JP2010197437A - Molded plastic lens and its molding die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding die for molding a convex lens which has a thick central part and a small curvature radius or a concave lens which has a thin central part, without a sink and a seam; and to obtain a molded plastic lens. <P>SOLUTION: The molded plastic lens 40 has: a lens part 43 with a circular front (an effective diameter part 41 and an effective diameter outside part 42); a gate part 44 which is continuously formed at a portion of a periphery of the lens part 43; and blind partial hole parts 45A, 45B, 45C formed at the effective diameter outside part 42 while avoiding a region connecting the gate part 44 and a central part of the effective diameter part 41. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a molded plastic lens and a molding die thereof.

  Molded plastic lenses are generally manufactured by injection molding using a mold (Patent Document 1). The lens generally has a front (planar) circular shape, and its shape accuracy (within an effective diameter) is a life. For this reason, the gate (injection port) which inject | pours molten resin material in a shaping | molding die is arrange | positioned at the periphery of a shaping | molding die (it must arrange | position).

JP 60-132719 A

  In the molding of this molded plastic lens, the injected resin material from the gate flows into the circular mold from the gate and flows to the opposite side of the gate. At this time, depending on the shape of the lens and the fluidity of the resin material, it has been pointed out that at the center (within the effective diameter), joints and sink marks of the resin material may occur and the necessary optical performance may not be exhibited. Yes. In particular, a convex lens with a thick center and a tight curvature (small radius of curvature) is prone to sink because the inflowing resin material is difficult to flow into the mold center in a short time. Conversely, a concave lens with a thin center is Since the resin material does not easily pass through the center portion, it flows in an arc shape from the gate to both sides of the center portion, and a seam is likely to occur at the junction (opposite the gate).

  The present invention provides a molded plastic lens and a molding die thereof capable of molding a convex lens having a thick central portion and a small radius of curvature or a concave lens having a thin central portion without sink or seam, based on the above awareness of the molded plastic lens. Objective.

  The molded plastic lens (and mold) of the present invention includes a front circular lens part (lens part molding part) and a gate part (gate) formed continuously from a part of the periphery of the lens part (lens part molding part). Formed on the outer circumference of the effective diameter of the lens part (lens part molding part), avoiding the area connecting the gate part (gate part molding part) and the central part of the lens part (lens part molding part). And having a bottomed partial hole portion (bottomed partial hole portion forming projection).

  The bottomed partial hole portion (bottomed partial hole portion forming projection) is preferably formed, for example, in a front arc shape around the center of the optical axis, and it is practical to form a plurality at intervals in the circumferential direction. . More specifically, the bottomed partial hole portion (bottomed partial hole portion forming projection) is formed on both sides of the region connecting the gate portion (gate portion forming portion) and the center portion of the lens portion (lens portion forming portion) and the lens portion. It is preferable to form each on the opposite side of the gate part (gate part molding part) across the (lens part molding part).

  The lens unit may be a convex lens or a concave lens. In the case of the convex lens, a particularly good result is obtained when there is an effective diameter outer portion between the convex lens and the gate portion, and the thickness of the center portion of the lens portion is 1.3 times or more of the thickness of the effective diameter outer portion. It is done.

  In the concave lens mode, good results can be obtained when an effective diameter outer portion is provided between the concave lens and the gate portion, and the thickness of the center portion of the lens portion is 45% or less of the thickness of the effective diameter outer portion. Alternatively, good results can be obtained when the depth of the central portion of the lens portion is 35% or more of the thickness of the outer portion of the effective diameter.

  Usually, at least a part of the gate portion of the lens is removed after the molding is completed.

  In the aspect of the molding die including a pair of split molds for injection molding a plastic lens having a front circular lens section, the present invention includes a front circular lens section molding section formed on each of the pair of split molds, An area connecting the gate part molding part and the central part of the lens part molding part to at least one of the pair of split dies, and a gate part molding part formed continuously to the peripheral part of the lens part molding part in the split mold It is characterized by having a bottomed partial hole portion forming projection formed on the outer periphery of the effective diameter of the lens portion forming portion.

  According to the molded plastic lens of the present invention, since the bottomed partial hole portion formed on the outer periphery of the effective diameter of the lens portion is avoided so as to avoid the region connecting the gate portion and the central portion of the lens portion, sink marks or seams are formed in the lens portion. Can be made difficult to occur. Even if sink marks or seams occur, they do not reach the center of the lens part (within the effective diameter), and the optical performance does not deteriorate.

  According to the molded plastic lens mold of the present invention, the effective diameter of the lens part molding part is avoided by avoiding a region connecting the gate part molding part and the center part of the lens part molding part to at least one of the pair of split molds. Since it has a bottomed partial hole molding protrusion formed on the outer periphery, when molding a plastic lens by injection molding using this mold, the bottom of the resin part center of the resin material (within the effective diameter) ) Can be improved. As a result, it is possible to make it difficult for sink marks and seams to occur in the lens part of the molded plastic lens, and even if sink marks or seams occur, it does not reach the center part of the lens part (within the effective diameter) and the optical performance deteriorates Never do.

It is sectional drawing which follows the II line | wire of FIG. 2 which shows the shaping | molding die of the shaping | molding plastic lens which concerns on Embodiment 1 of this invention. It is sectional drawing which follows the II-II line of FIG. It is sectional drawing which follows the III-III line of FIG. 4 which shows the shaping | molding die of the shaping | molding plastic lens which concerns on Embodiment 2 of this invention. It is sectional drawing which follows the IV-IV line of FIG. (A) is a front view of the shaping | molding plastic lens shape | molded with the shaping | molding die of FIG.1 and FIG.2, (B) is sectional drawing which follows the VV line of (A). (A) and (C) are a front view and a rear view of a molded plastic lens molded by the mold shown in FIGS. 3 and 4, and (B) is a sectional view taken along line VI-VI in (A) and (C). It is.

(Embodiment 1)
1 and 2 are views showing a molded plastic lens mold (hereinafter, simply referred to as “mold”) 10 according to Embodiment 1 of the present invention. This embodiment illustrates a mold 10 for molding a plano-convex lens. The mold 10 includes a pair of split molds 20 and 30 divided by a parting line PL, and a cavity C for injecting a molten resin material is formed between the pair of split molds 20 and 30.

  The split mold 20 includes an effective diameter portion forming concave portion 21 and an effective diameter outer portion forming portion 22 located on the outer periphery of the effective diameter portion forming concave portion 21 in order from the center, and the effective diameter portion forming concave portion 21 and the effective diameter. The outer side molding part 22 forms a front circular lens part molding part 23. In this embodiment, the effective diameter outer portion molding portion 22 constitutes an annular flat portion. A gate part molding part (resin material injection port) 24 is continuously formed on a part of the periphery of the lens part molding part 23.

  The split mold 20 avoids a region connecting the gate portion molding portion 24 and the center portion of the lens portion molding portion 23 (effective diameter portion molding concave portion 21), and has a bottomed partial hole portion formed in the effective diameter outer portion molding portion 22. It has molding protrusions 25A, 25B, and 25C. The bottomed partial hole portion forming projections 25A, 25B, 25C have a front arc shape, and are formed at three locations at intervals in the circumferential direction of the lens portion forming portion 23 (effective diameter outer portion forming portion 22). Yes. More specifically, on both sides of the region connecting the gate portion molding portion 24 and the center portion of the lens portion molding portion 23 (avoid the region connecting the gate portion molding portion 24 and the center portion of the lens portion molding portion 23). Bottomed partial hole molding projections 25A and 25B are formed, and a bottomed partial hole molding projection 25C is formed on the opposite side of the gate molding portion 24 with the center portion of the lens portion molding portion 23 interposed therebetween (FIG. 2). ). These bottomed partial hole portion forming protrusions 25A, 25B, and 25C are set to have a shape that does not adversely affect the light flux that passes through the lens formed by the effective diameter portion forming concave portion 21.

  The split mold 30 includes an effective diameter portion forming portion 31 and an effective diameter outer portion forming portion 32 continuous in the circumferential direction of the effective diameter portion forming portion 31 in order from the center portion. The radially outer portion molding portion 32 forms a front circular lens portion molding portion 33. In this embodiment, the entire lens molding portion 33 is a flat surface. A gate portion molding portion (resin material injection port) 34 is continuously formed on a part of the periphery of the lens portion molding portion 33.

  When a plastic lens is molded by injection molding using the mold 10 described above, a molten resin material (for example, an optical resin material such as an acrylic resin or a non-acrylic resin) is placed between a pair of split molds 20 and 30. It inject | emits through the gate part shaping | molding parts 24 and 34 in the formed cavity C. FIG.

  The injected resin material passes between the bottomed partial hole portion molding protrusions 25A and 25B and is led to the center of the lens portion molding portions 23 and 33 (effective diameter portion molding concave portion 21 and effective diameter portion molding portion 31). Further, it flows between the bottomed partial hole forming projections 25A and 25C and between the projections 25B and 25C to the peripheral portion. Further, (or) the resin material that wraps around the bottomed partial hole molding projection 25A (25B) passes between the bottomed partial hole molding projections 25A and 25C and between the projections 25B and 25C to form the lens portion. It is led to the center of the molding parts 23 and 33 (effective diameter part molding part 21, effective diameter part molding part 31). In any case, compared with the case where the protrusions 25A, 25B, and 25C are not present, the injection resin material quickly flows into the effective diameter portion forming recess 21 and the effective diameter portion forming portion 31.

  When the filling of the resin material into the cavity C is completed, the mold 10 is cooled for a certain time to solidify the resin material. When the resin material is solidified, the split molds 20 and 30 are divided along the parting line PL, and the molded plastic lens is taken out.

  FIG. 5 is a diagram showing a convex plastic lens 40 molded by the mold 10, and the convex plastic lens 40 has a shape corresponding to the shape of the mold 10 (split molds 20, 30).

  The convex plastic lens 40 has an effective diameter portion 41 and an effective diameter outer portion 42 located on the outer periphery of the effective diameter portion 41 in order from the center, and the effective diameter portion 41 and the effective diameter outer portion 42 are front circular. The lens part 43 is made. A gate portion 44 is formed on a part of the periphery of the lens portion 43. At least a part of the gate portion 44 is removed (cut out) when mounted on a device such as a camera module.

  The convex plastic lens 40 avoids a region connecting the gate portion 44 and the central portion of the lens portion 43 (effective diameter portion 41), and has a bottomed partial hole formed on the outer periphery (effective diameter outer portion 42) of the effective diameter portion 41. It has parts 45A, 45B, 45C. The bottomed partial hole portions 45 </ b> A to 45 </ b> C have a front arc shape, and are formed at three locations with a gap in the circumferential direction of the lens portion 43. More specifically, bottomed partial hole portions 45A and 45B are formed on both sides of a region connecting the gate portion 44 and the central portion of the lens portion 43, and the opposite side of the gate portion 44 across the central portion of the lens portion 43. A bottomed partial hole 45C is formed in the bottom (FIG. 5A). As described above, these bottomed partial hole portions 45A, 45B, and 45C have shapes that do not adversely affect the light flux that passes through the effective diameter portion 41.

  According to the convex plastic lens molding die 10 described above, the fluidity of the resin material to the effective diameter portion molding recess 21 can be enhanced by the bottomed partial hole molding projections 25A, 25B, and 25C. That is, the resin material easily flows into the effective diameter portion molding portion 21 at the center of the lens portion molding portion 23, and the resin material is sequentially filled from the center portion. As a result, sink marks and seams are unlikely to occur in the lens portion 43 of the molded plastic lens 40, and even if sink marks or seams occur, it does not reach the center portion (effective diameter portion 41) of the lens portion 43, and optical performance. Will not drop.

In particular, the thickness D of a convex lens having a thick central portion and a small radius of curvature, for example, the central portion (effective diameter portion 41) of the lens portion 43 is 2 mm or more and 1.3 times or more the thickness d of the effective diameter outer portion 42. The present invention is effective when a certain plastic lens 40 is molded. When the three types of plastic lenses shown in Table 1 were manufactured, it was confirmed that the fluidity of the resin material and thus the plastic lens moldability (particularly, the shape accuracy of the effective diameter portion) was improved.

  In the present embodiment, the molding die 10 for molding the plano-convex lens has been described as an example. However, the shape of the lens portion molding portions 23 and 33 is changed as appropriate to mold a biconvex lens or a meniscus lens. It can also be a mold.

(Embodiment 2)
3 and 4 are views showing a molding die 50 of a molded plastic lens according to Embodiment 2 of the present invention. The mold 50 of the present embodiment is a mold for molding a biconcave lens. The mold 50 includes a pair of split molds 60 and 70 divided by a parting line PL, and a cavity C for injecting a molten resin material is formed between the pair of split molds 60 and 70.

  The split mold 60 has an effective diameter portion forming convex portion 61 and an effective diameter outer portion forming portion 62 located on the outer periphery of the effective diameter portion forming convex portion 61 in order from the center portion. The effective diameter outer portion molding portion 62 forms a front circular lens portion molding portion 63. A gate portion molding portion (resin material injection port) 64 is continuously formed on a part of the periphery of the lens portion molding portion 63.

  The split mold 70 includes an effective diameter portion forming convex portion 71 and an effective diameter outer portion forming portion 72 continuous in the circumferential direction of the effective diameter portion forming convex portion 71 in order from the center portion. 71 and the effective diameter outer portion molding portion 72 form a front circular lens portion molding portion 73. A gate portion molding portion (resin material injection port) 74 is continuously formed on a part of the periphery of the lens portion molding portion 73.

  The split mold 70 has a bottomed partial hole formed in the effective diameter outer portion molding portion 72 while avoiding a region connecting the gate portion molding portion 74 and the central portion (effective diameter portion molding convex portion 71) of the lens portion molding portion 73. Part molding protrusions 75A, 75B, and 75C are provided. The bottomed partial hole portion molding protrusions 75A, 75B, and 75C have a front arc shape, and are formed at three locations at intervals in the circumferential direction of the lens portion molding portion 73. More specifically, bottomed partial hole molding protrusions 75A and 75B are formed on both sides of a region connecting the gate portion molding portion 74 and the central portion of the lens portion molding portion 73, and the central portion of the lens portion molding portion 73 is formed. A bottomed partial hole molding protrusion 75C is formed on the opposite side of the gate molding part 74 (FIG. 4). These bottomed partial hole forming projections 75A, 75B, and 75C are set in a shape that does not adversely affect the light flux that passes through the lens formed by the effective diameter portion forming convex portion 71.

  When a plastic lens is molded by injection molding using the molding die 50 described above, the molten resin material is injected through the gate portion molding portions 64 and 74 into the cavity C formed between the pair of split dies 60 and 70. .

  The injected resin material passes between the bottomed partial hole portion molding protrusions 75A and 75B and is led to the center (effective diameter portion molding convex portions 61 and 71) of the lens portion molding portions 63 and 73. It flows between the projections 75A and 75C and between the projections 75B and 75C and flows to the peripheral edge. Further, (or) the resin material that has sunk outside the bottomed partial hole molding projection 75A (75B) passes between the bottomed partial hole molding projections 75A and 75C and between the projections 75B and 75C to form the lens part. Guided to the center of the parts 63 and 73 (effective diameter part forming parts 61 and 71). In any case, compared to the case where the protrusions 75A, 75B, and 75C are not present, the injection resin material flows to the effective diameter portion molding portions 61 and 71 more quickly.

  When the filling of the resin material into the cavity C is completed, the mold 50 is cooled for a certain time to solidify the resin material. When the resin material is solidified, the split molds 60 and 70 are divided along the parting line PL, and the molded plastic lens is taken out.

  FIG. 6 is a diagram showing a concave plastic lens 80 molded by the molding die 50. The concave plastic lens 80 has a shape corresponding to the shape of the molding die 50 (split molds 60, 70).

  The concave plastic lens 80 has an effective diameter portion 81 and an effective diameter outer portion 82 that is continuous in the circumferential direction of the effective diameter portion 81 in order from the center, and the effective diameter portion 81 and the effective diameter outer portion 82 are located on the front surface. A circular lens portion 83 is formed. A gate portion 84 is formed on a part of the periphery of the lens portion 83. At least a part of the gate portion 84 is removed (cut out) when mounted on a device such as a camera module.

  The concave plastic lens 80 has bottomed partial holes 85A, 85B, and 85C formed in the effective diameter outer portion 82, avoiding the region connecting the gate portion 84 and the central portion of the lens portion 83 (effective diameter portion 81). is doing. The bottomed partial hole portions 85 </ b> A to 85 </ b> C have a front arc shape, and are formed at three locations at intervals in the circumferential direction of the lens portion 83. More specifically, bottomed partial hole portions 85A and 85B are formed on both sides of a region connecting the gate portion 84 and the central portion of the lens portion 83, and the opposite side of the gate portion 84 across the central portion of the lens portion 83. A bottomed partial hole 85C is formed in the bottom (FIG. 6C). As described above, these bottomed partial hole portions 85A, 85B, and 85C have shapes that do not adversely affect the light flux that passes through the effective diameter portion 81.

  According to the concave plastic lens mold 50 described above, the fluidity of the resin material to the effective diameter portion molding convex portions 61 and 71 can be enhanced by the bottomed partial hole portion molding projections 85A, 85B, and 85C. That is, since the resin material is easy to flow to the center part (effective diameter part molding convex parts 61, 71) of the lens part molding parts 63, 73, the resin material from the gate part molding parts 64, 74 is the lens part molding part. It is possible to prevent a seam from occurring at the junction (opposite the gate) by flowing in an arc shape on both sides of 63 and 73.

In particular, a concave lens having a thin central portion, for example, a plastic lens in which the thickness D ′ of the central portion (effective diameter portion 81) of the lens portion 83 is 45% or less of the thickness d ′ of the effective diameter outer portion, or the central portion of the lens portion 83 When molding a plastic lens in which one of the depths D1 ′ and D2 ′ of the (effective diameter portion 81) (D2 ′ in the example of FIG. 6) is 35% or more of the thickness d ′ of the outside portion of the effective diameter The present invention is effective. When the five types of plastic lenses shown in Table 2 were manufactured, it was confirmed that the flowability of the resin material and thus the plastic lens moldability (particularly the shape accuracy of the effective diameter portion) was improved.

  In the present embodiment, the molding die 50 for molding the biconcave lens has been described as an example. However, the shape of the lens portion molding portions 63 and 73 is appropriately changed to mold a planoconcave lens or a meniscus lens. It can also be a mold.

  In each of the above embodiments, the bottomed partial hole is provided in one of the pair of split molds, but the bottomed partial hole forming projection may be provided in both of the pair of split molds. Further, the number, shape, position, and the like of the bottomed partial hole can be variously changed within the scope of the technical idea of the present invention.

10 50 Molded plastic lens mold 20 30 60 70 A pair of split molds 21 Effective diameter part molding recess 22 32 62 72 Effective diameter outer part molding part 23 33 63 73 Front circular lens part molding part 24 34 64 74 Gate part molding (Resin material inlet)
25A, 25B, 25C 75A, 75B, 75C Bottomed partial hole forming projection 31 Effective diameter part forming part 61 71 Effective diameter part forming convex part 40 Convex plastic lens 80 Concave plastic lens 41 81 Effective diameter part 42 82 Effective diameter outside part 43 83 Front circular lens portion 44 84 Gate portion 45A, 45B, 45C 85A, 85B, 85C Bottomed partial hole portion

Claims (12)

A front circular lens part;
A gate portion formed continuously to a part of the periphery of the lens portion;
Avoiding the region connecting the gate part and the center part of the lens part, the bottomed partial hole part formed on the outer periphery of the effective diameter of the lens part,
A molded plastic lens characterized by comprising: The molded plastic lens according to claim 1, wherein
The bottomed partial hole is a molded plastic lens having a front arc shape. The molded plastic lens according to claim 1 or 2,
A molded plastic lens in which a plurality of the bottomed partial hole portions are formed at intervals in the circumferential direction. The molded plastic lens according to any one of claims 1 to 3,
The bottomed partial hole portion is a molded plastic lens formed on both sides of a region connecting the gate portion and the central portion of the lens portion and on the opposite side of the gate portion with the lens portion interposed therebetween. The molded plastic lens according to any one of claims 1 to 4,
A molded plastic lens in which the lens portion is a convex lens, has an effective diameter outer portion between the convex lens and the gate portion, and the thickness of the central portion of the lens portion is 1.3 times or more the thickness of the effective diameter outer portion. The molded plastic lens according to any one of claims 1 to 4,
A molded plastic lens in which the lens part is a concave lens and has an effective diameter outer part between the concave lens and the gate part, and the thickness of the center part of the lens part is 45% or less of the thickness of the effective diameter outer part. The molded plastic lens according to claim 6, wherein
A molded plastic lens in which the depth of the central portion of the lens is 35% or more of the thickness of the outer portion of the effective diameter. The molded plastic lens according to any one of claims 1 to 7,
Molded plastic lens with the gate part removed. A mold including a pair of split molds for injection molding a plastic lens having a front circular lens portion,
A front circular lens part molding part formed on each of the pair of split molds;
A gate part molding part formed on the pair of split molds continuously with a part of the periphery of the lens part molding part; and
Forming a bottomed partial hole formed on the outer periphery of the effective diameter of the lens part molding part, avoiding a region connecting the gate molding part and the center part of the lens part molding part to at least one of the pair of split molds With protrusions,
Molded plastic lens mold characterized by that. The molded plastic lens mold according to claim 9, wherein
The bottomed partial hole molding projection is a molded plastic lens mold having a front arc shape. In the molding plastic lens mold according to claim 9 or 10,
A molding die for a molded plastic lens in which a plurality of the bottomed partial hole molding projections are formed at intervals in the circumferential direction. In the shaping | molding die of the shaping | molding plastic lens of any one of Claim 9 thru | or 11,
The bottomed partial hole molding protrusions are formed on both sides of the region connecting the gate molding portion and the lens molding center and on the opposite side of the gate molding portion with the lens molding portion interposed therebetween. Lens mold.

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