JP3188802B2 - Ladder type electric filter - Google Patents

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 radio 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 constituting a unit filtering circuit are housed in a case.

[0002]

2. Description of the Related Art A ladder-type electric filter has one side electrode of a series resonator connected to an input side, one side electrode of a parallel resonator connected to a ground side, and the other side electrode of a series resonator and a parallel resonator. And the other side electrode is connected to the output side. A ladder-type electric filter of this type uses a series resonator and a parallel resonator using a contour vibration mode as a square having a side of about 5 mm so as to operate at a center frequency of 455 KHz, or has a diameter of about 5 mm. There is known a 5 mm circle using a series resonator and a parallel resonator using a vibration mode in the radial direction.

[0003]

In recent years, the weight and size of wireless communication devices have been reduced, and accordingly, the ladder type filter used in a filter circuit has been reduced in thickness by a unit of 0.01 mm. Are competing. By the way, the conventional configuration of the ladder-type electric filter has a configuration in which the parallel resonator and the series resonator are stacked in one direction, and the thickness of the ladder-type electric filter is
The thickness of each resonator is regulated by the sum of the thicknesses of the resonators, and the total height including the case and the terminal plate has to be increased, so that the reduction in thickness cannot be expected at all.

An object of the present invention is to provide a ladder-type electric filter capable of further reducing the thickness.

[0005]

According to the present invention, an opening 2 is provided on one side.
Are formed, and the ground terminal plate 10 is integrated,
The connecting foot 10a is projected outward from the surface facing the opening 2.
And the entire width inside the interior communicating with the opening 2
The storage room 4d is divided into left and right by a partition wall 4c.
And three storage chambers 4a and 4b communicating with each other at the top and bottom, respectively.
A case 1 having a storage cavity 3 having a structure is provided.
In addition, two square parallel resonators P ₁ and P ₂ using the contour vibration mode are vertically stacked in the storage chamber 4d,
Left and right of the housing chamber 4a, the strip of the series resonator S _1, S ₂ that uses the respective longitudinal vibration mode is arranged to 4b, and the parallel resonator P ₂ and series resonators S ₁ of the _upper, S ₂ An insulating plate 12 is interposed therebetween, and the lower surface electrodes of the resonators S ₁ and S ₂ are connected to the lower surface electrodes of the lowermost parallel resonator P _{1 by} a terminal plate.
13 through the connecting, the upper electrode of the resonator S ₁ is connected to an input terminal plate, parallel to the upper surface electrode of the resonator S ₂ resonator P
_{2 and} the upper surface electrode ₂ via an output terminal plate 8 and are connected in parallel.
Each electrode on the laminated surface of the resonators P ₁ and P ₂ is connected to a ground terminal.
Connected to the board 10, the input terminal board 7, the output terminal board 8
The connecting foot rods 7a, 8a respectively formed in the case through the opening 2
1 is a ladder-type electric filter that protrudes outside and connects the connecting foot bars 7a, 8a, and 10a to an external electric circuit.

[0006]

In the above-described configuration, the resonators S ₁ and S ₂ are arranged in parallel, and the thickness of the resonator is one sheet, and the total thickness is reduced. And the arrangement of the resonators S ₁ , S ₂ , P ₁ , and P ₂ .
The clerk has a storage chamber 4d covering the entire width and a partition wall 4 in the case.
is divided into left and right, and communicates with the storage room 4d at the top and bottom, respectively.
Storage space having a three-chamber structure including storage chambers 4a and 4b
3 ensured.

[0007]

DETAILED 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 thin rectangular case made of a synthetic resin material having an opening 2 formed on one surface thereof. A square parallel resonator P ₁ , P ₂ is provided in a storage space 3 of the case 1.
The strip-shaped series resonators S ₁ and S ₂ are arranged in a stacked manner as described later. Here series resonators S _1, S _2, in order to reduce the electrostatic capacitance with respect to the parallel resonator P _1, P _2, and the series resonators S _1, S ₂ and the wall thickness, the parallel resonator P
₁ and P ₂ are made thinner, and the parallel resonators P ₁ and P ₂ are formed in a square shape using a contour vibration mode as described later.
The electrode area is increased.

That is, in such a configuration, the series resonators S ₁ and S ₂ are formed in a strip shape, and the main resonance frequency of the longitudinal vibration mode in the longitudinal direction is matched with the center frequency of the ladder type filter. The parallel resonators P ₁ and P ₂ match the anti-resonance frequency of the contour vibration mode with the center frequency of the filter as before, and thus the series resonators S ₁ and S ₂ and the parallel resonator P ₁ , P ₂ constitute the required unit filtering circuit shown in FIG.

In the above configuration, the series resonators S ₁ and S ₂
Has a shape of, for example, 1.5 mm in width, 3.8 mm in length, and 0.50 mm in thickness, and the parallel resonators P ₁ and P ₂ have a shape of 4.65 mm in length and width and a thickness of 4.65 mm.
0.32mm shape.

The storage space 3 is provided with a storage room 4 over the entire width.
d and a partition wall 4c communicating with the upper part of the partition wall d.
It has a three-chamber structure having storage chambers 4a and 4b . The basic arrangement of each member in the storage space 3 will be described with reference to FIG. 1. In the storage chamber 4d, a square shape using the contour vibration mode is used. The two parallel resonators P ₁ and P ₂ are vertically stacked via the ground terminal plate 10 and the connection terminal plate 11, and the respective electrodes on the stacked surface are connected to the ground terminal plate 10. . The ground terminal plate 10 is connected to the connecting foot 1 from the edge.
0a, the ground terminal plate 10 and the parallel resonator P
_A square connection terminal plate 11 is provided between the two. The connecting foot rod 10a penetrates through the inside of the case 1 and protrudes outward by molding.

The upper parallel resonator P_Two aboveThere
Through the edge plate 12 and the terminal strip 13a of the connection terminal plate 13,
Strip-shaped series resonator S using longitudinal vibration mode
₁ , S _Two Are arranged in parallel on the left and right. This positioning
Are the storage chambers 4a, 4 divided into right and left by the above-mentioned partition 4c.
b represents a series resonator S ₁ , S _Two By storing each
Can be done.The connection terminal plate 13 is composed of two parallel terminal pieces.
13a and 13b are connected by a connection portion 13c.
The child piece 13b is connected to the parallel resonator P₁ On the lower surface of the
And the series resonator S via the connection terminal plate 13.₁ , S_Two 
The lower electrode of the parallel resonator P₁ To be connected to the lower electrode of
I have to.

Further, an input terminal plate 7 is provided on the upper surface electrode of the series resonator S ₁ , and a connecting foot 7 a extending from an edge of the input terminal plate 7 is connected to the opening 2 of the case 1 through the opening 2. It protrudes outward. That is, it can be connected to the upper electrode of the series resonator S ₁ to the input-side external path.

Next, an upper surface electrode of the series resonator S ₂ ,
Parallel resonator and the upper electrode of the P _2, are electrically connected by an output terminal board 8, connected to form the output terminal board 8 legs rods 8
a is projected outward from the opening 2 of the case 1 so that the upper surface electrodes of the series resonator S ₂ and the parallel resonator P ₂ can be connected to the output-side external electric circuit.

The output terminal plate 8 is, as shown in FIG.
Strip terminal strip 8 to close the upper surface electrode of the series resonator S ₂
and b, are connected by connecting portions 8d to insert passed the square-shaped terminal piece 8c closely on the upper surface electrode of the parallel resonator P ₂ both terminal pieces 8b, between the side edges of 8c, further square-shaped terminal piece 8c The connecting foot 8a is configured to protrude from the corner of the front edge of the front end. On the lower surfaces of the terminal pieces 8b and 8c, pressure contact ridges x and y serving as nodes of vibration are formed to secure electrical connection with the upper surface electrodes of the series resonator S ₂ and the parallel resonator P _2. I have.

In addition, buffer plates 15a and 15b are interposed between the input terminal plate 7 and the output terminal plate 8 and the ceiling surface of the case 1.

In the above construction, the case 1 is formed integrally with the ground terminal plate 10 by molding, and thereafter, the above-mentioned members are inserted into predetermined positions from the opening 2, and
After the connecting feet 7a, 8a protrude from the opening 2, the bottom plate 4 is fitted into the opening 2, and a sealing resin 5 such as epoxy resin.
To complete the ladder-type electric filter F. Further, the connecting feet 7a, 8a and the connecting feet 10a of the ground terminal plate 10 are each bent twice along the case 1, and the ends thereof are positioned on the bottom surface of the case 1. As a result, surface mounting on a printed circuit board becomes possible.

In the ladder type electric filter F, the input terminal plate 7, the output terminal plate 8 and the ground terminal plate 10 are exposed at the lower part, and therefore, the conductive paths formed on the required printed circuit board are formed. By electrically connecting the exposed ends of the terminal boards to each other by soldering or the like, a desired filtering circuit can be constructed by connecting an appropriate number of the unit filtering circuits shown in FIG.

In the ladder-type electric filter F having the above-described configuration, the resonators S ₁ and S ₂ are arranged in parallel, and the thickness is reduced to one sheet, and the total thickness is reduced.

[0020]

According to the present invention, as described above, the three-chamber structure is used.
And housed in comprising housing gap 3, it is so arranged to dispose the series resonators S _1, S ₂ in parallel form on the laminate of the parallel resonator P _1, P _2, the series resonators S _1, S ₂ increases the thickness by one sheet. Therefore, the total thickness of the ladder-type electric filter F is reduced, and the ladder-type electric filter F can be made as thin as possible. It can contribute to miniaturization . Also,
The arrangement relationship of each resonator S ₁ , S ₂ , P ₁ , P ₂ is the case
Inside, a storage room 4d covering the entire width and a partition wall 4c separate left and right.
The storage rooms 4a, 4b,
4b and secured by a storage space 3 consisting of a three-chamber structure
Has excellent effects such as:

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a ladder-type electric filter F of the present invention.

FIG. 2 is a view 3A-A of the ladder type electric filter F of the present invention.

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a sectional view taken along the line CC of FIG. 3;

FIG. 5 is a perspective view of an output terminal plate 8;

FIG. 6 is a unit filter circuit diagram constituted by a ladder-type electric filter F of the present invention.

[Explanation of symbols]

F ladder-type electric filter 1 case 3 accommodating void 4a, 4b, 4c containing chamber 4d septum S _1, S ₂ series resonators P _1, P ₂ parallel resonators 7 input terminal board 8 output terminal plates 8a connected foot lever 8b strip Terminal piece 8c square terminal piece 10 ground terminal plate

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 4-121125 (JP, U) JP-A 56-57524 (JP, U) JP-A 56-152416 (JP, U) JP-Sho 62- 44592 (JP, Y2)

Claims (1)

(57) [Claims] An opening (2) is formed on one surface, and a ground terminal is provided.
The plate 10 is integrated, and the connecting foot 10a is paired with the opening 2.
Projecting outward from the facing surface and communicating with the opening 2
Inside, a storage room 4d spanning the entire width and a partition 4c left
Storage room divided to the right and communicating with storage room 4d at the top and bottom respectively
The storage space 3 having a three-chamber structure provided with 4a and 4b has a shape.
The case 1 is formed, and two parallel square resonators P ₁ and P ₂ each using a contour vibration mode are vertically stacked in a storage room 4d, and are respectively stacked in the left and right storage rooms 4a and 4b. arranged a strip of the series resonator _S 1, _{S 2} that use a longitudinal vibration mode, and the parallel resonator _{P 2} and series resonators _S 1 of the upper, _{S 2}
An insulating plate 12 is interposed therebetween, and the lower electrodes of the resonators S ₁ and S ₂ are connected to the lower electrodes of the lowermost parallel resonator P ₁ via a terminal plate 13 ,
The upper electrode of the resonator S ₁ is connected to an input terminal plate, connects the upper electrode of the resonator S ₂ and the upper surface electrode of the parallel resonator P ₂ via the output terminal board 8, the parallel resonator P _1, P Product of _two
When each electrode on the layer surface is connected to the ground terminal plate 10,
And connection legs formed on the input terminal plate 7 and the output terminal plate 8 , respectively.
The rods 7a and 8a are projected from the opening 2 to the outside of the case 1 for connection.
A ladder-type electric filter configured to connect the foot rods 7a, 8a, and 10a to an external electric circuit.