Flexible Display Cover Window Thickness Gradient Manufacturing
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Solution Overview
Problem
Flexible display devices face challenges in achieving a balance between thinness for increased flexibility and impact resistance, as traditional glass cover windows become vulnerable when thinned for flexibility.
Innovation Solution
A manufacturing method for a cover window involves attaching a glass substrate to a jig with a hinge, folding it to create a bent portion, and then gradually etching the glass substrate in an etchant to form a cover window with a thickness that gradually increases from the center to the edge, enhancing both flexibility and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cover window is formed to be relatively thin, then the flexible characteristic is increased, but impact resistance decreases
Solution Approach 1:
The patent applies local quality by creating a cover window with non-uniform thickness distribution. The center region is thinned to enhance flexibility for folding operations, while the edge regions maintain greater thickness to provide impact resistance and structural support. This spatial variation in thickness allows different regions of the same component to fulfill different functional requirements.
Solution Approach 2:
The patent segments the cover window into functionally distinct regions based on thickness: a central flexible region and peripheral protective regions. This segmentation is achieved through selective etching processes that remove material from specific areas while preserving material in others, creating a multi-functional structure from a single continuous component.
2Object-affected harmful factors
If the glass substrate is etched to create thin and thick regions, then flexibility and impact resistance are improved, but the boundary between regions may become visible
Solution Approach 1:
The patent applies preliminary action by pre-forming a bent portion in the glass substrate before etching. This pre-bending creates a curvature that guides the etchant flow and ensures that the thickness transition from thin to thick regions occurs gradually. The pre-formed geometry controls the etching process to produce a smooth gradient rather than an abrupt boundary.
Solution Approach 2:
The patent uses curvature by forming a bent portion with a specific radius of curvature in the glass substrate. This curvature serves multiple purposes: it creates the desired thin region at the bend, guides the etchant flow to achieve gradual thickness transition, and ensures that the transition between thin and thick regions is smooth and visually imperceptible.
3Manufacturing precision
If gradual etching is performed from first portion to second portion, then thickness gradient is achieved, but etching uniformity becomes difficult to control
Solution Approach 1:
The patent applies preliminary action by pre-forming the bent portion geometry before etching. This pre-formed structure acts as a template that controls etchant distribution and flow patterns, ensuring that the gradual thickness transition is achieved uniformly. The predetermined curvature radius and bend geometry serve as reference features that guide the etching process.
Solution Approach 2:
The patent applies parameter changes by controlling the etching process parameters (etchant concentration, temperature, immersion time, flow rate) to match the pre-formed bent portion geometry. By adjusting these parameters, the etching rate is controlled to produce a smooth thickness gradient that follows the predetermined curvature, achieving both precision and uniformity.
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 method allows for the formation of a cover window with a predetermined thin region for flexibility and thicker regions for impact resistance, increasing the yield and stabilizing external dimensions while preventing the visibility of the boundary between thin and thick regions.
Implementation Method 1
A cover window having a thickness that gradually increases from a center to an edge is formed by wet etching the glass substrate in an etchant
Implementation Method 2
the attaching may include using an adhesive member that does not react with the etchant to attach the glass substrate to the jig
Data Source
AI summary
A manufacturing method of a cover window of a flexible display device includes attaching a glass substrate to a jig including a hinge. The jig and the glass substrate are folded around the hinge. The glass substrate is immersed in an etchant to etch the glass substrate.