Interlace Video Signal Control for LCD Residual Image Prevention
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Solution Overview
Problem
IPS liquid crystal displays face challenges in preventing residual image phenomena, especially with interlace videos, due to charge accumulation caused by impurities and polarity differences between odd and even fields, which existing technologies struggle to address effectively.
Innovation Solution
A video processing device that generates a display video signal for a liquid crystal display using a frame inversion scheme, with a control microcomputer setting a display invalid section for interlace video signals based on a vertical synchronization signal, and optionally adjusting this period based on temperature detection, to prevent charge accumulation and residual images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If interlace video is displayed using frame inversion scheme, then view angle characteristics are improved, but residual image phenomenon occurs due to charge accumulation
Solution Approach 1:
The patent applies periodic action by inverting the polarity of the liquid crystal display at regular intervals (every N frames) to eliminate charge accumulation. The control microcomputer controls the data enable signal to set display invalid sections at periodic intervals, creating a periodic polarity inversion that prevents residual image formation while maintaining the benefits of frame inversion driving scheme for view angle characteristics.
2Reliability
If polarity inversion is conducted for each frame, then charge accumulation is eliminated for non-interlace video, but charge accumulation cannot be eliminated for interlace video due to field polarity differences
Solution Approach 1:
The patent applies dynamics by making the display invalid section setting adaptable to different video types. The control microcomputer detects whether the input video is interlace or non-interlace and dynamically adjusts the polarity inversion strategy: for non-interlace video, it uses standard frame-by-frame polarity inversion, while for interlace video, it sets display invalid sections at periodic intervals to achieve effective polarity inversion despite field differences.
3Reliability
If display invalid section is set at fixed period, then residual image phenomenon is prevented, but temperature changes affect prevention effectiveness
Solution Approach 1:
The patent applies feedback by using a temperature detector to monitor the display device temperature and feeding this information back to the control microcomputer. The control microcomputer then adjusts the display invalid section period based on the detected temperature, extending the period at higher temperatures and reducing it at lower temperatures to maintain optimal residual image prevention effectiveness across different operating conditions.
Data Source
AI summary
Provided is a video processing device that generates a display video signal to be supplied to a liquid crystal display having a liquid crystal that is driven by a frame inversion scheme and includes a control microcomputer and a video signal processor. The control microcomputer controls a data enable signal such that a display invalid section having a predetermined number of fields is set for an interlace video signal at a predetermined period based on a vertical synchronization signal included in the interlace video signal input from outside. The video signal processor generates the display video signal by setting the display invalid section for the interlace video signal based on the data enable signal and outputs the display video signal to the liquid crystal display.