JPS6210912A - Ladder type filter - Google Patents

Abstract

PURPOSE:To decrease the number of earth lead terminals drawn out of a case by providing >=1 U-shaped terminal connecting electrically the earth electrodes of two parallel resonators while two terminal boards and a joint connecting them are provided. CONSTITUTION:The earth electrodes of parallel resonators 6b, 6c are connected electrically by the U-shaped terminal 12c comprising two terminal boards 8m, 8n and the joint 10c connecting them and the number of earth lead terminals led out of the case 2 is decreased by one. Since the number of the earth lead terminals led out of the case is decreased in this way, the handling and workability in mounting are improved and a face bond shape with low cost even for multi elements is attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multi-element ladder filter, and in particular,
This invention relates to means for reducing the number of grounding lead terminals that are drawn out of the case.

[Conventional technology]

FIG. 5 is a schematic diagram showing an example of a conventional ladder-type filter, FIG. 6 is an equivalent circuit diagram of the ladder-type filter shown in FIG. It is an exploded perspective view showing the contents.

This ladder type filter is a 6-element type, and three series resonators 4a to 4C and three parallel resonators 6a to 6C are connected to terminal plates 8a to 8I! They are sandwiched between each other and housed in a rectangular case 2. The entire body is elastically pressed together by a spring plate 16 provided at the end. In addition, the code 14a
, 14b are insulating spacers.

In this case, for example, the series resonator 4a has electrodes 42a and 43a formed on both sides of a piezoelectric substrate 41a, and the other series resonators 4b to 4C and parallel resonators 6a to 6C have a similar structure. are doing.

For example, the terminal plate 8a has a protrusion 9a for supporting the series resonator 4a at its vibration node, and the other terminal plates 8b to 8β also have similar protrusions.

The terminal plates 8b and 88 and the terminal plates 8f and 81 are connected to the joint part 1
0a and 10b are respectively connected to U-shaped terminals 12a.
and 12b, and the U-shaped terminals 12a, 1
The series resonators 4a to 4C are electrically connected in series by 2b. In addition, terminal plates 8a, 8d, 8h, 8j2.
8j is connected to input (or output) lead terminals 21, grounding lead terminals 22 to 24, and output (or input) lead terminals 25, which are formed integrally with them. The lead terminals 21 to 25 are drawn out of the case 2. Although not shown, the opening of the case 2 is sealed with a sealant. Note that the connection between the lead terminals 22 to 24 is performed, for example, on the mounting board side.

[Problem that the invention seeks to solve]

In the ladder type filter as described above, five lead terminals 21 to 25 are drawn out to the outside of the case 2, so these lead terminals are bent into a face bond shape as shown in FIG. 8, for example. Even if they tried, it would be impossible because there are lead terminals that collide with each other. Furthermore, even if this is not done, the large number of lead terminals makes handling difficult and poor workability when mounting on a board or the like. Moreover, such problems increase as the number of elements increases.

In this case, the above problem can be solved if the number of grounding lead terminals drawn out of the case can be reduced, apart from input/output lead terminals. Therefore, the main object of the present invention is to reduce the number of grounding lead terminals drawn out of the case.

[Means for solving problems]

The ladder filter of the present invention has two terminal plates and a joint that connects them, and includes one or more U-shaped terminals that electrically connect between the ground side electrodes of two parallel resonators. It is characterized by

(Function) The U-shaped terminal electrically connects the ground-side electrodes of the parallel resonators either directly or through another object.This reduces the number of ground lead terminals that can be drawn out of the case. Ru.

〔Example〕

FIG. 1 is a schematic view showing a ladder type filter according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view showing the contents of the ladder type filter of FIG. 1.

Components equivalent to those in FIGS. 5 to 7 are designated by the same reference numerals, and their explanations will be omitted.

In this ladder type filter, the above-mentioned terminal plate 8h
Parallel resonators 6b, 6c are connected to the parallel resonators 6b, 6c by a U-shaped terminal 12c consisting of two terminal plates 8m, 8n and a joint 10c connecting them, without using the lead terminals 23 connected thereto.
The electrodes on the ground side of the case 2 are electrically connected to each other, thereby eliminating the need for one grounding lead terminal to be drawn out of the case 2. Also, the lead terminal 2 from the terminal plate 8a
1 is drawn out in the opposite direction from the conventional method in order to avoid contact with the lead terminal 22 when it is bent. Incidentally, the terminal plates 8m and 8n are provided with protrusions such as the above-mentioned protrusion 9a as necessary. In that case, the terminal board 8
The protrusion 1 is no longer necessary.

Further, the electrical connection between the terminal plates 8m, 8n and the electrodes of the parallel resonators 6b, 6c may be made not directly but through another object.

By adopting the above structure, the number of grounding lead terminals drawn out from the case 2 is eliminated, making it easier to handle when mounting on a board, etc., and improving workability. Furthermore, since the lead terminals 21, 22, 24, and 25 are pulled out of the case 2 in the arrangement shown in Figure 3, even if they are bent as shown by the chain lines, they will not collide with each other. It is possible to Moreover, since it is sufficient to use only the U-shaped terminal 12C without changing much of the other structure, a low-cost face-bond type is possible.

Incidentally, when actually assembling the ladder filter as described above, for example, a method is adopted in which each component is sequentially inserted from the opening of the case 2. In that case, either one of the U-shaped terminals 12b or 12C is connected to the other joint 1.
0b or IOC gets in the way and cannot be inserted. Therefore, in such a case, one of the joints, for example the joint 10b as shown in the figure, may be brought sideways with the other joint 10C shifted by 90 degrees as shown in the figure, or it may be brought sideways by 180 degrees. All you have to do is shift it a degree and bring it to the bottom. Alternatively, if the width W of one terminal plate 8m of one U-shaped terminal, for example, the U-shaped terminal 12C, is narrowed to such an extent that it does not hit the joint 10b of the other U-shaped terminal 12b, as shown in FIG. , joint part 10b of both U-shaped terminals 12'b, 12c,
Even if the IOC is provided on the same side, both U-shaped terminals 10b,
Insertion from above 10C becomes possible. As described above, whichever method is adopted, it is possible to reduce the number of lead terminals without impairing assembly work efficiency.

Incidentally, the same means as above is adopted on the lead terminal 22 side, and the series resonators 6a and 6b are connected by another U-shaped terminal.
It is also possible to electrically connect between the earth side electrodes of
Thereby, the number of grounding lead terminals drawn out of the case 2 can be reduced to one, for example, only the lead terminal 24. If this is done, handling and workability during implementation will be further improved. Of course, it is also possible to use a face bond type.

Further, the above-mentioned means is not limited to the case of six elements, and can be applied to cases where the number of elements is less than or greater than that.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to reduce the number of grounding lead terminals drawn out of the case, thereby improving handling and workability during mounting. In addition, even with a large number of elements, a low-cost face-bond type can be realized.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a ladder filter according to an embodiment of the present invention. 2 is an exploded perspective view showing the contents of the ladder-type filter of FIG. 1. FIG. FIG. 3 is a plan view showing a lead terminal extension portion of the ladder-type filter shown in FIG. 1. FIG. FIG. 4 is a perspective view showing another example of the U-shaped terminal. FIG. 5 is a schematic diagram showing an example of a conventional ladder type filter. FIG. 6 is an equivalent circuit diagram of the ladder filter shown in FIG. 7 is an exploded perspective view showing the contents of the ladder-type filter of FIG. 5. FIG. FIG. 8 is a perspective view showing an example of a face bond type ladder filter.

Claims (1)

[Claims] (1) In a ladder-type filter in which multiple series resonators and parallel resonators are sandwiched between terminal plates and housed in a case, and lead terminals for input, output, and ground are respectively drawn out of the case. , a ladder filter characterized in that it has two terminal plates and a joint that connects them, and includes one or more U-shaped terminals that electrically connect between the ground side electrodes of two parallel resonators. .