Quartz crystal elements and crystal units

Abstract

The present invention comprises a crystal piece having a main surface defined by a first base axis and a second base axis that intersects with the first base axis, and an excitation electrode part provided to the main surface of the crystal piece. When a voltage is applied to the excitation electrode part, the crystal piece undergoes thickness-shear vibration in which a surface defined by the thickness direction and the first base axis vibrates, the thickness direction being a direction intersecting the main surface. The excitation electrode part has a flat plate part and a thick part which is located at an electrode end in a direction along the main surface of the crystal piece and which is thicker than the flat plate part. The thick part has: a first protruding part which is positioned at an end of the main surface in the axis direction of the first base axis, and which protrudes from the flat plate part extending in the axis direction of the second base axis; and a second protruding part which is positioned at an end of the main surface in the axis direction of the second base axis and which protrudes from the flat plate part extending in the axis direction of the first base axis. The cross-sectional area of the first protruding part in a cross-section taken in a direction along a surface defined by the first base axis and the thickness direction of the crystal piece is greater than the cross-sectional area of the second protruding part in a cross-section taken in a direction along a surface defined by the second base axis and the thickness direction of the crystal piece.

Description

[Technical field]

[0001] The present invention relates to a quartz crystal resonator element and a quartz crystal unit. [Background technology]

[0002] Quartz crystal units with thickness-shear vibration as the main vibration are widely used as signal sources of reference signals used in oscillators, bandpass filters, etc. For example, Patent Document 1 discloses a configuration in which the mesa thickness ratio of the inverted mesa shape of the excitation electrode is changed while the shape of the vibration displacement is flattened to reduce spurious oscillations that occur at frequencies other than the main vibration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO 98 / 38736 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the prior art, it is desirable to further reduce spurious oscillations.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a quartz crystal vibrating element and a quartz crystal resonator that can further reduce spurious oscillations. [Means for solving the problem]

[0006] A quartz crystal vibrating element according to one aspect of the present invention includes a quartz crystal piece having a principal surface defined by a first base axis and a second base axis intersecting the first base axis, and an excitation electrode portion provided on the principal surface of the quartz crystal piece, wherein when a voltage is applied to the excitation electrode portion, the quartz crystal piece performs thickness-shear vibration in which the quartz crystal piece vibrates in a plane defined by the thickness direction and the first base axis when a direction intersecting the principal surface is defined as the thickness direction, and the excitation electrode portion has a flat portion and a thickness portion located at an electrode end of the principal surface of the quartz crystal piece and having a thickness greater than that of the flat portion, and the thickness portion is a thickness of the principal surface of the quartz crystal piece. The crystal piece has a first convex portion located at an axial end of a first base axis on the main surface and serving as a convex portion protruding from a flat portion extending in the axial direction of a second base axis, and a second convex portion located at an axial end of the second base axis on the main surface and serving as a convex portion protruding from a flat portion extending in the axial direction of the first base axis, wherein a cross-sectional area of ​​the first convex portion cut in a direction along a plane defined by the first base axis and a thickness direction of the crystal piece is larger than a cross-sectional area of ​​the second convex portion cut in a direction along a plane defined by the second base axis and a thickness direction of the crystal piece.

[0007] A quartz crystal vibration element according to one aspect of the present invention comprises a quartz crystal piece having a main surface defined by a first base axis and a second base axis intersecting the first base axis, and an excitation electrode portion provided on the main surface of the quartz crystal piece, wherein when a voltage is applied to the excitation electrode portion, the quartz crystal piece performs thickness-shear vibration in which the quartz crystal piece vibrates in a plane defined by the thickness direction and the first base axis when a direction intersecting the main surface is defined as the thickness direction, and the excitation electrode portion has a flat portion and a thickness portion located at an electrode end in a direction along the main surface of the quartz crystal piece and having a thickness greater than that of the flat portion, and the thickness portion is located at an end of the main surface in the axial direction of the first base axis, and has a first convex portion as a convex portion extending in the axial direction of the second base axis.

[0008] A quartz crystal vibration element according to one aspect of the present invention comprises a quartz crystal piece having a main surface defined by a first base axis and a second base axis intersecting the first base axis, and an excitation electrode portion provided on the main surface of the quartz crystal piece, wherein when a voltage is applied to the excitation electrode portion, the quartz crystal piece performs thickness-shear vibration in which the quartz crystal piece vibrates in a plane defined by the thickness direction and the first base axis when a direction intersecting the main surface is defined as the thickness direction, and the excitation electrode portion has a flat portion and a thickness portion located at an electrode end in a direction along the main surface of the quartz crystal piece and having a thickness greater than that of the flat portion, and the thickness portion is located at an end of the main surface in the axial direction of the second base axis, and has a second convex portion as a convex portion extending in the axial direction of the first base axis.

[0009] A quartz crystal resonator according to one aspect of the present invention includes the quartz crystal resonator element having the above-described configuration, a base member on which the quartz crystal resonator element is mounted, and a lid member joined to the base member to seal the quartz crystal resonator element. Effect of the Invention

[0010] According to the present invention, spurious oscillation can be further reduced. [Brief description of the drawings]

[0011] [Figure 1] 1 is an exploded perspective view showing a schematic configuration of a quartz crystal resonator according to a first embodiment. [Diagram 2] 1 is a cross-sectional view illustrating a schematic configuration of a quartz crystal resonator according to a first embodiment. [Diagram 3] 2 is a diagram illustrating an example of a principal surface defined by a first base axis and a second base axis of a quartz crystal piece. FIG. [Figure 4] 1A and 1B are diagrams illustrating an example of a main surface defined by a first base axis and a second base axis of a quartz crystal piece. [Diagram 5] FIG. 1 is a plan view of a quartz crystal vibration element according to a first embodiment. [Figure 6] 1 is a cross-sectional view of a quartz crystal vibration element according to a first embodiment. [Figure 7] 4 is a graph showing the electromechanical coupling constant of the quartz crystal vibration element according to the first embodiment. [Figure 8]4 is a graph showing vibration characteristics of the quartz crystal vibration element according to the first embodiment. [Figure 9] 4 is a graph showing vibration characteristics of the quartz crystal vibration element according to the first embodiment. [Figure 10] FIG. 11 is a plan view of a quartz crystal vibrating element according to a second embodiment. [Figure 11] FIG. 6 is a cross-sectional view of a quartz crystal vibrating element according to a second embodiment. [Figure 12] 10 is a graph showing the electromechanical coupling constant of the quartz crystal vibrating element according to the second embodiment. [Figure 13] 10 is a graph showing vibration characteristics of the quartz crystal vibration element according to the second embodiment. [Figure 14] FIG. 11 is a plan view of a quartz crystal vibrating element according to a third embodiment. [Figure 15] FIG. 11 is a cross-sectional view of a quartz crystal vibrating element according to a third embodiment. [Figure 16] 10 is a graph showing the electromechanical coupling constant of the quartz crystal vibrating element according to the third embodiment. [Figure 17] 10 is a graph showing vibration characteristics of the quartz crystal vibration element according to the third embodiment. [Figure 18] 10 is a graph showing the electromechanical coupling constant of the quartz crystal vibrating element according to the fourth embodiment. [Figure 19] 10 is a graph showing vibration characteristics of the quartz crystal vibration element according to the fourth embodiment. [Figure 20] 10 is a graph showing vibration characteristics of the quartz crystal vibration element according to the fourth embodiment. [Figure 21] 13 is a graph showing the electromechanical coupling constant of the quartz crystal vibrating element according to the fifth embodiment. [Figure 22] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the fifth embodiment. [Diagram 23] 13 is a graph showing the electromechanical coupling constant of the quartz crystal vibrating element according to the sixth embodiment. [Figure 24] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Diagram 25] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Figure 26]13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Figure 27] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Figure 28] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Figure 29] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Diagram 30] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Diagram 31] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Diagram 32] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Diagram 33] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Diagram 34] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Diagram 35] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Diagram 36] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the sixth embodiment. [Figure 37] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the seventh embodiment. [Figure 38] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the seventh embodiment. [Figure 39] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the seventh embodiment. [Diagram 40] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the seventh embodiment. [Diagram 41] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the seventh embodiment. [Diagram 42] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the seventh embodiment. [Diagram 43] 13 is a graph showing vibration characteristics of the quartz crystal vibration element according to the seventh embodiment. [Diagram 44] 1 is a graph for explaining the function of a quartz crystal vibration element. [Diagram 45] 1 is a graph for explaining the function of a quartz crystal vibration element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] First Embodiment The configuration of a quartz crystal resonator 1 according to a first embodiment of the present invention will be described with reference to FIGS.

[0013] For the sake of clarity and understanding of the relationship between the drawings, each drawing may be accompanied by an orthogonal coordinate system consisting of an X-axis, a Y'-axis, and a Z'-axis. The X-axis, the Y'-axis, and the Z'-axis correspond to each other in each drawing. The X-axis, the Y'-axis, and the Z'-axis correspond to the crystallographic axes of the quartz blank 11 described below. The X-axis corresponds to the electrical axis (polarity axis), the Y-axis corresponds to the mechanical axis, and the Z-axis corresponds to the optical axis. The Y'-axis and the Z'-axis are respectively axes obtained by rotating the Y-axis and the Z-axis around the X-axis by 35 degrees 15 minutes ± 1 minute 30 seconds in the direction from the Y-axis to the Z-axis. The X-axis is an example of the first axis, the Y-axis is an example of the second axis, and the Z-axis is an example of the third axis.

[0014] 1 and 2, the quartz crystal resonator 1 includes a quartz crystal resonator element 10, a base member 30, a lid member 40, and a bonding member 50. The quartz crystal resonator element 10 is provided between the base member 30 and the lid member 40.

[0015] The quartz crystal vibrating element 10 includes a thin quartz crystal blank 11, a first excitation electrode 14a, a second excitation electrode 14b, a first extraction electrode 15a, a second extraction electrode 15b, a first connection electrode 16a, and a second connection electrode 16b. The quartz crystal blank 11 is formed by etching a quartz crystal substrate (e.g., a quartz crystal wafer) obtained by cutting and polishing a crystal of synthetic quartz crystal. When a voltage is applied to the first excitation electrode 14a and the second excitation electrode 14b, the quartz crystal blank 11 performs thickness-shear vibration in which the quartz crystal blank 11 vibrates in a plane defined by the thickness direction and the first base axis of the quartz crystal blank 11 when the direction intersecting the main surface of the quartz crystal blank 11 is defined as the thickness direction.

[0016] 3 and 4 are diagrams for explaining an example of a principal surface defined by the first and second base axes of the quartz blank 11. Note that, while Fig. 3 and Fig. 4 show an example of a cut angle of the quartz blank 11 when the primary vibration of the quartz blank 11 is thickness shear vibration, the present invention may be applied to other cut angles as long as the primary vibration of the quartz blank 11 is thickness shear vibration.

[0017] 3, when the Z'-axis (third tilt axis) is defined as an axis obtained by tilting the Z-axis by a predetermined angle θ around the X-axis among the mutually intersecting X-axis, Y-axis, and Z-axis that are the crystal axes of quartz blank 11, the X-axis corresponds to the first base axis and the Z'-axis corresponds to the second base axis. In this case, the first base axis includes, for example, an axis obtained by tilting the X-axis slightly around the Z'-axis. Also, the second base axis includes an axis obtained by tilting the Z-axis at an angle slightly deviated from the predetermined angle around the X-axis. In the example shown in the figure, the cut angles of quartz blank 11 include, for example, AT cut, BT cut, and CT cut.

[0018] The AT-cut crystal blank 11 has a main surface that is parallel to a plane defined by the X-axis and a Z'-axis inclined by about 35 degrees around the X-axis. The AT-cut crystal blank 11 may have a main surface that is parallel to a plane defined by the Z'-axis inclined by an angle slightly different from about 35 degrees around the X-axis and the X'-axis inclined by a slight angle around the Z-axis. The crystal vibrating element 10 using the AT-cut crystal blank 11 has high frequency stability over a wide temperature range. The BT-cut crystal blank 11 has a main surface that is parallel to a plane defined by the X-axis and a Z'-axis inclined by about -49 degrees around the X-axis. The CT-cut crystal blank 11 has a main surface that is parallel to a plane defined by the X-axis and a Z'-axis inclined by about 38 degrees around the X-axis.

[0019] In the example shown in FIG. 4, among the mutually intersecting X-axis, Y-axis, and Z-axis which are the crystal axes of the quartz blank, the X-axis tilted at a predetermined angle φ around the Z-axis is defined as the X'-axis (first tilt axis) (see FIG. 4(a)), and the Z-axis tilted at a predetermined angle θ around the X'-axis is defined as the Z'-axis (third tilt axis) (see FIG. 4(b)). In this case, the X'-axis corresponds to the first base axis and the Z'-axis corresponds to the second base axis. In this case, the first base axis includes, for example, the X-axis tilted at an angle slightly deviated from the predetermined angle φ around the Z-axis. Also, the second base axis includes the Z-axis tilted at an angle slightly deviated from the predetermined angle around the X'-axis. In the example shown in the figure, the cut angle of the quartz blank 11 includes, for example, an SC cut. For example, the main surface of the SC-cut crystal piece 11 is a plane parallel to a plane defined by an X'-axis that is inclined about 22 degrees from the X-axis around the Z-axis, and a Z'-axis that is inclined about 34 degrees from the Z-axis around the X'-axis.

[0020] 1 and 2, AT-cut crystal piece 11 is a plate having a long side direction parallel to the X-axis, a short side direction parallel to the Z'-axis, and a thickness direction parallel to the Y'-axis. First principal surface 11A and second principal surface 11B of crystal piece 11 are rectangular.

[0021] The quartz crystal vibrating element 10 includes an excitation electrode portion 14. The excitation electrode portion 14 includes, for example, a first excitation electrode 14a and a second excitation electrode 14b. The first excitation electrode 14a is provided on a first main surface 11A of the quartz crystal piece 11. The second excitation electrode 14b is provided on a second main surface 11B of the quartz crystal piece 11. The first excitation electrode 14a and the second excitation electrode 14b face each other across the quartz crystal piece 11. The first excitation electrode 14a and the second excitation electrode 14b are rectangular and are arranged to overlap each other in a plan view.

[0022] The first excitation electrode 14a and the second excitation electrode 14b are located at electrode ends in a direction along the first main surface 11A of the crystal piece 11, and have a thickness portion 14C that is thicker than the flat portion 14B.

[0023] The quartz crystal vibrating element 10 has a first extraction electrode 15a and a second extraction electrode 15b. The first extraction electrode 15a is provided on a first main surface 11A of the quartz crystal piece 11. The first extraction electrode 15a electrically connects the first excitation electrode 14a and the first connection electrode 16a. The second extraction electrode 15b is provided on a second main surface 11B of the quartz crystal piece 11. The second extraction electrode 15b electrically connects the second excitation electrode 14b and the second connection electrode 16b.

[0024] The first connection electrode 16a extends in the +Z'-axis direction from the end of the first extraction electrode 15a on the -X-axis direction side, is folded back at the end face on the +Z'-axis direction side of the crystal blank 11, and extends in the -Z'-axis direction on the second main surface 11B of the crystal blank 11. The first excitation electrode 14a and the base member 30 are electrically connected via the first extraction electrode 15a and the first connection electrode 16a. The second connection electrode 16b extends in the -Z'-axis direction from the end of the second extraction electrode 15b on the -X-axis direction side, is folded back at the end face on the -Z-axis direction side of the crystal blank 11, and extends in the +Z'-axis direction on the second main surface 11B of the crystal blank 11. The second excitation electrode 14b and the base member 30 are electrically connected via the second extraction electrode 15b and the second connection electrode 16b.

[0025] The base member 30 is made of a sintered material such as insulating ceramic (alumina). The crystal vibrating element 10 is mounted on an upper surface 31A of the base member 30. An external circuit board (not shown) is mounted on a lower surface 31B of the base member 30.

[0026] The base member 30 includes a first electrode pad 33a, a second electrode pad 33b, a first external electrode 35a, a second external electrode 35b, a third external electrode 35c, a fourth external electrode 35d, a first conductive holding member 36a, and a second conductive holding member 36b.

[0027] The first electrode pad 33a and the second electrode pad 33b are provided on the upper surface of the base member 30 and are electrically connected to the quartz crystal vibrating element .

[0028] The first external electrode 35a and the second external electrode 35b are provided on the lower surface 31B of the base member 30, and electrically connect the crystal unit 1 to an external substrate (not shown). The third external electrode 35c and the fourth external electrode 35d are provided on the lower surface 31B of the base member 30, and are dummy electrodes to which no electrical signals are input. The first electrode pad 33a is electrically connected to the first external electrode 35a via a first through electrode 34a that penetrates the base member 30 along the Y'-axis direction. The second electrode pad 33b is electrically connected to the second external electrode 35b via a second through electrode 34b that penetrates the base member 30 along the Y'-axis direction.

[0029] The first conductive holding member 36a and the second conductive holding member 36b are, for example, a cured product of a conductive adhesive containing a thermosetting resin, a photocurable resin, etc., and the main component of the first conductive holding member 36a and the second conductive holding member 36b is a silicone resin. The first conductive holding member 36a and the second conductive holding member 36b contain conductive particles, and as the conductive particles, for example, metal particles containing silver (Ag) are used.

[0030] The first conductive holding member 36a and the second conductive holding member 36b electrically connect the quartz crystal vibrating element 10 and the base member 30. The first conductive holding member 36a bonds the first electrode pad 33a and the first connection electrode 16a. The second conductive holding member 36b bonds the second electrode pad 33b and the second connection electrode 16b. The first conductive holding member 36a and the second conductive holding member 36b hold the quartz crystal vibrating element 10 at a distance from the base member 30 so that the quartz crystal vibrating element 10 can be excited.

[0031] The cover member 40 is joined to the base member 30, and forms an internal space 49 between the cover member 40 and the base member 30. The crystal vibration element 10 is accommodated in the internal space 49. The material of the cover member 40 is not particularly limited, but is, for example, made of a conductive material such as a metal. By making the cover member 40 out of a conductive material, the entry and exit of electromagnetic waves into the internal space 49 is reduced.

[0032] The bonding member 50 bonds the tip of the side wall of the cover member 40 to the upper surface 31A of the base member 30, sealing the internal space 49. It is desirable that the bonding member 50 has high gas barrier properties, and it is further desirable that the bonding member 50 has low moisture permeability. The bonding member 50 is, for example, a cured product of an adhesive containing an epoxy resin as a main component. The resin-based adhesive constituting the bonding member 50 may include, for example, a vinyl compound, an acrylic compound, a urethane compound, a silicone compound, etc.

[0033] Next, the configuration of the excitation electrode portion 14 of the quartz crystal vibrating element 10 according to this embodiment will be described, particularly focusing on the configuration of the film thickness portion 14C of the excitation electrode portion 14. In the following description, for the convenience of understanding the description of the specification, the film thickness portion 14C of the first excitation electrode 14a will be particularly described, but the film thickness portion of the second excitation electrode 14b also has a similar configuration.

[0034] As shown in FIG. 5 and FIG. 6, the first excitation electrode 14a has, for example, a flat plate portion 14B and a film thickness portion 14C. The flat plate portion 14B has, for example, a rectangular shape, and is provided on the first main surface of the crystal piece 11. The film thickness portion 14C includes a first convex portion 14Ca and a second convex portion 14Cb protruding from the upper surface of the flat plate portion 14B. The first convex portion 14Ca and the second convex portion 14Cb are made of, for example, the same material as the flat plate portion 14B in the first excitation electrode 14a. The first convex portion 14Ca and the second convex portion 14Cb may be made of a material different from the flat plate portion 14B in the first excitation electrode 14a. In this case, the first convex portion 14Ca and the second convex portion 14Cb are made of, for example, an insulating material. The first convex portion 14Ca is located at an end in the X-axis direction on the first main surface 11A of the crystal piece 11, and extends in the Z′-axis direction. The first convex portions 14Ca are located, for example, at both ends in the X-axis direction on the first main surface 11A of the crystal piece 11, and extend from one end to the other end in the Z'-axis direction on the first main surface 11A of the crystal piece 11. The second convex portions 14Cb are located at ends in the Z'-axis direction on the second main surface 11B of the crystal piece 11, and extend in the X-axis direction. The second convex portions 14Cb are located, for example, at both ends in the Z'-axis direction on the second main surface 11B of the crystal piece 11, and extend from one end to the other end in the X-axis direction on the second main surface 11B of the crystal piece 11. The width Wx of the first convex portions 14Ca is greater than the width Wz of the second convex portions 14Cb.

[0035] Next, the function of the crystal resonator 1 according to the present embodiment will be described with reference to FIG. 7 to FIG. 9. FIG. 7 and FIG. 8 show vibration characteristics of the crystal resonator element 10 predicted using a simulation model of the crystal resonator 1 according to the present embodiment. In the simulation model of the crystal resonator 1, aluminum is set as the material of the excitation electrode portion 14. In the simulation model of the crystal resonator 1, when a voltage is applied to the excitation electrode portion 14, the crystal blank 11 performs thickness-shear vibration in which the crystal blank 11 vibrates in a plane defined by the thickness direction and the first base axis when the direction intersecting the main surface is the thickness direction. FIG. 7 is a graph showing the electromechanical coupling constant of the crystal resonator element 10 according to the present embodiment. The electromechanical coupling constant is a coefficient that represents the conversion ability between electrical energy and mechanical energy, and the larger the value of this coefficient, the higher the conversion ability between electrical energy and mechanical energy. FIG. 8 is a graph showing the vibration characteristics of the crystal resonator element 10 according to the present embodiment. The vibration characteristics of the crystal resonator element 10 show the vibration shape of the crystal resonator element 10 during thickness-shear vibration. FIG. 9 is a graph showing the vibration characteristics of the quartz crystal vibrating element 10 according to this embodiment while changing various parameters related to the quartz crystal vibrating element 10. In FIG.

[0036] 7 shows the change in the electromechanical coupling constant of the quartz crystal unit 1 when the width Wz of the second convex portion 14Cb is fixed at "3.4" and the width Wx of the first convex portion 14Ca is changed. In the example shown in the figure, the vertical axis represents the electromechanical coupling constant, and the horizontal axis represents the ratio of the width Wx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11. In this example, the value of the electromechanical coupling constant is "6.8" in a comparative example corresponding to a case where the excitation electrode portion 14 is not provided with the first convex portion 14Ca and the second convex portion 14Cb. In contrast, in an embodiment in which the excitation electrode portion 14 is provided with the first convex portion 14Ca and the second convex portion 14Cb, when the ratio of the width Wx of the first convex portion 14Ca to the thickness T of the crystal blank 11 is increased stepwise from "0.0", "3.4", "4.6", to "5.0", the value of the electromechanical coupling constant is "7.5" when the ratio is "0", and the value of the electromechanical coupling constant tends to increase as the ratio increases. When the ratio is "4.6", the value of the electromechanical coupling constant reaches a maximum value of "7.9".

[0037] That is, when the first convex portion 14Ca or the second convex portion 14Cb is provided on the excitation electrode portion 14, the speed of sound propagating through the excitation electrode portion 14 is partially reduced due to the mass loading effect. Therefore, during thickness-shear vibration of the crystal blank 11, the wavelength of vibration of the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14 becomes relatively shorter than the wavelength of vibration of the flat portion 14B of the excitation electrode portion 14. Then, the distortion generated in the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14 becomes relatively larger than the distortion generated in the flat portion 14B of the excitation electrode portion 14. As a result, during thickness-shear vibration of the quartz crystal piece 11, distortion is concentrated on the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14, and distortion in the flat portion 14B of the excitation electrode portion 14 is relieved and the amount of displacement becomes uniform, thereby increasing the electromechanical coupling constant of the quartz crystal vibration element 10.

[0038] 7, the quartz crystal vibrating element 10 satisfies the condition that the width Wx of the first convex portion 14Ca is greater than the width Wz of the second convex portion 14Cb. That is, during thickness-shear vibration of the quartz crystal blank 11, the quartz crystal blank 11 is displaced in the X-axis direction, and the distortion generated in the excitation electrode portion 14 is greater in the X-axis direction than in the Z'-axis direction. Therefore, the optimal value of the width Wx of the first convex portion 14Ca for alleviating the distortion in the X-axis direction is greater than the optimal value of the width Wz of the second convex portion 14Cb for alleviating the distortion in the Z'-axis direction.

[0039] The example shown in FIG. 8 shows the vibration characteristics of the quartz crystal vibrating element 10 in the example shown in FIG. 7 when the ratio of the width Wx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11 is set so that the value of the electromechanical coupling constant is the maximum value "7.9". FIG. 8 is a diagram showing the displacement amount for each position in the Z-axis direction in the quartz crystal vibrating element 10. In the example shown in FIG. 8, a comparative example corresponding to the case where the quartz crystal vibrating element 10 is not provided with the first convex portion 14Ca and the second convex portion 14Cb is provided on the quartz crystal blank 11 under the above conditions is superimposed. As is clear from the example shown in FIG. 8, the quartz crystal vibrating element 10 of the example has a flatter vibration shape during thickness-shear vibration than the quartz crystal vibrating element 10 of the comparative example, and spurious oscillation, which is a vibration occurring at a frequency other than the main vibration, is suitably reduced.

[0040] In the examples shown in Fig. 9(a) to Fig. 9(c), the thickness T of the crystal blank 11, the thickness Te of the flat portion 14B of the excitation electrode portion 14, and the thickness Tf of the film thickness portion 14C of the excitation electrode portion 14 are changed as various parameters of the crystal vibrating element 10 shown in Fig. 9(d). The thickness Tf corresponds to the amount of protrusion of the film thickness portion 14C from the flat portion 14B of the excitation electrode portion 14. Fig. 9(a) is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.05", and the ratio of the thickness Tf of the film thickness portion 14C of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.02". 9B is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.10" and the ratio of the thickness Tf of the film thickness portion 14C of the crystal blank 11 to the thickness T of the crystal blank 11 is "0.03". FIG. 9C is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.20" and the ratio of the thickness of the film thickness portion 14C of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.06". In any of these examples, when the condition for the width Wx of the first convex portion 14Ca at which the electromechanical coupling constant is maximized is compared with the condition for the width Wz of the second convex portion 14Cb at which the electromechanical coupling constant is maximized, the width Wx of the first convex portion 14Ca is larger than the width Wz of the second convex portion 14Cb.

[0041] The quartz crystal vibrating element 10 according to this embodiment has a Y'-axis and a Z'-axis, which are axes obtained by inclining the Y-axis and the Z-axis by a predetermined angle around the X-axis, among the X-axis, Y-axis, and Z-axis, and includes a quartz crystal blank 11 having a first principal surface 11A and a second principal surface 11B that are parallel to a plane specified by the X-axis and the Z'-axis, and excitation electrode portions 14 provided on the first principal surface 11A and the second principal surface 11B of the quartz crystal blank 11. When a voltage is applied to the excitation electrode portions 14, the quartz crystal blank 11 has a thickness that vibrates in a plane defined by the thickness direction and the first base axis when a direction intersecting the principal surfaces is defined as the thickness direction. The excitation electrode portion 14 performs shear vibration, and is located at the electrode end in the direction along the first principal surface 11A and the second principal surface 11B of the quartz crystal piece 11, and has a film thickness portion 14C having a thickness greater than that of the flat portion 14B, and the film thickness portion 14C has a first convex portion 14Ca located at the end in the axial direction of the X-axis on the first principal surface 11A and the second principal surface 11B and extending in the axial direction of the Z'-axis, and a second convex portion 14Cb located at the end in the axial direction of the Z'-axis on the first principal surface 11A and the second principal surface 11B and extending in the axial direction of the X-axis, and a width Wx of the first convex portion 14Ca is greater than a width Wz of the second convex portion 14Cb. In the quartz crystal vibrating element 10, when the width Wx of the first convex portion 14Ca is larger than the width Wz of the second convex portion 14Cb, distortion is concentrated on the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14 during thickness-shear vibration of the quartz crystal blank 11, and distortion in the flat portion 14B of the excitation electrode portion 14 is alleviated and the amount of displacement becomes uniform, compared to when the width Wx of the first convex portion 14Ca is equal to or smaller than the width Wz of the second convex portion 14Cb. Therefore, the value of the electromechanical coupling constant, which corresponds to the efficiency of the piezoelectric effect in the quartz crystal vibrating element 10, becomes large, and spurious oscillations, which are vibrations occurring at frequencies other than the main vibration, can be reduced.

[0042] <Second embodiment> In the second embodiment, the description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0043] As shown in FIG. 10 and FIG. 11, the first excitation electrode 14a has, for example, a flat plate portion 14B and a film thickness portion 14C. The flat plate portion 14B has, for example, a rectangular shape, and is provided on the first main surface 11A of the crystal piece 11. The film thickness portion 14C protrudes from the upper surface of the flat plate portion 14B and includes, for example, a first convex portion 14Ca. The first convex portion 14Ca is located at an end portion in the X-axis direction on the first main surface 11A of the crystal piece 11, and extends in the Z′-axis direction. The first convex portion 14Ca is located at, for example, both ends in the X-axis direction on the first main surface 11A of the crystal piece 11, and extends from one end to the other end in the Z′-axis direction on the first main surface 11A of the crystal piece 11.

[0044] Next, the function of the crystal unit 1 according to the present embodiment will be described with reference to FIG. 12 and FIG. 13. FIG. 12 and FIG. 13 show vibration characteristics of the crystal unit 10 predicted using a simulation model of the crystal unit 1 according to the present embodiment. In the simulation model of the crystal unit 1, aluminum is set as the material of the excitation electrode portion 14. In the simulation model of the crystal unit 1, when a voltage is applied to the excitation electrode portion 14, the crystal blank 11 performs thickness-shear vibration in which the crystal blank 11 vibrates in a plane defined by the thickness direction and the first base axis when the direction intersecting the main surface is the thickness direction. FIG. 12 is a graph showing the electromechanical coupling constant of the crystal unit 1 according to the present embodiment. FIG. 13 is a graph showing vibration characteristics of the crystal unit 1 according to the present embodiment. The vibration characteristics of the crystal unit 1 show the vibration shape of the crystal unit 1 during thickness-shear vibration.

[0045] FIG. 12 shows an example of the change in the electromechanical coupling constant of the crystal unit 1 when the width Wx of the first convex portion 14Ca is changed. In the example shown in the figure, the vertical axis represents the electromechanical coupling constant, and the horizontal axis represents the ratio of the width Wx of the first convex portion 14Ca to the thickness T of the crystal blank 11. In this example, in a comparative example corresponding to the case where the first convex portion 14Ca is not provided on the crystal blank 11, the value of the electromechanical coupling constant is "6.8". In contrast, in an example corresponding to the case where the first convex portion 14Ca is provided on the crystal blank 11, when the ratio of the width Wx of the first convex portion 14Ca to the thickness T of the crystal blank 11 is increased stepwise from "3.8", to "4.2", to "5.0", to "7.0", the value of the electromechanical coupling constant reaches a maximum value of "7.3" when the ratio is "4.2".

[0046] That is, when the first convex portion 14Ca is provided on the excitation electrode portion 14, the speed of sound propagating through the excitation electrode portion 14 is partially reduced due to the mass loading effect. Therefore, during thickness-shear vibration of the crystal blank 11, the wavelength of vibration of the first convex portion 14Ca of the excitation electrode portion 14 becomes relatively shorter than the wavelength of vibration of the flat portion 14B of the excitation electrode portion 14. Then, the distortion occurring in the first convex portion 14Ca of the excitation electrode portion 14 becomes relatively larger than the distortion occurring in the flat portion 14B of the excitation electrode portion 14. As a result, during thickness-shear vibration of the crystal blank 11, distortion is concentrated on the first convex portion 14Ca of the excitation electrode portion 14, and the distortion in the flat portion 14B of the excitation electrode portion 14 is alleviated and the amount of displacement becomes uniform, so that the electromechanical coupling constant of the crystal vibration element 10 increases.

[0047] The example shown in FIG. 13 shows the vibration characteristics of the quartz crystal vibrating element 10 in the example shown in FIG. 12 when the ratio of the width Wx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11 is set so that the value of the electromechanical coupling constant is the maximum value "7.3". FIG. 13 is a diagram showing the displacement amount for each position in the X-axis direction in the quartz crystal vibrating element 10. In the example shown in FIG. 13, a comparative example corresponding to a case where the first convex portion 14Ca is not provided on the quartz crystal blank 11 and an example corresponding to a case where the first convex portion 14Ca is provided on the quartz crystal blank 11 under the above conditions are overlapped. As is clear from the example shown in FIG. 8, the quartz crystal vibrating element 10 of the example has a flatter vibration shape during thickness-shear vibration than the quartz crystal vibrating element 10 of the comparative example, and spurious oscillation, which is a vibration occurring at a frequency other than the main vibration, is suitably reduced.

[0048] The quartz crystal vibrating element 10 according to this embodiment is provided with a quartz crystal blank 11 having a first principal surface 11A and a second principal surface 11B that are parallel to a plane defined by the X-axis and Z-axis, and an excitation electrode portion 14 provided on the first principal surface 11A and the second principal surface 11B of the quartz crystal blank 11. When a voltage is applied to the excitation electrode portion 14, the quartz crystal blank 11 is provided with an excitation electrode portion 14 that is intersected with the principal surfaces. When the intersecting direction is the thickness direction, the crystal blank 11 performs thickness-shear vibration in which the crystal blank 11 vibrates in a plane defined by the thickness direction and the first base axis, and the excitation electrode portion 14 is located at the electrode end in the direction along the first main surface 11A and the second main surface 11B of the crystal blank 11 and has a film thickness portion 14C that is thicker than the flat portion 14B, and the film thickness portion 14C is located at the end of the first main surface 11A and the second main surface 11B in the axial direction of the X-axis and has a first convex portion 14Ca extending in the axial direction of the Z'-axis. When the crystal vibrating element 10 has the first convex portion 14Ca, distortion is concentrated on the first convex portion 14Ca of the excitation electrode portion 14 during thickness-shear vibration of the crystal blank 11, and distortion in the flat portion 14B of the excitation electrode portion 14 is alleviated, resulting in a uniform amount of displacement, compared to when the crystal blank 11 does not have the first convex portion 14Ca. Therefore, the value of the electromechanical coupling constant, which corresponds to the efficiency of the piezoelectric effect in the quartz crystal vibrating element 10, becomes large, so that spurious oscillations, which are vibrations occurring at frequencies other than the main vibration, can be reduced.

[0049] <Third embodiment> In the third embodiment, the description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0050] As shown in FIG. 14 and FIG. 15, the first excitation electrode 14a has, for example, a flat plate portion 14B and a film thickness portion 14C. The flat plate portion 14B has, for example, a rectangular shape, and is provided on the first main surface 11A of the crystal piece 11. The film thickness portion 14C protrudes from the upper surface of the flat plate portion 14B and includes, for example, a second convex portion 14Cb. The second convex portion 14Cb is located at an end portion in the Z′-axis direction on the second main surface 11B of the crystal piece 11 and extends in the X-axis direction. The second convex portion 14Cb is located, for example, at both ends in the Z′-axis direction on the second main surface 11B of the crystal piece 11 and extends from one end to the other end in the X-axis direction on the second main surface 11B of the crystal piece 11.

[0051] Next, the function of the quartz crystal vibrating element 10 according to this embodiment will be described with reference to FIG. 16 and FIG. 17. FIG. 16 and FIG. 17 show vibration characteristics of the quartz crystal vibrating element 10 predicted using a simulation model of the quartz crystal vibrator 1 according to this embodiment. In the simulation model of the quartz crystal vibrator 1, aluminum is set as the material of the excitation electrode portion 14. In addition, in the simulation model of the quartz crystal vibrator 1, when a voltage is applied to the excitation electrode portion 14, the quartz crystal blank 11 performs thickness-shear vibration in which the quartz crystal blank 11 vibrates in a plane defined by the thickness direction and the first base axis when the direction intersecting the main surface is the thickness direction. FIG. 16 is a graph showing the electromechanical coupling constant of the quartz crystal vibrating element 10 according to this embodiment. FIG. 17 is a graph showing the vibration characteristics of the quartz crystal vibrating element 10 according to this embodiment. The vibration characteristics of the quartz crystal vibrating element 10 show the vibration shape of the quartz crystal vibrating element 10 during thickness-shear vibration.

[0052] The example shown in FIG. 16 shows the change in the electromechanical coupling constant of the quartz crystal vibrating element 10 when the width Wz of the second convex portion 14Cb is changed. In the example shown in the figure, the vertical axis represents the electromechanical coupling constant, and the horizontal axis represents the ratio of the width Wz of the second convex portion 14Cb to the thickness T of the quartz crystal piece 11. In this example, in a comparative example corresponding to a case where the second convex portion 14Cb is not provided on the quartz crystal piece 11, the value of the electromechanical coupling constant is "6.8". In contrast, in an example corresponding to a case where the second convex portion 14Cb is provided on the quartz crystal piece 11, when the ratio of the width Wz of the second convex portion 14Cb to the thickness T of the quartz crystal piece 11 is increased stepwise from "2.8", "3.4", "4.0", to "7.0", the value of the electromechanical coupling constant reaches the maximum value "7.4" when the ratio is "3.4".

[0053] That is, when the second convex portion 14Cb is provided on the excitation electrode portion 14, the sound velocity propagating through the excitation electrode portion 14 is partially decreased due to the mass loading effect. Therefore, during thickness-shear vibration of the crystal blank 11, the wavelength of vibration of the second convex portion 14Cb of the excitation electrode portion 14 becomes relatively shorter than the wavelength of vibration of the flat portion 14B of the excitation electrode portion 14. Then, the distortion occurring in the second convex portion 14Cb of the excitation electrode portion 14 becomes relatively larger than the distortion occurring in the flat portion 14B of the excitation electrode portion 14. As a result, during thickness-shear vibration of the crystal blank 11, distortion is concentrated on the second convex portion 14Cb of the excitation electrode portion 14, and the distortion in the flat portion 14B of the excitation electrode portion 14 is alleviated and the amount of displacement becomes uniform, so that the electromechanical coupling constant of the crystal vibration element 10 increases.

[0054] The example shown in FIG. 17 shows the vibration characteristics of the quartz crystal vibrating element 10 in the example shown in FIG. 16 when the ratio of the width Wz of the second convex portion 14Cb to the thickness T of the quartz crystal blank 11 is set so that the value of the electromechanical coupling constant is the maximum value "7.4". FIG. 15 is a diagram showing the displacement amount for each position in the Z-axis direction in the quartz crystal vibrating element 10. In the example shown in FIG. 17, a comparative example corresponding to a case where the second convex portion 14Cb is not provided on the quartz crystal blank 11 and an example corresponding to a case where the second convex portion 14Cb is provided on the quartz crystal blank 11 under the above conditions are overlapped. As is clear from the example shown in FIG. 17, the quartz crystal vibrating element 10 of the example has a flatter vibration shape during thickness-shear vibration than the quartz crystal vibrating element 10 of the comparative example, and spurious oscillation, which is a vibration occurring at a frequency other than the main vibration, is suitably reduced.

[0055] The quartz crystal vibrating element 10 according to this embodiment is provided with a quartz crystal blank 11 having a first principal surface 11A and a second principal surface 11B that are parallel to a plane defined by the X-axis and Z-axis, and an excitation electrode portion 14 provided on the first principal surface 11A and the second principal surface 11B of the quartz crystal blank 11. When a voltage is applied to the excitation electrode portion 14, the quartz crystal blank 11 When the direction intersecting the principal surface is defined as the thickness direction, the crystal blank 11 performs thickness-shear vibration in a plane defined by the thickness direction and the first base axis, and the excitation electrode portion 14 is located at the electrode end in the direction along the first principal surface 11A and the second principal surface 11B of the crystal blank 11 and has a film thickness portion 14C having a larger film thickness than the flat portion 14B, and the film thickness portion 14C is located at the end in the Z'-axis direction on the second principal surface 11B of the crystal blank 11 and has a second convex portion 14Cb extending in the X-axis direction. When the crystal vibrating element 10 has the second convex portion 14Cb, distortion is concentrated on the second convex portion 14Cb of the excitation electrode portion 14 during thickness-shear vibration of the crystal blank 11, compared to when the crystal vibrating element 10 does not have the second convex portion 14Cb. Therefore, the value of the electromechanical coupling constant, which corresponds to the efficiency of the piezoelectric effect in the quartz crystal vibrating element 10, becomes large, so that spurious oscillations, which are vibrations occurring at frequencies other than the main vibration, can be reduced.

[0056] <Fourth embodiment> In the fourth embodiment, the description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0057] The function of the crystal resonator 1 according to this embodiment will be described with reference to FIG. 18 to FIG. 20. FIG. 18 to FIG. 20 show vibration characteristics of the crystal resonator element 10 predicted using a simulation model of the crystal resonator 1 according to this embodiment. In the simulation model of the crystal resonator 1, aluminum is set as the material of the excitation electrode portion 14. In the simulation model of the crystal resonator 1, when a voltage is applied to the excitation electrode portion 14, the crystal blank 11 performs thickness-shear vibration in which the crystal blank 11 vibrates in a plane defined by the thickness direction and the first base axis when the direction intersecting the main surface is the thickness direction. FIG. 18 is a graph showing the electromechanical coupling constant of the crystal resonator element 10 according to this embodiment. The electromechanical coupling constant is a coefficient that represents the conversion ability between electrical energy and mechanical energy, and the larger the value of this coefficient, the higher the conversion ability between electrical energy and mechanical energy. FIG. 19 and FIG. 20 are graphs showing the vibration characteristics of the crystal resonator element 10 according to this embodiment. The vibration characteristics of the crystal resonator element 10 show the vibration shape of the crystal resonator element 10 during thickness-shear vibration.

[0058] 18 shows the change in the electromechanical coupling constant of the quartz crystal unit 1 when the width Wx of the first convex portion 14Ca and the width Wz of the second convex portion 14Cb are fixed at "4.5", the ratio of the protrusion amount Tfz of the second convex portion 14Cb to the thickness T of the quartz crystal blank 11 is fixed at "0.013", and the ratio of the protrusion amount Tfx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11 is changed. In the example shown in the figure, the vertical axis represents the electromechanical coupling constant, and the horizontal axis represents the ratio of the protrusion amount Tfx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11. In this example, the value of the electromechanical coupling constant is "6.8" in a comparative example corresponding to a case where the excitation electrode portion 14 is not provided with the first convex portion 14Ca and the second convex portion 14Cb. In contrast, in an embodiment in which the excitation electrode 14 is provided with the first convex 14Ca and the second convex 14Cb, when the ratio of the protrusion amount Tfx of the first convex 14Ca to the thickness T of the crystal blank 11 is increased stepwise from "0.0", "0.010", "0.018", "0.025", to "0.035", when the ratio is "0", the value of the electromechanical coupling constant is "7.5", and the value of the electromechanical coupling constant tends to increase as the ratio increases. When the ratio is "0.018", the value of the electromechanical coupling constant reaches a maximum value of "8.0".

[0059] That is, when the first convex portion 14Ca or the second convex portion 14Cb is provided on the excitation electrode portion 14, the speed of sound propagating through the excitation electrode portion 14 is partially reduced due to the mass loading effect. Therefore, during thickness-shear vibration of the crystal blank 11, the wavelength of vibration of the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14 becomes relatively shorter than the wavelength of vibration of the flat portion 14B of the excitation electrode portion 14. Then, the distortion generated in the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14 becomes relatively larger than the distortion generated in the flat portion 14B of the excitation electrode portion 14. As a result, during thickness-shear vibration of the quartz crystal piece 11, distortion is concentrated on the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14, and distortion in the flat portion 14B of the excitation electrode portion 14 is relieved and the amount of displacement becomes uniform, thereby increasing the electromechanical coupling constant of the quartz crystal vibration element 10.

[0060] 18, the quartz-crystal vibrating element 10 satisfies the condition that the protrusion amount Tfx of the first convex portion 14Ca is greater than the protrusion amount Tfz of the second convex portion 14Cb, under the assumption that the width Wx of the first convex portion 14Ca and the width Wz of the second convex portion 14Cb are the same. That is, during thickness-shear vibration of the quartz-crystal blank 11, the quartz-crystal blank 11 is displaced in the X-axis direction, and the distortion generated in the excitation electrode portion 14 is greater in the X-axis direction than in the Z'-axis direction. Therefore, the optimal value of the protrusion amount Tfx of the first convex portion 14Ca for alleviating the distortion in the X-axis direction is greater than the optimal value of the protrusion amount Tfz of the second convex portion 14Cb for alleviating the distortion in the Z'-axis direction.

[0061] 19 and 20 show vibration characteristics of the quartz crystal vibrating element 10 in the example shown in FIG. 18 when the ratio of the protrusion amount Tfx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11 is set so that the value of the electromechanical coupling constant is the maximum value "8.0". FIG. 19 is a diagram showing the displacement amount for each position in the X-axis direction in the quartz crystal vibrating element 10. FIG. 20 is a diagram showing the displacement amount for each position in the Z-axis direction in the quartz crystal vibrating element 10. In the examples shown in FIG. 19 and 20, a comparative example corresponding to the case where the quartz crystal vibrating element 10 does not have the first convex portion 14Ca and the second convex portion 14Cb is provided on the quartz crystal blank 11 under the above conditions is superimposed. As is clear from the examples shown in FIG. 19 and 20, the quartz crystal vibrating element 10 of the example has a flatter vibration shape during thickness-shear vibration than the quartz crystal vibrating element 10 of the comparative example, and spurious oscillation, which is a vibration occurring at a frequency other than the main vibration, is suitably reduced.

[0062] <Fifth embodiment> In the fifth embodiment, the description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0063] The function of the crystal unit 1 according to the present embodiment will be described with reference to FIG. 21 and FIG. 22. FIG. 21 and FIG. 22 show vibration characteristics of the crystal unit 10 predicted using a simulation model of the crystal unit 1 according to the present embodiment. In the simulation model of the crystal unit 1, aluminum is set as the material of the excitation electrode portion 14. In the simulation model of the crystal unit 1, when a voltage is applied to the excitation electrode portion 14, the crystal blank 11 performs thickness-shear vibration in which the crystal blank 11 vibrates in a plane defined by the thickness direction and the first base axis when the direction intersecting the main surface is the thickness direction. FIG. 21 is a graph showing the electromechanical coupling constant of the crystal unit 1 according to the present embodiment. FIG. 22 is a graph showing vibration characteristics of the crystal unit 1 according to the present embodiment. The vibration characteristics of the crystal unit 1 show the vibration shape of the crystal unit 1 during thickness-shear vibration.

[0064] FIG. 21 shows the change in the electromechanical coupling constant of the quartz crystal unit 1 when the ratio of the protrusion amount Tfx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11 is changed. In the example shown in FIG. 21, the vertical axis represents the electromechanical coupling constant, and the horizontal axis represents the ratio of the protrusion amount Tfx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11. In this example, the value of the electromechanical coupling constant is "6.8" in a comparative example corresponding to the case where the quartz crystal blank 11 does not have the first convex portion 14Ca. In contrast, in an example corresponding to the case where the quartz crystal blank 11 has the first convex portion 14Ca, when the ratio is increased stepwise from "0.010", "0.018", "0.025", to "0.035", the value of the electromechanical coupling constant reaches a maximum value of "7.5" when the ratio is "0.018".

[0065] That is, when the first convex portion 14Ca is provided on the excitation electrode portion 14, the speed of sound propagating through the excitation electrode portion 14 is partially reduced due to the mass loading effect. Therefore, during thickness-shear vibration of the crystal blank 11, the wavelength of vibration of the first convex portion 14Ca of the excitation electrode portion 14 becomes relatively shorter than the wavelength of vibration of the flat portion 14B of the excitation electrode portion 14. Then, the distortion occurring in the first convex portion 14Ca of the excitation electrode portion 14 becomes relatively larger than the distortion occurring in the flat portion 14B of the excitation electrode portion 14. As a result, during thickness-shear vibration of the crystal blank 11, distortion is concentrated on the first convex portion 14Ca of the excitation electrode portion 14, and the distortion in the flat portion 14B of the excitation electrode portion 14 is alleviated and the amount of displacement becomes uniform, so that the electromechanical coupling constant of the crystal vibration element 10 increases.

[0066] The example shown in FIG. 22 shows the vibration characteristics of the quartz crystal vibrating element 10 in the example shown in FIG. 21 when the ratio of the protrusion amount Tfx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11 is set so that the value of the electromechanical coupling constant is the maximum value "7.5". FIG. 22 is a diagram showing the displacement amount for each position in the X-axis direction in the quartz crystal vibrating element 10. In the example shown in FIG. 22, a comparative example corresponding to a case where the first convex portion 14Ca is not provided on the quartz crystal blank 11 and an example corresponding to a case where the first convex portion 14Ca is provided on the quartz crystal blank 11 under the above conditions are overlapped. As is clear from the example shown in FIG. 22, the quartz crystal vibrating element 10 of the example has a flatter vibration shape during thickness-shear vibration than the quartz crystal vibrating element 10 of the comparative example, and spurious oscillation, which is a vibration occurring at a frequency other than the main vibration, is suitably reduced.

[0067] Sixth Embodiment In the sixth embodiment, the description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0068] The function of the quartz crystal vibrating element 10 according to this embodiment will be described with reference to FIG. 23 and FIG. 24. FIG. 23 and FIG. 24 show vibration characteristics of the quartz crystal vibrating element 10 predicted using a simulation model of the quartz crystal vibrator 1 according to this embodiment. In the simulation model of the quartz crystal vibrator 1, aluminum is set as the material of the excitation electrode portion 14. In addition, in the simulation model of the quartz crystal vibrator 1, when a voltage is applied to the excitation electrode portion 14, the quartz crystal blank 11 performs thickness-shear vibration in which the quartz crystal blank 11 vibrates in a plane defined by the thickness direction and the first base axis when the direction intersecting the main surface is the thickness direction. FIG. 23 is a graph showing the electromechanical coupling constant of the quartz crystal vibrating element 10 according to this embodiment. FIG. 24 is a graph showing vibration characteristics of the quartz crystal vibrating element 10 according to this embodiment. The vibration characteristics of the quartz crystal vibrating element 10 show the vibration shape of the quartz crystal vibrating element 10 during thickness-shear vibration.

[0069] The example shown in FIG. 23 shows the change in the electromechanical coupling constant of the quartz crystal vibrating element 10 when the ratio of the protrusion amount Tfz of the second convex portion 14Cb to the thickness T of the quartz crystal blank 11 is changed. In the example shown in the figure, the vertical axis represents the electromechanical coupling constant, and the horizontal axis represents the ratio of the protrusion amount Tfz of the second convex portion 14Cb to the thickness T of the quartz crystal blank 11. In this example, in a comparative example corresponding to the case where the second convex portion 14Cb is not provided on the quartz crystal blank 11, the value of the electromechanical coupling constant is "7.5". In contrast, in an example corresponding to the case where the second convex portion 14Cb is provided on the quartz crystal blank 11, when the ratio of the protrusion amount Tfz of the second convex portion 14Cb to the thickness T of the quartz crystal blank 11 is increased stepwise from "0.01", "0.013", "0.020", and "0.025", the value of the electromechanical coupling constant reaches the maximum value "7.5" when the ratio is "0.013".

[0070] That is, when the second convex portion 14Cb is provided on the excitation electrode portion 14, the sound velocity propagating through the excitation electrode portion 14 is partially decreased due to the mass loading effect. Therefore, during thickness-shear vibration of the crystal blank 11, the wavelength of vibration of the second convex portion 14Cb of the excitation electrode portion 14 becomes relatively shorter than the wavelength of vibration of the flat portion 14B of the excitation electrode portion 14. Then, the distortion occurring in the second convex portion 14Cb of the excitation electrode portion 14 becomes relatively larger than the distortion occurring in the flat portion 14B of the excitation electrode portion 14. As a result, during thickness-shear vibration of the crystal blank 11, distortion is concentrated on the second convex portion 14Cb of the excitation electrode portion 14, and the distortion in the flat portion 14B of the excitation electrode portion 14 is alleviated and the amount of displacement becomes uniform, so that the electromechanical coupling constant of the crystal vibration element 10 increases.

[0071] The example shown in FIG. 24 shows the vibration characteristics of the quartz crystal vibrating element 10 in the example shown in FIG. 23 when the ratio of the protrusion amount Tfz of the second convex portion 14Cb to the thickness T of the quartz crystal blank 11 is set so that the value of the electromechanical coupling constant is the maximum value "7.5". FIG. 24 is a diagram showing the displacement amount for each position in the Z-axis direction in the quartz crystal vibrating element 10. In the example shown in FIG. 24, a comparative example corresponding to a case where the second convex portion 14Cb is not provided on the quartz crystal blank 11 and an example corresponding to a case where the second convex portion 14Cb is provided on the quartz crystal blank 11 under the above conditions are overlapped. As is clear from the example shown in FIG. 24, the quartz crystal vibrating element 10 of the example has a flatter vibration shape during thickness-shear vibration than the quartz crystal vibrating element 10 of the comparative example, and spurious oscillation, which is a vibration occurring at a frequency other than the main vibration, is suitably reduced.

[0072] In the examples shown in Fig. 25(a) to Fig. 25(c), examples are described in which the thickness T of the crystal blank 11, the thickness Te of the flat portion 14B of the excitation electrode portion 14, and the thickness Tf of the film thickness portion 14C of the excitation electrode portion 14 are changed as various parameters related to the crystal vibrating element 10. The thickness Tf corresponds to the amount of protrusion of the film thickness portion 14C from the flat portion 14B of the excitation electrode portion 14. Fig. 25(a) is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.05", and the ratio of the protrusion amount Tfz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.013". 25(b) is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is "0.10" and the ratio of the protrusion amount Tfz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is "0.016". FIG. 25(c) is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is "0.20" and the ratio of the protrusion amount Tfz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is "0.021". In any of these examples, when comparing the conditions regarding the protrusion amount Tfx of the first convex portion 14Ca at which the electromechanical coupling constant is maximized with the conditions regarding the protrusion amount Tfz of the second convex portion 14Cb at which the electromechanical coupling constant is maximized, the protrusion amount Tfx of the first convex portion 14Ca is greater than the protrusion amount Tfz of the second convex portion 14Cb.

[0073] In the examples shown in Figs. 26(a) to (c), the thickness T of the quartz crystal blank 11, the thickness Te of the flat portion 14B of the excitation electrode portion 14, and the thickness Tf of the film thickness portion 14C of the excitation electrode portion 14 are changed as various parameters related to the quartz crystal vibrating element 10. Fig. 26(a) is a graph in which the thickness Te of the flat portion 14B of the excitation electrode portion 14 is "0.05 µm". Fig. 26(b) is a graph in which the thickness Te of the flat portion 14B of the excitation electrode portion 14 is "0.10 µm". Fig. 26(c) is a graph in which the thickness Te of the flat portion 14B of the excitation electrode portion 14 is "0.20 µm". In any of these examples, when the condition for the width Wx of the first convex portion 14Ca at which the electromechanical coupling constant is maximized is compared with the condition for the width Wz of the second convex portion 14Cb at which the electromechanical coupling constant is maximized, if the thickness Tf of the film thickness portion 14C of the excitation electrode portion 14 is a common condition, the width Wx of the first convex portion 14Ca is larger than the width Wz of the second convex portion 14Cb. Also, as the thickness Tf of the film thickness portion 14C of the excitation electrode portion 14 increases, the width Wx of the first convex portion 14Ca and the width Wb of the second convex portion 14Cb at which the electromechanical coupling constant is maximized become smaller.

[0074] 27, an example will be described in which the thickness T of the quartz crystal blank 11, the thickness Te of the flat portion 14B of the excitation electrode portion 14, and the thickness Tf of the film thickness portion 14C of the excitation electrode portion 14 are changed as various parameters related to the quartz crystal vibrating element 10. In the graph shown in Fig. 27, the vertical axis indicates the ratio of the total value of the cross-sectional area of ​​the flat portion 14B and the film thickness portion 14C of the excitation electrode portion 14 to the cross-sectional area of ​​the flat portion 14B of the excitation electrode portion 14, and the horizontal axis indicates the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the quartz crystal blank 11. In this graph, in both the first convex portion 14Ca and the second convex portion 14Cb, the ratio of the sum of the cross-sectional areas of the flat portion 14B and the thickness portion 14C of the excitation electrode portion 14 to the cross-sectional area of ​​the flat portion 14B of the excitation electrode portion 14 decreases as the ratio of the thickness Tf of the thickness portion 14C of the excitation electrode portion 14 to the thickness T of the quartz crystal piece 11 increases.

[0075] 28 shows the transition of the change in the electromechanical coupling constant of the quartz crystal unit 1 when the width Wx of the first convex portion 14Ca or the width Wz of the second convex portion 14Cb is fixed and the ratio of the protrusion amount Tfx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11 or the ratio of the protrusion amount Tfz of the second convex portion 14Cb is changed. In the example shown in the figure, the vertical axis represents the electromechanical coupling constant, and the horizontal axis represents the ratio of the protrusion amount Tfx of the first convex portion 14Ca to the thickness T of the quartz crystal blank 11. In this example, the value of the electromechanical coupling constant is "6.8" at the point (Tf / T=0) corresponding to the case where the first convex portion 14Ca or the second convex portion 14Cb is not provided on the excitation electrode portion 14. In contrast, when the first convex portion 14Ca is provided on the excitation electrode portion 14, the value of the electromechanical coupling constant is the maximum value "7.5" at the point (Tf / T=0.013). In this example, the point where (Tf / T=0.013) corresponds to the optimal value of the ratio of the protruding amount Tfx of the first convex portion 14Ca to the thickness T of the crystal blank 11. When the first convex portion 14Ca is provided on the excitation electrode portion 14, the point where (Tf / T=0.018) corresponds to the value of the electromechanical coupling constant "6.8" corresponding to the case where the first convex portion 14Ca or the second convex portion 14Cb is not provided on the excitation electrode portion 14. In this example, the point where (Tf / T=0.018) corresponds to the maximum value of the ratio of the protruding amount Tfx of the first convex portion 14Ca to the thickness T of the crystal blank 11. When the second convex portion 14Cb is provided on the excitation electrode portion 14, the point where (Tf / T=0.020) corresponds to the maximum value of the electromechanical coupling constant "7.3". In this example, the point where (Tf / T=0.020) corresponds to the optimal value of the ratio of the protrusion amount Tfz of the second convex portion 14Cb to the thickness T of the crystal blank 11. Furthermore, when the second convex portion 14Cb is provided on the excitation electrode portion 14, the point where (Tf / T=0.028) corresponds to the value of the electromechanical coupling constant "6.8" corresponding to the case where the first convex portion 14Ca or the second convex portion 14Cb is not provided on the excitation electrode portion 14. In this example, the point where (Tf / T=0.028) corresponds to the maximum value of the ratio of the protrusion amount Tfz of the second convex portion 14Cb to the thickness T of the crystal blank 11 at which the vibration characteristics of the crystal vibrating element 10 satisfy the predetermined condition.The specified condition is met, for example, when the electromechanical coupling constant of the quartz crystal resonator 1 is equal to or greater than that in the case where the quartz crystal resonator 1 does not have the first convex portion 14Ca and the second convex portion 14Cb, and the effect of increasing the electromechanical coupling constant is obtained.

[0076] The example shown in FIG. 29 shows the transition of the change in the maximum value of Tfx / T at which the effect of increasing the electromechanical coupling constant is no longer obtained when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is changed. In this example, a graph is shown in which the width Wx of the first convex portion 14Ca of the excitation electrode portion 14 is "3.5 (μm)", "4.5 (μm)", and "6.0 (μm)". In each case, in this graph, the larger the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11, the larger the maximum value of Tfx / T at which the effect of increasing the electromechanical coupling constant is no longer obtained. In addition, the maximum value of Tfx / T at which the effect of increasing the electromechanical coupling constant is no longer obtained is expressed by a linear function "A×(Te / T)+B" when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is used as a variable.

[0077] The example shown in FIG. 30 shows the transition of the change in the maximum value of Tfz / T at which the effect of increasing the electromechanical coupling constant is no longer obtained when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is changed. In this example, a graph is shown in which the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 is "3.5 (μm)", "4.5 (μm)", and "6.0 (μm)". In each case, in this graph, the larger the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11, the larger the maximum value of Tfz / T at which the effect of increasing the electromechanical coupling constant is no longer obtained. In addition, the maximum value of Tfz / T at which the effect of increasing the electromechanical coupling constant is no longer obtained is expressed by a linear function "A×(Te / T)+B" when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is used as a variable.

[0078] 31 shows the change in coefficient A of the linear function described above when the ratio of the width Wx of the first convex portion 14Ca of the excitation electrode portion 14 or the ratio of the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is changed. In either case, in this example, the coefficient A of the linear function decreases as the ratio of the width Wx of the first convex portion 14Ca of the excitation electrode portion 14 to the thickness T of the crystal piece 11 or the ratio of the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 increases.

[0079] 32 shows the change in coefficient B of the linear function described above when the ratio of the width Wx of the first convex portion 14Ca of the excitation electrode portion 14 or the ratio of the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is changed. In either case, in this example, the coefficient B of the linear function decreases as the ratio of the width Wx of the first convex portion 14Ca of the excitation electrode portion 14 to the thickness T of the crystal piece 11 increases.

[0080] The example shown in FIG. 33 shows the change in the optimal value of Tfx / T at which the electromechanical coupling constant is maximized when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is changed. In this example, a graph is shown for the cases where the width Wx of the first convex portion 14Ca of the excitation electrode portion 14 is "3.5 (μm)", "4.5 (μm)", and "6.0 (μm)". In each case, in this graph, the greater the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11, the greater the optimal value of Tfx / T at which the electromechanical coupling constant is maximized. In addition, the optimal value of Tfx / T at which the electromechanical coupling constant is maximized is expressed by a linear function "A×(Te / T)+B" when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is used as a variable.

[0081] The example shown in FIG. 34 shows the change in the optimal value of Tfz / T at which the electromechanical coupling constant is maximized when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is changed. In this example, a graph is shown for the cases where the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 is "3.5 (μm)", "4.5 (μm)", and "6.0 (μm)". In each case, in this graph, the greater the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11, the greater the optimal value of Tfz / T at which the electromechanical coupling constant is maximized. In addition, the optimal value of Tfz / T at which the electromechanical coupling constant is maximized is expressed by a linear function "A×(Te / T)+B" when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is used as a variable.

[0082] 35 shows the change in coefficient A of the linear function when the ratio of the width Wx of the first convex portion 14Ca or the ratio of the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is changed. In either case, the coefficient A of the linear function decreases as the ratio of the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 increases.

[0083] 36 shows the change in coefficient B of the linear function described above when the ratio of the width Wx of the first convex portion 14Ca or the ratio of the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is changed. In either case, in this example, the coefficient B of the linear function decreases as the ratio of the first convex portion 14Ca or the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 increases.

[0084] Seventh embodiment In the seventh embodiment, the description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0085] 37 shows the change in the electromechanical coupling constant when the cross-sectional area of ​​the first protrusion 14Ca cut along the protruding direction of the first protrusion 14Ca is changed. In this example, a graph is shown for cases where the ratio of the thickness Tf of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.015", "0.020", "0.025", and "0.030". In each case, the graph shows the maximum value of the cross-sectional area of ​​the first protrusion at which the effect of increasing the electromechanical coupling constant is no longer obtained, and the maximum value is approximately constant.

[0086] 38 shows the transition of the change in the maximum value of the cross-sectional area of ​​the first convex portion and the second convex portion at which the increase in the electromechanical coupling constant is no longer obtained when the ratio of the cross-sectional area Sfx of the first convex portion 14Ca of the excitation electrode portion 14 (the cross-sectional area of ​​the first convex portion 14Ca cut in a direction along a plane defined by the first base axis and the thickness direction of the crystal piece 11) or the ratio of the cross-sectional area Sfz of the second convex portion 14Cb (the cross-sectional area of ​​the second convex portion 14Cb cut in a direction along a plane defined by the second base axis and the thickness direction of the crystal piece 11) to the thickness T of the crystal piece 11 is changed. In either case, in this example, the greater the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal piece 11, the greater the maximum value of the cross-sectional area of ​​the first convex portion and the second convex portion at which the increase in the electromechanical coupling constant is no longer obtained. In addition, the maximum value of the cross-sectional area of ​​the first convex portion and the second convex portion at which the effect of increasing the electromechanical coupling constant is no longer obtained is expressed by the linear function “A×(Te / T)+B” when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the quartz crystal piece 11 is used as a variable.

[0087] The example shown in FIG. 39 shows the transition of the change in the optimal value of Wx / T at which the electromechanical coupling constant is maximized when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is changed. In this example, a graph is shown in which the ratio of the protrusion amount Tfx of the first convex portion 14Ca of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.015", "0.020", and "0.030". In each case, in this graph, the greater the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11, the greater the optimal value of Wx / T at which the electromechanical coupling constant is maximized. In addition, the optimal value of Wx / T at which the electromechanical coupling constant is maximized is expressed by a linear function "A×(Te / T)+B" when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is used as a variable.

[0088] The example shown in FIG. 40 shows the transition of the change in the optimal value of Wz / T at which the electromechanical coupling constant is maximized when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is changed. In this example, a graph is shown in which the ratio of the protrusion amount Tfz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.015", "0.020", and "0.030". In each case, in this graph, the greater the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11, the greater the optimal value of Wz / T at which the electromechanical coupling constant is maximized. In addition, the optimal value of Wz / T at which the electromechanical coupling constant is maximized is expressed by a linear function "A×(Te / T)+B" when the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is used as a variable.

[0089] 41 shows the change in coefficient A of the linear function described above when the ratio of the protrusion amount Tfx of the first convex portion 14Ca of the excitation electrode portion 14 or the ratio of the protrusion amount Tfz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is changed. In either case, in this example, the coefficient A of the linear function becomes smaller as the ratio of the protrusion amount Tfx of the first convex portion 14Ca of the excitation electrode portion 14 to the thickness T of the crystal piece 11 or the ratio of the protrusion amount Tfz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 increases.

[0090] 42 shows the change in coefficient B of the linear function described above when the ratio of the protrusion amount Tfx of the first convex portion 14Ca of the excitation electrode portion 14 or the ratio of the protrusion amount Tfz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the crystal piece 11 is changed. In either case, in this example, the coefficient B of the linear function becomes smaller as the ratio of the protrusion amount Tfx of the first convex portion 14Ca of the excitation electrode portion 14 to the thickness T of the crystal piece 11 or the ratio of the protrusion amount Tfz of the second convex portion 14Cb of the excitation electrode portion 14 becomes larger.

[0091] In the examples shown in Figs. 43(a) to (c), the thickness T of the crystal blank 11, the thickness Te of the flat portion 14B of the excitation electrode portion 14, and the thickness Tf of the film thickness portion 14C of the excitation electrode portion 14 are changed as various parameters related to the crystal vibrating element 10. The thickness Tf corresponds to the amount of protrusion of the film thickness portion 14C from the flat portion 14B of the excitation electrode portion 14. Fig. 43(a) is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.05". Fig. 43(b) is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.10". Fig. 43(c) is a graph in which the ratio of the thickness Te of the flat portion 14B of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.20". In any of these examples, when the condition regarding the ratio of the cross-sectional area of ​​the first convex portion 14Ca at which the electromechanical coupling constant is maximized is compared with the condition regarding the ratio of the cross-sectional area of ​​the second convex portion 14Cb at which the electromechanical coupling constant is maximized, the cross-sectional area of ​​the first convex portion 14Ca is larger than the cross-sectional area of ​​the second convex portion 14Cb.

[0092] The example shown in FIG. 44 shows the change in the Q value, which is a parameter indicating the vibration state of the crystal unit 1, when the ratio of the cross-sectional area Sfz of the second convex portion 14Cb of the excitation electrode portion 14 to the cross-sectional area Sfx of the first convex portion 14Ca of the excitation electrode portion 14 is changed. In this example, a graph is shown in which the ratio of the cross-sectional area Sfx of the first convex portion 14Ca of the excitation electrode portion 14 to the thickness T of the crystal blank 11 is "0.06", "0.08", "0.10", and "0.12". In each case, when the value of Sfz / Sfx exceeds "1.0", the Q value drops sharply. In other words, when the cross-sectional area Sfz of the second convex portion 14Cb of the excitation electrode portion 14 becomes larger than the cross-sectional area Sfx of the first convex portion 14Ca, the Q value drops sharply. Therefore, by making the cross-sectional area Sfx of the first convex portion 14Ca of the excitation electrode portion 14 larger than the cross-sectional area Sfz of the second convex portion 14Cb, the vibration characteristics of the quartz crystal resonator 1 can be improved.

[0093] The example shown in FIG. 45 shows the change in the Q value, which is a parameter indicating the vibration state of the quartz crystal unit 1, when the ratio of the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 to the thickness T of the quartz crystal blank 11 is changed. In this example, a graph is shown in which the ratio of the width Wx of the first convex portion 14Ca of the excitation electrode portion 14 to the thickness T of the quartz crystal blank 11 is "1.0", "2.0", "3.0", and "4.3". In each case, when the width Wz of the second convex portion 14Cb of the excitation electrode portion 14 becomes larger than the width Wx of the first convex portion 14Ca, the Q value drops sharply. Therefore, by making the width Wx of the first convex portion 14Ca of the excitation electrode portion 14 larger than the width Wz of the second convex portion 14Cb, the vibration characteristics of the quartz crystal unit 1 can be improved.

[0094] The following describes some or all of the embodiments of the present invention and their effects. Note that the present invention is not limited to the following descriptions.

[0095] According to one aspect of the present invention, a crystal element having a principal surface defined by a first basis axis and a second basis axis intersecting the first basis axis, and an excitation electrode portion provided on the principal surface of the crystal element, the crystal element performs thickness-shear vibration in which the crystal element vibrates in a plane defined by the thickness direction and the first basis axis when a voltage is applied to the excitation electrode portion and the direction intersecting the principal surface is defined as the thickness direction, the excitation electrode portion has a flat portion and a thickness portion located at an electrode end in a direction along the principal surface of the crystal element and having a thickness greater than that of the flat portion, the thickness portion being a thickness of the flat portion on the principal surface. the first convex portion is located at an axial end of the first base axis and serves as a convex portion protruding from a flat portion extending in the axial direction of the second base axis, and the second convex portion is located at an axial end of the second base axis on the main surface and serves as a convex portion protruding from the flat portion extending in the axial direction of the first base axis, wherein a cross-sectional area of ​​the first convex portion cut in a direction along a plane defined by the first base axis and a thickness direction of the quartz piece is larger than a cross-sectional area of ​​the second convex portion cut in a direction along a plane defined by the second base axis and the thickness direction of the quartz piece.

[0096] According to one embodiment of the present invention, a quartz crystal vibration element is provided in which the first convex portion and the second convex portion are made of aluminum, and the greater the ratio of the thickness of the flat portion to the thickness of the quartz crystal piece, the greater the maximum cross-sectional area of ​​the first convex portion and the second convex portion at which the vibration characteristics of the quartz crystal vibration element satisfy predetermined conditions.

[0097] According to one embodiment of the present invention, a quartz crystal vibration element is provided in which the maximum cross-sectional area of ​​the first convex portion and the second convex portion at which the vibration characteristics of the quartz crystal vibration element satisfy predetermined conditions is expressed as a linear function having as a variable the ratio of the thickness of the flat portion to the thickness of the quartz crystal piece.

[0098] According to one aspect of the present invention, a quartz vibration element is provided, in which the width of the first convex portion in a direction intersecting the protruding direction of the first convex portion is greater than the width of the second convex portion in a direction intersecting the protruding direction of the second convex portion.

[0099] According to one embodiment of the present invention, a quartz crystal vibration element is provided in which the first convex portion and the second convex portion are made of aluminum, and the greater the ratio of the thickness of the flat portion to the thickness of the quartz crystal piece, the greater the maximum width of the first convex portion and the second convex portion at which the vibration characteristics of the quartz crystal vibration element satisfy predetermined conditions.

[0100] According to one embodiment of the present invention, a quartz crystal vibration element is provided in which the maximum width of the first convex portion and the second convex portion at which the vibration characteristics of the quartz crystal vibration element satisfy specified conditions is expressed as a linear function with the ratio of the thickness of the flat portion to the thickness of the quartz crystal piece as a variable.

[0101] According to one aspect of the present invention, there is provided a quartz crystal vibrating element, in which the protrusion amount of the first convex portion is greater than the protrusion amount of the second convex portion.

[0102] According to one aspect of the present invention, there is provided a quartz vibration element comprising: a quartz crystal piece having a principal surface defined by a first base axis and a second base axis intersecting the first base axis; and an excitation electrode portion provided on the principal surface of the quartz crystal piece, wherein when a voltage is applied to the excitation electrode portion, the quartz crystal piece performs thickness-shear vibration in which the quartz crystal piece vibrates in a plane defined by the thickness direction and the first base axis when the direction intersecting the principal surface is defined as the thickness direction, and the excitation electrode portion has a flat portion and a thickness portion located at an electrode end in a direction along the principal surface of the quartz crystal piece and having a thickness greater than that of the flat portion, and the thickness portion is located at an end of the principal surface in the axial direction of the first base axis, and has a first convex portion as a convex portion extending in the axial direction of the second base axis.

[0103] According to one aspect of the present invention, there is provided a quartz vibration element comprising: a quartz crystal piece having a main surface defined by a first base axis and a second base axis intersecting the first base axis; and an excitation electrode portion provided on the main surface of the quartz crystal piece, wherein when a voltage is applied to the excitation electrode portion, the quartz crystal piece performs thickness-shear vibration in which the quartz crystal piece vibrates in a plane defined by the thickness direction and the first base axis when the direction intersecting the main surface is defined as the thickness direction, and the excitation electrode portion has a flat portion and a thickness portion located at an electrode end in a direction along the main surface of the quartz crystal piece and having a thickness greater than that of the flat portion, and the thickness portion is located at an end of the main surface in the axial direction of the second base axis, and has a second convex portion as a convex portion extending in the axial direction of the first base axis.

[0104] In one embodiment, a quartz crystal vibration element is provided in which, when the third axis is tilted at a predetermined angle around the first axis as a third tilt axis, out of the first axis, second axis, and third axis which are intersecting crystal axes of the quartz crystal piece, the first axis corresponds to the first base axis and the third tilt axis corresponds to the second base axis.

[0105] In one embodiment, a quartz crystal vibration element is provided in which, when the first axis is tilted at a predetermined angle around the third axis as the first tilt axis, and the third axis is tilted at a predetermined angle around the first tilt axis as the third tilt axis, the first tilt axis corresponds to the first base axis and the third tilt axis corresponds to the second base axis, among the first axis, second axis, and third axis which are intersecting crystal axes of the quartz crystal piece, the first tilt axis corresponds to the first base axis and the third tilt axis corresponds to the second base axis.

[0106] In one aspect, there is provided a quartz crystal vibration element, in which the convex portion is made of the same material as the flat portion of the excitation electrode portion.

[0107] In one aspect, a quartz crystal vibration element is provided, in which the convex portion is made of a material different from that of the flat portion of the excitation electrode portion.

[0108] In one aspect, there is provided a quartz crystal vibration element, in which the protrusion is made of an insulating material.

[0109] As described above, according to one aspect of the present invention, spurious oscillation can be further reduced.

[0110] The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention may be modified / improved without departing from the spirit thereof, and equivalents are also included in the present invention. That is, those in which a person skilled in the art appropriately adds design changes to each embodiment are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements and their arrangements, materials, conditions, shapes, sizes, etc. of each embodiment are not limited to those exemplified, and can be appropriately changed. In addition, the elements of each embodiment can be combined to the extent technically possible, and those combinations of these are also included in the scope of the present invention as long as they include the characteristics of the present invention. [Explanation of symbols]

[0111] 1...Crystal resonator 10...Crystal vibration element 11...Crystal piece 14a, 14b...Excitation electrode 15a, 15b...Extraction electrode 16a, 16b...Connection electrodes 30...Base member 33a, 33b...electrode pads 34a, 34b...Through electrode 35a~35d...External electrode 36a, 36b...conductive holding members 40…Cover member 50...Jointing material.

Claims

1. a quartz crystal piece having a major surface defined by a first base axis and a second base axis intersecting the first base axis; an excitation electrode portion provided on a main surface of the quartz crystal piece; When a voltage is applied to the excitation electrode portion, the quartz crystal piece performs thickness-shear vibration in which the quartz crystal piece vibrates in a plane defined by the thickness direction and the first base axis when a direction intersecting the main surface is defined as a thickness direction, and The excitation electrode portion has a flat portion and a thickness portion that is located at an electrode end in a direction along the main surface of the crystal piece and has a thickness larger than that of the flat portion, the thickness portion is a first convex portion located at an end of the main surface in the axial direction of the first base axis and protruding from the flat plate portion extending in the axial direction of the second base axis; a second convex portion located at an end of the main surface in the axial direction of the second base axis and protruding from the flat plate portion extending in the axial direction of the first base axis; having When the cross-sectional area of ​​the first convex portion is Sfx, the cross-sectional area of ​​the second convex portion is Sfz, the thickness of the quartz crystal piece is T, and the thickness of the flat portion is Te, 0<Sfx / T 2≦0.84×(Te / T)+0.07 and, 0<Sfz / T 2≦0.29×(Te / T)+0.07 Fulfilling the conditions of The first convex portion and the second convex portion are made of aluminum. Quartz crystal element.

2. a width of the first convex portion in a direction intersecting a protruding direction of the first convex portion is larger than a width of the second convex portion in a direction intersecting a protruding direction of the second convex portion; The quartz crystal resonator element according to claim 1 .

3. A protruding amount of the first convex portion is greater than a protruding amount of the second convex portion. The quartz crystal resonator element according to claim 1 .

4. a cross-sectional area of ​​the first convex portion cut in a direction along a plane defined by the first base axis and a thickness direction of the crystal piece is larger than a cross-sectional area of ​​the second convex portion cut in a direction along a plane defined by the second base axis and a thickness direction of the crystal piece; The quartz crystal resonator element according to claim 1 .

5. a quartz crystal piece having a major surface defined by a first base axis and a second base axis intersecting the first base axis; An excitation electrode portion provided on the main surface of the crystal piece; Equipped with When a voltage is applied to the excitation electrode portion, the quartz crystal piece performs thickness-shear vibration in which the quartz crystal piece vibrates in a plane defined by the thickness direction and the first base axis when a direction intersecting the main surface is defined as a thickness direction, The excitation electrode portion has a flat portion and a thickness portion that is located at an electrode end in a direction along the main surface of the crystal piece and has a thickness larger than that of the flat portion, The thickness portion is A protrusion protruding from the flat plate portion is provided. the protrusion includes only a protrusion extending in the axial direction of the second base shaft, the protrusion is located at an end of the main surface in an axial direction of the first base shaft, When the cross-sectional area of ​​the convex portion is Sfx, the thickness of the crystal piece is T, and the thickness of the flat portion is Te, 0<Sfx / T 2≦0.84×(Te / T)+0.07 Fulfilling the conditions of The material of the protrusion is aluminum. Quartz crystal element.

6. a quartz crystal piece having a major surface defined by a first base axis and a second base axis intersecting the first base axis; An excitation electrode portion provided on the main surface of the crystal piece; Equipped with When a voltage is applied to the excitation electrode portion, the quartz crystal piece performs thickness-shear vibration in which the quartz crystal piece vibrates in a plane defined by the thickness direction and the first base axis when a direction intersecting the main surface is defined as a thickness direction, The excitation electrode portion has a flat portion and a thickness portion that is located at an electrode end in a direction along the main surface of the crystal piece and has a thickness larger than that of the flat portion, The thickness portion is A protrusion protruding from the flat plate portion is provided. the protrusion includes only a protrusion extending in the axial direction of the first base shaft, the protrusion is located at an end of the main surface in the axial direction of the second base shaft, When the cross-sectional area of ​​the convex portion is Sfz, the thickness of the quartz crystal piece is T, and the thickness of the flat portion is Te, 0<Sfz / T 2≦0.29×(Te / T)+0.07 Fulfilling the conditions of The material of the protrusion is aluminum. Quartz crystal element.

7. Among the first axis, the second axis, and the third axis which are the crystal axes of the quartz crystal blank and intersect with each other, when the third axis is inclined at a predetermined angle around the first axis to be defined as a third inclination axis, the first axis is made to correspond to the first base axis and the third inclination axis is made to correspond to the second base axis; The quartz crystal resonator element according to claim 1 .

8. Among the first axis, the second axis, and the third axis which are the crystal axes of the quartz crystal blank and intersect with each other, an axis obtained by tilting the first axis around the third axis by a predetermined angle is defined as a first tilt axis, and an axis obtained by tilting the third axis around the first tilt axis by a predetermined angle is defined as a third tilt axis, the first tilt axis is made to correspond to the first base axis, and the third tilt axis is made to correspond to the second base axis. The quartz crystal resonator element according to claim 1 .

9. The convex portion is made of the same material as the flat plate portion of the excitation electrode portion. The quartz crystal resonator element according to claim 1 .

10. The convex portion is made of a material different from that of the flat plate portion of the excitation electrode portion. The quartz crystal resonator element according to claim 1 .

11. The quartz crystal vibration element according to claim 1 , A base member on which the crystal vibration element is mounted; a cover member that is bonded to the base member and seals the crystal vibration element; A quartz crystal oscillator comprising:

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