LCD Response Speed via Dual Gray Gap Lookup Tables
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Solution Overview
Problem
The response speed of liquid crystal molecules in liquid crystal displays (LCDs) is slow, leading to degradation in image quality at high driving frequencies due to the conventional dynamic capacitance compensation (DCC) scheme, which struggles to reach target voltages efficiently, especially when the difference between previous and target voltages is large.
Innovation Solution
A liquid crystal display system that includes an image signal modifier and a lookup table to generate modified signals based on first and second image signals, using two lookup tables with different gray gaps to optimize data voltage application, thereby increasing response speed and preventing image degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drive frequency of the liquid crystal display is increased to improve productivity, then the response time available for charging the liquid crystal capacitor is reduced, causing degradation of image quality
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal data voltages in a lookup table (LUT) that compensate for the liquid crystal's slow response. The LUT is pre-computed based on the relationship between gray levels, response times, and required voltage adjustments, allowing the system to quickly retrieve and apply appropriate compensation voltages without real-time calculation delays, thus maintaining image quality at high drive frequencies
Solution Approach 2:
The patent changes the parameter of data voltage dynamically based on the previous frame's gray level and the current frame's target gray level. By adjusting the data voltage beyond the standard voltage required for the target gray level (when the previous voltage was significantly different), the system accelerates the liquid crystal response while maintaining accuracy through the pre-computed lookup table
2Speed
If dynamic capacitance compensation (DCC) is applied to increase response speed by applying greater data voltage, then the time to reach target voltage is reduced, but image quality degrades at high driving frequencies due to excessive voltage application
Solution Approach 1:
The patent implements feedback by using the previous frame's gray level information to determine the appropriate compensation voltage for the current frame. The system continuously monitors the relationship between consecutive frames and adjusts the data voltage accordingly, creating a closed-loop control mechanism that prevents over-compensation and maintains image quality while improving response speed
Solution Approach 2:
The lookup table is pre-computed based on the liquid crystal's electrical characteristics and response behavior, storing the optimal voltage compensation values in advance. This preliminary calculation eliminates the need for complex real-time computations and ensures accurate voltage application that balances response speed improvement with image quality preservation
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 system enhances the response speed of liquid crystal molecules and prevents image quality issues by effectively managing the difference between previous and target voltages, improving display performance at high driving frequencies.
Implementation Method 1
The liquid crystal capacitor has a pixel electrode and a common electrode as terminals and a liquid crystal layer between the electrodes functions as a dielectric material
Implementation Method 2
a liquid crystal layer between the electrodes functions as a dielectric material
Implementation Method 3
voltages are applied to the electric field generating electrodes to generate an electric field in the liquid crystal layer. Due to the generated electric field, liquid crystal molecules of the liquid crystal layer are aligned and polarization of incident light is controlled
Data Source
AI summary
A liquid crystal display includes an image signal modifier for generating a modified signal based on a first image signal of a first frame, a second image signal of a second frame, and a lookup table. A data driver converts the modified signal into a data voltage which is supplied to a pixel of the display. The lookup table stores a plurality of reference modified signals for a plurality of reference first image signals and a plurality of reference second image signals. The lookup table includes a first lookup table having a gray gap of the reference first image signals and a gray gap of the reference second image signals of x, and a second lookup table having a gray gap of the reference first image signals and a gray gap of the reference second image signals of y, where y is greater than x.