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Time accounting system, in particular for parking subject to charge

  • US 5,003,520 A
  • Filed: 02/23/1989
  • Issued: 03/26/1991
  • Est. Priority Date: 05/14/1987
  • Status: Expired due to Fees
First Claim
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1. A time accounting system comprising a card (10) and a case (20);

  • said card having an electronic memory (12) with memory locations, each of the memory locations representing a time unit credit allocated to the holder of the card, and each memory location thereof adapted to be individually and irreversibly written, and coupling means (11) for accessing the memory;

    said case (20) having a clock circuit (26), a writing circuit (27), coupling means (21) for receiving the card and cooperating with the coupling means of the card for enabling a link to be established with the circuits of the case, said writing circuit (27) including means for irreversible writing on the memory locations in the electronic memory (12) of the card (10) received into the case, said writing circuit (27) being periodically triggered under the control of the clock circuit (26) for successively writing the card memory locations and corresponds to gradual consumption, as time elapses, of the time unit credits remaining in the card, and, means (28) for temporarily storing time unit credits, said temporary storing means (28) being activable by said writing circuit (27) in substitution of said electron memory (12) of the card (10) in response to the remaining number of unwritten memory locations representing time unit credits in the card inserted into the case being less than a pre-determined quantity.

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