Display Panel Pixel Driving Circuit With Preliminary Source Reset
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Solution Overview
Problem
The parasitic capacitance between the gate and source of the driving transistor in the pixel driving circuit causes varying gate-source voltage differences during the reset phase, leading to different source voltages and threshold voltages, resulting in residual images on the display panel.
Innovation Solution
The display panel incorporates a pixel driving circuit with additional transistors and conductive layers to stabilize the gate-source voltage difference by using transistors like the eighth transistor to reset the second node N2, ensuring consistent voltage levels across different gray scales.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel driving circuit uses a conventional reset phase to initialize gate voltage, then the gate voltage is set to initial voltage, but the parasitic capacitance causes varying source voltage changes leading to different gate-source voltage differences and residual images
Solution Approach 1:
The patent introduces a preliminary reset action by adding an eighth transistor that resets the source node before the main reset operation. This preliminary action compensates for the parasitic capacitance effect by pre-adjusting the source voltage, ensuring that subsequent reset operations produce consistent gate-source voltage differences regardless of previous gray scale states, thereby eliminating residual images
Solution Approach 2:
The eighth transistor acts as an intermediary element between the initial signal line and the source node. It mediates the reset process by controlling the discharge path of the parasitic capacitance through its gate connected to the reset signal line, isolating the harmful capacitance effect from affecting the main driving transistor's operation and preventing residual image formation
2Object-generated harmful factors
If additional transistors and conductive layers are added to stabilize gate-source voltage, then residual images are reduced, but device complexity increases
Solution Approach 1:
The patent segments the reset function into two independent parts: the eighth transistor handles the source node reset while the existing reset transistor handles the gate node reset. This segmentation allows each transistor to specialize in one aspect of the reset process, improving effectiveness without requiring a complete redesign of the entire pixel circuit, thus limiting the increase in complexity
Solution Approach 2:
The eighth transistor is designed with multi-functionality, serving both as a reset switch for the source node and as a compensation mechanism for parasitic capacitance. By connecting its gate to the reset signal line, it universally handles multiple aspects of the voltage stabilization problem simultaneously, achieving residual image elimination without proportionally increasing circuit complexity
Data Source
AI summary
The display panel includes a pixel driving circuit. The pixel driving circuit includes a driving transistor and an eighth transistor. A first terminal of the eighth transistor is connected to a first terminal of the driving transistor, and a second terminal of the eighth transistor is connected to a third initial signal line. The display panel further includes: a base substrate, a first active layer, a first conductive layer, and the third initial signal line. The first active layer is located on a side of the base substrate. The first active layer includes an eighth active portion, a second active portion, a ninth active portion, a tenth active portions, and an eleventh active portion. The eighth active portion is connected between the ninth active portion and the tenth active portion. The eleventh active portion is connected to a side of the second active portion.