非接触icカードのデータアクセス装置

Data access device for non-contact ic card

Abstract

(57)【要約】 【課題】 非接触ICカードから送信されたデータに直 流成分のノイズが重畳すると、受信したデータの波形全 体が正側または負側に移動するが、受信したデータの波 形全体がスレッショールドSから逸脱すると、コンパレ ータ35がパルス波形を生成することができなくなる課 題があった。 【解決手段】 閾値信号生成手段により整流手段から出 力された正の整流信号と負の整流信号を互いに加算し、 その加算結果を閾値信号として出力する。
PROBLEM TO BE SOLVED: To precisely read out transmission data from a non-contact IC card by mutually adding positive and negative rectified signals and outputting the added result as a threshold signal. SOLUTION: An inputted carrier (a) is turned to positive and negative rectified signals (b) through a rectifying means consisting of a preamplifier 51, an operational amplifier 53, diodes 57, 59, and resistors 52, 54, 58, 60. Then, the positive rectified signal is averaged through a threshold signal generating means consisting of a resistor 61 and a capacitor 62 and the negative rectified signal is averaged through a threshold signal generating means consisting of a resistor 64 and a capacitor 65. The positive and negative rectified signals are mutually added through a threshold signal generating means consisting of resistors 63, 66. A comparator 56 to be a comparing means compares an wave (e) to be a threshod with the carrier (a) and outputs a waveform corresponding to a compared result. Thereby, the comparator 56 outputs an accurate digital signal to a demodulation circuit. COPYRIGHT: (C)1997,JPO

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Cited By (2)

    Publication numberPublication dateAssigneeTitle
    JP-2002099878-AApril 05, 2002Hitachi Kokusai Electric Inc, 株式会社日立国際電気非接触icカード用リーダ/ライタ装置
    JP-2008250655-AOctober 16, 2008Renesas Technology Corp, 株式会社ルネサステクノロジSemiconductor integrated circuit