Fuji Xerox Phaser 5500, Service Manual

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Theory of Operation 2-15
Paper Level Sensing
As paper is fed from the tray, the paper level drops. When the paper level reaches a
certain point, an actuator unblocks the Level Sensor signaling the control logic to stop
paper feed and raise the tray bottom. Raising the tray bottom pushes the paper up to
achieve optimum force against the Feed Roller and blocks the Level Sensor resuming
paper feed. This loop continues until the No Paper sensor is activated. Paper level
sensing operates the same way for Trays 2 through 6. Tray 1 uses No Paper sensing
only.
Paper Present Sensing
When the last sheet is fed from any of the trays, the No Paper Sensor actuator drops
into an opening in the paper tray, unblocking the sensor. Feeding is inhibited until
paper is loaded into the tray.
Xerographics
Drum Cartridge
The Drum Cartridge is located behind the Front Door and is a customer-replaceable
item. The Drum Cartridge has a maximum drum cycle count of 240,000. The number
of drum cycles per page and the prints available varies according to the customer’s
usage patterns. The Drum Cartridge Life specification of 60,000 prints is based on an
average job length of six, single-sided pages.
As an example of how job length effects the Drum Cartridge Life count, a continuous
print job having a job length of 500 to 1000 pages results in a drum cycle count of 3.2
cycles per page. At 3.2 drum cycles per page, the Drum Cartridge Life count increases
to 75,000 prints. However, if the customer were to print mostly single page jobs, the
drum cycle count increases to 7.68 drum cycles per page reducing the Drum Cartridge
Life count to 31,250 prints.
To better understand how the Drum Cartridge operates, the name and function for
each Drum Cartridge component is listed below.
Drum Cartridge Components
Component Function
Drum The Drum is an aluminum cylinder coated with a layer of photo-
conductive material that retains electrical charges on its surface
until exposed to light, when electrical conduction occurs.
Bias Charge Roller (BCR) The BCR uniformly distributes electrical charges over the drum
surface, and erases the previous charge pattern.