User manual

95.08.23.11.29
Color LaserWriter 12/600 PS Basics & Theory 1–61
High-Voltage Control: Operation
When the /PRNT signal sent from the I/O controller goes “L,” and the
print sequence command is entered from the DC controller to the
mechanical controller, the mechanical controller rotates the drum motor
and controls the high-voltage control IC (IC1003) on the high-voltage
power supply board as follows.
Voltage to
Primary
Charging
Roller
The high-voltage control IC (IC 1003) on the high-voltage power
supply board 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 switches the primary charging voltage AC current
value according to the environment detected by the tempera-
ture/humidity sensing system. The output value of the
/HV1PWM signal
remains fixed.
OFF
Between-Colors Bias/Between-Pages Bias
Print Bias
AC Current : Low
/HV1DC0
L
H
H
/HV1DC1
H
L
L
L
/HV1AC0
H
L
/HV1AC1
H
H
L
L
AC Current : High