Signal-powered frequency-dividing transponder
First Claim
1. A batteryless, portable frequency divider, comprisinga first resonant circuit including an inductance and a capacitance that is resonant at a first frequency for receiving electromagnetic radiation at a first frequency;
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wherein one of the resonant circuits is a series resonant circuit and the other of the resonant circuits is a parallel resonant circuit;
wherein the one resonant circuit is connected directly across the other resonant circuit; and
wherein the frequency divider includes an element for causing the second resonant circuit to transmit electromagnetic radiation at the second frequency in response to variations in energy in the first resonant circuit'"'"'s resulting from the first resonant circuit receiving electromagnetic radiation at the first frequency.
1 Assignment
0 Petitions
Accused Products
Abstract
A batteryless, portable frequency divider, such as used in presence detection systems for article surveillance or as used for article-location determination, includes a series LC resonant circuit connected directed across a parallel LC resonant circuit. One circuit is resonant at a first frequency and the other circuit is resonant at a second frequency that is a plural-integer-divided quotient of the first frequency. In one class of embodiments, either or both of the series and parallel resonant circuits includes a variable capacitance element, such as a varactor, in which the capacitance varies in accordance with the voltage across the variable capacitance element. The variation of the capacitance of the variable capacitance element in response to variations in energy in the higher-frequency resonant circuit resulting from receipt electromagnetic radiation at the first frequency causes the lower-frequency resonant circuit to transmit electromagnetic radiation at the second frequency. In another class of embodiments, the parallel circuit is resonant at the higher first frequency and the series circuit is resonant at the frequency-divided second frequency; the frequency divider includes a three-terminal semiconductor switching device having a control terminal, a reference terminal, and a controlled terminal, which is connected directly across both resonant circuits and between the inductance and the capacitance of the series resonant circuit and which switches on and off in response to variations in energy in the parallel resonant circuit resulting from the parallel resonant circuit receiving electromagnetic radiation at the first frequency to cause the series resonant circuit to transmit electromagnetic radiation at the second frequency.
35 Citations
20 Claims
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1. A batteryless, portable frequency divider, comprising
a first resonant circuit including an inductance and a capacitance that is resonant at a first frequency for receiving electromagnetic radiation at a first frequency; - and
a second resonant circuit including an inductance and a capacitance that is resonant at a second frequency that is 1/n the first frequency for transmitting electromagnetic energy at the second frequency, wherein "n" is an integer greater than one; wherein one of the resonant circuits is a series resonant circuit and the other of the resonant circuits is a parallel resonant circuit; wherein the one resonant circuit is connected directly across the other resonant circuit; and wherein the frequency divider includes an element for causing the second resonant circuit to transmit electromagnetic radiation at the second frequency in response to variations in energy in the first resonant circuit'"'"'s resulting from the first resonant circuit receiving electromagnetic radiation at the first frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A tag for attachment to an article to be detected within a surveillance zone of an electronic article surveillance system, comprising
a frequency-dividing transponder for detecting electromagnetic radiation of a first predetermined frequency and responding to said detection by transmitting electromagnetic radiation of a second predetermined frequency that is a plural-integer-divided quotient of the first predetermined frequency; -
a container for housing the transponder and means for use in attaching the container to the article to be detected; wherein the transponder comprises a first resonant circuit including an inductance and a capacitance that is resonant at a first frequency for receiving electromagnetic radiation at a first frequency; and a second resonant circuit including an inductance and a capacitance that is resonant at a second frequency that is 1/n the first frequency for transmitting electromagnetic energy at the second frequency, wherein "n" is an integer greater than one; wherein one of the resonant circuits is a series resonant circuit and the other of the resonant circuits is a parallel resonant circuit; wherein the one resonant circuit is connected directly across the other resonant circuit; and wherein the frequency-dividing transponder includes an element that is responsive to variations in energy in the first resonant circuit resulting from the first resonant circuit'"'"'s receiving electromagnetic radiation at the first frequency for causing the second resonant circuit to transmit electromagnetic radiation at the second frequency. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A tag for attachment to a buried article to enable the buried article to be located by detecting the presence of said tag, comprising
a frequency-dividing transponder for detecting electromagnetic radiation of a first predetermined frequency and responding to said detection by transmitting electromagnetic radiation of a second predetermined frequency that is a plural-integer-divided quotient of the first predetermined frequency; - and
a sealed container housing the transponder to protect the transponder from moisture; wherein the transponder comprises a first resonant circuit including an inductance and a capacitance that is resonant at a first frequency for receiving electromagnetic radiation at a first frequency; and a second resonant circuit including an inductance and a capacitance that is resonant at a second frequency that is 1/n the first frequency for transmitting electromagnetic energy at the second frequency, wherein "n" is an integer greater than one; wherein one of the resonant circuits is a series resonant circuit and the other of the resonant circuits is a parallel resonant circuit; wherein the one resonant circuit is connected directly across the other resonant circuit; and wherein the frequency-dividing transponder includes an element that is responsive to variations in energy in the first resonant circuit resulting from the first resonant circuit'"'"'s receiving electromagnetic radiation at the first frequency for causing the second resonant circuit to transmit electromagnetic radiation at the second frequency. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification