Canon i-SENSYS D450d, Service Manual, Page: 82 / 182

Chapter 6
6-2
2) Developing block
Put the toner on the electrostatic latent image on the surface of the photosensitive drum to visualize
Step 3: Development
3) Transfer block
The toner image on the surface of the photosensitive drum is transferred to papers.
Step 4: Transfer (Transfers the toner on the photosensitive drum to a paper)
Step 5: Separation (Separates the paper from the photosensitive drum)
4) Fixing block
The toner image is fixed on the paper.
Step 6: Fixing
5) Drum cleaning block
The residual toner on the photosensitive drum is removed.
Step 7: Drum cleaning (Removes the residual toner on the photosensitive drum)
6.2 Driving and Controlling the High-Voltage System
6.2.1 Generation of Transfer Charging Bias
0020-2693
i-SENSYS MF4300dn / i-SENSYS MF4350d / i-SENSYS MF4380dn / i-SENSYS MF4310/4318 / i-SENSYS MF4320d / i-SENSYS MF4330d / i-SENSYS
MF4340d / i-SENSYS D450d / i-SENSYS MF4370dn
The transfer charging bias (TRS) is output to transfer the toner on the photosensitive drum to papers.
There are transfer charging DC positive bias and transfer charging DC negative bias generated at the transfer charging bias generation circuit in the high-voltage
power supply circuit. The transfer charging DC positive bias is output to the transfer charging roller at transferring the toner. The transfer charging DC negative
bias is applied to the transfer charging roller at cleaning the transfer charging roller.
The transfer charging bias generation circuit applies these transfer charging biases to the transfer charging roller according to each print sequence.
The following are the biases for print sequences.
- Cleaning bias:
This is the bias for transferring the toner on the photosensitive drum to the paper at the time of print sequence. The transfer charging DC positive bias is applied to
the transfer charging roller.
- Sheet-to-sheet bias:
This is the bias to prevent the residual toner on the photosensitive drum from being attracted to the transfer charging roller, at between sheets during continuous
printing. Faint transfer charging DC positive bias is applied to the transfer charging roller.
- Cleaning bias:
This is the bias to return the residual toner on the transfer charging roller to the photosensitive drum at the time of warm-up or last rotation sequence. The transfer
charging DC negative bias is applied to the transfer charging roller.
The transfer charging DC positive bias is changed due to the instruction of the DCNT PCB. To realize appropriate transfer density, the DCNT PCB changes the
voltage of the transfer charging DC positive bias for constant current control according to the transfer current feedback signal (TRCRNT) sent from the transfer
charging bias generation circuit.