Image Number 7 for United States Patent #5761156.
The invention relates to a piezoelectric transducer particularly for use in transit time measurements. The object of the invention is to provide a piezoelectric transducer which ensures an in-phase two-dimensional pulse emission which, independent of the selection of a definite excitation frequency, substantially closely follows the electric excitation at a low time deformation of the pulse owing to transient and dying-out operations and which permits to obtain sufficiently high sound levels at low amplitudes of the excitation voltage. These objects are realized according to the invention in that the center of mass of the entire transducer system is remote from a sound emitting and sound receiving, respectively, surface (4) and in that at least one piezoelectric sheet (1) is provided which via one of its narrow sides (21) is connected to at least one rigid, geometrically and variably adaptable cover plate (3) of low mass, compared to the entire transducer and sheet mass, respectively, in such a manner that the entire surface (4) of the cover plate (3), at least in the sound emitting mode, is substantially and completely covered by the surface lines (5) of an emission angle (.alpha.) under which the piezoelectric sheet irradiates said cover plate (3), and only to said surface (4) the function of being a sound emitting and/or a sound receiving area is assigned.