Functions - Toshiba e-STUDIO281c Service Manual

11.3 Functions

1) Drum
Drum is made of a cylindrical aluminum base coated with thin film of organic photoconductive sub-
stance.
Photoconductive object becomes insulative (high electrical resistance) when it is not exposed to
lights and becomes conductive (low electrical resistance) when it is exposed to lights. This object is
called photoconductor.
2) Main charger
Main charger consists of a metal rod case having insulated blocks at the both ends with the charger
wire attached and the grid is set between them.
When high voltage is applied to the charger wire, the surrounding air is charged (ionized). Then a
flow of the ionized air into the drum applies the drum a charge as well. This phenomenon is called
"corona discharge" and a control bias is applied to the grid to control the charging amount. Negative
charge caused by the corona discharge is applied to the drum surface evenly in dark places.
Charger wire is equipped with an automatic wire cleaner to clean the wire.
3) Drum thermistor (THM4)
Since the photoconductive characteristic of the drum surface changes depending on the tempera-
ture of the drum surface, the drum thermistor detects the temperature of the drum surface and con-
trols to gain the charging potential according to the environment.
4) Drum cleaner
- Cleaning blade
This blade is pressed against the drum surface with a constant force by pressure springs, and
scrapes off the residual toner on the drum surface. Also it removes the positive charge on the
photoconductive drum by applying negative charge on the blade.
- Recovery blade
This blade catches the toner scraped off by the cleaning blade.
- Toner recovery auger
This auger carries the residual toner scraped off to the toner bag.
- Drum cleaner brush
This brush roller prevents the residual toner and foreign matter adhering to the drum surface.
5) Discharge LED (ERS)
Discharge is a process to decrease or eliminate the static electricity on the drum surface.
The electrical resistance of the photosensitive layer is decreased by the light, and the residual
charge on the drum surface is neutralized and eliminated (cleaned). Electrical potential of the drum
surface is fixed to a certain amount before the drum is charged.
6) Toner bag
This collects the residual toner scraped off on the drum surface by the cleaning blade and residual
toner scraped off on the transfer belt by the transfer belt cleaning blade.
7) Toner bag full detection sensor (S20)
The sensor detects the toner bag full when it is pushed by the toner recovery auger in the cleaner
which is given a pressure from the used toner in the toner bag.
"Toner bag full" is determined when the toner bag full detection sensors (S20) detects full of toner.
Printing is interrupted upon the detection of "Toner bag full" status, however, the paper already fed is
subject to be printed and exited. When the sensor is in trouble, "Toner bag full" is determined instead
of "Call for service". If "Toner bag full" status is not cleared, the sensor, harnesses and LGC board
need to be checked.
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e-STUDIO281c/351c/451c
DRUM RELATED SECTION
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