IPS LCD Optical Compensation Layer for Viewing Angle Correction
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Solution Overview
Problem
Conventional IPS LCD devices experience chromaticity shift and leakage light issues when viewed at angles, degrading image quality and contrast ratio due to insufficient polarization and optical compensation.
Innovation Solution
The IPS LCD device incorporates specific optical compensation layers with controlled birefringence and retardation properties, along with protective layers, to minimize chromaticity shift and leakage light by optimizing the alignment and thickness of polarizing films and optical compensation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optical compensation layers are added to suppress chromaticity shift, then image quality improves, but device complexity increases
Solution Approach 1:
The optical compensation function is divided into multiple separate layers: a first optical compensation layer on the light-incident side and a second optical compensation layer on the light-emitting side. Each layer has specific retardation values (N1 and N2 respectively) that work together to compensate for optical path differences, thereby suppressing chromaticity shift while maintaining manageable structural complexity through functional division
Solution Approach 2:
The patent employs composite optical structures combining polarizing films with specific retardation properties and optical compensation layers made of materials with controlled birefringence. The combination of TAC protective layers, PVA polarization layers, and optical compensation layers creates a composite structure that achieves superior chromaticity control through the synergistic optical properties of different materials
2Reliability
If protective layers with retardation are used in polarizing films, then polarization performance improves, but leakage light increases
Solution Approach 1:
The patent carefully controls the retardation parameters of protective layers within specific ranges (N1 for the first protective layer and N2 for the second protective layer) and optimizes the thickness of the optical compensation layers. By adjusting these optical parameters, the system achieves effective compensation of polarization deviations while minimizing leakage light generation through precise parameter optimization
Solution Approach 2:
Different regions of the optical stack are assigned different optical properties: the first protective layer has retardation N1, the second protective layer has retardation N2, and the optical compensation layers have specific birefringence values. This local differentiation of optical qualities allows each layer to address specific aspects of polarization control and leakage light suppression
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 effectively reduces leakage light and suppresses chromaticity shift, enhancing the contrast ratio and image quality, especially when viewed at slanted angles.
Implementation Method 1
The TAC layer 219B has a negative retardation, whereas the optical compensation layer 219A has a positive retardation having a value equivalent to the absolute value of the negative retardation of the TAC layer 219B
Implementation Method 2
the LC layer is applied with a lateral electric field, which is parallel to the substrates, to control the direction of the LC molecules for image display
Implementation Method 3
first and second polarizing films sandwiching therebetween the first and second substrates and the LC layer, the first and second polarizing films having polarization axes extending normal to each other
Data Source
AI summary
An in-plane-switching-mode (IPS) LCD device includes a TFT substrate and a CF substrate sandwiching therebetween an LC layer, and a pair of polarizing films sandwiching therebetween the substrates and the LC layer. Each polarizing film has a polarization layer and a protective layer An optical compensation layer having a birefringence is disposed between the light-emitting-side polarizing film and the CF substrate. The optical compensation layer has an in-plane retardation of N1 satisfying the following relationship:83.050−0.810×D1≦N1≦−228.090−0.74D1 in the range of 0<D1≦80 μm, wherein D1 is the thickness of the protective layer of the light-incident-side polarizing film.