Liquid Crystal Display Storage Swing Voltage Control
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Solution Overview
Problem
Conventional liquid crystal display (LCD) technologies face challenges in achieving a wide viewing angle while maintaining high brightness and side visibility, as they often result in a decrease in contrast ratio due to increased black brightness when voltage variation is increased.
Innovation Solution
A liquid crystal display employing a storage swing method with a pixel electrode structure and a thin film transistor (TFT) that transmits data voltage to electrodes during a horizontal scan period, utilizing liquid crystals with specific dielectric anisotropy and elastic constant ratios to maximize voltage variation without increasing black brightness, thereby enhancing brightness and side visibility while maintaining a high contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If voltage variation of storage electrode is increased to improve brightness and side visibility, then brightness and side visibility are improved, but contrast ratio decreases due to increased black brightness
Solution Approach 1:
The patent changes the voltage parameter characteristics by applying a pulsed common voltage to the storage electrode instead of a static voltage. The common voltage has a high level during a first time period and a low level during a second time period, creating voltage variation that improves brightness and side visibility while the pulsed nature prevents excessive black brightness increase, thus maintaining contrast ratio.
2Ease of operation
If voltage variation of storage electrode is increased to improve side visibility, then side visibility is improved, but contrast ratio decreases due to increased black brightness
Solution Approach 1:
The patent changes the voltage parameter characteristics by applying a pulsed common voltage to the storage electrode instead of a static voltage. The common voltage has a high level during a first time period and a low level during a second time period, creating voltage variation that improves side visibility while the pulsed nature prevents excessive black brightness increase, thus maintaining contrast ratio.
3Ease of manufacture
If CC-type S-PVA mode is used to reduce manufacturing cost, then manufacturing cost is reduced, but brightness and side visibility deteriorate
Solution Approach 1:
The patent uses a single thin film transistor per pixel instead of two transistors, reducing manufacturing cost. By applying pulsed common voltage to the storage electrode, the invention achieves improved brightness and side visibility characteristics while maintaining the simpler and more cost-effective single-transistor architecture.
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 increases brightness and side visibility while preventing excessive decrease in contrast ratio by optimizing the voltage variation range of the main storage electrode, using liquid crystals with dielectric anisotropy between -3.8 and -2.2 and elastic constant ratios between 1.155 and 1.385, thus improving the overall display performance.
Implementation Method 1
utilizing liquid crystals with specific dielectric anisotropy and elastic constant ratios to maximize voltage variation without increasing black brightness
Implementation Method 2
A liquid crystal display employing a storage swing method with a pixel electrode structure and a thin film transistor (TFT) that transmits data voltage to electrodes during a horizontal scan period
Data Source
AI summary
In a liquid crystal display, an image-defining data voltage is simultaneously applied to a main pixel electrode (MPE) and an electrically isolatable sub pixel electrode (SPE) to thereby respectively define a main pixel voltage and a sub pixel voltage. The MPE defines one plate of a first capacitor whose other plate receives a first common voltage whose voltage level can be varied after the image-defining data voltage is applied. Thus the main pixel voltage is shifted up or shifted down according to the voltage variation of the first common voltage. The SPE defines one plate of a second capacitor whose other plate receives a second common voltage. By causing the main pixel voltage to be of greater absolute amplitude than the sub pixel voltage, a side visibility of the liquid crystal display can be enhanced. Also, the liquid crystal display utilizes a liquid crystal having a dielectric anisotropy and an elastic constant ratio within a specific range, so that an undesirable increase of a black brightness effect is reduced and thus image contrast is not adversely affected.