Image forming apparatus controlling image forming conditions based on detected toner concentration before and after stoppage

Abstract

An image forming apparatus is provided with a function for forming an image on a recording medium such, as a sheet or the like. The image forming apparatus includes an image forming unit for forming an image on a recording material including an image bearing member. A developing unit develops an electrostatic image formed on the image bearing member by a developer. A density detection unit detects a developer density inside the developing unit. The density detection unit detects a parameter relating to physical property of the developer based on a previous detection value detected by the density detection unit during a previous image forming drive operation by the image forming unit and before the previous image forming drive operation stops. The detection unit also detects a next detection value detected by the density detecting unit after the previous image forming drive operation stops and before a next image forming drive operation by the image forming unit starts. Accordingly, the image forming condition of the next image forming drive operation is controlled to be variable by a control unit based on the detection values.