Pixel Node Initialization Circuit for Stable OLED Luminance
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Solution Overview
Problem
Display devices face challenges in maintaining uniform luminance across pixels due to variations in data signals from previous frames, leading to non-uniform image display.
Innovation Solution
A pixel structure incorporating transistors and a storage capacitor, along with specific initialization power sources and scan signals, ensures uniform luminance by initializing nodes to a consistent voltage level regardless of previous frame data, using a four-transistor configuration and a storage capacitor to stabilize node voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional pixel structure is used, then the device complexity is low, but the luminance uniformity deteriorates due to variations from previous frame data signals
Solution Approach 1:
The patent applies preliminary action by initializing the first and second nodes to a reference voltage level before the display period begins. The initialization transistor is turned on during an initialization period to set both nodes to a known reference voltage, eliminating residual charges from previous frames. This preliminary initialization ensures that subsequent luminance display is uniform and not influenced by previous frame data, directly resolving the luminance uniformity issue while maintaining a relatively simple pixel structure.
2Stability of the object's composition
If initialization voltage is applied to both nodes, then the luminance uniformity is improved, but the power consumption increases
Solution Approach 1:
The patent applies local quality by differentiating the voltage levels applied to different nodes based on their specific functions. The first node (gate electrode of driving transistor) receives a first initialization voltage to ensure proper transistor switching, while the second node (anode of light emitting element) receives a second initialization voltage optimized for light emission control. This localized voltage optimization allows each node to be initialized with the minimum necessary voltage, reducing overall power consumption while maintaining voltage stability and luminance uniformity.
Data Source
AI summary
A pixel includes a first transistor having a first electrode connected to a first power line, a gate electrode connected to a first node, and a second electrode connected to a second node; a light emitting element connected between the second node and a second power line; a second transistor connected between a data line and the first node and having a gate electrode connected to a first scan line; a third transistor connected between the second node and a lead-out line and having a gate electrode connected to a second scan line; and a fourth transistor having a first electrode connected to the first node or the second node, a second electrode connected to the lead-out line or a third power line, and a gate electrode connected to a third scan line.