LCD Timing Controller Grayscale Adjustment for Charging Defects
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Solution Overview
Problem
The Programmable Line Start Control (PLSC) function in liquid crystal display devices leads to a decrease in charging time for pixel rows other than the first, resulting in insufficient charging and display defects due to large grayscale changes, particularly in high-frequency displays like 8K-120 Hz panels.
Innovation Solution
A liquid crystal display device and method that includes a timing controller to automatically adjust the grayscale value and on-width of the internal clock signal for target pixel rows based on the difference with the previous pixel row, ensuring faster charging and improved image quality by using a lookup table or predetermined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the PLSC function is applied to enhance charging rate of the first pixel row, then charging speed of the first pixel row is improved, but charging time of remaining pixel rows is reduced causing insufficient charging and display defects
Solution Approach 1:
The patent applies different on-width settings to different pixel rows based on their specific charging requirements. The first pixel row receives an extended on-width to enhance charging rate, while subsequent pixel rows receive adjusted on-width values based on their grayscale change characteristics. This localized differentiation resolves the contradiction by optimizing charging for each row individually rather than applying a uniform approach.
Solution Approach 2:
The patent dynamically adjusts the on-width of the internal clock signal based on grayscale change characteristics between consecutive pixel rows. When grayscale changes are large, the on-width is extended to provide sufficient charging time. When grayscale changes are small, the on-width is reduced to maintain overall timing. This dynamic adjustment resolves the contradiction between charging speed and image quality.
2Duration of action of moving object
If the on-width of internal clock signal for the first pixel row is increased, then charging time for the first pixel row is extended, but total duration constraint causes decrease in charging time for subsequent pixel rows
Solution Approach 1:
The patent changes the on-width parameter of the internal clock signal dynamically based on grayscale change characteristics. By calculating the grayscale difference between consecutive pixel rows and comparing it to a threshold, the system adjusts the on-width parameter to ensure sufficient charging time for rows with large grayscale changes while maintaining timing constraints for the overall frame.
3Reliability
If the polarity of data voltage is inverted frequently to prevent liquid crystal deterioration, then liquid crystal characteristics are maintained, but charging time for each pixel row is reduced
Solution Approach 1:
The patent performs preliminary assessment of grayscale change characteristics between consecutive pixel rows before determining the on-width setting. By anticipating which rows will require extended charging time based on large grayscale changes, the system can pre-adjust the on-width parameter to ensure sufficient charging time is allocated, thereby resolving the contradiction between frequent polarity inversion requirements and adequate charging time.
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 allows for faster charging of pixel rows, ensuring that target grayscale levels are reached within reduced time, thereby enhancing display effects and reducing image quality degradation caused by the PLSC function.
Implementation Method 1
Liquid crystal display devices (LCDs) display picture information using photoelectric properties of liquid crystals injected into a liquid crystal panel
Implementation Method 2
two substrates and liquid crystals having a dielectric anisotropy are injected between the two substrates
Data Source
AI summary
Provided are a liquid crystal display device and a method for driving the same. The liquid crystal display device includes: a display panel; a gate driver; a data driver; and a timing controller configured to control operations of the gate driver and the data driver, and the timing controller configured to output a data signal, an internal clock signal, and a polarity control signal to the data driver based on image data, wherein the data driver is configured to invert polarity of a data voltage every predetermined, or alternatively, desired rows based on the polarity control signal, and in a plurality of adjacent pixel rows loaded with data voltages of the same polarity, an on-width of the internal clock signal of a first pixel row is greater than that of the internal clock signals of other pixel rows; and wherein when an original grayscale value of a target pixel row in the other pixel rows is different from the original grayscale value of a previous pixel row in the other pixel rows, the timing controller is configured to automatically adjust the grayscale value of the target pixel row, and output the adjusted grayscale value as the data signal of the target pixel row.