Flexible Display Asymmetric Hardness Surface Protection

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Solution Overview

Problem

Flexible display apparatuses face damage during storage due to friction and impact when rolled or bent, particularly affecting the light-emitting surface, as existing materials lack sufficient impact resistance and flexibility.

Innovation Solution

A flexible display apparatus design where the light-emitting surface has a higher hardness than the rear surface, utilizing materials like polyethylene naphthalate (PEN) and polyether sulfone (PES) films with varying Young's modulus, light weight tear strength, and Vickers hardness to absorb contact stress and prevent damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the glass base film is thinned to reduce thickness and weight, then the display apparatus becomes more flexible and lighter, but the impact resistance characteristic deteriorates

Engineering Contradiction:

ImproveweightVSAvoidimpact resistance

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent employs a composite base film structure combining a polymer film (PET or PEN) with a metal thin film layer. This composite structure provides both flexibility and impact resistance, resolving the contradiction between thinness/weight reduction and impact resistance. The metal layer reinforces the polymer film to withstand impact while maintaining flexibility for rolling and bending.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent uses thin polymer films (PET or PEN) as the base film to achieve flexibility and light weight. These thin films enable the display apparatus to be rolled up or bent for storage while maintaining sufficient mechanical strength through the composite structure with metal thin film reinforcement.

Inventive Principle:

Principle #30Flexible shells and thin films

2Adaptability or versatility

If the glass base film is thinned to improve flexibility, then the display apparatus can be rolled up or bent, but the glass base film cannot be bent without breaking

Engineering Contradiction:

ImproveflexibilityVSAvoidbend resistance

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent replaces rigid glass with flexible polymer films (PET or PEN) that can be bent and rolled without breaking. These polymer films inherently possess the flexibility required for portable storage while maintaining sufficient strength through the composite structure with metal thin film reinforcement.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The composite structure of polymer film plus metal thin film provides both the flexibility needed for bending and rolling, and the strength to prevent breaking during repeated flexing operations.

Inventive Principle:

Principle #40Composite materials

3Volume of moving object

If the light emitting surface is brought into contact with the rear surface during storage, then the display apparatus can be compactly stored, but the light emitting surface is easily damaged by friction and impact

Engineering Contradiction:

Improvestorage sizeVSAvoidsurface damage

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies different hardness characteristics to different surfaces of the base film. The light-emitting surface is designed with higher hardness to resist damage during contact, while the rear surface has lower hardness to provide cushioning. This local differentiation of material properties protects the critical light-emitting surface during compact storage.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The softer rear surface acts as a cushioning layer that absorbs impact energy before it reaches the light-emitting surface. This beforehand cushioning prevents damage to the critical light-emitting surface during rolling and storage operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Adaptability or versatility

If a polymer film or metal thin film is used instead of glass base film, then thickness and weight are reduced and flexibility is improved, but the light emitting surface is easily damaged by contact friction

Engineering Contradiction:

ImproveflexibilityVSAvoidsurface damage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent creates asymmetric hardness distribution in the base film structure, with the light-emitting surface having higher hardness than the rear surface. This local quality differentiation protects the light-emitting surface from friction damage during contact while maintaining the overall flexibility of the polymer or metal thin film structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The composite structure of polymer/metal thin film with differentiated surface hardness provides both flexibility for portable storage and protection against surface damage. The combination of materials and asymmetric hardness distribution resolves the contradiction between flexibility and surface durability.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8456078B2Flexible display apparatus

Publication Date: 2013.06.04 CANON KK

AI summary

A flexible display apparatus includes a flexible base film, and a light emitting device formed on the base film. A surface located on a light emitting surface side has a hardness higher than a hardness of a surface located on a rear surface side.