Canon imageRUNNER ADVANCE 4551i Service Manual page 83

Feed
The Pickup motor (M1) drives the Lower registration roller through the Registration clutch (CL2). Thus a document is fed.
A document is fed to the read wait point when the Read motor (M2) drives the Read roller 1 (upper).
Stream reading
The stream reading starts when the leading edge of a document reaches the reading point and the read start signal is received
from the host machine.
"Stream reading" is a scan function which a document is scanned while feeding along the Document glass. The Scanner which
is fixed under the Document glass reads the image.
A document is fed by the Read roller 1 (upper) and the Platen roller driven by the Read motor (M2). The read image is stored in
the memory of the host machine.
● Pickup Roller Assembly and Separation Roller
The Pickup roller assembly consists of the Pickup roller and the Feed roller.
When the start key is pressed or a document pickup signal is input, the Pickup motor (M1) drives to lower the Pickup roller
assembly through the Pickup clutch (CL1) and then the Pickup roller and the Feed roller rotates to feed a document to the
Registration roller.
The Pickup roller assembly is equipped with stoppers to prevent that a document is inserted deeper than appropriate position.
The Separation roller is used to improve the separation performance while picking up a document.
Upper/Lower registration roller
Loop
M2
CL2
Read roller 1
(Upper)
Reading start point
M2
Document glass Scanner
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M1
Lower registration roller
Platen roller
2. Technology