OLED Pixel Compensation Circuit for Brightness Uniformity
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Solution Overview
Problem
Existing OLED displays suffer from non-uniform brightness due to variations in carrier mobility and aging of driving transistors and light emitting components, leading to inconsistent display quality over time and across different regions.
Innovation Solution
The implementation of a pixel compensation circuit with a current source signal terminal and acquisition capacitor to provide constant or variable current signals to driving transistors, decoupling light emitting current from threshold voltage and carrier mobility, ensuring consistent brightness across the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pixel circuits only compensate threshold voltages of driving transistors, then the circuit design is simple, but display uniformity deteriorates due to carrier mobility variations and aging effects
Solution Approach 1:
The patent applies preliminary action by measuring and storing the carrier mobility of driving transistors before the display operates. The pixel compensation circuit includes a mobility compensation module that measures carrier mobility in advance and stores it in a storage unit, then uses this stored mobility data to compensate for current variations during operation. This preliminary measurement and storage approach allows the system to maintain display uniformity without adding complex real-time compensation mechanisms.
2Device complexity
If no consideration is given to carrier mobility and aging, then the device structure remains simple, but light emitting current decreases over time due to forward voltage drop increase
Solution Approach 1:
The patent implements feedback by measuring the forward voltage drop of light emitting components and using this information to adjust the driving current. The pixel compensation circuit includes a feedback module that continuously monitors the forward voltage drop and adjusts the current signal provided to the light emitting component, ensuring stable light emission over time despite aging effects.
Solution Approach 2:
The patent applies preliminary action by measuring and storing the forward voltage drop characteristics of light emitting components before operation. The compensation circuit uses pre-measured mobility and forward voltage data to calculate appropriate compensation currents, eliminating the need for complex real-time adjustment mechanisms while maintaining performance over the device's service life.
3Adaptability or versatility
If different light emitting components and driving transistors are used, then manufacturing flexibility increases, but display brightness uniformity deteriorates due to varying aging degrees and carrier mobility
Solution Approach 1:
The patent applies local quality by implementing individualized compensation for each pixel's driving transistor and light emitting component. The pixel compensation circuit measures and stores specific carrier mobility values and forward voltage drop characteristics for each component, then applies tailored compensation currents to each pixel. This localized compensation approach maintains brightness uniformity across the display even when different components with varying characteristics are used throughout manufacturing.
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
This solution ensures display brightness uniformity in both time and space dimensions by compensating for variations in threshold voltage, carrier mobility, and aging of light emitting diodes, resulting in improved display coherence and longevity.
Implementation Method 1
a light emitting diode and a driving transistor, the light emitting diode being arranged in each of the pixel regions
Data Source
AI summary
The present application discloses an organic light emitting display panel, a driving method thereof and an organic light emitting display apparatus. The organic light emitting display panel comprises: a pixel array, comprising pixel regions in M rows and N columns; a plurality of pixel driving circuits each comprising a light emitting diode and a driving transistor for driving the light emitting diode, the light emitting diode being arranged in one of the pixel regions; and a plurality of pixel compensation circuits, each configured to provide a compensated light emitting control signal for a gate of the driving transistor to correct brightness of the light emitting diode in one of the plurality of pixel driving circuits. According to the present disclosure, the final light emitting current may be unrelated to the threshold voltage of the driving transistor, the carrier mobility and aging of the light emitting diode.