| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce power consumption of a non-contact information storage device and to control a carrier sense and transmission interval of the non-contact information storage device by a reader/writer. <P>SOLUTION: In an information access system, an active non-contact information storage device 204 performs carrier sense of an RF signal of a first frequency f<SB>1</SB>in a predetermined period with a predetermined cycle (50 and 52). When performing carrier sense to detect the first frequency RF signal in a certain predetermined period, the active non-contact information storage device 204 operates so as to further receive an information request signal (54) and transmits a tag information signal 56 of a second frequency f2 for carrying information in an information transmission period with a tag information transmission cycle. The reader/writer 304 repeatedly transmits an information request signal 42 of the first frequency for carrying values of a carrier sense cycle and the tag information transmission cycle during an information request transmission period, and takes out tag information to collate the tag information with a tag information list LID upon receiving the tag information signal. Upon receiving the information request signal, the non-contact information storage device takes out the values of the carrier sense cycle and the tag information transmission cycle and sets the values in timers 274 and 275. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
