HP 3390 Service Manual - Page 116

Step 3: Developing, Step 4: Transfer,

Page 116 highlights

The laser beam scans the photosensitive drum to neutralize negative charges on parts of the drum. An electrostatic latent image is formed on the drum where negative charges were neutralized. Step 3: Developing The developing cylinder comes in contact with the photosensitive drum to deposit toner onto the electrostatic latent image. NOTE The charges on the exposed area of the drum are shown as positive in Figure 4-9 Developing on page 94. The charges are actually negative, but they are more positive than the charges on the developing cylinder. Figure 4-9 Developing Toner acquires a negative charge through friction from the developing cylinder and the blade. When the negatively charged toner comes in contact with the drum, the toner adheres to the electrostatic latent image. The image on the drum becomes visible because of the toner. Step 4: Transfer The transfer charging roller, to which a dc positive bias is applied, imparts a positive charge on the print media. When the print media comes in contact with the photosensitive drum, the toner is transferred to the print media. 94 Chapter 4 Theory of operation ENWW

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The laser beam scans the photosensitive drum to neutralize negative charges on parts of the drum. An
electrostatic latent image is formed on the drum where negative charges were neutralized.
Step 3: Developing
The developing cylinder comes in contact with the photosensitive drum to deposit toner onto the
electrostatic latent image.
NOTE
The charges on the exposed area of the drum are shown as positive in
Figure 4-9
Developing
on page
94
. The charges are actually negative, but they are more positive than
the charges on the developing cylinder.
Figure 4-9
Developing
Toner acquires a negative charge through friction from the developing cylinder and the blade. When the
negatively charged toner comes in contact with the drum, the toner adheres to the electrostatic latent
image. The image on the drum becomes visible because of the toner.
Step 4: Transfer
The transfer charging roller, to which a dc positive bias is applied, imparts a positive charge on the print
media. When the print media comes in contact with the photosensitive drum, the toner is transferred to
the print media.
94
Chapter 4
Theory of operation
ENWW