Scanner Theory; Duplex Adf - Lexmark X548 Series Service Manual

7525-63x
When the trailing edge of the media clears the fuser, the fuser engine rotates forward to prepare the fuser for the
page travelling through the duplexer.
As the media reaches the gate aligner, a sensor (S1) is triggered indicating the presence of the leading edge.
When the S1 sensor is triggered, the paper continues to the S2 sensor. When the S2 signal is detected, the
speed of the paper is adjusted to accommodate the speed of the transfer belt, ensuring the proper registration of
the image on the media. The paper travels to the ITU (C) and the second image is transferred to the reverse
side of the media.
Once the imaged is transferred, the media travels to the fuser (D), the fuser exit rolls (E), and the output bin.

Scanner theory

Duplex ADF

The following illustration shows the paperpath, rollers and sensors used in the X548 duplex ADF.
The X548 duplex ADF enables the user to create duplex scans automatically, eliminating the need to stop the
scanning process to flip the media being duplicated over. The ADF uses a step motor, and a series of sensors to
determine the media's position in the paper path during the scan process.
The following steps are performed in creating a duplex scan on the X548 duplex ADF.
1. The scanner control unit, on the RIP board receives a command to create a scan, fax, or copy.
A signal is sent to the ADF to poll the paper present sensor to check if the media to be scanned is in the
2.
correct position. The media must be placed in the ADF input tray so it actuates the paper present sensor. If
the ADF paper present sensor isn't actuated, a flatbed scan is run by default.
3. If the media has actuated the paper present sensor, an ADF scan is executed. At this point the roller on the
pick arm assembly drops and advances the paper into the ADF, actuating the document sensor. Actuating
this sensor determines that this will be the first side of the document to be scanned.
Service Manual
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