Liquid Crystal Display Black Level Gamma Voltage Control
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Solution Overview
Problem
Liquid crystal display devices experience afterimages at the black level due to the driving voltage of the black level being lower than the voltage at which gray inversion occurs, causing image data to persist across frames.
Innovation Solution
A liquid crystal display device and driving method that utilize a gamma voltage supplying unit to establish a gamma voltage range of 0 V to 0.005 V for the black level, allowing the data driving unit to convert digital image data into analog data, thereby preventing afterimages by ensuring the black level driving voltage is within a range that does not affect the liquid crystal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the driving voltage of the black level is reduced to improve power consumption and prevent afterimages, then the liquid crystal layer may not be properly activated, but reducing the voltage below the gray inversion point causes afterimages to occur
Solution Approach 1:
The patent applies parameter changes by precisely adjusting the black level driving voltage to a specific range (0.05V to 0.2V) that is below the gray inversion voltage but optimized to prevent afterimages. This parameter optimization resolves the contradiction by finding the optimal voltage point that balances power consumption and image quality stability.
2Object-generated harmful factors
If the driving voltage of the black level is set low to prevent afterimages, then power consumption is reduced, but the voltage may fall below the gray inversion threshold causing display issues
Solution Approach 1:
The patent introduces an intermediary approach by using a dedicated voltage generation circuit that intermediates between the digital image data and the liquid crystal panel. This circuit generates the black level voltage as an intermediate signal that is carefully controlled to be below the gray inversion point but high enough to prevent afterimages, thus resolving the contradiction between preventing afterimages and maintaining gray scale accuracy.
3Loss of energy
If the black level driving voltage is set to 0V to completely eliminate afterimages, then power consumption is minimized, but the liquid crystal layer cannot be properly driven
Solution Approach 1:
The patent applies parameter changes by setting the black level driving voltage to a non-zero optimal range (0.05V to 0.2V) rather than 0V. This parameter optimization allows the liquid crystal layer to be properly activated while minimizing power consumption and preventing afterimages, thus resolving the contradiction between complete power savings and proper liquid crystal activation.
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 effectively prevents afterimages at the black level, improves image clarity, and reduces power consumption by maintaining the driving voltage of the black level at or near 0 V, while ensuring the first gray level voltage is set to avoid gray inversion, thus enhancing overall display quality and efficiency.
Implementation Method 1
a gamma voltage supplying unit establishing a gamma voltage corresponding to each gray level according to a predetermined T-V curve
Implementation Method 2
liquid crystal is affected by 0.2V. Therefore, the image data of the black level displayed at a current frame remains at a next frame
Data Source
AI summary
A liquid crystal display device includes a liquid crystal panel; a gamma voltage supplying unit establishing a gamma voltage corresponding to each gray level according to a predetermined T-V curve; and a data driving unit changing digital image data into analog image data using the gamma voltage and outputting the analog image data to the liquid crystal panel, wherein the gamma voltage corresponding to a black level is configured to have a value within a range of 0 V to 0.005 V.