Canon PC300 Service Manual page 51

S88 OPERATIONS AND TIMINGI28
2. Operations
a. Operations in Measurement Mode
HVTDC=1, DOTPWM=0
Oscillation circuit goes ON.
Constant current control circuit generates 'ON'.
Measurement mode is selected,
applying a constant current to
the transfer charging roller.
TREV=1
Positive bias control circuit goes OFF.
High-voltage transformer/rectifier
circuit goes OFF.
In measurement mode, the current is monitored by the current sensor circuit so that the
constant current control circuit can control it to a constant current.
Further, the microprocessor monitors the internal resistance of the transfer charging roller in
terms of voltage using the auxiliary winding of the transformer (T107).
b. Operations during Copying
HVTDC=1, DCTPWM=1
Oscillation circuit goes ON.
Pulse/DC converter circuit goes ON.
Voltage control circuit goes ON.
|
+» High-voltage transformer (T107)
goes ON to apply a negative DC
bias to the transfer charging roller.
TREV=1
Positive bias control circuit goes OFF.
Multiplier/rectifier
circuit goes OFF.
3-24 COPYRIGHT © 1994 CANONINC. CANON PC300/%20/225, FC210/290 REV.O JULY 1904 PRINTED IN JAPAN (IMPRIME AU JAPON)