| 摘要 |
PROBLEM TO BE SOLVED: To prevent toner scattering, faulty image quality and the lowering of resolution and to prolong the maintenance cycle by accurately controlling toner concentration without causing overshoot exceeding the appropriate toner concentration even in the case of outputting a large-sized image for which toner is consumed much or even in the case of forcibly supplying the toner when the toner is depleted in a system where a toner concentration sensor is disposed in a developer carrying path. SOLUTION: By dividing a toner replenishing means above the developer carrying path to an upstream side and a downstream side while putting a non- replenishing area in between and attaching the toner concentration sensor to the lower part of the nonreplenishing area, the toner concentration of the developer in which the toner for-replenishment is completely uniformly mixed is detected and the toner replenishment is controlled based on the detected toner concentration, so that the toner concentration is always stably controlled. |
