Fingerprint Identification Apparatus with Stress Buffer

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Solution Overview

Problem

The demand for smaller non-viewable areas in mobile devices for fingerprint identification has created a need for a fingerprint identification apparatus that is resistant to impact forces without compromising fingerprint identification ability, as traditional solutions are inconvenient for users and may be affected by the thickness of protective layers.

Innovation Solution

A fingerprint identification apparatus comprising a cover lens, an optically clear adhesive layer, a fingerprint sensitive layer, and a stress buffer, where the stress buffer has greater hardness than the fingerprint sensitive layer, allowing for thinner cover lenses and enabling fingerprint sensitive electrodes to be placed on the viewable area without affecting identification accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a thick cover lens is used above the fingerprint sensitive layer, then the endurance to impact force is improved, but the fingerprint identification ability is adversely affected

Engineering Contradiction:

Improveendurance to impact forceVSAvoidfingerprint identification ability

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The patent segments the protective structure into multiple functional layers: a cover lens for basic protection, an optically clear adhesive layer for bonding, and a stress buffer layer specifically designed to absorb impact forces. This segmentation allows each layer to specialize in its function, enabling the cover lens to be thin while maintaining overall impact resistance through the stress buffer layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stress buffer layer acts as an intermediary between the cover lens and the fingerprint sensitive layer. It absorbs and dissipates impact forces before they reach the fingerprint sensitive electrodes, protecting the identification ability while allowing the cover lens to remain thin for optimal optical performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of stationary object

If the non-viewable area is reduced to achieve narrower frame, then the device aesthetics and compactness are improved, but the space for fingerprint identification area is reduced

Engineering Contradiction:

Improvenon-viewable areaVSAvoidfingerprint identification area space

Core Design Contradiction:

Area of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent employs thin film structures for the cover lens and stress buffer layer, allowing the fingerprint identification area to extend closer to the edges of the display. This enables the non-viewable area to be minimized while maintaining sufficient space for functional electrodes in the viewable area, achieving both narrow frame and adequate identification area.

Inventive Principle:

Principle #30Flexible shells and thin films

3Ease of operation

If fingerprint sensitive electrodes are formed on the viewable area, then the fingerprint identification accessibility is improved, but the visual appearance may be affected

Engineering Contradiction:

Improvefingerprint identification accessibilityVSAvoidvisual appearance

Core Design Contradiction:

Ease of operationVSShape

Solution Approach 1:

The patent uses an optically clear adhesive layer that is transparent to allow the fingerprint sensitive electrodes in the viewable area to remain visually imperceptible. This enables electrodes to be placed in the viewable area for better accessibility without affecting the visual appearance, as the electrodes are hidden beneath the transparent adhesive layer.

Inventive Principle:

Principle #32Color changes

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 stress buffer effectively buffers impact forces, improving the apparatus' endurance and allowing for thinner designs that maintain fingerprint verification accuracy, enabling both high impact resistance and visible fingerprint sensitive electrodes without compromising identification performance.

Implementation Method 1

The cover lens and the fingerprint sensitive layer are adhered by the optically clear adhesive layer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

The stress buffer has greater hardness than that of the fingerprint sensitive layer... the stress buffer can buffer an impact force from a dropped ball

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS10572712B2Fingerprint identification apparatus

Publication Date: 2020.02.25 ALPHA TOUCH GROUP LLC

AI summary

A fingerprint identification apparatus includes a cover lens, an optically clear adhesive layer, a fingerprint sensitive layer and a stress buffer. A total thickness of the cover lens and the optically clear adhesive layer is less or equal to a value “M”, wherein 0.3 mm≤M≤0.45 mm. The cover lens and the fingerprint sensitive layer are adhered by the optically clear adhesive layer. The fingerprint sensitive layer is disposed on the stress buffer. The stress buffer has greater hardness than that of the fingerprint sensitive layer.