Preformed Curvilinear Foldable Substrate for Low-Stress Flexible Displays

Solution Overview

Problem

Foldable electronic devices with flexible displays face mechanical stress issues when folding, leading to adhesive layer failure due to tight bending radii, which limits the number of folding cycles before mechanical failure occurs.

Innovation Solution

Preforming the foldable substrate into a predefined curvilinear three-dimensional shape minimizes stress loads on the flexible display, allowing it to maintain a neutral, force-free state and reduce mechanical strain during folding, thereby extending the lifespan of the display.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the flexible display is folded with a tight bending radius, then the device achieves a compact form factor, but the adhesive layers fail due to excessive mechanical stress

Engineering Contradiction:

Improvecompact form factorVSAvoidadhesive layer durability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The substrate is preformed into a curvilinear three-dimensional shape that anticipates the folding configuration, positioning the display in a neutral state before folding occurs. This preliminary shaping reduces the sudden stress冲击 during folding by pre-accommodating the curvature, allowing tight folding radii without adhesive failure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The substrate's physical shape is changed from a flat two-dimensional plane to a preformed curvilinear three-dimensional configuration. This parameter change in the substrate's geometry allows it to better accommodate the folding stress distribution, reducing mechanical strain on the adhesive layers while maintaining compact form factor when folded.

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If the display is made larger, then consumer preference for large displays is satisfied, but mechanical stress upon folding increases

Engineering Contradiction:

Improvedisplay sizeVSAvoidmechanical stress during folding

Core Design Contradiction:

Area of stationary objectVSStress or pressure

Solution Approach 1:

The substrate is preformed into a curvilinear three-dimensional shape that anticipates the folding configuration, positioning the display in a neutral state before folding occurs. This preliminary shaping reduces the sudden stress冲击 during folding by pre-accommodating the curvature, allowing tight folding radii without adhesive failure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The substrate is formed into a curvilinear three-dimensional shape with smooth continuous curves rather than sharp angles or flat surfaces. This curvature distribution allows stress to be evenly dispersed throughout the substrate during folding, reducing peak stress concentrations that would otherwise cause adhesive failure in larger displays.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Adaptability or versatility

If the substrate is made flexible to enable folding, then the device can be folded, but the adhesive layers fail due to repeated folding cycles

Engineering Contradiction:

Improvefolding capabilityVSAvoidnumber of folding cycles

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The substrate is preformed into a curvilinear three-dimensional shape that anticipates the folding configuration, positioning the display in a neutral state before folding occurs. This preliminary shaping reduces the sudden stress冲击 during folding by pre-accommodating the curvature, allowing tight folding radii without adhesive failure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The preformed substrate serves itself by maintaining a neutral force-free state that automatically accommodates folding movements. The curvilinear shape inherently absorbs and distributes folding stresses without requiring additional protective mechanisms, enabling the display to withstand repeated folding cycles without adhesive layer failure.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11550364B2Flexible display with preformed curvilinear foldable substrate and corresponding electronic devices and methods

Publication Date: 2023.01.10 MOTOROLA MOBILITY LLC

AI summary

A flexible display includes a foldable display coupled to a foldable substrate. The foldable substrate is preformed to maintain a curvilinear three-dimensional shape when in a neutral, force-free state. The curvilinear three-dimensional shape can simulate one or more contours of an electronic device housing to which the flexible display is attached, thereby reducing or minimizing stress loads on the flexible display as the electronic device housing transitions between an axially displaced open position and a closed position.