Siemens Aktiengesellschaft

Rudolf Thurn

Hans-Joachim Burger

Klaus Busch

An ultrasonic transducer includes a housing, in which an ultrasonic oscillator is secured with at least one of a nonpositive and positive fit and at least three layers with acoustic wave impedances that vary to alternating degrees. The layers are arranged such that the ultrasonic oscillator is embedded in a first relatively acoustically soft layer, a second layer, which includes at least one relatively acoustically hard material, surrounds the first layer, and a third relatively acoustically soft layer at least partially surrounds the second layer.

Ultrasonic transducer

Ultrasound transducer

Ultrasonic transducer with a disk-shaped quarter wave length transformer

For certain applications, such as detecting of glass breakage, it is advantageous to use frequency-selective ultrasonic transducers. In this case, one can dispense with using costly filter configurations to filter out relevant frequency components of the received ultrasonic spectrum. An ultrasonic sandwich transducer, which shows a high sensitivity for certain predetermined frequencies, can be produced by selectively adapting at least one of its geometric dimensions to the frequency selectivity which is required of the transducer. The ultrasonic sandwich transducer preferably has a piezoelectric-ceramic wafer, which is surrounded on at least one of its two wafer surfaces by a layer of low acoustical impedance. The piezoelectric-ceramic wafer is effectively rectangular, resulting in a block-shaped member. One of the dimensions of height, length and width is fixed to correspond to a desired fundamental frequency.

Frequency-selective ultrasonic sandwich transducer

A method for producing an ultrasound transformer as a single integral unit that includes a piezoelectric transformer element coupled to an acoustical matching layer formed from an elastomer capable of vibrating. The method includes the steps of: producing an elastomer body from a molded part which has centering contours; positioning the transformer element into the elastomer body; centering the transformer element with the centering contours; and, coupling the transformer element to the matching layer.

Method for the production of ultrasound transformers

In an ultrasonic sandwich transducer having an astigmatic sonic lobe, a small rectangular piezoceramic plate is operated on the fourth planar vibrational mode. To prevent the creation of secondary lobes that lead to spurious signals, damping elements are applied to the longitudinal ends of the ultrasonic sandwich transducer. These types of ultrasonic sandwich transducers find application, in ultrasonic proximity switches.

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Pressath, Germany

Rudolf Thurn