3: Operation
Colorwriter LSR 2000 Printer
Service Guide
3-47
Generation of voltage applied to the primary charging
roller
The high-voltage control IC (IC 1003) on the high-voltage power
supply PCB outputs the primary charging dc voltage drive signal
(/HV1DC1), primary charging ac voltage drive signal (/HV1AC1),
primary charging dc voltage select signal (/HV1DC0), primary
charging ac voltage select signal (/HV1AC0), and density
adjustment signal (for primary charging voltage) (/HV1PWM) to
control the high-voltage power supply.
The /HV1DC1 signal and /HV1AC1 signal turn the primary
charging voltage (DC, AC) ON or OFF. The /HV1DC0 signal
selects the printing bias or the between-colors bias/between-pages
bias.
The /HV1AC0 signal alters the primary charging voltage AC
current value according to the environment detected by the
environment change correction control (see “Environment-change
correction control” on page 3-69). The output value of the
/HV1PWM signal remains constant.
For the initial rotations, IC1003 sets the /HV1DC1 signal to “L”
and the /HV1DC0 signal to “L” to apply between-colors
bias/between-pages bias to the primary charging roller. Then, the
/HV1DC1 signal goes “L” and the /HV1AC1 signal goes “H” so
that the primary charging roller is charged with the print bias with
the primary charging voltage AC bias and DC bias superimposed.
For between-colors/between-pages, the /HV1AC1 signal is set to
“H” and only the DC bias is applied while the AC bias is turned
OFF.
/HV1DC0
/HV1DC1
/HV1AC0
/HV1AC1
OFF
—
H
—
H
Between-colors bias/between-pages bias
L
L
—
H
Print bias
AC Current: Low
H
L
H
L
AC Current: High
H
L
L
L
