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Contactless communication with authorization by human contact and visual indicator

  • US 8,676,163 B2
  • Filed: 12/09/2011
  • Issued: 03/18/2014
  • Est. Priority Date: 12/10/2010
  • Status: Active Grant
First Claim
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1. A transponder comprising:

  • a resonant circuit that includes an antenna and a capacitor;

    a memory;

    a contact zone configured to be contacted by a portion of human body;

    an enable/disable circuit configured to switch from a first state, in which the enable/disable circuit does not allow the memory to be accessed, to a second state in which the enable/disable circuit allows the memory to be accessed when the resonant circuit of the transponder is contactlessly powered by a reader; and

    a first indicator configured to indicate that a portion of human body has contacted the contact zone of the transponder, wherein the enable/disable circuit is configured to switch from the first state to the second state in response to a portion of human body being placed on the contact zone and is configured to remain in the second state after the portion of human body is removed from the contact zone, the enable/disable circuit including;

    a switch configured to selectively place the enable/disable circuit in the second state;

    a capacitor configured to store an amount of charge that keeps the switch in a state that keeps the enable/disable circuit in the second state;

    a charge circuit configured to charge the capacitor and place the switch in the state that keeps the enable/disable circuit in the second state in response to a portion of human body being placed on the contact zone; and

    a flip-flop configured to place the enable/disable circuit in the second state, the flip-flop having an input, coupled to the switch, and an output;

    wherein;

    the charge circuit includes a first diode electrically coupled between the contact zone and the capacitor and a second diode electrically coupled between the output of the flip-flop and the capacitor, the first diode being configured to charge the capacitor in response to a portion of human body being placed on the contact zone and the second diode being configured to keep the capacitance capacitor charged based on an output value provided by the flip-flop.

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