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KEYBOARD BASED IN POLYMER, COPOLYMER OR COMPOSITES WITH PIEZO- AND/OR PYROELECTRIC PROPERTIES AND RESPECTIVE USE

  • US 20100253552A1
  • Filed: 07/17/2008
  • Published: 10/07/2010
  • Est. Priority Date: 07/17/2007
  • Status: Active Grant
First Claim
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1. Laminar keyboard based on a material with piezo- and/or pyroelectric proprieties, comprising:

  • a film consisting of a polymeric, copolymeric or composite material with piezo- and/or pyroelectric proprieties;

    at least one key formed by one conductive electrode and by the film with piezo- and/or pyroelectric proprieties, which thus induces a mechanical and/or thermal signal;

    a grounded electrode placed underneath the piezoelectric film;

    connections between the keys and the readout system of the keys by means of the contact points;

    a multiplexer which establishes the electric connection between each contact point and a bandpass filter;

    a band-pass filter that separates the piezoelectric and the pyroelectric effects through the regulation of its central frequency;

    a rectifier which eliminates the negative component from the output signal on the band-pass filter; and

    a low-pass filter, that filters the signal from the rectifier or a digital circuit of rebound elimination from the signal provided by the rectifier in order to obtain a single pulse at the output for the pressure applied in each key.

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