IDENTIFICATION METHOD FOR OVERLAPPED TAGS

摘要

Problem: To positively identify a plurality of tags even when they overlap each other or tags and metal plates overlap each other. Solutions: Tags (11 to 13) attached to articles each have an antenna coil (14) and an RFID element (16) connected to the antenna coil, and a plurality of resonance capacitors (19a to 19n) are parallel-connected with the antenna coil in parallel with each other. A plurality of switches (24a to 24n) connected respectively to the resonance capacitors electrically connect or disconnect the resonance capacitors to/from the antenna coil and the RFID element respectively, and the control circuit (25) controls for opening or closing the switches, thereby making it possible to change the resonance frequency of a resonance circuit consisting of the antenna coil and the resonance capacitors.