Ibt I - Epson AcuLaser C8500 Service Manual

EPSON AcuLaser C8500

2.5.8 IBT I

TRANSFER ASSY
The TRANSFER ASSY consists of the following parts.
1ST BTR
BACK UP ROLL
CONTACT ROLL
IBT DRIVE ROLL ASSY
TR0 SENSOR
IBT BELT ASSY
The 1ST BTR (First Bias Roll) is a conductive roll that sandwiches the IBT
BELT ASSY together with drum, and transfers the toner image on the drum
to the surface of the IBT BELT ASSY (primary transfer).
The CONTACT ROLL is metal roll of small diameter that makes contact
with the BACK UP ROLL, and supplies transfer voltage to the BACK UP
ROLL for secondary transfer.
The BACK UP ROLL is a conductive roll that sandwiches the IBT BELT
ASSY together with 2ND BTR from the inside, and induces a charge to the
2ND BTR for secondary transfer.
The IBT DRIVE ROLL ASSY transmits the drive of the PROCESS MOTOR
ASSY to the IBT BELT ASSY.
The positions of the each color toner image transferred must line up
accurately on the IBT BELT ASSY. A silver mark (TRO mark) is therefore
applied to the rear edge of the IBT BELT ASSY as a reference for transfer
position of toner images. The TRO SENSOR detects the transfer reference
mark once per cycle of the IBT BELT ASSY. A TRO signal (signal for
reference point for forming YMCBk image and transfer reference point)
when a certain amount of time elapses following a detection signal.
For B/W Mode (TRO-less mode), without using TRO signal, where the
DRUM and the DEVELOPER ASSY meet is the reference point and a print
control is conducted.
Operating Principles
The IBT BELT ASSY transfers a toner image of each color developed on
the drum to the IST BTR, forming a complete toner image of the 4
overlapped colors. When the 4-color toner image is formed, a supply of
negative voltage is received from the BACK UP ROLL, and a complete
toner image consisting of 4 colors is transferred (secondary transfer) to
paper.
Figure 2-40. IBT I
Revision C
2-34