JPH06204786A - Ladder type electric filter - Google Patents

Abstract

PURPOSE:To make the weight of a radio communication equipment or the like light and the size small by reducing the number of mounted ladder type filters F on a printed circuit board (p). CONSTITUTION:Container air gaps 4L, 4R are formed to the left and right parts in a single case 1 and a unit filter circuit C1(C2) each composed of two series resonators S1, S2 (S3, S4) and two parallel resonators P1, P2 (P3, P4) connected together are built in the air gap. Thus, the filter circuit equivalent to two ladder filters F of conventional configuration is built in and the number of mounts of the filters on a printed circuit board (p) is halved and the installed area is made small and the configuration contributes to the light weight and the small size of a radio communication equipment or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a filtering circuit of a wireless communication device such as a portable mobile radio device and a car telephone, and is mounted on a printed board to construct a required filtering circuit. The present invention relates to a ladder-type electric filter in which a series resonator and a parallel resonator that form a unit filtering circuit are housed in a case.

[0002]

2. Description of the Related Art In a ladder type electric filter, one side electrode of a series resonator is connected to an input side, one side electrode of a parallel resonator is connected to a ground side, and the other side electrode of the series resonator and a parallel resonator are connected. The other side electrode is connected to the output side. A ladder-type electric filter of this type is usually constructed by housing a unit filtering circuit formed by connecting two series resonators and two parallel resonators.

[0003]

The ladder type electric filter has been multi-staged so as to operate accurately at the center frequency of 455 KHz, and a large number of ladder type electric filters are mounted on the printed circuit board. By the way, in such mounting, each electric filter is supported by four claws by a robot or the like and sequentially mounted, and it is necessary to provide a gap between the electric filters in order to enable the opening operation of the claws. Therefore, as the number of stages increases, it becomes necessary to secure a wide installation surface, which hinders weight reduction and size reduction of wireless communication devices and the like.

An object of the present invention is to reduce the number of ladder type electric filters to be mounted so that the installation area can be small.

[0005]

SUMMARY OF THE INVENTION According to the present invention, in a rectangular case, a storage space which is partitioned by a partition wall and is open on one side is formed on the left and right sides, and two series resonances are provided in each storage space. Housing a unit filtering circuit formed by connecting a child and two parallel resonators, and connecting both unit filtering circuits with a connecting terminal plate arranged across both housing voids, and connecting one unit filtering circuit. Between the parallel resonators of the circuit and between the other parallel resonators are connected to a ground terminal plate arranged across the storage space, and the input terminal plate is connected to the electrode of the series resonator in the preceding stage of one unit filtering circuit. And further connecting the output terminal plate to the electrode of the series resonator of the latter stage of the other unit filtering circuit, the ground terminal plate and the input terminal plate,
It is characterized in that each connecting branch piece of the output terminal board is configured to project outside the case.

[0006]

In the single case, two unit filtering circuits, which are formed by connecting two series resonators and two parallel resonators, are built in on the left and right sides. Therefore, it is possible to configure a ladder type electric filter having double the filtering capability as compared with the conventional configuration.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A ladder type electric filter F to which the present invention is applied will be described with reference to FIGS. Reference numeral 1 denotes a rectangular case made of a synthetic resin material having an opening 2 formed on one surface thereof, and a partition wall extending from the opening 2 to the inner depth with a gap filled with a sealing resin 41 described later. 3 is formed in the center thereof, and left and right storage voids 4L, which communicate with the openings 2 inside,
4R is partitioned and formed. In addition, an L-based communication groove 5 is formed in the partition wall 3. The communication groove 5 will be described later.
A connecting terminal plate 8 for connecting unit filtering circuits provided in the left and right storage spaces 4L, 4R is fitted. This connecting terminal plate 8 has a connecting portion 8c in the vertical direction as shown in FIG.
The left and right connecting plate portions 8L and 8R are connected to each other by forming a step in the vertical direction, and the connecting portion 8c is fitted into the communication groove 5 from the opening 2 side so as to connect the storage voids 4L and 4R. Is installed in.

Further, as shown in FIG. 4, a forked ground terminal plate 6 is integrally provided on the case 1 by molding so as to cross the case 1, and the ground terminal plate 6 is connected to the case 1. The connection plate portions 6L and 6R are stored in the storage spaces 4L and 4 respectively.
Insert into R to divide the storage voids 4L, 4R into upper and lower parts,
As a result, the storage spaces 4L and 4R are provided so as to communicate with each other. The continuous base ends of the connecting plate portions 6L and 6R are the openings 2
The connecting branch piece 6t is embedded in the side wall surface opposite to, and projects from the continuous base end to the outside of the case 1.

As shown in FIG. 6, in addition to the connecting branch piece 6t, a connecting branch piece 7t of the input terminal board 7 and a connecting branch piece 12t of the output terminal board 12 are seated on the back surface of the case 1, respectively. Three groove surfaces f are formed.

The connecting plate portion 6 is provided in the one accommodation space 4L.
The series resonator S ₁ and the parallel resonator P ₁ are stacked on the L, and the parallel resonator P ₂ and the series resonator S ₂ are stacked under the connecting plate portion 6L, as shown in FIGS. 1 and 3. The layers are electrically connected to each other.

That is, the input terminal plate 7 shown in FIG. 5B is arranged on the outer surface (upper surface) electrode of the series resonator S ₁ .
The connecting branch piece 7t projects outward from the opening 2. Further, between the series resonator S ₁ and the parallel resonator P ₁ , an auxiliary terminal plate h and a connecting plate portion 9u of the connecting terminal plate 9 are interposed and electrically connected. The parallel resonator P ₁ and the parallel resonator P ₂ are electrically connected to each other with the auxiliary terminal plate h and the connecting plate portion 6L of the ground terminal plate 6 interposed. Also,
An auxiliary terminal plate h is provided between the parallel resonator P ₂ and the series resonator S _2.
And the connection plate portion 8L of the communication terminal plate 8 is interposed and electrically connected. Further, the connection plate portion 9d of the connection terminal plate 9 is disposed on the outer surface (lower surface) electrode of the series resonator S ₂ , and the series resonator S ₁ and the parallel resonator P are connected via the connection terminal plate 9. _{I am} trying to connect between _one . Then, by such connection, as shown in FIGS.
_Make up _one .

Next, in the other accommodation space 4R, the series resonator S ₃ and the parallel resonator P ₃ are stacked on the connecting plate portion 6R, and the parallel resonator P ₄ and the serial resonator P ₄ are connected under the connecting plate portion 6R. Resonator S
₄ are stacked and electrically connected on each stacking surface as shown in FIGS. 1 and 3.

That is, the connection plate portion 8R of the connecting terminal plate 8 is interposed between the outer surface (upper surface) electrode of the series resonator S ₃ and the parallel resonator P ₂ in the storage space 4L and the series resonance. It is connected to the child S ₂ and is thereby connected to the unit filtering circuit C ₁ . Further, between the series resonator S ₃ and the parallel resonator P ₃ , the auxiliary terminal plate h and the connecting plate portion 11u of the connecting terminal plate 11 are connected.
Is interposed and electrically connected. The parallel resonator P ₃ and the parallel resonator P ₄ are electrically connected to each other via the auxiliary terminal plate h and the connecting plate portion 6R of the ground terminal plate 6. An auxiliary terminal plate h and an output terminal plate 12 shown in FIG. 5C are arranged between the parallel resonator P ₄ and the series resonator S ₄ , and the connecting branch piece 12t is projected outward from the opening 2. There is. Further, a connection plate portion 11d of the connection terminal plate 11 is arranged on an outer surface (lower surface) electrode of the series resonator S ₄ , and the electrode is connected to the series resonator S via the connection terminal plate 11.
₃ , the parallel resonator P ₃ is connected. The unit filtering circuit C ₂ is configured by such connection as shown in FIGS.

Then, as described above, the storage voids 4L, 4R
The respective mounting members are inserted into, the bottom plate 40 is fitted into the opening 2, and the sealing resin 41 such as epoxy resin is injected as shown in FIG. In the ladder type filter F having such a configuration, the connecting branch piece 7t of the input terminal plate 7 and the connecting branch piece 12t of the output terminal plate 12 project from the opening 2, and from the surface facing the opening 2,
The connecting branch piece 6t of the ground terminal plate 6 projects. Then, each is bent along the side surface at the projecting base end, and further, the end edge portion is bent inward and fitted into the groove surface f, respectively. Thus, the ladder type filter F is mounted on the required conductive path of the printed board, and the connecting branch pieces 6t, 7t, 12t are soldered.
In this case, one side of the ladder type filter F is connected to the connecting branch piece 6
It is supported by joining t, and the other side is connected with branch pieces 7t, 12t.
It can be stably mounted by being supported by the joining of the above, being held on both sides.

In such a structure, the ladder type filter F has unit filtering circuits C ₁ and C ₂ built therein, and a circuit corresponding to two ladder type filters F having the conventional structure. Therefore, the number of mountings on the printed circuit board p can be halved, and the installation area can be reduced, which can contribute to weight reduction and size reduction of the wireless communication device and the like.

7 to 12 show another embodiment of the present invention.

Here, the storage voids 24L, 2 of the case 21
In the partition wall 23 that divides the 4R, a communication groove 24a into which the connecting portion 26c of the ground terminal plate 26 shown in FIG. 11B is fitted and a communication groove 24b into which the connecting portion 28c of the communication terminal plate 28 is fitted are formed. There is.

In this structure, the mounting members are fitted in the storage space 24L in the same arrangement order as in the above-described embodiment, and the series resonator S ₄ and the parallel resonator P are housed in the storage space 24R.
₄ , the parallel resonator P ₃ and the series resonator S ₃ are stacked in this order. Then, as described above, the ground terminal plate 26 and the communication terminal plate 28 are mounted so as to communicate the storage spaces 24L and 24R from the opening 22. Here, the connecting branch piece 26t of the ground terminal plate 26 extends from the connecting portion 26c.

The series resonator S is placed in the storage space 24L.
₁ , parallel resonator P ₁ , parallel resonator P ₂ , series resonator S ₂
Are sequentially laminated, and are electrically connected at each laminated surface as shown in FIGS. 7 and 9.

That is, an input terminal plate 27 similar to that shown in FIG. 5B is arranged on the outer surface (upper surface) electrode of the series resonator S ₁ and the connecting branch piece 27t thereof is projected outward from the opening 22. . Further, between the series resonator S ₁ and the parallel resonator P ₁ , an auxiliary terminal plate h and a connecting plate portion 29u of the connecting terminal plate 29 are interposed and electrically connected. And the parallel resonator P ₁
And the parallel resonator P ₂ are electrically connected to the auxiliary terminal plate h via the connecting plate portion 26L of the ground terminal plate 26. Further, between the parallel resonator P ₂ and the series resonator S ₂ , the auxiliary terminal plate h and the connecting plate portion 28L of the connecting terminal plate 28 are interposed and electrically connected. Furthermore, the series resonator S
The connecting plate portion 29d of the connecting terminal plate 29 is disposed on the outer surface (lower surface) electrode of ₂ , and is connected between the series resonator S ₁ and the parallel resonator P ₁ via the connecting terminal plate 29. There is. Then, by such connection, the unit filter circuit C ₁ is configured as shown in FIGS.

On the other hand, each mounting member is assembled in the storage space 24R as follows.

That is, the connection plate portion 31u of the connection terminal plate 31 is arranged on the outer surface (upper surface) electrode of the series resonator S ₄ . Further, between the series resonator S ₄ and the parallel resonator P ₄ , an auxiliary terminal plate h and an output terminal plate 32 similar to those shown in FIG. 5C are arranged, and the connecting branch piece 32t thereof is projected outward from the opening 22. ing.

The parallel resonator P ₃ and the parallel resonator P ₄
Is the auxiliary terminal plate h and the connecting plate portion 2 of the earth terminal plate 26.
It is electrically connected via 6R. Further, between the parallel resonator P ₃ and the series resonator S ₃ , the auxiliary terminal plate h and the connecting plate portion 31d of the connecting terminal plate 31 are interposed and electrically connected. The outer surface (lower surface) electrodes of the series resonator S _3, connecting plate portion 28R of the contact terminal plate 28 is interposed,
The parallel resonator P ₂ and the series resonator S ₂ in the storage space 24L are connected to each other, and the connection forms a unit filter circuit C ₂ as shown in FIGS. Then, the connecting terminal plate 28 is connected to the unit filtering circuit C ₁ .

With this connection, unit filtering circuits C ₁ and C ₂ are formed in the storage voids 4L and 4R, the bottom plate 40 is fitted in the opening 22, and the sealing resin 41 is injected, so that the ladder filter F is inserted. Is configured.

In such a structure, the connecting branch pieces 26t, 27t, 32t project from the opening 22, respectively, and are bent twice to attach their respective ends to the groove surface f formed on the lower surface of the case 1. . By the way, when the connecting branch pieces 26t, 27t, 32t are projected from only one side of the case 1 and soldered onto the printed circuit board p in this way, the ladder type filter F is stably supported as one side. Can't hold.

Therefore, as shown in FIGS. 8 and 11, a dummy metal plate 34 having a connecting branch piece 34t is fixed in advance to the surface of the case 21 facing the opening 22 by molding. Therefore, the connecting branch piece 34t is similarly bent twice, and its end is attached to a groove surface f formed in advance on the back surface of the opening 22 as shown in FIG. By fixing by soldering at a position where there is no path, the ladder type filter F can be supported on both sides and can be stably held.

[0027]

According to the present invention, in a single case 1, 21,
Storage cavities 4L, 4R, 24L, 24R are formed on the left and right, and two series resonators S ₁ , S ₂ , S ₃ , S _{4 are provided for each.}
And two parallel resonators P ₁ , P ₂ , P ₃ , and P ₄ are connected to each other, the unit filtering circuits C ₁ and C ₂ are built in. Since a filter circuit corresponding to the filter F is built in, the number of mountings on the printed circuit board p can be halved, the installation area can be reduced, and the weight and size of the wireless communication device can be reduced. There is an excellent effect that it can contribute.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a ladder type filter F according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the ladder type filter F of the present invention shown in FIG. 3A-A.

FIG. 3 is a cross-sectional view of the ladder type filter F of the present invention taken along the line 2B-B of FIG.

FIG. 4 is a perspective view of a case 1 of the ladder type filter F of the present invention.

5A shows a connecting terminal board 8, 2B shows an input terminal board 7, and 3C shows an output terminal board 12. FIG.

FIG. 6 is a bottom view of case 1.

FIG. 7 is a conceptual diagram of a ladder type filter F according to a second embodiment of the present invention.

FIG. 8 is a sectional view taken along the line 9C-C of the ladder type filter F of the second embodiment.

FIG. 9 is a front view of a cross section of FIG. 8D-D of the ladder type filter F of the second embodiment.

FIG. 10 is a perspective view of a case 21 of the ladder type filter F of the present invention.

[Fig. 11] b is a connecting terminal plate 28 and b is a ground terminal plate 2
6 is shown.

FIG. 12 is a bottom view of the case 21.

FIG. 13 is a circuit diagram of a ladder filter F of the present invention.

[Explanation of sign]

F Ladder filter C ₁ , C ₂ Unit filter circuit S ₁ , S ₂ , S ₃ , S ₄ Series resonator P ₁ , P ₂ , P ₃ , P ₄ Parallel resonator 1, 21 Case ₃ , 23 Partition wall 4L , 4R, 24L, 24R storage space 5,25a, 25b communication groove 6,26 ground terminal plate 7,27 input terminal plate 8,28 communication terminal plate 12,32 output terminal plate 6t, 7t, 12t, 26t, 27t, 37t Connection branch piece 34 Dummy metal 34t plate Connection branch piece

Claims (5)

[Claims] 1. A rectangular case is formed with a storage space, which is partitioned by a partition wall and is open on one side, on the left and right sides, and two series resonators and two parallel resonances are provided in each storage space. A unit filtering circuit that is connected to a child is housed, and both unit filtering circuits are connected by a connecting terminal plate that is arranged across both housing voids.
Between the parallel resonators of one unit filtering circuit and between the other parallel resonators are connected to a ground terminal plate disposed across the storage space, and the electrodes of the series resonators in the preceding stage of one unit filtering circuit are connected. The input terminal board is connected to, and the output terminal board is connected to the electrode of the series resonator in the latter stage of the other unit filtering circuit, and the ground terminal board and the connecting branch pieces of the input terminal board and the output terminal board are A ladder-type electric filter characterized in that it is configured so as to protrude outside the case. 2. A communication groove for inserting a communication terminal plate or a ground terminal plate is formed in the partition wall, and the communication terminal plate or the ground terminal plate is accommodated in both storage spaces through the communication groove. The ladder type electric filter according to claim 1. 3. The communication terminal plate or the ground terminal plate is integrally assembled to the rectangular case by molding, and the communication terminal plate or the ground terminal plate is provided so as to communicate with both storage voids. 1. The ladder type electric filter described in 1. 4. A dummy having a connecting branch piece projecting from each of the connecting terminal pieces of the ground terminal plate, the input terminal board and the output terminal board from an opening formed in one side surface of the rectangular case, and having a connecting branch piece in the other side surface facing the one side surface. The metal plate is fixed, each connecting branch piece is bent in a direction flush with the lower bottom surface of the rectangular case, and the bent end is fixed to the printed circuit board. Ladder type electric filter. 5. A series resonator S in one of the storage voids.
₁ , parallel resonator P ₁ , parallel resonator P ₂ and series resonator S
₂ are sequentially laminated and electrically connected to each other on the laminated surface, and the series resonator S ₁ and the parallel resonator P ₁ are connected to the outer surface electrode of the series resonator S ₂ by a connection terminal plate, and the series resonance is performed. An input terminal plate is connected to the outer electrode of the child S ₁ , a ground terminal plate is connected between the parallel resonator P ₁ and the parallel resonator P _2, and a connecting terminal is further connected between the parallel resonator P ₂ and the series resonator S _2. While connecting the plates, in the other accommodation space, the series resonator S ₃ and the parallel resonator P are arranged.
₃ , the parallel resonator P ₄ and the series resonator S ₄ are sequentially stacked and electrically connected to each other on the stacked surfaces, and the series resonator S ₃ and the parallel resonator P ₃ are connected to each other and the outer surface of the series resonator S ₄ . The electrodes are connected by a connection terminal plate, a ground terminal plate is connected between the parallel resonator P ₃ and the parallel resonator P ₄ , a connecting terminal plate is connected to the outer electrode of the series resonator S ₃ , and the parallel resonator is further connected. The ladder type electric filter according to claim 1, further comprising an output terminal plate connected between P ₄ and the series resonator S ₄ .