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Method for wireless transmission of data to a data carrier

  • US 5,286,955 A
  • Filed: 02/21/1992
  • Issued: 02/15/1994
  • Est. Priority Date: 03/07/1991
  • Status: Expired due to Term
First Claim
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1. A method for wireless transmission of data onto a data carrier having a semiconductor circuit (1), in particular onto a chip card or IC card, wherein the supply voltage of said semiconductor circuit (1) is generated by a high-frequency field (10) in which the data carrier has been placed, characterized by the following features:

  • a) for transmission of logic levels and command instructions said high-frequency field (10) is switched off and on such that the duration of the transmission intervals is constant whereas the transmission duration is of varying length depending on the logic levels and command instructions to be transmitted,b) the transmission duration is determined from the number of periods transmitted of said high-frequency field (10),c) to retrieve the data transmitted with said high-frequency field (10), the number of periods of said high-frequency field (10) transmitted between two transmission gaps is ascertained, stored and evaluated,d) to ascertain the number of periods, a clock signal is generated exclusively during the transmission times,e) to minimize the current consumption of said semiconductor circuit (1), the clock signal is off during the transmission gaps.

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