IPS Liquid Crystal Display Pixel Electrode Asymmetry
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Solution Overview
Problem
Liquid crystal display devices in IPS mode suffer from dark unevenness on the peripheral portions due to the accumulation of ions and impurities, which affects viewing angle uniformity, particularly at the corners of the display region.
Innovation Solution
The design involves forming pixel electrodes and common electrodes with specific angles and orientations on TFT and counter substrates, ensuring that the rotation directions of liquid crystal molecules are opposite between adjacent pixels, preventing the directional flow of ions and impurities, thereby eliminating dark unevenness. This is achieved by configuring pixel electrodes and common electrodes with slopes or projections at complementary angles across the display region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If pixel electrodes are formed with uniform slopes in IPS mode, then viewing angle characteristics are improved, but dark unevenness occurs on the peripheral portions due to ion accumulation
Solution Approach 1:
The patent applies asymmetry by forming pixel electrodes with different slope directions in adjacent pixels. Specifically, pixel electrodes in odd-numbered pixels have slopes inclined in one direction, while pixel electrodes in even-numbered pixels have slopes inclined in the opposite direction. This asymmetric arrangement prevents ions from accumulating in specific peripheral regions, thereby eliminating dark unevenness while maintaining uniform viewing angle characteristics across the display panel.
2Illumination intensity
If comb tooth electrodes are bent to vary liquid crystal rotation directions, then azimuth angle anisotropy is reduced, but ion flow in specific directions causes dark unevenness
Solution Approach 1:
The patent applies local quality by varying the slope direction of pixel electrodes based on the specific pixel's position in the matrix arrangement. Each pixel's electrode slope is locally optimized to point toward the center of the display region, with the specific direction determined by the pixel's location. This local optimization ensures that ions from all pixels flow toward the center rather than accumulating in peripheral regions, eliminating dark unevenness while maintaining viewing angle uniformity.
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
The solution effectively prevents the accumulation of ions and impurities at the corners of the display region, ensuring uniform viewing angles and reducing dark unevenness, thereby enhancing the overall display quality.
Implementation Method 1
a pixel electrode and a common electrode, and an electric field is generated between both electrodes
Implementation Method 2
a liquid crystal is sandwiched between the TFT substrate and the counter substrate. An image is formed by controlling the optical transmittance of liquid crystal molecules
Implementation Method 3
ions and impurities included in a liquid crystal (in the following, referred to as ions and the like) flow in a specific direction depending on the direction of an electric field formed by the pixel electrode or a common electrode
Data Source
AI summary
To prevent dark unevenness at the corner portion of a screen, a provided is a liquid crystal display including a first pixel formed with a pixel electrode at a first angle in a Y-direction, wherein the pixel electrodes of top, bottom, left, and right adjacent pixels to the first pixel are at a second angle in a Y-direction. The absolute value of the first angle is equal to the absolute value of the second angle, and a sign of the first angle is opposite to a sign of the second angle The rotation direction of a liquid crystal when a voltage is applied to the pixel electrode is in the opposite directions between the adjacent pixels. Thus, it is possible to prevent ions included in the liquid crystal from flowing on the peripheral portion of a display region to prevent dark unevenness at the corner portion of the screen.