Wireless IC Tag Coil Antenna Winding Direction Optimization
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Solution Overview
Problem
The energy transfer efficiency between wireless IC tags and reader-writers in RFID systems is reduced due to opposing winding directions of coil-shaped antennas, leading to decreased communication distances.
Innovation Solution
The use of coil-shaped antennas with the same winding direction and arranged at different positions, improving energy transfer efficiency by aligning magnetic fields and reducing current offset, thereby increasing communication distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two coil-shaped antennas are connected in series with opposite winding directions to form a figure eight, then the antenna structure is compact and can be integrated into the wireless IC tag, but the energy transfer efficiency is reduced due to current offset between the two antennas
Solution Approach 1:
The patent inverts the conventional approach by using the same winding direction for both coil-shaped antennas instead of opposite winding directions. This inversion prevents current offset and improves energy transfer efficiency while maintaining the compact figure-eight structure.
Solution Approach 2:
The patent changes the winding direction parameter from opposite to same for both antennas. This parameter change eliminates the current cancellation effect and enhances the magnetic field coupling between the reader-writer and tag antennas, thereby improving energy transfer efficiency.
2Device complexity
If two coil-shaped antennas with opposite winding directions are used, then the antenna configuration is simplified, but the communication distance decreases due to reduced energy transfer efficiency
Solution Approach 1:
The patent inverts the winding direction arrangement from opposite to same, which prevents current offset and enhances energy transfer efficiency. This enables extended communication distance while keeping the antenna configuration simple and integrated.
Solution Approach 2:
By changing the winding direction parameter to be identical for both antennas, the patent optimizes the magnetic field interaction and energy transfer, thereby extending the communication distance without complicating the antenna configuration.
3Loss of energy
If coil-shaped antennas with the same winding direction are used, then energy transfer efficiency is improved, but the antenna design becomes more complex
Solution Approach 1:
The patent merges the two coil-shaped antennas into a figure-eight configuration where both coils share the same winding direction. This merging approach maintains structural simplicity while achieving improved energy transfer efficiency through constructive magnetic field interaction.
Solution Approach 2:
The patent changes the winding direction parameter to be identical for both antennas in the figure-eight configuration. This parameter change simplifies the overall design by eliminating the need for complex phase management while improving energy transfer efficiency.
4Reliability
If coil-shaped antennas with the same winding direction are arranged at different positions, then communication reliability is improved without erroneous interactions, but the positioning and alignment requirements increase
Solution Approach 1:
The patent applies local quality by arranging the two coil-shaped antennas at different positions within the figure-eight configuration, each optimized for its specific spatial location. This local optimization ensures reliable communication while minimizing erroneous interactions with non-target tags.
Solution Approach 2:
The patent utilizes spatial dimensionality by arranging antennas at different positions in the figure-eight configuration. This dimensional arrangement enables selective communication with target tags while reducing interference with non-target tags, improving communication reliability.
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
Enhanced energy transfer efficiency between the wireless IC tag and reader-writer, allowing for longer communication distances and more reliable communication without erroneous interactions with non-target tags.
Implementation Method 1
a reader-writer producing an induction electromagnetic field communicates with a wireless tag in a non-contact manner to transmit information
Implementation Method 2
The antenna includes a first coil-shaped antenna portion and a second coil-shaped antenna portion... the winding axes of the first and second coil-shaped antenna portions are arranged at different positions
Data Source
AI summary
A wireless IC tag includes a wireless IC chip and two coil-shaped antennas. One end of each of the coil-shaped antennas is electrically connected to the wireless IC chip, and the other ends of the coil-shaped antennas are electrically connected to each other. The winding axes of the coil-shaped antennas are arranged at different positions, and the coil-shaped antennas have the same winding direction. A reader-writer includes an antenna connected to an information processing circuit. The antenna is electromagnetically coupled to the coil-shaped antennas for communication.