OLED Pixel Compensation Circuit for Luminance Degradation
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Solution Overview
Problem
Organic light emitting displays face challenges in maintaining desired luminance due to the degradation of organic light emitting diodes over time, leading to reduced light output.
Innovation Solution
A pixel design incorporating a compensation unit with feedback capacitors and transistors to control the voltage of the gate electrode of the second transistor, compensating for the degradation of the organic light emitting diode by adjusting the electric current and voltage to maintain consistent luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If organic light emitting diodes are used in displays, then rapid response time and low power consumption are achieved, but luminance degradation occurs over time
Solution Approach 1:
The patent implements a feedback mechanism using a feedback capacitor connected between the gate electrode of the drive transistor and the anode of the OLED. This capacitor senses the voltage changes caused by OLED degradation and automatically adjusts the gate voltage to compensate for the luminance loss, maintaining stable light output over time.
Solution Approach 2:
The patent changes the electrical parameters (gate voltage) of the drive transistor dynamically to compensate for OLED degradation. By adjusting the gate voltage based on the degradation state, the system maintains constant current flow through the OLED, thereby preserving luminance despite the organic material's natural degradation.
2Device complexity
If conventional pixel circuits are used, then simple circuit structure is maintained, but luminance cannot be maintained due to OLED degradation
Solution Approach 1:
The feedback capacitor is added to the conventional pixel circuit to create a self-regulating system. This single additional component enables the circuit to automatically compensate for OLED degradation without requiring complex external control mechanisms, maintaining luminance while adding minimal circuit complexity.
Solution Approach 2:
The feedback mechanism allows the pixel circuit to self-adjust and self-compensate for OLED degradation. The circuit monitors its own performance through the feedback capacitor and automatically corrects any luminance loss, eliminating the need for external intervention or complex control systems.
3Device complexity
If no compensation mechanism is used, then device complexity is minimized, but display lifespan is reduced due to visible luminance degradation
Solution Approach 1:
The feedback capacitor provides continuous monitoring and automatic adjustment throughout the OLED's operational life. This ongoing feedback mechanism ensures that luminance degradation is constantly compensated, extending the display's effective lifespan by maintaining acceptable image quality over time.
Solution Approach 2:
The feedback capacitor is pre-configured in the circuit to automatically detect and respond to OLED degradation before it becomes visually apparent. This preliminary action of continuous voltage adjustment prevents noticeable luminance loss, effectively extending the display's usable lifespan.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively compensates for the degradation of organic light emitting diodes, ensuring that the display maintains desired luminance levels by adjusting the electric current and voltage, thereby extending the lifespan of the display.
Implementation Method 1
an organic light emitting diode which generates light by utilizing the recombination of electrons and holes
Implementation Method 2
a compensation unit for controlling a voltage of a gate electrode of the second transistor to correspond to a degradation of the organic light emitting diode
Data Source
AI summary
A pixel capable for compensating for the degradation of an organic light emitting diode. The pixel includes an organic light emitting diode; a pixel circuit including a driving transistor for controlling an electric current capacity flowing from a first power source to a second power source via the organic light emitting diode; and a compensation unit for controlling a voltage of a gate electrode of the driving transistor to correspond to a degradation of the organic light emitting diode. The compensation unit includes first and second feedback capacitors coupled in series between an anode electrode of the organic light emitting diode and the gate electrode of the driving transistor and a switching transistor coupled between a common node of the first and second feedback capacitors and a reset power source and for turning on when a control signal is supplied to a control line coupled to the switching electrode.