Read Sharp MX-M850 (serv.man22) Service Manual online
MX-M1100 DEVELOPING SECTION K – 2
2. Operational descriptions
Toner and carrier in the developing unit are mixed and transported.
At that time, toner is charged negatively by mechanical contact with
carrier.
This process is known as triboelectrification. The suffix tribo means
to rub in Greek, thus triboelectrification simply means to electrify (or
charge) by rubbing, or by contact. Interestingly, it is not friction that
results in the charging process, but rather a chemical reaction that
occurs between the two dissimilar materials. By rubbing the two
materials together a larger surface area is contacted resulting in a
greater exchange in charge.
In addition, the developing bias voltage is applied to the developing
roller.
Negatively charged toner is attached to the exposed section on the
OPC drum surface (where the negative potential is reduced) by the
developing bias voltage.
On the other hand, the surface potential of the non-exposed sec-
tion on the OPC drum surface is higher than the developing bias,
and toner is not attached to that section. Through this operation,
visible images are formed on the OPC drum with toner.
At that time, toner is charged negatively by mechanical contact with
carrier.
This process is known as triboelectrification. The suffix tribo means
to rub in Greek, thus triboelectrification simply means to electrify (or
charge) by rubbing, or by contact. Interestingly, it is not friction that
results in the charging process, but rather a chemical reaction that
occurs between the two dissimilar materials. By rubbing the two
materials together a larger surface area is contacted resulting in a
greater exchange in charge.
In addition, the developing bias voltage is applied to the developing
roller.
Negatively charged toner is attached to the exposed section on the
OPC drum surface (where the negative potential is reduced) by the
developing bias voltage.
On the other hand, the surface potential of the non-exposed sec-
tion on the OPC drum surface is higher than the developing bias,
and toner is not attached to that section. Through this operation,
visible images are formed on the OPC drum with toner.
A. Developing bias voltage
Immediately after starting rotation of the OPC drum and when the
developing roller is stationary, the reverse bias (positive voltage) is
applied to the developing roller, preventing unnecessary toner from
attaching to the OPC drum.
developing roller is stationary, the reverse bias (positive voltage) is
applied to the developing roller, preventing unnecessary toner from
attaching to the OPC drum.
By changing the developing bias voltage control signal (XDVPWM)
duty, the polarity and the output voltage are controlled.
duty, the polarity and the output voltage are controlled.
The developing bias voltage ON/OFF is controlled with the signal
XDVREM.
The toner density sensor (TCS) is provided in the lower section of
the developing section to always detect the toner density.
This signal is inputted to the PCU PWB, which controls the toner
supply quantity from the toner hopper and the toner bottle so that
the proper density is always maintained.
XDVREM.
The toner density sensor (TCS) is provided in the lower section of
the developing section to always detect the toner density.
This signal is inputted to the PCU PWB, which controls the toner
supply quantity from the toner hopper and the toner bottle so that
the proper density is always maintained.
3. Disassembly and assembly
A. Development unit
(1) Development unit
1)
Open the front cover (a), and pull out the toner tray (b) slightly.
Operation mode
Output voltage
COPY
-500v
PRINTER
-500v
FAX
-500v
When not developing
+150v
OPC drum
CTL
CGL
Aluminum
layer
layer
TCS
Developing
mode
mode
Cleaning
mode
mode
DVBS
-500v
+150v
Unit
Parts
Page
Development unit
A
ATC sensor
K - 3/a
A
a
b
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