| 摘要 |
PURPOSE:To accurately detect toner concentration by providing a heating device to a member for holding a toner concentration sensor and preventing the detection characteristic or the detected value of the toner concentration sensor from being influenced by temperature change. CONSTITUTION:When a main switch which is not shown in figure is turned on, the startup of respective parts necessary for development is executed and a heater 6 is turned on simultaneously with the startup. The energizing time of the heater 6 is set at a proper rate and the startup of the temperature of the bottom side part 1a of a developing device 1 is finished by the time when the startup of the respective parts is completed. Then, a thermistor 5 measures the temperature of the bottom side part 1a of the device 1 and the energizing time of the heater 6 is controlled by a CPU 8 in accordance with the measured value. Thus, the detection characteristic or the detected value of the toner concentration sensor is prevented from being influenced by the temperature change. |
