Controlling The Primary/Transfer Corona Current; Outline; Controlling The Primary Corona Current - Canon NP6045 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
C. Controlling the Primary/Transfer Corona Current

1. Outline

Figure 4-109 shows the circuit that controls the primary/transfer corona, and the
circuit has the following functions:
Turning ON and OFF the primary corona current.
Controlling the primary corona current to a specific level.
Turning ON and OFF the transfer corona.
Controlling the transfer corona to a specific level.

2. Controlling the Primary Corona Current

The DC controller PCB compares the drum surface potential V
potential detection circuit against the target potential; if it is different from the target
potential, the signal used to control the primary corona current generated by the DC
controller PCB is corrected.
The corrected signal is converted to an analog value (HVTPC signal) by the D/A
converter circuit and sent to the high-voltage transformer, thereby controlling the primary
corona current.
The primary corona current output is turned ON and OFF by the DCON signal. The
output of the primary corona current is controlled by the HVTPC signal.
If the HVTPC signal is about 3 to 11 V or less, the output of the primary corona
current turns ON; it turns OFF when the signal is about 12 V or more.
a. Primary Corona Current Output OFF
HVTPC is about 12 V.
DCON is '0'.
The variable width pulse oscillator circuit turns OFF.
The drive circuit turns OFF.
The primary high-voltage transformer turns OFF.
b. Primary Corona Current Output ON
HVTPCB is less than about 11 V.
DCON is '1'.
The variable width pulse oscillator circuit turns ON.
The comparator circuit turns ON.
The drive circuit turns ON.
The primary high-voltage transformer turns ON.
4-10
COPYRIGHT © 1997 CANON INC. CANON NP6045 REV. 1 MAR. 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
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