| 摘要 |
PURPOSE:To shorten a holding time, by providing a solenoid valve for controlling the quantity of a developer, a solenoid valve driving circuit, and the first controlling circuit and the second controlling circuit for turning on this driving circuit. CONSTITUTION:When the electric powr source is turned on, electric power is supplied to a heater 12, a developing tank is heated, and a temperature of the tank reaches to T1, an input of a set terminal S of a flip-flop circuit 14 becomes. H. Therefore, a timer 19 and a twin timer 17 start to operate. Since a resistance value of a resistor 25 is made smaller than resistance values of a resistor 5 and a variable resistor 15, only a discharge time is shortened remarkably while an output of the timer 19 is H, by which the time when a transistor 10 becomes nonconductive, that is to say, the time when a solenoid valve 18 is closed is shortened, and a developer is supplied to the developing tank more than usual in its quantity. |
