OLED Pixel Circuit Reset and Compensation for Afterimage Elimination
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Solution Overview
Problem
In OLED display technology, the uneven threshold voltage shift of driving transistors leads to image unevenness, and the hysteresis effect causes short-term afterimages when switching from black and white to gray scale, which are not effectively improved in existing technologies.
Innovation Solution
A pixel circuit with a driving circuit, energy storage circuit, initialization circuit, light emitting control circuit, compensation control circuit, and written-in control circuit, along with a reset circuit, which includes transistors and capacitors, is designed to manage voltage connections and compensations to ensure consistent initialization and threshold voltage compensation, reducing afterimages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If threshold voltage compensation is implemented in the pixel circuit, then image unevenness is reduced, but the short-term afterimage problem caused by hysteresis effect cannot be effectively improved
Solution Approach 1:
The patent applies preliminary action by introducing a reset circuit that performs preliminary resetting of the light emitting element before normal operation. The reset transistor is turned on during a reset period to write initialization voltage into the first electrode of the light emitting element, clearing residual charges that would cause afterimages. This preliminary reset action prevents the hysteresis effect from causing short-term afterimages when switching between black and white pictures, while the threshold voltage compensation circuit simultaneously addresses image unevenness.
2Reliability
If a reset circuit is added to clear residual charges, then short-term afterimages are reduced, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the reset transistor to serve multiple functions within the pixel circuit. The same reset transistor and initialization voltage line are used both for clearing residual charges to eliminate afterimages and for providing initialization voltage to the driving circuit. This multi-functional design achieves afterimage elimination without proportionally increasing circuit complexity, as the reset circuit shares components with the existing initialization functionality.
Data Source
AI summary
A pixel circuit, a pixel driving method and a display device are provided. The pixel circuit includes a light emitting element, a driving circuit, an energy storage circuit, an initialization circuit, a compensation control circuit, a light emitting control circuit and a written-in control circuit. The initialization circuit writes an initialization voltage into a control end of the driving circuit under the control of a first gate driving signal so as to conduct the connection between a first end of the driving circuit and a second end of the driving circuit; the compensation control circuit is configured to conduct the connection between the control end of the driving circuit and the second end of the driving circuit under the control of the second gate driving signal.