Method and apparatus for testing thin material
AssigneeGiesecke & Devrient GmbH
InventorBernd Wunderer
Life of this patent
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Abstract
A method is described for testing thin material wherein the material is irradiated with ultrasonic waves at least in certain areas and transmission of the ultrasonic waves through the material is determined and evaluated. The transmission of ultrasonic waves of different frequencies is thereby determined. The differences of the transmission at the different frequencies are then used to determine a criterion for evaluating the quality, in particular the porosity, of the irradiated material. Furthermore, a corresponding test device is described.
Claims23
A method for contactlessly testing banknotes wherein a banknote is irradiated with ultrasonic waves at least in certain areas and transmission of the ultrasonic waves through the banknote is determined and evaluated, comprising determining the transmission of ultrasonic waves at different frequencies and establishing at least one criterion for evaluating the quality of the irradiated banknote according to the differences of transmission at the different frequencies, wherein said at least one criterion is dependent on the frequency dependence of the diffraction on pores of the banknote.
A test device for contactlessly testing banknotes, comprising
- an ultrasonic transmitting device arranged to irradiate a banknote under test with ultrasonic waves from one side at least in certain areas thereof,
- an ultrasonic receiving device arranged to measure the intensity of the ultrasonic waves transmitted through the banknote on the other side of the banknote, and
- an evaluation device configured to evaluate the determined transmission of the transmitted ultrasonic waves,
- wherein the ultrasonic transmitting device and/or the ultrasonic receiving device are configured to operate at different ultrasonic wave frequencies during testing of the banknote,
- the evaluation device is configured to establish a criterion for evaluating the quality of the irradiated banknote according to the differences of the transmission at the different frequencies, and
- wherein said at least one criterion is dependent on the frequency dependence of the diffraction on pores of the banknote.
Dependencies are inferred from the claim text.