Pixel Circuit Driving Method for OLED Luminance Uniformity
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Solution Overview
Problem
The driving process of OLED display panels has a poor compensation effect for display nonuniformity caused by structural nonuniformity in pixel circuits, leading to inadequate compensation and resulting in poor luminance uniformity across the panel.
Innovation Solution
A driving method for a pixel circuit that includes a data writing circuit, a sensing circuit, and a storage capacitor, where specific voltage control stages are implemented to write test and reference voltages, allowing for external and internal compensation to adjust the data voltage based on electron mobility and RC delay differences, ensuring uniform charging times across the panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional driving process is used, then device complexity is reduced, but compensation effect deteriorates
Solution Approach 1:
The driving process is segmented into multiple distinct stages: sensing write stage, sensing sampling stage, sensing reset stage, and sensing charging stage. Each stage performs a specific function in the compensation process, allowing complex compensation to be achieved through systematic division of operations rather than a single complex operation.
Solution Approach 2:
The patent performs preliminary actions by writing test voltage and reference voltage to the pixel circuit before the actual display operation. The sensing write stage prepares the pixel circuit with appropriate voltages in advance, enabling accurate compensation measurements and adjustments to be made during subsequent stages without affecting normal display operation.
2Manufacturing precision
If external compensation is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The pixel circuit performs self-compensation by utilizing its own internal components (driving transistor, sensing circuit, storage capacitor) to measure and adjust its performance characteristics. The sensing circuit measures the actual current output of the driving transistor, and the compensation is performed within the pixel circuit itself rather than requiring external complex compensation circuits.
Solution Approach 2:
The patent implements feedback by measuring the actual current output of the driving transistor through the sensing circuit and using this measurement to adjust the gate voltage. The sensing circuit provides feedback information about the transistor's performance, enabling real-time compensation adjustments to achieve uniform display across the panel.
3Measurement precision
If multiple sensing stages are implemented, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The sensing operations are designed to be continuous and efficient. The sensing write stage, sampling stage, reset stage, and charging stage occur in sequential continuity without idle periods. The storage capacitor maintains voltage levels between operations, and the sensing circuit continuously monitors the pixel circuit state, minimizing unnecessary time losses while maintaining high measurement precision.
Data Source
AI summary
There is provided a driving method for a pixel circuit including a driving transistor, a data writing circuit, a sensing circuit, and a storage capacitor. The driving method includes: during a sensing write stage, writing a test voltage equal to a sum of a first reference voltage and a threshold voltage of the driving transistor, by the data writing circuit, to the control electrode of the driving transistor, and writing a second reference voltage, by the sensing circuit, to a second electrode of the driving transistor; during a sensing sampling stage, continuing to write the test voltage to the control electrode of the driving transistor by the data writing circuit, and stopping writing a voltage to the second electrode of the driving transistor by the sensing circuit. The driving method further includes a sensing reset stage and a sensing charging stage.