Operation in very close coupling of an electromagnetic transponder system
First Claim
1. A method of data transmission between a terminal for generating an electromagnetic field and a transponder, the terminal and the transponder each including an oscillating circuit forming an antenna, and said transponder including an electronic circuit adapted to drain and give back power provided by the electromagnetic field from the terminal, the oscillating circuits of the transponder and of the terminal being capable of transmitting radio-electric signals of determined frequency, the method including causing a detuning of at least one of the oscillating circuits with respect to the determined frequency, so as to decrease a coupling coefficient between the oscillating circuits while maintaining communication between the transponder and the terminal, when the transponder and the terminal are very close to each other.
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Accused Products
Abstract
A method and a system of data transmission between a terminal for generating an electromagnetic field and a transponder, the terminal and the transponder each including an oscillating circuit forming an antenna, and the transponder including an electronic circuit adapted to absorbing and giving back power provided by the terminal field, the oscillating circuits of the transponder and of the terminal being capable of transmitting radio-electric signals of determined frequency, this method including causing a detuning of at least one of the oscillating circuits with respect to the determined frequency when the transponder and the terminal are very close to each other.
300 Citations
13 Claims
- 1. A method of data transmission between a terminal for generating an electromagnetic field and a transponder, the terminal and the transponder each including an oscillating circuit forming an antenna, and said transponder including an electronic circuit adapted to drain and give back power provided by the electromagnetic field from the terminal, the oscillating circuits of the transponder and of the terminal being capable of transmitting radio-electric signals of determined frequency, the method including causing a detuning of at least one of the oscillating circuits with respect to the determined frequency, so as to decrease a coupling coefficient between the oscillating circuits while maintaining communication between the transponder and the terminal, when the transponder and the terminal are very close to each other.
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8. A method for communication between a terminal and a remote transponder that receives operating power from the terminal, the method comprising acts of:
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generating with the terminal an electromagnetic field;
determining a distance between the terminal and the remote transponder;
detuning an oscillating circuit of one of the terminal and the transponder, so as to decrease a coupling coefficient between the transponder and the terminal in a detuned state, in response to the distance between the terminal and the transponder being less than a predetermined value;
wherein the transponder still receives operating power from the terminal in the detuned state. - View Dependent Claims (9, 10, 11, 12, 13)
measuring the phase of the current; and
varying a capacitance of the oscillating circuit so as to achieve a desired phase of the current.
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11. The method of claim 10, wherein measuring the phase of the current includes acts of:
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measuring the current with a current-measuring device to provide a measured current;
comparing a phase of the measured current with a phase of a reference signal using a phase comparator; and
determining the phase of the current based on the comparing act.
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12. The method of claim 8, wherein determining the distance includes acts of:
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measuring a first voltage when the oscillating circuit is in a tuned mode;
measuring a second voltage when the oscillating circuit is in the detuned mode;
comparing the first and second voltages to provide a comparison bit; and
determining the distance between the terminal and the transponder, relative to a critical coupling point, based on a value of the comparison bit.
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13. The method of claim 8, further comprising an act of varying a rate of data transmission between the terminal and the remote transponder based at least in part on the distance between the terminal and the remote transponder.
Specification