Canon imagePRESS C1 P Service Manual page 288

AB-Configuration
CCD original detection position
To raise the accuracy of original size identification (as when the original is displaced while the ADF is closed), the machine makes use of the following 2 types of
mechanisms:
1. Presence/Absence of an Original at 2 Points (for each point of measurement)
For each point of measurement in main scanning direction, the machine checks the presence/absence of an original with reference to the CCD output at 2 points
near the point of measurement.
1A
no
yes
no
yes
Note:
Changes in the Signal (from ADF open to close)
change: no
other: yes
The machine uses OR combinations for identification.
2.Priority on the Front Sensors
When checking the measurements for main scanning direction, if the absence of an original is indicated at the rear while the presence of an original is indicated at
the front, the machine will give priority to the indication at the front (i.e., presence of an original).
Original
sensor 1
Point of original
detection 1
B6 B5R
Print of original
A5 A4R
detection 2
B5
Point of original
A4
detection 4
Original size
border line
Near 13 mm
Original size
border line
Result of measurement
1B
no
no
yes
yes
Inch-configuration
Point of original
detection 1 STMTR
Point of original
detection 2
STMT
B4
Point of original
detection 3
A3
CCD original detection position
F-5-17
1A:additional point
of detection
Near 4 mm
1B:conventional point
if detection
F-5-18
T-5-6
Result of detection
original absent
original present
original present
original present
Original
sensor 3
LTRR LGL
279.4×431.8mm
LTR
(11"×17")
Chapter 5
5-9