Field Sequential LCD Polarity Control for Luminance Gradient Elimination
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Solution Overview
Problem
Liquid crystal display devices using field sequential driving methods often experience luminance gradients and image quality degradation due to polarity inversion schemes like column inversion or frame inversion.
Innovation Solution
A liquid crystal display device and driving method that employs an area light source with successively turned on light sources, where video signal write and reset signal write are executed with the same polarity within a frame period, and the polarity of display pixels is reversed between frame periods, utilizing an OCB liquid crystal mode for high responsivity and preventing reverse transitions of liquid crystal molecules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If field sequential driving method is used, then light use efficiency is improved, but luminance gradient occurs in display image
Solution Approach 1:
The patent applies dynamics by making the polarity inversion timing adaptive to the light source activation. Instead of fixed polarity inversion, the system dynamically adjusts when polarity inversion occurs to coincide with light source switching, thereby maintaining image quality while preserving the high light efficiency of field sequential driving
Solution Approach 2:
The patent employs periodic action through synchronized polarity inversion that occurs at regular intervals corresponding to the light source activation cycles. Each light source activation period is accompanied by coordinated polarity inversion, creating a periodic pattern that prevents luminance gradient while maintaining the efficiency benefits of sequential light source operation
2Use of energy by moving object
If column inversion or frame inversion is executed as polarity inversion scheme, then power consumption is reduced, but luminance gradient occurs in display image
Solution Approach 1:
The patent transforms static polarity inversion schemes into a dynamic system where polarity inversion timing is adapted to light source activation. This dynamic approach maintains the low power consumption characteristics of frame inversion while eliminating the luminance gradient problem through synchronized timing with light source switching
Solution Approach 2:
The patent implements feedback by using information about light source activation timing to control polarity inversion timing. The system monitors when each light source is activated and uses this information to trigger polarity inversion at the optimal moment, creating a closed-loop control that prevents luminance gradient while maintaining energy efficiency
3Stability of the object's composition
If polarity inversion is executed frequently, then liquid crystal molecule distribution uniformity is improved, but write deficiency and burn-in occur
Solution Approach 1:
The patent applies periodic action by establishing regular intervals for polarity inversion that correspond to light source activation cycles. This periodic pattern ensures liquid crystal molecules are redistributed uniformly while avoiding excessive inversion frequency that would cause write deficiency and burn-in, achieving a balanced inversion schedule
Solution Approach 2:
The patent changes the timing parameter of polarity inversion to synchronize with light source activation. By adjusting when polarity inversion occurs rather than changing the inversion mechanism itself, the system maintains uniform liquid crystal distribution while preventing display defects caused by improper inversion timing
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 prevents luminance gradients and maintains image quality by ensuring the same polarity within a frame period and reversing it only between frames, reducing power consumption and flicker while avoiding write deficiencies and burn-in.
Implementation Method 1
Alignment of liquid crystal molecules in the pixel region is set by an electric field which corresponds to the driving voltage. Thereby, the transmittance of the pixel is controlled.
Implementation Method 2
an area light source device which illuminates the liquid crystal display panel; the area light source device includes plural kinds of light sources which are successively turned on in one frame period
Data Source
AI summary
A liquid crystal display device includes a liquid crystal display panel (LCD panel), an area light source device which illuminates the LCD panel, a driving unit which drives the LCD panel and the area light source device, and a control unit which controls the driving unit. The LCD panel includes display pixels. The area light source device includes plural kinds of light sources which are successively turned on in one frame period. The control unit includes means for controlling the driving unit in a manner to execute video signal write and reset signal write after the video signal write, in a period in which one of the plural kinds of light sources is turned on in the one frame period. The video signal write and the reset signal write are executed with the same polarity, and a polarity of potential of the display pixels is reversed between frame periods.