| 摘要 |
PROBLEM TO BE SOLVED: To always detect and control the stable toner specific concentration of developer without being influenced by the deterioration of an image carrier and the change of developing characteristic due to environmental fluctuation by providing a means for detecting the toner specific concentration of the developer oppositely to a position where the developer is supplied from a lower stirring means to an upper stirring means. SOLUTION: As to a magnetic type toner specific concentration detection sensor T arranged in a housing 1; the 1st attaching position Ta is set to a downstream side from a toner supply port 6 in a developer circulation path S, the 2nd attaching position Tb is set to the downstream side of a magnet roller 3 of a supplying developer accumulation part 7 in the path S, and the 3rd attaching position Tc is set to the downstream side from the supply port 6 in the path S and the upstream side of the roller 3 of the accumulation part 7. Then, the sensor T is attached in a state where the 1st and the 3rd attaching positions Ta and Tc are on the bottom part of the housing 1 at the lower part of a lower auger 4B and the 2nd attaching position Tb is on the side wall of the housing 1 at the side part of an upper auger 4A. |
