Rotating Mechanism Geometry for Wrinkle-Free Foldable Displays

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Solution Overview

Problem

Existing rotating mechanisms for foldable terminals tend to stretch the display during folding, leading to wrinkles and affecting the reliability of the foldable terminal.

Innovation Solution

A rotating mechanism with a limit base, first swing arm, and second swing arm, where the rotating shaft portions include arc-shaped parts with axle centers located at the neutral layer of the display, allowing the rotation process to match the bending process of the display, reducing stretching and wrinkles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conventional rotating mechanism is used for folding, then the folding function is achieved, but the display is stretched and wrinkles appear

Engineering Contradiction:
Improvefolding functionVSAvoiddisplay quality
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the geometric parameters of the rotating mechanism by positioning the rotation axis at the neutral layer of the display and designing arc-shaped rotation paths with specific radii. This parameter adjustment ensures that the display bends along its natural neutral axis without stretching, preventing wrinkles while maintaining the folding function.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces arc-shaped rotation paths for the swing arms, where the rotation trajectory follows a circular arc centered at the neutral layer. This curvature design matches the natural bending geometry of the display, allowing smooth folding without creating stress concentrations that would cause wrinkles.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Device complexity

If the rotation axis is not aligned with the neutral layer, then the rotating mechanism is simpler, but stretching and wrinkles occur on the display

Engineering Contradiction:
Improverotating mechanism structureVSAvoiddisplay surface quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent specifies precise parameter positioning for the rotation axis at the neutral layer of the display and defines specific radius values for the arc-shaped paths. This parameter precision ensures that the rotating mechanism achieves the correct bending geometry without requiring complex additional components, balancing simplicity with manufacturing precision.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If the swing arms rotate in a straight line, then the mechanism is simpler, but the display cannot bend smoothly

Engineering Contradiction:
Improverotation path structureVSAvoiddisplay bending shape
Core Design Contradiction:
Device complexityVSShape

Solution Approach 1:

The patent replaces straight-line rotation with arc-shaped rotation paths, where the swing arms follow circular trajectories centered at the neutral layer. This curvature transformation enables the display to bend smoothly along a consistent radius, achieving the desired folded shape without creases or wrinkles.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP4210305B1Rotating mechanism and foldable terminal
Publication Date: 2025.04.02 HONOR DEVICE CO LTD
  • EP4210305B1 patent drawingFigure 1~2
  • EP4210305B1 patent drawingFigure 3
  • EP4210305B1 patent drawingFigure 4~5

AI summary

Embodiments of this application provide a rotating mechanism and a foldable terminal. The foldable terminal includes a display and the rotating mechanism. The display includes a neutral layer. The rotating mechanism includes a limit base, a first swing arm, and a second swing arm, and the limit base is provided with a first arc-shaped groove and a second arc-shaped groove. The first swing arm includes a first rotating shaft portion, and the first rotating shaft portion is slidably mounted in the first arc-shaped groove and may rotate with respect to the limit base. The second swing arm includes a second rotating shaft portion, and the second rotating shaft portion is slidably mounted in the second arc-shaped groove and may rotate with respect to the limit base. The first rotating shaft portion and the second rotating shaft portion rotate in opposite directions with respect to the limit base. The first rotating shaft portion includes a first arc-shaped part and a second arc-shaped part that are distributed in a circumferential direction of the first rotating shaft portion, the first arc-shaped part and the second arc-shaped part are fixedly connected, an axle center of the first arc-shaped part and an axle center of the second arc-shaped part are both located at the neutral layer and coincide with each other, and a radius of the first arc-shaped part is different from a radius of the second arc-shaped part.