Method and apparatus for dynamic determination of the thickness and/or basis weight of moving material under test
AssigneeGiesecke & Devrient GmbH
InventorChristoph Gerz
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Abstract
The invention relates to a method and apparatus for dynamic determination of the thickness and/or basis weight of moving material under test. The material under test is exposed to a focused ultrasound filed with high sound intensity, whereby the sound fraction coming from the material under test is detected directly in the near filed, i.e. at a distance smaller than or equal to the acoustic wavelength used, and evaluated for determining the thickness and/or basis weight. The near-field measurement preferably takes place with continuous sound and in transmission.
Claims9
A method for dynamic noncontacting determination of the thickness and/or basis weight of a material under test using ultrasound, the material under test being transported in a defined direction characterized in that a plurality of transmitters each with the same radiation characteristics radiate ultrasonic waves in phase toward a defined area of the material under test perpendicular to the transport direction, so that a focused sound field with high sound intensity is produced in the defined area of the material under test, a portion of the ultrasonic waves coming through the material under test being detected at a distance smaller than or equal to an acoustic wavelength of the ultrasonic waves, and the detected portion of the ultrasonic waves being evaluated for determining the thickness and/or basis weight.
Dependencies are inferred from the claim text.