LCD Zone Backlight Gain and Compensation Control
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Solution Overview
Problem
Existing liquid crystal display (LCD) technologies face limitations in dynamic contrast quality due to the inability to effectively control backlight brightness across zones, leading to inadequate representation of image details and hierarchy, especially at high and low brightness levels.
Innovation Solution
The proposed solution involves an apparatus and method that determines grayscale values for pixels in zone image data blocks, applies a backlight value gain coefficient when the zone backlight value exceeds a threshold to enhance peak brightness, and uses compensation coefficients when the zone backlight value is below a threshold to improve image hierarchy, utilizing a lookup table to determine optimal gain and compensation coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If dynamic backlight modulation is applied globally, then energy consumption is reduced and display contrast is improved, but local image details and hierarchy are lost due to uniform brightness control
Solution Approach 1:
The patent divides the backlight assembly into multiple independently controllable zones (e.g., first backlight zone, second backlight zone, etc.), each with its own driver circuit. This segmentation allows different backlight zones to be adjusted independently, preserving local image details while still enabling overall energy savings through selective dimming of less critical zones.
Solution Approach 2:
The patent applies different brightness control strategies to different zones based on local image characteristics. High-importance zones receive enhanced brightness control to preserve details, while low-importance zones can be dimmed more aggressively for energy savings. This local differentiation resolves the contradiction between global energy efficiency and local detail preservation.
2Illumination intensity
If zone backlight values are increased to improve peak brightness, then dynamic contrast is enhanced, but low brightness areas lose image hierarchy
Solution Approach 1:
The patent introduces gain coefficients (greater than 1) that are applied selectively to zone backlight values based on image brightness characteristics. For zones with high brightness requirements, the gain coefficient amplifies the backlight value to enhance peak brightness. For zones with low brightness, different compensation coefficients are used to maintain image hierarchy. This dynamic parameter adjustment resolves the contradiction between peak brightness enhancement and low brightness area quality.
3Illumination intensity
If gain coefficients are applied to enhance backlight brightness, then peak brightness is improved, but low brightness zones require separate compensation to maintain hierarchy
Solution Approach 1:
The patent pre-calculates and stores compensation coefficient lookup tables that map image brightness levels to appropriate compensation values. This preliminary preparation allows the control algorithm to quickly retrieve and apply the correct compensation coefficient without complex real-time calculations, thereby reducing algorithmic complexity while maintaining the ability to compensate for low brightness areas after gain application.
4Manufacturing precision
If multiple thresholds are used to differentiate brightness zones, then image hierarchy is preserved, but control system complexity increases
Solution Approach 1:
The patent uses multiple brightness thresholds (first threshold, second threshold, etc.) to divide the image into different brightness zones, each requiring different levels of compensation. To manage the complexity of multiple thresholds, the system employs a lookup table approach where pre-calculated compensation coefficients are stored and retrieved based on the threshold comparisons, simplifying the real-time control logic while maintaining precise brightness differentiation.
Data Source
AI summary
The disclosure provides an apparatus for controlling liquid crystal display brightness, the apparatus pre-obtaining a zone backlight value corresponding to a zone image data block according to grayscale values; if the zone backlight value is above a first threshold, multiplying the pre-obtained zone backlight value with a backlight value gain coefficient, which is more than 1, to a obtain backlight value to which a gain is applied, of a backlight zone corresponding to the zone image data block, outputting the backlight value to which the gain is applied, to a driver circuit of backlight source in the backlight zone to control brightness of the backlight source in the backlight zone as a result of driving; if the zone backlight value is below a second threshold, compensating for the grayscale values of the pixels in the zone image data block using compensation coefficients, each of which is more than 1.