Liquid Crystal Display Spacer Gap Uniformity via Step Films
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Solution Overview
Problem
Conventional liquid crystal display devices experience variations in the gap between substrates due to inaccuracies in the contact area between columnar spacers and the active matrix substrate, leading to issues with light leakage, display unevenness, and variations in luminance, chromaticity, and contrast.
Innovation Solution
The implementation of locally formed films on the active matrix substrate, which create steps that determine the contact area with spacers, ensuring a uniform gap between the active matrix and color filter substrates by controlling the contact region and reducing frictional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If columnar spacers are formed to extend toward the active matrix substrate with their tips contacting the protective film, then the gap between substrates is maintained, but frictional force prevents dislocation restoration causing light leakage and display unevenness
Solution Approach 1:
The patent extracts the frictional contact interface by introducing a liquid crystal layer between the spacer tip and the protective film. The spacer tip contacts the liquid crystal layer instead of directly contacting the protective film, eliminating the harmful frictional force that caused dislocation restoration failure and light leakage, while still maintaining gap uniformity through the liquid crystal's confinement effect
Solution Approach 2:
The liquid crystal layer serves as an intermediary substance between the spacer tip and the protective film. It mediates the interaction by providing a low-friction interface that allows the spacer to maintain its position without generating harmful frictional forces, thus preventing light leakage while preserving gap uniformity
2Object-affected harmful factors
If the number of columnar spacers is reduced to decrease frictional force, then light leakage is reduced, but plastic deformation occurs causing gap unevenness
Solution Approach 1:
The patent changes the physical state of the spacer tip interface from solid-to-solid contact (high friction) to solid-liquid interface (low friction) by introducing the liquid crystal layer. This parameter change in the interface nature allows maintaining sufficient friction for gap uniformity while reducing enough friction to prevent plastic deformation and light leakage, eliminating the need to reduce spacer number
3Reliability
If columnar spacers are made to contact the protective film firmly, then gap is held, but friction causes irreversible dislocation preventing restoration
Solution Approach 1:
The patent replaces the direct mechanical contact system (spacer tip to protective film) with a fluid-mediated system (spacer tip to liquid crystal layer to protective film). The liquid crystal layer substitutes for the rigid mechanical interface, providing gentle confinement that holds the gap without the high friction that causes irreversible dislocation and prevents restoration
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 results in a uniform gap between substrates, reducing display unevenness and variations in luminance, chromaticity, and contrast, while maintaining the structural integrity of the spacers and preventing plastic deformation.
Implementation Method 1
a liquid crystal layer which is disposed between the color substrate and the active matrix substrate
Data Source
AI summary
First and second columnar spacers are formed on a color filter substrate, and step films are formed on an active matrix substrate in the same step as signal lines. The columnar spacers are formed by proximity exposure, and the step films are formed by being exposed by a lens projection system. In plan view, the step films are disposed inside the columnar spacers. The first columnar spacers are made to be in contact with the regions of the protective film that are higher in elevation with the step films in the active matrix substrate.