Laserdiode Drive; Figure 2-23. Laser Diode Drive Circuit; Figure 2-24. /L Data Generation Circuit - Epson H5200 - TM B/W Thermal Line Service Manual

Operating Principles
Laser Diode Drive
2.1.2.5
Figure 2-23 shows the laser diode
DATA, DA1, and
(L
S SCAN <
co ~
DAI
L DATA
Engine Controller
Board (PWB-A)
The L DATA signal is the laser ON/OFF signal. When it is LOW, the laser emits, and when it is
HIGH, laser stops emitting. L DATA is the combination of the two signals in the figure below. If
the VIDEO or the FORCED LASER DIODE ON signal is activated (LOW), the
L DATA signal will be active. The VIDEO signal is an image signal sent from the video controller
board (C108 MAIN board). The FORCED LASER DIODE ON signal is a laser emission signal to
apply the laser beam to the SOS sensor.
from the Video Controller
Board (C108 MAIN Board)

Figure 2-24. /L DATA Generation Circuit

The laser diode is forcibly activated within between 0.2 seconds and 0.1 seconds after the scanner
mirror motor (M2) turns ON. At this time, laser emission power is adjusted. LDVR1 and LDVR2
are the laser emission power adjust signals; they are analog signals. LDVR1 is a tuning. LDVR2 is a
fine tuning.
LDATA
(CN5A-7)
(CN5A-1O)
LDLVL
(CN5A-11)
drive circuit. Laser diode emission is controlled by three signals
from the engine controller board

Figure 2-23. Laser Diode Drive Circuit

Forced Laser Diode ON
k 0.1 ,!,
: : ::
I
: :
:
: : ;
: : :
Laser Diode
LD
Sos
SOS sensor
0.2
I