Pixel Driving Circuit Pre-Charging for AMOLED Data Writing
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Solution Overview
Problem
Existing active matrix OLED (AMOLED) pixel driving circuits face challenges in reducing power consumption and improving display quality due to increased transient current and reduced charging rate, particularly because the signal time for writing data signals is occupied by the demultiplexer (DEMUX) operation, leading to reduced display quality.
Innovation Solution
A pixel driving circuit comprising a reset module, data write module, output module, and pre-charging module, where the pre-charging module pre-charges the control node before scanning, allowing for faster data signal writing and improved charging rate by establishing a raised base point for writing data signals, thus enhancing display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a DEMUX is used to separate RGB signals in AMOLED, then manufacturing cost is reduced, but data writing time is reduced and charging rate is reduced
Solution Approach 1:
The patent applies preliminary action by pre-charging the control node before the data writing phase. The pre-charging module raises the voltage of the control node to a high level before the scanning signal writes data, ensuring that the light emitting device is already in a ready state. This preliminary charging action eliminates the need for extended data writing time while maintaining proper signal separation functionality.
Solution Approach 2:
The patent segments the driving circuit into distinct functional modules: a reset module, a pre-charging module, a data write module, and an output module. This segmentation allows each module to operate independently and efficiently, with the pre-charging module specifically dedicated to raising the control node voltage before data writing, thereby resolving the time conflict without affecting the DEMUX cost-saving benefit.
2Duration of action of moving object
If scanning signal time is used to write Vth signal, then emission signal timing is maintained, but data signal writing time is reduced
Solution Approach 1:
The pre-charging module performs preliminary charging of the control node during the period when the scanning signal is writing the Vth signal. By raising the control node voltage to a high level in advance, the system ensures that when data writing occurs, the light emitting device can charge rapidly without being constrained by the Vth writing timeline, thus maintaining emission timing while improving charging rate.
Solution Approach 2:
The patent ensures continuity of useful action by overlapping the pre-charging operation with the Vth signal writing process. Both operations occur simultaneously without interfering with each other, maximizing the utilization of available time periods and ensuring continuous productive action in the pixel driving circuit.
3Speed
If transient current is increased to reduce driving time, then display size can be increased, but power consumption increases significantly
Solution Approach 1:
The pre-charging module performs preliminary charging of the control node before the data writing and light emitting phases. By raising the control node voltage in advance, the system reduces the charging time required during the active phases without requiring increased transient current, thereby maintaining fast driving speeds while avoiding significant power consumption increases.
Solution Approach 2:
The patent changes the voltage parameter of the control node dynamically - raising it to a high level during the pre-charging phase and then using it to drive the light emitting device. This parameter change enables faster charging during the emission phase without requiring sustained high current, thus reducing overall power consumption while maintaining fast driving performance.
Data Source
AI summary
The present invention provides a pixel driving circuit and a driving method thereof, and a display apparatus, which can raise starting point for writing a data, ensure time for writing the data, and avoid distortion of the written data. The pixel driving circuit comprises a reset module, a data write module, an output module and a pre-charging module, wherein during a period after a reset stage and before inputting of a row driving signal, the pre-charging module performs a step of pre-charging.