Insulating Layer Compressive Stress for FFS LCD Adhesion
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Solution Overview
Problem
In liquid crystal display devices, particularly of the fringe field switching (FFS) type, the adhesion of the insulating layer between the upper and lower electrodes is inconsistent, leading to reduced insulation, disturbance of the electric field driving the liquid crystal layer, and degradation of the storage capacitor, resulting in poor image quality.
Innovation Solution
The insulating layer is engineered to have a compressive stress within the range of 0 to 5×10^4 N/cm², using inorganic materials like silicon nitride, silicon oxide, or silicon oxynitride, which enhances adhesion and maintains the integrity of the storage capacitor, ensuring high-quality image display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulating layer is formed between the upper electrode and the lower electrode in an FFS type liquid crystal display device, then the storage capacitor can be defined, but the adhesion between the insulating layer and adjoining layers becomes inconsistent causing separation
Solution Approach 1:
The patent applies parameter changes by controlling the residual stress of the insulating layer to be within a specific range (compressive stress of 0 to 5×10^4 N/cm²). This parameter control prevents the insulating layer from separating from adjoining layers while maintaining stable insulation between electrodes, thereby resolving the adhesion inconsistency problem.
2Strength
If the insulating layer has increased residual stress to improve adhesion, then the adhesion strength increases, but the insulating layer separates from adjoining layers
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the residual stress parameter to be within the optimal range of 0 to 5×10^4 N/cm². This parameter optimization ensures sufficient adhesion strength while preventing separation, maintaining stable insulation between electrodes.
Solution Approach 2:
The patent converts the potentially harmful effect of residual stress into a beneficial outcome by controlling it to be compressive rather than tensile. The compressive stress within the specific range strengthens adhesion while preventing layer separation, turning what could be a cause of failure into a stabilizing factor.
3Ease of manufacture
If the insulating layer separates from adjoining layers, then the adhesion is reduced, but the electric field for driving the liquid crystal layer is disturbed and storage capacitor is degraded
Solution Approach 1:
The patent ensures manufacturing precision by controlling the residual stress parameter of the insulating layer to be within the specific range of 0 to 5×10^4 N/cm². This parameter control prevents separation during the layer formation process and ensures stable electric field distribution and storage capacitor characteristics, thereby maintaining high image quality.
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 solution stabilizes the adhesion of the insulating layer, preventing separation and maintaining the dielectric properties necessary for high-quality image display and superior capacitance, thus enhancing the overall performance of the liquid crystal display device.
Implementation Method 1
the insulating layer has a compressive stress in the range of 0 to 5×10^4 N/cm2
Implementation Method 2
Since an inorganic insulating layer generally has a higher dielectric constant than an organic insulating layer, the inorganic insulating layer leads to superior capacitance properties
Implementation Method 3
a voltage is applied between the pixel electrodes and the common electrode to generate an electric field substantially parallel to the surface of the substrate, thereby driving liquid crystal molecules in a plane substantially parallel to the surface of the substrate
Data Source
AI summary
A liquid crystal display device includes a pair of substrates opposing each other, a liquid crystal layer disposed between the pair of substrates, and a pair of electrodes separated by an insulating layer, disposed on one of the substrates. The pair of electrodes drives the liquid crystal layer. The insulating layer has a compressive stress in the range of 0 to 5×104 N/cm2.