| 摘要 |
<p>A developing device includes a developing roller, a magnetic roller opposed to the developing roller so as to form a magnetic brush, a high voltage power supply including a transformer having secondary side outputs one of which is connected to the developing roller while the other output is connected to the magnetic roller, so as to apply AC voltages to the developing roller and the magnetic roller, a detection portion for detecting occurrence of discharge between the developing roller and the photoreceptor drum, a restriction portion for restricting movement of toner from the magnetic roller to the developing roller, and a moving portion configured to move the restriction portion in discharge start voltage detection mode so as to restrict toner movement to the developing roller.</p> |
