Abstract: The invention relates to directional electro-acoustic transducers compris a sealed shell consisting of two portions.A transducer according to the invention comprises one or more electro-acoustic drivers (1) composed for example of a stack of piezoelectric plates (1a, 1b, . . . 1n) located inside a sealed shell. This shell comprises a first portion (3A) symmetrical as to a plane (PP') fitted with two flanges at its ends, these flanges being coupled mechanically and acoustically by means of a rod (7) and two bolts (8) With each driver (1). The shell includes a second portion (3b) which is complementary to the first portion and which is acoustically uncoupled from the first portion and from the drivers.An application of the invention is the construction of low-frequency transmitter of acoustic waves in the water in a given direction.

Abstract: The invention relates to electro-acoustic transducers comprising a flexible nd sealed transmitting shell referred to as flextensional transducers. A transducer according to the invention comprises one or more electro-acoustic drivers, e.g., a stack of piezoelectric plates 1a, 1b . . . 1n, located inside a flexible and sealed shell. Each piezo-electric driver comprises, at both its ends, a counter-mass coupled mechanically and acoustically with the stack and the ends of the shell by means of an axial threaded rod and two nuts screwed on the ends of the rod. The mass of the two counter-masses and the dimensions of the stack are determined so that the fundamental frequency of the axial oscillations of this mechanical assembly will be close to the natural frequency of the bending oscillations of the shell. An application of the invention is the construction of sonar transmitters.

Abstract: A Tonpilz type piezoelectric transducer which can be used alternately as a wide-band receiver and an emitter includes a stack of pairs of piezoelectric segments separated by electrodes, the stack being placed between a horn and a countermass. An emitter is connected by a conductor to one of the two electrodes for each segment pair. One pair of segments next to the countermass is separated from the others by an insulator. The two electrodes to either side of the one pair are connected in parallel to a receiver and, through two diodes connected in opposition, to a grounded common conductor.

Abstract: An electro-acoustic transducer according to the invention is of the Tonpilz type comprising a stack of piezo-electric plates placed between a horn and a countermass, and electrodes inserted between the plates. Some of the electrodes are connected to a common excitation or output conductor through phase-shifting circuits which allow the electric voltage of a proportion of these electrodes to be dephased. A logic unit allows the phase-shifting of the electrodes to be distributed within the stack according to several different groupings in dependence upon frequency. One application of the invention is to the construction of long-range power sonars.