Technical information

OPERATIONS AND TIMING
E. Error Detection Circuit
(NP21 20)
1. Outline
An error in these signals causes the error detec-
The signals (LIGHT, SSRON, HTRD, TH) shown
tion circuit to issue the ACOFF signal, thereby acti-
vating the AC shutoff relay (RLl).
in Figure 3-45a are input signals to the error detec-
tion circuit.
The error detection circuit is built into the DC
controller, and is used to monitor the surface tem-
peratureoftheupperfixingroller,theconditionofthe
fixing heater, and the condition of the scanning lamp.
Fixing heater (Hl)
DC controller
Figure 3-45a
2. Mechanism
Figure 3-45a shows the error detection circuit,
and Table 3-5 lists the conditions for its activation.
The error AC shutoff relay (RLl) goes OFF in
response lo the output of the errordetection circuit in
terms of both software and hardware.
a. Detection by Software
Ifanerrorinthesurfacetemperatureoftheupper
fixing roller (220°C) or the activation of the fixing
heater is detected in terms of software, the error AC
shutoff relay (RLl) is turned OFF immediately and
an error code is displayed.
3-47a COPYRIGNT 0 1992 CNNON ING.
CANON NPZl20/2MO RN.0 OEC. 1992 PAINTED IN JAPAN (IMPRIME AU JAPONI