3: Operation
3-52
Colorwriter LSR 2000 Printer
Service Guide
The between-colors bias, with a voltage value smaller than that of
the print bias, is applied between colors to minimize the damage of
the photosensitive drum.
When the drum motor begins to rotate, the high-voltage control IC
(IC1003) on the high-voltage power supply PCB is charged with
transfer bias by setting the transfer voltage drive signal (/HVTR) to
“L.” At the same time, the print bias and between-colors bias for
each color are applied by varying the /TRPWM signal.
Generation of voltage applied to the attraction roller
For full-color transfer, the high-voltage control IC (IC1003) on the
high-voltage power supply PCB applies attraction voltage to the
attraction roller by setting the attraction voltage drive signal
(/HVATR) to “L” before transference of the first color image. Also,
an appropriate attraction bias is applied by varying the attraction
bias value control signal (/ATRPWM) according to the
environment detected by the environment change correction
control (see “Environment-change correction control” on
page 3-69). After the attraction roller contacts the transfer drum for
a specified period of time, /HVATR signal is set to “H,” and the
attraction bias to OFF.
Generation of voltage applied to the discharge roller
When the paper is separated, the high-voltage control IC (IC1003)
on the high-voltage power supply PCB applies the discharge bias,
which is output in response to the combination of the discharge bias
(AC) SELECT signals (/HVSEAC0, /HVSEAC1), to the discharge
roller in order to discharge the transfer drum surface.
The discharge bias changes the combination of the /HVSEAC0 and
/HVSEAC1 signals according to the environment change correction
control (see “Environment-change correction control” on
page 3-69) to switch the discharge bias value.
/HVSEAC0
/HVSEAC1
OFF
H
H
Discharge bias: low
L
H
Discharge bias: middle
H
L
Discharge bias: high
L
L