Read Sharp AR-810 (serv.man16) Service Manual online
AR-651/810 DEVELOPER UNIT 12 - 2
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 of the
electrically conductive ferrite which ranges in size from 30~100µm and the toner is made up of
the resin particles ranges in size from 5~20µm. Since the developer material gets deteriorated
over time with use, regular replacement is needed.
b. Mixer unit
When stirring the developer material, the carrier and toner create a static charge when mixed,
the carrier develops a positive (+) charge and the toner develops a negative (–) 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 must remain constant. The auto-toner sensor detects the toner ratio in the
developer material via the magnetic bridge circuit and supplies 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 starts to run short.
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