In-Cell Retarder Positioning for LCD Parallax Color Mixture
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Solution Overview
Problem
Liquid crystal display devices with circularly polarizing plates suffer from increased parallax color mixture due to the placement of the in-cell retarder between the black matrix and the liquid crystal layer, leading to worse color mixture at smaller angles compared to common LCDs without such a retarder.
Innovation Solution
The in-cell retarder is positioned outside the region between the black matrix and the liquid crystal layer, either in the thin-film transistor substrate or the color filter substrate, to reduce the distance between the black matrix and the liquid crystal layer, thereby minimizing parallax color mixture and reflection of outside light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the in-cell retarder is disposed on the liquid crystal layer side of the color filter substrate to achieve circularly polarized light output, then outside visibility is improved by reducing reflection, but parallax color mixture worsens due to increased distance between black matrix and liquid crystal layer
Solution Approach 1:
The patent moves the in-cell retarder from the color filter substrate to the thin-film transistor substrate, changing its spatial position in the display structure. This dimensional repositioning allows the retarder to be placed on the opposite side of the liquid crystal layer, thereby reducing the distance between the black matrix and liquid crystal layer while still achieving the required optical path length for circular polarization through the entire cell thickness
Solution Approach 2:
The patent changes the optical path parameters by utilizing the liquid crystal layer itself as part of the retardation path. By adjusting the liquid crystal layer thickness and birefringence, along with the out-cell retarder properties, the system achieves the required quarter-wave retardation without needing the in-cell retarder to be positioned far from the black matrix
2Object-affected harmful factors
If a circularly polarizing plate is disposed on the outermost surface of the panel to reduce outside light reflection, then outside visibility improves, but the distance between black matrix and liquid crystal layer increases causing color mixture
Solution Approach 1:
The patent extracts the in-cell retarder from its conventional position on the color filter substrate and relocates it to the thin-film transistor substrate. This extraction from the problematic position eliminates the source of parallax color mixture while the circularly polarizing plate remains on the outermost surface to continue providing anti-reflection functionality
Solution Approach 2:
The retardation function is segmented between the liquid crystal layer, the in-cell retarder on the TFT substrate, and the out-cell retarder on the circularly polarizing plate. This segmentation allows each component to be optimized independently, with the in-cell retarder positioned to minimize color mixture and the out-cell components providing the necessary optical path extension for circular polarization
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 configuration reduces parallax color mixture to levels equivalent to common LCDs and enhances outside visibility by minimizing reflection, achieving improved optical characteristics similar to those of common LCDs while maintaining reduced reflection of outside light.
Implementation Method 1
an in-cell retarder disposed in one substrate disposed on the viewing side selected from the thin-film transistor substrate and the color filter substrate
Implementation Method 2
a circularly polarizing plate disposed on a viewing side of the liquid crystal panel, the circularly polarizing plate sequentially including, from a viewing side, a linearly polarizing plate and an out-cell retarder
Implementation Method 3
voltage is applied to the liquid crystal composition to change the alignment of liquid crystal molecules, whereby the amount of light passing through the liquid crystal panel is controlled
Data Source
AI summary
A liquid crystal display device includes a liquid crystal panel and a circularly polarizing plate disposed on a viewing side of the liquid crystal panel. The circularly polarizing plate sequentially includes, from a viewing side, a linearly polarizing plate and an out-cell retarder. The liquid crystal panel includes a thin-film transistor substrate, a color filter substrate facing the thin-film transistor substrate and including black matrix, a horizontal alignment liquid crystal layer disposed between the thin-film transistor substrate and the color filter substrate, and an in-cell retarder disposed in one substrate disposed on the viewing side selected from the thin-film transistor substrate and the color filter substrate. The in-cell retarder is disposed outside a region between the black matrix and the horizontal alignment liquid crystal layer.