Fake Fingerprint Detection Using Dual-Angle Prism Illumination
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Solution Overview
Problem
Current fingerprint recognition technologies face challenges in accurately distinguishing fake fingerprints from real ones, particularly in high-security applications, due to variations in light attenuation and radiation angles affecting identification performance.
Innovation Solution
A fake fingerprint identifying apparatus and method that utilizes a housing with a prism, a first light source unit, and a second light source unit, where the second light source unit is fixedly supported to irradiate light at a predetermined angle with the fingerprint contact surface, allowing for comparison of images acquired through the prism to identify fake fingerprints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is radiated from an external light source to identify fake fingerprints, then the identification capability is improved, but the light radiation angle and contact state variations cause identification performance to deteriorate
Solution Approach 1:
The patent divides the lighting system into two separate light sources: an internal light source (first light source unit) that shines through the prism from below, and an external light source (second light source unit) that shines from above at a predetermined angle. This segmentation allows each light source to serve a specific function - the internal light provides consistent baseline illumination while the external light creates angle-dependent shadows that reveal fake fingerprints, thereby resolving the contradiction between identification capability and performance stability
Solution Approach 2:
The patent changes the lighting parameters by fixing the external light source at a predetermined radiation angle relative to the prism surface. This parameter control ensures that light always reaches the finger or fake fingerprint at a consistent angle, creating reliable shadow patterns that enhance fake fingerprint detection while maintaining stable identification performance across different contact states
2Use of energy by moving object
If the second light source unit is fixedly supported to irradiate light at a predetermined angle, then light transmission efficiency is improved, but the device structure becomes more complex
Solution Approach 1:
The patent merges the light irradiating unit and the housing into a single integrated structure. The housing itself incorporates the function of supporting and positioning the external light source at the predetermined angle, eliminating the need for separate complex positioning mechanisms. This merging achieves both the desired light transmission efficiency and acceptable structural complexity by combining multiple functions into one component
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 ensures consistent light reaching the fingerprint or fake fingerprint, enhancing the identification performance by maintaining constant light angles and improving light transmission efficiency, thereby improving the accuracy of fake fingerprint detection.
Implementation Method 1
radiating light from the outside such that light is transmitted through a finger along an inner surface adjacent to a surface of the finger
Implementation Method 2
Since the living body has a large degree of light attenuation, the light rapidly attenuates while it proceeds inside of the body, and then disappears. On the other hand, in a fake fingerprint, the degree of light attenuation is small, so that most of the light is transmitted
Data Source
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AI summary
An apparatus (1000) for identifying a fake fingerprint includes a housing (1100), a prism (1200), a first light source unit (1300), a second light source unit (1400), a sensor unit (1500) and a control unit (1600). The prism (1200) is disposed in the internal space (1120) of the housing. The first light source unit (1300) irradiates light in the internal space (1120) to allow the light to pass through the prism (1200). The second light source unit (1400) irradiates light to allow the light not to pass through the prism (1200). The sensor unit (1500) acquires a first image through the first light source unit (1300) and a second image through the second light source unit (1400). The control unit (1600) identifies a fake fingerprint on the basis of a result acquired by comparing the first image and the second image. The housing (1100) includes a light irradiating unit (200) that fixes and supports the second light source unit (1400) to form a predetermined angle with the fingerprint contact surface (1210).