Feed Error Detection - Canon imageFORMULA DR-M160 Service Manual

CHAPTER 2 FUNCTIONS & OPERATION

2. Feed Error Detection

1) Paper Jam Detection
Paper jams are detected by the registration
sensors (pre and post). The types of the
document jams are described as follows.
a) Pickup Delay Jam (Pickup Error)
The leading edge of the document
was not detected by the registration
sensor within the specified time after
the machine starts scanning.
b) Early Reach Jam
The leading edge of the following
document was detected after the trailing
edge of the document was detected by the
registration sensor before the document
has been fed for a specified length.
c) Residual Jam
The trailing edge of the document was not
detected even though the document has
been fed for the maximum specified length
after the leading edge of the document
was detected by the registration sensor.
d) Fast Feed Jam
The trailing edge of the document was
detected after the leading edge of the
document was detected by the registration
sensor before the document has been fed
for the minimum specified length.
e) Non-removal Jam
The machine starts scanning while the
document is detected by the registration
sensor and still remains inside this machine.
2) Double Feed Detection
There are 2 double feed detection
methods: the document length detection
by the registration sensor and the
document overlapping detection by the
ultrasonic sensor.
2-12
Registration sensor
The registration sensor uses the first
document length of the scanned batch as
a reference to detect the document length.
The 35 mm or more difference from the
standard is interpreted as a double feed.
Ultrasonic sensor
The ultrasonic drive sensor transmits the
ultrasonic and the ultrasonic receive
sensor receives the ultrasonic signal to
gain a specific signal level. When
overlapping documents are fed, the signal
level is different from when properly
feeding a single document. This machine
interprets this difference as a double feed.
Note that since this difference in the
signal occurs depending on the presence
of a layer of air, a double feed will not be
detected if the document is tightly
adhered by static electricity or adhesive.
Furthermore, double feed is judged if a
double feed is detected continuously for
a specific amount of time. As a result, if
the overlap between sheets is less than
50 mm when a document is being fed, it
might not be judged as a double feed
because the detection time is short. In
the case of separation retry, since the
detection is performed with the document
stopped momentarily, double feed can be
judged even if the overlap is short.
COPYRIGHT © CANON ELECTRONICS INC. 2011
Ultrasonic receive sensor
(reception)
Ultrasonic drive sensor
(transmission)
Figure 2-305
CANON DR-M160 FIRST EDITION