JPS60153213A - Piezoelectric filter - Google Patents

Abstract

PURPOSE:To increase the number of degrees of freedom of capacity between electrodes and to reduce the size by uniting vibrating reeds with a coupling part by a piezoelectric body and connecting three-terminal type vibrators in parallel to form respective vibrating reeds. CONSTITUTION:Signals are inputted/outputted by an external terminal 36 which is stored in a case 35 and elastically contacted. The vibrating reeds 11, 12 constitute respective three-terminal type piezo-electric vibrating elements each of which consists of four vibrators 40 connected with each other in parallel and the inter-electrode capacity becomes four times one vibrator 40, so that the distance between the opposed electrodes can be narrowed and the inter-electrode capacity is increased. A capacitor coupling the vibrating reeds 11, 12 is formed on a coupling part 13 as a parallel plate capacitor 17, so that a lead wire for connecting the capacitor and metallic chips which are contact with the electrodes are omitted and parts other than an external terminal is integrally formed. Therefore, the number of parts can be reduced and the device can be easily produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric filter formed by C-coupling a plurality of Fi3 terminal type piezoelectric imaging elements, and in which a capacitor and a piezoelectric vibrating element are formed as a single piezoelectric body.

FIG. 1 is an explanatory diagram of a conventional piezoelectric filter in which a plurality of three-terminal piezoelectric vibrating elements are C-coupled. A dot electrode 2 and a ring electrode 3 surrounding it are provided on the main surface of a rectangular 8E electric plate 1 in the shape of a turning angle, and a full-surface electrode is provided on the main surface of the 8E plate 1 so that the dot electrode 2 is spread in a manner that the dot electrode 2 and the ring electrode 3 surrounding the dot electrode 3 are spread out. Two piezoelectric vibrating elements 4 are connected via a capacitor C, input/output terminals 5 and 6 are connected to the dot electrodes 2, and the entire surface electrode is grounded. Then, the pass band is adjusted by changing the capacitance value of the capacitor C. However, in this type of piezoelectric filter, the size and shape of the piezoelectric vibrating element 4 are determined by the frequency, so there is little flexibility in the interelectrode capacitance, and the interelectrode capacitance is easily influenced by external capacitance.

In addition, connection of input/output terminals to electrodes and connections between electrodes are performed by elastically bringing a metal piece into point contact with the electrodes, and a capacitor for external connection is also required, so it is not possible to use a system with a large number of parts. It is also troublesome to assemble.

The present invention aims to improve the drawbacks of such conventional piezoelectric filters.

In the piezoelectric filter of the present invention, a plurality of elongated vibrating pieces and a coupling part for coupling the vibrating pieces are formed in 91 pieces of piezoelectric material, and inside the vibrating pieces there is a groove extending over almost the entire surface of the vibrating pieces. 1 electrode and a second and third electrode that face the first electrode via a piezoelectric material and extend in the length direction of the vibrating element.
More than one pair of electrodes are stacked, and adjacent vibrating pieces are electrically C-coupled by extending at least one second and third electrode to the joint, and both ends The ends of the second electrode and the third electrode of each vibrating piece are exposed on one side of the vibrating piece and connected in common to form an input/output terminal, and the first electrode of each vibrating piece is connected. A grounding terminal is formed by exposing the electrode near the coupling part and making a common connection, and the second electrode and the third electrode, which are not connected to the input/output terminal, are exposed near the joint part and are connected in common. It is characterized by

Below, FIGS. 2 to 5 show embodiments of the piezoelectric filter of the present invention.
This will be explained with reference to the figures. Fig. 2 is a perspective view of a piezoelectric filter, Fig. 3 is an enlarged sectional view taken along line AA' in Fig. 2, Fig. 4 is a perspective view for explaining an example of a manufacturing method, and Fig. 5 is a piezoelectric filter. FIG. 3 is a plan view showing the external connection state of the device.

Photographic pieces 11, 12 of 102 IE radio wave devices. Joint part 1
3 is formed into an H-shaped piece by a piezoelectric ceramic plate. Inside the elongated rectangular vibrating piece 11.12, there is a first electrode 14-1 extending over almost the entire surface in a plane.
A second electrode 15 and a third electrode 16 are provided which are opposed to 4 with a piezoelectric ceramic interposed therebetween and extend in the length direction thereof.

The 20'th pole 15 and the third electrode 16 are stacked on the same horizontal plane, and in this embodiment, these three electrodes constitute one set, and four sets of electrodes are stacked on each of the vibrating piece 11 and the imaging piece 12.

Furthermore, the third electrode 16 of the third set from the top of the vibrating element ti
A parallel plate capacitor 17 is formed by extending the second electrodes 15 of the second set from the top of the vibrating element 12 to the coupling portion 13 and facing them.

The end of the third wire i16 is exposed on the outer end surface 18 of the vibrating piece 12, and an input/output terminal 19 is formed by common connection. A second electrode 15 is provided on the outer end surface of the vibrating piece 11.
The ends of the two terminals are exposed and similarly connected in common to form input/output terminals 20.

The ends of the first electrode 14 and the third electrode 16 are exposed on the side surface of the vibrating piece 11 on the coupling part 13 side, and the ends of the first electrode 14 and the third electrode 16 are
14 is also exposed at the end of the side surface 21 of the joint portion 13. The first @ poles 14 are commonly connected at the end portions of the side surfaces 21 of the coupling portions 13 that are not exposed on the third electrodes 16, and the commonly connected portions form the grounding terminals 22. Only the third electric wire i16 is exposed at a position corresponding to the grounding terminal 22 on the side surface opposite to the side surface 21, and is commonly connected. Vibration piece 1
The first electrode 14 and the second electrode 15 of 2 are also exposed on the side surface on the joint portion 13 side, and the first electrode 1i14 is common at the end portion of the side surface 21 opposite to the grounding terminal 22. connected,
That part forms the ground terminal. The second electrodes 15 are commonly connected at the end portions of the sides opposite to the side faces 21.

As shown in FIG. 4, the piezoelectric filter lO is made by stacking a plurality of piezoelectric ceramic green sheets 30 with their H-shaped outlines (mainly indicated by dotted lines) aligned, and then punching out the H-shaped portions to form a single piezoelectric filter. It is best to fire it as a board.

A second electrode 15 and a third electrode 16 are formed on the first, third and fifth green sheets 30 from the top, and at electrodes 14 are formed on the second and fourth sheets. It is. The second electrode 15 on the right side of the third image and the third electrode 4i1 on the left side of the fifth image
6 extends to the central portion 31 which will later become the joint 13.

First electricity 1fIj! , 14, when the green sheets 30 are stacked, the first voltage IN<1 of this portion
Connect the input/output terminals 19.2 without exposing the terminals 4 to the outside.
The purpose is to expose the second electrode 15 and the third electrode 16 that are not connected to 0 and connect them in common. Also the second 4
The removed portion 33 of the first electrode 15 and the removed portion 34 of the third electrode 16 are such that only the first electrode 14 is exposed at these portions so that the grounding terminal 22 can be formed. The first and second electrodes from the top, and the third and fourth electrodes will later form the top and second sets of electrodes in Figure 3, respectively, and the fifth electrode will similarly form the third set of electrodes. constitutes part of the set of electrodes. In order to construct the four sets of electrodes shown in FIG. 3, it is necessary to stack more green sheets in the same manner as in FIG. 4, but this is not shown. Each electrode in FIG. 4 is formed by screen printing. After baking, apply conductive paint to the exposed parts of each electrode to connect them commonly, and also connect them to the input/output terminals 19 and 2.
0. The piezoelectric filter IO is completed by forming the grounding terminal 22 at a position that does not inhibit vibration and polarizing it. Polarization is performed in the direction in which the electrodes are stacked, and the vibrating element 11.1
2 undergoes stretching vibration in the length direction. The coupling portion 13 is located at a vibration node.

The piezoelectric filter 10 as described above is held in a case 35 as shown in the plan view of FIG. 5, and input and output of signals is performed by, for example, external terminals 36 that are in elastic contact with each other. 37 is an external terminal for grounding. 38 and 39 are input/output terminals 19
．． The second electrode [15 and the third electrode 1] which is not connected to 20
6 are common connection parts. The piezoelectric filter 10 is isometrically constructed as shown in the wiring diagram in FIG. Constitutes a vibration element. The capacitance between the electrodes is four times that of one vibrator 40, and if the stain electrodes are stacked in the manner shown in Figure 4, the distance between the opposing electrodes can be made very narrow, so the capacitance between the capacitances can be dramatically increased. I can listen to dogs. Further, a capacitor for C-coupling the vibrating element ti and the vibrating element 12 is formed as a parallel plate capacitor 17 in the coupling part 13.
There is no need for lead wires that connect the capacitor or metal pieces that come into contact with the electrodes, and everything except the external terminals is formed in one piece. Therefore, the number of parts is reduced and manufacturing becomes easier.

FIG. 7 is a plan view showing an example 711 (i) of the piezoelectric filter of the present invention.

The piezoelectric filter 50 has three elongated rectangular vibrating pieces 51, 52.
．． 53 and the connecting portion 54 are connected to each other by a piezoelectric ceramic plate.
The body is formed. Vibrating piece 51, 52° 53 is vibrating piece 1
1 and the vibrating piece 12, and are C-coupled by a parallel plate capacitor formed in the coupling part 54. 55
and 59 are input/output terminals, 56 is a ground terminal, 57 is a common connection portion of the third electrode, and 58 is a common connection portion of the second electrode. In this way, two or more vibrating pieces can be formed into one body.

FIG. 8 is a perspective view showing still another embodiment of the piezoelectric filter of the present invention.

This piezoelectric filter 60 has a coupling part 61 curved in a U-shape in a vertical plane, and input/output terminals 64 of vibrating pieces 62 and 63.
．． 65 is formed on its lower surface. This is exactly the shape of the piezoelectric filter 10 shown in FIG. 2, which is curved at the joint portion 13. Since the piezoelectric filter 60 can be configured three-dimensionally, the interval between the vibrating pieces 62 and 630 can be narrowed, and the piezoelectric filter 60 can be made smaller in plan. 66 is a ground terminal.

As described above, in the piezoelectric filter of the present invention, the vibrating piece and the coupling part are formed as a single piece of piezoelectric material, and each vibrating piece has a three-terminal type vibrator formed inside that is connected in parallel. This structure constitutes one three-terminal type piezoelectric vibrating element. And each vibrating piece is C-coupled at the connecting part, so the external ☆1
．． Everything except the shield is formed in one piece. Also, as mentioned above, the capacitance between the electrodes can be adjusted freely, and the degree of freedom of the electric current increases by 4, making it possible to miniaturize the shape and groove.

Note that in the embodiment, the C-coupling between the vibrating pieces is performed by one parallel plate capacitor, but it is performed by a plurality of parallel plate capacitors formed by extending a plurality of second electrodes and third electrodes. It's okay. In addition, the position of the second and third electrodes that are not connected to the ground terminal and the input/output terminal (the position of the reverse connection part is not limited to the example, but it is necessary to connect the joint part in such a way that it does not inhibit vibrations). It is preferable to provide the electrode at the end of the vibrating element or near the vibrating element.Also, in the embodiment, the end of the electrode is exposed in addition to the terminal and the common connection part, but it is necessary to expose the end of the electrode in areas necessary to maintain good insulation between the electrodes. You can also just present the cod.

In this manner, the present invention can provide a piezoelectric filter in which C number of three-terminal piezoelectric vibrating elements are coupled together.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional piezoelectric filter, FIG. 2 is a perspective view showing an embodiment 11 of the piezoelectric filter of the present invention, and FIG. 3 is an enlarged sectional view taken along line AA' in FIG. r Figure 4 is a perspective view illustrating an example of the method of manufacturing a piezoelectric filter of the present invention, Figure 5 is a plan view of the piezoelectric filter showing the external connection state, Figure 6M is a wiring diagram, and Figure 7 is a diagram. 8 is a plan view showing an embodiment of the function of the piezoelectric filter of the present invention, and FIG. 8 is a perspective view showing still another embodiment of the piezoelectric filter of the present invention. 1: piezoelectric plate, 2: dot electrode ( L3;'J electrode, 4:
Pressure vibration element, 5, 6, 19, 20, 55, 59, 6
4/65X human output terminal, 10/50/60: Piezoelectric filter, 11-12/5■/52/53/62/63: Vibrating piece, 13/54/61: Coupling part, 14: First electrode,
15: 20th electrode, 16: 30th IM, pole, 17: parallel plate capacitor, 18: outer end surface, 21: side surface. 22/56: Ground terminal, 3o Nigeleen sheet,
31: central part, 32, 33, 34: removed part,
36/37: External terminal. 38, 39, 57, 58: Common connection part. 40: Oscillator patent applicant Toko Co., Ltd. Figure 6 Figure 7

Claims (1)

[Claims] The connecting part that connects a plurality of long rectangular vibrating pieces and their imaging pieces is formed into one piece using a piezoelectric material. One or more pairs of electrodes are laminated and adjacent to each other, each pair consisting of an electrode and a second and third electrode that face the first electrode via a piezoelectric material and extend in the length direction of the vibrating element. The vibrating piece is C-coupled to the stain air bacteria by extending at least one second and third electrodes on the adjacent sides to the joint, and the second and third electrodes of the vibrating piece at both ends are An input/output terminal is formed by exposing the ends of the electrode and the third electrode on one side of the vibrating piece and connecting them in common, and forming a common connection by exposing the first electrode of each vibrating piece near the coupling part. A piezoelectric device characterized in that the connection forms a shearth terminal, and the second and third electrodes, which are not connected to the input/output terminal, are exposed near the joint and are commonly connected. Filter.