RFID Antenna Polarization Control for Tag Reading Efficiency
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Solution Overview
Problem
Traditional wireless tag reading methods using linearly polarized waves require longer reading times due to unknown tag orientations, leading to inefficient communication distances and prolonged reading times.
Innovation Solution
A wireless tag reading apparatus with an RFID antenna capable of emitting both horizontally and vertically polarized waves, where the power feeding time ratio is adjusted based on the number of tags in each direction to optimize reading efficiency, allowing for efficient communication with tags regardless of orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If linearly polarized waves are switched to achieve long communication distance, then communication distance is improved, but reading time increases due to unknown tag orientations
Solution Approach 1:
The patent applies dynamics by making the polarization direction adjustable rather than fixed. The antenna can dynamically switch between horizontal and vertical polarization modes based on real-time detection of tag orientations, allowing the system to adapt to unknown tag directions while maintaining efficient communication distance and reducing reading time.
Solution Approach 2:
The patent changes the polarization parameter of the emitted wave between horizontal and vertical modes. By varying this parameter based on detected tag orientations, the system optimizes both communication distance and reading efficiency, resolving the contradiction between maintaining long range and reducing time loss from unknown orientations.
2Adaptability or versatility
If circularly polarized waves are used to read tags irrespective of direction, then adaptability to tag orientations is improved, but communication distance decreases
Solution Approach 1:
Instead of using fixed circular polarization, the system dynamically switches between horizontal and vertical linear polarizations based on detected tag orientations. This dynamic approach provides adaptability to various tag directions while maintaining the longer communication distance characteristic of linearly polarized waves.
Solution Approach 2:
The patent segments the polarization emission into distinct horizontal and vertical modes rather than using a single circular polarization mode. This segmentation allows the system to target specific polarization directions based on tag orientation detection, achieving both adaptability and extended communication distance.
3Length of stationary object
If traditional switching between linearly polarized waves is used, then communication distance is maintained, but reading efficiency decreases due to unnecessarily long emission time
Solution Approach 1:
The patent implements feedback by detecting the orientations of wireless tags and using this information to adjust the polarization mode of the emitted waves. This feedback mechanism eliminates unnecessary emission time by targeting the appropriate polarization direction based on actual tag orientations, thereby improving reading efficiency while maintaining communication distance.
Solution Approach 2:
The system performs preliminary detection of tag orientations before emitting the polarized waves. This preliminary action allows the system to pre-determine the optimal polarization mode, avoiding unnecessary emission time and improving overall reading efficiency while maintaining the ability to communicate over long distances.
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 approach reduces reading time by adjusting the power feeding time ratio and maximizing bit length settings for each polarization, ensuring efficient reading of all tags while maintaining communication distance, even when tag orientations are unknown.
Implementation Method 1
a linearly polarized wave having a longer communicable distance at the same radio wave intensity
Implementation Method 2
emitting a circularly polarized wave capable of reading irrespective of the directions of the wireless tags
Data Source
AI summary
In accordance with an embodiment, a wireless tag reading apparatus includes an antenna, first and second power feeding ports, and a controller. The first power feeding port feeds electric power into the antenna so as to emit the first linearly polarized wave from the antenna. The second power feeding port feeds electric power into the antenna so as to emit the second linearly polarized wave from the antenna. The controller sets a ratio of a time of power feeding from the first power feeding port to a time of power feeding from the second power feeding port to take a value according to a ratio of the number of wireless tags existing in the direction of the first linearly polarized wave to the number of wireless tags existing in the direction of the second linearly polarized wave.