| 摘要 |
PURPOSE:To detect surely a developer density and to reduce the size of a device by providing the detection surface of the developer density detector in proximity to a developer agitating body disposed to a developer contg. part. CONSTITUTION:The developer density detector 44(43) provided to each develop ing device has a head part 201 which faces a casing 1812(1811) and contains internally a coil 200 for generating a magnetic field. The magnetic permeability changing with the mixing ratio of the toner T2(T1) in the developer G2(G1) flowing on the surface of the head part is converted to the change of inductance and the density of the toner T2 in the developer G2 is detected. On the other hand, the detector 44 of the developing device is provided in proximity to the developer agitating body 1802 and in the state in which the detection surface 201a of the head 201 is made vertical. Said detector makes stable detection as the space H between the locus on the outside of periphery of the body 1802 and the surface 201a is set at 0.2-1mm. The toner T2 in a hopper 1732 is replenished onto the body 1802 by rotating a roller 1921 according to the result of the detection by the detector 44. |
