JPH06204722A - Manufacture of dielectric filter - Google Patents

Abstract

PURPOSE:To reduce the cost of plural dielectric filters by providing a short- circuit conductor to a 2nd end face in a 1st dielectric block and to a 1st end face in a 2nd dielectric block respectively. CONSTITUTION:A dielectric block 1 having conductors 6, 8, 9 and an assembly by integrating a couple of capacitors 10 and shield members 19 by means of a resin-made insulation cover 18 are prepared to manufacture the dielectric filter. Then each of the two capacitors 10 is inserted simultaneously to each of two resonance throughholes 4. A 1st dielectric filter is obtained by turning over the dielectric block 1 and the assembly so that a 2nd lead wire 17 is located upper and a 1st lead wire 16 is located lower. A short-circuit conductor 9 of the 2nd dielectric block 1 of the 2nd dielectric filter is provided to a 1st end face 2 and a 2nd end face 3 is formed to be an open end face. Thus, a larger diameter part 5a of a coupling hole 5 is set to a lower side and a smaller diameter part 5b is set to an upper side and the coupling capacitor 10 is inserted to the throughhole 4 from the end face 3. As a result, the cost of two kinds of the dielectric filters is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a dielectric filter which can be used in communication devices such as car telephones, personal radios and cordless telephones.

[0002]

2. Description of the Related Art Two resonance through holes are formed in a dielectric block, and an inner conductor film is provided in the resonance through holes.
A dielectric filter is known in which an outer conductor film is provided on the outer peripheral surface of a dielectric block, and coupling holes are provided between the resonance through holes.

[0003]

By the way, in the case of producing dielectric filters having various pass band widths, various molds must be used to prepare porcelain dielectric blocks of various shapes. It was Therefore, the cost of the dielectric filter is inevitably high.

Therefore, an object of the present invention is to provide a method of manufacturing a dielectric filter that can reduce the costs of a plurality of dielectric filters.

[0005]

The present invention for achieving the above object comprises a first dielectric filter having a first characteristic and a second dielectric filter.
And a second end surface facing the first end surface and an outer peripheral surface between the first and second end surfaces. And at least two resonance through holes formed from the first end surface to the second end surface, and a coupling hole, wherein the coupling hole is disposed between the two resonance through holes. Preparing a plurality of dielectric blocks, each of which has a shape and / or position on the first end face of the coupling hole different from the shape and / or position on the second end face of the coupling hole; An inner conductor is formed in two resonance holes of a first dielectric block selected from a plurality of dielectric blocks, an outer conductor is formed on an outer peripheral surface of the first dielectric block, and the inner conductor and the outer conductor are formed on a second end surface of the inner conductor. Of the first characteristic by forming a short-circuit conductor connecting Obtaining a serial first dielectric filter, the inner conductors formed on the two resonance holes of the second dielectric block selected from the plurality of the dielectric block,
Forming an outer conductor on the outer peripheral surface and forming a short-circuit conductor connecting the inner conductor and the outer conductor on the first end surface to obtain the second dielectric filter having the second characteristic; The present invention relates to a method for manufacturing a dielectric filter, which is characterized in that In addition, it is desirable to provide an input coupling capacitor and an output coupling capacitor as described in claim 2. Further, as described in claim 3, the short-circuit conductor can be omitted.

[0006]

According to the present invention, the first dielectric block selected from a plurality of dielectric blocks having the same structure is provided with the short-circuit conductor on the second end face, and the second dielectric block is provided with the first dielectric block. Provide a short-circuit conductor on the end face of. As a result, the first and second dielectric filters having the first and second characteristics can be obtained based on the asymmetry of the coupling hole, and the cost of these can be reduced. Even if the short-circuit conductor is not provided as in the third aspect, the dielectric filters having the first and second characteristics can be obtained from the dielectric blocks having the same structure by changing the connection surface of the coupling capacitor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method of manufacturing first and second 1/4 wavelength distribution constant type dielectric filters according to an embodiment of the present invention will be described with reference to FIGS.

To construct the first and second dielectric filters having different characteristics, a plurality of prismatic dielectric blocks 1 made of barium titanate porcelain are prepared. This dielectric block 1 has two through holes 4 for resonance extending from the first end face 2 to the second end face 3, and further has one coupling hole 5 between them. Each resonance through hole 4 is a circular hole having the same diameter from the first end face 2 to the second end face 3, but the coupling hole 5 has a large diameter portion 5a between the center and the first end face 2. , Has a small diameter portion 5b from the center to the second end face 3. That is, the resonance through-holes 4 are formed symmetrically, but the coupling holes 5 are formed asymmetrically with respect to the virtual plane (central cross section) intermediate between the first end face 2 and the second end face 3. ing.

When constructing the first dielectric filter having the first characteristic, the inner conductors 6 are provided on the wall surfaces of the resonance through holes 4 as shown in FIG. 3, and the inner conductors 6 are provided between the pair of end faces 2 and 3. An outer conductor 8 is provided on the outer peripheral surface 7, that is, four side surfaces, and a short-circuit conductor (end surface conductor) 9 is provided on the second end surface 3 so as to connect the inner conductor 6 and the outer conductor 8. The inner conductor 6, the outer conductor 8 and the end face conductor 9 are made of a conductor film obtained by applying and baking a silver paste.
The first end surface 2 is an open end surface.

In the two resonance through holes 4, the first end face 2 is formed.
The coupling capacitors 10 are inserted from the side.
The coupling capacitor 10 arranged in the through-hole 4 for resonance is
As shown in FIG. 5, the cylindrical ceramic porcelain dielectric 11
Coupled to the first electrode 12 provided on the inner peripheral surface, one end surface and a part of the outer peripheral surface of the dielectric body 11, the second electrode 13 provided on the outer peripheral surface, and the first electrode 12. A first metal cap 14 and a second metal cap 14 coupled to the second electrode 13.
Metal cap 15 and first and second metal caps 1
4 and 15 and first and second lead wires 16 and 17, respectively.

The pair of capacitors 10 are coupled to each other by an insulating cover 18. A metal shield member 19 is further integrated with the insulating cover 18.

When manufacturing this dielectric filter, the dielectric block 1 having the conductors 6, 8 and 9 is prepared, and the pair of capacitors 10 and the shield member 19 are integrated by the insulating cover 18 made of synthetic resin. Prepare the assembly, 2
One capacitor 10 is inserted into the two through-holes for resonance 4 at the same time, and the second lead wire 17 is on the upper side and the first lead wire 16 is on the lower side. Turn upside down. If it is reversed from the beginning, it is not necessary to turn it upside down. Next, several metal particles 20 made of copper having an outer diameter of about 0.2 to 1.0 mm are put into the through hole 4 for resonance. Since the metal particles 20 are sufficiently smaller than the resonance through-hole 4, they can be injected into the resonance through-hole 4 very easily. Further, it is not necessary to specifically position the metal particles 20 with respect to the metal cap 15 and the lead wire 17. Next, cream solder (paste-like solder) is injected into the resonance through-hole 4 and heated in a constant temperature bath. As a result, the cream solder melts and the metal particles 20
Solder between the metal particles 20 and the metal cap 15 and the lead wire 17, and between the metal particles 20 and the inner conductor 6, and the solder 21 and the metal particles 20 cause the metal cap 15 and the leads. The terminal portion composed of the wire 17 and the inner conductor 6 are electrically and mechanically coupled to each other. The shield member 19 has a portion that covers the upper portion of the coupling through hole 5 and a portion that covers the pair of side walls of the dielectric block 1, and is formed to have a U-shaped cross section as a whole. When connecting the completed dielectric filter to an electric circuit, a pair of lead wires 1
One of 6 is an input lead terminal and the other is an output lead terminal, and the shield member 19 is connected to the ground.

FIG. 6 shows an equivalent circuit of the dielectric filter.
The first resonance circuit composed of the capacitor C1 and the inductance L1 is formed based on one inner conductor 6 of the pair of through holes 4, the outer conductor 8 and the short-circuit conductor 9 which are grounded, and the capacitor C2 and the inductance L2. A second resonance circuit consisting of a pair of through holes 4 is formed based on the other inner conductor 6 of the pair of through holes 4, an outer conductor 8 grounded, and a short-circuit conductor 9, and the two resonance circuits are formed by a dielectric impedance Z1. Are combined. The input coupling capacitance Ca corresponds to one of the pair of capacitors 10 and the output coupling capacitance Cb corresponds to the other of the pair of capacitors 10.

The frequency characteristic of the dielectric filter shown in FIG. 3 is shown in FIG.
Becomes the first characteristic line A of By the way, a second dielectric filter having a frequency characteristic as shown by the second characteristic line B in FIG. 8 having a narrower pass band width than the first characteristic line A may be required. In this case, the second dielectric filter shown in FIG. 7 is manufactured. 7, the same parts as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. In the method of manufacturing the second dielectric filter of FIG. 7, the short-circuit conductor 9 is attached to the first end surface 2
The method is the same as that of FIG. That is, the dielectric block 1 of the second dielectric filter of FIG. 7 is the same as that of FIG. 1, but the method of forming the short-circuit conductor 9 is different,
A short-circuit conductor 9 is provided on the first end face 2 and the second end face 3 is an open end face. Therefore, the large diameter portion 5a of the coupling hole 5
Is on the lower side, the small diameter portion 5b is on the upper side, and the coupling capacitor 10 is inserted into the resonance through hole 4 from the second end face 3 side. By arranging the small-diameter portion 5b having a small space on the open end face side in this manner, it is possible to obtain the second dielectric filter having the second characteristic, which has a narrower pass band width than the dielectric filter of FIG.

As described above, if two types of dielectric filters can be obtained by using the dielectric block 1 having the same shape, two types of dielectric filters are produced by using the two types of dielectric blocks. Compared with the case, the cost of the mold for forming the dielectric block can be reduced.

[0016]

MODIFICATION The present invention is not limited to the above-mentioned embodiments, but the following modifications are possible. (1) As shown in FIGS. 9 and 10, the coupling hole 5 has a quadrangular planar shape, the first end surface 2 of the coupling hole 5 is provided with a wide portion 5a, and the second end surface 3 is provided with a narrow portion 5b. May be provided. (2) As shown in FIG. 11, the coupling hole 5 has a rectangular shape,
The first end face 2 may be vertically long, and the second end face 3 may be horizontally long. (3) As shown in FIGS. 12 and 13, the coupling hole 5 may be formed in a truncated cone shape. (4) The coupling hole 5 is not penetrated from the first end face 2 to the second end face 3, but the first end face 2 and the second end face 3 are provided with independent engagement holes having different shapes or positions. Good. (5) The present invention can also be applied to the case where the half-wavelength distributed constant type dielectric filter is formed by omitting the end face conductor film 9. (6) Two or more resonance through holes 4 in the dielectric block 1
Can be provided and two or more coupling holes 5 are provided.

[Brief description of drawings]

FIG. 1 shows a dielectric block according to an embodiment of the present invention.
It is sectional drawing shown by the AA line.

FIG. 2 is a plan view of the dielectric block of FIG.

FIG. 3 is a first configuration using the dielectric block of FIG.
5 is a cross-sectional view showing the dielectric filter of FIG. 4 at a portion corresponding to line BB in FIG. 4.

FIG. 4 is a plan view of the dielectric filter of FIG.

FIG. 5 is an enlarged sectional view of a coupling capacitor.

6 is an equivalent circuit diagram of the dielectric filter of FIG.

7 is a cross-sectional view showing a second dielectric filter using the dielectric block of FIG.

8 is a frequency characteristic diagram of the first and second dielectric filters shown in FIGS. 3 and 7. FIG.

FIG. 9 is a plan view of a modified dielectric block.

10 is a cross-sectional view taken along the line CC of FIG.

FIG. 11 is a plan view of a dielectric block of another modification.

FIG. 12 is a plan view showing still another dielectric block.

13 is a cross-sectional view taken along line DD of FIG.

[Explanation of symbols]

 1 Dielectric Block 2 First End Face 3 Second End Face 4 Resonant Through Hole 5 Coupling Hole

Claims (3)

[Claims] 1. A method of manufacturing a first dielectric filter having a first characteristic and a second dielectric filter having a second characteristic, comprising a first end face and a second end face facing the first end face. At least two through-holes for resonance and coupling holes each having an end face and an outer peripheral surface between the first and second end faces, and formed so as to extend from the first end face to the second end face. And the shape and / or the position of the coupling hole at the first end surface of the coupling hole are arranged between the two through holes for resonance, and the shape and / or position of the coupling hole at the second end surface of the coupling hole are And / or preparing a plurality of dielectric blocks having different positions, and forming inner conductors in the two resonance holes of the first dielectric block selected from the plurality of dielectric blocks, An outer conductor is formed, and the inner conductor and the outer conductor are formed on the second end face. Forming a short-circuit conductor connecting the conductor to obtain the first dielectric filter having the first characteristic; and two resonance holes of a second dielectric block selected from the plurality of dielectric blocks. An inner conductor is formed on the first end surface, and an outer conductor is formed on the outer peripheral surface thereof, and a short-circuit conductor connecting the inner conductor and the outer conductor is formed on the first end surface of the second conductor having the second characteristic And a step of obtaining a dielectric filter. 2. An input coupling capacitor is connected to the inner conductor of the first resonance hole in the first dielectric filter at the first end face side, and the first conductor is connected to the inner conductor of the second resonance hole. An output coupling capacitor is connected on the end face side of the second resonance hole, and an input coupling capacitor is connected on the second end face side to the inner conductor of the first resonance hole in the second dielectric filter. The method of manufacturing a dielectric filter according to claim 1, wherein an output coupling capacitor is connected to the inner conductor on the second end face side. 3. The method of manufacturing a dielectric filter according to claim 2, wherein the first and second dielectric filters have a structure in which the short-circuit conductor is omitted.