Toshiba e-studio550 Service Manual page 175

12. 2. Functions
(1) Toner cartridge drive unit
The toner cartridge is filled with toner and supplies it to the developer unit with the driving of the new
toner supply motor.
(2) Toner recycle unit
This copier takes a toner recycle method. The toner recovered from the drum surface with the
cleaner is transported to the developer unit by the toner recycle unit and then reused.
(3) Developer unit
a. Developer material
The developer material consists of the carrier and toner. The carrier is made up with the
electrically conductive ferrites which size is as big as 30~100µm and the toner is made up with
the resin particles which size is as big as 5~20µm. Since the developer material gets deteriorated
after a long time of use, regular replacements are needed.
b. Mixer unit
When stirring the developer material, the carrier and toner are frictionized each other, causing
the carrier to have a positive (+) charge and the toner to have a minus (–) charge. The toner
adheres to the drum surface as a result of the electrostatic force.
c. Paddle
The paddle supplies the developer material stirred with the mixer unit to the transport sleeve and
gets the material separated from the lower developer sleeve back to the mixer.
d. Transport sleeve/Developer sleeve (magnetic roller)
These rollers are made of aluminum each having a magnet inside. With this magnet, the developer
material is absorbed to form the magnetic brush. The magnet is fixed, so only its ambient sleeve
rotates. By this rotation, the developer material is transported to the developer sleeve from the
transport sleeve. Then the magnetic brush formed at the developer sleeve moves on the drum
surface like a sweeping broom and the development is carried out.
e. Doctor blade
This is for controlling the amount of the developer material which is to be transported from the
transport sleeve so that the magnetic brush can get in touch with the drum surface properly.
f. Auto-toner sensor
To output a normal image, the proportion (toner density ratio) of the carrier and toner in the
developer material needs to be always constant. The auto-toner sensor detects the toner ratio in
the developer material with applying the magnetic bridge circuit and suppies the toner from the
toner cartridge and recycle toner hopper by driving the new toner supply motor and recycle toner
hopper motor when the toner becomes to be run short.
e-STUDIO550/650/810 DEVELOPER UNIT 12 - 2 JUNE 2002 © TOSHIBA TEC