CHAPTER 2

1. Electrostatic latent image formation stage

This stage follows two steps to produce an electrostatic latent image on the photosensitive drum. At the end of the stage, negative charges remain on the unexposed “dark” areas, where the

laser beam struck (exposed) the drum surface.

This image of negative charges on the drum is invisible to the eye, so it is referred to as an called an “electrostatic latent image.”

Surface potential (V)

0 -100

-500

Time (t)

Exposed area

Unexposed area

Primary

Scanning

Transfer

Primary

charge

exposure

(step 4)

charge

(step 1)

(step 2)

 

(step 1)

Figure 2-4-5

Step 1 Primary charge

Primary charging roller

AC bias

Photosensitive drum

DC bias

Figure 2-4-6

For preparation of the latent image formation, a uniform negative potential is applied to the pho- tosensitive drum surface. For primary charge, the printer uses the charging method, which directly charges the drum.

The primary charging roller is made of conductive rubber. In addition to DC bias, AC bias has been applied to the primary charging roller to keep the potential on the drum’s surface uni- form. The DC bias is changed with the developing DC bias.

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Image 76
Canon 3260 manual Electrostatic latent image formation stage, Primary charge