Method and system of communication for a non-contact IC card

Claim 2

A non-contact, electromagnetically coupled communication system comprising a first communicating unit (1) and a second communicating unit (2) coupled electro­magnetically in non-contact fashion for communicating signals, wherein said first communicating unit comprises a first electromagnetic transducing circuit (14) for said electromagnetic coupling and a carrier wave generating circuit (5) connected to said first electromagnetic transducing circuit for generating a carrier wave for transmitting a signal to said second communicating unit, said second communicating unit comprising a second electro­magnetic transducing circuit (15) for said electro­magnetic coupling and a circuit connected to said second electromagnetic transducing circuit for varying the impedance of said second electromagnetic transducing circuit, said first communicating unit receiving a signal sent from said second communicating unit by detecting a change in the frequency of said carrier wave.

Claim 3

A system according to Claim 1, wherein said first communicating unit comprises a data write-and-read unit and said second communicating unit comprises an IC card, said first and second electromagnetic transducing circuits each comprising a coil, said second electromagnetic transducing circuit including means (10) of creating a variation in said load impedance by grounding or opening the connection of said second transducing circuit.

Claim 4

A system according to Claim 2, wherein said first communicating unit comprises means (7) of comparing the output frequency of said first electromagnetic transducing circuit with a reference carrier frequency of said carrier generating circuit for the sake of detecting a variation in the carrier frequency.

Claim 5

A non-contact data communication system comprising an external unit (1) with the ability of communicating function for reading or writing data for a recording medium (2) with the ability of communicating function, and said recording medium which transacts signals with said external unit by being coupled electromagnetically in non-contact fashion and supplied with power from said external unit, wherein said external unit comprises a power supply circuit (3) which supplies power in the form of electromagnetic energy to said recording medium, a control signal receiving circuit (19) which receives a control signal for controlling the intensity of generation of said electromagnetic energy by being coupled with said recording medium, a control circuit (16) which controls the quantity of electromagnetic energy generation by said power supply circuit in response to a signal from said receiving circuit, a first electro­magnetic transducing circuit (14) for said electromagnetic coupling, and a carrier wave generation circuit (15) connected to said first electromagnetic transducing circuit for generating a carrier wave for transmitting a signal to said recording medium, and said recording medium comprises a transducing circuit (13) which converts electromagnetic energy received from said power supply circuit into electrical energy, a power circuit (18) which produces a d.c. power voltage from the electrical energy provided by said transducing circuit, a control signal generation circuit (18) which produces said control signal in response to a voltage of said power circuit, control signal output circuit (17) which is in electromagnetic coupling with said control signal receiving circuit for outputting said control signal, a second electromagnetic transducing circuit (15) for said electromagnetic coupling, and a circuit (10) connected to said second electromagnetic transducing circuit for varying the load impedance of said second electromagnetic transducing circuit in response to the transmitted signal, said external unit receiving a signal transmitted from said recording medium by detecting a variation in the frequency of said carrier wave and operat­ing on said control circuit of said external unit using said control signal to maintain the output voltage of said power circuit constant.

Claim 6

A non-contact data communication system comprising an external unit (1) with the ability of communicating function for reading or writing data for a recording medium (2) with the ability of communicating function, and said recording medium which transacts signals with said external unit by being coupled electromagnetically in non-contact fashion and supplied with power from said external unit, wherein said external unit comprises a power supply circuit (3) which supplies power in the form of electromagnetic energy to said recording medium, a control signal receiving circuit (19) which receives a control signal for controlling the intensity of generation of said electromagnetic energy by being coupled with said recording medium, a control circuit (16) which controls the quantity of electromagnetic energy generation by said power supply circuit in response to a signal from said receiving circuit, a first electro­magnetic transducing circuit (14) for said electromagnetic coupling, and a carrier wave generation circuit (15) connected to said first electromagnetic transducing circuit for generating a carrier wave for transmitting a signal to said recording medium, and said recording medium comprises a transducing circuit (13) which converts electromagnetic energy received from said power supply circuit into electrical energy, a power circuit (18) which produces a d.c. power voltage from the electrical energy provided by said transducing circuit, a control signal generation circuit (18) which produces said control signal in response to a voltage of said power circuit, control signal output circuit (17) which is in electromagnetic coupling with said control signal receiving circuit for outputting said control signal, a second electromagnetic transducing circuit (15) for said electromagnetic coupling, and a circuit (10) connected to said second electromagnetic transducing circuit for varying the load impedance of said second electromagnetic transducing circuit in response to the transmitted signal, said external unit receiving a signal transmitted from said recording medium by detecting a variation in the frequency of said carrier wave and operat­ing on said control circuit of said external unit using said control signal to maintain the output voltage of said power circuit constant.

Claim 7

A system according to Claim 4 further comprising a voltage stabilizing circuit (21), which maintains a constant output voltage of said power circuit, provided between said power circuit and said control signal generation circuit of said recording medium.

Claim 8

A non-contact data communication system comprising an external unit (1) with the ability of communicating function of reading or writing data for a recording medium (2) with the ability of communicating function, and said recording medium which transacts signals with said external unit by being coupled electromagnetically in non-contact fashion with said external unit and supplied with power from said external unit, wherein said external unit comprises a power supply circuit (3) which supplies power in the form of electromagnetic energy to said recording medium, a control signal receiving circuit (19) which receives a control signal for controlling the intensity of generation of said electromagnetic energy by being coupled with said recording medium, and a control circuit (6) which controls the quantity of electromagnetic energy generation by said power supply circuit in response to a signal from said receiving circuit, and said recording medium comprises an electromagnetic transducing circuit (13) which converts electromagnetic energy received from said power supply circuit into electrical energy, a power circuit (8) which produces a d.c. power voltage from the electrical energy provided by said transducing circuit, a control signal generation circuit (18) which produces said control signal in response to the voltage of said power circuit, and a control signal output circuit (17) which outputs said control signal by being coupled electromagnetically with said control signal receiving circuit, at least said control signal generation circuit being an integrated circuit operating to control said control circuit of said external unit using said control signal so that the output voltage of said power circuit is maintained constant.

Claim 9

A non-contact data communication system comprising an external unit (1) with the ability of communicating function of reading or writing data for a recording medium (2) with the ability of communicating function, and said recording medium which transacts signals with said external unit by being coupled electromagnetically in non-contact fashion with said external unit and supplied with power from said external unit, wherein said external unit comprises a power supply circuit (3) which supplies power in the form of electromagnetic energy to said recording medium, a control signal receiving circuit (19) which receives a control signal for controlling the intensity of generation of said electromagnetic energy by being coupled with said recording medium, and a control circuit (6) which controls the quantity of electromagnetic energy generation by said power supply circuit in response to a signal from said receiving circuit, and said recording medium comprises an electromagnetic transducing circuit (13) which converts electromagnetic energy received from said power supply circuit into electrical energy, a power circuit (8) which produces a d.c. power voltage from the electrical energy provided by said transducing circuit, a control signal generation circuit (18) which produces said control signal in response to the voltage of said power circuit, and a control signal output circuit (17) which outputs said control signal by being coupled electromagnetically with said control signal receiving circuit, at least said control signal generation circuit being an integrated circuit operating to control said control circuit of said external unit using said control signal so that the output voltage of said power circuit is maintained constant.

Claim 10

A system according to Claim 6 further comprising a voltage stabilizing circuit (21) which controls said power circuit to produce a constant output voltage and supplies power to the whole circuit of said recording medium, and means of supplying said output voltage to said control signal generating circuit so that said control signal generating circuit produces a control signal in response to said output voltage of said voltage stabilizing circuit.

Claim 11

A system according to Claim 6, wherein said control signal generating circuit comprises a voltage detecting circuit (18) for detecting a voltage of said power circuit and produces said control signal in response to the voltage detected by said voltage detecting circuit.

Claim 12

A system according to Claim 8, wherein said external unit comprises an IC card reader/writer, said recording medium comprises an IC card, said electromagnetic field generation circuit comprises an oscillation circuit (4) and a coil (12), said control signal output circuit comprises a coil, and said control signal generating circuit (21) comprises a voltage-controlled oscillation circuit and a voltage detecting circuit (18) for detecting a voltage of said voltage stabilizing circuit, said voltage detecting circuit producing a control voltage for said voltage-controlled oscillation circuit.

Claim 13

A functional recording medium (2) which is coupled electromagnetically in non-contact fashion with an external unit (1), which implements data reading or writing for said recording medium, and adapted to transact signals with said external unit by being supplied with power from said external unit, said recording medium comprising a data processing circuit (11), an electro­magnetic transducing coil (15) used for the electromagnetic coupling with said external unit and adapted to transmit an external signal to said data processing circuit, and a signal modulating circuit (10) which is connected to said electromagnetic transducing circuit and adapted to vary the impedance of said electromagnetic transducing circuit in response to a data signal sent from said data processing circuit, said coil, when being coupled electromagnetically with an electromagnetic transducing coil (14) of said external unit, enabling said external unit to reproduce a transmitted signal in the form of a variation in the frequency of a carrier wave supplied by said external unit on the basis of interaction between said carrier wave and said impedance variation.

Claim 14

A functional recording medium (2) which is coupled electromagnetically in non-contact fashion with an external unit (1), which implements data reading or writing for said recording medium, and adapted to transact signals with said external unit by being supplied with power from said external unit, said recording medium comprising a data processing circuit (11), an electro­magnetic transducing coil (15) used for the electromagnetic coupling with said external unit and adapted to transmit an external signal to said data processing circuit, and a signal modulating circuit (10) which is connected to said electromagnetic transducing circuit and adapted to vary the impedance of said electromagnetic transducing circuit in response to a data signal sent from said data processing circuit, said coil, when being coupled electromagnetically with an electromagnetic transducing coil (14) of said external unit, enabling said external unit to reproduce a transmitted signal in the form of a variation in the frequency of a carrier wave supplied by said external unit on the basis of interaction between said carrier wave and said impedance variation.