| 摘要 |
PROBLEM TO BE SOLVED: To prevent excessive voltage being apt to be generated at a rising time from being applied to an electrification device. SOLUTION: At a starting time, a high and a low one-bit signals which can be switched with a frequency being higher than that of a normal-state alternating component are outputted from an electronic control unit 70. Then, the alternating component of the frequency being based on the signals is applied to an electrifying roller 24. Since it can be considered that the impedance of a system constituted of a photoreceptor drum 22 and the roller 24 approximately depends on a capacitor, it is in proportion to the inverse of the frequency. Therefore, when the frequency is increased, the impedance becomes small and the voltage becomes small at the time of constant current control. As the result, the excessive voltage is prevented from being applied to the roller 24 at the starting time.
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