Finger Vein Authentication Device Size Reduction
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Solution Overview
Problem
Existing finger vein authentication devices require a large device size to capture a wide image of the finger, including its contour, which limits their downsizing and increases costs due to the need for expensive lenses or distorted images.
Innovation Solution
A finger vein authentication system that calculates the position and shape of a finger without capturing its contour, using a configuration with light sources arranged on both sides of the opening portion and an image taking unit below, allowing for accurate authentication while reducing device size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a wide-angle lens or microlens array is used to capture finger contour, then the device size can be reduced, but the image quality deteriorates due to distortion or high cost
Solution Approach 1:
The invention extracts only the necessary information (finger position and shape) from the captured image, rather than requiring a complete contour capture. By using multiple light sources to illuminate the finger from different angles and processing the resulting images to extract position and shape data, the system eliminates the need for wide-angle lenses or microlens arrays, thereby maintaining image quality while reducing device size.
Solution Approach 2:
The imaging unit serves multiple functions: it captures both the finger contour information and the vein pattern information using the same optical path. The light sources are arranged to provide both contour illumination and vein illumination, eliminating the need for separate optical systems and reducing overall device complexity and size.
2Measurement precision
If the device captures a wide image including finger contour, then accurate position measurement is achieved, but the device size increases
Solution Approach 1:
The invention transitions from a two-dimensional contour capture approach to a three-dimensional positioning approach. By arranging light sources at different positions and angles around the opening portion and processing images from multiple perspectives, the system calculates finger position and shape in three-dimensional space, achieving accurate measurement without requiring a wide-field single-image capture system.
Solution Approach 2:
The system performs preliminary illumination of the finger from multiple fixed light source positions before capturing the vein image. By pre-positioning the light sources and calculating their relative positions to the opening portion, the system can determine finger position and shape from the combined image data without requiring additional wide-angle optical components.
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
Enables highly accurate authentication with a compact device by measuring finger position and shape without contour capture, improving usability and reducing costs through efficient light source placement and image processing.
Implementation Method 1
a light source (50) for irradiating the finger (1) with light
Implementation Method 2
The infrared ray is scattered at inside of the finger, thereafter, transmitted to outside
Implementation Method 3
hemoglobin in blood absorbs the infrared ray more than a surrounding tissue
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~3D
AI summary
A blood vessel image taking device including a finger presentation area configured at a surface of a cabinet, plural light sources arranged at the finger presentation area for irradiating a presented finger with a light ray, a light quantity controlling unit for controlling light quantities of the plural light sources, an opening portion configured at the finger presentation area, and an image taking unit for taking an image of the light ray from the light source portion passing through the opening portion and irradiated to the finger, in which portions of the finger presentation area are a tip end presentation area for presenting a tip end side of the finger, and a root presentation area for presenting a root side of the finger.