Optical: systems and elements – Lens – With support
Reexamination Certificate
2002-05-01
2004-05-25
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
With support
C359S811000, C359S820000, C156S322000
Reexamination Certificate
active
06741407
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical pickup for use in a disk player such as a DVD or a CD and a method of fixing a plate provided with an electronic component such as a photodiode. More particularly, the present invention concerns a technique whereby the fixation of the plate can be effected speedily and accurately.
Conventionally, a technique disclosed in the Unexamined Japanese Patent Application Publication No.Sho62-89249 and the like is known as a technique concerning an optical pickup. One of its examples will be described with reference to FIG.
5
. In this optical pickup, a bilateral pair of projecting portions
1
b
are projectingly provided integrally on one end face
1
a
of a housing
1
, and a plate
2
with a photodiode PD is fixed between the two projecting portions
1
b
. A collimator lens QWP and an objective lens OL are disposed on the other end face
1
c
side of the housing
1
, a half mirror HM is disposed in an inclined state in a groove portion
3
of the housing
1
, and a plate
4
with a semiconductor laser LD is fixed to a side surface
1
d
of the housing
1
. Laser light is projected onto a disk D from the semiconductor laser LD through the half mirror HM, the collimator lens QWP, and the objective lens OL, and the light reflected therefrom is received by the photodiode PD through the half mirror HM, thereby reading information recorded in the disk D.
A description will be given of the procedure of fixing the plate
2
with the photodiode PD in the above-described arrangement. As shown by the phantom lines in
FIG. 6
, the plate
2
is attracted to a permanent magnet
6
b
(see
FIG. 7A
) provided on a lower surface of a distal end of a positioning arm
6
, and is retained by a plurality of pins
6
a
provided projectingly on the lower surface of the distal end of the arm
6
. As the positioning arm
6
is moved in three-dimensional directions a to f in the back-and-forth, left-and-right, and vertical directions, the plate
2
is positioned between the two projecting portions
1
b
with a predetermined interval &agr; from the end face
1
a
of the housing
1
, as shown in
FIG. 7A
, so as to align the center of the photodiode PD with the axis of the objective lens OL. Next, as shown in
FIG. 7B
, by means of an applicator
7
an adhesive
8
is applied to two gaps which are each formed between either side edge
21
of the plate
2
and the housing
1
. The adhesive
8
is allowed to cure so as to fix the plate
2
to the housing
1
, and the positioning arm
6
is raised to move the pins
6
a
away from the plate
2
.
Conventionally, as the aforementioned adhesive
8
, an ultraviolet curing adhesive is generally used, and the ultraviolet curing adhesive is applied over each entire range between either side edge
2
a
of the plate
2
and the housing
1
, as shown in FIG.
7
B.
With the above-described conventional arrangement, as the ultraviolet curing adhesive applied over each entire range between either side edge
2
a
of the plate
2
and the housing
1
is allowed to cure instantly by the application of ultraviolet rays thereto, there is an advantage that the plate
2
can be fixed to the housing
1
in a short time. However, since the degree of shrinkage of the ultraviolet curing adhesive due to temperature change is large, there is a possibility that the center of the photodiode PD becomes positionally offset from the axis of the objective lens OL.
Accordingly, it is conceivable to use as the adhesive
8
a thermosetting adhesive whose degree of shrinkage due to the temperature change is small, and to apply the thermosetting adhesive over each entire range between either side edge
2
a
of the plate
2
and the housing
1
. With the thermosetting adhesive, however, since it takes time to heat and cure the hat curing adhesive, it is necessary to maintain the support of the plate
2
by the positioning arm
6
for a relatively long time, so that this method lacks mass productivity.
In view of the above-described conventional drawbacks, the object of the invention is to provide an optical pickup which makes it possible to speedily and accurately fix a plate provided with an electronic component such as a photodiode, as well as a method of fixing a plate with an electronic component.
SUMMARY OF THE INVENTION
To attain the above object, the invention according to aspect 1 is characterized in that a plate with a photodiode is positioned with a slight interval with respect to a housing, that a small amount of an ultraviolet curing adhesive is applied between either side edge of the plate and the housing, that the ultraviolet curing adhesive is allowed to cure by application of ultraviolet rays thereto to temporarily fix the plate to the housing, that an appropriate amount of a thermosetting adhesive is applied between a central portion of the either side edge of the plate and the housing, and that the thermosetting adhesive is allowed to cure by heating so as to finally fix the plate to the housing.
According to the above-described construction, since the plate with a photodiode is temporarily fixed to the housing by the ultraviolet curing adhesive, there is no need to support the plate at the time of final fixation by the thermosetting adhesive, so that it is possible to overcome the drawback of the thermosetting adhesive that it takes time to cure. In addition, since the amount of ultraviolet curing adhesive applied can be reduced by the portion by which the thermosetting adhesive is applied, it is possible to overcome the drawback of the ultraviolet curing adhesive that the degree of shrinkage due to the temperature change is large. Thus by the combination of the two adhesives, the drawbacks of the two adhesives can be overcome, and the fixation of the plate with the photodiode to the housing can be effected speedily and accurately.
Further, since the four corners of the plate can be temporarily fixed positively to the housing by the ultraviolet curing adhesive, and the thermosetting adhesive is applied between the cured ultraviolet curing adhesive portions, the efflux of the thermosetting adhesive to the outside can be reliably prevented, and the plate can be finally fixed firmly to the housing.
The invention according to aspect 2 is characterized in that a plate with a electronic component is positioned with a slight interval with respect to a housing, that a small amount of an ultraviolet curing adhesive is applied between the plate and the housing, that the ultraviolet curing adhesive is allowed to cure by application of ultraviolet rays thereto to temporarily fix the plate to the housing, that an appropriate amount of a thermosetting adhesive is applied between the plate and the housing, and that the thermosetting adhesive is allowed to cure by heating so as to finally fix the plate to the housing.
According to the above-described construction, since the plate with an electronic component is temporarily fixed to the housing by the ultraviolet curing adhesive, there is no need to support the plate at the time of final fixation by the thermosetting adhesive, so that it is possible to overcome the drawback of the thermosetting adhesive that it takes time to cure. In addition, since the amount of ultraviolet curing adhesive applied can be reduced by the portion by which the thermosetting adhesive is applied, it is possible to overcome the drawback of the ultraviolet curing adhesive that the degree of shrinkage due to the temperature change is large. Thus by the combination of the two adhesives, the drawbacks of the two adhesives can be overcome, and the fixation of the plate with the electronic component to the housing can be effected speedily and accurately.
The invention according to aspect 3 is characterized in that, in the optical pickup according to aspect 2, the ultraviolet curing adhesive is applied to a plurality of portions at predetermined intervals between either side edge of the plate and the housing, and that the thermosetting adhesive is applied to gaps other than portions where the ultraviolet
Fujita Ken-ichi
Harada Suehiro
Epps Georgia
Funai Electric Co. Ltd.
Martinez Joseph
Morgan & Lewis & Bockius, LLP
LandOfFree
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