Non-Contact Finger Vein Authentication Light Guide Design
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Solution Overview
Problem
Conventional finger vein authentication apparatuses face challenges in maintaining stable finger positioning for non-contact authentication, leading to reduced repeatability and quality of vein images due to variations in finger placement, which also results in adverse light leakage affecting the imaging unit.
Innovation Solution
A non-contact finger vein authentication apparatus is designed with a light source positioned to minimize light leakage to the imaging unit, using a light source direction adjustment and independent control of light intensity to ensure proper illumination of the finger while preventing strong light from entering the imaging unit, and incorporating a positioning unit such as air blowing or visible light sources to guide finger placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a non-contact authentication apparatus is used to avoid physical contact and maintain sanitation, then sanitation and user comfort are improved, but finger presentation position stability deteriorates
Solution Approach 1:
A light guide unit is introduced as an intermediary component between the light source and the finger. This unit guides and concentrates light onto the finger while allowing the finger to be positioned without physical contact, thus maintaining both sanitation and light illumination effectiveness
Solution Approach 2:
The mechanical contact-based positioning system is replaced with an optical field-based system. Instead of using physical guide units that require finger contact, the patent uses light fields to define and maintain the finger presentation position, eliminating the need for mechanical contact while preserving positioning stability
2Illumination intensity
If light intensity is increased to improve illumination quality, then imaging quality is improved, but light leakage to peripheral portions and imaging unit increases
Solution Approach 1:
The light guide unit is designed to concentrate light locally onto the finger area. By controlling the light distribution to be high intensity only where needed (on the finger) and low or zero elsewhere, the system achieves good illumination quality without causing light leakage to peripheral portions or the imaging unit
3Object-generated harmful factors
If a light shielding unit is installed to prevent light leakage to the imaging unit, then imaging quality is protected, but light transmission through the finger is blocked
Solution Approach 1:
The light guide unit serves as an intermediary that separates the light path into two distinct functions: (1) guiding light to the finger for transmission imaging, and (2) preventing light from reaching the imaging unit directly. This mediator structure allows the system to block light leakage without requiring a light shielding unit that would obstruct the transmitted light path
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
The apparatus achieves high-quality vein image acquisition and stable authentication without physical contact, reducing psychological resistance and maintaining image quality even with varying finger positions, while minimizing light-related noise and ensuring proper illumination.
Implementation Method 1
when infrared light is illuminated to a finger, the illuminated infrared light is scattered in an interior portion of the finger, and thereafter, is radiated outside the finger. At this time, since hemoglobin contained in blood may largely absorb the infrared light, as compared with peripheral tissue of blood vessels, when the light which has transmitted through the finger is imaged, blood vessels distributed under the skin of this finger, namely, finger veins may be visualized as dark shadow patterns
Implementation Method 2
air blowing units to assist in finger positioning
Data Source
AI summary
A perfect non-contact type vein authentication apparatus is provided with a light source for emitting infrared light; an input interface equipped with an imaging unit for photographing a vein image of a living body by the infrared light emitted from said light source; a unit for controlling intensity of light to be illuminated; an image calculating unit for performing a feature extracting operation and a feature authenticating operation with respect to an image; and a positioning unit for presenting the living body. More specifically, the light source is provided in front of the living body. Both the light source and the imaging unit are installed in such a positional relationship that the light of the light source gives no adverse influence to the imaging unit. Also, the light source is installed in such a direction that the light of the light source gives no adverse influence to the imaging unit.