Foldable Display Hinge Structure for Thin Dust-Resistant Folding

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Solution Overview

Problem

Existing foldable display devices face challenges in achieving a small thickness while maintaining durability and preventing foreign material ingress, especially when using a 4-axis gear hinge structure.

Innovation Solution

A foldable display device with a new hinge structure featuring two bevel gears and a link slider for synchronous biaxial rotation, along with a cam structure incorporating compression springs for enhanced holding torque and free stop function, and foreign material inflow prevention elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a 4-axis gear hinge structure is used, then the foldable display device can achieve folding functionality, but the thickness increases and durability decreases

Engineering Contradiction:

Improvefolding functionalityVSAvoidthickness

Core Design Contradiction:

Ease of operationVSLength of stationary object

Solution Approach 1:

The patent combines multiple gear functions into a single integrated hinge structure. The hinge assembly integrates the hinge arm, gear arm, bevel gears, and link slider into one unified component that performs both folding and synchronization functions, eliminating the need for separate 4-axis gear mechanisms and reducing overall thickness.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from a conventional planar gear arrangement to a biaxial rotation structure that operates in multiple dimensions. The bevel gears enable rotation around two perpendicular axes simultaneously, allowing the hinge to achieve complex folding movements without increasing thickness in the vertical dimension.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Length of stationary object

If gear size is reduced to achieve small thickness, then thickness decreases, but durability reduces and defect rate increases

Engineering Contradiction:

ImprovethicknessVSAvoiddurability

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

The hinge assembly uses composite structural design combining multiple materials and components. The hinge arm and gear arm are made from durable materials with appropriate mechanical properties, while the bevel gears provide precise engagement. This composite approach maintains strength and durability despite the reduced overall thickness of the hinge assembly.

Inventive Principle:

Principle #40Composite materials

3Force

If friction-based holding force is used, then holding force is initially sufficient, but it decreases with continuous folding and unfolding operations

Engineering Contradiction:

Improveholding forceVSAvoidoperational lifespan

Core Design Contradiction:

ForceVSDuration of action of stationary object

Solution Approach 1:

The patent incorporates compression springs that dynamically adjust the holding force based on operational conditions. As the hinge undergoes continuous folding and unfolding, the springs maintain optimal contact pressure between friction surfaces, compensating for wear and ensuring consistent holding force throughout the device's operational lifespan.

Inventive Principle:

Principle #15Dynamics

4Ease of manufacture

If the hinge structure is simplified, then manufacturing becomes easier, but foreign material ingress increases causing damage

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidforeign material ingress

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent uses the hinge arm itself as a flexible sealing element that moves with the folding motion. This flexible barrier follows the contours of the hinge assembly and maintains contact with the housing, creating an effective seal against foreign material ingress without requiring complex rigid sealing structures that would complicate manufacturing.

Inventive Principle:

Principle #30Flexible shells and thin films

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 solution enables a foldable display device with improved impact resistance, durability, and holding force, while maintaining a minimal thickness and preventing foreign material ingress.

Implementation Method 1

a cam structure including compression springs

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

holding force using friction between components constituting a hinge

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12324113B2Foldable display device including a foreign material inflow prevention element

Publication Date: 2025.06.03 LG DISPLAY CO LTD

AI summary

A foldable display device includes a first support plate and a second support plate, a display panel disposed on the first support plate and the second support plate and a hinge assembly disposed between the first support plate and the second support plate, the hinge assembly includes a hinge arm, a gear arm coupled to the hinge arm, an inner frame disposed under the hinge arm and the gear arm and fixing the hinge arm and the gear arm, a hinge housing accommodating the inner frame, the hinge arm, and the gear arm, under the inner frame, and a foreign material inflow prevention element interposed between the hinge housing and the inner frame and connected to the hinge arm to operate together with folding of the hinge arm when the hinge arm is folded.