Non-periodic Random Polarity Inversion for LCD Flicker Elimination
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Solution Overview
Problem
Conventional polarity inversion methods in liquid crystal displays cause screen flicker due to periodic inversions, particularly when displaying specific patterns like the 'Killer pattern', which is unavoidable and induces image retention issues.
Innovation Solution
A non-periodic random inversion method is introduced, where pixels are driven by odd and even inversion signals that randomly alternate between logic 1 and logic 0, eliminating the need for periodic polarity changes and reducing flicker by using a point-to-point architecture with a timing controller generating random inversion signals for each group of pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic polarity inversion is used to eliminate image retention, then Killer pattern is resolved, but screen flicker occurs due to periodic nature
Solution Approach 1:
The patent applies dynamics by transitioning from a static periodic inversion pattern to a dynamic random inversion pattern. The inversion signal changes polarity randomly rather than periodically, making the system adaptive and unpredictable. This random dynamic behavior prevents the formation of Killer patterns while avoiding the periodicity that causes screen flicker, thus resolving the technical contradiction between eliminating image retention and avoiding flicker.
Solution Approach 2:
The patent inverts the conventional approach by using non-periodic action instead of periodic inversion. The inversion signal switches between logic levels randomly without a fixed period, thereby eliminating the harmful effects of periodicity (screen flicker) while maintaining the beneficial effect of polarity inversion (Killer pattern elimination). This is achieved through a random number generator that produces unpredictable inversion sequences.
2Reliability
If double period inversion signal is used, then first Killer pattern is resolved, but another Killer pattern emerges
Solution Approach 1:
The patent applies parameter changes by varying the inversion signal parameters from fixed periodic patterns to random variations. Instead of using a fixed double-period inversion pattern that can be predicted and countered by specific input patterns, the system uses random parameter changes in the inversion signal. This makes the system adaptable to any input pattern, preventing the emergence of new Killer patterns while maintaining elimination of existing ones.
Solution Approach 2:
The patent uses the inversion principle by inverting the conventional periodic inversion approach. Rather than following a predictable inversion cycle that can be exploited, the system inverts the logic by using random inversion patterns. This reverse thinking approach ensures that no fixed pattern can be exploited to create Killer patterns, thereby enhancing the display's adaptability to various input patterns.
Data Source
AI summary
An inversion method for use in a liquid crystal display having pluralities of pixels. First, at least one inversion signal is provided to determine a polarity. A data voltage is then generated according to the polarity and a data signal. Thereafter, a scan signal is provided to activate a pixel, such that the data voltage is converted to luminance. The inversion signal is a non-periodic signal. When the scan signal activates the pixel, the inversion signal provides the random alternative of a first level and a second level.