| 摘要 |
PURPOSE:To eliminate the temperature gradients of the temperature of the fitting member of a toner concentration sensor and the temperature of a developer and to prevent the characteristics of a sensor from varying by installing a heater which heats the developer in a developing unit nearby the developing unit and driving the heater unless detected member reaches set temperature. CONSTITUTION:A thermistor 10 as a temperature detecting means for detecting the temperature of the bottom plate of the developing unit 2 is fitted to the bottom plate 9 adjacently to the toner concentration sensor 8. Further, the heater 11 for heating the developer in the developing unit 2 is fitted to the bottom part of the bottom plate 9. The temperature detection signal of the thermistor 10 is inputted to a CPU 13 through an input/output interface 12 to monitor the temperature of the bottom plate 9 at all times. The temperature detected value Ts which is inputted to the CPU 13 is compared with a previously set comparison value T0. When the detected temperature is less than the comparison value T0, the heater 11 is turned on and the CPU 13 drives driving motors 16 and 17 through the input/output interface 12 to rotate a developing roller 6 and a paddle roller 7. |
