Office National D'etudes Et De Recherches Aerospatiales

Office National D'etudes Et De Recherches Aerospatiales (onera)

Vincent Gaudineau

Jean Guerard

Denis Janiaud

Olivier Le Traon

Claude Chartier

Raphaël Levy

Marc Pernice

Béatrice Verlhac

Pierre Lavenus

Guillaume Aoust

Oliver Le Traon

Rachid Taibi

Thomas Perrier

An electrical field detector includes an electromechanical oscillator, part of which is included of a piezoelectric element, a frequency measuring device which is coupled to the oscillator so as to measure the oscillation frequency, and an electrical masking assembly. The electrical masking assembly is arranged close to the piezoelectric element so that, during an use of the detector, the piezoelectric element moves by vibrating relative to the electrical masking assembly. A variable part of the piezoelectric element is thus exposed to the electrical field to be measured. A change in the oscillating frequency then forms an electrical field measurement result.

Electric field detector

An electric measurement circuit possesses an electrical reaction leg for forming an oscillator from a resonator, and furthermore possesses a measurement leg the input of which is supplied by the electrical reaction leg. The measurement leg contains an adjustable phase shifter so that an additional excitation force that is applied to the resonator in the measurement leg can be adjusted in phase quadrature with respect to an excitation force that is applied to the resonator in the electrical reaction leg. Such an electrical measurement circuit is particularly suitable for forming a photoacoustic gas detector.

Electrical measurement circuit, gas detector and method for measuring a gas concentration

The invention is a device for measuring the temperature of the vibrating beam of a vibrating-beam sensor. It comprises a resonator () vibrating in torsion in resonant mode and exhibiting a torsional vibration node (N), said node being its zone of fixing in the vicinity of the middle of the length (L) of the vibrating beam, said fixing allowing thermal transfers between the resonator and the beam. The frequency of the resonator and the variations of this frequency are representative respectively of the mean temperature T of the beam and of the variations of this temperature T, the effects of which may be compensated by a model.

Device for measuring the temperature of a vibrating beam and application to the improvement of the precision of measurement of a vibrating-beam sensor

Mechanical resonators for making timepieces have the drawback of not being simultaneously efficient, compact, and inexpensive. The invention is a planar structure of a mechanical resonator () that is suitable for reducing bulkiness and manufacturing cost and comprises a bar (R) vibrating in longitudinal expansion/compression resonance and two beams, () each vibrating simultaneously in longitudinal expansion/compression and it bending oscillation in the plane of the structure and connected to the bar by a connection element () on the median plane (&#x3c0;) of the bar, thereby enabling the effects of the transverse deformations of the bar, due to the Poisson ratio of the material, to not be transmitted to the attachment pads (PF) of the resonator. Thus, the quality factor of the resonator can be very high.

Planar structure of a mechanical resonator decoupled by bending oscillation and expansion/compression vibrations

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Palaiseau, France

Vincent Gaudineau