US 5,847,662 AGranted

Radio card communication apparatus

AssigneeKabushiki Kaisha Toshiba

InventorsTsuneshi Yokota, Tetsuo Saitoh, Seiji Ohura, Takanobu Ishibashi, Hiroyasu Uchida

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Abstract

A read request signal containing a command, an address, etc. is subjected to two-phase modulation with the first carrier of a first frequency and the resultant signal is then transmitted to a radio card. After the transmission of the read request signal, the first carrier is kept transmitted to the radio card. Upon reception of the read request signal, the radio card generates a power supply voltage and an operation clock and sends response data to the read request signal to a radio card reader/writer. Unlike in the prior art, therefore, the reception of power or the reception/transmission of data need not be performed intermittently so that a large amount of data can be received or transmitted continuously at a high speed.

Claims2

Dependent claims

A radio card communication apparatus having a transmitting antenna and a receiving antenna for radio communication with a portable radio card having a radio communication function, comprising:

modulation means for modulating a modulated signal, obtained by modulating a command signal including a command and data, with a first carrier of a predetermined frequency to provide a first modulated carrier signal;
transmission means for transmitting said first carrier which is unmodulated from said transmitting antenna to said radio card in order to supply power to said radio card, transmitting said first modulated carrier signal from said transmitting antenna to said radio card and maintaining transmission of said unmodulated first carrier to said radio card in order to supply power thereto after transmission of said first modulated carrier signal;
reception means for receiving a response signal in association with said command signal, modulated with a second carrier, from said radio card via said receiving antenna, comprising
a first tuning circuit including a first coil serving as said receiving antenna, a capacitor and a resistor, the capacitor and resistor being connected in parallel to said first coil, for tuning to said second carrier frequency;
a second tuning circuit including a capacitor and a second coil connected in series, and connected in parallel to said first tuning circuit, for tuning to said first carrier thereby to attenuate a first carrier component contained in said response signal;
a differential amplifier having a non-inverting input terminal connected to one end of said first tuning circuit;
and
a third coil having one end connected to an other end of said first tuning circuit and an other end connected to an inverting input terminal of said differential amplifier, said third coil being closely coupled to said second coil, and generating a signal which corresponds to the first carrier component contained in the response signal received by said reception means, whereby the first carrier component contained in the response signal received is subtracted from said second carrier before being amplified by the differential amplifier;
and
means for causing said transmission means to stop transmitting said first carrier when reception of said response signal by said reception means is completed.

7 more elements

A radio card communication apparatus having a transmitting antenna and a receiving antenna coil for radio communication with a portable radio card having a radio communication function, comprising:

modulation means for modulating a first two-phase modulated signal, obtained by performing two-phase modulation on a read request, with a first carrier of a first predetermined frequency to provide a first modulated carrier signal;
transmission means for transmitting said first carrier which is unmodulated from said transmitting antenna to said radio card in order to supply power to said radio card, transmitting said first modulated carrier from said transmitting antenna to said radio card, and maintaining transmission of said unmodulated first carrier to said radio card in order to supply power thereto after transmission of said first modulated carrier signal;
reception means for receiving a second modulated carrier signal corresponding to said read request signal from said radio card via said receiving antenna coil, comprising
a first tuning circuit including a capacitor and resistor connected in parallel to said receiving antenna coil, for tuning to said second carrier frequency;
a second tuning circuit including a capacitor and a second coil connected in series, and connected in parallel to said first tuning circuit, for tuning to said first carrier thereby to attenuate said first carrier component contained in said response signal;
a differential amplifier having a non-inverting input terminal connected to one end of said first tuning circuit;
and
a third coil having one end connected to an other end of said first tuning circuit and an other end connected to an inverting input terminal of said differential amplifier, said third coil being closely coupled to said second coil, and generating a signal which corresponds to the first carrier component contained in the response signal received by the reception means, whereby said first carrier component contained in said response signal received is subtracted from said second carrier before being amplified by the differential amplifier;
demodulation means for generating said second carrier by frequency-dividing said first carrier and demodulating said received second demodulated carrier signal using said generated second carrier;
and
means for stopping transmission of said first carrier by said transmission means when reception of said second demodulated carrier signal by said reception means is completed.

8 more elements

Dependencies are inferred from the claim text.