Abstract: An apparatus for determining the transit time of ultrasonic pulses in a fluid has two spaced apart electro-acoustic converters (11, 20). A transmitter signal proportional to the sound pressure is applied via a controllable delay circuit (23) to a multiplication circuit (25) to which the received signal is also passed. The product signal is in turn passed to a transit time detector circuit (10) (FIG. 1).

Abstract: An apparatus for determining the transit times of ultrasonic pulses in a fluid has at least two electroacoustic converters (11, 20) arranged spaced apart in the fluid. An electrical signal proportional to the sound pressure generated at the transmitting converter (11) is derived from the transmitting converter (11) and is fed to the input of a correlation circuit (12).

Abstract: Piezoelectric light deflecting apparatus consists of first and second piezoceramic strips 11, 12 each of which has a clamped end and a free end 15. The strips 11, 12 are substantially aligned in one plane with their free ends 15 facing one another and spaced apart by a distance x. An AC voltage U having a frequency which differs significantly from the natural resonant frequency of the strips is used to energize the strips to execute oscillations so that their free ends are periodically displaced in counterphase to one another. A mirror 13 is mounted via flexible legs 14 to the free ends of the piezoceramic strips 11, 12 so that the mirror 13 executes a rotary oscillation as a result of the counterphase movements of the free ends of the piezoceramic strips.

Abstract: A piezoelectric fluid atomizer comprises an oscillating plate which is made to resonate by means of an electric alternating voltage. The element causing the oscillations is a piezoceramic converter which is connected to the oscillating plate via a cylindrical extension part. The cylindrical extension with the oscillating plate is constructed as an axial extension of the front side of a bolt which comprises a widened portion in the form of an abutment plate adjacent the cylindrical extension. The bolt supports converter elements which are shaped as rings and which are pressed across the bolt against the abutment plate by means of a pressure plate. A shield which extends across the converter elements is secured on the bolt at some distance behind the pressure plate. In operation an oscillation node is present for the freely suspended part supporting the piezoelectric converter elements, at the area of the abutment plate.