Lexmark X792 7562-4xx, Service Manualv

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Service Manual
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Scanner theory
A document sheet set in the document tray assembly is fed through the ADF feed roll, ADF pick roll, and ADF
separation roll assembly. The document image is scanned at the scan position, and the document sheet is
ejected through the ADF feed-out roll assembly and the ADF exit roll assembly. For a duplex document sheet,
the image on side 1 and the image on side 2 are scanned at the same time in the same pass.
Described below is the overview of the steps before document scanning and that of simplex and duplex
document scanning modes.
Setting a document
When a document is set on the document tray assembly and the lead edge is pushed into the tray until it stops,
the ADF document set actuator moves to place the sensor (ADF document set) in the unshielded (unblocked)
state. Then the machine recognizes that the document has been set properly, turning on the document set
LED.
Preparation for feed
1.
Pressing the start button with the document set in the document tray will start feeding the document.
2.
The pick roll moves down and presses the document on the document tray to enable document feed.
3.
The pick roll moves down with the normal rotation of the ADF feed drive motor assembly and it moves up
with the reverse rotation of the ADF feed drive motor assembly.
4.
Upon completion of document feed, the pick roll returns to the normal (raised) position.
Shown below is the document feed path from the ADF.
Simplex and duplex document feed
For two simplex document sheets, feed is performed in the following sequence:
1.
The first document sheet is fed to the ADF transport roll assembly.
2.
The document is fed to the ADF registration roll assembly, and then fed to the scan feed reference
position.
3.
The document sheet is fed at the feed speed corresponding to the selected magnification, and the image
on it is scanned with the exposure lamp at the scan position.
4.
As the image is scanned, the document sheet is fed and ejected by the ADF feed-out roll assembly and
ADF exit roll assembly that are driven by the ADF transport motor.
5.
When the trail edge of the first document sheet has passed through the sensor (sheet through), the feed of
the second document sheet starts.
Duplex CCD