Canon imageCLASS LBP325dn Service Manual page 38

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.
● Drum discharge
The drum discharge is a feature to remove residual charge on the Photosensitive Drum surface for preventing the uneven image
density.
The Laser Beam strikes the surface of the Photosensitive Drum to remove the residual charge.
The drum discharge is performed during LSTR period.
■ 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 developing blade.
The negatively charged toner is attracted to the latent image on the photosensitive drum surface because the drum surface has
a higher potential. The developing bias is applied to the developing roller.
Unexposed
Unexposed area
Blade
Developing roller
Exposed
area
area
Photosensitive drum
Laser beam
Exposed area
Unexposed
area
Exposed
Developing bias
area
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2. Technical Explanation (Device)