| 摘要 |
PURPOSE:To detect toner concentration accurately by utilizing variation in the flowability of a developer with the toner concentration difference of the developer. CONSTITUTION:When the toner concentration of the developer 2 flowing in a flow passage 8 is low, there are many magnetic carriers, so the developer 2 is dry and has good flowability, so that the developer 2 never stays in the flow passage 8. Consequently, a buoyant plate 9 in the flow passage 8 is at a lower position as shown by a broken line and separated from a sensor 10. When, however, the toner concentration increases, the amount of toner increases, so the developer 2 deteriorates in flowability to stay gradually in the flow passage 8 and is restrained by a flow-rate restraint plate 11 to swell before it. The swell elevates the buoyant plate 9, which touches the sensor 10, thereby operating the sensor 10. Consequently, the toner concentration in the flow passage 8 is detected to know the toner concentration in a case 1. |
