Piezo-Tuned RFID Tag Circuit for Motion-Selective Reading
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Solution Overview
Problem
Conventional RFID systems face challenges in distinguishing between moving and stationary RFID tags, leading to unintended readings of tags outside the intended area or of static merchandise.
Innovation Solution
The implementation of a piezo-based circuit in RFID tags that tunes the antenna's impedance and operation based on physical movement, using a piezo electric energy harvesting module to supply power and control the impedance tuned circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional RFID tags continuously respond to readers, then all tags are tracked, but stationary tags outside intended area are also read causing unintended readings
Solution Approach 1:
The RFID tag's antenna impedance is dynamically adjusted based on movement detection. When movement is detected, the antenna is tuned to a functional impedance that enables communication with readers. When no movement is detected, the antenna is detuned to a non-functional impedance that prevents reading. This dynamic switching resolves the contradiction by making the tag selectively responsive only when needed.
Solution Approach 2:
The patent changes the electrical parameter (impedance) of the antenna based on the movement state of the tag. By switching between different impedance values (functional vs. non-functional), the system controls whether the tag responds to reader signals, thereby eliminating unintended readings of stationary tags while maintaining tracking of moving tags.
2Object-affected harmful factors
If RFID tags use movement-based functionality control, then unintended readings are reduced, but additional components are required
Solution Approach 1:
The patent combines multiple functions into a single integrated circuit that performs both movement detection and antenna impedance tuning. The piezoelectric energy harvesting module simultaneously harvests energy from movement and provides the signal for impedance control. This merging approach reduces overall device complexity compared to having separate movement sensing and impedance control systems.
Solution Approach 2:
The impedance tuned circuit serves multiple purposes: it controls antenna functionality, harvests energy from tag movement, and provides the control signal for impedance switching. This multi-functionality reduces the need for additional dedicated components, thereby managing device complexity while achieving movement-based control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables RFID tags to selectively respond to RFID readers based on their movement status, improving the accuracy of asset tracking and reducing unnecessary readings.
Implementation Method 1
a piezoelectric transducer, a power management module, and an energy storage unit
Data Source
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AI summary
A radio frequency identification (RFID) tag comprising a tag integrated circuit (IC), an antenna coupled to the tag IC, and an impedance tuned circuit coupled to the antenna, wherein the impedance tuned circuit configured to tune a circuit impedance of the antenna based on power received by the impedance tuned circuit. The RFID tag further comprises a piezo electric energy harvesting module coupled to the impedance tuned circuit, wherein the piezo electric energy harvesting module is configured to supply the power to the impedance tuned circuit.