IMAGE FORMING APPARATUS FOR MEASURING REFERENCE VALUE OF TONER CONCENTRATION

An image forming apparatus for measuring a reference value of a toner concentration is provided. A developing device (31) of the image forming apparatus includes a casing (64), two-component developeraccommodated in the casing (64), a stirring screw (63) for conveying and stirring the developer in the casing (64) by rotation in a predetermined direction, and a toner concentration sensor (65) thatoutputs a value indicative of the toner concentration of the developer in the casing (64). The image forming apparatus determines whether or not the developer in the casing (64) has become uniform, based on the amount of change per unit time of the output value of the toner concentration sensor (65), acquired after the stirring of the developer in the casing (64) by the stirring screw (63) is started. It is possible to appropriately measure the reference value of the toner concentration. 本发明提供种进行调色剂浓度的基准值的测定的图像形成装置。图像形成装置的显影组件(31)包括：框体(64)；双成分显影剂，收容于框体(64)内；搅拌螺杆(63)，通过旋转而向预定的方向输送框体(64)内的显影剂来搅拌；以及调色剂浓度传感器(65)，输出表示框体(64