CX-3168
10
1
2
3
4
1
2
3
4
C
D
F
A
B
E
COM
COP
IC302
BD7962FM
CARRIAGE
MOTOR
19
20
M
R321
27K
R319
39K
C306
4R7P
33
32
3) Carriage servo system
DIG.
EQ
SD
IC201 UPD63763AGJ,UPD63761AGJ
105
KICK, BRAKE
REGISTERS
DAC
CONTROL
FROM
TRACK. EQ
DRIVE ON/OFF THRESHOLD
Carriage is moved by these points.
TRACKING DRIVE
(LOW FREQUENCY)
LENS POSITION
CRG DRIVE
(INSIDE UPD63711GC)
CRG MOTOR VOLTAGE
Fig.11 Carriage servo block diagramFig 16: Carriage servo block diagram
Fig.12 Carriage signal waveform
The carriage servo is input the output from low frequency
number composite of tracking equalizer (position
information of lens) to carriage equalizer, and after
acquiring fixed gain, it outputs drive signal from LSI. The
signal is impressed to carriage motor via driver IC.
To be more precise, since it is necessary to move the
entire pick-up to forward direction when lens off-set during
playing reaches to certain level, the gain of equalizer is
set to generate higher voltage than start-up voltage of
carriage motor at that time. In addition, actual operation is
set to fix a certain threshold for equalizer output inside
servo LSI, and to output the drive voltage only when the
level of equalizer output is over that fixed level. In that
way, power consumption is reduced. Moreover, according
to decentering of a disc, the level of equalizer output
voltage may cross threshold level several times before the
entire pick-up starts to move. At that time, output
waveform of drive voltage from LSI is pulse state.