Transfer Unit; Outline Of The Transfer Unit; Outline; Controlling The Transfer Bias - Canon iR3245 Series Service Manual

7.9 Transfer Unit

7.9.1 Outline of the Transfer Unit

7.9.1.1 Outline

iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
The transfer unit [1] consists of the transfer roller and the static eliminator.
The transfer roller rotates in connection with the photosensitive drum.
Bias is applied to the static eliminator so that sheets can be separated from the drum.

7.9.2 Controlling the Transfer Bias

7.9.2.1 Transfer Roller Bias Control

iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
The machine changes the output of transfer bias based on the following conditions.
Environment: 5 settings according to absolute moisture content
Paper type: plain paper, envelope, thick paper, tracing paper, postcard, transparency, bond paper, label sheet
Paper width: size boundaries as defined by 2 points
Source of paper: feeding from cassette, automatic double-sided feeding from cassette, feeding from multi-feeder, i.e., 1st side (half-speed), 2nd side (half-speed)
The transfer bias is applied at the time of image formation. A voltage of a specific level is applied between sheets for cleaning of the transfer roller.

7.9.3 Cleaning

7.9.3.1 Transfer Roller Cleaning Mechanism

iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
The machine uses the transfer roller cleaning mechanism to return the toner sticking to the transfer roller back to the photosensitive drum by applying a cleaning
bias to the roller.
Once the toner reaches the drum, it is scraped by the photosensitive drum cleaning blade for collection in the waste toner box.

7.9.4 Separation Mechanism

7.9.4.1 Controlling the Static Eliminator Bias

iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
A different level of static eliminator bias is applied depending on the 1st and 2nd side.
A DC bias is applied between sheets while an image is being formed. (It is applied until the ongoing job is over.)
Transfer bias: 1000 to 6000 V
Transfer bias for cleaning: -2600 V
1st side: -2300 V
2nd side: -3000 V
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