Local Dimming Backlight Control for VR Display Artifacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional liquid crystal display (LCD) panels in virtual and augmented reality headsets suffer from display artifacts such as light leakage, poor contrast ratios, and ghosting due to their reliance on local-dimming capable backlights, which are prone to haloing and have slower refresh rates, affecting user experience, especially with rapidly moving objects on dark backgrounds.
Innovation Solution
A computer-implemented method for local dimming of backlights in brightness-controlled environments, where the absolute brightness levels of image blocks are determined, and relative brightness levels are calculated using an internal reference or human perception models to adjust illumination levels of the backlight array, preventing external brightness influence and reducing visual artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional LCD panels with local-dimming backlights are used, then contrast ratios and black levels are improved, but haloing artifacts and ghosting trails occur
Solution Approach 1:
The system performs preliminary analysis of the image content to identify bright objects on dark backgrounds before displaying. It pre-calculates the optimal backlight illumination levels for each local dimming zone based on the detected image characteristics, preparing the backlight configuration in advance to prevent haloing artifacts and ghosting trails before they occur during display.
Solution Approach 2:
The backlight illumination levels are dynamically adjusted in real-time based on the detected image content and motion characteristics. The system continuously monitors for moving objects and adapts the local dimming zones' brightness levels dynamically, increasing refresh rates for regions with motion to eliminate ghosting trails while maintaining high contrast ratios for static regions.
2Illumination intensity
If local-dimming capable backlights are used to enhance contrast, then black levels are improved, but refresh rates decrease
Solution Approach 1:
The display panel is divided into multiple local dimming zones, each controlled independently by separate backlight units. This segmentation allows different refresh rates to be applied to different zones simultaneously - zones with static content use lower refresh rates to conserve power, while zones with moving objects use higher refresh rates to prevent ghosting, thus maintaining good black levels without uniformly reducing overall refresh rate.
Solution Approach 2:
The system dynamically changes the illumination parameters of different backlight zones based on content analysis. For regions displaying fast-moving objects, the system increases the refresh rate parameter and adjusts illumination timing to reduce motion artifacts. For static regions, it maintains lower refresh rates while preserving deep black levels through effective local dimming, thus optimizing the trade-off between refresh rate and black level performance across different areas.
3Illumination intensity
If conventional LCDs with local-dimming backlights are used, then contrast ratios are improved for high-contrast images, but display artifacts increase for rapidly moving objects
Solution Approach 1:
The system incorporates feedback mechanisms that continuously analyze the displayed content and detect the presence of rapidly moving objects. Based on this feedback, it automatically adjusts the backlight refresh rates and illumination timing for affected zones. This closed-loop control ensures that contrast ratios are maintained for high-contrast static images while simultaneously reducing display artifacts like ghosting trails when fast motion is detected, thereby improving overall display reliability.
Data Source
AI summary
The disclosed display device may include (1) a display panel including pixel regions, (2) a backlight array coupled to the display panel that includes luminous elements, (3) a display housing configured to substantially prevent a user from referencing external brightness levels, (4) a display driver configured to receive an image including image blocks and scan the image to the display panel, and (5) a backlight driver configured to (a) determine an absolute brightness level of each of the image blocks, (b) derive, for each of the image blocks, a relative brightness level, (c) calculate, for each of the luminous elements, an illumination level based on the relative brightness level of a corresponding portion of the image blocks, and (d) illuminate, while the image is displayed via the display panel, each of the luminous elements according to the illumination level. Various other apparatus, systems, and methods are also disclosed.