IMAGE FORMING APPARATUS

To provide an image forming apparatus that can accurately reduce toner fogging when the image forming apparatus is left standing for a long time.SOLUTION: An image forming apparatus comprises: developing devices that each carry developer on a surface of a developer carrier (developing roller) and develop an electrostatic latent image on a surface of an image carrier (photoreceptor drum); and a control unit 5 that controls the developing devices. The control unit 5 has: peripheral environment acquisition means that acquires a peripheral environment of the developing device; left-standing time checking means that checks the time during which the image forming apparatus is left standing; printing rate calculation means that calculates a printing rate; returning means that executes a returning operation of the developing device; returning condition determination means that determines a returning condition; and storage means that stores a tentative parameter related to the returning condition in association with the peripheral environment and the time during which the image forming apparatus is left standing. The returning condition determination means acquires the tentative parameter based on the peripheral environment and the time during which the image forming apparatus is left standing, and determines the returning condition by correcting the tentative parameter based on the printing rate.SELECTED DRAWING: Figure 3 【課題】画像形成装置が長時間放置された場合におけるトナーかぶりを精度良く低減することができる画像形成装置を提供する。【解決手段】現像剤を現像剤担持体（現像ローラ）の表面に担持して、像担持体（感光体ドラム）の表面の静電潜像を現像する現像装置と、現像装置を制御する制御部５と、を備えた画像形成装置であって、制御部５は、現像装置の周辺環境を取得する周辺環境取得手段と、画像形成装置の放置時間を計時する放置時間計時手段と、印字率を算出する印字率算出手段と、現像装置の復帰動作を実行する復帰手段と、復帰条件を判定する復帰条件判定手段と、周辺環境及び放置時間に関連付けて、復帰条件に係る暫定パラメータを記憶しておく記憶手段と、を有し、復帰条件判定手段は、周辺環境及び放置時間に基づいて暫定パラメータを取得し、暫定パラメータを印字率に基づいて補正することにより復帰条件を判定する。【選択図】図３