IMAGE FORMING APPARATUS

To prevent an image defect due to contact of a toner supply roller and a developing roller with each other in an image forming apparatus.SOLUTION: An image forming apparatus has: an image carrier; a developing member that supplies a developer having a normal polarity; a developer supply member that supplies the developer to the developing member; and a control unit that applies a first voltage to the developing member and a second voltage to the developer supply member. The control unit can execute an image forming operation, a first rotation operation in which the developer supply member rotates with the first voltage having the normal polarity being applied thereto and the potential difference is a first potential difference, and a second rotation operation in which the second voltage having the same polarity as the normal polarity and having a larger absolute value is applied and the developing member and the developer supply member rotate with the potential difference being a second potential difference. When the potential difference during image formation is a third potential difference, the control unit controls the magnitude of the potential difference for directing the developer having the normal polarity from the developer supply member toward the developing member so that the first potential difference becomes smaller than the third potential difference and the second potential difference becomes larger than the third potential difference.SELECTED DRAWING: Figure 3 【課題】画像形成装置のトナー供給ローラと現像ローラが接触することに起因する画像不良を抑制する。【解決手段】画像形成装置において、像担持体と、正規極性の現像剤を供給する現像部材と、現像部材への現像剤供給部材と、現像部材に第１の、現像剤供給部材に第２の電圧を印加させる制御部を有し、制御部は、画像形成動作と、正規極性の第１の電圧が印加された状態で現像剤供給部材が回転する回転動作であって、電位差が第１の電位差の第１の回転動作と、正規極性と同極性で絶対値が大きい第２の電圧が印加され、電位差が第２の電位差の状態で現像部材と現像剤供給部材が回転する第２の回転動作を実行させ、画像形成時の電位差を第３の電位差としたとき、制御部は、正規極性の現像剤を現像剤供給部材から現像部材に向かわせる電位差の大きさが、第３の電位差よりも第１の電位差の方が小さく、第３の電位差よりも第２の電位差の方が大きくさせる。【選択図】図３