Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specified detail of transducer assembly support structure
Reexamination Certificate
2001-06-07
2004-03-02
Cao, Allen (Department: 2652)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specified detail of transducer assembly support structure
Reexamination Certificate
active
06700860
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for adjusting the tilt angle of an optical pickup used for an optical recording and reproducing apparatus for effecting recording or reproduction with respect to a compact disk, an optical disk, or the like.
2. Description of the Related Art
An optical pick up has the function of applying laser light upon a disk, and unless the direction of application of the laser light is adjusted appropriately, optical aberrations occur, so that drawbacks such as a decline in a signal level occurs. For this reason, a tilt-angle adjusting step for appropriately adjusting the direction of application of the laser light with high accuracy is included in the process of fabrication of the optical pickup. A conventional tilt-angle adjusting device for effecting the tilt-angle adjusting step is shown in
FIG. 13
, and the configuration of a leaf spring used in the tilt-angle adjusting device is shown in FIG.
14
. Further, the operation based on the tilt-angle adjusting device is shown in FIG.
15
.
In
FIG. 13
, reference numeral
1
denotes an optical base serving as a main base. A spherical seat
3
is provided on a bottom plat
2
of this optical base
1
. Reference numeral
4
denotes an actuator on which a lens unit (not shown) for application of laser light is mounted, and the actuator
4
has supported portions
5
. The supported portions
5
are mounted and supported on the spherical seat
3
of the optical base
1
in such a manner as to be tiltable about a center X (see
FIG. 15
) of the spherical seat
3
. For this reason, the actuator
4
is tiltable about the center X.
A leaf spring
6
is screwed down in a predetermined position on the optical base
1
. One portion of a base
7
of the actuator
4
is resiliently pressed by this leaf spring
6
at an eccentric position from the spherical seat
3
, and the supported portions
5
of the actuator
4
are pressed against the spherical seat
3
by its resiliently pressing force. Meanwhile, threaded holes
8
and
9
are provided at two other portions of the base
7
of the actuator
4
, and screwed into these threaded holes
8
and
9
are tilt-angle adjusting screws
10
and
11
inserted from the reverse side of the bottom plate
2
into screw insertion holes (not shown) provided in the bottom plate
2
of the optical base
1
. In this state, the tilt-angle adjusting screws
10
and
11
are rotatably fitted at fixed positions on the optical base
1
. Here, the portion a of the base
7
which is resiliently pressed by the leaf spring
6
is located at an eccentric position from the spherical seat
3
. Similarly, the threaded holes
8
and
9
into which the tilt-angle adjusting screws
10
and
11
are screwed are also located at eccentric positions from the spherical seat
3
, and the resiliently pressed portion a and the two threaded holes
8
and
9
are arranged in such a manner as to be distributed on both sides with the center X of the spherical seat
3
placed therebetween.
As shown in
FIG. 14
, the leaf spring
6
is formed by a single flat plate material having an attaching portion
12
and a resilient piece portion
13
. As shown in
FIG. 13
, the attaching portion
12
is fixed to the optical base
1
by means of a screw
14
and, as shown in
FIG. 15
, the resilient piece portion
13
is in resilient contact with a receiving piece portion
15
provided on the base
7
in a state of being superposed on the receiving piece portion
15
. For this reason, the direction of the resiliently pressing force applied to the receiving piece portion
15
of the actuator
4
by the leaf spring
6
has been substantially vertical as shown by arrow F
1
in
FIG. 1
, i.e., substantially parallel to the axis P of the tilt-angle adjusting screw
10
.
On the other hand, JP-A-11-273104 and JP-A-63-129524 give descriptions of optical pickups. Of these publications, JP-A-63-129524 proposes an optical pickup in which the tilt angle of the optical pickup is adjusted by making use of screws and a coil spring. In this optical pickup as well, the resiliently pressing force of the coil spring is parallel to the axial direction of the screw.
However, with the conventional tilt-angle adjusting device described with reference to
FIGS. 13
to
15
, it was found that when the actuator
4
is tilted by rotating the two tilt-angle adjusting screws
10
and
11
to effect the adjustment of the tilt angle of the optical pickup, since its adjustable range is narrow and the torque required for the tilt-angle adjusting screws
10
and
11
changes substantially depending on the amount of rotation, if the amount of rotation becomes large, the required torque becomes excessively large, and the tilt-angle adjusting screws
10
and
11
become difficult to rotate, with the result that it is difficult to ensure adjustment accuracy. On the other hand, if the amount of rotation is small, the required torque becomes excessively small, with the result that the adjustment sensitivity declines. Furthermore, it was found that since the resiliently pressing force applied to the receiving piece portion
15
of the actuator
4
by the leaf spring
6
is constituted by only a substantially downwardly oriented force, and the situation is such that practically no horizontal component is generated, the actuator
4
is likely to produce a horizontal positional offset.
SUMMARY OF THE INVENTION
The invention has been devised in view of the above-described circumstances, and its object is to provide a device for adjusting the tilt angle of an optical pickup by using a leaf spring and tilt-angle adjusting screws, which makes it possible to expand the adjustable range of the tilt angle, in which the torque required for rotating the tilt-angle adjusting screw ceases to change so much depending on the amount of rotation so as to make it possible to effect the adjustment of the tilt angle smoothly with high sensitivity, and in which the actuator is difficult to cause a horizontal positional offset, by allowing the resiliently pressing force imparted to the actuator by the leaf spring to generate a vertical component and a horizontal component.
The device for adjusting the tilt angle of an optical pickup includes: an optical base having a spherical seat; an actuator having supported portions supported by the spherical seat in such a manner as to be tiltable about a center of the spherical seat; a leaf spring for pressing the supported portions against the spherical seat by resiliently pressing a portion of a base of the actuator at an eccentric position from the spherical seat; and a tilt-angle adjusting screw fitted rotatably to a fixed position on the optical base and screwed down in a threaded hole at another portion of the base at an eccentric position from the spherical seat. Further, the direction of a resiliently pressing force applied to the actuator by the leaf spring is tilted with respect to an axis of the tilt-angle adjusting screw.
According to the above-described arrangement, the resiliently pressing force imparted to the actuator by the leaf spring generates a vertical component and a horizontal component. Accordingly, the adjustable range of the tilt angle expands, and the torque required for rotating the tilt-angle adjusting screw ceases to change so much depending on the amount of rotation to make it possible to effect the adjustment of the tilt angle smoothly with high sensitivity. Furthermore, the actuator is difficult to cause a horizontal positional offset.
Preferably, the leaf spring includes an attaching piece portion which is attached to the optical base, a resilient piece portion continuing from the attaching piece portion, and an applying portion which is provided in the resilient piece portion and is in resilient contact with the one portion of the base. As a specific example of such a leaf spring, it is possible to suitably use one having the following structure.
Namely, it is possible to suitably use a leaf spring in which the resilient piece portion has a projectio
Harada Suehiro
Ito Tatsuya
Cao Allen
Funai Electric Co. Ltd.
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