Optical pickup

Details Optical pickup Optical pickup

2003-04-04

2004-03-23

Schwartz, Jordan M. (Department: 2873)

Optical: systems and elements

Lens

With support

C359S819000

Reexamination Certificate

active

06710948

ABSTRACT:

The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2002-114320 filed Apr. 17, 2002, which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical pickup that makes it possible to effect the tilt adjustment of an objective lens easily with an inexpensive structure.
2. Description of the Related Art
As techniques concerning optical pickups, those including one disclosed in JP-A-10-162372 are known. To describe one such example with reference to
FIGS. 7
to
9
, an optical pickup
2
is movably arranged on a pair of guide rails
1
laid along the radial direction of a disk D. A rack
4
is formed integrally with a synthetic resin-made housing
3
of the optical pickup
2
. A pinion
6
, which is forwardly and reversely rotated by a feed motor (not shown) by a gear
5
, meshes with the rack
4
. As the feed motor is forwardly or reversely rotated, the optical pickup
2
can be moved in back-and-forth directions a and b along the guide rails
1
by means of the gear
5
, the pinion
6
, and the rack
4
.
An objective lens unit
8
and a collimator lens QWP are provided on one end side of the housing
3
, while a light receiving element PD constituted by a photodiode IC is provided at the other end side of the housing
3
. A half mirror HM and a semiconductor laser LD are disposed in the housing
3
. Laser light is projected from the semiconductor laser LD onto the disk D through the half mirror HM, the collimator lens QWP, and an objective lens OL of the objective lens unit
8
. The reflected light is received by the light receiving element PD, and information recorded on the disk D is read on the basis of a received light signal thereof.
The objective lens unit
8
includes an actuator base
11
having a shaft
10
provided uprightly in its center; a lens holder
12
for supporting the objective lens OL, the lens holder
12
is fitted to the shaft
10
slidably and oscillatably; a focusing coil
13
and a pair of tracking coils
14
attached to the lens holder
12
; a pair of magnets
15
secured to both side portions of the actuator base
11
with the lens holder
12
located therebetween; and a pair of yokes
17
rising up from the actuator base
11
and respectively inserted in a pair of through holes
16
of the lens holder
12
. As the focusing coil
13
is energized to cause the lens holder
12
to slide along the shaft
10
in a focusing direction, the focus of the objective lens OL is adjusted to the disk D. As the tracking coils
14
are energized to cause the lens holder
12
to oscillate about the shaft
10
in a tracking direction, a predetermined track of the disk D is followed.
Three threaded holes
19
are formed in the actuator base
11
at predetermined intervals, while three through holes
20
are bored in the housing
3
in such a manner as to oppose these threaded holes
19
. One reference bolt
21
and two tilt adjusting bolts
22
are respectively inserted in these through holes
20
. A small-diameter portion at the tip of the reference bolt
21
and the tilt adjusting bolts
22
are screwed into the threaded holes
19
. A recessed portion
23
, which is concentric with the through hole
20
for the reference bolt
21
, is formed in the housing
3
. A cylindrical spring
24
is interposed between a bottom surface
23
a
of the recessed portion
23
and a head
21
a
of the reference bolt
21
. The actuator base
11
is pulled toward an end face side of the housing
3
by the cylindrical spring
24
by means of the reference bolt
21
.
In the above-described construction, in the process of the adjustment of the optical axis prior to shipment from a factory, the actuator base
11
is moved in the back-and-forth directions a and b and in left-and-right directions c and d to horizontally move an optical axis O
1
of the objective lens OL. Meanwhile, the amount of screwing-in of each tilt adjusting bolt
22
is adjusted to tilt the optical axis O
1
of the objective lens OL in radial directions e and f and in tangential directions g and h. Thus the optical axis O
1
of the objective lens OL is precisely aligned with an optical axis O
2
of the laser light.
In the above-described conventional construction, since the housing
3
is formed of a synthetic resin, the end of the cylindrical spring
24
can possibly bite into the bottom surface
23
a
of the recessed portion
23
. As a result, there are cases where the cylindrical spring
24
constitutes a hindrance to the movement of the reference bolt
21
, and the horizontal movement and tilting of the actuator base
11
is hindered, thereby making the tilt adjustment of the objective lens OL difficult.
Accordingly, as shown in
FIG. 10A
, a washer
26
is interposed between the bottom surface
23
a
of the recessed portion
23
and the cylindrical spring
24
. According to this arrangement, the end of the cylindrical spring
24
can easily slide on the washer
26
, facilitating the movement of the actuator base
11
. On the other hand, however, the number of parts increases by the washer
26
and the fabrication cost increases. Also, in a case where the washer
26
has slid on the bottom surface
23
a
in a direction opposite to the sliding direction of the cylindrical spring
24
, there are cases where the end of the cylindrical spring
24
is fitted in a gap &agr; between the inner peripheral wall of the washer
26
and the peripheral wall of the reference bolt
21
. As a result, there are cases where the cylindrical spring
24
constitutes a hindrance to the movement of the reference bolt
21
, and the horizontal movement and tilting of the actuator base
11
is hindered, thereby making the tilt adjustment of the objective lens OL difficult.
SUMMARY OF THE INVENTION
In view of the drawbacks of the above-described conventional art, the object of the invention is to provide an optical pickup that makes it possible to effect the tilt adjust of the objective lens easily with an inexpensive structure.
To attain the above object, in accordance with a first aspect of the invention, there is provided an optical pickup comprising: a housing having a through hole for reference bolt, a recessed portion formed concentric with the through hole for reference bolt and through holes for tilt adjusting bolt; a reference bolt to be inserted in the through hole for reference bolt, the reference bolt having a head; two tilt adjusting bolts to be inserted in the through holes for tilt adjusting bolt; an actuator base attached to an end face of the housing by the reference bolt and the tilt adjusting bolts; a lens holder holding an objective lens, the lens holder is supported on the actuator base; and a tapered conical spring interposed between the recessed portion and the head of the reference bolt, the tapered conical spring having one end portion whose outside diameter is set to be identical to or slightly smaller than a diameter of a bottom surface of the recessed portion and another end portion whose outside diameter is set to be smaller than the outside diameter of the one end portion and identical to or slightly smaller than a diameter of the head of the reference bolt, wherein the one end portion of the tapered conical spring is made to abut against the bottom surface of the recessed portion without abutting against a washer, while the other end portion of the tapered conical spring is made to abut against the head of the reference bolt, thereby urging the actuator base toward the end face of the housing, and each of the tilt adjusting bolts is operated against a spring force of the tapered conical spring so as to align an optical axis of the objective lens with an optical axis of laser light.
According to the above-described construction, even if the one end portion of the conical spring interposed between the bottom surface of the recessed portion and the head of the reference bolt bites into the bottom surface, since the one end portion of the conical spring is formed in the large-di

Affiliated with

Also associated with

Rating

Optical pickup does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Optical pickup, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical pickup will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3288767