CX-890
4) Spindle servo system
The spindle servo has the following modes:
IC 201 UPD63702AGF
(1)Kick mode:To be used for accelerating disc rotationIC301
SPEED AND
BA5986FM
during setting.PHASE ERROR SIGNAL
MDY MDX
(2)Offset mode:
EFMDSPDIGITAL
a)To be used after completion of kick until comple69DAC 6124BLOCKEQUALIZERR206
SIN1001
tion of spindle lock during setting. 22
R308
b)If focus is out of range during playback, this mode
10kW23
is used until focus is recovered. In both cases, R307
10kWDRIVER
Offset mode is used for maintaining disc rotation
to the speed close to specified rotation.
(3)Adaptive Servo mode: CLV servo mode during nor-Fig. 17 Spindle servo block diagram
mal operation. The system samples every WFCK in
16 cycles whether frame synchronous signal match-
es output from the internal frame counter in EFM
demodulation block, and generates signal that
shows matching/unmatching status. If signal show-
ing unmatching status continues for 8 times, the sys-
tem deems it as asynchronous status. Except this
case, the system judges as synchronous. In Adaptive
Servo mode, the system automatically selects with-
drawal servo for asynchronous status, and steady-
state servo for synchronous status.
(4)Brake mode: Mode to stop the spindle motor.
The microcomputer outputs brake voltage from the
servo LSI. Waveforms of EFM are monitored inside
the LSI. If the longest pattern of EFM exceeds speci-
fied intervals (if the rotation speed adequately
slowed down), flag is activated in the LSI, and the
microcomputer turns brake voltage to OFF. If no flag
is activated after a specified time, the microcomput-
er changes from Brake to Stop mode. This status
continues for a specified time. If the system changes
to Stop mode during ejection, disc is ejected after
the specified time mentioned above.
(5)Stop mode: To be used when the power is turned to
ON, and during ejection. In Stop mode, the end-to-
end voltage of the spindle motor is 0 V.
(6)Rough Servo mode: To be used when returning car-
riage (carriage move during long search, etc.). The
system calculates linear speed from waveforms of
EFM, and inputs either "H" or "L" level to the spindle
equalizer. This mode is also used for confirmation of
grating in Test mode.
12 |
ACEC
