Epson ColorPage EPL-C8000, Service Manual

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EPSON EPL-C8000 Rev. B
Chapter 2 OPERATING PRINCIPLES 2-4
2.1.3.2 (2) Exposure
In the exposure step, the system scans the drum surface (negatively
charged) with a laser beam and forms an invisible electrostatic latent
image on the drum surface.
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The printer controller outputs the data (image data) to the laser
beam unit. As determined by the data from the printer controller, the
laser beam unit emits a laser beam onto the drum surface, the area
of which is determined by data from the printer controller. (That is,
areas on the drum surface where the laser is emitted will be
developed with toner; areas on the drum surface where the laser is
not emitted will not be developed.)
The laser beam is emitted from the laser diode in the ROS
Assembly. The laser beam goes through the Scanner Assembly in
the ROS Assembly, the rotating polygon mirror, fixed mirror and
lens, and scans the drum surface from one end to the other in the
axis direction of the drum.
Figure 2-4. Lase beam emission
The laser beam irradiated on the drum surface generates electron-
hole pairs in the photoconductive layer. (Excited electrons create a
hole in the conductive band.) The electrons are attracted by the
electric field and move toward the inner conductor of the drum and
flow into it. The holes move toward the outside surface of the
photoconductive layer and recombine with the negative charges
(electrons) on the drum surface, thus decreasing the negative
charges on the surface. The resultant less negatively charged areas
on the drum surface forms an invisible electrostatic latent image
(printed image).
Figure 2-5. Exposure process