OLED Pixel Circuit Threshold Voltage Compensation
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Solution Overview
Problem
The manufacturing process of OLED display panels faces challenges in ensuring uniformity of threshold voltages across driving thin film transistors, leading to non-uniform brightness of pixels due to drifting threshold voltages, which affects display uniformity and effectiveness.
Innovation Solution
A pixel circuit is designed with a compensation current signal from a constant current source that compensates the threshold voltage of the light emitting drive transistor, ensuring the light emitting current is not affected by the transistor's threshold voltage, thereby improving display uniformity and brightness consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional AMOLED display panel manufacturing is used, then production simplicity is maintained, but threshold voltage uniformity deteriorates leading to non-uniform pixel brightness
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage compensation before the light emitting phase. The compensation circuit writes compensation voltage information into the light emitting drive transistor during the data writing stage, preemptively correcting threshold voltage deviations before they affect pixel brightness. This ensures uniform threshold voltages across all pixels without requiring complex real-time adjustment mechanisms during light emission.
Solution Approach 2:
The patent introduces a compensation circuit as an intermediary component between the data writing circuit and the light emitting drive transistor. This compensation circuit includes compensation transistors and capacitors that act as mediators to transfer and store compensation voltage information, enabling threshold voltage correction without directly modifying the light emitting drive transistor structure or requiring complex external adjustment equipment.
2Illumination intensity
If threshold voltage compensation is implemented, then pixel brightness uniformity is improved, but circuit structure complexity increases
Solution Approach 1:
The patent merges the compensation function with the existing data writing circuitry by using the same scanning signal line to control both data writing and compensation operations. The compensation circuit shares transistors and capacitors with the data writing circuit, combining multiple functions into a unified structure that achieves brightness uniformity without proportionally increasing device complexity.
Solution Approach 2:
The patent changes the operational parameters of existing circuit components to enable compensation functionality. By adjusting the timing and control signals of existing transistors and capacitors, the circuit transitions from simple data storage to active threshold voltage compensation, improving brightness uniformity without adding significant structural complexity.
3Manufacturing precision
If compensation circuit is added to correct threshold voltage drift, then display uniformity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent uses capacitor-based storage to copy and retain compensation voltage information throughout the display operation cycle. The storage capacitor captures the compensation voltage written during the data writing stage and maintains it during the light emitting stage, effectively copying the correction state without requiring continuous active compensation or complex real-time control mechanisms.
Data Source
AI summary
A pixel circuit, a method of driving a pixel circuit, a display panel and a display device. The pixel circuit includes a light emitting drive circuit, a storage circuit, a data writing circuit, a light emitting control circuit, and a compensation circuit. The data writing circuit is configured to write a data signal into the storage circuit under a control of a scanning signal; the storage circuit is configured to store the data signal; the compensation circuit is configured to write compensation voltage information which is based on a compensation current signal into the light emitting drive circuit under a control of the scanning signal; and the light emitting control circuit is configured to control the light emitting drive circuit to drive a light emitting element to emit light under a control of a light emitting control signal.