Scanner - Xerox Phaser 6500 Service Manual

Theory of Operation

Scanner

2-60
The Scanner consists of a lamp (fluorescent lamp, etc.) that illuminates the
original document with uniform light and a Charged Coupled Device (CCD), which
reads the light reflected from the image.
A CCD is a light-receiving element that produces an electrical signal in response to
light. In the case of a Fax, a number of CCDs are arranged in a line.
The white areas of the original document reflect the light from the lamp. The black
areas reflect no light. The CCDs read the light reflected from the original,
outputting sequentially to the control circuit, which areas are white and which are
black as binary data (1/0 digital data: 1 bit).
To scan the original, the CCD device is shifted a distance of one line after each line
is scanned. When the original is scanned directly on the document glass, the CCD
is moved across the original. When the ADF is used, scanning is performed by
moving the original with the CCD fixed at one position. This is called Constant
Velocity Transport (CVT).
The scanning section consists of a Scanhead assembly that scans documents
placed on the document glass.
The optical image reflected from the document reaches the Charged Coupled
Device (CCD) image sensor via the light path.
CVT Position
(Home Position)
Scanner
Home Position Sensor
Xerox Internal Use Only
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Platen Registration Point
Scanhead
CCD Image Sensor
Phaser 6500/WorkCentre 6505 Service Manual
s6500-076