VERFAHREN UND VORRICHTUNG ZUR MESSUNG DER TONERENTNAHME IN EINER ELEKTROFOTOGRAFISCHEN REPRODUKTIONSMASCHINE

摘要

A method and apparatus for measuring or measuring and replacing the amount of toner consumed in an electrophotographic reproduction machine wherein the method involves measuring an electrical value corresponding to the charge transferred in a copying operation by the toner to the photoconductor. The electrical value measured is the voltage at a high-resistance resistor through which current flows to the ground from an element charged with a charge corresponding to the transferred charge or the voltage at a capacitor charged from an element that is itself charged with a charge corresponding to the transferred charge or the charge flow from or to the conductive carrier material of the photoconductor. The corresponding charge is the residual charge of carrier material from which toner has been withdrawn by the photoconductor. In response to the measurement an amount of toner is dispensed to the machine which may be intermittent after and in accordance with integration of the charge transferred during the interval between dispensing operations. The apparatus includes an insulated electrically conductive element to receive a charge of the same magnitude as the charge passed to the photoconductor and a measuring instrument which is connected to a toner dispensing device dependent for delivery of toner on the measurement. The conductive element is composed of one or more well insulated deflector sheets fitted in a cascade developing unit wherein the sheets are positioned below the developing zone of the unit so that the spent developer trickles over the sheets beyond the developing zone. The apparatus may also include two toner dispensing devices one of which is dependent upon the number of copies and the other is dependent upon the charge on a capacitor.