Non-contact IC card system and non-contact IC card
First Claim
1. A non-contact IC card system comprising:
- a reader/writer and a non-contact IC card, wherein at least one of said reader/writer and said non-contact IC card includes;
an AM demodulating circuit for converting a reception signal being a carrier AM-modulated by transmission data into a binary signal by comparing said reception signal with a reference value and further for detecting said transmission data by comparing a pulse width of the converted binary signal with a width of a reference pulse feedbacked to vary in accordance with a variation of said pulse width of the converted binary signal.
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Accused Products
Abstract
A non-contact IC card system capable of improving the data transmission rate and communication range without considerably enlarging the frequency band of a signal to be put to use. An AM-modulated signal (1F) from a reader writer (200) is received by a resonance circuit (6) of an IC card (100), and an IC card driving power source is produced therefrom in a rectifying section (8). In addition, it is demodulated in an AM demodulating circuit (10) and decoded in a decoder (13), thereby presenting reception data (10). On the other hand, when data (1J) is transmitted from the IC card (100), a characteristic of a regulator (9) for stabilizing an operating voltage of the resonance circuit (6) is altered on the basis of a signal encoded in an encoder (11) so that the signal is transmitted as an AM-modulated signal (1P) to the reader writer (200).
34 Citations
4 Claims
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1. A non-contact IC card system comprising:
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a reader/writer and a non-contact IC card, wherein at least one of said reader/writer and said non-contact IC card includes;
an AM demodulating circuit for converting a reception signal being a carrier AM-modulated by transmission data into a binary signal by comparing said reception signal with a reference value and further for detecting said transmission data by comparing a pulse width of the converted binary signal with a width of a reference pulse feedbacked to vary in accordance with a variation of said pulse width of the converted binary signal.
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2. A non-contact IC card system comprising:
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a reader/writer and a non-contact IC card, wherein at least one of said reader/writer and said non-contact IC card includes;
a filter for converting a reception signal including a plurality of carriers different in frequency from each other into a binary signal by comparing said reception signal with a reference value and further for extracting a carrier with a desired frequency by comparing a pulse width of the converted binary signal with a width of a reference pulse feedbacked to vary in accordance with a variation of said pulse width of the converted binary signal.
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3. A non-contact IC card which receives power supply from a reader/writer and conducts data transmission/reception to/from said reader/writer, comprising:
an AM demodulating circuit for converting a reception signal being a carrier AM-modulated by transmission data into a binary signal by comparing said reception signal with a reference value and further for detecting said transmission data by comparing a pulse width of the converted binary signal with a width of a reference pulse feedbacked to vary in accordance with a variation of said pulse width of the converted binary signal.
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4. A non-contact IC card which receives power supply from a reader/writer and conducts data transmission/reception to/from the reader/writer, comprising:
a filter for converting a reception signal including a plurality of carriers different in frequency from each other into a binary signal by comparing said reception signal with a reference value and further for extracting a carrier with a desired frequency by comparing a pulse width of the converted binary signal with a width of a reference pulse feedbacked to vary in accordance with a variation of said pulse width of the converted binary signal.
Specification