Flexible Transparent Block for Fingerprint Capture

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Solution Overview

Problem

Existing fingerprint identification and authentication methods face challenges with two-dimensional capture systems that cause finger deformation and uncertainty due to contact with rigid plates, and three-dimensional capture systems require immobility of the hand, making them difficult to use effectively.

Innovation Solution

A device with a flexible, transparent block supported by a bottom plate that deforms to match the shape of the finger, allowing for image capture and template construction without the need for hand immobilization, using a camera and illumination system to analyze and generate a template from the deformed pattern.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a rigid plate is used for 2D fingerprint capture, then the device structure is simple, but the finger is deformed and the imprint accuracy is reduced

Engineering Contradiction:
Improvedevice structureVSAvoidimprint accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies a flexible transparent membrane instead of a rigid plate for fingerprint capture. The membrane can deform elastically under finger pressure to conform to the finger's surface topology, then return to its original state. This flexibility allows accurate capture of the fingerprint pattern without permanently deforming the finger or losing ridge detail information.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the physical state of the capture surface from rigid to flexible. By using a membrane with specific elastic properties, the system can dynamically adjust its stiffness - remaining rigid when not in use but becoming compliant during fingerprint capture. This parameter change resolves the contradiction between structural simplicity and capture accuracy.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If a 3D capture system with multiple sensors is used, then the identification accuracy is improved, but the ease of operation is reduced due to hand immobilization requirement

Engineering Contradiction:
Improveidentification accuracyVSAvoidease of use
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces complex multi-sensor 3D capture systems with a simpler 2D imaging approach. By using a flexible transparent membrane that naturally conforms to the finger shape, the system achieves sufficient identification accuracy without requiring multiple sensors or hand immobilization. The mechanical flexibility of the membrane substitutes for complex sensor arrays.

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

Solution Approach 2:

The flexible membrane creates a faithful optical copy of the fingerprint pattern by conforming to the finger's surface. This direct optical contact method captures sufficient ridge and valley information for identification without needing complex 3D reconstruction algorithms or multiple viewing angles, thereby simplifying operation.

Inventive Principle:
Principle #26Copying

3Area of stationary object

If a transparent flexible block is used for capture, then the fingerprint surface area captured is increased and deformation is reduced, but the device complexity increases

Engineering Contradiction:
Improvefingerprint surface areaVSAvoiddevice structure
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The transparent flexible block serves multiple functions simultaneously: it acts as the capture surface, provides structural support, enables optical transparency for imaging, and offers elastic deformation capability. This multi-functionality increases the captured surface area without proportionally increasing device complexity, as a single component achieves what would otherwise require multiple separate elements.

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

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 accurate and comfortable capture of a large fingerprint surface with reduced deformation, improving identification and authentication processes by maintaining ease of use while enhancing image quality and information capture.

Implementation Method 1

the transparent block being made of a flexible material which deforms and matches the shape of the part of the body bearing the print when the latter presses thereon

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2425375B1Device for identifying a person by a print thereof
Publication Date: 2014.10.29 MORPHO
  • EP2425375B1 patent drawingFigure 1
  • EP2425375B1 patent drawingFigure 2

AI summary

The invention relates to a device (100) for identifying or authenticating a person by a print thereof, the identification or authentication device (100) including: a bearing means (102, 130) including a transparent base (130) and a transparent block (102) supported by said base (130) on which the part of the body carrying the print is pressed, the surface of the transparent block (102) on which the part of the body carrying the print is pressed having a test chart (132), the transparent block (102) being made of a flexible material that deforms and fits the shape of the part of the body carrying the print when the latter is pressed against the former, a means (106, 126) for capturing an image of said print and the test chart (132) through said bearing means (102, 130), a means (108) for analysing the image of the deformed test chart (132), a means (110) for constructing a template of the print according to the print thus captured and the image of the test chart (132) thus analysed, a means (114) for verifying the identity of the person or a means (114) for authenticating the person according to the template thus constructed.