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5
4) Spindle servo system
There are following modes for spindle servo.
1 Simple FG servo:
It is for maintaining the rotation of a disc to be in closer
condition of regular rotation.
The microcomputer monitors FG signal output pulse
according to the rotation of a spindle motor and controls
the drive voltage of the spindle motor.
This is used in following situation.
a) At set-up time, it is used during transition from power
ON with focus-close to rough servo.
b) It is used until recovering from out-of-focus during
playing.
2 Adaptation servo:
It is CLV servo mode of normal operation.
It takes a sample of WFCK/16 at EFM demodulation
block to check whether frame synchronized signal and
internal frame counter output agree, then generates
signal showing "agree" or "disagree". When this signal
shows "disagree" 8 times continuously, it is considered
as asynchronous and otherwise, it is considered as
synchronous. This adaptation servo selects lead-in servo
in asynchronous, and regular servo in synchronous
automatically.
3 Brake:
It is a mode for stopping a spindle motor. The
microcomputer monitors FG pulse and applies the brake
fully to certain interval (speed) and decreases the brake
level and stops it when the speed is under that.
IC201 UPD63763AGJ,UPD63761AGJ
SPEED ERROR SIGNAL
EFM
DSP
DIG.
BLOCK
EQ
SIGNAL
PHASE ERROR SIGNAL
5
6
C307
0.01µ
R320
33K
MD
DAC
107
27
R322
18K
IC302
BD7962FM
Fig.13 Spindle servo block diagram
6
7
4 Stop:
It is a mode used at the time of POWER ON and eject.
Both ends of voltage of a spindle motor is 0V at this time.
5 Rough servo:
It is a mode used at the time of carriage feed (carriage
move of long search, etc.).
It inputs which one of H level or L level to a spindle
equalizer after calculating line speed according to EFM
waveform.
Also this mode is to confirm the grating in test mode.
IC301
BA6859AFP
26
20
EC
A3
4
19
A2
5
ECR
6
SPCONT
21
A1
FG
22
CX-3168
7
SPINDLE
M
MOTOR
8
A
B
C
D
E
F
11
8
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