Step Covering Layer for Flexible Display Surface Uniformity
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Solution Overview
Problem
Flexible display devices with touch input capabilities face issues due to uneven protective films caused by level differences in digitizer layers, leading to visible irregularities when high luminance light is applied, especially when no image is displayed.
Innovation Solution
A display device design incorporating a step covering layer with a metal plate and a non-metal plate, where the metal plate overlaps the folding area and the non-metal plate is disposed on the surface of the metal plate, maintaining a constant thickness across folding and non-folding areas to smooth out surface irregularities and prevent visibility of uneven shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a protective film is disposed on the digitizer layer with level differences, then the digitizer layer can sense touch input, but the protective film develops an uneven shape that is visible when high luminance light is illuminated
Solution Approach 1:
The step covering layer is divided into multiple segments: a first step covering layer portion covering the folding area, a second step covering layer portion covering the non-folding area, and a third step covering layer portion connecting them. Each segment has different thickness characteristics tailored to its specific function, allowing the folding area to maintain flexibility while the non-folding area provides surface uniformity.
Solution Approach 2:
Different regions of the step covering layer have different thickness properties: the first step covering layer portion has greater thickness to accommodate the folding area's flexibility requirements, while the second step covering layer portion has smaller thickness to provide a flat surface in the non-folding area. This local differentiation resolves the contradiction between flexibility and surface uniformity.
2Adaptability or versatility
If the display device uses a flexible material to enable bending and folding, then portability and space utilization are improved, but the protective film becomes uneven due to level differences in the digitizer layer
Solution Approach 1:
The step covering layer is segmented into distinct portions with different thickness characteristics. The first portion covers the folding area with greater thickness to maintain flexibility, while the second portion covers the non-folding area with smaller thickness to ensure surface flatness, resolving the contradiction between adaptability and shape uniformity.
Solution Approach 2:
The step covering layer acts as an intermediary structure between the flexible display panel and the protective film. It mediates the conflict between flexibility and flatness by providing a thickness gradient that transitions from the folding area to the non-folding area, allowing both properties to coexist.
3Ease of manufacture
If the step covering layer uses a single material, then manufacturing is simplified, but it cannot simultaneously provide both flexibility in the folding area and surface uniformity in the non-folding area
Solution Approach 1:
The step covering layer is constructed as a composite structure with multiple portions having different thickness characteristics. This composite design allows the first portion to provide flexibility for folding while the second portion ensures surface uniformity, achieving both functional requirements through material structure differentiation.
Data Source
AI summary
A display device includes: a display panel including a folding area and a first non-folding area extended from a first folding line located on a first side of the folding area; a digitizer layer disposed on the display panel and including electrode patterns; and a step covering layer disposed between the display panel and the digitizer layer, wherein the step covering layer includes a first metal plate, a second metal plate, and a first non-metal plate, wherein the first metal plate overlaps the folding area, wherein the second metal plate overlaps the first non-folding area, and wherein the first non-metal plate overlaps the first non-folding area and is disposed on a first surface of the second metal plate.