| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi-feeding detection unit which can perform highly accurate multi-feeding detection even when change and variation occur in the ultrasonic wave arrival time.SOLUTION: A multi-feeding detection unit comprises an ultrasonic transmission sensor T1 which transmits an ultrasonic wave into a direction of a manuscript 102, an ultrasonic reception sensor T2 which outputs a reception signal by receiving the transmitted ultrasonic wave, an AD conversion circuit, and a CPU. The AD conversion circuit acquires the amplitude of the reception signal output from the ultrasonic reception sensor. The CPU controls the amplitude acquisition timing at the time when the AD conversion circuit acquires the amplitude in a case where the manuscript exists on a conveyance path sandwiched by the ultrasonic transmission sensor and the ultrasonic reception sensor on the basis of the time from transmission of the ultrasonic wave to reception of the reception signal by the AD conversion circuit in the state where the manuscript does not exist on the conveyance path sandwiched by the ultrasonic transmission sensor and the ultrasonic reception sensor. The CPU also determines whether or not the manuscripts are in the multi-feeding state on the basis of whether or not the acquisition result of the AD conversion circuit exceeds a threshold.SELECTED DRAWING: Figure 3 |
