APPARATUS FOR DETECTING MAGNETIC DYE OF SINGLE COMPONENT IN DUPLICATING MACHINES

摘要

The invention relates to a device which reliably detects the absence of magnetic one-component developer in the supply container, provided therefor, of duplicators, and signals this state to the user in good time. The aim of the invention is reliable detection of the undershooting of a critical threshold of the quantity of one-component developer in electrophotographic duplicators with the aid of simple means without interfering in the supply container. The object of the invention is to provide a scanning magnetic field which produces a different effect on an element, which records magnetic fields, as a function of the presence of the one-component developer. According to the invention, use is made for this purpose of a magnetic field generator, for example embodied as an electromagnet driven in a pulsed fashion and having at its pole end an element which records magnetic fields, e.g. a Hall-effect element, it being possible to use this arrangement in the form of a probe which is placed from outside onto the developer supply container.