CABC Control Circuit for Smooth Backlight Luminance Reduction
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Solution Overview
Problem
Existing control circuits for CABC (Content Adaptive Brightness Control) in display devices face challenges in reducing power consumption while maintaining image quality, as current methods often result in abrupt luminance changes and discomfort due to large circuit sizes and inefficient luminance control.
Innovation Solution
A control circuit that calculates a feature value using a polynomial function of the average and maximal gradation values of the video signal, with coefficients set to control backlight luminance smoothly, reducing power consumption without abrupt changes in image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the circuit for calculating the feature value is made large to improve image quality control, then the luminance reduction control becomes more accurate, but the power consumption of the circuit increases
Solution Approach 1:
The patent extracts only the essential feature values (average and maximum gradation values) needed for luminance control, discarding unnecessary calculation components. This selective extraction maintains adequate control accuracy while significantly reducing circuit complexity and power consumption compared to comprehensive image analysis circuits.
Solution Approach 2:
The patent changes the calculation parameters from complex multi-dimensional image features to simplified gradation value parameters (average and maximum). This parameter transformation maintains the essential control functionality while reducing computational complexity and circuit scale, thereby lowering power consumption.
2Loss of energy
If the B/L luminance is reduced significantly to achieve low power consumption, then energy savings increase, but the image quality deteriorates with abrupt luminance changes
Solution Approach 1:
The patent implements dynamic luminance control where the backlight luminance is adjusted continuously based on the calculated feature values of the video signal. This dynamic adjustment follows the content characteristics, providing significant power savings for dark scenes while maintaining smooth transitions and avoiding abrupt changes that would degrade image quality.
Solution Approach 2:
The system uses feedback from the video signal analysis (average and maximum gradation values) to continuously adjust the backlight luminance. This feedback mechanism ensures that luminance changes are proportional to the actual image content, achieving energy efficiency while maintaining visual comfort through continuous rather than abrupt transitions.
3Measurement precision
If the histogram method is used to calculate feature values, then the gradation distribution is accurately captured, but the luminance changes discontinuously causing image quality discomfort
Solution Approach 1:
Instead of using the complete histogram method which processes all gradation bins, the patent extracts only two critical parameters: the average gradation value representing overall brightness and the maximum gradation value representing peak luminance. This extraction maintains sufficient accuracy for luminance control while avoiding the discontinuous changes inherent in full histogram analysis.
Solution Approach 2:
The patent transforms the complex histogram parameter set into simplified average and maximum gradation parameters. This parameter change maintains the essential information needed for luminance control while ensuring continuous variation, thereby eliminating the discontinuous luminance changes and associated image quality discomfort.
4Use of energy by moving object
If the circuit scale is reduced to achieve low power consumption, then energy efficiency improves, but the ability to maintain image quality deteriorates
Solution Approach 1:
The patent extracts only the two most critical features (average and maximum gradation values) needed for effective luminance control, eliminating unnecessary calculation circuits. This selective extraction maintains adequate image quality control while significantly reducing circuit scale and power consumption.
Solution Approach 2:
The patent changes from complex image analysis parameters to simplified gradation-based parameters that can be calculated with minimal circuitry. This parameter transformation maintains the essential control functionality for image quality while enabling a compact, low-power circuit implementation.
Data Source
AI summary
A control circuit having large effects of low power consumption in CABC drive is provided. The control circuit performs B/L luminance reduction in eliminating a discomfort in image quality by using the feature value calculation circuit in the video signal. The control circuit comprises a luminance control circuit controlling a backlight luminance according to an inputted video signal and a gradation conversion circuit for converting a gradation of inputted video signal according to a controlled luminance. The control circuit reduces continuously and smoothly the backlight luminance, while the screen area reaches one-pixel white, in case where the all white is inputted as video signal, one-pixel black is displayed in any screen area from a display condition of all white, a rate of screen area displaying one-pixel black is gradually increased, and the video signal is continuously changed until the screen area of all white reaches the one-pixel white.