2-8 Phaser 7500 Printer Service Manual
Theory of Operation
The LEDs are lit in one line units based on the print data (image data) that is
sent from the printer controller.
The lenses then focus the light onto the Drum surface. The LED is only lit for
the parts where the one line is made up of pixels (small dots that form
characters or images). When parts of the Drum surface are exposed, they
become conductive and the negative charges flow towards the positive side to
cancel out the positive charges, reducing the potential on the Drum surface.
These sections with lowered surface potential form the electrostatic latent
image.
Photoconductor
Conductor
Negative Charge
Positive Charge
Drum
LPH
Drum Concept
LED On
(LED On)
(LED On)
Electrostatic
Latent Image
Electrostatic
Latent Image
Drum Surface Potential
Drum Surface
-V
0
s7500-343
Photoconductor
Conductor
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