Local Dimming Directivity Filter Tuning for LCD Artifact Reduction
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Solution Overview
Problem
The image quality of LCD devices with local dimming function is affected by light directivity characteristics of backlight sources, leading to display artifacts such as halo, flicker, and brightness unevenness.
Innovation Solution
A method to tune the directivity filter of the local dimming function by measuring luminance levels under specific lighting conditions using a reduced number of test patterns, calculating V/H or V, H, and D parameters, and determining filter coefficients to control light source brightness based on light directivity characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional multiple test patterns are used for tuning local dimming, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent extracts only the essential luminance measurement data needed for tuning local dimming by selectively measuring specific zones (center zone and four corner zones) rather than进行全面 measurement. This extraction approach maintains sufficient tuning accuracy while significantly reducing measurement time and complexity.
Solution Approach 2:
The patent applies partial action by using a reduced set of test patterns (first, second, and third test patterns with specific luminance distributions) instead of comprehensive test patterns. This partial measurement approach provides enough information for effective tuning while minimizing time loss.
2Manufacturing precision
If comprehensive test patterns are used for tuning, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the measurement process into distinct test patterns (first, second, third) with specific luminance distributions, where each pattern targets particular zones of the display panel. This segmentation simplifies the overall measurement complexity while maintaining manufacturing precision through systematic data collection.
Solution Approach 2:
The patent applies local quality by focusing measurements on specific zones (center and corner zones) rather than uniformly measuring the entire display panel. This localized measurement approach reduces device complexity by concentrating resources on critical areas that most impact local dimming performance.
Data Source
AI summary
A method for tuning a local dimming function includes measuring a first luminance level of a measurement area of a display panel while the display panel is illuminated with four light sources of a backlight device, the four light sources being arranged in two rows and two columns. The method further includes measuring a second luminance level of the measurement area while the display panel is illuminated with two of the four light sources, the two of the four light sources being arranged in the same row or the same column. The method further includes measuring a third luminance level of the measurement area while the display panel is illuminated with one of the four light sources. The method further includes determining, based on the first, second, and third luminance levels of the measurement area, filter coefficients of a directivity filter used for a local dimming function.