Black-Grayscale Correction Circuit for OLED Contrast
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Solution Overview
Problem
Existing display devices, particularly organic light emitting display devices, face challenges in achieving optimal black-level luminance and image quality due to the need for precise tuning, which can be difficult to manufacture and result in lower contrast ratios compared to liquid crystal display devices.
Innovation Solution
A display device with a black-grayscale correcting circuit that adjusts the black-level of grayscale data based on the color of pixels, their position on the panel, and the grayscale data of previous and next horizontal periods, converting this corrected data into data voltages for improved luminance and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If organic light emitting display device uses precise black-level tuning, then black-level luminance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal black-level correction values in a lookup table (LUT) during the manufacturing process. The black-grayscale correcting circuit then retrieves and applies these pre-computed correction values during operation, eliminating the need for complex real-time tuning while achieving precise black-level control.
Solution Approach 2:
The patent changes the parameter approach by transforming the continuous black-level tuning problem into a discrete correction value selection problem. By converting grayscale data through predefined correction curves and lookup tables with different gamma values, the system achieves precise black-level control through parameter selection rather than complex continuous adjustment.
2Reliability
If organic light emitting display device achieves high contrast ratio, then image quality is improved, but black-level optimization becomes more difficult to manufacture
Solution Approach 1:
The patent applies local quality by implementing position-dependent black-level correction. The black-grayscale correcting circuit identifies the pixel position and applies location-specific correction values from the lookup table, allowing different regions of the display to have optimized black levels tailored to their specific characteristics, thereby achieving high contrast ratio without uniform complex tuning across the entire panel.
Solution Approach 2:
The patent uses preliminary action by pre-determining and storing position-specific black-level correction values in the lookup table during manufacturing. This allows the display to achieve high contrast ratio through simple retrieval and application of pre-optimized correction values rather than requiring complex real-time adjustment mechanisms.
3Illumination intensity
If black-level correction is applied to all grayscale data, then luminance is improved, but processing time increases
Solution Approach 1:
The patent applies partial action by selectively correcting only the black-grayscale data portions of the image signal while leaving other grayscale levels unchanged. The black-grayscale correcting circuit identifies black-grayscale data and applies correction only to those specific data points, reducing processing overhead while maintaining improved luminance where it matters most for image quality.
Solution Approach 2:
The patent uses preliminary action by pre-computing and storing correction values for all possible black-grayscale input values in the lookup table during manufacturing. During operation, the system simply retrieves the pre-computed correction value based on the input grayscale value, transforming a complex real-time calculation into a simple table lookup operation that minimizes processing time.
Data Source
AI summary
A display device includes a display panel including a plurality of data lines and a plurality of color pixels arranged into rows, a black-grayscale correcting circuit, and a data driving circuit. The black-grayscale circuit corrects a black-level of black-grayscale data of input grayscale data to generate corrected image data. The black-grayscale circuit corrects the black-grayscale data to be applied to a current one of the rows during a current horizontal period based on the input grayscale data to be applied to a previous one of the rows during a previous horizontal period and the input grayscale data to be applied to a next one of the rows during a next horizontal period. The data driving circuit converts the corrected image data into data voltages for output to the data lines.