Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specific detail of storage medium support or motion production
Reexamination Certificate
2002-04-25
2004-08-17
Klimowicz, William (Department: 2652)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specific detail of storage medium support or motion production
C369S270100
Reexamination Certificate
active
06778487
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a turntable that is provided in a disc-drive for rotationally driving a disc-like recording medium, such as an optical disc or a magneto-optical disc, and recording and/or reproducing information, as well as to a method of manufacturing the turntable, a disc chucking apparatus that uses the turntable, and a disc-drive that uses the turntable.
2. Description of the Related Art
Information is usually recorded onto and reproduced from a disc-like recording medium like an optical disc (e.g., a CD (Compact Disc), CD-ROM (Compact Disc-Read Only Memory), or a DVD (Digital Video/Versatile Disc)), and a magneto-optical disc by loading a disc into a disc-drive. In a disc-drive, a disc-like recording medium in the form of an optical disc is placed upon a turntable that is attached to a rotational shaft of a spindle motor, the disc is chucked, and the disc is rotationally driven while an optical head of an optical pickup apparatus irradiates laser light at the information recording surface of the optical disc, with recording or reproduction being performed for the optical disc as the optical pickup apparatus is moved in the radial direction.
FIG. 8
shows a conventionally known disc chucking apparatus and a disc-drive. The disc-drive
1
shown in
FIG. 8
is composed of a box-like main chassis
2
that has openings in the top and the front surfaces, a disc tray
3
with a disc mounting part
3
a
that is moved in and out of the front opening of the main chassis
2
and on which an optical disc D is placed, a base holder
4
that is kept in a depressed part in the main chassis
2
and is supported so as to be able to swing, and a base unit
5
that is elastically supported by the base holder
4
.
The base unit
5
includes a spindle chassis
7
that supports a turntable
6
to which the optical disc D is attached, so that the turntable
6
is freely rotatable and a pickup chassis
9
that supports an optical pickup apparatus
8
, which reproduces information from the optical disc D that has been attached to the turntable
6
, in a way such that the optical pickup apparatus
8
is able to move. The spindle chassis
7
and pickup chassis
9
compose a base chassis
10
.
The pickup chassis
9
of the base unit
5
is supported in approximately the center of the spindle chassis
7
, so as to be freely rotatable, while a rear end of the base holder
4
that supports the base unit
5
is rotatably supported by the main chassis
2
. A cam pin
11
that is provided at the front end of the base holder
4
engages a chuck cam mechanism
12
disposed at the front of the main chassis
2
, so that the base holder
4
is rotated up and down by the movement of the chuck cam mechanism
12
with the support at the rear end of the base holder
4
as the pivot.
A mounting part
6
a
on which the periphery of the center hole d of the optical disc D is placed and a disc engaging part
6
b
in the form of a truncated cone that engages the center hole d are integrally formed in the turntable
6
that is supported by the spindle chassis
7
, with a ring-shaped magnet
13
being inserted along with a ring-shaped yoke plate
14
onto the disc engaging part
6
b
. A central shaft part of this turntable
6
engages and is fixed to rotational shaft
15
a
of a spindle motor
15
that is fixed to the spindle chassis
7
.
A chuck holder
16
is attached to the top of the main chassis
2
so as to cross the disc tray
3
above the disc tray
3
. A chucking plate
17
that faces the turntable
6
is supported by the chuck holder
16
, so as to be capable of swinging and rotating.
When the disc-drive
1
of the above construction is not in use, the base unit
5
is moved downwards. In other words, the front of the base holder
4
is rotated downwards at an angle about the rear support, with the turntable
6
that is supported by the spindle chassis
7
being positioned below the disc tray
3
.
In order to reproduce an optical disc D, the disc tray
3
is first ejected from the main chassis
2
by an eject operation. After an optical disc D has been placed on the disc mounting part
3
a
, a loading operation is performed and the disc tray
3
is retracted back into the main chassis
2
, with the base holder
4
being rotated upwards into an approximately horizontal state via the cam pin
11
due to the chuck cam mechanism
12
being driven. Since the base holder
4
is moved upwards in this way, the turntable
6
enters the opening
3
b
in the disc tray
3
from below, with the disc engaging part
6
b
engaging the center hole d of the optical disc D that has been placed on the disc tray
3
and the periphery of the center hole d being mounted on the disc mounting part
6
a
of the turntable
6
. The mounting part
6
a
of the turntable
6
lifts up the optical disc D slightly, with the chucking plate
17
that is supported by the chuck holder
16
being held by the magnet
13
that is inserted on the disc engaging part
6
b
of the turntable
6
.
As a result, the optical disc D is chucked by being supported on both sides by the turntable
6
and the chucking plate
17
so that the optical disc D is coupled with the turntable
6
in the rotational direction and is rotated at a predetermined speed by the driving force of the spindle motor
15
, with reproduction being performed by predetermined movement of the optical pickup apparatus
8
.
In a disc-drive
1
of the above construction, the turntable
6
of the rotational driving mechanism for the optical disc D is constructed of a ring-shaped magnet
13
and a ring-shaped yoke plate
14
that are inserted, as shown in
FIG. 11
, onto the disc engaging part
6
b
, which engages the center hole d of the optical disc D and is in the form of a truncated cone, so as to surround the center shaft portion of the disc engaging part
6
b
. With this construction, the optical disc D is chucked as shown in
FIG. 8
between a chucking plate
17
and the magnet
13
and yoke plate
14
.
The magnet
13
and the yoke plate
14
have to be inserted onto the disc engaging part
6
b
concentrically with the central shaft part of the turntable to prevent eccentric rotation of the turntable
6
.
For the above reason, when the magnet
13
and the yoke plate
14
are inserted and the turntable
6
is molded, it is necessary to position the magnet
13
and the yoke plate
14
accurately. As shown in
FIG. 11
, this is conventionally achieved by arranging molding pins
18
for positioning the magnet
13
and the yoke plate
14
in the horizontal direction at at least three positions around the circumferential surface of the disc engaging part
6
b
during the molding of the turntable
6
. The turntable
6
is then molded with the magnet
13
and the yoke plate
14
being positioned in the horizontal direction by these molding pins
18
.
However, with a turntable
6
that has been molded as described above, the withdrawal holes
19
of the molding pins
18
are exposed to the circumferential surface of the disc engaging part
6
b
, as shown in
FIGS. 9 and 10
. When a disc chucking operation is performed with this turntable
6
, as shown in
FIGS. 12A and 12B
, the turntable
6
rises from a position below and at an angle to the optical disc D, so that the disc engaging part
6
b
engages the center hole d of the optical disc D.
At this point, the sloped circumferential surface of the disc engaging part
6
b
, which composes the disc sliding surface
6
c
, comes into sliding contact with the inner circumferential edge of the center hole d, wherein the withdrawal holes
19
of the molding pins
18
ends up being on the disc sliding surface
6
c
for the inner circumferential edge of the center hole d of the optical disc D to get caught on the edges of the withdrawal holes
19
of the molding pins
18
that are positioned in the disc sliding surface
6
c
(i.e., the circumferential surface of the disc engaging part
6
b
), leading to potential problems during the chucking of the optical disc D. In particular, if bu
Kananen Ronald P.
Klimowicz William
Rader & Fishman & Grauer, PLLC
Sony Corporation
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