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1
1.2.4 Spindle servo system
In the spindle servo system, the following seven modes are available:
A
1) Kick
Used to accelerate the disc rotation in the setting-up mode.
2) Offset
a. Used in the setting-up mode until the AGC completes after the kick mode.
b. Used when the focus loop is unlocked during the play mode and until it is locked again.
In both cases, the mode is to keep the disc rotation near to the appropriate one.
3) Applicable servo
In the normal operation, the CLV servo mode is used.
The EFM demodulation block detects through WFCK/16 sampling whether or not the frame sync signal and the inter-
B
nal frame counter output are synchronized, and generates the status signal based on the sampling result, synchro-
nized or non-synchronized. If eight consecutive "non-sync" signals are obtained, the system senses the status as "non-
sync". If not, the system senses as "sync". In the applicable servo mode, the leading-in servo mode is automatically
selected at the non-sync status, and the normal servo mode is at the sync status.
4) Brake
Used to stop the spindle motor.
In accordance with the microcomputer's command, the brake voltage is sent out from the servo LSI. At this moment,
the EFM waveform is being monitored in this LSI. When the longest EFM pattern exceeds a certain cycle (or the rota-
tion slows down enough), a flag is set inside the LSI, and the microcomputer switches off the brake voltage. If a flag is
not set within a certain period, the microcomputer shifts the mode from the brake mode to the stop mode, and keeps
C
this for a certain period. In the eject mode, after the mode is shifted to the stop mode and a certain period passes, the
loaded disc is ejected.
5) Stop
Used when the power is turned on and during the eject mode. At this moment, the voltage through the spindle motor
is 0V.
6) Rough servo
Used when the carriage is moved (or in the carriage move mode such as long search).
By obtaining the linear velocity from the EFM waveform, "H" or "L" is applied to the spindle equalizer. In the test
mode, this mode is used for grating confirmation.
D
7) Rotation speed
CD-DA and CD-ROM are controlled differently at their rotation speeds. Both of them are done by the double speed in
the setting-up mode when a disc gets inserted. However, CD-DA is done by the standard speed in the setting-up mode
starting from SOURCE ON/ACC ON with the disc inside, while CD-ROM is still done by the double speed. During the
play mode, the rotation speed of CD-DA is always the standard speed, while that of CD-ROM is always the double
speed.
UPD63760GJ
E
EFM
SIGNAL
F
Fig.1.2.9 Block diagram of the spindle servo system
12
1
2
SPEED ERROR SIGNAL
DSP
DIG.
PWM
BLOCK
EQ
PHASE ERROR SIGNAL
CX-3057
2
3
BA5996FM
16 SOP
108
MD
26
SOM
15
3
4
M
SPINDLE
MOTOR
4
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