JPH0143912Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention is a shielding case used for high-frequency electrical equipment, and particularly relates to an improvement in the mounting structure for external equipment.

(b) Conventional technology For high-frequency electrical equipment such as electronic tuners and RF modulators, high-frequency circuit components are embedded and wired on a printed circuit board, and the printed wiring body is housed in a shield case to prevent unnecessary radiation and stabilize the electrical characteristics. It will be done. A shield case generally has a structure in which two shield covers are fitted from above and below into a frame-shaped opening of a frame-shaped base member made by punching and bending a metal plate. In addition, the shield case is generally attached to an external device by forming taps at one or more locations on the frame-shaped base member and fixing them with screws, but this attachment structure has a problem.

For example, two conventional examples of RF modulators will be explained with reference to FIGS. 1 to 5. In an example of FIGS. 1 to 3, a shield case 1 is composed of a frame-shaped base member 2 having a mouth shape and two shield covers 3, 3 that are fitted into the opening thereof. Reference numeral 4 denotes a high frequency printed wiring body housed within the frame-shaped base member 2, in which a high frequency circuit component 6 is assembled and wired on a printed circuit board 5. 7 is a tap formed at one corner of the base member 2. In addition, 8 to 10 are channel selectors protruding from the shield cover 3,
Antenna input terminal, TV output terminal, 11 is a VTR output terminal protruding from one side of the base member 2,
The antenna input terminal 9 and the TV output terminal 10 have screws cut on their outer peripheries. The shield case 1 is attached to the external device 12 by screwing a mounting screw 13 into the tap 7 and by screwing a nut (not shown) into each output terminal 9, 10.

The structure of installing the shield case 1 is simple, but since the tip of the mounting screw 13 enters the case, the stray capacitance and inductance inside the case change, resulting in a change in high frequency characteristics, and the mounting screw 13 may change. There was an inconvenience that it came into contact with the high frequency circuit components 6 inside the case. Further, due to such defects, there are restrictions on the mounting position of the tap 7 and the dimensions of the mounting screw 13, making the overall design extremely difficult.

The conventional example shown in FIGS. 4 and 5 is a frame-shaped base member 1.
For example, cut and raised pieces 15 are provided protrudingly at, for example, three locations on the piece 4, and taps 16 are formed on each cut and raised piece 15. According to this structure, the problems of the conventional example described above are solved, but because of the cut and raised pieces 15...
There was a problem that the notch holes 17 were formed in the base member 14, increasing the risk of deterioration in shielding performance, and lowering the mechanical strength of the base member 14.

(c) Purpose of the invention In view of the above-mentioned conventional problems, it is an object of the present invention to provide a shield case that solves all of them.

(d) Structure of the invention The present invention involves extending the part of the frame-shaped base member that forms the side wall part to form an extension part, and attaching this extension part to the mounting piece for screwing the shield case from the outer wall surface of the frame-shaped base member. This is a shield case with a protruding structure. By forming the mounting piece with the extra part in this way, there is no need to worry about damaging the shielding properties and mechanical strength of the base member, and the mounting screws do not enter the case, so the above conventional problems are easily solved. can.

(E) Example An example in which the present invention is applied to an RF modulator similar to that shown in FIG. 1 is shown in FIGS. 6 to 8.
is a shield case, which includes a square-shaped base member 21 and two shield covers 22, 22 that close this opening.
Consists of. The same reference numerals as in other figures in FIG. 1 indicate the same contents. The only feature of this shield case 20 is that the following three mounting pieces 23 are integrally provided on the outer wall surface of, for example, three corners of the base member 21. Each mounting piece 23 is formed by extending the side end of the main part of the base member 21 and bending the extended portion 24 inward by 90 degrees. Each mounting piece 23 is pre-formed with a tap or elongated mounting hole 25 for fixing a shield case screw. Further, each mounting piece 23 is formed by punching out the base member 21 from a metal plate integrally with the main part as shown in FIG. 9, and then bending it together with the main part.

Note that the present invention is not limited to the above-described embodiments, and the number and shape of the mounting pieces may be changed depending on the type of high-frequency electrical equipment to which it is applied.

(F) Effects of the invention As described above, according to the invention, there is no need for large openings to be formed in the base member by the mounting pieces, and therefore there is no deterioration in shielding performance or mechanical strength. Furthermore, since the mounting piece is provided outside the base member, the mounting screws do not enter the case, making it possible to provide a shield case with stable characteristics and high reliability.

[Brief explanation of drawings]

Figures 1 and 2 are a plan view and a side view of a conventional shield case, Figure 3 is a partial sectional view of the shield case in Figure 1 when it is attached to an external device, and Figures 4 and 5 are other figures. FIGS. 6 and 7 are a plan view and a side view of an embodiment of the present invention, and FIGS. 8 and 9 are a frame of the shield case shown in FIG. 6. FIG. 6 is a partially enlarged perspective view and a developed view of the shape base. 20... Shield case, 21... Frame-shaped base, 22... Shield cover, 23... Mounting piece,
24...extension part.

Claims (1)

[Claim for Utility Model Registration] A shield cover is fitted over the frame-shaped opening of the frame-shaped base member forming at least the side wall portion to shield the interior from high frequency waves, and a mounting piece for screwing the shield case to external equipment is provided. In the shield case, the member forming the side wall of the shield case of the frame-shaped base member is extended extra, and the extended portion is provided to protrude from the outer wall surface of the frame-shaped base as a mounting piece for fixing the shield case screws. A shield case that is characterized by: