Fingerprint Sensor Concurrent Capacitance Measurement
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Solution Overview
Problem
Fingerprint sensors in smart cards face challenges in achieving high sensitivity due to the attenuation of capacitance changes caused by insulation materials between the finger and the sensor, which reduces sensor performance and requires resource-intensive correction techniques, making them less suitable for resource-constrained devices.
Innovation Solution
Concurrently measuring capacitances on subsets of sensor plates instead of individually, creating a 'virtual sensor plate' with increased capacitance that mitigates attenuation, thereby enhancing sensitivity without the need for software corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance is measured individually on each sensor plate, then measurement precision is maintained, but sensitivity is reduced due to attenuation by insulation materials
Solution Approach 1:
The patent combines multiple sensor plates into groups and measures the total capacitance of each group simultaneously. This merging approach creates a 'virtual sensor plate' with larger effective area, which compensates for the signal attenuation caused by insulation materials while maintaining measurement capability through subsequent processing to derive individual plate capacitances.
2Reliability
If software correction techniques are used to compensate for attenuation, then sensitivity is improved, but device complexity and resource consumption increase
Solution Approach 1:
The patent performs preliminary action by measuring multiple subsets of sensor plates concurrently before any correction is needed. By capturing multiple overlapping measurements in advance, the system enables subsequent mathematical processing to extract individual plate capacitances without requiring complex real-time correction algorithms, thus reducing device complexity.
3Device complexity
If traditional sequential measurement is used, then device complexity is low, but productivity is reduced due to longer measurement time
Solution Approach 1:
The patent implements periodic action by systematically cycling through multiple subsets of sensor plates in a structured sequence. Each subset is measured in a dedicated time slot, and by overlapping these periodic measurements, the system achieves concurrent measurement of all sensor plates, significantly improving productivity while maintaining manageable device complexity.
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 approach increases the sensitivity of fingerprint sensors while maintaining high-resolution image production, suitable for resource-constrained devices like smart cards without the power and memory requirements of traditional correction techniques.
Implementation Method 1
The measurement unit 104 is configured to measure one or more capacitances on the sensor plates 102
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
According to a first aspect of the present disclosure, a fingerprint processing system is provided, which comprises: a set of sensor plates; a measurement unit configured to measure one or more capacitances on the sensor plates; a processing unit configured to process the measured capacitances; wherein the measurement unit is configured to concurrently measure capacitances on subsets of the set of sensor plates; wherein the processing unit is configured to process the concurrently measured capacitances. According to a second aspect of the present disclosure, a corresponding method of processing a fingerprint in a fingerprint processing system is conceived. According to a third aspect of the present disclosure, a corresponding computer program is provided.