Canon DADF-Q1, Service Manual

Page: 32 / 156

Chapter 2
2-10
F-2-14
2.3.3 Original Size Detection 1
0011-2242
In original size detection 1, the original trailing edge sensor is used (S7), which is designed to identify the original in the original tray as being small-size or large-
size.
When the original covers the original trailing edge sensor, the light from the LED of the original trailing edge sensor is reflected by the original to hit the phototran-
sistor, at which time the DADF identifies the original as being large-size.
The DADF sends original size data (small-size or large-size) to the copier, which uses the data to determine the point at which the scanner is stopped for stream
reading.
Small size: A5, A4, B5, STMT, LTR
Large-size: A4R, B5R, A3, B4, LTRR, LGL, 279.4X431.8mm (11"X17")
ADF controller PCB
S6
(light-receiving side)
S6
(light-emitting side)
S6
(light-receiving side)
ADF controller PCB
When an original is detected When no original is detected
S6
(light-emitting side)
S6
(light-receiving side)
ADF controller PCB
DTS signal
DTS signal
Original
Light is blocked.
S6
(light-emitting side)