Ultrasonic method for determination of the thickness of sheet material, especially banknotes, whereby time of flight sound wave measurements are made on either side of the note with ultrasonic signals having different waveforms

摘要

Method for determining the thickness (D) of sheet material (BN), especially banknotes in which ultrasonic signals (S) are transmitted towards the material from either side to determine its thickness. The ultrasonic signals have different waveforms. An independent claim is made for a device for determining the thickness of sheet material with two ultrasound transmitters (4, 5) arranged on either side of sheet material so that time of flight measurements of transmitted and reflected or received signals can be made.