Finger Vein Imaging Illumination Control via Transmission Power

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Solution Overview

Problem

Existing systems for acquiring images of finger veins on-the-fly struggle to efficiently adjust illumination power due to the iterative nature of previous methods, which are time-consuming and not suitable for real-time applications, especially when dealing with varying finger thickness and dermis thickness.

Innovation Solution

A system that includes a camera, an infrared illumination device, and a control unit capable of measuring transmission power using a photoemitter and photodetector pair to adjust illumination intensity in real-time, with a learning mode to establish an optimal illumination-intensity link, and optional servocontrol and channel selection for image quality optimization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If iterative servocontrol method is used to adjust illumination power, then illumination intensity can be adapted to finger transmission power, but acquisition time increases significantly

Engineering Contradiction:

Improveillumination powerVSAvoidacquisition time

Core Design Contradiction:

Illumination intensityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by using a photodetector to measure finger transmission power before image acquisition. This pre-measurement allows the system to determine the appropriate illumination power in advance, eliminating the need for iterative adjustments during the actual image capture process and enabling on-the-fly acquisition.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the iterative mechanical feedback system (servocontrol based on image brightness measurement) with an optical measurement system (photodetector-based transmission power measurement). This substitution provides direct feedback about finger properties before illumination is applied, allowing immediate calculation of optimal illumination power without time-consuming iterations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If high illumination power is used for thick fingers, then vein images can be captured, but thin fingers become overexposed and unusable

Engineering Contradiction:

Improveimage qualityVSAvoidadaptability to different finger types

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by measuring the transmission power specific to each finger being scanned and adjusting illumination power accordingly. Instead of using a fixed illumination level or iterative global adjustment, the system tailors the illumination power to the local characteristics (thickness, dermis density) of each individual finger, ensuring optimal image quality for both thick and thin fingers.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the illumination power parameter dynamically based on the measured transmission power of each finger. The control unit calculates the optimal illumination power as a function of the measured transmission power, allowing the system to adapt to varying finger characteristics and maintain consistent image quality across different finger types.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If exposure measurement devices are added to the camera, then illumination can be adjusted, but system cost and complexity increase

Engineering Contradiction:

Improveillumination controlVSAvoidsystem complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary photodetector device that measures finger transmission power independently of the camera system. This intermediary measurement allows the control unit to calculate optimal illumination power without requiring complex exposure measurement devices integrated into the camera, thereby avoiding increased system complexity and cost while still achieving precise illumination control.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 rapid and accurate adjustment of illumination intensity, reducing the number of iterations needed for high-quality image acquisition, ensuring effective vein image capture even with thick fingers or thin skin, and maintaining image quality during movement.

Implementation Method 1

a photoemitter and photodetector pair to adjust illumination intensity

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

The absorption of the light by the haemoglobin flowing in the veins of the fingers makes it possible to reveal these veins in the acquired image

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS10105056B2System and method for acquiring images of veins of a finger

Publication Date: 2018.10.23 IDEMIA PUBLIC SECURITY FRANCE

AI summary

A system for acquiring an image of veins of a finger includes a camera designed to acquire an image of said finger when it is passed in front of it, a lighting device designed to illuminate said finger and a control unit for controlling the illumination intensity of said lighting device. Also, at least one system measures the transmission power of said finger upstream of the camera with respect to the passage of said finger towards said camera, said control unit being designed to control the illumination intensity of said lighting device according to the transmission power measured by said measuring system. Additionally, a method for acquiring images of veins of a finger is provided.