Exposure Process - Epson EPL-5900 Service Manual

EPSON EPL-5900/EPL-5900L

2.2.4 Exposure Process

The laser beam from the print head creates an electrostatic latent image on the OPC drum
surface.
The following control is performed in order to find the appropriate timing to print the
image.
SUB SCANNING DIRECTION (VERTICAL SCANNING DIRECTION)
When the printer receives the PRINT signal, the polygon motor (M3) and the main motor
(M1) operate, and paper feeding is started.
Upon passage of a specified period of time after the front end of the fed sheet turns the
paper feed sensor ON (TOD signal), the main control board sends the VIDEO signal to the
print head, and printing starts.
When moving on from the first line to the second line, the print starting position is shifted
down by delaying the VIDEO signal sending time
MAIN SCANNING DIRECTION (HORIZONTAL SCANNING DIRECTION)
The laser diode control board (PWB-D) is equipped with the SOS sensor to unify the timing
of the laser emission for every one line of main scanning.
PRINTABLE AREA
The main control board sends the VIDEO signal corresponding to the paper size to the
engine (controller).
The main control board determines the printing start position by TOD signal (sub scanning
direction) and the HSYNC signal, which are sent from the engine (controller).
Upon receiving the VIDEO signal, the print head starts laser emission.
Operating Principles
Print Head Unit
Polygon Motor
(M3)
Description of Mechanisms
Laser Diode
Figure 2-12. Exposure Control
Printable Area
Figure 2-13. Printable Area
Revision B
OPC Drum
SOS (Start of Scan)
Sensor (PWB-D)
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