JPS628582Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a split electrode type three-terminal ceramic filter used in intermediate frequency amplification circuits of various wireless devices including radios.

Figure 1 shows the structure of a piezoelectric ceramic vibrator 1 used in a split-electrode type three-terminal ceramic filter, in which an entire surface electrode 4 is provided on one main surface of a square plate-shaped piezoelectric ceramic to form a common ground electrode. However, the other main surface is provided with an approximately square inner electrode 2 in the center and an electrically insulated outer electrode 3 surrounding it,
The inner electrode 2 forms an input electrode, and the outer electrode 3 forms an output electrode.

Since the square plate-shaped piezoelectric ceramic vibrator shown in Fig. 1 is excited by peripheral vibration, the vibrator is supported by holding the center of the square plate between the common ground terminal and the input terminal, but the outer electrode In order to obtain an output from the outer electrode 3, it is necessary to contact the output terminal near the center of the side of the square plate of the outer electrode 3.

Figure 2 shows the structure of a conventional split-electrode type three-terminal ceramic filter, in which the input terminal 5 has a tongue in the center and the U-shaped output terminal 6 has tongues on both left and right sides. The input/output electrodes are stacked with each other with an insulating plate 7 in between, and the piezoelectric ceramic vibrator 1 is sandwiched between the common ground terminal 8 and a common ground terminal 8 having a tongue in the center. Output terminal 6
The reason why the tongue pieces are provided on both the left and right sides of the is that if only one side is provided, the pressing force applied to the piezoelectric ceramic vibrator by the tongue pieces of the output terminal will be uneven, and the piezoelectric ceramic vibrator will be tilted and the parts other than the supported part will be uneven. The part comes into contact with the terminal board,
This is to prevent vibration characteristics from deteriorating.

In the conventional structure as explained above, it is necessary to make the input terminal 5 and the output terminal 6 separately, and
It is necessary to insert an insulating plate 7 between the input terminal 5 and the output terminal 6, which has disadvantages in that the number of parts is large, the material cost is high, and automatic assembly of the ceramic filter is difficult.

The present invention improves these drawbacks and provides a split-electrode three-terminal ceramic filter that requires fewer parts and is easier to assemble than the conventional filter.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figure 3 shows the structure of the input/output terminals used in the split electrode type three-terminal ceramic filter of the present invention before assembly, and the input terminals 9 and output terminals 10 are integrally stamped from the same metal plate. A curved portion 11 as shown in the figure is formed at the contact portion of the input terminal 9 with the inner electrode 2 of the piezoelectric ceramic vibrator, and a small protrusion 12 is formed at the apex of the curved portion 11. is formed. Further, the output terminal is lined up with the input terminal 9, and a curved portion 11' similar to the input terminal is formed so as to make contact with the electrode at one central portion of the side of the outer electrode 3 of the piezoelectric ceramic vibrator. A small protrusion 12' is formed at the apex of 11'. Note that the binding material 15 of the input terminals 9 and 10 is
After the filter is assembled, it is separated by cutting along the dashed line in the figure.

FIG. 4 shows the structure of the case 13 used in the split electrode type three-terminal filter of the present invention.
When the input/output terminals 9 and 10 shown in the figure are placed in the case, as shown by the dotted lines, the small protrusion 1 of the input terminal 9
A protrusion 14 is formed at a position symmetrical to the small protrusion 12' of the output terminal 10 with respect to the output terminal 10. Protrusion 1
The height of 4 is the same as the height from the bottom of the input or output terminal to the tip of the small protrusion. When the case and input/output terminal of the present invention are used, the piezoelectric ceramic vibrator is electrically connected by the input terminal 9 and the output terminal 10, and structurally the small protrusion 1 of the output terminal 10 is connected.
2' and the protrusion 14 inside the case, balance is maintained, and the characteristics are exactly the same as the conventional one.

As shown above, by using the case and input/output terminal of the present invention, an insulating plate becomes unnecessary, and the input/output terminal is formed integrally by punching from a single metal plate and then assembled. Since the process can be adopted, the number of parts is reduced, resulting in a significant reduction in material costs, and at the same time, it is possible to automate filter assembly with a simple mechanism, which has great effects.

[Brief explanation of the drawing]

Figures 1a and 1b are a plan view of a piezoelectric ceramic vibrator for a split electrode type three-terminal ceramic filter, and A-A.
In the cross-sectional view, 1 is a vibrator, 2 is an inner electrode, 3 is an outer electrode, and 4 is a common ground electrode. FIG. 2 is a structural diagram of a conventional split electrode type three-terminal ceramic filter, in which 5 shows an input terminal, 6 an output terminal, 7 an insulating plate, and 8 a common ground terminal. FIG. 3 is a perspective view of the input/output terminal of the present invention, where 9 is an input terminal, 10 is an output terminal, 11 and 11' are curved portions, and 12 and 12' are small protrusions. FIG. 4 is a perspective view of the outer case 13 of the present invention.
14 indicates a protrusion.

Claims (1)

[Scope of utility model registration request] A piezoelectric vibrator with an input electrode and an output electrode formed concentrically on one main surface of a square plate-shaped piezoelectric ceramic and a common ground electrode formed on the entire other main surface is housed in a case, and the input electrode and output electrode are arranged in a case. In a ceramic filter in which the input terminal, output terminal, and common ground terminal connected to the electrode and the common ground electrode are drawn out to the outside of the case, the input terminal and the output terminal are pressure-welded at positions facing the input electrode and the output electrode, respectively. The case includes an insulator protrusion on the inner surface facing the input/output electrode surface of the vibrator at a position symmetrical to the protrusion of the output terminal with respect to the protrusion of the input terminal. A split-electrode three-terminal ceramic filter that stably supports the vibrator.