GB2390484A

GB2390484A - Shielding structure for preventing electromagnetic interference of extension module

Info

Publication number: GB2390484A
Application number: GB0215273A
Authority: GB
Inventors: Jinny-Dyi Liao; Kuo-Hsien Wen
Original assignee: Accton Technology Corp
Current assignee: Accton Technology Corp
Priority date: 2002-07-02
Filing date: 2002-07-02
Publication date: 2004-01-07
Also published as: GB0215273D0

Abstract

An extension module 13 for a network communication device is shielded against electromagnetic interference by a shielding structure 14 with top, left and right walls and a rear board formed with an opening for the connecting slot of the module, the shielding structure being fixed to the casing 11 of the device.

Description

SHIELDING STRUCTURE FOR PREVENTING

ELECTROMAGNETIC INTERFERENCE OF EXTENSION

. _ MODULE

The invention relates to a shielding structure against electromagnetic interference, particularly pertinent to a shielding structure for preventing electromagnetic interference of an extension module of network corrununication products.

Owing to the development trend in high speed of electronic products, the leads and printed circuit wire trace inside the electronic products will radiate electromagnetic signals, which will further radiate to and couple with signal wires, cables and conductors of the other surrounding electronic 15 products. For instance, a poor design of the household electric appliances mutually interferes with and results in a poor quality in audio and video - screen, the mutual interference of computer products will cause a malfunction when executing a program or a system crash; lighting equipment will generate a flashing phenomenon as a result of power supply 20 interference. Nowadays, some modern developed countries in the world already have strict EMI / EMC regulations for electronic, IT products, etc. to protect wireless communication and merchandises from an electromagnetic interference with proper care. By and large, to reduce the effect of an 25 electromagnetic interference, the method in reducing the interference source or method with shield is usually employed to confine the electromagnetic signal within a specific area.

- 2 - The current researches of the above electromagnetic interference mostly focus on the aspect of a connector design. However, the researches for an electromagnetic interference effect of network communication products are relatively scarce. A conventional shielding structure against 5 electromagnetic interference of network communication products is disclosed in the patent specification of U.S. Patent No. 6,283,791, entitled "

EMI SHIELDED CONNECTOR OF A HUB," whereas the conventional technique only instructs how to design the shielding structure against electromagnetic interference of connectors, but does not teach how to 10 isolate the electromagnetic interference of expansion modules of network communication products. After all, as the expansion modules of the current network communication products always connect to a fiber optics transmission line, 1000 BASE transmission line or other transmission line with GHz speed class, the electromagnetic interference situation becomes 15 extremely critical. How to effectively isolate the electromagnetic interference of the expansion modules in network communication products is in fact a significantly important subject for the time being.

The major object of the invention is to provide a shielding structure 20 against electromagnetic interference of expansion modules used in network communication products such that the electromagnetic interference generated by the expansion module can be isolated and the expansion module will not affect normal operations of the network communication products. 25 To attain the above object, the invention uses a shielding structure to wrap around the outer space of the expansion module. In addition, the shielding structure is fixed on the case of the network communication product, ensuring theelectromagnetic interference generated from the expansion module to be confined inside of the shielding structure and not 30 affecting the packet transmission of overall network communication

- 3 product due to emission leakage. The shielding structure contains a top lid, metal insulation boards on left and right sides, a front opening and rear metal insulation board. The metal insulation boards on the left and right sides are extended downward from the left and right sides of the top lid and 5 are fixed on the case of the network communication product. The front opening is used to accommodate the expansion module. The rear metal insulation board is extended downward from the back of the top lid and is provided an opening for housing the connection slot. The expansion module can utilize the connection slot for electrically connecting to the 10 circuit board of the communication network board.

The shielding structure against electromagnetic interference according to the invention at least has the following advantages: 1. The electromagnetic interference generated by the expansion module can be confined in the shielding structure without affecting the 15 packet transmission of the entire network communication product due to emission leakage.

2. Inexpensive cost and easy assembly.

o. - - Tess space required and flexible design method upon request at any time.

The present invention will be described by way of example with reference to the appended drawings in which: FIG. l shows a solid diagram of a network communication product according to the invention; 25 FIG. 2 shows a solid diagram of a shielding structure for preventing an electromagnetic interference according to the invention; FIG. 3 shows another solid diagram of a shielding structure for

- 4 preventing an electromagnetic interference according to the invention; and FIG. 4 shows another solid diagram of a shielding structure for preventing an electromagnetic interference according to the invention.

5 FIG. 1 shows a solid diagram of a network communication product 10 according to the invention, including a case 11, a circuit board 12, an expansion module 13 and a shielding structure 14. The back of the case 11 is provided an opening 15 capable of inserting the expansion module 13 into the network commurucation product 10 and electrically connecting to 10 the circuit board 12. The network communication product 10 can be a hub, switch, router, and so on. In general, the expansion module 13 and the other side of the electrical connection plane of the circuit board 12 are connected to a high frequency signal line, such as a fiber optics Transmission line, 1000 BASE transmission line or other transmission with 15 GHz speed. Hence, the electromagnetic interference becomes remarkably critical. To avoid the packet transmission error resulted from the interference of the network communication product 10 or the electromagnetic wave radiation spreading outside the case 11 of the network communication product 10 affecting the nonnal operation of the 20 neighboring electronic products, the invention provides a shielding structure 14 fastened on the case 11, effectively confining the electromagnetic wave in a specific area and gradually releasing the accumulated electromagnetic wave from the bottom lid of the case 11 with a grounding method.

25 FIG. 2 shows a solid diagram of a shielding structure for preventing an electromagnetic interference according to the invention. The shielding structure 14 can be in U shape or other forms, and is fixed on the bottom lid of the case 11 with a screw or built as a whole to integrate with the case 11. For the sake of effectively confining the electromagnetic wave

- 5 generated by the expansion module 13 in the lower area of the shielding structure, the shielding structure 14 can lower its height together with the overall mechanism design as much as possible. Both sides of the expansion module 13 can be added with cooling holes to prevent 5 malfunctioning operations as a result of being unable to dissipate heat of the expansion module 13. Nonetheless, the existence of the cooling holes 21 will lead to the leakage of part of electromagnetic wave, as such the diameter of the cooling holes 21 will better be restrained below 1 mm and be in shape of eaves cover.

10 FIG. 3 shows another solid diagram of the shielding structure against electromagnetic interference according to the invention. The shielding structure 14 and the other side of the connecting side of the expansion module 13 are provided with a connection slot 23 that is electrically connected to the circuit board 12. By means of inserting the expansion 15 module 13 into the connection slot 23, it can be electrically connected to the circuit board 12. However, the gap existing in the location of the connection slot may result in electromagnetic wave leakage. A feasible method is to add a heavy-duty insulation board 22 on the top of the connection slot 23 to prevent electromagnetic wave Leakage. The heavy _ 20 duty insulation board is optional and can be omitted if the operational frequency of the expansion module 13 is not so high and the leakage degree of the electromagnetic wave is within an acceptable range for saving cost and reducing the complexity in assembly.

FIG. 4 shows another solid diagram of the shielding structure against 25 electromagnetic interference according to the invention. After the shielding structure 14 is fixed on the bottom lid of the case 11, the opening of the connecting side in connection with the expansion module is kept open only when the rest of metal insulation boards along all directions are sealed to prevent electromagnetic wave leakage. The shielding structure 14 and the 30 installing face 31 in contact with the bottom lid of the case it can gradually diffuse the accumulated static electricity of the shielding

structure from the bottom lid of the case 11. The shielding structure 14 can be flexible in construction, which can be assembled by various metal insulation boards with screws or built as a whole, and it is not subject to any limitation according to the invention.

5 The above-described embodiments of the present invention are intended to be illustrative only. Numerous alternative embodiments may be devised by Nose skilled in the art without departing from the scope of the following claims.

...DTD:

Claims

-7 CLAIMS

1. A shielding structure for preventing electromagnetic interference, used for an extension module of a network communication product, said extension 5 module using a connection slot to electrically connect to a printed circuit board of said network communication product, said shielding structure comprising: a top lid; left side and right side metal insulation boards connected to said top lid and 10 fixed on a case of said network communication product; a front opening for containing said extension module; and a rear metal insulation board connected to said top lid and having an opening for containing said connection slot.

15

2. The shielding structure of claim 1, which is built as a whole to integrate with said case.

3. The shielding structure of claim 1 or 2, further comprising cooling holes on said left side and right side metal insulation boards.

4. The shielding structure of claim 3, wherein diameters of said cooling holes are less than 1 mm.

5. The shielding structure of claim 1, 2, 3 or 4, further comprising a 25 heavy-duty insulation board on a top of said connection slot.

6. A network communication product comprising a case, a printed circuit board, at least one extension module and at least one connection slot, characterized in that said extension module is enclosed by a shielding structure for preventing 30 electromagnetic interference and said shielding structure is fixed on a case of said

# -8 network communication product.

7. The network communication product of claim 6, wherein said shielding structure is built as a whole to integrate with said case of said network 5 communication product.

8. The network communication product of claim 6 or 7, wherein a plurality of cooling holes are formed on left side and right side metal insulation boards of said shielding structure.

9. The network communication product of claim 8, wherein diameters of said cooling holes are less than I mm.

l O. The network communication product of claim 6, 7, 8 or 9 wherein a I S heavy-duty insulation board is formed on a top of said shielding structure.

11. A shielding structure constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

12. A network communication product having at least one extension module enclosed with a shielding structure according to claim 11.