Lexmark MX81 Series Service Manual page 787

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
sensor (ADF media present) becomes covered and the machine recognizes that the document has been set properly,
turning on the media present LED.
Preparation for feed
Pressing the start button with the document set in the document tray will start feeding the document.
First, the pick roller moves down and presses the document on the document tray to enable document feed. The ADF
tray lift motor then raises the ADF media tray to the correct position for media to be picked. The ADF pick roller, ADF
feed belt and ADF separator roller are driven by the normal rotation of the ADF pick motor. The transport rollers are
driven by the ADF transport motor.
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
roller assembly that are driven by the ADF transport motor.
5
When the trail edge of the first document sheet has passed through the sensor (ADF pick), the feed of the second
document sheet starts.
Duplex document
For duplex document sheets, feed is performed in the following sequence:
1
The first document sheet is fed to the ADF transport roller assembly.
2
The document is fed to the ADF registration roll assembly, and then fed to the scan feed reference position.
Appendix C: Theory of operation
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