Resonance Circuit Frequency Control for Stable RFID Voltage
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Solution Overview
Problem
Information processing terminals, such as IC cards and RFID tags, face instability due to varying received voltage levels from readers/writers, leading to inefficient power conversion and potential operational failure, especially at longer distances or with obstructions, and existing solutions like clamping circuits can deprive the terminal of necessary power.
Innovation Solution
An information processing terminal with a resonance circuit unit that varies its resonance frequency linearly in response to control signals, a maximum received voltage setting unit, and a control signal generation unit, allowing the terminal to maintain stable operation by optimizing received voltage within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonance frequency is varied non-linearly to control received voltage, then the terminal can prevent excessive voltage, but the efficiency of voltage conversion deteriorates above and below threshold levels
Solution Approach 1:
The patent applies parameter changes by continuously adjusting the resonance frequency of the terminal based on the detected received voltage level. The control unit varies the resonance frequency within a predetermined range to optimize voltage conversion efficiency while preventing excessive voltage. This dynamic parameter adjustment resolves the contradiction by maintaining both operational stability and conversion efficiency through real-time frequency tuning rather than fixed threshold-based switching.
2Reliability
If a clamping circuit is used to prevent excessive received voltage, then voltage protection is achieved, but the terminal is deprived of necessary power when received voltage is relatively low
Solution Approach 1:
The patent replaces the static clamping circuit with a dynamic resonance frequency control mechanism. The control unit continuously adjusts the resonance frequency based on the actual received voltage level, enabling the terminal to adaptively optimize power extraction. When voltage is low, the frequency adjusts to maximize power transfer; when voltage is high, the frequency shifts to prevent excessive voltage. This dynamic approach resolves the contradiction between protection and power availability.
3Device complexity
If the terminal operates at fixed resonance frequency, then the circuit design is simplified, but the terminal cannot maintain stable performance when received voltage varies due to distance or obstructions
Solution Approach 1:
The patent implements feedback control by detecting the received voltage level and using this information to adjust the resonance frequency. The control unit receives feedback about the voltage condition and dynamically tunes the resonance frequency to maintain optimal operation. This feedback mechanism enables the terminal to adapt to varying communication conditions (distance, obstructions) while maintaining performance stability without requiring overly complex circuit design.
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
The solution enables the terminal to function stably across varying voltage conditions, maximizing power reception when needed and preventing excessive voltage, thus enhancing communication reliability and reducing heat generation.
Implementation Method 1
When the magnetic field of the reader/writer is transited by the IC card or RFID tag with its receiving coil, the coil induces a voltage (called the induced voltage) in reaction to the magnetic field
Implementation Method 2
The IC card or RFID tag using its receiving coil acquires magnetic field energy from the transmitting coil of the reader/writer and receives a voltage (called the received voltage) by causing the induced voltage to resonate with the predetermined frequency
Data Source
AI summary
Disclosed herein is an information processing terminal including: a resonance circuit unit configured to have a resonance frequency varying linearly in accordance with a control signal so as to receive data and power from a reader/writer in noncontact fashion at the resonance frequency; a maximum received voltage setting unit configured to output a reference voltage for defining a maximum received voltage to be output by the resonance circuit unit; a control signal generation unit configured to generate the control signal in accordance with the received voltage and the reference voltage; and a transmit-receive processing section configured to operate on the received voltage to process the data; wherein the received voltage is not in excess of a predetermined level.