Foldable Display Hinge Cam Structure Against Restoring Force

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Solution Overview

Problem

Foldable electronic devices with flexible displays face issues with maintaining a desired folded state due to increased restoring forces, which can lead to defects in folding and unfolding motions.

Innovation Solution

A hinge structure that includes a fixed portion, rotary portions, arm shafts, arms with cams, and elastic members to provide torque that cancels out the restoring force of the display, allowing stable maintenance of a folded state without increasing the device's thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the size of the flexible display is increased to provide a wide screen, then the screen area is improved, but the restoring force in the folded state increases causing defects in folding motion

Engineering Contradiction:
Improvedisplay areaVSAvoidrestoring force
Core Design Contradiction:
Area of stationary objectVSForce

Solution Approach 1:

The hinge structure generates counter-torque through cam mechanisms that act against the restoring force of the flexible display. The cam profiles are designed to produce sufficient counter-torque to balance the increased restoring force from larger displays, enabling stable folding motion and maintaining desired folded states without unintended unfolding.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

2Area of stationary object

If the restoring force is increased due to larger display size, then the screen area is improved, but the stability of the folded state deteriorates

Engineering Contradiction:
Improvedisplay areaVSAvoidfolded state stability
Core Design Contradiction:
Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The hinge structure generates counter-torque through cam mechanisms that act against the restoring force of the flexible display. The cam profiles are designed to produce sufficient counter-torque to balance the increased restoring force from larger displays, enabling stable folding motion and maintaining desired folded states without unintended unfolding.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The hinge structure uses dynamic cam mechanisms that adjust the counter-torque based on the folding angle and position. The cam profiles vary the mechanical advantage throughout the folding range, providing optimal counter-torque at different stages of folding to maintain stability across the entire motion range.

Inventive Principle:
Principle #15Dynamics

3Stability of the object's composition

If a hinge structure with multiple cams and elastic members is added to counteract restoring force, then the folded state stability is improved, but the device complexity increases

Engineering Contradiction:
Improvefolded state stabilityVSAvoidhinge structure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The hinge structure integrates multiple functions into a unified mechanism. The cam mechanisms simultaneously generate counter-torque to balance restoring force, guide the folding motion along a specific trajectory, and work with elastic members to provide damping and stability. This merging of functions reduces the need for separate components for each purpose.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cam mechanisms serve multiple purposes: generating counter-torque to counteract restoring force, guiding the folding motion trajectory, and working with elastic members to provide damping. This multi-functionality reduces the overall number of components needed compared to having separate mechanisms for each function.

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 hinge structure ensures a stable folding motion and maintains the desired folded state by providing sufficient torque to counteract the restoring force of the display, preventing unintended unfolding motions.

Implementation Method 1

a first elastic member coupled to the first arm shaft and configured to apply an elastic force in the axial direction, a second elastic member coupled to the second arm shaft and configured to apply an elastic force in the axial direction

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 2

a hinge structure for providing torque capable of cancelling out a restoring force of a display

Methodology Applied
Scientific EffectTorque: Torque

Implementation Method 3

The hinge structure includes: a fixed portion, a first rotary portion coupled to the fixed structure to be rotatable about a first axis of rotation and connected to the first housing, a second rotary portion coupled to the fixed portion to be rotatable about a second axis of rotation and connected to the second housing

Methodology Applied
Scientific EffectMechanical advantage: Mechanical Advantage

Data Source

PatentEP4194994B1Hinge structure and electronic device comprising same
Publication Date: 2024.12.18 SAMSUNG ELECTRONICS CO LTD
  • EP4194994B1 patent drawingFigure 1
  • EP4194994B1 patent drawingFigure 2A
  • EP4194994B1 patent drawingFigure 2B

AI summary

An electronic device includes a housing including a first housing and a second housing, a display extending from the first housing to the second housing, and a hinge structure including a hinge connected to the first housing and the second housing. The hinge structure includes: a fixed portion, a first rotary portion coupled to the fixed structure to be rotatable about a first axis of rotation and connected to the first housing, a second rotary portion coupled to the fixed portion to be rotatable about a second axis of rotation and connected to the second housing, the first axis of rotation and the second axis of rotation extending parallel to an axial direction, a first arm shaft rotatably coupled to the fixed portion and parallel to the axial direction, a second arm shaft rotatably coupled to the fixed portion and parallel to the axial direction, a first arm coupled to the first arm shaft and configured to rotate together with the first arm shaft and including a first arm cam formed around the first arm shaft, a second arm coupled to the second arm shaft and configured to rotate together with the second arm shaft and including a second arm cam formed around the second arm shaft, a first elastic member coupled to the first arm shaft and configured to apply an elastic force in the axial direction, a second elastic member coupled to the second arm shaft and configured to apply an elastic force in the axial direction.