Foldable Substrate Layout for Reliable Multi-Hinge Connections

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Solution Overview

Problem

There is a trade-off between the display size and the compactness of electronic devices, as larger displays are required for multimedia services but compromise the device's portability.

Innovation Solution

A foldable electronic device design with a hinge structure allowing the device to be unfolded for a larger display and folded for convenience, incorporating flexible circuit boards to connect components across the folding axis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a foldable electronic device is bent or folded, then the device can be compacted for portability, but the connection between the first substrate and second substrate may be damaged due to stress concentration at the bent portion

Engineering Contradiction:
ImprovecompactnessVSAvoidconnection reliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The connection structure is divided into multiple connection portions distributed across the first and second substrates. This segmentation distributes the stress concentration that occurs during folding, preventing any single connection point from bearing excessive stress that could damage the connection between substrates.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Connection portions are strategically positioned at specific locations including the bent portion and non-bent portions of the substrates. This local distribution ensures that connections are present where stress occurs during folding, while maintaining overall connection reliability across the entire device structure.

Inventive Principle:
Principle #3Local quality

2Device complexity

If connection portions are positioned only at non-bent portions of the substrate, then the connection structure is simpler, but the connection reliability is insufficient when the device is folded

Engineering Contradiction:
Improveconnection structure complexityVSAvoidconnection reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

Connection portions are pre-positioned at locations that will experience stress during the folding operation. By anticipating the stress distribution pattern when the device is bent, the connection structure is designed in advance to place connection portions exactly where they are needed to maintain reliability during folding.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the transparent conductive layer has high work function, then the hole injection efficiency is improved, but the electron barrier increases making electron injection difficult

Engineering Contradiction:
Improvehole injection efficiencyVSAvoidelectron barrier
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The work function of the transparent conductive layer is optimized to a specific range (4.0 eV to 4.7 eV) rather than maximizing it. This parameter optimization balances two competing requirements: maintaining sufficiently high hole injection efficiency while keeping the electron barrier at an acceptable level, achieving overall device performance optimization.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Different materials with specific work function characteristics are selected for the transparent conductive layer based on their local function requirements. Materials such as ITO, IZO, or IGZO are chosen to provide the appropriate electrical properties at this specific interface location, balancing hole injection and electron barrier considerations.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4344175B1Foldable electronic device comprising substrate portion
Publication Date: 2026.04.08 SAMSUNG ELECTRONICS CO LTD
  • EP4344175B1 patent drawingFigure 1
  • EP4344175B1 patent drawingFigure 2
  • EP4344175B1 patent drawingFigure 3

AI summary

An comprises a housing including a first housing and a second housing, a display disposed on the first housing and the second housing, a hinge structure configured to connect the first housing and the second housing and including a first hinge, a second hinge, and a third hinge positioned between the first hinge and the second hinge, a battery disposed in the first housing, a board unit including a first circuit board disposed in the first housing and including a main area being at least partially positioned on an upper portion of the battery and having a second width and an extension area extending from the main area and having a first width shorter than the second width and a second circuit board disposed in the second housing, a connecting structure configured to electrically connect the first circuit board and the second circuit board and including a first connection member being at least partially positioned between the first hinge and the third hinge and a second connection member being at least partially positioned between the second hinge and the third hinge, and at least one electronic component positioned between the third hinge and the battery and disposed on the extension area.