| 摘要 |
PROBLEM TO BE SOLVED: To perform toner end display and its release with high accuracy by judging the toner end or the like when an output change width of a magnetic sensor to detect magnetic permeability of a developer is larger than a prescribed value when toner is replenished. SOLUTION: A magnetic sensor 306 arranged in a developing hopper 301 or on a hopper wall, outputs electric power corresponding to magnetic permeability of a developer to be carried. When toner is supplied from a toner replenishing part 304 while agitating the developer by rotating agitating screws 302a and 302b, just after the toner is replenished, a developer whose toner density is locally large moves along the vicinity of the magnetic sensor 306, and magnetic sensor output voltage temporarily reduces, and returns to ordinary voltage in a uniformly dispersed condition. When a residual toner quantity in a replenishing toner vessel is little, since only a small quantity of toner is supplied, a reduction quantity of output voltage of the magnetic sensor 306 also reduces. Release of the toner end is judged by using an output change in this magnetic sensor 306. |
