Narrow Gasket LCD With Barrier Layer
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Solution Overview
Problem
Liquid crystal display (LCD) devices suffer from defects and catastrophic failures over time due to trace impurities affecting the alignment layers, and the wide gasket required for sealing reduces the yield of devices per wafer.
Innovation Solution
Incorporating a barrier layer between the liquid crystal alignment layer and the liquid crystal layer to protect against impurities and reduce the gasket width, allowing for smaller and more reliable LCD devices with increased yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wide gasket is used to seal the liquid crystal layer, then sealing reliability is improved, but the device area increases and yield per wafer decreases
Solution Approach 1:
The patent applies a thin film barrier layer (50-200 nm thickness) between the alignment layer and liquid crystal layer to prevent impurity penetration. This thin film structure provides effective sealing and protection without requiring a wide gasket, thereby maintaining sealing reliability while reducing the overall device area and increasing yield per wafer.
2Productivity
If the gasket width is reduced to increase yield, then device area decreases and yield per wafer increases, but sealing effectiveness and protection against impurities deteriorates
Solution Approach 1:
The patent introduces a barrier layer as an intermediary component between the alignment layer and liquid crystal layer. This barrier layer acts as a mediator that prevents trace impurities from the liquid crystal layer from reaching and degrading the alignment layer, thereby maintaining protection effectiveness even when the gasket width is reduced to increase yield per wafer.
Solution Approach 2:
The thin film barrier layer provides effective impurity protection through its barrier properties, enabling the use of narrower gaskets while maintaining adequate protection against impurity penetration, thus increasing yield per wafer without sacrificing reliability.
3Ease of operation
If polyimide alignment layers are used, then alignment functionality is achieved, but stability under high intensity illumination deteriorates
Solution Approach 1:
The patent employs evaporated thin film materials (such as silicon oxide or silica) as alignment layers, which provide both the necessary alignment functionality and superior stability under high intensity illumination compared to polyimide layers. This composite approach maintains ease of operation while significantly improving stability.
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 barrier layer effectively prevents impurity absorption, maintains alignment layer functionality, and reduces gasket width, enhancing the reliability and yield of LCD devices by minimizing contamination and material costs.
Implementation Method 1
trace impurities (e.g., water vapor) were being absorbed into or adsorbed onto the thin film liquid crystal alignment layers
Implementation Method 2
evaporated thin film alignment layers were developed. These evaporated thin film layers are typically formed from oblique evaporation of silicon oxide (SiO) or silica (SiO2)
Data Source
AI summary
A liquid crystal display device includes a substrate, a liquid crystal layer, a liquid crystal alignment layer between the substrate and the liquid crystal layer, a barrier layer between the liquid crystal alignment layer and the liquid crystal layer, and a gasket formed around the perimeter of the liquid crystal layer and abutting the barrier layer. The gasket has a width less than or equal to 400 micrometers. A second substrate also includes a liquid crystal alignment layer and a barrier layer formed over the liquid crystal alignment layer. The gasket also abuts the barrier layer of the second substrate. In a particular embodiment, the substrate is a reflective display backplane, and the second substrate is a transparent substrate having a transparent electrode layer. The gasket of the present invention is much narrower than gaskets of the prior art, which enables LCD devices to be made smaller and cheaper because more LCD devices can be produced per wafer.