Konica Minolta BIZHUB 25E Field Engineering Manual page 61

2.3.5 Development mechanism
The static image created in exposure step is developed through toner adherence. The toner is transferred
using the potential difference between the drum potential and developing bias charged on transfer roller.
The exposed area on the drum surface has higher potential (VL) than the developing bias (Vb) that makes
the toner transfer from the developing roller to the drum surface. The potential of the non-exposed area
keeps the exposing potential (Vo) that is lower than the developing bias (Vb), so the toner does not transfer
to the drum surface.
Non-exposed area
Exposed area
Non-exposed area
2.3.6 Transfer mechanism
A specific amount of electric is applied to the transfer roller by a constant current control, and negatively
charged toner on the drum surface is transferred to the paper by electrostatic force. The transfer voltage is
controlled by paper size, paper type, simplex/duplex printing, temperature and humidity. The residual toner
on the transfer roller is cleared by applying negative transfer voltage.
3
No.
1 Transfer roller
3 OPC drum
Vo
VL
Vo
Toner
2
Part name
Developing roller
Bias potential
Vb
No. Part name
2 Paper
2-13
Vo<Vb
Toner does not transfer
VL>Vb
Toner transfers
Vo<Vb
Toner does not transfer
Paper feeding direction
1