Vibration element

Abstract

To achieve a vibration element that prevents causing a reduction in vibration strength to obtain a high Q value.SOLUTION: A vibration element 100 uses a piezoelectric body formed of a sphalerite-type single crystal, and comprises a vibration part 1 that has a ring shape, and has a plurality of first vibration parts 161 and 162 and a plurality of second vibration parts 163 and 164 arranged alternately in at least part thereof. The vibration part 1 has: first electrodes 111 and 112 provided in the plurality of first vibration parts 161 and 162, respectively; second electrodes 113 and 114 provided in the plurality of second vibration parts 163 and 164, respectively; a first connection part 11b electrically connecting the first electrodes to each other; and a second connection part 11c electrically connecting the second electrodes to each other. The plurality of first electrodes 111 and 112 and the plurality of second electrodes 113 and 114 are arranged alternately on a surface perpendicular to the [001] axis of the single crystal.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a vibration element. [Background technology]

[0002] Conventionally, various vibration elements have been known that vibrate a vibration part using a plurality of vibrator units. For example, Patent Document 1 discloses a Lame vibration quartz crystal vibrator in which a plurality of small vibration parts are arranged two-dimensionally. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-111434 Summary of the Invention [Problem to be solved by the invention]

[0004] The Lame vibration quartz crystal unit of Patent Document 1 vibrates with equal intensity in two directions: the row direction, which is one of the two-dimensional array directions, and the column direction, which is perpendicular to the row direction. The resonant frequencies corresponding to these two directions depend on the width of the vibrating section. Therefore, to achieve coordinated vibration in these two directions, the row and column dimensions of the vibrating section must be matched. However, increasing the resonant frequency shortens the wavelength contributing to resonance, and therefore, when the resonant frequency is high, there is a risk that the vibration intensity will decrease due to errors in processing accuracy, etc. A decrease in vibration intensity reduces the Q value, which is the quality factor Q. [Means for solving the problem]

[0005] The vibration element of the present invention, which solves the above problem, is a vibration element that uses a piezoelectric material made of a zinc blende-type single crystal, and is ring-shaped and has a vibration part in which a plurality of first vibration parts and a plurality of second vibration parts are alternately arranged in at least a portion thereof, and the vibration part has a first electrode provided on each of the plurality of first vibration parts, a second electrode provided on each of the plurality of second vibration parts, a first connection part that electrically connects the first electrodes to each other, and a second connection part that electrically connects the second electrodes to each other, characterized in that the plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the

[0001] axis of the single crystal. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a perspective view of a vibration element according to a first embodiment of the present invention, viewed from the (001) plane side of a cubic crystal. [Figure 2] 1 is a schematic diagram showing how a longitudinal wave is reflected as a transverse wave at a first reflecting section, a transverse wave is reflected as a transverse wave at a second reflecting section, and a transverse wave is reflected as a longitudinal wave at a third reflecting section. [Figure 3] Graph showing the relationship between the angle of incidence and the angle of reflection, the angle of incidence and the amplitude of reflection, and the angle of incidence and the phase change when a longitudinal wave is incident. [Figure 4] Graph showing the relationship between the angle of incidence and the angle of reflection, the angle of incidence and the amplitude of reflection, and the angle of incidence and the phase change when a shear wave is incident. [Figure 5] 1 is a perspective view illustrating the vicinity of a position where a first connecting portion and a second connecting portion of a vibration element according to a first embodiment of the present invention are overlapped. [Figure 6] 4 is a graph showing the change over time in voltage at the first electrode, the second electrode, and the common electrode of the vibration element of Example 1 of the present invention. [Figure 7] FIG. 2 is a schematic plan view of a part of a vibration part of the vibration element of the first embodiment of the present invention, showing a state when a voltage is applied. [Figure 8] 2 is a diagram showing the crystal structure of a single crystal of a piezoelectric body of the vibration element according to the first embodiment of the present invention. FIG. [Figure 9] FIG. 1 is a schematic diagram showing the vibration element of Example 1 of the present invention as viewed from the (001) plane side of a cubic crystal, illustrating the deformation state of each vibrator unit. [Figure 10] FIG. 10 is a schematic plan view of a vibration part of a vibration element according to a second embodiment of the present invention, illustrating a state when a voltage is applied. DETAILED DESCRIPTION OF THE INVENTION

[0007] First, the present invention will be briefly described. In order to solve the above problem, a vibration element of a first aspect of the present invention is a vibration element using a piezoelectric material made of a zinc blende-type single crystal, and is provided with a ring-shaped vibration part in which a plurality of first vibration parts and a plurality of second vibration parts are alternately arranged in at least a portion thereof, and the vibration part has a first electrode provided on each of the plurality of first vibration parts, a second electrode provided on each of the plurality of second vibration parts, a first connection part that electrically connects the first electrodes to each other, and a second connection part that electrically connects the second electrodes to each other, characterized in that the plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the

[0001] axis of the single crystal.

[0008] According to this aspect, a ring-shaped vibrating section has, at least in part, a plurality of first vibrating sections and a plurality of second vibrating sections alternately arranged, and first electrodes corresponding to the first vibrating sections and second electrodes corresponding to the second vibrating sections are alternately arranged on a plane perpendicular to the

[0001] axis of the single crystal. By arranging a plurality of vibrator units in at least a part of the ring-shaped vibrating section in this manner, the phases of the vibration waves generated by each vibrator unit can be aligned and circulated around the ring-shaped vibrating section. Therefore, by circulating the waves, the vibration strength can be increased, and a high Q value can be obtained.

[0009] A vibration element according to a second aspect of the present invention is an aspect dependent on the first aspect, and is characterized by including a reflecting portion that reflects vibrations generated by the vibrating portion.

[0010] According to this aspect, the reflecting section is provided to reflect the vibrations generated by the vibrating section, and therefore, in the ring-shaped vibrating section, the vibration waves generated by each vibrator unit can be easily synchronized in phase and circulated.

[0011] A third aspect of the vibration element of the present invention is an aspect dependent on the second aspect, and is characterized in that the reflecting portion includes a first reflecting portion that reflects incident longitudinal waves as transverse waves, and a second reflecting portion that reflects transverse waves that are incident via the first reflecting portion as longitudinal waves.

[0012] According to this aspect, the reflecting section includes a first reflecting section that reflects an incident longitudinal wave as a transverse wave and a second reflecting section that reflects a transverse wave that is incident via the first reflecting section as a longitudinal wave. Therefore, in the ring-shaped vibrating section, the vibration waves generated by each vibrator unit can be circulated in phase with each other while changing from a longitudinal wave to a transverse wave and from a transverse wave to a longitudinal wave.

[0013] A fourth aspect of the vibration element of the present invention is an aspect dependent on the third aspect, and is characterized in that the reflecting portion has a third reflecting portion between the first reflecting portion and the second reflecting portion, which reflects incident transverse waves as transverse waves.

[0014] According to this aspect, the reflecting section includes a third reflecting section between the first reflecting section and the second reflecting section, which reflects the incident shear wave as a shear wave. Therefore, the third reflecting section can adjust the direction of the shear wave so that the shear wave travels preferably from the first reflecting section to the second reflecting section.

[0015] A vibration element according to a fifth aspect of the present invention is an aspect dependent on the second aspect, and is characterized in that the reflecting portion includes a fourth reflecting portion that reflects an incident longitudinal wave as a longitudinal wave.

[0016] According to this aspect, the reflecting section has a fourth reflecting section that reflects the incident longitudinal wave as a longitudinal wave, and therefore, by combining the vibration waves generated by each vibrator unit while maintaining the state of longitudinal waves in the ring-shaped vibrating section, it is possible to match and strengthen the phases of the vibration waves generated by each vibrator unit.

[0017] A sixth aspect of the vibration element of the present invention is an aspect dependent on any one of the first to fifth aspects, and is characterized in that it comprises a spacer between the first connection portion and the second connection portion at a position where the first connection portion and the second connection portion overlap when viewed from a direction parallel to the

[0001] axis of the single crystal, insulating the first connection portion from the second connection portion.

[0018] According to this aspect, a spacer is provided between the first and second connecting portions at a position where the first and second connecting portions overlap when viewed in a direction parallel to the

[0001] axis of the single crystal, insulating the first and second connecting portions from each other, thereby enabling a desired voltage to be stably applied to the first and second electrodes.

[0019] A seventh aspect of the vibration element of the present invention is an aspect dependent on any one of the first to fifth aspects, characterized in that a plurality of the first vibration parts and a plurality of the second vibration parts are arranged in the piezoelectric body parallel to the

[0110] axis of the single crystal or the [-110] axis of the single crystal.

[0020] According to this aspect, the plurality of first vibration parts and the plurality of second vibration parts are arranged in parallel to the

[0110] axis or the [-110] axis of the single crystal on the piezoelectric body. With this configuration, even when a voltage is applied to each electrode to vibrate the first vibration part and the second vibration part, distortion of the vibration part as a whole can be prevented in the direction in which the first vibration part and the second vibration part are arranged.

[0021] The vibration element of the eighth aspect of the present invention is an aspect dependent on any one of the first to fifth aspects, and is characterized by comprising: a base portion which is provided around at least a part of the periphery of the vibration portion when viewed from a direction parallel to the

[0001] axis of the single crystal, and on which a plurality of the first vibration portions and a plurality of the second vibration portions are not arranged; and a support portion which bridges the vibration portion and the base portion.

[0022] According to this aspect, the device includes a base portion provided around at least a portion of the periphery of the vibrating portion when viewed from a direction parallel to the

[0001] axis of the single crystal, on which the plurality of first vibrating portions and the plurality of second vibrating portions are not disposed, and a support portion bridging the vibrating portion and the base portion. With this configuration, it is possible to preferably provide a vibrating portion that vibrates when a voltage is applied to the electrodes, and a base portion that does not vibrate even when a voltage is applied to the electrodes.

[0023] A vibration element according to a ninth aspect of the present invention is an aspect dependent on the eighth aspect, characterized in that the support portion bridges the nodal points of the vibration portion and the base portion.

[0024] According to this aspect, the support section bridges the nodal points of the vibration section and the base section. This configuration bridges the base section and the areas of the vibration section that do not vibrate even when the vibration section vibrates due to application of a voltage to the electrodes. Therefore, it is possible to prevent the base section from vibrating even when a voltage is applied to the electrodes.

[0025] The vibration element of the tenth aspect of the present invention is an aspect dependent on the eighth aspect, characterized in that the support portion extends parallel to the

[0110] axis of the single crystal or the [-110] axis of the single crystal.

[0026] According to this aspect, the support portion extends parallel to the

[0110] axis or the [-110] axis of the single crystal, and this configuration allows the vibrating portion and the base portion to be suitably bridged.

[0027] The vibration element of the sixth aspect of the present invention is an aspect dependent on any one of the first to fifth aspects, and is characterized in that the piezoelectric body is made of any of SiC, GaN, GaAs, ZnS, CdS, and AlN.

[0028] According to this aspect, the piezoelectric body is made of any one of SiC, GaN, GaAs, ZnS, CdS, and AlN. With this configuration, a suitable piezoelectric body can be obtained.

[0029] [Example 1] Hereinafter, a vibration element 100 according to a first embodiment of the present invention will be described with reference to the accompanying drawings, with reference to FIGS. 1 to 9. The vibration element 100 of this embodiment is a piezoelectric vibration element using a piezoelectric material made of a zinc blende single crystal. As shown in FIG. 1, the vibration element 100 of this embodiment is mainly composed of a vibration section 1 that vibrates when a voltage is applied, a base section 3 that does not vibrate even when a voltage is applied, and a support section 2 that bridges the vibration section 1 and the base section 3. Note that "does not vibrate even when a voltage is applied" does not strictly mean that it is necessary for the vibration element to not vibrate at all, but means that vibration is suppressed to an extent that does not cause any malfunction.

[0030] The vibration unit 1 is composed of a substrate of a zinc-blende single crystal (point group F-43m) that has a piezoelectric effect. Examples of zinc-blende single crystals that can be used include cubic 3C-SiC single crystals. The vibration unit 1 is ring-shaped, and as will be described in detail later, a portion of the ring has multiple first vibration units and multiple second vibration units that are adjacent to each other and alternately arranged in the direction of the single crystal's

[0110] axis. In each of Figures 1, 2, 5, 7 to 9, and 10, the a1 axis corresponds to the single crystal's

[0100] axis, the a2 axis corresponds to the single crystal's

[0010] axis, and the a3 axis corresponds to the single crystal's

[0001] axis.

[0031] The vibrating section 1 is formed on the surface on the

[0001] axis side and is composed of an electrode group including electrode units 11 each corresponding to a vibrator unit 16 of the first vibrating section and the second vibrating section, two common electrodes (not shown) formed in an area on the surface on the [00-1] axis side corresponding to the back side of the area where the electrode units 11 are formed, a longitudinal wave-to-shear wave converter 13, and a total reflection section 14. The structure consisting of the electrode group on the surface on the

[0001] axis side, the area of the common electrode on the surface on the [00-1] axis side facing it, and an area of the single crystal substrate where stress is generated due to the piezoelectric effect when a voltage is applied between these electrodes functions as a single vibrator and composes the vibrator unit 16. For example, the single crystal substrate can be made of 3C-SiC single crystal, as well as AlN or GaN, which belong to the zincblende type single crystal (point group F-43m). The electrode material may be, for example, Au, Pt, or Al, and a layer of Ti or a compound thereof may be provided between these metal materials and the single crystal to strengthen adhesion.

[0032] In this specification, the

[0100] axis may refer to the direction of the arrow on the a1 axis, the [-100] axis may refer to the direction opposite to the direction of the arrow on the a1 axis, and the

[0100] axis may refer to the direction along the arrow on the a1 axis and its opposite direction. The

[0010] axis may refer to the direction of the arrow on the a2 axis, the [0-10] axis may refer to the direction opposite to the direction of the arrow on the a2 axis, and the

[0010] axis may refer to the direction along the arrow on the a3 axis and its opposite direction. The

[0001] axis may refer to the direction of the arrow on the a3 axis, the [00-1] axis may refer to the direction opposite to the direction of the arrow on the a3 axis, and the

[0001] axis may refer to the direction along the arrow on the a3 axis and its opposite direction.

[0033] The excitation section 12, corresponding to the formation region of the electrode units 11, has a structure in which oscillator units 16 are arranged in a matrix along the (001) plane of a cubic crystal. Specifically, two rows of oscillator units 16 are arranged along the [-110] axis of the single crystal, and multiple oscillator units 16 are arranged along the

[0110] axis of the single crystal. The longitudinal wave component of the elastic wave generated by the displacement of each oscillator unit 16 and propagating in the longitudinal direction of the excitation section 12, i.e., the

[0110] axis direction of the single crystal, becomes a traveling wave. As will be described in detail later, this traveling wave is reflected by the longitudinal wave-to-transverse wave converter 13 and then propagates and reflects again at the total reflection section 14, circulating along the ring-shaped structure of the vibration section 1. In addition to the traveling wave component circulating in one direction, there is also a traveling wave component circulating in the opposite direction. These two traveling waves interfere with each other to generate a standing wave. Due to the structure of the vibration section 1, the center position of this standing wave becomes a node.

[0034] 2, the longitudinal wave-to-shear wave converter 13 has a planar end surface that reflects the traveling wave of the longitudinal wave P generated in the excitation unit 12, converts it into a shear wave SV, and reflects it in the direction of the total reflection unit 14, or converts the shear wave SV into a longitudinal wave P and reflects it in the direction of another excitation unit 12. Here, the behavior of reflection at the longitudinal wave-to-shear wave converter 13 will be explained below.

[0035] If the sound velocities of longitudinal waves P (P waves) and shear waves SV (SV waves) in a crystal are represented by α and β, respectively, the values of α and β are generally different. For example, typical values for 3C-SiC are α = 11,938 m / s and β = 7,608 m / s. In this case, when longitudinal waves P are reflected from a free surface, shear wave SV components are generated, which exit at different angles and separate from the longitudinal wave P components. Similarly, when shear waves SV are reflected from a free surface, they separate into shear wave SV components and longitudinal wave P components. The equations showing this reflection amplitude and phase change are shown in Table 1 below. The variables used here are shown in Equation 1 below. Figure 3 shows the outgoing angle Θ* of longitudinal waves P, the outgoing angle φ* of shear waves SV, and the reflection amplitude and phase change when the incident angle Θ of longitudinal waves P is used as a variable. As shown in the middle graph of Figure 3, when the incident angle of the longitudinal wave P is Θ = 46°, the reflected amplitude of the longitudinal wave P is 0, and it can be seen that all of the vibration energy of the longitudinal wave P is converted into a shear wave SV. As shown in Figure 2, when Θ = 46°, φ* = 27°, and the outgoing angle φ* of the shear wave SV is different from the incident angle Θ of the longitudinal wave P. On the other hand, Figure 4 shows the outgoing angle Θ* of the longitudinal wave P, the outgoing angle φ* of the shear wave SV, the reflection amplitude, and the phase change when the incident angle φ of the shear wave SV is a variable. When the incident angle φ of the shear wave SV is φ = 27°, as shown in the middle graph of Figure 4, the reflected amplitude of the shear wave SV is 0, and it is possible to convert all of the vibration energy of the shear wave SV into a longitudinal wave P.

[0036] [Table 1]

[0037]

number

[0038] As shown in Fig. 2, the total reflection section 14 has a flat surface for totally reflecting the shear wave SV that has been reflected and converted by the longitudinal wave-to-shear wave conversion section 13, and for emitting the shear wave in the direction of the longitudinal wave-to-shear wave conversion section 13 that is located symmetrically to the side from which it was incident. As shown in Fig. 4, it can be seen that the shear wave SV is totally reflected at an incident angle φ = 73°. Note that Fig. 2 shows the positional relationship between the paths of the series of traveling waves of the longitudinal wave P-to-shear wave SV wave conversion, total reflection of the shear wave SV, and shear wave SV-to-longitudinal wave P conversion that have been explained so far, and the reflection surface.

[0039] Next, an example of a method for connecting the electrode units 11 will be described below based on this embodiment. To obtain constructive vibrations from the traveling waves generated by all of the oscillator units 16 working together, the electrode units 11 are connected so that the directions of the electric fields applied in the

[0001] axial direction are antiparallel to adjacent oscillator units 16 in the

[0100] axial direction or the

[0010] axial direction. To achieve this, all of the electrode units belong to either the a-electrode group corresponding to the first oscillator section corresponding to oscillator units 161 and 162 of the oscillator units 16 in FIG. 5, or the b-electrode group corresponding to the second oscillator section corresponding to oscillator units 163 and 164 of the oscillator units 16 in FIG. 5.

[0040] 5 shows an enlarged structure of region R in FIG. 1. Among electrode units 11, electrode units 111 and 112, which are arranged diagonally on the surface of the single-crystal substrate, belong to electrode group a and are connected by bridge portion 11b. On the other hand, electrode units 113 and 114 of electrode units 11 belong to electrode group b and are connected by link portion 11c. Here, the region sandwiched between electrode unit 111 of vibrating portion 1 and the common electrode corresponds to vibrator unit 161, and the region sandwiched between electrode unit 112 of vibrating portion 1 and the common electrode corresponds to vibrator unit 162. The region sandwiched between electrode unit 113 of vibrating portion 1 and the common electrode corresponds to vibrator unit 163, and the region sandwiched between electrode unit 114 of vibrating portion 1 and the common electrode corresponds to vibrator unit 164.

[0041] The link portion 11c and the bridge portion 11b are electrically insulated by a spacer 11a. The spacer 11a can be made of an oxide such as SiO2, a nitride, a resin material, or the like. All of the electrode units 11 belonging to the electrode group a are connected using this cross-connection method. On the other hand, all of the electrode units 11 belonging to the electrode group b are connected in the same manner. As a result of this connection, electrode units 11 with different polarities are alternately arranged on the surface of the cubic (001) plane of the vibrating portion 1, forming a so-called checkerboard pattern. Furthermore, a common electrode formed on the back surface of the cubic (00-1) plane of the vibrating portion 1 is connected to a common electrode (not shown) provided on the back surface of the base portion 3 via an electrode formed on the back surface of the support portion 2.

[0042] Here, the support portion 2 is a portion for holding the vibrating portion 1 in a relative position with respect to the base portion 3. The same single-crystal substrate as the vibrating portion 1 can be used as the material, but it can also be formed by bonding other materials. To minimize vibration leakage from the vibrating portion 1 to the base portion 3, it is desirable to connect the support portion 2 to the vibrating portion 1 at a location where there is no vibration displacement of the vibrating portion 1, i.e., a node position. While it is desirable to minimize the thickness of the support portion 2 to minimize vibration leakage from the vibrating portion 1 to the base portion 3, it is also desirable to ensure the necessary strength by making the support portion 2 of an appropriate thickness to prevent damage to the support portion 2 due to external vibration or impact. Furthermore, while FIG. 1 shows the support portion 2 as a straight, rectangular columnar shape, its length can be optimized or a curved structure can be incorporated to alleviate stress concentration and improve impact resistance. In this embodiment, electrodes are formed on the surface of the support portion 2, which also serves to electrically connect the vibrating portion 1 to the electrodes formed on the base portion 3.

[0043] The base portion 3 is fixed in a hermetically sealed package that surrounds the piezoelectric vibrator. It can be made of the same single-crystal substrate as the vibrating portion 1 and the support portion 2, but it can also be formed by bonding other materials. Lead electrode 5a formed on the surface of the base portion 3 shown in FIG. 1 is electrically connected to all electrode units of electrode group a via electrodes formed on the surface of the support portion 2. On the other hand, lead electrode 5b shown in FIG. 1 is electrically connected to all electrode units of electrode group b. Furthermore, lead electrodes 5a and 5b are connected to an oscillator circuit (not shown) installed in the same package by wire bonding or the like to supply power to the vibrating portion 1.

[0044] In the vibrating element 100 of this embodiment, applying a voltage between the electrode unit 11 and the opposing common electrode makes it possible to apply an electric field in the

[0001] axial direction to the single crystal substrate. This action enables the single crystal of each vibrator unit 16 to operate in contour vibration. Specifically, when the single crystal expands in the

[0110] axial direction at a certain phase, it contracts in the [-110] axial direction, and when the direction of the electric field is reversed, it contracts in the

[0110] axial direction, corresponding to the operation of a vibration mode in which the single crystal expands in the [-110] axial direction. This contour vibration operation simultaneously causes equal amounts of expansion and contraction in different directions in a local area within the single crystal substrate, resulting in no volume change. This is advantageous from the perspective of thermoelastic loss and Akhiezer loss due to phonon scattering.

[0045] Here, examples of voltage waveforms applied to the lead electrodes 5a, 5b, and common electrode are shown in FIG. 6. These voltage waveforms can be generated by the oscillator circuit (not shown) described above. In FIG. 6, the lead electrode 5a is represented by a solid line, the lead electrode 5b by a dashed line, and the common electrode by a two-dot dashed line. The voltage waveforms applied to the lead electrodes 5a and 5b are sine waves with the same amplitude but are shifted in phase by π [rad] for half a cycle. The common electrode voltage is the average voltage applied to the lead electrodes 5a and 5b. As shown in FIG. 6, when the voltages applied to the lead electrodes 5a and 5b have opposite signs but the same amplitude, the voltage of the common electrode is a constant value.

[0046] Applying an AC voltage of a frequency at which the vibrating unit 1 resonates to the lead electrodes 5a and 5b enables the desired vibration. For example, Figure 7 shows the displacement of a corner of the vibrating unit 1, exaggerated for clarity. Here, the vibrator units 16 corresponding to the same hatching are formed with electrode units belonging to the same electrode group, either the a-electrode group or the b-electrode group. When no voltage is applied to the lead electrodes 5a and 5b, all vibrator units 16 remain square without displacement. However, applying an electric field in the same direction results in the same deformation. Furthermore, applying a voltage causes displacement. After a time equivalent to half a cycle of the resonant frequency has elapsed, reversing the direction of voltage application reverses the warping direction of the outline of each vibrator unit 16. In other words, even when the direction of voltage application is continuously reversed, the boundary surfaces of adjacent vibrator units 16 remain smooth and the warping is consistent, resulting in no unnecessary distortion.

[0047] Similarly, by repeatedly reversing the direction of voltage application in accordance with the resonant frequency, all of the oscillator units 16 cooperate and constructively generate stable, low-loss vibrations. This causes the phases of adjacent loops of the standing wave to be opposite, resulting in a stable standing wave.

[0048] Next, we will explain the appropriate crystal orientation for achieving the above-mentioned vibration operation. Figure 8 shows the crystal structure of 3C-SiC used in the vibration element 100 of this example. The single crystal's

[0100] axis, single crystal's

[0010] axis, and single crystal's

[0001] axis correspond to the a1 axis, a2 axis, and a3 axis, respectively, and confirm the displacement when an electric field is applied.

[0049] In general, the piezoelectric tensor e of e form in a crystal of point group F-43m is described by Equation 2 below:

[0050]

number

[0051] On the other hand, the piezoelectric tensor d of d-form can be derived as shown in the following equation 4 using the following equation 3, which is the elastic compliance tensor SE.

[0052]

number

[0053]

number

[0054] Here, the displacement tensor S when an electric field E having components E1, E2, and E3 in the directions of the a1, a2, and a3 axes, respectively, is applied can be expressed by the following equation 5.

[0055]

number

[0056] Here, when an electric field is applied in the axial direction of the a3 axis, only the component of E3 becomes non-zero, and therefore only the component S6 of the displacement tensor S becomes non-zero. The definition equation for this component S6 is Equation 6 below.

[0057]

number

[0058] Here, u1 and u2 represent the amount of displacement in the axial direction of the a1 axis and the a2 axis, respectively. Next, we will use Figure 9 to explain what kind of deformation the above-mentioned amount of displacement actually brings about in the vibrating part 1. In particular, since component S6 does not have a component in the axial direction of the a3 axis, it is expressed in a two-dimensional plane including the a1 axis and the a2 axis. First, from the defining formula 5, we obtain the following formula 7, and from formula 7, we obtain the following formula 8.

[0059]

number

[0060]

number

[0061] Here, if we assume that component S6 is a positive value, then S12 and S21 will also be positive values. When moving only a small distance +Δa1 from the S12 component of the defining equation (Equation 5), the change in displacement will be +Δu2, and similarly, when moving +Δa2 from the S21 component, the displacement will be +Δu1. The displacement obtained by combining these will be in the positive direction of the a1' axis in Figure 9. Conversely, at positions (-Δa1, -Δa2), the displacements will be -Δu1, -Δu2, so the combined displacement will be in the negative direction of the a1' axis. As a result, the small region within the oscillator unit 16 will be elongated and deformed in the axial direction of the a1' axis.

[0062] On the other hand, at position (Δa1, -Δa2), there is a positive displacement along the a2' axis, and at position (-Δa1, Δa2), there is a negative displacement along the same axis, resulting in contraction deformation along the a2' axis. Then, when the direction of applied voltage is reversed, the sign of component S6 is also reversed, and the expansion and contraction directions are swapped.

[0063] As explained above, by assigning the

[0001] axis to the a3 axis, the

[0110] axis to the a1' axis, and the [-110] axis to the a2' axis shown in Figure 1, the displacement required for the desired contour vibration can be obtained. Furthermore, at points (Δa1, 0), (-Δa1, 0), (0, Δa2), and (0, -Δa2), contour vibration occurs but there is no displacement at all, i.e., they become vibration nodes. Therefore, providing the support 2 in this direction can suppress vibration leaking to the base 3. Therefore, it is desirable to provide the support 2 in one of the crystal orientations

[0100] , [-100],

[0010] , or [0-10] from the center of gravity of any oscillator unit 16. As shown in Figure 1, the vibration element 100 of this embodiment has such a configuration, and for example, the vibrator unit 16 corresponding to the electrode unit 11 has a support portion 2 provided in the [-100] direction from its center of gravity.

[0064] That is, in the vibration element 100 of this embodiment, the support portion 2 bridges the nodal points of the vibration portion 1 and the base portion 3. By being configured in this manner, the vibration element 100 of this embodiment can bridge the regions of the vibration portion 1 that do not vibrate even when the vibration portion 1 vibrates by applying a voltage to the electrode units 11 as electrodes, and the base portion 3. Therefore, the vibration element 100 of this embodiment can prevent the base portion 3 from vibrating even when a voltage is applied to the electrode units 11.

[0065] From another perspective, assuming that the support portion 2 bridges the nodes of the vibration portion 1 and the base portion 3, the support portion 2 is connected to the four sides of the vibration portion 1, two of which extend along the

[0110] axis of the single crystal, and the remaining two of which extend parallel to the [-110] axis of the single crystal. With this configuration, the vibration element 100 of this embodiment can suitably bridge the vibration portion 1 and the base portion 3.

[0066] An oscillator can be constructed by combining the above-described vibration element 100 with an oscillation circuit. Furthermore, a more stable oscillator can be obtained by housing these in a vacuum package. While this embodiment uses a piezoelectric body made of a 3C-SiC single crystal, materials other than 3C-SiC single crystal may be used as long as the piezoelectric body is made of a zinc blende single crystal.

[0067] Here, the vibration element 100 of this embodiment will be described from another perspective. As described above, the vibration element 100 of this embodiment is ring-shaped and includes, at least in a portion thereof, a vibration unit 1 having a plurality of first vibration units, such as vibrator units 161 and 162, sandwiched between an electrode group a and a common electrode, and a plurality of second vibration units, such as vibrator units 163 and 164, sandwiched between an electrode group b and a common electrode, alternately arranged. The vibration unit 1 includes first electrodes corresponding to the electrode units 111 and 112, etc., and provided on each of the plurality of first vibration units; second electrodes corresponding to the electrode units 113 and 114, etc., and provided on each of the plurality of second vibration units; bridge portions 11b serving as first connectors electrically connecting the first electrodes; and link portions 11c serving as second connectors electrically connecting the second electrodes. The plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the

[0001] axis of the single crystal.

[0068] In this way, the vibration element 100 of this embodiment is configured such that a plurality of vibrator units 16 are arranged in at least a part of the ring-shaped vibrating part 1, so that the phases of the vibration waves generated by the respective vibrator units 16 can be matched and circulated in the ring-shaped vibrating part 1. Therefore, the vibration strength of the vibration element 100 of this embodiment can be increased by circulating it, and a high Q value can be obtained.

[0069] 5, the vibration element 100 of this embodiment includes a spacer 11a between the bridge portion 11b and the link portion 11c at a position where the bridge portion 11b and the link portion 11c overlap when viewed in a direction parallel to the

[0001] axis of the single crystal, the spacer 11a insulating the bridge portion 11b from the link portion 11c. This allows a desired voltage to be stably applied to the first electrode and the second electrode.

[0070] Furthermore, as described above, the vibration element 100 of this embodiment includes the longitudinal wave-to-shear wave converter 13 and the total reflection section 14 as reflecting sections that reflect the vibration generated in the vibration section 1. Therefore, the vibration element 100 of this embodiment can easily align the phases of the vibration waves generated by each vibrator unit 16 in the ring-shaped vibration section 1 and cause them to circulate.

[0071] 2, the longitudinal wave-to-shear wave converter 13 has a first reflecting portion on the left side that reflects the incident longitudinal wave P as a shear wave SV, and a second reflecting portion on the right side that reflects the shear wave SV that has entered through the first reflecting portion as a longitudinal wave P. That is, the vibration element 100 of this embodiment has, as its reflecting portion, a first reflecting portion that reflects the incident longitudinal wave P as a shear wave SV, and a second reflecting portion that reflects the shear wave SV that has entered through the first reflecting portion as a longitudinal wave P. Therefore, the vibration element 100 of this embodiment can circulate the vibration waves generated by each vibrator unit 16 in phase with each other while changing the longitudinal wave P to a shear wave SV and the shear wave SV to a longitudinal wave P in the ring-shaped vibration unit 1.

[0072] 2, the vibration element 100 of this embodiment has, as a reflection portion, a total reflection portion 14 serving as a third reflection portion that reflects the incident shear wave SV as a shear wave SV between the first reflection portion and the second reflection portion. Therefore, the vibration element 100 of this embodiment is configured to be able to adjust the direction in which the shear wave SV travels by the total reflection portion 14 serving as the third reflection portion so that the shear wave SV travels suitably from the first reflection portion to the second reflection portion.

[0073] Furthermore, in the vibration element 100 of this embodiment, the multiple first vibration parts and the multiple second vibration parts are arranged on the piezoelectric body parallel to the

[0110] axis of the single crystal. This configuration of the vibration element 100 of this embodiment makes it possible to effectively prevent distortion of the entire vibration part in the direction in which the first vibration parts and the second vibration parts are arranged, even when a voltage is applied to each electrode unit 11 to vibrate the first vibration parts and the second vibration parts. In this embodiment, the multiple first vibration parts and the multiple second vibration parts are arranged on the piezoelectric body parallel to the

[0110] axis of the single crystal. However, a similar effect can be obtained with a configuration in which the multiple first vibration parts and the multiple second vibration parts are arranged on the piezoelectric body parallel to the [-110] axis of the single crystal.

[0074] Moreover, the vibration element 100 of this embodiment includes a base portion 3 that is provided around at least a portion of the periphery of the vibration portion 1 when viewed from a direction parallel to the

[0001] axis of the single crystal, and on which the plurality of first vibration portions and the plurality of second vibration portions are not arranged, and a support portion 2 that bridges the vibration portion 1 and the base portion 3. By being configured in this manner, the vibration element 100 of this embodiment can suitably include the vibration portion 1 that vibrates when a voltage is applied to the electrode units 11, and the base portion 3 that does not vibrate even when a voltage is applied to the electrode units 11.

[0075] Although there are no particular limitations on the material of the piezoelectric body as long as it is made of a zinc blende single crystal, it is preferable that the piezoelectric body be made of any of SiC, GaN, GaAs, ZnS, CdS, and AlN, as this configuration will result in a suitable piezoelectric body.

[0076] As described above, by arranging multiple vibrator units 16 operating in contour vibration mode in a ring shape, the phases of the acoustic waves generated by each vibrator unit 16 are aligned and rotated, resulting in a single constructive vibration mode and a high Q value. Furthermore, by forming two electrode groups with different polarities on the front surface of the vibrating part 1 and a common electrode on the back surface, alignment of the front and back surfaces during patterning is no longer necessary, improving productivity. Additionally, by using zinc blende crystals on a single crystal substrate and arranging them in the appropriate crystal orientation, strong contour vibration can be achieved. As a result of these effects, the vibrating element 100 of this embodiment can generate a large-amplitude, stable signal from the vibrating part 1, resulting in an oscillator with low phase noise.

[0077] [Example 2] Next, the vibration element 100 of Example 2 will be described with reference to FIG. 10. Note that FIG. 10 is a diagram showing the vibration unit 1, and has the same configuration as the vibration element 100 of Example 1 except for the parts described below. In FIG. 10, components common to Example 1 above are indicated by the same reference numerals, and detailed description thereof will be omitted. Here, except for the parts described below, the vibration element 100 of this example has the same characteristics as the vibration element 100 of Example 1.

[0078] In the vibrating element 100 of this embodiment, electrode units 11 are formed over the entire surface of the (001) plane of the cubic crystal of the vibrating portion 1, and a common electrode consisting of a solid electrode is formed over the entire surface of the (00-1) plane of the cubic crystal of the vibrating portion 1. With this configuration, as shown in FIG. 10 , vibrator units 16 are formed over the entire vibrating portion 1. Similar to the vibrating element 100 of Example 1, the vibrator units 16 are arranged alternately, with multiple first vibrating portions and multiple second vibrating portions. With this configuration, there are no reflective portions or reflective surfaces that vertically reflect traveling waves. However, at the corners 15 of the vibrating portion 1, there are vibrator units 16 that induce, by contour vibration, traveling waves propagating in the

[0110] axis direction of the single crystal, for example, in the [-110] axis direction of the single crystal. The action of these vibrator units 16 generates traveling waves that circulate, resulting in stable vibration.

[0079] From another perspective, the vibration element 100 of this embodiment is configured to have, as a reflection portion, a fourth reflection portion that corresponds to the side of the corner portion 15 and reflects the incident longitudinal wave P as a longitudinal wave P. For this reason, the vibration element 100 of this embodiment can match and strengthen the phases of the vibration waves generated by each of the vibrator units 16 in the ring-shaped vibration portion 1 by matching the vibration waves generated by each of the vibrator units 16 while maintaining the state of the longitudinal wave P.

[0080] The present invention is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit of the present invention. For example, the present invention can be applied to local oscillators incorporating the vibration element 100 of each of the above-described embodiments, distance measurement / positioning systems using the same local oscillator, and highly sensitive MEMS sensors. The technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0081] 1... vibrating portion, 2... supporting portion, 3... base portion, 5a... lead electrode, 5b... lead electrode, 11... electrode unit, 11a... spacer, 11b... bridge portion (first connection portion), 11c... link portion (second connection portion), 12... excitation portion, 13... longitudinal wave-to-shear wave conversion portion (reflection portion, first reflection portion, second reflection portion), 14... total reflection portion (reflection portion, third reflection portion), 15... corner portion (fourth reflection portion ), 16... vibrator unit, 100... vibrating element, 111... electrode unit (first electrode), 112... electrode unit (first electrode), 113... electrode unit (second electrode), 114... electrode unit (second electrode), 161... vibrator unit (first vibrating part), 162... vibrator unit (first vibrating part), 163... vibrator unit (first vibrating part), 164... vibrator unit (second vibrating part), P... longitudinal wave, SV... transverse wave

Claims

1. A vibration element using a piezoelectric body made of a zinc blende single crystal, a ring-shaped vibration unit having at least a portion in which a plurality of first vibration units and a plurality of second vibration units are alternately arranged; the vibration section has a first electrode provided on each of the plurality of first vibration sections, a second electrode provided on each of the plurality of second vibration sections, a first connection section that electrically connects the first electrodes to each other, and a second connection section that electrically connects the second electrodes to each other, A vibration element, characterized in that the plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the [001] axis of the single crystal.

2. The vibration element according to claim 1 , A vibration element comprising a reflecting portion that reflects vibrations generated by the vibrating portion.

3. The vibration element according to claim 2, A vibration element characterized in that the reflecting portion includes a first reflecting portion that reflects incident longitudinal waves as transverse waves, and a second reflecting portion that reflects transverse waves that are incident via the first reflecting portion as longitudinal waves.

4. The vibration element according to claim 3, The vibration element has, as the reflecting portion, a third reflecting portion between the first reflecting portion and the second reflecting portion, which reflects an incident transverse wave as a transverse wave.

5. The vibration element according to claim 2, The vibration element has, as the reflecting portion, a fourth reflecting portion that reflects an incident longitudinal wave as a longitudinal wave.

6. The vibration element according to any one of claims 1 to 5, A vibration element characterized in that a spacer is provided between the first connection portion and the second connection portion at a position where the first connection portion and the second connection portion overlap when viewed from a direction parallel to the [001] axis of the single crystal, insulating the first connection portion from the second connection portion.

7. The vibration element according to any one of claims 1 to 5, The vibration element characterized in that the plurality of first vibration parts and the plurality of second vibration parts are arranged in the piezoelectric body parallel to the [110] axis of the single crystal or the [-110] axis of the single crystal.

8. The vibration element according to any one of claims 1 to 5, A vibration element characterized by comprising: a base portion that is provided around at least a portion of the vibration portion when viewed from a direction parallel to the [001] axis of the single crystal, and on which multiple first vibration portions and multiple second vibration portions are not arranged; and a support portion that bridges the vibration portion and the base portion.

9. The vibration element according to claim 8, The vibration element is characterized in that the support portion bridges the nodal points of the vibration portion and the base portion.

10. The vibration element according to claim 8, The vibration element is characterized in that the support portion extends parallel to the [110] axis or the [−110] axis of the single crystal.

11. The vibration element according to any one of claims 1 to 5, A vibration element characterized in that the piezoelectric body is made of any one of SiC, GaN, GaAs, ZnS, CdS, and AlN.

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