Image Transfer - Ricoh FT7770 Service Manual

30
April, '89
TRANSFER AND SEPARATION
1. PTC (Pre-Transfer Corona) and PTL (Pre-Transfer Lamp)
The
high speed of
transfer.
The PTC and the PTL help to achieve this goal by reducing the
attraction between the toner and drum before the image transfer process
The PTC applies a negative dc charge
charge increases the negative
transfer to paper.
makes paper separation easier. The PTL also makes paper separation easier by
illuminating the drum and removing positive charge.

Image Transfer

2.
The registration rollers feed the copy paper through the transfer entrance
guides to the transfer section. There, the transfer corona wire applies posi-
tive ions to the back side of the copy paper to attract the negatively
charged toner image away from the drum and onto the paper.
If the copy paper is damp, a part of the transfer corona charge may leak to
the machine frame or across the paper to the drum because of the reduced
electrical resistance of the damp paper. This reduces the transfer of toner,
and a light or patchy image results.
this
machine's copy
potential of the
ac
The charge removes positive charge from the drum and
process requires a quick image
and an ac charge to the drum.
toner to improve
2-42
The dc
t o n e r