JPH0462491B2 - - Google Patents

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 body 2 . Internal capacitor electrodes 4 are disposed on the left and right sides of the inner peripheral surface 3 of the dielectric 2, facing each other with a predetermined distance apart.
5 is formed. 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. The openings at both ends of the dielectric 2 are covered with metal caps 9 and 10. The recesses of the metal caps 9, 10 are filled with conductive bonding members 11, 12. This joining member 1
By inserting both ends of the piezoelectric resonant element 8 into the piezoelectric resonant elements 1 and 12, the piezoelectric resonant element 8 is arranged and fixed in the internal cavity 7 in such a manner that it does not come into contact with the inner circumferential surface 3 of the dielectric body 2.

In this way, the piezoelectric resonant element 8 is placed in the internal cavity 7.
For example, a capacitor with a structure in which the fourth
It is used as an electronic component of the oscillation frequency determining circuit 14 of the Colpitts type oscillation circuit 13 shown in the figure, which is surrounded by a broken line.

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

Furthermore, it is necessary to form internal capacitor electrodes 4 and 5 on the inner peripheral surface 3 of the dielectric 2, but forming such electrodes 4 and 5 on the inner peripheral surface 3 is technically difficult;
For this reason, it is difficult to obtain a capacitor having a predetermined capacitance with high precision, and there is also a drawback that there is a high probability that the internal capacitor electrodes 4 and 5 will be formed in contact with each other at their opposing ends. .

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 electrodes 4 and 5.

The present invention aims to eliminate such drawbacks.

<Means for solving the problems> In order to achieve such an object, the present invention has the following features:
It is equipped with a cylindrical insulating element containing a piezoelectric resonant element, and on the outer peripheral surface of this insulating element, a capacitor electrode on one side and a capacitor electrode on the other side are laminated with each other with a dielectric interposed therebetween. It is characterized by the fact that it is formed.

<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 a cylindrical insulating body made of alumina porcelain, which is cylindrical in the embodiment. First and second capacitor electrodes 21 and 22, which are capacitor electrodes on one side, are formed on the outer peripheral surfaces of both outer end sides along the longitudinal direction of this insulating element body 20, and these capacitors The electrodes 21 and 22 are spaced apart by a predetermined distance. Further, a dielectric body 23 having a length shorter than the entire length of the insulating element body 20 is formed on the mutually opposing inner end sides of the capacitor electrodes 21 and 22 arranged apart from each other. Furthermore, a third capacitor electrode 24 having a shorter overall length is formed as the other capacitor electrode on the dielectric body 23 at a position corresponding to approximately the center in the longitudinal direction of the insulating element body 20. ing. That is, on the outer peripheral surface of the insulating element body 20 in this piezoelectric resonator with a cylindrical capacitor, the capacitor electrodes 21 and 22 on one side and the capacitor electrode 24 on the other side are formed in a laminated state with a dielectric material 23 in between. has been done.

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 insulating 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 body is provided, and one capacitor electrode, a dielectric body, and the other capacitor electrode are provided in this order on the outer peripheral surface of the insulating body. It is being

Therefore, according to the present invention, the basic structure in terms of the external shape of the capacitor part is determined by the cylindrical insulating element, but the insulating element itself does not need to take into account its dielectric properties. Therefore, 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 insulating element, 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, if the component comes into contact with the capacitor electrode, Accidents can be avoided.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a capacitor portion according to an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view of Fig. 1, Fig. 3 is a longitudinal cross-sectional view of a conventional example, and Fig. 4 is a circuit diagram of a Colpitts type oscillation circuit. It is. 20... Insulating element body, 21, 22, 24... Capacitor electrode, 23... Dielectric material.

Claims (1)

[Claims] 1 It is equipped with a cylindrical insulating element containing a piezoelectric resonator, and on the outer peripheral surface of this insulating element, a capacitor electrode on one side and a capacitor electrode on the other side are laminated with each other with a dielectric interposed therebetween. A piezoelectric resonator with a cylindrical capacitor, characterized by being formed of.