JPH09220770A - Plastic member or plastic lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize highly accurate production not extending a production time by uniformizing a longitudinal cross-sectional area to reduce the irregularity of pressure or temp. at a time of molding. SOLUTION: The area of the effective longitudinal cross section P1 traversing the effective range 2a of a long lens part 2 is changed in a longitudinal direction while, so that the area of an expanded longitudinal cross section wherein the effective longitudinal cross section P1 of the effective range 2a and the auxiliary longitudinal cross section P2 of the auxiliary range 2b adjacent thereto and extended therefrom becomes almost uniform, the area of the auxiliary longitudinal cross section P2 of the auxiliary range is changed in a longitudinal direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic member such as a plastic lens, and more particularly to a plastic member which can be manufactured with high precision in a range required for precision by injection molding.

[0002]

2. Description of the Related Art In recent years, even optical parts such as lenses requiring high precision are often manufactured from resin (plastic), and injection molding such as injection compression molding is often used as a manufacturing method. There is. As a plastic part of this type, for example, when manufacturing a plastic lens with a special shape, in order to manufacture it with high precision by injection molding, the resin internal pressure and temperature in the mold during the filling / cooling process should be uniform. There is a need to.

Such a plastic lens is, for example, a plastic lens used in an optical writing unit of a laser printer, for example, Japanese Patent Laid-Open No. 5-188.
No. 285 gazette. This plastic lens is formed to be long in order to correct the focal length of the scanning laser beam, and changes the cross-sectional area of the range through which the laser light is transmitted in the longitudinal direction, so the ratio of the longitudinal cross-sectional area changes greatly in the longitudinal direction. The side plate is integrally formed so as not to do so.

[0004]

However, in such a conventional plastic member, particularly in the long plastic lens 1 as shown in FIGS. 7 and 8, the lens portion 2 and the box-shaped rib ( Even if the side plate 3 is integrally formed, since the lens portion 2 is formed on different lens surfaces such as the curved surface r1 on one side and the curved surface r2 on the back side, the resin amount in the longitudinal direction at the time of molding is Depending on the position, for example, the thickness of the lens unit 2 (a <b
Only the change in <c) is different.

This cannot be solved even if the rib 3 is integrally molded, and it is more effective than the case without the rib 3, but the resin internal pressure and the cooling rate at the time of molding cannot be made sufficiently uniform. In addition, uneven transfer of the curved surfaces r1 and r2 or sink marks may occur at a thick portion. This problem may be improved to some extent by increasing the holding time of cooling, but it is not sufficient, and there is a problem that the molding time becomes long and the cost increases. The rib 3 has a box shape in order to reinforce the lens portion 2 and improve positioning accuracy.

Therefore, in the present invention, by making the vertical cross-sectional area uniform, it is possible to reduce the variation in pressure and temperature when manufacturing by injection molding and to realize highly accurate manufacturing without increasing the manufacturing time. The purpose is to do. Further, it is intended to improve the reliability by reducing the influence of temperature and the like even after manufacturing.

[0007]

In order to achieve the above object, the present invention provides a plastic member in which an area of a required longitudinal section for longitudinally cutting a range required for accuracy changes depending on the longitudinal position. The area of the extended portion of the enlarged vertical section is changed so that the area of the enlarged vertical section including the required vertical section obtained by extending the required vertical section is substantially uniform. is there.

According to a second aspect of the present invention, in addition to the structure of the first aspect of the invention, the area of an effective vertical section in which the lens portion is formed to be long and which cuts the effective range of the lens portion changes in the longitudinal direction. A plastic lens, wherein the area of the extended portion of the enlarged vertical section is changed in the longitudinal direction so that the area of the enlarged vertical section including the effective vertical section is substantially uniform. It is characterized by.

According to the first and second aspects of the present invention, the longitudinal sectional area is made uniform, and for example, in the case of a long plastic lens, the longitudinal sectional area is made uniform at each position in the longitudinal direction. Therefore, when it is manufactured by injection molding, the amount of resin in the longitudinal direction is made uniform. According to a third aspect of the invention, in addition to the configuration of the second aspect of the invention, the area of the enlarged vertical section is formed to be a substantially average value when the area of the extended portion of the enlarged vertical section is not changed. It is characterized by that.

According to the third aspect of the invention, the difference in the area of the extended portion is reduced. Therefore, the difference in shape of the portion outside the range is reduced. The invention according to claim 4 is
In addition to the configuration of the invention described in claim 2 or 3, the extended portion of the enlarged vertical section is formed so as to be symmetric with respect to a plane passing through the center of the effective range in the thickness direction. Is.

According to the fourth aspect of the invention, the shape of the extended portion is made symmetrical with respect to the center plane. Therefore, in the case of injection molding, a temperature difference due to a difference in resin amount between a pair of molds (for example, a fixed mold and a movable mold) that define a cavity is reduced. The invention according to claim 5 is the invention according to claim 2
In addition to the configuration of the invention described in any one of 4 above, a taper shape that faces outward is provided between the extended portion of the enlarged vertical section and the effective range.

According to the fifth aspect of the invention, a taper surface is formed between the extended portion and the effective range. Therefore, in the case of injection molding, the molding surface of the mold faces the tapered surface. The invention according to claim 6 is characterized in that, in addition to the configuration of the invention according to any one of claims 2 to 5, the extended portion of the enlarged vertical cross section and the effective range are connected by an arc shape. To do.

According to the sixth aspect of the present invention, an arc is formed between the extended portion and the effective range. Therefore, in the case of injection molding, the resin flows along the arc portion.
Here, the range required for accuracy includes the effective range of the lens part of the plastic lens, the reflection part of the mirror, etc., but is not limited to this and is applied to members other than the optical system where accuracy is required. be able to.

Further, the lens may be one in which one lens portion is formed in an elongated shape, or a plurality of lenses arranged in parallel in an array, and has a non-circular irregularly shaped wall thickness difference, for example, fθ. You may apply to a lens etc.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 to 4 are views showing a first embodiment of a plastic lens according to the present invention, and the present embodiment claims
4 corresponds to the invention described in. 1 and 2, reference numeral 10 denotes a plastic lens (plastic member) formed by injection molding, and the plastic lens 10 is a box-shaped rib 3 including a side plate 3a and an end plate 3b on the outer circumference of a long lens portion 2. Are integrally molded, and the rib 3 improves the strength of the lens portion 2 and also improves the positioning accuracy and workability during mounting.

The lens portion 2 has toroidal curved surfaces r1 and r2 formed as two lens surfaces, and the lens portion 2 has curvature radii y1 and y2 in the longitudinal direction of the curved surfaces r1 and r2.
Since (y1> y2) is different, the thickness increases from the central portion (position A) to the end portion (position C), and as shown in FIG.
Then, thickness (distance between vertices on center line C1 of effective range 2a)
At the position a and the position C, the thickness is cmm, and at the position B, the intermediate thickness is bmm. Further, the lens portion 2 has an effective range 2a (width emm) as an optical element inside the rib 3 from the side plate 3a by dmm. That is, in the lens portion 2, the area of the effective vertical section (required vertical section) P1 at each of the positions A to C that vertically crosses the effective range 2a changes in the longitudinal direction.

The lens portion 2 changes according to the toroidal curved surfaces r1 and r2 having an effective vertical section P1 designed,
Between the side plate 3a of the rib 3 and the effective range 2a, curved surfaces r1, r
A curved auxiliary area 2b (width dmm) different from 2 is formed. The auxiliary range 2b has a shape (area of the auxiliary vertical section P2) such that the area of the enlarged vertical section P3, which is the sum of the area of the auxiliary vertical section P2 and the area of the effective vertical section P1, is uniform in the longitudinal direction. The position is changed in the longitudinal direction, and its position is based on the area of the enlarged vertical section P3 at the position B (substantially the average of the area of the enlarged vertical section P3 when the auxiliary vertical section P2 is an extension of the effective vertical section P1). Figure 3 on the center side from B
The protrusion shape (height f, thickness g) shown in FIG.
On the end side from the position B, the groove shape (depth h, thickness j) shown in FIG. 3B is formed. Also, the auxiliary range 2b
Are formed to have a symmetrical shape (longitudinal cross-sectional area) with respect to the center plane C2 of the distance between the vertices.

For example, when the above shape is applied to an example of the plastic lens 10, the dimensions of positions A to C (unit: m
m) is summarized as follows. Position A Position B Position C Effective range 2a thickness 2 (a) 3 (b) 4 (c) Height of protrusion / depth of groove 1.5 (f) 0 (-) 1.5 (h) Auxiliary Thickness of range 2b 5 (g) 3 (b) 1 (j) Area of effective vertical section P1 16 24 32 Area of enlarged vertical section P3 36 36 36 Next, the production of the plastic lens 10 by injection molding is shown in FIG. It will be described together with the operation.

First, a mold 4 comprising an upper mold (movable side) 4a and a lower mold (fixed side) 4b shown in FIG. 4 is clamped to define a cavity 5, and then a molten resin is filled in the cavity 5. Injection fill. At this time, the auxiliary range 2 of the lens unit 2
In b, the area of the auxiliary vertical section P2 is changed in the longitudinal direction to make the area of the enlarged vertical section P3 that is the same as the area of the effective vertical section P1 uniform, so that the molten resin in the cavity 5 has a resin amount in the longitudinal direction. Be filled uniformly. In addition, the auxiliary range 2b is formed such that the center side is a projection shape and the end side is a groove shape with the position B as a boundary, and these projection shapes and groove shapes are symmetrical with respect to the center plane C2 of the effective vertical section P2. Since the auxiliary vertical cross section P2 is formed in the longitudinal direction, the difference in area in the longitudinal direction is reduced, and the mirror surface piece 6a, the cross sectional area adjusting plate 7a and the mirror surface piece 6b are formed.
Also, the amount of resin in contact with the sectional area adjusting plate 7b is made uniform.

Next, by generating an internal resin pressure in the molten resin injected and filled in the cavity 5, the mirror surface piece 6
a and 6b, which are opposite mirror surfaces, are transferred to form curved surfaces r1 and r2 of the effective range 2a of the lens portion 2, and the cross-sectional area adjusting plate 7a,
An auxiliary area 2b is formed by the opposing molding surfaces of 7b.
At this time, since the molten resin in the cavity 5 is uniformly filled with the resin amount in the longitudinal direction, it is possible to evenly generate the resin internal pressure and transfer the mirror surfaces of the mirror surface pieces 6a and 6b with high accuracy.

Next, after cooling the resin in the cavity 5 to at least the heat distortion temperature or lower, the mold is opened and the molded product (plastic lens 10) is taken out. At this time, the amount of resin in the cavity 5 is made uniform in the longitudinal direction, the area difference in the longitudinal direction of the auxiliary vertical section P2 is made small, and the mirror surface pieces 6a, 6b and the cross-sectional area adjusting plates 7a, 7b are not provided. Since the amount of resin in contact with each other is also equalized, it is possible to reduce the deviation of the resin temperature depending on the position and suppress the generation of internal distortion, and the timing of cooling and solidification is shifted depending on the position, and the amount of volume shrinkage is uneven. It doesn't become Therefore, it is possible to manufacture the plastic lens 10 on which the mirror surface is transferred with high accuracy without causing a sink mark.

Here, the plastic lens 10 can also be manufactured by an injection compression molding method in which the molten resin is injected and filled in the cavity 5 and then compressed. In this case, since the mirror surface piece 6b of the lower die 4b and the cross-sectional area adjusting plate 7b can be integrally moved in the vertical direction by the compressor 8, the mirror surface piece 6b and the cross-sectional area adjusting plate 7b are lowered. After injection-filling the molten resin with, the components are raised and cooled. In this injection compression molding method, it is possible to more accurately transfer the mirror surfaces of the mirror surface pieces 6a and 6b to the effective range 2a of the lens portion 2 by compensating for the volume shrinkage of the resin during cooling.
It is possible to more reliably prevent the occurrence of sink marks. In addition,
The mirror surface piece 6b and the cross-sectional area adjusting plate 7b may be separate members or may be a single member.

As described above, in this embodiment, the auxiliary range 2 other than the effective range 2a of the lens section 2 which requires accuracy is used.
By changing the sectional area of the auxiliary vertical section P2 with b, the effective vertical section P
Since the area of the enlarged vertical section P3 including 1 is made uniform in the longitudinal direction, even if the thickness of the effective range 2a (the area of the effective vertical section P1) changes in the longitudinal direction, the amount of resin to be produced by injection molding can be increased. It can be made uniform in the longitudinal direction. Therefore, the resin internal pressure for transferring the curved surfaces r1 and r2 can be uniformly generated, and the variation in the resin temperature can be reduced and the resin can be cooled.

Further, the area of the auxiliary vertical section P2 increases or decreases in the shape of a protrusion and the shape of a groove on the central portion side and the end portion side with reference to the position B and is symmetrical with respect to the central plane C2. The deviation of the resin temperature on the end side can be reduced to prevent the occurrence of sink marks. As a result, the plastic lens 10 can uniformly cool the temperature without increasing the cooling time and the like, and the curved surfaces r1 and r2 can be transferred with high accuracy.

Further, since the effective range 2a and the auxiliary range 2b of the plastic lens 10 are made uniform in the area of the enlarged vertical section P3 in the longitudinal direction, the mounting position is, for example, an environment where the temperature becomes high. However, the influence of the external load can be made uniform in the longitudinal direction, and the deformation due to the environmental temperature can be suppressed. In the present embodiment, a long plastic lens is described as the plastic member, but the plastic member is not limited to a long one in terms of shape and shape. For example, it can also be applied to those that are formed in an irregular shape and whose thickness changes in the rotational direction.

Next, FIG. 5 is a view showing a second embodiment of the plastic lens according to the present invention, and this embodiment corresponds to the invention described in claim 5. Since the present embodiment is formed in substantially the same manner as the above-described embodiment, the same reference numerals are given to the same configurations and only the characteristic portions will be described. In the figure, T is a taper surface, and the taper surface T is continuous with the effective range 2a, and the auxiliary range 2b formed in a projection shape or a groove shape.
And the tapered surface T is formed so as to face outward, that is, in the mold opening direction of the mold 4.

In the present embodiment, in addition to the effects of the first embodiment described above, the tapered surface T facing outward is formed on the side surface (boundary) of the auxiliary range 2b continuous with the effective range 2a. The molding surface of the mold 4 faces the tapered surface T,
It can be released without resistance when opening the mold. Further, at the time of use, the tapered surface T can prevent irregular reflection in the auxiliary range 2b and reduce the occurrence of ghost.

The side plate 3a continuous to the auxiliary range 2b
Needless to say, (3b) may also be a tapered surface. Next, FIG. 6 is a view showing a third embodiment of the plastic lens according to the present invention, and this embodiment corresponds to the invention described in claim 6. Since the present embodiment is formed in substantially the same manner as the above-described embodiment, the same reference numerals are given to the same configurations and only the characteristic portions will be described.

In the figure, R is a curved surface, and the curved surface R is continuous with the effective area 2a and constitutes the side surface of the auxiliary area 2b formed in the shape of a protrusion or a groove. It is formed so as to face the mold opening direction of the mold 4. In addition, in this way, the auxiliary range 2 is added to the effective range 2a.
When b is continuous with the curved surface R, it is effective to integrally process the mirror surface piece 6a and the cross-sectional area adjusting plate 7a used for the mold 4 and the mirror surface piece 6b and the cross-sectional area adjusting plate 7b by an NC processing machine or the like. . The same applies to the tapered surface T in the second embodiment.

In this embodiment, in addition to the effects of the second embodiment described above, since the effective range 2a and the auxiliary range 2b are formed so as to be continuous in an arc shape, the molten resin injected and filled has a curved surface. Flow along R. Therefore, when the flow of the molten resin is improved, the resin amount can be made uniform and the internal strain can be reduced. Needless to say, the side plate 3a (3b) continuous with the auxiliary range 2b may be similarly curved and continuous, and the tapered surface T of the second embodiment described above may be continuously curved. .

[0031]

According to the first and second aspects of the invention, in the case of a plastic member having an accuracy required range, for example, a long plastic lens, the area of the vertical section including the effective range of the lens surface is Since the vertical cross-sectional area outside the range is made uniform by changing it in the longitudinal direction, it is possible to make the amount of resin in the longitudinal direction uniform when manufacturing by injection molding, and reduce variations in resin internal pressure and resin temperature. You can Further, the influence of external load such as the temperature applied after fabrication can be made uniform in the longitudinal direction. Therefore, it can be manufactured with high accuracy without increasing the cooling time and the like. Further, even after being manufactured, it does not deform due to the environment.

According to the third aspect of the present invention, the area outside the range that is changed to make the vertical cross-sectional area uniform is increased or decreased from the average before change to reduce the difference, so that it is manufactured by injection molding. In this case, the deviation of the resin temperature in the vertical cross section can be reduced. Therefore, it can be manufactured with higher accuracy. According to the invention described in claim 4, the shape outside the range to be changed in order to make the vertical cross-sectional area uniform is made symmetrical in the thickness direction. Therefore, when manufacturing by injection molding, the difference in the amount of resin in the mold. It is possible to reduce the temperature difference caused by. Therefore, it is possible to prevent the sink mark generated on the transfer surface due to the temperature difference.

According to the fifth aspect of the present invention, the boundary between the outside and the outside is tapered, and the tapered surface is open so as to face outward. Therefore, at the time of taking out by injection molding, The molding surface can be separated only by moving the mold. Therefore, releasability can be improved. Further, in the case of a plastic lens, it is possible to prevent diffuse reflection outside the effective range and reduce ghost.

According to the sixth aspect of the present invention, the boundary between the outside and the outside is formed in an arc shape, or the boundary between the tapered surface and the tapered surface is formed in an arc shape so as to be a continuous shape. The flow of resin to be injected and filled can be improved. Therefore, it is possible to improve the releasability and reduce the ghost, as well as reduce the internal strain.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a first embodiment of a plastic lens according to the present invention, and is a longitudinal sectional view in a longitudinal direction thereof.

FIG. 2 is a plan view of the first embodiment.

FIG. 3 is a vertical cross-sectional view orthogonal to the longitudinal direction showing a main part of the first embodiment, (a) is a vertical cross-sectional view at a position A, and (b) is a cross-sectional view.
[Fig. 3] is a vertical sectional view at a position C.

FIG. 4 is a perspective view showing a schematic configuration of an injection molding die for manufacturing the first embodiment.

FIG. 5 is a vertical cross-sectional view showing a main part of a second embodiment of a plastic lens according to the present invention, the view being orthogonal to the longitudinal direction;
(A) is a vertical sectional view at a position A, and (b) is a vertical sectional view at a position C.

FIG. 6 is a longitudinal sectional view orthogonal to the longitudinal direction showing a main part of a third embodiment of a plastic lens according to the present invention,
(A) is a vertical sectional view at a position A, and (b) is a vertical sectional view at a position C.

FIG. 7 is a diagram showing an overall configuration of a conventional plastic lens, and is a longitudinal sectional view in the longitudinal direction thereof.

8A and 8B are vertical cross-sectional views orthogonal to the longitudinal direction showing a main part of a conventional example, where FIG. 8A is a vertical cross-sectional view at position A, FIG. 8B is a vertical cross-sectional view at position B, and FIG. It is a longitudinal cross-sectional view in the position C.

[Explanation of symbols]

 2 Lens part 2a Effective range 2b Auxiliary range (extended part) 3 Rib 4 Mold 5 Cavities 6a, 6b Mirror surface piece 7a, 7b Cross sectional area adjusting plate 10 Plastic lens (plastic member) C2 Center plane (flat) P1 Effective vertical cross section ( Required vertical section) P2 Auxiliary vertical section r1, r2 Lens surface R Curved surface (arc shape) T Tapered surface

Claims (6)

[Claims] 1. A plastic member in which an area of a required vertical section that vertically cuts a range required for accuracy changes according to the vertical position, and an area of an enlarged vertical section including the required vertical section obtained by extending the required vertical section. The plastic member is characterized in that the area of the extended portion of the enlarged vertical cross section is changed so as to be substantially uniform. 2. A plastic lens in which a lens portion is formed in a long size and an area of an effective vertical cross section longitudinally cutting an effective range of the lens portion changes in a longitudinal direction, and the effective vertical cross section is obtained by extending the effective vertical cross section. A plastic lens, wherein the area of the extended portion of the enlarged vertical section is changed in the longitudinal direction so that the area of the enlarged vertical section including the surface becomes substantially uniform. 3. The plastic lens according to claim 2, wherein the area of the enlarged vertical section is formed to be a substantially average value when the area of the extended portion of the enlarged vertical section is not changed. 4. The plastic lens according to claim 2, wherein the extended portion of the enlarged vertical section is formed so as to be symmetrical with respect to a plane passing through the center of the effective range in the thickness direction. . 5. The plastic lens according to claim 2, wherein a taper shape that faces outward is provided between the extended portion of the enlarged vertical section and the effective range. 6. The plastic lens according to claim 2, wherein the extended portion of the enlarged vertical section and the effective range are made continuous by an arc shape.