| 摘要 |
PURPOSE:To stabilize developer concentration, to prevent toner from being scattered and an image from fogging, and to form an image of high quality by operating a developer supply means intermittently according to whether or not a main power source is turned on and whether or not a toner supply signal is generated. CONSTITUTION:A mixing ratio detection sensor 15 is provided on a path through which a developer mixed and agitated by two screws 8 and 9 is sent to a developing sleeve 71. When the toner supply signal is generated within a specific time after the main switch of a copying machine is turned on or after toner is put in a toner container, toner supply is performed for t2 and stopped for t3. Toner is supplied for t2 after t2+t3 and the toner supply is stopped for t3. Said operation is carried out for up to t1. When the detection signal voltage Vsens of the sensor 15 is smaller than a specific voltage Vth, the agitation, conveyance, and supply of the developer mentioned above are repeated intermittently with the toner supply signal. When the concentration does not reach the specific value even a specific time later, a toner absence display is made. Thus, a stable image having no fogging is formed with the simple constitution. |
