SHEET SUPERPOSING FEEDING DETECTION METHOD, SHEET FEEDING DEVICE AND IMAGE READING DEVICE USING THIS

PROBLEM TO BE SOLVED: To provide a superposing feeding detection method for a sheet and a sheet feeding device, which exactly determine one sheet or a plurality of sheets of wide sheets having different length in a conveying direction on the midway of conveying and exactly and particularly detecting superposing of two upper and lower sheets and simultaneously detecting superposing largely deviated in a longitudinal direction. SOLUTION: At least two first and second conveying means 4, 5 are arranged in a sheet guide 3 for guiding the sheets on a stacker 1 to processing positions such as image-reading and printing. A superposing feeding detection means 6 for detecting the superposing of the sheet during movement at a predetermined length area (measurement length) is arranged between the first conveying means 4 and the second conveying means 5. A sheet length recognition means 50 for discriminating conveying direction length of the sheet placed on the above stacker 1 to at least two and a determination means for determining multiple conveying of the sheet based on the detection data from the superposing feeding detection means 6 are provided. The determination means is constituted such that the superposing of the sheet is determined by the detection data of one measurement area selected from a plurality of measurement areas based on information obtained from the sheet length recognition means 50. COPYRIGHT: (C)2005,JPO&NCIPI