Canon FY8-13FW-000DADF-A1 Service Manual page 27

3. Detecting the Size of an Original
a. Outline
The machine detects the size of an original
in relation to the vertical (feeding) and
horizontal directions of the original, ensuring
correct size detection and for use for the
communication protocol of fax mode.
b. Detecting in Vertical (feeding)
Direction
Detection in vertical direction is made by
the registration paper sensor (S3) and the
registration roller clock sensor (S11).
The registration paper sensor detects the
leading and trailing edges of an original, and
the registration roller clock sensor detects the
rotation of the registration roller while the
original moves past the sensor. The rotation of
the registration roller is converted to the length
of the original.
DADF controller PCB
Registration
paper sensor
Registration roller clock sensor
Registration roller
Figure 2-208
COPYRIGHT © 1998 CANON INC. CANON DADF-A1 REV.0 DEC. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 2 BASIC OPERATION
c. Detection in Horizontal Direction
Detection in horizontal direction is made
by the original width detecting volume (VR)
on the original tray. The original width
detecting volume operates in conjunction with
the side guide. As its resistance varies, the
changes are detected by the DADF controller
PCB, which converts them into a length in
horizontal direction.
DADF controller PCB
Figure 2-209
Side guides
VR
2-13