| 摘要 |
PURPOSE:To simplify constitution, and to stabilize glid voltage using a constant voltage element such as a varistor by comparing a voltage impressed to both the ends of the constant voltage element with a reference value and controlling the level of voltage to be impressed to a corona discharger based on an output from a comparing means. CONSTITUTION:A DC high voltage is impressed from a high voltage generating circuit (HVG) 4 to a discharging wire 20 in the corona discharger 2, the constant voltage element 5 such as a varistor is connected to a grid 3 in series and the surface voltage of a member 1 to be charged such as a photosensitive body is controlled so as to be almost equal to a grid voltage determined by the element 5. When the characteristics of the element 5 is varied by a change in peripheral temperature, an error between the voltage on both the ends of the element 5 and a reference voltage 6 is generated, a detected by a comparator 7 and led in a control circuit 8 and the output voltage of the HVG 4, i.e. a corona discharging voltage, is controlled until the voltage on both ends of the element 5 becomes equal to the reference voltage 6. |
