Panasonic UF-580 Service Manual page 216

6.2.12 Laser Unit (LSU) Control Circuit
The laser control signals are described below.
nLDEN
The LSU is activated when this output signal is LOW. If an error occurs, the nLDEN output signal level
goes High and the LSU is deactivated.
nVIDEO
This is the actual Data Signal. The Laser is ON when the nVIDEO output signal level is LOW.
nHSYNC
This horizontal synchronization signal transmitted from the Beam Detection Sensor sets the horizontal
position of the laser beam as it crosses the OPC Drum.
nSTART
This is the Scanner Motor Control Signal. The Scanner Motor rotates when the nSTART output signal
level is LOW.
nREADY
A Phased-Lock Loop (PLL) circuit keeps the Scanner Motor speed constant when the nREADY is at a
Low output signal level.
CLK
This is the Scanner Motor Clock.
nS/H
This is the Sample Hold Signal in order to adjust the Laser power. When the Laser switches on compul-
sorily, the Laser Power is adjusted to a suitable level and held until the next duty cycle in order to keep
the Laser Power stable.
IC3
SHINE
Q24
20
2 3
1
IC34
19
4
2
+5V
+5V
R181
24
163
4 2
R328
IC35
23
30
21
2
GND
SC PCB
Laser Unit Control Circuit Block Diagram
CN68
nS/H
1
nVIDEO
6
nLDON
Q23
5
2
3
1
2 nHSYNC
3
nPMON
Q21
3
2
1
2 nPMRY
R326
1
nPMCK
3
CN69
Q22
1
216
Laser
Drive
Laser
Circuit
Timing
Sensor
Scanner
Motor
Drive
Circuit
Scanner
Motor
LSU