| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to identify a loaded developing device with a simple configuration without the need to incorporate storage means such as a memory in the developing device.SOLUTION: A developing device 34 is detachably from an image forming unit 3, and includes: a scraper 66 for rotating in accordance with rotation of a screw feeder 64A; and a toner concentration sensor 67 for detecting magnetic permeability of a developer. The scraper 66 periodically contacts a detection surface 68 per rotation. A rotation drive force of a stepping motor 77 is transmitted to the screw feeder 64A via a gear 78 to allow the scraper 66 to rotate. The toner concentration sensor 67 outputs a signal which periodically changes in accordance with the rotation of the scraper 66. A controller 5 determines a cycle of an output waveform from the toner concentration sensor 67 and identifies the developing device 34 on the basis of the cycle. |
