OLED Drive Circuit Compensation for Brightness Uniformity
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Solution Overview
Problem
OLED display panels face issues with poor brightness uniformity due to varying drive currents and power supply voltage differences across pixel units, leading to non-uniform light emission.
Innovation Solution
A display drive circuit comprising a pixel circuit and a compensation circuit, where the pixel circuit includes a drive transistor, a light emitting device, and a storage capacitor, along with a voltage generating and adjusting sub-circuit to regulate the drive current and ensure uniformity, and a gating sub-circuit for controlling connections based on scanning signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a drive transistor is used to generate drive current in OLED display panels, then the light emitting device can be driven to emit light, but the brightness uniformity deteriorates due to varying drive currents and power supply voltage differences across pixel units
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the gate voltage of the drive transistor through the compensation circuit before the light emitting device operates. The compensation circuit calculates the required voltage adjustment based on stored threshold voltage information and applies it in advance, ensuring that drive currents remain consistent across all pixel units despite manufacturing variations or voltage drops, thereby maintaining brightness uniformity.
Solution Approach 2:
The patent implements feedback by using the storage capacitor to retain threshold voltage information from previous operations and feeding this information back to the compensation circuit. The compensation circuit then uses this feedback to adjust the gate voltage appropriately, creating a closed-loop system that continuously maintains drive current consistency and brightness uniformity across the display panel.
2Reliability
If power supply voltage is increased to compensate for voltage drops, then drive current can be maintained, but brightness uniformity deteriorates due to IR drop variations across different pixel units
Solution Approach 1:
The patent applies local quality by implementing compensation at the individual pixel unit level rather than using a global voltage increase. Each pixel's compensation circuit adjusts its drive transistor's gate voltage based on its specific threshold voltage characteristics and local conditions, allowing precise local compensation that maintains drive current stability without causing brightness non-uniformity from IR drop variations across different pixel units.
3Device complexity
If threshold voltage drift of drive transistor is not compensated, then circuit complexity is reduced, but brightness uniformity deteriorates over time
Solution Approach 1:
The patent applies preliminary action by measuring and storing the threshold voltage of the drive transistor in advance during a testing phase or initial operation, then using this pre-acquired information to compensate for threshold voltage drift during normal operation. This preliminary measurement and storage approach enables long-term brightness uniformity maintenance without requiring complex real-time monitoring circuits.
Solution Approach 2:
The patent implements self-service by having each pixel unit's compensation circuit autonomously adjust its drive transistor's gate voltage based on stored threshold voltage information, without requiring external intervention or complex centralized control. This self-service mechanism maintains brightness uniformity over time while keeping the overall circuit design relatively simple.
Data Source
AI summary
A display drive circuit, a drive method thereof, and a display device are disclosed. The display drive circuit includes: a pixel circuit and a compensation circuit, the pixel circuit includes: a drive transistor, a light emitting device, a storage capacitor, and a gating sub-circuit configured to control connection and disconnection between the control electrode of the drive transistor and a control terminal of the compensation circuit and connection and disconnection between a second electrode of the light emitting device and a sensing terminal of the compensation circuit in response to a signal of a scanning line; the compensation circuit includes: a voltage generating sub-circuit configured to generate a sensing voltage according to the drive current and a target data voltage, and a voltage adjusting sub-circuit configured to adjust a voltage of the control terminal according to the sensing voltage and a voltage of a second power supply terminal.