| 摘要 |
<P>PROBLEM TO BE SOLVED: To shorten time by the time when double feed of a sheet is determined in a processing device for detecting the double feed of the sheet to be fed. <P>SOLUTION: An image reader has a feed part for feeding a document along a feeding path, and an ultrasonic sensor. This image reader finds a value obtained by dividing a differential receiving level ΔE of a receiving level E received for each frequency by a receiver of the ultrasonic sensor by a time interval for each frequency as a slope DE of the receiving level E, and when the slope DE of the receiving level E is a slope of the same direction, and a section belonging to a fixed range exceeding a given magnitude is twice detected like a first section Z1 and a second section Z2, the image reader detects double feed. <P>COPYRIGHT: (C)2013,JPO&INPIT |
