Card Reader Break-In Sensing Circuit Noise Reduction
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Solution Overview
Problem
Card readers with security CPUs face issues with noise interference leading to incorrect detection, particularly when sensing external aggression, due to the length of security lines which are prone to noise contamination.
Innovation Solution
A card reader design incorporating a break-in sensing circuit with a security mesh circuit, utilizing protection elements like zener diodes and capacitors to reduce noise influence, and employing pulse signals to accurately detect circuit states by observing phase differences between input and output terminals, thereby preventing wrong detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a long security line is used to sense external aggression, then the sensing coverage is improved, but noise interference increases leading to wrong detection
Solution Approach 1:
The patent introduces a protection element as an intermediary component between the security line and the sensing circuit. This protection element acts as a mediator that allows the security line to maintain its long length for comprehensive sensing coverage while blocking noise interference from reaching the sensing circuit, thus resolving the contradiction between sensing coverage and noise susceptibility
Solution Approach 2:
The patent converts the harmful noise interference into a beneficial filtering mechanism by using the protection element to selectively block high-frequency noise while allowing legitimate sensing signals to pass through. This transforms the noise problem into an opportunity to enhance signal purity and detection accuracy
2Reliability
If protection elements are added to reduce noise, then wrong detection is prevented, but device complexity increases
Solution Approach 1:
The patent applies protection elements selectively at specific critical points in the security line where noise interference is most likely to affect detection accuracy, rather than protecting the entire circuit uniformly. This localized approach maintains high detection accuracy while minimizing the addition of components and overall circuit complexity
Solution Approach 2:
The patent employs simple, inexpensive protection elements that can be easily integrated into the existing circuit without requiring complex design or expensive components. These protection elements are designed to be straightforward to implement and maintain, reducing the burden of device complexity while effectively preventing wrong detection
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 effectively minimizes noise interference and prevents incorrect detection, ensuring accurate sensing of break-in attempts, including disconnection and short-circuiting, while maintaining low power consumption and flexibility in port configuration.
Implementation Method 1
at least either one of the output terminal and the input terminal of the security circuit has a protection element between the terminal itself and an earth ground
Implementation Method 2
The protection element may be one of a zener diode, a capacitor, a parallel circuit of a capacitor and a zener diode, and a parallel circuit of a zener diode and a low-pass filter
Data Source
AI summary
A card reader may include a break-in sensing circuit and a security circuit structured to output a break-in sensing signal into the break-in sensing circuit, and receive a returned break-in sensing signal that returns from the break-in sensing circuit. The security circuit may include an output terminal to output the break-in sensing signal, and an input terminal to receive the returned break-in sensing signal. The break-in sensing signal may be input to an input section of the break-in sensing circuit, and then output from an output section of the break-in sensing circuit as the returned break-in sensing signal. The break-in sensing signal may be a pulse signal. At least either one of the output terminal and the input terminal of the security circuit may include a protection element between the terminal itself and an earth ground.