Rfid tag, and system and method for detecting change of rfid tag environment

Abstract

Provided is an RFID tag suitable for detecting a change of the RFID tag environment in real time by a simple and low-cost system. The system and the method for detecting a change of the RFID tag environment are also provided. An RFID tag (2) is provided with an antenna (20), a wireless communication IC (21) for transmitting / receiving radio waves through the antenna (20), and an element (22A) of which characteristics change corresponding to a change of the physical quantity of the RFID tag environment. Gain of the antenna (20) changes due to a change of the characteristics of the element (22A). When the environment of the RFID tag (2) changes, gain of the antenna (20) is reduced or increased by the element (22A). Thus, the RFID tag (2) is brought into a state where answering waves (ANS) to interrogation waves (RQ) transmitted from a tag communication device (3) can be transmitted and into a state where such waves cannot be transmitted, and the change of the environment of the RFID tag (2) can be detected in real time, depending on whether the answering waves (ANS) are received or not.

Description

technical field [0001] The present invention relates to an RFID tag suitable for real-time detection of a situation change around an RFID (Radio Frequency Identification) tag, a situation change detection system around an RFID tag, and a detection method thereof. Background technique [0002] An RFID tag communication system is known that performs wireless communication between an RFID tag and a tag communication device via radio waves. In this RFID tag communication system, various schemes for transmitting the situation changes around the RFID tag to the tag communication device in real time have been studied, among which the method of using active type RFID tags is more common. [0003] However, since an active type RFID tag has a built-in power source such as a battery and requires peripheral circuits, the circuit structure is also complicated and expensive, and there is also a problem of battery life. [0004] If an active type RFID tag is used, changes in conditions ar...

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Problems solved by technology

[0007] However, if the resonance frequency of the antenna of the RFID tag (20) changes as in Patent Document 1, the same tag reader (26) may not be able to communicate with the RFID tag (20).

If it is impossible to communicate with the RFID tag (20), it is unclear whether the resonance frequency has changed. Therefore, in the technology of Patent Document 1, it is impossible to reliably detect changes in conditions around the RFID tag (20), specifically asset movement

[0008] Patent Document 2 discloses that, among a plurality of RFID tags in an area where communication is possible, by irradiating light or the like on the RFID tag to be communicated, it is possible to communicate only with the RFID tag to be communicated. technology, but does not disclose the technology for real-time detection of changes in conditions around the RFID tag

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