Chapter 23: Theory Of Operation - Lexmark C720 User Reference Manual

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Theory of operation
By understanding how the toner cartridges, photo developer cartridge, transfer drum, transfer roller,
and fuser interact you can understand why problems occur and how to correct or prevent them.
Output tray
Photo developer cartridge
Fuser
Toner cartridges
Transfer roller
Laser emitter
Transfer drum
Paper trays
Photo developer charger
The green film inside the photo developer is a belt that makes a continuous loop as your printer
operates. The photo developer charger (the thin wire on the bottom of the photo devleoper), places a
uniform negative charge on the surface of the green film (photo developer media) as the media travels
past the photo developer charger.
As the media moves toward the toner cartridges it passes the laser emitter inside your printer. The
information you send to your printer is changed into a laser-emitted signal. This signal is projected onto
the photo developer media and discharges portions of the media.
The discharged areas on the photo developer media pull negatively charged toner particles from the
toner cartridges into the discharged areas on the photo developer media.
As the photo developer media rotates, it meets the transfer drum. The transfer drum has a uniform
neutral charge on it. When the transfer drum and photo developer meet, the image on the photo
developer media moves from the media onto the transfer drum.
As the transfer drum rotates toward the rear of the printer, the paper is pulled from the paper tray and
travels up the paper path to meet your image. The paper or other media (such as transparencies or
envelopes), arrives at the transfer roller and transfer drum just prior to your image.
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