Photosensitive Drum; Pre-Transfer Exposure Led (Addition) - Canon iR8500 Service Manual

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7.3 Photosensitive Drum

The machine's photosensitive drum has a higher degree of charging ability than that of the

The machine uses processing speed of 450 mm/sec (as opposed to 300 mm/sec of the

GP605), to enable the generation of 85 copies per minute (iR8500: A4, Direct), in the case

of the iR7200, 72 copies per minute because of the increased distance between sheets.

To make up for the reduction in the strength of charging on the photosensitive drum, the

machine uses a photosensitive drum with a higher charging ability. The wave length of the

light emitted by the pre-exposure lamp is 660 nm, made shorter to eliminate residual

charges and to ensure a specific volume of charge.

In addition, to make up for the possible decrease in the power of separation caused by a

higher process speed, the following pre-transfer exposure LED is used:

Pre-Transfer Exposure

Wave length:

Timing of activation: The LED is kept ON between a point in time 100

At the beginning of the transfer process, the photo-

sensitive drum potential (white background poten-

tial) is reduced by removing charges, and the static

bond between the photosensitive drum and the

transfer medium is weakened to facilitate separation.

msec before the leading edge of the image reaches

the point of light emission of the LED and a point in

time when the trailing edge of the image moves past

it (See F02-701-02).

2000 2000 2000 2000

CANON iR8500/7200 REV.1 AUG. 2001

CHAPTER 2 NEW FUNCTIONS

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