SHEET ACCOMMODATION MECHANISM, POST-PROCESSING DEVICE AND IMAGE FORMING DEVICE

PROBLEM TO BE SOLVED: To provide a sheet accommodation mechanism which can correctly operate a paper pressing member which presses a sheet face when accommodating a sheet on a tray at correct timing, and does not disturb a posture of the sheet which is accommodated by the operation.SOLUTION: Paper pressing means 35 which presses an uppermost sheet which is laminated on and accommodated in a stack tray is constituted so as to be capable of oscillating a base end part 35a of an arm member having a paper pressing face at a tip, and a return locus at which the paper pressing face 35x moves to a standby position from an operation position in which the paper pressing face presses the sheet performs return motion according to a state of the accommodated sheet at either of a first locus Los which is the same as a forward locus and a second locus Lo2 at which a paper placing face approximates a sheet end regulation face side. 【課題】トレイ上にシートを積載収納する際にシート面を押圧する紙押さえ部材を正しいタイミングで、正しく動作させることと、その動作で収納したシートの姿勢を乱すことがないシート収納機構を提供する。【解決手段】スタックトレイに積載収納された最上シートを押圧する紙押え手段３５を、先端部に紙圧面を有するアーム部材の基端部３５ａを揺動可能に構成し、紙圧面３５ｘがシートを押圧する作動位置から待機位置に移動する復路軌跡を、往路軌跡と同一の第１軌跡Ｌo１と、紙載面がシート端規制面側に接近した第２軌跡Ｌo２のいずれか一方で収納されたシートの状態に応じて復帰動するように構成する。【選択図】図４