Patent ID: 7934722

Claim:
An image scanning apparatus comprising: a containing unit arranged to contain at least two sheets of original documents; an original document separation unit arranged to transport the original document from the containing unit onto a transport path; a plurality of transportation rollers arranged to transport the original document along the transport path at a transportation speed; a motor unit for driving the plurality of transportation rollers; an original document scanning unit arranged to optically scan the original document transported from the containing unit; an ultrasonic sensor including a transmission unit arranged to transmit ultrasonic sound towards the original document that is being transported from the containing unit to the original document scanning unit, and a reception unit arranged to receive the ultrasonic sound that has passed through the original document that is being transported; and a transportation speed adjusting unit arranged to adjust the transportation speed of the original document based on a reception signal sent from the reception unit, wherein the transportation speed adjusting unit includes: a paper thickness detection unit arranged to detect a paper thickness of the original document based on the reception signal; and a multiple-feeding detection unit arranged to detect, based on the reception signal, whether or not the original document that is being transported has been multiply fed, and the transportation speed adjusting unit adjusts the transportation speed by controlling the motor unit based on a detection result obtained by the paper thickness detection unit and the multiple-feeding detection unit, wherein when the original document that is being transported has not been multiply fed, the transportation speed adjusting unit changes the transportation speed based on the paper thickness detected by the paper thickness detection unit.