LCD Gate Drive Voltage Stabilization via Temperature Compensation
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Solution Overview
Problem
Liquid crystal display (LCD) devices face instability in gate driving circuits due to temperature variations, leading to degradation in picture quality caused by wide voltage ranges required for liquid crystals and large size of thin film transistors (TFTs), which result in increased current variation and flicker issues.
Innovation Solution
An apparatus and method that detect ambient temperature at different time points to vary gate driving voltage and common voltage levels, using a drive voltage controller to generate signals for adjusting these voltages inversely proportional to temperature, thereby stabilizing the gate driving circuit and reducing image display voltage variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the level of drive voltage is linearly varied in accordance with temperature, then gate and data drive circuits can be stably driven and picture quality is enhanced, but in LCD devices with gate drive circuit formed at the liquid crystal panel using amorphous silicon TFTs, the method cannot be applied because TFTs have wide voltage operation ranges and large sizes causing increased current variation
Solution Approach 1:
The patent applies parameter changes by varying the gate drive voltage and common voltage levels in non-linear accordance with temperature changes. Specifically, the gate drive voltage is adjusted by a first voltage variation amount and the common voltage is adjusted by a second voltage variation amount, where these variation amounts are determined based on temperature compensation characteristics. This resolves the contradiction by adapting the voltage adjustment parameters to the specific characteristics of a-Si TFTs, enabling stable operation while maintaining applicability to this TFT type.
2Temperature
If TFTs are made large to meet high-temperature operation characteristics, then high-temperature stability is achieved, but current amount variation depending on temperature variation is increased causing gate drive circuit instability
Solution Approach 1:
The patent applies dynamics by implementing dynamic voltage adjustment that adapts to temperature variations. The gate drive voltage and common voltage are dynamically adjusted based on detected temperature changes, with the adjustment amounts varying according to the temperature compensation characteristics. This dynamic adjustment compensates for the increased current variation caused by large TFT sizes, thereby maintaining gate drive circuit stability across different temperatures.
3Temperature
If the level of low drive voltage or high drive voltage is varied to compensate for temperature, then temperature compensation is achieved, but the variation width of image display voltage depending on kick-back voltage (ΔVp) is increased causing picture quality degradation
Solution Approach 1:
The patent applies local quality by implementing differentiated voltage adjustment for different voltage components. Specifically, the gate drive voltage is adjusted by a first voltage variation amount while the common voltage is adjusted by a second voltage variation amount, where these adjustment amounts are optimized based on temperature compensation characteristics. This localized adjustment approach compensates for temperature effects while minimizing the variation width of the image display voltage, thereby preventing picture quality degradation.
Data Source
AI summary
Discussed are an apparatus and method for driving a liquid crystal display device, whereby the apparatus includes a data driver for driving data lines of a liquid crystal panel, setting detectable temperatures for different temperature detection time points, detecting an ambient temperature at each temperature detection time point, and outputting a gate drive voltage variation signal and a common voltage variation signal in accordance with the set and detected temperatures at each temperature detection time point, and a power supplier for varying levels of a gate drive voltage and a common voltage in accordance with the gate drive voltage variation signal and the common voltage variation signal, and supplying the gate drive voltage and common voltage to a gate driver and the liquid crystal panel, respectively.