Automatic adjusting responder with no self-contained power supply
First Claim
1. A responder for communicating with an interrogator by an electromagnetic wave in a non-contact IC card communication system comprising:
- a resonance circuit (1, 13, 26, 32) including an antenna (11, 25, 31) receiving the electromagnetic wave from said interrogator and switching means (SQ, TQ) for switching a resonance frequency of the resonance circuit; and
switching manner setting means (2) for setting a switching manner of said switching means (SQ, TQ), said switching manner setting means (2) including determining means (3) for sequentially switching said switching means (SQ, TQ) of said resonance circuit (1, 13, 26, 32) and detecting an output voltage or output current of said resonance circuit (1, 13, 26, 32) in each switching manner and, in accordance with a detection result, obtaining a suitable switching manner of said switching means (SQ, TQ) producing a desired output voltage or output current, said determining means (3) including reference voltage generating means (6, 19, 33) for receiving the output voltage of said resonance circuit (1, 13, 26, 32) to generate a prescribed reference voltage regardless of variation in the output voltage, output value measuring means (7, 20, 34) for measuring a magnitude of the output voltage of said resonance circuit (1, 13, 26, 32) in each switching manner by using the reference voltage generated in said reference voltage generating means (6, 19, 33) as a reference and outputting each measurement result as an output value, output value storing means (8, 18) for storing each output value output from said output value measuring means (7, 20, 34) corresponding to each switching manner of said switching means (SQ, TQ), and manner determining means (9, 17) for determining as a suitable switching manner a switching manner corresponding to a largest output value read from said output value storing means (8, 18); and
switching manner storing means (4, 18) for storing the suitable switching manner obtained by said determining means (3) wherein said responder is formed to receive the electromagnetic wave from the interrogator as a power source.
1 Assignment
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Accused Products
Abstract
In a non-contact IC card, a driving portion 5 sequentially switches a resonance frequency of a resonance circuit 1. A reference voltage generating portion 6 receives an output voltage of resonance circuit 1 for outputting a prescribed reference voltage. An output value measuring portion 7 measures a magnitude of the output voltage of resonance circuit 1 at each resonance frequency using the reference voltage as a reference. An output value storing portion 8 stores a measurement value (an output value). A manner determining portion 9 selects the largest one of the output values stored in output value storing portion 8, and determines a switching manner corresponding thereto as a suitable switching manner. Thus, the suitable switching manner allowing the most efficient power supply can be achieved.
54 Citations
12 Claims
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1. A responder for communicating with an interrogator by an electromagnetic wave in a non-contact IC card communication system comprising:
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a resonance circuit (1, 13, 26, 32) including an antenna (11, 25, 31) receiving the electromagnetic wave from said interrogator and switching means (SQ, TQ) for switching a resonance frequency of the resonance circuit; and
switching manner setting means (2) for setting a switching manner of said switching means (SQ, TQ), said switching manner setting means (2) including determining means (3) for sequentially switching said switching means (SQ, TQ) of said resonance circuit (1, 13, 26, 32) and detecting an output voltage or output current of said resonance circuit (1, 13, 26, 32) in each switching manner and, in accordance with a detection result, obtaining a suitable switching manner of said switching means (SQ, TQ) producing a desired output voltage or output current, said determining means (3) including reference voltage generating means (6, 19, 33) for receiving the output voltage of said resonance circuit (1, 13, 26, 32) to generate a prescribed reference voltage regardless of variation in the output voltage, output value measuring means (7, 20, 34) for measuring a magnitude of the output voltage of said resonance circuit (1, 13, 26, 32) in each switching manner by using the reference voltage generated in said reference voltage generating means (6, 19, 33) as a reference and outputting each measurement result as an output value, output value storing means (8, 18) for storing each output value output from said output value measuring means (7, 20, 34) corresponding to each switching manner of said switching means (SQ, TQ), and manner determining means (9, 17) for determining as a suitable switching manner a switching manner corresponding to a largest output value read from said output value storing means (8, 18); and
switching manner storing means (4, 18) for storing the suitable switching manner obtained by said determining means (3) wherein said responder is formed to receive the electromagnetic wave from the interrogator as a power source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
a capacitance of said variable capacitance circuit (C, SQ, TQ) can be switched by said switching means (SQ, TQ). -
3. The responder in the non-contact IC card communication system according to claim 1, wherein said resonance circuit (1, 13, 26, 32) further includes a condenser (C) connected in parallel to said antenna (11, 25, 31), and
an inductance of said antenna (11, 25, 31) can be switched by said switching means (SQ, TQ). -
4. The responder in the non-contact IC card communication system according to claim 1, wherein said switching means (SQ, TQ) includes a plurality of transistors (SQ, TQ), and
said switching manner storing means (4, 18) stores a value that represents which one of said plurality of transistors (SQ, TQ) is rendered conductive. -
5. The responder in the non-contact IC card communication system according to claim 1, wherein said resonance circuit (1, 13, 26, 32) is used at least for supplying operation power of said responder.
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6. The responder in the non-contact IC card communication system according to claim 1, wherein said resonance circuit (1, 13, 26, 32) is used at least for data communication with said interrogator.
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7. The non-contact IC card communication system according to claim 1, wherein said determining means (3) determines said suitable switching manner during manufacture of said responder.
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8. The responder in the non-contact IC card communication system according to claim 1, wherein said determining means (3) determines said suitable switching manner once in a prescribed period of time.
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9. The responder in the non-contact IC card communication system according to claim 8, wherein said prescribed period of time is between a previous determination time and a time when a prescribed amount of time has elapsed.
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10. The responder in the non-contact IC card communication system according to claim 8, wherein said prescribed period of time is between a previous determination date and a time when said responder is used a prescribed number of times.
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11. The responder in the non-contact IC card communication system according to claim 1, wherein said resonance circuit (1, 13, 26, 32) and said switching manner setting means (2) are formed as an integrated circuit chip.
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12. The responder of claim 1, wherein said output value measurement means (7, 20, 34) includes:
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threshold voltage generation means (R1-R4) for dividing said reference voltage to generate a plurality of threshold voltages; and
a comparator circuit (22a-22c) comparing each of said plurality of threshold voltages generated by said threshold voltage generation means (R1-R4) and a voltage output from said resonance circuit (1, 13, 26, 32) in a switching manner and outputting a signal indicative of a resultant comparison as said output value.
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Specification