| 摘要 |
PURPOSE:To hold toner density in a developing device at a fixed level by arranging plural toner density detecting means and feeding toner in accordance with toner density values detected by these detecting means. CONSTITUTION:A front side auto-toner detector 7a and a rear side auto-toner detector 7b are arranged and toner ratio density in a developing flow scraped from a developing sleeve 1 is detected by these detectors 7a, 7b. When the toner ratio density on the front side is dropped, a feeding signal is outputted from the detector 7a and the detector 7b is kept at the normal state. A difference between the outputs of the detectors 7a, 7b is detected by a judging circuit and a toner feeding motor 6 is rotated at a low speed by a control circuit. Since the toner is moderately carried in a toner carrying pipe 5, the toner is not almost dropped in a toner dropping hole 5a on the front side, so that the toner ratio density on the front side is returned to the normal level and becomes almost the same as the toner ratio density on the rear side. |
