| 摘要 |
<p>A non-contact type IC card system comprising a non-contact type IC card using an electromagnetic wave as a communication medium and not containing a battery therein, and a reading and writing (R/W) unit. To eliminate a problem that the level of a received signal varies depending upon the communication distance between the card and the R/W unit, a comparator 7 detects the received signal level of an antenna resonance circuit 4 for data transmission and reception, before a variable resistance device 8 alters the quality factor Q of the antenna resonance circuit 4, which results in adjusting the level of the received signal being inputted to a desirable value. <IMAGE></p> |
