Prism-Based Fingerprint Detection Using IR and Visible Light
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Solution Overview
Problem
Conventional fingerprint recognition devices are unable to distinguish between real and fake fingerprints, especially when they have similar patterns, leading to invalidations of valid fingerprints.
Innovation Solution
A fingerprint recognition system that uses a prism with an IR LED and a light source to capture both direct and inverse images of a fingerprint, analyzing the differences in gray-level and pixel variations to determine the validity of the fingerprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fingerprint recognition devices focus on pattern matching, then they can identify fingerprints efficiently, but they cannot distinguish between real and fake fingerprints
Solution Approach 1:
The patent divides the fingerprint verification process into three separate tests: (1) gray-level difference analysis comparing direct and inverse images, (2) pixel variation analysis examining ridge patterns, and (3) quality assessment of the fingerprint image. Each test independently evaluates different aspects of fingerprint authenticity, and all three must pass for verification. This segmentation allows the system to maintain efficient processing while comprehensively detecting fake fingerprints through multiple independent validation mechanisms.
2Reliability
If the system uses multiple light sources to capture direct and inverse images, then it can detect fake fingerprints more accurately, but the device complexity increases
Solution Approach 1:
The patent employs a single optical sensor that performs multiple functions: capturing both the direct image (from the light source illuminating the fingerprint) and the inverse image (from the IR LED illuminating through the fingerprint). This multi-functional approach allows the system to obtain multiple types of fingerprint data using one sensor, reducing overall device complexity while maintaining the ability to perform comprehensive fake fingerprint detection through gray-level and pixel variation analysis.
Solution Approach 2:
The patent introduces a prism as an intermediary optical element that directs light from both the light source and IR LED to the fingerprint and routes the resulting images to the sensor. This intermediary component simplifies the optical path design and enables simultaneous capture of direct and inverse images without requiring separate complex imaging systems, thereby reducing device complexity while achieving reliable fake fingerprint detection.
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
Effectively differentiates between real and fake fingerprints by passing three tests based on predetermined threshold values, ensuring accurate identification and preventing unauthorized access.
Implementation Method 1
both the IR LED and the light source are configured to illuminate the fingerprint simultaneously to produce a captured image of the fingerprint
Implementation Method 2
providing an IR LED located near a second side of the prism
Data Source
AI summary
Methods and Apparatus are provided for fake fingerprint detection. In one embodiment, an apparatus for fake fingerprint detection includes a prism having a first side configured to be touched by a fingerprint, an IR LED located near the second side of the prism, a light source located near the third side of the prism, where both the IR LED and the light source are configured to illuminate the fingerprint simultaneously to produce a captured image of the fingerprint, one or more lenses configured to direct the captured image of the fingerprint for storage, one or more CMOS sensors configured to collect the captured image of the fingerprint for analysis, and a controller configured to determine validity of the fingerprint using the captured image.