| 摘要 |
A developing device includes a development roller (11), a magnetic roller (12), a transformer (83), a switching portion (81), output control portion (80) and a capacitor (82). The development roller (11) is opposite a photoconductor drum (42). The magnetic roller (12) performs, with a magnetic brush, the supply of a toner to the development roller (11) and the removal of the toner. The transformer (83) generates an alternating-current voltage applied to the development roller (11). The switching portion (81) passes and interrupts a current to the transformer (83). The output control portion (80) stepwise changes, when a duty ratio in switching is changed, the duty ratio a plurality of times from a first duty ratio to a second duty ratio. The capacitor (82) has one end connected to the transformer (83) and the other end connected to the switching portion (81). |
