EMC shield for expansion slots

Details EMC shield for expansion slots EMC shield for expansion slots

2004-01-22

2004-11-23

Vu, Phuong T. (Department: 2841)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S740000, C361S759000, C361S816000, C361S818000, C174S034000

Reexamination Certificate

active

06822877

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to ElectroMagnetic Compatibility (EMC) shields, and particularly to an EMC shield for shielding expansion slots in a rear panel of a computer enclosure to reduce leakage of electromagnetic radiation.
2. Prior Art
In the enclosure of a typical personal computer, there are generally kinds of electronic components such as Central Processing Units (CPUs) and accelerated chips mounted therein. The electronic components may emit electromagnetic radiation as operating. Computer systems are manufactured with expansion slots to allow peripheral devices to be added to the systems, so most of the electromagnetic radiation will leak out through the expansion slots to potentially interfere with other electronic components.
Typically, a plurality of cover plates is attached to a rear panel and block the expansion slots thereon. However, as the internal circuitry of computers has advanced, the cover plates can be inadequate to block the electromagnetic radiation. The inadequacy of the cover plates is believed to be due to gaps between the cover plates and the computer enclosure.
To overcome these shortcomings, conventional EMC shields are disclosed in Taiwan Patent Application No. 84209619. Each EMC shield is discrete and is mounted on a corresponding strip between two expansion slots. Two holes are defined in each strip. Each EMC shield is made with size according to the corresponding strip. Two brims are formed toward each other from opposite sides of each EMC shield for packing the corresponding strip. Two hooks are formed on each EMC shield corresponding to the holes of the strip, and a plurality of elastic tabs is stamped from each EMC shield. A plurality of cover plates is secured to the expansion slots and presses the tabs of the EMC shields to prevent electromagnetic radiation from leaking out. However, the discrete strips must be mounted to the strips one by one, which is cumbersome and time-consuming.
A typical computer enclosure EMC shield
10
′, as shown in
FIG. 5
, is integrally made by stamping a rectangular metal sheet. A bent portion
20
′ extends perpendicularly from one end of the EMC shield
10
′. A plurality of fixing holes
18
′ is defined in the bent portion
20
′ of the EMC shield
10
′. The EMC shield
10
′ defines a plurality of elongated openings
12
′ and forms a plurality of beams
14
′ alternating with the opening
12
′. A plurality of tabs
16
′ is stamped from the beams
14
′. In pre-assembly, screws must be used to fasten the EMC shield
10
′ to a rear panel of the computer enclosure via the fixing holes
18
′, which is cumbersome and time-consuming. This will lower the assembly efficiency.
Thus, an improved EMC shield which overcomes the above-mentioned problems is desired.
BRIEF SUMMARY OF THE INVENTION
Correspondingly, an object of the present invention is to provide an EMC shield that can reduce leakage of electromagnetic radiation through a computer enclosure.
Another object of the present invention is to provide an EMC shield that is easy to be assembled.
To achieve the above-mentioned objects, an EMC shield attachable to a rear panel of a computer enclosure defines a number of elongated openings and forms a number of bars alternating with the openings. The EMC shield includes at least one hook folded back from the EMC shield at one side of at least one opening for engaging with the rear panel, a number of arch-shaped strips protruding outwardly and forwardly on said bars, and a number of tabs protruding outwardly and rearwardly on said bars alternating with the strips.
Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of a preferred embodiment of the present invention with the attached drawings, in which:


REFERENCES:
patent: 5679923 (1997-10-01), Le
patent: 6058025 (2000-05-01), Ecker et al.
patent: 6182835 (2001-02-01), Chen
patent: 6618271 (2003-09-01), Erickson et al.
patent: 99240664.1 (2000-09-01), None
patent: 264067 (1995-11-01), None

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