JP2001057515A - Thickness longitudinal piezoelectric resonator and piezoelectric resonator component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thickness longitudinal piezoelectric resonator of an energy confinement type that obtains an excellent resonance characteristic with less frequency dispersion and utilizes a harmonic mode of a thickness longitudinal vibration mode. SOLUTION: In an energy confinement type piezoelectric resonator 1 where a plurality of internal electrodes is formed in a piezoelectric body and utilizes a harmonic mode of a thickness longitudinal vibration mode where electric fields of opposite polarity are alternately applied to a piezoelectric layer between the internal electrodes in the broadwise direction, relations of 0.50 <=(D1+D2)/2D<=1.00 in the case of N=3, 0.45<=(D1+D2)/2D<=0.75 in the case of N=4, and 0.45<=(D1+D2)/2D<=0.60 in the case of N=5 hold, where D is a thickness of a piezoelectric layer between internal electrodes 2, 3 adjacent in the thickness direction and D1, D2 are thickness of 1st and 2nd piezoelectric layers 2c, 2d outward from the outermost internal electrodes in the thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickness extensional piezoelectric resonator and a piezoelectric resonance component used for various resonators, oscillators, and the like, and more particularly, to a thickness extensional using a harmonic in a thickness extensional vibration mode. The present invention relates to a piezoelectric resonator and a piezoelectric resonance component.

[0002]

2. Description of the Related Art Piezoelectric resonators are used in various piezoelectric resonance components such as piezoelectric oscillators, discriminators, and piezoelectric filters. As this kind of piezoelectric resonator, those utilizing various piezoelectric vibration modes according to the operating frequency are known.

[0003] Japanese Patent Publication No. 404041/1988 discloses an energy trap type piezo-resonator utilizing a higher-order mode of thickness longitudinal vibration. That is, in the piezoelectric ceramic, a plurality of internal electrodes are arranged so as to overlap with each other with a piezoelectric layer interposed therebetween, and the piezoelectric layers between the internal electrodes are alternately polarized in different directions in the thickness direction. Child is disclosed.

[0004]

However, in the above-mentioned prior art, it is disclosed that a plurality of internal electrodes are arranged in the piezoelectric body to utilize the harmonics in the thickness longitudinal vibration mode. Only specific examples are shown for forming positions. That is, in the above prior art, a piezoelectric resonator in which the distance between adjacent internal electrodes is 73 μm and the thickness of the entire piezoelectric body is 259 μm or 257 μm is shown as an example of the piezoelectric resonator using the tertiary thickness longitudinal vibration mode. It is just being done.

In the thickness extensional piezoelectric resonator utilizing the harmonics in the thickness extensional vibration mode as described above, the resonator is processed from a mother piezoelectric substrate. However, since the mother piezoelectric substrate has warpage or the like, planar polishing is often performed. Therefore, the position of the internal electrode in the piezoelectric substrate in the thickness direction tends to vary, and the frequency tends to vary. In particular, the above-mentioned frequency fluctuation appears more remarkably in a thickness longitudinal piezoelectric resonator used at a high frequency, which is a great hindrance to a higher frequency.

An object of the present invention is to provide an energy confinement type thickness longitudinal piezoelectric resonator utilizing harmonics in the thickness longitudinal vibration mode, which can effectively improve frequency accuracy and can cope with a higher frequency. It is an object of the present invention to provide a thickness vertical piezoelectric resonator and a piezoelectric resonance component.

[0007]

According to a first aspect of the present invention, there is provided a piezoelectric body uniformly polarized in a thickness direction, and the piezoelectric body is disposed so as to overlap in the thickness direction via a piezoelectric layer in the piezoelectric body. (N-1) in a thickness longitudinal vibration mode in which N internal electrodes (N is a natural number of 3 to 5) and electric fields of opposite polarities are alternately applied in the thickness direction to the piezoelectric layers between the internal electrodes. In the energy trap type piezoelectric resonator using the next higher-order mode, the thickness of the piezoelectric layer between the internal electrodes adjacent in the thickness direction is D, and the first and outer layers are located outside the outermost internal electrodes in the thickness direction.
When the thickness of the second piezoelectric layer is D ₁ and D ₂ , N =
When 0.5, 0.50 ≦ (D ₁ + D ₂ ) /2D≦1.0
0, N = 4, 0.45 ≦ (D ₁ + D ₂ ) / 2D ≦
When 0.75 and N = 5, 0.45 ≦ (D ₁ + D ₂ ) /
2D ≦ 0.60.

A second invention of the present application is directed to a piezoelectric body and N (N is a natural number of 3 to 5) internal electrodes arranged in the piezoelectric body so as to overlap in the thickness direction via a piezoelectric layer. And the piezoelectric layer between the internal electrodes is alternately polarized in the thickness direction in the opposite direction, and the thickness longitudinal vibration mode (N−
1) In the energy trap type piezoelectric resonator using the next higher-order mode, the thickness of the piezoelectric layer between the internal electrodes adjacent in the thickness direction is D, and the thickness of the first and third piezoelectric layers outside the outermost internal electrode in the thickness direction is D. When the thickness of the piezoelectric layer 2 is D ₁ and D ₂ , when N = 3, 0.60 ≦ (D ₁ + D ₂ ) / 2D
0.70 ≦ (D ₁ + D ₂ ) when ≦ 1.10 and N = 4
When ₁ / 2D ≦ 0.90 and N = 5, 0.65 ≦ (D ₁ +
D ₂ ) /2D≦0.80.

Further, in the first and second inventions (hereinafter collectively referred to as the present invention), preferably, the plurality of internal electrodes have a linear shape and intersect via a piezoelectric layer.
In this case, the intersections constitute an energy trapping type piezoelectric vibrating section.

Further, the thickness extensional piezoelectric resonator of the present invention can be suitably used as a piezoelectric oscillator. Further, the piezoelectric resonance component provided in a specific aspect of the present invention is a thickness vertical piezoelectric resonator according to the present invention, and a thickness vertical piezoelectric resonator separated by a space for preventing vibration of the thickness vertical piezoelectric resonator. And a bonded capacitor substrate.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 (a) and (b)
1 is a perspective view and a sectional view for explaining a thickness extensional piezoelectric resonator according to a first embodiment of the present invention.

The thickness vertical piezoelectric resonator 1 has a rectangular parallelepiped piezoelectric body 2 made of piezoelectric ceramics such as lead titanate zirconate ceramics, or a piezoelectric single crystal such as quartz or LiTaO ₃ . Inside the piezoelectric body 2, a plurality of internal electrodes 3 to 6 are arranged so as to overlap in the thickness direction via a piezoelectric body layer.

The piezoelectric body 2 is uniformly polarized in the thickness direction as indicated by an arrow P. Internal electrodes 3, 5
Are drawn out to one end face 2a of the piezoelectric body 2, and the internal electrodes 4 and 6 are drawn out to an end face 2b opposite to the end face 2a.

External electrodes 7, 8 are formed so as to cover the end faces 2a, 2b. The external electrodes 7 and 8 are formed by applying and curing a conductive paste, or by sputtering, depositing, or plating a metal material.

The external electrode 7 is electrically connected to the internal electrodes 3 and 5, and the external electrode 8 is electrically connected to the internal electrodes 4 and 6. In the thickness extensional piezoelectric resonator 1 of this embodiment, when an AC electric field is applied between the external electrodes 7 and 8, the piezoelectric layer between the internal electrodes 3 and 4 and the piezoelectric layer between the internal electrodes 4 and 5 When the AC electric field is applied, an electric field of the opposite polarity is applied. Similarly, a piezoelectric layer between the internal electrodes 4 and 5 and a piezoelectric layer between the internal electrodes 5 and 6 are alternately applied with electric fields of opposite polarities. Therefore, the portion where the internal electrodes 3 to 6 overlap in the thickness direction resonates, and operates as an energy trapping type thickness vertical piezoelectric resonator. In this case, since the number of laminated internal electrodes is four, the device operates as a thickness longitudinal piezoelectric resonator utilizing the third harmonic of the thickness longitudinal vibration mode.

A thickness longitudinal piezoelectric resonator in which a piezoelectric body is uniformly polarized and a piezoelectric layer between adjacent internal electrodes is alternately applied with an electric field of opposite polarity in the thickness direction is referred to as a parallel type. A connection-type thickness longitudinal piezoelectric resonator is used.

In the thickness longitudinal piezoelectric resonator 1 of this embodiment, the piezoelectric body 2 can be obtained by using a well-known ceramic integral firing technique. For example, as shown in FIG. 2, a plurality of green sheets 9a to 9e mainly composed of piezoelectric ceramics are prepared. On the green sheets 9b to 9e, linear internal electrodes 3 to 6 are formed by screen printing of a conductive paste as shown in the figure. Thereafter, the green sheets 9a to 9e are stacked, pressed in the thickness direction, and then fired, whereby the piezoelectric body 2 can be obtained.

In the present embodiment, the internal electrodes 3 to 6 have a linear shape except for a portion extending to the edge of the green sheet. Therefore, the portion where the internal electrodes 3 to 6 overlap in the thickness direction is constituted by the portion where the linear electrodes cross each other. Therefore, the area of the energy trapping type piezoelectric vibrating portion can be easily adjusted by adjusting the intersecting region of the internal electrodes 3 to 6, and can be finely adjusted. Accordingly, it is possible to easily form an energy trapping type piezoelectric vibrating portion having a small area in response to the increase in frequency.

Next, the features of the thickness extensional piezoelectric resonator 1 of this embodiment will be described. In the thickness extensional piezoelectric resonator 1 of the present embodiment, the first and second portions outside the portion where the plurality of internal electrodes 3 to 6 overlap, that is, outside the outermost internal electrodes 3 or 6.
When the thickness of the piezoelectric layers 2c and 2d is D ₁ and D ₂ and the thickness of the piezoelectric layer between the internal electrodes adjacent in the thickness direction, for example, between the internal electrodes 3 and 4, is D, Piezoelectric layer 2
The thicknesses of c and 2d are selected so as to satisfy the following expression (1).

0.45 ≦ (D ₁ + D ₂ ) /2D≦0.75 (1) In the thickness longitudinal piezoelectric resonator of this embodiment, the first and second piezoelectric resonators satisfy the expression (1). Since the thicknesses of the piezoelectric layers 2c and 2d are selected, variations in the resonance frequency or the anti-resonance frequency can be effectively reduced. Hereinafter, this will be described.

When manufacturing the vertical piezoelectric resonator 1, the thickness of the first and second piezoelectric layers 2c and 2d of the piezoelectric body 2 is ideally equal. That is, it is desirable that the internal electrodes 3 to 6 be arranged so that D ₁ = D ₂ .

However, usually, the piezoelectric body 2 is obtained by cutting the mother piezoelectric substrate. However,
A slight warpage may occur in the mother piezoelectric substrate, and the upper surface and / or the lower surface are usually polished at the mother piezoelectric substrate stage in order to improve the flatness.

Due to the warpage of the mother substrate and the variation in the amount of polishing on the upper surface and / or the lower surface during planar polishing, the portion where the internal electrodes 3 to 6 are laminated tends to deviate from the ideal position described above. .

For example, as shown in FIG.
Since the thickness D of each piezoelectric layer between the internal electrodes 4 and 5 and between the internal electrodes 5 and 6 substantially corresponds to the thickness of the prepared green sheet, it can be constant. However, when the piezoelectric body 2 is obtained from the piezoelectric substrate, the thicknesses D ₁ , D _{2 of} the first and second piezoelectric layers 2c, 2d may vary due to variations in the amount of polishing of the upper and lower surfaces and the warpage of the mother piezoelectric substrate.
Tended to vary. The broken line A in FIG.
Indicates ideal positions of the internal electrodes 3 to 6. In addition, the shift amount of the internal electrodes 3 to 6 from the ideal position is dD.

The inventor of the present application has found that when the positions of the internal electrodes 3 to 6 in the thickness direction deviate from the ideal positions, the resonance frequency and the antiresonance frequency change, and the degree of this change is the first and the outermost layers. The inventors have found that the thickness depends on the thicknesses of the second piezoelectric layers 2c and 2d, and have accomplished the present invention.

That is, as described above, the piezoelectric body 2
In the case of the thickness longitudinal piezoelectric resonator 1 having three internal electrodes 3 to 6 and utilizing the third harmonic, the piezoelectric layers 2c and 2d may be formed so as to satisfy the above-described expression (1). I found that.

The inventor of the present application changed the number of laminated internal electrodes in various ways and similarly confirmed the results by experiments. As shown in FIG. 7, the thickness of the parallel connection type using the second harmonic wave as the second embodiment is shown in FIG. It has been found that in the vertical piezoelectric resonator 11, the piezoelectric layers 2c and 2d may be formed so as to satisfy the following expression (2).

0.50 ≦ (D ₁ + D ₂ ) /2D≦1.00 (2) Further, 4 as a third embodiment shown in a sectional view in FIG.
Parallel connection type thickness longitudinal piezoelectric resonator 21 utilizing harmonics 21
Has found that frequency fluctuation can be suppressed by controlling the thickness of the outermost piezoelectric layers 2c and 2d so as to satisfy the following expression (3).

0.45 ≦ (D ₁ + D ₂ ) /2D≦0.60 (3) The thickness longitudinal piezoelectric resonator 1 utilizing the second harmonic shown in FIG.
In No. 1, three internal electrodes 12 to 14 are arranged so as to overlap in the thickness direction via a piezoelectric layer.

In the thickness vertical piezoelectric resonator 21 using the fourth harmonic shown in FIG. 8, five internal electrodes 22 to 26 are arranged so as to overlap in the thickness direction via the piezoelectric layer. Further, in the thickness vertical piezoelectric resonators 11 and 21, the piezoelectric body 2
Since the inside is of a parallel connection type, it is uniformly polarized in the direction of arrow P.

The thickness extensional piezoelectric resonators 11 and 21 are configured in the same manner as the thickness extensional piezoelectric resonator 1 of the first embodiment, except that the number of laminated internal electrodes and the higher order mode used are different. .

Next, specific experimental examples will be described. 2
As the thickness longitudinal piezoelectric resonator 11 using the harmonic, the thickness longitudinal piezoelectric resonator 1 using the third harmonic, and the thickness longitudinal piezoelectric resonator 21 using the fourth harmonic, the piezoelectric body is made of a PT-based ceramic. The area of the electrode intersection, that is, the area of the energy trapping type vibrating part is 0.025 mm ² , the thickness D of the piezoelectric layer between adjacent internal electrodes is 40 μm, and the first and second outermost layers D ₁ and D ₂ Are equal in thickness (this is D '
), And the rate of change of the oscillation frequency _FOSC when D '/ D was varied variously. The results are shown in FIGS.

FIG. 13 shows the result in the case of the thickness extensional piezoelectric resonator 11 using the second harmonic, FIG. 14 shows the result in the case of the thickness extensional piezoelectric resonator 1 using the third harmonic, and FIG. The result in the case of the thickness extensional piezoelectric resonator 21 using the harmonic is shown.

In FIG. 13, the horizontal axis represents the ratio (percentage) of the displacement dD in the thickness direction of the internal electrode to the thickness D of one piezoelectric layer sandwiched between the internal electrodes. dD is
This corresponds to the displacement of the internal electrode forming position in the thickness extensional piezoelectric resonator 1 using the third harmonic shown in FIG. FIG.
The vertical axis indicates the oscillation frequency variation dF _OSC (= the actual measurement value of the oscillation frequency−F when the ideal oscillation frequency F _OSC is used).
_OSC = dF _OSC ) to the oscillation frequency F _OSC (percentage).

The solid line A in FIG. 13 is D '/ D = 1.2.
, The dashed-dotted line B represents the case of D '/ D = 1.0, the dashed-dotted line C represents the case of D' / D = 0.8, and the three-dot dashed line D represents D '/ D = 0.6. , The broken line E is D '/ D = 0.4
And the broken line F shows the result when D '/ D = 0.2.

FIG. 13 shows the result of rewriting the result of FIG. 13 with the ratio (D ′ / D) of the thickness D ′ of the outermost first and second piezoelectric layers 2 c and 2 d to the thickness D (D ′ / D) as the horizontal axis. This is shown in FIG. In FIG. 16, the change rate of the oscillation frequency on the vertical axis is also normalized by dD / D.

On the other hand, it is necessary that the initial tolerance of the resonance frequency of the piezoelectric resonator has an accuracy in the range of ± 0.2%. Therefore, as is apparent from FIG. 16, in order to keep the fluctuation rate of the oscillation frequency within ± 0.2%, D ′ / D, that is, (D ₁ + D ₂ ) / 2D is set to a range of 0.50 or more. It turns out that it is good.

FIG. 14 shows the results when the thicknesses of the first and second piezoelectric layers 2c and 2d are variously changed in the third harmonic thickness longitudinal piezoelectric resonator 1. In FIG. 14, solid line A, dashed-dotted line B, dashed-dotted line C, dashed-dotted line D, dashed line E and dashed line F have D '/ D of 1.2, respectively.
It corresponds to the cases of 1.0, 0.8, 0.6, 0.4 and 0.2. FIG. 17 is a diagram in which the result shown in FIG. 14 is rewritten, and FIG.
FIG. 6 is a diagram corresponding to FIG.

FIG. 15 shows the results when the thicknesses of the first and second piezoelectric layers are variously changed in the thickness extensional piezoelectric resonator 21 using the fourth harmonic. In FIG.
Solid line A, chain line B, chain line C, chain line D, broken line E
And dashed line F indicate that D '/ D is 1.2, 1..
The cases of 0, 0.8, 0.6, 0.4 and 0.2 are shown.
FIG. 18 is a diagram in which the result of FIG. 15 is rewritten.
FIG. 17 is a view corresponding to FIG. 16 regarding a thickness longitudinal piezoelectric resonator using a second harmonic.

As is apparent from FIGS. 17 and 18, 3
In the thickness extensional piezoelectric resonators 1 and 21 using the harmonic and the fourth harmonic, the first and second outermost piezoelectric layers 2c and 2c are set so as to satisfy the above-described equations (1) and (3). It can be seen that controlling the thickness of 2d allows the oscillation frequency to be in the range of ± 0.2%.

In the expression (2), the upper limit of (D ₁ + D ₂ ) / 2D is set to 1.00 in the thickness extensional piezoelectric resonator using the second harmonic. The reason will be described with reference to FIG.

FIG. 19 shows the first and second piezoelectric layers 2c and 2c.
is a diagram showing the relationship between the thickness D _1, D ₂ and fractional bandwidth of d, (a) for the second harmonic, (b) shows the results for the fourth harmonic as a spurious. Outermost piezoelectric layer 2
As the thicknesses of c and 2d are larger, the fractional band of the second harmonic is smaller and the fractional band of the fourth harmonic is greater. Since the fourth harmonic is spurious, it cannot be used as an oscillator if the ratio band of the fourth harmonic is large. Therefore, the upper limit of D '/ D, that is, (D ₁ + D ₂ ) / 2D is 1.0 in the thickness extensional piezoelectric resonator 11 using the second harmonic. For the same reason, in the thickness extensional piezoelectric resonator 1 using the third harmonic, FIG.
From (a) and (b), D '/ D, that is, (D ₁ + D ₂ )
The upper limit of / 2D is 0.9 in the thickness longitudinal piezoelectric resonator 21 using the fourth harmonic, and is 0.8 from FIGS. 21 (a) and 21 (b).

However, in each of the thickness longitudinal piezoelectric resonators 1 and 21 utilizing the third harmonic and the fourth harmonic, the upper limit obtained from the above-mentioned frequency change is lower, so that (D ₁ + D ₂ ) / 2.
D has upper limits of 0.75 and 0.60, respectively, as shown in equations (1) and (3).

In high frequency applications, the thickness D of one piezoelectric layer sandwiched between the internal electrodes is small. Therefore, in the case of the same processing accuracy, dD / D increases and the frequency accuracy deteriorates. However, according to this embodiment, by selecting the thicknesses of the outermost piezoelectric layers 2c and 2d within the above specific range, it is possible to effectively reduce the influence on the change in the oscillation frequency due to the displacement of the internal electrodes. it can.

In the above-described embodiment, the so-called parallel connection type thickness vertical piezoelectric resonators 1, 11, 21 have been described. However, in the second invention of the present application, a series type thickness vertical piezoelectric resonator is used. This is shown in FIGS. Although the external electrodes are not shown in FIGS. 9 to 11, a pair of external electrodes are provided so as to cover the end surfaces 2a and 2b of the piezoelectric body 2 similarly to the external electrodes 7 and 8 in FIG. An electrode is formed.

In the thickness extensional piezoelectric resonator 31 of the fourth embodiment shown in FIG. 9, three internal electrodes 32 to 34 are provided in the piezoelectric body 2.
Are arranged so as to overlap via the piezoelectric layer.
The central internal electrode 33 is a non-connection type internal electrode. The internal electrode 32 is drawn out to the end face 2a of the piezoelectric body 2, and the internal electrode 34 is drawn out to the end face 2b opposite to the end face 2a of the piezoelectric body 2. Further, in the piezoelectric body 2, as indicated by arrows, the piezoelectric layer between the internal electrode 32 and the internal electrode 33 and the piezoelectric layer between the internal electrode 33 and the internal 34 are opposite in the thickness direction. Is polarized.

Therefore, a pair of external electrodes are formed on the end faces 2a, 2b so as to be electrically connected to the internal electrodes 32, 34, and when an AC electric field is applied, the thickness longitudinal piezoelectric resonance utilizing the second harmonic is achieved. Act as a child.

Similarly, in the thickness extensional piezoelectric resonator 41 of the fifth embodiment shown in FIG. 10, four internal electrodes 42 to 45 are formed in the piezoelectric body 2, and between the internal electrodes 42 and 45. By applying an AC voltage to the piezoelectric resonator, it operates as a thickness longitudinal piezoelectric resonator using a series connection type third harmonic.

In the thickness vertical piezoelectric resonator 51 of the sixth embodiment shown in FIG.
2 to 56 are arranged so as to overlap in the thickness direction via the piezoelectric layer. Here, by applying an AC voltage between the internal electrodes 52 and 56, the piezoelectric element operates as a thickness longitudinal piezoelectric resonator using the fourth harmonic of the thickness longitudinal vibration.

The series connection type thickness vertical piezoelectric resonator 3
1 to 51, as in the case of the parallel connection type, the thickness of the outermost piezoelectric layers 2c and 2d is calculated by the following formulas (4) to (4).
By configuring so as to satisfy (6), it is possible to effectively reduce the variation of the oscillation frequency as in the case of the parallel connection type thickness vertical piezoelectric resonator, and to obtain a spurious (N + 1) order mode. Vibration can be effectively suppressed. This will be described with reference to FIGS.

0.60 ≦ (D ₁ + D ₂ ) /2D≦1.10 (4) 0.70 ≦ (D ₁ + D ₂ ) /2D≦0.90 (5) 0.65 ≦ (D ₁ + D ₂ ) /2D≦0.80 (6) FIGS. 22 to 24 show thickness vertical piezoelectric resonators 31 to 5, respectively.
D ′ / D for ₁ , ie (D ₁ + D ₂ ) / 2D
/ D and the oscillation frequency change rate dF when
FIG. 14 is a diagram showing a relationship between _OSC / F _OSC and a diagram corresponding to FIG. 13 showing a thickness longitudinal piezoelectric resonator using a double wave of a parallel connection type.

22 to 24, solid line A, dashed line B, two-dot chain line C, three-dot chain line D, broken line E and broken line F
Has the same meaning as in FIG. Also, FIG.
Numeral 27 denotes D '/ D, that is, (D ₁ + D ₂ ) / 2D and the oscillation frequency in each of the thickness-wise longitudinal piezoelectric resonators 31 to 51 using the series-connected double, third and fourth harmonics, respectively. It is a figure which shows the relationship with the value which normalized the rate of change, and is a figure corresponding to FIG. 17 about the thickness longitudinal piezoelectric resonator which used the 2nd harmonic of a parallel connection type.

As is apparent from FIGS. 25 to 27, D '/ D, that is, (D ₁ + D ₂ ) / 2D, is obtained in each of the series-connected thickness vertical piezoelectric resonators 31 to 51.
It can be seen that the fluctuation rate of the oscillation frequency can be set within ± 0.2% when they are 0.60 or more, 0.70 or more and 0.65 or more, respectively.

FIGS. 28 (a) and (b) to FIG.
(A), (b) is a figure which shows the ratio band of the main mode and the ratio band of the spurious mode in the thickness extensional piezoelectric resonators 31-51, and each shows the thickness extensional piezoelectric resonator using a 2nd harmonic. FIG. 20 is a diagram corresponding to FIGS. 19A and 19B for No. 11. As is clear from FIGS.
In order to reduce the fractional bandwidth of the (N + 1) -order mode that becomes a spurious, the upper limit value of D ′ / D, that is, (D ₁ + D ₂ ) / 2D is 1 in each of the thickness longitudinal piezoelectric resonators 31 to 51. It can be seen that the values should be set to .10, 0.90 and 0.80.

Therefore, in the series connection type thickness extensional piezoelectric resonators 31 to 51, from the above results, the equations (4)
If (D ₁ + D ₂ ) / 2D is controlled so as to satisfy (6) to (6), the change in the oscillation frequency can be effectively suppressed, and the spurious (N + 1) -order mode response can be effectively reduced. It can be seen that suppression and good resonance characteristics are obtained.

As described above, the thickness vertical piezoelectric resonator according to the present invention may employ either a parallel connection type or a series connection type structure. It can be suitably used as a part.

FIG. 4 is an exploded perspective view showing a piezoelectric resonance component as another embodiment of the present invention, and FIG. 5 is a perspective view showing its appearance. In the piezoelectric resonance component of the present embodiment, the thickness extensional piezoelectric resonator 1 is bonded on the capacitor substrate 61 via the conductive adhesives 62 and 63. Capacitor substrate 61
Are configured using a dielectric substrate. Further, the first to third external electrodes 61 are provided on the outer surface of the capacitor substrate 61.
a to 61c are formed. On the capacitor substrate 61, capacitors C1 and C2 are formed between the external electrodes 61a and 61b and between 61b and 61c, respectively.
Further, the second external electrode 61b is connected to the ground potential.

On the upper surface of the capacitor substrate 61, a film 65 on a rectangular frame made of an insulating material is laminated in order to prevent a short circuit with the external electrodes 61a and 61c and join the metal cap 64. A metal cap 64 is bonded onto the film 65 using an insulating adhesive. In this way, the piezoelectric resonance component 66 constituting the built-in capacitor type piezoelectric oscillator shown in FIG. 5 is obtained. The circuit configuration of the piezoelectric resonance component 66 is shown in the circuit diagram of FIG.

That is, according to this embodiment, a three-terminal type piezoelectric oscillator with a built-in capacitor can be provided. In the first embodiment, the internal electrodes 2 to 5 are linear and extend so as to extend obliquely from the edge of the green sheet. However, in the piezoelectric resonator according to the present invention, The internal electrode may extend in a direction perpendicular to the edge of the green sheet. That is, as shown in FIG. 12, each of the internal electrodes 2 to 4 may have a linear shape extending from the edge of the green sheet in a direction perpendicular to the edge.

Further, in the present invention, the internal electrode of the piezoelectric resonator is not necessarily required to be linear, but may be an internal electrode or the like in which a connection conductive portion is electrically connected to a circular excitation electrode portion. Is also good.

FIGS. 31 and 32 are an exploded perspective view and an external perspective view showing a piezoelectric resonance component as still another embodiment of the present invention. In the piezoelectric resonance component shown in FIGS. 4 and 5, the piezoelectric resonator is surrounded by the metal cap. However, as in this embodiment, the piezoelectric substrate is laminated by using the dielectric substrate without using the metal cap. Resonant components may be configured.

In FIG. 31, a case substrate 71 made of a dielectric substrate is laminated on the lower surface side of a thickness extensional piezoelectric resonator 1 according to a first embodiment schematically shown. A concave portion 71a is formed on the upper surface of the case substrate 71. The concave portion 71a is provided so as not to hinder the vibration of the energy trap type vibrating portion of the thickness extensional piezoelectric resonator 1.

A second case substrate 72 is laminated on the upper surface of the thickness extensional piezoelectric resonator 1. The case substrate 72
It is made of a dielectric substrate and has a concave portion on the lower surface for preventing the vibration of the piezoelectric vibrating portion. Above and below the thickness longitudinal piezoelectric resonator 1,
By bonding the case substrates 72 and 71 with an insulating adhesive and further coating the upper surface with a resin film 73, a piezoelectric resonance component 74 shown in FIG. 32 is obtained.

As the case substrates 71 and 72, a dielectric substrate having a low dielectric constant is preferably used. External electrodes 71a are provided on the side surfaces of the case substrates 71 and 72, respectively.
To 71c and 72a to 72c are formed. The external electrodes 71a to 71c and the external electrodes 72a to 72c are electrically connected via external electrodes 1a to 1c formed on the side surfaces of the thickness extensional piezoelectric resonator 1. Also, the external electrode 71
a, 1a, 72a and external electrodes 71b, 1
A capacitor is formed between the electrodes b and 72b. Similarly, a capacitor is formed between the electrodes formed of the external electrodes 71b, 1b and 72b and the electrodes formed of the external electrodes 71c, 1c and 72c. .

Therefore, as in the case of the piezoelectric resonance component shown in FIG. 5, a three-terminal type piezoelectric oscillator in which two capacitors are connected to the vertical piezoelectric resonator can be formed.

[0066]

According to the first aspect of the present invention, the piezoelectric body has N internal electrodes, and has a thickness longitudinal vibration mode (N-1).
In the parallel connection type energy trap type piezoelectric resonator using the next higher order mode, the thickness of the piezoelectric layer between the adjacent internal electrodes is D, and the first and second layers are located outside the outermost internal electrodes in the thickness direction. When the thicknesses of the piezoelectric layers are D ₁ and D ₂ , equation (2) is obtained when N = 3, equation (1) is obtained when N = 4, and equation (3) is obtained when N = 5. ), The dispersion of the resonance frequency and the oscillation frequency can be reduced, and the fractional bandwidth of the higher-order spurious mode can be narrowed to obtain good resonance characteristics. Can be.

According to the second aspect of the present invention, a series connection type energy trapping type piezoelectric resonance device having N internal electrodes in a piezoelectric body and utilizing the (N-1) th higher order mode of the thickness longitudinal vibration mode is used. When the thickness of the piezoelectric layer between adjacent internal electrodes is D, and the thicknesses of the first and second piezoelectric layers outside the outermost internal electrodes in the thickness direction are D ₁ and D ₂ , Equation (4) is satisfied when N = 3, equation (5) when N = 4, and equation (6) when N = 5. Variations can be reduced, the fractional bandwidth of higher order spurious modes can be narrowed, and good resonance characteristics can be obtained.

In the case where the plurality of internal electrodes are linear electrodes and intersect via the piezoelectric layer, and the intersecting portions constitute an energy trapping type piezoelectric vibrating portion, the linear electrodes By adjusting the area of the intersection, it is possible to easily configure a thickness longitudinal piezoelectric resonator suitable for high frequency operation.

Further, the thickness extensional piezoelectric resonator according to the present invention
Although it can be used for various piezoelectric resonance components, it is preferably used as a piezoelectric oscillator, and in this case, a piezoelectric oscillator with less variation in oscillation frequency can be provided.

In the piezoelectric resonator component according to the present invention, since the capacitor substrate is bonded to the thickness piezo-resonator with a space for preventing vibration of the thickness piezo-resonator from being hindered. Further, it is possible to provide a piezoelectric resonance component as a built-in capacitor type piezoelectric oscillator.

[Brief description of the drawings]

FIGS. 1A and 1B are a perspective view and a cross-sectional view of a thickness extensional piezoelectric resonator using a third harmonic of thickness extensional vibration as a first embodiment of the present invention.

FIG. 2 is an exploded perspective view for explaining the shape of an internal electrode used for forming a piezoelectric body of the thickness extensional piezoelectric resonator according to the first embodiment.

FIG. 3 is a cross-sectional view for explaining a case where a position of an internal electrode is shifted in the thickness longitudinal piezoelectric resonator of the first embodiment, and thicknesses of first and second piezoelectric layers are shifted from an ideal state. FIG.

FIG. 4 is an exploded perspective view of a piezoelectric resonance component using the thickness extensional piezoelectric resonator according to the first embodiment.

FIG. 5 is an external perspective view showing a piezoelectric resonance component according to one embodiment of the present invention.

6 is a diagram showing a circuit configuration of the piezoelectric resonance component of the embodiment shown in FIG.

FIG. 7 is a cross-sectional view showing a thickness extensional piezoelectric resonator using a second harmonic as a second embodiment of the present invention.

FIG. 8 is a sectional view showing a parallel connection type thickness longitudinal piezoelectric resonator using a fourth harmonic as a third embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating a series-connected thickness longitudinal piezoelectric resonator using a second harmonic as a fourth embodiment of the present invention.

FIG. 10 is a cross-sectional view for explaining a series connection type thickness extensional piezoelectric resonator using a third harmonic as a fifth embodiment of the present invention.

FIG. 11 is a cross-sectional view illustrating a series connection type thickness extensional piezoelectric resonator using a fourth harmonic as a sixth embodiment of the present invention.

FIG. 12 is an exploded perspective view for explaining another example of the internal electrode shape in the thickness extensional piezoelectric resonator according to the present invention.

FIG. 13 is a graph showing the relationship between the displacement amount of the internal electrode forming position and the oscillation frequency change rate when the thickness of the outermost piezoelectric layer in the parallel connection type thickness vertical piezoelectric resonator using the second harmonic is changed. The figure which shows a relationship.

FIG. 14 is a graph showing the relationship between the amount of displacement of the internal electrode formation position and the oscillation frequency change rate when the thickness of the outermost piezoelectric layer in the parallel connection type thickness vertical piezoelectric resonator using the third harmonic is changed. The figure which shows a relationship.

FIG. 15 is a graph showing the relationship between the amount of displacement of the internal electrode formation position and the oscillation frequency change rate when the thickness of the outermost piezoelectric layer in the parallel connection type thickness vertical piezoelectric resonator using the fourth harmonic is changed. The figure which shows a relationship.

FIG. 16 is a diagram obtained by rewriting the result shown in FIG. 13;
The figure which shows the relationship between the thickness of the outermost piezoelectric body layer, and the oscillation frequency change rate.

FIG. 17 is a diagram obtained by rewriting the result shown in FIG. 14;
The figure which shows the relationship between the thickness of the outermost piezoelectric body layer, and the oscillation frequency change rate.

18 is a diagram obtained by rewriting the result shown in FIG. 15,
The figure which shows the relationship between the thickness of the outermost piezoelectric body layer, and the oscillation frequency change rate.

FIGS. 19A and 19B are diagrams showing a fractional bandwidth of a second harmonic and a fractional bandwidth of a spurious mode in a parallel connection type thickness extensional piezoelectric resonator using a second harmonic. FIGS.

20 (a) and (b) are diagrams showing a fractional bandwidth of a third harmonic and a fractional bandwidth of a spurious mode in a parallel connection type thickness extensional piezoelectric resonator using a third harmonic.

FIGS. 21 (a) and (b) are diagrams illustrating a fractional bandwidth of a fourth harmonic and a fractional bandwidth of a spurious mode in a parallel connection type thickness extensional piezoelectric resonator using a fourth harmonic. FIGS.

FIG. 22 is a graph showing the relationship between the amount of displacement of the internal electrode formation position and the oscillation frequency change rate when the thickness of the outermost piezoelectric layer is changed in the series connection type thickness vertical piezoelectric resonator using the second harmonic. The figure which shows a relationship.

FIG. 23 is a graph showing the relationship between the amount of displacement of the internal electrode forming position and the oscillation frequency change rate when the thickness of the outermost piezoelectric layer in a series connection type thickness vertical piezoelectric resonator using a third harmonic is changed. The figure which shows a relationship.

FIG. 24 is a graph showing the relationship between the amount of displacement of the internal electrode formation position and the oscillation frequency change rate when the thickness of the outermost piezoelectric layer in a series connection type thickness longitudinal piezoelectric resonator using fourth harmonics is changed. The figure which shows a relationship.

FIG. 25 is a diagram obtained by rewriting the result shown in FIG. 22;
The figure which shows the relationship between the thickness of the outermost piezoelectric body layer, and the oscillation frequency change rate.

FIG. 26 is a diagram obtained by rewriting the result shown in FIG. 23;
The figure which shows the relationship between the thickness of the outermost piezoelectric body layer, and the oscillation frequency change rate.

FIG. 27 is a diagram obtained by rewriting the result shown in FIG. 24;
The figure which shows the relationship between the thickness of the outermost piezoelectric body layer, and the oscillation frequency change rate.

FIGS. 28 (a) and (b) are diagrams showing a fractional bandwidth of a second harmonic and a fractional bandwidth of a spurious mode in a series connection type thickness extensional piezoelectric resonator using a second harmonic. FIGS.

FIGS. 29A and 29B are diagrams showing a fractional bandwidth of a third harmonic and a fractional bandwidth of a spurious mode in a series connection type thickness extensional piezoelectric resonator using a third harmonic.

FIGS. 30 (a) and (b) are diagrams showing a fractional bandwidth of a fourth harmonic and a fractional bandwidth of a spurious mode in a series connection type thickness extensional piezoelectric resonator using a fourth harmonic.

FIG. 31 is an exploded perspective view for explaining another embodiment of the piezoelectric resonance component of the present invention.

FIG. 32 is a perspective view showing a piezoelectric resonance component according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thickness vertical piezoelectric resonator 2: Piezoelectric body 2c, 2d ... First and second piezoelectric layers 3-6 ... Internal electrode 7, 8 ... External electrode 11, 21 ... Thickness vertical piezoelectric resonator 31, 51, 61 ... Thickness vertical piezoelectric resonator

Claims (5)

[Claims] 1. A piezoelectric body uniformly polarized in a thickness direction, and N sheets (N is a natural number of 3 to 5) arranged so as to overlap in the thickness direction via a piezoelectric layer in the piezoelectric body.
Energy confinement using the (N-1) -th order mode of the thickness longitudinal vibration mode, wherein electric fields of opposite polarities are alternately applied in the thickness direction to the piezoelectric layers between the internal electrodes. In the piezoelectric resonator, the thickness of the piezoelectric layer between the internal electrodes adjacent in the thickness direction is D, and the thickness of the first and second piezoelectric layers outside the outermost internal electrode in the thickness direction is D ₁ , D when _2, when N = 3, 0.50 ≦ (D 1 + D 2) /2D≦1.00,N=
In the case of 4, 0.45 ≦ (D ₁ + D ₂ ) /2D≦0.7
5, when N = 5, 0.45 ≦ (D ₁ + D ₂ ) / 2D ≦
A thickness longitudinal piezoelectric resonator, wherein the thickness is 0.60. 2. A piezoelectric body, and N sheets (N is a natural number of 3 to 5) arranged so as to overlap in the thickness direction via a piezoelectric layer in the piezoelectric body.
Energy confining type using the (N-1) th order mode of the thickness longitudinal vibration mode, wherein the piezoelectric layers between the internal electrodes are alternately polarized in the direction opposite to the thickness direction. In the piezoelectric resonator, the thickness of the piezoelectric layer between the internal electrodes adjacent in the thickness direction is D, and the thicknesses of the first and second piezoelectric layers outside the outermost internal electrodes in the thickness direction are D ₁ and D _2. When N = 3, 0.60 ≦ (D ₁ + D ₂ ) /2D≦1.10, N =
When 0.7, 0.70 ≦ (D ₁ + D ₂ ) /2D≦0.9
0, N = 5, 0.65 ≦ (D ₁ + D ₂ ) / 2D ≦
A thickness longitudinal piezoelectric resonator, which is 0.80. 3. The piezoelectric device according to claim 1, wherein the plurality of internal electrodes are linear electrodes and intersect via a piezoelectric layer, and the intersecting portions constitute an energy trapping type piezoelectric vibrating portion. 3. The thickness longitudinal piezoelectric resonator according to 2. 4. A piezoelectric oscillator using the thickness extensional piezoelectric resonator according to claim 1. 5. A thickness vertical piezoelectric resonator according to any one of claims 1 to 3, and a capacitor bonded to the thickness vertical piezoelectric resonator via a space for preventing vibration of the thickness vertical piezoelectric resonator. A piezoelectric resonance component comprising: a substrate.