Gate Driving Circuit Supplementary Unit Voltage Jump Reduction
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Solution Overview
Problem
Existing gate driving circuits in LCDs suffer from large voltage jumps during TFT turn-off, affecting picture quality due to the deactivation of multi-level gate (MLG) function when temperature compensation circuits raise the voltage beyond what DC/DC ICs can handle, leading to reduced mobility in low-temperature conditions.
Innovation Solution
Incorporating a supplementary unit in the gate driving circuit that controls the output signal through a second clock terminal, allowing the clock signal to transition from a high level to a lower high level, reducing the voltage jump and enabling the MLG function, which includes a pull-up driving unit, a reset unit, and a pull-down unit, along with a supplementary unit comprising TFT switching devices to manage the clock signals and output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature compensation circuits are used to raise voltage for low-temperature operation, then mobility is improved, but the voltage exceeds DC/DC IC handling capability and MLG function is deactivated
Solution Approach 1:
The gate driving circuit is divided into multiple stages with separate voltage control mechanisms. The supplementary unit segments the voltage transition process into two phases: first phase uses normal voltage level for standard operation, second phase uses reduced voltage level for voltage jump suppression. This segmentation allows independent optimization of each phase without requiring complex overall voltage control.
Solution Approach 2:
The circuit dynamically switches between different operating modes based on temperature conditions and operational phase. The supplementary unit activates during specific phases to provide reduced voltage level, creating a dynamic voltage control system that adapts to different operational requirements without manual intervention or complex control logic.
2Device complexity
If traditional gate driving circuit is used, then device complexity is low, but large voltage jump occurs at TFT turn-off affecting picture quality
Solution Approach 1:
The supplementary unit acts as an intermediary between the main gate driving circuit and the output node. It introduces an intermediate voltage level (second high level) between the normal high voltage level and the low voltage level, thereby smoothing the voltage transition and eliminating the abrupt voltage jump that directly affects picture quality.
Solution Approach 2:
The supplementary unit prepares a reduced voltage level in advance before the TFT turn-off event occurs. By having the second high level voltage ready and available, the circuit can smoothly transition through this intermediate level during the critical turn-off moment, cushioning the impact of the voltage change and preventing picture quality degradation.
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 supplementary unit reduces the voltage jump at TFT turn-off, achieving the MLG function and enhancing picture quality by managing clock signals and output voltages, thereby stabilizing the gate driving circuit operation across temperature variations.
Implementation Method 1
a first TFT switching device M1, a second TFT switching device M2, a third TFT switching device M3, a fourth TFT switching device M4
Data Source
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Figure 3~4
Figure 5~6
AI summary
The present disclosure provides a gate driving circuit, a gate driving method and a liquid crystal display. Said gate driving circuit includes shift registers at a plurality of stages, wherein the shift register at each stage includes a pull-up driving unit, a pull-up unit, a reset unit, a pull-down unit and a supplementary unit; said pull-up unit is used for making a clock signal at a first clock terminal an output signal of the shift register at the present stage when being turned on; said supplementary unit, connected to said pull-up unit, is used for making a clock signal at a second clock terminal the output signal of the shift register at the present stage when being turned on. With the supplementary unit of the shift register at each stage in the gate driving circuit, the present disclosure controls the output of the shift register through turning on the supplementary unit at the instant of the TFT being turned off, which can reduce voltage jump of a pixel, achieve the MLG function and enhance the picture quality of the LCD.