Display Cover Stack With Hard Coating for Flexible Impact Resistance

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Solution Overview

Problem

Existing display device cover members struggle to balance impact resistance, scratching resistance, and bending resistance, particularly in flexible displays, with glass cover members being prone to breakage and resin cover members lacking durability.

Innovation Solution

A stacked body comprising an impact absorbing layer and a hard coating layer is designed with specific breaking strength and elongation ranges, where the hard coating layer breaks at 7 MPa or more and 4% to 36% elongation, combined with a thin glass substrate, to enhance impact, scratching, and bending resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If glass cover member is used to improve impact resistance and scratch resistance, then durability is improved, but breakage risk increases and weight increases

Engineering Contradiction:

Improveimpact resistanceVSAvoidbreakage risk

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The cover member is divided into multiple functional layers: a glass substrate layer for structural strength and impact resistance, and a resin layer for flexibility and breakage prevention. This segmentation allows each layer to perform its specific function optimally without compromising the others.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining glass and resin materials. The glass substrate provides hardness and impact resistance, while the resin layer provides flexibility and prevents complete breakage. This composite approach resolves the contradiction between durability and breakage risk.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If glass cover member is thinned to improve flexibility for foldable displays, then bending resistance is improved, but impact resistance deteriorates dramatically

Engineering Contradiction:

ImproveflexibilityVSAvoidimpact resistance

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The cover member is segmented into a thin glass substrate layer that provides flexibility and a separate resin layer that provides impact resistance. This allows the glass to be thin enough for folding while the resin compensates for the reduced impact resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

By combining thin glass with resin in a composite structure, the invention achieves both flexibility and impact resistance. The resin layer acts as a cushioning medium that maintains protection even when the glass substrate is thinned for flexibility.

Inventive Principle:

Principle #40Composite materials

3Strength

If impact absorbing layer and hard coating layer are added to glass substrate to improve impact and scratch resistance, then durability is improved, but bending resistance deteriorates

Engineering Contradiction:

Improveimpact resistanceVSAvoidbending resistance

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The invention changes the material parameters by replacing rigid hard coating layers with a resin layer that has appropriate elasticity. This allows the cover member to maintain impact resistance while achieving the necessary flexibility for bending applications.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The resin layer serves as both an impact absorbing layer and a flexible coating layer, eliminating the need for separate hard coating layers. This composite structure provides impact resistance while maintaining bending flexibility.

Inventive Principle:

Principle #40Composite materials

4Weight of moving object

If resin cover member is used to reduce weight and improve flexibility, then weight and flexibility are improved, but durability and scratch resistance deteriorate

Engineering Contradiction:

ImproveweightVSAvoiddurability

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The cover member is segmented into a glass substrate layer that provides durability and scratch resistance, and a resin layer that provides flexibility and weight reduction. This segmentation allows the glass to ensure durability while the lightweight resin layer provides the needed flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The composite structure combines heavy glass with lightweight resin, achieving a balance between durability and weight reduction. The glass substrate ensures scratch and impact resistance, while the resin layer keeps the overall weight low and provides flexibility.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS20260036723A1Member for display device and display device

Publication Date: 2026.02.05 DAI NIPPON PRINTING CO LTD

AI summary

The present disclosure provides a member for a display device comprising a stacked body formed by stacking an impact absorbing layer and a hard coating layer, wherein, when measuring a tensile stress of the stacked body, a stress at which the hard coating layer breaks is regarded as a hard coating layer breaking strength, and an elongation at which the hard coating layer breaks is regarded as a hard coating layer breaking elongation, the hard coating layer breaking strength is 7 MPa or more, and the hard coating layer breaking elongation is 4% or more and 36% or less.