JP2600921B2 - Piezoelectric resonator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type piezoelectric resonator using an energy trapping type piezoelectric resonator, and more particularly, to an improvement in a resonance electrode and a drawing structure of the resonance electrode. About things.

[Conventional technology]

As a Colpitts type oscillation circuit using a piezoelectric oscillator, a circuit shown in FIG. 2 is known. In FIG. 2, 1 indicates an inverter, 2 indicates a feedback resistor, 3 indicates a piezoelectric resonator, and 4 and 5 indicate external capacitors.

By adjusting the capacitance values of the external capacitors 4 and 5, the oscillation voltage is controlled to an appropriate value, and stable oscillation is obtained.

However, since the above configuration requires an external capacitor, the number of components increases. Therefore, a configuration in which the external capacitors 4 and 5 can be omitted has been proposed (for example, JP-A-55-95417). As shown in FIG. 3, here, in the three-terminal type piezoelectric oscillator 6, the resonance electrodes 6a and 6b formed on one main surface and the common electrode 6 formed on the other main surface.
Two resonance units are formed between the two resonance units. In the region where the two resonance units are configured, the polarization direction of the piezoelectric plate is reversed as shown by the arrow in the drawing.

A structure using a four-terminal type piezoelectric oscillator shown in FIG. 4 has also been proposed. Here, the resonance electrodes 7a and 7b are formed on one main surface of the piezoelectric oscillator 7 and the resonance electrodes 7c and 7d are formed on the other main surface, thereby forming a four-terminal piezoelectric oscillator. In the piezoelectric oscillator 7, the piezoelectric plate is uniformly polarized as shown by the direction of the arrow in the figure. In this piezoelectric vibrator, lead terminals are actually drawn out from each of the resonance electrodes 7a to 7d. When mounted on a printed circuit board, the resonance electrodes 7c and
The lead terminals connected to 7b are electrically connected by conductive patterns on the printed circuit board.

[Technical problem to be solved by the invention]

In the piezoelectric oscillator 6 shown in FIG. 3, the polarization direction of the piezoelectric plate must be reversed between the resonance units. Therefore, it has been difficult to obtain a resonator that requires complicated polarization processing and has stable characteristics.

On the other hand, in the piezoelectric oscillator 7 shown in FIG. 4, since the polarization direction is uniform, the polarization processing is easy. However, it is a four-terminal type piezoelectric component from which four lead terminals are drawn out, and it is necessary to wire between the lead terminals using a conductive pattern on a printed circuit board. That is, a complicated wiring operation is required, and the mounting density is reduced.

Therefore, an object of the present invention is to provide a small and inexpensive piezoelectric resonator with a built-in load capacitance, which does not require complicated polarization processing and external wiring work.

[Means for solving technical problems]

The present invention is a chip-type piezoelectric resonator using an energy trapping type piezoelectric resonator, in which a piezoelectric plate is uniformly polarized. First and second resonance electrodes are formed on one main surface of the piezoelectric plate, and third and fourth resonance electrodes are formed on the other main surface. The third and fourth resonance electrodes are formed so as to at least partially oppose the first and second resonance electrodes via the piezoelectric plate.

A protective substrate is laminated on both main surfaces of the piezoelectric plate to form a laminate.

The first to fourth resonance electrodes are formed on the outer peripheral side surface of the piezoelectric plate.
It is drawn to different first to fourth regions. On the other hand, first to fourth terminal electrodes are formed on the side surfaces of the piezoelectric plate so as to be electrically connected to the first to fourth resonance electrodes, respectively. Connected third
A fifth terminal electrode formed on the outer surface of the laminate, and a second terminal electrode electrically connected to a second resonance electrode formed so as to face the fourth resonance electrode. And are electrically connected.

As the resonance electrode formed on the piezoelectric plate, a resonance electrode divided into four on one main surface may be formed. That is, in addition to the first and second resonance electrodes, the fifth and sixth resonance electrodes are provided on one main surface of the piezoelectric substrate, and the fifth and sixth resonance electrodes and the piezoelectric plate are provided on the other main surface. It is also possible to use a structure in which the seventh and eighth resonance electrodes are formed so as to face each other through the intermediary. In this case, the fifth to eighth resonance electrodes are extended to the fifth to eighth regions on the outer peripheral side surface and the fifth to eighth terminals formed in the fifth to eighth regions. It is electrically connected to the electrodes. Then, the fourth terminal electrode and the fifth terminal electrode, and the sixth terminal electrode and the seventh terminal electrode are electrically connected to each other using the outer peripheral surface of the component.

[Action]

Since a piezoelectric plate having a uniform polarization direction is used, complicated polarization processing is not required. In addition, since the second and third resonance electrodes are connected in advance in the component, there is no need to form a wiring pattern on the circuit board when mounting on a printed circuit board or the like, and the mounting space can be reduced. It is possible.

[Explanation of Example]

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1A is a plan view for explaining a piezoelectric plate used for a piezoelectric oscillator according to one embodiment of the present invention and a resonance electrode formed thereon, and FIG. It is a top view which shows the shape of the resonance electrode of the lower surface side seen through the piezoelectric plate. The piezoelectric plate 11 is made of piezoelectric ceramics uniformly polarized in the thickness direction. At the center of the upper surface of the piezoelectric plate 11, a first resonance electrode 12a and a second resonance electrode 12b each having a substantially semicircular shape obtained by dividing a circle into two are formed. First resonance electrode 1
2a and the second resonance electrode 12b are connected to the extraction electrodes 13a and 13b to the first side 11a and the second side 11b of the piezoelectric plate 11, respectively.
Has been withdrawn by

On the other hand, as shown in FIG. 1 (b) through the piezoelectric plate 11, a substantially semicircular third resonance electrode 12c and a fourth resonance electrode 12d are formed on the lower surface of the piezoelectric plate 11. ing. Similarly, the fourth resonance electrode 12d is opposed to the first resonance electrode 12a via the piezoelectric plate 11 so as to face the first resonance electrode 12c.
Are formed so as to be opposed to the second resonance electrode 12b via the piezoelectric plate 11. Third and fourth resonance electrodes 12c, 12d
Are extracted to the third side surface 11c and the fourth side surface 11d of the piezoelectric plate 11 by the extraction electrodes 13c and 13d, respectively.

In manufacturing the piezoelectric plate 11, it is only necessary to prepare a piezoelectric plate that is uniformly polarized in the thickness direction, so that complicated polarization processing is not required. Moreover, the first and third resonance electrodes
A difference in resonance characteristics between the resonance unit composed of 12a and 12c and the resonance unit composed of the second and fourth resonance electrodes 12b and 12d is unlikely to occur.

Next, protective substrates 14a and 14b made of insulating ceramics shown in FIG. 5 are bonded to the upper and lower surfaces of the piezoelectric plate 11 via an adhesive. In this way, the resonance part can be sealed. Although not shown, concave portions are formed on the upper and lower surfaces of the protection substrates 14a and 14b in order to provide a space for preventing the resonance of the portion where the resonance unit is formed.

The protective substrates 14a and 14b may be made of, besides insulating ceramics, glass or a high-melting-point resin that can withstand heat during soldering or electrode formation, or may be made of a metal plate with insulating coating. Good.

Next, first to fourth terminal electrodes 15a to 15d are provided on the first to fourth regions on the side surfaces of the piezoelectric plate 11 on which the protection substrates 14a and 14b are stacked.
Is formed. The terminal electrodes 15a to 15d are formed by applying and baking a conductive paste, or by a known electrode forming method such as plating or vapor deposition.

The first terminal electrode 15a is connected to the first resonance electrode 12a (FIG. 1).
And is used as an input / output terminal electrode. The fourth terminal electrode 15d is connected to the fourth resonance electrode 1
It is electrically connected to 2d and is also used as an input / output terminal electrode.

On the other hand, the second and third terminal electrodes 15b and 15c are
2, electrically connected to the third resonance electrodes 12b and 12c,
Further, they are electrically connected to each other by a connection electrode 16 as a fifth terminal electrode.

Therefore, in the above-described piezoelectric oscillator, the terminal electrodes 15a and 15d are used as input / output terminals and the terminal electrodes 15b and 15c are used as ground terminals.
It can be seen that the load capacity built-in type piezoelectric oscillator shown by the equivalent circuit in the figure is configured. In addition, as in the case of the conventional piezoelectric oscillator 7 shown in FIG. 4, there is no need to perform complicated connection work outside the piezoelectric oscillator, so that the mounting workability is excellent and the mounting space is reduced. It is also possible.

The steps of forming the piezoelectric plate 11 and laminating the protective substrates 14a and 14b can be performed in a state of the mother substrate,
Therefore, the piezoelectric component of the above embodiment is excellent in mass productivity. In the above embodiment, the terminal electrodes 15b and 15c connected to the second and third resonance electrodes are electrically connected by the connection electrode 16 formed on the protection substrate 14a. The electrical connection of the third resonance electrode may be made at an arbitrary portion such as the side surface of the piezoelectric plate 11 or the lower surface of the protection substrate 14b.

FIGS. 7 (a) and 7 (b) are plan views for explaining another example of the shape of the resonance electrode that can be used in the present invention, and a shape for explaining the shape of the resonance electrode on the lower surface when viewed through the piezoelectric plate. FIG.

Here, the first and second resonance electrodes 12a and 12b formed on the upper surface of the piezoelectric plate 11 have a shape obtained by diagonally dividing a circular electrode material. On the lower surface side of the piezoelectric plate 11, the third and fourth resonance electrodes 12c and 12d are respectively connected to the first and second resonance electrodes 12c and 12d.
It is formed so as to overlap with a and 12b.

A second point different from the embodiment shown in FIG. 1 is that the extraction electrodes 13b and 13c are extended to the same side surface 11b.
By laminating protective substrates 14a and 14b on the upper and lower surfaces of the piezoelectric plate 11 shown in FIG. 7 and forming terminal electrodes, the piezoelectric oscillator shown in FIG. 8 can be obtained. Here, the terminal electrodes 16a to 1
6c is formed by a known external electrode forming method,
The terminal electrodes 16a and 16c constitute first and fourth terminal electrodes, that is, input / output terminal electrodes. Then, the second resonance electrode 12b and the third resonance electrode 12c of FIG. 7 are electrically connected by the terminal electrode 16b also serving as the second, third and fifth terminal electrodes of the present invention. ing. Extraction electrode 1
Since 3b and 13c (FIG. 7) are drawn to the same side surface 11b, in this embodiment, the second and third resonance electrodes are connected only by forming the terminal electrode 16b extending vertically.

In the above-described embodiment, the piezoelectric resonator using the energy trap type piezoelectric resonator utilizing the thickness longitudinal vibration mode in which the resonance electrodes are formed on both main surfaces of the piezoelectric plate polarized in the thickness direction has been described. However, it is also possible to use a piezoelectric resonator using another vibration mode.

9 (a) and 9 (b) show an embodiment applied to an energy trap type piezoelectric resonator utilizing a thickness shear vibration mode.

In the piezoelectric resonator 21, a strip-shaped piezoelectric plate 22 uniformly polarized in the direction of the arrow shown in the figure is used. On the upper surface of the piezoelectric plate 22, first and second resonance electrodes 23a and 23 extending in the longitudinal direction are provided.
b is formed so as to extend from the side surface 22a of the piezoelectric plate 22 toward the center. On the other hand, on the lower surface of the piezoelectric plate 22, third and fourth resonance electrodes 23c and 23d extending from the other side surface 22b toward the center are formed. That is, also in the piezoelectric resonator 21 of the present embodiment, it can be seen that the piezoelectric plate 22 is uniformly polarized, and that the two main surfaces are formed with two divided resonance electrodes. Therefore, four regions which are not short-circuited with each other are selected from the outer peripheral side surface of the piezoelectric plate 22 to form first to fourth terminal electrodes, and the second and third terminal electrodes are electrically connected on the outer peripheral surface of the component. By doing so, it is possible to configure a piezoelectric oscillator with a built-in load capacitance similar to that of the first embodiment.

FIG. 10 is a perspective view showing another example of an energy trapping type piezoelectric resonator using a thickness shear vibration mode which can be used in the present invention, and a diagram showing a lower surface side resonance electrode.

In the piezoelectric resonator 31, from the center of the upper surface of the piezoelectric plate 32, side surfaces 32a,
First and second resonance electrodes 33a and 33b extending toward the 32b side are formed. On the other hand, as shown in FIG. 10 (b), a space 34b larger than the space 34a between the resonance electrodes 33a, 33b on the upper surface side is opened on the lower surface side, and the third and fourth resonance electrodes 33c, 33c are formed.
3d is formed.

The first to fourth resonance electrodes 33a to 33d are respectively
The piezoelectric elements 32 are led out to the side surfaces 32a and 32b by the lead electrodes 35a to 35d.

The piezoelectric resonator 31 shown in FIG. 10 is the same as the piezoelectric resonator shown in FIG.
This corresponds to a structure in which two piezoelectric resonance units in 21 are connected in the longitudinal direction of the piezoelectric plate. Therefore, the extraction electrode described above
The first side of the piezoelectric plate 32 from which 35a to 35d are drawn
It is understood that by forming the fourth to fourth terminal electrodes, a piezoelectric oscillator similar to the above-described embodiment can be formed.

FIGS. 11 (a) and (b) are plan views for explaining still another embodiment of the present invention. In the piezoelectric resonator 41 of the present embodiment, the first and second resonance electrodes 12a,
In addition to 12b, fifth and sixth resonance electrodes 43a and 43b are formed. Further, on the other main surface of the piezoelectric plate 42, at a position facing the front and back with the fifth and sixth resonance electrodes 43 a and 43 b via the piezoelectric plate 42,
Seventh and eighth resonance electrodes 43c and 43d are formed.

That is, in the piezoelectric resonator 41, a resonance electrode having a shape obtained by dividing a circular electrode material into four is formed on both main surfaces of the piezoelectric plate 42.

The first to eighth resonance electrodes 12a to 12d and 43a to 43d are drawn to first to eighth regions on the outer peripheral side surface of the piezoelectric plate 42 by the extraction electrodes 13a to 13d and 44a to 44d, respectively.

However, of the extraction electrodes, the extraction electrode 13b connected to the second resonance electrode 12b and the extraction electrode 13c connected to the third resonance electrode 12c are extracted to the central region of the same side surface 42a of the piezoelectric plate 42. Have been. That is, the second and third regions are the same region. Similarly, the extraction electrode 44a and the extraction electrode 13d are extended to the same side surface 42b, and the extraction electrode 44b and the extraction electrode 44c are extended to the central region of the same side surface 42c.

Therefore, as in the embodiment shown in FIG.
If a terminal electrode extending in the thickness direction of the piezoelectric plate 42 is formed,
The extraction electrode 13b and the extraction electrode 13c can be electrically connected, so that the second resonance electrode 12b and the third resonance electrode 12c can be electrically connected.

Similarly, on the other side surfaces 42b and 42c of the piezoelectric plate 42, the terminal electrodes are formed in the same manner, so that the fifth resonance electrode 43a and the fourth resonance electrode 12d and the sixth resonance electrode 43b are formed respectively. The seventh resonance electrode 43c can be electrically connected to each other. Thus, the piezoelectric resonator shown in FIG.
If 41 is used, a resonance device having a structure in which a plurality of structures shown by the equivalent circuit shown in FIG. 6 are electrically connected can be easily obtained.

It should be pointed out that the piezoelectric resonator of the present invention is not limited to the one for constituting the piezoelectric oscillation circuit described above, but can be applied to filters and various resonance devices.

〔The invention's effect〕

As described above, in the present invention, since the piezoelectric plate is only polarized uniformly, it is not necessary to implement a complicated polarization method such as partially performing polarization in the opposite direction. Further, since the load capacitance can be configured without requiring an external capacitor or the like, the configuration of the piezoelectric oscillation circuit can be simplified and reduced in size. Since the first to fourth terminal electrodes are used as chip-type components that can be appropriately connected using the outer peripheral surface of the element, complicated line work on a printed circuit board or the like is performed. Can be omitted, and the mounting space can be reduced.

Fifth and sixth resonance electrodes are further formed on one main surface of the piezoelectric plate, and seventh and eighth resonance electrodes are further formed on the other main surface. Are electrically connected to each other using the outer peripheral surface of the component similarly to the third terminal electrode and the second terminal electrode in the example in which only the first to fourth resonance electrodes are formed. It is possible to realize a complicated configuration of the piezoelectric resonance circuit with small chip components.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a plan view for explaining the shapes of a piezoelectric plate and a resonance electrode used in a first embodiment of the present invention, respectively, and the resonance on the lower surface side when seen through the piezoelectric plate. FIG. 2 shows an oscillation circuit, FIG. 3 shows a circuit diagram showing an oscillation circuit using a conventional piezoelectric oscillator, and FIG. 4 shows another example of a conventional piezoelectric oscillator. Circuit diagram,
FIG. 5 is an external perspective view of the first embodiment of the present invention, FIG. 6 is a diagram showing an equivalent circuit of the first embodiment of the present invention, and FIGS. 7 (a) and 7 (b) are diagrams of the present invention. FIG. 8 is a plan view for explaining the shape of the resonance electrode in the second embodiment, FIG. 8 is an external perspective view of the second embodiment, and FIGS. FIGS. 10 (a) and 10 (b) are a perspective view and a cross-sectional view taken along line BB, respectively, for explaining another example of a piezoelectric resonator that can be used. FIGS. 11 (a) and 11 (b) are a perspective view for explaining a device and a schematic plan view showing a resonance electrode formed on the lower surface side, respectively, and FIGS. It is each top view. In the figure, 11 is a piezoelectric plate, 11a to 11d are first to fourth side faces, 12a to 12d are first to fourth resonance electrodes, and 15a to 15d are first
To 4th terminal electrode.

Claims (2)

(57) [Claims] 1. A chip type piezoelectric resonator of an energy trap type, comprising: a uniformly polarized piezoelectric plate; and first and second resonant electrodes formed on one main surface of the piezoelectric plate. A third and fourth resonance electrodes formed on the other main surface of the piezoelectric plate so as to face each other at least partially with the first and second resonance electrodes and the piezoelectric plate interposed therebetween, The first to fourth piezoelectric plates are separated from each other on the outer peripheral side surface.
The first to fourth resonance electrodes are extended to first to fourth regions on the outer peripheral side surface of the piezoelectric plate. And first to fourth terminal electrodes electrically connected to the first to fourth resonance electrodes, respectively, and laminated on both main surfaces of the piezoelectric plate to form a laminate. A chip-type piezoelectric element, further comprising a protective substrate, wherein the third terminal electrode and the second terminal electrode are electrically connected using a fifth terminal electrode formed on the outer surface of the multilayer body. Resonator. 2. An outer peripheral side surface of the piezoelectric plate has fifth to eighth regions in addition to the first to fourth regions, and first and second first and second regions are formed on one main surface of the piezoelectric plate. Fifth and sixth resonance electrodes are formed in addition to the resonance electrodes. On the other main surface, the fifth and sixth resonance electrodes are opposed to the fifth and sixth resonance electrodes via piezoelectric plates, respectively. 7, an eighth resonance electrode is formed, and the fifth to eighth resonance electrodes are drawn to fifth to eighth regions on the outer peripheral side surface of the piezoelectric plate. And further comprising fifth to eighth terminal electrodes formed in the fifth to eighth regions and electrically connected to the fifth to eighth resonance electrodes, respectively. 5th terminal electrode and 6th terminal electrode
2. The chip-type piezoelectric resonator according to claim 1, wherein the terminal electrode and the seventh terminal electrode are electrically connected by using an outer peripheral surface of the component.