D. Error Detection
(NP2020)
The error detection circuit found
the DC
controller PCB and
to monitor the fixing
temperature and scanning
rises
the former, and timing of activation of the latter.
of the
conditions occurs, the output
of the circuit causes the
to go OFF,
thereby cutting the supply power
to the fixing
heater and lamp regulator.
2. Mechanism
Whenthevoltageofthethermistorreachesabout
1.0 V
of a rise the temperature of the
fixing roller, the output of the No. comparator of
goes ‘0’.
The lamp regulator generates
ning lamp
signal) at
times as long as the
scanning lamp
The
conditions cause the No. 2
tor of Q309 to
‘1’. thereby charging the
(C333).
C333
charged about 20 seconds
thereafter: and output ‘1’ of the No. 2 comparator
sent the negative input
of the No. 3
comparator. As a result, the output of the No. 3
comparator of Q309 goes ‘0’.
T h e
conditions
thereby causing the
to go OFF.
The
can be
after activation of the
errordetection circuit by turning it OFF and then
detection circuit
(DC
PCB)
Figure
CANON INC.
C A N O N
IN
3-47
Summary of Contents for NP-2020
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