Image Transfer And Paper Separation; Pre-Transfer Lamp (Ptl) - Ricoh FW830 Service Manual

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31 December 1992

IMAGE TRANSFER AND PAPER

SEPARATION

[A]

[B]

After the latent image is developed but before the image is transferred to the

copy paper, the drum surface is illuminated by the pre-transfer lamp [A]. This

illumination reduces the negative potential on the drum surface. This

prevents the toner particles from being re-attracted to the negatively charged

drum during the paper separation process. It also makes image transfer and

paper separation easier.

5.2 IMAGE TRANSFER

The registration rollers [B] feed the copy paper through the transfer entrance

guides to the transfer section. A high negative voltage (about –5.0 kV) is

applied to the transfer corona wire [C], and the corona wire generates

negative ions. These negative ions are applied to the copy paper, and the

negative charge attracts the positive charged toner away from the drum and

onto the paper. In addition, the paper is held against the drum by the positive

counter charge on the drum.

5.3 PAPER SEPARATION

After image transfer, the copy must be separated from the drum. To break

the attraction between the paper and the drum, the separation corona wires

[D] apply an ac corona (4.0 kV) to the reverse side of the paper. The stiffness

and weight of the paper causes it to separate from the drum.

The separation corona has a negative component of approximately –200

volts. This negative component holds the toner on the paper to prevent it

from being reattracted to the drum during paper separation. The two pick-off

pawls [E] ensure that thin paper, paper with low stiffness, or upward curled

paper separates completely from the drum.

IMAGE TRANSFER AND PAPER SEPARATION

[D]

[C]

2-29

[E]

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