Operations; Turning On/Off The Scanning Lamp; Detecting The Activation Of The Scanning Lamp - Canon 1130 Service Manual

B. Operations

1. Turning On/Off the Scanning Lamp

When LAON=0, the lamp regulator drive circuit and the intensity control circuit turn off,
causing the lamp to turn off.
When LAON=1, the lamp regulator drive circuit and the intensity control circuit turn on,
causing the lamp to turn on.

2. Detecting the Activation of the Scanning Lamp

When the lamp is on, the lamp activation detection circuit sends the activation detection signal
(LAON-S*) to the timer circuit and the CPU PCB (R-CPU). The timer circuit is reset on a
periodical basis so that the lamp may be kept on continuously as in A4/LTR continuous copying
operation (2-sheet retention).
3. Detecting an Error in the Activation of the Scanning Lamp
If an error keeps the scanning lamp on for about 60 sec (LAON-S*=0) when continuous
copying mode (2-sheet retention) is not selected, the timer circuit turns on the error latch circuit to
force the LAON signal to go '0', thereby turning off the lamp. At the same time, the lamp error
signal (LAERR) is sent to the CPU PCB.
As a result, the copier will indicate 'E220' on the control panel, and activate the auto shut-off
mechanism. If such has happened, remove the cause, and turn on the power switch to reset the
copier.
In addition, the copier is equipped with the following hardware protective mechanisms to
protect against lamp malfunctions:
· If the internal temperature of the thermal switch exceeds 175ºC, the thermal switch turns off
to cut off the power to the lamp.
· If an overcurrent flows because of a short circuit around the lamp, the fuse (FU1) will blow to
turn off the lamp regulator.
The contact of the scanner thermal switch (TP1, TP6) is subject to damage when
it turns on. Do not use it once it has turned on.
4. Controlling the Intensity of the Scanning Lamp
The intensity of the lamp is determined by the duty
(LACNTL) from the CPU PCB, and the intensity control circuit inside the lamp regulator sends
pulse signal (PWM) to suit the duty
and off at short intervals to control the current to the lamp and, ultimately, the intensity.
The duty ratio of the LACNTL signal is determined in response to FUNCTION>CCD>CCD-
ADJ in service mode, and it remains the same until the item is executed the next time.
FUNCTION > CCD > ADJ
Be sure to execute this item if you have replaced the standard white plate,
scanning lamp, R flash memory, CCD unit, analog processor PCB, or CPU
PCB.
COPYRIGHT © 2002 CANON INC.
ratio to the switching circuit, which in response keep turning on
CANON CLC1100/1130/1150/1160/1180 REV.1 FEB. 2002 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 3 EXPOSURE SYSTEM
ratio of the intensity adjustment signal
3-7