Gamma Decoder DAC Switching for Lower-Power Display Driving
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Solution Overview
Problem
As display device resolution increases, the number of bits in digital image signals grows, leading to higher power consumption and increased capacity and element count for digital-analog converters, which is inefficient.
Innovation Solution
A digital-analog converter that reduces power consumption by turning off some gamma decoders in the global ramp using a ramp controller, which generates a ramp control signal based on the most significant bits of the digital image data to selectively disable gamma decoders during horizontal periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of bits of digital image signal increases to achieve higher resolution, then the resolution is improved, but power consumption increases and the capacity and number of elements for implementing the digital-analog converter increase
Solution Approach 1:
The patent divides the global ramp into multiple sub-ramps (first sub-global ramp and second sub-global ramp), each handling a specific range of grayscale values. This segmentation allows the system to process high-resolution images while only activating the necessary sub-ramp for the current image data range, reducing overall power consumption compared to a single full-range global ramp.
2Measurement precision
If all gamma decoders are kept active to ensure complete grayscale coverage, then the grayscale accuracy is maintained, but power consumption increases
Solution Approach 1:
The patent implements dynamic control of gamma decoders through a ramp controller that selectively activates only the necessary sub-ramp based on the most significant bits of the digital image data. This dynamic switching mechanism ensures that grayscale accuracy is maintained for the active range while minimizing power consumption by keeping inactive gamma decoders disabled.
3Adaptability or versatility
If the number of gamma decoders is increased to cover more grayscale values, then the grayscale range is expanded, but device complexity increases
Solution Approach 1:
The patent segments the global ramp into multiple sub-ramps with dedicated gamma decoders for specific grayscale ranges. This segmentation allows the system to achieve expanded grayscale coverage while managing complexity by only activating the necessary subset of decoders for each image, rather than requiring all decoders to be simultaneously operational.
Data Source
AI summary
A digital-analog converter of the disclosure converts digital image data to generate analog data signals. The digital-analog converter includes a voltage divider which generates a plurality of gamma reference voltages based on a first reference voltage and a second reference voltage; a global ramp including a plurality of gamma decoders which generates a plurality of global gamma voltages based on the gamma reference voltages; a decoder which selects one of the global gamma voltages according to the digital image data to generate the analog data signals; and a ramp controller which turns off at least some of the gamma decoders based on the digital image data.