Technical information

C. Controlling the Scanning
Lamp
1. Outline
The scanning lamp iscontrolled bythe DC controller
PCB as follows; see Figure 3-24.
- Turns the scanning lamp ON and OFF.
* Controls the scanning lamp intensity.
2. ivlechanism
a. Turning the Scanning Lamp ON and OFF
The microprocessor (slave; Q302) on the DC
controller PCB causes the transistor (Q324) to
goON,therebycausingthescanninglamp(LAl)
to go ON; the lamp goes OFF when Q324 goes
OFF.
b. Controlling the Scanning Lamp Intensity
The intensity of the scanning lamp is varied by
controlling the voltage supplied to it in response
to the level of the intensity adjustment signa1
DC wntroller PGB
3-26
(LINT) from the DC controller PCB.
The LINT signa1 varies between 10 and 16 V
as determined by the copy density correction
lever, controlling the voltage supplied to the
scanning lamp so that it varies between 50 and
75 V (phase control).
WhentheCTunitisused,thevoltageapplied
to the scanning lamp is raised by about 1.8 V as
opposed to when the black developing assembly
is used so as to increase the intensity of the
scanning lamp. A constant voltage (70 V),
however, is applied to the scanning lamp during
AE exposure for both the black developing as-
sembly and CT unit.
c. Error Identification Circuit
The scanning lamp is monitored using the lamp
ON signa1 (LIGHT).
lf the scanning lamp ON signa1 (LIGHT) is
present on the DC controller for about 20 sec
continuously, the error identification signa1 gen-
erates the AC power OFF signa1 (ACOFF) to cut
off the AC power; see p. 3-47.
i
T
circuit
-2 LMPOr\! -5 Switching
- circuit
-5 ZXDP -2
Lamp reg&tor
Figure 3-24
COPVRIGHT 0 1992 CANON INC. CANON NPZl20/2MO RN.0 MAV 1990 PAINTEU IN JAPAN IIMPAIME AU JAPONI
Scanning
lamp
(LAI)