Canon Color imageRUNNER LBP5280, Service Manual, Page: 25 / 284

2
2
2-6
2-6
Technical Reference > Image Formation System > Construction > Transfer block
Technical Reference > Image Formation System > Construction > Transfer block
■
Latent image formation block
During the two steps that comprise this block, an invisible latent image is formed on the
photosensitive drum.
Step 1:Primary charging
To prepare for latent image formation, the surface of the photosensitive drum is charged with
a uniform negative potential. The primary charging roller charges the photosensitive drum
directly. The primary charging bias is applied to the primary charging roller to keep a negative
potential on the drum surface.
Photosensitive Drum
Primary Charging Roller
DC bias
Step 2: Laser-beam exposure
The laser beam scans the photosensitive drum to neutralize the negative charge on portions
of the drum surface. An electrostatic latent image forms where the negative charge was
neutralized.
Laser beam
Unexposed area Exposed area
F-2-5
F-2-6
■
Developing block
Toner adheres to the electrostatic latent image on the photosensitive drum, which becomes
visible.
Step 3: Developing
Toner acquires a negative charge from the friction that occurs when the developing roller
rotates against the developer blade. The developing bias is applied to the developing roller
to make difference in the electric potential of the drum. When the negatively charged toner
comes in contact with the photosensitive drum, it adheres to the latent image because the
drum surface has a higher potential.
Developing Cylinder
Photosensitive Drum
Exposed
area
Exposed
area
Exposed
area
Unexposed
area
Unexposed
area
Unexposed
area
Developing Blade
DC negative bias
■ Transfer block
During the three steps that comprise this block, a toner image on the photosensitive drum
transfers to the print media through the ITB.
Step 4: Primary transfer
The toner image on the photosensitive drum is transferred to the ITB. The DC positive bias
is applied to the primary transfer pad. The negatively charged toner transfers to the ITB from
the drum surface.
F-2-7