Cover Window Segmentation for Wearable Display Hardness and Moldability
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Solution Overview
Problem
Wearable devices require a cover window that combines high hardness with versatility in form factors, but existing materials like sapphire are difficult to mold into complex shapes due to their hardness, limiting the depth and design possibilities.
Innovation Solution
A cover window composed of multiple parts with different hardness levels, where the high-hardness sapphire is used for the front part and more moldable materials like tempered glass or ceramic for the side parts, bonded directly with a thin interface, allowing for various form factors and sufficient depth without visible seams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-hardness sapphire material is used for the cover window, then scratch resistance and surface hardness are improved, but the ability to mold into complex shapes and achieve diverse form factors deteriorates
Solution Approach 1:
The cover window is divided into multiple parts with different hardness levels: a front part made of high-hardness sapphire material and side parts made of more moldable materials such as tempered glass or ceramic. This segmentation allows each part to be optimized for its specific function - the front part for scratch resistance and the side parts for complex molding and form factor versatility.
Solution Approach 2:
Different regions of the cover window are assigned different material properties - the front part uses high-hardness sapphire for maximum scratch resistance where the display surface is most vulnerable, while the side parts use materials with lower hardness but better moldability to achieve complex curved shapes and diverse form factors.
2Adaptability or versatility
If deep side parts are created to accommodate complex designs, then form factor versatility is improved, but the structural integrity and molding difficulty increase
Solution Approach 1:
The cover window is segmented into a front part and side parts that can be manufactured separately and then bonded together. This allows the side parts to be designed with deep, complex shapes for versatile form factors while maintaining structural integrity through the bonding process, avoiding the need to mold the entire deep structure from a single piece of material.
Solution Approach 2:
The cover window uses a composite structure combining sapphire front part with tempered glass or ceramic side parts. This composite approach enables the side parts to achieve deep, complex geometries for diverse form factors while the overall structure maintains strength through the combination of materials and the bonding interface.
3Ease of manufacture
If multiple materials with different hardness levels are bonded, then moldability and form factor versatility are improved, but the bonding interface complexity and manufacturing precision requirements increase
Solution Approach 1:
A bonding interface is introduced between the sapphire front part and the tempered glass or ceramic side parts. This bonding interface serves as an intermediary that connects materials with different hardness levels and manufacturing requirements, allowing each part to be molded separately with optimal precision for its material properties while achieving a unified final structure.
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 provides a high-hardness cover window that can be molded into diverse shapes while maintaining superior optical and surface hardness properties, enhancing scratch resistance and appearance, and accommodating complex designs without compromising on material quality.
Implementation Method 1
The first part and the second part may be directly bonded after bonding surfaces of the first part and the second part are activated by plasma.
Implementation Method 2
A thickness of a bonding interface between the first part and the second part of the cover window may be less than or equal to about 100 nm.
Data Source
AI summary
A display device according to an embodiment includes a display panel and a cover window disposed at a front of the display panel and including a front part and a side part that surrounds the front part and is at least partially curved, the cover window includes the front part and a second part including at least a portion of the side part, and the first part and the second part are directly bonded, and the first part has a greater hardness than the second part.