Patent ID: 7489893

Claim:
A hybrid type developing method comprising: forming a magnetic brush from a non-magnetic toner and a magnetic carrier on a circumference of a magnetic roller using a magnetic force; forming a uniform toner layer on a circumference of a donor roller by providing only toner from the magnetic roller to the donor roller; developing an electrostatic latent image formed on an image receptor with the toner on the donor roller; dividing an area of the donor roller facing the magnetic roller into an upstream area and a downstream area with respect to a rotation direction of the donor roller as a reference direction; applying an electric field to the upstream area of the donor roller to remove toner from the upstream area of the donor roller; applying an electric field to the downstream area of the donor roller to supply toner from the magnetic roller to the downstream area of the donor roller; applying an electric field to a development area of the donor roller facing the image receptor for developing the toner from the donor roller onto the image receptor, where the electric fields applied to the upstream area and the downstream area are independent from the electric field applied to the development area, the donor roller having a plurality of spaced apart electrodes on an outer surface thereof, a first brush electrode contacting at least one of the electrodes in the upstream area, a second brush electrode contacting at least one of the electrodes in the downstream area, and a third brush electrode contacting the electrodes in the development area, and applying a recovery bias to the first brush electrode to form an electric field for removing toner from the donor roller, applying a supply bias to the second brush electrode to form an electric field to supply toner to the donor roller; applying a development bias to the third brush electrode to form an electric field for developing the toner; and wherein, if potentials of DC components of a magnetic roller bias applied to the magnetic roller, the recovery bias and the supply bias are denoted as V m , V r , and V s , respectively, when the toner is negatively charged, V r <V m <V s , and when the toner is positively charged, V s <V m <V r .