Sharp AL-1611 Service Manual page 22

Operation cycle
Paper exit roller
Paper exit
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B. Outline of print process
The printer section of this machine employs the laser print system
where print images are formed by the laser beams on the OPC drum.
A high voltage (corona) is applied from the main charger to the OPC
drum to charge the OPC drum.
Laser beams are radiated to the charged OPC drum to form electrical
images on the OPC drum. (Exposure)
(At that time, the print image on the OPC drum cannot be seen: latent
electrostatic image)
By the potential difference between the unexposed area and the latent
electrostatic images, toner ia attracted only to the images. (Developing)
(At that time, the print image formed by toner on the OPC drum can be
seen. Visible images)
The toner image on the OPC drum is transferred on the print paper by
the transfer corona (voltage).
After that, the print paper with the toner image on it is subject to heat
and pressure in the fusing section to fuse the image on the paper.
This machine employs the following organic photoconductor (OPC)
drum.
An OPC drum is used for the photoconductor.
(Structure of the OPC drum layers)
eat roller
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a te to er ox
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OPC layer
(20microns thick)
Pigment layer (0.2
to 0.3 microns thick)
Aluminium drum
AL-1611/AL-1622 OPERATIONAL DESCRIPTIONS
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ra er
y ro izatio
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a ette paper
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C. Actual print process
(1) Charging
A high voltage is applied to the main charger, and negative charges are
discharged to the OPC drum. A screen grid is provided between the
main charger and the OPC drum, and negative charges are uniformly
charged on the OPC drum surface.
Positive charges are attracted by the negative electrode on the OPC
drum surface and excited in the aluminum layer in the OPC drum.
DC5.5KV
6 – 3
ar er
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ra er ar er i olta e po er
e i t roller
a al paper
ee
(-525V/-400V)