An image forming device includes a storage device that stores toner, an agitator
that agitates the toner in the storage device, a detector that detects an amount
of toner in the storage device, and a controller that prohibits an operation of
the agitator when the detected amount of toner is equal to or more than a prescribed
amount, and permits the operation of the agitator when the amount of toner is less
than the prescribed amount. A controller circuit sets a voltage level based on
the amount of toner and a biasing circuit impresses the voltage to a developing
roller, a supply roller and a regulating blade.
