JPS6214509A - Piezoelectric resonator with cylindrical capacitor - Google Patents

Abstract

PURPOSE:To improve the mechanical strength by providing one capacitor electrode, a dielectric, and the other capacitor electrode in order on the outside peripheral surface of a cylindrical insulating element assembly and determining the fundamental structure of a capacitor by the insulating element assembly to give the degrees of freedom to selection of materials. CONSTITUTION:A piezoelectric resonator 25 is incorporated in a magnetic element assembly 20 of a piezoelectric resonator with a cylindrical capacitor, and the magnetic element assembly 20 is formed cylindrically. The first and the second capacitor electrodes 21 and 22 whose both end parts are a prescribed length distant from each other are formed on upper right and left sides of the outside peripheral surface of the magnetic element assembly 20. A dielectric 23 shorter than the length in the lengthwise direction of the magnetic element assembly 20 is formed on electrodes 21 and 23 in the center of the magnetic element assembly 20. The third electrode 24 is formed on the dielectric 23, and the fundamental structure of the capacitor is determined by the magnetic element assembly to select freely materials, thus improving the mechanical strength.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a piezoelectric resonator with a cylindrical capacitor.

<Prior Art> FIG. 3 is a sectional view of a conventional piezoelectric resonator with a cylindrical capacitor. This piezoelectric resonator 1 has a capacitor and includes a cylindrical dielectric 2 . Internal capacitor electrodes 4.about.5 are formed on the left and right sides of the inner circumferential surface 3 of the dielectric body 2, facing each other at a predetermined distance. Furthermore, an external capacitor electrode 6 is formed approximately at the center of the outer circumferential surface of the dielectric 2 . Therefore, in this capacitor, one internal capacitor electrode 4 and external capacitor electrode 6 form a first capacitor part, and the other internal capacitor electrode 5 and external capacitor electrode 6 form a second capacitor part.

A piezoelectric resonant element 8 such as an energy trap type thickness shear vibration type is inserted into the internal cavity 7 of the dielectric body 2. Metal caps 9 are provided at both end openings of the dielectric 2. l
O is covered. The recess of this metal cap 9.10 is filled with an electrically conductive joining member 11.12. By inserting both ends of the piezoelectric resonant element 8 into the joining members 11 and 12, the piezoelectric resonant element 8 is placed and fixed in the internal cavity 7 in a state where it does not come into contact with the inner circumferential surface 3 of the dielectric body 2. Ru.

In this way, a capacitor having a structure in which the piezoelectric resonant element 8 is inserted into the internal cavity 7 can be used as an electronic component of the oscillation frequency determining circuit 14 of the Colpitts type oscillation circuit 13 surrounded by the broken line as shown in FIG. 4, for example. used.

<Problems to be Solved by the Invention> By the way, in such a configuration, the basic structure of making the capacitor cylindrical is determined by the dielectric 2;
The dielectric 2 itself has a disadvantage in that it is inferior in mechanical strength and is easily damaged during handling.

Also, an internal capacitor electrode 4.5 is provided on the inner circumferential surface 3 of the dielectric 2.
However, it is technically difficult to form such electrodes 4 and 5 on the inner circumferential surface 3. Therefore, it is difficult to obtain a capacitor having a predetermined capacitance with high precision, and there are There is a drawback that there is a high probability that the capacitor electrodes 4.5 will be formed in a state where their opposite ends are in contact with each other.

Furthermore, since it is relatively difficult to accurately insert the piezoelectric resonant element 8, there is a drawback that there is a high probability that the piezoelectric resonant element 8 will come into contact with the internal capacitor electrode 4.5.

The present invention aims to eliminate such drawbacks.

<Means for Solving the Problems> In order to achieve such an object, the present invention is provided with a cylindrical insulating body, and on the outer peripheral surface of the insulating body, one capacitor electrode, a dielectric material, and the other side are arranged. capacitor electrodes are provided in this order.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings. FIG. 1 is a perspective view of a capacitor portion according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of FIG. 1.

In these figures, 20 is cylindrical, in the example it is cylindrical;
It is an alumina porcelain body. On both sides of the outer peripheral surface of the porcelain body 20 in the left-right direction in the figure, there are two first porcelain bodies with their ends separated by a predetermined distance from each other. A second capacitor electrode 21,22 is formed. And porcelain body 20
approximately at the center of each of these capacitor electrodes 2
A dielectric body 23 having a length slightly shorter than the longitudinal length of the porcelain body 20 is formed on the porcelain body 20 . Further, a third capacitor electrode 24 is formed approximately in the center of the ceramic body 20 and on the dielectric body 23 .

The capacitor portion of this embodiment has such a structure.

When this capacitor part is used as a component of the oscillation frequency determining circuit 14 of the oscillation circuit 13 as shown in FIG. Placed.

Although the porcelain element body 20 in the embodiment has a cylindrical shape, it is of course possible to have a rectangular cylinder shape or other shapes other than the cylindrical shape.

Effects> As described above, according to the present invention, a cylindrical insulating element is provided, and one capacitor electrode, a dielectric, and the other capacitor electrode are provided in this order on the outer peripheral surface of the insulating element. ing.

Therefore, according to the present invention, the basic external structure of the capacitor part is determined by the cylindrical insulating element, but the insulating element itself does not need to take into account the characteristics of a dielectric. , the range of material selection is expanded, and a capacitor with high mechanical strength and easy handling can be obtained.

In addition, since the capacitor electrode is formed on the outer peripheral surface of the porcelain body, it is easier to form the capacitor electrode than in the conventional case where the capacitor electrode is formed on the inner peripheral surface of the dielectric. The probability that the electrodes are formed in contact with each other is also extremely low.

Furthermore, since no capacitor electrode is formed on the inner peripheral surface of the insulating element, when a component such as the piezoelectric resonant element is inserted into the internal cavity of this insulating element, the component may come into contact with the capacitor electrode. Things like this can be avoided.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a capacitor portion according to an embodiment of the present invention, Fig. 2 is a longitudinal sectional view of Fig. 1, Fig. 3 is a longitudinal sectional view of a conventional example, and Fig. 4 is a circuit diagram of a Colpitts type oscillator circuit. It is. 20... Insulating element body, 21, 22.24... Capacitor electrode, 23... Dielectric material.

Claims (1)

[Claims] (1) Equipped with a cylindrical insulating element containing a piezoelectric resonant element,
A piezoelectric resonator with a cylindrical capacitor, characterized in that one capacitor electrode, a dielectric, and the other capacitor electrode are provided in this order on the outer peripheral surface of the insulating element.