Foldable Display Hinge Assembly With Virtual Axis Gears
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Solution Overview
Problem
Foldable display devices face challenges in maintaining a specific folding angle due to reduced holding force over time and increased thickness, which affects durability and weight-bearing capacity.
Innovation Solution
A foldable display device with a new hinge structure incorporating a 2-axis rotation mechanism, 4-axis gear, link slider, cam structure with compression springs, and leaf springs to enhance holding torque and free stop function, ensuring durability and reduced thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 4-axis gear is used to implement a folding hinge, then the hinge can maintain folding angle, but the thickness increases and durability decreases
Solution Approach 1:
The hinge assembly is divided into multiple functional components: a first hinge arm and second hinge arm for rotation, virtual axis gears for motion control, rotational gears for transmission, and gear arms for synchronization. This segmentation allows each component to be optimized independently, reducing overall thickness while maintaining durability through specialized functions.
Solution Approach 2:
The patent transitions from a traditional 4-axis gear configuration to a 2-axis rotation structure with virtual axis gears. By changing the dimensional arrangement of rotation axes and using meshing gears between virtual axes, the hinge achieves comparable durability with reduced thickness in the critical direction.
2Reliability
If friction-based holding force is used to maintain folding angle, then the hinge structure is simple, but holding force decreases over time
Solution Approach 1:
The patent introduces cam structures with compression springs that change geometric parameters during operation. The cam profiles are designed to provide varying normal forces that compensate for friction degradation, maintaining consistent holding force throughout the hinge's operational life without significantly increasing structural complexity.
Solution Approach 2:
Compression springs are introduced as intermediary elements between the cam structures and hinge arms. These springs provide additional holding force and compensate for friction losses, acting as a mediator that maintains reliable angle positioning without requiring a complete redesign of the hinge structure.
3Length of stationary object
If gear size is reduced to achieve small thickness, then thickness decreases, but durability becomes defective
Solution Approach 1:
The patent employs nested gear arrangements where rotational gears mesh between virtual axis gears, and gear arms interlock with multiple gear components. This nesting allows compact thickness while maintaining adequate gear sizes for durability through multi-stage motion transmission and force distribution.
Solution Approach 2:
The hinge assembly combines multiple materials and structural approaches: metallic gears for durability, plastic components for lightweighting, and spring elements for force maintenance. This composite approach allows reduced thickness while preserving gear durability through material optimization in critical areas.
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 solution maintains a consistent holding force, improves durability, and reduces thickness, addressing the limitations of existing foldable display devices while supporting a specific folding angle and weight-bearing capacity.
Implementation Method 1
cam structure including compression springs
Implementation Method 2
compression springs
Implementation Method 3
assisting the free stop function through applying leaf springs
Implementation Method 4
holding force using friction between components
Data Source
AI summary
A foldable display device includes a first support plate and a second support plate, a display panel disposed on the first support plate and the second support plate and a hinge assembly disposed between the first support plate and the second support plate, wherein the hinge assembly includes, a first hinge arm and a second hinge arm rotatably connected to each other, a first virtual axis gear coupled to the first hinge arm, a second virtual axis gear coupled to the second hinge arm, a first rotational gear and a second rotational gear disposed to mesh with each other between the first virtual axis gear and the second virtual axis gear and a first gear arm and a second gear arm fastened to interlock with the first virtual axis gear and the second virtual axis gear, wherein the first support plate, the second support plate, and the display panel perform folding and unfolding operations about a rotation axis different from central axes of the first virtual axis gear and the second virtual axis gear.