Under-display fingerprint spoof detection via light scattering
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Solution Overview
Problem
Current fingerprint sensors are vulnerable to high-quality, high-resolution spoof fingerprints, which can trick the system and grant unauthorized access, as they primarily rely on image comparison without effectively distinguishing between real and fake fingerprints.
Innovation Solution
An under-display optical fingerprint sensor with a controlled light source illuminates a target region, acquiring an anti-spoof image to identify characteristics such as scattered light distribution, which differs between real and spoofed fingers, using algorithms and machine learning to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If image comparison is used to detect fingerprints, then authentication speed is improved, but vulnerability to spoof fingerprints increases
Solution Approach 1:
The fingerprint detection process is segmented into multiple independent detection channels: a first channel captures reflected light for traditional fingerprint imaging, while a second channel captures transmitted light to detect subsurface scattering characteristics. This segmentation allows the system to maintain fast authentication through parallel processing while improving reliability by analyzing multiple physical characteristics simultaneously.
Solution Approach 2:
The patent introduces light scattering characteristics as an intermediary detection parameter between the traditional reflected light imaging and the final authentication decision. By analyzing how light scatters within the fingerprint ridges and valleys before making authentication decisions, the system gains an additional layer of verification that resists spoof attempts while maintaining speed.
2Device complexity
If traditional reflected light imaging is used, then device complexity is reduced, but ability to detect spoof fingerprints deteriorates
Solution Approach 1:
The optical sensor is designed with multi-functionality to serve both traditional fingerprint imaging and anti-spoof detection. By incorporating multiple light sources (reflected and transmitted light paths) and multiple image sensors within a single integrated structure, the system achieves enhanced spoof detection capability without proportionally increasing device complexity, as the same hardware serves dual purposes.
Solution Approach 2:
The patent transitions from two-dimensional reflected light imaging to three-dimensional light interaction analysis by adding transmitted light detection. This dimensional expansion allows the system to probe subsurface scattering characteristics that are invisible to traditional surface-level imaging, thereby improving spoof detection without adding significant structural complexity.
3Reliability
If multiple light sources and sensors are added for anti-spoof detection, then spoof detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the anti-spoof detection function with the existing fingerprint imaging system by combining multiple light sources and image sensors into a unified optical detection unit. The first and second light sources with their corresponding image sensors are integrated such that they share common structural elements and processing pathways, thereby improving spoof detection accuracy while minimizing the increase in device complexity through functional consolidation.
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 method improves the ability to distinguish real from spoofed fingerprints by analyzing the extent of light scattering, reducing the risk of unauthorized access and enhancing the security of fingerprint-based authentication systems.
Implementation Method 1
analyzing the extent of light scattering
Data Source
AI summary
A method for detecting spoof fingerprints with an under-display fingerprint sensor includes illuminating, with incident light emitted from a display, a target region of a fingerprint sample disposed on a top surface of the display; detecting a first scattered signal from the fingerprint sample with a first image sensor region of an image sensor located beneath the display, the first image sensor region not directly beneath the target region, the first scattered signal including a first portion of the incident light scattered by the target region; determining a scattered light distribution based at least in part on the first scattered signal; and identifying spoof fingerprints based at least in part on the scattered light distribution.