DEVICE FOR DETECTING AMOUNT OF TONER USED

PURPOSE: To control toner particles supplied to a developing device by detecting a current for biasing a mixing device, mixing toner in the developing device in accordance with the detected result, and applying electric bias between the mixing device and the developing device so that the toner may be attracted to the developing device. CONSTITUTION: New toner particles are discharged to one end of the chamber 78 of the developing device 38 from a container 86, and a toner mixer 44 is rotated in a direction shown by an arrow 40 so as to mix and fluidize the toner particles. The toner particles are moved from one end to the other end of a housing chamber 80 by applied pressure. The electric bias, for example, 250-1,000V is impressed between a supply roller 74 and the mixer 44 by DC voltage sources 41 and 42. A controller 88 detects the current for biasing and outputs a control signal. Energizing a motor 82 is adjusted according to the control signal, and the discharged amount of the toner from the container 86 to the chamber 78 of the housing 80 by the rotation of an auger 90 is detected and adjusted.