TRD Liquid Crystal Display Sub-pixel Charge Control
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Solution Overview
Problem
Triple Rate Driving (TRD) liquid crystal display devices experience image quality defects due to charge variation between sub-pixels, particularly caused by insufficient charge time leading to reddish phenomena and linear spots, as a result of polarity inversion in data voltages.
Innovation Solution
The method involves interlaced driving where one sub-pixel is turned off per frame, and the remaining sub-pixels are charged with data voltages having inverted or same polarity for specific charge times, with the polarity inverted data voltage being supplied for 2 horizontal periods and the same polarity data voltage for 1 horizontal period, ensuring sufficient charge time and alternating polarity inversion timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Triple Rate Driving (TRD) is used to reduce the number of data lines, then manufacturing cost is reduced, but charge variation occurs between sub-pixels causing image quality defects
Solution Approach 1:
The patent applies preliminary action by extending the charge time for sub-pixels receiving polarity-inverted data voltages before the actual polarity inversion occurs. The gate signal is held high during an extended charge period, allowing the capacitor to fully charge before the data driver inverts the voltage polarity. This prevents charge deficiency that would otherwise cause image quality defects like reddish spots and linear artifacts.
2Stability of the object's composition
If data voltage polarity is inverted to reduce charge variation, then charge distribution is improved, but insufficient charge time causes reddish phenomena and linear spots
Solution Approach 1:
The patent implements preliminary action by extending the charge accumulation period before polarity inversion. The gate signal remains high longer than in conventional TRD, allowing the liquid crystal capacitor to reach full charge voltage before the data driver inverts the polarity. This ensures sufficient charge is stored even though polarity inversion still occurs, preventing the reddish phenomena and linear spots caused by charge deficiency.
Solution Approach 2:
The patent changes the timing parameter of the gate signal duration. Instead of using standard charge time, the gate signal is extended to provide additional charge accumulation time. This parameter change allows the system to maintain charge distribution benefits of polarity inversion while preventing charge deficiency-related image quality defects.
3Manufacturing precision
If charge time is extended for polarity-inverted data voltages, then charge variation is prevented, but driving complexity increases
Solution Approach 1:
The patent resolves the complexity issue by implementing the extended charge time through existing gate driver functionality rather than requiring additional hardware. The gate signal timing is adjusted using software or control logic already present in the display system, avoiding the need for extra circuitry while achieving the desired charge distribution improvement.
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 charge variation between sub-pixels, thereby eliminating image quality defects such as reddish phenomena and linear spots, by ensuring adequate charge time for all sub-pixels, thus maintaining image quality.
Implementation Method 1
Liquid crystal display devices display an image by varying the arrangement direction of liquid crystal molecules depending on the magnitude of an electric field to adjust transmittance of light passing through a polarizing plate
Implementation Method 2
charging another sub-pixel with a data voltage having an inverted polarity as compared to a previous data voltage supplied through the data line for a first charge time
Data Source
AI summary
Disclosed is a liquid crystal display device and a method of driving the same, which prevent image-quality defects due to charge variation. In the method of driving the liquid crystal display device including a pixel consisting of first to third sub-pixels which share one data line and are connected to first to third gate lines, one sub-pixel is turned off on a per frame basis, another sub-pixel is charged with a polarity inverted data voltage for a first charge time including a charge time of the turned-off sub-pixel, and the other sub-pixel is charged with a data voltage having the same polarity as a previous data voltage for a second charge time less than the first charge time. The turned-off sub-pixel, the sub-pixel charged with the polarity inverted data voltage, and the sub-pixel charged with the polarity maintained data voltage alternately vary on a per frame basis.