AMOLED Brightness Compensation via Voltage Data Conversion
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Solution Overview
Problem
AMOLED displays experience uneven brightness due to differences in threshold voltage and intrinsic conducting factor of the driving TFT and OLED, leading to non-uniform display performance even with the same voltage difference across the TFT.
Innovation Solution
A compensation system comprising a grayscale data conversion unit, a compensation unit, a compensation data storage unit, and a voltage data conversion unit, which convert initial grayscale data into driving voltage data, compensate it using stored coefficients, and output adjusted data to the source driver to achieve uniform brightness across the AMOLED display, reducing the required data amount for compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If voltage signals are used to drive AMOLED pixels, then the display can be controlled by standard ICs, but brightness uniformity deteriorates due to variations in TFT threshold voltage and OLED characteristics
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation data in a lookup table during the manufacturing process. The compensation values for different gray levels are determined in advance based on measured pixel characteristics, and this compensation data is integrated into the display driver IC before the display is assembled. This allows the compensation to be automatically applied during normal operation without requiring real-time measurements or complex calculations, thus maintaining brightness uniformity while using standard voltage-driven ICs.
2Manufacturing precision
If compensation data is stored for all possible gray levels, then brightness uniformity is improved, but the data storage requirement increases significantly
Solution Approach 1:
The patent applies local quality by dividing the compensation approach into two distinct parts with different data requirements: a small lookup table storing only critical compensation parameters (such as maximum compensation values and key gray level corrections) that fit in limited on-chip memory, and a larger compensation data structure stored externally in frame buffer memory. This allows the system to achieve comprehensive compensation coverage while minimizing the memory burden on the display driver IC itself.
Solution Approach 2:
The patent resolves the memory constraint by transitioning from a single-dimension storage solution to a two-dimension architecture: small, fast on-chip lookup tables for immediate compensation access, and large external frame buffer memory for complete compensation data. This dimensional separation allows the system to have both rapid response for critical corrections and comprehensive data for full gray level compensation without requiring large on-chip memory resources.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively compensates for brightness variations, ensuring uniformity in AMOLED displays by adjusting driving voltage data, thereby reducing the necessary data amount and simplifying the compensation process.
Implementation Method 1
the grayscale data converting unit converts the initial grayscale data into initial driving voltage data corresponding to the initial grayscale data
Implementation Method 2
the compensation unit compensates the initial driving voltage data transmitted by the grayscale data conversion unit by using the compensation ratio coefficient and the compensation voltage data
Implementation Method 3
the voltage data conversion unit converts the compensation driving voltage data transmitted by the compensation unit into compensation grayscale data
Implementation Method 4
When a current flows through the OLED, the OLED emits light, and the light-emitting brightness is determined by the current flowing through the OLED itself
Data Source
AI summary
The present invention provides a compensation system and a compensation method for AMOLED display. In the system, the initial grayscale data is inputted into the grayscale data converting unit, the initial grayscale data is converted into the initial driving voltage data corresponding to the initial grayscale data by the grayscale data converting unit, and the initial grayscale data is transmitted to the compensation unit; the compensation unit compensates the initial driving voltage data by using the compensation ratio coefficient and the compensation voltage data in the compensation data storage unit and outputs the compensation driving voltage data to the voltage data conversion unit; the voltage data conversion unit then converts the compensation driving voltage data into the compensation grayscale data and outputs the compensation grayscale data to the source driver of the AMOLED display to uniformly compensate the AMOLED display by compensating the initial driving voltage data, which is capable of reducing the required data amount of compensation.