Contactless Fingerprint Capture with Optical Guidance and Dynamic Alignment

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Solution Overview

Problem

Current biometric fingerprint systems, particularly contactless ones, face challenges such as high cost, complexity, limited integration with other systems, ergonomic design issues, and high false rejection rates due to skin deformations and variability in finger positioning, which hinder widespread adoption in security and access control applications.

Innovation Solution

A compact, ergonomic device with advanced sensors and acoustic-luminous signaling for contactless fingerprint capture, capable of capturing multiple fingers simultaneously, utilizing a CMOS image sensor, LED illumination, and sophisticated algorithms for image processing and biometric recognition, integrated with communication interfaces for seamless connectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If contactless fingerprint capture is implemented, then hygiene and user safety are improved, but device complexity and cost increase

Engineering Contradiction:
ImprovehygieneVSAvoiddevice complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces contact-based mechanical fingerprint sensors with a contactless optical imaging system. Instead of direct physical contact between the finger and sensor, the system uses an image sensor to capture fingerprint images through optical means, eliminating the need for mechanical contact while maintaining fingerprint recognition capability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical field as an intermediary between the finger and the image sensor. The fingerprint information is transmitted through light reflection and optical paths rather than direct physical contact, allowing the sensor to capture detailed fingerprint patterns without touching the user's finger

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If contactless fingerprint capture is implemented, then hygiene and user safety are improved, but measurement precision deteriorates due to skin deformations and positioning variability

Engineering Contradiction:
ImprovehygieneVSAvoidfingerprint capture quality
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent employs dynamic image processing techniques that can adapt to varying finger positions and skin deformations. The system uses multiple image capture frames and applies dynamic alignment algorithms to compensate for movement and deformation, ensuring consistent measurement precision despite the contactless nature of capture

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback mechanisms where the system analyzes captured fingerprint image quality in real-time and provides guidance to the user for optimal positioning. The processing module evaluates image quality metrics and can request additional captures if the quality threshold is not met, ensuring high measurement precision

Inventive Principle:
Principle #23Feedback

3Productivity

If multiple fingers are captured simultaneously, then identification speed and productivity are improved, but device complexity increases

Engineering Contradiction:
Improveidentification speedVSAvoiddevice complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent combines multiple fingerprint capture functions into a single imaging operation. The image sensor captures all visible fingers in the field of view simultaneously, and the processing module then separates and processes each fingerprint individually, achieving multi-finger identification in one capture event without requiring multiple sensors

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent designs the imaging system to serve multiple functions: it can capture single or multiple fingers, adjust to different lighting conditions, and adapt to various finger positions. This universal design allows the same hardware to handle diverse identification scenarios without requiring additional specialized components

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Volume of moving object

If compact integration of components is achieved, then device portability and ease of installation are improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvedevice sizeVSAvoidcomponent integration precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent employs a nested arrangement where the image sensor, illumination module, and processing components are integrated within a compact housing. The optical components are positioned in nested configurations to minimize space requirements while maintaining proper optical paths and focal distances

Inventive Principle:
Principle #7Nested doll (Nesting)

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 device provides fast, secure, and reliable biometric identification and verification with reduced false rejection rates, enhancing user experience and acceptance by ensuring high-quality fingerprint captures and efficient integration with existing systems.

Implementation Method 1

an illumination module (comprising high-power LED sources of one or more wavelengths, focusing optical lenses)

Methodology Applied
Scientific EffectLight Emitting Diode: Light Emitting Diode

Implementation Method 2

an image capture module including a 1∼3 MP CMOS image sensor

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP4287148B1Contactless fingerprint biometric system
Publication Date: 2025.08.06 BY TECHDESIGN SL
  • EP4287148B1 patent drawingFigure 1
  • EP4287148B1 patent drawingFigure 2A~2B
  • EP4287148B1 patent drawingFigure 3~4

AI summary

The present invention relates to a device and methods for the acquisition and processing of touchless fingerprints of one or more fingers, which can be used for biometric (1:N) identification and/or (1:1) verification of users in applications related to the field of security systems and access control in offices, large corporate buildings, industry, hospitals, universities, luxury residential environments, etc. The device houses all the system components inside a compact compartment of reduced dimensions and bestows both a highly-innovative mechanics and an ergonomic design, which is underpinned by a open-capture area that lacks covers, visors, or supporting parts to place the hand or fingers in the tridimensional space. The fingers are captured "in the air" (without contact with the device) in a rapid, hygienic, simple and intuitive way, while the user is guided where to properly locate the hand (fingers) during the capture process through an acoustic-luminous signaling system. The device comprises at least an external mechanical enclosure and electronic modules for the illumination, image capturing, object detection, acoustic-luminous signaling, image and data processing, and control. In addition to biometric fingerprint recognition (of one or more fingers), the device allows the capture of other digital access credentials (multi-credential approach), such as RFID proximity cards and smartphones (mobile credential).