Controlling The Fluorescent Lamp Heater - Canon NP6218 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
Input to the Reversal Amplifier Circuit (if the intensity increased gradually)
Changes in the Duty Ratio of the FLON signal

6. Controlling the Fluorescent Lamp Heater

As the temperature around the scanner increases, the resistance of the fluorescent
lamp thermistor (TH3) lowers, thereby lowering the voltage of the fluorescent lamp
thermal signal (FLTH). Based on the voltage, the fluorescent lamp heater control circuit
on the composite power supply PCB turns on and off the fluorescent lamp heater drive
signal (FLTHON).
You can force the fluorescent heater off by turning off the scanning lamp (fluorescent
lamp) heater switch (SW2) during the months in which the heater is not needed.
4-8
Voltage (V)
Reference voltage
(4V)
Reference voltage
(4V)
Figure 4-109
FLON signal 'C'
FLON signal 'D'
Figure 4-110
COPYRIGHT © 1997 CANON INC.
Input from intensity
adjustment sensor
Lighter
Darker
Time (t)
"C" "D"
OFF
ON
OFF
ON
CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)