Display Backlight Non-Uniformity Compensation via Point Spread Simulation
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Solution Overview
Problem
Backlights in electronic displays can exhibit brightness and color non-uniformities, leading to undesirable artifacts in displayed images due to manufacturing variations and light emission characteristics, which existing technologies fail to adequately address.
Innovation Solution
The implementation of control circuitry that adjusts pixel and backlight signals by simulating artificial backlight data based on target images and using stored point spread function information, combined with measured actual backlight data to compensate for brightness and color variations, ensuring uniform illumination across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a direct-lit backlight with local dimming is used, then brightness uniformity is improved, but color non-uniformity and artifacts such as grid mura and bluish edges still occur
Solution Approach 1:
The system performs preliminary characterization of the backlight's point spread function and non-uniformity patterns during manufacturing. This pre-acquired data is stored and later used to predict and compensate for image-dependent and white-point-dependent non-uniformities before they manifest as visible artifacts, enabling proactive correction rather than reactive adjustment
Solution Approach 2:
The system implements a feedback mechanism where the displayed image content and backlight state are continuously analyzed. The controller predicts non-uniformity patterns based on the current image and white point, then adjusts backlight signals accordingly to compensate for anticipated artifacts, creating a closed-loop system that actively maintains uniformity
2Manufacturing precision
If backlight signals are adjusted to compensate for non-uniformity, then image quality is improved, but power consumption increases
Solution Approach 1:
Instead of uniformly adjusting the entire backlight, the system applies compensation only to specific regions where non-uniformity is predicted to occur. By using the point spread function to identify localized artifacts such as grid mura and bluish edges, the controller adjusts only the necessary backlight zones, minimizing overall power consumption while maintaining image quality
Solution Approach 2:
The system dynamically changes backlight parameters (intensity, color temperature) based on the predicted non-uniformity patterns. By adjusting parameters locally and temporarily only when and where needed, rather than maintaining constant compensation across the entire display, the system reduces overall power consumption while still achieving the desired image quality
3Measurement precision
If point spread function information is used to simulate artificial backlight data, then compensation accuracy is improved, but device complexity increases
Solution Approach 1:
The complex task of characterizing the backlight's point spread function is performed once during manufacturing rather than in real-time during operation. This pre-computed information is stored in memory and reused for multiple images, reducing the ongoing computational burden and simplifying the real-time control circuitry while maintaining high compensation accuracy
Solution Approach 2:
Instead of performing complex physical measurements for each image, the system creates a digital model (point spread function) that replicates the backlight's behavior. This virtual copy allows the controller to predict non-uniformities through computation rather than measurement, reducing hardware complexity while maintaining precision
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
This approach effectively compensates for image-dependent and white-point-dependent non-uniformities, enhancing the dynamic range and image quality by providing uniform backlight illumination, thereby reducing power consumption and eliminating artifacts such as grid mura and bluish edges.
Implementation Method 1
one or more light sources emit light into an edge of a light guide plate that distributes the light across the array of pixels
Implementation Method 2
liquid crystal displays include pixels that do not produce light but instead are used to adjust the amount of light transmitted from a backlight through the display
Data Source
AI summary
An electronic device may include a display having an array of pixels and a backlight that provides backlight illumination for the array of pixels. The backlight may be a direct-lit backlight with a two-dimensional array of light-emitting diodes operable in a local dimming scheme. The electronic device may include control circuitry that provides pixel signals to the array of pixels and backlight signals to the backlight. The control circuitry may adjust the pixel signals and the backlight signals to compensate for brightness and color non-uniformity in the backlight. To compensate for image-dependent backlight non-uniformity, the control circuitry may simulate artificial backlight data based on the target image to be displayed and stored point spread information. To compensate for white-point-dependent backlight non-uniformity, the control circuitry may use measured actual backlight data that describes color variations across the backlight for a given target white point.