JPH02309709A - Filter device - Google Patents

Abstract

PURPOSE:To approximate the ground potential of an SAW filter to the reference ground potential of a metallic frame and to attain to a target ripple attenuation characteristic by connecting the ground part of a surface acoustic wave(SAW) filter to the metallic frame directly and electrically through a metallic plate. CONSTITUTION:After creamy solder 18 is applied to the base part 14 of the metallic plate 13, input and output leads 6 are inserted into an escape hole 15 to incorporate the SAW filter 1 on the metallic plate 13 and they are soldered in an oven. Then the input and output leads 6 are inserted into lead holes 9 of a substrate 8 and the body is mounted on a substrate 8, packaged in the metallic frame 10, and soldered by dipping. While the metallic plate 13 and metallic frame 10 are connected by the DIP soldering, the substrate 8 are connected to the input and output leads 6 with solder 17. The ground potential of the SAW filter 1 can, therefore, be approximated to the reference earth potential of the metallic frame 10.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a filter device used in a demodulation section of an indoor receiver for satellite broadcasting.

Conventional technology First, a brief explanation of the sAW filter will be given.

As shown in FIG. 3, the SAW filter 1 includes comb-shaped input side metal electrodes 3 for input and output on the surface of a crystal plate 2 made of a piezoelectric material. The output side metal electrodes 4 are formed facing each other. The input signal is supplied to the input side metal electrode 3 and S
It is converted into an AW, propagates on the surface of the crystal plate 2, reaches the output side metal electrode 4, is converted into an electrical signal, and becomes an output signal. Such a SAW filter 1 is housed in a predetermined case 76 as shown in FIG. Since this SAW filter 1 can be made smaller in circuit size and requires no adjustment, it is expected to be applied and developed in various electronic devices such as TV receivers.

Note that 6 is a person, an output lead, and 7 is a ground lead.

The configuration of a filter device using the above-mentioned SAW filter 1 was as shown in FIGS. That is, the SAW filter 1 is mounted on the board 8 by inserting the lead wire, lead wire, and ground lead 7 into the lead hole 9 of the board 8, and then mounting it on the frame 1o and performing DIP soldering. The DIP soldering after assembly is completed is shown in Figure 6. The lead wire and output lead wire are connected to the front and rear circuits according to a pattern, and the ground lead 7 is routed in a pattern, and the soldering part 11 is grounded to the frame 1o.

Problems to be Solved by the Invention In the UHF band of the demodulator of indoor receivers for satellite broadcasting, etc.
When using the SAt filter 1 shown in FIG. 6, in the conventional structure, the ground lead 7 has a length as shown in FIG. The connection is through a pattern with e,
Therefore, the potential of the grounding node 7 is different from the reference grounding potential of the frame 1o, and as a result, there is a drawback that it is difficult to achieve the targets for the ripple and attenuation characteristics shown in FIG.

The present invention is intended to solve the above-mentioned problems, and aims to achieve the goals of ripple and damping characteristics.

Means for solving the problem and to achieve this object, the present invention provides the above-mentioned SAt
A metal plate, to which the grounding part of the filter is electrically connected, is electrically connected to a metal frame.

Function: With the above-described configuration, the present invention electrically connects the ground portion of the SAw filter directly to the metal frame via the metal plate, so that the ground potential of the SAt filter can be brought close to the reference ground potential of the metal frame.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

An embodiment of the present invention is shown in FIGS. 1 and 2. FIG. Note that the ground lead is omitted in the figure, and grounding is performed through the metal case 6. Further, in this embodiment, after applying the cream solder 18 to the vane portion 14 of the metal plate 13, the SAt filter 1 is
is assembled into the metal plate 13 and soldered open. And people.

The lead wire is inserted into the lead hole 9 of the board 8, attached to the board 8, mounted on the metal frame 1o, and DIP soldered. A cross-section of the Mu person in FIG. 2 is shown in FIG. The metal plate 13 and the metal frame 10 are connected by solder 16 by DIP soldering, and at the same time, the board 8 and the output card are connected by solder 17.

With the above structure, the case 76 of the SAt filter 1, which is the root of the ground lead 7, is directly connected to the metal frame 1o via the metal plate 13, so the ground potential of the SAW filter 1 is set to the reference ground potential of the metal frame 1o. This makes it possible to achieve the target ripple and damping characteristics.

In addition, in this embodiment, cream solder 18 that melts at a low temperature is used.
Since this is used, there is no risk of thermal destruction of the SAt filter 1, which often occurs when manual soldering is performed using a high-temperature soldering iron.

Effects of the Invention As described above, according to the present invention, it is possible to bring the ground potential of the SAt filter close to the reference ground potential of the metal frame, so that it is possible to achieve the targets for ripple and attenuation characteristics.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is an exploded perspective view thereof, Fig. 3 is a perspective view of the SAt filter, Fig. 4 is a perspective view of the SAt filter housed in a case, and Fig. 6 is a perspective view of the SAt filter. FIG. 6 is an exploded perspective view of the conventional example, FIG. 6 is a perspective view of the back side thereof, and FIG. 7 is a characteristic diagram. 1... SAt filter, 6... Case, 6... Input, output lead, 8... Board, 9... Lead hole, 10...Metal frame, 13...Metal plate. Name of agent: Patent attorney Shigetaka Awano and 1 other person9-
Sword Milk Figure 3 Figure 4 Foil Figure 5 Figure 6

Claims (1)

[Claims] Surface acoustic wave (hereinafter referred to as SAW) filter and this S
A filter device in which a metal frame is electrically connected to a substrate to which input and output leads of an AW filter are connected, and a metal plate to which a ground portion of the SAW filter is electrically connected.