Scanner System: Mx310/Mx410/Mx510/Mx610; Adf Theory Of Operation - Lexmark MS310 Manual

Lexmark MS31x/41x/510/610 & MX310/410/51x/61x Product Study Guide

Scanner System: MX310/MX410/MX510/MX610

The document scanning section consists of a scanner that reads a single-sheet document placed on the
flatbed glass and an Auto Document Feeder (ADF) that can read the pages of a multiple-sheet and/or
duplexed document.

ADF Theory of Operation

A duplex ADF enables the user to create duplex scans automatically thus eliminating the need to
manually flip the document. The ADF uses DC motors with encoder wheels and a series of sensors to
determine the position of the media in the paper path during the scan process.
The following steps are performed in creating a duplex scan on a duplex ADF.
Step Function
The scanner control unit (on the controller board) receives a command to create a scan, fax,
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or copy.
A signal is sent to the ADF to poll the document sensor to check if the media to be scanned is
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in the correct position. Media must be placed in the ADF input tray so it actuates the document
sensor. If the ADF document sensor isn't actuated, a flatbed scan is run by default.
If the media actuates the document sensor, then an ADF scan is executed. At this point, the
pickup roller on the pick arm assembly drops and advances the paper into the ADF. To
minimize the possibility of multiple sheets being fed, the ADF uses a separator roll that
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counter-rotates against the feed direction. After passing the pick assembly, the media
actuates the stage and interval sensors. Actuating these sensors indicates this will be the first
side of the document to be scanned.
The stage sensors are used to determine and correct document skew if it is present. If the
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stage sensors actuate at different times, the paper is slowly fed to the paper feed 1 roller. The
feed motor encoder wheel count tracks the paper location in the paper path.
The paper feed 1 roller is stationary and acts as a registration roll which causes the paper to
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de-skew.
When the encoder count reaches a certain point, the paper feed 1 roller advances the de-
skewed paper to the paper feed 2 roller and feed sensor. If the paper does not actuate the
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feed sensor before the pre-determined encoder count is attained, a paper jam error is
generated.
When the feed sensor actuates, the paper advances to the scan area. While the paper is
advancing to the scan area, the DC motor encoder generates a count which is stored in an on-
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board counter. These counters, in conjunction with the feed sensor, ensure the media is
travelling at the correct speed through the scan area. The speed of the document through the
ADF scan area is dependent on the image DPI which is specified by the user.
After a predetermined number of counts, the media reaches the scan area and the image
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acquisition process is initiated. While the image acquisition process is executing, the feed
sensor is polled to determine if the trailing edge of the media has reached the sensor.
For Training Purposes Only 19
Rev 1.3
4/21/2014