OLED Pixel Driving Circuit Threshold Voltage Stabilization
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Solution Overview
Problem
The threshold voltage variation of driving transistors in OLED display panels affects the luminance uniformity of AMOLED panels, leading to non-uniform light emission and poor display effects.
Innovation Solution
An OLED pixel driving circuit with a reset module, capacitor, transistors, and light-emitting control module is designed to control the threshold voltage difference between the driving transistor and a first transistor, ensuring the luminance variation is within a preset range by charging the capacitor to a specific voltage, thereby stabilizing the luminance of OLED pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the driving transistor is used to control OLED luminance, then the response speed and contrast are improved, but the luminance uniformity deteriorates due to threshold voltage variation
Solution Approach 1:
The patent applies preliminary action by charging the first capacitor to a specific voltage before the light-emitting phase through the reset module and charging control module. This pre-charging operation ensures that the gate voltage of the driving transistor is properly established before luminance control begins, compensating for threshold voltage variations in advance and maintaining luminance uniformity throughout the display frame.
2Device complexity
If the threshold voltage of the driving transistor is allowed to vary, then the device complexity is reduced, but the luminance stability deteriorates
Solution Approach 1:
The patent introduces an intermediary element - the first capacitor - that mediates between the data line and the driving transistor gate. The capacitor stores and stabilizes the gate voltage, isolating the driving transistor from threshold voltage variations. This intermediary component maintains luminance stability without significantly increasing overall circuit complexity, as it integrates smoothly with the existing pixel structure.
3Stability of the object's composition
If the first capacitor is charged to a specific voltage, then the luminance variation is controlled, but the use of energy increases due to the charging operation
Solution Approach 1:
The patent implements periodic action by charging the first capacitor only during the reset phase before each frame, rather than continuously. The charging control module activates the first transistor periodically to charge the capacitor to the required voltage, then maintains this charge throughout the light-emitting phase. This periodic charging approach controls luminance variation while minimizing energy consumption compared to continuous charging operations.
Data Source
AI summary
An OLED pixel driving circuit, a driving method, and an OLED display apparatus are provided. The OLED pixel driving circuit comprises a reset module (1), a first capacitor (C1), a first transistor (T1), a charging control module (2), a driving transistor (M1) and a light-emitting control module (3); the reset module (1) is connected to two terminals of the first capacitor (C1) and configured to make the two terminals of the first capacitor (C1) have an initial voltage; a first electrode of the first transistor (T1) is connected to the charging control module (2), a second electrode thereof is connected to a first terminal of the first capacitor (C1), and a control electrode thereof is connected to a second terminal of the first capacitor (C1); the charging control module (2) is connected to the first transistor (T1) and a data line (Data); a control electrode of the driving transistor (M1) is connected to the second terminal of the first capacitor (C1), a first electrode thereof is connected to a high voltage terminal (VDD), and a second electrode thereof is connected to the light-emitting control module (3); and the light-emitting control module (3) is connected to the light-emitting device (4), wherein a difference value between a threshold voltage of the first transistor (T1) and a threshold voltage of the driving transistor (M1) is smaller than a preset value. The OLED pixel driving circuit can make the luminance of the OLED pixel within one frame picture maintain stable.