Card Reader Disturbing Magnetic Field Skimming Prevention
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Solution Overview
Problem
Existing card readers with differential type skimming magnetic heads struggle to prevent skimming when the distance between the read head and the dummy head is narrow, as the difference in output signal amplitudes due to the disturbing magnetic field becomes too small, making it difficult to obtain a read signal not affected by the field.
Innovation Solution
A card reader design that includes a disturbing magnetic field generation mechanism with a core and coil configuration, where the magnetic flux lines change direction to create a stronger disturbing magnetic field across the card passage, ensuring a significant difference in signal amplitudes between the read head and dummy head, even when the distance between them is narrow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a differential type skimming magnetic head is used with narrow distance between read head and dummy head, then the device structure is compact, but the difference in output signal amplitudes due to disturbing magnetic field becomes too small to prevent skimming
Solution Approach 1:
The patent applies local quality by creating a non-uniform disturbing magnetic field distribution across the card passage. The disturbing magnetic field generation means is positioned to generate a field that varies in intensity at different locations, specifically creating a larger difference in field intensity between the read head and dummy head positions. This localized variation in magnetic field strength ensures that even when the distance between heads is narrow, the differential signal remains sufficiently large to prevent skimming.
2Reliability
If a disturbing magnetic field is generated using conventional means, then skimming is prevented for wide-distance heads, but the signal amplitude difference becomes insufficient for narrow-distance heads
Solution Approach 1:
The patent applies parameter changes by modifying the intensity distribution of the disturbing magnetic field. Instead of using a uniform field, the disturbing magnetic field generation means is designed to create a field where the intensity parameter varies spatially. This results in a larger difference in magnetic field intensity at the read head versus the dummy head, thereby increasing the output signal amplitude difference and improving both skimming prevention and signal discrimination.
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 design effectively prevents skimming by ensuring a large difference in output signal amplitudes between the read head and dummy head, making it difficult to acquire a read signal not affected by the disturbing magnetic field, thus effectively preventing skimming.
Implementation Method 1
a disturbing magnetic field generation means including a core part having at least one core formed of magnetic material and a disturbing magnetic field generation coil wound around the core
Implementation Method 2
the core part includes a first end face and a second end face which are disposed so as to face substantially the front side. The disturbing magnetic field generation means generates a disturbing magnetic field in which a direction of a magnetic flux line is changed
Data Source
AI summary
A card reader may include a card insertion port; a card passage; and a disturbing magnetic field generator. The disturbing magnetic field generator may include a core part including a core formed and a disturbing magnetic field generation coil wound around the core. The core part may include a first end face and a second end face which are disposed so as to face substantially the front side. The disturbing magnetic field generator may generate a disturbing magnetic field whose flux line changes into a direction from the first end face toward the second end face and a direction from the second end face toward the first end face. The direction of the magnetic flux lines are substantially parallel to the passing direction of the card. In a width and thickness direction of the card, the magnetic flux line crosses a position where the magnetic stripe is passed.