IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To normally transfer a toner image on an intermediate transfer belt to a recording medium despite a change of the radius of the intermediate transfer roller.SOLUTION: An image forming apparatus includes an intermediate transfer belt 20 to which an image formed on a photoreceptor drum 11 is transferred, a secondary transfer roller 31 that forms a transfer nip with the intermediate transfer belt, and a conveying roller pair 54 that is arranged on the upstream side of the transfer nip to transport a sheet P to the transfer nip. The image forming apparatus includes a radius sensor 60 that measures the radius of the secondary transfer roller 31 affecting the speed of the sheet P passing through the transfer nip, and control means 70 for adjusting the speed of a conveying roller motor 80 driving the conveying roller pair 54 on the basis of a result of the measurement by the radius sensor 60.SELECTED DRAWING: Figure 2 【課題】中間転写ローラーの半径が変化したとしても中間転写ベルト上のトナー像を記録媒体に正常に転写する。【解決手段】感光体ドラム１１に形成された画像が転写される中間転写ベルト２０と、中間転写ベルトとの間に転写ニップを形成する二次転写ローラー３１と、転写ニップの上流側に配置され、転写ニップに用紙Ｐを移送する搬送ローラー対５４とを備える。転写ニップを通過する用紙Ｐの速度に影響を与える二次転写ローラー３１の半径を測定する半径センサー６０と、半径センサー６０の測定結果に基づいて搬送ローラー対５４を駆動する搬送ローラーモーター８０の速度を調整する制御手段７０とを備える。【選択図】図２