Apparatus for monitoring developer mixture

摘要

An electrostatographic reproduction machine includes a toner concentration monitor having a resistive element through which electrical current is passed. The resistive element is heated by the electrical current. In a steady state mode, the resistive element transfers heat to its surroundings and attains a steady state temperature dependent upon the heat transfer characteristics of the surroundings. The toner concentration is detected by measuring the power into the resistive element. The heat transfer characteristics are determined by the thermal conductivity and the flow rate of the developer mixture.