Ricoh FT5540 Service Manual page 26

ERASE
The erase lamp illuminates the areas of the charged drum surface that will not be used for the
copy image. The resistance of the drum in the illuminated areas drops and the charge on
those areas dissipates.
DEVELOPMENT
Negatively charged toner is attracted to the positively charged areas of the drum, thus
developing the latent image. (The negative triboelectric charge is caused by friction between
the carrier and toner particles.)
PRE-TRANSFER LAMP (PTL)
The PTL illuminates the drum to remove all positive charge from the exposed areas of the
drum. This prevents the toner particles from being reattracted to the drum surface during
paper separation and makes paper separation easier.
IMAGE TRANSFER
Paper is fed to the drum surface at the proper time so as to align the copy paper and the
developed image on the drum surface. Then, a strong positive charge is applied to the back
side of the copy paper, providing an electrical force which pulls the toner particles from the
drum surface to the copy paper. At the same time, the copy paper is electrically attracted to
the drum surface.
PAPER SEPARATION
A strong ac corona discharge is applied to the back side of the copy paper, reducing the
positive charge on the copy paper and breaking the electrical attraction between the paper
and the drum. Then, the stiffness of the copy paper causes it to separate from the drum
surface. The pick-off pawls help to separate paper which has low stiffness.
PRE-CLEANING
The pre-cleaning corona (PCC) applies an ac corona with a negative bias to the drum. This
removes the positive charge from the drum and makes the negative charge on the toner
remaining on the drum even.
CLEANING
The cleaning brush removes most of the toner on the drum and loosens the remainder. Then,
the bias roller, which has a positive potential, attracts the toner particles from the cleaning
brush to keep it clean. Finally, the cleaning blade scrapes off the loosened toner.
QUENCHING
The pre-quenching corona applies a positive corona charge to the selenium drum to eliminate
any negative charge remaining from the pre-cleaning corona. Then, light from the quenching
lamp electrically neutralizes the drum.
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31 August 1989