Dual component developing material detecting device for electrostatic copying apparatus.

摘要

A detecting device for detecting when the amount of toner in a dual component developing material is less than a predetermined level includes a hopper for supplying the toner, a stirring roller for stirring a carrier and the toner from the hopper, and a detector for detecting the amount of developing material provided near the stirring roller to mix the toner supplied from the hopper with the carrier. A discriminator discriminates an output signal from the detector for a predetermined interval during the rotational period of the stirring roller. An indicating element operates in response to the output signal from the discriminator to indicate when the amount of the toner in the developing material is less than the predetermined level. Since it is indicated when the toner in the developing material is less than the predetermined level, the toner is supplied according to such indication, and therefore, an undesirable deterioration of copy density is prevented.