Liquid Crystal Display Tailing Suppression via Black Level Shift
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Solution Overview
Problem
Liquid crystal panels in projectors and displays suffer from the tailing phenomenon, where image abnormalities occur due to voltage changes, leading to perceptible after-images and reduced contrast, especially when transitioning from black to white, and existing solutions either compromise image quality or require significant memory and circuitry for correction.
Innovation Solution
An image display apparatus and method that detects picture levels for each picture element, adjusts transmittance to shift the black level towards the white side when brightness exceeds a threshold, using a processor to adjust voltage levels and maintain contrast while suppressing the tailing phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the aperture ratio of the liquid crystal panel is increased to achieve higher luminance, then the luminance is improved, but the area of light shielding decreases and the configuration becomes more susceptible to light leakage and tailing phenomenon
Solution Approach 1:
The patent applies preliminary action by adjusting the black level voltage before displaying moving images. The processor shifts the black level toward the white side in advance, which prevents the liquid crystal molecules from orienting in abnormal directions during subsequent voltage changes, thereby suppressing the tailing phenomenon without requiring structural modifications to the panel.
2Productivity
If voltage changes are applied to picture element electrodes to display moving images, then the moving images are displayed, but liquid crystal molecules orient in abnormal directions under horizontal field influence, causing tailing phenomenon
Solution Approach 1:
The patent applies preliminary anti-action by introducing a black level shift that counteracts the horizontal field influence before it can cause abnormal liquid crystal orientation. By shifting the black level voltage toward the white side, the patent creates a preventive effect that opposes the tailing phenomenon caused by voltage changes during moving image display.
3Reliability
If existing correction methods are applied to suppress tailing phenomenon, then the tailing phenomenon is reduced, but image contrast deteriorates or extensive memory and circuitry are required
Solution Approach 1:
The patent applies parameter changes by modifying the black level voltage parameter rather than using complex correction circuits. The processor shifts the black level toward the white side by a predetermined amount, which suppresses the tailing phenomenon through a simple voltage parameter adjustment without requiring additional memory or complex correction circuitry.
4Reliability
If black level is shifted toward white side to suppress tailing phenomenon, then tailing is reduced, but image brightness may be affected
Solution Approach 1:
The patent applies partial action by shifting only the black level portion of the voltage range toward the white side, while maintaining the overall brightness through the white level. This selective adjustment suppresses the tailing phenomenon without significantly affecting the overall image brightness, as the white level and its corresponding voltage are preserved.
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
The solution effectively reduces the occurrence of the tailing phenomenon, enhances image brightness, and maintains contrast, preventing color shifts and ensuring clear image quality without the need for extensive memory or circuitry.
Implementation Method 1
When voltage is applied to picture element electrode 51 with common electrode 52 as a standard, the liquid crystal molecule 60 of liquid crystal material 53 changes from the state shown in FIG. 2A to the state shown in FIG. 2B, and the orientation of liquid crystal molecule 60 becomes a fixed orientation.
Implementation Method 2
The orientation of the liquid crystal molecule is controlled by the field generated by the difference in potential between these electrodes (hereinbelow, this field is referred to as the 'vertical field') and light is polarized.
Implementation Method 3
When picture elements are caused to display white, an electric field is produced by the difference in the potential of picture signals between adjacent picture elements, as shown in FIG. 1. This electric field is referred to as a 'horizontal field.' When liquid crystal molecules 60 between picture elements receive the influence of a horizontal field and assume an orientation that differs from the ideal, phenomena such as light leakage are brought about.
Data Source
AI summary
An image display apparatus includes: a panel (16a) that includes a plurality of picture elements that change transmittance of light according to picture levels; a detection unit (12) that detects, in one-image portions of the panel (16a), picture levels for each of the plurality of picture elements from picture signals that indicate the picture levels of each picture element; and a processor (18) that, based on the picture levels of one-image portions that were detected by the detection unit (12), adjusts the transmittance of light of the plurality of picture elements such that the image realized by the picture signal is brighter when a value that corresponds to brightness is greater than a predetermined threshold value.