Non-contact IC card and system for performing data communication
First Claim
1. An IC card which transmits and receives desired data sequences in non-contact transmission between itself and a predetermined processor, said IC card comprising:
- an antenna for receiving a transmission signal from the processor;
a demodulation circuit for retrieving a transmitted data sequence sent from the processor by demodulating the transmission signal received by said antenna; and
a modulation circuit for forming a response signal by modulating a main carrier having the same frequency as a main carrier of the transmission signal with a response data sequence corresponding to the transmitted data sequence in such a manner that a sideband of the response signal does not overlap a sideband of the transmission signal along the frequency axis, said modulation circuit sending out the response signal from said antenna.
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Accused Products
Abstract
An IC card, an IC card processor, and an IC card system are simply arranged to perform full-duplex data exchange efficiently using a frequency band in such a manner that a transmission signal sent from the IC card processor is received by an antenna, the transmission signal is demodulated, and a response signal to be sent from the antenna is formed by modulating a main carrier having the same frequency as a main carrier of the transmission signal with a response data sequence in such a manner that a sideband of the response signal does not overlap a sideband of the transmission signal along the frequency axis.
29 Citations
17 Claims
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1. An IC card which transmits and receives desired data sequences in non-contact transmission between itself and a predetermined processor, said IC card comprising:
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an antenna for receiving a transmission signal from the processor;
a demodulation circuit for retrieving a transmitted data sequence sent from the processor by demodulating the transmission signal received by said antenna; and
a modulation circuit for forming a response signal by modulating a main carrier having the same frequency as a main carrier of the transmission signal with a response data sequence corresponding to the transmitted data sequence in such a manner that a sideband of the response signal does not overlap a sideband of the transmission signal along the frequency axis, said modulation circuit sending out the response signal from said antenna. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
a first demodulator for demodulating the transmission signal to obtain a demodulated signal; and
a second demodulator for demodulating the demodulated signal to retrieve the transmitted data sequence.
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3. An IC card according to claim 1, wherein said modulation circuit forms the response signal by modulating a subcarrier having a predetermined frequency with the response data sequence, and forms the response signal by modulating the main carrier with the modulated subcarrier.
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4. An IC card according to claim 1, wherein the response data sequence is formed of a plurality of data sequences, and
wherein said modulation circuit multiplexes the plurality of data sequences and thereafter forms the response signal. -
5. An IC card according to claim 4, wherein said modulation circuit forms the response signal by frequency-multiplexing the plurality of data sequences.
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6. An IC card according to claim 1, wherein the response data sequence is coded by a coding method of suppressing a lower band.
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7. An IC card according to claim 1, wherein said modulation circuit sends out the response signal from said antenna by changing the load impedance of said antenna.
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8. An IC card according to claim 1, wherein said demodulation circuit and said modulation circuit are operated by electric power of the transmission signal.
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9. An IC card processor which transmits and receives desired data sequences in non-contact transmission between itself and an IC card, said IC card processor comprising:
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a demodulation circuit for retrieving a response data sequence sent from the IC card by demodulating a response signal sent from the IC card by wireless communication; and
a modulation circuit for forming a transmission signal by modulating a main carrier having the same frequency as a main carrier of the response signal with a transmitted data sequence urging sending out of the response data sequence in such a manner that a sideband does not overlap a sideband of the response signal along the frequency axis, said modulation circuit sending out the transmission signal from a predetermined antenna. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
a first demodulator for demodulating the response signal to obtain a demodulated signal; and
a second demodulator for demodulating the demodulated signal to retrieve the response data sequence.
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11. An IC card processor according to claim 9, wherein said modulation circuit forms the transmission signal by modulating a subcarrier having a predetermined frequency with the transmitted data sequence, and forms the transmission signal by modulating the main carrier with the modulated subcarrier.
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12. An IC card processor according to claim 9, wherein the transmitted data sequence is formed of a plurality of data sequences, and
wherein said modulation circuit multiplexes the plurality of data sequences and thereafter forms the transmission signal. -
13. An IC card processor according to claim 12, wherein said modulation circuit forms the transmission signal by frequency-multiplexing the plurality of data sequences.
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14. An IC card processor according to claim 9, wherein the transmitted data sequence is coded by a coding method of suppressing a lower band.
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15. An IC card processor according to claim 9, wherein said modulation circuit forms the transmission signal so that the electric power of the main carrier is 99% or more of the total electric power.
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16. An IC card processor according to claim 9, wherein the modulation circuit forms the transmission signal by a depth of modulation smaller than 1.
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17. An IC card system in which desired data sequences are transmitted and received in a non-contact manner between an IC card and an IC card processor, said IC card comprising:
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an antenna for receiving a transmission signal from the IC card processor;
a demodulation circuit for retrieving a transmitted data sequence sent from said IC card processor by demodulating the transmission signal received by said antenna; and
a modulation circuit for forming a response signal by modulating a main carrier having the same frequency as a main carrier of the transmission signal with a response data sequence corresponding to the transmitted data sequence in such a manner that a sideband does not overlap a sideband of the transmission signal along the frequency axis, the modulation circuit sending out the response signal from said antenna, said IC card processor comprising;
a demodulation circuit for retrieving the response data sequence sent from the IC card by demodulating the response signal sent from the IC card by wireless communication; and
a modulation circuit for forming the transmission signal by modulating the main carrier with the transmitted data sequence, said modulation circuit sending out the transmission signal from a predetermined antenna.
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Specification