Magnetic Stripe Reader Interference Cancellation
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Solution Overview
Problem
Magnetic stripe card readers face interference from electromagnetic noise, which affects the accuracy of data reading from magnetic tracks, particularly due to adjacent electronic circuitry.
Innovation Solution
Incorporating multiple magnetic sensors, including at least one that does not read encoded data, and a subtractor to cancel out interference by subtracting noise from the magnetic track sensor outputs, providing an interference-adjusted output to a processor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple magnetic sensors are used to read magnetic tracks, then data reading capability is improved, but electromagnetic interference from adjacent circuitry increases
Solution Approach 1:
The patent introduces a subtractor as an intermediary component that processes the outputs of multiple magnetic sensors. The subtractor removes interference signals from the sensor outputs by subtracting the non-encoded data sensor output from the encoded data sensor output, thereby eliminating electromagnetic interference while preserving the useful data reading function
Solution Approach 2:
The patent extracts and separates the interference component from the useful signal. By using an additional magnetic sensor that does not read encoded data and subtracting its output from the track reading sensors, the interference is extracted and removed, leaving only the clean encoded data signal
2Reliability
If additional magnetic sensors are added to cancel interference, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent segments the magnetic sensing function into distinct components: track reading sensors for data acquisition and additional sensors for interference detection. This segmentation allows independent optimization of each sensor type and simplifies the overall system design by clearly defining the role of each sensor
Solution Approach 2:
The subtractor acts as a simple intermediary that performs a straightforward subtraction operation between sensor outputs. This simple mathematical operation adds minimal complexity while effectively combining the outputs of multiple sensors to achieve reliable reading
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 solution effectively cancels electromagnetic interference, enhancing the accuracy of data reading from magnetic stripe cards by reducing noise, thereby improving the reliability of magnetic stripe card readers in point of sale devices.
Implementation Method 1
a magnetic stripe reader head including multiple magnetic sensors including at least one magnetic track reading sensor for reading data encoded in a magnetic track of a magnetic stripe
Data Source
AI summary
A magnetic stripe card reader useful for reading magnetic stripe bearing cards having at least one magnetic track, the magnetic stripe reader including a magnetic stripe reader head including multiple magnetic sensors including at least one magnetic track reading sensor for reading data encoded in a magnetic track of a magnetic stripe and at least one magnetic sensor which does not read encoded data, the magnetic stripe reader head providing magnetic sensor outputs including at least one magnetic track sensor reading output and at least one magnetic sensor output which has no encoded data therein and a subtractor operative to subtract at least a portion of the at least one magnetic sensor output, which has no encoded data therein, from the at least one magnetic track sensor reading output having card data encoded thereon, thereby to cancel interference from the at least one magnetic track reading output.