GB2316236A

GB2316236A - Shielding case for high frequency equipment

Info

Publication number: GB2316236A
Application number: GB9715729A
Authority: GB
Inventors: Hiroto Kinuyama; Tadaaki Oonishi; Naoto Akiyama
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1996-08-07
Filing date: 1997-07-28
Publication date: 1998-02-18
Anticipated expiration: 2017-07-28
Also published as: GB2316236B; CN1085932C; GB9715729D0; KR100286476B1; CN1173109A; JP3264835B2; KR19980018409A; JPH1056282A; MY123350A

Abstract

A plurality of upper claws 11 and lower claws 12 are formed on an upper cover 10, with the lower claws 12 being at a position lower than that of the upper claws 11 and extending horizontally from the conical surface 13, and the edges of the lower claws 12 overlapping the edges of the upper claws 11. The upper cover 10 is placed upon the upper opening plane of the frame 2, and the protruding portion 3a at the upper edge of the partition plate 3 is fit between the free ends of the lower claws 12. This causes the lower claws 12 to be raised upwards by the protruding portion 3a so as to come into contact with the edge lower surface of the neighboring upper claws 11, so that the partitioning plate 3 is grounded to the upper cover 10 via the lower claws 12.

Description

SHIELDING CASE FOR HIGH-FREQUENCY EQUIPMENT The present invention relates to a shielding case for high-frequency equipment which uses high frequency circuits such as television receiver tuners and the like, and particularly relates to a grounding configuration between a partitioning plate which is provided to the side of the framing and a cover which covers the opening plane of the framing.

Generally, shielding cases for high-frequency equipment which uses local oscillator circuits is electrically shielded by dividing the interior of the framing by means of a plurality of partitioning plates and covering the opening plane of the aforementioned framing with a cover, so as to obtain circuit effects, and at the same time to prevent undesirable effects such as leakage of local oscillation signals (OSC signals) to other circuitry.

Fig. 6 is a plan view illustrating the principal components of a known shielded case, and Fig. 7 is a crosssectional diagram along line VIl-VIl in Fig. 6. In the Figures, reference numeral 1 denotes a print substrate 1 mounted with an unshown local oscillating circuit or some other circuit members, reference numeral 2 denotes framing for storing this print substrate, reference numeral 3 denotes a partitioning plate for partitioning the interior of the framing 2 into a plurality of chambers, reference numeral 4 denotes an upper cover for covering the upper opening plate of the framing 2, reference numeral 5 denotes a lower cover for covering the lower opening plate of the framing 2, and reference numeral 6 denotes soldering for connecting the print substrate 1 and the partitioning plate 3. 4 claws 7 are formed onto the aforementioned upper cover 4, and each of the claws 7 are separated by means of a center hole 8 and a cross-shaped slit 9.

By schematically constructing a shielding case as described above, wherein the upper cover 4 is placed over the upper opening plane of the framing 2 and the protrusion 3a to the upper end of the partitioning plate 3 is fit through the hole 8, each of the claws 7 are thereby pressed by the protrusion 3a and deformed upwards, so that the partitioning plate 3 is grounded to the upper cover 4 via each of the claws 7, and the local oscillation signal generated by the local oscillation circuit is flows to the framing 2 via the partitioning plate 3 and the upper cover 4, and consequently, the signal can be inhibited from flowing to other circuitry.

With a shielding case such as described above, fitting the protrusion 3a of the partitioning plate 3 into the hole 8 of the upper cover 4 causes the plurality of claws 7 formed around the hole 8 to come into contact with the perimeter surface of the partitioning plate 3, such a construction facilitating increasing of the shielding effect due to lessened notch gaps around the claws as compared to the grounding construction wherein cantilever claws formed by cutting out in the upper cover are caused to come into elastic contact with the upper edge of the partitioning plate, as with the shielding case disclosed in Japanese Unexamined Utility Model Publication No. 59-81088. Also, this arrangement is also advantageous in that conductivity is increased between the partitioning plate 3 and the upper cover 4 since flux adhered to the surface of the partitioning plate 3 is scraped off by the claws 7, upon inserting the protrusion 3a of the partitioning plate 3 through the hole 8 of the upper cover 4.

However, since the protrusion 3a of the partitioning plate 3 is fit through the center of the claws 7 formed in the upper cover 4, in the event that there is even slight mutual offset between the positions of the hole 8 and the protrusion 3a, not only is the work of fitting the protrusion 3a through the hole 8 made difficult, but there have been problems wherein the reaction force of the forcibly bent claws 7 is applied to the partitioning plate 3 in the form of bending stress, following placing of the upper cover 4 upon the upper opening plane of the framing 2, and this bending stress has caused cracking in the solder 6.

Now, since such problems occur when the claws 7 are formed of so as to be relatively difficult to bend, arrangement may be conceived wherein the thickness of the upper cover 4 is reduced so as to make each of the claws 7 easier to bend, but in such a case, in the event that shock is applied to the upper cover 4 or the framing 2 due to dropping the like, following placing of the upper cover 4 onto the upper opening plane of the framing 2, there is a new problem in that each of the claws 7 becomes deformed and detached from the partitioning plate 3, and in such a case, conductivity between the partitioning plate 3 and the upper cover 4 cannot be maintained.

Accordingly, it is an object of the present invention to provide a shielding case for high-frequency equipment wherein the problems such as described above have been dealt with. To this end, the present invention involves providing a cover for covering the opening plate of the framing with lower claws and upper claws which mutually overlap in the direction of the plane of one another, so that fitting the edge portion of the partitioning plate which partitions the framing into a plurality of chambers through the tips of the aforementioned lower claws causes the lower claws to come into contact with the lower plane of the aforementioned upper claws. Thus, by making the arrangement to be of a two-tiered construction comprised of lower claws and upper claws, even in the event that there is slight mutual offset between the positions of the members upon placing the cover over the framing, this offset is absorbed by the easily flexible lower claws following the edge of the partitioning plate, thus preventing generation of cracking in the solder which connects the partitioning plate to the print substrate. Further, since deforming of the lower claws is prevented by the upper claws following placing of the cover onto the framing, the contact condition between the cover and partitioning plate can be maintained in a markedly stable state.

The shielding case for high-frequency equipment according to the present invention comprises: a print substrate mounted with circuit members such as a local oscillating circuit; framing which stores the aforementioned print substrate and of which the interior is divided into a plurality of portions by means of partitioning plates; and a cover which electrically shields the aforementioned framing by means of covering the opening plane of the aforementioned framing; wherein the aforementioned cover is provided with lower claws and upper claws which mutually overlap in the direction of the plane of one another, and wherein the aforementioned lower claws are made to come into contact with the lower surface of the aforementioned upper claws by means of fitting the aforementioned partitioning plate between the tip portion of the aforementioned lower claws and the aforementioned upper claws.

Although the form of the aforementioned lower claws and the aforementioned upper claws is not relevant as long as the claws mutually overlap in the direction of the plane of one another, but making these lower claws and upper claws to be fan-shaped is advantageous, since the claws can be easily overlapped simply by shifting the upper claws in a radial direction, thus simplifying the mold structure for forming the cover.

Also, the aforementioned lower claws and the aforementioned upper claws may be of identical shape and form, but forming the upper claws to be wider than the lower claws increase the mechanical strength of the upper claws, thus increasing the deformation prevention effects of the upper claws to the lower claws.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a plan view illustrating the principal components of the shielded case for high-frequency equipment according to the present invention; Fig. 2 is a cross-sectional diagram along line Il-Il in Fig. 1; Fig. 3 is a plan view of the cover provided to the shielded case; Fig. 4 is a cross-sectional diagram along line IV-IV in Fig. 3; Fig. 5 is a diagram for describing the fabrication process of the aforementioned cover; Fig. 6 is a plan view illustrating the principal components of a known shielded case; and Fig. 7 is a cross-sectional diagram along line VII-VII in Fig. 6.

With reference to the drawings, Fig. 1 is a plan view illustrating the principal components of the shielded case for high-frequency equipment according to the present invention, Fig. 2 is a cross-sectional diagram along line II-II in Fig. 1, Fig. 3 is a plan view of the cover provided to the shielded case, Fig. 4 is a cross-sectional diagram along line IV-IV in Fig. 3, and Fig. 5 is a diagram for describing the fabrication process of the aforementioned cover. In the Figures, the members which are equivalent to those in the above-described Fig. 6 and Fig. 7 are provided with the same reference numeral.

The points of difference between the shielded case according to the present embodiment and the known example described in Figs. 6 and 7 is that in the present embodiment, the upper cover 10 is provided with a plurality of upper claws 11 and lower claws 12 which mutually overlap in the direction of the plane of one another, and wherein the lower claws 12 are made to come into contact with the lower surface of the upper claws 11 by means of fitting the protruding portion 3a at the upper edge of the partitioning plate 3 between the tips of the lower claws 12 so as to protrude therefrom, upon covering the upper opening plane of the framing 2 with the upper cover 10; other configurations thereof are basically equivalent.

The aforementioned upper claws 11 and lower claws 12 are made to be in a fan-shaped form, these being formed alternating in the peripheral direction within a cone surface 13 formed within the aforementioned upper cover 10, with the upper claws 11 being formed sufficiently wider than the lower claws 12. As shown in Fig. 3 and Fig. 4, in the state before the upper cover 10 is placed upon the framing 2, the lower claws 12 are at a position lower than that of the upper claws 11 and extending horizontally from the conical surface 13, and the sides of the lower claws 12 are overlapping the sides of the upper claws 11. For fabricating the overlapped form, first, as shown in Fig. 5A, a concave portion 14 in an inverse conical form on the plate surface of the upper cover 10 by means of drawing, and a hole 15 (diameter dl) is formed at the bottom center of the concave portion 14. Next, as shown in Fig. 5B, an unshown punch and die are used to form slits in the concave portion 14 from the inclined plane thereof to the bottom plane thereof, so as to separate the upper claws 11 and the lower claws 12, and also, the upper claws 11 are pressed back toward the plate surface of the upper cover 10.

Consequently, there is slight deviation of the upper claws 11 toward the center of the hole 15, so while the tip distance of the opposing lower claw 12 remains unchanged at dl, the tip distance of the opposing upper claw 11 becomes d2, and as described above, the side portion of each of the lower claws 12 overlaps the side portion of the neighboring upper claw 11.

Regarding assembly of a shielding case for highfrequency equipment such as described above, the print substrate 1, framing 2, and partitioning plate 3 are integrated beforehand, following which the upper cover 10 is placed upon the upper opening plane of the framing 2, and as shown in Figs. 1 and 2, the protruding portion 3a at the upper edge of the partition plate 3 is fit between the tips of the lower claws 12. This causes the lower claws 12 to be raised upwards by means of the protruding portion 3a so as to come into contact with the lower surface of the neighboring upper claws 11, so that the partitioning plate 3 is grounded to the upper cover 10 via the lower claws 12, and the local oscillation signals generated by the local oscillation circuit flow through the framing 2 via the partitioning plate 3 and upper cover 10, thus inhibiting the signals affecting other circuitry. At this time, even if there is slight mutual offset between the positions of the upper cover 10 and the framing 2, the protruding portion 3a of the partition plate 3 is not in contact with the upper claws 11 but rather is only in contact with the easily deformable lower claws 12, so that the aforementioned offset is absorbed by the easily flexible lower claws 12 following the partitioning plate 3. Accordingly, forcible bending stress is not placed upon the partitioning plate 3 from the lower claws 12, thus preventing generation of cracking in the solder 6 in a sure manner. Also, even in the event that shock is applied to the upper cover 10 or the framing 2 due to dropping or the like following placing of the upper cover 10 onto the upper opening plane of the framing 2, the claws 12 are not easily deformed since they are in contact with the lower surface of the upper claws 11 and are not detached from the protruding portion 3a of the partitioning plate 3, and consequently, conductivity between the partitioning plate 3 and the upper cover 10 is maintained in a sure manner.

With the aforementioned embodiment constructed thus, a plurality of upper claws 11 and lower claws 12 are formed on an upper cover 10 which is placed on the upper opening plane of a frame 2, the arrangement being of a two-tiered construction wherein the upper claws 11 and lower claws 12 overlap, so that even in the event that there is slight mutual offset between the positions of the members upon placing the upper cover 10 over the framing 2, this offset is absorbed by the easily flexible lower claws 12 following the protruding portion 3a of the partitioning plate 3, and thus forcible bending stress is not placed upon the partitioning plate 3, consequently preventing generation of cracking in the solder 6 in a sure manner. Further, since deforming of the lower claws 12 is prevented by the upper claws 11 following placing of the upper cover 10 onto the framing 2, the contact condition between the upper cover 10 and partitioning plate 3 can be maintained in a markedly stable state.

The upper claws 11 and lower claws 12 are made to be fan-shaped, and the upper claws 11 and lower claws 12 are relatively shifted in the radial direction of the hole 15 with the conical plane 13 as a base, thus forming the upper claws 11 and lower claws 12 on the upper cover 10, and facilitating overlapping of both, consequently simplifying the mold structure for forming the upper cover 10.

Moreover, the upper claws 11 are formed to be wider than the lower claws 12, increasing the ease of deformation of the lower claws 12, and increasing the mechanical strength of the upper claws 11, thus increasing the deformation prevention effects of the upper claws 11 to the lower claws 12.

The present invention is implemented by an arrangement such as the above-described embodiment, and exhibits advantages such as described below.

Due to the arrangement comprising a print substrate mounted with circuit members such as a local oscillating circuit, framing which stores the aforementioned print substrate and of which the interior is divided into a plurality of portions by means of partitioning plates, and a cover which electrically shields the aforementioned framing by means of covering the opening plane of the aforementioned framing wherein the aforementioned cover is provided with lower claws and upper claws which mutually overlap in the direction of the plane of one another, and wherein the tips of the aforementioned lower claws are made to come into contact with the lower surface of the aforementioned upper claws by means of fitting the aforementioned partitioning plate between the tips of the aforementioned lower claws and the aforementioned upper claws, consequently, even in the event that there is slight mutual offset between the positions of the members upon placing the cover over the framing, generation of cracking in the solder connecting the partitioning plate to the print substrate can be prevented, and since deforming of the lower claws is prevented by the upper claws following placing of the cover onto the framing, the contact condition between the cover and partitioning plate can be maintained in a markedly stable state.

Further, forming the lower claws and upper claws each to be fan-shaped allows for the claws to be easily overlapped simply by shifting the upper claws in a radial direction, thus simplifying the mold structure for forming the cover.

Also, forming the aforementioned upper claws to be wider than the aforementioned lower claws increases the mechanical strength of the upper claws, thus increasing the deformation prevention effects of the upper claws to the lower claws.

Claims

CLAIM

1. A shielding case for high-frequency equipment, comprising: framing which stores a print substrate mounted with circuit members and of which the interior is divided into a plurality of portions by means of partitioning plates; and a metal plate cover which electrically shields said framing by means of covering the opening plane of said framing; wherein said cover is provided with a plurality of lower claws and upper claws which are alternately arrayed with the free ends thereof facing a central point, and wherein the edges of said lower claws and upper claws are caused to overlap, and further wherein said lower claws are raised in an upwards direction by means of a protrusion at the upper edge of said partitioning plate so that said lower claws are made to come into contact with the lower surface of said upper claws.

2. A shielding case for high-frequency equipment according to Claim 1, wherein both said lower claws and said upper claws are fan-shaped such that the width of the base portions thereof is greater than the width of the free ends thereof.

3. A shielding case for high-frequency equipment according to Claim 1 or Claim 2, wherein the base portion of said upper claw is formed to be wider than the base portion of said lower claw.

4. A shielding case substantially as hereinbefore described, with reference to, and as illustrated by, the accompanying drawings.