Printer/copier with disposable toner cartridge

Claim 1

A self-contained developer unit for use in connection with an electrophotographic printing apparatus, said developer unit comprising a substantially closed housing, means for receiving a disposable cartridge containing toner, a mixing chamber wherein said toner and a carrier are mixed, means for delivering controlled amounts of toner from said cartridge to said mixing chamber, circuit means for monitoring the toner/carrier mix in said mixing chamber, means coupled to said delivering means for controlling the amount of toner delivered from said toner cartridge to said mixing chamber in response to signals generated by said circuit means, means coupled to said mixing chamber for mixing said toner with carrier particles, and means coupled to said mixing chamber for applying said toner/carrier mix to a photoconductive element to develop a latent electrostatic image, said housing substantially enclosing said disposable cartridge receiving means, said mixing chamber, said delivery means, said mixing means, and said means for applying said toner/carrier mix to said photoconductive element, and at least partially enclosing said circuit means.

Claim 20

A device for controlling the toner/carrier mix in a mixing chamber of a developing unit of an electrographic printing apparatus, comprising means for storing toner, means for delivering said toner to said mixing chamber, and circuit means for monitoring the toner/carrier mix in said mixing chamber, said circuit means comprising a magnetic core having two outer legs and a central leg, said three legs defining a pair of apertures for said core, a first outer leg of said core being in contact with said toner/carrier mix, a primary winding wound about said central leg, said primary winding carrying a primary voltage with a phase dependent upon the toner/carrier mix, a secondary winding coupling said pair of apertures, said secondary winding carrying a secondary voltage, a phase detector receiving said primary and secondary voltages and generating a voltage proportional to the phase difference between said primary and secondary voltages, a voltage comparator comparing said voltage generated by said phase detector to a reference voltage and generating a signal in response thereto, and a microprocessor receiving said signal from said voltage comparator and actuating said delivery means.

Claim 21

A device for controlling the toner/carrier mix in a mixing chamber of a developing unit of an electrographic printing apparatus, comprising means for storing toner, means for delivering said toner to said mixing chamber, and circuit means for monitoring the toner/carrier mix in said mixing chamber, said circuit means comprising a magnetic core having two outer legs and a central leg, said three legs defining a pair of apertures for said core, a first outer leg of said core being in contact with said toner/carrier mix, a primary winding wound about said central leg, said primary winding carrying a primary voltage with a phase dependent upon the toner/carrier mix, a secondary winding coupling said pair of apertures, said secondary winding carrying a secondary voltage, a phase detector receiving said primary and secondary voltages and generating a voltage proportional to the phase difference between said primary and secondary voltages, a voltage comparator comparing said voltage generated by said phase detector to a reference voltage and generating a signal in response thereto, and a microprocessor receiving said signal from said voltage comparator and actuating said delivery means.