Pixel Circuit Pre-Charging for High-Refresh Threshold Compensation
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Solution Overview
Problem
In high-frequency refreshing scenarios, pixel circuits in display panels do not have sufficient time for threshold voltage compensation due to line scanning time limitations, affecting display quality, especially in large and medium-sized panels, and failing to achieve full band support from low to high frequencies.
Innovation Solution
A pixel circuit design incorporating a pre-charging circuit, data writing circuit, first and second energy storage circuits, and driving circuits, along with additional control circuits, allows for efficient threshold voltage compensation by sequencing phases such as pre-charging, initialization, and refresh reset to ensure adequate time for data writing and compensation, even at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-frequency refreshing is implemented, then display refresh rate is improved, but threshold voltage compensation time becomes insufficient
Solution Approach 1:
The patent applies preliminary action by performing pre-charging of the storage capacitor in the previous frame period before the actual data writing phase. This allows the pixel circuit to have sufficient time for threshold voltage compensation during the current frame period even when operating at high refresh rates, as the pre-charging operation prepares the circuit state in advance.
2Speed
If line scanning time is reduced for high-frequency operation, then display refresh rate is improved, but display quality deteriorates
Solution Approach 1:
The patent performs pre-charging operations in advance during the previous frame period, which allows the main data writing and compensation phases to complete faster during the current frame period. This maintains display quality by ensuring sufficient compensation time while achieving high refresh rates through the preliminary preparation.
Solution Approach 2:
The patent segments the data writing process into multiple phases: pre-charging phase (in previous frame), initialization phase, and data writing phase (in current frame). This segmentation allows each phase to be optimized independently, ensuring that threshold voltage compensation receives adequate time while maintaining high overall refresh rates.
3Duration of action of moving object
If pre-charging phase is added before data writing, then threshold voltage compensation time is improved, but overall circuit complexity increases
Solution Approach 1:
The pre-charging transistor T1 is designed to serve multiple functions: it acts as the pre-charging switch during high-frequency operation, and can also function as part of the normal data writing path during low-frequency operation. This multi-functionality reduces the need for entirely separate circuit components, thereby limiting the increase in circuit complexity while still providing the necessary pre-charging capability.
Data Source
AI summary
A pixel circuit, a display panel, and a display device. The pixel circuit includes a light-emitting element, a pre-charging circuit, a first energy storage circuit, a data writing circuit and a driving circuit; the pre-charging circuit writes a data voltage into a pre-charging node under the control of a pre-charging scanning signal; the first energy storage circuit is electrically connected to the pre-charging node for storing electric energy; the data writing circuit controls the connection or disconnection between the pre-charging node and the first terminal of the driving circuit under the control of the first scanning signal; the first terminal of the driving circuit is electrically connected to the light-emitting element for driving the light-emitting element. The present disclosure enables the threshold voltage compensation to be completed during the data writing phase without the line scan time limitation during high frequency display.