JP2567103Y2 - Ladder type filter - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ladder filter, and more particularly to a ladder filter suitable for surface mounting.

[0002]

2. Description of the Related Art As a ladder type filter suitable for surface mounting, a laminated body in which a piezoelectric resonator and a terminal plate are stacked;
2. Description of the Related Art There is known a case including a case having an opening and accommodating a laminate, a sealing portion for sealing the opening, and a lead terminal formed integrally with the terminal plate and protruding from the sealing portion. In this ladder type filter, the lead terminals are formed outside the sealing portion into a shape suitable for surface mounting, and are surface mounted on the printed wiring.

[0003]

In the conventional ladder-type filter, in order to sufficiently exhibit the electrical characteristics of the piezoelectric resonator, the terminal plate constituting the laminate is made of a resilient, thin metal material (for example, Phosphor bronze). For this reason, it is difficult to form a lead terminal integrally formed with the terminal plate with high precision for surface mounting. For example, if the forming accuracy of the input, output, and ground lead terminals does not match, when the filter is mounted on the printed wiring board, the lead terminals that are in close contact with the printed wiring board and the lead terminals that are raised from the printed wiring board May occur and lead terminals may have poor soldering.

It is an object of the present invention to provide a ladder-type filter which is less likely to cause a mounting failure during surface mounting.

[0005]

A ladder-type filter according to the present invention has a laminate in which a plurality of piezoelectric resonators and a plurality of terminal plates are alternately stacked, an opening having an opening, and a case for accommodating the body, the base member and a seal for sealing the opening
And a sealing portion consisting of wood, and electrically connected to the terminal plate,
And a plurality of lead terminals led out to the outside. In this ladder type filter, the plurality of terminal plates
Of the predetermined terminal plates, a lead portion penetrating the base member is provided.
Has one of the tip portions of the plurality of lead terminals are locked to a surface to be mounted bottom before <br/> SL case, the other tip portion
Is electrically connected to the lead of the terminal plate within the seal member.
Connected .

[0006]

In the ladder filter according to the present invention, the ends of the lead terminals are locked on the surface serving as the mounting bottom surface of the case. For this reason, the lead terminal extending from each terminal plate has a substantially uniform thickness at the bottom surface of the case with the lead terminal whose tip is extended from another terminal plate. Poor mounting is unlikely.

[0007]

Embodiment 1 FIGS. 1 to 3 show a ladder-type filter according to an embodiment of the present invention. In the figure, a ladder-type filter 1 mainly has a box-shaped case 2 and a filter member group 3 housed in the case 2.

The case 2 is a hollow, substantially rectangular parallelepiped member made of a resin having a relatively high melting temperature. An opening 4 is formed at one end of the case 2, and a slight step portion 4a is formed in the opening 4 as shown in FIGS.
As shown in FIGS. 1 and 2, the other end of the case 2 is provided with an L-shaped fixing bracket 33 at the center of the lower corner of the case. This serves as a dummy terminal for fixing the case 2 to the printed wiring board 31 (see FIG. 6).

The filter member group 3 housed in the case 2
2 includes a filter unit 5, a first series resonator 6, a first terminal plate 7, and a spring member 8 stacked in order from the bottom in FIG.

The filter unit 5 has a U-shaped terminal 9.
In the terminal 9, the second series resonator 10, the second terminal plate 11, the first parallel resonator 12, the third terminal plate 13, and the second parallel resonance And child 14. The U-shaped terminal 9 includes a pair of terminal plates 15 and 16 arranged in parallel, and a connecting portion 17 that connects the two terminal plates 15 and 16. Terminal board 15
Is a square plate member, and a projection 1 is provided at the center of the upper surface of FIG.
5a. The protrusion 15 a is formed by, for example, drawing, and is in contact with the second series resonator 10. The terminal plate 16 is formed by stacking two square plate-like members, and has protrusions 16a, 16a on the main surfaces on both sides, respectively.
b. The projections 16a and 16b are in contact with the first series resonator 6 and the second parallel resonator 14, respectively. The connecting portion 17 is a member for connecting the terminal plate 15 and the terminal plate 16, and extends parallel to the inner wall surface of the box-shaped case 2.

The second series resonator 10 and the first parallel resonator 12
The second parallel resonator 14 has electrodes (not shown) on both main surfaces.
Are plate members made of piezoelectric ceramics, and have a substantially square shape. The second series resonator 10 includes the parallel resonator 1
The thickness is set to be larger than 2 and 14.

The second terminal plate 11 and the third terminal plate 13 are each formed by stacking two square plate members.
Both main surfaces have projections 11a, 11b, 13a, 13b, respectively. Each projection 11a, 11b, 13a, 13b
Are in contact with the opposing resonators 10, 12, 12, and 14, respectively. The second terminal plate 11 and the third terminal plate 13
The case 2 has lead portions 18 and 19 extending in the direction of the opening 4 (see FIG. 3). Both lead portions 18, 19
Are provided so as to be shifted from each other so as not to overlap with each other, and extend from one end of the second terminal plate 11 and the central portion of the third terminal plate 13, respectively.

The first series resonator 6 includes a second series resonator 10
This is a piezoelectric ceramic plate-like member configured in the same manner as described above. The first terminal plate 7 is a square plate-shaped member, and has a projection 7a at the center of the lower surface in FIG. The projection 7a is in contact with the first series resonator 6. Also, the first terminal plate 7
Has a lead portion 20 extending in the direction of the opening 4. The lead portion 20 is provided at an end on the near side in FIG. 2 so as not to overlap with the lead portions 18 and 19. The spring member 8 is interposed between the upper surface of the case 2 and the first terminal plate 7, and is a member for pressing and fixing the filter member group 3 in the case 2.

In the filter member group 3, each of the terminal plates 7, 11, 13, 15, 16 is made of a springy flexible metal material such as phosphor bronze.
The thickness is set to about 0.1 mm.

The opening 4 of the case 2 in which the filter member 3 is accommodated is sealed by a paper base 21 and a sealing material 23. The paper base 21 includes the lead portions 18, 19, 20.
Has a slit at a position corresponding to, and is in contact with the step portion 4a. The lead portions 18, 19, and 20 project from corresponding slits in the paper base 21, respectively.

A first lead terminal 25, a second lead terminal 26, and a third lead terminal 27 are soldered to the tips of the leads 20, 19, and 18, respectively. As shown in FIG. 4, each of the lead terminals 25, 26, 27 has a slit 25a, 2 corresponding to a lead portion 20, 19, 18, respectively.
6a, 27a and mounting portions 28a, 29a, 30a
, Slits 25a, 26a, 27a and mounting portion 28
a, 29a, 30a, and drawer portions 28, 29, 3
0. Mounting parts 28a, 29a, 30a
Are formed in a substantially U-shape, and each of the fitting grooves 28
b, 29b and 30b. Each lead terminal 25,
The mounting portions 28a, 27a, and 30a are elastically fitted into the lower side of the opening 4 of the case 2 in FIG.
reference). The lead portions 20, 19, 18 pass through the corresponding slits 25a, 26a, 27a, and are soldered around the slits 25a, 26a, 27a.

The sealing material 23 is, for example, an epoxy resin, and is filled in the opening 4. Thus, the opening 4 is hermetically sealed.

FIG. 5 shows an equivalent circuit of the ladder-type filter 1.
Shown in In the drawings, corresponding parts are denoted by the same reference numerals. As is clear from FIG. 5, the mounting portion 28a of the first lead terminal 25 and the mounting portion 30a of the third lead terminal 27 are input / output terminals, and the mounting portion 29a of the second lead terminal 26 is a ground terminal.

The ladder-type filter 1 is used for surface mounting so that one main surface of the case 2, that is, the surface serving as the bottom surface, faces the printed wiring board 31. Here, as shown in FIG. 6, solders 32 and 34 are arranged at predetermined positions on the printed wiring board 31, and the solders 32 and 34 are arranged.
Mounting portions 28a, 29a, 30a
And the fixing bracket 33 is arranged. Here, since each of the mounting portions 28a, 29a, and 30a is along the outer surface of the case 2, all the mounting portions come into good contact with the solder 32. Therefore, the mounting portions 28a, 29a, 30a
In this case, poor mounting is unlikely to occur. The ladder-type filter 1 is fixed to the printed wiring board 31 by the fixing bracket 33.
It is placed horizontally on top.

[0020]

Second Embodiment In the first embodiment, the mounting portion of the lead terminal is fitted into the opening 4, but the present invention is not limited to this.
For example, as shown in FIG. 7 , a long groove-shaped through hole 22 may be formed on the lower surface of the case 2, and the lead terminal 36 may be inserted through the through hole 22. Here, an L-shaped lead terminal 36 having a mounting portion 35 is used as the lead terminal 36, and the lead terminal 36 is connected to a corresponding lead portion in the case 2, and is locked to the bottom surface of the case 2 by the mounting portion 35. And fix it.

[0022]

[Effects of the Invention] In the ladder type filter of the present invention, since the tips of the lead terminals are locked to the bottom surface of the case, mounting failure is unlikely to occur during surface mounting.

[Brief description of the drawings]

FIG. 1 is a perspective view of Embodiments 1 and 2 of the present invention.

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

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a perspective view of a member employed in the embodiment.

FIG. 5 is an equivalent circuit diagram of the embodiment.

FIG. 6 is a front view showing a surface mounting state of the embodiment.

FIG. 7 is a diagram corresponding to FIG. 2 of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ladder type filter 2 Case 3 Filter member group 4 Opening 6,10,12,14 Resonator 7,11,13,15,16 Terminal board 23 Sealing material 25,26,27,36 Lead terminal 28a, 29a, 30a, 35 Mounting part

 ──────────────────────────────────────────────────続 き Continued on the front page (56) References JP-A 2-106727 (JP, U) JP-A 2-55732 (JP, U) JP-A 2-38820 (JP, U) JP-A 59- 99529 (JP, U) Japanese Utility Model 2-26820 (JP, U) Japanese Utility Model 2-24212 (JP, Y2)

Claims (1)

(57) [Scope of request for utility model registration] A plurality of piezoelectric resonators and a plurality of terminal plates are alternately provided.
A laminate stacked on the case and housing the laminated body has an opening, and a sealing portion comprising a base member and a seal member for sealing said opening, electrically connected with the terminal plate And the externally derived complex
A ladder-type filter having a number of lead terminals, wherein a predetermined terminal plate of the plurality of terminal plates is the base member
And a lead portion that penetrates the plurality of lead terminals.
One end is locked to the mounting bottom surface of the case.
And the other end portion of the terminal plate in the seal member.
A ladder-type filter electrically connected to a load section .