Pixel Circuit Charging Time Extension
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Solution Overview
Problem
High-frequency charging in liquid crystal displays leads to a decrease in dielectric constant, resulting in insufficient charges, reduced voltage, and abnormal brightness due to fixed charges in the pixel system.
Innovation Solution
A pixel structure incorporating a first voltage dividing unit, a liquid crystal capacitor, a control unit, a writing-in unit, and an adjusting unit, which cooperatively control the voltage stored in the liquid crystal capacitor to mitigate the effects of high-frequency charging, ensuring continuous charging and reducing power loss by turning off transistors after the charging process is completed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frame frequency is increased to improve display resolution, then the display quality is improved, but the charging time of the pixel is shortened causing insufficient charges
Solution Approach 1:
The pixel circuit performs preliminary charging action by extending the charging period through delayed transistor switching. The second transistor is turned off later than the first transistor, creating an extended charging window that ensures sufficient charge accumulation even at high frame frequencies, thereby resolving the contradiction between high productivity and sufficient charging duration
2Reliability
If storage capacitors with large area are used to maintain voltage stability, then the voltage stability is improved, but the aperture ratio is significantly decreased
Solution Approach 1:
The invention changes the temporal parameters of the charging process rather than increasing capacitor area. By extending the charging time through controlled transistor switching sequences, the circuit achieves voltage stability without requiring larger storage capacitors, thus maintaining a high aperture ratio while ensuring reliable voltage supply to the liquid crystal capacitor
3Quantity of substance
If the charging time is extended to provide sufficient charges, then the charge adequacy is improved, but the power loss increases due to continuous transistor conduction
Solution Approach 1:
The pixel circuit implements periodic action by using controlled, sequential transistor switching. The first transistor conducts during the initial charging phase, then turns off, followed by the second transistor turning off later to complete the charging process. This periodic switching pattern ensures sufficient charge accumulation while minimizing power loss by limiting the conduction time of each transistor to only when necessary
Data Source
AI summary
A pixel includes a voltage dividing unit, a LC capacitor, a control unit, a first capacitor, a writing-in unit, and an adjusting unit. First terminal of the voltage dividing unit receives a first power voltage. The control terminal of the voltage dividing unit receives a first control signal. The LC capacitor is electrically coupled to the second terminal of voltage dividing unit. The control terminal of the control unit receives a second control signal. The writing-in unit provides a first pixel data signal to the first capacitor based on a third control signal. The adjusting unit receives a second power voltage. The adjusting unit divides voltage difference between the first and second power voltages based on the first pixel data signal stored in the first capacitor so as to control voltage stored in the LC capacitor, such that the LC corresponding to LC capacitor can be controlled.