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Electromagnet induced switch

  • US 5,880,539 A
  • Filed: 04/10/1997
  • Issued: 03/09/1999
  • Est. Priority Date: 12/05/1996
  • Status: Expired due to Term
First Claim
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1. A keyboard system, comprisinga keyboard array scanning device havinga plurality of electromagnet induced switches mounted thereon, each of said electromagnet induced switches including a magnet core,a substrate having a plurality of through holes, each through hole corresponding to a magnetic core,first conductive membranes disposed on a first surface of the substrate,second conductive membranes disposed on a second surface of the substrate opposite the first surface,a scanning line electrically connected to each first conductive membrane, anda return line electrically connected to each second conductive membrane,each first and second conductive membrane being positioned relative to a through hole such that, when a current in a first membrane adjacent to a through hole is varied while an electromagnet induced switch is depressed to thereby cause the corresponding magnet core to move down through said through hole, a current is induced in a second conductive membrane adjacent said through hole;

  • an encoder electrically connected to the scanning line;

    a current and voltage controlling device electrically connected to each of the first and second conductive membranes to enhance the sensitivity of the keyboard system to current induced in a second conductive membrane;

    a CPU electrically connected to the input port of said encoder;

    an analog multiplexer electrically connected to said returning line and said CPU;

    a signal amplifying device electrically connected to an output port of said analog multiplexer, to amplify the signal from said multiplexer;

    a signal triggering device electrically connected to an output port of said signal amplifying device to receive a signal from said signal amplifying device and establish an upper and lower threshold for accuracy of the signal, so that the signal from said signal amplifying device can be categorized at a high or low level; and

    a breaking point controlling device electrically connected to said signal amplifying device and also to said CPU, wherein said breaking point controlling device during operation receives the controlling signal from said CPU to obtain upper or a lower limits for correcting the triggering position.

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