To stably and accurately detect a toner decreasing process with simple constitution.
In a state where toner D in a developer tank 41 is decreased to be under a fixed level, the vicinity of the edge of a flexible member 53 slides on the surface of the toner D, and a body to be detected 54 also slides and moves on the surface of the toner D. Furthermore, when the toner D in the tank 41 is gradually decreased and the level of the surface of the toner D is gradually lowered, the position of the body to be detected 54 sliding and moving on the surface of the toner D is also gradually lowered, so that a distance between the body to be detected 54 and an electrostatic capacity sensor 55 is shortened. An electrostatic capacity detection circuit 68 inputs the detection output of the sensor 55 so as to detect electrostatic capacity between the body to be detected 54 and the sensor 55. The electrostatic capacity is changed in accordance with the distance between the body to be detected 54 and the sensor 55. Therefore, the residual amount of the toner D is detected based on the electrostatic capacity.
SUDO TERUTAKA
ISHII HIROSHI
