OLED Pixel Driving Circuit Precharging Overlap
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Solution Overview
Problem
Existing OLED display pixel driving circuits face inefficiencies in charging storage capacitors, leading to inconsistent driving currents and inadequate saturation current, particularly in high-resolution displays, due to varying threshold voltages and limited TFT sizes.
Innovation Solution
The introduction of a precharging transistor and overlapping scanning times between row scanning control lines allows for advanced charging of storage capacitors during previous row scanning cycles, ensuring stable driving currents by partially overlapping the scanning time of the current row with the previous row, thereby improving charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scanning time of each row is extended to allow sufficient charging of the storage capacitor, then the charging efficiency is improved, but the display refresh rate is reduced
Solution Approach 1:
The patent applies preliminary action by enabling the storage capacitor to be precharged during the scanning period of the previous row through the precharging transistor. This allows the capacitor to accumulate charge in advance, so that when the current row scanning begins, the capacitor is already sufficiently charged, eliminating the need to extend the scanning time while still ensuring adequate charging for stable driving current.
2Reliability
If the TFT transistor size is increased to provide sufficient saturation current, then the driving current stability is improved, but the pixel area is increased
Solution Approach 1:
The patent uses preliminary action by precharging the storage capacitor during the previous row's scanning period. This ensures that when the driving transistor operates, the capacitor is already charged to the required voltage level, providing sufficient saturation current without needing to increase the driving transistor size, thus maintaining pixel area constraints while ensuring driving current stability.
3Manufacturing precision
If the scanning time is extended to ensure sufficient charging, then the display quality is improved, but the time consumption per frame is increased
Solution Approach 1:
The patent implements preliminary action by charging the storage capacitor during the previous row's scanning time through the precharging transistor. This overlapping charging approach ensures that the capacitor is fully charged before the current row scanning begins, maintaining high display quality with stable driving current while avoiding any increase in total frame time, as the charging occurs in parallel with previous row operations.
Data Source
AI summary
The present invention discloses a pixel driving circuit of OLED display, which comprises: a scanning transistor TFT1, the source thereof being connected to the data line, the gate thereof being connected to a current row scanning control line, the drain thereof being connected to a first terminal of a storage capacitor C1; a precharging transistor TFT3, the source thereof being connected to the data line, the gate thereof being connected to a previous row scanning control line, and the drain thereof being connected to the first terminal of the storage capacitor C1; a driving transistor TFT2; and an organic light emitting diode; wherein, the scanning time of the current row scanning control line at least partially overlaps that of the previous row scanning control line. The embodiment of the present invention can improve the charging efficiency of the storage capacitor in each pixel unit and then improve the display effects.