Controlling The Pre-Heating Mechanism; Turning On And Off The Scanning Lamp; Controlling The Intensity - Canon GP335 Service Manual

B. Controlling the Pre-Heating Mechanism
The filament of the scanning lamp is kept powered so that the intensity of the scanning lamp
will attain an optimum level in a short time after the Copy Start key is pressed (pre-heating).
The pre-heating state may be either full-preheating or lamp pre-heating.
a. Full Pre-Heating
About 4.2 V is applied to the filament during initial rotation.
b. Lamp Pre-Heating
About 3.8 V is applied to the filament during a copying run.
C. Turning On and Off the Scanning Lamp
The scanning lamp is turned on or off by the intensity control signal from the image processor
PCB. A lamp activation voltage is applied to the scanning lamp in response to the signal.
D. Controlling the Intensity
The intensity control signal is a pulse signal, and the intensity of the scanning lamp is varied by
changing the duty ratio of the signal. The output value of the scanning lamp intensity sensor is sent
to the image processor PCB on a periodical basis for monitoring and maintaining the intensity at a
specific level.
Related Service Mode
FUNCTION>CCD>MAN-ADJ
COPYRIGHT © 1999 CANON INC. CANON 405/335 REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Determines an optimum activation voltage based on the results of
shading auto correction.
CHAPTER 3 EXPOSURE SYSTEM
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