Local Dimming LCD Gray Level Calibration for Contrast
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Solution Overview
Problem
In liquid crystal display (LCD) devices using local dimming technology, pixels with low gray levels are often represented brighter than intended due to neighboring bright pixels, leading to reduced contrast ratios and increased power consumption.
Innovation Solution
An LCD device and driving method that calibrate gray levels by adjusting the amount of light emitted from each pixel based on the difference between ideal and actual light incidence, using a processor to calculate and apply gray level adjustments to ensure accurate representation of low gray levels, even in the presence of significant gray level differences among adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If local dimming technology is applied to enhance contrast ratio, then contrast ratio is improved, but gray level accuracy deteriorates due to light leakage from neighboring bright pixels
Solution Approach 1:
The patent applies preliminary anti-action by calculating compensation values before displaying the image. The processor pre-calculates how much light leakage will occur from each backlight region to adjacent pixels, and applies compensatory adjustments to the gray levels in advance. This prevents the gray level accuracy problem from occurring in the first place, rather than trying to fix it after the fact.
Solution Approach 2:
The patent implements local quality by applying different compensation strategies to different regions of the display. Each pixel's gray level is adjusted based on its specific location and the characteristics of its neighboring backlights. The compensation value for each pixel is calculated individually considering the local backlight distribution, ensuring that each region receives appropriate compensation tailored to its specific conditions.
2Use of energy by moving object
If local dimming technology is applied to reduce power consumption, then power efficiency is improved, but image quality deteriorates due to incomplete dark representation
Solution Approach 1:
The patent employs feedback by using the calculated light leakage information to adjust gray levels. The system calculates how much light each backlight emits and how much leaks to neighboring pixels, then uses this feedback information to compensate by adjusting the gray levels accordingly. This closed-loop approach ensures that power consumption is optimized while maintaining image quality through continuous adjustment based on actual backlight behavior.
Solution Approach 2:
The patent applies parameter changes by modifying the gray level parameters of pixels based on backlight characteristics. The processor changes the gray level parameters dynamically according to the backlight's emission intensity and the resulting light leakage patterns. This allows the system to maintain reliable image quality while optimizing power consumption by adjusting parameters rather than using fixed values.
3Use of energy by moving object
If multiple backlights are used for local dimming, then power efficiency is improved, but device complexity increases due to gray level calibration requirements
Solution Approach 1:
The patent applies self-service by having the processor automatically calculate and apply compensation values without requiring external calibration procedures. The system performs its own gray level calibration by internally calculating the light leakage patterns and automatically adjusting the gray levels accordingly. This eliminates the need for complex external calibration equipment or procedures, reducing device complexity while maintaining power efficiency benefits.
Data Source
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AI summary
Disclosed is a local dimming liquid crystal display device. The present local dimming liquid crystal display device comprises: a display panel unit having a plurality of pixels; a panel driving unit for driving each of the plurality of pixels; a backlight unit comprising a plurality of backlights for dividing the display panel unit into a plurality of areas to emit light to each of the plurality of regions; a backlight driving unit for driving the plurality of backlights on the basis of gray level information of the plurality of pixels corresponding to each of the plurality of areas; and a processor for calculating a first amount of light to be incident on each pixel on the basis of the gray level of each pixel, calculating a second amount of light incident on each pixel in accordance with a driving state of the plurality of back lights, changing the gray level of at least one of the plurality of pixels on the basis of the difference between the first amount of light and the second amount of light, and controlling the panel driving unit on the basis of the changed gray level.