JPS6119558Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic filter that is easy to produce, has stable characteristics, and has high strength.

As shown in FIG. 1, the ceramic filter has electrodes 2 formed on both sides of a piezoelectric ceramic body 1, and utilizes the thickness vibration of a vibrator formed by a portion of the electrodes. Therefore, it is necessary for this vibrating portion 3 to be able to vibrate freely, and if distortion or the like is applied, desired characteristics cannot be obtained.

Conventionally, as shown in FIGS. 2A and 2B, a cap 21 is brought into contact with the vibrating part to secure a space, and molding is performed with dip or the like, or paraffin or the like is applied to the vibrating part and then molded. The paraffin was absorbed into the mold resin by heating to create space. However, these ceramic filters are difficult to manufacture, as the cap must be accurately placed against the vibrating part, and heat treatment is required after the resin has hardened, as well as strength problems. I couldn't get anything special.

The object of the present invention is to effectively solve these problems and to provide a ceramic filter which is extremely simple in structure, has excellent strength, and can be manufactured stably and in large quantities.

The present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view showing an embodiment of the present invention.
That is, an electrode 32 is provided on the surface of the piezoelectric ceramic body 31, and a lead terminal 33 is further provided. A bottomed cap 34 is inserted from the end of the piezoelectric ceramic body 31 opposite to the lead terminal. The bottomed cap is made of resin or the like,
A housing portion 36 is formed with a size such that a minute gap 35 is formed between the surface of the element body and the inner surface of the cap, and the depth to the inner bottom surface is sufficient to cover at least the vibrating portion of the electrode. It's deep. By setting such a depth, the operator does not have to worry about accurately coming into contact with the vibrating part, and can simply insert the bottomed cap until it reaches the inner bottom surface, which greatly improves work efficiency. . The bottomed cap and the piezoelectric ceramic body are integrally molded by a mold 37, but when they are integrally molded in, for example, an injection molding machine, the resin does not enter into this minute gap, so it can be freely molded. A space for vibration is secured. This minute gap is conveniently about 10 to 50 microns, and particularly preferably about 10 to 20 microns.

FIG. 4 shows another embodiment of the present invention. Here, the bottomed cap 44 is formed to have a convex portion 48, and by forming it in this way, the position within the molding machine is accurately determined by the convex portion, and when molding 47 is performed, a uniform thickness can be obtained. It can be easily molded and has increased strength.

FIG. 5 shows another embodiment of the present invention, in which the inner surface of the bottomed cap 54 is stepped. It is desirable that this stepped portion 58 be formed with an inclination.
The bottom side of the accommodating portion 56 is sized to fit with the piezoelectric ceramic body, and the opening side is sized to form a minute gap. By forming in this way, minute gaps are formed evenly on both sides of the porcelain body, and the bottomed cap does not move during molding, which brings about favorable results.

As described above, in the present invention, a bottomed cap is inserted from one end side of a piezoelectric ceramic body on which an electrode is formed, and a minute gap is provided between the inner surface of the cap and the vibrating part of the electrode. The ceramic filter is characterized in that the bottom cap and the piezoelectric ceramic body are integrally molded, and it is extremely easy to manufacture, can be produced stably and in large quantities, has excellent strength, and has an extremely high yield. This is an excellent idea.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of the electrode configuration of a ceramic filter. 2A and 2B are schematic diagrams showing a conventional ceramic filter. 3, 4, and 5 are sectional views showing ceramic filters according to embodiments of the present invention.

Claims (1)

[Claims for Utility Model Registration] (1) A bottomed cap is inserted from one edge side of a plate-shaped piezoelectric ceramic element having electrodes formed on both sides so as to cover the electrodes on both sides, and the bottomed cap A ceramic filter having a minute gap between the inner surface of the cap and the vibrating portion of each electrode, and wherein the bottomed cap and the piezoelectric ceramic body are integrally molded. (2) The ceramic filter according to claim 1, wherein the outer surface of the bottomed cap is formed in a convex shape. (3) The ceramic filter according to claim 1, wherein the inner surface of the bottomed cap is stepped.