Live Finger Detection via Radiated RF Electric Field Patterns
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Solution Overview
Problem
Existing fingerprint sensor systems are ineffective in distinguishing live human fingers from artificial fingers due to variations in capacitance, resistance, and impedance across different demographics and over time, leading to high false rejection rates and security concerns.
Innovation Solution
The use of radiated RF electric field patterns to differentiate between live human fingers and artificial fingers by analyzing the stable electric field patterns generated by live human fingers, which are more reliable across a wide spectrum of populations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance, resistance, or impedance measurement techniques are used to detect live fingers, then the detection system can identify electrical characteristics of fingers, but the wide variations in these parameters across different demographics and over time lead to high false rejection rates
Solution Approach 1:
The patent changes the detection parameter from electrical impedance (capacitance, resistance) to optical properties (light absorption, reflection, transmission). This parameter change allows detection of finger characteristics that are more stable across demographics and less susceptible to environmental factors like sweat gland activity, thereby reducing false rejection rates while maintaining detection accuracy
Solution Approach 2:
The patent replaces the electrical measurement system with an optical measurement system. Instead of using electrical contacts to measure capacitance or resistance, the system uses light sources and optical sensors to detect finger properties, eliminating the issues associated with electrical parameter variations
2Measurement precision
If electrical impedance measurement techniques are used, then the system can differentiate between live and artificial fingers based on electrical properties, but the capacitance, resistance, and impedance of human tissue varies over time and in response to environmental conditions, reducing detection reliability
Solution Approach 1:
The patent transitions from measuring electrical parameters (capacitance, resistance, impedance) to measuring optical parameters (light absorption, reflection, transmission). Optical parameters are inherently more stable in human tissue and less affected by environmental conditions such as sweat gland activity, temperature, and humidity, thereby improving parameter stability while maintaining differentiation capability
Solution Approach 2:
The patent introduces light as an intermediary medium to probe finger characteristics. Light interacts with the finger tissue in a manner that reveals structural and compositional information without being significantly affected by the variable electrical properties of the tissue, providing a stable measurement medium
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 provides a more reliable method for live finger detection, reducing false rejection rates and enhancing security by utilizing the distinct electric field characteristics of live human fingers, which are stable across demographics and environmental conditions.
Implementation Method 1
determining whether the object is a live human finger or an artificial finger by a radiated RF electric field pattern
Data Source
AI summary
A live finger detection system and method includes a drive plate configured to inject radio frequency signals into an object proximate the drive plate. The injected radio frequency energy causes the object to radiate an electric field. A pickup plate is configured to detect an intensity associated with the electric field radiated by the object. A sensor coupled to the pickup plate is configured to determine whether the object is a live finger based on the detected intensity of the electric field radiated by the object.