Pixel Circuit Voltage Compensation for OLED Luminance Uniformity
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Solution Overview
Problem
Existing organic light-emitting display devices experience uneven display luminance due to power supply voltage drops, resulting in different currents flowing through each light-emitting diode.
Innovation Solution
A pixel circuit comprising seven thin film transistors and a storage capacitor, where the current flowing through the light-emitting diode is independent of the power supply voltage, controlled by data and reference voltages, effectively compensating for power supply voltage drops and threshold voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple pixel circuits share a common power source, then device complexity is reduced, but power supply voltage drop causes uneven display luminance
Solution Approach 1:
The patent divides the power supply system by introducing local reference voltage signal lines for each pixel circuit, segmenting the common power source into multiple independent voltage reference channels. This allows each pixel circuit to compensate for its own voltage drop independently, resolving the contradiction between simplified power supply structure and uniform display luminance.
Solution Approach 2:
The patent changes the voltage parameter by introducing reference voltages with different potential values to different pixel circuits. By adjusting and compensating the gate voltage of driving transistors based on these reference voltages, the system compensates for power supply voltage drops and ensures uniform current distribution across all pixel circuits.
2Ease of manufacture
If pixel circuits use simplified driving structures, then ease of manufacture increases, but threshold voltage variations cause current inconsistency
Solution Approach 1:
The patent applies preliminary action by pre-compensating for threshold voltage variations through the reference voltage signal lines before the pixel circuits operate. The reference voltages are designed to counteract the threshold voltage differences of driving transistors, ensuring that current consistency is achieved without requiring complex post-manufacturing adjustments.
3Power
If power supply voltage is increased to compensate for voltage drop, then current through light-emitting diode increases, but power consumption increases
Solution Approach 1:
The patent changes the voltage distribution parameter by introducing reference voltage signal lines that provide localized voltage compensation. Instead of increasing the overall power supply voltage, the system adjusts the gate voltage of driving transistors using reference voltages, thereby maintaining the required current through light-emitting diodes without increasing overall power consumption.
Data Source
AI summary
The disclosure discloses a pixel circuit, a driving method thereof, and a display device. 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 transistors, a light-emitting diodes and a storage capacitor.