AMOLED Pixel Circuit Flicker Reduction via Dual Initialization
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Solution Overview
Problem
Active Matrix Organic Light Emitting Diode (AMOLED) display panels experience significant flicker and poor image display effects due to brightness fluctuations during idle modes, primarily caused by leakage currents and potential variations at intermediate nodes in the pixel circuit.
Innovation Solution
The array substrate incorporates a specific drive time sequence and initialization module configuration, where the end time of the active level pulse of the first additional scan signal is later than that of the first scan signal, reducing the potential difference and leakage currents at intermediate nodes, thereby stabilizing the drive current and minimizing flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel circuit is used to drive the light emitting module, then the drive current can be controlled, but significant flicker phenomenon and poor image display effect occur during idle mode due to leakage currents and potential variations at intermediate nodes
Solution Approach 1:
The initialization module is divided into two separate transistors (first initialization transistor and second initialization transistor) instead of using a single transistor. This segmentation allows independent control of the initialization process, enabling the first transistor to initialize the control terminal while the second transistor initializes the intermediate node, thereby reducing potential variations and leakage currents that cause flicker
Solution Approach 2:
The pixel circuit performs initialization actions before the light emitting phase by applying initialization signals during the programming phase. The first initialization transistor initializes the control terminal and the second initialization transistor initializes the intermediate node in advance, ensuring stable potentials before drive current generation, thus preventing flicker during idle mode
2Device complexity
If the first additional scan signal and first scan signal have the same timing, then the circuit operation is simple, but the potential difference at intermediate nodes causes leakage currents and drive current fluctuations
Solution Approach 1:
The patent introduces dynamic timing control where the first additional scan signal is delayed relative to the first scan signal. This dynamic adjustment of signal timing allows the first initialization transistor to complete its operation before the second initialization transistor is activated, creating a sequential initialization process that stabilizes potentials and reduces leakage currents without excessive complexity
Data Source
AI summary
The display panel includes an array substrate, and the array substrate includes pixel circuits arranged in an array. A first initialization module and a second initialization module are connected in series to an initialization signal terminal and a control terminal of the drive module, an output terminal of the second initialization module is electrically connected to the control terminal of the drive module; a control terminal of the first initialization module is used for receiving a first additional scan signal, and a control terminal of the second initialization module is used for receiving a first scan signal. Within at least one light emitting period of one frame duration, the end time of an active level pulse of the first additional scan signal is later than the end time of an active level pulse of the first scan signal.