Pixel Circuit Compensation for OLED Brightness Uniformity
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Solution Overview
Problem
Existing organic light emitting display devices experience uneven brightness due to internal resistance drops in the supply voltage, leading to differences in current flow through light emitting diodes across pixel circuits.
Innovation Solution
A pixel circuit design incorporating multiple thin film transistors and capacitors, along with a compensation voltage signal line, which partially compensates for the supply voltage and helps in reducing the influence of internal resistance drops, ensuring consistent current flow through light emitting diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same power source supplies voltage to multiple pixel circuits, then the circuit structure is simple, but internal resistance drops cause uneven brightness
Solution Approach 1:
The invention introduces a compensation electrode that is segmented and connected to multiple pixel circuits through compensation lines. This electrode provides localized voltage compensation to each pixel circuit, dividing the compensation function into distributed segments rather than using a single centralized power source, thereby addressing the brightness uniformity issue while maintaining structural simplicity.
Solution Approach 2:
The compensation electrode acts as an intermediary between the power source and the pixel circuits. It receives compensation voltage signals and distributes them to pixel circuits experiencing voltage drops, mediating the effect of internal resistance and ensuring uniform brightness without requiring separate power sources for each pixel.
2Illumination intensity
If compensation voltage is applied to all pixel circuits, then brightness uniformity improves, but power consumption increases
Solution Approach 1:
The compensation voltage signal is dynamically adjusted based on the actual voltage drop conditions in different pixel circuits. The compensation electrode modulates the compensation voltage according to the emission control signals and the specific needs of each pixel region, applying compensation only where and when voltage drops occur, thereby reducing overall power consumption while maintaining brightness uniformity.
Solution Approach 2:
The invention changes the voltage parameter of the compensation signal dynamically. The compensation voltage varies in magnitude and timing based on the emission phase and the detected voltage drop conditions, allowing the system to optimize power consumption by applying minimal necessary compensation rather than constant full-strength compensation to all pixels.
Data Source
AI summary
A pixel circuit and a driving method thereof, a display device are provided. The pixel circuit includes: a first thin film transistor, a second thin film transistor, a third thin film transistor, a fourth thin film transistor, a fifth thin film transistor, a sixth thin film transistor, a seventh thin film transistor, an eighth thin film transistor, a ninth thin film transistor, a first capacitor, a second capacitor, and a light emitting diode. In the pixel circuit provided by the embodiment of the application, a compensation voltage provided by a compensation voltage signal line can partially compensate a supply voltage during an emission stage of the pixel circuit.