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Browse Prior Art Database

RFI Grounding of Membrane Keyboards by Metallizing

IP.com Disclosure Number: IPCOM000101237D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Eardley, RA: AUTHOR [+3]

Abstract

A method of cost reducing the RFI grounding arrangements on membrane keyboards is described.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

RFI Grounding of Membrane Keyboards by Metallizing

       A method of cost reducing the RFI grounding arrangements
on membrane keyboards is described.

      The current methods used to achieve RFI grounding on membrane
keyboards (Fig. 1) are by using a braided earth strap 1 or by a
combination of earth wire plus screws 2 through the logic card 10
into a bracket 4 mounted under a metal baseplate 5.

      If the underside of the membrane drive layer 6 in Fig. 2 is
'metallized' 7 either by laminating a metal foil to it or by
'spraying' - both processes currently in existence - then it should
be possible to achieve RFI grounding without braided earth straps or
earth wire, screws or bracket.  The metallized membrane drive layer 6
would be grounded through an alternative triomate-type connector 8
which would contact the membrane switch signal tracks 9 on one side
but be earthed through the metallizing 7 on the otherside.

      The cost of this method would be approximately 35% less than
the strap and 50% less than the wire, screws, bracket arrangements.
This change also allows the logic card to be mounted with push fit
stand- offs (Fastex* type design) and also has the potential to allow
the metal baseplate 5 to be replaced with an alternative lighter
material 9.
* Trademark of Illinois Tool Works Inc.