Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2001-04-27
2003-05-27
Huber, Paul W. (Department: 2653)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S053190
Reexamination Certificate
active
06570828
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention: relates to an optical pickup device or use with an optical disk apparatus for recording and/or reproducing an optical disk which is a disk-like optical recording medium such as an optical disk and a magneto-optical disk.
2. Description of the Related Art
Optical pickup devices are generally for use with an optical disk apparatus. An optical disk apparatus, such as a CD player and a DVD player for reproducing an optical disk, includes an optical pickup device alone, and a magneto-optical disk apparatus for recording and/or reproducing a magneto-optical disk includes an optical pickup device combined with a magnetic head device serving as an overwrite head.
While this optical pickup device is able to read out a signal from an optical disk by irradiating laser beams on the optical disk, if the optical disk is encountered with a trouble such as a skew, then a laser beam irradiated from an objective lens is focused on a signal surface with an inclination. As a result, a focus of a laser beam is spread as an elliptical focus and reading of a signal becomes indefinite due to a crosstalk so that a picture quality is deteriorated when a video signal is read out from the signal surface.
For this reason, since laser beams should constantly be irradiated on the optical disk perpendicularly in order to accurately read out a signal from the optical disk, the optical pickup device detects a disk skew so as to constantly read a recorded signal with the best optical aberration state relative to the skew of the optical disk and reads (reproduces) a recorded signal by mechanically inclining the optical pickup device itself, i.e., adjusts a skew based on a detected signal.
As an optical disk apparatus in which the disk skew is detected and the optical disk is reproduced while the optical pickup device itself is being inclined mechanically, there is known an optical disk apparatus in which a mechanical chassis includes a pickup chassis having an optical pickup device which is driven with an inclination independently of a disk drive chassis including a spindle motor and a turntable, a sensor for detecting an inclination of a disk is disposed on this pickup chassis, this sensor detects an inclination of a disk surface relative to the optical axis of the optical pickup device and skew servo for adjusting an angle of the optical axis of the optical pickup device is effected by driving the pickup chassis with an inclination in accordance with the detected inclination.
In recent years, there has been sued an optical disk apparatus including an optical pickup device which introduces skew servo to calculate an optical jitter value by directly monitoring a jitter value of an RF signal of an optical pickup device without the sensor for detecting the inclination of the optical disk.
As the optical disk apparatus including the above optical pickup device, there is proposed an optical disk apparatus as shown in
FIGS. 15
to
18
.
A base chassis
2
of an optical disk apparatus
1
shown in
FIGS. 15
to
18
is comprised of a spindle chassis
4
including a rotary drive mechanism
3
for rotating an optical disk D and a pickup chassis
6
including an optical pickup device
5
for reading out an information recording signal from the optical disk D rotated by the rotary drive mechanism
3
in such a manner that the optical pickup device can be moved.
The spindle chassis
4
is shaped as a substantially rectangular frame-like chassis. A front side portion
4
a
which is one end side of the longitudinal direction is substantially twice as high as other three side portions. Its top surface is inwardly extended and its central portion is protruded in the upper direction, thereby providing a motor attachment base
7
. A spindle motor
8
is attached to the lower surface side of this motor attachment base
7
. A rotary shaft
8
a
of this spindle motor is protruded to the upper surface side of the motor attachment base
7
, and a turntable
9
is fitted into and fixed to the protruded end of the rotary shaft at a fitting portion
9
a
of the central portion. The spindle motor
8
and the turntable
9
constitute the rotary drive mechanism
3
.
On the other hand, the pickup chassis
6
is substantially the same in shape as the three-side portion without the front side portion
4
a
of the spindle chassis
4
, i.e., substantially U-letter shape of substantially the same size when viewed from a plan, and a coupling member
6
a
is extended between the front ends of the pickup chassis. This pickup chassis
6
is disposed on the spindle chassis
4
behind the front side portion
4
a.
In the inside of one side portion
6
b
of this pickup chassis
6
, there is extended a feed screw shaft
10
of the optical pickup device
5
in the front and back direction so that the feed screw shaft may be pivotally supported at the front and rear ends. The feed screw shaft is coupled at its front end to a feed motor
11
attached to the front end face of the one side portion
6
b.
In the inside of another side portion
6
c
of the pickup chassis
6
, there is extended a guide shaft
12
in parallel to the feed screw shaft
10
. A cam member
13
is protruded from the upper front end of another side portion
6
c.
Shaft portions
14
a,
14
b
are protruded from the lower sides of substantially the central portions of the outside of the two side portions
6
b,
6
c
of this pickup chassis
6
and pivoted at bearing portions
15
a,
15
b
provided at substantially the central portions of the two side portions
4
b,
4
c
of the spindle chassis
4
. While the shaft portions
14
a,
14
b
of the pickup chassis
6
are being pivoted at the bearing portions
15
a,
15
b
of the spindle chassis
4
, a predetermined space is generated between the lower surface side of the pickup chassis and the upper surface side of the three-side portion of the spindle chassis
4
.
The pickup chassis
6
pivotally disposed on the spindle chassis
4
as described above includes the optical pickup device
5
in such a manner that the optical pickup device can be moved close to or moved away from the disk rotary drive mechanism
3
attached to the front side portion
4
a
of the spindle chassis
4
. Specifically, this optical pickup device
5
includes a slide member
17
with a biaxial actuator
16
for driving an objective lens
5
a
mounted thereon and which incorporates therein optical assemblies (not shown). This slide member
17
has a bearing aperture
17
a
defined at its one side. The feed screw shaft
10
at the one side portion
6
b
side of the pickup chassis
6
is inserted into this bearing aperture
17
a
so as to become freely slidable. A slide rack
18
attached to the lower surface of the slide member
17
is meshed with this feed screw shaft
10
. A bearing portion of substantially U-letter shape is provided on the other side of the slide member
17
and tightly inserted into the guide shaft
12
on another side portion
6
c
of the pickup chassis
6
so as to become freely slidable. In this manner, the slide member
17
is supported by the feed screw shaft
10
and the guide shaft
12
and transported by a transport drive mechanism comprised of the feed screw shaft
10
, the feed motor
11
and the slide rack
18
, whereby the optical pickup device
5
is moved close to or moved away from the disk rotary drive mechanism
3
.
Then, the pickup chassis
6
including this optical pickup device
5
is constantly displaced toward the other side portion
4
c
side with elasticity relative to the spindle chassis
4
and is tilted by a tilt drive mechanism
19
. This tilt drive mechanism
19
is attached to the front side portion
4
a
of the spindle chassis
4
and is comprised of a tilt motor
20
attached to the lower surface side of the front side portion
4
a,
a tilt gear
21
fitted into and fixed to a rotary shaft of the tilt motor
20
protruded to the upper surface side and a tilt cam
22
pivotally supported to the upper surface side so as to be meshed with the t
Kikuchi Nobuyasu
Maeda Tetsuo
Seki Yusaku
Sugawara Yutaka
Yamakawa Akio
Huber Paul W.
Kananen, Esq. Ronald P.
Rader & Fishman & Grauer, PLLC
Sony Corporation
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