| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of exactly determining toner empty by surely detecting decrease in the concentration of toner in developer, and to provide a toner empty detection method. SOLUTION: The image forming apparatus includes: developing units 40, each of which stores developer composed of a mixture of magnetic carrier and nonmagnetic toner; toner storage means 400, each of which stores toner for replenishing the corresponding developing unit; toner supplying means 401, each of which supplies toner in the toner storage means to the corresponding developing unit; and toner concentration detection sensors 53, each of which outputs a toner concentration detection signal corresponding to the magnetic permeability of the developer stored in the corresponding developing unit 40. Each toner concentration is calculated from a toner concentration detection signal from the corresponding toner concentration detection sensor 53. Then, based on the amplitude of the toner concentration detection signal changing with the lapse of time, it is determined whether developer stored in the corresponding developing unit 40 is empty of toner or not. COPYRIGHT: (C)2007,JPO&INPIT |
