LCD Pixel Electrode Segmentation for Wide Viewing Angle
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid Crystal Displays (LCDs) suffer from poor visibility at wide viewing angles due to discrepancies in gamma curves between the front and side perspectives, leading to increased luminance and color shifts, especially in multi-domain structures like PVA mode, resulting in narrow grayscale intervals and dull image expression.
Innovation Solution
The implementation of a pixel electrode divided into main-pixel and sub-pixel electrodes, with different signal voltages applied at the same gray scale, where the sub-pixel electrodes have lower gamma values determined by the equation Gamma K=(current gray scale/maximum gray scale)f, and the main-pixel electrodes' gamma values are calculated by deducting twice the sub-pixel gamma value, ensuring alternation in all lines and rows, and utilizing a lookup table for image signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If an aperture pattern is formed in the common electrode to form a multi-domain structure, then the viewing angle is widened to more than 80 degrees, but the luminance becomes higher and the color becomes closer to white as the viewing point moves to the side, resulting in poor visibility at left and right sides of the screen
Solution Approach 1:
The pixel electrode is divided into a first pixel electrode and a second pixel electrode, with the first pixel electrode having a larger area than the second pixel electrode. This segmentation allows different regions to have different luminance characteristics, compensating for the gamma curve disagreement between front and side viewing angles.
Solution Approach 2:
Different regions of the pixel electrode are given different properties: the first pixel electrode has a larger area for front-view luminance, while the second pixel electrode has a smaller area for side-view luminance control. This local differentiation resolves the uniform structure's inability to handle directional viewing variations.
2Ease of manufacture
If the same voltage is applied to all pixel electrodes at a given gray scale, then the manufacturing process is simple, but the gamma curve at the front and gamma curve at the side disagree, causing unnatural grayscale expression
Solution Approach 1:
The pixel electrode is segmented into first and second pixel electrodes with different areas. The driving circuit applies different voltages to these segments based on their respective areas, enabling independent gamma curve control for front and side viewing angles while maintaining simple manufacturing through standard photolithography processes.
Solution Approach 2:
The voltage parameter is changed differently for the first and second pixel electrodes. The driving circuit calculates and applies voltages based on the area ratio between the two pixel electrodes, allowing precise control of luminance characteristics for different viewing angles without complicating the manufacturing process.
3Device complexity
If a uniform pixel electrode structure is used, then the device complexity is low, but the visibility at wide viewing angles is poor due to gamma curve disagreement
Solution Approach 1:
The uniform pixel electrode is segmented into first and second pixel electrodes with different areas. This segmentation increases device complexity minimally while significantly improving visibility at wide viewing angles by allowing independent voltage control for different viewing directions.
Solution Approach 2:
The pixel electrode structure transitions from a static uniform design to a dynamic configuration where voltages are adjusted based on viewing angle requirements. The driving circuit dynamically applies different voltages to the first and second pixel electrodes, enabling optimal visibility across various viewing angles.
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 visibility by maintaining low luminance in sub-pixels for medium gray scales and controlled luminance in main-pixels, preventing unnatural grayscale expressions and improving side visibility, thereby widening the viewing angle and maintaining image clarity across different angles.
Implementation Method 1
a dielectric anisotropy liquid crystal layer interposed between the panels. In the LCD, the variation of the voltage difference between the field generating electrodes, i.e., the variation in the strength of an electric field generated by the electrodes, changes the transmittance of the light passing through the LCD
Implementation Method 2
the aperture pattern formation method utilizes a fringe field that occurs near the apertures formed in the pixel electrodes and the common electrode. That is, the fringe field controls tilt directions of the liquid crystal molecules to ensure the wide viewing angle
Implementation Method 3
The projection forming method utilizes projections formed on the pixel electrodes and the common electrode of the upper panel. These projections distort an electric field generated between the two electrodes, so that tilt directions of the liquid crystal molecules are controlled
Data Source
AI summary
A liquid crystal display includes first and second opposing spaced insulating substrates, pixel electrodes formed on the first substrate, a common electrode formed on at least one of the first and second substrates, and a liquid crystal layer interposed there between the first substrate and the second substrate. In this structure, each pixel electrode is divided into a main-pixel electrode and a sub-pixel electrode, to which different signal voltages are individually applied at the same gray scale. Further, a signal voltage to be applied to the sub-pixel electrodes is determined by a gamma value satisfying the following equation:Gamma K=(current gray scale/maximum gray scale)f F(Gray Scale)=α×(maximum gray scale/current gray scale),wherein α is a constant.