Canon NP6330 Service Manual page 79

2. Operation
When the copyboard cover is brought down to about 30°, the copyboard cover
open/closed sensor (PS17) turns ON, i.e., the light-blocking plate blocks PS17.
After PS17 has turned ON, the output level of each size sensor is read for 15 sec or
until the Copy Start key is pressed at intervals of about 0.1 sec. If the output level
remains the same during the period, the copier assumes the presence of an original at
the respective sensors, ultimately identifying the size of the original according to Table
3-401/3-402.
Although this way of identification can detect the size of a black original, the output
level of the sensor will not change in the following cases:
a. Black original of A3/11"
b. Book original (the thickness prevents changes in level)
Reference:
a or b can cause wrong detection of the size.
Origina
PS17: ON
Original
size sensor
COPYRIGHT © 1997 CANON INC.
17"
Copyboard cover
15°~30°
ON
OFF
Figure 3-403
CANON NP6330 REV.0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 3 EXPOSURE SYSTEM
Copyboard glass
No change
Original
size sensor
ON ON
Change
in level in level
3-15