Tuning fork resonator

Abstract

To provide a tuning fork resonator. [Solution] One aspect of the present invention relates to a tuning fork resonator having a design that reduces the dimensions of the resonator while maintaining a high quality factor.

Description

Technical Field

[0001] The present invention relates to a tuning fork resonator having a shape that enables reduction of the size of the resonator while maintaining a high quality factor.

Background Art

[0002] A tuning fork resonator generally includes at least two tines (also called vibrating arms or beams) and at least one stem (or base) that couples the tines. The stem and the tines are generally in the same plane. The tuning fork resonator can be made of, for example, silicon or quartz. The tines are generally arranged symmetrically, parallel to each other. The tines generally include electrodes disclosed in, for example, European Patent No. 3468037, or piezoelectric strips disclosed in, for example, European Patent No. 2278709. The electrodes or the piezoelectric strips can be coupled to an alternating voltage to vibrate the tines of the tuning fork. Conventional tuning forks are included in one vibration plane and have tines that vibrate in this vibration plane.

[0003] One characteristic of a resonator is its quality factor Q (<<Q value>> or < <q>(It can also be stated that) the quality factor Q is generally defined as the ratio of the energy stored in the resonator to the energy lost during the oscillation cycle. The higher the Q value, the better the resonant characteristics of the resonator. A high Q value facilitates the achievement of low resistance in the resonator.

[0004] One objective for resonator manufacturers is to reduce the size of the resonator while maintaining high quality factors and resonator frequency values. The main problem in miniaturizing low-frequency bending-mode resonators is the decrease in the quality factor Q, which leads to an increase in resistance due to thermoelastic damping. Thermoelastic damping is highest when the thermal relaxation time τ (tau) of the resonator beam in the oscillation direction is equal to the reciprocal of the oscillation angular frequency ω = 2πf, i.e., ω·τ = 1.

[0005] Due to the thermal processing characteristics of quartz, it has been found that ω·τ > 1 in a typical tuning fork resonator operating at 32768 Hz.

[0006] Miniaturizing a given shape decreases τ (tau) and therefore ω·τ. As a result, Q continues to decrease with size until ω·τ = 1. For even smaller structures, Q increases again.

[0007] As a countermeasure, resonator designs aim to maximize τ (tau) by, for example, etching grooves on both sides of the resonator beam, making the beam's cross-section H-shaped, and leaving a thin film between the sidewalls. An example of a miniature piezoelectric resonator having these features is described in European Patent No. 3468037. Some of these solutions involve etching grooves within the vibrating arm to reduce energy consumption by providing a more homogeneous electric field. On the one hand, these grooves provide thermal insulation between the compression and extension sides, increasing Q and decreasing resistance. On the other hand, due to the thin, high boundary walls, the electric field is more homogeneous and stronger, increasing the series capacitance and consequently decreasing resistance. More specifically, each resonator beam comprises a first groove on the first side and a second groove on the opposite side, with the depths of the first and second grooves being different. Miniaturization of such types of resonators may be limited by the complexity of the design and the possibility of machining.

[0008] Apart from the primary purpose of the grooves, namely the increased piezoelectric coupling due to narrow, high sidewalls, the thin film between the sidewalls slows down thermal kinetics within the beam and increases τ (tau). However, this technique only partially compensates for the decrease in Q-factor associated with size.

[0009] The remarkable thermal processing properties of quartz make it a desirable material for tuning fork resonators.

[0010] To achieve a quartz regime ω·τ<<1 where Q increases again to a moderate level, it is necessary to miniaturize tuning fork resonators, preferably quartz tuning fork resonators, and to provide new designs for such resonators. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] European Patent No. 3468037 [Patent Document 2] European Patent No. 2278709 [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] The present invention aims to provide a tuning fork resonator with reduced size and a relatively high quality factor Q. [Means for solving the problem]

[0013] In a first embodiment, the present invention relates to a tuning fork resonator, wherein the tuning fork resonator is - A handle having a first height portion extending from the first base to the second base, - A first resonator beam and a second resonator beam are spaced apart from each other, connected to a handle, and positioned in a plane substantially perpendicular to the height of the handle. The device is characterized in that the first resonator beam and the second resonator beam have a thickness portion that is included between 0.05% and 20% of the first height portion of the handle.

[0014] Preferably, the tuning fork resonator is configured such that the resonator beam can oscillate in an out-of-planar mode.

[0015] Preferably, the first resonator beam comprises a first piezoelectric assembly provided on the surface of the first resonator beam, and the second resonator beam comprises a second piezoelectric assembly provided on the surface of the second resonator beam, and each of the first piezoelectric assembly and the second piezoelectric assembly is - A first electrode layer extending across the surface of the resonator beam, - A piezoelectric layer extending to the first electrode, - A second electrode layer extending across the piezoelectric layer and Equipped with, -The first electrode layer of the first piezoelectric assembly and the second electrode layer of the second piezoelectric assembly are electrically coupled to a first mounting pad configured to be coupled to the first pole of an AC power supply. - The second electrode layer of the first piezoelectric assembly and the first electrode layer of the second piezoelectric assembly are electrically coupled to a second mounting pad configured to be coupled to the opposite pole of an AC power supply.

[0016] Preferably, the shank and the resonator strip are made of quartz, preferably Z-cut quartz. Other materials may also be selected, such as langasite, GaPO4, or partially oxidized silicon, or any compound having a crystal orientation in which at least the first-order frequency-temperature coefficient of the resonator is zero or substantially zero, for example, less than 1 ppm / K in absolute value. The resonance frequency f of the tuning fork resonator depending on the temperature T is f(T)=β·(T - T Ref ) 2 +α·(T - T Ref )+f(T Ref ), which can be approximated, where T Ref is the reference temperature (typically 25 °C), and α and β are the first-order temperature coefficient and the second-order temperature coefficient, respectively. In the case of quartz where T Ref is about 25 °C, there is a cut angle close to the z-cut, at which the α of the tuning fork resonator is substantially zero, for example, less than 1 ppm / K in absolute value. Therefore, f(T) is dominated by the second-order term that results in a parabolic frequency-temperature characteristic.

[0017] Preferably, the tuning fork resonator forms one body in which the first resonator strip and the second resonator strip are integral with the shank.

[0018] Preferably, the tuning fork resonator further includes an intermediate thin plate portion extending between the shank and the first resonator strip and the second resonator strip. The thin plate portion is in the same plane as the first resonator strip and the second resonator strip and preferably has the same thickness as the first resonator strip and the second resonator strip. The thin plate portion extends from one of the first base or the second base of the shank or from an intermediate position between the first base and the second base of the shank.

[0019] Preferably, the thickness portions of the first resonator strip and the second resonator strip are included between 0.05 μm and 25 μm, preferably less than 10 μm.

[0020] Preferably, the height portion of the shank is included between 10 μm and 200 μm, preferably between 20 μm and 150 μm, more preferably between 80 and 125 μm.

[0021] Preferably, each of the first resonator bar 15a and the second resonator bar 15b has a first end fixed to the handle 11 or the thin plate portion 27 and a free end (non-attached end), and the first resonator bar and the second resonator bar - a main portion extending from the free end (non-attached end) to a region close to the attachment end, and - an overhanging portion that widens from the main portion toward the attachment end and further includes.

[0022] In some embodiments, the main portion has a constant width.

[0023] In some embodiments, the free ends of the main portions of the first resonator bar and the second resonator bar include a further mass body or an enlarged portion that provides a further mass.

[0024] Preferably, the width portion of the handle is included between 50 μm and 200 μm, preferably between 80 and 125 μm.

[0025] Preferably, the width portion of each main portion of the first resonator bar and the second resonator bar is included between 10% and 45% of the width portion of the handle.

[0026] Preferably, the tuning fork resonator has a length portion shorter than 500 μm, preferably shorter than 400 μm.

[0027] Preferably, the handle has a thickness portion measured in the direction of the resonator bar, and each of the first resonator bar and the second resonator bar has a length portion greater than at least half of the thickness portion of the handle.

[0028] Preferably, the handle includes a tapered portion that extends from a lateral side of the handle and / or one of the first base or the second base to a joint or intermediate surface between the handle and the first resonator bar and the second resonator bar, or extends to a joint or intermediate surface between the handle and a thin plate portion connected to the resonator bar.

[0029] Preferably, the quality factor of the tuning fork resonator at 32768 Hz in a vacuum is 5000 or more, preferably 7500 or more, more preferably 10000 or more, and preferably 15000 or more.

[0030] The object, advantages, and features of the present invention will become clear from the following description, which is given with reference to the drawings as merely a non-limiting example. [Brief explanation of the drawing]

[0031] [Figure 1] This is a top view of a tuning fork resonator according to a first embodiment of the present invention. [Figure 2] This is a side view of a tuning fork resonator according to one embodiment of the present invention. [Figure 3] This is a schematic diagram of one embodiment of a tuning fork resonator comprising two piezoelectric strip assemblies and two mounting pads. [Figure 4a] This is a top view of a tuning fork resonator according to a second embodiment of the present invention. [Figure 4b] This is a top view of a tuning fork resonator according to a third embodiment of the present invention. [Figure 5a] This is a top view of a tuning fork resonator according to a fourth embodiment of the present invention. [Figure 5b] This is a side view of a tuning fork resonator according to a fourth embodiment of the present invention. [Modes for carrying out the invention]

[0032] Unless otherwise stated, please note that the drawings are not to a fixed scale, and modifications may be made to the design presented in the drawings within the scope of the spirit of the present invention.

[0033] The present invention will be described in more detail below, with reference to Figures 1 and 2, which show a top view and a side view, respectively, of one embodiment of the tuning fork resonator according to the present invention.

[0034] The tuning fork resonator 10 according to the present invention is - A handle 11 having a first height portion 12 extending from a first base portion 13 to a second base portion 14, - The first resonator beam 15a and the second resonator beam 15b are spaced apart from each other, connected to the handle 11, and extend in a plane substantially perpendicular to the height portion 12 of the handle 11. The first resonator beam 15a and the second resonator beam are characterized in that they have thickness portions 17a and 17b that are included in the range of 0.05% to 20%, preferably 0.1% to 10%, more preferably 0.1% to 5%, and even more preferably 0.5% to 5% of the first height portion 12 of the handle 11. In the context of this specification, the term "bonding" means - A first element that is directly connected to (physically joined to or attached to) a second element, - The first element is indirectly connected to (physically joined to or attached to) the second element through at least one further element. It refers to.

[0035] Preferably, the intermediate thin section 27 extends between the handle 11 and the first resonator beam 15a and the second resonator beam 15b. Preferably, the intermediate thin section 27 has the same thickness as the first resonator beam 15a and the second resonator beam 15b and is coplanar with the first resonator beam 15a and the second resonator beam 15b. The intermediate thin section 27 may also be coplanar with either the first base 13 or the second base 14 of the handle 11. As shown in Figure 2, the intermediate thin section 27 is coplanar with the second base 14. In an alternative embodiment, as shown in Figure 5b, the intermediate thin section 27 may be positioned at an intermediate location between the first base 13 and the second base 14 of the handle 11. In either case, the intermediate thin section 27 is substantially perpendicular to the height section 12 of the handle 11. The intermediate thin section 27 is advantageous with respect to temperature transition T0 and isolation of the resonator beams 15a and 15b from the handle 11. The first resonator beam 15a and the second resonator beam 15b are attached to the intermediate thin section 27 and have a first end, also referred to as the <<attachment end>>, and a second end, which is a free end, also referred to as the <<unattachment end>>.

[0036] The term "substantially orthogonal" refers to an axis, plane, or surface that is orthogonal to another axis, plane, or surface with a tolerance of 5° or less, preferably 1° or less. In the context of the present invention, the expression "substantially orthogonal to the height of the handle" refers to a position where the first and second resonator beams are orthogonal to the height of the handle with a tolerance of 5° or less, preferably 1° or less, in the absence of an electric field generated across the resonator beams or any mechanical shock that causes the first and second resonator beams to vibrate.

[0037] The first base 13 and the second base 14 are opposite to each other, preferably substantially flat, and preferably substantially parallel to each other. The term “substantially flat” includes a surface that is generally flat or level, but optionally includes minor irregularities or interruptions such as holes, but which do not affect the overall flat or level appearance. The term “substantially parallel” refers to two substantially flat surfaces or axes that are parallel to each other, thereby forming an angle of 0° with each other with a tolerance of less than 5°, preferably less than 1°.

[0038] In this disclosure, the term “resonator beams” may refer to arms, tines, or cantilever elements, which have a length portion that is at least five times greater than the width and / or thickness portion and is suitable for vibration.

[0039] From the top view shown in Figure 1, the first resonator beam 15a and the second resonator beam 15b have, for example, a main portion MP with a constant width. The shape of the main portion MP is not limited to a rectangle, and other suitable shapes can be designed, such as a rectangular shape with rounded or chamfered free ends, or an adjustable shape with a width that changes along the length direction, as shown in Figure 4a.

[0040] In some embodiments, the free ends of the main portions of the first resonator beam 15a and the second resonator beam 15b are provided with additional mass bodies or extensions that introduce additional mass, as shown in Figure 4b. These additional mass bodies may allow for a reduction in the length of the resonator beam.

[0041] The tuning fork resonator is configured such that the resonator beam can oscillate in out-of-planar modes. The high ratio of the thickness portion 17a / 17b of the resonator beam to the height portion 12 of the handle results in a handle 11 with higher inertia compared to the resonator beams 15a / 15b. Therefore, the handle takes over residual motion more easily than if the handle 11 and the resonator beams 15a and 15b had the same thickness. When the first resonator beam 15a and the second resonator beam 15b undergo out-of-planar oscillation modes, it has been found that the residual torsional motion of the resonator beams 15a and 15b in out-of-planar modes is negligible due to the large mass of the handle 11, which is thicker than the resonator beams. In the context of this disclosure, the term “out-of-plane oscillation mode” refers to a vibration or oscillation mode of two resonator beams 15a and 15b that, when at rest, are contained within (or coplanar) one plane and, under the action of an electric field applied through the resonator beams or a mechanical shock substantially perpendicular to the plane, vibrate out of the plane and in opposite directions (out of phase). While it is possible to use common in-plane modes of the tuning fork resonator, out-of-plane modes are selected for ease of fabrication. The shapes of the tuning fork resonators described above are preferably combined with one of the embodiments presented below to reduce the size of the tuning fork resonator while maintaining a relatively high quality factor Q at low frequencies.

[0042] The casing and the first and second resonator beams are made from quartz, preferably Z-cut quartz. Other materials may also be selected, such as langasite, GaPO4, or partial silicon oxide, or any compound having a crystal orientation in which the primary frequency-temperature coefficient of at least the resonator is zero or nearly zero, for example, less than 1 ppm / K in absolute value. As will be described below, the resonator beams 15a and 15b according to the present invention are configured to oscillate in out-of-planar modes. Z-cut quartz is well known in the art and is advantageously chosen for its ease of manufacture. Because the piezoelectric coupling of out-of-planar modes in quartz is weak, piezoelectric assemblies 28a and 29a are used for operation. This is advantageous because it results in the separation of mechanical and electrical properties, allowing both domains to be optimized independently.

[0043] Advantageously, the tuning fork resonator is made from a single component in which the first resonator beam 15a and the second resonator beam 15b are integrated with the handle 11.

[0044] In one embodiment shown in Figure 2, the first resonator beam 15a and the second resonator beam 15b each have surfaces 16a and 16b that are in the same plane as the second base 14 of the handle 11.

[0045] In an alternative embodiment, the first resonator beam 15a and the second resonator beam 15b may be positioned intermediate from the second base 14 and the first base 13 of the handle, as shown in Figure 5b.

[0046] Advantageously, the thicknesses 17a and 17b of the first and second resonator beams are between 0.05 μm and 25 μm, preferably less than 10 μm, and more preferably less than 5 μm. More advantageously, the first resonator beam 15a and the second resonator beam 15b have the same thickness.

[0047] Preferably, the height portion 12 of the handle 11 is between 10 μm and 200 μm, preferably between 20 μm and 150 μm, and preferably between 80 and 125 μm.

[0048] Preferably, each of the first resonator beam 15a and the second resonator beam 15b is, - The main part MP extends from the free end (non-mounted end) to the region adjacent to the mounting end, -The overhang portion FP extends from the main portion MP toward the mounting end. It is equipped with.

[0049] The lengths of the main section MP and the protruding section FP can be varied to suit each other's advantages, from zero to the total length of the resonator beam.

[0050] The first resonator beam 15a and the second resonator beam 15b are separated from each other by a gap 19, which is constant between the main portions MP of the resonator beams 15a and 15b and can decrease between the protruding portions FP of the resonator beams 15a and 15b. The protruding portions FP of the resonator beams 15a and 15b improve impact resistance.

[0051] The width portion 20 of the handle 11 is between 50 μm and 200 μm, preferably between 80 μm and 125 μm, and preferably wider than the sum of the width portions of the first resonator beam 15a and the second resonator beam 15b at the joint with the handle 11.

[0052] Preferably, the widths 18a and 18b of the main portions MP of the first resonator beam 15a and the second resonator beam 15b, respectively, are between 10% and 45% of the width 20 of the handle 11. Advantageously, the widths 18a and 18b of the main portions MP of the first resonator beam 15a and the second resonator beam 15b are the same.

[0053] Preferably, the tuning fork resonator has a length portion 21 shorter than 500 μm, preferably shorter than 400 μm.

[0054] The handle 11 has a thickness portion 30 measured in the direction of the resonator beams 15a and 15b. Each of the first resonator beam 15a and the second resonator beam 15b has length portions 23a and 23b that are at least half the thickness portion 30 of the handle. Advantageously, the first resonator beam 15a and the second resonator beam 15b have the same length portions 23a and 23b.

[0055] Preferably, the handle 11 has a tapered portion 24, which extends laterally from the side portion 25 of the handle and / or the first base portion 13 or second base portion 14 of the handle 11 to the joint or intermediate surface 26 between the handle 11 and the first resonator beam 15a and the second resonator beam 15b, preferably to the joint between the handle 11 and the intermediate thin portion 27 between the handle and the resonator beams 15a and 15b. A portion of the length portion 22 comprises a thickness portion 30 of the handle, a width portion of the tapered portion 24, and a width portion of the intermediate thin portion 27, as shown in one embodiment of Figure 1 or Figures 5a and 5b. A portion of the length portion 22 may be included in between 5% and 60%, preferably between 20% and 45%, of the length portion 21 of the tuning fork resonator 10. As shown in one embodiment of Figure 2, one tapered portion 24 extends from the side portion 25 of the handle 11, which is located midway between the first base portion 13 and the second base portion 14, to the joint portion 26 between the intermediate flake portion 27 and the handle 11. As shown in another embodiment of Figure 5b, the first tapered portion 24a extends from the second base portion 14 of the handle 11 to the intermediate flake portion 27, and the second tapered portion 24b extends from the location between the first base portion 13 and the second base portion 14 of the handle to the joint portion 26 between the handle 11 and the intermediate flake portion 27.

[0056] According to the present invention, as previously described, the tuning fork is configured such that the resonator beams 15a and 15b are capable of oscillating in out-of-planar modes. It should be noted that in the case of a common Z-cut quartz crystal used in a tuning fork resonator, the piezoelectric coupling is very weak in out-of-planar modes. This is even more true with respect to small size. Therefore, the series capacitance resulting from direct excitation by electrodes on the quartz is quite small and suppresses operation in the oscillator circuit due to a small figure of merit. To obtain sufficient coupling and low resistance, small, thin strips of piezoelectric material such as AlN (aluminum nitride), PZT (lead zirconate titanate), or KNN (potassium sodium niobate) are placed on the resonator plate and electrically coupled to the mounting pads for excitation. The advantage of this method is that the piezoelectric coupling and thermomechanical properties, i.e., thermoelastic damping and frequency-temperature behavior, can be optimized independently.

[0057] Preferably, each of the first resonator beam 15a and the second resonator beam 15b further comprises a first piezoelectric assembly 28a and a second piezoelectric assembly 28b provided on their respective surfaces 16a and 16b. Each of the first piezoelectric assembly 28a and the second piezoelectric assembly 28b is - First electrode layers 41a, 41b are placed on the surfaces 16a, 16b of the resonator beams 15a, 15b, - Piezoelectric layers 42a and 42b are placed over the first electrodes 41a and 41b, - Second electrode layers 43a, 43b are placed across piezoelectric layers 42a, 42b and It is equipped with.

[0058] The handle 11 further comprises a first mounting pad 29a and a second mounting pad 29b, preferably positioned on the first base 13 of the handle 11. As illustrated in Figure 3, the first mounting pad 29a is configured to be electrically coupled (or connected) to a first pole (not shown) of an electrical excitation source (or power source), a first electrode 41a of a first piezoelectric assembly 28a, and a second electrode 43b of a second piezoelectric strip assembly 28b. The second mounting pad 29b is configured to be electrically connected to the opposite pole (not shown) of an electrical excitation source, a second electrode 43a of a first piezoelectric assembly 28a, and a first electrode 41b of a second piezoelectric strip assembly 28b. Advantageously, the first piezoelectric assembly 28a and the second piezoelectric assembly 28b are at least partially located on the overhanging portions FP of the resonator beams 15a and 15b. The first piezoelectric assembly 28a and the second piezoelectric assembly 28b preferably have a strip shape.

[0059] During operation, electrical excitation generates alternating electric fields on the one hand between the first electrode 41a and the second electrode 43a of the first piezoelectric assembly 28a, and on the other hand between the first electrode 41b and the second electrode 43b of the second piezoelectric assembly 28b. The alternating electric fields cause the piezoelectric layers 42a and 42b of the first piezoelectric assembly 28a and the second piezoelectric assembly 28b to contract and expand cyclically in the longitudinal direction, with a phase displacement of half the period between the piezoelectric layers 42a and 42b.

[0060] While the piezoelectric layer 42a of the first piezoelectric strip assembly 28a stretches in the longitudinal direction, the piezoelectric layer 42b of the second piezoelectric strip assembly 28b contracts, forcing the two resonator beams 15a and 15b to bend downward or upward, away from the plane formed by the surfaces 16a and 16b of the resonator beams 15a and 15b when they are at rest.

[0061] One possible method for providing piezoelectric assemblies 28a, 28b includes the step of forming a first metal film over the surfaces 16a, 16b of the resonator beams 15a, 15b. The metal film may be made from, for example, any sufficient metal or alloy, chromium / gold or platinum. The film may be formed using vacuum deposition, sputtering, or any other sufficient method known to those skilled in the art. Next, a piezoelectric thin film is grown over the (entire) surface of the metal film. The piezoelectric thin film is preferably AlN or KNN or a derivative of the said material. However, any other suitable piezoelectric material may be used for the thin film. The thickness of the piezoelectric thin film is preferably in the range of 0.05 to 3 μm, most preferably about 0.2 μm. Next, a second metal film, possibly platinum, chromium, or any other sufficient layer matching the crystal lattice of the respective piezoelectric layer, is placed over the entire surface of each piezoelectric thin film. Next, preferably, a third metal film made of metal (Au) is formed over the second metal film.

[0062] The entire surface of the outermost metal film can be covered with a photoresist, which is patterned to form an etching mask on the substrate. The structure formed by the substrate and the various films formed across the main surface is then etched layer by layer by wet or dry etching. The remaining photoresist is then removed from the resonator (for example, by immersing the resonator in a solvent), exposing the metal film.

[0063] One possible method for implementing the connection between the electrode layer and the mounting pad is to place conductive orbitals of a metal film using a deposition mask or photolithography technique. Advantageously, in both piezoelectric assemblies, the position of the first electrode layer is longitudinally offset from the position of the second electrode layer to prevent the connection of their respective conductive orbitals from interfering with each other.

[0064] One non-limiting example of one embodiment of a tuning fork resonator is made from a Z-cut quartz crystal and comprises a shank 11 and a first resonator beam 15a and a second resonator beam 15b, the first and second resonator beams 15a and 15b being integral with the shank and extending from the shank in a longitudinal direction perpendicular to the height portion 12 of the shank 11. The shank 11 has a height portion 12 of 100 μm and a width portion 20 of 100 μm. The first and second resonator beams 15a and 15b have thickness portions 17a and 17b of 1 μm, a width portion of the main portion of 20 μm, and a length portion of 150 μm. The first and second resonator beams 15a and 15b extend parallel and symmetrically to each other in the same longitudinal direction, and their cantilever portions are separated from each other by a gap 19 between the main portions MP by 15 μm. The total length of the tuning fork, including the handle, is 370 μm. The first resonator beam 15a comprises a first piezoelectric assembly 28a placed on the surface 16a, and the second resonator beam 15b comprises a second piezoelectric assembly 28b placed on the surface 16b. Each of the first piezoelectric assembly 28a and the second piezoelectric assembly 28b comprises a first electrode layer 41 placed on the surfaces 16a and 16b of the resonator beams 15a and 15b, a piezoelectric layer extending over the first electrode layer, and a second electrode layer extending over the piezoelectric layer. The handle 11 further comprises a first mounting pad 29a and a second mounting pad 29b positioned on the first base 13 of the handle 11. The first mounting pad 29a is electrically connected to the first electrode 41a of the first piezoelectric assembly 28a and the second electrode 43b of the second piezoelectric assembly 28b. The second assembly pad 29a is connected to the second electrode 43b of the first piezoelectric assembly 28a and the first electrode 41b of the second piezoelectric assembly 28b. The tuning fork resonator is configured to vibrate in an out-of-planar mode.

[0065] As shown in Table 1 below, the quality factors of the crystal tuning fork resonators described above in the examples of this specification were compared with the quality factors of various conventional crystal tuning fork resonators.

[0066] Table 1: JPEG2026053282000002.jpg127165

[0067] According to the present invention, it is possible to reduce the overall dimensions of the crystal tuning fork resonator while maintaining an acceptable quality factor of over 10,000, preferably 15,000 or more, at 32,768 MHz. [Explanation of Symbols]

[0068] 10 Tuning Fork Resonator 11 patterns 12. First height section of the handle 13. First base of the handle 14. Second base of the handle 15a First resonator beam 15b Second resonator beam Surface of 16a and 15a Surface of 16b and 15b 17a 15a thickness section 17b 15b thickness section Width section of 18a and 15a Width section of 18b and 15b 19 Gap between the main parts of 15a and 15b 20 width of the pattern 21 Length section of the tuning fork resonator 22 Width of the pattern Length portion of 23a 15a Length section of 23b and 15b 24 Tapered part 24a First tapered portion 24b Second tapered section 25 Side of the pattern 26 Joint 27 Intermediate thin section 28a First piezoelectric strip assembly on 15a 28b Second piezoelectric strip assembly on 15b 29a First assembly pad 29b Second assembly pad 30 Thickness of the handle 41a 28a First electrode layer Piezoelectric layer 42a 28a 43a 28a Second electrode layer 41b 28b First electrode layer 42b 28b piezoelectric layer 43b 28b Second electrode layer 44a Enlarged portion or mass of 16a 44b Enlarged portion or mass of 16b< / q>

Claims

1. A tuning fork resonator (10), wherein the tuning fork resonator (10) is - A handle (11) having a first height portion (12) extending from a first base portion (13) to a second base portion (14), - A first resonator beam (15a) and a second resonator beam (15b) are spaced apart from each other, coupled to the handle (11), and positioned in a plane substantially perpendicular to the height portion (12) of the handle (11). A tuning fork resonator (10) comprising the first resonator beam (15a) and the second resonator beam (15b) having a thickness portion (17a, 17b) that is included in the range of 0.05% to 20% of the first height portion (12) of the handle (11), wherein the tuning fork resonator (10) is characterized in that

2. The tuning fork resonator according to claim 1, wherein the resonator beams (15a, 15b) are configured to oscillate in an out-of-planar mode.

3. The first resonator beam (15a) comprises a first piezoelectric assembly (28a) provided on the surface (16a) of the first resonator beam (15a), and the second resonator beam (15b) comprises a second piezoelectric assembly (28b) provided on the surface (16b) of the second resonator beam (15b), and the first piezoelectric assembly (28a) and the second piezoelectric assembly (28b) are, - The first electrode layers (41a, 41b) extend over the surfaces (16a, 16b) of the resonator beams (15a, 15b), - A piezoelectric layer (42a, 42b) extending over the first electrode layer (41a, 41b), - A second electrode layer (43a, 43b) extending over the piezoelectric layer (42a, 42b) and Equipped with, - The first electrode layer (41a) of the first piezoelectric assembly (28a) and the second electrode layer (43b) of the second piezoelectric assembly are electrically coupled to a first mounting pad (29a) configured to be coupled to the first pole of a power supply. - The tuning fork resonator according to claim 1, wherein the second electrode layer (43a) of the first piezoelectric assembly (28a) and the first electrode layer (41b) of the second piezoelectric assembly (28b) are electrically coupled to a second mounting pad (29b) configured to be coupled to the opposite pole of the power supply.

4. The tuning fork resonator according to claim 1, wherein the handle (11) and the resonator beams (15a, 15b) are made of quartz, preferably Z-cut quartz, or langasite, GaPO4, or partial silicon dioxide.

5. The tuning fork resonator according to claim 1 or 2, wherein the first resonator beam (15a) and the second resonator beam (15b) form a main body that is integrated with the handle (11).

6. The tuning fork resonator according to claim 1, further comprising an intermediate thin section (27) extending between the handle (11) and the first resonator beam (15a) and the second resonator beam (15b), wherein the intermediate thin section (27) is in the same plane as the first resonator beam (15a) and the second resonator beam (15b) and preferably has the same thickness as the resonator beams.

7. The tuning fork resonator according to claim 1, wherein the thickness portions (17a, 17b) of the first resonator beam (15a) and the second resonator beam (15b) are between 0.05 μm and 25 μm, preferably less than 10 μm.

8. The tuning fork resonator according to claim 1, wherein the height portion (12) of the handle (11) is between 10 μm and 200 μm, preferably between 20 μm and 150 μm, and more preferably between 80 μm and 125 μm.

9. Each of the first resonator beam 15a and the second resonator beam 15b has a first end fixed to the handle (11) or the thin section (27) between the handle and the resonator beams (15a, 15b), and a free end (non-attached end), and the first resonator beam and the second resonator beam are, - The main portion MP extending from the free end (non-mounted end) to the region adjacent to the mounting end, - The overhang portion FP widens from the main portion MP toward the mounting end. The tuning fork resonator according to claim 1, further comprising the following:

10. The tuning fork resonator according to claim 1, wherein the width portion (20) of the handle (11) is between 50 μm and 200 μm, preferably between 80 μm and 125 μm.

11. The tuning fork resonator according to claim 9, wherein the width portions (18a, 18b) of the main portions (MP) of the first resonator beam (15a) and the second resonator beam (15b) are between 20% and 45% of the width portion (20) of the handle (11).

12. The tuning fork resonator according to claim 1, having a length portion (21) shorter than 500 μm, preferably shorter than 400 μm.

13. The tuning fork resonator according to claim 1, wherein the handle (11) has a thickness portion (30) measured in the direction of the resonator beams (15a, 15b), and each of the first resonator beam (15a) and the second resonator beam (15b) has a length portion (23a, 23b) that is at least half the thickness portion (30) of the handle (11).

14. The tuning fork resonator according to claim 1, wherein the handle (11) has a tapered portion (24), and the tapered portion (24) extends from the lateral portion (25) and / or one of the first base portion (13) or the second base portion (14) of the handle (11) to the joint or intermediate surface (26) between the handle (11) and the first resonator beam (15a) and the second resonator beam (15b), or extends to the joint (26) or surface between the handle and the thin piece portion (27) connected to the resonator beam.

15. The tuning fork resonator according to claim 1, having a quality factor of 5000 or more, preferably 7500 or more, more preferably 10000 or more, and even more preferably 15000 or more at 32768 Hz in a vacuum.

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