JP2004098547A - Mold for insert molding lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately bring an optical axis of a lens into coincidence with a central axis of a lens holder without causing a scratch within an optical effective diameter of the lens when the lens to be inserted is held by the holder and molded. <P>SOLUTION: A mold for insert molding the lens includes two-divisible molds 4, 5 each having a cavity larger than an outer diameter of the lens 3 to be inserted, and lens holders 1, 2 respectively inserted in engaging state into the molds 4, 5 so as to be disposed at a substantially central part of the cavity and having ends of shapes smaller than the outer diameter of the lens for disposing the lens 3 by holding the lens 3 from both the surfaces before a resin is filled. Infinitesimal curved surfaces are formed over the entire peripheral surfaces of the ends of the holders 1, 2 brought into contact with the lens 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a lens insert molding die for integrally molding a lens and a frame (mirror frame) of the lens outer peripheral portion by filling the cavity with a resin in a state where the lens is inserted into the cavity. About.
[0002]
[Prior art]
Japanese Patent Publication No. 50-14126 discloses a conventional lens insert molding die. In this lens insert molding die, the lens holder is inserted into each of the pair of dies in a fitted state so as to be located at substantially the center of each of the two cavities. The center axes of the lens holders coincide with each other with high precision. By holding the lens from both sides with this lens holder, a straight line (optical axis) passing through the center of curvature of both sides of the lens is accurately matched with the central axis. be able to. In this case, the tip of the lens holder is slightly chamfered so as to prevent the lens holder from being scratched when the lens is clamped from both sides.
[0003]
[Problems to be solved by the invention]
With conventional lens insert molding dies, the edge of the lens holder is chamfered in the same way as when there is no chamfer, so the lens holder prevents scratches when the lens is clamped from both sides. Can not. Especially, in the case of coated lenses, when the lens holder holds the lens from both sides, the movement of the lens on the lens holder is not smooth, so the lens holding Requires a large force, and as a result, scratches are likely to occur. Moreover, since the coating treatment has been performed, the scratches are more prominent.
[0004]
On the other hand, there is an avoiding means for preventing the scratch occurrence position from being within the optical effective diameter of the lens, but in this case, the diameter of the front end of the lens holder must be increased, and as a result, the lens However, there is a problem that the outer diameter cannot be increased and the size cannot be reduced.
[0005]
The present invention has been made in consideration of such a conventional problem, and does not cause scratches within the optical effective diameter of the lens and does not hinder compactness. On the other hand, an object of the present invention is to provide a lens insert molding die capable of accurately matching the optical axis of a lens.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a lens insert molding die according to the first aspect of the present invention includes two splittable dies having a cavity larger than the outer diameter of the lens to be inserted, and a mold located substantially at the center of the cavity. A lens holder having a tip smaller than the outer diameter of the lens, which is inserted into each mold in a fitted state so as to sandwich the lens from both sides before filling with the resin and position the lens. A minute curved surface is formed over the entire circumference of the front end of the lens holder in contact.
[0007]
According to the present invention, since the distal end portion of the lens holder has a minute curved surface and thus does not have an edge shape, the lens holder may be scratched when the lens is sandwiched from both sides by the lens holder. Disappears. In addition, the contact between the lens and the minute curved surface is always a line contact with the tip of the lens holder in a circle centered on the optical axis, as in the case of the edge shape. Therefore, the positioning accuracy of the optical axis of the lens with respect to the center axis of the lens holder does not deteriorate. In this case, the radius of curvature of the minute curved surface can be set in a range of 0.01 mm to 0.2 mm, and is particularly preferably set in a range of 0.03 mm to 0.1 mm.
[0008]
According to a second aspect of the present invention, there is provided the lens insert molding die according to the first aspect, wherein the lens holder having the minute curved surface formed at the front end is disposed on the fixed die side. I do.
[0009]
According to the present invention, even if the lens has a shape in which it is difficult to position the lens, the optical axis of the lens can be accurately matched with the center axis of the lens holder without causing any damage to the lens.
[0010]
When positioning the lens by holding the lens from both sides with the lens holder, the positioning accuracy of the lens depends on the lens shape.If the shape is difficult to position theoretically, both lenses that come into contact with the lens If a minute curved surface is provided at the tip of the holder, the positioning accuracy of the lens becomes unstable. Therefore, if attention is paid only to the positioning accuracy of the lens, as disclosed in the related art, it is desirable that the front end portion of the lens holder has an edge shape, but the appearance problem of generation of scratches cannot be avoided.
[0011]
However, the following facts have been found by the study of the present inventors. FIG. 1 shows a state in which a lens 53 is placed on a fixed-side lens holder 51, and the optical axis of the lens 53 is shifted to the right. Here, when the movable-side lens holder 52 is moved closer to the fixed-side lens holder 51 in a state where the center axis of the fixed-side lens holder 51 and the center axis of the movable-side lens holder 52 are substantially aligned, the optical axis of the lens 53 is changed. The tip end 52a of the movable lens holder 52 first contacts the lens 53 on the side where is shifted. When the movable lens holder 52 is further moved closer to the fixed lens holder 51 from this state, the optical axis of the lens 53 moves in a direction in which the center axes of the two lens holders 51 and 52 coincide with each other, and At the time when the lens 53 is completely clamped by the movable lens holder 52, the central axes of the two lens holders 51 and 52 and the optical axis of the lens 53 substantially match.
[0012]
When the lens 53 moves, the largest frictional force is generated at the moment when the lens 53 is about to start moving. When the movement of the lens 53 is started, the lens 53 moves in a direction in which the lens 53 moves away from the lens holders 51 and 52 at the contact portion between the movable lens holder 52 and the lens 53. At the contact portion 53, the lens 53 moves while being pressed against the lens holder 51. Therefore, when the lens 53 is pinched by the lens holders 51 and 52, the most obvious scratch is caused by the vicinity of the surface of the lens 53 in contact with the front end 51a of the fixed lens holder 51 in the direction in which the optical axis of the lens 53 is shifted. It is. From the above examination results, by providing a minute curved surface only at the tip end portion 51a of the fixed-side lens holder 51 where scratches are likely to occur, it is possible to prevent scratches when the lens 53 is sandwiched between the lens holders 51 and 52, and Even in a lens having a shape that is relatively difficult to position, the optical axis of the lens 53 can be accurately matched with the center axis of the lens holders 51 and 52.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
FIG. 2 is a cross-sectional view of the lens insert molding die according to Embodiment 1 of the present invention. As shown in FIG. 2, the fixed mold 4 and the movable mold 5 are in contact with each other on the parting surface 6 in a state where their central axes are substantially coincident. When the fixed mold 4 and the movable mold 5 come into contact with each other, a cavity 7 as a molding space is formed between them. The sprue 10 and the gate 11 for injecting the resin into the cavity 7 are formed on the movable mold 5.
[0014]
The lens holders 1 and 2 are inserted into the fixed mold 4 and the movable mold 5, respectively. The fixed-side lens holder 1 is inserted into the fixed-side mold 4 so as to fit with the inner diameter of the fixed-side mold 4, and the outer diameter of its tip is 10.6 mm. The movable-side lens holder 2 is inserted into the movable-side mold 5 so as to fit with the inner diameter of the movable-side mold 5, and the outer diameter of the tip portion is 12.6 mm. The central axis of the fixed lens holder 1 substantially coincides with the central axis of the fixed mold 4, and the central axis of the movable lens holder 2 substantially coincides with the central axis of the movable mold 5. Thus, the central axes of the fixed-side lens holder 1 and the movable-side lens holder 2 substantially coincide with each other. An urging member 9 made of a spring or the like is disposed between the movable lens holder 2 and the movable mounting plate 8 so that the movable lens holder 2 elastically contacts the lens 3. Has become.
[0015]
The lens 3 is sandwiched from both sides by the fixed lens holder 1 and the movable lens holder 2. The fixed lens surface is a convex surface having a radius of curvature of 25 mm, the effective diameter is 10 mm, and the movable lens surface is 20 mm. Has an effective diameter of 12 mm and a diameter of 13.5 mm. Further, since the Z coefficient of the lens of this embodiment is 0.2 from the values of the two radii of curvature and the two effective diameters, this lens is a lens that can be easily positioned automatically by a bell clamp.
[0016]
As shown in FIG. 3, a small curved surface having a radius of 0.08 mm is provided over the entire circumference at the distal end portion 1a of the fixed lens holder 1 and the distal end portion 2a of the movable lens holder 2. When the movable mold 5 and the movable mold 5 are in close contact with each other, the tip 1a of the fixed lens holder 1 and the lens 3 come into contact with each other at a position of 10.44 mm in diameter, and the tip 2a of the movable lens holder 2 and the lens 3 contact each other. Are in contact at a position of 12.44 mm in diameter.
[0017]
In the case where the lens 3 is sandwiched from both sides by the fixed lens holder 1 and the movable lens holder 2 using the lens insert molding die of this embodiment, the light of the lens 3 placed on the fixed lens holder 1 Even when the axis is deviated from the central axis of the fixed lens holder 1, the optical axis of the lens 3 substantially coincides with the central axis of the fixed lens holder 1 in the process of holding the lens 3 from both sides. In addition, since the distal end portion 1a of the fixed-side lens holder 1 and the distal end portion 2a of the movable-side lens holder 2 are provided with minute curved surfaces over the entire circumference, the lens 3 is scratched in the process of clamping the lens 3 from both sides. Nothing.
[0018]
Therefore, according to this embodiment, not only is the lens 3 not damaged, but also the optical axis of the lens 3 can be accurately aligned with the center axis of the lens holders 1 and 2.
[0019]
(Embodiment 2)
The configuration of the lens insert molding die in this embodiment is substantially the same as the molding die shown in FIG. FIG. 4 shows a state where the fixed lens holder 11 and the movable lens holder 12 in this embodiment hold the lens 3 therebetween.
[0020]
The lens 3 used in this embodiment has a fixed lens surface having a convex surface with a radius of curvature of 80 mm and an effective diameter of 12 mm, and a movable lens surface having a convex surface with a radius of curvature of 200 mm and an effective diameter of 10 mm. Since the Z coefficient of this lens is 0.05 from the values of the two radii of curvature and the two effective diameters, the lens 3 of this embodiment is a lens that is difficult to position by a bell clamp.
[0021]
The fixed-side lens holder 11 has an outer diameter of a tip 11a of 12.4 mm, and the movable-side lens holder 12 has an outer diameter of a tip 12a of 10.4 mm. A small curved surface having a radius of curvature of 0.05 mm is formed over the entire circumference at the distal end portion 11a of the fixed lens holder 11, while the distal end portion 12a of the movable lens holder 12 is not formed as a curved surface but has an edge shape. Has become. Therefore, when the lens 3 is sandwiched between the fixed lens holder 11 and the movable lens holder 12 from both sides, the fixed lens holder 11 and the lens 3 come into contact at a position having a diameter of 12.3 mm, and the movable lens holder 12 and the lens 3 No. 3 comes in contact at a position of 10.4 mm in diameter.
[0022]
When the lens 3 is clamped from both sides by the fixed lens holder 11 and the movable lens holder 12 using the lens insert molding die having this configuration, the optical axis of the lens 3 placed on the fixed lens holder 11 Even when the center axis of the fixed-side lens holder 11 is deviated, the optical axis of the lens 3 substantially coincides with the center axis of the fixed-side lens holder 11 in the process of holding the lens 3 from both sides. Note that the lens 3 is a lens that is difficult to be positioned by a bell clamp, but since a curved surface is not provided at the distal end portion 12a of the movable lens holder 12, the lens 3 is fixed on both sides by the fixed lens holder 11 and the movable lens holder 12. The lens 3 does not slide with respect to the distal end portion 12a of the movable lens holder 12 when the lens holder 12 is pinched from above, and accurate positioning with respect to the lens 3 is possible. Further, since the distal end portion 11a of the fixed-side lens holder 11 is provided with a minute curved surface over the entire circumference, the lens 3 is not scratched in the process of holding the lens 3 from both sides.
[0023]
Therefore, according to this embodiment, even if it is difficult for the lens to be positioned by the bell clamp, the optical axis of the lens can be accurately aligned with the center axis of the lens holder without damaging the lens. Can be done.
[0024]
【The invention's effect】
As described above, according to the lens insert molding die of the first aspect of the present invention, the optical axis of the lens can be accurately aligned with the center axis of the lens holder without damaging the lens. At the same time, since it is not necessary to increase the outer diameter of the lens, there is no hindrance to downsizing.
[0025]
According to the invention of claim 2, in addition to the effect of the invention of claim 1, even if the lens shape is difficult to be positioned by a bell clamp, the optical axis of the lens with respect to the center axis of the lens holder Can be accurately matched.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a mechanism in which a lens is scratched when the lens is sandwiched.
FIG. 2 is a cross-sectional view of a lens insert molding die according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view of the lens holding state according to the first embodiment.
FIG. 4 is a cross-sectional view of a lens holding state according to a second embodiment.
[Explanation of symbols]
1, 11 Fixed lens holder 1a, 11a Fixed lens holder tip 2, 12 Movable lens holder 2a, 12a Movable lens holder tip 3 Lens 4 Fixed mold 5 Movable mold

Claims (2)

Two split molds having a cavity larger than the outer diameter of the lens to be inserted, and two molds inserted into each mold in a fitted state so as to be located substantially at the center of the cavity, and the lens is filled on both sides before resin filling. And a lens holder having a tip with a shape smaller than the lens outer diameter for positioning the lens by sandwiching the lens from the lens holder, and that a minute curved surface is formed over the entire circumference of the tip of the lens holder in contact with the lens. Characteristic mold for lens insert molding. 2. The lens insert molding die according to claim 1, wherein the lens holder having a minute curved surface formed at the tip is disposed on a fixed die side.

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