| 摘要 |
PURPOSE:To detect the concentration of developer by applying AC voltage of more than a fixed frequency between a pair of electrodes sandwiching the developer and measuring the change in the electrostatic capacity between the electrodes. CONSTITUTION:Arrangement is so made that two-component type developer 2 passes between a pair of electrode plates 1. The electrodes 1 are connected to an AC power source 3 and are connected on their way with a protection resistance 4 and current measuring device 5. According to the measurement value of the current measuring device 5, the supplementing of the toner is controlled with a toner supplement contol unit. When AC of more than a fixed frequency is applied to a pair of said electrode plates, the current flowing between the electrodes is inversely proportional to capacitance and therefore the change in the toner concentration may be known. |
