IMAGE FORMING APPARATUS

To allow appropriate control of a static eliminating bias according to an increase in secondary transfer bias due to a durability change while reducing an initial cost, and maintain a static eliminating function even after a long-term use, and to prevent the occurrence of a failure in transfer of a toner image even to a recording material having a low surface electric resistance and output a high-quality image.SOLUTION: An image forming apparatus 100 has an internal power supply configuration for applying a secondary transfer bias to a counter roller 54, and the image forming apparatus makes common a power supply that outputs voltage for applying the secondary transfer bias to the counter roller 54 and a power supply that outputs voltage for applying a static eliminating bias to a static eliminating needle 91 (transfer power supply D2), uses the transfer power supply D2, and even if the secondary transfer bias increases according to a durability change, outputs the static eliminating bias for maintaining the constant potential difference between a secondary transfer unit and the static eliminating needle.SELECTED DRAWING: Figure 3 【課題】イニシャルコストを抑えた上で耐久変化による二次転写バイアスの上昇に応じた除電バイアスの適切な制御を可能にし、長期使用後においても除電機能を保つこと。また、表面の電気抵抗が低い記録材に対してもトナー画像の転写不良の発生を抑え、高品質の画像を出力すること。【解決手段】対向ローラ５４に二次転写バイアスを印加する内給電構成の画像形成装置１００において、対向ローラ５４に二次転写バイアスを印加する電圧を出力する電源と、除電針９１に除電バイアスを印加する電圧を出力する電源とを共通にし（転写電源Ｄ２）、転写電源Ｄ２を用い、耐久変化に応じて二次転写バイアスが上昇しても、二次転写部と除電針の間の電位差を一定に保つ除電バイアスを出力する。【選択図】図３