Toshiba DP120F, Service Manual

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DP120F/DP125F Mechanical Description 5-22 March 2000 © TOSHIBA TEC
(3) Exposure process
The organic photoconductor (OPC) drum consists of a carrier generation layer (CGL),
carrier transport layer (CTL) and under coat layer (UCL).
When the OPC drum has been irradiated by the laser beam from the LSU, an electrical
charge is generated on the CGL layer. The generated positive charge is transferred through
the CTL layer to the drum surface and is thus combined with the negative charge applied
at the electrostatic charge process. The negative charge is pulled down to the ground.
This results in the formation of an area with less electrical charge than an area that is
unexposed. This forms an electrostatic latent image which cannot be seen by the human
eye on the drum surface.
The characteristics of the OPC drum to generate a charge reacts to all light sources, not
only a laser beam, and controls the life of the drum.
Laser beam
CTL
CGL
Fig. 5-3-20
05-03-20
Fig. 5-3-21
05-03-21
Time (t)
Surface electric potential (v)
0
-500
Laser ON
Laser OFF
UCL