OLED Pixel Compensation Circuit for Luminance Degradation
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Solution Overview
Problem
Conventional organic light emitting display devices face difficulties in maintaining desired luminance due to the deteriorating efficiency of organic light emitting diodes (OLEDs) over time.
Innovation Solution
A pixel circuit with a compensation unit, including a compensation transistor and capacitor, is used to control the voltage at the gate electrode of the drive transistor, compensating for the deterioration of OLEDs by adjusting the electric current supplied to maintain desired luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional organic light emitting display devices are used, then the device structure is simple, but the luminance deteriorates over time due to OLED efficiency degradation
Solution Approach 1:
The patent implements a feedback mechanism where the compensation transistor continuously monitors the voltage at the gate electrode of the drive transistor and adjusts the electric current supplied to the OLED accordingly. As the OLED efficiency degrades over time, the compensation transistor increases the current to compensate for the luminance loss, maintaining consistent display brightness throughout the operational lifetime of the display device.
Solution Approach 2:
The patent changes the electrical parameters (voltage and current) supplied to the OLED over time to compensate for degradation. The compensation unit dynamically adjusts the gate voltage of the drive transistor, which in turn modulates the current through the OLED. This parameter adjustment allows the system to maintain desired luminance characteristics even as the OLED material naturally degrades during extended operation.
2Illumination intensity
If a compensation unit is added to compensate for OLED deterioration, then the luminance consistency is improved, but the device complexity increases
Solution Approach 1:
The compensation transistor is integrated into the existing pixel circuit structure, sharing the gate electrode node with the drive transistor. This multi-functional design allows the same circuit node to serve both as the control input for the drive transistor and as the monitoring point for the compensation mechanism. The first capacitor also serves dual purposes: stabilizing the gate voltage and enabling the compensation function, thereby reducing the need for completely separate compensation circuitry.
Solution Approach 2:
The patent merges the compensation function with the existing drive circuit by combining the compensation transistor and first capacitor with the drive transistor's gate control structure. Rather than adding a completely separate compensation circuit, the invention integrates the compensation elements into the existing pixel circuit architecture, sharing common nodes and signals where possible to minimize overall circuit complexity.
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 OLED deterioration by increasing the electric current as the OLEDs degrade, ensuring consistent luminance and enabling the display of images with desired brightness.
Implementation Method 1
the organic light emitting display displays an image by using organic light emitting diodes which generate lights using the recombination of electrons and holes
Data Source
AI summary
A pixel of an organic light emitting display device and an organic light emitting display device using the same. The pixel is configured to compensate for the deterioration of organic light emitting diodes. The pixel includes an organic light emitting diode; a pixel circuit including a drive transistor for controlling an amount of electric current that flows from a first power source to a second power source via an organic light emitting diode; and a compensation unit between a gate electrode and a first electrode of the drive transistor for controlling a voltage of the gate electrode of the drive transistor to correspond to the deterioration of the organic light emitting diode. The compensation unit includes a transistor and a capacitor coupled in series between the gate electrode and the first electrode of the drive transistor.