26
A/D
111
A/D
113
Parallel
digital
compensator
Sled
Compensator
Controlled by
prediction and
lens shift quantity.
Quantity of
Lens shift
D/A
PWM
PWM
A/D
3.3V
TD
TRS
SIN1
SIN2
120
55
116
66
67
IC201
(Drive IC)
(Drive IC)
Lens control
To control
stepping motor
IC301
IC301
TE
RFDiF
(LNSC)
3-6. TRACKING SERVO SYSTEM
Tracking servo system
Tracking servo is used to follow trace center of detector with TE signal and to control stepping motor.
Tracking servo make lens into center of detector using RFDiF(LNCS) signal.
TE signal is sampled by A/D converter during sequential read and do gain compensation, phase compensation
in parallel digital compensator.
This signal is changed to analog signal in D/A converter and feed into Drive IC301 from IC201 120 pin and
operate tracking actuator.
Control of stepping motor(sled motor) is decided by disk and rotation speed,and control signal output is obtained
by IC201 66 and 67 pin.
If large lens shift,detected lens shift quantity by IC201 pin116 and compensated by u-com.
During long seek,LNSC is converted by A/D and compensated.
Therefore servo is applied good and controlled detector
¡fl
s center.
