Pixel Driving Scheme for Accurate Low-Grayscale Display
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Solution Overview
Problem
Display devices face challenges in accurately expressing low grayscales due to dispersion of driving current and leakage currents, leading to inaccurate color representation.
Innovation Solution
The display device employs a data driver to provide two data signals in a frame period, with the pixel emitting light differently in each period based on the grayscale value, using a controller to generate data values that adjust the luminance and emission periods to enhance grayscale accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single data signal is provided to the pixel in a frame period, then the device complexity is low, but the grayscale expression accuracy deteriorates due to current dispersion and leakage
Solution Approach 1:
The frame period is divided into two distinct periods (first period and second period), and the single data signal is segmented into two separate data signals (first data signal and second data signal). Each data signal controls light emission in its respective period, allowing independent optimization of driving current intensity for each grayscale level, thereby improving grayscale expression accuracy while managing device complexity through structured segmentation
2Measurement precision
If the driving current intensity is increased to improve low grayscale expression, then the grayscale accuracy improves, but color shift increases due to current magnitude effects
Solution Approach 1:
The patent implements periodic action by alternating between two emission periods with different data signals. For low grayscale values, the first data signal provides higher current intensity in the first period to overcome leakage effects, while the second data signal provides lower current intensity in the second period to maintain color accuracy. This periodic alternation allows the system to achieve both accurate low grayscale expression and color consistency
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the intensity parameters of the driving current based on the grayscale value and emission period. The first data signal uses higher current intensity parameters for low grayscale values, while the second data signal uses lower current intensity parameters. This parameter adjustment strategy enables accurate representation of low grayscales while minimizing color shifts through controlled current magnitude variation
3Measurement precision
If dual data signals are used to improve grayscale accuracy, then the luminance control precision improves, but the device complexity increases
Solution Approach 1:
The data driver structure is segmented into two distinct signal generation paths, each handling specific grayscale ranges and emission periods. The first data signal path handles low grayscale values with higher current intensity, while the second data signal path handles all grayscale values with lower current intensity. This segmentation allows the complex dual-signal system to be managed through modular, independent signal generation paths
Solution Approach 2:
The patent implements dynamics by making the data driver adaptable and configurable based on operating conditions. The data driver dynamically selects which data signal to use based on the grayscale value, and can be configured to operate in different modes (single period or dual period). This dynamic adaptability reduces the effective complexity by enabling the system to simplify to single-signal operation when high grayscale accuracy is not required
Data Source
AI summary
A display device includes a pixel including a light-emitting element, and a data driver configured to sequentially provide first and second data signals to the pixel in a frame period including a first period and a second period, wherein the pixel is configured to emit light during the first period based on the first data signal, and to emit light during the second period based on the second data signal, wherein, when a grayscale value for the pixel is greater than a reference grayscale value, the pixel is configured to equally emit light in the first period and the second period, and wherein, when the grayscale value is less than or equal to the reference grayscale value, the pixel is configured to emit light differently in the first period compared to the second period, or to emit light in the first period while not emitting light in the second period.