OLED Pixel Circuit With Feedback Compensation for Brightness Aging
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Solution Overview
Problem
Conventional organic light emitting displays face issues with maintaining desired brightness due to the deterioration of organic light emitting diodes over time, leading to reduced light output.
Innovation Solution
Incorporating a compensating unit within the pixel circuit that includes a second transistor and a feedback capacitor to control the gate electrode voltage of the first transistor, allowing for increased current supply to the organic light emitting diode as it deteriorates, thereby compensating for the degradation and maintaining desired brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pixel circuit is used, then device complexity is low, but brightness maintenance capability deteriorates due to OLED deterioration
Solution Approach 1:
The patent implements a feedback mechanism by introducing a second transistor that senses the voltage at the gate electrode of the first transistor and adjusts the current supply accordingly. The feedback capacitor stores the sensed voltage information, creating a closed-loop system that automatically compensates for OLED deterioration by increasing current when voltage drop is detected, thereby maintaining brightness without requiring complex external control circuits.
2Illumination intensity
If current supply is increased to compensate for OLED deterioration, then brightness is maintained, but energy consumption increases
Solution Approach 1:
The patent employs a dynamic current adjustment mechanism where the current supply to the OLED is not fixed but adapts automatically based on real-time conditions. The second transistor dynamically modulates the current based on the feedback from the voltage sensing capacitor, increasing current only when and where OLED deterioration is detected, rather than maintaining high current continuously. This dynamic approach maintains brightness while minimizing unnecessary energy consumption during periods when the OLED is still performing within acceptable parameters.
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
Enables the display to maintain desired brightness levels despite organic light emitting diode deterioration by adjusting the current supply, ensuring consistent image quality.
Implementation Method 1
the OLED displays an image using an organic light emitting diode generating light by recombination of electrons and holes
Implementation Method 2
a feedback capacitor coupled between the second transistor and the organic light emitting diode
Data Source
AI summary
A pixel capable of compensating for deterioration of an organic light emitting diode includes an organic light emitting diode. A pixel circuit includes a first transistor controlling an amount of current supplied from a first power supply to the organic light emitting diode corresponding to a data signal. A compensating unit controls a voltage of a gate electrode of the first transistor to compensate for deterioration of the organic light emitting diode. The compensating unit includes a second transistor coupled between the gate electrode of the first transistor and the organic light emitting diode and turned off during a period of the supply of the data signal to the pixel circuit, and a feedback capacitor coupled between the second transistor and the organic light emitting diode.