Coupled LC Oscillator Circuit for Multi-Frequency RFID Detection
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Solution Overview
Problem
Conventional RFID readers face challenges in detecting transponders tuned to different resonant frequencies, leading to reduced sensitivity and detection range, especially when dealing with a population of transponders having varying resonant frequencies.
Innovation Solution
The implementation of a detection signal generator circuit within the RFID reader that utilizes a coupled oscillator system with multiple LC pairs, enabling the generation of detection signals at different frequencies, allowing for the detection of transponders tuned to various resonant frequencies while maintaining low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single frequency detection signal is used, then the reader can maintain low power consumption, but it cannot detect transponders with different resonant frequencies
Solution Approach 1:
The patent combines multiple LC pairs (first LC pair and second LC pair) into a single detection signal generator circuit. These LC pairs are coupled together through a coupling capacitor, allowing the circuit to generate detection signals at multiple frequencies (first detection frequency and second detection frequency) while maintaining a unified, integrated structure rather than using separate generator circuits for each frequency.
Solution Approach 2:
The detection signal generator circuit is designed to perform multiple functions by generating detection signals at different frequencies using the coupled LC pairs. This universal circuit can detect transponders with various resonant frequencies, making the reader adaptable to different transponder types without requiring separate dedicated circuits for each frequency range.
2Adaptability or versatility
If multiple separate detection signal generators are used for different frequencies, then all transponder frequencies can be detected, but power consumption increases
Solution Approach 1:
The patent merges multiple LC pairs into a single coupled oscillator system that shares common components and coupling mechanisms. This integrated approach allows the generation of multiple detection frequencies from one unified circuit rather than operating separate generator circuits, thereby reducing overall power consumption while maintaining the ability to detect transponders across different frequency ranges.
3Reliability
If the reader operates continuously in data transaction state, then communication with transponders is maintained, but power supply depletes rapidly
Solution Approach 1:
The reader employs periodic detection signal generation instead of continuous data transaction state operation. The coupled LC pairs generate detection signals at specific intervals to sense the presence of transponders, and only transition to the higher-power data transaction state when a transponder is detected. This periodic operation pattern maintains communication reliability by continuously monitoring for transponders while significantly reducing average power consumption during periods when no transponders are present.
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 enhances the reader's ability to detect transponders with different resonant frequencies, maintaining high sensitivity and reducing power consumption, thereby improving detection range and efficiency.
Implementation Method 1
The first and second LC pairs resonate in response to applied first and second pulses to produce a sequence of first and second detection signals
Implementation Method 2
The transponder data signals are transmitted in the form of electromagnetic oscillations into the surrounding space in which the reader resides via the antenna of the transponder LC pair
Implementation Method 3
The reader 'excites' or powers up the passive transponder by transmitting excitation signals of a given frequency into the space surrounding the reader, which are received by the transponder and provide the operating power for the circuitry of the recipient transponder
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
An RFID transponder detector is provided having a coupled oscillator system. Coupled first and second LC pairs of the system produce a detection signal each time a combination of pulses is applied to the LC pairs. Application of the pulses is repeated periodically to produce a sequence fo detection signals having two different first and second detection frequencies. Transmitting the sequence of detection signals results in corresponding first and second response signals having the first and second detection frequencies at the LC pairs. Values of a preselected detection parameter for the detection signals are compared to the values of the detection parameter for the response signals to determine if a transponder having a transponder resonant frequency corresponding to the first or second detection frequency is present in a proximal space of the transponder detector.