Pixel Driving Circuit Threshold Compensation Aperture Ratio
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Solution Overview
Problem
In AMOLED displays, non-uniformity in threshold voltages of driving transistors leads to inconsistent display brightness due to varying current densities, which reduces the lifespan of the organic light-emitting layer and affects image quality.
Innovation Solution
A pixel driving circuit with a reset unit that stores both data and threshold voltages during the charging phase, allowing the driving unit to operate independently of threshold voltage during the driving phase, thereby ensuring consistent current delivery to the OLED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a compensation unit is added to each pixel to eliminate threshold voltage influence, then display uniformity is improved, but aperture ratio decreases rapidly
Solution Approach 1:
The pixel circuit is divided into two functional regions: a first region containing the essential driving components (driving transistor, storage capacitor, OLED) and a second region containing the compensation circuitry. This spatial segmentation allows the compensation unit to be shared across multiple pixels, reducing the area occupied per pixel while maintaining compensation functionality for display uniformity.
Solution Approach 2:
The compensation unit is designed to serve multiple pixels simultaneously rather than being dedicated to a single pixel. By implementing a shared compensation architecture where one compensation unit can compensate for threshold voltage variations across multiple driving transistors, the patent reduces the overall transistor count per pixel while maintaining display uniformity.
2Area of stationary object
If aperture ratio is increased to maintain brightness, then current density of organic light emitting layer increases, but material aging accelerates and usage life decreases
Solution Approach 1:
The patent modifies the circuit operating parameters by implementing precise threshold voltage compensation, which enables the driving transistor to operate at optimized current levels. This parameter optimization allows the OLED to emit required brightness at lower current densities, reducing material stress and extending display panel lifespan without sacrificing aperture ratio.
3Manufacturing precision
If threshold voltage compensation is implemented, then display quality is improved, but device complexity increases due to additional transistors
Solution Approach 1:
The pixel circuit is divided into two functional regions: a first region containing the essential driving components (driving transistor, storage capacitor, OLED) and a second region containing the compensation circuitry. This spatial segmentation allows the compensation unit to be shared across multiple pixels, reducing the area occupied per pixel while maintaining compensation functionality for display uniformity.
Solution Approach 2:
The compensation unit is designed to serve multiple pixels simultaneously rather than being dedicated to a single pixel. By implementing a shared compensation architecture where one compensation unit can compensate for threshold voltage variations across multiple driving transistors, the patent reduces the overall transistor count per pixel while maintaining display uniformity.
Data Source
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AI summary
The present disclosure relates to a pixel driving circuit, a display apparatus and a pixel driving method. The pixel driving circuit comprises a reset unit. The reset unit is arranged to enable the storage capacitor to store not only a data voltage but also a threshold voltage of the driving unit in the charging phase, to compensate for the driving unit in the driving phase, so that the operating current of the driving unit is not influenced by the threshold voltage. This eliminates the influence of the threshold voltage of the driving unit to the operating current of the driving unit, thereby solving the technical problem of non-uniformity of display brightness of the light-emitting elements due to inconsistency of threshold voltages and improving the display quality of the display apparatus. Further, the reset unit is moved outside an active display area, and is shared by a row of pixel driving circuits, which can significantly increase the aperture rate of the pixels. In this way, the current density of the organic light-emitting layer is reduced, thereby extending the usage life of the display panel.