Display Driver Gamma Curve Control for Grayscale Preservation
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Solution Overview
Problem
Display brightness control in display panels, such as liquid crystal and OLED panels, faces challenges in maintaining image quality and grayscale levels when reducing brightness, as existing methods often result in grayscale collapse due to the non-linear gamma property, leading to a reduction in usable grayscale values.
Innovation Solution
A display driver with gamma curve control circuitry generates multiple gamma curves for different brightness levels, and a converter controller adjusts the analog signal voltage amplitude of the DAC based on these curves, allowing for smooth brightness control without reducing the number of grayscale levels, thereby preventing grayscale collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If display brightness is reduced by adjusting output voltages and light emitting time, then power consumption is reduced, but grayscale levels collapse and image quality deteriorates
Solution Approach 1:
The patent implements dynamic gamma curve selection based on brightness levels. The gamma curve control circuitry switches between different gamma curves (first gamma curve for high brightness, second gamma curve for low brightness) depending on the current brightness level, allowing the system to adaptively optimize both power consumption and grayscale precision for each operating condition
Solution Approach 2:
The patent changes the gamma curve parameter based on brightness level. By selecting different gamma curves with appropriate characteristics for different brightness ranges, the system maintains accurate grayscale representation at low brightness while enabling aggressive brightness reduction for power savings
2Use of energy by stationary object
If the number of grayscale levels is reduced to control brightness, then power consumption decreases, but image resolution and quality are lost
Solution Approach 1:
The system dynamically adjusts the gamma curve based on brightness level rather than reducing grayscale levels. This dynamic adaptation allows the full range of grayscale information to be preserved and properly mapped to the display output, preventing information loss while achieving power savings through brightness control
Solution Approach 2:
By changing the gamma curve parameter according to brightness level, the patent ensures that all input grayscale values are effectively utilized. The second gamma curve for low brightness levels provides an optimized mapping that preserves image resolution while enabling lower power consumption
3Use of energy by stationary object
If existing brightness control methods are used, then power consumption is reduced, but additional lookup tables are required increasing memory usage and circuit size
Solution Approach 1:
The gamma curve control circuitry serves multiple functions: it generates both the first gamma curve for high brightness and the second gamma curve for low brightness, and it controls the DAC output voltage range. This multi-functionality eliminates the need for separate lookup tables while achieving effective brightness control across different power consumption levels
Data Source
AI summary
A display driver includes gamma curve control circuitry and a converter controller. The gamma curve control circuitry is configured to generate a first gamma curve for a first display brightness value (DBV), and a second gamma curve for a second DBV lower than the first DBV. The converter controller is configured to control a digital-analog converter (DAC) configured to perform digital-analog conversion of an input image data. Further, the converter controller is configured to adjust an analog signal voltage amplitude of the DAC based on a range of an output voltage associated with the second gamma curve.