Centre Electronique Horloger S. A.

Centre Suisse D'electronique Et De Microtechnique Sa

Csem Centre Suisse D'electronique Et De Microtechnique Sa&#x2014;recherche Et D&#xe9;veloppement

Claude Bourgeois

Jean W Hermann

David Ruffieux

Jacek Baborowski

Marc-Alexandre Dubois

The invention relates to a silicon resonator () of the tuning-fork type in which the linear frequency drift depending on the temperature is compensated. The resonator includes a silicon base (), a plurality of parallel arms () capable of vibrating and actuator (), wherein the arms include a silicon layer provided between two layers of silicon oxide having a thickness, relative to that of the silicon layer, such that it ensures the first-order compensation of the resonator thermal drift.

Silicon resonator of the tuning-fork type

A thin quartz plate having opposite major surfaces, each of the opposite major surfaces having a geometrical shape symmetrical or antisymmetrical with respect to an axis of reference; and X, Y and Z crystallographic directions corresponding to electrical, mechanical and optical axes, respectively, of the quartz plate, wherein the axis of reference forms an angle .psi. with said X axis, and the major surfaces form an angle .theta. with a plane defined by said X and Y axes, the angles .theta. and .psi. being chosen such that the first order frequency-temperature coefficient (.alpha.) of the quartz resonator is substantially 0, and the second order frequency-temperature coefficient (.beta.) of said quartz resonator is substantially 0. The shape of the resonator may be rectangular, square, polygonal, circular or elliptical. The resonator is fixed on a supporting base by means of at least one pair of connecting arms located on the extension of a nodal line. The resonator of the invention finds application in the field of relatively low frequency miniature resonators suitable for encapsulation.

Quartz resonator vibrating in a fundamental torsion mode

A piezoelectric resonator formed as a thin parallelepipedic quartz plate whose width is arranged along the electric axis X of the crystal, the length along an axis Y' and the thickness along an axis Z', wherein the axes Y' and Z' form an angle approximately equal to 24.degree. with the mechanical axis Y and the optical axis Z of the crystal, respectively, and the ratio w/l of its width to its length is approximately equal to 0.64.

Piezoelectric resonator

The piezoelectric resonator (1) comprises two plates (5,6) and at least two parallel bars (2 to 4) connecting the plates (5,6) to each other. The orientation of the quartz wafer in which the resonator (1) is cut and the arrangement of the electrodes (9 to 11, 15 to 17) on the bars (2 to 4) are such that these bars (2 to 4) vibrate in an elongation mode. The elongation mode of the bars is coupled to a plate and bar flexure mode to improve the thermal properties of the resonator. This resonator can be used in devices in which the dimensions of the resonator have to be as small as possible and/or in which its resonance frequency has to be as low as possible.

2T-cut piezoelectric resonator using coupled contour modes

A ZT-cut quartz crystal resonator comprises two thin rectangular plates connected together by at least one resonant arm which itself is connected to a support zone by a linking bar. A pair of electrodes is provided on the quartz resonator for receiving alternating electrical signals of opposite polarity for effecting in-phase contour-mode vibration of the plates while making the arms to vibrate in opposite phase to the plates.

ZT-Cut piezo-electric resonator

The resonator according to the invention comprises at least one quartz crystal in the form of a rectangular thin plate, of which the length l is directed along an axis X', the width w along an axis Y' and the thickness t along an axis Z', and which vibrates in a contour mode. The axis Z' is situated in the plane of the electrical axis X and optical axis Z of the crystal and forms with the axis Z an angle .phi. such that

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Bole, Switzerland

Claude Bourgeois