OLED Pixel Drive Circuit Gamma Biasing to Reduce Horizontal Stripes
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Solution Overview
Problem
OLED display panels experience horizontal stripes during dynamic picture display due to deviations in drive transistor characteristics, leading to poor display quality and user experience.
Innovation Solution
A driving method that applies a data voltage based on a reference gamma curve with a higher lowest voltage than the standard gamma curve and a preset voltage equal to or less than the reference gamma curve's lowest voltage to the drive transistor's second electrode, reducing the difference in sensed values and minimizing horizontal stripes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard gamma curve is used for driving the OLED display panel, then the drive voltage can be kept low, but horizontal stripes appear during dynamic picture display due to deviations in drive transistor characteristics
Solution Approach 1:
The patent modifies the gamma curve parameters by raising the lowest voltage level from the standard gamma curve to create a reference gamma curve. This parameter change ensures that the voltage applied to the drive transistor remains above the threshold voltage, preventing the transistor from entering the subthreshold region where characteristic deviations cause horizontal stripes. The modified voltage parameters eliminate the harmful effect while maintaining display quality.
2Reliability
If the lowest voltage of the gamma curve is raised to prevent horizontal stripes, then display quality improves, but the voltage range required increases
Solution Approach 1:
The patent optimizes the voltage parameters of the reference gamma curve by setting the lowest voltage to be greater than or equal to the threshold voltage of the drive transistor. This parameter optimization raises the floor voltage to prevent horizontal stripes while controlling the overall voltage range. The patent specifies that the preset voltage applied to the second electrode should be less than or equal to the lowest voltage of the reference gamma curve, thereby minimizing the required voltage swing and energy consumption while achieving the display quality improvement.
3Measurement precision
If a preset voltage is applied to the second electrode of the drive transistor, then the difference in sensed values is reduced, but the circuit complexity increases
Solution Approach 1:
The patent applies a preset voltage to the second electrode of the drive transistor before the data voltage is applied to the third electrode. This preliminary action pre-biases the transistor to operate in the saturation region, ensuring that subsequent sensing operations occur under optimal conditions where characteristic deviations are minimized. By performing this preparatory voltage application, the patent improves sensed value consistency without requiring complex real-time compensation circuits.
Data Source
AI summary
A driving method and an apparatus, and a storage medium are provided. The driving method is applied to a pixel drive circuit, the pixel drive circuit including a drive transistor, the drive transistor including a second electrode and a third electrode; and the method includes: applying a data voltage acquired based on a reference gamma curve to the third electrode of the drive transistor, and applying a preset voltage to the second electrode of the drive transistor; a lowest voltage of the reference gamma curve is greater than a lowest voltage of a standard gamma curve, and the preset voltage is less than or equal to the lowest voltage of the reference gamma curve.