DEVELOPING DEVICE, IMAGE FORMING APPARATUS, AND DEVELOPER RUNOUT DETECTION METHOD

To provide a developing device, an image forming apparatus, and a developer runout detection method that can improve accuracy in detecting runout of developer.SOLUTION: An image forming apparatus comprises: a conveying member 42 that conveys toner in a housing 41; a sensor 47 that detects the amount of toner passing through a detection position on a conveyance path of the toner conveyed by the conveying member 42; a drive processing unit that, when the amount of toner detected by the sensor 47 is equal to or less than a first reference amount, drives a supply member 46A supplying the toner from a toner container 46 to the housing 41; a detection processing unit that, when a result of detection performed by the sensor 47 does not satisfy a first specific condition from start of drive of the supply member 46A until the lapse of determination time, detects runout of developer in the toner container 46; and a switching processing unit that switches the first specific condition according to a variation value related to variation in the detection amount acquired on the basis of, the result of detection performed by the sensor 47.SELECTED DRAWING: Figure 3 【課題】現像剤切れの検出精度を向上可能な現像装置、画像形成装置、及び現像剤切れ検出方法を提供すること。【解決手段】画像形成装置は、筐体４１内のトナーを搬送する搬送部材４２と、搬送部材４２によるトナーの搬送経路における検出位置を通過するトナーの量を検出するセンサー４７と、センサー４７によるトナーの検出量が第１基準量以下である場合に、トナーコンテナ４６から筐体４１へトナーを供給する供給部材４６Ａを駆動する駆動処理部と、供給部材４６Ａの駆動開始時から判定時間が経過するまでにセンサー４７の検出結果が第１特定条件を充足しない場合に、トナーコンテナ４６における現像剤切れを検出する検出処理部と、センサー４７の検出結果に基づいて取得される前記検出量の変動に関する変動値に応じて前記第１特定条件を切り替える切替処理部と、を備える。【選択図】図３