High-Bit-Depth Display Driving With Variable Current and Timing
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Solution Overview
Problem
Conventional micro-LED displays face limitations in achieving higher bit depth and frame rates due to fixed voltage or current levels, leading to inaccuracies and restrictions in representing grayscale values, especially when applying gamma correction.
Innovation Solution
A display system that varies pixel drive currents and time intervals dynamically within a frame, using a flexible sequence of bit planes to combine time and current/voltage modulation for intensity control, allowing real-time adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a digital drive scheme using PWM is used to control pixel intensity, then grayscale representation is improved, but the frame rate is limited due to the large number of bit planes required
Solution Approach 1:
The patent segments the grayscale representation into multiple bit planes, where each bit plane carries a specific weight. By transmitting multiple bit planes sequentially and accumulating their contributions, the system achieves high precision grayscale representation while managing the time required through efficient segmentation of the data transmission process
Solution Approach 2:
The patent employs periodic transmission of bit planes within each frame, where multiple bit planes are transmitted in sequence during the frame time. This periodic action allows the system to distribute the transmission of high-precision grayscale data across multiple time intervals, enabling both high precision and maintained frame rate
2Measurement precision
If gamma correction is applied to expand grayscale data, then color depth accuracy is improved, but the number of bit planes required increases significantly
Solution Approach 1:
The patent applies gamma correction as a preliminary processing step to the grayscale data before it is segmented into bit planes. By pre-processing the data with gamma correction, the system expands the grayscale values to achieve accurate color depth representation, and then segments the corrected data into manageable bit planes for transmission
Solution Approach 2:
The patent changes the parameter representation by applying gamma correction to transform the grayscale values from linear to gamma-encoded space. This parameter transformation allows the system to represent a wider range of intensities with the same number of bits, effectively improving color depth accuracy without proportionally increasing the number of bit planes required
3Device complexity
If fixed voltage or current levels are used in digital drive schemes, then system simplicity is maintained, but inaccuracies and drift occur in analog representations
Solution Approach 1:
The patent introduces dynamic current levels that can be adjusted for each bit plane during the transmission process. Instead of using fixed current levels, the system dynamically modifies the current based on the specific bit plane being transmitted, allowing for more precise control of pixel intensity while maintaining a relatively simple digital drive architecture
Solution Approach 2:
The patent replaces the traditional analog voltage drive mechanism with a digital pulse-based system that uses controlled current pulses of varying durations and magnitudes. This substitution eliminates the drift and inaccuracy issues associated with analog voltage levels while maintaining digital system simplicity, as the pixel intensity is controlled through the duration and amplitude of digital current pulses rather than continuous analog voltage
Data Source
AI summary
Systems and methods for varying an intensity of pixels of displays are provided. A display subsystem may include a display driver for receiving image frame data and commands from an image or data source, including pixel intensity values for bit planes of an image frame; a parser for receiving the image frame data and the commands, and configured to determine a drive waveform having an pixel drive value and a pixel drive time interval for each bit plane of the image frame data; a display backplane for receiving the drive waveform, the display backplane including a pixel array comprising an array of pixels, each pixel driven by a pixel circuit; and display driver circuitry for driving the pixels in accordance with the drive waveform; and wherein an intensity of the pixel varies for each bit plane according to the pixel drive value and the pixel drive time interval.