LCD Afterimage Elimination via Dynamic Gray-Scale Alternation
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Solution Overview
Problem
In liquid crystal display (LCD) devices, still images displayed for a long time cause liquid crystal molecules to become polarized, leading to afterimages when the image is changed, due to ion aggregation and residual electric fields.
Innovation Solution
A method that determines if a still image is displayed, generates alternative output gray-scales to match the actual gray-scale, and alternates between these gray-scales to create a dynamic image output, preventing polarization and afterimages by changing the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a still image is displayed for a long time in TFT-LCD, then the image display stability is improved, but the liquid crystal molecules become polarized causing afterimage
Solution Approach 1:
The patent applies the dynamics principle by converting static gray-scale values into dynamic alternating output. Instead of displaying the same gray-scale value continuously for still images, the system alternates between multiple output gray-scales (e.g., higher and lower gray-scales) over time. This temporal variation prevents liquid crystal molecules from maintaining a fixed polarized state, thereby eliminating afterimages while preserving the perceived stability of the displayed image through persistence of vision.
Solution Approach 2:
The patent implements periodic action by systematically alternating between different output gray-scales at regular intervals. The controller generates a sequence of alternating gray-scale values (such as alternating between gray-scale N+1 and gray-scale N-1) rather than maintaining a constant gray-scale. This periodic variation in the electric field applied to liquid crystal molecules prevents continuous polarization, solving the afterimage problem while maintaining stable visual display.
2Reliability
If alternative gray-scales are alternated to eliminate afterimage, then afterimage is eliminated, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the gray-scale output parameters dynamically. The system determines the actual gray-scale value needed for display and then generates alternative output gray-scales (typically one higher and one lower than the actual gray-scale) that alternate in sequence. This parameter variation approach eliminates afterimages by preventing liquid crystal polarization while maintaining manageable control complexity through systematic gray-scale manipulation rather than complex hardware modifications.
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
Effectively eliminates afterimages by converting still images into dynamic outputs, ensuring the liquid crystal molecules are not polarized, thus maintaining image quality and preventing residual image traces.
Implementation Method 1
the liquid crystal molecules cannot rotate normally under the control of the signal voltage since the liquid crystal molecules are polarized after being driven for a long time
Data Source
AI summary
A method for controlling image display is disclosed. The method comprises the following steps: determining whether a still image appears; obtaining, when a still image appears, an actual gray-scale of each pixel of said still image, and generating a plurality of output gray-scales corresponding to the actual gray-scale; and substituting the actual gray-scale with said output gray-scales alternately, and forming dynamic image output. According to the present disclosure, the still image can be converted into dynamic image output through controlling the image display in spatial domain and time domain, and thus the problem of afterimage of the still image can be solved.