Laserdiode Drive - Epson ActionLaser 1300 EPL-3000 Service Manual

2.1.2.5 Laser Drive
Diode
Laser diode emission is controlled by three signals (LDATA, LDVR1 and LDVR2) sent from the
main board a 1 simal (LDLVL) from the laser diode drive board (PWB-D). The photo diode
(sensor) is located i~side-the laser diode. This sensor measures the laser power.
-LDATA
Controller
LD VR1
Board
LD VR2
LD LVL
Signal
This signal is the laser otioff signal. When it is "L", the laser is allowed to emit;
when it is "H", the laser is stopped emitting.
and
This signal adjusts the laser drive current so that the laser emission becomes
the regulated value (rough adjustment).
This signal adjusts the laser drive current so that the laser emission becomes
the regulated value (fine adjustment).
This signal indicates whether the laser drive current has reached the regulated
value. The signal "H" shows that the current has reached the regulated value
and the signal "L" shows that the current has not yet.
This signal is returned from the PWB-D to the main board. This is the signal to
the SOS sensor and is the main scanning direction synchronization signal. The
main board is timed with this signal and sends the LDATA signal to the PWB-D.
Rev. A
Laser Diode
Drive Board
Figure 2-22. Laser Diode Drive Circuit
Table 2-2. Laser Diode Control Circuit
Laser Diode
SOS Sensor
Description
Operating Principles
Laser
Diode
Photo
Diode
SOS Mirror
2-15