Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specified detail of transducer assembly support structure
Reexamination Certificate
1999-05-06
2004-02-10
Young, W. R. (Department: 2655)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specified detail of transducer assembly support structure
C369S263100, C369S044140
Reexamination Certificate
active
06690638
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a supporting mechanism for an optical disc driving device.
In an optical disc player, there is a limit to ability to accurately control the trucking servo and focusing servo against the external vibration applied from the outside and the internal vibration. In particular, in the case of the computer disc player, the vibration generated inside the player at high speed reading becomes problem.
FIG. 9
shows a device for damping the external vibration. As shown in the drawing, a main frame
4
is mounted on a box
1
by three elastic members
2
at corners. On the main frame
4
, a turntable
6
and a spindle motor (not shown) for rotating the turntable are provided.
A pickup
5
for reading information recorded in a disc is slidably mounted on a pair of guide rails
11
a
and
11
b
. The pickup engages with a driving screw
8
so as to be moved in a radial direction of a disc loaded on the turntable
6
. The driving screw
8
is connected to a rotating shaft of a stepping motor
9
so that the pickup
5
is moved along the guide rails
11
a
and
11
b
by the rotation of the driving screw
8
.
In operation, the main frame
4
including various members mounted therein are vibrated by imbalance of the disc and others when the disc is rotated by the spindle motor. In particular, at high speed reading of information, the rotating speed of the disc is increased, and hence the vibration is accordingly increased.
Since the main frame
4
is mounted in the box
1
through the elastic members
2
, the vibration transmitted from the main frame
4
to the box
1
is reduced. The external vibration transmitted to the box
1
is damped by the elastic members
2
. Therefore, the quantity of vibration transmitted to the main frame
4
is reduced.
FIG. 10
shows a vibration model of the structure shown in
FIG. 9
, where the elastic member
2
has a stiffness of k and a coefficient of loss (viscosity) of &mgr;, and a main frame device
20
has a mass of m.
There is a following relationship if external force is F and displacement of the main frame device is x,
md
2
x/dt
2
=F−&mgr;dx/dt−kx
If the equation of motion is solved under a condition, the relationship between the resonance frequency f
0
and the mass m can be obtained. The resonance frequency can be expressed as follows.
f
0
=1/(2&pgr;)*(
k/m
)1/2
The ratio of the resonance frequency f
1
for the box
1
of mass m
1
to the resonance frequency f
0
for the main frame device
20
of mass m
0
is follows.
f
0
/f
1
=(
m
1
/m
1
)1/2
If the mass m
0
is multiplied by 2, the resonance frequency f
1
becomes about 0.7f
1
.
Thus, the transmissibility can be expressed by the mass and the stiffness and the coefficient of loss of the elastic member. It is possible to obtain a desired transmissibility by selecting the mass, stiffness and coefficient of loss.
From the foregoing, it will be understood that in order to interrupt the transmittance of the external vibration to the main frame device
20
, it is effective to reduce the stiffness of the elastic member
2
and to increase the mass of the main frame device supported by the elastic member
2
.
However, it is desirable to reduce the size of the device. Since it is difficult to increase the mass of the main frame device
20
, the stiffness of the elastic member
2
is reduced heretofore.
Thus, the external vibration can be damped.
However, the own vibration of the main frame
4
caused by the imbalance of the disc and others can not be damped since the stiffness of elastic member is reduced.
If the main frame vibrates, the pickup
5
mounted in the main frame
4
through guide rails
11
a
and
11
b
is vibrated. If the pickup vibrates, the servo operation for controlling the information reading operation may be disturbed. As a result, the information can not be accurately read out.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a device which may damp an internal vibration caused by operation of driving mechanisms in the device.
According to the present invention, there is provided a supporting mechanism for an optical disc driving device, comprising, a box, a main frame provided in the box, first elastic members elastically connecting the main frame to the box, an optical disc driving device mounted on the main frame, the optical disc driving device including a spindle motor and a turntable securely mounted on a rotating shaft of the spindle motor, a sub-frame, and second elastic members elastically connecting the sub-frame to the main frame.
REFERENCES:
patent: 4703470 (1987-10-01), Castagna et al.
patent: 5732063 (1998-03-01), Chen
patent: 5933407 (1999-08-01), Watanabe et al.
patent: 6034941 (2000-03-01), Ro
patent: 6125097 (2000-09-01), Wu
patent: 63-298795 (1988-12-01), None
Hoshinaka Eiji
Ishii Katsumi
Kiyomiya Masaaki
Takagi Keiichi
Arent Fox Kintner & Plotkin & Kahn, PLLC
Pioneer Electric Corporation
Young W. R.
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