Abstract: The invention is a mechanical sensor produced from a polymer film whose upper part (A) is made conductive, the lower part (B) remaining an insulator. When a strain is applied, the mechanical sensor according to the invention distorts, varying the resistance of part (A) and thus allowing the strain to be measured. Preferably, the polymer used is a thermostable polymer.

Abstract: The invention relates to elastic surface wave pressure gauges.The gauge comprises a plate on which are located the electronic components of the gauge and a pressure sensor grouping the electromechanical elements on a header having connecting pins. The header is provided with a pressure inlet which traverses the plate.The invention is also applicable to the measurement of the pressures of fluids in order to optimize the supply to internal combustion engines. The pressure inlet is made of a rigid metal header and separately grounded for shielding of the surface acoustic wave electrodes to prevent "pull-in" where the oscillators inadvertantly lock on the same frequency.

Abstract: A flowmeter incorporating a pressure differential member creating a differential pressure between an upstream flow path and a downstream flow path of a pipe. The flowmeter has pressure connecting lines located on either side of the pressure differential member and constituted by conduits issuing on the surface of the device. The pressures in the upstream and downstream flow paths are transferred to a differential pressure sensor constituted by two elastic surface wave oscillators supplying signals, whose frequency is proportional to the pressures. The signals are then transmitted to a mixer, whose output supplies a beat signal, whose frequency is equal to the difference of the frequencies of the signal supplied by the oscillators. This frequency difference is directly proportional to the differential pressure.

Abstract: In order to bring about a reduction in the reflection coefficient due to reflections on the successive fingers of a transducer in the form of interdigitated transducer elements with split fingers of unequal length when a load impedance is applied at the terminals thereof, the invention provides for the displacement of at least the smallest minor lobe of the pulse response envelope, whose design is reproduced by the fingers, in order to position it in front of one of the maxima of the major lobe.

Abstract: A sensor of the type comprising two delay lines forming part of two oscillators whose output signals are mixed and in particular a surface acoustic wave sensor comprising a wafer made from a piezoelectric material comprising a calibrating device for calibrating the output frequency constituted by an additional delay line formed by a metal strip inserted in the connections of one of the oscillators. By means of a laser beam indentations are formed in this metal strip, thus causing an increase in the delay for adjusting the frequency of the output signals of the sensor to a predetermined value.

Abstract: An elastic surface wave filter including on the surface of a plate, an emitting transducer, a surface wave coupler, and means for receiving the waves radiated by the coupler. The means for receiving includes two transducers each having two terminals with one terminal of each being in common with one terminal of the other. The common terminal serves as a phase reference and the voltages induced at the remaining terminals are in phase opposition to one another in the transmission band of the filter.

Abstract: A surface elastic wave filter in which Rayleigh waves experience only small attenuation and phase-shift, the number of radiating elements encountered by the surface wave during the wave propagation having a direction parallel to an axis xx through the filter, being restricted. The filter comprises at least one electromechanical transducer constituted by two metallic comb structures A and B whose teeth d.sub.A1, d.sub.A2, d.sub.A3 and d.sub.B1, d.sub.B2, d.sub.B3 are interdigitated and are arranged at either side of an axis yy in symmetrical fashion vis-a-vis a point M located upon said axis, at the center of the transducer. The filter can be used to the filtering of video-frequency signals in television circuits.

Abstract: The present invention relates to the manufacture of surface acoustic wave transmission devices. The invention provides a method of cutting the edges of surface acoustic wave devices, which consists in directing on to that face designed to propagate said waves, a jet of abrasive particles.

Abstract: An elastic surface wave transmitting device comprising a piezoelectric substrate S.sub.1 on which is arranged a transmitting transducer T.sub.E placed on the center of the substrate S.sub.1, and two receiving transducers T.sub.R1 and T.sub.R2 arranged on either side of the transmitting transducer T.sub.E, means (a metallic wafer P.sub.1, for example deposited by evaporation on to the substrate S.sub.1) enabling the waves transmitted by the transmitting transducer T.sub.E towards each of the receiving transducers T.sub.R1 and T.sub.R2 to be phase-shifted so that the waves O.sub.1 and O.sub.2 respectively reflected by these receiving transducers T.sub.R1 and T.sub.R2 cancel one another out at the transmitting transducer T.sub.E.

Abstract: The present invention relates to electromechanical devices for the transmission of surface acoustic waves between a launching transducer and a receiving transducer arranged upon the main face of a substrate. The transmission device in accordance with the invention comprises ground zones provided in order to scatter the vibrational energy of bulk waves propagating within the thickness of the substrate. The creation of the ground zones involves the use of a jet of sand directed on to the large faces of the substrate.

Abstract: The present invention relates to surface elastic wave electromechanical devices. The electromechanical device in accordance with the invention comprises a central common transducer and two identical transducers interconnected electrically. The central transducer produces bi-directional radiation, and intermediate means are provided to selectively modify the propagation of the surface elastic waves.

Abstract: The present invention relates to electromechanical resonance devices comprising a piezo-electric crystalline plate and electrodes arranged opposite one another upon the principal faces of said plate. In accordance with the invention, the piezo-electric wafer is cut from a lithium niobate crystal, in accordance with the Y + 37.degree. cut.