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 transducer includes at least one cylindrical driving assembly and at least one headmass coupled to an end of the cylindrical driving assembly. The headmass has an external ring that surrounds a core. The core is made from a core material that is less dense than the material from which the external ring is made. The headmass is dimensioned to occupy a predetermined volume so as to transmit waves within a predetermined frequency range. As a result, the transducer provides higher power waves, yet occupies the same volume as the transducers of the prior art.

Abstract: A transducer includes one or more electro-acoustic motors located on a same internal plane or as a peripheral ring of a flexible envelope to which they are interdependent by at least one-of their ends by an assembling device and to which they transmit their vibrations, the flexible envelope being in contact with the liquid and constituting the acoustic waves emitting surface. The flexible envelope is shaped such that the amplitude of the vibrations is increased in a range of very low frequency. The envelope includes at least one orifice allowing the liquid to enter the whole internal cavity delimited by the envelope and a baffle made up of alveolar material that resists the immersion pressure and fills most of the cavity volume. The external surface of the baffle is at a constant distance from that of the interior of the envelope and is interdependent to the assembling device of the acoustic motors.

Abstract: The invention relates to processes and electro-acoustic transducers for transmitting low-frequency acoustic waves in a liquid. An electro-acoustic transducer according to the invention is a transducer of the double-tonpilz type, comprising two electro-acoustic drivers (1a, 1b) in line on both sides with a central counter-mass (2) and between two horns (3a, 3b). This mechanical assembly is located in a rigid box (4) which is fitted with side holes (5) and which delimits a cavity (7) housing elastic tubes (6) closed at their both ends and filled with gas so that the Helmholtz resonant frequency of the cavity (7) is close and preferably lower than the fundamental frequency of the axial vibrations of the vibrating assembly. An application of the invention is the construction of low-frequency transmitting transducers of the double-tonpilz type with a wide pass-band.

Abstract: An electroacoustic transducer according to the invention comprises a stacking of annular plates (13) made of piezoelectric ceramics alternating with annular electrodes (14) and pressed by an axial prestressing stem (15). The contact faces between each plate and the adjacent ones are made of two flat parts (16a, 16b) whose surface is smaller than the maximum cross section, due to the chamfers (19a, 19b, 20a, 20b) which truncate the edges of each plate. One application is the construction of low frequency sonar transmitters. Referenced elements refer to FIG. 3.

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.