OLED Panel Compensation Voltage Lines for Brightness Uniformity
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Solution Overview
Problem
Conventional active-matrix OLED panels face issues with irregular brightness due to manufacturing variations and material properties affecting threshold voltage, leading to increased complexity and reduced aperture ratio with existing compensation circuits.
Innovation Solution
The OLED panel employs a system with sampling voltage lines and compensation voltage lines to generate compensation voltages, adjusting data signals and using compensation circuits with capacitors and switches to stabilize current through organic light-emitting diodes, reducing the impact of threshold voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional compensation circuits are added to compensate threshold voltage, then brightness uniformity is improved, but circuit complexity increases and aperture ratio decreases
Solution Approach 1:
The patent combines the compensation function with existing pixel components by using the storage capacitor for dual purposes: storing data voltage and compensating threshold voltage. The compensation transistor is integrated into the existing pixel circuit architecture, sharing components with the data writing function. This merging approach achieves threshold voltage compensation without significantly increasing circuit complexity or reducing aperture ratio.
Solution Approach 2:
The storage capacitor is designed to perform multiple functions: it stores the data voltage during the writing phase and simultaneously serves as a compensation capacitor for threshold voltage compensation. The compensation transistor acts as a switch during data writing and as a compensation element during the compensation phase. This multi-functionality reduces the need for additional dedicated compensation components.
2Illumination intensity
If conventional compensation circuits are added to compensate threshold voltage, then brightness uniformity is improved, but aperture ratio decreases
Solution Approach 1:
The patent merges the compensation function with existing pixel components, particularly utilizing the storage capacitor and compensation transistor that are already part of the pixel circuit. By making these existing components serve dual purposes (data storage and threshold compensation), the patent avoids adding separate dedicated compensation components that would occupy additional pixel area, thereby maintaining a high aperture ratio while achieving brightness uniformity.
3Illumination intensity
If conventional compensation circuits are added to compensate threshold voltage, then brightness uniformity is improved, but control signal complexity increases
Solution Approach 1:
The patent implements compensation through periodic scanning operations where the compensation transistor is sequentially activated for each pixel along a scan line. The controller applies compensation voltages in a systematic sequence, first to pixels on one scan line, then to the next scan line, and so on. This periodic scanning approach simplifies control signal generation compared to simultaneous compensation of all pixels, as the controller only needs to manage sequential voltage application through the existing scan and data line infrastructure.
Data Source
AI summary
An organic light-emitting diode (OLED) panel and driving method thereof is provided. The OLED panel includes a plurality of data lines, scan lines, pixels, sampling voltage lines and compensation voltage lines. The sampling voltage line transmits a compensation voltage in response to compensation signals from the data lines, threshold voltages of driving transistors and organic light emitting diodes in the pixels connected to the same scan line. The corresponding compensation voltage line adjusts data signals transmitted into the pixels connected to the same scan line in response to the compensation voltage.