Optical: systems and elements – Lens
Reexamination Certificate
2000-12-21
2002-10-15
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
C359S819000, C359S830000, C425S808000
Reexamination Certificate
active
06466376
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a plastic lens formed by the injection molding and to a production method thereof.
The plastic lens is used for, for example, an optical system for optical pick-up apparatus and cameras. When such the plastic lens is molded by the injection molding, at least a gate portion which is a resin injection path, is integrally formed with the plastic lens at the time of molding.
The integrally formed gate portion at the molding, is cut from the plastic lens and removed after that. Conventionally, as shown in
FIG. 12
, the plastic lens in which a gate-cut plane
100
b
formed when the gate portion
100
a
integrally formed at the time of the molding of the plastic lens
100
is cut, is linear, or as shown in
FIG. 13
, the gate-cut plane
100
b
is arc-shaped along the outer periphery of the plastic lens, is well known.
Further, as shown in
FIG. 14
, a plastic lens
100
in which a gate-cut plane
100
b
formed by cutting a gate portion
100
a
is made to be the same arc-shaped as the plastic lens as shown in
FIG. 13
, and further, at a different position from the gate-cut plane
100
b
, a gate position indicating section
100
c
showing the gate-located position is formed, is known.
In this connection, in the plastic lens formed such the injection molding, generally, the un-uniformity of the molecular orientation or inner distortion is generated due to the injection molding, and when the plastic lens is rotated around the optical axis of the plastic lens, the optical performance of the lens is changed. Accordingly, for example, when the mounting position of the plastic lens to each kind of optical system or apparatus is not constant for the plastic lens rotational direction, the performance among products are not stable even in the same optical system or same apparatus, and there is a case where a desired optical characteristic can not be obtained.
Accordingly, the mounting position is made constant, for example, on the basis of a portion corresponding to a position at which the gate portion of the plastic lens existed (hereinafter, called gate-located position), however, in the gate-cut plane
100
b
which is linear as shown in
FIG. 12
, or the arc-shaped gate-cut plane
100
b
along the outer periphery of the plastic lens as shown in
FIG. 13
, specifically for the down sizing of the plastic lens, the more the width of the flange portion of the plastic lens is reduced, or the more the diameter of the plastic lens is decreased, the more the gate-cut plane of the plastic lens is difficult to be distinguished from the outer periphery of the other plastic lens, and problems in which the gate-located position or the central gate-located position which is the central portion of the gate portion can not be detected, and the detection accuracy is lowered, and the operability of the assembling is lowered, occur.
On the one hand, in the plastic lens shown in
FIG. 14
, a gate position indicating section
100
c
showing the gate-located position is formed at a position different from the gate-cut plane
100
b
, and when the detection of the gate position indicating section
100
c
is easy, and the positional relationship with the gate-located position of the gate position indicating section
100
c
is clear, the assembling position can be made constant on the basis of the gate position indicating section
100
c
, however, when the gate position indicating section is provided on the position as shown in
FIG. 14
, it is also difficult for the operator who generally looks the plastic lens from the optical axis direction (the direction along the optical axis) to detect the gate position indicating section, and it is also difficult to correspond to it by using the conventional commonly used detector, and there is also a problem that it is yet insufficient to obtain the plastic lens which has the easily assembling operability unless the easiness of detection is increased, further, without decreasing the detection accuracy. Further, there is also a problem that the new detector to detect the gate position indicating section is necessary, and the production cost of the product is increased.
Furthermore, when the gate position indicating section is provided as a recess, because it is difficult to provide a recess by the molding die from the problem of the durability and the accuracy of the molding die of the lens, a process to newly provide the gate position indicating section is necessary. Therefore, the problems that the production cost is increased, and the time necessary for the production becomes long, occur.
Further, when the gate position indicating section is provided as a protrusion, the following problem occurs. When the gate position indicating section of the gate portion of the plastic lens is cut, it is preferable to use the masking so that the chip does not adhere onto the lens surface, however, a problem that, when the protrusion exists, the masking is difficult, and the chip adheres onto the lens surface, occurs.
SUMMARY OF THE INVENTION
The present invention is attained in view of such the problems, and the object of the present invention is to provide a plastic lens by which an object to make the detection of the gate-located position of the plastic lens easy, and to increase the detection accuracy, and an object that the lens can be easily assembled in a desired direction and the optical performance is stabilized, can be stood together, and to provide a production method thereof. Further, the object is to provide the plastic lens and the production method thereof, by which, because the cutting of the gate-located position and the display of the gate-located position can be conducted in the continuous or the same process, the production can be conducted quickly and at low cost. Further, the object is to obtain the plastic lens by which, even when the lens is a small sized one, the gate portion can be easily cut, and there is no flaw in the optical function portion, and the stable optical performance can be obtained. Further object is to obtain the plastic lens which can be stably held.
In order to solve the above problems and attain the objects, the invention is structured as follows.
(1-1) A plastic lens molded through a gate in a molding process, comprises
a gate-located portion on an outer peripheral surface of the plastic lens, and
a concave surface provided on at least a part of the gate-located portion.
(1-2) In the plastic lens of (1-1), a form of the concave surface is concave when the form is viewed along an optical axis of the plastic lens.
(1-3) In the plastic lens of (1-1), the concave surface is provided onto an entire surface of the gate-located portion.
(1-4) In the plastic lens of (1-1), the concave surface is provided on at least a part of the gate-cut surface in the gate-located portion.
(1-5) In the plastic lens of (1-4), the gate-cut-out surface other than the concave surface is shaped in a flat surface or an arc-shaped convex surface.
(1-6) In the plastic lens of (1-4), the gate-cut-out surface is the concave surface.
(1-7) In the plastic lens of (1-1), the plastic lens further comprises:
an optical function section to perform an optical function;
wherein the concave portion is provided on an outer peripheral surface of the optical function section.
(1-8) In the plastic lens of (1-1), the plastic lens further comprises:
an optical function section to perform an optical function and
a flange section;
wherein the concave portion is provided on an outer peripheral surface of the flange section.
(1-9) In the plastic lens of (1-1), a distance between an imaginary peripheral surface on the concave portion and a bottom of the concave portion has the shortest distance of 0.15 mm to 0.25 mm.
(1-10) In the plastic lens of (1-1), an angle formed between a line connecting a bottom section of the concave portion to an optical axis of the plastic lens with a shortest distance and a line connecting a center of the gate-located portion to the optical axis with a shortest distance is not larger than 10 degrees.
(1-
Ishida Kazuo
Koshimizu Toshiyuki
Kurihara Etsuzo
Epps Georgia
Konica Corporation
O'Neill Gary
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