Patent ID: 7715745

Claim:
An image forming apparatus, comprising: a belt; a plurality of support rollers which rotatably supports the belt; a plurality of photosensitive media, each having a surface on which a visible toner image is formed by charged toner; a plurality of transfer rollers disposed adjacent to the photosensitive media with the belt interposed therebetween; a power supplying part which supplies power to at least two of the plurality of transfer rollers so that a surface of the at least two of the plurality of transfer rollers have an electrical potential; and a control part which controls the power supplying part to supply a pulse power which has a middle power level having a same polarity as a polarity of the charged toner to the at least two of the plurality of transfer rollers so that the charged toner remaining on the belt is transferred back to at least one of the plurality of photosensitive media; wherein the at least two of the plurality of transfer rollers have electrical resistances which increase along a direction in which a printing medium is transferred past the photosensitive media by the belt.