Xerox Phaser 6280, Service Manual

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2-32 Phaser 6280 Color Laser Printer Service Manual
Theory of Operation
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Laser Diode Board
There are four Laser Diodes which produce laser beams that are turned
On and Off according to the print data signal.
The Laser Diode Board is comprised of four LDs corresponding to C, M,
Y, and K. Each LD converts the electric signals of incoming image data
into laser waves. In order to stabilize the laser light quantity during
formation of an electrostastic latent image, the LD Board monitors the
intensity of the laser beam to adjust it to the appropriate level. This
process is called Auto Power Control (APC).
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Scanner
The Scanner is comprised of a Scanner Motor that rotates at a constant
speed and a Polygon Mirror that is mounted on the Motor Shaft. The laser
light output from the LD is irradiated onto the Polygon Mirror via the
Mirror. The Polygon Mirror, provided with six reflecting mirror faces,
changes the reflection angle of the laser light as it rotates by the Scanner
Motor, thereby allowing the laser light to scan the drum along its axial
direction. Scanning is performed using one reflecting mirror face for each
line.
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Start of Scan (SOS) Board
The SOS Sensor on the SOS Board converts incoming laser beam, upon
detection, to an electric signal as reference for starting scanning, and
transmits this signal to the MCU Board. The SOS sensor signals are used
to synchronize the starting point of the laser beam scanning with the
starting point of the image writing.
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Lenses
The laser light reflected from the Polygon Mirror reaches the drum surface
via the Lenses, Mirror, and Window. The Lenses correct aberration.
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Mirror
The Mirror directs the laser beam and secure an optical path.
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Window
The window prevents debris from entering into the Laser Unit.