Patent ID: 8047541
Filing Date: 2011-11-01
Classification: B65H

Abstract:
1. A duplicate feeding detection device for use with sheet members comprising: a feeding passage on which the sheet members are carried; an ultrasonic transmission part which is disposed on one side of the feeding passage and to which a predetermined drive voltage is applied to emit an ultrasonic wave; an ultrasonic receiving part which is disposed on an other side of the feeding passage for receiving the ultrasonic wave from the ultrasonic transmission part; a duplicate feeding judging part for judging duplicate feeding of the sheet members on a basis of an output from the ultrasonic receiving part; a control part for controlling the ultrasonic transmission part; a temperature measuring part for measuring temperature of the ultrasonic transmission part or a vicinity of the ultrasonic transmission part; a memory part in which a relationship between a drive voltage for driving the ultrasonic transmission part and a temperature is stored; and a second memory part in which a relationship between an oscillation frequency and a temperature is stored; wherein the control part sets a drive voltage corresponding to the temperature which is measured by the temperature measuring part as the predetermined drive voltage on a basis of the relationship between the drive voltage and the temperature stored in the memory part, and a set drive voltage is applied to the ultrasonic transmission part; wherein the ultrasonic transmission part emits the ultrasonic wave having a predetermined oscillation frequency; and wherein the control part sets an oscillation frequency corresponding to a temperature which is measured by the temperature measuring part as the predetermined oscillation frequency on a basis of the relationship between the oscillation frequency and the temperature which is stored in the second memory part; wherein the control part controls the ultrasonic transmission part so as to emit the ultrasonic wave having the predetermined oscillation frequency; and wherein the relationship between the oscillation frequency and the temperature which is stored in the second memory part corresponds to a change of a resonance frequency corresponding to a change of the temperature in the ultrasonic transmission part; and wherein the drive voltage which is stored in the memory part is obtained on a basis of an inverse function of a function which is defined by a relationship between an output of the ultrasonic wave which is emitted at the predetermined oscillation frequency and received by the ultrasonic receiving part and a temperature.