Canon iR1600 Service Manual page 83

When the copyboard cover is closed to about 30°, the copyboard cover open/closed sen-
sor (PS111) goes ON. The original detection/reader motor drive PCB reads the output lev-
els of the original size sensors at intervals of 0.125 sec for 15 sec after the copyboard
cover open/closed sensor goes ON or between when the copyboard cover open/closed sen-
sor goes ON and when the Start key is pressed. If it detects a change in the level, it identi-
fies the condition as the absence of an original; if there is no change, it will identify the
condition as the presence of an original. This way of identification enables the machine to
detect the size of a black original.
In the case of conditions a and b in the following, the output level of the sensor remains
unchanged, at times causing the machine to make the wrong detection. If, for condition c,
i.e., A3 (11x17) is selected with priority and A3 (11x17) paper is absent, the cassette se-
lected for standard mode will be selected.
a. A3 (11x17) Black Original
b. Book original (The thickness of the original prevents the copyboard cover from closing
fully, making it difficult to detect a change in the sensor level.)
c. Copyboard cover (not closed)
Copyboard cover
PS111:OFF
COPYRIGHT© 2002 CANON INC.
CHAPTER 3 IMAGE READING/PROCESSING SYSTEM
Copyboard cover
Original
PS111:ON
Original size sensor2 Original size sensor1
(PS115)
F03-302-02
2000 CANON iR1600/iR2000 REV.1 JAN. 2002
30˚
PS111:ON
Copyboard
glass
Change in
(PS114)
No change
level in level
3-5