Dynamic optical information storage or retrieval – Dynamic mechanism optical subsystem – Optical storage medium support
Reexamination Certificate
2002-03-21
2004-06-22
Ometz, David (Department: 2653)
Dynamic optical information storage or retrieval
Dynamic mechanism optical subsystem
Optical storage medium support
Reexamination Certificate
active
06754903
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disc device for rotatably holding a disc, such as a compact disc (CD) or a digital video disc (DVD), or a disc used in, for example, a compact disc read only memory (CD-ROM). More particularly, the present invention relates to a disc device which makes it possible to reduce a load on a mechanical part and which can reliably clamp a disc.
2. Description of the Related Art
FIGS. 14A and 14B
are side views of the main portion of a conventional vehicle-mounted disc device.
FIG. 14A
shows an unclamped state of a disc, while
FIG. 14B
shows a clamped state of the disc.
In the disc device, a slit-like insertion slot
2
is formed in a face provided at the front surface of a housing
1
. A disc D is inserted into the housing
1
from the insertion slot
2
. A transfer roller
4
and a roller supporting member
3
for supporting the transfer roller
4
are provided inwardly of the insertion slot
2
. A guide member
5
is provided above the transfer roller
4
.
A supporting base
6
that is supported in an elastically raised state by, for example, a clamper is provided inside the housing
1
. A spindle motor M and a turntable T, rotationally driven by the spindle motor M, are provided on the supporting base
6
. In addition, an optical head (not shown) and other component parts are provided on the supporting base
6
. A clamping member
7
is rotatably supported on the supporting base
6
through a supporting shaft
9
. A clamper
8
for clamping a disc D on the turntable T as a result of pushing the disc D is rotatably supported at an end of the clamping member
7
. A coil spring
10
for urging the clamping member
7
in the direction of the turntable T is provided near the supporting shaft
9
.
In
FIG. 14A
, the clamping member
7
is lifted by an unclamping member (not shown), so that there is a gap between the turntable T and the clamper
8
. When the disc D is inserted from the insertion slot
2
, the disc D that is clamped by the transfer roller
4
and the guide member
5
is transferred into the gap between the turntable T and the clamper
8
. When the center of the disc D and the center of the turntable T coincide, a lifting force of the unclamping member on the clamping member
7
is removed. At this time, because of the elastic force of the coil spring
10
, the clamping member
7
is rotated in the clockwise direction upon the supporting shaft
9
as a fulcrum, in order to, as shown in
FIG. 14B
, cause the clamper
8
to push the center portion of the disc D against the turntable T and to clamp the disc D.
Then, the spindle motor M rotates to rotationally drive the disc D by the turntable T, so that a signal recorded on the disc D is read by an optical head (not shown).
In the conventional disc device shown in
FIG. 14
, a moment Mc in the clockwise direction is applied to the clamping member
7
by the coil spring
10
, so that, because of the moment Mc, a clamping force Fc for clamping the disc D is exerted on the clamper
8
. Here, when the point upon which an elastic force f applied to the clamping member
7
from the coil spring
10
acts is expressed as
10
a
, and the distance from the center of the supporting shaft
9
to the elastic force f acting point
10
a
is expressed as L
1
, the moment Mc is equal to L
1
×f. In the clamped state shown in
FIG. 14B
, when the point upon which a clamping force Fc applied to the clamper
8
by the clamping member
7
acts is expressed as
7
a
, and a distance from the center of the supporting shaft
9
to the force acting point
7
a
is expressed as L
2
, Fc=(L
1
/L
2
)×f.
Therefore, the elastic force f of the coil spring
10
must be larger than the clamping force Fc required to clamp the disc D by the clamper
8
by a factor of L
2
/L
1
.
For example, in the case where, in order to clamp the disc D, a clamping force Fc of 3 N (approximately 306 gf) with respect to the clamper
8
is required, when L
2
/L
1
=4, the coil spring
10
needs to provide an elastic force f of 12 N (approximately 1.22 kgf).
When a coil spring
10
with such a large elastic force f is used, a large force is applied to the base of the clamping member
7
from the coil spring
10
, so that a distortion tends to occur at the base of the clamping member
7
. In addition, a large load also acts upon the portion of the clamping member
7
rotatably supported by the supporting shaft
9
.
In the conventional structure, when the state of the disc D is to be changed to the unclamped state shown in
FIG. 14A
, the clamping member
7
is lifted by the unclamping member. Hitherto, a point upon which a lifting force Fu, applied to the clamping member
7
from the unclamping member, acts is set at the base end portion side of the clamping member
7
. Accordingly, when the disc device is constructed so that the clamping member
7
is lifted obliquely upward with the supporting shaft
9
as a fulcrum, the distance that the clamping member
7
is lifted by the unclamping member can be made small by lifting the base end portion of the clamping member
7
.
However, when the disc device is constructed so that the lifting force Fu is applied to the base of the clamping member
7
, since the distance between the lifting force Fu acting point and the center of the supporting shaft
9
is small, a very large lifting force Fu is required. In general, the unclamping member comprises a cam plate that moves towards the left and right in
FIGS. 14A and 14B
, and lifts the clamping member
7
by an inclined groove formed in the cam plate. However, since a large lifting force Fu is required, a large driving force is required to move the cam plate. Therefore, a large frictional force acts between the cam plate and the clamping member
7
, so that rattling and wearing at a sliding portion between the cam plate and the clamping member
7
tend to increase.
SUMMARY OF THE INVENTION
In order to overcome the above-described problems in a conventional device, it is an object of the present invention to provide a disc device, in which, even when a biasing member having a weak elastic force for applying a clamping force to a clamping member is used, a disc can be reliably clamped; in which, by a biasing force of the biasing member, distortion or wearing by driving does not easily occur in a mechanical component part; and in which a force required to unclamp the disc can be made small.
To this end, according to a basic form of the present invention, there is provided a disc device comprising a turntable for placing a center hole of a disc thereon, a clamper for clamping the disc along on the turntable, a clamping member including a clamping force acting portion for exerting upon the clamper a force for clamping the disc, a supporting portion for supporting the clamping member, and a clamping elastic member for producing a disc clamping moment having the supporting portion as a fulcrum with respect to the clamping member by action on the clamping member at a location separated from the supporting portion. In the disc device, the distance from the supporting portion to a biasing force acting portion upon which a biasing force of the clamping elastic portion acts is greater than the distance from the supporting portion to the clamping force acting portion.
In the present invention, by setting the positional relationship among the clamping portion supporting fulcrum of the supporting portion, the clamping force acting portion, and the biasing force acting portion as mentioned above, the clamping elastic member used may be one with a weak elastic force, so that it is possible to prevent a large localized force from acting on, for example, the clamping member.
When the structure of the basic form is used, the disc clamping moment may act directly on the clamping member from the clamping elastic member. Alternatively, when the structure of the basic form is used, the disc device may further comprise an intermediate member for being subjected to an elastic force from the clamping
Alpine Electronics Inc.
Brinks Hofer Gilson & Lione
Ometz David
LandOfFree
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