Active Matrix Display Voltage Drop Compensation
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Solution Overview
Problem
Active matrix displays, particularly organic electroluminescent (EL) displays, face a voltage reduction issue due to changes in the current flowing through the panel, which affects the gray level representation of pixels, as the power supply voltage drops when the total driving current increases, leading to inaccurate gray level expression.
Innovation Solution
A compensation circuit unit generates a compensation signal to counteract the voltage drop in the power line by calculating the total driving current flowing through the panel and adjusting the data signals transmitted to the data lines, ensuring consistent power supply voltage to the driving transistors, thereby maintaining accurate gray level representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the total driving current flowing through the panel increases to enhance display brightness, then the luminance is improved, but the power supply voltage drops due to voltage reduction, causing inaccurate gray level representation
Solution Approach 1:
The patent implements a feedback mechanism where the compensation circuit unit continuously monitors the actual voltage supplied to pixel circuits and compares it with the expected voltage. Based on this feedback, the data driver adjusts the data signals to compensate for voltage drops, ensuring accurate gray level representation even when the total driving current increases for enhanced brightness.
Solution Approach 2:
The patent changes the parameter of data signal voltage levels dynamically. The data driver modifies the voltage levels of data signals based on compensation values generated by the compensation circuit unit, allowing the system to adapt to varying power supply voltage conditions and maintain precise gray level control across different brightness levels.
2Adaptability or versatility
If the current flowing through the panel changes to adapt to different display content requirements, then the adaptability is improved, but the power supply voltage becomes unstable, affecting pixel circuit performance
Solution Approach 1:
The compensation circuit unit continuously monitors power supply voltage variations and provides real-time feedback to the data driver. This feedback loop enables the system to maintain stable pixel circuit operation despite changes in total driving current caused by different display content requirements, as the data signals are dynamically adjusted to compensate for voltage fluctuations.
Solution Approach 2:
The patent introduces dynamic adjustment capability where the data driver modifies data signal characteristics in real-time based on the compensation values from the compensation circuit unit. This dynamic response allows the system to adapt to varying current conditions while maintaining voltage stability for accurate pixel rendering.
Data Source
AI summary
An active matrix display may include: a panel including a plurality of scan lines which transmit scan signals, a plurality of data lines which transmit data signals in response to the scan signals from the scan lines, a plurality of pixel circuits which are formed in a plurality of pixels, and each of the pixel circuits include a display element and a driving transistor driving the display element, and a power line which supplies a driving current to the driving transistor; a scan driver selectively transmitting the scan signals to the scan lines; a compensation circuit unit generating a compensation signal for compensating a voltage drop of the power line which results from a change in a total driving current flowing through the panel; and a data driver compensating the data signals using the compensation signal and transmitting compensated data signals to the data lines.