Foldable Screen Coupling Linkage for Wrinkle Compensation

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Solution Overview

Problem

Foldable screens in mobile terminals often develop wrinkles due to differences in the thickness and dimensions of their front and back surfaces when folded, leading to potential damage and impaired functionality.

Innovation Solution

A coupling device with a middle frame fixing member, transmission assemblies, and a linkage system that converts rotational motion into linear motion, ensuring accurate compensation of the screen's length during folding to prevent wrinkles and extend its lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a hinge for coupling two middle frames is arranged at a position where a screen is folded, then the screen can be folded, but wrinkles are formed in the screen due to different lengths of front surface and back surface

Engineering Contradiction:
Improvefolding functionVSAvoidwrinkles in screen
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a coupling device as an intermediary mechanism between the hinge and the screen. This device includes a first transmission assembly with a first transmission member having a first helical tooth portion, a second transmission member with a second helical tooth portion, and a second transmission assembly with a synchronization member, shaft sleeve, and linkage. These intermediary components convert the rotational motion of the hinge into precise linear motion to compensate for the length difference between the front and back surfaces of the screen during folding, thereby preventing wrinkle formation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent utilizes the parameter change of helical gear ratios to achieve differential motion compensation. The first helical tooth portion and second helical tooth portion are designed with specific gear ratios that change during rotation, allowing the coupling device to dynamically adjust the relative positions of the middle frames. This parameter change enables the system to compensate for the varying length difference between screen surfaces as the folding angle changes.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the screen is folded without length compensation, then folding is achieved, but the screen may be damaged due to wrinkle formation

Engineering Contradiction:
Improvefolding capabilityVSAvoidscreen durability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The coupling device performs preliminary action by pre-compensating for the length difference between the front and back surfaces of the screen before the folding process completes. The transmission assemblies are designed to anticipate and counteract the wrinkle-forming forces that would otherwise develop during folding, thereby protecting the screen from damage before it occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The coupling device acts as a protective intermediary mechanism that absorbs and manages the mechanical stresses generated during folding. By introducing this intermediate system with multiple transmission components, the patent prevents direct transmission of harmful forces to the screen, thereby enhancing screen durability while maintaining folding capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If a coupling device with transmission assemblies is introduced to compensate screen length, then wrinkles are prevented, but the device complexity increases

Engineering Contradiction:
Improvewrinkle preventionVSAvoidcoupling device structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges multiple transmission functions into a single integrated coupling device. The first transmission assembly and second transmission assembly are combined with the hinge mechanism, sharing common components such as the middle frames and coupling members. This merging approach reduces the overall number of separate components and simplifies the device structure while maintaining the wrinkle prevention function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coupling device is designed with multi-functionality, where the same transmission assemblies serve both to enable folding motion and to compensate for screen length differences. The helical gear mechanisms simultaneously provide motion transmission and differential adjustment, eliminating the need for separate compensation mechanisms and thereby reducing device complexity.

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

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

The coupling device effectively prevents wrinkles and prolongs the service life of the screen by accurately adjusting the screen's length during folding, ensuring smooth operation and durability.

Implementation Method 1

a second transmission assembly having a first end hinged to the first transmission assembly at a first hinge center and having a second end slidably coupled to the first transmission assembly. A rotation center of the first transmission assembly does not coincide with the first hinge center, and the second transmission assembly converts a rotation action of the first transmission assembly into a moving action along a second direction

Methodology Applied
Scientific EffectMechanical linkage: Four-Bar Linkage

Implementation Method 2

a third transmission assembly having a first end hinged to the second transmission assembly and having a second end and a third end both slidably coupled to the middle frame fixing member. The second end and the third end of the third transmission assembly are on two sides of the first end of the third transmission assembly, and the third end of the third transmission assembly pushes the middle frame fixing member to move towards a first side facing away from the first transmission assembly or a second side towards the first transmission assembly

Methodology Applied
Scientific EffectMechanical force transmission: Lever

Data Source

PatentEP4187354A1Coupling device and terminal equipment
Publication Date: 2023.05.31 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4187354A1 patent drawingFigure 1~2
  • EP4187354A1 patent drawingFigure 3~4
  • EP4187354A1 patent drawingFigure 5~6

AI summary

A coupling device (100) includes a middle frame fixing member (2), a first transmission assembly (3), a second transmission assembly (4) and a third transmission assembly (5). The first transmission assembly (3) is rotatable relative to the middle frame fixing member (2) during rotation of the middle frame fixing member. The second transmission assembly (4) has a first end hinged to the first transmission assembly and a second end slidably coupled to the first transmission assembly, and the second transmission assembly (4) converts a rotation action of the first transmission assembly into a moving action along a second direction. A third end of the third transmission assembly (5) pushes the middle frame fixing member to move towards a first side facing away from the first transmission assembly (3) or a second side towards the first transmission assembly during the rotation of the middle frame fixing member (2).