Xerox Phaser 7500 Service Manual page 68

Theory of Operation
2-8
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.
Drum
LPH
Drum Concept
LED On
Photoconductor
Conductor
Photoconductor
Negative Charge
Conductor
Positive Charge
Electrostatic
Latent Image
Phaser 7500 Printer Service Manual
Drum Surface
(LED On)
Electrostatic
Latent Image
Drum Surface Potential
(LED On)
-V
0
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