RFID Transponder Passing Time from 3D Field Symmetry
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Solution Overview
Problem
Current transponder systems for determining passing time over RFID loop antennas suffer from inaccuracies due to orientation, speed, and external conditions, leading to unreliable and inefficient time measurements.
Innovation Solution
A transponder system utilizing three inductive coils to measure field strength values, a processing unit to determine an effective value, an accumulation unit to collect and analyze time series data, and a symmetry unit to identify the point of maximum symmetry in the time series for precise passing time determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the passing time is determined as the point in time at which the highest field strength is detected, then the passing time determination is simple, but the measurement precision deteriorates due to orientation, speed, and external conditions
Solution Approach 1:
The patent divides the field strength detection into three separate inductive coils arranged orthogonally (x, y, z directions). Each coil measures field strength independently, and the measurements are combined to calculate the total field strength. This segmentation allows the system to capture the complete three-dimensional field vector, improving measurement accuracy while maintaining computational simplicity through the formula E_total = sqrt(E_x² + E_y² + E_z²).
Solution Approach 2:
The patent transitions from single-dimensional field strength measurement to three-dimensional field vector measurement by adding spatial dimensionality through orthogonal coil arrangement. This dimensional expansion enables the system to determine passing time based on the complete field vector magnitude rather than a single component, making the measurement independent of transponder orientation and improving precision without complicating the determination process.
2Measurement precision
If three inductive coils are used for three-dimensional field strength detection, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent merges the functions of three separate inductive coils into a unified three-dimensional field detection system. The coils are arranged orthogonally and their individual field strength measurements are combined using the vector magnitude formula E_total = sqrt(E_x² + E_y² + E_z²). This merging approach achieves complete three-dimensional field vector detection while maintaining a compact transponder structure, as all three coils can be integrated within a single transponder housing without significantly increasing overall device complexity.
Solution Approach 2:
The three orthogonal inductive coils serve multiple functions simultaneously: each coil detects field strength in its respective direction, collectively they provide complete three-dimensional field vector information, and their combined output enables orientation-independent passing time determination. This multi-functionality justifies the added complexity by delivering comprehensive field detection capabilities from a single integrated sensor array.
3Measurement precision
If multiple effective values are collected over time to determine a time series, then the measurement precision improves, but the loss of time increases due to data accumulation
Solution Approach 1:
The patent performs preliminary action by continuously measuring and storing effective field strength values in memory during the transponder's passage through the RFID loop antenna's electromagnetic field. The system accumulates multiple effective values at different time points, creating a time series dataset that captures the complete field interaction profile. This preliminary data accumulation occurs in real-time during the passing event, and the actual passing time determination is then performed by analyzing the stored time series to identify the moment of maximum field strength, thereby improving precision without extending the measurement duration beyond the natural passage time.
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 system provides accurate and efficient passing time calculations with high precision, reducing errors from external factors and enabling cost-effective implementation.
Implementation Method 1
three inductive coils for measuring three field strength values of an activation signal transmitted by the RFID loop antenna
Data Source
Figure 1~2
Figure 3(a)~3(e)
Figure 4(a)~4(d)
AI summary
The present invention relates to a transponder (12) for determining a passing time upon passing an RFID loop antenna (18), comprising: three inductive coils (26) for measuring three field strength values of an activation signal transmitted by the RFID loop antenna upon passing the RFID loop antenna; a processing unit (28) for determining an effective value of the three field strength values indicating an inductive field strength based on the three field strength values; an accumulation unit (30) for collecting effective values for multiple activation signals over time and determining a time series of effective values; and a symmetry unit (32) for determining a transponder passing time corresponding to a point in time (P) within the time series at which effective values before and after the point in time have a maximum level of symmetry. The present invention further relates to a method and a system (14) for determining a passing time of a transponder (12).