RFID reader
First Claim
1. An animal entry control system, the system comprising:
- a radio frequency identification (RFID) reader to register the presence and identification number of a transponder injected under the skin of an animal; and
a door mounted on a hinge and controlled by said RFID tag reader; and
wherein said RFID reader comprises a resonant circuit including a tuning circuit to tune a resonant frequency of the RFID reader to a resonant frequency of the transponder and to control a drive frequency of said RFID reader,wherein the resonant circuit comprises an inductive-capacitive (LC) resonant circuit and the tuning circuit includes a drive circuit to drive said LC resonant circuit to oscillate at said drive frequency;
wherein an effective capacitance of said LC resonant circuit is variable whilst said LC resonant circuit is being driven by said drive circuit to automatically tune a resonant frequency of said LC resonant circuit; and
wherein said RFID reader is automatically controlled by the tuning circuit to tune said RFID reader to substantially matchi) said resonant frequency of said LC resonant circuit of said RFID reader andii) said drive frequency of said drive circuit of said RFID reader toiii) said resonant frequency of said transponder,wherein said resonant circuit comprises at least two capacitive paths and a field-effect transistor (FET) configured to repeatedly switch on and off during a cycle of oscillation of said resonant circuit to vary a total effective capacitance associated with the at least two capacitive paths over said cycle of oscillation to match a resonance of said resonant circuit to a range of frequencies, and wherein said resonant frequency of said resonant circuit is dependent upon a duty cycle of the switching.
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Accused Products
Abstract
We describe an animal entry control system, for example for a cat flap, using RFID (radio frequency identification). The system comprises an RFID reader to register the presence and identification number of a transponder (15) injected under the skin of an animal; and a door (8) mounted on a hinge (10) and controlled by the RFID tag reader. The RFID reader comprises a resonant circuit including a tuning circuit to control the RFID reader such that a drive frequency of the RFID reader matches both a resonant frequency of the RFID reader and a resonant frequency of the transponder. Embodiments of the system are thus tolerant to a degree of detuning, for example from a metallic or magnetic material in the vicinity of the antenna.
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Citations
14 Claims
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1. An animal entry control system, the system comprising:
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a radio frequency identification (RFID) reader to register the presence and identification number of a transponder injected under the skin of an animal; and a door mounted on a hinge and controlled by said RFID tag reader; and wherein said RFID reader comprises a resonant circuit including a tuning circuit to tune a resonant frequency of the RFID reader to a resonant frequency of the transponder and to control a drive frequency of said RFID reader, wherein the resonant circuit comprises an inductive-capacitive (LC) resonant circuit and the tuning circuit includes a drive circuit to drive said LC resonant circuit to oscillate at said drive frequency;
wherein an effective capacitance of said LC resonant circuit is variable whilst said LC resonant circuit is being driven by said drive circuit to automatically tune a resonant frequency of said LC resonant circuit; andwherein said RFID reader is automatically controlled by the tuning circuit to tune said RFID reader to substantially match i) said resonant frequency of said LC resonant circuit of said RFID reader and ii) said drive frequency of said drive circuit of said RFID reader to iii) said resonant frequency of said transponder, wherein said resonant circuit comprises at least two capacitive paths and a field-effect transistor (FET) configured to repeatedly switch on and off during a cycle of oscillation of said resonant circuit to vary a total effective capacitance associated with the at least two capacitive paths over said cycle of oscillation to match a resonance of said resonant circuit to a range of frequencies, and wherein said resonant frequency of said resonant circuit is dependent upon a duty cycle of the switching. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An animal feeding control RFID system including
a radio frequency identification (RFID) reader to register the presence and identification number of a transponder injected under the skin of an animal; -
wherein said RFID reader comprises a resonant circuit including a tuning circuit to tune a resonant frequency of the RFID reader to a resonant frequency of the transponder and to control a drive frequency of said RFID reader; wherein the resonant circuit comprises an inductive-capacitive (LC) resonant circuit having a field-effect transistor connected in parallel with a capacitor and the tuning circuit includes a drive circuit to drive said LC resonant circuit to oscillate at said drive frequency; wherein an effective capacitance of said LC resonant circuit is configured to be varied by repeatedly switching said field-effect transistor during oscillation periods of said LC resonant circuit whilst said LC resonant circuit is being driven by said drive circuit to automatically tune a resonant frequency of said LC resonant circuit; and wherein said RFID reader is automatically controlled by the tuning circuit to tune said RFID reader to substantially match i) said resonant frequency of said LC resonant circuit of said RFID reader and ii) said drive frequency of said drive circuit of said RFID reader to iii) said resonant frequency of said transponder.
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13. A method of controlling animal access in an animal entry control system, the system comprising:
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a radio frequency identification (RFID) reader having a resonant circuit with a resonant frequency to register the presence and identification number of a transponder injected under the skin of an animal; and a door mounted on a hinge and controlled by said RFID tag reader;
the method comprising;
automatically controlling said RFID reader to tune the resonant frequency of the RFID reader to a resonant frequency of the transponder; andautomatically controlling a drive frequency of said RFID reader such that it matches both the resonant frequency of said RFID reader and a resonant frequency of said transponder, wherein controlling said RFID reader comprises repeatedly switching, during an oscillation period of the resonant circuit, a field-effect transistor that is connected in parallel with a capacitor to control an effective capacitance of the resonant circuit. - View Dependent Claims (14)
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Specification