OPTICAL SCANNER AND IMAGE FORMING APPARATUS

To accurately reduce the occurrence of banding, moire, and operation sound caused by an optical scanner, and achieve high image quality, miniaturization, and low cost.SOLUTION: An optical scanner comprises a memory 117 that synchronizes a predetermined surface of a rotary polygon mirror 102a with each of a plurality of surfaces of a rotary polygon mirror 102b to measure the amounts of shift in a sub scanning direction of a light beam L radiated on a body to be scanned, and stores information on the combination of the predetermined surface of the rotary polygon mirror 102a and a surface of the rotary polygon mirror 102b in which the shift amount becomes minimum among the measured shift amounts. A control unit 118 controls scanner motors 103a, 103b, in performing image formation, such that the combination of the surface of the rotary polygon mirror 102a and the surface of the rotary polygon mirror 102b becomes one stored in the memory 117.SELECTED DRAWING: Figure 5 【課題】光学走査装置に起因するバンディングやモアレ、動作音の発生を精度よく低減し、高画質化と小型化、低コスト化を実現すること。【解決手段】回転多面鏡１０２ａの所定の面と回転多面鏡１０２ｂの複数の面とをそれぞれ同期させて、被走査体上に照射される光束Ｌの副走査方向におけるずれ量を測定し、測定したずれ量の中で最もずれ量が小さくなる回転多面鏡１０２ａの所定の面と回転多面鏡１０２ｂの面の組み合わせの情報を記憶したメモリ１１７を備え、制御部１１８は、画像形成を行う際に、回転多面鏡１０２ａの面と回転多面鏡１０２ｂの面がメモリ１１７に記憶された組み合わせとなるようにスキャナモータ１０３ａ、１０３ｂを制御する。【選択図】図５