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1. 发明授权

US5418353A Non-contact, electromagnetically coupled transmission and receiving system for IC cards 失效
标题翻译：用于IC卡的非接触式，电磁耦合传输和接收系统
公开(公告)号：US5418353A
公开(公告)日：1995-05-23
申请号：US325643
申请日：1994-10-19
申请人： Yosuke Katayama , Wasao Takasugi , Toshiharu Ieki , Takashi Takeuchi
发明人： Yosuke Katayama , Wasao Takasugi , Toshiharu Ieki , Takashi Takeuchi
IPC分类号： G06K7/00 , G06K19/07 , G06K5/00
CPC分类号： G06K19/0723 , G06K7/0008
摘要： A non-contact IC card communication in which power consumption of a driver of a reader/writer is reduced and the size of a power supply circuit for operating the driver is made small. The driver has a low output impedance. A current detecting circuit including a detecting coil magnetically coupled with a transceiver coil of the reader/writer through a magnetic coiling element and a resistor detects a current which flows through the transceiver coil. A voltage drop to be detected is small and is approximately constant for a variation of the transceiver coil current. When data is read from an IC card, a load of the driver is changed. The driver drives the transceiver coil in a constant voltage fashion even if a current flowing through the transceiver coil changes due to the change in load. Input voltages of a rectifying/smoothing circuit and a regulator in the IC card become approximately constant. As a result, the amplitude of a high frequency output voltage of the driver can be made small. Also, a high frequency signal current sent from a reader/writer is subjected to double modulation including amplitude modulation by card data and modulation by second information, such as information indicative of the abnormality of an IC card, in synchronism with a timing at which data transmission between the reader/writer and the card is made, and the second information is extracted by the reader/writer.
摘要翻译：读取器/写入器的驱动器的功耗减小并且用于操作驱动器的电源电路的尺寸变小的非接触IC卡通信。驱动器具有低输出阻抗。电流检测电路包括通过磁性卷绕元件与读取器/写入器的收发器线圈磁耦合的检测线圈和电阻器，检测流过收发器线圈的电流。要检测的电压降很小，并且对于收发器线圈电流的变化大致恒定。当从IC卡读取数据时，改变驱动器的负载。即使流经收发器线圈的电流由于负载变化而变化，驱动器以恒定电压方式驱动收发器线圈。 IC卡中的整流/平滑电路和稳压器的输入电压变为近似恒定。结果，能够使驱动器的高频输出电压的振幅变小。此外，从读取器/写入器发送的高频信号电流与数据的定时同步地进行包括由卡数据的幅度调制和第二信息的调制（例如表示IC卡的异常的信息）的双调制进行读写器与卡之间的传输，读/写器提取第二信息。

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