JP2503891Y2 - Ceramic filter - Google Patents

Description

[Detailed description of the device]

[0001]

The present invention relates to an even number of two-element type ceramic filters having two strip-shaped piezoelectric vibrators,
The present invention relates to a ceramic filter having a cascade connection structure.

[0002]

2. Description of the Related Art FIG. 1 shows a structural example of a conventional two-element type ceramic filter. An input lead-out electrode 12 and an output lead-out electrode 13 are formed on the front surface of a frame body 10 made of a thin plate-shaped insulator provided with a punched-out portion 11, and a ground lead-out electrode (not shown) is provided on the back surface. is there. The strip-shaped piezoelectric vibrators 20 and 30 are polarized in the thickness direction and in the same direction, and have electrodes provided on two surfaces perpendicular to the polarization direction, and perform elongation vibration in the length direction.
Two strip-shaped piezoelectric vibrators 20 and 30 are arranged in parallel in the punched portion 11, and an electrode 21 on the surface of the piezoelectric vibrator 20 and an input lead-out electrode 12 and an electrode 31 on the surface of the piezoelectric vibrator 30 are arranged. The output derivation electrodes 13 are connected by lead wires 1 and 2, respectively. Three
Is a connector composed of a conductive wire that crosses the punched portion 11 and has both ends connected to the ground lead electrode of the frame body 10. The electrodes on the back surfaces of the piezoelectric vibrators 20 and 30 are connected and fixed on the connector 3. The connector 3 plays a role of fixing the piezoelectric vibrators 20 and 30 and transmitting the vibration. The input terminal 4, the output terminal 5, and the ground terminal 6 are soldered to the input-leading electrode 12, the output-leading electrode 13, and the ground-leading electrode provided on the frame body 10, respectively.

A ceramic filter having such a structure is
Although it can be used alone as it is, it may be used by connecting several units in series to further enhance the selectivity. FIG. 2 is a conceptual diagram showing an example in which two two-element type ceramic filters are cascade-connected. Four piezoelectric vibrators 20a, 30a, 20
b and 30b are the electrodes 21 and 31 on the front surface to the electrode 22 on the back surface,
It is polarized in the direction of the arrow toward 32. Reference numeral 1 is an input side lead wire, 2 is an output side lead wire, and 7 is a lead wire connecting the electrode 31 of the piezoelectric vibrator 30a and the electrode 21 of the piezoelectric vibrator 20b.

[0004]

The filtering characteristic of this ceramic filter has a waveform in which both sides of the pass band are gently attenuated as shown by a broken line B in FIG. Although the selectivity is improved as compared with the characteristic curve A of the ceramic filter alone, it is still insufficient, and there is a problem that a large amount of attenuation cannot be obtained for signals of channels of adjacent frequencies.

[0005]

An object of the present invention is to improve the selectivity of an even number of two-element type ceramic filters in which two strip-shaped piezoelectric vibrators are connected by a connector. It is a thing.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a strip-shaped piezoelectric vibrator, which is entirely polarized in one direction in the thickness direction and has electrodes provided on two surfaces perpendicular to the polarization direction. In an even number of two-element type ceramic filters connected in series, the polarization direction of one strip-shaped piezoelectric vibrator in any one of the two-element type ceramic filters is changed to the other piezoelectric vibrations. It is characterized by a configuration that is opposite to the polarization direction of the child.

[0007]

FIG. 4 shows an embodiment of the present invention. The arrows in the figure indicate the respective piezoelectric vibrators 20a, 30a, 20b, 30.
The polarization direction of b is shown. That is, the ceramic filter of the present invention comprises four piezoelectric vibrators 20a, 30a, 20b,
Of the 30b, for example, only the piezoelectric vibrator 20b of the two-element type ceramic filter on the right side is connected to the other piezoelectric vibrators 20a, 30b.
a, 30b in the opposite direction from the back electrode 22 to the front electrode 32
The structure is polarized toward. When the filtering characteristic of this ceramic filter was measured, a waveform like a curve C shown by a solid line in FIG. 3 was obtained. It can be seen that in this curve C, poles appear on both sides of the pass band, a large selectivity is obtained, and spurious characteristics are improved. Note that the same result can be obtained by selecting any of the four piezoelectric vibrators 20a, 30a, 20b, 30b as the piezoelectric vibrator whose polarization direction is opposite to that of the other piezoelectric vibrators. The present invention is effective when applied to two-element type ceramic filters connected in an even number of stages. In the case of odd-numbered cascade connections, the phases are reversed even if the polarization directions of all piezoelectric vibrators are the same,
A filtering characteristic with a pole is obtained.

[0008]

EFFECTS OF THE INVENTION According to the present invention, the selectivity characteristic of the ceramic filter is remarkably improved by simply changing the polarization direction of one of the four or more piezoelectric vibrators in the opposite direction. Can be made.

[Brief description of drawings]

FIG. 1 is a front view showing a configuration example of a two-element type ceramic filter.

FIG. 2 is a conceptual diagram of a main part of a conventional cascade type ceramic filter.

FIG. 3 is a filtering characteristic diagram of the conventional and the present invention ceramic filters.

FIG. 4 is a conceptual diagram of a main part of the cascade type ceramic filter of the present invention.

[Explanation of symbols]

 3 Connector 20a Piezoelectric vibrator 20b Piezoelectric vibrator 30a Piezoelectric vibrator 30b Piezoelectric vibrator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Shozo Iwamoto 828 Hinohara, Tamagawa, Hamahara, Hiki-gun, Saitama Prefecture Toko Co., Ltd. Inside the Tamagawa factory (56) Reference JP 61-199316 (JP, A) JP Sho 63-234707 (JP, A) Actual opening 56-116722 (JP, U) Actual opening 59-158319 (JP, U)

Claims (1)

(57) [Scope of utility model registration request] 1. A strip-shaped piezoelectric vibrating device in which the whole is polarized in one direction in the thickness direction and electrodes are provided on two surfaces perpendicular to the polarization direction.
Two devices ceramic filter formed by connecting the two connectives to Doko, even number cascaded connection with the ceramic filter, either one of the 2-element type ceramic filter your <br/> takes one strip-shaped piezoelectric Set the polarization direction of the oscillator to
Ceramic filter, characterized in that the polarization direction opposite to the direction of the piezoelectric vibrator of Te.