Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specified detail of transducer assembly support structure
Reexamination Certificate
1996-06-24
2002-11-12
Young, W. R. (Department: 2653)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specified detail of transducer assembly support structure
C369S044160
Reexamination Certificate
active
06480460
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to optical pickups used for recording and/or reproducing information signals and, in particular, to a biaxial actuator for an objective lens of an optical pickup used for recording and reproducing signals of a CD, MD, digital video disc, or other information recording medium.
2. Description of the Related Art
Conventionally, reproduction or recording of information signals with respect to a disc-form recording medium, such as an optical disc, for example a so-called compact disc (CD) or an optomagnetic disc, has been carried out using an optical pickup. This optical pickup includes a semiconductor laser as a light source, an objective lens, an optical system and a light detector.
In an optical pickup, a light beam emitted from the semiconductor laser is converged through the optical system onto the recording surface of an optical disc by the objective lens. A return light beam from the optical disc is split from the light beam emitted from the semiconductor laser and guided to the light detector by the optical system. The position of the objective lens in the optical axis direction is adjusted so that the light beam emitted from the semiconductor laser follows displacements of the optical disc in a direction intersecting orthogonally with the plane direction of the optical disc occurring as a result of warp of the optical disc and the like and is focused at the recording surface of the optical disc. At the same time, the position of the objective lens in a direction intersecting orthogonally with the optical axis is adjusted so that the position of a spot on the optical disc of the light beam emitted from the semiconductor laser follows any eccentricity of the optical disc and snaking of a track formed on the optical disc.
This adjustment of the focusing position and the spot position on the recording surface of the light beam emitted from the semiconductor laser is carried out by adjusting the position in the optical axis direction of the objective lens and the position in a direction intersecting orthogonally with the optical axis of the objective lens. An electromagnetically driven actuator is used for positional adjustment of the objective lens.
This actuator is called an objective lens actuator or a biaxial actuator and includes a bobbin on which the objective lens is mounted and on which a plurality of coils are wound, a plurality of elastic supporting members and a driving part that generates driving forces by passing currents through the coils of the bobbin.
The bobbin is so supported with respect to a fixed part by the plurality of elastic supporting members that the position of the objective lens in the optical axis direction, namely the focusing position, and the position of the objective lens in a direction intersecting orthogonally with the optical axis, namely the tracking position, are adjustable. An example of this biaxial actuator is described below with reference to
FIGS. 8 and 9
.
This kind of biaxial actuator is constructed for example as shown in FIG.
8
. That is, a biaxial actuator
1
, as shown in
FIG. 8
, comprises a lens holder
2
on the front end of which is mounted an objective lens
2
a
and a coil bobbin (not shown in the drawing) attached to this lens holder
2
by means of an adhesive or the like.
The above-mentioned lens holder
2
is supported with respect to a fixed part
3
movably in two perpendicular directions, namely a tracking direction perpendicular to the paper surface and a focusing direction shown with the mark Fcs, by two pairs of wires
4
having one end fixed to both sides of this lens holder
2
and the other end fixed to the fixed part
3
.
Also, on the above-mentioned coil bobbin are wound a coil for focusing and a coil for tracking (not shown in the drawing). By passing currents through the coils, magnetic flux produced in the coils mutually acts on magnetic flux from a yoke attached to the fixed part
3
and a magnet attached thereto (not shown in the drawing).
Also, the rear ends of the above-mentioned wires
4
pass through this fixed part
3
and are soldered to a base plate
5
. Here, as shown in
FIG. 9
, to suppress vibration of these wires
4
, these wires
4
are fitted through dampers
6
passed through holes
3
a
,
3
b
in the fixed part
3
. In the case of
FIG. 9
, the dampers
6
are in contact with the base plate
5
.
With a biaxial actuator
1
constructed like this, and driving voltages being supplied to the coils from outside, magnetic flux produced in the coils mutually acts on magnetic flux from the yoke and the magnet and this coil bobbin is moved with respect to the tracking direction and the focusing direction Fcs. In this way, the objective lens
2
a
mounted on the lens holder
2
is suitably moved with respect to the focusing direction and the tracking direction.
When the lens holder
2
is moved with respect to the focusing direction and the tracking direction in this way, this lens holder
2
tries to vibrate in relation to the movement direction, but by the damping action of the dampers
6
provided near the rear ends of the wires
4
the vibration is suppressed. As a result, the lens holder
2
is stopped in a predetermined position in a stable state.
A biaxial actuator constructed as shown in
FIG. 10
is also known. That is, a biaxial actuator
7
comprises a lens holder
2
on the front end of which is mounted an objective lens
2
a
and a coil bobbin (not shown in the drawing) attached to this lens holder
2
by means of and adhesive or the like.
The above-mentioned lens holder
2
is movably supported with respect to a fixed part
3
in two perpendicular directions, namely a tracking direction perpendicular to the paper surface and a focusing direction, at least one pair of sheet springs
8
having one end fixed to both sides of this lens holder
2
and the other end fixed to the fixed part
3
.
Also, on the above-mentioned coil bobbin are wound a coil for focusing and a coil for tracking (not shown in the drawing). By passing currents through the coils, magnetic flux produced in the coils mutually acts on magnetic flux from a yoke attached to the fixed part
3
and a magnet attached thereto (not shown in the drawing).
In this case, the rear end vicinity of each of the above-mentioned sheet springs
8
, as shown in
FIG. 11
, has a crank part
8
a
bent into a crank shape toward the inner side and an extension part
8
b
extending from further forward than this crank part
8
a
toward the outer side and extending to the rear, and is provided with a projecting part
8
c
projecting from the rear end of this sheet spring
8
between the above-mentioned crank part
8
c
and the extension part
8
b
. A slit
8
e
is set in a direction intersecting orthogonally with the optical axis direction of the objective lens
2
a
between this projecting part
8
c
and the crank part
8
a.
An anti-vibration tape
9
is affixed as a damper so as to completely cover this crank part
8
a
and the extension part
8
b
, and the projecting part
8
c
and slit
8
e
extending therebetween.
When the lens holder
2
is moved with respect to the focusing direction and the tracking direction in this way, this lens holder
2
tries to vibrate in relation to the movement direction, but by the damping action of the anti-vibration tape
9
provided in the vicinity of the rear ends of the sheet springs
8
the vibration is suppressed. As a result, the lens holder
2
is stopped in a predetermined position in a stable state.
However, in a biaxial actuator
7
of this kind of construction, when moving the lens holder
2
in the focusing direction, there have been the following kinds of problem. That is, FIGS.
12
(
a
) and
12
(
b
) show a state of the lens holder
2
being moved in the focusing direction and brought close to a disc D, and FIGS.
13
(
a
) and
13
(
b
) show a state of the lens holder
2
being moved in the focusing direction and moved away from the disc D.
As shown in FIGS.
12
(
a
) and
12
(
b
), when the le
Mitsumori Koji
Ohkuma Hideo
Kananen, Esq. Ronald P.
Rader & Fishman & Grauer, PLLC
Sony Corporation
Young W. R.
LandOfFree
Actuator for an objective lens of an optical pickup for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Actuator for an objective lens of an optical pickup for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Actuator for an objective lens of an optical pickup for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2955617