Sharp AR-BC260 Service Manual page 54

• LED unit composition
Item
Print width
Total number of dots
Resolution
LED Number of LED chips
composition
Number of dots
Lens
c. OPC drum section operations
The OPC drum surface is charged negatively by the main charger,
and LED light of images are radiated onto the OPC drum surface
by the LED (writing) unit to form electrostatic latent images.
1) The OPC drum surface is negatively charged by the main
charger.
High voltage unit
CTL
CGL
Aluminum
layer
The screen grid is attached to the main charger unit. The OPC
drum is charged at a voltage nearly same as the voltage
applied to the screen grid.
2) LED light is radiated onto the OPC drum surface by the LED
(writing) unit to form electrostatic latent images.
LED light
OPC drum
When LED light is radiated onto the OPC drum CGL, positive
and negative charges are generated. Positive charges gener-
ated in the CGL are attracted and moved by negative charges
of the OPC drum, and negative charges by positive charges of
the aluminum layer of the OPC drum. Therefore, on the OPC
drum surface and in the aluminum layer, positive and negative
charges are neutralized, reducing the OPC drum surface
potential.
Electric charges remain in the areas where LED light is not
radiated onto the OPC drum.
As a result, electrostatic latent images are formed on the OPC
drum surface.
Charges are disposed in direct proportion to the amount of
light received.
Content
314mm
7424 dot
600dpi
58 chip
128 dot
Selfoc lens
Main corona unit
Screen grid
OPC drum
OPC drum
CTL
CGL
Aluminum
layer
AR-BC260 DESCRIPTIONS OF EACH SECTION 7 - 17
3) Clean and remove residual toner from the OPC drum with the
cleaning blade after transfer operations.
Removed residual toner is transported to the waste toner sec-
tion of the toner cartridge by the waste toner transport screw.
4) The whole surface of the OPC drum is discharged.
Lens
CTL
CGL
Aluminum
layer
By radiating discharge lamp light onto the discharge lens, light
is radiated through the discharge lens to the OPC drum sur-
face.
When discharge lamp light is radiated onto the OPC drum
CGL, positive and negative charges are generated.
Positive charges generated in the CGL are attracted and
moved by negative charges of the OPC drum, and negative
charges by positive charges of the aluminum layer of the OPC
drum. Therefore, on the OPC drum surface and in the alumi-
num layer, positive and negative charges are neutralized,
reducing the OPC drum surface potential, preparing the drum
surface for the new copy cycle.
OPC drum
CTL
CGL
Aluminum
layer