Browse Prior Art Database

EMI Radiated Noise Reduction Method in Notebook Type PCs

IP.com Disclosure Number: IPCOM000112947D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Fukuda, K: AUTHOR [+4]

Abstract

This article describes a method to reduce EMI (Electromagnetic Interference) emission by direct or indirect electrical connection between the display subassembly and the enclosure of Notebook PC. The direct connection is the contact between the shielding material of the system unit of the Notebook Type Personal Computer and the shielding material of the flat display subassembly. The indirect connection is the contact by intermediary of the conductive material.

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EMI Radiated Noise Reduction Method in Notebook Type PCs

      This article describes a method to reduce EMI (Electromagnetic
Interference) emission by direct or indirect electrical connection
between the display subassembly and the enclosure of Notebook PC.
The direct connection is the contact between the shielding material
of the system unit of the Notebook Type Personal Computer and the
shielding material of the flat display subassembly.  The indirect
connection is the contact by intermediary of the conductive material.

      This method is effective in not only the reduction of EMI
radiated/conducted emission but also the decrease of the influence
caused by electromagnetic energy coupled into sensitive circuits,
interconnecting signal and power leads.

      Figs. 1, 2, 4 and 5 show the relation between electromagnetic
field strength and frequency radiated from Notebook Type Personal
Computer.  Line 1 in Fig. 1 shows Federal Communication Commission
(FCC) class B limit of EMI radiated emission level.  Fig. 1 shows the
EMI radiated emission from Notebook Type Personal Computer without
'the indirect contact'.  Fig. 2 shows the EMI radiation in case of
'the indirect contact' by using a Hinge made of conductive material.

      Fig. 3 shows the flat display module 2 and the system unit 4 of
Notebook Type Personal Computer.  3 and 5 are a naked area of the EMI
shielding conductive material.  Fig.  4 shows that the
electromagnetic field level exceeds t...