Foldable Display Coating Layer with Gradient Thickness

Solution Overview

Problem

In foldable display devices, the protective film can cause damage when the display panel is folded due to its thickness, leading to contact between film portions.

Innovation Solution

A display device structure with a coating layer design that includes a base layer, light emitting element layer, and driving circuit, where the coating layer's thickness gradually decreases towards the folding area, preventing damage during folding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective film is disposed below the display panel, then the display panel is protected, but the film may contact itself and cause damage when folded due to its thickness

Engineering Contradiction:

Improveprotection of display panelVSAvoidself-contact damage to film

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The coating layer is designed with non-uniform thickness, being thicker in the first and third portions and thinner in the second portion where folding occurs. This local variation in thickness allows the film to maintain protective function in non-folded areas while accommodating folding motion in the bent area without self-contact damage

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The thickness parameter of the coating layer is changed across different spatial locations. By controlling the thickness to be greater than a first reference value in non-folded portions and less than a second reference value in the folded portion, the film's mechanical properties are optimized to prevent damage during folding while maintaining protection elsewhere

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If the coating layer has uniform thickness, then manufacturing is simplified, but the coating layer may be damaged when the display panel is folded

Engineering Contradiction:

Improvecoating layer fabricationVSAvoiddamage resistance during folding

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The coating layer is designed with non-uniform thickness, being thicker in the first and third portions and thinner in the second portion where folding occurs. This local variation in thickness allows the film to maintain protective function in non-folded areas while accommodating folding motion in the bent area without self-contact damage

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating layer's thickness is dynamically adapted to match the structural requirements of different regions. The varying thickness allows the coating to flex and deform appropriately during folding without exceeding its elastic limit, thereby maintaining reliability while remaining manufacturable through controlled deposition processes

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If the coating layer is made thinner to improve flexibility, then folding is easier, but the protective function is reduced

Engineering Contradiction:

Improvefolding flexibilityVSAvoidprotective capability

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The coating layer is designed with non-uniform thickness, being thicker in the first and third portions and thinner in the second portion where folding occurs. This local variation in thickness allows the film to maintain protective function in non-folded areas while accommodating folding motion in the bent area without self-contact damage

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating layer applies protective function excessively in non-folded areas (thicker regions) while minimizing thickness in folding areas. This partial differentiation ensures that protection is maximized where needed while flexibility is enabled where required, resolving the contradiction between protective capability and folding flexibility

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11158822B2Display device including a coating layer having decreasing thickness

Publication Date: 2021.10.26 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a display panel that is bent with respect to a bending area. A coating layer is disposed below the display panel and may include a resin. A portion of the coating layer, which is adjacent to the bending area, may have a thickness that gradually decreases in a direction toward the bending area.