Sheet feeding apparatus with ultrasonic sensor for detecting multiple feed of papers

A sheet feeding apparatus, comprising:

• a multiple feed detecting section having an ultrasonic transmitter, an ultrasonic receiver arranged on opposite sides of a conveyance path for conveying multiple sheets, and a comparison section, the multiple feed detecting section detecting a feed of the multiple sheets, the ultrasonic transmitter transmitting an ultrasonic wave to the ultrasonic receiver through at least one sheet traveling along the conveyance path for detecting the feed of the multiple sheets, and the comparison section comparing the ultrasonic wave received by the ultrasonic receiver with a reference level;
• a temperature detecting section for detecting a temperature of the apparatus;
• and
• an on/off operation control section for controlling on/off operations of the multiple feed detecting section, wherein the on/off operation control section turns off the multiple feed detecting section when the temperature detected by the temperature detecting section is outside a temperature range.