Sharp SF-2014 Service Manual page 33

Low intensity in
the area corre-
sponding to the
darker density
portion of the
document
CTL
CGL
Aluminum
layer
Surface potential
(High)
CTL
CGL
Aluminum
layer
Step 5 (Development)
Toner is attached to the latent static-electricity images on the drum
surface to change them to visible images. The two-component mag-
netic brush development system charges toner positively by friction
with carriers, and toner is attached to negative charges on the drum
surface. The potential in the darker document projecting area (low
intensity) is high (much negative charges) and attracts more toner.
The potential in the lighter document projecting portion (high inten-
sity) is low (less negative charges), and attracts less toner.
OPC drum
Aluminum layer
Higher surface
potential
(Much negative
(charges)
Medium surface
potential
(Less negative
(charges)
Lower surface
potential
(No negative
(charges)
At that time, a bias of –200V is applied to the MG roller (magnet
roller), which is provided for preventing toner from being attracted by
the residual voltage (about –80V to –100V) in the lighter portion after
exposure.
HIgh intensity in
Medium intensity
in the area corre- the area corre-
sponding to the sponding to the
medium density lighter density of
portion of the the document
document
OPC drum
Surface
potential
Surface
(Medium)
potential
(Low)
OPC drum
CGL CTL
MG roller
High voltage unit
bias voltage
Main corona unit
Discharge lamp
Cleaning blade
Seperation pawl
Main corona unit
Discharge lamp
Cleaning blade
Seperation pawl
-200V
5 – 9
Blank lamp
Seperation corona unit Transfer corona unit
Blank lamp
Seperation corona unit Transfer corona unit
Developer unit
MG roller
Resist roller
Developer unit
MG roller
Resist roller