Foldable Phone Hinge Assembly Using Lightweight Conductive Door Plates

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Solution Overview

Problem

Conventional foldable smartphones face challenges in mass production due to bulky rotation shaft assemblies made of stainless steel, leading to increased weight and difficulty in carrying, which affects user comfort and experience.

Innovation Solution

The rotation shaft assembly in the foldable smartphone is made of a lightweight electrical material with a density less than 1.70 g/cm³, such as carbon fiber, and includes a flexible buffer layer and heat dissipation layer to enhance durability and thermal management, along with a middle assembly to improve display flatness and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the rotation shaft assembly is made of stainless steel to ensure structural strength, then the assembly strength is improved, but the device weight increases and portability deteriorates

Engineering Contradiction:
Improverotation shaft assembly strengthVSAvoidfoldable smartphone weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent changes the material parameter from traditional stainless steel to lightweight electrical materials such as carbon fiber composites, achieving a density reduction while maintaining structural strength through advanced material properties

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The rotation shaft assembly employs composite materials including carbon fiber reinforced polymers and metal-matrix composites that combine lightweight characteristics with high strength-to-weight ratio, resolving the contradiction between strength and weight

Inventive Principle:
Principle #40Composite materials

2Reliability

If the rotation shaft assembly is made heavier to improve structural integrity, then the assembly reliability is improved, but the ease of operation deteriorates

Engineering Contradiction:
Improverotation shaft assembly reliabilityVSAvoidportability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent optimizes material density parameters to achieve the minimum necessary weight for structural integrity while maximizing portability, using lightweight alloys and composites that maintain reliability without excessive mass

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The rotation shaft assembly is divided into modular segments with different material compositions - critical load-bearing portions use high-strength materials while non-critical portions use lightweight materials, optimizing the balance between reliability and ease of operation

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If conventional materials are used for the rotation shaft assembly, then the manufacturing simplicity is maintained, but the thermal management performance deteriorates

Engineering Contradiction:
Improveassembly manufacturing simplicityVSAvoidthermal management performance
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The patent employs composite material structures that integrate thermally conductive fillers or coatings within the lightweight material matrix, enabling effective heat dissipation from the rotation shaft assembly during operation while maintaining manufacturing feasibility

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent introduces thermal interface materials or heat dissipation layers as intermediary components between the rotation shaft assembly and the device housing, improving thermal management without significantly complicating the overall manufacturing process

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4167375B1Rotary shaft assembly and foldable screen device
Publication Date: 2026.03.11 HUAWEI TECH CO LTD
  • EP4167375B1 patent drawingFigure 1~2
  • EP4167375B1 patent drawingFigure 3
  • EP4167375B1 patent drawingFigure 4

AI summary

A rotation shaft assembly (10) and a foldable display device (100) are provided. At least one door plate (102) in the rotation shaft assembly (10) is made of a first electrical material, a density of the first electrical material is less than 1.70 g/cm3, and a second electrical material is disposed at a location on the at least one door plate (102) close to an antenna (40). This can not only improve electrical conductivity of the door plate (102), but also resolve or reduce influence of the door plate (102) on radiation performance of the antenna (40), so that the door plate (102) has good electrical conductivity in a radiation region, and mass production performance of the foldable display device (100) is improved.