Document Scanning At Adf - Lexmark MB790MFP Service Manual

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Document scanning at ADF

The document scanning section of this machine consists of a scanner that reads a single-sheet document
placed on the platen glass and a document feeder that can transport a multiple-sheet document for one or two-
sided scanning.
Document scanning at platen
Shown below is the operational overview of document scanning at the platen.
The scanner CCD assembly travels to read the document.
The exposure lamp is installed on the scanner CCD assembly. As the scanner CCD assembly travels, the
document on the platen glass is scanned and exposed with the exposure lamp.
The image data is read with the scanner CCD image sensor assembly.
This ADF employs a constant velocity transport system that scans images by feeding the document at a
constant speed over the specified position (scan position) where the carriage of the scanner unit assembly is
fixed.
ADF Scan position
Names and functions of components
The sections below describe the functions of main components of the scanner.
Scanner unit assembly
Sensor (FB length APS 1), Sensor (FB length APS 2), Sensor (FB length APS 3)
The document length in the slow scanning direction is detected by a combination of the three reflector sensors.
Switch (ADF closed interlock)
A switch that detects whether the ADF is open and determines the timing of platen document size detection.
Scanner drive motor assembly
A stepping motor that drives the scanner CCD assembly.
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Service Manual
Platen registration point
Carriage
Sensor (scanner HP)
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