Glass Substrate Compaction Control via Cooling Rate Optimization
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Solution Overview
Problem
The challenge in glass substrate manufacturing for liquid crystal displays (LCDs) is the compaction issue, which arises due to thermal cycling, especially during the processing of polycrystalline-silicon thin film transistors, leading to alignment problems and increased manufacturing costs, as existing methods require lengthy heat treatments and significant experimentation to control compaction effectively.
Innovation Solution
A method involving measuring and correlating compaction with cooling rates to predict and minimize compaction by iteratively modifying cooling curves, using regression analysis to determine target cooling rates that minimize compaction, thereby optimizing the glass substrate's thermal stability and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pre-shrinking heat treatment is applied to reduce compaction, then glass substrate dimensional stability is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent applies preliminary action by incorporating compaction control directly into the glass forming process through optimized cooling rates, rather than requiring separate post-forming heat treatments. The cooling curve is designed to pre-establish the desired dimensional stability, eliminating the need for subsequent pre-shrinking treatments and reducing total manufacturing time.
Solution Approach 2:
The patent extracts the compaction control function from the separate pre-shrinking heat treatment process and integrates it into the glass forming process itself. By taking out the dimensional stability control from a post-processing step and embedding it in the forming stage, the method eliminates redundant handling and reduces manufacturing time while maintaining quality.
2Stability of the object's composition
If draw distance is increased to reduce compaction, then glass substrate dimensional stability is improved, but manufacturing space and capital requirements increase
Solution Approach 1:
The patent applies parameter changes by modifying the cooling rate parameters during the glass forming process to control compaction. Instead of increasing the physical draw distance, the method changes the thermal parameters (cooling rates at different temperature ranges) to achieve the desired dimensional stability, thereby reducing the need for additional manufacturing space.
Solution Approach 2:
The patent transitions from controlling compaction through spatial extension (increasing draw distance) to controlling it through thermal parameter adjustment (cooling rates). This dimensional shift from space-based control to parameter-based control allows compaction management without expanding the manufacturing footprint.
3Manufacturing precision
If polynomial regression analysis is used to predict compaction, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The patent replaces complex experimental trial-and-error methods with polynomial regression analysis based on cooling rate parameters. This substitution uses mathematical modeling to predict compaction, reducing the need for extensive physical experimentation while improving prediction accuracy and reducing overall process complexity.
Solution Approach 2:
The patent creates a mathematical model (polynomial regression) that copies and simulates the complex relationship between cooling rates and compaction. This virtual model allows accurate prediction of compaction behavior without requiring extensive physical testing, thereby improving precision while reducing the complexity of actual manufacturing operations.
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
This approach allows for precise control of compaction, reducing thermal stress and alignment issues in LCD manufacturing, leading to improved product quality and cost efficiency by predicting and minimizing compaction through optimized cooling rate adjustments.
Implementation Method 1
compaction is the change in length per unit length exhibited by a glass substrate in a plane of the substrate as a result of subtle changes in glass structure produced by thermal cycling
Implementation Method 2
The impact of temperature can be most acute during the forming process, where a thin glass ribbon... is drawn from a forming body through free space supported principally by its edges
Data Source
AI summary
A method of controlling compaction including obtaining a plurality of sets of process conditions for a plurality of glass ribbons, measuring a compaction value for a glass sheet cut from each glass ribbon of the plurality of glass ribbons, correlating the compaction to the process conditions. The method further includes selecting a predetermined cooling curve including a plurality of cooling rates, modifying the cooling curve by varying cooling rates of the plurality of cooling rates, calculating a predicted compaction value for a glass sheet cut from a glass ribbon drawn using the modified cooling curve, and repeating the modification and predicting until compaction is minimized.