Canon LBP-1120 Service Manual page 47

CHAPTER 2
An AC bias is applied to the developing cylinder to help project the toner particles to the drum surface and improve
the contrast of the printed image. The center voltage of the AC bias (1460 Vp-p) varies with the developing DC bias.
This printer changes the developing DC bias value according to the IMAGE DENSITY DATA signal sent from the
interface controller. The changes of the developing DC bias value makes the potential difference between the cylinder
and drum so that the density of the print can be adjusted.
3. Transfer Stage
In the transfer stage, the toner image is transferred from the drum surface onto the paper.
Step 4: Transfer
Positive charges are applied to the back of the paper to attract the negatively charged toner particles to the paper.
Step 5: Separation
The elasticity of the paper causes it to separate from the drum (curvature separation).
To stabilize the paper feed system and to prevent droplets on the printed image at low temperature and low humidity,
the charge on the back of the paper is reduced by the static charge eliminator.
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Photo-
sensitive
drum
Transfer charging roller
Figure 2-4-10
Photo-
sensitive
drum
e
Static charg
eliminator
Transfer charging roller
Figure 2-4-11
Paper
Paper