US Patent 8419014 Image reading apparatus, multifeed determining method, and multifeed determining program

An image reading apparatus includes a multifeed detecting mechanism including an ultrasonic sensor, and a control unit. The control unit includes (i) a detecting unit that detects an attached portion on a paper from an output of the ultrasonic sensor for the paper fed, and (ii) a determining unit that ignores, when it is detected as “Occurrence of multifeed” by the multifeed detecting mechanism and if an amount of variation in the output within the attached portion detected by the detecting unit is equal to or more than a first predetermined value, a result of detection as the occurrence of multifeed by the multifeed detecting mechanism, and determines the detection as “No multifeed”.