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2) Document size detection by the document width
sensor (DWS) in the paper feed section
The document size detection by the document width sensor (DWS) in
the paper feed section is used in automatic paper size and automatic
magnification ratio selection mode to determine whether the docu-
ment is A4 or A5 (11" x 8.5" or 8.5" x 5.5").
When documents composed of stacked sheets of different sizes are
set in the document tray, the document size cannot be detected by
the sensors in the document tray. Therefore, this function is provided
to sense the document size behind the resist roller after the paper
feed section has fed the document, as far as documents of A4 or A5
size (11" x 8.5" or 8.5" x 5.5") (portrait) is concerned. Consequently, if
A4- and A5-size (11" x 8.5" or 8.5" x 5.5") documents (portrait) are
stacked and set in the document tray, the document size detection by
the paper feed section document width sensor (DWS) has the priority
over the document size detection by the document set tray.
When A4- and A5-size (11" x 8.5" and 8.5" x 5.5") documents
(portrait) are stacked and set in the document tray, the document
length sensors (DSL1, DSL2) are not actuated. Therefore, the docu-
ment width is sensed by the paper feed section document width
sensor (DWS) to judge A4 or A5 (11" x 8.5" or 8.5" x 5.5").
Paper feed section original width sensor (DWS)
Paper feed section original width sensor (DWS)
Paper feed section document width sensor (DWS) status
Document
F: Output LOW (Detection)
size
: Output HIGH
A4/11" × 8.5"
B5/8.5" × 11"
A4/11"x8.5"
B5/8.5"x11"
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3) Document size detection by the paper feed
motor rotation sensor (DFMRS)
This function compensates for the inaccuracy of the document size
recognition in the document tray when documents of different sizes
are stacked in the document tray. That is, results of this function has
priority over the document size detection in the document tray. The
pulses of the slit disc rotation of the feed motor (DFM) are counted in
the period before the rear edge of document is sensed (DFD output
LOW) by the document feed sensor after the feed motor (DFM) has
started reverse rotation, that is, after the resist roller has started
rotating and feeding of document from the fed section to the transport
section has been started, to determine the document length.
To improve detection accuracy, the document width is sensed also by
the paper feed section document width sensor (DWS).
Resist roller rotation start (The document is fed from the paper feed
section.)
Original feed sensor (DFS)
A
Resist roller
Original feed sensor (DFD)
B
Resist roller
The paper feed motor rotation sensor (DFMRS) counts the number of
rotations of the paper feed motor (DFM) between
the document length.
7 – 5
Original feed sensor (DFS)
detects the original rear edge.
A
B
and
to judge
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