Marelli Autronica S.p.a.

Roberto Dell'Acqua

Giuseppe Dell'Orto

Giuseppina Rossi

Gilberto Dendi

Silvano Donati

Giovanni Brunetti

An electrical force and/or deformation sensor includes a support structure constituted by a rigid plate in one face of which a recess is formed. The bottom wall of the recess is thin and is resiliently deformable under the action of a force or pressure to be measured. At least one piezoresistive sensitive element constituted by a thick-film resistor is applied to the other face of the plate in correspondence with the recess. Electrical conductor elements connected to the sensitive element or elements are also applied to this face of the plate to enable its connection to supply and processing circuits. These circuits may conveniently be produced by thick- or thin-film hybrid circuit technology on the same face of the support plate as that which carries the piezoresistive element or elements. In order to measure absolute pressure, the inlet opening of the recess may be closed by a gas-tight seal so as to define a closed cavity in the thickness of the plate, in which a vacuum is formed.

Electrical force and/or deformation sensor, particularly for use as a

The sensor comprises a body defining a closed chamber which is partially filled with electrically conductive liquid. A main electrode and first and second auxiliary electrodes extend within the chamber in such a way that a variation in the inclination of the body from a predetermined position causes a corresponding variation in the electrical resistance between each auxiliary electrode and the main electrode. The monitoring circuit for the sensor comprises a generator which applies square-wave signals to the auxiliary electrodes in counterphase, and a detector/amplifier which is synchronized with the generator and samples the signal taken from the main electrode in the sensor.

Electrical inclination sensor and a monitoring circuit for the sensor

The sensor includes a rigid support and a diaphragm having a peripheral portion fixed by a layer of glue to the support. The central portion of the diaphragm is spaced from the support and, on its surface facing the support, carries at least one thick-film resistor acting as a piezo-resistive transducer. The diaphragm can deform resiliently towards the support when a pressure is exerted on its other surface. The surface of the support which is connected to the diaphragm is flat, and the layer of glue has a calibrated thickness such that the distance between the diaphragm and the surface of the support at rest is substantially equal to the deflection of the diaphragm corresponding to a predetermined maximum pressure measured.

Pressure sensor

In a thick-film pressure sensor comprising a support plate on at least one surface of which are deposited at least one thick-film resistor acting as a piezo-resistive transducer and at least one pair of thick-film conductors acting as rheophores, the at least one thick-film resistor and the thick-film conductors are covered with a protective layer of dielectric material.

Thick-film sensor, particularly a pressure sensor

A pressure measuring device comprises a support casing having an aperture, a substrate mounted in the casing and deformable through the effect of a pressure to be measured introduced into the casing through the aperture, at least one electrical deformation sensor, preferably a thick-film resistor, applied to the substrate, circuit means housed in the casing and connected to the at least one electrical deformation sensor for outputting electrical signals indicative, according to a predetermined response curve, of the deformations of the substrate and hence of the pressure acting thereon, and manually-operable electrical adjustment means mounted in the casing and connected to the circuit means, for modifying predetermined characteristics of the response curve.

Pressure measuring device

The sensor comprises a body formed by first and second elements of which at least one has a cavity, the elements being sealed together to form a chamber. The chamber contains an electrically-conductive liquid which fills it almost completely so as to form a bubble. At least one main electrode and at least one pair of auxiliary electrodes extend into the chamber through the body and are accessible on the exterior thereof, so that any variation in the inclination of the body relative to at least one predetermined direction causes a movement of the bubble and a corresponding variation in the electrical resistance measurable between each auxiliary electrode and the main electrode. The electrodes are constituted by strips of electrically-conductive material deposited by screen printing on at least one of the said elements by thick film deposition method.

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Pavia, Italy

Roberto Dell'Acqua