| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an IC card communication system that can prevent a reader/writer from delaying in recognizing that an IC card does not exist in a magnetic field, even if the transmission of an execution command from the reader/writer to the IC card is not carried out for a long time. <P>SOLUTION: When the execution command is not transmitted, the reader/writer 1 sends an invalid command of an I-block frame to the IC card 3 to produce a command error. When receiving from the IC card 3 an error response of an I-block frame to the invalid command, the reader/writer recognizes that the IC card 3 exists within a magnetic field 2. When receiving from the IC card 3 no response to the invalid command, it recognizes that the IC card 3 does not exist in the magnetic field 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
