Pixel Driving Circuit Layout for Higher-Density OLED Displays
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Solution Overview
Problem
Existing display technologies face challenges in reducing the area of the pixel driving circuit, leading to increased physical size and reduced pixel density, which affects display quality and power consumption.
Innovation Solution
A pixel structure with a 6T2C configuration, utilizing six transistors and two capacitors, reduces the number of signal lines and transistors, allowing for a smaller pixel driving circuit area and improved pixel density, while maintaining high-resolution capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of transistors and signal lines in the pixel driving circuit is reduced, then the pixel driving circuit area is reduced and pixel density is increased, but the complexity of circuit design and signal control increases
Solution Approach 1:
The patent merges multiple functions into fewer transistors. Specifically, the first transistor serves both as a driving transistor for the light emitting element and as a storage element through its gate electrode (first node) that holds voltage information. The second and third transistors are configured to share control signals and perform both switching and data writing functions, reducing the total transistor count while maintaining necessary circuit functions.
Solution Approach 2:
Each transistor in the circuit is designed to perform multiple functions. The first transistor acts as both a driving transistor and a memory element. The second transistor serves as both a switching element and a data writing element. The third transistor functions as both a switching element and a compensation element. This multi-functionality reduces the overall circuit complexity despite the reduced transistor count.
2Area of stationary object
If the pixel driving circuit area is reduced, then pixel density is increased, but signal interference between adjacent pixels may increase
Solution Approach 1:
The patent segments the control signals into distinct time periods (first period through fifth period) and uses separate scan signals (first scan signal, second scan signal) and emission control signals (first emission control signal, second emission control signal) to control different transistors. This temporal and signal segmentation reduces simultaneous signal transitions, thereby minimizing crosstalk and interference between adjacent pixels despite reduced spacing.
Solution Approach 2:
The circuit performs preliminary actions in each time period before the next operation. For example, during the first period, initialization voltages are applied to all nodes before data writing. During the second period, compensation voltages are applied before data signals are written. This sequential preliminary action ensures that each pixel is properly prepared and isolated before receiving new signals, preventing interference from adjacent pixels.
3Ease of manufacture
If the number of transistors is reduced from conventional designs, then manufacturing process complexity is reduced, but ensuring reliable voltage storage and signal control becomes more difficult
Solution Approach 1:
The first transistor's gate electrode (first node) serves as a self-contained voltage storage element. The transistor itself provides the storage function through its gate structure, eliminating the need for separate dedicated storage capacitors or additional transistors. This self-service approach maintains voltage storage reliability while reducing the total component count and manufacturing complexity.
Solution Approach 2:
The patent uses different voltage levels (first power source voltage, second power source voltage, initialization voltage) applied at different time periods to maintain reliable operation. By carefully controlling voltage parameters and timing, the circuit ensures that each transistor operates in its appropriate region regardless of the reduced transistor count, maintaining reliability through parameter optimization rather than increased component redundancy.
Data Source
AI summary
Disclosed is a pixel including a first transistor including a gate electrode connected to a first node, a first electrode electrically connected to a first power source line, and a second electrode connected to a second node, a second transistor including a gate electrode to which a first scan signal is provided, a first electrode electrically connected to a data line to which a data signal is provided, and a second electrode, a third transistor including a gate electrode, a first electrode connected to a third node, and a second electrode, a first capacitor, and a light emitting element.