Lexmark 4200 Series - Manual (Page 36)

3-2 Service Manual
4413-XXX
Contact Image Sensor (CIS)
The contact image sensor unit consist of LEDs, rod lens array, and a
photo sensor. The LEDs illuminate the document to be scanned
when the leading edge is detected by the document scan sensor.
The LEDs turn off when the document exits the scanner mechanism.
The LEDs illuminate the document to obtain an image from the
document through the rod lens array, where the image is translated
into voltage levels.
Document sensors
There are two document sensors in the scanner mechanism; the
document detect and the document scan sensor. The document
detect sensor, detects whether or not a document is loaded, and the
document scan sensor detects the scan position of the document.
The scanner mechanism consists of components which feed, scan,
and eject the documents that are to be copied or transmitted to a
remote facsimile unit.