Display Device Power Supply Voltage Adjustment for Transistor Compensation
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Solution Overview
Problem
Display devices face challenges in maintaining uniform image quality due to inherent characteristic deviations in driving transistors, such as threshold voltages and mobility, which can lead to luminance differences across images.
Innovation Solution
A display device and method that divide the operation period into a display period and a sensing period, where the voltage of the first power supplied to pixels is adjusted based on the grayscale of the data signal during the sensing period to reflect the channel length modulation effect of the driving transistor, allowing for accurate characterization and compensation of transistor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed voltage of first power is supplied to pixels during sensing period, then the sensing circuit can extract sensing current based on data signals, but channel length modulation effects cause compensation errors that reduce image quality
Solution Approach 1:
The patent applies dynamics by changing the voltage level of first power from a fixed value to a variable value that depends on the grayscale of the data signal. The power supply voltage is dynamically adjusted to different levels (e.g., first voltage level for first grayscale, second voltage level for second grayscale) to compensate for channel length modulation effects, thereby improving both sensing accuracy and image quality simultaneously
2Reliability
If the voltage of first power is changed based on grayscale during sensing period, then channel length modulation effect is reflected in compensation, but the power supply system becomes more complex
Solution Approach 1:
The patent applies parameter changes by modifying the voltage parameter of first power based on the grayscale parameter of data signals. The power supply system is configured to output different voltage levels corresponding to different grayscale values, allowing the system to reflect channel length modulation effects in compensation without requiring complex additional circuitry
Data Source
AI summary
A display device includes pixels connected to scan lines, control lines, data lines, and sensing lines; a scan driver configured to supply a scan signal to the scan lines and supply a control signal to the control lines; a data driver configured to supply one of an image data signal and a sensing data signal to the data lines; a sensing circuit configured to sense the characteristics based on a sensing current supplied through the sensing lines during the sensing period; and a power supply configured to supply a voltage of first power to the pixels. The sensing period includes a first sensing period during which a first sensing current is extracted based on a first sensing data signal corresponding to a first grayscale, and a second sensing period during which a second sensing current is extracted based on a second sensing data signal corresponding to a second grayscale, and the voltage of the first power supplied during the first sensing period is different from the voltage of the first power supplied during the second sensing period.