Axial Hinge Transmission for Foldable Screens Under Outward Bending

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Solution Overview

Problem

Flexible screens in foldable electronic devices are prone to damage during folding due to excessive stretching or creasing, leading to a shortened service life.

Innovation Solution

The electronic device employs a first housing and a second housing that rotate relative to each other through a shaft assembly, with a transmission member driven by a pushing portion and guide surfaces to prevent screen assembly damage during folding by moving sections of the screen assembly relative to each other.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the foldable electronic device is folded inwards with a small bending radius at the hinge position, then the device can be compactly stored, but the flexible screen is creased or damaged due to excessive squeezing

Engineering Contradiction:
Improvecompact storage volumeVSAvoidscreen assembly integrity
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The screen assembly is divided into a first screen portion and a second screen portion that can move relative to each other. During folding, the first screen portion moves toward the second screen portion, reducing the bending radius and preventing excessive squeezing that would damage a single continuous screen.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The screen assembly is designed with dynamic movement capability where the first screen portion can move toward the second screen portion during the folding process. This dynamic adjustment allows the screen to adapt to the folding motion, reducing stress concentration and preventing creasing or damage at the hinge position.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the foldable electronic device is folded outwards with a large bending radius at the hinge position, then the device can be easily accessed, but the flexible screen is excessively stretched and deformed, or even cracked

Engineering Contradiction:
Improvedevice accessibilityVSAvoidscreen assembly integrity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

By segmenting the screen into movable portions, the patent eliminates excessive stretching during outward folding. The first and second screen portions move relative to each other, distributing the mechanical stress and preventing the screen material from being overstretched or cracked.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The dynamic movement mechanism allows the screen assembly to adjust during outward folding, with the first screen portion moving toward the second screen portion. This dynamic adjustment prevents excessive stretching and deformation that would occur in a fixed screen design.

Inventive Principle:
Principle #15Dynamics

3Strength

If a traditional rigid hinge structure is used for folding, then the mechanical strength is sufficient, but the screen assembly is damaged easily due to fixed bending radius

Engineering Contradiction:
Improvehinge mechanical strengthVSAvoidscreen assembly durability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent replaces the fixed rigid hinge with a dynamic system where the first screen portion can move toward the second screen portion during folding. This dynamic mechanism allows the bending radius to adjust during the folding process, reducing stress concentration and preventing screen damage while maintaining sufficient mechanical strength.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the bending radius parameter dynamically during the folding process by allowing the first screen portion to move toward the second screen portion. This parameter adjustment optimizes the stress distribution, preventing screen damage while maintaining the mechanical strength needed for reliable folding operation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4407961B1Electronic device
Publication Date: 2025.08.06 VIVO MOBILE COMM CO LTD
  • EP4407961B1 patent drawingFigure 1~2
  • EP4407961B1 patent drawingFigure 3
  • EP4407961B1 patent drawingFigure 4

AI summary

An electronic device is disclosed. The electronic device includes a first housing (100), a second housing (200), a screen assembly (300), a shaft assembly (400), and a transmission member (500). The first housing and the second housing are in rotational fit with each other through the shaft assembly. The transmission member sleeves on the shaft assembly. The transmission member is capable of moving in an axial direction of the shaft assembly. The first housing is provided with a first pushing portion (210). The transmission member is provided with a first guide surface (510). The first pushing portion is abutted on the first guide surface. A first section and a second section of the screen assembly are disposed in the first housing and the second housing, respectively. The first section is in sliding fit with the first housing. One of the transmission member and the screen assembly is provided with a second pushing portion (520). The other one of the transmission member and the screen assembly is provided with a second guide surface (310). The second guide surface is disposed aslant relative to the shaft assembly. In a process of folding the electronic device outwards, the first pushing portion drives the transmission member to move in the axial direction, and drives, through the transmission member, the first section of the screen assembly to move, thereby preventing the screen assembly from being stretched.