IMAGE FORMING DEVICE, IMAGE FORMING UNIT ATTACHED TO IMAGE FORMING DEVICE AND METHOD FOR CALCULATING EXCHANGING TIME OF IMAGE FORMING UNIT

摘要

PROBLEM TO BE SOLVED: To detect with simple constitution that an image forming unit is in an initial state. SOLUTION: The storage chamber 17 of this image forming unit 2 is filled with initial toner. A developing device 14 is provided with a toner cartridge attaching part 22 to which a toner cartridge to be replenished with the toner later is attached. When the unit 2 is in the initial state, a cover plate 26 (initial set member) which can be replaced by the toner cartridge is attached to the attaching part 22. The plate 26 is equipped with a projected piece which does not exist in the toner cartridge so as to discriminate that the unit 2 is in the initial state by the use of the projected piece.