Card Reader Capacitive Sensor Region Switching
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Solution Overview
Problem
Existing card readers face challenges in detecting foreign matters, such as magnetic heads for skimming, due to the influence of movable components, which can lead to false detections and increased costs from multiple capacitive sensors and drive circuits.
Innovation Solution
A card reader design with a capacitive sensor divided into regions, where one region is less susceptible to movable structure influence and another is more susceptible, using a switch circuit to connect and disconnect these regions to the drive and detection circuit, allowing for wide-range foreign matter detection without interference from movable components and reducing the number of drive and detection circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If capacitive sensors are arranged over a wide range inside the card reader to detect foreign matter, then the detection coverage is improved, but the number of drive and detection circuits increases, leading to higher costs
Solution Approach 1:
Multiple capacitive sensor regions share a single drive and detection circuit. The control circuit multiplexes the circuit resources by sequentially connecting different sensor regions to the shared drive and detection circuit, enabling wide-area detection while minimizing the number of circuits required
Solution Approach 2:
The patent employs dynamic switching of sensor regions using switch circuits controlled by a control unit. Different capacitive sensor regions are selectively connected to the shared drive and detection circuit based on detection needs, allowing flexible resource allocation and reducing the need for permanent dedicated circuits for each sensor region
2Reliability
If multiple capacitive sensors and drive circuits are arranged to detect foreign matter over a wide range, then the detection capability is improved, but the cost increases
Solution Approach 1:
The patent merges multiple sensor regions into a single detection system by sharing the drive and detection circuit among multiple regions. This consolidation maintains comprehensive detection capability while significantly reducing the number of expensive dedicated circuits required, thereby lowering manufacturing costs
Solution Approach 2:
The single drive and detection circuit is designed to serve multiple capacitive sensor regions through time-division multiplexing. This universal circuit performs the function of detecting capacitance changes in different sensor regions sequentially, replacing what would traditionally require multiple specialized circuits
3Measurement precision
If capacitive sensors are used to detect foreign matter, then the detection sensitivity is improved, but the influence of movable members causes erroneous detections
Solution Approach 1:
The capacitive sensor is divided into multiple distinct regions, each monitored by the shared drive and detection circuit. This segmentation allows the system to identify which specific region experiences capacitance changes, enabling differentiation between genuine foreign matter detections and false signals from movable member movements in particular areas
Solution Approach 2:
The control circuit receives feedback from the detection circuit about capacitance changes in different sensor regions and uses this information to distinguish between legitimate foreign matter detections and interference from movable members. The system can adjust detection thresholds or trigger additional verification based on the location and characteristics of detected changes
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 accurate and continuous foreign matter detection over a wide range at a lower cost by isolating the influence of movable structures and sharing drive and detection circuits, thereby reducing erroneous detections and operational expenses.
Implementation Method 1
In a method of detecting insertion of a foreign matter into a card reader by using a capacitive sensor, a capacitance change caused along with the foreign matter being arranged inside the card reader is detected.
Data Source
AI summary
A card reader for use with a card having a magnetic stripe may include a card insertion port; a card passage through which the card inserted from the card insertion port passes, the card passage being connected to the card insertion port; a magnetic head configured to perform at least one of: recording magnetic data to the magnetic stripe of the card and reading magnetic data from the magnetic stripe of the card; a capacitive sensor provided in contact with the card passage; and a movable structure structured such that a distance to the capacitive sensor is variable. The capacitive sensor may include a plurality of regions, each of the plurality of regions being structured to detect a capacitance, and a switch circuit configured to electrically connect and disconnect each region of the plurality of regions.