Mechanism - Canon NP6317 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
B.

Mechanism

1. Turning the Scanning Lamp ON and OFF
The microprocessor (Q300) on the DC controller PCB controls the lamp regulator. The scan-
ning lamp goes ON when the scanning LAMP ON command (LOAN) is '1', and it goes OFF when
the signal is '0'.
2. Controlling the Intensity of the Scanning Lamp
The intensity of the scanning lamp is controlled by the lamp shift signal.
The intensity of the scanning lamp is changed.
When the reproduction ratio is different than 100% changing the T-on time of the lamp shift
signal. The T-on time of the lamp shift signals is fixed to 5ms at 100%. During AE exposure,
however, the voltage (135 V) applied to the scanning lamp remains the same.
The adjusts the copy density using its development bias; see p. 10-18.
3. Error Protection
The condition of the scanning lamp is monitored using the lamp check signal.
If the lamp check signal is received by the DC controller even when the lamp is off, the error
detection circuit generates the AC SHUTOFF signal to force the relay (K100) on the AC driver/DC
power supply PCB to go OFF, thereby cutting AC power supply (p. 3-39). In this case, E220 error
is displayed.
4. Zero-Cross Signal
The board generates the zero cross signal that the DC controller uses to control the fixing
heater temperature. E261 is indicated on the control panel if an zero cross error is identified.
DC controller PCB
4-4
J306
-4
MEAT
J305 J203
-3 -4
LAMP
CHECK
ZERO
CROSS
J305
J203
-2
-5
Intensity
J305 J203
switching
-1 -6
circuit
LAMP
SHIFT
J305 J203
-4 -3
switching
circuit
LAMP-ON
Lamp driver unit
Figure 4-201
COPYRIGHT © 1999 CANON INC.
Power supply assembly
Lamp ON
detection
circuit
Phase
control
Triac-triggering circuit
Short connector
CANON NP6317 REV.0 APR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Relay
J201
-1 K100
-2
J202-1
FU2
Scanning lamp
(LA1)
J202-3