Gebhardt, W.W.GebhardtLicht, R.R.Licht2022-03-082022-03-082005https://publica.fraunhofer.de/handle/publica/306868Ultraschallwandler mit in Abstrahlrichtung aufeinander gestapelten piezoelektrischen Scheiben oder Platten, wobei die einzelnen piezoelektrischen Scheiben oder Platten individuell elektrisch kontaktiert sind und im Sendefall zur Schallerzeugung mittels bekannter Verzoegerungselektronikelemente zeitlich verzoegert derart nacheinander elektrisch angesteuert werden, dass der vom hinteren Piezo-Element erzeugte Ultraschallimpuls beim Durchlaufen des Stapels verstaerkt wird.WO 200035338 A UPAB: 20000831 NOVELTY - Ultrasonic waves generated by an ultrasonic transducer unit are directed towards a closed volume (1) with at least two openings (3,4). A gas flow is fed into the first opening (3) to produce an overpressure and to form the coupling medium. The second opening (4) directly faces the boundary surface via which a gas flow passes from the interior of the volume. DETAILED DESCRIPTION - The arrangement has an ultrasonic transducer unit (6) that couples ultrasonic waves into the medium via a coupling medium between the unit generating the waves and the boundary surface (8). The ultrasonic waves generated are directed towards a closed volume (1) with at least two openings (3,4). A gas flow is fed into the first opening (3) to produce an overpressure and to form the coupling medium. The second opening (4) directly faces the boundary surface via which a gas flow passes from the interior of the volume. USE - For coupling ultrasonic waves into a medium via a boundary surface. ADVANTAGE - The coupling efficiency is considerable increased.de608620658670patent1998-19861017