JPH0525832U - Piezoelectric resonator - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to adjust the size of the relay capacitance without increasing the size of the piezoelectric resonator, and to improve the resonance characteristics by preventing spurious generation in the relay capacitance section. A piezoelectric portion of a composite substrate 1 formed by joining piezoelectric substrates 1a and 1b having piezoelectricity and a dielectric substrate 1c having dielectricity but not piezoelectricity The vibrating electrodes 2 and 3 are disposed on the piezoelectric vibrating portions A and B to obtain a predetermined piezoelectric vibration, and the capacitive electrode 4 is disposed on the portion having the dielectric property but not the piezoelectric property. As a result, the relay capacitance part C capable of obtaining a capacitance having a predetermined size is formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a multi-element type piezoelectric resonator including a relay capacitance section such as a piezoelectric filter and a trap.

[0002]

[Prior Art]

 4 and 5 are plan views showing one main surface and the other main surface of a conventional piezoelectric resonator in the thickness shear vibration mode, and FIG. 6 shows an equivalent circuit thereof. In the conventional piezoelectric resonator shown in these figures, two vibrating electrodes (split electrodes) 22 and 23 are formed on both left and right sides of one main surface of the piezoelectric substrate 21, and the vibrating electrode 22 is one The vibrating electrode 23 is composed of one electrode 23a and the other electrode 23b. Further, in the center of the piezoelectric substrate 21, an electrode (capacitance electrode) 24 for forming a relay capacitance is formed which is electrically connected to the other electrodes 22b and 23b via the lead portions 34 and 35. Further, on both ends of the piezoelectric substrate 21, an attachment electrode for attaching an input / output terminal (not shown) derived from one electrode 22a, 23a of the vibrating electrodes 22, 23 through the lead portions 32, 33. Parts 25, 26 are provided.

On the other hand, on the other main surface (back surface) of the piezoelectric substrate 21, counter electrodes (common electrodes) 27, 28 are formed at positions facing the vibrating electrodes 22, 23, as shown in FIG. The opposing electrodes 27 and 28 face the vibrating electrodes 22 and 23 to form piezoelectric vibrating portions A and B. Further, in the center of the piezoelectric substrate 21, a counter capacitance electrode 29 facing the capacitance electrode 24 via the piezoelectric substrate 21 is formed. The counter electrodes 27, 28 and the counter capacitance electrode 29 are strip-shaped lead portions. It is electrically connected by 30 and 31. The opposing capacitance electrode 29, together with the capacitance electrode 24, forms a relay capacitance portion C that couples the piezoelectric vibrating portions A and B.

[0004]

By the way, in the above-described conventional piezoelectric resonator, in order to form the relay capacitance portion C, the capacitance electrode 24 and the capacitance facing the capacitance electrode 24 are provided at positions facing each other on both main surfaces of the piezoelectric substrate 21. Since the electrode 29 is formed, vibration occurs in this portion (relay capacitor portion C). Therefore, in order to dampen this vibration, in the process of soldering a ground terminal (not shown) to the counter capacitance electrode 29, a considerable amount of solder is applied so that effective damping can be performed.

However, even when solder is placed on the counter capacitance electrode 29 as described above, it is not possible to completely prevent the vibration of the relay capacitance part C, and harmful spurious is generated to cause resonance characteristics. There is a problem of lowering it. Further, the size (capacitance value) of the relay capacitor is one of the main design parameters of the piezoelectric resonance component (piezoelectric resonator) such as the piezoelectric filter, and it is desirable that the value can be originally selected arbitrarily. , C = (ε ₀ ε _S S) / d where ε ₀ = dielectric constant of vacuum, ε _S = relative permittivity of piezoelectric substrate, S = electrode area, d = distance between electrodes (thickness of piezoelectric substrate ), The capacitance value C is determined by the material forming the piezoelectric substrate 21 and the thickness thereof. The only way to change the capacitance is to change the electrode area. In order to obtain the above, the area of the electrode becomes large, and the vibrating region (vibrating portion) of the piezoelectric resonator is invaded. Therefore, the size of the piezoelectric substrate 21 must be increased, and the size of the piezoelectric resonator becomes large. There is.

The present invention solves the above-mentioned problems, and it is possible to adjust the size of the relay capacitance without increasing the size of the piezoelectric resonator and to eliminate unnecessary vibration in the relay capacitance section. It is an object of the present invention to provide a piezoelectric resonator that does not generate the characteristics and does not deteriorate the characteristics.

[0007]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the piezoelectric resonator of the present invention is a piezoelectric resonator in which a plurality of piezoelectric vibrating parts are coupled by a relay capacitor, and has a piezoelectric substrate having a piezoelectric property and an inductive property. A piezoelectric vibrating section capable of obtaining a predetermined piezoelectric vibration by disposing a vibrating electrode on a portion of a composite substrate formed by joining a dielectric substrate having no piezoelectricity and having piezoelectricity. And forming a relay capacitance part capable of obtaining a capacitance of a predetermined size by arranging a capacitance electrode in a portion having a dielectric property but not a piezoelectric property.

[0008]

[Action]

 A piezoelectric vibrating portion is formed in a piezoelectric portion of a composite substrate formed by bonding a piezoelectric substrate (piezoelectric substrate) and a dielectric substrate (dielectric substrate). A predetermined piezoelectric vibration is generated by applying a voltage between the counter electrode and the counter electrode, but the relay capacitor part is formed in the part (dielectric substrate part) that has the dielectric property but not the piezoelectric property. Therefore, even if a voltage is applied between the capacitive electrode and the counter capacitive electrode, piezoelectric vibration does not occur.

Therefore, by using a composite substrate in which a dielectric substrate having a predetermined dielectric constant is used in the portion forming the relay capacitance, it becomes possible to freely set the capacitance value of the relay capacitance portion, and the piezoelectric resonance The degree of freedom in the design of the child is improved, and unnecessary piezoelectric vibration does not occur in the relay capacitor section, so that it is possible to obtain a piezoelectric resonator having good resonance characteristics.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are perspective views showing one principal surface and the other principal surface of a thickness-shear vibration mode piezoelectric resonator according to an embodiment of the present invention, and FIG. 3 is a piezoelectric resonator of this embodiment. 3 is a perspective view showing a composite substrate used in FIG.

As shown in FIG. 3, the composite substrate 1 constituting the piezoelectric resonator of this embodiment has two substrates (piezoelectric substrates) 1 a and 1 b having piezoelectricity and a substrate (dielectric substrate having dielectricity). It is a composite substrate formed by bonding both sides of the body substrate) 1c. As shown in FIG. 1, a vibrating electrode (split electrode) 2 is formed on one piezoelectric substrate 1a forming the composite substrate 1, and a vibrating electrode (split electrode) is formed on the other piezoelectric substrate 1b. ) 3 is formed. The vibrating electrode 2 is composed of one electrode 2a and the other electrode 2b, and similarly the vibrating electrode 3 is composed of one electrode 3a and the other electrode 3b. Further, mounting electrode portions 5 and 6 for mounting input / output terminals are provided on both end sides of the composite substrate 1, that is, on the end portions of the piezoelectric substrates 1a and 1b forming the composite substrate 1. The parts 5 and 6 are connected to one electrodes 2a and 3a of the vibrating electrodes 2 and 3 via the lead parts 12 and 13.

The dielectric substrate 1c forming the composite substrate 1 has an electrode for forming a relay capacitor, which is electrically connected to the other electrodes 2b and 3b of the vibrating electrodes 2 and 3 via the lead portions 14 and 15. (Capacitance electrode) 4 is formed.

On the other hand, on the other main surface (back surface) of the composite substrate 1, as shown in FIG. 2, a position facing the vibrating electrodes 2 and 3 (that is, the back surface of the piezoelectric substrates 1a and 1b) is opposed. Electrodes (common electrodes) 7 and 8 are formed, and the counter electrodes 7 and 8 face the above-described vibrating electrodes 2 and 3 formed on one surface (front surface) of the composite substrate 1, and the piezoelectric vibrating portion is formed. A and B are formed. Further, on the dielectric substrate 1c at the center of the composite substrate 1, a counter capacitance electrode 9 facing the capacitance electrode 4 via the dielectric substrate 1c is formed. The counter electrodes 7 and 8 and the counter capacitance electrode are formed. 9 is electrically connected by strip-shaped lead portions 10 and 11. In this way, the relay capacitance portion C is formed on the dielectric substrate 1c, and the piezoelectric vibration portions A and B are coupled to each other by the capacitance formed by the opposing capacitance electrode 9 and the capacitance electrode 4.

In the piezoelectric resonator of the present invention configured as described above, the composite substrate 1 obtained by joining the piezoelectric substrates 1a and 1b having piezoelectricity and the dielectric substrate 1c having dielectricity, Since the piezoelectric vibrating portions A and B are formed on the portions having piezoelectricity (that is, the piezoelectric substrates 1a and 1b), and the relay capacitance portion C is formed on the dielectric substrate 1c having dielectricity but not piezoelectricity. The piezoelectric vibrating portions A and B generate a predetermined piezoelectric vibration by applying a voltage to the vibrating electrodes 2 and 3, but the relay capacitance portion C does not generate a voltage between the capacitance electrode 4 and the counter capacitance electrode 9. Does not cause piezoelectric vibration. Therefore, by using the dielectric substrate 1c having a predetermined dielectric constant for the relay capacitance section C, it is possible to form a capacitance necessary for the design without causing unnecessary piezoelectric vibration in the relay capacitance section C. As a result, a piezoelectric resonator having good resonance characteristics can be obtained. Further, when connecting the grounding terminal to the opposed capacitance electrode 9, it is not necessary to put a large amount of solder in consideration of vibration damping, and therefore, normal vibration of the piezoelectric resonator is not disturbed from that aspect as well. The resonance characteristic can be improved.

In the above embodiments, the thickness-shear vibration mode piezo-resonator is explained, and although the present invention is meaningful for the thickness-shear vibration mode piezo-resonator, other vibration modes, for example, The present invention can also be applied to a piezoelectric resonator using a vibration mode such as a thickness longitudinal vibration mode.

In the above embodiment, the case where the piezoelectric resonator is formed by disposing the electrodes on the composite substrate in which the piezoelectric substrate and the dielectric substrate are joined has been described. It is also possible to separately form the piezoelectric vibrating portions A and B and the relay capacitance portion C, and then to join them.

Furthermore, although the two-element type piezoelectric resonator has been described in the above embodiment, the present invention is not limited to the two-element type piezoelectric resonator and can be applied to a multi-element type piezoelectric resonator having three or more elements. .

In this invention, there is no particular restriction on the mode of bonding the piezoelectric substrate and the dielectric substrate, and there is no particular restriction on the bonding method. Further, it is also possible to provide a plurality of piezoelectric vibrating portions (vibrating elements) or a plurality of relay capacitance portions on one piezoelectric substrate or dielectric substrate, respectively.

Further, in this invention, there are no particular restrictions on the shape and structure of the composite substrate, the vibrating electrode, the capacitor electrode, the counter electrode, the counter capacitor electrode, etc., as long as they do not hinder the operation of the invention. It can be formed into a shape.

[0020]

[Effect of the device]

 As described above, in the piezoelectric resonator of the present invention, the vibrating electrode is arranged on the portion having piezoelectricity (that is, on the piezoelectric substrate) on the composite substrate formed by joining the piezoelectric substrate and the dielectric substrate. Since the piezoelectric vibrating portion is formed by arranging it, and the relay capacitance portion is formed by disposing the capacitance forming electrode on the portion having dielectric properties (that is, on the dielectric substrate), The piezoelectric vibrating part generates a predetermined piezoelectric vibration by applying a voltage to the vibrating electrode, but the relay capacitance part is formed on the dielectric substrate part, and even if a voltage is applied to the capacitive electrode, the piezoelectric vibration part Does not occur. Therefore, by using a dielectric substrate with a prescribed permittivity, the required capacitance can be provided without causing harmful piezoelectric vibrations such as spurious emission in the relay capacitance section. The piezoelectric resonator can be formed, the degree of freedom in design is improved, and a piezoelectric resonator having good resonance characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing one main surface of a piezoelectric resonator according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the other principal surface of the piezoelectric resonator according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a composite substrate used in a piezoelectric resonator according to an embodiment of the present invention.

FIG. 4 is a plan view showing one main surface of a conventional piezoelectric resonator.

FIG. 5 is a plan view showing the other principal surface of a conventional piezoelectric resonator.

FIG. 6 is a diagram showing an equivalent circuit of a conventional piezoelectric resonator.

[Explanation of symbols]

 A, B Piezoelectric vibration part C Relay capacitance part 1 Composite substrate 1a, 1b Substrate having piezoelectricity 1c Dielectric substrate 2,3 Vibrating electrodes 2a, 3a One electrode of vibrating electrode 2b, 3b The other electrode of vibrating electrode 4 Capacitance electrodes 7,8 Counter electrode (common electrode) 9 Counter capacitance electrode

Claims (1)

[Scope of utility model registration request] 1. A piezoelectric resonator including a plurality of piezoelectric vibrating portions coupled by a relay capacitor, wherein a piezoelectric substrate having piezoelectricity and a dielectric substrate having dielectricity but not piezoelectricity are bonded together. By forming a piezoelectric vibrating portion capable of obtaining a predetermined piezoelectric vibration by arranging a vibrating electrode on a portion having a piezoelectric property of a single composite substrate formed by the above, the piezoelectric substrate has a dielectric property but a piezoelectric property. A piezoelectric resonator, wherein a capacitance electrode is arranged in a portion not having the relay capacitance portion to obtain a capacitance of a predetermined size.