Evaluation of the number of electromagnetic transponders in the field of a reader
First Claim
1. A terminal for generating a high-frequency electromagnetic field by means of an oscillating circuit, adapted to cooperate with at least one transponder when said transponder enters the electromagnetic field, and including:
- means for regulating a signal phase in the oscillating circuit with respect to a reference value; and
means for evaluating, based on a measurement of a current in the oscillating circuit, a minimum number of transponders present in the electromagnetic field.
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Accused Products
Abstract
A terminal for generating a high-frequency electromagnetic field by an oscillating circuit, adapted to cooperating with at least one transponder when the transponder enters this field, and a method for establishing a communication between the devices, including circuitry for regulating the signal phase in the oscillating circuit with respect to a reference value and circuitry for evaluating, based on a measurement of the current in the oscillating circuit, the minimum number of transponders present in the field.
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Citations
25 Claims
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1. A terminal for generating a high-frequency electromagnetic field by means of an oscillating circuit, adapted to cooperate with at least one transponder when said transponder enters the electromagnetic field, and including:
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means for regulating a signal phase in the oscillating circuit with respect to a reference value; and
means for evaluating, based on a measurement of a current in the oscillating circuit, a minimum number of transponders present in the electromagnetic field. - View Dependent Claims (2, 3, 4, 5, 9)
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6. A method of establishing at least one communication between a terminal generating a high-frequency electromagnetic field and a transponder, including:
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periodically sending a request sequence until at least one transponder entering the field sends an acknowledgement, and evaluating, based on a measurement of a current in an oscillating circuit of the terminal, a minimum number of transponders likely to be present in the electromagnetic field. - View Dependent Claims (7, 8, 10)
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11. A terminal adapted to generate an electromagnetic field and to communicate with at least one transponder that is present in the electromagnetic field, the terminal comprising:
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an oscillating circuit;
a first circuit to measure the current in the oscillating circuit; and
a second circuit to determine, based at least in part on the measured current, a minimum number of transponders present in the electromagnetic field. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of determining a number of transponders present in an electromagnetic field generated by a terminal including an oscillating circuit, the method comprising:
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measuring a current in the oscillating circuit; and
determining, based on a comparison of the measured current with a reference value, a minimum number of transponders present in the electromagnetic field. - View Dependent Claims (21, 22, 23, 24, 25)
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Specification