protruding portion is formed in a depression lower than the surface of the other flange portion, and the flange portion is formed by the protruding portion. The burr generated around the trace of the contact portion is prevented from protruding from the surface of the other flange portion, and when the optical element is an objective lens for an optical pickup device, the working distance is shortened. To prevent that.
JP 2007-196665 A

  However, when the optical element molded by the above resin molding die is observed from the lateral direction perpendicular to the optical axis, although the contact portion trace is formed in the recess of the flange portion, the periphery of the contact portion trace Is surrounded by the flange portion except for some directions, the entire burr generated around the contact portion trace by the protruding portion cannot be easily confirmed from the outer side surface side of the optical element. For this reason, for example, during repeated molding of an optical element using a resin molding die, it is impossible to easily check and manage the state of burrs and their changes, and prevent burrs from exceeding the allowable range. There is a problem that it is difficult.

  Therefore, the present invention not only prevents the burr around the abutting portion generated in the flange portion due to the abutting of the protruding portion from protruding from the surface of the other flange portion, but also occurs around the abutting portion of the protruding portion. An object of the present invention is to provide an optical element capable of easily and reliably confirming burrs from the outside over the entire circumference.

In order to solve the above problems, an optical element according to the present invention is an optical element that includes a lens body portion and an annular flange portion that extends around the lens body portion, and is formed by resin injection molding. The flange portion has a recess in the periphery of the pin contact portion and the pin contact portion with which the protruding pin is contacted at the time of mold release, and when the recess is viewed from the optical axis direction of the optical element, The flange portion is formed over the entire region closer to the pin contact portion than the predetermined tangent line, with reference to a predetermined tangent line that contacts the outer periphery of the pin contact portion and passes outside the outer periphery of the lens body portion. , in the region of the wall thickness excluding the recess, characterized Rukoto that having a top end surface extending from the inner periphery of the flange portion to the outer periphery of the flange portion.

  In the optical element, the concave portion is in all regions closer to the pin abutting portion than the predetermined tangent with reference to a predetermined tangent that is in contact with the outer periphery of the pin abutting portion and passes outside the outer periphery of the lens body portion. When the concave portion is observed from the outer side surface, the tip of the burr extending upward from the periphery of the pin contact portion, that is, the pin contact portion trace toward the upper end surface position of the flange portion is observed from the outside. It can be easily confirmed over the circumference. Therefore, it is possible to easily and surely check the burr generated around the abutting part of the protruding part from the outside over the entire circumference, and facilitate the management to prevent the occurrence of a burr exceeding the allowable range. .

  According to a specific aspect or aspect of the present invention, in the optical element, the predetermined tangent line is orthogonal to a line segment connecting the center of the lens main body portion and the center of the pin contact portion. In this case, by observing the concave portion from the outer side surface of the flange portion, the burr extending above the pin contact portion can be reliably confirmed over the entire circumference. In addition, the optical element can be easily formed in a well-balanced manner without complicating the flange shape. In particular, when a concave portion is provided for each of a plurality of pin abutting portions, the concave portion can be easily arranged in a well-balanced manner on the flange portion of the optical element, and the balance of resin fluidity during injection molding can be achieved. It can be easily secured.

  Further, according to a specific aspect or aspect of the present invention, in the optical element, when the concave portion is viewed from the optical axis direction of the optical element, the lens body portion of the tangent line that contacts the outer periphery of the pin contact portion. It is formed in all regions on the pin contact portion side with respect to a tangent line perpendicular to a line segment connecting the center and the center of the pin contact portion. In this case, by observing the concave portion from the outer side surface of the flange portion, the burr extending above the pin contact portion can be reliably confirmed over the entire circumference. In addition, the optical element can be easily formed in a well-balanced manner without complicating the flange shape. In particular, when a concave portion is provided for each of a plurality of pin abutting portions, the concave portion can be easily arranged in a well-balanced manner on the flange portion of the optical element, and the balance of resin fluidity during injection molding can be achieved. It can be easily secured.

  According to a specific aspect or aspect of the present invention, in the optical element, the concave portion is orthogonal to a line segment connecting the center of the lens main body portion and the center of the pin contact portion, and the lens main body portion and the pin. It is formed over the entire region on the pin contact portion side rather than a straight line that does not intersect the contact portion. In this case, by observing the concave portion from the outer side surface of the flange portion, the burr extending above the pin contact portion can be more easily confirmed over the entire circumference. In addition, the optical element can be easily formed in a well-balanced manner without complicating the flange shape. In particular, when a concave portion is provided for each of a plurality of pin abutting portions, the concave portion can be easily arranged in a well-balanced manner on the flange portion of the optical element, and the balance of resin fluidity during injection molding can be achieved. It can be easily secured.

  According to another aspect of the present invention, when the concave portion is viewed from the side surface direction perpendicular to the optical axis of the lens main body portion, the tip end portion of the burr extending upward from the pin contact portion, that is, the pin contact portion trace Has a shape that enables observation. In this case, the entire circumference of the tip portion of the burr can be easily confirmed from the side surface direction of the flange portion.

  According to still another aspect of the present invention, pin contact portions are provided at a plurality of locations along the flange portion. In this case, since the optical element is released at a plurality of locations dispersed by the plurality of protruding pins, each protruding pin can be made relatively small, and a local force acts on the flange portion to cause the optical element to be released. Can be easily prevented from deteriorating.

  According to still another aspect of the present invention, the lens main body portion, the flange portion, and the pin contact portion have a circular outline when viewed from the optical axis direction.

  According to still another aspect of the present invention, the recess is formed in an arcuate region including the outer edge of the flange portion. In this case, the area of the recess for enabling the burr observation of the pin contact portion, that is, the pin contact portion trace, can be minimized.

[First Embodiment]
Hereinafter, a first embodiment of an optical element according to the present invention will be described with reference to the drawings. 1A is a plan view illustrating the optical element of the present embodiment, FIG. 1B is a side view of the optical element, and FIG. 1C is a partially enlarged view of the optical element. FIG.

  The optical element 20 is an objective lens incorporated in the optical pickup device, and includes a lens main body 21 having an optical function and an annular flange 22 extending around the lens main body 21. In this optical element 20, the lens body 21 and the flange 22 are integrally formed by resin injection molding. As is clear from the figure, the lens body 21 has a circular outline in plan view, and the flange 22 has an annular outline in plan view.

  In the optical element 20, the lens body 21 causes the light beam, which is emitted from a light source (not shown) and collimated, to enter the optical surface 21 a along the optical axis OA shown in FIG. The light is converged and emitted from the optical surface 21b, and a light spot (not shown) is formed on the upper side of FIG.

  The flange portion 22 is formed in an annular shape along the outer periphery of the lens body portion 21 and supports the lens body portion 21 from the periphery. The outer peripheral side surface 22p of the flange portion 22 has a cylindrical shape with the AB direction as the axial direction. A gate portion GT for introducing resin at the time of molding is formed at one location on the outer peripheral side surface 22p so as to protrude outward. The gate part GT may not remain in the final optical element due to the cut after molding. The lower end surface 22a of the flange portion 22 has an annular contour and is flat as a whole, but the upper end surface 22b of the flange portion 22 is formed with four concave portions 32, so that the flange portion 22 of that portion becomes thin. ing. Pin abutting portions 33 for abutting the protruding pins EP at the time of mold release are provided at the center of each recess 32, that is, at four locations in the direction obtained by dividing the circumference of the flange portion 22 into four equal parts.

  Each pin contact portion 33 is circular in plan view, and a cylindrical burr 41 having an irregular height h extends from the outer peripheral edge upward, that is, along the AB direction. The concave portion 32 has an arcuate shape in plan view, and has a depth d such that the tip end portion 41a of the normal burr 41 does not reach the upper end surface position US1 of the flange portion 22. Here, the lateral width w that is the distance from the step 32 s of the recess 32 to the farthest point on the outer peripheral side surface 22 p is larger than the diameter e of the pin contact portion 33, and the pin contact portion 33 is within the region of the recess 32. Has come to fit. The depth d from the upper end surface position US1 of the flange portion 22 to the lower end surface position LS1 of the recess 32 is larger than the height h of the normal burr 41. On the other hand, if the depth d of the concave portion 32 is made too large, an unfavorable result with respect to the strength of the flange portion 22 and the like is caused. As a result, when the height of the burr 41 becomes extremely large due to variation in molding, there is a possibility that the tip portion 41a may exceed the upper end surface position US1 of the flange portion 22, and thus the burr 41 exceeding the height limit is generated. It is necessary to distinguish the optical element 20 having the burrs 41 from the optical elements 20 having the following burrs 41 as defective or low-grade products. In the case of the present embodiment, when the concave portion 32 is viewed from the side surface direction perpendicular to the optical axis OA of the lens main body portion 21, that is, from the front and back in the CD direction or the EF direction, all protrusions from the bottom surface 32a of the concave portion 32 can be observed. Since it has a shape, the burr 41 can be easily and reliably confirmed from the outside over the entire circumference. That is, it is possible to directly observe the tip portion 41a of the burr 41 that is close to the concave portion 32 side of the upper end surface position US1 from the surroundings without any blind spots, using an optical microscope or an electron microscope. The bottom surface 32a of the recess 32 is preferably formed in a plane parallel to the upper end surface of the flange portion 22 in terms of facilitating observation and confirming more reliably.

  FIG. 2 is a partially enlarged plan view of the optical element 20 and is a diagram for explaining a region where the recess 32 is to be formed. Here, a straight line extending in parallel to the surface of the flange portion 22, that is, the paper surface perpendicular to the optical axis OA is considered. Such a straight line includes a large number of tangent lines that are in contact with the outer periphery of the pin contact portion 33, and among these tangent lines, the line segment SL extends from the center O of the lens body 21 to the center of the pin contact portion 33. The reference tangent line TL0 means an example of a minimum boundary that does not block the field of view from the CD direction, which is one side surface direction of the flange portion 22, and that exposes the entire burr 41. Therefore, when the concave portion 32 is formed in a region equal to or wider than the reference tangential outside region AR0 extending to the pin contact portion 33 side with respect to the reference tangent TL0, the flange portion 22 extends along the tangent line of the outer peripheral side surface 22p. By observing from the viewpoint directions VP1 and VP2, the burr 41 extending above the pin contact portion 33 can be confirmed over the entire circumference including the back portion 41i and the front portion 41o. Therefore, in the present embodiment, the step 32 s that is the inner boundary of the recess 32 is set to an inner position that is parallel to the reference tangent line TL0 and closer to the center O. As a result, the concave portion 32 is formed in a wider area including the reference tangential outer area AR0.

  Hereinafter, modifications of the present embodiment will be described. In FIG. 2, when a tangent line extending in parallel with the plane perpendicular to the optical axis OA and in contact with the outer periphery of the pin contact portion 33 is considered, the tangent line passing outside the outer periphery of the lens body portion 21 is In addition to the reference tangent line TL0, a large number of tangent lines continuously exist from the tangent line L11 rotated most clockwise to the tangent line L12 rotated most counterclockwise. Here, when one of the tangent lines L11 to L12 is used as a reference and the side visual recognition areas VA1, AR0, and VA2 that extend to the pin contact portion 33 side with respect to the specific tangent line are considered, When the concave portion 32 is formed in a region equal to or wider than the visual recognition regions VA1, AR0, VA2, the tangential direction of the outer peripheral side surface 22p of the flange portion 22, that is, the front and back on the tangent lines L11 to L12 By observing from two points, the burr 41 extending above the pin contact portion 33 can be confirmed over the entire circumference. That is, the step 32s of the recess 32 can be formed along the tangents L11 and L12, or can be formed closer to the center O than the tangents L11 and L12. At this time, the step 32s does not need to be a straight line when viewed from the optical axis OA direction, and can be a curved line when viewed from the optical axis OA direction. Further, the step 32s does not need to extend in parallel with the optical axis OA direction, and can be an inclined surface having a constant inclination angle with respect to the optical axis OA as long as it does not exceed the reference tangent TL0.

  FIG. 3 is a conceptual side sectional view for conceptually explaining the structure of a molding die for molding the optical element 20 shown in FIGS. 1 (A) to 1 (C). The molding die 50 includes a fixed die 51 and a movable die 52, and both the die 51 and 52 can be opened and closed with a parting line PL as a boundary. A cavity CV, which is a space between both molds 51, 52, corresponds to the shape of the optical element 20 (see FIG. 1A, etc.) that is a molded product. The fixed mold 51 includes an outer peripheral mold 51a and a core mold 51b. The movable mold 52 also includes an outer peripheral mold 52a and a core mold 52b. The optical transfer surfaces 51t and 52t of both core dies 51b and 52b are portions for forming the optical surfaces 21a and 21b of the lens body 21 of the optical element 20, and the transfer surfaces of both outer peripheral dies 51a and 52a. 51 u and 52 u are portions for forming the lower end surface 22 a and the upper end surface 22 b of the flange portion 22 of the optical element 20. A protrusion 52p for forming the recess 32 of the flange portion 22 is provided on a part of the transfer surface 52u of the outer peripheral mold 52a. The protrusion 52p is formed with a through hole 52h through which the protrusion pin EP is inserted, and the flange portion 22 can be protruded by the protrusion pin EP when the molds 51 and 52 are released after the molds are opened. .

  As is clear from the above description, in the optical element 20 of the above embodiment, the concave portion 32 is located closer to the pin contact portion 33 than the reference tangent line TL0 that contacts the outer periphery of the pin contact portion 33 on the center side of the lens body portion 21. It is formed including. In other words, the recess 32 is formed in a wider area including all the areas closer to the pin contact portion 33 than the reference tangent line TL0, that is, all the side visual recognition areas AR0. Therefore, when the concave portion 32 is observed from the side, that is, from the CD direction, the tip of the burr 41 extending upward from the pin contact portion 33 can be easily confirmed over the entire circumference from the outside. Therefore, it is possible to facilitate the management for preventing the occurrence of burrs exceeding the allowable range.

[Second Embodiment]
The optical element according to the second embodiment of the present invention will be described below. The optical element of the second embodiment is obtained by partially changing the optical element of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

  FIG. 4A is a partial plan view illustrating the optical element of the second embodiment, and FIG. 4B is a partial side view of the optical element of the present embodiment. In this case as well, an arcuate recess 132 is formed in the flange portion 22 provided in the optical element 120, but the bottom surface 132 a has a two-stage depth, and in the peripheral region R 1 close to the pin contact portion 33. It is deep and shallow in the remote region R2 away from the pin contact portion 33. Thereby, it is possible to secure a sufficient margin with respect to the allowable length of the burr 41.

  In the above example, the recess 132 has a two-stage depth. Needless to say, the depth can be three or more, but the bottom surface 132a is inclined with respect to the upper end surface 22b of the flange portion 22. You can also

  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 pin contact portions 33 are provided at four locations. However, for example, the pin contact portions 33 can be provided at 1 to 3 locations and 5 locations or more, and the intervals between the pin contact portions 33 are also equal. Need not be.

The optical element 20, 12 0 of the above embodiment is used as an objective lens for the optical pickup is not limited to the objective lens, in various plastic lens used as the collimator lens, the concave portion 32 as described above, 13 2 can be a provided.

In the above embodiment, is provided with the recesses 32,13 2 and the pin contacting portion 33 on the upper end face 22b side of the flange portion 22, the concave portion on the lower end surface 22a side of the flange portion 22 32,13 2 and pin those A contact portion 33 can also be provided.

  Moreover, the outline of the pin contact portion 33 is not limited to a circle, and can be various shapes such as a rectangle and an ellipse.

(A)-(C) are the top view of the optical element of 1st Embodiment, a side view, and a partial enlarged view. It is a partial expanded plan view of an optical element, and is a figure explaining the area | region which should form a recessed part. It is a conceptual diagram of the side cross section explaining the structure of the metal mold | die for shape | molding an optical element. (A), (B), the Ru partial plan view and a partial side view der illustrating the optical element of the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Optical element 21 ... Lens main-body part 21a, 21b ... Optical surface, 22 ... Flange part, 22a ... Lower end surface, 22b ... Upper end surface, 22p ... Outer peripheral side surface, 32 ... Recessed part, 32a ... Bottom surface, 32r ... Outer edge, 32s ... Step, 33 ... Pin abutting part, 41 ... Burr, 41a ... Tip, 50 ... Molding die, 51 ... Fixed die, 52 ... Moving die, AR0 ... Outside reference tangential line, CV ... Cavity, EP: Extrusion pin, GT: Gate part, TL0, L11, L12 ... Tangent, OA ... Optical axis, TL0 ... Reference tangent, VA1, AR0, VA2 ... Side view area

Claims (8)

An optical element comprising a lens main body and an annular flange extending around the lens main body, and formed by resin injection molding,
The flange portion has a pin contact portion with which the protruding pin is contacted at the time of mold release and a recess around the pin contact portion,
The concave portion is in contact with the outer periphery of the pin contact portion when viewed from the optical axis direction of the optical element, and the predetermined tangent line with reference to a predetermined tangent line passing outside the outer periphery of the lens body portion. is formed over the entire region of the pin abutment portion than,
The said flange part has an upper end surface extended from the inner periphery of the said flange part to the outer periphery of the said flange part in the thick area | region except the said recessed part .   2. The optical element according to claim 1, wherein the predetermined tangent line is orthogonal to a line segment connecting a center of the lens main body portion and a center of the pin contact portion.   When viewed from the optical axis direction of the optical element, the concave portion is perpendicular to a line segment connecting the center of the lens main body portion and the center of the pin contact portion among the tangent lines in contact with the outer periphery of the pin contact portion. 2. The optical element according to claim 1, wherein the optical element is formed in an entire region closer to the pin contact portion than a tangent line.   The concave portion is perpendicular to a line segment connecting the center of the lens main body portion and the center of the pin abutting portion, and more than the straight line that does not intersect the lens main body portion and the pin abutting portion. The optical element according to any one of claims 1 to 3, wherein the optical element is formed over the entire region on the side.   The concave portion has a shape that makes it possible to observe a tip portion of a burr extending upward from the pin contact portion when viewed from a side surface direction perpendicular to the optical axis of the lens main body portion. The optical element according to any one of claims 1 to 4.   The optical element according to claim 1, wherein the pin contact portion is provided at a plurality of locations along the flange portion.   The optical system according to any one of claims 1 to 6, wherein the lens main body portion, the flange portion, and the pin contact portion have a circular outline when viewed from the optical axis direction. element.   The optical element according to claim 7, wherein the concave portion is formed in an arcuate region including an outer edge of the flange portion.

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