SHEET FEEDING DEVICE, AUTOMATIC SHEET FEEDING DEVICE, IMAGE READING DEVICE, AND IMAGE FORMING DEVICE

To suppress a situation that positioning work of a regulating section cannot be completed before falling into a contacted state where a sheet bundle on a placing portion and a feeding member come into contact with each other.SOLUTION: A sheet feeding device including a stacking portion on which a sheet bundle is placed, a feeding member that contacts and feeds sheets placed on the stacking portion, and a regulating section that is configured to be movable in a sheet width direction and regulates a position of the sheet bundle on the stacking portion in a sheet width direction, comprises: switching means 105 for switching from a separation state where the sheet bundle and the feeding member are separated to a contact state where the sheet bundle and the feeding member are in contact without waiting for instructions to start feeding, after the sheet bundle is placed on the stacking portion; size identifying means 116a to 116d for identifying a sheet width direction size of the sheet bundle; and timing changing means 150 for delaying a timing to complete switching from the separation state to the contact state when the sheet width direction size identified by the timing changing means is smaller than a predetermined size compared to when it is equal to or larger than the predetermined size.SELECTED DRAWING: Figure 3 【課題】載置部上のシート束と給送部材とが当接する当接状態になる前に、規制部の位置合わせ作業を完了できない事態を抑制する。【解決手段】シート束が載置される載置部と、載置部に載置されたシートに当接して給送する給送部材と、シート幅方向へ移動可能に構成され、載置部上におけるシート束のシート幅方向位置を規制する規制部と、を備えたシート給送装置であって、載置部にシート束が載置された後、給送開始指示を待たずに、シート束と給送部材とが離間する離間状態から、シート束と給送部材とが当接する当接状態へと切り替える切替手段１０５と、シート束のシート幅方向サイズを特定するサイズ特定手段１１６ａ～１１６ｄと、サイズ特定手段が特定したシート幅方向サイズが所定サイズよりも小さいとき、該所定サイズ以上であるときよりも、離間状態から当接状態への切り替え完了タイミングを遅らせるタイミング変更手段１５０と、を有する。【選択図】図３