JPH0379111A - Surface mount type composite piezoelectric element - Google Patents

Abstract

PURPOSE:To make the shape small in size by holding a piezoelectric resonator on one side plate surface of a base made of an insulator and sealing it airtightly with a cover, and connecting a coil formed by forming conductor foil spirally on the internal surface of the cover to the piezoelectric resonator in series. CONSTITUTION:One side plate side of the base 11 molded out of the insulator such as ceramic and glass in a plate shape is covered with the cover 14 made of an insulator such as ceramic and glass as well as the base 11 and sealed airtightly. The coil 15 which is formed spirally of the conductor foil is provided on the internal side of the cover 14. This coil 15 is formed by etching metallic foil stuck on the internal surface of the cover 14 and connected in series with a crystal resonator 13 to increase its equivalent inductance. Consequently, the piezoelectric resonator 13 and the coil 15 which is connected thereto in series are united.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a surface-mounted composite piezoelectric element that integrally combines a piezoelectric resonator and a coil.

(Technical background of the invention and its problems) Recently, various electronic devices are desired to be smaller and lighter.
Additionally, surface-mounted parts are frequently used to automate production and assembly.

For this reason, surface-mounted piezoelectric resonators such as crystal resonators are also provided.

By the way, for example, in a thickness-shear crystal resonator, the resonant frequency is determined by the thickness of the crystal piece, so it is difficult to manufacture a resonant frequency that is too high.

Therefore, when a high frequency oscillation output is required, the fundamental wave signal is multiplied or oscillated with a high-order overtone. By the way, in general, in an oscillation circuit using a crystal resonator, in order to finely adjust the oscillation frequency, a variable capacitor is connected in series with the crystal resonator to precisely tune it to a predetermined oscillation frequency.
In an overtone oscillation circuit, the frequency variable range becomes narrow in inverse proportion to the square of the path order. Therefore, in an overtone oscillation circuit, an inductance is connected in series with the crystal resonator.
That is, a coil is connected to increase the uniformly constrained inductance of the crystal oscillator to widen the frequency variable range to match the desired oscillation frequency.

Conventionally, in circuit configurations like this, the crystal oscillator and coil were each provided separately, but this increased the number of parts and the overall size, and was not electrically appropriate. It was extremely troublesome to select a coil with a suitable value.

(Object of the Invention) The present invention has been made in view of the above circumstances, and it is possible to reduce the size of the piezoelectric resonator and the coil by integrally combining the piezoelectric resonator and the coil. The object of the present invention is to provide a surface-mounted composite piezoelectric element that can be easily assembled and handled.

(Summary of the Invention) The present invention has a piezoelectric resonator held on one side plate surface of a base made of an insulating material, hermetically sealed with a cover, and a coil with a conductive foil spirally formed on the inner surface of the cover. It is characterized in that it is connected in series to the piezoelectric resonator.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the sectional view shown in FIG.

In the figure, reference numeral 11 denotes a base made of an insulating material such as ceramic or glass formed into a plate shape. A pair of holding members 12 are disposed at a predetermined interval on one example of the plate surface of the base 11, and both ends of the crystal resonator 13 are held there. This crystal resonator 13 is made by cutting a quartz crystal at a predetermined angle with respect to the crystal axis, polishing the cut crystal, forming electrodes on the plate surface, and adjusting the resonant frequency to a predetermined value.

Note that on the other side plate surface of the base 11, an electrode 11a is formed for leading out the electrode of the crystal resonator 13 to the outside and mounting it on a printed circuit board (not shown), as shown in FIG. A shield electrode 111) is provided in between.

Then, on one side of the base 11, S is made of ceramic, glass, etc. in the same way as the l\-S 11! ! , a cover 14 made of edge material is placed over it and sealed airtightly.

On the inner surface of the cover 14, a coil 15 made of conductive foil formed in a spiral shape is provided, for example, as shown in FIG. The coil 15 is formed, for example, by etching a metal foil adhered to the inner surface of the cover 14, and is connected in series to the crystal resonator 13 to increase its isometric inductance.

A shield electrode 16 made of metal foil or the like is also formed on the outer surface of the guide bar 14.

With such a configuration, the piezoelectric resonator 13 and the coil 15 connected in series to the piezoelectric resonator 13 can be integrated, and assembly is easy and suitable for mass production.Moreover, the coil 15 can be formed by spirally forming a conductive foil. Coupled with the fact that they are molded, the overall shape can be made significantly smaller than when these are individually sealed, the cost can be reduced, and it is also possible to combine coils 15 of appropriate values.

Since the coil 15 is formed on the inner surface of the cover 14 of the surface-mounted container, the overall shape does not become large and it is easy to handle, resulting in a piezoelectric resonator suitable for an ultra-compact and high-performance overtone oscillation circuit. It will be done.

Note that the present invention is not limited to the above embodiments,
Of course, the analogy can also be applied to piezoelectric resonators such as tantalum oxide.

(Effects of the Invention) As detailed above, according to the present invention, it is possible to provide a composite piezoelectric element that can be miniaturized, is easy to assemble, is inexpensive, and is suitable for mass production.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing an embodiment of the present invention, Fig. 2 is a plan view showing electrodes formed on the bottom surface of the base of the above embodiment, and Fig. 3 is a plan view showing electrodes formed on the inner surface of the cover of the above embodiment. FIG. 3 is a plan view showing a pattern of the coil. 11 Conflict 12 φ l 3 ・ l 4 ・ 15 φ φ Base・・Holding member・・Crystal resonator・Curn − Power bar conflict φ・・Coil 6 ・Shield electrode

Claims (1)

[Claims] A base made of an insulating material, a piezoelectric resonator held on one side of the base, a cover made of an insulating material for airtightly sealing the one side of the base, and a cover of the cover. 1. A surface-mounted composite piezoelectric element comprising a coil made of a spiral conductive foil formed on an inner surface and connected in series to the piezoelectric resonator.