| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a blockage signal transmitter capable of preventing erroneous detection of a tag by limiting a spatial area where a seizing signal transmitted by an LF transmitter can be received within an arbitrary area. <P>SOLUTION: An LF transmitter 102a transmits a seizing signal 1401 to a tag at a cycle ct. A blockage signal transmitter 151a independently operates without being linked with the LF transmitter 102a to detect the seizing signal transmitted by the LF transmitter 102a, calculates a transition time st of the seizing signal 1401 and transmits a blockage signal (1411, 1412 and the like) at a cycle it1 shorter than st to thereby limit a spatial range where the tag can receive the seizing signal 1401. The transition time lt1 of the blockage signal has at least a signal length longer than a signal length (equivalent to n bit) in which the tag can perform error correction. <P>COPYRIGHT: (C)2013,JPO&INPIT |
