Proximity detecting apparatus
First Claim
1. A remotely powered batteryless portable device having circuitry for storing and transmitting coded information comprising:
- a memory in which coded information is stored;
electromagnetic coupling means for receiving electromagnetic radiation of a first predetermined frequency;
power means connected to said first coupling means for deriving power from the received signal for use by the circuitry in said portable device;
circuit means, connected to said first coupling means and responsive to a received signal of said first predetermined frequency, for reading said coded information from said memory;
means for generating a carrier signal of a second predetermined frequency;
modulating means for modulating said carrier signal with the coded information read from said memory;
electrostatic coupling means, connected to the output of said modulating means, for transmitting the modulated carrier signal via an electric field; and
further means, connected to said output of said modulating means, for simultaneously causing said modulated carrier signal to be electromagnetically transmitted.
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Accused Products
Abstract
A proximity detection system which combines the advantages of an electrostatic (electric) field coupling mechanism with those of an electromagnetic coupling mechanism in order to overcome the disadvantages of the respective individual coupling mechanisms. The system includes a coded tag which is excited with an induction field, i.e., by using an electromagnetic coupling mechanism as has been done in the past in such proximity identification systems, but which transmits stored data back to the receiver using both an electric field coupling mechanism and an electromagnetic field coupling mechanism. The receiver, in turn, is provided with a novel preamplifier circuit arrangement, so that it can simultaneously receive signals via either or both of these coupling mechanisms.
234 Citations
25 Claims
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1. A remotely powered batteryless portable device having circuitry for storing and transmitting coded information comprising:
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a memory in which coded information is stored; electromagnetic coupling means for receiving electromagnetic radiation of a first predetermined frequency; power means connected to said first coupling means for deriving power from the received signal for use by the circuitry in said portable device; circuit means, connected to said first coupling means and responsive to a received signal of said first predetermined frequency, for reading said coded information from said memory; means for generating a carrier signal of a second predetermined frequency; modulating means for modulating said carrier signal with the coded information read from said memory; electrostatic coupling means, connected to the output of said modulating means, for transmitting the modulated carrier signal via an electric field; and further means, connected to said output of said modulating means, for simultaneously causing said modulated carrier signal to be electromagnetically transmitted. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification