Oxide Semiconductor Pixel Transistor for LCD Voltage Compensation
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in reducing power consumption and maintaining display quality, particularly during still image display, due to complex driver circuit configurations and voltage fluctuations caused by leakage currents and parasitic capacitance, leading to issues like image burn-in and gray scale inconsistencies.
Innovation Solution
Incorporating a transistor with an oxide semiconductor layer as the channel formation layer in the pixel, which allows for voltage compensation between frame periods and polarity inversion during still image display, thereby reducing power consumption and stabilizing gray scale levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a break period is provided during which no scan line and no signal line are selected, then power consumption is reduced, but the voltage applied to the liquid crystal element is largely decreased by leakage current and parasitic capacitance, lowering display quality
Solution Approach 1:
The patent applies periodic action by implementing inversion driving where the polarity of voltage applied to the liquid crystal element is inverted between subsequent frame periods. This periodic voltage inversion compensates for voltage decrease caused by leakage current during break periods, maintaining consistent gray scale levels while allowing extended break periods for reduced power consumption
Solution Approach 2:
The patent changes the voltage parameter by inverting its polarity between frame periods. This parameter change compensates for the voltage decrease that occurs during break periods due to leakage current and parasitic capacitance, thereby maintaining display quality while enabling longer break periods for lower power consumption
2Reliability
If inversion driving is performed to suppress image burn-in, then display reliability is improved, but voltage fluctuation causes gray scale level differences between sequential frame periods, deteriorating display quality
Solution Approach 1:
The patent implements feedback by comparing image data between sequential frame periods and detecting voltage fluctuations. Based on this feedback, the system adjusts the voltage applied to the liquid crystal element to compensate for gray scale level differences, maintaining display quality while continuing inversion driving for burn-in suppression
Solution Approach 2:
The patent adjusts voltage parameters dynamically by inverting polarity between frame periods and compensating for voltage fluctuations. This parameter adjustment maintains consistent gray scale levels while preserving the inversion driving effect for preventing image burn-in
3Use of energy by stationary object
If the interval between writing operations into pixels is extended during break period, then power consumption is reduced, but the voltage applied to liquid crystal element decreases significantly due to leakage current
Solution Approach 1:
The patent uses periodic voltage inversion between frame periods to compensate for voltage loss during extended break periods. This allows significantly longer intervals between writing operations while maintaining sufficient voltage levels for proper liquid crystal element operation and display quality
Solution Approach 2:
The patent changes the voltage parameter by inverting polarity and applying compensation voltage between frame periods. This enables extended break periods with reduced power consumption while preventing significant voltage decrease that would otherwise occur due to leakage current over the extended time interval
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
This approach reduces power consumption during still image display while maintaining display quality by compensating voltage fluctuations and preventing image burn-in, allowing for longer display periods with reduced power usage.
Implementation Method 1
the voltage applied to a liquid crystal element is largely decreased by leakage current of a transistor or parasitic capacitance
Implementation Method 2
a liquid crystal element including a first terminal to which the image signal is supplied and a second terminal to which a common voltage is input
Data Source
AI summary
Disclosed is a liquid crystal display device and a driving method thereof for displaying an image, in which the polarity of a voltage applied to the liquid crystal element is inverted in a first frame period and a second frame period which are sequential. The voltage applied to the liquid crystal element is compensated in the case where images of the first frame period and the second frame period are judged as a still image as a result of comparison of the image of the first frame period with the image of the second frame period and the absolute value of the voltage applied to the liquid crystal element in the first frame period is different from that of the voltage applied to the liquid crystal element in the second frame period.