OLED Pixel Circuit for Simultaneous Emission and Luminance Uniformity
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Solution Overview
Problem
Organic light emitting displays face performance issues due to manufacturing process variations causing luminance deviations and complexity in achieving high-resolution displays with simultaneous emission methods.
Innovation Solution
A display device with a panel driver that provides scan and data signals to pixels, utilizing a specific voltage level management system for transistors and capacitors to enable simultaneous emission, compensating for threshold voltage differences and improving display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pixels have a relatively complicated structure for compensating threshold voltages or for simultaneous emission, then display quality and luminance uniformity are improved, but it becomes difficult to manufacture displays with high resolution
Solution Approach 1:
The patent applies parameter changes by utilizing different voltage levels (first, second, and third voltage levels) to control transistor operations during different periods (initialization, threshold voltage compensation, data writing, and emission periods). This allows the pixel circuit to achieve threshold voltage compensation and simultaneous emission functionality without increasing structural complexity, thereby maintaining manufacturability at high resolutions.
2Reliability
If pixels have a relatively complicated structure for compensating threshold voltages or for simultaneous emission, then display quality is improved, but device complexity increases
Solution Approach 1:
The first transistor serves multiple functions: it acts as a driving transistor during the emission period, as a diode connection for threshold voltage compensation during the threshold voltage compensation period, and its gate electrode is initialized during initialization periods. This multi-functionality reduces the need for additional dedicated transistors, thereby maintaining display quality while reducing device complexity.
Solution Approach 2:
The patent implements dynamic operation by controlling transistors and capacitors to operate in different states during different periods (initialization, threshold voltage compensation, data writing, and emission periods). The voltage levels of power sources are dynamically changed to achieve different functions, allowing a single pixel structure to adapt to multiple operational requirements without increasing complexity.
3Reliability
If pixels are driven in simultaneous emission manner, then motion blur is prevented and display quality is improved, but manufacturing becomes more difficult due to complex pixel structures
Solution Approach 1:
The patent applies preliminary action by performing initialization of the first electrode of the organic light emitting diode during the first initialization period before the emission period. This preliminary initialization ensures that the OLED is properly prepared for simultaneous emission, enabling motion blur prevention while maintaining a manufacturable pixel structure through proper timing control rather than structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for high-resolution displays with improved quality by driving pixels in a simultaneous emission manner, reducing luminance deviations and motion blur, and simplifying the manufacturing process.
Implementation Method 1
Light is emitted when holes from the anode combine with electrons from the cathode in the organic layer
Data Source
AI summary
A pixel includes first, second, and third transistors, first and second capacitors, and an organic light emitting diode. The first transistor has a gate electrode connected to a first node, a first electrode that receives a first power voltage, and a second electrode connected to a second node. The second transistor has a gate electrode that receives a scan signal, a first electrode connected to the first node, and a second electrode connected to a third node. The third transistor has a gate electrode that receives a common control signal, a first electrode connected to the third node, and a second electrode connected to the second node. The organic light emitting diode has a first electrode connected to the second node and a second electrode that receives a second power voltage.