Layered Pixel Driving Circuit for High-Resolution OLED Panels
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Solution Overview
Problem
High-resolution light emitting display panels face challenges in manufacturing due to the difficulty in forming pixel driving circuits, including internal compensation circuits, as the size of each pixel is reduced, leading to variations in current output from driving transistors caused by threshold voltage deviations.
Innovation Solution
The light emitting display panel is designed with transistors of the pixel driving circuit divided into multiple layers, with the driving transistor in the first layer and the capacitor for threshold voltage storage in the third layer, allowing for efficient current control and compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the light emitting display panel is increased, then the image quality is improved, but the size of each pixel is reduced making it difficult to form pixel driving circuits
Solution Approach 1:
The pixel driving circuit is divided into multiple independent transistor components (driving transistor, compensation transistor, switching transistor) that are separately formed in the pixel electrode structure. This segmentation allows each transistor to be independently manufactured and positioned, making it feasible to create complex driving circuits even in highly reduced pixel sizes for high-resolution displays
Solution Approach 2:
The patent utilizes the vertical dimension by forming transistors at different depth levels within the pixel electrode structure. Multiple transistors are stacked vertically with conductive connections extending through intermediate layers, effectively increasing the available circuit space without expanding the horizontal pixel footprint, thus enabling high-resolution displays
2Measurement precision
If the pixel size is reduced for high-resolution displays, then the resolution is improved, but the integration of internal compensation circuits becomes difficult
Solution Approach 1:
The compensation circuit transistors are nested within the pixel electrode structure, with the compensation transistor formed in the same pixel electrode as the driving transistor. This nesting approach allows the compensation circuit to be integrated into the same physical space as the driving circuit, reducing overall complexity while maintaining high-resolution pixel dimensions
Solution Approach 2:
The patent employs vertical stacking of transistor layers to integrate compensation circuits within the pixel depth dimension. By forming transistors at different vertical levels and connecting them through conductive paths, the compensation circuit is embedded within the pixel structure without requiring additional horizontal space, thus enabling high-resolution displays with integrated compensation
3Manufacturing precision
If process deviation occurs, then manufacturing variations increase, but threshold voltage deviation of driving transistors causes current output variation
Solution Approach 1:
The compensation transistor is configured to sense the threshold voltage of the driving transistor through electrical connection. By monitoring the voltage characteristics of the driving transistor, the compensation transistor generates compensating signals that counteract threshold voltage deviations, thereby maintaining uniform current output across pixels despite manufacturing process variations
Solution Approach 2:
The pixel driving circuit performs self-compensation by using the compensation transistor to automatically detect and correct threshold voltage variations in the driving transistor. This self-service mechanism eliminates the need for external calibration or adjustment, ensuring consistent current output and reliable image quality even when manufacturing process deviations occur
Data Source
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AI summary
A display device is provided. The display device includes a light emitting display panel. The display panel includes a plurality of pixels. Each of the pixels include a first, second, third, and fourth pixel circuit layers and a light emitting device layer. Each of the layers are sequentially mounted on each other from the first pixel circuit layer to the light emitting device layer. The first pixel circuit layer includes a first pixel circuit configuring a pixel driving circuit. The second pixel circuit layer includes a second pixel circuit configuring the pixel driving circuit. The third pixel circuit layer includes a third pixel circuit configuring the pixel driving circuit. The fourth pixel circuit layer includes a fourth pixel circuit configuring the pixel driving circuit. The light emitting device layer includes a light emitting device electrically connected to the fourth pixel circuit.