Gestetner A193 Service Manual page 57

COPY PROCESS
1. EXPOSURE
A xenon lamp exposes the original. Light reflected from the original passes to
the CCD, where it is converted into an analog data signal. The analog data is
converted to a digital signal, processed, and stored in the memory. At the
time of printing, the digital data is retrieved and sent to the laser diode. For
multi-copy runs, the original is scanned once only and stored to the memory.
2. DRUM CHARGE
In the dark, the charge roller gives a negative charge to the organic
photo-conductive (OPC) drum. The charge remains on the surface of the
drum because the OPC material has a high electrical resistance in the dark.
3. LASER EXPOSURE
The processed data scanned from the original is retrieved from the memory
and transferred to the drum by a laser beam, which forms an electrical latent
image on the drum surface. The amount of charge remaining as a latent
image on the drum depends on the laser beam intensity, which is controlled
by the BICU board.
4. DEVELOPMENT
The magnetic developer brush on the development rollers comes in contact
with the latent image on the drum surface. Toner particles are
electrostatically attracted to the areas of the drum surface where the laser
reduced the negative charge on the drum.
5. IMAGE TRANSFER
Paper is fed to the area between the drum surface and the transfer roller at
the proper time for aligning the copy paper and the developed image on the
drum surface. Then, the transfer roller applies a high positive charge to the
reverse side of paper. This positive charge produces an electrical force which
pulls the toner particles from the drum surface on to the paper. At the same
time, the paper is electrically attracted to the transfer roller.
6. PAPER SEPARATION
Paper separates from the drum as a result of the electrical attraction between
the paper and the transfer roller. The discharge brush helps separate the
paper from the drum.
7. CLEANING
The cleaning blade removes any toner remaining on the drum surface after
the image is transferred to the paper.
8. QUENCHING
The light from the quenching lamp electrically neutralizes the charge on the
drum surface.
(A193) 1-14 SM