JPS6244591Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a ladder-shaped filter that has stable performance against mechanical impact force and vibration.

Conventionally, a ladder filter in which a series resonator and a parallel resonator are connected in a ladder shape has a configuration as shown in FIG. The resonators 1a and 1b are sandwiched between electrode plates 2, and a cushion 3 and an insulating plate 4 are appropriately arranged and housed in a case 5. Here, the cushion 3 provides elastic support pressure to the series resonator 1a and the parallel resonator 1b, and has the effect of absorbing external shock, and is made of silicon rubber, a plate spring, a coil spring, etc. . In addition, the effect can be obtained from the springiness of the electrode plate 2 itself without using the cushion 3 at all.
Alternatively, the elasticity of the insulating plate 4 and the case 5 may be used instead.

In addition, the insulating plate 4 is required to configure a ladder circuit as shown in FIG. 2, and as shown in FIG.
In the case where the resonators b are arranged alternately, it is necessary to arrange the insulating plate 4 for each basic L-shaped circuit section composed of the series resonators 1a and the parallel resonators 1b.

The electrode plate 2 is usually made of a thin plate made of a spring contact material such as silver-plated bronze or nickel silver, and is composed of a terminal 6 and a support part 7 as shown in FIG. Series resonator 1a, parallel resonator 1b
A protrusion 8 that contacts is formed by drawing. Note that FIG. 3a is a front view, and FIG. 3b is a side view.

In the ladder filter having such a configuration, the signal transmission side is connected to the terminal portions 6 of the electrode plate 2 or by soldering the terminal portions 6 and the input/output terminals 9.
Further, on the ground side, wiring is performed by soldering the lead wire 10 and the terminal portion 6 of the electrode plate 2 or the lead wire 10 and the ground terminal 11, thereby constructing a ladder-shaped circuit as shown in FIG.

Figure 4 shows an example of the frequency characteristics of a ladder filter with such a configuration, and the frequency characteristics of this filter are determined by the frequency characteristics of the series and parallel resonators 1a and 1b and their combination. A change in the frequency characteristics of the resonator due to a change in the resonator support state due to an external impact or the like directly appears as a change in the frequency characteristics of the ladder filter.

By the way, in the case of a conventional ladder filter,
Since the interior has a flexible structure and the whole is in one room, force and tilt of the parts are easily transmitted to all the parts housed in the case 5, and the resonators 1a and 1b are affected by external shocks. Problems have arisen in that non-uniform support pressure and tilting of the resonators 1a, 1b and the electrode plate 2 tend to occur, resulting in large fluctuations in frequency characteristics. In addition, if such a problem is severe, the electrode plate 2 and the resonators 1a, 1
In addition, as the number of resonators 1a and 1b increases, the contact with It was hot.

Therefore, in order to improve this problem, the fifth
A ladder-shaped filter with the structure shown in the figure was developed. In the ladder type filter shown in FIG.
In place of the insulating plate 4 used in the ladder-type filter shown in the figure, a partition wall 12 integrally formed with the case 5 is interposed therebetween, and the inside of the case 5 is divided into several chambers.

However, even in the case of a ladder-shaped filter as shown in FIG. Although it was somewhat effective compared to other products, it could not be said to be sufficient.

The present invention has been developed in view of such conventional problems, and will be described below with reference to the drawings of FIGS. 6 to 9 showing embodiments of the present invention. Note that the same parts as those of the conventional ladder-shaped filter shown in FIGS. 1 and 5 will be described with the same numbers.

FIG. 6 shows a ladder-shaped filter according to an embodiment of the present invention, and FIG. 7 shows its main parts.
As shown in FIGS. 6 and 7, the series resonator 1
The arrangement of the parallel resonator 1b, the cushion 3, and the insulating plate 4, as well as the wiring conditions, are the same as those of the conventional ladder filter shown in FIG.

That is, the ladder-shaped filter according to the present invention has a partition wall 13 between the electrode plates 2, which were originally arranged back to back and did not need to be insulated.
Electrical continuity is achieved by soldering the terminal portions 6 of the electrode plate 2 to each other, and they are fixed by sandwiching the partition wall 13 between them.

Further, the partition wall 13 may be formed integrally with the case 5 as shown in FIG. 7, or may be inserted into the case 5 by providing a notch 14 therein as shown in FIG.

Note that a sufficient effect can be obtained by arranging the middle partition wall 13 at only one location, and the middle partition wall 13 may be provided in place of the insulating plate 4.

As is clear from the above configuration, in the present invention, a middle partition wall 13 is arranged between the electrode plates 2 at the point where a short circuit is to be made to constitute a ladder-shaped filter. Since each chamber is independent against force and tilt, it is extremely stable against external impact force and vibration, and the initial arrangement is also good, creating a ladder-shaped filter with extremely stable characteristics. can do.

Figure 9 shows the insertion loss variation when an external shock is applied to a ladder filter consisting of 11 series and parallel resonators, and curve a is the first one.
The conventional product shown in the figure, curve b is the conventional product shown in FIG.
Curve c is a characteristic of each product of the present invention.

It is clear from FIG. 9 that the ladder-shaped filter according to the present invention exhibits extremely little fluctuation compared to conventional filters.

As described above, the ladder-shaped filter according to the present invention is
It has extremely stable characteristics against external impacts, and the increase in shape due to the provision of a partition wall reduces the height of the protrusion on the electrode plate,
Since it can be sufficiently absorbed by removing the cushion, etc., it has a high practical value without sacrificing the advantage of being small.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the internal structure of a conventional ladder filter, Fig. 2 is an electric circuit diagram of the filter, and Figs. 3 a and b are front and side views showing the electrode plates used in the filter, respectively. , FIG. 4 is a diagram showing an example of the frequency characteristics of the same filter, and FIG. 5 is a cross-sectional view showing the internal structure of a conventional ladder-type filter.
FIG. 6 is a sectional view showing the internal structure of a ladder filter according to an embodiment of the present invention, FIG. 7 is a perspective view showing a case used in the filter, and FIG. FIG. 9, a perspective view showing an example, is a diagram showing a comparison of insertion loss fluctuations due to external impact between a conventional product and a product of the present invention. 1a...Series resonator, 1b...Parallel resonator, 2
...Electrode plate, 3...Cushion, 4...Insulating plate,
5...Case, 13...Inner partition wall.

Claims (1)

[Scope of utility model registration request] A plurality of series resonators and parallel resonators, a plurality of electrode plates having protrusions that clamp each resonator, and cushions and insulating plates disposed at appropriate locations are arranged in series in a case. In the ladder-shaped filter stored in the case, a partition wall fixed to the case is interposed at at least one place between two adjacent electrode plates to be short-circuited among the electrode plates,
A ladder-shaped filter is formed by connecting and fixing the two electrode plates together.