PURPOSE: To eliminate the need for complicate mechanism by permitting a control circuit to vary the voltage value of a development bias depending upon the time also when a switching element was turned on previously.
CONSTITUTION: Control circuit CS for development bias voltage value control functions to vary the voltage value of a development bias applied to development sleeve 3 when switch S1 is turned on depending upon the time when switch S1 was turned off before it is turned on. Further, it has the 2nd function of gradually increasing the voltage value of the development bias applied to development sleeve 3 up to a constant value while switch S1 is turned on. Then this control circuit CS has capacitor C1 that starts charging operation by bias power source E1 via resistances R1 and R2 as switch S1 turned on and starts discharging operation via resistance R3 as switch S1 is turned off and both the functions are alternated according to the charge and discharge states of this capacitor C1.
WADA KENICHI
TANAKA SUSUMU
