Liquid Crystal Display Voltage Adjustment for Still Image Quality
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Solution Overview
Problem
Liquid crystal display devices face challenges in maintaining image quality and reducing power consumption when displaying still images with a reduced refresh rate, as voltage fluctuations due to off-state current and leakage current affect the gray level, leading to deteriorated image quality and insufficient power savings.
Innovation Solution
A liquid crystal display device with a timing controller that adjusts the absolute voltage applied to normally white or black mode liquid crystals based on the gray level number of the image signal, increasing voltage for still images to maintain image quality and reduce refresh rate, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the refresh rate is reduced when displaying a still image, then power consumption is reduced, but the gray level changes due to voltage fluctuations from off-state current and leakage current, deteriorating image quality
Solution Approach 1:
The patent applies parameter changes by adjusting the voltage applied to the liquid crystal based on the gray level number. Specifically, when a still image is displayed with a reduced refresh rate, the absolute value of the voltage is increased for lower gray level numbers (darker pixels) to compensate for voltage drops caused by leakage current. This dynamic voltage adjustment maintains accurate gray levels while enabling lower refresh rates and reduced power consumption.
2Manufacturing precision
If the refresh rate is kept high to maintain gray level stability, then image quality is maintained, but power consumption cannot be sufficiently reduced
Solution Approach 1:
The patent enables refresh rate optimization by changing the voltage parameter dynamically. By applying higher absolute voltage values during still image display with reduced refresh rates, the system compensates for the cumulative effect of leakage current over the longer display period, thereby maintaining gray level stability without requiring high refresh rates, thus reducing power consumption.
Solution Approach 2:
The patent introduces dynamic voltage adjustment based on display conditions. The voltage applied to each pixel is not fixed but is dynamically modified according to the gray level number and display mode (still image vs. moving image), allowing the system to adapt to different operational requirements and optimize both image quality and power consumption.
3Manufacturing precision
If the absolute value of voltage applied to liquid crystal is increased for still images, then gray level accuracy is maintained with reduced refresh rate, but power consumption increases
Solution Approach 1:
The patent applies local quality by differentiating voltage adjustment based on gray level number. Instead of uniformly increasing voltage for all pixels, the patent specifically increases the absolute voltage for pixels with lower gray level numbers (which are more susceptible to voltage drop and appear darker). This selective approach maintains image quality where needed while minimizing unnecessary power consumption increases.
Data Source
AI summary
To suppress deterioration of quality of a still image displayed with a reduced refresh rate. A liquid crystal display device includes a display portion that is controlled by a driver circuit and includes normally white mode (or normally black mode) liquid crystals, and a timing controller for controlling the driver circuit. The timing controller is supplied with an image signal for displaying a moving image and an image signal for displaying a still image. The absolute value of a voltage applied to the liquid crystals in order to express black (or white) in an image corresponding to the image signal for displaying the still image is larger than that of a voltage applied to the liquid crystals in order to express black (or white) in an image corresponding to the image signal for displaying the moving image.