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Backlit tactile keyboard with improved tactile and electrical characteristics

  • US 5,138,119 A
  • Filed: 03/15/1991
  • Issued: 08/11/1992
  • Est. Priority Date: 03/15/1991
  • Status: Expired due to Fees
First Claim
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1. A keypad for mounting over a substrate and providing at least one key, said at least one key being backlit by at least one light source, said keypad comprising in combination:

  • an at least partially translucent overlay layer means having a top surface with at least a portion of said top surface comprising at least one key;

    tactile layer means, located under said overlay layer means and having at least one collapsible resilient dome substantially aligned with a corresponding said at least one key, for providing a tactile feedback and an actuation force when said at least one key is depressed a predetermined amount and said at least one resilient dome inverts, each of said at least one resilient, dome including a smaller dome thereon, said smaller dome comprising a means for improving force distribution when said at least one resilient dome inverts and for permitting passage of light from said at least one light source to said at least one key;

    circuitry layer means, located under said tactile layer means and on said substrate, having at least one conductor pair located thereon, said at least one conductor pair being substantially aligned with a corresponding dome of said tactile layer;

    shorting means, with at least one conductive area located between said at least one resilient dome of said tactile layer means and a corresponding said at least one conductor pair of said circuitry layer means and responsive to said tactile layer means, for shorting a corresponding said at least one conductor pair when said key is depressed and said at least one resilient dome inverts, said shorting means including means for passing light from said at least one light source to said at least one key; and

    means for maintaining the relative positions of said overlay layer means, said tactile layer means, said circuitry layer means, and said shorting means.

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