OLED Pixel Driving Circuit Threshold Voltage Compensation
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Solution Overview
Problem
The inconsistency in threshold voltage of driving transistors used in organic light-emitting display panels due to manufacturing limitations leads to unstable driving current and poor uniformity in display luminance, affecting the performance of organic light-emitting display devices.
Innovation Solution
An organic light-emitting pixel driving circuit is designed with a specific configuration of transistors and capacitors that initializes and controls the driving transistor, detects its threshold voltage, and maintains charge levels, ensuring a stable and uniform driving current by decoupling the driving current from the threshold voltage and power supply voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If driving transistors are manufactured using low-temperature polycrystalline silicon technology, then the manufacturing process is simpler and easier to implement, but the threshold voltage uniformity deteriorates and drift occurs
Solution Approach 1:
The patent applies preliminary action by initializing the driving transistor threshold voltage before normal operation through a dedicated initialization phase. The circuit performs threshold voltage detection and compensation in advance, storing correction values in capacitors to preemptively counteract the uniformity issues caused by low-temperature polycrystalline silicon manufacturing variations.
Solution Approach 2:
The patent implements feedback mechanisms where the circuit continuously monitors the driving transistor threshold voltage through detection phases, compares it against reference values, and adjusts the driving current accordingly. This closed-loop feedback compensates for threshold voltage drift and non-uniformity in real-time, maintaining display quality despite manufacturing variations.
2Stability of the object's composition
If the same gray-scale voltage is input to different driving transistors, then the control signal consistency is maintained, but the driving current becomes inconsistent due to threshold voltage variations
Solution Approach 1:
The patent applies local quality by providing customized compensation for each driving transistor individually. Instead of using a uniform approach for all transistors, the circuit performs pixel-level threshold voltage detection and applies specific compensation values to each transistor based on its unique characteristics, thereby maintaining driving current stability despite variations in threshold voltage.
Solution Approach 2:
The patent changes the operating parameters of each driving transistor dynamically based on its measured threshold voltage. The circuit adjusts the gate-source voltage and driving current parameters individually for each transistor, transforming the fixed gray-scale voltage input into adaptive, transistor-specific driving conditions that compensate for threshold voltage variations.
3Device complexity
If the driving current is directly controlled by the driving transistor without compensation, then the circuit structure remains simple, but the display luminance uniformity deteriorates
Solution Approach 1:
The patent merges multiple functions into the pixel circuit structure, combining the driving transistor, compensation capacitors, initialization circuits, and detection mechanisms into an integrated pixel-level system. This consolidation achieves luminance uniformity compensation without requiring separate external compensation circuits, thereby limiting the increase in overall device complexity while improving display quality.
Data Source
AI summary
The present disclosure discloses an organic light-emitting pixel driving circuit, driving method and an organic light-emitting display panel. A driving transistor is to generate a driving current, a light-emitting element is to emit light; a first transistor is to transmit a first initialization voltage to the light-emitting element; a second transistor is to transmit a second initialization voltage to the driving transistor; a third transistor is to transmit a data signal voltage to the pixel driving circuit; a fourth transistor is to transmit a reference voltage to the driving circuit; a first capacitor is coupled in series between the output terminal of the third transistor and the driving transistor; a fifth transistor is to control the first capacitor; a sixth transistor is to control light emission of the light-emitting element; a second capacitor is to maintain the charge amount between the gate and source of the driving transistor.