Card Reader Metal Detection Sensor Adaptive Thresholding
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Solution Overview
Problem
Card readers often erroneously detect water as a foreign matter due to the characteristics of metal detection sensors, leading to unreliable operation, especially in environments exposed to wind and rain.
Innovation Solution
A card reader system that includes a metal detection sensor, a judgment part to compare outputs with a threshold value, and an abnormality determination part to assess differences within a stable determination width, reducing erroneous detection by updating reference values based on actual circumstances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal detection sensor is used to detect foreign matter, then foreign matter detection capability is improved, but erroneous detection of water droplets as foreign matter occurs
Solution Approach 1:
The system dynamically adjusts the determination threshold based on the reference value obtained during the card insertion period. Instead of using a fixed threshold, the threshold is adapted to the actual ambient conditions, allowing the system to distinguish between legitimate foreign matter signals and water droplet interference signals that vary with environmental conditions.
Solution Approach 2:
The system performs preliminary measurement during the card insertion period to establish a reference value before actual foreign matter detection begins. This preliminary action captures the baseline sensor output under normal operating conditions, enabling subsequent comparisons to distinguish true foreign matter from environmental interference.
2Device complexity
If a fixed threshold value is used for foreign matter detection, then detection simplicity is improved, but adaptation to environmental changes is reduced
Solution Approach 1:
The system transitions from a static fixed threshold to a dynamic adaptive threshold that changes based on environmental conditions. The determination threshold is continuously updated based on the reference value obtained during card insertion, allowing the system to adapt to varying ambient temperatures, humidity, and other environmental factors without increasing overall system complexity.
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 enhances the reliability of the card reader by accurately distinguishing between foreign matters and water droplets, ensuring stable foreign matter detection while minimizing false alarms.
Implementation Method 1
a metal detection sensor structured to detect a foreign matter including metal... when an object including metal is located in the vicinity of the core, an output voltage from the detection coil is increased
Data Source
AI summary
A card reader may be structured to perform at least one of reading of magnetic data recorded in a card and writing of magnetic data to the card. The card reader may include a metal detection sensor structured to detect a foreign matter including metal, a judgment part configured to compare an output of the metal detection sensor with a predetermined threshold value to determine whether abnormality has occurred or not, and an abnormality determination part configured to obtain a difference between a reference value and an output of the metal detection sensor in a case that the judgment part determines that the abnormality has occurred to determine as the foreign matter in a state that the difference is within a stable determination width.