LCD Subpixel Voltage Compensation for Viewing Angle Defects
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Solution Overview
Problem
Liquid crystal displays (LCDs) face issues with side visibility due to refractive anisotropy in liquid crystal materials, leading to color and contrast ratio differences at various viewing angles, and manufacturing defects in thin film transistors can cause subpixel electrodes to malfunction, affecting display quality.
Innovation Solution
The LCD design includes a matrix of pixels with subpixel electrodes and switching elements, where the second subpixel electrode is connected to the first subpixel electrode regardless of gate signals, and a voltage-changing capacitor is used to adjust voltages, allowing for independent control of subpixel voltages and improving lateral visibility by disconnecting source electrodes from data lines and shorting voltage-changing capacitor terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the liquid crystal material with refractive anisotropy is used to achieve high front visibility, then the contrast ratio and color accuracy are improved, but the side visibility deteriorates due to viewing angle dependence
Solution Approach 1:
The pixel electrode is divided into two subpixel electrodes (first and second subpixel electrodes) that can be independently controlled. This segmentation allows different voltage applications to adjacent subpixels, creating a compensation effect that widens the viewing angle while maintaining front visibility quality
2Ease of manufacture
If the thin film transistor channel is exposed during manufacturing, then the patterning process can be completed, but impurity introduction causes channel deterioration and subpixel electrode malfunction
Solution Approach 1:
The voltage-changing capacitor is connected in parallel with the liquid crystal capacitor to provide voltage compensation. When channel deterioration causes improper voltage application, the capacitor compensates for voltage deviations, preventing display defects and maintaining reliable operation despite manufacturing imperfections
3Object-affected harmful factors
If the subpixel electrodes are independently controlled with different voltages to improve viewing angle, then lateral visibility is enhanced, but the device complexity increases due to additional switching elements
Solution Approach 1:
The voltage-changing capacitor serves multiple functions: it compensates for voltage deviations due to channel deterioration, enables viewing angle compensation through differential voltage application, and provides stability to the liquid crystal voltage. This multi-functionality reduces the need for separate compensation circuits, managing device complexity while achieving improved lateral visibility
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 enhances lateral visibility by ensuring accurate voltage application to subpixel electrodes, mitigating defects in thin film transistors and improving display quality by maintaining consistent voltage levels across subpixels.
Implementation Method 1
a voltage-changing capacitor including the third drain electrode and a common voltage line transmitting a common voltage as its two terminals
Implementation Method 2
The liquid crystal layer includes a liquid crystal material having refractive anisotropy. Because of the refractive anisotropy of the liquid crystal material however, large differences in the color and the contrast ratio can occur between different viewing angles
Data Source
AI summary
A liquid crystal display includes a plurality of data lines and a plurality of pixels arranged in a matrix, wherein the plurality of pixels include a first pixel and a second pixel, and each of the first pixel and the second pixel includes a first subpixel electrode and a second subpixel electrode, a first switching element, a second switching element, a third switching element, and a voltage-changing capacitor, wherein a first source electrode on the first switching element and a second source electrode on the second switching element from the first pixel are connected to a data line, the first source electrode and the second source electrode of the second pixel are disconnected from the plurality of data lines, and the two terminals of the voltage-changing capacitor of the second pixel are shorted to each other.