OLED Pixel Circuit With Self-Compensated Driving Current
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Solution Overview
Problem
Current pixel circuits for OLED displays lack a current-type design capable of threshold voltage self-compensation.
Innovation Solution
A pixel circuit with a driving circuit, energy storage circuits, and control circuits that allow for threshold voltage self-compensation by controlling the connection and disconnection of power and voltage terminals in specific phases, using capacitors and transistors to manage the driving current independently of the threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel circuit design is used for OLED display, then the circuit structure is simple, but threshold voltage compensation is not achieved leading to display non-uniformity
Solution Approach 1:
The pixel circuit is divided into multiple functional modules: driving circuit, first energy storage circuit, second energy storage circuit, writing-in control circuit, and first control circuit. Each module performs a specific function in the threshold voltage compensation process, allowing complex compensation operations to be achieved through modular design.
Solution Approach 2:
The circuit performs preliminary actions by storing reference voltages in the energy storage circuits during initialization phase, and by pre-configuring the control circuits to enable threshold voltage compensation before the actual display operation begins, ensuring uniformity from the start.
2Reliability
If threshold voltage self-compensation is implemented, then display uniformity is improved, but the circuit complexity increases
Solution Approach 1:
The pixel circuit achieves self-service through automatic threshold voltage compensation. The first control circuit automatically controls the connection between the power supply voltage terminal and the driving circuit based on control signals, and the writing-in control circuit automatically writes reference voltages into the energy storage circuits, eliminating the need for external manual intervention and reducing the burden on external control systems.
Solution Approach 2:
The energy storage circuits store reference voltages that create equipotential conditions for compensation. By maintaining consistent voltage levels across different pixels through the stored reference voltages, the circuit achieves uniform compensation效果 across the entire display panel.
3Manufacturing precision
If multiple control circuits and energy storage circuits are added for current control, then driving current consistency is improved, but the manufacturing complexity increases
Solution Approach 1:
The control circuits and energy storage circuits are designed with multi-functionality. The first control circuit not only controls the power supply connection but also participates in the threshold voltage compensation process. The energy storage circuits store both reference voltages and compensation voltages, reducing the need for separate dedicated circuits and simplifying manufacturing.
Data Source
AI summary
A pixel circuit includes a light emitting element, a driving circuit, a first energy storage circuit, a second energy storage circuit, and a writing-in-in control circuit and a first control circuit; a first terminal of the first energy storage circuit is electrically connected to a control terminal of the driving circuit, and a second terminal of the first energy storage circuit is electrically connected to a first terminal of the driving circuit; a first terminal of the second energy storage circuit is electrically connected to a control terminal of the driving circuit; the writing-in control circuit is configured to control to connect or disconnect the writing-in terminal and the second terminal of the second energy storage circuit under the control of the first writing-in control signal provided by the first writing-in control terminal.