Toshiba e-studio550 Service Manual page 151

10. 2. Functions
(1) Drum
The drum is a cylindrical aluminum base which is applied the organic photosensitive material
(photoconductor) thinly on it. The photoconductor becomes insulative (low-electric resistance) at the
dark places (out of the light) while it becomes conductive (high-electric resistance) under the light, so it
is called a photoconductor.
(2) Main charger
The main charger is configured by stretching a charger wire between two insulation blocks provided at
both ends of the U-shaped metal rod.
When a high voltage is applied to the charger wire, the air around the wire is ionized (electrostatically
charged), and this ionized air is attracted onto the drum's surface. This phenomenon is referred to as
the "corona discharge". In the dark, the surface of the drum is negatively (–) charged by the corona
discharge of the main charger.
(3) Charger wire cleaner
The charger wire cleaner is for removing stain on the charger wire. It moves backward and forward to
clean the charger wire after the power is turned ON and more than 2000 continuous copies have been
made since the door switch was turned ON or the previous cleaning operation.
(4) Discharge lamp
Discharging is a process of reducing or eliminating the electrostatic charges on the drum.
The discharge lamp has two effects, a cleaning effect and pre-exposure effect. By the cleaning effect, it
neutralizes and eliminates the residual charges on the drum surface by lowering the electrical resis-
tance of the photosensitive surface by exposing it to the light, and by the pre-exposure effect, it keeps a
fixed drum surface potential before the charging process.
(5) Ozone filter
The ozone filter decomposes ozone with its catalyst by absorbing the ozone, which has been gener-
ated through the corone discharge of the main charger, by the exhaust fan and letting it through the
ozone filter.
(6) Surface potential sensor
The surface potential sensor detects the surface potential of the photoconductive drum and controls it
to keep constant.
e-STUDIO550/650/810 PROCESS RELATED SECTION 10 - 2 JUNE 2002 © TOSHIBA TEC