12
CX-958
4) Spindle Servo System
The spindle servo has the following modes.
1
Kick :
This mode is used for accelerating the disc rotation
during setup.
2
Offset :
(a) After the kick is over in the setup, this mode is
turned on until changing to rough servo mode.
(b) When focus is lost during play, this mode is
turned on until the focus is restored.
Both of the above are used for maintaining the disc
rotation rate near to the specified rate.
3
Applicable servo :
The CLV servo mode is turned on for the normal
operations.
In the EFM demodulation block, the frame sync
signal and internal counter output signal are
sampled for every WFCK/16 and a signal is produced
for indicating whether or not they are matching.
They are determined to be asynchronous only when
this signal fails to match 8 times in succession. In all
other cases, above two signals are assumed to be
synchronous. In the applicable servo mode, the
retracting servo is automatically selected if the two
signals are synchronous. If not, the regular servo is
automatically selected.
4
Brake :
This mode is turned on when stopping the spindle
motor.
The microcomputer outputs the brake voltage
through the servo LSI. The LSI monitors the EFM
waveform and, if its longest pattern exceeds a
certain interval (if the rotation is sufficiently slow),
the flag is set the LSI and the microcomputer turns
off the brake voltage. When the flag is not up within
a specified period time, the microcomputer switches
the mode from the brake to the stop mode, and
maintains this mode for a fixed period of time. If this
stop mode is continued for a fixed period of time,
the disc will be ejected.
5
Stop :
This mode is used for powering on the system and
the eject operation. When this mode is turned on,
voltage across the spindle motor is 0V.
6
Rough servo :
This mode is used for when the carriage feed
(carriage mode for the long search, etc.) is turned on.
The linear speed is calculated from the EFM
waveform and high or low level is entered to the
spindle equalizer. In the test mode, this mode is also
used for the grating check.
DSP
BLOCK
DIG.
EQ
MD
SOP
SOM
IC301
BA5985FM
SPINDLE
MOTOR
IC201 UPD63711GC
65
5
12
11
DAC
EFM
SIGNAL
M
SPEED ERROR SIGNAL
PHASE ERROR SIGNAL
Fig.18 : SPINDLE SERVO MOTOR BLOCK DIAGRAM
Summary of Contents for DEH-1350B
Page 6: ...4 DEH 2350 1350 2 2 EXTERIOR B A ...
Page 8: ...6 DEH 2350 1350 2 3 CD MECHANISM MODULE C D ...
Page 25: ...23 DEH 2350 1350 ...
Page 28: ...26 DEH 2350 1350 1 2 3 4 1 2 3 4 D C B A A 4 5 6 3 2 1 1 2 3 6 5 4 A TUNER AMP UNIT ...
Page 29: ...27 DEH 2350 1350 5 6 7 8 5 6 7 8 D C B A A 1 2 3 6 5 4 4 5 6 3 2 1 FRONT SIDE B ...
Page 31: ...29 DEH 2350 1350 1 2 3 4 1 2 3 4 D C B A B B CN601 A SIDE B KEYBOARD UNIT ...
Page 33: ...31 DEH 2350 1350 1 2 3 4 1 2 3 4 D C B A CLAMP SIDE B CONTROL UNIT C C ...
Page 40: ...38 DEH 2350 1350 Grating waveform Ech Xch 20mV div AC Fch Ych 20mV div AC 45 0 75 60 30 90 ...
