High quality factor flexural vibration resonator, force sensor or gyro tester for generating a time reference

Abstract

A resonator is adapted to reduce or suppress forces transmitted from a vibrating part to a supporting part (Pf) of the resonator. To this end, the vibrating part comprises two extensions (P1, P2) each of which is shaped in such a way that two segments of each extension have respective velocity components oriented in opposite directions. Such a resonator, which is balanced, can advantageously be used in a gyro tester or a force sensor.

Description

Technical Field

[0001] This specification relates to a resonator having a vibrating portion formed in a wafer having parallel surfaces, and a force sensor and gyroscope tester including the resonator. Background Technology

[0002] Flexural resonators are widely used to create time references, gyroscopes, and force sensors. Best known examples include, for instance, a quartz crystal tuning fork for providing a time reference, as described in U.S. Patent No. 3,683,213; a double-ended tuning fork for forming a force sensor, as described in U.S. Patent No. 4,215,570; a double-ended tuning fork for measuring rotational speed, as described in U.S. Patent No. 61,529,400; or a simple tuning fork with a decoupled structure for measuring rotational speed, as described in U.S. Patent No. 6,414,416.

[0003] In the case of a piezoelectric flexural resonator made of quartz crystal, the orientation of the resonator beam is typically chosen along the crystal axis Yc, and the planar structure of the resonator is parallel to the crystal plane Xc-Yc. On the one hand, this allows optimal benefit from piezoelectric coupling to excite and detect flexural vibrations in the planes Xc-Yc and Yc-Zc, and on the other hand, from higher etching rates along the axis Zc used for etching the structure using an acid-type wet etching process, typically with a mixture of ammonium fluoride (NH4F) and hydrofluoric acid (HF). In practice, the piezoelectric tensor of the triangular crystal provides optimal coupling with respect to the deformation Syy (i.e., along the beam axis) with respect to the electric field Exx. For this purpose, electrodes positioned along the beam are used to excite the flexural vibrations of the beam via a direct piezoelectric effect to generate the electric field Exx, and the deformation Syy is detected via the charge generated by the indirect piezoelectric effect on these same electrodes. Several alternative configurations of the electrodes are possible. For example, the electrodes can be arranged on both sides of the wafer in which the resonator is formed, such as for vibrational motion parallel to the direction Xc. Figure 1a As shown in the figure, or as for out-of-plane vibration motion parallel to direction Zc, [ Figure 1b As shown in the image. Figure 1a ]and[ Figure 1b The electric field component Exx necessary for generating the bending of the beam is further shown for each of the illustrated electrode configurations. Such a configuration with electrodes on the surface of the wafer is simple to implement. However, other electrode configurations are also possible, such as electrodes arranged on the side of the beam perpendicular to the surface of the wafer. Such other configurations are more effective at generating the bending of the beam, but are more difficult to implement, as described, for example, in U.S. Patent No. 4,524,619.

[0004] When these resonators are produced by wet chemical etching of wafers with parallel planes, the asymmetry in the pattern of the resonator caused by the crystal orientation of the etched planes alters the subsequent operation of the resonator. In fact, in the case of crystals with near-32-fold triangular symmetry, such as quartz, it is well known that beams with oriented Yc etched using a mixture of NH4F-HF have perfectly orthogonal sides in the Xc- direction and dihedral sides in the Xc+- direction. Subsequently, due to the triangular symmetry of quartz, this pattern itself repeats every 120° (degrees), as shown in […]. Figure 2a As shown in the image. Figure 2b The diagram illustrates a typical result obtained for a quartz tuning fork, where the wafer facets are parallel to the plane Xc-Yc and the beam is oriented longitudinally along the axis Yc. The facet fd on the side of the beam of the tuning fork breaks the symmetry with respect to the plane P orthogonal to the wafer facets, and the facet fo at the embedded end of the beam breaks the symmetry with respect to the midplane M of the resonator.

[0005] The disruption of these symmetries leads to poor dynamic equilibrium in the resonator, resulting in vibrational energy loss in the resonator's attachments and thus degrading the resonator's quality factor and the stability of its vibrational frequency. These degradations are detrimental to using resonators to generate precision force sensors or time bases.

[0006] When such resonators are used to generate vibration gyroscope testers, the symmetry of the resonators breaks the parasitic mechanical coupling between the two useful vibration modes that typically generate the gyroscope tester. This leads to measurement bias, meaning that the output signal from the gyroscope tester is no longer zero when there is no rotation. The presence of this non-zero measurement bias significantly degrades the measurement accuracy of the gyroscope tester.

[0007] Compensation methods are then applied, typically by adding a mass at the end of the beam and adjusting the mass by laser ablation, to reduce imbalance and / or adjust the vibration frequency, as described in US 3,683,213, or to reduce orthogonal coupling in the case of a vibration gyroscope tester as described in US 61,529,400.

[0008] Orthogonal coupling in a gyroscope tester originates from the mechanical coupling connecting two useful modes of vibration of the gyroscope tester: a mode called the "leading mode," which typically corresponds to the tuning fork vibration mode; and an out-of-plane vibration mode called the "sensing mode," which is excited by Coriolis acceleration from the leading mode when the resonator rotates about the longitudinal direction of the beam. When there is a symmetry break in the resonator, it is primarily a symmetry break relative to the midplane M (see […]). Figure 2bA coupling stiffness arises between the lead mode and the sensing mode, which generates parasitic movement of the resonator in the sensing mode when rotation is absent. This defect significantly limits the performance of gyroscope testers by introducing measurement bias. However, performing localized and individually adjusted laser ablation on each manufactured resonator to correct such symmetry defects in the gyroscope tester is particularly expensive and often imperfect, leaving the final performance of the gyroscope tester still limited.

[0009] Other original methods for inherently reducing orthogonal coupling in vibrating quartz gyroscope testers have been implemented, for example in FR 2,944,102 filed by the applicant. In FR 2,944,102, the orientation of the vibrating beam is altered and a torsional vibration mode of the beam is used, which is coupled to a flexural vibration mode via Coriolis acceleration. These alterations make it possible to achieve perfect symmetry of the vibrating structure even when the resonator is fabricated using a low-cost process of chemically etching quartz. Orthogonal coupling is thus reduced by 3 to 4 orders of magnitude, as reported by Guérard et al. in their paper entitled “Quartz Structure for Coriolis Vibrating Gyroscopes” (DOI:10.1109 / ISISS.2014.6782534), but this is detrimental to the inherent thermal sensitivity of the gyroscope tester, which is significantly degraded due to the significant thermal dependence of the torsional mode, due to the inherent properties of quartz.

[0010] JP 2005-068690 discloses a primitive structure for a vibrating quartz gyroscope tester, wherein the sensitive axis is perpendicular to the plane of the structure. This vibrating quartz gyroscope tester utilizes the triangular symmetry of quartz and employs three beams oriented according to the crystal axis Yc. In this manner, the resulting gyroscope tester benefits from excellent piezoelectric coupling between the leader mode and the sensing mode. However, when the wafer is etched by chemical etching, this vibrating structure is asymmetrical relative to a plane orthogonal to the wafer's plane, and the vibrational modes involved do not allow for good dynamic balance of the resonator. The quality factor of the useful vibrational modes is degraded.

[0011] For force sensors, the double-ended tuning fork structure described in U.S. Patent No. 4,215,570 constitutes a noteworthy trade-off, specifically due to the extremely thin slot separating the two beams vibrating in opposite phases. This configuration ensures good coupling between the resonators while reducing deformation at the embedded ends of the beams. In this way, parasitic longitudinal movement that occurs when the beams vibrate and causes energy dissipation is reduced. This longitudinal movement is used, for example, in a musical tuning fork to transmit the vibration of the beams through the feet of the tuning fork to the resonant support in order to emit an audible sound that is extremely useful for tuning instruments. This example of longitudinal movement transmitted through the feet of the tuning fork clearly illustrates the energy leakage that occurs from the resonator through its feet to the outside. On the other hand, the double-ended tuning fork of U.S. Patent No. 4,215,570, when fabricated by chemical etching, is not symmetrical with respect to a plane orthogonal to the plane of the resonator, due to the dihedral angle present on the orthogonal side in the Xc+ direction. This geometric asymmetry also produces an asymmetry in the longitudinal force transmission in the two beams, resulting in unequal frequency changes in the two constituent beams of the tuning fork. This subsequently disrupts the tuning fork effect and, in fact, greatly reduces the value of the mass factor when the resonator is subjected to the axial tension to be measured. Alternatives to the double-ended tuning fork for making force sensors have been proposed, such as one described in FR 8,418,587 filed by the applicant. Specifically, FR 8,418,587 proposes associating a simple single-beam resonator with a given flexural vibration with the system via an inertial mass provided at the end of the beam, in order to decouple the vibration of this beam from the support. This resonator has two advantages: on the one hand, the single beam (tooth) for the tuning fork makes it possible to double the scale factor of the resonator, meaning the frequency variation with the axial tension to be measured; and on the other hand, the principle of decoupling provides high tolerance to possible alignment errors. However, this resonator is still bulky, which limits its use in small devices such as accelerometers, which are based on the resonator used as a sensor element and on the frequency variation associated with the force generated by the test mass via the acceleration to be measured. Another original alternative has been proposed in FR 2,739,190, also filed by the applicant, in which a simple flexural vibration resonator is integrated within the monolithic accelerometer structure, and a system for decoupling the vibration from the outside is provided at the monolithic accelerometer structure. Optimization of the simple flexural vibration resonator by improving the figure of merit F x Q / Sf has also been proposed in FR 2,805,344, also filed by the applicant, where F is the frequency of the resonator, Q is the resonant mass factor, and Sf is expressed as a function of the resonant frequency F x Q / Sf. 2The scaling factor expressed by the Hertz number. This improvement is achieved by using a beam with a non-constant cross-section, which provides a gain of 1.2 to the figure of merit F x Q / Sf, which represents the stability of the accelerometer bias, i.e., the stability of the resonator frequency in the absence of acceleration. However, these simple resonators are unsatisfactory for variable frequency force sensor applications that require inherent decoupling of the resonator and insensitivity to its attachment conditions in order to allow for easy and reliable force measurement. Based on this, one aspect of the invention is to propose a new force sensor that satisfies these inherent decoupling requirements, but instead of relying on a modification of the stiffness of a flexural vibrating beam generated by an axial force that acts as a restoring torque and thus modifies the resonant frequency, it modifies the flexural inertia generated by the displacement produced by the force applied to the resonator. The principle of this force sensor based on modified flexural inertia has been proposed, for example, in the paper "A Novel Resonant Accelerometer Based on Rigidity Change" by Y. Omura, Y. Nonomura, and O. Tabata (TRANSDUCERS 97, 1997, International Conference on Solid State Sensors and Actuators, Chicago). However, it is based on a non-decoupled resonator, which cannot meet the high requirements of applications that require a high quality factor resonator for measurement accuracy and resolution.

[0012] Importantly, it's crucial to reiterate at this stage that wet chemical etching, used to fabricate crystal resonators, is an inexpensive process, particularly well-suited for the mass production of microdevices while preserving the crystal's inherent quality factor. In fact, chemical etching based on localized chemical reactions allows for the dissolution of crystals atom by atom without altering or degrading the material's lattice. This is not the case for etching based on localized abrasion, such as ultrasonic processing using fine abrasive particles excited by ultrasound generated between a probe (ultrasonic generator) and the surface to be etched, or etching based on ion bombardment using ion kinetic energy. These latter two techniques alter the lattice at the etched edges over characteristic distances of tens of nanometers to a few micrometers for higher-energy etching, reducing the resonator's inherent quality factor, especially when miniaturization of the device is desired.

[0013] Technical issues

[0014] In light of this, one object of the present invention is to provide a novel resonator that improves upon at least some of the shortcomings of the prior resonators discussed above.

[0015] Specifically, one object of the present invention is to provide a resonator that reduces the loss of vibrational energy to the outside in order to provide an increase in the mass factor.

[0016] An auxiliary objective of this invention is to reduce symmetry defects caused by differences in etching rates between different crystal orientations of the material used to construct the resonator, which affect the shape of the resonator. Summary of the Invention

[0017] To achieve at least one of these or other objectives, a first aspect of the present invention provides a resonator comprising:

[0018] - A portion of a wafer having two flat and parallel opposing surfaces, the wafer portion being designed to flexurally vibrate during the use of the resonator, and referred to as the vibrating portion; and

[0019] - A support portion, which is external to the vibrating portion and connected to the vibrating portion via an intermediate segment of the wafer called a foot, the foot being integral with the vibrating portion and forming a rigid connection between the support portion and the vibrating portion.

[0020] In this resonator of the present invention, the vibrating portion has a first symmetry plane, called the mid-plane, parallel to and equidistant from two surfaces of the wafer, and a second symmetry plane, called the orthogonal symmetry plane, perpendicular to the mid-plane and longitudinally passing through the connection formed by the foot between the support portion and the vibrating portion. The intersection point between the mid-plane and the orthogonal symmetry plane constitutes the central axis of the vibrating portion.

[0021] The vibrating portion includes two extensions that each flexure and vibrate symmetrically from the foot on each side of the plane of symmetry orthogonal to the wafer.

[0022] According to some features of the invention, each extension has a longitudinal slot that extends from a plane of symmetry orthogonal to the wafer toward the distal end of the extension but does not reach the distal end, passing perpendicularly through the mid-plane of the vibrating portion, such that each extension is bent. The respective slots of the two extensions are symmetrical with respect to the plane of symmetry orthogonal to the wafer and converge at this plane. The vibrating portion thus includes two main segments, each connecting the foot to the distal end of one of the extensions, and two auxiliary segments interconnected at the plane of symmetry orthogonal to the wafer via their respective proximal ends, each of the two auxiliary segments extending to the distal end of one of the extensions to connect to one of the main segments at this distal end.

[0023] Thanks to this configuration of the vibrating section, and for vibration modes comprising only movement parallel to the midplane and symmetrical with respect to a plane of symmetry orthogonal to the wafer, the two main segments have instantaneous velocity components parallel to the central axis, which at every moment during vibration are in the opposite direction to the instantaneous velocity components of the auxiliary segment, which are also parallel to the central axis. These opposite velocity orientations allow some of their associated momentum components to at least partially compensate for each other, thus reducing the movement transmitted from the vibrating section to the foot. Therefore, the resonator has low vibrational energy loss, and thus its quality factor can be high.

[0024] Advantageously, the vibrating component can have a mass distribution such that vibration modes comprising only movement parallel to the mid-plane and symmetrical with respect to a plane of symmetry orthogonal to the wafer do not cause movement of the foot parallel to the central axis. In other words, compensation for the momentum component of the vibrating component parallel to the central axis of the resonator can be precise or nearly precise. In this case, the vibrational energy loss through the foot of the resonator is zero or nearly zero, and the mass factor can be extremely high.

[0025] In a preferred embodiment of the invention, the wafer material can be a single crystal and is triangular and piezoelectric. In this case, the central axis of the vibrating portion is parallel to the material axis Xc, and the two main segments and two auxiliary segments of the vibrating portion are parallel to the material axis Yc. In other words, one of the two extensions of the vibrating portion can be parallel to the crystal axis Yc+, and the other parallel to the crystal axis Yc-. For these embodiments, the two extensions of the vibrating portion can form an angle of 60° between them. Specifically, the wafer can be made of α-quartz crystal (α-SiO2) or any other crystal of the triangular system of symmetry class 32, such as gallium orthophosphate (GaPO4), germanium oxide (GeO2), gallium arsenate (GaAsO4), or LGX series crystals: lanthanum gallium silicate (LGS or La3Ga5SiO2). 14 ), Lanthanum gallium tantalate (LGT or La3Ga5, 5TaO, 5O) 14 ), or lanthanum gallium niobate (LGN or La3Ga5, 5NbO, 5O 14 ).

[0026] Alternatively, the two extensions of the vibrating part may form an angle of 180° between them.

[0027] When the wafer material is single crystal and is triangular or piezoelectric, the resonator of the present invention may further include:

[0028] - Excitation components adapted to generate flexural deformation of the vibrating portion, these excitation components comprising a first electrode and a second electrode electrically insulated from each other, the first electrode comprising, on each face of the wafer and for each major segment or auxiliary segment, a strip of conductive material centrally and longitudinally arranged on the segment within the width of the segment, and the second electrode also comprising, on each face of the wafer and for each major segment or auxiliary segment, two strips arranged on opposite sides of the strip of the first electrode on the segment; and

[0029] - Detection components adapted to measure the amplitude of the flexural deformation of the vibrating portion generated by the excitation components during use of the resonator, these detection components include circuitry for detecting currents appearing in the first and second electrodes.

[0030] Generally, in this invention, each extension of the vibrating portion may be widened at its distal end and parallel to the midplane, including the outer longitudinal edges of the main segment and auxiliary segments relative to this extension. This widening provides additional degrees of freedom to compensate for the momentum component of the vibrating portion parallel to the central axis. This thus facilitates the design of a resonator according to the invention and with a high quality factor.

[0031] Similarly, generally speaking, for the present invention, the resonator may also include additional segments of the wafer in the form of segments, referred to as guides, which are parallel to the central axis and extend from the proximal end of the interconnection of the auxiliary segments in a direction away from the foot. These guides may also help to compensate for the momentum components of the vibrating portion parallel to the central axis.

[0032] A resonator may comprise two vibrating portions formed on the same wafer and having corresponding guide rods. The two vibrating portions may then be interconnected by guide rods oriented relative to each other, such that the respective central axes of the two vibrating portions are superimposed.

[0033] According to another possibility, the resonator may also include two vibrating portions formed in the same wafer, the two vibrating portions being interconnected by corresponding feet of the two vibrating portions and oriented relative to each other such that the corresponding central axes of the two vibrating portions are again superimposed.

[0034] A second aspect of the invention provides a force sensor comprising a resonator according to the invention, wherein two vibrating portions are interconnected by their respective guide rods. This sensor is adapted to measure a tensile force applied between the respective feet of the two vibrating portions and parallel to the central axis of the two vibrating portions.

[0035] Finally, a third aspect of the invention relates to a gyroscope tester comprising at least one resonator according to a first aspect of the invention. The operation of this gyroscope tester utilizes coupling generated by a vibration mode having movement parallel to a mid-plane and a vibration mode having movement perpendicular to this mid-plane.

[0036] Preferably, the gyroscope tester may include a resonator with two vibrating portions interconnected by their respective feet and oriented in opposite directions. For this configuration of the gyroscope tester, two dissimilar uses are possible, depending on the selected pilot mode, each having a single responsive rotation axis. According to a first possible selection for the pilot mode, in this pilot mode, the two vibrating portions vibrate in opposite phases. Coriolis acceleration generated by rotation about an axis parallel to the common central axis of the two vibrating portions subsequently excites a dynamically balanced out-of-plane vibration mode. According to another possible selection, at this time in the pilot mode, the two vibrating portions vibrate in phase, and Coriolis acceleration generated by rotation about an axis perpendicular to the common central axis of the two vibrating portions and parallel to the mid-plane excites another dynamically balanced out-of-plane vibration mode. In a preferred embodiment of this gyroscope tester having two vibrating portions connected by their respective feet and simultaneously oriented relative to each other, the wafer may be made of quartz crystal, and each of the two vibrating portions positions its extension at 60° relative to each other and parallel to the crystal axis Yc. This configuration makes it possible to obtain optimal piezoelectric coupling for the vibrational mode to be excited or detected, as well as symmetrical fabrication of the resonator when manufactured by chemical etching. Attached Figure Description

[0037] Referring to the accompanying drawings, the features and advantages of the invention will become more apparent from the following detailed description of some non-limiting embodiments, the drawings of which include:

[0038] The already discussed [ Figure 1a [This is the remainder of the first possible electrode configuration suitable for piezoelectric coupling, which, in the case of beam materials that are piezoelectric and belong to a triangular system of symmetry class 32 (e.g., α-quartz), can be used for the excitation and detection of in-plane flexural vibrations of beams.]

[0039] The already discussed [ Figure 1b [Corresponding to a second possible electrode configuration for excitation and detection of out-of-plane vibrations] Figure 1a ];

[0040] The already discussed [ Figure 2a ] is the remaining part of triangular symmetry;

[0041] The already discussed [ Figure 2bThe image shows a resonator in the form of a tuning fork, as known in the art and obtained by chemically etching a quartz crystal using a mixture of ammonium fluoride and hydrofluoric acid, wherein the symmetry is broken when the two beams (teeth) of the tuning fork are parallel to the Y-axis.

[0042] [ Figure 3a This illustrates the momentum involved in a tuning fork with parallel beams, as known in the prior art.

[0043] [ Figure 3b [Corresponding to a tuning fork with non-parallel beams] Figure 3a ];

[0044] [ Figure 3c [Corresponding to a double-ended tuning fork with non-parallel teeth] Figure 3b It allows for global compensation of unbalanced momentum within each tuning fork;

[0045] [ Figure 4a [Illustration] is a plan view of the first resonator made of triangular piezoelectric material according to the present invention;

[0046] [ Figure 4b ] corresponds to [ Figure 4a The diagram shows the useful vibration modes of the first resonator and the deformation of its associated momentum.

[0047] [ Figure 4c ] corresponds to [ Figure 4a The image shows the electrodes that allow for the excitation and detection of useful modes of vibration in the case of a resonator made of a triangular piezoelectric crystal (e.g., quartz) of symmetry class 32;

[0048] [ Figure 4d ] corresponds to [ Figure 4c Cross-sectional view of the first resonator;

[0049] [ Figure 5a [Corresponding to the two possible improvements of the present invention] Figure 4a ];

[0050] [ Figure 5b ] corresponds to [ Figure 5a ], showing the deformation of the useful vibration mode;

[0051] [ Figure 6a [This is also a plan view of the second resonator made of piezoelectric material according to the present invention;]

[0052] [ Figure 6b ] corresponds to [ Figure 6a [This shows a variation of the useful vibration modes of the second resonator;]

[0053] [ Figure 6c [Corresponding to when using possible improvements of the present invention] Figure 6a];

[0054] [ Figure 6d ] corresponds to [ Figure 6c The resonator of ] Figure 6b ];

[0055] [ Figure 7a [Illustration 1] is a perspective view of a first gyroscope tester according to the present invention, and shows a variation associated with the pilot mode of the first gyroscope tester.

[0056] [ Figure 7b ] corresponds to [ Figure 7a ], but shows rotation about the first axis from [ Figure 7a The deformation produced by the leading mode of ];

[0057] [ Figure 7c ]For the second axis of rotation, corresponding to [ Figure 7b ];

[0058] [ Figure 7d For the third axis of rotation, corresponding to [ Figure 7b ];

[0059] [ Figure 8a This illustrates a variation of the second gyroscope tester according to the invention, the variation occurring in the first pilot mode;

[0060] [ Figure 8b ] corresponds to [ Figure 8a This illustrates a variation of the first sensing mode of a second gyroscope tester, generated by rotation about a first axis, starting from the first pilot mode.

[0061] [ Figure 8c [This shows other variations of the second gyroscope tester generated in the second pilot mode;]

[0062] [ Figure 8d ] corresponds to [ Figure 8b This illustrates a variation of the second sensing mode of a second gyroscope tester, generated by rotation about a second axis, starting from the second pilot mode.

[0063] [ Figure 9a This is a perspective view of the second gyroscope tester, showing its electrodes;

[0064] [ Figure 9b [This is a first cross-sectional view of the second gyroscope tester, corresponding to [] Figure 9a ];

[0065] [ Figure 9c [This is the second cross-sectional view of the second gyroscope tester, which also corresponds to [] Figure 9a ];

[0066] [ Figure 10a[Illustration] is a plan view of the first force sensor according to the present invention;

[0067] [ Figure 10b ] corresponds to [ Figure 10a The image shows the deformation associated with the useful vibration modes of the first force sensor.

[0068] [ Figure 10c ] corresponds to [ Figure 10a The image shows the static deformation of the first force sensor when subjected to axial tensile force.

[0069] [ Figure 11a The second force sensor according to the present invention corresponds to [ Figure 10a ];

[0070] [ Figure 11b For the second force sensor, corresponding to [ Figure 10b ];as well as

[0071] [ Figure 11c For the second force sensor, corresponding to [ Figure 10c ]. Detailed Implementation

[0072] For clarity, the dimensions of the components shown in these figures do not correspond to actual dimensions or actual size ratios. Specifically, all resonator distortions shown have been magnified to a level that provides better visibility. Furthermore, the same numbers indicated in different figures refer to the same or equivalent components or measurements.

[0073] Now refer to [ Figure 4a ]-[ Figure 4d A first resonator according to the present invention is described. This first resonator includes a support portion or fixed portion designated by reference numeral Pf, a vibrating portion, and a foot Pd connecting the vibrating portion to the fixed portion Pf. Preferably, the fixed portion Pf, the vibrating portion, and the foot Pd are formed simultaneously by chemical etching in a wafer having parallel surfaces, such that the material of these three resonator portions is continuous. When the thickness is measured perpendicular to the surface of the wafer, the wafer used can have a thickness between a few micrometers and a few millimeters. Figure 4a ]-[ Figure 4dThe resonator's vibrating portion includes two extensions, P1 and P2, extending from the base Pd and forming a non-zero angle α between them. The two extensions P1 and P2 extend symmetrically to both sides of a central axis aligned with the longitudinal direction of the base Pd. This central axis corresponds to the intersection of a first plane of symmetry and a second plane of symmetry, the first plane of symmetry being parallel to the surface of the wafer and located at its intermediate thickness, and the second plane of symmetry being orthogonal to the surface of the wafer, with the two extensions P1 and P2 corresponding via reflection symmetry. In the remainder of this specification, and similar to the tuning fork resonator described in U.S. Patent No. 3,683,213, the two extensions P1 and P2 are also referred to as beams P1 and P2. According to the invention, longitudinal slots are provided in each beam P1, P2, and are designated by reference numerals FL1 and FL2, respectively. These two longitudinal slots FL1 and FL2 meet at the central axis of the resonator. Each beam P... i Therefore, it includes two blades L iext and L iint The index i is equal to 1 or 2. In the majority of this specification, the blade L... 1ext (correspondingly L) 2ext The main segment of the extension P1 (and correspondingly P2) is called the blade L. 1int (correspondingly L) 2int This is called a secondary segment of the extension P1 (and correspondingly P2). Therefore, the two blades L 1ext and L 2ext Connected to foot Pd and extending to the corresponding distal ends of extensions P1 and P2, where they are connected one-to-one to the two blades L. 1int and L 2int Each extension P1, P2 is therefore bent between the central axis and its distal end. Additionally, the blade L... 1int and L 2int Through these two blades L 1int and L 2int The corresponding proximal ends are interconnected at the central axis. The two longitudinal slots FL1 and FL2 of the corresponding beams P1 and P2 also meet at the central axis, causing the two blades L... 1int and L 2int The corresponding proximal junction with the blade L 1ext and L 2ext Separate and separate from foot Pd. For example [ Figure 4b As shown in the figure, when the distal ends of beams P1 and P2 move symmetrically away from the central axis in opposite directions during the vibration of the resonator, the blade L... 1ext and L 2ext Having corresponding momentum MV1 and MV2, it is tilted but symmetrically oriented toward the same side of the resonator as foot Pd, and the blade L 1int and L 2intThe connector has momentum MV 12 It is parallel to the central axis and oriented away from the foot Pd. Therefore, the blade L 1int and L 2int It has a corresponding momentum that is tilted but symmetrically oriented toward the resonator relative to foot Pd. Subsequently, according to the optimization proposed in this invention, this can be achieved in all blades L 1ext L 2ext L 1int and L 2int The mass distribution of the vibrating section between the blades ensures that the movement of foot Pd generated by these momentum is zero or almost zero. Due to this lack of movement of foot Pd, the vibrational energy transfer from the vibrating section to the supporting section Pf is zero or extremely low, thus allowing for a high mass factor for the resonator. The optimized mass distribution between the four blades of the vibrating section remains symmetrical with respect to the central axis and can be achieved by adjusting the mass distribution of two blades L... 1ext and L 2ext Assign common thickness e ext The obtained common thickness is different from that of the two blades L. 1int and L 2int The representation of is e int The common thickness. When this type of optimization is applied, the resonator is called balanced. Blade thickness e ext and e int It was measured parallel to the surface of the wafer.

[0074] According to [ Figure 5a The invention is illustrated together but can be used independently of each other. The vibrating portion of the resonator can be supplemented by two inertial masses MI1 and MI2 for the first improvement, and by a guide rod Pc for the second improvement. Preferably, the two inertial masses MI1 and MI2 are located at the distal ends of two beams P1 and P2 and are identical. They can each be formed by widening the corresponding beams P1 and P2 located at their distal ends. The guide rod Pc can be formed by additional blades parallel to the central axis in a direction away from the foot Pd and superimposed on the blade L. 1int and L 2int The joint extends to the proximal end. Advantageously, the guide rod Pc is also symmetrical with respect to the central axis. Adding two inertial masses MI1 and MI2 and / or the guide rod Pc to the vibrating part of the resonator makes it possible to obtain the resonator's equilibrium with additional degrees of freedom. Figure 5b The diagram illustrates the movement of inertial masses MI1 and MI2 and guide rod Pc at the same moment during the vibration of the resonator. The two inertial masses MI1 and MI2 subsequently possess momentum components along the central axis that are opposite to the momentum component of guide rod Pc. By applying the present invention, these momentum components of inertial masses MI1 and MI2 and guide rod Pc are related to the four blades L... 1ext L2ext L 1int and L 2int The combination of those momentum components produces a zero or essentially zero movement of foot Pd.

[0075] It should be noted that, for matters known in the prior art and in [ Figure 3a The tuning fork with parallel beams, as shown in [ ], naturally achieves balance for this type of resonator because the two beams P1 and P2 are identical. The momentum of the two beams P1 and P2 are again represented as MV1 and MV2, respectively. According to [ Figure 3a This resonator does not cause its foot Pd to move parallel to its central axis X during its vibration because the momentum MV1 and MV2 are perpendicular to this central axis. Furthermore, for vibration modes in which two beams P1 and P2 move in opposite phases, if the two beams P1 and P2 are identical, then the momentum MV1 and MV2 of the two beams... 2进行 Compensation. The tuning fork resonator is then balanced. Therefore, no vibrational energy is transmitted through beams P1 and P2 to foot Pd, thus neglecting the deformation of this foot at the embedded ends of the two beams P1 and P2, which generates bending moments Mf1 and Mf2 and shear forces T1 and T2, especially when the gap separating the two beams P1 and P2 is narrow. However, as mentioned above, this resonator with parallel and symmetrical beams cannot be fabricated solely by chemically etching a wafer of triangular 32 crystalline material because this would create an etched surface that breaks the shape symmetry between the two beams P1 and P2. To obtain two beams with symmetrical shapes, it is possible to fabricate the resonator with its two beams P1 and P2 parallel to the axes Yc+ and Yc- of the triangular 32 crystalline material, and the central axis of the resonator parallel to the crystalline axis Xc. But then the two beams P1 and P2 of the tuning fork are no longer parallel, and for this reason, it becomes impossible to achieve resonator balance. Due to [ Figure 4a ]-[ Figure 4d Using the longitudinal slots FL1 and FL2 according to the invention, resonator balancing is again possible, but its beams P1 and P2 are not parallel to each other.

[0076] However, the inventors point out that, for [ Figure 3b The resonator, by making its vibrating portion symmetrical with respect to the plane YZ, can potentially achieve its balance as a non-parallel beam. The vibrating portion thus comprises four beams P1, P2, P3, and P4, which can have symmetrical shapes, such as those produced by chemical etching from a triangular-class 32 crystalline material. The resonator's foot Pd is located at the intersection of these four beams. In this case, the resonator is balanced for the vibrational modes of two of the tuning forks vibrating in phase. However, as […] Figure 3c The double-ended tuning fork resonator configuration thus obtained, as shown in the diagram, is larger and may not be well-suited for applications requiring significant miniaturization. For such applications, [ Figure 4a]-[ Figure 4d ]or[ Figure 5a ]-[ Figure 5b The resonator of [ ] can be preferred.

[0077] for[ Figure 4a ]-[ Figure 4d ]or[ Figure 5a ]-[ Figure 5b The resonator has an angle α between the two beams P1 and P2 equal to 60°. In this way, it is possible to obtain a symmetrical embodiment by chemically etching a wafer with parallel planes made of a triangular 32 crystalline material, by longitudinally oriented beams P1 and P2 parallel to the crystal axes Yc+ and Yc-, and the central axis parallel to the crystal axis Xc, with the wafer face perpendicular to axis Z. For example, the wafer material can be single-crystal α-quartz, which is piezoelectric. In this case, the resonator can have two electrodes, such as […]. Figure 4c ]and[ Figure 4d As shown in the figures. These electrodes can be used in a known manner as components for exciting symmetrical vibrational modes, and as components for detecting the vibrational amplitude in this same mode. The reference numerals in these two figures have the meanings listed below:

[0078] For those that can be connected to electrical ground First electrode :

[0079] The segment of the first electrode of PC1 supported by the resonator's support portion Pf.

[0080] el 1-PC1 The segment of the first electrode carried by the resonator's pin Pd.

[0081] On the first surface of the two sides of the wafer, the first electrode is formed by blades L. 1ext Fragments carried along its outer edge

[0082] On the first surface of the wafer, the first electrode is formed by blades L. 1ext Fragments carried along its inner edges

[0083] On the first surface of the wafer, the first electrode is formed by blades L. 1int Fragments carried along its inner edges

[0084] On the first surface of the wafer, the first electrode is formed by blades L. 1int Fragments carried along its outer edge

[0085] EL7 and EL9 are for blade L 2int Corresponding to el6 and el4 respectively

[0086] el 10 and el 12For blade L 2ext Corresponding to el3 and el1 respectively

[0087] el 1-6 On the first surface of the wafer, at the distal end of beam P1, there is an electrical connection segment between segments el1 and el6.

[0088] el 3-4 On the first surface of the wafer, at the distal end of beam P1, there is an electrical connection segment between segments el3 and el4.

[0089] el 7-9 On the first surface of the wafer, at the distal end of beam P2, there is an electrical connection segment between segments el7 and el9.

[0090] el 10-12 At the far end of beam P2 and on the first surface of the wafer, in segment el 10 With el 12 Electrical connection segments between them.

[0091] The first electrode segments el6 and el7 are interconnected at the central axis, as are segments el4 and el9, and segments el3 and el 10 That's also true.

[0092] For those that can be connected to an AC voltage V source Second electrode :

[0093] PC2 and el 2-PC2 Corresponding to PC1 and el respectively 1-PC1 ,

[0094] And for the second electrode

[0095] el2 is on the first surface of the wafer, and the second electrode is formed by blade L. 1ext Fragments carried in its central part

[0096] el5, el8 and el 11 Corresponding to blade L 1int L 2int and L 2ext el2

[0097] el 2-5 On the first surface of the wafer, at the far end of beam P1, there is an electrical connection segment between segments el2 and el5.

[0098] The second electrode segments el5 and el8 are interconnected at the central axis, and segments el2 and el... 11 That's also true.

[0099] For an integer index n varying from 1 to 12, the electrode segment el 10nThe segments corresponding to the second side of the wafer, respectively. n This includes electrical connection segments similar to those described for the first side of the wafer. Finally, segments of the same electrode in the two electrodes located on each of the two sides of the wafer are electrically interconnected via electrical connections carried by resonators or via external electrical connections.

[0100] Each electrode segment can be composed of strips of conductive materials such as gold (Au) deposited using thin-film deposition techniques, and has a width equal to 200 μm (micrometers). According to the list just provided, three parallel strips are arranged on each blade surface, meaning a total of twelve conductive strips per side of the wafer: el1 to el2 on the first side. 12 and the el on the second side 101 to el 112 If you have already referred to […] Figure 1a The explanation is that the three conductive strips on each blade surface effectively excite and detect flexural vibrations parallel to the plane Xc-Yc of the blade when the blade extends longitudinally along the crystal axis Yc+ or Yc-. For increased efficiency of the piezoelectric coupling, it is advantageous that the strip of the first electrode is relatively thin, with the strip width within the blade's L... 1ext L 2ext L 1int and L 2int thickness e ext or e int The width of the stripe for the second electrode can be between 1 / 10 and 1 / 5 of the width of the stripe for the first electrode.

[0101] This arrangement of electrodes for vibration excitation and detection via the piezoelectric effect is suitable for flexural vibration modes in which two beams P1 and P2 move in opposite phases, such as [ Figure 4b As shown in the figure. However, other electrode configurations are alternatively possible, for example, by depositing conductive material strips on the side of the blade perpendicular to the wafer face. In this case, strips el1 and el2... 101 blade L 1ext The single strip on the side is replaced, and for the first electrode, it is replaced by other strips L. 1int L 2int and L 2ext Individually carried strip pairs are similar. Each blade side carries two strips, each close to the edge of the side opposite the edge of the other strip, where one of the two strips belongs to the first electrode and the other to the second electrode. This other electrode configuration is for piezoelectric coupling ratio [ Figure 4c ]-[ Figure 4d The configuration is more efficient, but at the cost of greater complexity in its production.

[0102] The resonator can therefore be associated with an electronic oscillator loop connected to the input of segment PC1, the first electrode on the support portion Pf of the resonator, and to the output of segment PC2, also on the support portion Pf. Thus, an AC voltage V applied by the electronic oscillator loop between the two electrodes excites the two beams P1 and P2 in opposite phase vibration modes, and the vibration amplitude of the resonator for this same mode is detected by the current generated in the two electrodes by the vibration of the resonator. For this purpose, a current sensing circuit with advantageously high input impedance can be used in the electronic oscillator loop.

[0103] The inventors now provide some rules that, according to the present invention, allow for […]. Figure 4a ]-[ Figure 4d The resonator balance is achieved without the need for inertial masses MI1, MI2 or guide rod Pc. The resonator frequency F for the flexural vibration mode in which two beams P1 and P2 move in opposite directions can be approximated by the following equation (Equation 1):

[0104]

[0105] It has the following meanings, some of which have already been provided:

[0106] e int Blade L 1int and L 2int The common thickness, measured parallel to the surface of the wafer and expressed in meters.

[0107] e ext :L 1ext and L 2ext The common thickness, measured parallel to the surface of the wafer and expressed in meters.

[0108] L int Blade L 1int and L 2int The common length, expressed in meters.

[0109] L ext Blade L 1ext and L 2ext The common length, expressed in meters.

[0110] F l The common width of the longitudinal slots FL1 and FL2 in extensions P1 and P2, measured parallel to the surface of the wafer and expressed in meters.

[0111] E: Young's modulus of the wafer material, expressed in Newtons per square meter (N / m²) 2 )Express

[0112] ρ: Density of the wafer material, expressed in kilograms per cubic meter (kg / m³)3 )Express.

[0113] To allow for compensation of the momentum component parallel to the axis Xc at foot Pd, dimension e is also necessary. int e ext L int and L ext The following conditions must be met (Equation 2):

[0114]

[0115] However, this condition means that the blade L 1ext L 2ext The thin length L of each of them ext / e ext Larger than blade L 1int L 2int The thin length L of each of them int / e int Equation 2 can also be written in the following form (Equation 3):

[0116] in

[0117] The positivity of 1-k makes it possible to give the quotient e. ext / e int The first limit: This quotient is greater than 0.4.

[0118] Furthermore, by construction, the following equation relates the blade L via the angle α that separates the two beams P1 and P2. ext and L int Length (Equation 4):

[0119]

[0120] It has five unknowns e ext e int L ext L int and F l These last three equations allow those skilled in the art to select the size of the resonator based on the given application and technical constraints, specifically based on the space available for the resonator in each application.

[0121] For example, for a crystal wafer of a triangular system with symmetry class 32, such as piezoelectric α-quartz, and for an angle α of 60° between two beams P1 and P2, each beam is oriented parallel to the crystal axis Yc, one beam parallel to Yc+ and the other parallel to Yc-, to ensure the symmetry of the resonator obtained by chemical etching as explained, it is possible to calculate the symmetry of the blade L. 1int and L2int The common slenderness P between 3 and 10 int =L int / e int and the L-shaped blade 1ext and L 2ext Another slender length P, common to both 8 and 30 ext =L ext / e ext And has a quotient e between 1 and 5 int / e ext The size of the balanced resonator. For example, L int ~2.5mm (millimeters), e int ~0.24mm, L ext ~3.3mm, e ext ~0.15mm, and F l ~0.27mm, producing a resonator with a vibration frequency F equal to 32kHz (kilohertz). L can also be used. int ~4.95mm, e int ~1.5mm, L ext ~8.9mm, e ext ~1.7mm and F l A 0.7mm diameter yields the same value of 32kHz for frequency F, demonstrating the extent to which the size of a balanced resonator is possible when using this invention.

[0122] For a given resonator designed for flexural vibration, the resonator's intrinsic mass factor is limited by thermoelastic losses, which arise from heat exchange between the fibers of each blade during compression and stretching, as theorized in C. Zener's paper entitled "Internal Friction of Solids" (Physical Review 52, ​​August 1937, pp. 230-235). In the case of quartz, and for a simple beam having flexural vibrations at frequencies between several kilohertz and several hundred kilohertz, the thermoelastic mass factor is proportional to the resonator's frequency F multiplied by the square of the vibration thickness: Q 热弹性 (quartz)∝Fe 2 In the case of silicon and for the same frequency interval, this thermoelastic factor is proportional to the resonator frequency F divided by the square of the vibration thickness e: ∝F / e 2 This leads to extremely different dimensional determinations between the two crystals for the resonator. Therefore, in the case of quartz and when considering the desired frequency stability performance of the resonator, the thickness e corresponds to... int and e ext The determination of the size of the significant value is preferred, and the opposite is true for silicon.

[0123] According to [ Figure 4aCompared to the resonator configuration of [previous configuration], adding the guide rod Pc modifies the momentum generated by vibration along the axis Xc: the momentum component of the guide rod Pc is added to the blade L. 1int and L 2int Those momentum components. This makes it possible to increase the likelihood of determining the dimensions for achieving resonator equilibrium. Specifically, the addition of the guide rod Pc allows for […]. Figure 4a Compared to the configuration with added blades, the L configuration is... 1ext and L 2ext thickness e ext .

[0124] Again with [According to] Figure 4a Compared to the resonator configuration of [previous configuration], adding inertial masses MI1 and MI2 to the far ends of beams P1 and P2 also makes it possible to modify the momentum distribution among all parts of the vibrating section. Specifically, the addition of inertial masses MI1 and MI2 allows for modifications to the momentum distribution along their length L. int The equal value increases the leaf L 1int and L 2int thickness e int .

[0125] [ Figure 6a ]or[ Figure 6c The resonator of ] corresponds to [ Figure 5a The resonator, but the angle α is equal to 180° instead of 60°, Figure 6a [Does not have a guide rod and] Figure 6c It has a guide rod Pc. The blade L... ext and L int The lengths become equal, and the conditions of Equation 3 previously provided for resonator balance without guide rod Pc and without inertial masses MI1 and MI2 are no longer satisfied. Inertial masses MI1 and MI2 are necessary to compensate for momentum when angle α equals 180°. When the resonator does not have a guide rod, in [ Figure 6b In or when the resonator contains a conductor Pc in [ Figure 6d The vibration modes shown in the figure mainly correspond to the two blades L mentioned above. 1int and L 2int The continuous flexural vibration of the union of blades, wherein the two blades have a total length equal to the sum of their individual lengths, and again have a thickness e. int The frequency F of the resonator used for this vibration mode can be approximated by the following equation (Equation 5):

[0126]

[0127] in:

[0128] L intThe total blade length measured between the two inertial masses MI1 and MI2, expressed in meters.

[0129] e int The width of the blade opposite to foot Pd, measured parallel to the surface of the wafer and expressed in meters.

[0130] L c The length of the guide rod Pc, measured parallel to the wafer surface and expressed in meters.

[0131] e c : The width of the guide rod Pc, measured parallel to the surface of the wafer and expressed in meters.

[0132] E: Young's modulus of the wafer material, expressed in Newtons per square meter (N / m²) 2 )Express

[0133] ρ: Density of the wafer material, expressed in kilograms per cubic meter (kg / m³) 3 )Express.

[0134] To allow for compensation of momentum along axis Xc, dimension e is also necessary. int e ext L int e Mi L Mi L c and e c The following two inequalities (Equation 6) are satisfied:

[0135]

[0136] It has the following additional meanings:

[0137] e ext The width of the blade connected to pin Pd, measured parallel to the surface of the wafer and expressed in meters.

[0138] e Mi The common width of inertial mass bodies MI1 and MI2, measured parallel to the blade and expressed in meters.

[0139] L Mi The common length of inertial mass bodies MI1 and MI2, measured parallel to axis Xc and expressed in meters.

[0140] J: The moment of inertia per unit surface area of ​​inertial mass bodies MI1 and MI2, which is equal to (Equation 7):

[0141] J = L Mi ·e Mi ·(L Mi 2 +e Mi 2 )

[0142] The double inequality in Equation 6 makes it possible to determine [the value] based on certain initial choices made according to the desired characteristics of these resonators. Figure 6a ]-[ Figure 6d The size of the resonators is adjusted to ensure they are balanced.

[0143] It is possible that the dimensional determination of each of the resonators mentioned above, using the rules provided above, can be continued using digital simulations such as finite element calculations to achieve a more accurate balance of these resonators.

[0144] The resonator described above can be used to form a gyroscope tester with one or more sensitive axes. The sensitive axis of the gyroscope tester is the axis of rotation around which the gyroscope tester allows measurement of rotational speed. To obtain a gyroscope tester with three sensitive axes, thus making it possible to measure the rotational speed components along axes X, Y, and Z respectively, a resonator with an angle α different from 0° and 180° is necessary. Such a resonator with an angle α equal to 60° is preferred. During the rotation of the resonator, Coriolis acceleration produces an additional displacement for each blade of the resonator, perpendicular to the displacement of this blade for the pilot mode. Figure 7a Recall that when α equals 60° and the vibration mode excited by the electrodes (i.e., the leader mode) is a mode in which the two beams P1 and P2 move in opposite phases parallel to the plane of the wafer in a tuning fork manner, the resonator according to the invention exhibits simultaneous displacement of beams P1 and P2 and guide rod Pc. MV1, MV2, and MV c Specify the corresponding momentum of beams P1 and P2 and guide rod Pc. Figure 7b The corresponding Coriolis acceleration is shown, denoted as Γ. C It is generated by rotation about axis X, and has a rotational speed Ω. y ;[ Figure 7c This shows the accelerations produced by rotation about axis Y, with rotational speed Ω. y ;as well as[ Figure 7d This shows the accelerations produced by rotation about axis Z, with rotational speed Ω. z These Coriolis accelerations are perpendicular to the crystal used for rotation about axes X and Y, where the symbol of a dot surrounded by a circle represents the Coriolis acceleration toward the reader, and the cross surrounded by a circle represents the Coriolis acceleration oriented in the reader's gaze direction. However, the inertial force from these Coriolis accelerations is not compensated at foot Pd, so additional means are preferably provided to limit the loss of vibrational energy occurring through foot Pd of the resonator. For example, a decoupling structure as described in U.S. Patent No. 6,414,416 filed by the applicant can be used in a gyroscope tester with a single sensitive axis as axis X (see […]). Figure 7bThis decoupling structure effectively reduces or avoids the transmission of torsional torque to the resonator's attachment portion via the resonator's pin Pd. For gyroscope testers with only one sensitive axis as axis Y (see […]), this is because the decoupling structure effectively reduces or avoids the transmission of torsional torque to the resonator's attachment portion via the resonator's pin Pd. Figure 7c ]), coupled to [ ]) via rotational speed Ωy Figure 7a The leading mode of vibration is characterized by two beams, P1 and P2, undergoing in-phase out-of-plane bending, while the guide rod Pc undergoes out-of-plane bending in the opposite phase to beams P1 and P2. However, the resulting force is not compensated at the resonator's foot Pd, and the residual torque is transmitted to the resonator's attachment via the foot Pd. (From […]) Figure 7a The leading mode of rotation about axis Z (see [ ]) Figure 7d The force generated during this period is parallel to the wafer and is not compensated.

[0145] To compensate for the force and torque transmitted to the attachment portion Pf of the resonator, this invention proposes a novel gyroscope tester, which includes two vibration parts, each of which is similar to […]. Figure 7a The two vibrating sections are opposite each other and share a common foot Pd. Both vibrating sections are manufactured from the same wafer, therefore their material is continuous across foot Pd. Figure 8a ]-[ Figure 8d The gyroscope tester shown in the figure is effectively used to measure rotation about axis X or about axis Y. Two excitation vibration modes are possible as leading modes, each of which preserves the balance provided by the dual resonator structure: an out-of-phase mode in which the two beams P1 and P2 of one of the vibrating parts move out of phase relative to the beams P3 and P4 of the other vibrating part, moving apart and toward each other, as shown in the figure. Figure 8a As shown in the diagram; and in a phase-independent mode, in which two beams P1 and P2 of one of the vibrating parts move in phase with beams P3 and P4 of the other vibrating parts, moving apart and toward each other, as shown in the diagram. Figure 8c As shown in the figures. In both figures, each MV label indicates the momentum of the beam or guide rod superimposed upon it. Figure 8b [This shows the pattern used as a leading mode] Figure 8a Coriolis acceleration Γ of the vibration excitation mode C The compensation for inertial forces, and [ Figure 8d ] is for use as a leader mode. Figure 8c The vibration excitation mode is determined by the configuration of electrodes on the two vibrating sections. One of these two excitation modes is selected as the leader mode. For example, in the case of piezoelectric quartz crystals or any other piezoelectric crystals of the same symmetry class, the gyroscope tester may include two vibrating sections positioned from head to tail, each having two beams forming a 60° angle between them, such that these beams are parallel to the crystallographic axes Yc+ and Yc-. Figure 9a]-[ Figure 9c [This shows a set of strips of conductive material arranged on the surfaces of all segments of two vibrating sections. The two vibrating sections are designated by the letters A and B, respectively, and correspond to the [...] for vibrating section A. Figure 9b The cross-sectional view of ], and corresponding to the [ for vibrating part B] Figure 9c Cross-sectional view of ].

[0146] For a gyroscope with a sensitive axis parallel to the crystallization axis Xc, the pilot mode is the mode in which two resonators vibrate in opposite phase, such as [ Figure 8a As shown in the image. The teachings of U.S. Patent No. 2012 / 279303, filed by the applicant, may then be applied to limit capacitive coupling between the leader mode and the sensing mode. According to these teachings, the stripe e 3-A el 103-A el 4-A el 104-A el 9-A el 109-A el 10-A el 110-A el 3-B el 103-B el 4-B el 104-B el 9-B el 110-B el 110-B Used to excite the leader mode by electrically connecting them to an AC voltage V source, and el 2-A el 102-A el 5-A el 105-A el 8-A el 108-A el 11-A and el 111-A Used to detect the amplitude of the leader mode. Therefore, the strip el 1-A el 101-A el 6-A el 106-A el 7-A el 107-A el 12-A el 112-A el 1-B el 101-B el 6-B el 106-B el 7-B el 107-B el 12-B and el 112-B It can be used to detect movement caused by rotation about axis X, but by one side, the strip el 1-A el6-A el 7-A el 12-A el 1-B el 6-B el 7-B and el 12-B And on the other hand, the stripe el 101-A el 106-A el 107-A el 112-A el 101-B el 106-B el 107-B and el 112-B They are respectively connected to the input terminals of the differential amplifier, which serves as the current detector.

[0147] For a gyroscope tester whose sensitive axis is axis Xc perpendicular to the crystal and lies on axis Y in the common plane of axes Xc, Yc+, and Yc-, the leader mode is the mode in which the two resonators oscillate in phase, such as [ Figure 8c As shown in the image. 1-A el 101-A el 6-A el 106-A el 7-A el 107-A el 12-A el 112-A el 1-B el 101-B el 6-B el 106-B el 7-B el 107-B el 12-B and el 112-B This subsequently makes it possible to excite this leader mode by connecting them to an AC voltage V source, and the stripe el 2-A el 102-A el 5-A el 105-A el 8-A el 108-A el 11-A el 111-A el 2-B el 102-B el 5-B el 105-B el 8-B el 108-B el 11-B and el 111-B Used to detect the amplitude of the leader mode. In this case, the strip el 3-A el 103-A el 4-A el104-A el 9-A el 109-A el 10-A el 110-A el 3-B el 103-B el 4-B el 104-B el 9-B el 109-B el 10-B and el 110-B It can be used to detect movement caused by rotation about the Y-axis, but by one side, the strip el 3-A el 4-A el 9-A el 10-A el 103-B el 104-B el 10-B and el 110-B And on the other hand, the stripe el 103-A el 104-A el 109-A el 110-A el 3-B el 4-B el 9-B etel 10-B They are respectively connected to the input terminals of the differential amplifier, which serves as the current detector.

[0148] Another application of the resonator according to the invention is in the implementation of a force sensor. For example [ Figure 10a As shown in the diagram, the force sensor is based on two identical vibrating sections, which are again fabricated in the same wafer and oriented opposite each other but joined by their guide rods Pc. Each of the two vibrating sections is sized to be individually balanced. Beams P1 and P2 of one of the two vibrating sections and beams P3 and P4 of the other vibrating sections form a 60° angle between them. This association of the two vibrating sections makes it possible to obtain a dual resonator, whose two ends, formed by the corresponding feet of the individual vibrating sections, have little or no residual motion for the vibration modes of the two vibrating sections oscillating in opposite phases, as shown by […]. Figure 10b As shown in the figure. When this sensor is subjected to axial tensile force, the static deformation applied to the dual resonator modifies its flexural inertia. Figure 10c This shows the static deformation under axial tensile force T.

[0149] If this force sensor is made of quartz crystal, then two configurations are possible, the two configurations corresponding to an angle α equal to 60°, such as [ Figure 10a ]-[ Figure 10c As shown in the figure, or corresponding to an angle α equal to 180°, such as [ Figure 11a ]-[ Figure 11c As shown in the image. Therefore, [ Figure 11a The diagram shows a configuration with two vibrating parts, where beams P1 and P2 form one side and beams P3 and P4 form the other side at a 180° angle. Figure 11b This shows the vibration modes of interest for in-phase vibration of two vibrational components. Figure 11a The instantaneous deformation of the dual resonator structure. Figure 11c The diagram shows the static deformation of the same force sensor when subjected to an axial tensile force T. For the case where the angle α equals 180°, the change in the relative frequency F of the considered vibration mode induced by the axial tensile force T is proportional to the following (Equation 8):

[0150]

[0151] Using Equation 8, those skilled in the art can determine the size of the force sensor based on each application and the measurement sensitivity suitable for said application.

[0152] It should be understood that the invention can be reproduced by modifying minor aspects of the embodiments described in detail above while retaining at least some of the enumerated advantages. Specifically, the material of the wafer does not necessarily have to be a piezoelectric single-crystal material. For example, the wafer may be made of single-crystal silicon or polycrystalline silicon, or it may be piezoelectric ceramic, or a combination of metal and piezoelectric ceramic. The components used for vibration excitation and detection must then be adapted according to each material. For example, excitation can be achieved using electrostatic force, magnetic force, or by implementing a photothermal effect, and detection can be achieved by measuring the capacitance change of the capacitor formed between the moving and stationary parts of the resonator, or by using a piezoresistive effect, or by measuring with optical interferometry, etc. Finally, all values ​​cited have been provided for illustrative purposes only and may be changed according to the application considered.

Claims

1. A resonator comprising: - A portion of a wafer having two flat and parallel opposing surfaces, the wafer portion being designed to flexurally vibrate during the use of the resonator, and is referred to as the vibrating portion; as well as - A support portion (Pf), which is external to the vibrating portion and connected to the vibrating portion via an intermediate segment of the wafer called a foot (Pd), the foot being integral with the vibrating portion and forming a rigid connection between the support portion and the vibrating portion. The vibrating portion has a first symmetry plane, called the mid-plane (M), which is parallel to two surfaces of the wafer and equidistant from the two surfaces, and a second symmetry plane, called the orthogonal symmetry plane (P), which is perpendicular to the mid-plane and longitudinally passes through the connection formed by the foot between the support portion (Pf) and the vibrating portion. The intersection point between the midplane (M) and the plane of symmetry (P) orthogonal to the wafer constitutes the central axis of the vibrating portion. The vibrating portion includes two extensions (P1, P2) that each flexure and vibrate symmetrically from the foot (Pd) on each side of the plane of symmetry (P) orthogonal to the wafer. The resonator is characterized in that each extension (P1, P2) has a longitudinal slot (FL1, FL2) extending from the plane of symmetry (P) orthogonal to the wafer toward the distal end of the extension but not reaching the distal end, perpendicular to the mid-plane (M) through the vibrating portion, such that each extension is bent into shape. The corresponding slots (FL1, FL2) of the two extensions (P1, P2) are symmetrical with respect to the plane of symmetry (P) orthogonal to the wafer, and converge at the plane of symmetry, such that the vibrating portion includes two main segments (L1, FL2) that each connect the foot (Pd) to the distal end of one of the extensions. 1ext L 2ext ), and two auxiliary segments (L 1int L 2int The two auxiliary segments are interconnected at their respective proximal ends in a plane orthogonal to the symmetry of the wafer, and each extends to the distal end of one of the extensions to connect to one of the main segments at the distal end. This allows for the vibrational modes of a portion that comprises only movement parallel to the midplane (M) and is symmetrical with respect to the plane of symmetry (P) orthogonal to the wafer, resulting in two main segments (L... 1ext L 2ext The ) has an instantaneous velocity component parallel to the central axis, and the instantaneous velocity component at each moment during the vibration is in conjunction with the auxiliary segment (L) 1int L 2int The instantaneous velocity component is parallel to the central axis and in the opposite direction.

2. The resonator according to claim 1, characterized in that, The vibrating portion has a mass distribution such that the vibration mode, which includes only movement parallel to the midplane (M) and is symmetrical with respect to the plane of symmetry (P) orthogonal to the wafer, does not cause movement of the foot (Pd) parallel to the central axis.

3. The resonator according to claim 1 or 2, characterized in that, The wafer is made of a single crystal, and is triangular and piezoelectric, wherein: The central axis of the vibrating part is parallel to the axis Xc of the material, and The two main segments of the vibrating part (L) 1ext L 2ext ) and two auxiliary segments (L 1int L 2int ) Parallel to the axis Yc of the material.

4. The resonator according to claim 3, characterized in that, The two extensions (P1, P2) of the vibrating part form an angle (α) between them equal to 60° or 180°.

5. The resonator according to claim 3, further comprising: - An excitation member adapted to generate flexural deformation of the vibrating portion, the excitation member comprising a first electrode and a second electrode electrically insulated from each other, the first electrode being on each face of the wafer and for each major segment (L 1ext L 2ext ) or auxiliary fragments (L 1int L 2int The first electrode includes a conductive material strip arranged longitudinally and centrally on the segment within the width of the segment, and the second electrode is also on each face of the wafer and, for each main segment or auxiliary segment, includes two strips arranged on the segment on two opposite sides of the strip of the first electrode. as well as - A detection component adapted to measure the amplitude of the flexural deformation of the vibrating portion generated by the excitation component during use of the resonator, the detection component including circuitry for detecting currents appearing in the first and second electrodes.

6. The resonator according to claim 1 or 2, characterized in that, Each extension (P1, P2) includes, at its distal end and parallel to the midplane (M), the main segment (L) relative to the extension. 1ext L 2ext ) and auxiliary segments (L 1int L 2int The outer longitudinal edge of the ) is widened.

7. The resonator according to claim 1 or 2, further comprising an additional segment of the wafer, referred to as a guide rod (Pc), the additional segment being parallel to the central axis and extending from the auxiliary segment (L) in a direction away from the foot (Pd). 1int L 2int Interconnection near-end extension.

8. The resonator of claim 7, comprising two vibrating portions formed in the same wafer and having respective guide rods (Pd), the two vibrating portions being interconnected by the guide rods and oriented relative to each other such that the respective central axes of the two vibrating portions are superimposed.

9. The resonator according to claim 1 or 2, comprising two vibrating portions formed in the same wafer, the two vibrating portions being interconnected by corresponding pins (Pd) of the two vibrating portions and oriented relative to each other such that the corresponding central axes of the two vibrating portions are superimposed.

10. A force sensor comprising the resonator according to claim 8, and adapted to measure a tensile force applied between corresponding feet (Pd) of two vibrating portions and parallel to the central axis of the two vibrating portions.

11. A gyroscope tester comprising at least one resonator according to any one of claims 1 to 9.

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