Contactless Biodetector Visual Sign Positioning

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Solution Overview

Problem

Conventional biodetectors require a support surface for image capture, leading to user reluctance due to skin contact concerns and resulting in poor image quality and erroneous recognition results, especially when users are hesitant to touch external surfaces.

Innovation Solution

A contactless biodetector system that projects visual signs onto the user's hand or finger, allowing them to position their hand in a volume without a contact surface, with the sign reconstituted on the opposite side, guiding the user to the correct position for image capture, eliminating the need for autofocus lenses and support surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a support surface is used for image capture, then image quality and user guidance are improved, but user reluctance increases due to skin contact concerns

Engineering Contradiction:
Improveimage qualityVSAvoiduser cooperation
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The invention removes the support surface (glass plate or prism) from the system, extracting the element that causes user reluctance while preserving its image capture function through alternative means (direct imaging of the hand/finger placed in the capture volume without contact surface).

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a visual sign projection system as an intermediary to guide users. Instead of relying on physical contact with a support surface, the system projects visual signs onto the user's hand to indicate correct positioning, mediating between the user and the image capture process without requiring skin contact with external surfaces.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If automatic focusing systems are used, then image capture without contact is enabled, but device complexity and cost increase

Engineering Contradiction:
Improvecontactless operationVSAvoidfocus mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The invention makes the user responsible for positioning their hand/finger in the correct plane through visual feedback from projected signs, rather than requiring the device to actively adjust focus. The system provides the means (visual signs indicating correct position) but relies on user action to achieve proper positioning, eliminating complex autofocus mechanisms.

Inventive Principle:
Principle #25Self-service

3Use of energy by moving object

If the aperture of the imaging device is increased, then sensitivity is improved, but depth of field decreases

Engineering Contradiction:
Improvesensor sensitivityVSAvoiddepth of field
Core Design Contradiction:
Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent transitions from a static support surface to a dynamic visual sign projection system that can adapt to different hand positions and orientations. The visual signs are projected in real-time to guide users, allowing the system to maintain effectiveness across a range of positions rather than requiring precise fixed positioning, effectively compensating for the reduced depth of field.

Inventive Principle:
Principle #15Dynamics

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 system provides an intuitive and reliable method for users to capture high-quality images without skin contact, improving user cooperation and reducing errors in recognition and identification processes.

Implementation Method 1

a device for projecting two components of a visual sign, which is adapted so that this sign is reconstituted from the two components in a registration plane substantially parallel to the image capture plane

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP1987472B1Biodetector functioning without contact
Publication Date: 2009.06.24 SAGEM SECURITE SA
  • EP1987472B1 patent drawingFigure 1~3c
  • EP1987472B1 patent drawingFigure 3d~4b
  • EP1987472B1 patent drawingFigure 5

AI summary

A biodetector permits formation of an image of the inner face of the hand or of a finger of a user when the hand or the finger (101) is placed in front of an image-forming device (11), at a defined height (F). The height is adapted such that the biodetection image is sufficiently clear and is indicated to the user by means of a sign (40) projected onto the outer face of the hand or of the finger. Such a biodetector does not require the hand or finger to be applied to a support surface, and it permits intuitive and rapid use of the biodetector.