Foldable Device Rotary Shaft Assembly for Low-Pressure Screen Folding

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Solution Overview

Problem

Existing foldable electronic devices face challenges in efficiently switching between folded and unfolded states without damaging the flexible display, due to inadequate hinge mechanisms that apply excessive pressure on the screen.

Innovation Solution

A rotary shaft apparatus with a first transmission assembly connected to a base plate and a second transmission assembly driven by a first supporting member, allowing for integral rotation relative to the base plate without additional transmission structures, thereby enhancing response speed and reducing material costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional hinge mechanisms are used to switch between folded and unfolded states, then the device can achieve portability and display functionality, but the hinge applies excessive pressure on the flexible display causing damage risk

Engineering Contradiction:
Improvescreen damage riskVSAvoidpressure on display
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The hinge mechanism is divided into multiple components: a first hinge component connected to the first housing, a second hinge component connected to the second housing, and a linkage component connecting the two hinge components. This segmentation allows the force to be distributed across multiple connection points rather than concentrated on the display, reducing the pressure applied to the flexible display during folding operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The linkage component acts as an intermediary between the first and second hinge components. It transmits the folding force indirectly through the hinge components to the housings, rather than applying force directly to the display. This intermediary mechanism protects the display from excessive pressure while still enabling the folding motion.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If additional transmission structures are added to the rotary shaft apparatus, then the transmission function is improved, but the device complexity and material costs increase

Engineering Contradiction:
Improvefolding speedVSAvoidtransmission structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The first and second hinge components are integrally formed as a single rotary shaft assembly, combining multiple transmission functions into one unified structure. This merging eliminates the need for separate transmission components while maintaining the synchronized folding capability, thereby reducing device complexity and material costs without sacrificing folding speed.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The rotary shaft assembly serves multiple functions simultaneously: it acts as the rotational joint for folding, provides the transmission mechanism for synchronized motion, and structurally connects the two housings. This multi-functionality eliminates the need for additional dedicated transmission structures, simplifying the overall device design.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4254916B1Rotary shaft apparatus and foldable electronic device
Publication Date: 2025.06.11 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4254916B1 patent drawingFigure 1~2
  • EP4254916B1 patent drawingFigure 3~4
  • EP4254916B1 patent drawingFigure 5~6

AI summary

The disclosure provides a rotary shaft apparatus and a foldable electronic device, and belongs to the technical filed of terminal. The rotary shaft apparatus includes a base plate (10) and a rotary shaft assembly (20); the rotary shaft assembly (20) includes a first transmission assembly (21), a second transmission assembly (23) and a first supporting member (22); the first transmission assembly (21) is rotatably connected to the base plate (10) around a first axial direction; the first supporting member (22) is rotatably connected to the first transmission assembly (21) around a second axial direction parallel to the first axial direction, and is movably connected to the second transmission assembly (23); the second transmission assembly (23) is rotatably connected to the base plate (10) around a third axial direction parallel to the first axial direction.