JPS631772B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In order to connect the drive electrode of a rectangular piezoelectric ceramic plate having a drive electrode on one side and a floating electrode on the other side to an external lead terminal, the present invention has a ground terminal in the center and a ground terminal on both edges. A conductive pattern layer is provided on one surface between the terminal surface of a plurality of three-terminal ceramic filters each having an input terminal and an output terminal arranged so that the terminal surfaces face the same direction and three external lead terminals. This is a terminal connection method for edge mode ceramic filters in which conductive rubber plates, which are conductive only in the thickness direction, are sandwiched and held in pressure contact.

For intermediate frequency amplification circuits in radios and other wireless devices, rectangular piezoelectric ceramic plates are used to concentrate vibration energy near the ends of the length, and utilize edge mode vibration where the resonant frequency is determined by the width of the plate. An edge mode ceramic filter is used. As shown in FIG. 1, this filter unit includes a drive electrode 2 at one end of one surface of a piezoelectric ceramic plate 1 polarized in the thickness direction.
3 and 4 are provided, and by extending this, an input terminal 2', a ground terminal 3', and an output terminal 4' for external connection are drawn out at the other end, and a drive electrode 2 is provided on the other side. , 3, 4 are provided with floating electrodes 5, 5' substantially opposite to them to form a three-terminal type filter. Since the edge mode ceramic filter is symmetrical, the input terminal 2' and output terminal 4' may be reversed. Further, even if the length of the piezoelectric ceramic plate is set to 2 to 3 times the width and is fixed with a length of approximately 1.5 times the width left from the end face where the drive electrode is located, there is almost no effect on the filter characteristics.

Conventionally, in order to connect a large number of edge mode ceramic filters in cascade, they are fixed to the base board 9 in the same direction as shown in the example shown in FIG. , and the ground terminal 3' are soldered with the lead wire 10, and then the lead terminal 2'' is soldered to one of the input terminals, the lead terminal 3'' is soldered to the ground terminal, and the lead terminal 4'' is soldered to the output terminal. Another method is Fig. 3 a.
Solder the external leads 2'', 3'', and 4'' to the input terminal 2', ground terminal 3', and output terminal 4' of the filter unit as shown in FIG. on the conductor pattern 11'
Make one, insert the lead terminal of the filter unit, and solder it. However, the former method requires a large number of lead wires 10 to be soldered, and the latter method requires many holes to be drilled in the printed circuit board. Since there are many points, there is a drawback of lack of reliability.

The present invention eliminates these drawbacks and connects the input, ground, and output of the filter unit to external terminals using a conductive rubber coated with conductive paint on one side of the conductive rubber that is conductive only in the thickness direction. Concerning terminal connection methods.

The terminal connection method of the edge mode ceramic filter according to the present invention is as shown in FIG. Conductive rubber 6 provided with conductor patterns of layers 7 and 8,
It is assembled as shown in the three-element, three-terminal embodiment shown in FIGS. 5 and 6. Since this filter unit has the ground terminal 3' in the center as shown in Figure 1, the three filter units are arranged with the terminal surfaces for external connections in the same direction and on the same surface, and the conductive rubber 6 shown in Figure 4 is arranged. With the conductor layers 7 and 8 facing up, the conductor layer 7 is overlaid with the input terminal 2' and output terminal 4' of each filter unit, and the conductor layer 8 is overlaid with the ground terminal of each filter unit. Furthermore, in the part that only has conductive rubber, overlap the input terminal 2' of the leftmost filter unit and the output terminal 4' of the rightmost filter unit, and connect the input lead terminal 2'' and the output lead terminal 4'' on top of each other. By stacking the earth lead terminals 3'' on the conductor layer 8 and holding the respective lead terminals in pressure contact, a cascade-connected filter can be obtained.

As described above, the present invention allows connection to the outside using conductive rubber and metal pieces with a simple structure, simplifies work without requiring difficult processes such as soldering, and simplifies the work. Since the terminals are held in pressure contact with the ceramic filter through the rubber, the electrodes do not come off due to friction, and a highly reliable multi-element filter with excellent vibration and shock resistance can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram of the electrode pattern of an edge mode ceramic filter unit, where a is a surface view and b is a surface view.
2 is a plan view showing an example of the conventional terminal connection method, FIG. 3 is a plan view of another example of the conventional terminal connection method, b is a diagram of the conductor pattern on the printed circuit board, and FIG. Fig. 4 is a perspective view of conductive rubber used in the terminal connection method of the present invention, Fig. 5 is a plan view of an embodiment of the terminal connection method of the present invention, and Fig. 6 is A in Fig. 5.
-A sectional view. In the figure, 1: piezoelectric ceramic plate, 2, 3,
4: Drive electrode, 5, 5': Floating electrode, 2': Input terminal, 3': Earth terminal, 4': Output terminal, 2'',
3″, 4″: Lead terminal, 6: Conductive rubber, 7,
8: Conductor layer Note that the symbols appended with a, b, and c correspond to the respective symbols of the filter of the three-terminal element.

Claims (1)

[Claims] 1 A plurality of three-terminal ceramic filters each having an input terminal for external connection, an output terminal, and a ground terminal near the end of one surface of a rectangular piezoelectric ceramic plate are arranged on the same surface, and each terminal surface for external connection is arranged on the same surface. The multi-element element is characterized in that a ceramic filter and an external lead terminal are held in pressure contact by sandwiching a conductive rubber plate having a conductive pattern layer on a portion of at least one surface and having conductivity only in the thickness direction. Terminal connection method for edge mode ceramic filters.