Electrical transmission or interconnection systems – Anti-induction or coupling to other systems
Reexamination Certificate
1999-04-22
2001-06-19
Paladini, Albert W. (Department: 2836)
Electrical transmission or interconnection systems
Anti-induction or coupling to other systems
C320S118000, C333S018000, C361S818000, C369S107000
Reexamination Certificate
active
06249062
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a technique for protecting an electronic device from electromagnetic interference (EMI), and in particular to a method and apparatus for pseudogrounding an electronic device which is connected to a plurality of cables such as communication lines, power supply lines, and interface buses.
BACKGROUND
For corporate information communication devices such as switches for PBX (private branch exchange), ATM (asynchronous transfer mode) switches, etc. which are connected to a number of communication lines, such as telephone lines of unshielded twisted pair cables which are wired simultaneously with construction of building, it is generally impossible to replace all existing indoor wires with new shielded wires which are employed for information devices such as personal computers and main frames, etc.
SUMMARY OF THE DISCLOSURE
Accordingly, protection against EMI was endeavored by passing communication lines, interface lines or power supply lines through apertured ferrite cores. However, cost for preventing EMI is tremendously high due to use of a lot of expensive ferrite cores.
Since the standards of measurement which are specified by CISPR22, VCCI is added with an additional requirement that the packages and cables should be added until no increase in measured radiated noise by 2 dB or more occurs when the number of packages and cables is increased in case where a plurality of packages and cables are incorporated in a device under test, a measurement should be conducted in a system in which a maximum number of packages and cables are accommodated. A stable protection against EMI, in which the energy of the radiated noise never increase even if the number of packages and cables is increased has been demanded.
The present invention has been thus achieved in view of the above-mentioned problem. It is an object of the present invention to provide a method and apparatus for protecting an electronic device from EMI at a low expenditure without using any expensive ferrite cores, particularly those which achieve reduction in the number of steps for EMI protection and in cost therefor.
It is a further object of the present invention to provide a novel method and apparatus which is capable of pseudogrounding communication lines, etc.
In order to achieve the above-mentioned object, there is provided a method for protecting against EMI, according to a first aspect of the present invention. In the method, a wiring is pseudogrounded by radio-frequency connecting said wiring having a level of the radiated noise energy which is reduced to a value less than that of a pseudogrounded housing to said housing via a capacitance.
In a method according to a second aspect of the present invention, a wiring is pseudogrounded (a) by making the level of the radiated noise energy of a package which is accommodated in a pseudogrounded housing less than that of said housing, and (b) by radio-frequency connecting said wiring connected to a circuit block on said package and connected to an external wiring via a connector to said pseudogrounded housing via a capacitive element.
According to a third aspect of the present invention, there is provided a structure, wherein a wiring that is connected to an integrated circuit block on a package to be accommodated in a housing, and is connected to an external wiring via a connector is radio-frequency connected to a pseudogrounded housing (particularly pseudogrounded earth position) via a capacitive element in said package.
REFERENCES:
patent: 4274050 (1981-06-01), Martin
patent: 4760231 (1988-07-01), Hayashi
patent: 4908735 (1990-03-01), Tsuneki
patent: 5488540 (1996-01-01), Hatta
patent: 5589718 (1996-12-01), Lee
patent: 5757338 (1998-05-01), Bassetti et al.
patent: 5841202 (1998-11-01), Noguchi et al.
patent: 6008682 (1999-12-01), Mirov
patent: 0 181 286 A1 (1986-05-01), None
patent: 0 673 057 A2 (1995-09-01), None
patent: 61-212193 (1986-09-01), None
patent: 63-107195 (1988-05-01), None
patent: 6-2786 (1994-01-01), None
patent: 6-85485 (1994-03-01), None
patent: 06-098539 (1994-04-01), None
patent: 6-252575 (1994-09-01), None
patent: 9-312488 (1997-12-01), None
patent: 10-22857 (1998-01-01), None
Deguchi Masaru
Kohya Kenji
Suzuki Mitsuo
Foley & Lardner
NEC Corporation
Paladini Albert W.
LandOfFree
Method and apparatus of pseudogrounding does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus of pseudogrounding, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus of pseudogrounding will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2461596