Liquid Crystal Panel Precharge for Afterimage Reduction
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Solution Overview
Problem
Conventional liquid crystal displays suffer from image sticking and slow reaction times due to the slow response of liquid crystal materials, leading to afterimages, especially when displaying rapidly moving objects, and existing solutions like changing viscosity, over driving, or black insertion increase the load on driving circuits or require higher voltages.
Innovation Solution
A liquid crystal panel and driving method that performs black or grey insertion without increasing driving frequency, using alternating common voltage signals of reverse polarities and incorporating a precharge function to reduce voltage differences across pixel electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional driving methods are used, then the liquid crystal display can operate, but image sticking and afterimages occur due to slow liquid crystal response
Solution Approach 1:
The patent applies preliminary action by pre-charging the pixel electrodes before the main switching operation. The common electrode is charged to a pre-charge voltage that prepares the liquid crystal molecules for the upcoming switching action, thereby reducing the actual response time and eliminating image sticking without requiring faster liquid crystal materials
2Reliability
If black insertion or grey insertion is performed by increasing driving frequency, then afterimages are reduced, but the driving circuit load increases
Solution Approach 1:
The patent performs black or grey insertion by applying a pre-charge voltage to the common electrode before the normal driving cycle, rather than increasing the driving frequency. This preliminary action prepares the liquid crystal state to prevent afterimages while maintaining the same driving frequency, thus avoiding increased circuit load
Solution Approach 2:
The patent changes the voltage parameter of the common electrode by introducing a pre-charge voltage level that is different from the normal driving voltages. This parameter change enables afterimage reduction through voltage-controlled liquid crystal preparation rather than through frequency-based methods
3Speed
If over driving is used to improve response time, then reaction speed increases, but higher voltages are required
Solution Approach 1:
The patent achieves fast response without over-driving voltages by pre-charging the common electrode to a specific voltage level before the switching operation. This preliminary action creates favorable initial conditions for the liquid crystal molecules, enabling rapid response at normal voltage levels rather than requiring elevated over-driving voltages
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
Achieves effective black or grey insertion without increasing driving frequency, improving response time and reducing afterimages by precharging pixel electrodes, thus enhancing display quality without the need for higher voltages or increased circuit load.
Implementation Method 1
an LCD controls light transmittance of liquid crystal by an electrical field so as to display images
Implementation Method 2
Each pixel comprises a TFT, a liquid crystal capacitor CLC, and a storage capacitor Cst. The TFT is located at the intersection of a scanning line and a data line, and functions as a switch element to drive a pixel electrode
Implementation Method 3
A liquid crystal capacitor CLC is formed between a pixel electrode and a common electrode of an opposite substrate
Data Source
AI summary
A liquid crystal panel, a liquid crystal display, and a driving method thereof are disclosed. The liquid crystal panel comprises scanning lines, data lines, and a plurality of pixels, each of the plurality of pixels including a TFT, a pixel electrode, a first common electrode, and a second common electrode. The first common electrodes of first pixels of the plurality of pixels are electrically connected via a first common line, the first common electrodes of second pixels of the plurality of pixels are electrically connected via a second common line, and the second common electrodes of the plurality of pixels are electrically connected.