Card Reader Foreign Matter Detection via Shutter Capacitance
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Solution Overview
Problem
Card readers face challenges in accurately distinguishing between liquid entry and insert skimmer attachment in the card conveyance path, leading to potential false detection and security vulnerabilities.
Innovation Solution
A card reader design incorporating a shutter member and two capacitance sensors to calculate output differences, determining the presence of foreign matter by distinguishing between liquid entry and insert skimmer attachment based on specific threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitance sensor is used to detect foreign matter in the card conveyance path, then the detection capability is improved, but the ability to distinguish between liquid entry and insert skimmer attachment deteriorates
Solution Approach 1:
The detection process is segmented into multiple measurement phases: initial measurement with shutter closed, intermediate measurement with shutter open, and final measurement with shutter closed. This segmentation allows the system to capture different capacitance characteristics that help distinguish between liquid entry and insert skimmer attachment, resolving the contradiction between detection capability and detection accuracy.
Solution Approach 2:
The system changes the state parameter of the shutter (open/closed) during the detection process to modulate the capacitance sensor readings. By comparing capacitance values under different shutter states, the system can identify patterns specific to liquid entry versus insert skimmer attachment, thereby improving detection accuracy while maintaining detection capability.
2Measurement precision
If the shutter member is moved to detect foreign matter, then the detection process is improved, but the time required for detection increases
Solution Approach 1:
The system performs preliminary measurements with the shutter closed before opening the shutter. This preliminary action establishes baseline capacitance values that are used for comparison during the actual detection phase, enabling faster and more accurate foreign matter identification without requiring extensive measurement time.
Solution Approach 2:
The detection process uses periodic shutter operations (closed-open-closed) to gather capacitance data at different states. This periodic action allows the system to efficiently collect necessary measurement information in a structured sequence, balancing detection accuracy with time efficiency.
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 solution enables high-accuracy detection of foreign matter, improving crime prevention by accurately differentiating between liquid presence and insert skimmer attachment, thereby enhancing security.
Implementation Method 1
a first capacitance sensor provided in the main body part and structured to detect that an object is present in the card conveyance path
Data Source
AI summary
A card reader may include a main body part including a card conveyance path; a shutter member structured to move between a closed position and an open position; a first capacitance sensor provided in the main body part; and a control unit. The control unit may be structured to calculate a first output difference between an output of the first capacitance sensor in a first state and an output of the first capacitance sensor in a second state; calculate a second output difference between a maximum output of the first capacitance sensor in a period from the first state to the second state and the output of the first capacitance sensor in the second state; and determine that an object is installed when the first output difference is greater than a predetermined first threshold and the second output difference is less than a predetermined second threshold.