Importance

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Abstract

An IC card device capable of transmitting identification data to an inquiring unit without involving interference even when a plurality of IC card devices stay in the vicinity of the inquiring unit over a certain time. As the IC card device approaches the inquiring unit, the field intensity of a signal received by a receiver circuit incorporated in the IC card device increases. When it is determined that the field intensity exceeds a preset threshold level, a reception level determination circuit reads out identification data from a memory. A transmitter circuit transmits repeatedly the identification data signal to the inquiring unit. When the number of times the identification data is transmitted reaches a preset number, a counter stops the transmitting operation of the transmitter circuit. When it is determined by a reception level determination circuit that the field intensity exceeds the preset threshold value, a timer causes the receiver circuit to stop reception of the signal transmitted from the inquiring unit for a predetermined period.

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First Claim