JPH0677706A - Dielectric filter - Google Patents

Abstract

PURPOSE:To facilitate the fitting of a polarized capacitor and reduce the size of the filter by holding the polarized capacitor so that it can electrically be connected to lead terminals. CONSTITUTION:A filter body 2 is formed by arranging two independent dielectric resonators 9 and 10 adjacently and joining them by electromagnetic field coupling. The resonator 9 has a through hole 12 in the center part of a dielectric block 11 and is equipped with a cavity 13 which contains an input/output capacity 3 at an open-end-surface side opening part in front of the hole 12. The lead terminals 4 and 5 are fitted to the external electrode 18 of the capacitor 3 and the lead terminals 5 consists of lead parts 20, joint parts 21, and bent parts 22. The polarized capacitor 6 consists of a stripped dielectric substrate 6a, electrodes 25 are formed at both length-directional ends of one surface of the substrate 6a, and a gap part 24 is formed between both the electrodes 25 to obtain an electrostatic capacitor. The capacitor 6 is held at the bent parts of the terminals 4 and 5 and the electrode 25 abuts on the bent parts 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter, and more particularly to a dielectric filter having at least one pair of dielectric resonators arranged in parallel by electromagnetic field coupling.

[0002]

2. Description of the Related Art As a dielectric filter used for communication equipment, a multi-stage dielectric filter is already known for the purpose of obtaining a filter characteristic having a desired frequency band. Japanese Unexamined Patent Publication No. 62-77703 discloses a structure in which resonators of this type of dielectric filter are connected by reactance elements in order to have a pole in the attenuation region of the filter characteristic (to polarize). There is.

In the dielectric filters disclosed in JP-A-3-158001 and JP-A-3-65302, a polarized dielectric substrate having a predetermined electrode pattern is used as a reactance element. A hole is provided in this polarized dielectric substrate, and a terminal of the dielectric resonator is passed through the hole and fixed by soldering. In such a dielectric filter, workability is poor because it is not easy to pass the terminal through the hole of the polarized dielectric substrate.

In the dielectric filters disclosed in Japanese Utility Model Laid-Open No. 3-79503 and Japanese Utility Model Laid-Open No. 3-84602, a polarized dielectric substrate is arranged horizontally with respect to a case, and a dielectric resonator is provided. The soldering is performed so that the terminals of the above are placed on the electrode surface of the polarized dielectric substrate. In this structure, the polarized dielectric substrate horizontally arranged on the bottom surface of the case increases the bottom area of the entire dielectric filter, so that the miniaturization required as a surface mount component cannot be sufficiently achieved.

An object of the present invention is to obtain polar characteristics by an easy operation while achieving miniaturization.

[0006]

A dielectric filter according to the present invention corresponds to at least one pair of dielectric resonators having open end faces and arranged in parallel by electromagnetic coupling, and the dielectric resonator. At least one pair of lead terminals, an input / output capacitor arranged between the open end surface of the dielectric resonator and the lead terminal, and a polarized capacitor arranged between the lead terminals. . The polarized capacitor is a dielectric substrate including a gap portion and a pair of electrodes sandwiching the gap portion. The lead terminal has a holding portion that holds the dielectric substrate and is electrically connected to the electrode.

[0007]

In the dielectric filter according to the present invention, the polarized capacitor is held by the holding portion provided on the lead terminal so as to be electrically connectable to the lead terminal. In such a configuration, the work of attaching the polarized capacitor to the lead terminal is facilitated, and the polarized capacitor can be arranged in parallel with the open end face of the dielectric resonator. Is more miniaturized.

[0008]

1 and 2 show a dielectric filter 1 as an embodiment of the present invention. It should be noted that FIG. 1 shows a state in which the upper case 7 in FIG. 2 is removed or the hook 30 is not fixed. In the figure, a dielectric filter 1 is mainly composed of a filter body 2 in which a pair of dielectric resonators 9 and 10 are arranged in parallel, and an open end face side of the dielectric resonators 9 and 10 (front side in FIG. 1). And a pair of connection terminals 4 and 5 respectively connected to each capacitor 3, and a polarization capacitor 6.

The filter body 2 is formed by adjoining two independent dielectric resonators 9 and 10 by electromagnetic field coupling. As shown in FIG. 2, the dielectric resonator 9 has a rectangular parallelepiped dielectric block 11. A cylindrical through hole 1 extending in the longitudinal direction is provided at the center of the dielectric block 11.
2 is formed. Front of the through hole 12 (left side of FIG. 2)
A cavity 13 is provided in the open end face side opening of the. The capacitor 3 is housed in the cavity 13.

An inner conductor 14 is attached to the inner peripheral surface of the through hole 12 and the surface of the cavity 13. An outer conductor 15 is attached to the outer peripheral surface of the dielectric block 11 except for the open end surface on the cavity 13 side. This outer conductor 1
5 is short-circuited to the inner conductor 14 at the rear end surface of the dielectric block 11. Electromagnetic field coupling is formed at the joining portion of the dielectric resonators 9 and 10 by a rectangular hole 16 extending in a direction orthogonal to the through hole 12 without a conductor film.

The resonator 10 is constructed similarly to the resonator 9 and is also provided with the capacitor 3.
The input / output capacitor 3 includes a circular dielectric 17, and outer electrodes 18 and inner electrodes 1 arranged on both surfaces of the dielectric 17.
It is composed of 9 and 9. The inner electrode 19 of the input / output capacitor 3 is connected to the inner conductor 14 in the cavity 13. Lead terminals 4 and 5 are attached to the outer electrode 18 of the input / output capacitor 3.

As shown in FIG. 3, the lead terminal 5 includes a lead portion 20 protruding in a direction away from the capacitor 3 side.
It is composed of a joint portion 21 formed at the other end of the lead portion 20 and a bent portion 22. The joint portion 21 has a rectangular shape. A hole 21 a for cream solder injection is formed in the center of the joint portion 21. The hole 21a has a diameter of about 1 mm. The bent portion 22 is bent in an L shape from the lower portion of the joint portion 21 to the protruding side of the lead portion 20. The lead terminal 4 and the lead terminal 5 are bilaterally symmetrical.

The polarized capacitor 6 is composed of a strip-shaped dielectric substrate 6a. Electrodes 25 are formed on both ends of one surface of the dielectric substrate 6a in the longitudinal direction. Both electrodes 25
A gap portion 24 is provided between the gaps, and with such a configuration, a capacitance for polarization can be obtained. The polarized capacitor 6 is held by the bent portions 22 of the lead terminals 4 and 5, and the electrode 25 is in contact with the bent portions 22 of the lead terminals 4 and 5.

As shown in FIG. 2, solder 30 is injected into the hole 21a of the joint portion 21 of the lead terminals 4 and 5. The solder 30 electrically and mechanically joins the lead terminals 4 and 5 to the outer electrode 18 of the input / output capacitor 3. The cases 7 and 8 are flat metal members. The lower case 8 is provided with a ground terminal protruding in the horizontal direction, and FIG. 1 shows the ground terminal 32 provided in the lower case 8.

Next, a method of manufacturing the dielectric filter 1 will be described. First, cream solder is applied on the lower case 8, and the filter body 2 is placed thereon. next,
The inner electrode 19 of the capacitor 3 and the inner conductor 14 inside the cavity 13 are temporarily fixed by cream solder. Then, the lead terminals 4 and 5 are brought into contact with the outer electrode 18 and the holes 2
Cream solder is injected into 1a to temporarily fix both. The lead terminals 4 and 5 are integrally connected to a lead frame formed by punching a metal plate flat surface and bending it.
At the time of temporary fixing, the polarized capacitor 6 is held in advance in the bent portions 22 of the lead terminals 4 and 5. In this way
Polarized capacitor 6, lead terminals 4, 5 and external electrode 18
And the temporary stop are done at the same time. The polarized capacitor 6 need only be mounted on the holding portions 22 of the lead terminals 4 and 5 and can be easily mounted.

Next, the upper case 7 is covered over the filter body 2 with cream solder. Then, the dielectric filter 1 in which the upper and lower cases 7 and 8 are assembled is passed through a reflow furnace, and the temporarily fixed joints are soldered.
As a result, it is possible to join all joints in one soldering step. Next, the lead terminals 4 and 5 joined to the outer electrode 18 are cut from the lead frame at predetermined portions. As a result, the lead terminals 4 and 5 are separated and become independent terminals. The lead terminals 4 and 5 may be formed of a lead frame integrated with the lower case 8. As a result, the ground terminal 32 and the lead terminal 4,
The height of the lead portion 20 of No. 5 easily becomes constant, and a product suitable for surface mounting can be obtained.

FIG. 4 shows an equivalent circuit of the dielectric filter 1. Here, Cgap is the electrostatic capacitance by the gap portion 24 between the pair of electrodes 25, C _IN and Cout are the input / output capacitors 3, and K is the electromagnetic field coupling by the square hole 16. As described above, the polarized capacitor 6 is easily attached to the lead terminals 4 and 5 by the bent portions 22 of the lead terminals 4 and 5. Moreover, since the polarized capacitor 6 is attached by the bent portion 22 so as to be substantially parallel to the open side end faces of the resonators 9 and 10, that is, to be perpendicular to the cases 7 and 8, the dielectric filter The bottom area of 1 does not increase and the size can be reduced.

Other Embodiments (a) The lead terminals 4 and 5 may be provided with a bent portion 27 as shown in FIG. 5 (only the lead terminal 5 is shown in FIG. 5). The bent portion 27 is the joint portion 2 of the lead terminal 5.
1 extends from one side portion to the other side portion substantially in parallel with the joint portion 21, and a folded portion 27a that supports the lower portion of the polarized capacitor 6 is formed at the tip. Also in the above structure, the same effect as that of the above embodiment can be obtained. Further, since the bent portion 27 is formed from one side portion of the joint portion 21, the positioning when mounting the polarized capacitor 6 is easily and accurately performed. (B) In the above embodiment, the number of dielectric resonators was two, but the present invention can be applied to a dielectric filter using three or more dielectric resonators. In that case, a polarized capacitor having electrodes formed on a dielectric substrate corresponding to the lead terminals is used.

[0019]

In the dielectric filter according to the present invention, the polarized capacitor can be electrically connected to the lead terminal by the holding portion provided on the lead terminal. Since the work for attaching the polarized filter can be facilitated and the polarized capacitor can be arranged so as to be parallel to the open end face of the dielectric resonator, the size of the dielectric filter can be further reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a dielectric filter as an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a perspective view of a lead terminal.

FIG. 4 is an equivalent circuit diagram of the embodiment of FIG.

FIG. 5 is a view corresponding to FIG. 3 of another embodiment.

[Explanation of symbols]

 1 Dielectric Filter 4, 5 Lead Terminal 6 Polarizing Capacitor 6a Dielectric Substrate 9, 10 Dielectric Resonator 3 In / Out Capacitor 24 Gap 25 Electrode

Claims (1)

[Claims] 1. At least one pair of dielectric resonators having open end faces and arranged in parallel by electromagnetic field coupling, and at least one pair of lead terminals provided corresponding to the dielectric resonators. A dielectric filter comprising an input / output capacitor arranged between the open end face of the dielectric resonator and the lead terminal, and a polarized capacitor arranged between the lead terminals, wherein the polarized capacitor Is a dielectric substrate composed of a gap portion and a pair of electrodes sandwiching the gap portion, and the lead terminal has a holding portion which holds the dielectric substrate and is electrically connected to the electrodes. A dielectric filter characterized in that