Piezoelectric vibration element

Abstract

The piezoelectric vibration element includes: a piezoelectric sheet having a first main surface and a second main surface facing each other; a first electrode including a first excitation electrode provided on the first main surface and a first extraction electrode connected to a first outer peripheral portion of the first excitation electrode; and a second excitation electrode provided on the second main surface, in which, in plan view, a high-sound-velocity region is provided in the center of a region in which the first excitation electrode and the second excitation electrode overlap, and a low-sound-velocity region is provided in the periphery of the region in which the first excitation electrode and the second excitation electrode overlap. A first outer peripheral portion of the first excitation electrode is provided further inward than a second outer peripheral portion of the second excitation electrode, the sound velocity in a region where the first extraction electrode and the second excitation electrode overlap is lower than the sound velocity in a high-sound-velocity region and equal to or higher than the sound velocity in a low-sound-velocity region, and the sound velocity in a region where the first electrode and the second excitation electrode overlap is lower than the sound velocity in a low-sound-velocity region. At least one opening is provided in at least one of the first electrode and the second excitation electrode, and the at least one opening is provided within a range that is at least four times the thickness of the piezoelectric sheet from the boundary between the first excitation electrode and the first extraction electrode.

Description

Technical Field

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

[0002] Piezoelectric vibration elements are used in various electronic devices such as mobile communication terminals, communication base stations, and home appliances for applications such as timing devices, sensors, and oscillators. A piezoelectric vibration element includes a piezoelectric sheet having a pair of principal surfaces and a pair of excitation electrodes provided on the principal surfaces of the piezoelectric sheet.

[0003] For example, patent document 1 discloses a vibration element including a substrate that vibrates by thickness shear vibration, a first excitation electrode arranged on a main surface of one side of the substrate and having the four corners of a quadrilateral cut off, and a second excitation electrode arranged on the main surface of the other side of the substrate, wherein the ratio (S2 / S1) of the area S1 of the quadrilateral to the area S2 of the first excitation electrode is 87.7%≤(S2 / S1)<95.0%.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-158149

[0005] According to the vibration element described in Patent Document 1, the spurious excitation pole of the inharmonic mode can be reduced. However, with the advancement of high performance electronic devices, further improvements in vibration characteristics are required for piezoelectric vibration elements. Summary of the Invention

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a piezoelectric vibration element capable of improving vibration characteristics.

[0007] A piezoelectric vibration element according to one embodiment of the present invention includes: a piezoelectric sheet having a first principal surface and a second principal surface facing each other; first electrodes including a first excitation electrode provided on the first principal surface and a first extraction electrode connected to the first excitation electrode; and a second excitation electrode provided on the second principal surface. The piezoelectric vibration element includes, in a plan view, a high-sonic-velocity region located in the center of an overlapping region between the first excitation electrode and the second excitation electrode, and a low-sonic-velocity region located in the peripheral portion of the overlapping region between the first excitation electrode and the second excitation electrode, the sound velocity of which is lower than that of the high-sonic-velocity region. A first outer peripheral portion of the first excitation electrode is located inward of a second outer peripheral portion of the second excitation electrode. The sound velocity of the overlapping region between the first extraction electrode and the second excitation electrode is lower than that of the high-sonic-velocity region and is equal to or higher than that of the low-sonic-velocity region. At least one opening is provided in at least one of the first and second excitation electrodes in the overlapping region between the first and second excitation electrodes. The at least one opening is provided within a range substantially at a distance of no more than four times the thickness of the piezoelectric sheet from a boundary between the first excitation electrode and the first extraction electrode.

[0008] A piezoelectric vibration element according to another embodiment of the present invention includes: a piezoelectric sheet having a first principal surface and a second principal surface facing each other; first electrodes including a first excitation electrode provided on the first principal surface and a first extraction electrode connected to the first excitation electrode; and a second excitation electrode provided on the second principal surface. The piezoelectric vibration element comprises: a piezoelectric sheet having a first principal surface and a second principal surface; a first excitation electrode provided on the first principal surface; and a second excitation electrode provided on the second principal surface. The piezoelectric vibration element comprises: a high-sonic-velocity region located in the center of an overlapping region between the first excitation electrode and the second excitation electrode, and a low-sonic-velocity region located in the peripheral portion of the overlapping region between the first excitation electrode and the second excitation electrode, wherein the sound velocity is lower than that of the high-sonic-velocity region; a first outer peripheral portion of the first excitation electrode is located inward of a second outer peripheral portion of the second excitation electrode; a sound velocity in the overlapping region between the first extraction electrode and the second excitation electrode is lower than that of the high-sonic-velocity region and is equal to or higher than that of the low-sonic-velocity region; at least one first opening is provided in at least one of the first excitation electrode and the second excitation electrode in a region on the first extraction electrode side relative to the high-sonic-velocity region in the low-sonic-velocity region; and at least one second opening is provided in at least one of the first excitation electrode and the second excitation electrode in a region on the opposite side of the first extraction electrode across the high-sonic-velocity region in the low-sonic-velocity region.

[0009] According to the present invention, a piezoelectric vibration element capable of improving vibration characteristics can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is an exploded perspective view of the crystal resonator according to the first embodiment.

[0011] Figure 2 This is a cross section of the crystal resonator according to the first embodiment.

[0012] Figure 3 It is a top view of the crystal resonator element according to the first embodiment.

[0013] Figure 4 It is a cross-sectional view of the crystal resonator element according to the first embodiment.

[0014] Figure 5 It is a diagram showing the vibration distribution of the crystal resonator element according to the first embodiment.

[0015] Figure 6 It is a diagram showing the vibration distribution of the crystal resonator element according to the first embodiment.

[0016] Figure 7 It is a diagram showing the vibration distribution of the crystal resonator element according to the first embodiment.

[0017] Figure 8 It is a top view of a crystal resonator element of a comparative example.

[0018] Figure 9 It is a diagram showing the vibration distribution of a quartz crystal resonator element of a comparative example.

[0019] Figure 10 It is a diagram showing the vibration distribution of a quartz crystal resonator element of a comparative example.

[0020] Figure 11 It is a diagram showing the vibration distribution of a quartz crystal resonator element of a comparative example.

[0021] Figure 12 This is a graph showing simulation results based on the first embodiment.

[0022] Figure 13 This is a graph showing simulation results based on the first embodiment.

[0023] Figure 14 It is a plan view of the crystal resonator element according to the second embodiment.

[0024] Figure 15 This is a graph showing simulation results based on the second embodiment.

[0025] Figure 16 This is a graph showing simulation results based on the second embodiment.

[0026] Figure 17 This is a graph showing simulation results based on the second embodiment.

[0027] Figure 18 This is a graph showing simulation results based on the second embodiment.

[0028] Figure 19 This is a graph showing simulation results based on the second embodiment.

[0029] Figure 20 It is a plan view of the crystal resonator element according to the third embodiment.

[0030] Figure 21 It is a diagram showing the vibration distribution of the crystal resonator element according to the third embodiment.

[0031] Figure 22 It is a diagram showing the vibration distribution of the crystal resonator element according to the third embodiment.

[0032] Figure 23 It is a diagram showing the vibration distribution of the crystal resonator element according to the third embodiment.

[0033] Figure 24 It is a top view of the crystal resonator element according to the fourth embodiment.

[0034] Figure 25 It is a diagram showing the vibration distribution of the crystal resonator element according to the fourth embodiment.

[0035] Figure 26It is a diagram showing the vibration distribution of the crystal resonator element according to the fourth embodiment.

[0036] Figure 27 It is a diagram showing the vibration distribution of the crystal resonator element according to the fourth embodiment.

[0037] Figure 28 It is a top view of the crystal resonator element according to the fifth embodiment.

[0038] Figure 29 It is a graph showing simulation results based on the fifth embodiment.

[0039] Figure 30 It is a plan view of the crystal resonator element according to the sixth embodiment.

[0040] Figure 31 It is a graph showing simulation results based on the sixth embodiment.

[0041] Figure 32 It is a graph showing simulation results based on the sixth embodiment.

[0042] Figure 33 It is a top view of the crystal resonator element according to the seventh embodiment.

[0043] Figure 34 It is an enlarged plan view of the connection portion in the seventh embodiment.

[0044] Figure 35 It is a diagram showing the vibration distribution of the crystal resonator element according to the seventh embodiment.

[0045] Figure 36 It is a diagram showing the vibration distribution of the crystal resonator element according to the seventh embodiment.

[0046] Figure 37 It is a diagram showing the vibration distribution of the crystal resonator element according to the seventh embodiment.

[0047] Figure 38 It is a graph showing simulation results based on the seventh embodiment.

[0048] Figure 39 It is a graph showing simulation results based on the seventh embodiment.

[0049] Figure 40 It is a top view of the crystal resonator element according to the eighth embodiment.

[0050] Figure 41 It is a graph showing simulation results based on the eighth embodiment.

[0051] Figure 42 It is a diagram showing the vibration distribution of the crystal resonator element according to the eighth embodiment.

[0052] Figure 43 It is a diagram showing the vibration distribution of the crystal resonator element according to the eighth embodiment.

[0053] Figure 44 It is a diagram showing the vibration distribution of the crystal resonator element according to the eighth embodiment.

[0054] Figure 45 It is a top view of the crystal resonator element according to the ninth embodiment.

[0055] Figure 46 It is a diagram showing the vibration distribution of the crystal resonator element according to the ninth embodiment.

[0056] Figure 47 It is a diagram showing the vibration distribution of the crystal resonator element according to the ninth embodiment.

[0057] Figure 48 It is a diagram showing the vibration distribution of the crystal resonator element according to the ninth embodiment.

[0058] Figure 49 It is a top view of the crystal resonator element according to the tenth embodiment.

[0059] Figure 50 It is a diagram showing the vibration distribution of the crystal resonator element according to the tenth embodiment.

[0060] Figure 51 It is a diagram showing the vibration distribution of the crystal resonator element according to the tenth embodiment.

[0061] Figure 52 It is a diagram showing the vibration distribution of the crystal resonator element according to the tenth embodiment.

[0062] Figure 53 It is a top view of the crystal resonator element according to the eleventh embodiment.

[0063] Figure 54 It is a graph showing simulation results based on the eleventh embodiment.

[0064] Figure 55 It is a diagram showing the vibration distribution of the crystal resonator element according to the eleventh embodiment.

[0065] Figure 56 It is a diagram showing the vibration distribution of the crystal resonator element according to the eleventh embodiment.

[0066] Figure 57 It is a diagram showing the vibration distribution of the crystal resonator element according to the eleventh embodiment.

[0067] Figure 58 It is a top view of the crystal resonator element according to the twelfth embodiment.

[0068] Figure 59 It is a diagram showing the vibration distribution of the crystal resonator element according to the twelfth embodiment.

[0069] Figure 60 It is a diagram showing the vibration distribution of the crystal resonator element according to the twelfth embodiment.

[0070] Figure 61 It is a diagram showing the vibration distribution of the crystal resonator element according to the twelfth embodiment.

[0071] Figure 62 It is a top view of a crystal resonator element according to a thirteenth embodiment.

[0072] Figure 63 It is a diagram showing the vibration distribution of the crystal resonator element according to the thirteenth embodiment.

[0073] Figure 64 It is a diagram showing the vibration distribution of the crystal resonator element according to the thirteenth embodiment.

[0074] Figure 65 It is a diagram showing the vibration distribution of the crystal resonator element according to the thirteenth embodiment.

[0075] Figure 66 It is a top view of the crystal resonator element according to the fourteenth embodiment.

[0076] Figure 67 It is a top view of the crystal resonator element according to the fifteenth embodiment.

[0077] Figure 68 It is a graph showing simulation results based on the fourteenth embodiment and the fifteenth embodiment.

[0078] Figure 69 It is a graph showing simulation results based on the fifteenth embodiment.

[0079] Figure 70 It is a graph showing simulation results based on the fourteenth embodiment.

[0080] Figure 71 It is a graph showing simulation results based on the fourteenth embodiment.

[0081] Figure 72 It is a top view of the crystal resonator element according to the sixteenth embodiment.

[0082] Figure 73 It is a diagram showing the vibration distribution of the crystal resonator element according to the sixteenth embodiment.

[0083] Figure 74 It is a diagram showing the vibration distribution of the crystal resonator element according to the sixteenth embodiment.

[0084] Figure 75 It is a diagram showing the vibration distribution of the crystal resonator element according to the sixteenth embodiment.

[0085] Figure 76 It is a top view of the crystal resonator element according to the seventeenth embodiment.

[0086] Figure 77 It is a diagram showing the vibration distribution of the crystal resonator element according to the seventeenth embodiment.

[0087] Figure 78 It is a diagram showing the vibration distribution of the crystal resonator element according to the seventeenth embodiment.

[0088] Figure 79 It is a diagram showing the vibration distribution of the crystal resonator element according to the seventeenth embodiment.

[0089] Figure 80 It is a top view of the crystal resonator element according to the eighteenth embodiment.

[0090] Figure 81 It is a diagram showing the vibration distribution of the crystal resonator element according to the eighteenth embodiment.

[0091] Figure 82 It is a diagram showing the vibration distribution of the crystal resonator element according to the eighteenth embodiment.

[0092] Figure 83 It is a diagram showing the vibration distribution of the crystal resonator element according to the eighteenth embodiment.

[0093] Figure 84 It is a top view of the crystal resonator element according to the nineteenth embodiment.

[0094] Figure 85 It is a diagram showing the vibration distribution of the crystal resonator element according to the nineteenth embodiment.

[0095] Figure 86 It is a diagram showing the vibration distribution of the crystal resonator element according to the nineteenth embodiment.

[0096] Figure 87 It is a diagram showing the vibration distribution of the crystal resonator element according to the nineteenth embodiment.

[0097] Figure 88 It is a top view of a crystal resonator element according to the twentieth embodiment.

[0098] Figure 89 It is a diagram showing the vibration distribution of the crystal resonator element according to the twentieth embodiment.

[0099] Figure 90 It is a diagram showing the vibration distribution of the crystal resonator element according to the twentieth embodiment.

[0100] Figure 91 It is a diagram showing the vibration distribution of the crystal resonator element according to the twentieth embodiment.

[0101] Figure 92 It is a top view of the crystal resonator element according to the twenty-first embodiment.

[0102] Figure 93 It is a diagram showing the vibration distribution of the crystal resonator element according to the twenty-first embodiment.

[0103] Figure 94 It is a diagram showing the vibration distribution of the crystal resonator element according to the twenty-first embodiment.

[0104] Figure 95 It is a diagram showing the vibration distribution of the crystal resonator element according to the twenty-first embodiment.

[0105] Figure 96 It is a top view of the crystal resonator element according to the twenty-second embodiment.

[0106] Figure 97 It is a diagram showing the vibration distribution of the crystal resonator element according to the twenty-second embodiment.

[0107] Figure 98 It is a diagram showing the vibration distribution of the crystal resonator element according to the twenty-second embodiment.

[0108] Figure 99 It is a diagram showing the vibration distribution of the crystal resonator element according to the twenty-second embodiment. DETAILED DESCRIPTION

[0109] The following describes an embodiment of the present invention. In the following drawings, the same or similar reference numerals represent the same or similar components. The drawings are for illustration only, and the sizes and shapes of the various parts are schematic and should not be interpreted as limiting the technical scope of the present invention to these embodiments.

[0110] In each of the drawings, an orthogonal coordinate system consisting of an X-axis, a Y'-axis, and a Z'-axis is sometimes added for convenience to clarify the relationships between the drawings and to help understand the positional relationships of the various components. The X-axis, Y'-axis, and Z'-axis correspond to each other in each of the drawings. The X-axis, Y'-axis, and Z'-axis correspond to the crystal axes (Crystallographic Axes) of the quartz plate 11 described later. The X-axis corresponds to the electrical axis (polar axis) of the quartz, the Y-axis corresponds to the mechanical axis of the quartz, and the Z-axis corresponds to the optical axis of the quartz. The Y'-axis and the Z'-axis are the axes obtained by rotating the Y-axis and the Z-axis counterclockwise by θ degrees around the X-axis when viewed from the positive direction of the X-axis.

[0111] In the following description, the direction parallel to the X-axis is referred to as the "X-axis direction", the direction parallel to the Y'-axis is referred to as the "Y'-axis direction", and the direction parallel to the Z'-axis is referred to as the "Z'-axis direction". In addition, the tip direction of the arrows of the X-axis, Y'-axis and Z'-axis is referred to as "positive" or "+(positive)", and the direction opposite to the arrow is referred to as "negative" or "-(negative)". In addition, although the +Y'-axis direction is set as the upward direction and the -Y'-axis direction is set as the downward direction for convenience, the upper and lower orientations of the quartz crystal resonator element 10 and the quartz crystal resonator 1 are not limited. In addition, the plane determined by the X-axis and the Z'-axis is referred to as the Z'X plane, and the same applies to the planes determined by other axes.

[0112] <First embodiment>

[0113] First, refer to Figure 1 as well as Figure 2 , the structure of the crystal resonator according to the first embodiment is described. Figure 1 This is an exploded perspective view of the crystal resonator according to the first embodiment. Figure 2 This is a cross section of the crystal resonator according to the first embodiment.

[0114] The crystal resonator 1 includes a crystal resonator element 10, a base member 30, a cover member 40, and a bonding portion 50. Hereinafter, the Y′-axis direction is referred to as the “thickness direction” of the crystal resonator element 10.

[0115] The crystal resonator 1 is used as a component of, for example, a temperature-compensated crystal oscillator (TCXO: Temperature Compensated Crystal Oscillator), a voltage-controlled crystal oscillator (VCXO: Voltage Controlled Crystal Oscillator), or an oven-controlled crystal oscillator (OCXO: Oven Controlled Crystal Oscillator).

[0116] The quartz crystal resonator element 10 is an electromechanical energy conversion element that converts electrical energy into mechanical energy through the piezoelectric effect. The frequency of the main mode of the quartz crystal resonator element 10 is, for example, above 0.8 GHz and below 2.0 GHz, for example, around 0.95 GHz. The frequency of the inharmonic mode of the quartz crystal resonator element 10 is, for example, within a range of approximately 1% of the main mode frequency.

[0117] The quartz crystal resonator 10 is excited at a predetermined frequency by an applied AC voltage. The quartz crystal resonator 10 is held in a vibrating space provided between the base member 30 and the cover member 40. The main vibration of the quartz crystal resonator 10 is the thickness shear vibration mode.

[0118] Furthermore, the main vibration of the quartz vibration element is not limited to the thickness shear vibration mode, and may be, for example, a thickness longitudinal vibration mode, an extension vibration mode, a length vibration mode, or a bending vibration mode.

[0119] like Figure 1 As shown, the quartz resonator element 10 includes a thin-sheet quartz plate (Quartz Crystal Element) 11, a first excitation electrode 14a and a second excitation electrode 14b constituting a pair of excitation electrodes, a first extraction electrode 15a and a second extraction electrode 15b constituting a pair of extraction electrodes, and a first connection electrode 16a and a second connection electrode 16b constituting a pair of connection electrodes.

[0120] The quartz plate 11 has an upper surface 11A and a lower surface 11B that face each other. The upper surface 11A is located on the side facing the top wall portion 41 of the cover member 40. The lower surface 11B is located on the side facing the base member 30. The upper surface 11A and the lower surface 11B correspond to a pair of principal surfaces of the quartz plate 11. The upper surface 11A corresponds to an example of a first principal surface, and the lower surface 11B corresponds to an example of a second principal surface.

[0121] The quartz plate 11 is, for example, an AT-cut quartz crystal. AT-cut quartz crystal is formed so that the XZ' plane serves as the principal surface, and the direction parallel to the Y' axis serves as the thickness. As an example, when viewing the upper surface 11A from the thickness direction (hereinafter referred to as "viewed from above"), the shape of the quartz plate 11 (hereinafter referred to as "planar shape") is a rectangle having a pair of short sides extending in the Z' axis direction and a pair of long sides extending in the X axis direction. As an example, the shape of the quartz plate 11 is a flat plate with a uniform thickness.

[0122] In addition, the planar shape of the quartz plate is not limited to the above. For example, the planar shape of the quartz plate may be a rectangle having long sides extending in the Z'-axis direction and short sides extending in the X-axis direction, or a square having sides extending in the Z'-axis direction and sides extending in the X-axis direction. The planar shape of the quartz plate may also be a rectangular shape having sides extending in a direction intersecting the Z-axis direction and the Z'-axis direction. The planar shape of the quartz plate may also be a polygon, a circle, an ellipse, or a combination thereof. In addition, the quartz plate is not limited to a flat plate. The quartz plate may also be a table-type structure or an inverted table-type structure having a concave and convex surface on at least one of the upper and lower surfaces. The quartz plate may be a convex structure in which the thickness variation varies continuously, or an inclined structure in which the thickness variation varies discontinuously.

[0123] The AT-cut quartz plate 11 is a quartz plate cut with the XZ' plane as the main surface, with the Y axis and the Z axis of the crystal axes of synthetic quartz (Synthetic Quartz Crystal) being rotated 35 degrees 15 minutes ± 1 minute 30 seconds from the Y axis to the Z axis around the X axis as the Y' axis and the Z' axis respectively.

[0124] The quartz crystal resonator element 10, which uses an AT-cut quartz crystal plate 11, exhibits high frequency stability over a wide temperature range. AT-cut quartz crystal resonators also exhibit excellent temporal characteristics and can be manufactured at low cost. Furthermore, AT-cut quartz crystal resonators primarily utilize the thickness shear vibration mode.

[0125] Furthermore, the cutting angle of the quartz plate is not limited to the above. The rotation angles of the Y' and Z' axes of the AT-cut quartz plate 11 can also be tilted within a range of 35 degrees and 15 minutes, ranging from -5 degrees to +15 degrees. Furthermore, the cutting angle of the quartz plate can also be applied to different cuts other than the AT cut, such as the BT cut, GT cut, and SC cut. Furthermore, the primary vibration mode of the quartz vibration element is not limited to the thickness shear vibration mode; for example, it can also be thickness longitudinal vibration, extension vibration, length vibration, or bending vibration.

[0126] The first excitation electrode 14a and the second excitation electrode 14b apply an AC voltage to the quartz plate 11 to excite the quartz plate 11. The first excitation electrode 14a and the second excitation electrode 14b are provided in the center of the quartz plate 11 when viewed from above. The first excitation electrode 14a is provided on the upper surface 11A, and the second excitation electrode 14b is provided on the lower surface 11B. The first excitation electrode 14a and the second excitation electrode 14b are opposed to each other in the Y'-axis direction with the quartz plate 11 interposed therebetween.

[0127] The first excitation electrode 14a has a rectangular planar shape with short sides extending in the Z'-axis direction and long sides extending in the X-axis direction. The first excitation electrode 14a has a thickness in the Y'-axis direction. The second excitation electrode 14b has the same shape.

[0128] Furthermore, the planar shapes of the first and second excitation electrodes are not limited to those described above. The planar shapes of the first and second excitation electrodes may also be rectangular with short sides extending in the X-axis direction, or square with sides extending in the X-axis direction and sides extending in the Z'-axis direction. The planar shapes of the first and second excitation electrodes may also be rectangular with sides extending in directions intersecting the Z-axis direction and the Z'-axis direction. The planar shapes of the first and second excitation electrodes may also be polygonal, circular, elliptical, or a combination thereof.

[0129] First extraction electrode 15a electrically connects first excitation electrode 14a to first connection electrode 16a, and second extraction electrode 15b electrically connects second excitation electrode 14b to second connection electrode 16b. First extraction electrode 15a extends from upper surface 11A to lower surface 11B of quartz plate 11, while second extraction electrode 15b is located on lower surface 11B of quartz plate 11.

[0130] The first connection electrode 16a and the second connection electrode 16b electrically connect the crystal vibration element 10 and the base member 30. The first connection electrode 16a and the second connection electrode 16b are provided on the lower surface 11B of the crystal plate 11.

[0131] The first excitation electrode 14a, the first extraction electrode 15a, and the first connection electrode 16a are integrally provided. The same applies to the second excitation electrode 14b, the second extraction electrode 15b, and the second connection electrode 16b. The set of electrodes consisting of the first excitation electrode 14a, the first extraction electrode 15a, and the first connection electrode 16a is referred to as the first electrode, and the set of electrodes consisting of the second excitation electrode 14b, the second extraction electrode 15b, and the second connection electrode 16b is referred to as the second electrode.

[0132] The first electrode and the second electrode may be, for example, a multilayer structure formed by sequentially stacking a base layer and a surface layer. For example, the base layer may be a chromium (Cr) layer having good adhesion to the quartz plate 11, and the surface layer may be a gold (Au) layer having good chemical stability. The first electrode and the second electrode may also include titanium (Ti), aluminum (Al), molybdenum (Mo), or an aluminum-copper alloy (AlCu) with aluminum (Al) as the main component. The first electrode and the second electrode may also be a single-layer structure.

[0133] The base member 30 holds the quartz crystal resonator element 10 so as to be excitable. The base member 30 includes a base 31, connection electrodes 33a, 33b, extraction electrodes 34a, 34b, external electrodes 35a, 35b, 35c, 35d, and conductive holding members 36a, 36b.

[0134] The substrate 31 is a plate-shaped insulator having an upper surface 31A and a lower surface 31B that are opposite to each other in the thickness direction. The upper surface 31A and the lower surface 31B are equivalent to a pair of main surfaces of the substrate 31. The upper surface 31A is located on the side opposite to the quartz vibration element 10 and the cover member 40, and is equivalent to the mounting surface on which the quartz vibration element 10 is mounted. From the viewpoint of suppressing the thermal stress applied from the substrate 31 to the quartz vibration element 10 due to thermal processes such as reflow, it is preferred that the substrate 31 be formed of a heat-resistant material. From the same viewpoint, the substrate 31 can also be provided by a material having a thermal expansion coefficient close to that of the quartz plate 11. For example, the substrate 31 is provided by a ceramic substrate, a glass substrate, or a quartz substrate.

[0135] The corners of the base 31 have a notched side surface, a portion of which is formed into a cylindrical curved surface (also called a dome shape). The shape of the corners of the base 31 is not limited thereto. The corners of the base may have a notched side surface formed into a prismatic shape, or may be substantially right-angled corners without a notch.

[0136] The connection electrodes 33a and 33b are electrically connected to the crystal resonator element 10. The connection electrode 33a is electrically connected to the connection electrode 16a of the crystal resonator element 10, and the connection electrode 33b is connected to the connection electrode 16b of the crystal resonator element 10.

[0137] The lead electrode 34a electrically connects the connection electrode 33a and the external electrode 35a, and the lead electrode 34b electrically connects the connection electrode 33b and the external electrode 35b. The lead electrodes 34a and 34b are provided on the upper surface 31A of the base 31.

[0138] The external electrodes 35a and 35b are external terminals for electrically connecting the quartz crystal vibration element 10 to an external substrate not shown. The external electrode 35a electrically connects the first excitation electrode 14a of the quartz crystal vibration element 10 to the external substrate, and the external electrode 35b electrically connects the second excitation electrode 14b of the quartz crystal vibration element 10 to the external substrate. One of the external electrodes 35c and 35d is a grounding electrode for grounding the cover part 40, and the other is a dummy electrode that is not electrically connected to the quartz crystal vibration element 10 and the cover part 40. The external electrodes 35a, 35b, 35c, and 35d are respectively provided continuously from the side faces of the cutouts provided at the four corners of the base 31 to the lower surface 31B. Figure 1In the illustrated example, the external electrodes 35 a and 35 b are located at diagonal positions on the upper surface 31A of the base 31 , and the external electrodes 35 c and 35 d are located at other diagonal positions on the upper surface 31A of the base 31 .

[0139] Furthermore, the functions and positions of the external electrodes 35a, 35b, 35c, and 35d are not limited to those described above. Both external electrodes 35c and 35d may be ground electrodes, or both may be dummy electrodes. External electrodes 35c and 35d may also be omitted. External electrode 35c may be electrically connected to one of external electrodes 35a and 35b, or external electrode 35d may be electrically connected to the other of external electrodes 35a and 35b. When viewed from above, external electrodes 35a and 35b may be located on either side of the same short side or on the same long side of the upper surface 31A of the substrate 31.

[0140] The conductive holding components 36a and 36b electrically connect the base component 30 and the quartz crystal vibration element 10 and mechanically hold the quartz crystal vibration element 10. The conductive holding component 36a electrically connects the first connection electrode 16a of the quartz crystal vibration element 10 and the connection electrode 33a of the base component 30. The conductive holding component 36b electrically connects the second connection electrode 16b of the quartz crystal vibration element 10 and the connection electrode 33b of the base component 30. The conductive holding components 36a and 36b are cured products of a conductive adhesive such as a thermosetting resin or a photocurable resin. The main component of the conductive holding components 36a and 36b is, for example, silicone resin. The conductive holding components 36a and 36b contain conductive particles, and as the conductive particles, metal particles containing silver (Ag) can be used, for example.

[0141] The main component of the conductive retaining members 36a and 36b is not limited to silicone resin; for example, epoxy resin or acrylic resin may also be used. Furthermore, the conductive particles contained in the conductive retaining members 36a and 36b are not limited to silver particles; they may also be formed from other metals, conductive ceramics, conductive organic materials, etc. The conductive retaining members 36a and 36b may also contain a conductive polymer.

[0142] The cover part 40 forms an internal space 39 for accommodating the quartz vibration element 10 between the cover part 40 and the base part 30. The cover part 40 has a top wall portion 41, a side wall portion 42 extending from the outer periphery of the top wall portion 41 toward the base part 30, and a flange portion 43 extending from the front end of the side wall portion 42 toward the outside. The top wall portion 41 is opposite to the base part 30 with the quartz vibration element 10 in the Y' axis direction. The side wall portion 42 surrounds the quartz vibration element 10 at a distance in the XZ' plane direction. The flange portion 43 is arranged in a frame shape when viewed from above and is arranged at a position in the cover part 40 closest to the base part 30. The material of the cover part 40 is preferably a conductive material, and more preferably a metal material with high airtightness. By forming the cover part 40 from a conductive material, the cover part 40 can be given an electromagnetic shielding function that reduces the entry and exit of electromagnetic waves into the internal space 39. To suppress the generation of thermal stress, the cover member 40 is preferably made of a material having a thermal expansion coefficient close to that of the base member 30, such as an Fe-Ni-Co alloy having a thermal expansion coefficient similar to that of glass and ceramics over a wide temperature range near room temperature. The cover member 40 is electrically connected to at least one of the external electrodes 35c and 35d via a grounding member (not shown).

[0143] The joint 50 joins the base member 30 and the cover member 40 and seals the internal space 39. The joint 50 is provided in a frame shape over the entire circumference of the flange portion 43 of the base member 30, and is clamped by the lower surface of the flange portion 43 of the cover member 40 and the upper surface 31A of the base member 30. The joint 50 is provided by an insulating material. For example, the joint 50 is provided by an organic adhesive including an epoxy-based, ethylene-based, acrylic-based, polyurethane-based or silicone-based resin. The material of the joint 50 is not limited to an organic adhesive, and may be provided by an inorganic adhesive such as a silicon-based adhesive including water glass or a calcium-based adhesive including cement. The material of the joint 50 may also be a low-melting-point glass (e.g., a lead borate-based, a tin phosphate-based, etc.).

[0144] Next, refer to Figure 3 as well as Figure 4 , the structure of the crystal resonator element 10 according to the first embodiment will be described. Figure 3 It is a top view of the crystal resonator element according to the first embodiment. Figure 4 It is a cross-sectional view of the crystal resonator element according to the first embodiment. Figure 4 It is along Figure 3 The quartz vibration element is shown in a cross-sectional view along line IV-IV. Figure 3In the figure, line IV-IV extends from the negative X-axis side of the quartz crystal resonator element 10 across the second low-velocity region 18B and the high-velocity region 17 in the X-axis direction, bends toward the first low-velocity region 18A, extends in the X-axis direction, bends again, and extends across the opening h1 and the first extraction electrode 15a in the X-axis direction to the positive X-axis side of the quartz crystal resonator element 10. Figure 3 as well as Figure 4 In the figure, the first connection electrode 16a and the second connection electrode 16b are omitted.

[0145] The quartz crystal resonator element 10 includes an excitation region 19, a high-sonic velocity region 17, and a low-sonic velocity region 18. The excitation region 19 is the region where the first excitation electrode 14a and the second excitation electrode 14b overlap, and is the region where a voltage is applied to the quartz plate 11 to excite it. The high-sonic velocity region 17 is a region in the excitation region 19 where the sound velocity is greater than the average sound velocity of the entire excitation region 19. The low-sonic velocity region 18 is a region in the excitation region 19 where the sound velocity is less than the average sound velocity of the entire excitation region 19. The sound velocity of the low-sonic velocity region 18 is less than the sound velocity of the high-sonic velocity region 17. The sound velocity of the region where the first extraction electrode 15a and the second excitation electrode 14b overlap is less than the sound velocity of the high-sonic velocity region 17 and is equal to or greater than the sound velocity of the low-sonic velocity region 18.

[0146] like Figure 3 As shown, the planar shape of excitation region 19 is a rectangle having a pair of sides extending along the X-axis and a pair of sides extending along the Z'-axis. The planar shape of excitation region 19 is determined by the planar shapes of first excitation electrode 14a, second excitation electrode 14b, and the positional relationship between first excitation electrode 14a and second excitation electrode 14b.

[0147] like Figure 3 As shown, in a plan view, the high-speed region 17 is located in the center of the excitation region 19. The planar shape of the high-speed region 17 is a rectangle having a pair of sides extending in the X-axis direction and a pair of sides extending in the Z'-axis direction.

[0148] Furthermore, the planar shape of the high-speed region is not limited to the above. The planar shape of the high-speed region may also be a rectangle having sides extending in directions intersecting the Z-axis and the Z'-axis. The planar shape of the high-speed region may also be a rectangle or a square. The planar shape of the high-speed region may also be a polygon, a circle, an ellipse, or a combination thereof.

[0149] In addition, when viewed from above, the high-sonic velocity region can also be set from the end of the excitation region on the positive side of the Z' axis to the end on the negative side of the Z' axis, or from the end of the excitation region on the positive side of the X axis to the end on the negative side of the X axis.

[0150] like Figure 3 As shown in FIG. 1 , in a plan view, the low-pitched tempo region 18 is located in the peripheral portion of the excitation region 19. The low-pitched tempo region 18 is provided in a rectangular frame shape surrounding the high-pitched tempo region 17. The low-pitched tempo region 18 includes a first low-pitched tempo region 18A, a second low-pitched tempo region 18B, a third low-pitched tempo region 18C, and a fourth low-pitched tempo region 18D.

[0151] The first low-pitched speed region 18A is adjacent to the positive X-axis side of the high-pitched speed region 17 and extends along the Z'-axis. The second low-pitched speed region 18B is adjacent to the negative X-axis side of the high-pitched speed region 17 and extends along the Z'-axis. The third low-pitched speed region 18C is adjacent to the positive Z'-axis side of the high-pitched speed region 17 and extends along the X-axis. The fourth low-pitched speed region 18D is adjacent to the negative Z'-axis side of the high-pitched speed region 17 and extends along the X-axis. The end of the first low-pitched speed region 18A on the positive Z'-axis side is connected to the end of the third low-pitched speed region 18C on the positive X-axis side, and the end of the first low-pitched speed region 18A on the negative Z'-axis side is connected to the end of the fourth low-pitched speed region 18D on the positive X-axis side. The end of the second low pitch region 18B on the positive side of the Z' axis is connected to the end of the third low pitch region 18C on the negative side of the X axis, and the end of the second low pitch region 18B on the negative side of the Z' axis is connected to the end of the fourth low pitch region 18D on the negative side of the X axis.

[0152] In a plan view, the end of the first low-pitched tempo region 18A on the positive Z'-axis side overlaps with the end of the third low-pitched tempo region 18C on the positive X-axis side, and the end of the first low-pitched tempo region 18A on the negative Z'-axis side overlaps with the end of the fourth low-pitched tempo region 18D on the positive X-axis side. The end of the second low-pitched tempo region 18B on the positive Z'-axis side overlaps with the end of the third low-pitched tempo region 18C on the negative X-axis side, and the end of the second low-pitched tempo region 18B on the negative Z'-axis side overlaps with the end of the fourth low-pitched tempo region 18D on the negative X-axis side.

[0153] Furthermore, the planar shape of the low-pitched speed region is determined by the planar shapes of the excitation region and the high-pitched speed region, and is not limited to the above. The planar shape of the low-pitched speed region may also be a polygonal, circular, elliptical, or a combination thereof. Furthermore, the third and fourth low-pitched speed regions may be omitted. That is, the high-pitched speed region, the first low-pitched speed region, and the second low-pitched speed region may be arranged as strips extending parallel to each other along the Z' axis. Alternatively, the first and second low-pitched speed regions may be omitted, and the high-pitched speed region, the third low-pitched speed region, and the fourth low-pitched speed region may be arranged as strips extending parallel to each other along the X-axis. Alternatively, the end of the first low-pitched speed region on the positive Z' axis side may be separated from the third low-pitched speed region, and the end of the first low-pitched speed region on the negative Z' axis side may be separated from the fourth low-pitched speed region. Alternatively, the end of the second low-pitched speed region on the positive Z' axis side may be separated from the third low-pitched speed region, and the end of the second low-pitched speed region on the negative Z' axis side may be separated from the fourth low-pitched speed region.

[0154] like Figure 3 As shown, when viewed from above, the quartz plate 11 has peripheral portions 91, 92, 93, and 94. Peripheral portion 91 is the peripheral portion of one side of the four peripheral portions of the quartz plate 11 extending along the Z'-axis direction on the positive X-axis side when viewed from above. Peripheral portion 92 is the peripheral portion of one side of the four peripheral portions of the quartz plate 11 extending along the Z'-axis direction on the negative X-axis side when viewed from above. Peripheral portion 93 is the peripheral portion of one side of the four peripheral portions of the quartz plate 11 extending along the X-axis direction on the positive Z'-axis side when viewed from above. Peripheral portion 94 is the peripheral portion of one side of the four peripheral portions of the quartz plate 11 extending along the X-axis direction on the negative Z'-axis side when viewed from above.

[0155] like Figure 3 As shown, in a plan view, the first excitation electrode 14a has peripheral portions 71, 72, 73, and 74. Peripheral portion 71 is the peripheral portion of one side of the four peripheral portions of the first excitation electrode 14a extending along the Z'-axis direction on the positive X-axis side in a plan view. Peripheral portion 72 is the peripheral portion of one side of the four peripheral portions of the first excitation electrode 14a extending along the Z'-axis direction on the negative X-axis side in a plan view. Peripheral portion 73 is the peripheral portion of one side of the four peripheral portions of the first excitation electrode 14a extending along the X-axis direction on the positive Z'-axis side in a plan view. Peripheral portion 74 is the peripheral portion of one side of the four peripheral portions of the first excitation electrode 14a extending along the X-axis direction on the negative Z'-axis side in a plan view. Peripheral portions 71, 72, 73, and 74 are examples of first peripheral portions.

[0156] Figure 3As shown, in a plan view, the second excitation electrode 14b has peripheral portions 81, 82, 83, and 84. Peripheral portion 81 is the peripheral portion of one side of the second excitation electrode 14b extending in the Z'-axis direction on the positive X-axis side in a plan view. Peripheral portion 82 is the peripheral portion of one side of the second excitation electrode 14b extending in the Z'-axis direction on the negative X-axis side in a plan view. Peripheral portion 83 is the peripheral portion of one side of the second excitation electrode 14b extending in the X-axis direction on the positive Z'-axis side in a plan view. Peripheral portion 84 is the peripheral portion of one side of the second excitation electrode 14b extending in the X-axis direction on the negative Z'-axis side in a plan view. Peripheral portions 81, 82, 83, and 84 are examples of first peripheral portions.

[0157] In a plan view, second excitation electrode 14b is smaller than quartz plate 11, and outer peripheral portions 81, 82, 83, and 84 of second excitation electrode 14b are located inward of outer peripheral portions 91, 92, 93, and 94 of quartz plate 11. First excitation electrode 14a is smaller than second excitation electrode 14b, and outer peripheral portions 71, 72, 73, and 74 of first excitation electrode 14a are located inward of outer peripheral portions 81, 82, 83, and 84 of second excitation electrode 14b. In a plan view, outer peripheral portions 71, 81, and 91 are arranged parallel to each other; outer peripheral portions 72, 82, and 92 are arranged parallel to each other; outer peripheral portions 73, 83, and 93 are arranged parallel to each other; and outer peripheral portions 74, 84, and 94 are arranged parallel to each other.

[0158] like Figure 3 As shown, in a plan view, the dimension of the quartz plate 11 along the X-axis direction is represented by length Lq, and the dimension of the quartz plate 11 along the Z'-axis direction is represented by length Wq. The dimension of the first excitation electrode 14a along the X-axis direction is represented by length Le, and the dimension of the first excitation electrode 14a along the Z'-axis direction is represented by length We. The dimension of the second excitation electrode 14b along the X-axis direction is represented by length Le2, and the dimension of the second excitation electrode 14b along the Z'-axis direction is represented by length We2.

[0159] Length Lq is the distance between outer periphery 91 and outer periphery 92 at a predetermined position along the X-axis direction, for example, the distance between outer periphery 91 and outer periphery 92 in the X-axis direction. This predetermined position is, for example, a straight line extending through the center of quartz plate 11 when viewed from above and in the X-axis direction. Length Lq can also be determined as the average or maximum value of the distances between outer periphery 91 and outer periphery 92 in the X-axis direction. Length Wq is the distance between outer periphery 93 and outer periphery 94 at a predetermined position along the Z'-axis direction, for example, the distance between outer periphery 93 and outer periphery 94 in the Z'-axis direction. This predetermined position is, for example, a straight line extending through the center of quartz plate 11 when viewed from above and in the Z'-axis direction. Length Wq can also be determined as the average or maximum value of the distances between outer periphery 93 and outer periphery 94 in the Z'-axis direction.

[0160] Similarly, the length Le is the distance along the X-axis between the outer peripheral portion 71 and the outer peripheral portion 72 at a predetermined position (e.g., on a straight line passing through the center of the first excitation electrode 14a and extending in the X-axis direction), and is determined, for example, as the distance between the outer peripheral portion 71 and the outer peripheral portion 72 in the X-axis direction. The length Le can also be determined as the average or maximum value of the distances between the outer peripheral portion 71 and the outer peripheral portion 72 in the X-axis direction. The length We is the distance along the Z'-axis between the outer peripheral portion 73 and the outer peripheral portion 74 at a predetermined position (e.g., on a straight line passing through the center of the first excitation electrode 14a and extending in the Z'-axis direction), and is determined, for example, as the distance between the outer peripheral portion 73 and the outer peripheral portion 74 in the Z'-axis direction. The length We can also be determined as the average or maximum value of the distances between the outer peripheral portion 73 and the outer peripheral portion 74 in the Z'-axis direction. The length Le2 is the distance along the X-axis between the outer peripheral portion 81 and the outer peripheral portion 82 at a predetermined position (e.g., on a straight line passing through the center of the second excitation electrode 14b and extending in the X-axis direction). For example, it is determined as the distance between the outer peripheral portion 81 and the outer peripheral portion 82 in the X-axis direction. The length Le2 can also be determined as the average or maximum value of the distances between the outer peripheral portion 81 and the outer peripheral portion 82 in the X-axis direction. The length We2 is the distance along the Z'-axis between the outer peripheral portion 83 and the outer peripheral portion 84 at a predetermined position (e.g., on a straight line passing through the center of the second excitation electrode 14b and extending in the Z'-axis direction). For example, it is determined as the distance between the outer peripheral portion 83 and the outer peripheral portion 84 in the Z'-axis direction. The length We2 can also be determined as the average or maximum value of the distances between the outer peripheral portion 83 and the outer peripheral portion 84 in the Z'-axis direction.

[0161] The planar shape of the quartz plate 11 is a rectangle with its longitudinal direction in the X-axis direction, so the length Lq is greater than the length Wq (Wq < Lq). The planar shapes of the first excitation electrode 14a and the second excitation electrode 14b are also identical rectangles, so the length Le is greater than the length We (We < Le), and the length Le2 is greater than the length We2 (We2 < Le2). The outer peripheries 81, 82, 83, and 84 of the second excitation electrode 14b are all located inward of the outer peripheries 91, 92, 93, and 94 of the quartz plate 11. Therefore, the length Lq is greater than the length Le2 (Le2 < Lq), and the length Wq is greater than the length We2 (We2 < Wq). The outer peripheries 71, 72, 73, and 74 of the first excitation electrode 14a are all located inward of the outer peripheries 81, 82, 83, and 84 of the second excitation electrode 14b. Therefore, the length Le2 is greater than the length Le (Le < Le2), and the length We2 is greater than the length We (We < We2). In summary, the relationships of Le<Le2<Lq, and We<We2<Wq hold.

[0162] like Figure 4 As shown, the thickness of the quartz plate 11 is denoted as Tq, the thickness of the first excitation electrode 14 a is denoted as Te, and the thickness of the second excitation electrode 14 b is denoted as Te2.

[0163] Thickness Tq is the distance between upper surface 11A and lower surface 11B along the Y'-axis at a predetermined location, for example, the distance between upper surface 11A and lower surface 11B in the Y'-axis direction. This predetermined location is, for example, a straight line extending in the Y'-axis direction through the center of excitation region 19. Thickness Tq can also be determined as the average or maximum value of the distance between upper surface 11A and lower surface 11B in the Y'-axis direction in excitation region 19.

[0164] Similarly, thickness Te is the distance along the Y'-axis between the upper and lower surfaces of first excitation electrode 14a at a predetermined position (e.g., on a straight line passing through the center of excitation region 19 and extending in the Y'-axis direction). For example, it can be determined as the distance in the Y'-axis between the upper and lower surfaces of first excitation electrode 14a. Thickness Te can also be determined as the average or maximum value of the distances in the Y'-axis between the upper and lower surfaces of first excitation electrode 14a in excitation region 19. Thickness Te2 is the distance along the Y'-axis between the upper and lower surfaces of second excitation electrode 14b at a predetermined position (e.g., on a straight line passing through the center of excitation region 19 and extending in the Y'-axis direction). For example, it can be determined as the distance in the Y'-axis between the upper and lower surfaces of second excitation electrode 14b. Thickness Te2 can also be determined as the average or maximum value of the distances in the Y'-axis between the upper and lower surfaces of second excitation electrode 14b in excitation region 19.

[0165] The thickness Tq and the thickness Te2 are substantially constant throughout the high-velocity region 17 and the low-velocity region 18. The thickness Te is substantially constant throughout the high-velocity region 17 and the low-velocity region 18 except for portions where a plurality of holes H and an opening h1 described later are formed.

[0166] Thickness Tq is greater than thickness Te and thickness Te2, and thickness Te is equal to thickness Te2 (Te=Te2<Tq). In addition, thickness Tq is greater than the sum of thickness Te and thickness Te2 (Te+Te2<Tq). However, the magnitude relationship between thickness Te and thickness Te2 is not limited to the above, and the relationship of Te<Te2 or Te2<Te may also hold.

[0167] Furthermore, the thickness of the first extraction electrode 15a is equal to the thickness Te of the first excitation electrode 14a. In other words, the first electrode has a uniform thickness Te. Furthermore, the thickness of the second extraction electrode 15b is equal to the thickness Te2 of the second excitation electrode 14b. In other words, the second electrode has a uniform thickness Te2.

[0168] like Figure 3 as well as Figure 4 As shown, a plurality of holes H are provided in the first excitation electrode 14a in the high-sonic velocity region 17. Therefore, the average mass of the crystal resonator element 10 in the high-sonic velocity region 17 is smaller than that in the low-sonic velocity region 18. This reduced average mass results in a higher sound velocity in the high-sonic velocity region 17 than in the low-sonic velocity region 18. By including both the high-sonic velocity region 17 and the low-sonic velocity region 18 in the excitation region 19, the electromechanical coupling coefficient k (%) of the spurious mode can be suppressed, thereby improving the electromechanical coupling coefficient k (%) of the main mode.

[0169] like Figure 4 As shown, the hole H is a through-hole that penetrates the first excitation electrode 14a in the Y'-axis direction. However, the hole is not limited to a through-hole and may also be a bottomed groove that opens in the Y'-axis direction. Furthermore, the hole may be provided in the second excitation electrode, or in both the first and second excitation electrodes.

[0170] like Figure 3 As shown, the planar shape of the hole H is a square having a pair of sides extending in the Z'-axis direction and a pair of sides extending in the X-axis direction. Therefore, when the dimension of the hole H in the X-axis direction is Hx and the dimension in the Z'-axis direction is Hz, Hx = Hz.

[0171] Furthermore, the planar shape of the hole is not limited to a square having sides extending along the X-axis and the Z'-axis. For example, the planar shape of the hole may be a rectangle with Hx < Hz or Hz < Hx, or a rectangle having sides extending in a direction intersecting the X-axis and the Z'-axis. The planar shape of the hole may also be a polygon, a circle, an ellipse, or a combination thereof.

[0172] like Figure 3 As shown, multiple holes H are arranged in a matrix along the X-axis and Z'-axis directions. The arrangement period of the multiple holes H in the Z'-axis direction, i.e., the distance between the ends of two adjacent holes H in the Z'-axis direction on the negative Z'-axis side, is denoted as PHz. The arrangement period of the holes H in the X-axis direction, i.e., the distance between the ends of two adjacent holes H in the X-axis direction on the negative X-axis side, is denoted as PHx. The multiple holes H are arranged at equal intervals in both the Z'-axis and X-axis directions. In other words, PHz = PHx.

[0173] Furthermore, the arrangement period of the plurality of holes H is not limited to the above, and may be PHz < PHx, or PHx < PHz. Furthermore, the arrangement of the plurality of holes H is not limited to the above. The plurality of holes H may be arranged along a direction intersecting the Z'-axis direction and the X-axis direction. The plurality of holes H may be arranged in a staggered pattern or in an irregular pattern.

[0174] When the hole H is a through-hole, in order for the interior of the hole H in the high-sonic velocity region 17 to function as part of the first excitation electrode 14a, it is preferable that, when the thickness of the quartz plate 11 is Tq and the inner diameter of the hole H is Hr, the relationship 0 < Hr / Tq ≤ 2.0 holds. In this case, the reduction rate of electrostatic capacitance caused by the hole H is suppressed to less than 1%, allowing the interior of the hole H to fully function as an excitation electrode. Furthermore, it is more preferable that the relationship 0 < Hr / Tq ≤ 1.5 holds, and even more preferably, 0 < Hr / Tq ≤ 1.0 holds. If 0 < Hr / Tq ≤ 1.5, the reduction rate of electrostatic capacitance can be suppressed to less than 0.5%, and if 0 < Hr / Tq ≤ 1.0, the reduction rate of electrostatic capacitance can be suppressed to less than 0.1%. Furthermore, to form the hole H with sufficient processing accuracy, it is preferable that 0.1 ≤ Hr / Tq, and more preferably 0.5 ≤ Hr / Tq.

[0175] In addition, the inner diameter Hr of the hole H is the length of one side when the shape of the hole H is a square (Hr=Hx=Hz), and is the length of one side when the shape of the hole H is converted into a square with a constant area when the shape of the hole H is other than a square.

[0176] like Figure 3As shown, the first extraction electrode 15a is connected to the corner formed by the outer periphery 71 and the outer periphery 73 of the first excitation electrode 14a. Furthermore, the first extraction electrode 15a is connected only to the outer periphery 71 of the outer peripheries 71, 72, 73, and 74 of the first excitation electrode 14a. Therefore, the boundary B between the first excitation electrode 14a and the first extraction electrode 15a is located on an extension of the outer periphery 71. The connection between the first excitation electrode 14a and the first extraction electrode 15a overlaps with the second excitation electrode 14b.

[0177] The connection position of the first extraction electrode to the first excitation electrode is not limited to the above. For example, the first extraction electrode may be connected to both the outer peripheral portion 71 and the outer peripheral portion 73 at a corner of the first excitation electrode. The first extraction electrode may also be connected to the center of the outer peripheral portion 71 of the first excitation electrode in the Z'-axis direction.

[0178] like Figure 3 As shown, the second extraction electrode 15b is connected to the corner formed by the outer periphery 81 and the outer periphery 84 of the second excitation electrode 14b. The second extraction electrode 15b is connected only to the outer periphery 81 of the outer peripheries 81, 82, 83, and 84 of the second excitation electrode 14b.

[0179] Furthermore, the connection position of the second extraction electrode to the second excitation electrode is not limited to the above. For example, the second extraction electrode may be connected to both the outer peripheral portion 81 and the outer peripheral portion 84 at a corner of the second excitation electrode. The second extraction electrode may also be connected to the center of the outer peripheral portion 81 of the second excitation electrode in the Z'-axis direction. However, from the perspective of suppressing the generation of stray vibrations between the first and second extraction electrodes, it is preferred that the first extraction electrode and the second extraction electrode do not overlap when viewed from above, and more preferably, they are as far apart as possible.

[0180] like Figure 3 As shown, an opening h1 is provided in the first electrode in a region overlapping the connection between the first excitation electrode 14a and the first extraction electrode 15a. In other words, the plurality of holes H and the opening h1 are provided on the same side of the first electrode as the quartz resonator element 10. The opening h1 overlaps with the second electrode. The opening h1 is provided on the first extraction electrode 15a side of the boundary B between the first excitation electrode 14a and the first extraction electrode 15a. The opening h1 is provided within a distance from the boundary B that is no more than four times the thickness Tq of the quartz plate 11. The opening h1 is a through-hole that penetrates the first excitation electrode 14a in the Y'-axis direction. The opening h1 is slit-shaped, with long sides extending parallel to the boundary B. The planar shape of the opening h1 is a rectangle with a pair of long sides extending in the Z'-axis direction and a pair of short sides extending in the X-axis direction. Furthermore, the opening h1 is slit-shaped, opening on the negative Z'-axis side of the first extraction electrode 15a.

[0181] The location of the opening is not particularly limited, as long as it overlaps the connection between the first excitation electrode 14a and the first extraction electrode 15a and is substantially within a distance of four times or less of the thickness Tq of the quartz plate 11 from the boundary B between the first excitation electrode 14a and the first extraction electrode 15a. For example, the opening may be located on the first excitation electrode 14a side of the boundary B, or may be located across the boundary B between the first extraction electrode 15a and the first excitation electrode 14a. If the opening is located in the first extraction electrode 15a, it may be in the form of a slit opening on the positive Z'-axis side of the first extraction electrode 15a. The opening may also be in the form of an island surrounded by the first electrode in the first electrode. The opening may also be located in the second electrode or in both the first and second electrodes. The longitudinal direction of the slit-shaped opening is, for example, parallel to the boundary B, but may also be in a direction intersecting the boundary B as long as it is along the boundary B. Here, the direction along the boundary B refers to a direction in which the absolute value of the angle formed with the boundary B is 45° or less. For example, it may be a direction in which the absolute value of the angle formed with the boundary B is 30° or less, or it may be a direction in which the absolute value of the angle formed with the boundary B is 20° or less. When the longitudinal direction of the slit-shaped opening is along the boundary B, the angle formed between the longitudinal direction of the slit-shaped opening and the boundary B is, for example, not less than -45° and not more than 45°.

[0182] The phrase "the openings are substantially located within a range of four times or less the thickness Tq of the quartz plate 11 from the boundary B between the first excitation electrode 14a and the first extraction electrode 15a" means that at least 90% of the openings are located within a range of four times or less the thickness Tq of the quartz plate 11 from the boundary B between the first excitation electrode 14a and the first extraction electrode 15a. Furthermore, the openings are preferably substantially located within a range of 3.5 times or less the thickness Tq of the quartz plate 11 from the boundary B, and more preferably within a range of three times or less the thickness Tq of the quartz plate 11 from the boundary B. Furthermore, it is preferred that all of the openings be located within a range of four times or less the thickness Tq of the quartz plate 11 from the boundary B, more preferably within a range of 3.5 times or less the thickness Tq of the quartz plate 11 from the boundary B, and even more preferably within a range of three times or less the thickness Tq of the quartz plate 11 from the boundary B.

[0183] The number of openings is not limited to one. For example, if the opening is slit-shaped with long sides extending in a direction along boundary B, multiple slit-shaped openings may be arranged in a direction intersecting boundary B. Alternatively, the opening may be arranged in a row along boundary B. Furthermore, multiple row-shaped openings may be arranged in a direction intersecting boundary B, as long as they are along boundary B. In this case, the angle formed between the direction in which the row-shaped openings are arranged and boundary B is, for example, not less than -45° and not more than 45°.

[0184] Furthermore, the longitudinal direction of the slit-shaped openings and the direction in which the row-shaped openings are arranged may be along a direction perpendicular to the boundary B (hereinafter referred to as "a direction perpendicular to the boundary B"). Here, the direction perpendicular to the boundary B refers to a direction in which the absolute value of the angle formed with the boundary B is greater than 45° and less than 135°. For example, the direction in which the absolute value of the angle formed with the boundary B is greater than 60° and less than 120°, or the direction in which the absolute value of the angle formed with the boundary B is greater than 70° and less than 110°.

[0185] like Figure 3 As shown, the dimension of the opening h1 along the X-axis direction is defined as length Lh1, and the dimension of the opening h1 along the Z'-axis direction is defined as length Wh1. The dimension of the portion of the first extraction electrode 15a that is narrowed by the opening h1 (hereinafter referred to as the "narrow portion") along the X-axis direction is defined as length Ls, and the dimension of the narrow portion along the Z'-axis direction is defined as length Ws.

[0186] The length Lh1 is the distance between the long sides of the opening h1 at a specified position along the X-axis direction, for example, it is determined as the distance between the long sides of the opening h1 in the X-axis direction. The specified position is, for example, a straight line passing through the center of the opening h1 when viewed from above and extending in the X-axis direction. The length Lh1 can also be determined as the average value or maximum value of the distances between the long sides of the opening h1 in the X-axis direction. The length Wh1 is the distance between the short sides of the opening h1 at a specified position along the Z'-axis direction, for example, it is determined as the distance between the short sides of the opening h1 in the Z'-axis direction. The specified position is, for example, a straight line passing through the center of the opening h1 when viewed from above and extending in the Z'-axis direction. The length Wh1 can also be determined as the average value or maximum value of the distances between the short sides of the opening h1 in the Z'-axis direction.

[0187] The length Ls is determined in the same manner as the length Lh1. The length Ws is the distance along the Z'-axis between the end of the narrow portion on the positive Z'-axis side and the end on the negative Z'-axis side at a specified position, for example, it is determined as the distance in the Z'-axis between the end of the narrow portion on the positive Z'-axis side and the end on the negative Z'-axis side. The specified position is, for example, a straight line passing through the center of the narrow portion when viewed from above and extending in the Z'-axis direction. The length Ws can also be determined as the average value or minimum value of the distance in the Z'-axis between the end of the narrow portion on the positive Z'-axis side and the end on the negative Z'-axis side. The length Ws can also be calculated by subtracting the length Wh1 from the length Wc. In addition, when the opening portion is provided in the central portion of the first lead-out electrode 15a in the Z'-axis direction, and a narrow path portion is formed on both sides of the opening portion on the positive direction side of the Z'-axis and the negative direction side of the Z'-axis, the length Ws is determined as the sum of the dimension of the narrow path portion on the positive direction side of the Z'-axis in the Z'-axis direction and the dimension of the narrow path portion on the negative direction side of the Z'-axis in the Z'-axis direction.

[0188] The length Wc is the distance along the Z'-axis between the ends of the first extraction electrode 15a on the positive Z'-axis side and the ends on the negative Z'-axis side at a predetermined position. For example, it can be determined as the distance in the Z'-axis between the ends of the first extraction electrode 15a on the positive Z'-axis side and the ends on the negative Z'-axis side. For example, the predetermined position is a straight line extending in the Z'-axis direction, equidistant from the second excitation electrode 14b and the first connection electrode 16a in the X-axis direction when viewed from above. The length Wc can also be determined as the average or maximum value of the distances in the Z'-axis between the ends of the first extraction electrode 15a on the positive Z'-axis side and the ends on the negative Z'-axis side. The length Wc corresponds to the length of the first extraction electrode 15a in a direction parallel to the boundary B.

[0189] The length Wh1 is greater than the length Lh1 (Lh1 < Wh1). The length Lh1 is equal to the length Ls (Lh1 = Ls). The length Wh1 is preferably equal to or greater than the length Ws (Ws ≤ Wh1). The length Wh1 is preferably greater than or equal to 50% and less than or equal to 90% of the length Wc (Wc × 0.50 ≤ Wh1 ≤ Wc × 0.90). When a plurality of openings are provided along the boundary B, the total length of the plurality of openings in the direction along the boundary B is preferably greater than or equal to 50% and less than or equal to 90% of the length Wc.

[0190] Preferably, the relationship of 2<Lh1 / Tq≤Wh1 / Tq holds, preferably the relationship of 2.5≤Lh1 / Tq≤Wh1 / Tq holds, more preferably the relationship of 3≤Lh1 / Tq≤Wh1 / Tq holds, more preferably the relationship of 3.5≤Lh1 / Tq≤Wh1 / Tq holds, and further preferably the relationship of 4≤Lh1 / Tq≤Wh1 / Tq holds.

[0191] Next, refer to Figures 5 to 13 , the simulation results based on the first embodiment are described.

[0192] Figures 5 to 7 It is a diagram showing the vibration distribution of the crystal resonator element according to the first embodiment. Figure 5 As simulation results based on the first embodiment, the vibration distribution of the S0 mode, which is the main mode, is shown. Figure 6 As simulation results based on the first embodiment, vibration distribution of a mode (hereinafter referred to as “A0Z mode”) in which vibrations with opposite phases are arranged in the Z′-axis direction in the A0 mode, which is a spurious mode, is shown. Figure 7 The vibration distribution of a mode in which vibrations of opposite phases are arranged in the X-axis direction in the A0 mode, which is a spurious mode (hereinafter referred to as the "A0X mode") is shown as a simulation result based on the first embodiment. Figures 5 to 7 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0193] The simulation conditions for the vibration distribution according to the first embodiment are as follows: Under the simulation conditions, the center of the first excitation electrode 14 a overlaps with the center of the second excitation electrode 14 b in a plan view.

[0194] Tq=1.52μm

[0195] Te=Te2=0.08μm

[0196] Lq=160μm

[0197] Wq=120μm

[0198] Le=100μm

[0199] We=80μm

[0200] Le2=120μm

[0201] We2=100μm

[0202] Wc=20μm

[0203] Hx=Hz=1.5μm

[0204] PHx=PHz=3μm

[0205] Number of H = 8 × 8

[0206] Ls=5μm

[0207] Ws=5μm

[0208] like Figure 5 As shown, the electromechanical coupling coefficient k of the S0 mode in the first embodiment (hereinafter referred to as "k_S0") is 7.37%, and the frequency Fr of the S0 mode (hereinafter referred to as "Fr_S0") is 985.14 MHz. Figure 6 As shown, the electromechanical coupling coefficient k of the A0Z mode in the first embodiment (hereinafter referred to as "k_A0Z") is 0.04%, and the frequency Fr of the A0Z mode (hereinafter referred to as "Fr_A0Z") is 985.64 MHz. Figure 7 As shown, the electromechanical coupling coefficient k (hereinafter referred to as “k_A0X”) of the A0X mode in the first embodiment is 0.00%, and the frequency Fr (hereinafter referred to as “Fr_A0X”) of the A0X mode is 985.67 MHz.

[0209] Figure 8 It is a top view of a crystal resonator element of a comparative example. Figures 9 to 11 It is a diagram showing the vibration distribution of a quartz crystal resonator element of a comparative example. Figure 9 The vibration distribution of the S0 mode is shown as a simulation result based on the comparative example. Figure 10 The vibration distribution of the A0Z mode is shown as a simulation result based on a comparative example. Figure 11 The vibration distribution of A0X mode is shown. Figures 9 to 11 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0210] like Figure 8 As shown, the crystal resonator element 100 of the comparative example is the same as the crystal resonator element 10 of the first embodiment except that the opening h1 is omitted. The simulation conditions for the comparative example are the same as those for the first embodiment except that Ls=0 and Ws=Wc.

[0211] like Figure 9 As shown, kS0 in the comparative example is 7.39% and FrS0 is 985.13MHz. Figure 10 As shown in FIG. 1 , k_A0Z in the comparative example is 0.37% and Fr_S0 is 985.61 MHz. Figure 11 As shown, in the comparative example, k_A0X is 0.12% and Fr_S0 is 985.67 MHz.

[0212] If the Figure 9 as well as Figure 5 In comparison, k_S0 is 7.39% when the opening h1 is not provided, and 7.37% when the opening h1 is provided. Therefore, the presence or absence of the opening h1 has little effect on k_S0. Figure 10 as well as Figure 6 By comparison, by providing the opening h1, k_A0Z is reduced from 0.37% to 0.04%. Figure 11 as well as Figure 7 In comparison, by providing the opening h1 , k_A0X is reduced from 0.12% to 0.00%.

[0213] like Figures 10 and 11 As shown in FIG. 1 , in the comparative example, the vibration distribution leaks from the excitation region to the first extraction electrode. As a result, the vibration intensity on the first extraction electrode side of the excitation region is stronger than the vibration intensity on the opposite side of the first extraction electrode, and the balance of the vibration distribution is disrupted. In contrast, Figures 6 to 8 As shown, in the first embodiment, vibration leakage to the first extraction electrode does not occur, and the balance of vibration distribution in the excitation region is improved.

[0214] The reason why the vibration distribution leaks out from the excitation region to the first extraction electrode in the comparative example is that the vibration excited between the first extraction electrode and the second excitation electrode is coupled with the vibration excited between the first excitation electrode and the second excitation electrode. In particular, the antisymmetric A0 mode is not excited in an ideal state because the positive and negative charges cancel each other out. However, if the balance of the vibration distribution is disrupted as in the comparative example, the amount that is not canceled out is emphasized. In the first embodiment, the opening h1 suppresses the coupling between the A0 mode in the excitation region and the vibration excited by the first extraction electrode. Therefore, the balance of the vibration distribution of the A0 mode in the excitation region is improved, and the vibration distribution of the A0 mode is brought closer to the ideal state. Therefore, the positive and negative charges in the A0 mode are canceled out, suppressing the increase in k_A0Z and k_A0X caused by the first extraction electrode.

[0215] Figure 12 as well as Figure 13 Graph showing simulation results based on the first embodiment. Figure 12 In the graph shown, the horizontal axis represents the length Ls [μm] of the narrow portion along the X-axis direction, and the vertical axis represents the electromechanical coupling coefficient k [%]. Figure 13 In the graph shown, the horizontal axis represents the length Ws [μm] of the narrow portion along the Z' axis, and the vertical axis represents the electromechanical coupling coefficient k [%). The simulation conditions are the same as those for the vibration distribution simulation based on the first embodiment, except that Ls and Ws are used as variables.

[0216] In addition, in the graph, not only k_A0X and k_A0Z are plotted, but also k_A0ZX is plotted. k_A0ZX is the electromechanical coupling coefficient k of the mode in which the vibrations in the Z'-axis direction and the Z-axis direction are arranged in opposite phases in the A0 mode, which is a spurious mode. k_A0ZX is Figure 12 as well as Figure 13Since the horizontal axis of the graph shown is small in all ranges, description of k_A0ZX is omitted.

[0217] like Figure 12 As shown, when the length Ls is 3 μm or greater, that is, when Tq×2 ≤ Ls, both k_A0X and k_A0Z become sufficiently small. To suppress increases in wiring resistance in narrow sections and the resulting decrease in Q value due to increased resonant resistance, the relationship Ls ≤ Ws / Rs is preferably established. Rs is the sheet resistance of the first extraction electrode. Based on the above, the relationship Tq×2 ≤ Ls ≤ Ws / Rs is preferably established. Furthermore, the relationship Tq×3 ≤ Ls ≤ Ws / Rs is more preferably established.

[0218] like Figure 13 As shown, the smaller the length Ws, the smaller both k_A0X and k_A0Z. When the length Ws is less than 16μm, that is, when Ws / We≤0.20, k_A0X becomes sufficiently small. When the length Ws is less than 12μm, that is, when Ws / We≤0.15, both k_A0X and k_A0Z become sufficiently small. From the viewpoint of suppressing the increase in wiring resistance of the narrow section, it is preferred that the relationship of 0.05≤Ws / We holds true. According to the above situation, it is preferred that the relationship of 0.05≤Ws / We≤0.20 holds true, and it is more preferred that the relationship of 0.05≤Ws / We≤0.15 holds true. In addition, it is more preferred that the relationship of 0.075≤Ws / We holds true, and it is still more preferred that the relationship of 0.10≤Ws / We holds true.

[0219] As described above, according to this embodiment, the crystal resonator element 10 includes a crystal plate 11, a first electrode comprising a first excitation electrode 14a and a first extraction electrode 15a provided on a first principal surface 11A of the crystal plate 11, and a second electrode comprising a second excitation electrode 14b and a second extraction electrode 15b provided on a second principal surface 11B of the crystal plate 11. In a plan view, a high-sonic velocity region 17 is provided in the central portion of an excitation region 19 where the first excitation electrode 14a and the second excitation electrode 14b overlap, and a low-sonic velocity region 18 is provided in the peripheral portion of the excitation region 19. A plurality of holes H are provided in the first excitation electrode 14a in the high-sonic velocity region 17 to increase the sound velocity. The outer peripheral portions 71 to 74 of the first excitation electrode 14a are provided inward of the outer peripheral portions 81 to 84 of the second excitation electrode 14b, and the connection portion between the first excitation electrode 14a and the first extraction electrode 15a overlaps with the second excitation electrode 14b. An opening h1 is provided at the connection portion between the first excitation electrode 14a and the first extraction electrode 15a. The opening h1 is provided substantially at a distance not greater than four times the thickness Tq of the quartz plate 11 from the boundary B between the first excitation electrode 14a and the first extraction electrode 15a.

[0220] This suppresses the coupling between the vibrations excited between first extraction electrode 15a and second excitation electrode 14b and the vibrations excited in excitation region 19, thus preventing any degradation in the balance of the vibration distribution in excitation region 19 caused by first extraction electrode 15a. This increases k_S0 and reduces k_A0Z and k_A0X, thereby improving vibration characteristics.

[0221] As one aspect of this embodiment, the length Wh1 of the opening h1 in the Z′-axis direction along the boundary B is not less than 50% and not more than 90% of the length Wc of the first extraction electrode 15a in the Z′-axis direction along the boundary B (0.50≤Wh1 / Wc≤0.90).

[0222] Therefore, by satisfying 0.50 ≤ Wh1 / Wc, coupling between the vibration excited between the first extraction electrode 15a and the second excitation electrode 14b and the vibration excited in the excitation region 19 can be effectively suppressed. By satisfying Wh1 / Wc ≤ 0.90, a decrease in the Q value due to an increase in resonant resistance caused by an increase in wiring resistance can be suppressed.

[0223] As one aspect of this embodiment, regarding the thickness Tq of the quartz plate 11 , the length Wh1 of the opening h1 in the Z′-axis direction along the boundary B, and the length Lh1 of the opening h1 in the X-axis direction intersecting the boundary B, the relationship 2<Lh1 / Tq≤Wh1 / Tq holds.

[0224] This can sufficiently suppress the electric field generated in the region overlapping the opening h1 . Therefore, the opening h1 can effectively suppress coupling between the vibration excited between the first extraction electrode 15 a and the second excitation electrode 14 b and the vibration excited in the excitation region 19 .

[0225] As one aspect of the present embodiment, the length Lh1 of the opening h1 in the X-axis direction intersecting the boundary B is three times or more the thickness Tq of the quartz plate 11 (3≦Lh1 / Tq).

[0226] According to this, the opening h1 can more effectively suppress coupling between the vibration excited between the first extraction electrode 15 a and the second excitation electrode 14 b and the vibration excited in the excitation region 19 .

[0227] As one aspect of this embodiment, for the difference Ws between the length Wc of the first extraction electrode 15a in the Z'-axis direction along the boundary B and the length Wh1 of the opening h1, and the length We of the first excitation electrode 14a in the Z'-axis direction along the boundary B, the relationship 0.05≤Ws / We≤0.15 holds.

[0228] Thus, by satisfying 0.05 ≤ Ws / We, the decrease in Q value caused by the increase in resonant resistance due to the increase in wiring resistance can be suppressed. By satisfying Ws / We ≤ 0.15, the coupling between the vibration excited between the first extraction electrode 15a and the second excitation electrode 14b and the vibration excited in the excitation region 19 can be effectively suppressed.

[0229] As one method of this embodiment, for the difference Ws between the length Wc of the first lead-out electrode 15a in the Z'-axis direction along the boundary B and the length Wh1 of the opening h1, the length Lh1 of the opening h1 in the X-axis direction intersecting the boundary B, and the sheet resistance Rs of the first lead-out electrode 15a, the relationship Ls≤Ws / Rs holds.

[0230] This can suppress a decrease in the Q value due to an increase in resonance resistance caused by an increase in wiring resistance.

[0231] Hereinafter, other embodiments will be described. In addition, structures that are identical or similar to the structures shown in the first embodiment will be given identical or similar reference numerals, and their descriptions will be omitted as appropriate. In addition, the same effects brought about by the same structures will not be mentioned in sequence.

[0232] <Second embodiment>

[0233] Next, refer to Figure 14 , the structure of the crystal vibration element 102 of the second embodiment is described. Figure 14 It is a plan view of the crystal resonator element according to the second embodiment.

[0234] The opening h1 is away from the boundary B. The dimension in the X-axis direction from the boundary B to the end of the opening h1 on the negative side of the X-axis is defined as the length Lx. The length Lx is the distance from the boundary B to the opening h1 in a direction intersecting the boundary B, for example, the distance in a direction perpendicular to the boundary B. The length Lx is the distance along the X-axis between the boundary B and the end of the opening h1 on the negative side of the X-axis at a predetermined position, for example, the distance in the X-axis direction between the boundary B and the end of the opening h1 on the negative side of the X-axis. The predetermined position is, for example, a straight line extending in the X-axis direction through the center of the opening h1 when viewed from above. The length Lx can also be determined as the average value or minimum value of the distances in the X-axis direction between the boundary B and the end of the opening h1 on the negative side of the X-axis.

[0235] Reference Figures 15 to 19 , the simulation results based on the second embodiment are described. Figures 15 to 18 In the graph shown, the horizontal axis represents the length Lx [μm] from the boundary B to the opening h1, and the vertical axis represents the electromechanical coupling coefficient k [%). Figure 19 In the graph shown, the horizontal axis represents the length Ls [μm] of the narrow portion along the X-axis, and the vertical axis represents the length Lx [μm] from boundary B to opening h1. The simulation conditions for the second embodiment are the same as those for the vibration distribution simulation for the first embodiment, except that Ls and Lx are variables.

[0236] Figure 15 This graph shows the relationship between length Lx and the electromechanical coupling coefficient k when Ls = 2μm. When the relationship -5.0μm ≤ Lx ≤ 1.0μm holds, k_A0Z is sufficiently small. When the relationship -3.0μm ≤ Lx ≤ 5.0μm holds, k_A0X is also sufficiently small. Therefore, when the relationship -3.0μm ≤ Lx ≤ 1.0μm holds, both k_A0X and k_A0Z are sufficiently small. When Lx = -1.0μm, both k_A0X and k_A0Z reach their minimum.

[0237] Figure 16 This graph shows the relationship between length Lx and the electromechanical coupling coefficient k when Ls = 3 μm. When the relationship -4.0 μm ≤ Lx ≤ 1.0 μm holds, k_A0Z is sufficiently small. When the relationship -2.0 μm ≤ Lx ≤ 5.0 μm holds, k_A0X is also sufficiently small. Therefore, when the relationship -2.0 μm ≤ Lx ≤ 1.0 μm holds, both k_A0X and k_A0Z are sufficiently small. When Lx = 0 μm, both k_A0X and k_A0Z reach their minimum.

[0238] Figure 17 This graph shows the relationship between length Lx and the electromechanical coupling coefficient k when Ls = 4μm. When the relationship -3.5μm ≤ Lx ≤ 1.5μm holds, k_A0Z is sufficiently small. When the relationship -2.0μm ≤ Lx ≤ 5.0μm holds, k_A0X is also sufficiently small. Therefore, when the relationship -2.0μm ≤ Lx ≤ 1.5μm holds, both k_A0X and k_A0Z are sufficiently small. When Lx = 0μm, both k_A0X and k_A0Z reach their minimum.

[0239] Figure 17 This graph shows the relationship between length Lx and the electromechanical coupling coefficient k when Ls = 5μm. When the relationship -4.0μm ≤ Lx ≤ 2.5μm holds, k_A0Z is sufficiently small. When the relationship -1.0μm ≤ Lx ≤ 5.0μm holds, k_A0X is also sufficiently small. Therefore, when the relationship -1.0μm ≤ Lx ≤ 2.5μm holds, both k_A0X and k_A0Z are sufficiently small. When Lx = 0μm, both k_A0X and k_A0Z reach their minimum.

[0240] Figure 18The upper limit, lower limit, and center value of Lx are plotted when both k_A0X and k_A0Z are sufficiently small. By fitting these plots, the conditional expression for both k_A0X and k_A0Z to be sufficiently small is obtained as shown below.

[0241] Lx=0.48×Ls-1.88±1.70

[0242] <Third embodiment>

[0243] Next, refer to Figure 20 , the structure of the crystal vibration element 103 of the third embodiment is described. Figure 20 It is a plan view of the crystal resonator element according to the third embodiment.

[0244] Two openings h11 and h12 are provided in the quartz crystal resonator element 103. The planar shapes of the openings h11 and h12 are both rectangular slits. The opening h11 is provided along the boundary B. The opening h12 is provided on the positive side of the X-axis of the opening h11. The long side direction of the opening h11 extends parallel to the long side direction of the opening h12. The length Ls of the opening h11 along the X-axis is the same as the length Ls of the opening h12 along the X-axis. The opening h11 is in the shape of a cutout that opens on the negative side of the Z' axis of the first extraction electrode 15a. The opening h12 is in the shape of a cutout that opens on the positive side of the Z' axis of the first extraction electrode 15a. Parts of the openings h11 and h12 are arranged in the X-axis direction.

[0245] Figures 21 to 23 It is a diagram showing the vibration distribution of the crystal resonator element according to the third embodiment. Figure 21 As simulation results based on the third embodiment, the vibration distribution of the S0 mode, which is the main mode, is shown. Figure 22 The vibration distribution of the A0Z mode is shown as a simulation result based on the third embodiment. Figure 23 The vibration distribution of the A0X mode is shown as a simulation result based on the third embodiment. Figures 21 to 23 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0246] like Figure 21 As shown in FIG. 1 , in an example of the third embodiment, k_S0 is 7.29% and Fr_S0 is 985.20 MHz. Figure 22 As shown in FIG. 1 , in an example of the third embodiment, k_A0Z is 0.18% and Fr_A0Z is 985.73 MHz. Figure 23 As shown, in an example of the third embodiment, k_A0X is 0.15% and Fr_A0X is 985.72 MHz.

[0247] Compared to the comparative example crystal resonator element 100 without an opening, in one example of the third embodiment, k_S0 increases, k_A0Z decreases, and k_A0X barely changes. Therefore, although the crystal resonator element 103 of the third embodiment is inferior to the crystal resonator element 10 of the first embodiment, the electromechanical coupling coefficient k is improved.

[0248] <Fourth embodiment>

[0249] Next, refer to Figure 24 , the structure of the crystal vibration element 104 of the fourth embodiment is described. Figure 24 It is a top view of the crystal resonator element according to the fourth embodiment.

[0250] The quartz crystal resonator element 104 has two openings h11 and h12. The openings h11 and h12 have the same rectangular slit-like planar shape and are of the same size. Opening h11 is located along boundary B. Opening h12 is located on the positive X-axis side of opening h11. The longitudinal direction of opening h11 extends parallel to the longitudinal direction of opening h12. Both openings h11 and h12 are slit-like, opening on the negative Z'-axis side of the first extraction electrode 15a.

[0251] Figures 25 to 27 It is a diagram showing the vibration distribution of the crystal resonator element according to the fourth embodiment. Figure 25 As simulation results based on the fourth embodiment, the vibration distribution of the S0 mode, which is the main mode, is shown. Figure 26 The vibration distribution of the A0Z mode is shown as a simulation result based on the fourth embodiment. Figure 27 The vibration distribution of the A0X mode is shown as a simulation result based on the fourth embodiment. Figures 25 to 27 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0252] like Figure 25 As shown, in an example of the fourth embodiment, k_S0 is 7.29% and Fr_S0 is 985.21 MHz. Figure 26 As shown in FIG. 1 , in an example of the fourth embodiment, k_A0Z is 0.03% and Fr_A0Z is 985.75 MHz. Figure 27 As shown, in an example of the fourth embodiment, k_A0X is 0.06% and Fr_A0X is 985.72 MHz.

[0253] Compared to the comparative example quartz crystal resonator element 100 without an opening, in one example of the fourth embodiment, k_S0 increases, while k_A0Z and k_A0X decrease. Therefore, in the quartz crystal resonator element 104 of the fourth embodiment, the electromechanical coupling coefficient k is improved compared to the quartz crystal resonator element 103 of the third embodiment. When two openings are provided, providing two openings on the same side of the positive or negative Z' axis is more effective in improving the electromechanical coupling coefficient k than providing two openings staggered from both sides of the positive and negative Z' axis.

[0254] <Fifth embodiment>

[0255] Next, refer to Figure 28 , the structure of the crystal vibration element 105 of the fifth embodiment is described. Figure 28 It is a top view of the crystal resonator element according to the fifth embodiment.

[0256] The quartz crystal resonator element 105 is provided with multiple openings h11. Each of the openings h11 has the same rectangular slit-like planar shape and the same dimensions. Each of the openings h11 is in the form of a slit, opening on the negative Z'-axis side of the first extraction electrode 15a. The openings h11 have long sides along the Z'-axis, which is aligned with the boundary B, and are arranged in the X-axis direction, which intersects the boundary B.

[0257] Reference Figure 29 , the simulation results based on the fifth embodiment are explained. Figure 29 Graph showing simulation results based on the fifth embodiment. Figure 29 In the graph shown, the horizontal axis represents the total length Ls of the multiple openings h11, Ls_total, and the vertical axis represents the electromechanical coupling coefficient k (k_A0Z) [%] in the A0Z mode. The simulation conditions for the fifth embodiment are the same as those for the first embodiment, except that Ws = 8 μm and Ls and the number of openings h11 are variables.

[0258] When Ls = 0.5 μm to 2.0 μm, within the range of 0 μm to 5.0 μm for the total length Ls, the greater the total length Ls, the smaller the electromechanical coupling coefficient k. From the perspective of reducing k_A0Z, 1.5 μm ≤ Ls_total is preferred, 3.0 μm ≤ Ls_total is more preferred, and 4.5 μm ≤ Ls_total is more preferred. In other words, the total length Ls, Ls_total, is preferably greater than or equal to the thickness Tq of the quartz plate 11, more preferably at least twice Tq, and even more preferably at least three times Tq. When the total length Ls, Ls_total, is greater than or equal to twice the thickness Tq of the quartz plate 11, k_A0Z becomes sufficiently small. When Ls = 1.5 μm and 2.0 μm, k_A0Z shows the same trend when there are multiple openings h11 as when there is only one opening h11. However, when Ls = 0.5 μm and 1.0 μm, k_A0Z is greater when there are multiple openings h11 than when there is only one opening h11. In other words, when there are multiple openings h11, the A0 mode suppression effect decreases when Ls < 1.5 μm. Therefore, when there are multiple openings h11, the relationship of 1.5 μm ≤ Ls is preferably satisfied.

[0259] <Sixth embodiment>

[0260] Next, refer to Figure 30 , the structure of the crystal resonator element 106 of the sixth embodiment is described. Figure 30 It is a plan view of the crystal resonator element according to the sixth embodiment.

[0261] The lengths of the first excitation electrode 14a and the second excitation electrode 14b along the Z'-axis of the quartz crystal resonator element 106 of the sixth embodiment are smaller than the lengths of the first excitation electrode 14a and the second excitation electrode 14b along the Z'-axis of the quartz crystal resonator element 101 of the first embodiment. In other words, the aspect ratio of the first excitation electrode 14a and the second excitation electrode 14b of the quartz crystal resonator element 106 of the sixth embodiment is larger than the aspect ratio of the first excitation electrode 14a and the second excitation electrode 14b of the quartz crystal resonator element 101 of the first embodiment.

[0262] Reference Figure 31 as well as Figure 32 , the simulation results based on the sixth embodiment are explained. Figure 31 as well as Figure 32 : is a graph showing the simulation results based on the sixth embodiment. Figure 31 In the graph shown, the horizontal axis represents the length Ls [μm] of the narrow portion along the X-axis direction, and the vertical axis represents the electromechanical coupling coefficient k [%]. Figure 32In the graph shown, the horizontal axis represents the length Ws [μm] of the narrow portion along the Z′-axis direction, and the vertical axis represents the electromechanical coupling coefficient k [%].

[0263] Figure 31 The simulation conditions of the graph shown are the same as those of the simulation of the vibration distribution according to the first embodiment, except that We=60 μm, Ws=6 μm, and Ls are variables. Figure 32 The simulation conditions of the graph shown are the same as those of the vibration distribution simulation based on the first embodiment, except that We=60 μm and Ws is a variable.

[0264] like Figure 31 As shown in FIG, when the length Ls is greater than 3 μm, that is, when Tq×2≤Ls, both k_A0X and k_A0Z become sufficiently small. Figure 32 As shown, when the length Ws is 9 μm or less, that is, when Ws / We ≤ 0.15, both k_A0X and k_A0Z become sufficiently small. In other words, as in the first and sixth embodiments, even if the length We of the first excitation electrode 14a varies and the aspect ratio of the first excitation electrode 14a varies, the conditions for the lengths Ls and Ws that provide a good electromechanical coupling coefficient k remain the same.

[0265] <Seventh embodiment>

[0266] Next, refer to Figure 33 as well as Figure 34 , the structure of the crystal vibration element 107 of the seventh embodiment is described. Figure 33 It is a top view of the crystal resonator element according to the seventh embodiment. Figure 34 It is an enlarged plan view of the connection portion in the seventh embodiment.

[0267] On the first extraction electrode 15a side of the boundary B between the first excitation electrode 14a and the first extraction electrode 15a, a row of openings h2 are provided, arranged along the boundary B. The openings h2 are arranged at equal intervals from the end of the first extraction electrode 15a on the positive Z' axis to the end on the negative Z' axis. The planar shape of the openings h2 is rectangular, with one pair of sides extending along the Z' axis and one pair of sides extending along the X axis. One side of the openings h2 overlaps the boundary B.

[0268] The dimension of the opening h2 along the X-axis direction is set to length Lh2. The length Lh2 is the length of the opening h2 along the direction in which the opening h2 is arranged, for example, it is determined as the length of the opening h2 in the direction parallel to the direction in which the opening h2 is arranged. The dimension of the opening h2 along the Z'-axis direction is set to length Wh2. The length Wh2 is the length of the opening h2 along the direction intersecting the direction in which the opening h2 is arranged, for example, it is determined as the length of the opening h2 in the direction orthogonal to the direction of the opening h2. The arrangement period of the opening h2 in the Z'-axis direction, that is, the distance between the ends of two adjacent openings h2 on the negative side of the Z'-axis in the Z'-axis direction is set to Wp. The arrangement period Wp is the arrangement period of the opening h2 along the direction in which the opening h2 is arranged, for example, it is determined as the arrangement period of the opening h2 in the direction in which the opening h2 is arranged.

[0269] Next, refer to Figures 35 to 39 , the simulation results based on the seventh embodiment are explained.

[0270] Figures 35 to 37 It is a diagram showing the vibration distribution of the crystal resonator element according to the seventh embodiment. Figure 35 The vibration distribution of the S0 mode is shown as a simulation result based on the seventh embodiment. Figure 36 The vibration distribution of the A0Z mode is shown as a simulation result based on the seventh embodiment. Figure 37 The vibration distribution of the A0X mode is shown as a simulation result based on the seventh embodiment. Figures 35 to 37 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0271] like Figure 35 As shown, in an example of the seventh embodiment, k_S0 is 7.37% and Fr_S0 is 985.13 MHz. Figure 36 As shown in FIG. 1 , in an example of the seventh embodiment, k_A0Z is 0.03% and Fr_A0Z is 985.62 MHz. Figure 37 As shown, in an example of the seventh embodiment, k_A0X is 0.01% and Fr_A0X is 985.66 MHz.

[0272] Figure 38 as well as Figure 39 : is a graph showing the simulation results based on the seventh embodiment. Figure 38 In the graph shown, the horizontal axis represents the length Lh2 [μm] of the opening h2 along the X-axis direction, and the vertical axis represents k_A0Z [%]. Figure 39In the graph shown, the horizontal axis represents the ratio of the length Lh2 of the opening h2 along the Z′ axis to the arrangement period Wp of the opening h2 (hereinafter referred to as the opening ratio) Wh2 / Wp, and the vertical axis represents k_A0Z[%].

[0273] Figure 38 The simulation conditions of the graph shown are the same as those of the vibration distribution simulation according to the first embodiment, except that the opening h2 is provided instead of the opening h1 , Wp=3 μm, and Lh2 and Wh2 are used as variables. Figure 39 The simulation conditions of the graph shown are the same as those of the vibration distribution simulation according to the first embodiment, except that openings h2 are provided instead of openings h1 , the number of openings h2 and Wp are used as variables, and Lh2 = Wh2 = 1.5 μm.

[0274] like Figure 38 As shown in Figure 2, the smaller the length Lh2, the smaller k_A0Z. When the length Lh2 is greater than 3 μm, that is, when Tq×2≤Lh2, k_A0Z becomes sufficiently small. Figure 39 As shown in the figure, the larger the opening ratio Wh2 / Wp, the smaller k_A0Z. When the opening ratio Wh2 / Wp is above 50% and below 90% (0.50≤Wh2 / Wp≤0.90), k_A0Z becomes sufficiently small. Specifically, when 0.50≤Wh2 / Wp≤0.90, k_A0Z<0.10. In order to further reduce k_A0Z, 0.60≤Wh2 / Wp is more preferred. In addition, from the perspective of suppressing the increase in wiring resistance, Wh2 / Wp≤0.90 is preferred, and Wh2 / Wp≤0.80 is more preferred.

[0275] <Eighth embodiment>

[0276] Next, refer to Figure 40 , the structure of the crystal vibration element 108 of the eighth embodiment is described. Figure 40 It is a top view of the crystal resonator element according to the eighth embodiment.

[0277] In the crystal resonator element 108 , the row of openings h2 is provided on the first excitation electrode 14 a side of the boundary B. The dimension in the X-axis direction from the boundary B to the end of the opening h2 on the negative side in the X-axis direction is defined as a distance Lx.

[0278] Next, refer to Figures 41 to 44 , the simulation results based on the eighth embodiment are explained.

[0279] Figure 41 : is a graph showing the simulation results based on the eighth embodiment. Figure 41In the graph shown, the horizontal axis represents the distance Lx [μm] from the boundary B to the end of the opening h2 on the negative side in the X-axis direction, and the vertical axis represents the electromechanical coupling coefficient k [%]. Figure 41 The simulation conditions of the graph shown are the same as those of the vibration distribution simulation according to the first embodiment, except that the opening h2 is provided instead of the opening h1 , Lh2 = Wh2 = 2 μm, and Lx is used as a variable.

[0280] The smaller Lx is, the greater the electromechanical coupling coefficient of the A0 mode. In other words, the closer the opening h2 is to the high-velocity region 17, the less effective the opening h2 is at suppressing the A0 mode. When the opening h2 is provided on the first excitation electrode 14a side, to fully suppress the A0 mode, a range of -5 μm ≤ Lx ≤ 0 μm is preferred.

[0281] Next, refer to Figures 42 to 44 , the simulation results based on the eighth embodiment are explained.

[0282] Figures 42 to 44 It is a diagram showing the vibration distribution of the crystal resonator element according to the eighth embodiment. Figure 42 The vibration distribution of the S0 mode is shown as a simulation result based on the eighth embodiment. Figure 43 The vibration distribution of the A0Z mode is shown as a simulation result based on the eighth embodiment. Figure 44 The vibration distribution of the A0X mode is shown as a simulation result based on the eighth embodiment. Figures 42 to 44 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0283] like Figure 42 As shown, in an example of the eighth embodiment, k_S0 is 7.36% and Fr_S0 is 985.63 MHz. Figure 43 As shown, in an example of the eighth embodiment, k_A0Z is 0.02% and Fr_A0Z is 985.63 MHz. Figure 44 As shown, in an example of the eighth embodiment, k_A0X is 0.01% and Fr_A0X is 985.67 MHz.

[0284] k_S0 in the example of the eighth embodiment is substantially the same as k_S0 in the comparative example. k_A0Z and Fr_A0X in the example of the eighth embodiment are smaller than k_A0Z and Fr_A0X in the comparative example.

[0285] <Ninth embodiment>

[0286] Next, refer to Figure 45, the structure of the crystal vibration element 109 of the ninth embodiment is described. Figure 45 It is a top view of the crystal resonator element according to the ninth embodiment.

[0287] In addition to the row of openings h21 located on the first excitation electrode 14a side of boundary B, the crystal resonator element 109 also includes row-shaped openings h22, h23, and h24. The openings h21 in the crystal resonator element 109 of the ninth embodiment have the same structure as the openings h2 provided in the crystal resonator element 108 of the eighth embodiment. The row of openings h21 is provided at a corner of the first excitation electrode 14a on the positive X-axis side and the positive Z'-axis side. The row of openings h22 is provided at a corner of the first excitation electrode 14a on the negative X-axis side and the negative Z'-axis side. The row of openings h23 is provided at a corner of the first excitation electrode 14a on the positive X-axis side and the negative Z'-axis side. The row of openings h24 is provided at a corner of the first excitation electrode 14a on the negative X-axis side and the positive Z'-axis side. The openings h22, h23, and h34 are arranged in a row in the Z'-axis direction. The openings h21 and h23 are located within a range of substantially four times the thickness Tq of the quartz plate 11 from the outer peripheral portion 71. The openings h22 and h24 are located within a range of substantially four times the thickness Tq of the quartz plate 11 from the outer peripheral portion 72.

[0288] The opening h21 is provided in the low-velocity region 18 on the side of the first extraction electrode 15a relative to the high-velocity region 17. The opening h22 is provided in the low-velocity region 18 on the opposite side of the first extraction electrode 15a across the high-velocity region 17. The openings h23 and h24 are provided at diagonal positions across the high-velocity region 17 in the low-velocity region 18. The opening h21 is an example of the first opening, the opening h22 is an example of the second opening, the opening h23 is an example of the third opening, and the opening h24 is an example of the fourth opening.

[0289] Openings h21 and h22 are arranged symmetrically with respect to the center point of the first excitation electrode 14a. Openings h21 and h22 are arranged symmetrically with respect to the center point of the first excitation electrode 14a. Openings h23 and h24 are arranged symmetrically with respect to the center point of the first excitation electrode 14a. Openings h23 and h24 are arranged symmetrically with respect to the center point of the first excitation electrode 14a.

[0290] The row-shaped openings h21 , h22 , h23 , and h24 are all provided in the first excitation electrode 14 a , but the present invention is not limited thereto. At least one of the row-shaped openings h21 , h22 , h23 , and h24 may be provided in the second excitation electrode 14 b .

[0291] Next, refer to Figures 46 to 48 , the simulation results based on the ninth embodiment are explained. Figures 46 to 48 It is a diagram showing the vibration distribution of the crystal resonator element according to the ninth embodiment. Figure 46 The vibration distribution of the S0 mode is shown as a simulation result based on the ninth embodiment. Figure 47 As simulation results based on the ninth embodiment, the vibration distribution of the A0Z mode is shown. Figure 48 The vibration distribution of the A0X mode is shown as a simulation result based on the ninth embodiment. Figures 46 to 48 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0292] like Figure 46 As shown, in an example of the ninth embodiment, k_S0 is 7.37% and Fr_S0 is 985.14 MHz. Figure 47 As shown in FIG. 1 , in an example of the ninth embodiment, k_A0Z is 0.07% and FrA0Z is 985.64 MHz. Figure 48 As shown, in an example of the ninth embodiment, k_A0X is 0.06% and Fr_A0X is 985.68 MHz.

[0293] k_S0 in the example of the ninth embodiment is substantially the same as k_S0 in the comparative example. k_A0Z and k_A0X in the example of the ninth embodiment are smaller than k_A0Z and k_A0X in the comparative example.

[0294] <Tenth embodiment>

[0295] Next, refer to Figure 49 , the structure of the crystal resonator element 110 according to the tenth embodiment will be described. Figure 49 It is a top view of the crystal resonator element according to the tenth embodiment.

[0296] A plurality of openings h21, h22, h23, and h24 are arranged in a matrix along the X-axis and the Z'-axis. Opening h21 is provided in the low-velocity region 18 on the side of the first extraction electrode 15a relative to the high-velocity region 17. Opening h22 is provided in the low-velocity region 18 on the opposite side of the first extraction electrode 15a across the high-velocity region 17. Openings h23 and h24 are provided diagonally across the high-velocity region 17 in the low-velocity region 18.

[0297] The number of openings h21 arranged in the Z'-axis direction increases as it approaches the positive X-axis direction. The number of openings h21 arranged in the X-axis direction increases as it approaches the positive Z'-axis direction. The openings h21 are provided in an area surrounded by an arc passing through the positive X-axis end and the positive Z'-axis end of the first excitation electrode 14a, and centered on the high-sonic velocity region 17.

[0298] The number of openings h22 arranged in the Z'-axis direction increases as the area moves toward the negative X-axis direction. The number of openings h22 arranged in the X-axis direction increases as the area moves toward the negative Z'-axis direction. The openings h22 are provided in an area surrounded by an arc passing through the negative X-axis end of the first excitation electrode 14a, the negative Z'-axis end of the first excitation electrode 14a, and the high-sonic velocity region 17 as its center.

[0299] The number of openings h23 arranged in the Z'-axis direction increases as the area moves toward the positive X-axis direction. The number of openings h23 arranged in the X-axis direction increases as the area moves toward the negative Z'-axis direction. The openings h23 are provided in an area surrounded by an arc passing through the positive X-axis end of the first excitation electrode 14a, the negative Z'-axis end of the first excitation electrode 14a, and the high-sonic velocity region 17 as its center.

[0300] The number of openings h24 arranged in the Z'-axis direction increases as it approaches the negative X-axis direction. The number of openings h24 arranged in the X-axis direction increases as it approaches the positive Z'-axis direction. The openings h24 are provided in an area surrounded by an arc passing through the negative X-axis end of the first excitation electrode 14a, the positive Z'-axis end of the first excitation electrode 14a, and the high-sonic velocity region 17 as its center.

[0301] Next, refer to Figures 50 to 52 , the simulation results based on the tenth embodiment are explained. Figures 50 to 52 It is a diagram showing the vibration distribution of the crystal resonator element according to the tenth embodiment. Figure 50 The vibration distribution of the S0 mode is shown as a simulation result based on the tenth embodiment. Figure 51As simulation results based on the tenth embodiment, the vibration distribution of the A0Z mode is shown. Figure 52 The vibration distribution of the A0X mode is shown as a simulation result based on the tenth embodiment. Figures 50 to 52 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0302] like Figure 50 As shown, in an example of the tenth embodiment, k_S0 is 7.25% and Fr_S0 is 985.20 MHz. Figure 51 As shown, in an example of the tenth embodiment, k_A0Z is 0.07% and Fr_A0Z is 985.71 MHz. Figure 52 As shown, in an example of the tenth embodiment, k_A0X is 0.01% and Fr_A0X is 985.75 MHz.

[0303] k_S0 in the example of the tenth embodiment is substantially the same as k_S0 in the comparative example. k_A0Z and k_A0X in the example of the tenth embodiment are smaller than k_A0Z and k_A0X in the comparative example.

[0304] <Eleventh embodiment>

[0305] Next, refer to Figure 53 , the structure of the crystal vibration element 111 of the eleventh embodiment is described. Figure 53 It is a top view of the crystal resonator element according to the eleventh embodiment.

[0306] In the quartz crystal resonator element 111, a matrix of openings h21 is provided in an area enclosed by an arc extending through the ends of the first excitation electrode 14a on the positive X-axis side, the positive Z'-axis side, and the high-sonic velocity region 17. The distance in the X-axis direction from the end of the opening h21 that is farthest from the boundary B on the negative X-axis side is defined as a distance Lx.

[0307] Next, refer to Figures 54 to 57 , the simulation results based on the eleventh embodiment are explained.

[0308] Figure 54 : is a graph showing the simulation results based on the eleventh embodiment. Figure 54 In the graph shown, the horizontal axis represents the distance Lx [μm] to the end position on the negative side of the X-axis of the opening provided farthest from the boundary B, and the vertical axis represents the electromechanical coupling coefficient k [%]. Figure 54The simulation conditions of the graph shown are the same as those of the vibration distribution simulation according to the first embodiment, except that the opening h21 is provided instead of the opening h1 , Lh2 = Wh2 = 2 μm, and Lx is used as a variable.

[0309] The smaller Lx is, the greater the electromechanical coupling coefficient of the A0 mode. That is, the closer the opening h21 is to the high-velocity region 17, the less effective the opening h2 is at suppressing the A0 mode. To suppress the A0 mode compared to the comparative example, a value of -5 μm ≤ Lx ≤ 0 μm is preferred.

[0310] Figures 55 to 57 It is a diagram showing the vibration distribution of a crystal resonator element of a comparative example with respect to the eleventh embodiment. Figure 55 The vibration distribution of the S0 mode is shown as a simulation result based on a comparative example with respect to the eleventh embodiment. Figure 56 As a simulation result based on a comparative example with respect to the eleventh embodiment, a vibration distribution in the A0Z mode is shown. Figure 57 The vibration distribution of the A0X mode is shown as a simulation result based on a comparative example with respect to the eleventh embodiment. Figures 55 to 57 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0311] like Figure 55 As shown in FIG. 1 , k_S0 is 7.23% and Fr_S0 is 985.24 MHz in the comparative example of the eleventh embodiment. Figure 56 As shown in FIG. 1 , k_A0Z is 0.41% and Fr_A0Z is 985.41 MHz in the comparative example of the eleventh embodiment. Figure 57 As shown, k_A0X is 0.16% and Fr_A0X is 985.73 MHz in the comparative example of the eleventh embodiment.

[0312] k_S0 in the comparative example relative to the eleventh embodiment is smaller than k_S0 in the case where no opening is provided. k_A0Z and k_A0X in the comparative example relative to the eleventh embodiment are larger than k_A0Z and k_A0X in the case where no opening is provided. The reason why the A0 mode in the comparative example relative to the eleventh embodiment is not suppressed compared to the case where no opening is provided is because in the comparative example relative to the eleventh embodiment, a maximum of six openings h21 are arranged in the X-axis direction, and Lx << -5μm. When the length Wh2 of the opening h21 along the X-axis direction is set to 2μm and the distance Wp between the ends of the two adjacent openings h2 on the negative side of the X-axis is set to 3μm, Lx = -18μm in the comparative example relative to the eleventh embodiment, which deviates significantly from the range of -5μm≤Lx≤0μm. As in Figure 54 As described in , if the relationship of −5 μm ≤ Lx ≤ 0 μm holds, even in this embodiment, the A0 mode can be suppressed compared to the case where no opening is provided.

[0313] <Twelfth embodiment>

[0314] Next, refer to Figure 58 , the structure of the crystal vibration element 112 of the twelfth embodiment is described. Figure 58 It is a top view of the crystal resonator element according to the twelfth embodiment.

[0315] Multiple openings h21, h22, h23, and h24 are arranged in an arc shape centered on the high-sonic velocity region 17. Multiple openings h21 are provided at corners of the first excitation electrode 14a on the positive X-axis side and the positive Z'-axis side. Multiple openings h22 are provided at corners of the first excitation electrode 14a on the negative X-axis side and the negative Z'-axis side. Multiple openings h23 are provided at corners of the first excitation electrode 14a on the positive X-axis side and the negative Z'-axis side. Multiple openings h24 are provided at corners of the first excitation electrode 14a on the negative X-axis side and the positive Z'-axis side.

[0316] The opening h21 is provided in the low-velocity region 18 on the side of the first extraction electrode 15a relative to the high-velocity region 17. The opening h22 is provided in the low-velocity region 18 on the opposite side of the first extraction electrode 15a across the high-velocity region 17. The openings h23 and h24 are provided at diagonally opposite corners of each other across the high-velocity region 17 in the low-velocity region 18.

[0317] Next, refer to Figures 59 to 61 , the simulation results based on the twelfth embodiment are explained. Figures 59 to 61 It is a diagram showing the vibration distribution of the crystal resonator element according to the twelfth embodiment. Figure 59 The vibration distribution of the S0 mode is shown as a simulation result based on the twelfth embodiment.

[0318] Figure 60 The vibration distribution of the A0Z mode is shown as a simulation result based on the twelfth embodiment.

[0319] Figure 61 The vibration distribution of the A0X mode is shown as a simulation result based on the twelfth embodiment. Figures 59 to 61 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0320] like Figure 59As shown, in an example of the twelfth embodiment, k_S0 is 7.17% and Fr_S0 is 985.33 MHz. Figure 60 As shown, in an example of the twelfth embodiment, k_A0Z is 0.02% and Fr_A0Z is 985.91 MHz. Figure 61 As shown, in an example of the twelfth embodiment, k_A0X is 0.07% and Fr_A0X is 985.88 MHz.

[0321] k_S0 in one example of the twelfth embodiment is slightly smaller than k_S0 in the comparative example. k_A0Z and k_A0X in one example of the twelfth embodiment are smaller than k_A0Z and k_A0X in the comparative example. Figure 59 As shown, k_S0 decreases because the vibration distribution does not extend across the entire surface of the first excitation electrode 14a, but rather vibrates strongly only within the region enclosed by the multiple openings h21, h22, h23, and h24. On the other hand, k_A0Z and k_A0X decrease, suppressing the A0 mode, because within the region enclosed by the multiple openings h21, h22, h23, and h24, vibrations of opposite phases are symmetrically distributed across the high-sonic velocity region 17, canceling out each other.

[0322] <Thirteenth embodiment>

[0323] Next, refer to Figure 62 , the structure of the crystal vibration element 113 of the thirteenth embodiment is described. Figure 62 It is a top view of a crystal resonator element according to a thirteenth embodiment.

[0324] The crystal resonator element 113 of the thirteenth embodiment differs from the crystal resonator element 112 of the twelfth embodiment in that the plurality of openings h22 , h23 , and h24 are omitted.

[0325] Next, refer to Figures 63 to 65 , the simulation results based on the thirteenth embodiment are explained. Figures 63 to 65 It is a diagram showing the vibration distribution of the crystal resonator element according to the thirteenth embodiment. Figure 63 The vibration distribution of the S0 mode is shown as a simulation result based on the thirteenth embodiment.

[0326] Figure 64 The vibration distribution of the A0Z mode is shown as a simulation result based on the thirteenth embodiment.

[0327] Figure 65 The vibration distribution of the A0X mode is shown as a simulation result based on the thirteenth embodiment. Figures 63 to 65In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0328] like Figure 63 As shown, in an example of the thirteenth embodiment, k_S0 is 7.32% and Fr_S0 is 985.16 MHz. Figure 64 As shown, in an example of the thirteenth embodiment, k_A0Z is 0.16% and Fr_A0Z is 985.65 MHz. Figure 65 As shown, in an example of the thirteenth embodiment, k_A0X is 0.45% and Fr_A0X is 985.71 MHz.

[0329] k_S0 in one example of the thirteenth embodiment is substantially the same as k_S0 in the comparative example. k_A0Z in one example of the thirteenth embodiment is smaller than k_A0Z in the comparative example. k_A0X in one example of the thirteenth embodiment is larger than k_A0X in the comparative example. Figure 64 As shown in FIG, k_A0Z becomes smaller because the positions of the plurality of openings h21 are far from the position of the vibration peak of the A0Z mode, and thus do not significantly affect the balance of the vibrations in the opposite phase. Figure 65 As shown, k_A0X increases because the positions of the plurality of openings h21 are close to the position of the vibration peak of the A0Z mode, and the plurality of openings h21 disrupt the balance of vibrations in opposite phases.

[0330] <Fourteenth embodiment>

[0331] Next, refer to Figure 66 , the structure of the crystal vibration element 114 of the fourteenth embodiment is described. Figure 66 It is a top view of the crystal resonator element according to the fourteenth embodiment.

[0332] The plurality of openings h21, h22, h23, and h24 are arranged in a straight line, arranged in a direction intersecting the Z'-axis direction. The row of openings h21 moves away from the end of the first excitation electrode 14a on the positive X-axis side as it moves toward the positive Z'-axis direction. The row of openings h21 moves away from the end of the first excitation electrode 14a on the negative X-axis side as it moves toward the negative Z'-axis direction. The row of openings h23 moves away from the end of the first excitation electrode 14a on the positive X-axis side as it moves toward the negative Z'-axis direction. The row of openings h24 moves away from the end of the first excitation electrode 14a on the negative X-axis side as it moves toward the positive Z'-axis direction. The angle formed between the arrangement direction of the plurality of openings h21, h22, h23, and h24 and the Z'-axis direction is, for example, 30°.

[0333] <Fifteenth embodiment>

[0334] Next, refer to Figure 67 , the structure of the crystal vibration element 115 of the fifteenth embodiment is described. Figure 67 It is a top view of the crystal resonator element according to the fifteenth embodiment.

[0335] The openings h21, h22, h23, and h24 are each slit-shaped openings extending in a straight line, each having a long side intersecting the Z'-axis direction. The slit-shaped opening h21 moves away from the end of the first excitation electrode 14a on the positive X-axis side as it approaches the positive Z'-axis direction. The slit-shaped opening h21 moves away from the end of the first excitation electrode 14a on the negative X-axis side as it approaches the negative Z'-axis direction. The slit-shaped opening h23 moves away from the end of the first excitation electrode 14a on the positive X-axis side as it approaches the negative Z'-axis direction. The slit-shaped opening h24 moves away from the end of the first excitation electrode 14a on the negative X-axis side as it approaches the positive Z'-axis direction. The angle formed between the long sides of each of the slit-shaped openings h21, h22, h23, and h24 and the Z'-axis direction is, for example, 30°.

[0336] Next, refer to Figure 68 , the influence of the length Ls in the fourteenth embodiment and the fifteenth embodiment is described. Figure 68 Graph showing simulation results based on the fourteenth and fifteenth embodiments. Figure 68 In the figure, the horizontal axis represents length Ls or length Lh2, and the vertical axis represents k_A0Z. Length Ls is the dimension of the slit-shaped opening along the short side of the opening, and length Lh2 is the dimension of the row-shaped opening along a direction intersecting the arrangement direction of the openings.

[0337] Figure 68 The simulation conditions for the graph shown are the same as those for the vibration distribution simulation based on the first embodiment, except for the conditions related to the openings. The arrangement direction of the columnar openings is tilted 30° from the Z'-axis direction. The longitudinal direction of the slit-shaped openings is tilted 30° from the Z'-axis direction. In the case of columnar openings, the arrangement period of the openings is Wp = 3 μm, the length of the openings in the arrangement direction is Wh2 = 2 μm, and the number of openings arranged in a column is seven. In the case of slit-shaped openings, the length of the openings in the longitudinal direction is Wh1 = 20 μm.

[0338] k_A0Z shows the same trend for the length Ls of the slit-shaped openings and the length Lh2 of the row-shaped openings. In the fourteenth embodiment, k_A0Z decreases as the length Ls increases, while in the fifteenth embodiment, k_A0Z decreases as the length Lh2 increases. When the length Ls or the length Lh2 is 3 μm or greater, that is, when Tq×2 ≤ Ls or Tq×2 ≤ Lh2, k_A0Z becomes sufficiently small.

[0339] Next, refer to Figure 69 , the influence of the angle of the opening portion in the fifteenth embodiment is explained. Figure 69 Graph showing simulation results based on the fifteenth embodiment. Figure 69 In the figure, the horizontal axis represents the length Ls and the vertical axis represents k_A0Z. The length Ls is the dimension of the opening along the short side. k_A0Z relative to the length Ls is plotted when the angle between the long side of the opening and the Z'-axis is 0°, 20°, 40°, 60°, 80°, and 90°. This angle is the angle obtained by rotating the long side of the opening h21 clockwise, that is, toward the negative X-axis side, with the end of the opening h21 on the negative Z'-axis side as the rotation center. This angle is the angle obtained by rotating the long side of the opening h22 clockwise, that is, toward the positive X-axis side, with the end of the opening h22 on the positive Z'-axis side as the rotation center. This angle is the angle obtained by rotating the long side of the opening h23 counterclockwise, that is, toward the negative X-axis side, with the end of the opening h23 on the positive Z'-axis side as the rotation center. This angle is obtained by rotating the longitudinal direction of the opening h24 counterclockwise, that is, toward the positive X-axis direction, with the end portion of the opening h24 on the negative Z′ axis side as the rotation center.

[0340] Figure 69 The simulation conditions of the graph shown are the same as those of the graph shown in FIG. 1 except that the angle between the long side of the opening and the Z' axis is used as a variable. Figure 68 The simulation conditions for the graphs shown are the same.

[0341] When the angle between the long side of the opening and the Z'-axis is between 0° and 90°, regardless of the angle, k_A0Z decreases as Ls increases. When the length Ls is 3 μm or greater, that is, when Tq×2 ≤ Ls, k_A0Z becomes sufficiently small. When the angle between the long side of the opening and the Z'-axis is 90°, k_A0Z also decreases when Tq×2 ≤ Ls. Therefore, even if the slit-shaped opening has its long side intersecting the boundary B, the A0 mode can be fully suppressed.

[0342] Next, refer to Figure 70 , the influence of the angle of the opening portion in the fourteenth embodiment is explained. Figure 70Graph showing simulation results based on the fourteenth embodiment. Figure 70 In the figure, the horizontal axis represents (Lh2 / Tq)×(Wh2 / Wp), and the vertical axis represents k_A0Z. Plot k_A0Z when the angles between the direction of the arrangement of the openings and the Z'-axis direction are 0°, 30°, 60°, and 90°. This angle is the angle obtained by rotating the arrangement direction of the multiple openings h21 clockwise, that is, toward the negative direction of the X-axis, with the opening closest to the negative direction of the Z'-axis among the multiple openings h21 as the rotation center. This angle is the angle obtained by rotating the arrangement direction of the multiple openings h22 clockwise, that is, toward the positive direction of the X-axis, with the opening closest to the positive direction of the Z'-axis among the multiple openings h22 as the rotation center. This angle is the angle obtained by rotating the arrangement direction of the multiple openings h23 counterclockwise, that is, toward the negative direction of the X-axis, with the opening closest to the positive direction of the Z'-axis among the multiple openings h23 as the rotation center. This angle is obtained by rotating the arrangement direction of the plurality of openings h24 counterclockwise, that is, toward the positive X-axis direction, with the opening closest to the negative Z′-axis side among the plurality of openings h24 as the rotation center.

[0343] Figure 70 The simulation conditions of the graph shown are the same as those of the graph shown in FIG. 1 except that the length Wh2 and the length Lh2 are variables and the angle between the direction in which the openings are arranged and the Z'-axis direction is a variable. Figure 68 The simulation conditions for the graphs shown are the same.

[0344] When the angle between the direction in which the openings are arranged and the Z'-axis is within the range of 0° to 90°, regardless of the angle, k_A0Z decreases as (Lh2 / Tq)×(Wh2 / Wp) increases. When 0.6≤(Lh2 / Tq)×(Wh2 / Wp), k_A0Z becomes sufficiently small. When the angle between the direction in which the openings are arranged and the Z'-axis is 90°, k_A0Z also decreases when 0.6≤(Lh2 / Tq)×(Wh2 / Wp). Therefore, even when the rows of openings are arranged in a direction intersecting boundary B, the A0 mode can be fully suppressed as long as the relationship 0.6≤(Lh2 / Tq)×(Wh2 / Wp) holds.

[0345] Next, refer to Figure 71 , the influence of the angle of the opening portion in the fourteenth embodiment is explained. Figure 71 : is a graph showing the simulation results based on the fourteenth embodiment. Figure 71 In FIG. 5 , the horizontal axis represents (Lh2 / Tq)×(Wh2 / Wp) and the vertical axis represents k_S0. k_S0 is plotted when the angles formed between the direction in which the openings are arranged and the Z′-axis direction are 0°, 30°, 60°, and 90°.

[0346] Figure 71The simulation conditions of the graph shown are the same as Figure 70 The simulation conditions for the graphs shown are the same.

[0347] When the angle between the direction in which the openings are arranged and the Z'-axis direction is within the range of 0° to 90°, regardless of the angle, the smaller (Lh2 / Tq)×(Wh2 / Wp), the larger k_S0. When (Lh2 / Tq)×(Wh2 / Wp)≤2.3, k_S0 in the fourteenth embodiment is larger than k_S0 in the comparative example. When the angle between the direction in which the openings are arranged and the Z'-axis direction is 90°, k_S0 also increases when (Lh2 / Tq)×(Wh2 / Wp)≤2.3. Therefore, even if the row-shaped openings are arranged in a direction intersecting the boundary B, as long as the relationship (Lh2 / Tq)×(Wh2 / Wp)≤2.3 holds, the A0 mode can be fully suppressed.

[0348] <Sixteenth embodiment>

[0349] Next, refer to Figure 72 , the structure of the crystal vibration element 116 of the sixteenth embodiment is described. Figure 72 It is a top view of the crystal resonator element according to the sixteenth embodiment.

[0350] The area of ​​the high-sonic velocity region 17 in the crystal resonator element 116 is larger than the area of ​​the high-sonic velocity region 17 in the crystal resonator element 10. The crystal resonator element 116 is provided with 16×12 holes H.

[0351] Next, refer to Figures 73 to 75 , the simulation results based on the sixteenth embodiment are explained. Figures 73 to 75 It is a diagram showing the vibration distribution of the crystal resonator element according to the sixteenth embodiment. Figure 73 The vibration distribution of the S0 mode is shown as a simulation result based on the sixteenth embodiment.

[0352] Figure 74 The vibration distribution of the A0Z mode is shown as a simulation result based on the sixteenth embodiment.

[0353] Figure 75 The vibration distribution of the A0X mode is shown as a simulation result based on the sixteenth embodiment. Figures 73 to 75 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0354] like Figure 73 As shown, in an example of the sixteenth embodiment, k_S0 is 7.25% and Fr_S0 is 986.39 MHz. Figure 74As shown, in an example of the sixteenth embodiment, k_A0Z is 0.75% and Fr_A0Z is 986.65 MHz. Figure 75 As shown, in an example of the sixteenth embodiment, k_A0X is 0.07% and Fr_A0X is 986.88 MHz.

[0355] Although not shown in the figure, in a comparative example in which the opening h1 is omitted from the sixteenth embodiment, k_S0 is 7.09%, Fr_S0 is 986.348 MHz, k_A0Z is 1.75%, Fr_A0Z is 986.616 MHz, k_A0X is 0.63%, and Fr_A0X is 986.844 MHz.

[0356] k_S0 in one example of the sixteenth embodiment is larger than k_S0 in the comparative example. k_A0Z in one example of the sixteenth embodiment is smaller than k_A0Z in the comparative example. k_A0X in one example of the sixteenth embodiment is smaller than k_A0X in the comparative example. According to the simulation results of the first and sixteenth embodiments, even if the area ratio of the high-velocity region 17 to the low-velocity region 18 is changed, the provision of the opening h1 can suppress the A0 mode and improve the vibration characteristics of the S0 mode.

[0357] <Seventeenth embodiment>

[0358] Next, refer to Figure 76 , the structure of the crystal vibration element 117 of the seventeenth embodiment is described. Figure 76 It is a top view of the crystal resonator element according to the seventeenth embodiment.

[0359] An opening h1' is provided in the second excitation electrode 14b in the region overlapping the connection between the first excitation electrode 14a and the first extraction electrode 15a. The planar shape, position, and dimensions of the opening h1' are identical to those of the opening h1 in the first embodiment. The opening h1' is provided on the second electrode opposite to the first electrode having the plurality of holes H.

[0360] Next, refer to Figures 77 to 79 , the simulation results based on the seventeenth embodiment are explained. Figures 77 to 79 It is a diagram showing the vibration distribution of the crystal resonator element according to the seventeenth embodiment. Figure 77 The vibration distribution of the S0 mode is shown as a simulation result based on the seventeenth embodiment.

[0361] Figure 78 As a simulation result based on the seventeenth embodiment, the vibration distribution of the A0Z mode is shown.

[0362] Figure 79 The vibration distribution of the A0X mode is shown as a simulation result based on the seventeenth embodiment. Figures 77 to 79 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0363] like Figure 77 As shown, in an example of the seventeenth embodiment, k_S0 is 7.37% and Fr_S0 is 985.14 MHz. Figure 78 As shown, in an example of the seventeenth embodiment, k_A0Z is 0.03% and Fr_A0Z is 985.63 MHz. Figure 79 As shown, in an example of the seventeenth embodiment, k_A0X is 0.03% and Fr_A0X is 985.67 MHz.

[0364] k_S0 in one example of the seventeenth embodiment is substantially the same as k_S0 in one example of the first embodiment. k_A0Z in one example of the seventeenth embodiment is substantially the same as k_A0Z in one example of the first embodiment. k_A0X in one example of the seventeenth embodiment is substantially the same as k_A0X in one example of the first embodiment. In other words, the same effect can be achieved regardless of whether the opening is provided in the first electrode or the second electrode.

[0365] <Eighteenth embodiment>

[0366] Next, refer to Figure 80 , the structure of the crystal vibration element 118 of the eighteenth embodiment is described. Figure 80 It is a top view of the crystal resonator element according to the eighteenth embodiment.

[0367] In the region overlapping the connection between the first excitation electrode 14a and the first extraction electrode 15a, an opening h1 is provided in the first excitation electrode 14a, and an opening h1' is provided in the second excitation electrode 14b. The planar shape, position, and dimensions of the opening h1 are substantially the same as those of the opening h1'.

[0368] Next, refer to Figures 81 to 83 , the simulation results based on the eighteenth embodiment are explained. Figures 81 to 83 It is a diagram showing the vibration distribution of the crystal resonator element according to the eighteenth embodiment. Figure 81 The vibration distribution of the S0 mode is shown as a simulation result based on the eighteenth embodiment. Figure 82 The vibration distribution of the A0Z mode is shown as a simulation result based on the eighteenth embodiment. Figure 83The vibration distribution of the A0X mode is shown as a simulation result based on the eighteenth embodiment. Figures 81 to 83 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0369] like Figure 81 As shown, in an example of the eighteenth embodiment, k_S0 is 7.36% and Fr_S0 is 985.14 MHz. Figure 82 As shown, in an example of the eighteenth embodiment, k_A0Z is 0.14% and Fr_A0Z is 985.64 MHz. Figure 83 As shown, in an example of the eighteenth embodiment, k_A0X is 0.35% and Fr_A0X is 985.68 MHz.

[0370] k_S0 in one example of the eighteenth embodiment is substantially the same as k_S0 in one example of the first embodiment. k_A0Z in one example of the eighteenth embodiment is substantially the same as k_A0Z in one example of the first embodiment. k_A0X in one example of the eighteenth embodiment is substantially the same as k_A0X in one example of the first embodiment. In other words, even if openings are provided in both the first electrode and the second electrode, the same effect can be achieved as when the opening is provided in only one of the first electrode and the second electrode.

[0371] <Nineteenth embodiment>

[0372] Next, refer to Figure 84 , the structure of the crystal vibration element 119 of the nineteenth embodiment is described. Figure 84 It is a top view of the crystal resonator element according to the nineteenth embodiment.

[0373] In the high-sonic velocity region 17, the second excitation electrode 14b is provided with a plurality of holes H. In other words, the second excitation electrode 14b, which has a larger area between the first excitation electrode 14a and the second excitation electrode 14b, is provided with a plurality of holes H. The opening h1 is provided on the first electrode opposite to the second electrode provided with the plurality of holes H.

[0374] Next, refer to Figures 85 to 87 , the simulation results based on the nineteenth embodiment are explained. Figures 85 to 87 It is a diagram showing the vibration distribution of the crystal resonator element according to the nineteenth embodiment. Figure 85 The vibration distribution of the S0 mode is shown as a simulation result based on the nineteenth embodiment. Figure 86 As a simulation result based on the nineteenth embodiment, the vibration distribution of the A0Z mode is shown. Figure 87The vibration distribution of the A0X mode is shown as a simulation result based on the nineteenth embodiment. Figures 85 to 87 In the figure, the second excitation electrode 14b is shown, and the first excitation electrode 14a, the first extraction electrode 15a, and the second extraction electrode 15b are not shown.

[0375] like Figure 85 As shown, in an example of the nineteenth embodiment, k_S0 is 7.37% and FrS0 is 985.14 MHz. Figure 86 As shown, in an example of the nineteenth embodiment, kA0Z is 0.10% and Fr_A0Z is 985.64 MHz. Figure 87 As shown, in an example of the nineteenth embodiment, k_A0X is 0.01% and Fr_A0X is 985.67 MHz.

[0376] In one example of the nineteenth embodiment, k_S0 is approximately the same size as k_S0 in the comparative example. In one example of the nineteenth embodiment, k_A0Z is smaller than k_A0Z in the comparative example. In one example of the nineteenth embodiment, k_A0X is smaller than k_A0X in the comparative example. Thus, when multiple holes H are provided in the second excitation electrode 14b, which has the larger area of ​​the first and second excitation electrodes 14a and 14b, and opening h1 is provided in the first electrode opposite to the second electrode having the multiple holes H, the A0 mode can be suppressed, while the vibration characteristics of the S0 mode are improved.

[0377] <Twentieth embodiment>

[0378] Next, refer to Figure 88 , the structure of the crystal vibration element 120 of the twentieth embodiment is described. Figure 88 It is a top view of a crystal resonator element according to the twentieth embodiment.

[0379] In the high-sonic velocity region 17, the second excitation electrode 14b is provided with a plurality of holes H. In other words, the second excitation electrode 14b, which has a larger area than the first excitation electrode 14a and the second excitation electrode 14b, is provided with a plurality of holes H. The opening h1' is provided on the first electrode on the same side as the second electrode having the plurality of holes H.

[0380] Next, refer to Figures 89 to 91 , the simulation results based on the twentieth embodiment are explained. Figures 89 to 91 It is a diagram showing the vibration distribution of the crystal resonator element according to the twentieth embodiment. Figure 89 The vibration distribution of the S0 mode is shown as a simulation result based on the twentieth embodiment.

[0381] Figure 90The vibration distribution of the A0Z mode is shown as a simulation result based on the twentieth embodiment.

[0382] Figure 91 The vibration distribution of the A0X mode is shown as a simulation result based on the twentieth embodiment. Figures 89 to 91 In the figure, the second excitation electrode 14b is shown, and the first excitation electrode 14a, the first extraction electrode 15a, and the second extraction electrode 15b are not shown.

[0383] like Figure 89 As shown, in an example of the twentieth embodiment, k_S0 is 7.37% and Fr_S0 is 985.14 MHz. Figure 90 As shown, in an example of the twentieth embodiment, k_A0Z is 0.12% and Fr_A0Z is 985.64 MHz. Figure 91 As shown, in an example of the twentieth embodiment, k_A0X is 0.00% and Fr_A0X is 985.67 MHz.

[0384] k_S0 in one example of the twentieth embodiment is substantially the same as k_S0 in one example of the nineteenth embodiment. k_A0Z in one example of the twentieth embodiment is substantially the same as k_A0Z in one example of the nineteenth embodiment. k_A0X in one example of the twentieth embodiment is substantially the same as k_A0X in one example of the nineteenth embodiment. In other words, the same effect can be achieved regardless of whether the opening is provided in the first electrode or the second electrode.

[0385] <Twenty-first embodiment>

[0386] Next, refer to Figure 92 , the structure of the crystal vibration element 121 of the twenty-first embodiment is described. Figure 92 It is a top view of the crystal resonator element according to the twenty-first embodiment.

[0387] Multiple holes H are provided in the second excitation electrode 14b, which has the larger area of ​​the first excitation electrode 14a and the second excitation electrode 14b. In the region overlapping the connection between the first excitation electrode 14a and the first extraction electrode 15a, an opening h1 is provided in the first excitation electrode 14a, and an opening h1' is provided in the second excitation electrode 14b. The planar shape, position, and dimensions of the opening h1 are substantially the same as those of the opening h1'.

[0388] Next, refer to Figures 93 to 95 , the simulation results based on the twenty-first embodiment are explained. Figures 93 to 95 It is a diagram showing the vibration distribution of the crystal resonator element according to the twenty-first embodiment. Figure 93 The vibration distribution of the S0 mode is shown as a simulation result based on the twenty-first embodiment. Figure 94 The vibration distribution of the A0Z mode is shown as a simulation result based on the twenty-first embodiment. Figure 95 The vibration distribution of the A0X mode is shown as a simulation result based on the twenty-first embodiment. Figures 93 to 95 In the figure, the second excitation electrode 14b is shown, and the first excitation electrode 14a, the first extraction electrode 15a, and the second extraction electrode 15b are not shown.

[0389] like Figure 93 As shown, in an example of the twenty-first embodiment, k_S0 is 7.36% and Fr_S0 is 985.14 MHz. Figure 94 As shown, in an example of the twenty-first embodiment, k_A0Z is 0.06% and Fr_A0Z is 985.64 MHz. Figure 95 As shown, in an example of the twenty-first embodiment, k_A0X is 0.04% and Fr_A0X is 985.68 MHz.

[0390] k_S0 in one example of the twenty-first embodiment is substantially the same as k_S0 in one example of the nineteenth embodiment and the twentieth embodiment. k_A0Z in one example of the twenty-first embodiment is substantially the same as k_A0Z in one example of the nineteenth embodiment and the twentieth embodiment. k_A0X in one example of the twenty-first embodiment is substantially the same as k_A0X in one example of the nineteenth embodiment and the twentieth embodiment. In other words, even if the opening is provided in both the first electrode and the second electrode, the same effect can be achieved as when the opening is provided in either the first electrode or the second electrode.

[0391] <Twenty-second embodiment>

[0392] Next, refer to Figure 96 , the structure of the crystal vibration element 122 of the twenty-second embodiment is described. Figure 96 It is a top view of the crystal resonator element according to the twenty-second embodiment.

[0393] The first extraction electrode 15a is connected to the center of the first excitation electrode 14a on the positive X-axis side. An opening h11 is provided on the first excitation electrode 14a side of boundary B, and an opening h12 is provided on the opposite side of opening h11 across the high-sonic velocity region 17. Openings h11 and h12 are slit-shaped openings with long sides extending in the direction along boundary B.

[0394] Next, refer to Figures 97 to 99, the simulation results based on the twenty-second embodiment are explained. Figures 97 to 99 It is a diagram showing the vibration distribution of the crystal resonator element according to the twenty-second embodiment. Figure 97 The vibration distribution of the S0 mode is shown as a simulation result based on the twenty-second embodiment. Figure 98 The vibration distribution of the A0Z mode is shown as a simulation result based on the twenty-second embodiment. Figure 99 The vibration distribution of the A0X mode is shown as a simulation result based on the twenty-second embodiment. Figures 97 to 99 In FIG. 1 , the first excitation electrode 14 a and the first extraction electrode 15 a are shown in the figure, and the second excitation electrode 14 b and the second extraction electrode 15 b are not shown in the figure.

[0395] like Figure 97 As shown, in an example of the twenty-second embodiment, k_S0 is 7.33% and Fr_S0 is 985.21 MHz. Figure 98 As shown, in an example of the twenty-second embodiment, k_A0Z is 0.03% and Fr_A0Z is 985.64 MHz. Figure 99 As shown, in an example of the twenty-second embodiment, k_A0X is 0.10% and Fr_A0X is 985.81 MHz.

[0396] Although not shown in the figure, in a comparative example in which the openings h11 and h12 are omitted from the twenty-second embodiment, k_S0 is 7.34%, Fr_S0 is 985.08 MHz, k_A0Z is 0.03%, Fr_A0Z is 985.63 MHz, k_A0X is 1.05%, and Fr_A0X is 985.58 MHz.

[0397] In one example of the twenty-second embodiment, k_S0 is approximately the same as k_S0 in the comparative example. In one example of the twenty-second embodiment, k_A0Z is approximately the same as k_A0Z in the comparative example. In one example of the twenty-second embodiment, k_A0X is smaller than k_A0X in the comparative example. Thus, even when the first extraction electrode 15a is connected to the center of the end portion rather than the corner portion of the first excitation electrode 14a, providing the opening h11 in the region overlapping the connection between the first excitation electrode 14a and the first extraction electrode 15a can suppress the A0 mode and improve the vibration characteristics of the S0 mode.

[0398] The following supplementary notes describe part or all of the embodiments of the present invention. However, the present invention is not limited to the following supplementary notes.

[0399] <1> A piezoelectric vibration element comprising:

[0400] The piezoelectric sheet has a first main surface and a second main surface facing each other;

[0401] The first electrode includes a first excitation electrode provided on the first main surface and a first extraction electrode connected to the first excitation electrode; and

[0402] The second excitation electrode is provided on the second main surface,

[0403] Among them, when looking down,

[0404] A high-speed sound region is provided in the center of the region where the first excitation electrode and the second excitation electrode overlap, and a low-speed sound region is provided in the peripheral portion of the region where the first excitation electrode and the second excitation electrode overlap and has a lower speed than the high-speed sound region.

[0405] The first peripheral portion of the first excitation electrode is provided on the inner side than the second peripheral portion of the second excitation electrode.

[0406] The sound velocity in the region where the first extraction electrode and the second excitation electrode overlap is lower than the sound velocity in the high sound velocity region and is equal to or higher than the sound velocity in the low sound velocity region.

[0407] In the region where the first electrode and the second excitation electrode overlap, at least one opening is provided in at least one of the first electrode and the second excitation electrode.

[0408] The at least one opening is provided within a range of a distance substantially equal to or less than four times the thickness of the piezoelectric sheet from a boundary between the first excitation electrode and the first extraction electrode.

[0409] <2> The piezoelectric vibration element according to <1>,

[0410] In the high-sonic-velocity region, a plurality of holes are provided in at least one of the first excitation electrode and the second excitation electrode.

[0411] <3> The piezoelectric vibration element according to <1> or <2>,

[0412] When viewed from above, the first excitation electrode has a rectangular shape.

[0413] The first extraction electrode is connected to a corner portion of the first excitation electrode.

[0414] <4> The piezoelectric vibration element according to <3>,

[0415] The first extraction electrode is connected to only one side of the first excitation electrode.

[0416] <5> The piezoelectric vibration element according to any one of <1> to <4>,

[0417] The at least one opening includes at least one of a slit-shaped opening having long sides extending in a direction along the boundary and row-shaped openings arranged in a direction along the boundary.

[0418] <6> The piezoelectric vibration element according to any one of <1> to <5>,

[0419] At least one opening portion includes at least one of a slit-shaped opening portion having long sides extending in a direction parallel to the boundary and a row-shaped opening portion arranged in a direction parallel to the boundary,

[0420] The total length of at least one opening in a direction parallel to the boundary is not less than 50% and not more than 90% of the length of the first extraction electrode in the direction parallel to the boundary.

[0421] <7> The piezoelectric vibration element according to any one of <1> to <6>,

[0422] At least one opening portion has openings arranged in a row in a direction parallel to the boundary,

[0423] In the direction in which the openings are arranged in a row, the length of one opening is denoted as Wh2, and the period at which the openings are arranged is denoted as Wp.

[0424] The relationship of 0.50≤Wh2 / Wp≤0.90 holds true.

[0425] <8> The piezoelectric vibration element according to any one of <1> to <7>,

[0426] When the thickness of the piezoelectric sheet is Tq, and the length of one of the at least one openings in the direction along the boundary is Wh, and the length of one of the at least one openings in the direction perpendicular to the length Wh along the boundary is Lh,

[0427] The relationship of 2<Lh / Tq holds.

[0428] <9> The piezoelectric vibration element according to any one of <1> to <8>,

[0429] The at least one opening portion includes a plurality of opening portions arranged in a direction intersecting the boundary.

[0430] <10> The piezoelectric vibration element according to any one of <1> to <9>,

[0431] The total length of at least one opening in a direction perpendicular to the boundary is at least twice the thickness of the piezoelectric sheet.

[0432] <11> The piezoelectric vibration element according to any one of <1> to <10>,

[0433] The at least one opening is a slit-shaped opening having a long side.

[0434] <12> The piezoelectric vibration element according to any one of <1> to <10>,

[0435] At least one opening portion includes a plurality of slit-shaped opening portions having long sides,

[0436] The long sides of the plurality of slit-shaped openings extend parallel to each other.

[0437] <13> The piezoelectric vibration element according to any one of <1> to <12>,

[0438] When the difference between the length of the first extraction electrode in the direction parallel to the boundary and the length of at least one opening is defined as Ws, and the length of the first excitation electrode in the direction parallel to the boundary is defined as We,

[0439] The relationship of Ws / We≤0.15 holds true.

[0440] <14> The piezoelectric vibration element according to any one of <1> to <13>,

[0441] At least one opening is formed in the first extraction electrode,

[0442] When the difference between the length of the first extraction electrode in a direction parallel to the boundary and the length of the at least one opening is defined as Ws, the length of the at least one opening in a direction perpendicular to the boundary is defined as Ls, and the sheet resistance of the portion of the first extraction electrode aligned with the at least one opening in a direction parallel to the boundary is defined as Rs,

[0443] The relationship Ls≤Ws / Rs holds.

[0444] <15> The piezoelectric vibration element according to any one of <1> to <14>,

[0445] When the distance between the boundary and the at least one opening in a direction perpendicular to the boundary is Lx, and the difference between the length of the first extraction electrode in a direction parallel to the boundary and the length of the at least one opening is Ws,

[0446] The relationship Lx=0.48×Ls-1.88±1.70 holds true.

[0447] <16> The piezoelectric vibration element according to any one of <1> to <15>,

[0448] At least one opening portion has a plurality of opening portions arranged in a row,

[0449] When the arrangement period of the plurality of openings is set to Wp, the length of each of the plurality of openings in the direction in which the plurality of openings are arranged is set to Wh2, the length of each of the plurality of openings in the direction perpendicular to the direction in which the plurality of openings are arranged is set to Lh2, and the thickness of the piezoelectric sheet is set to Tq,

[0450] The relationship of 0.6≤(Lh2 / Tq)×(Wh2 / Wp)≤2.3 holds true.

[0451] <17> The piezoelectric vibration element according to <2>,

[0452] At least one opening and a plurality of holes are formed in the electrode on the same side relative to the piezoelectric sheet.

[0453] <18> A piezoelectric vibration element comprising:

[0454] The piezoelectric sheet has a first main surface and a second main surface facing each other;

[0455] The first electrode includes a first excitation electrode provided on the first main surface and a first extraction electrode connected to the first excitation electrode; and

[0456] The second excitation electrode is provided on the second main surface,

[0457] Among them, when looking down,

[0458] A high-speed sound region is provided in the center of the region where the first excitation electrode and the second excitation electrode overlap, and a low-speed sound region is provided in the peripheral portion of the region where the first excitation electrode and the second excitation electrode overlap and has a sound velocity lower than that of the high-speed sound region.

[0459] The first peripheral portion of the first excitation electrode is provided on the inner side than the second peripheral portion of the second excitation electrode.

[0460] The sound velocity in the region where the first extraction electrode and the second excitation electrode overlap is lower than the sound velocity in the high sound velocity region and is equal to or higher than the sound velocity in the low sound velocity region.

[0461] In the low-speed region, at least one first opening is provided in at least one of the first excitation electrode and the second excitation electrode in a region on the first extraction electrode side relative to the high-speed region.

[0462] At least one second opening is provided in at least one of the first excitation electrode and the second excitation electrode in a region opposite to the first extraction electrode across the high-sonic-velocity region in the low-sonic-velocity region.

[0463] <19> The piezoelectric vibration element according to <18>,

[0464] In the high-sonic-velocity region, a plurality of holes are provided in at least one of the first excitation electrode and the second excitation electrode.

[0465] <20> The piezoelectric vibration element according to <18> or <19>,

[0466] The at least one first opening and the at least one second opening are provided within a range substantially within a distance of four times or less the thickness of the piezoelectric sheet from the first outer peripheral portion of the first excitation electrode.

[0467] <21> The piezoelectric vibration element according to any one of <18> to <20>,

[0468] When looking down,

[0469] The first excitation electrode is in a rectangular shape.

[0470] The first excitation electrode has a first corner portion and a second corner portion located diagonally opposite to each other.

[0471] The first extraction electrode is connected to the first corner of the first excitation electrode,

[0472] At least one first opening is provided in a region overlapping with the first corner portion,

[0473] The at least one second opening is provided in a region overlapping with the second corner portion.

[0474] <22> The piezoelectric vibration element according to <21>,

[0475] The first excitation electrode further has a third corner and a fourth corner located diagonally opposite to each other.

[0476] In the region overlapping the third corner portion in the low-pitched frequency region, at least one third opening is provided in at least one of the first excitation electrode and the second excitation electrode.

[0477] At least one fourth opening is provided in at least one of the first excitation electrode and the second excitation electrode in a region overlapping with the fourth corner portion in the low-pitched frequency region.

[0478] <23> The piezoelectric vibration element according to any one of <18> to <22>,

[0479] In a plan view, the at least one first opening and the at least one second opening are provided at positions symmetrical with respect to a center point of the first excitation electrode.

[0480] <24> The piezoelectric vibration element according to any one of <18> to <23>,

[0481] In a plan view, the at least one first opening and the at least one second opening are provided in a shape symmetrical with respect to a center point of the first excitation electrode.

[0482] <25> The piezoelectric vibration element according to any one of <18> to <24>,

[0483] The at least one first opening and the at least one second opening are provided in the same excitation electrode of the first excitation electrode and the second excitation electrode.

[0484] <26> The piezoelectric vibration element according to any one of <1> to <25>,

[0485] In the high-sonic-velocity region, a plurality of holes are provided in at least one of the first excitation electrode and the second excitation electrode.

[0486] The plurality of holes are holes that penetrate the excitation electrode in the thickness direction.

[0487] Assuming the thickness of the piezoelectric sheet is Tq, and when viewed from above, the length of one side of the plurality of holes in a square shape is Hr, and the length of one side when the plurality of holes are in a shape other than a square shape while maintaining a constant area is Hr,

[0488] The relationship of 0<Hr / Tq≤2.0 holds true.

[0489] In addition, this specification describes a quartz crystal resonator including a quartz crystal element as an example of a piezoelectric element, but the piezoelectric resonator is not limited to this. Examples of piezoelectric elements that can be suitably used in the piezoelectric resonator of this embodiment include piezoelectric ceramics such as lead zirconate titanate (PZT) and aluminum nitride, and piezoelectric single crystals such as lithium niobate and lithium tantalate, but are not limited to these and can be appropriately selected.

[0490] The embodiments of the present invention are not particularly limited and can be appropriately applied to any device that performs electromechanical energy conversion using the piezoelectric effect, such as a timing device, a sound generator, an oscillator, and a load sensor.

[0491] As described above, according to one aspect of the present invention, a piezoelectric vibration element capable of improving vibration characteristics can be provided.

[0492] In addition, the embodiment described above is an embodiment for facilitating the understanding of the present invention, and is not an embodiment for limiting the interpretation of the present invention. The present invention can be changed / improved within the scope of its main purpose, and its equivalents are also included in the present invention. That is, as long as the features of the present invention are possessed, the embodiments after those skilled in the art have appropriately applied design changes to the embodiments and / or modifications are also included in the scope of the present invention. For example, the various elements and their configurations, materials, conditions, shapes, sizes, etc. possessed by the embodiments and / or modifications are not limited to the illustrated contents and can be appropriately changed. In addition, the embodiments and modifications are for illustration, and of course, replacement or combination of parts of the structures shown in different embodiments and / or modifications can be performed, and as long as the features of the present invention are included, these embodiments are also included in the scope of the present invention.

[0493] Description of Reference Numerals

[0494] 1…quartz resonator, 10…quartz resonator element, 30…base member, 40…cover member, 50…joining portion, 11…quartz plate, 11A…upper surface, 11B…lower surface, 14a…first excitation electrode, 14b…second excitation electrode, 15a…first lead electrode, 15b…second lead electrode, 16a…first connecting electrode, 16b…second connecting electrode, 17…high-speed region, 18…low-speed region, 19…excitation region, 71, 72, 73, 74…peripheral portion, 81, 82, 83, 84…peripheral portion, B…boundary, h1…opening, H…hole portion.

Claims

1. A piezoelectric vibration element comprising: The piezoelectric sheet has a first main surface and a second main surface facing each other; The first electrode includes a first excitation electrode provided on the first main surface and a first extraction electrode connected to the first excitation electrode; and The second excitation electrode is provided on the second main surface. in, In a plan view, a high-speed sound region and a low-speed sound region having a lower speed than the high-speed sound region are provided, the high-speed sound region being located in the center of the region where the first excitation electrode and the second excitation electrode overlap, and the low-speed sound region being located in the peripheral portion of the region where the first excitation electrode and the second excitation electrode overlap. The first outer peripheral portion of the first excitation electrode is provided on the inner side than the second outer peripheral portion of the second excitation electrode. The sound velocity in the region where the first extraction electrode and the second excitation electrode overlap is lower than the sound velocity in the high sound velocity region and is equal to or higher than the sound velocity in the low sound velocity region. In a region where the first electrode and the second excitation electrode overlap, at least one opening is provided in at least one of the first electrode and the second excitation electrode. The at least one opening is provided within a range of a distance substantially equal to or less than four times the thickness of the piezoelectric sheet from a boundary between the first excitation electrode and the first extraction electrode.

2. The piezoelectric vibration element according to claim 1, wherein In the high-sonic velocity region, a plurality of holes are provided in at least one of the first excitation electrode and the second excitation electrode.

3. The piezoelectric vibration element according to claim 1 or 2, wherein: When viewed from above, the first excitation electrode is rectangular in shape. The first extraction electrode is connected to a corner portion of the first excitation electrode.

4. The piezoelectric vibration element according to claim 3, wherein The first extraction electrode is connected to only one side of the first excitation electrode.

5. The piezoelectric vibration element according to any one of claims 1 to 4, wherein The at least one opening includes at least one of a slit-shaped opening having long sides extending in a direction along the boundary and a row of openings arranged in a direction along the boundary.

6. The piezoelectric vibration element according to any one of claims 1 to 5, wherein The at least one opening includes at least one of a slit-shaped opening and a row of openings, wherein the slit-shaped opening has a long side extending in a direction parallel to the boundary, and the row of openings is arranged in a direction parallel to the boundary. The total length of the at least one opening in a direction parallel to the boundary is not less than 50% and not more than 90% of the length of the first extraction electrode in the direction parallel to the boundary.

7. The piezoelectric vibration element according to any one of claims 1 to 6, wherein The at least one opening has a row of openings arranged in a direction parallel to the boundary. In the direction in which the openings are arranged in the row, the length of one opening is Wh2, and the period at which the openings are arranged is Wp. The relationship of 0.50≤Wh2 / Wp≤0.90 holds true.

8. The piezoelectric vibration element according to any one of claims 1 to 7, wherein When the thickness of the piezoelectric sheet is Tq, and the length of one of the at least one opening in the direction along the boundary is Wh, and the length of one of the at least one opening in the direction perpendicular to the length Wh along the boundary is Lh, The relationship of 2<Lh / Tq holds.

9. The piezoelectric vibration element according to any one of claims 1 to 8, wherein The at least one opening includes a plurality of openings arranged in a direction intersecting the boundary.

10. The piezoelectric vibration element according to any one of claims 1 to 9, wherein The total length of the at least one opening in a direction perpendicular to the boundary is at least twice the thickness of the piezoelectric sheet.

11. The piezoelectric vibration element according to any one of claims 1 to 10, wherein The at least one opening is a slit-shaped opening having a long side.

12. The piezoelectric vibration element according to any one of claims 1 to 10, wherein: The at least one opening portion includes a plurality of slit-shaped opening portions, and the plurality of slit-shaped opening portions have long sides. The long sides of the plurality of slit-shaped openings extend parallel to each other.

13. The piezoelectric vibration element according to any one of claims 1 to 12, wherein: When the difference between the length of the first extraction electrode in a direction parallel to the boundary and the length of the at least one opening is defined as Ws, and the length of the first excitation electrode in a direction parallel to the boundary is defined as We, The relationship of Ws / We≤0.15 holds true.

14. The piezoelectric vibration element according to any one of claims 1 to 13, wherein The at least one opening is formed in the first extraction electrode. When the difference between the length of the first extraction electrode in a direction parallel to the boundary and the length of the at least one opening is defined as Ws, the length of the at least one opening in a direction perpendicular to the boundary is defined as Ls, and the sheet resistance of a portion of the first extraction electrode aligned with the at least one opening in a direction parallel to the boundary is defined as Rs, The relationship Ls≤Ws / Rs holds.

15. The piezoelectric vibration element according to any one of claims 1 to 14, wherein When the distance between the boundary and the at least one opening in a direction perpendicular to the boundary is Lx, and the difference between the length of the first extraction electrode and the length of the at least one opening in a direction parallel to the boundary is Ws, The relationship Lx=0.48×Ls-1.88±1.70 holds true.

16. The piezoelectric vibration element according to any one of claims 1 to 15, wherein The at least one opening has a plurality of openings arranged in a row, When the arrangement period of the plurality of openings is set to Wp, the length of each of the plurality of openings in the direction in which the plurality of openings are arranged is set to Wh2, the length of each of the plurality of openings in the direction perpendicular to the direction in which the plurality of openings are arranged is set to Lh2, and the thickness of the piezoelectric sheet is set to Tq, The relationship of 0.6≤(Lh2 / Tq)×(Wh2 / Wp)≤2.3 holds true.

17. The piezoelectric vibration element according to claim 2, wherein The at least one opening and the plurality of holes are formed on the electrode on the same side with respect to the piezoelectric sheet.

18. A piezoelectric vibration element comprising: The piezoelectric sheet has a first main surface and a second main surface facing each other; The first electrode includes a first excitation electrode provided on the first main surface and a first extraction electrode connected to the first excitation electrode; and The second excitation electrode is provided on the second main surface. in, In a plan view, a high-speed sound region and a low-speed sound region having a lower speed than the high-speed sound region are provided, the high-speed sound region being located in the center of the region where the first excitation electrode and the second excitation electrode overlap, and the low-speed sound region being located in the peripheral portion of the region where the first excitation electrode and the second excitation electrode overlap. The first outer peripheral portion of the first excitation electrode is provided on the inner side than the second outer peripheral portion of the second excitation electrode. The sound velocity in the region where the first extraction electrode and the second excitation electrode overlap is lower than the sound velocity in the high sound velocity region and is equal to or higher than the sound velocity in the low sound velocity region. In the low-velocity region, at least one first opening is provided in at least one of the first excitation electrode and the second excitation electrode on the first extraction electrode side relative to the high-velocity region. At least one second opening is provided in at least one of the first excitation electrode and the second excitation electrode in a region on the opposite side of the first extraction electrode across the high-sonic-velocity region in the low-sonic-velocity region.

19. The piezoelectric vibration element according to claim 18, wherein In the high-sonic velocity region, a plurality of holes are provided in at least one of the first excitation electrode and the second excitation electrode.

20. The piezoelectric vibration element according to claim 18 or 19, wherein: The at least one first opening and the at least one second opening are provided within a range of a distance from the first outer peripheral portion of the first excitation electrode that is not more than four times the thickness of the piezoelectric sheet.

21. The piezoelectric vibration element according to any one of claims 18 to 20, wherein When looking down, The shape of the first excitation electrode is rectangular. The first excitation electrode has a first corner portion and a second corner portion located diagonally opposite to each other. The first extraction electrode is connected to the first corner of the first excitation electrode. The at least one first opening is provided in a region overlapping with the first corner. The at least one second opening is provided in a region overlapping with the second corner.

22. The piezoelectric vibration element according to claim 21, wherein The first excitation electrode further comprises a third corner portion and a fourth corner portion located diagonally opposite to each other. In a region overlapping the third corner portion in the low-pitched frequency region, at least one third opening is provided in at least one of the first excitation electrode and the second excitation electrode. At least one fourth opening is provided in at least one of the first excitation electrode and the second excitation electrode in a region overlapping the fourth corner portion in the low-pitched frequency region.

23. The piezoelectric vibration element according to any one of claims 18 to 22, wherein: The at least one first opening and the at least one second opening are provided at positions symmetrical with respect to a center point of the first excitation electrode in a plan view.

24. The piezoelectric vibration element according to any one of claims 18 to 23, wherein: The at least one first opening and the at least one second opening are provided in a shape symmetrical with respect to a center point of the first excitation electrode in a plan view.

25. The piezoelectric vibration element according to any one of claims 18 to 24, wherein The at least one first opening and the at least one second opening are provided on the same excitation electrode of the first excitation electrode and the second excitation electrode.

26. The piezoelectric vibration element according to any one of claims 1 to 25, wherein: In the high-sonic velocity region, a plurality of holes are provided in at least one of the first excitation electrode and the second excitation electrode. The plurality of holes are holes that penetrate the first excitation electrode or the second excitation electrode in the thickness direction. Assuming that the thickness of the piezoelectric sheet is Tq, and when viewed from above, the length of one side of the plurality of holes in a square shape is Hr, and the length of one side when the plurality of holes are in a shape other than a square shape while maintaining a constant area is Hr, The relationship of 0<Hr / Tq≤2.0 holds true.

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