User's Manual

CHAPTER 4 IMAGE FORMATION SYSTEM

1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)

4-9

T_REV_ON* signal

Negative transfer bias ON

Positive transfer bias ON

(cleaning bias)

Transfer bias OFF

ATVC

Transfer bias ON signal

(serial communication)

bit2 bit3

T-FW_ON signal

2. Operations

a. Turning On and Off the Transfer Bias

The transfer bias applied to the transfer charging roller is turned on and off by the serial com-

munication signal from the DC controller PCB.

When the transfer bias ON signal (serial signal) is generated by the DC controller PCB, the

microprocessor (Q900) on the composite power supply PCB generates the high-voltage trans-

former control signal (CLK32K), transfer DC bias ON signal (T_FW_ON), and transfer DC bias

control signal (T_FW_DRV), thereby applying the transfer bias to the transfer charging roller.

Table 4-103 Relationship between Transfer Bias Output and Signals

b. Controlling the Transfer Bias to a Specific Voltage

The transfer bias applied to the transfer charging roller is controlled to a specific level by the

microprocessor (Q900) on the composite power supply PCB.

When a transfer bias is generated, the microprocessor (Q900) on the composite power supply

PCB checks the transfer bias voltage detection signal (T_FEEDBACK), compares it against the

reference value, and varies the transfer DC bias control signal (T_FW_DRV) according to the

difference to ensure that the transfer bias remains a specific level at all times.

Reference:

The level of transfer bias applied to the transfer roller during a copying run is between -7.5

and -3.0 kV.