Hinge Arm Structure for Stable Folding of Stiff Foldable Displays

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Solution Overview

Problem

Foldable electronic devices face challenges in maintaining a stable folded state due to the repulsive force from displays with increased stiffness or thickness, which can lead to defects in the folding operation.

Innovation Solution

The implementation of an arm structure and a hinge structure that provide a specified detent load, allowing for stable folding and unfolding operations without increasing the device's thickness, by utilizing a multi-detent structure and elastic bodies to resist the repulsive force of the display.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the display thickness is increased to enhance strength and resistance to external pressure, then the display strength is improved, but the repulsive force in the folded state increases which may lead to defects in the folding operation

Engineering Contradiction:
Improvedisplay strengthVSAvoidfolding operation stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The hinge structure is divided into multiple components including a first arm, second arm, and detent structure with separate functional elements. The detent structure includes a detent arm and detent protrusion that work independently to provide localized support and resistance, allowing the system to manage the repulsive force from thicker displays without compromising folding reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The detent structure provides a counteracting force (detent load) that balances the repulsive force generated by the thicker display in the folded state. The elastic body stores potential energy and releases it to create a counterbalancing moment that opposes the display's repulsive force, enabling stable folding operation despite increased display thickness and strength.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

2Strength

If the display stiffness is increased to prevent dents and wrinkles, then the display durability is improved, but the repulsive force in the folded state increases which may lead to defects in the folding operation

Engineering Contradiction:
Improvedisplay durabilityVSAvoidfolding operation stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The detent structure provides a counteracting force that balances the increased repulsive force from stiffer displays. The elastic body's restoring force creates a moment that opposes the display's repulsive force, allowing the hinge to maintain control and stability during folding operations even when the display has high stiffness to prevent dents and wrinkles.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The hinge structure's detent load parameters are specifically designed and adjusted to match the repulsive force characteristics of the display. By changing the detent load parameters (through elastic body selection or geometric adjustments), the hinge can adapt to displays with different stiffness levels, ensuring reliable folding operation while maintaining display durability.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the detent load is increased to resist the repulsive force of the display, then the folding operation stability is improved, but the device thickness increases which reduces portability

Engineering Contradiction:
Improvefolding operation stabilityVSAvoiddevice thickness
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The detent structure utilizes angular/rotational dimension rather than linear thickness to generate the required detent load. The lever arms and elastic bodies create moment forces through rotational movement, allowing high detent load to be achieved without increasing the linear thickness of the hinge structure, thus maintaining device portability while ensuring folding operation stability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The elastic body provides a dynamic detent load that adapts to the folding angle and repulsive force variations. Rather than using a static, overly robust structure that would increase thickness, the dynamic elastic response provides sufficient detent load only when needed during folding operations, maintaining thin profile while ensuring operational stability.

Inventive Principle:
Principle #15Dynamics

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

This solution enables the stable support of the folded state of the electronic device, even with displays of increased stiffness or thickness, while maintaining the portability and functionality of the device.

Implementation Method 1

a detent structure (240) connected to the rotating parts (211, 212)... an elastic body... to provide a detent load

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4128728B1Electronic device including hinge structure with arm structure
Publication Date: 2025.02.26 SAMSUNG ELECTRONICS CO LTD
  • EP4128728B1 patent drawingFigure 1a
  • EP4128728B1 patent drawingFigure 1b~1c
  • EP4128728B1 patent drawingFigure 2

AI summary

An arm structure of an electronic device is provided. The arm structure includes an arm body, a first cam disposed on one side of the arm body and including a first hole into which at least a portion of a rotating shaft providing a folding operation of the electronic device is inserted, a peak and a valley being formed around the first hole, a second cam arranged side-by-side on a same axis as the one side of the arm body, spaced apart from the first cam, and including a second hole into which at least a portion of the rotating shaft is inserted, a peak and a valley being formed around the second hole, and a connecting part disposed on another side of the arm body and fastened with a rotating part providing rotation of the electronic device.