SHEET DISCRIMINATION DEVICE, CONTROL METHOD AND IMAGE FORMATION DEVICE

To provide a sheet discrimination device for discriminating a kind of a conveyed sheet.SOLUTION: This sheet discrimination device comprises: a gate which changes from a first attitude of maintaining a direction for regulating traveling of a sheet by being energized by an energization member to a second attitude of retreating from a conveyance passage of the sheet by rushing of the sheet, and, by the change of the strength of the stiffness of the sheet applied to the energization member during passage of the sheet, restores from the second attitude to the first attitude; a sensor for detecting the change of the attitude of the gate; and a sheet discrimination circuit 112 which measures time to a time point of restoring to the first attitude with a time point where the gate changes from the first attitude to the second attitude as a reference during conveyance of the sheet, and discriminates a kind of the sheet in accordance with the length of the measured time.SELECTED DRAWING: Figure 8 【課題】搬送されるシートの種類を判別するシート判別装置を提供する。【解決手段】付勢部材により付勢されてシートの進行を規制する方向を維持する第１姿勢から、シートの突入により、シートの搬送経路から退避する第２姿勢に変化し、シートの通過中において前記付勢部材に与えるシートの腰の強さの変化により、前記第２姿勢から前記第１姿勢に復帰するゲート、ゲートの姿勢の変化を検知するセンサー及びシートの搬送中に、ゲートが第１姿勢から第２姿勢に変化した時点を基準として、第１姿勢に復帰する時点までの時間を計測し、計測した時間の長さに応じて、シートの種類を判別するシート判別回路１１２を備える。【選択図】図８