Try small tactile swithes behind the rubber membrane...its the only way for
indurance...l have used it on a recent project because of that very
reason...l know from experience that the carbon/rubber pads cause all kinds
of problems...the dust they leave behind can conduct even when not pushed
also...as for the screened on numbers well thats another story...

> >
> >I am interested in what mechanism you use to stop
> >the conductive rubber wearing away? This is one of the
> >most common faults I see, even with the gold plated
> >contacts the rubber still is subject to wear.
>
> I don't know that we took any steps against it. Until it was mentioned
here
> on the sig, I had never heard of that as a possible failure mechanism, or
> seen it happen.  I'm sure the plastic overcap and frame is a big
> contributor to success.  The keyboards that just screen the numbers onto
> the rubber always get worn off, or the rubber itself gets torn.
>
> Grab a verifone charge card terminal, and have a look. It's the same
keypad
> design in all the small (Jr, Xl, tranz...) units.
>
>
> >Who wants to make a product that lasts forever anymore?
>
> We figured our first terminals would be obsolete by 1987, but we also
> designed them so that Y2K wasn't a problem.
>
>
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>
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