Transflective IPS Liquid Crystal Display Phase Difference Layer Optimization
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Solution Overview
Problem
Transflective IPS liquid crystal display devices face challenges in achieving high reflectance and contrast ratios, especially in wide view angles and varying environments, due to limitations in the retardation values of phase difference layers and liquid crystal layers, which affect the polarization status and light reflection.
Innovation Solution
The solution involves adjusting the retardation value of the phase difference layer specifically for the blue pixel by reducing light irradiation during the formation process, using a half tone or gray scale mask to decrease the light irradiation amount, and potentially altering the film thickness, allowing for a thinner phase difference layer for the blue pixel, thereby improving contrast ratios and reflectance without increasing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the phase difference layer is formed with uniform thickness and standard light irradiation, then the manufacturing process is simple, but the contrast ratio and reflectance cannot be optimized for different color pixels
Solution Approach 1:
The patent applies local quality by creating phase difference layers with different thicknesses for different color pixels (red, green, blue). Specifically, the blue pixel region has a thinner phase difference layer compared to the red and green pixel regions. This localized variation in thickness allows each color to achieve optimal contrast ratio and reflectance characteristics tailored to its specific optical requirements, thereby resolving the contradiction between manufacturing simplicity and performance optimization.
2Manufacturing precision
If the phase difference layer for blue pixel is made thinner to improve contrast ratio, then the reflectance and contrast are enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent employs preliminary action by using a mask pattern during the phase difference layer formation process. The mask is applied before the phase difference layer is deposited, pre-defining the regions where the layer will be thin (blue pixel areas) versus where it will be thick (red and green pixel areas). This preliminary masking step allows the subsequent deposition process to create the desired non-uniform thickness profile in a single operation, avoiding the need for multiple sequential deposition steps and thereby maintaining manufacturing simplicity while achieving the required reflectance optimization.
3Adaptability or versatility
If standard retardation values are used for all pixels, then the manufacturing process is straightforward, but the polarization status cannot be optimized for wide view angles in reflection mode
Solution Approach 1:
The patent applies local quality by assigning different retardation values to different color pixels through varying the thickness of the phase difference layer. The blue pixel region uses a thinner phase difference layer with lower retardation, while the red and green pixel regions use thicker layers with higher retardation. This localized differentiation allows each color to achieve optimal polarization status for wide view angles in reflection mode, resolving the contradiction between adaptability and structural complexity.
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 enhances the contrast ratio of both transmission and reflection displays in transflective IPS liquid crystal devices, enabling high image quality under various environments, including bright outdoor conditions, while maintaining simplicity in manufacturing processes.
Implementation Method 1
The light which reaches the reflection layer is converted into circularly polarized light by employing this phase difference layer and the liquid crystal layer
Implementation Method 2
IPS (In-Plane Switching) type liquid crystal display devices are capable of displaying thereon images at wide view angles and in high contrast ratios
Data Source
AI summary
In a transflective type IPS type liquid crystal display device in which a phase difference layer has been built in a reflection display portion, a retardation value of the phase difference layer corresponding to a short wavelength color filter is different from a retardation value of the phase difference layer corresponding to a long wavelength color filter; while a blue display pixel is set to the short wavelength color filter and both red and green pixels are set to the long wavelength filter, the retardation value of the phase difference layer corresponding to the former-mentioned short wavelength color filter is made smaller than the retardation value of the phase difference layer corresponding to the latter-mentioned long wavelength color filter.