Fingerprint Identification Device Using Segmented Infrared Imaging
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Solution Overview
Problem
Existing personal identification devices using finger blood vessel patterns as biometric features face challenges in size due to configuration requirements and image quality degradation when the light source and image pickup means are positioned on the same side of the finger.
Innovation Solution
A personal identification device with an infrared light source, a transmission light quantity control element array, and a light receiving element array positioned on the same side of the finger, using a liquid-crystal material for light control and a single transparent substrate to reduce thickness and enhance image quality by combining images from different light transmission regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light source and image pickup means are positioned on opposite sides of the finger, then the image quality is improved, but the device size increases
Solution Approach 1:
The device segments the imaging process into multiple sequential light transmission measurements through different regions of the finger. By dividing the finger into multiple regions and measuring each separately, the system achieves high-quality images without requiring the light source and sensor to be on opposite sides, thus reducing device size while maintaining measurement precision.
Solution Approach 2:
The invention transitions from a single-point transmission measurement to a multi-regional measurement approach. By controlling the light transmission through multiple different regions of the finger sequentially and combining the images, the system achieves comprehensive blood vessel pattern detection without increasing the physical distance between light source and sensor, thus solving the contradiction between image quality and device size.
2Volume of moving object
If the light source and image pickup means are positioned on the same side of the finger, then the device size is reduced, but the image quality degrades due to light reflection noise
Solution Approach 1:
The device divides the finger into multiple distinct regions and performs separate light transmission measurements for each region. By segmenting the measurement process across different finger regions rather than using a single direct transmission path, the system eliminates the need for complex optical arrangements that increase device size, while the combination of multiple regional images compensates for the loss of image quality that would otherwise result from light reflection noise.
Solution Approach 2:
The invention uses the finger's own structure as an intermediary by measuring light transmission through multiple different regions of the finger sequentially. This approach acts as a mediator between the light source and sensor positioned on the same side, allowing the system to obtain sufficient blood vessel pattern information without direct line-of-sight transmission that would be blocked by the finger, thus reducing device size while maintaining image quality.
3Measurement precision
If multiple regions of the finger are measured sequentially, then the blood vessel pattern recognition accuracy is improved, but the authentication time increases
Solution Approach 1:
The device performs light transmission measurements through multiple finger regions in a periodic sequential manner. By systematically cycling through different regions and combining the results, the system achieves comprehensive blood vessel pattern recognition. The periodic measurement approach ensures that all necessary regions are covered efficiently, balancing the need for high recognition accuracy with acceptable authentication time.
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 solution results in a thin personal identification device that produces high-quality images of finger blood vessel patterns, addressing size and image quality issues while maintaining effective biometric authentication.
Implementation Method 1
radiates a finger with a light source containing an infrared or near-infrared light component
Implementation Method 2
The intensity distribution of the resulting infrared or near-infrared radiation contains the information about a blood vessel pattern
Implementation Method 3
The transmission light quantity control element array includes a plurality of light transmission control elements for exercising control to transmit or block light
Implementation Method 4
using a liquid-crystal material for light control
Data Source
AI summary
A thin personal identification device that in which the infrared light source, transmission light quantity control element array, and light receiving element array are positioned on the same side of a living body. A microcomputer controls the array to combine a first image, which is obtained from the living body when one region of the living body is radiated with light transmitted from the infrared light source, with a second image, which is obtained when another region of the living body is radiated, and identifies a person in accordance with the combined image.