Foldable Display Pages with Bend Limit Layer

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Solution Overview

Problem

Modern computing devices face challenges in balancing portability and functionality with foldable displays, as they often result in either an unwieldy large or too small form factor, and folding thin displays can damage sensitive components like TFTs and OLEDs due to small radius bends.

Innovation Solution

A computing device with a spine member housing memory and processor, featuring display pages that rotate about an axis, and incorporating a bend limit layer to restrict bending to a minimum radius, preventing damage to display components and allowing for easy switching between folded and unfolded configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a foldable flexible display is used to achieve a small form factor when folded, then the device becomes portable, but the unfolded configuration becomes too large and unwieldly

Engineering Contradiction:
Improveform factorVSAvoidusability
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The display is divided into multiple independent display pages that can be folded along with spines. Each page contains separate OLED displays on opposite sides, allowing the display to be segmented into manageable sections that can be folded without creating an excessively large unfolded form factor.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple display pages are nested together like book pages, with each page containing display elements. When folded, the pages nest within each other along the spine, creating a compact form factor while maintaining the ability to display content on multiple surfaces.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Volume of moving object

If a thin display is used to keep the device small and slim, then portability is improved, but small radius bends at the fold damage sensitive components like TFTs and OLEDs

Engineering Contradiction:
ImprovethicknessVSAvoidcomponent durability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

A bend limit layer is incorporated into the display structure beforehand to prevent excessive bending. This layer acts as a mechanical constraint that stops the display from bending beyond a safe radius, protecting sensitive components like OLEDs and TFTs from damage before damage can occur.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The display utilizes thin film structures including OLED layers and encapsulation layers that are inherently flexible but can be protected from excessive stress. The bend limit layer works in conjunction with these thin films to allow necessary flexibility while preventing damage.

Inventive Principle:
Principle #30Flexible shells and thin films

3Reliability

If the display is made thick to protect components from bending damage, then reliability is improved, but the device becomes bulky and less portable

Engineering Contradiction:
Improvecomponent protectionVSAvoidthickness
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

Instead of using thick rigid structures to protect components, the invention employs thin flexible film layers including OLED layers, encapsulation layers, and a bend limit layer. These thin films provide component protection through their layered structure and mechanical properties without increasing overall device thickness.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The display structure uses composite material layers including flexible substrates, OLED layers, encapsulation layers, and bend limit layers. Each layer contributes specific protective or functional properties, allowing thin overall construction while maintaining component protection through the composite structure.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3616025B1Foldable display devices with multiple pages
Publication Date: 2023.12.06 GOOGLE LLC
  • EP3616025B1 patent drawingFigure 1~2
  • EP3616025B1 patent drawingFigure 3~4
  • EP3616025B1 patent drawingFigure 5

AI summary

A computing device includes memory configured for storing executable instructions, a processor configured for executing the instructions, a spine member, where the spine member includes the memory and the processor, and a plurality of display pages, each display page coupled at a first edge of the page to the spine member and having a second edge, opposite the first edge that is free to rotate about an axis defined by the spine member, wherein at least one page includes two separately controllable OLED displays on opposite sides of the page.