LCD Pixel Drive Circuit for Residual Voltage Reset at Power-Off
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Solution Overview
Problem
Conventional liquid crystal display devices do not effectively remove residual voltage from pixel electrodes, which can lead to burn-in and flicker issues due to potential fluctuations through drain-to-gate capacitance after the pixel electrode is set to ground potential.
Innovation Solution
A display device with a drive circuit that supplies a first power supply voltage signal, sets the common electrode to ground potential, and applies an adjustment potential to the signal line during the power-off sequence to quickly reset the pixel electrode potential, reducing residual voltage and burn-in.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel electrode potential is set to ground potential by turning on the pixel transistor, then the liquid crystal drive voltage is discharged and burn-in is reduced, but potential fluctuation through drain-to-gate capacitance generates residual voltage in the pixel electrode
Solution Approach 1:
The patent applies preliminary action by setting the signal line potential to a predetermined potential (higher than GND) before turning off the pixel transistor. This preliminary potential setting prevents potential fluctuation through the drain-to-gate capacitance when the gate potential changes, thereby avoiding residual voltage generation in the pixel electrode while maintaining the burn-in reduction effect.
2Speed
If the gate potential is changed from on potential to off potential, then the pixel transistor turns off and liquid crystal voltage is discharged, but the drain-to-gate capacitance causes potential fluctuation and residual voltage generation
Solution Approach 1:
The patent applies preliminary action by pre-setting the signal line potential to a predetermined potential before the gate potential transitions from on to off. This preliminary potential configuration ensures that when the pixel transistor turns off, no potential fluctuation occurs through the drain-to-gate capacitance, thereby eliminating residual voltage while maintaining fast power-off speed.
Solution Approach 2:
The patent applies preliminary anti-action by applying a compensating potential to the signal line before the gate potential change. This preliminary anti-action counteracts the potential fluctuation that would otherwise occur through the drain-to-gate capacitance, preventing residual voltage generation while allowing rapid transistor switching.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces burn-in and flicker by quickly resetting the pixel electrode potential to ground, minimizing residual voltage and ensuring stable display performance.
Implementation Method 1
Holding capacitance is provided between the pixel electrode and a common electrode supplied with a common potential lower than a GND potential in a display operation
Data Source
AI summary
A display device includes a pixel, a scanning line, a signal line, and a drive circuit configured to be supplied with a first power supply voltage signal of a positive value and a second power supply voltage signal of a negative value. The drive circuit includes: a gate driver configured to supply a scanning signal to the scanning line; a signal line selection circuit configured to supply a pixel signal to the signal line; and a display control circuit. The display control circuit is configured to, at first time in a power-off sequence, supply the first power supply voltage signal to the scanning line, supply a GND potential to the common electrode, and supply an adjustment potential of a positive value to the signal line. The display control circuit is configured to supply the GND potential to the scanning line at second time after the first time.