MR Sensor Card Reader Jamming Field Detection
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Solution Overview
Problem
Existing card readers face difficulties in accurately detecting magnetic data on a card's magnetic stripe when a disturbing magnetic field is generated to prevent skimming, as the field interferes with the pre-head's ability to read the data.
Innovation Solution
The card reader incorporates an MR sensor with two resistors, strategically positioned close to each other in the moving direction of the card, connected in series, to minimize the impact of the disturbing magnetic field on the resistance changes, allowing for clear differentiation between data and noise signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a disturbing magnetic field is generated to prevent skimming, then security against fraudulent data acquisition is improved, but the ability of the pre-head to accurately detect magnetic data is deteriorated
Solution Approach 1:
The sensor is divided into multiple detection units (first detection unit and second detection unit) with different orientations. Each unit detects magnetic field components in different directions, allowing the system to segment the magnetic field measurement into orthogonal components that can be processed separately to distinguish signal from noise.
Solution Approach 2:
A magnetic shielding plate is introduced as an intermediary component between the disturbing magnetic field source and the detection sensor. The shielding plate selectively blocks or attenuates the disturbing magnetic field components while allowing the legitimate magnetic data to pass through, acting as a mediator that protects the detection process.
2Reliability
If a disturbing magnetic field is generated continuously to prevent skimming, then security is improved, but the signal-to-noise ratio for magnetic data detection is deteriorated
Solution Approach 1:
The disturbing magnetic field is applied in a periodic or pulsed manner rather than continuously. The field is activated during specific time intervals when skimming prevention is critical, and deactivated during intervals when accurate detection is required, creating a temporal pattern that alternates between security enforcement and detection optimization.
Solution Approach 2:
The system dynamically adjusts the characteristics of the disturbing magnetic field based on operational requirements. The field strength, duration, and activation timing are made variable rather than fixed, allowing the system to optimize the balance between security and detection accuracy in real-time based on the operational state.
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 configuration enables the card reader to accurately detect magnetic data on the card's stripe even when a disturbing magnetic field is present, ensuring effective prevention of skimming attempts.
Implementation Method 1
an MR sensor (magnetoresistive sensor) that detects whether magnetic data are recorded in the magnetic stripe
Implementation Method 2
a disturbing magnetic field generator that generates a disturbing magnetic field
Data Source
Figure 1~2
Figure 3~4
AI summary
The purpose of the present invention is to provide a card reader which, even if a jamming magnetic field is generated, is capable of appropriately sensing whether magnetic data is recorded on a magnetic stripe of a card which is inserted via a card insertion port. Provided is a card reader 1, comprising: a magnetoresistance (MR) sensor 10 for sensing whether magnetic data is recorded on a magnetic stripe of a card 2 which is inserted via a card insertion port 3; and a jamming magnetic field generating means 11 which generates a jamming magnetic field for jamming illicit reading of the magnetic data which is recorded on the magnetic stripe. Magnetic data which is arrayed in the movement direction of the card 2 which is inserted via the card insertion port 3 is recorded on the magnetic stripe of the card 2. The MR sensor 10 further comprises a first resistor and a second resistor, which are positioned in the movement direction of the card 2 separated by a distance which is less than a bit interval of the magnetic data when a zero is recorded in the data on the magnetic stripe.