Inventors:
Steven Lewis Applegate - Lexington KY
Cyrus Bradford Clarke - Lexington KY
Timothy Philip Craig - Georgetown KY
David Lee Merrifield - Lexington KY
James John Molloy - Lexington KY
Benjamin Keith Newman - Lexington KY
Gary Scott Overall - Lexington KY
Gregrory Lawrence Ream - Lexington KY
Thomas Gregrory Survant - Lexington KY
Thomas Campbell Wade - Lexington KY
Phillip Byron Wright - Lexington KY
Assignee:
Lexmark International, Inc. - Lexington KY
International Classification:
G03G 1508
Abstract:
An improved electrophotographic (EP) printer is provided having a detachable process cartridge that contains a non-volatile memory device, which is an EPROM that cannot be erased after a bit is burned. A "toner wheel" mounted to the exterior of the toner reservoir of the process cartridge provides, in conjunction with an optoelectronic sensor, an electrical signal that the printer receives and uses to determine toner usage. A toner "gas-gauge" is created which uses "bucket levels" as discrete steps to indicate how much of the measured physical toner material actually remains within the toner reservoir. After a given amount of toner material has been dispensed through the developer unit, one of the bits of the EPROM memory device is irreversibly burned, thereby providing a permanent record on the process cartridge of a certain amount of toner usage. As with a normal automobile gas gauge, the toner gas-gauge reading should never increase unless the amount of toner material inside the toner reservoir has increased. Once the bucket level transitions begin to occur for the toner gas-gauge, the printer becomes aware that a majority of the toner material has been expended from inside the toner reservoir.