Patent ID: 9201339
Filing Date: 2015-12-01
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a developing device developing an image carrier by a contained developer; a magnetic permeability detecting part detecting magnetic permeability of the developer in the developing device; an agitating member rotating in the developing device to agitate the developer; a detected result deciding part deciding, on the basis of the magnetic permeability detected by the magnetic permeability detecting part before the agitation by the agitating member, whether or not a detected result of the magnetic permeability detecting part is varied cyclically; and a detected result correcting part correcting the detected result of the magnetic permeability detecting part by subtracting the magnetic permeability in a predetermined cycle detected by the magnetic permeability detecting part before the agitation by the agitating member from the magnetic permeability in the predetermined cycle detected by the magnetic permeability detecting part during the agitation by the agitating member, in a case where the detected result deciding part decides that the detected result of the magnetic permeability detecting part is varied cyclically, and a developer amount measuring part calculating a duty ratio of the magnetic permeability of the developer in the developing device on the basis of detected result of the magnetic permeability detecting part corrected by the detected result correcting part and measuring a developer amount in the developing device on the basis of the duty ratio.