LCD Pixel Charging Circuit Pre-Charging Strategy
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Solution Overview
Problem
High frame rate televisions and tri-gate structured LCDs face insufficient charging due to high scan frequency, which reduces the time a thin film transistor (TFT) is turned on, affecting pixel charging efficiency.
Innovation Solution
A pixel charging method and circuit that outputs specific driving signals to adjacent scan lines with controlled angle cutting periods to ensure complete conduction of active switches during pre-charging and charging, preventing capacitive coupling effects and improving charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If angle cutting is applied to reduce capacitive coupling effect, then capacitive coupling is reduced, but scan potential decreases and pixel charging effect deteriorates
Solution Approach 1:
The patent segments the driving signal waveform into distinct time periods: a first time period without angle cutting for pre-charging, and a second time period with angle cutting for charging. This temporal segmentation allows the system to optimize for different objectives at different stages - maintaining high scan potential during pre-charge while reducing capacitive coupling during the charging phase.
Solution Approach 2:
The patent applies preliminary action by performing pre-charging of pixels before the main charging operation. During this pre-charging phase (first time period), no angle cutting is applied to ensure high scan potential and complete TFT conduction, preparing the pixels for subsequent charging while avoiding the harmful capacitive coupling effect that would occur if angle cutting were applied from the beginning.
2Productivity
If scan frequency is increased to achieve high frame rate, then frame rate is improved, but TFT on-time decreases and charging completeness deteriorates
Solution Approach 1:
The patent applies preliminary action by introducing a pre-charging phase before the main charging operation. During this pre-charging phase, the active switch is turned on without angle cutting to ensure complete conduction and adequate charging, even at high scan frequencies. This preliminary charging action compensates for the reduced TFT on-time caused by high frame rates.
Solution Approach 2:
The patent applies dynamics by dynamically adjusting the driving signal characteristics based on the charging stage. The signal transitions from no angle cutting during pre-charging to angle cutting during main charging, allowing the system to adapt to the time constraints imposed by high frame rates while maintaining charging effectiveness.
Data Source
AI summary
A pixel charging method and circuit, an LCD panel and an LCD device, wherein two driving signals drive two adjacent row scan lines to charge the pixel. When the pixel of a row is charged, the pixel of the next row is pre-charged, and there is no angle cutting in a certain period before and after the pre-charge is completed, so that after the pre-charge of the pixel is completed and the charging of the pixel starts, the active switch of the pixel is turned on completely without affecting the actual charging process, in order to improve the effect of charging the pixel.