Adaptive Emissive Screen for Fingerprint Sensor Image Quality
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Solution Overview
Problem
Current fingerprint sensors face challenges with bulkiness, inferior performance in portable devices, and issues with external light interference, which degrades image quality and can lead to fraud detection difficulties, especially in large-sized sensors where finger position is not predetermined.
Innovation Solution
A method using an automated data-processing system with an emissive screen and an imager where the emissive screen displays multiple display patterns based on the analysis of the initial image to optimize lighting and improve image quality, incorporating luminous geometric figures for fraud detection without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a flat optical sensor with diffuse light source is used to reduce sensor bulk, then sensor compactness is improved, but image quality degrades due to external light interference and exposure issues
Solution Approach 1:
The patent applies dynamics by making the light source intensity adjustable and adaptive. The system dynamically adjusts the intensity of light emitted by the sensor's light source based on detected external light conditions and finger characteristics. This allows the sensor to compensate for external light interference and achieve optimal image quality while maintaining the compact flat optical sensor design.
Solution Approach 2:
The patent changes the parameter of light intensity dynamically. By varying the intensity level of the light source according to environmental conditions and finger properties, the system overcomes the limitation of fixed illumination in compact sensors, thereby maintaining high image quality without increasing sensor bulk.
2Area of stationary object
If uniform diffuse lighting is used to illuminate the finger, then lighting coverage is improved, but fraud detection capability deteriorates due to lack of distinctive patterns
Solution Approach 1:
The patent introduces asymmetry by projecting non-uniform light patterns (such as lines, grids, or geometric shapes) onto the finger instead of uniform diffuse lighting. These asymmetric patterns create corresponding light reflections that are captured by the sensor, enabling the system to distinguish between authentic fingers and frauds based on the unique interaction patterns of light with the finger's surface properties.
Solution Approach 2:
The patent utilizes color changes by employing light sources that emit specific wavelengths or colors and detecting the reflected light characteristics. Different materials and surface properties of the finger interact differently with specific colors, providing distinctive signatures for fraud detection while maintaining comprehensive lighting coverage through the emissive screen.
3Measurement precision
If light intensity is adjusted to correctly image the center of the finger, then central region quality is improved, but peripheral regions become saturated due to overexposure
Solution Approach 1:
The patent applies local quality by projecting spatially varying light patterns that are differently intense at different locations. Instead of uniform illumination, the system uses patterns where the center and periphery receive appropriately differentiated light intensities, allowing both regions to be captured with optimal quality without saturation or underexposure, thereby preserving information across the entire finger surface.
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 enhances image quality and reliability by adapting lighting patterns to specific conditions and features, effectively improving the detection of authentic human body parts and reducing the risk of fraud, while maintaining sensor compactness and efficiency.
Implementation Method 1
an emissive screen comprising an array of individually controllable pixels, the state of the pixels defining a display pattern of the emissive screen
Implementation Method 2
a substrate on which are disposed elements sensitive to light constituting an imager
Data Source
AI summary
The invention relates to a method for biometric processing of images of part of the human body comprising at least one finger, said method being performed by a sensor, and wherein an emissive screen (1) displays at least one first display pattern to light said part of the human body and an imager (2) acquires at least one first image of said part of the human body; from this first image, the automated data-processing system determines at least one second display pattern different to the first display pattern; the emissive screen (1) displays at least the second pattern to light said part of the human body and the imager (2) acquires at least one second image of said part of the human body; a biometric processing being performed on a final image constructed from at least the second image.