| 摘要 |
PROBLEM TO BE SOLVED: To immediately detect an abnormal condition of a sensor which detects an amount of toner remaining in a hopper used for replenishing a developing unit with the toner, and to improve accuracy in toner replenislunent from the hopper. SOLUTION: The first hopper 101 for replenishing the developing unit 4d with the toner and the second hopper 111 for replenishing the first hopper 101 with the toner are provided. According to the output of the sensor 103 which detects an amount of the toner remaining in the first hopper 101, whether the hoppers 101 and 111 are abnormal or not are detected. A sensor 113 which detects an amount of the toner remaining in the hopper 111 is provided above the stirring area of the stirring member 114 of the hopper. |
