Dynamic information storage or retrieval – Information location or remote operator actuated control – Selective addressing of storage medium
Reexamination Certificate
2000-05-04
2002-06-25
Neyzari, Ali (Department: 2653)
Dynamic information storage or retrieval
Information location or remote operator actuated control
Selective addressing of storage medium
C369S044280, C388S821000, C318S375000
Reexamination Certificate
active
06411572
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a device for measuring parameters of a sled mechanism of an optical disc drive.
2. Description of the Related Art
An optical disc drive for driving an optical disc, such as a compact disc (CD), a CD-ROM or a DVD, includes an optical pickup, referred to below as OP, and an electrical controller for controlling the movement of an objective lens provided in the OP, and is configured for correctly illuminating the laser light emitted from the OP on a track on the optical disc. With such OP, since it is necessary to set mechanical and electro-optical parameters required for stable tracking and track jump under many different conditions, a lot of time and labor are required in newly studying and testing an OP.
It is therefore contemplated to effect computer simulation for an OP to study and test the OP.
For such computer simulation for an OP, parameters of a sled mechanism for causing radial movement of a main body unit of the OP along the radius of the optical disc are required.
Such sled mechanism generally includes a shaft provided radially of the optical disc, a sled motor for driving the OP provided on the shaft and plural gears for transmitting the sled motor rotation to the OP.
However, it is extremely difficult to find a motor constant Km, a viscosity coefficient &ggr; and a Coulomb friction F
c
in the sled mechanism, such that these parameters cannot be reflected in the Op simulation. The result is that the Op simulation on the computer cannot be accurate.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and apparatus for finding a motor constant Km, a viscosity coefficient &ggr; and a Coulomb friction F
c
in a sled mechanism for an optical disc drive.
In one aspect, the present invention provides a parameter measurement device for a sled mechanism of an optical disc drive including means for detecting the back-electromotive force of a sled motor, means for detecting the velocity of the movement velocity of an optical pickup, means for causing movement of the optical pickup and means for calculating a motor constant of the sled mechanism based on the back-electromotive force of the sled motor and on the movement velocity of the optical pickup when the movement means causes the movement of the optical pickup.
In the present parameter measurement device for a sled mechanism, the calculating means finds the motor constant Km based on E
b
=K
m
R
m
v
0
, where E
b
is the back-electromotive force of the sled motor when the movement means causes the movement of the optical pickup, v
0
is the movement velocity of the optical pickup when the movement means causes the movement of the optical pickup and Rm is the resistance of the sled motor.
In another aspect, the present invention provides a parameter measurement device for a sled mechanism of an optical disc drive including means for supplying a rectangular electrical voltage of a voltage magnitude V
m
and the time t
1
to a sled motor, means for detecting the maximum velocity v
0
of the pickup when the rectangular electrical voltage is supplied to the sled motor, the deceleration time t
3
of the optical pickup, and the distance x
3
traversed by the optical pickup during deceleration thereof, and means for calculating the viscous coefficient and/or the Coulomb coefficient of the sled mechanism of the optical disc drive based on the voltage magnitude V
m
, the above time t
1
, maximum velocity of the pickup v
0
, deceleration time t
3
of the optical pickup, the distance x
3
traversed by the optical pickup during deceleration thereof and the motor constant Km.
In the present parameter measurement device for the sled mechanism, &ggr;′ and F′
c
are found using
F′c
=2
&ggr;′v
0
/[exp(−2
&ggr;′t
3
)−1] (A)
and
F′
c
=(
v
0
−2
x
3
&ggr;′)/
t
3
(B)
while the mass m of the sled mechanism in its entirety is found using
m=K
m
/[(
v
0
/t
1
+F′c+&ggr;′v
0
)/(
V
m
−K
m
R
m
v
0
/2)] (C)
and the mass m, &ggr;′ and F′c thus found are substituted into
F
c
=mF′
c
(D)
and
&ggr;=
m&ggr;′
(E)
to find the viscosity coefficient &ggr; and the Coulomb friction Fc.
In still another aspect, the present invention provides a method for detecting parameters in a sled mechanism of an optical disc drive, including causing movement of an optical pickup, detecting the back-electromotive force of a sled motor and the movement velocity of the optical pickup on causing movement of the optical pickup, and finding the motor constant of the sled mechanism based on the detected back-electromotive force of the sled motor and the detected movement velocity of the optical pickup.
In the present method, the motor constant K
m
of a sled motor is found based on E
b
=K
m
R
m
v
0
, where E
b
is the back-electromotive force of the led motor on causing movement of the optical pickup, v
0
is the movement velocity of the optical pickup on causing movement of the optical pickup, and Rm is the resistance of the sled motor.
In yet another aspect, the present invention provides a method for detecting parameters in a sled mechanism of an optical disc drive including the steps of supplying a rectangular electrical voltage of a voltage magnitude V
m
and the time t
1
to a sled motor, detecting the maximum velocity v
0
of the pickup when the rectangular electrical voltage is supplied to the sled motor, the deceleration time t
3
of the optical pickup, and the distance x
3
traversed by the optical pickup during deceleration thereof; and calculating the viscous coefficient and/or the Coulomb coefficient of the sled mechanism based on the voltage magnitude V
m
, the above time t
1
, maximum velocity of the pickup v
0
, deceleration time t
3
of the optical pickup, the distance x
3
traversed by the optical pickup during deceleration thereof and the motor constant K
m
.
In the present method, &ggr;′ and F′c are found using
F′c=2
&ggr;′v
0
/[exp(−2
&ggr;′t
3
)−1] (A)
and
F′c
=(
v
0
−2
x
3
&ggr;′)/
t
3
(B)
while the mass m of the sled mechanism in its entirety is found using
m=K
m
/[(
v
0
/t
1
+F′c+&ggr;′v
0
)/(
V
m
−K
m
R
m
v
0
/2)] (C)
and the mass m, &ggr;′ and F′c thus found are substituted into
Fc=mF′c
(D)
and
&ggr;=
m&ggr;′
(E)
to find the viscosity coefficient &ggr; and the Coulomb friction Fc.
With the parameter measurement method and device of the present invention, the motor constant Km, viscous coefficient &ggr; and the Coulomb friction Fc in the sled mechanism of the optical disc drive can be measured accurately.
REFERENCES:
patent: 4510423 (1985-04-01), Iwasawa
patent: 5729399 (1998-03-01), Albrecht et al.
patent: 5757747 (1998-05-01), Shimada
patent: 5818184 (1998-10-01), Kim
patent: 6011902 (2000-01-01), Yamamoto
patent: 0 408 392 (1991-01-01), None
patent: 0 650 160 (1995-04-01), None
Frommer William S.
Frommer & Lawrence & Haug LLP
Neyzari Ali
Polito Bruno
Sony Precision Engineering Center (Singapore) PTE Ltd.
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