Sharp AL-1611 Service Manual page 23

(2) Exposure
A Laser beam is generated from the semiconductor laser and controlled
by the print pattern signal. The laser writes onto the OPC drum surface
through the polygon mirrors and lens. The resistance of the OPC layer
decreases for an area exposed by the laser beam (corresponding to the
print pattern signal). The beam neutralizes the negative charge. An
electrostatic latent image is formed on the drum surface.
Semiconductor laser
Exposure
(semiconductor laser)
Drum surface charge
sfter the exposure
Non-image area
(3) Developing (DC bias)
A bias potential is applied to the MG roller in the two component mag-
netic brush developing method, and the toner is charged negative
through friction with the carrier. Non-image area of the drum surface
charged with negative potential repel the toner, whereas the laser
exposed portions where no negative charges exist, attract the toner. As
a result, a visible image appears on the drum surface.
: Carrier (Magnetized particle)
: Toner (Charge negative by friction)
(N) (S) : Pemanent magnet
(provided in three locations)
N
N
MG roller
DC
-400v -8V
OPC layer
Pigment
layer
Aluminum
layer
OPC layer
Pigment
layer
Aluminum
layer
Image area
S
AL-1611/AL-1622 OPERATIONAL DESCRIPTIONS
Non-image area
-600
-400
Developing bias
Image area
Residual potential (-50 to -100V)
0
Charge Exposure
Toner is attracted over the shadowed area because of the developing
bias.
(4) Transfer
The visible image on the drum surface is transferred onto the print
paper by applying a positive charge from the transfer corona to the
backside of the print paper.
(5) Separation
Since the print paper is charged positively by the transfer corona, it is
discharged by the separation corona. The separation corona is con-
nected to ground.
(6) Cleaning
Toner remaining on the drum is removed and collected by the cleaning
blade. It is transported to the waste toner collecting section in the clean-
ing unit by the waste toner transport roller.
6 – 4
Toner attract
potential
Charge
Developing Transfer
Discharge
Time