17-09-2012, 03:04 PM
THE LATEST TECHNOLOGY USED IN TELEVISION
THE LATEST TECHNOLOGY.doc (Size: 77 KB / Downloads: 41)
Abstract:
LED (Light Emitting Diode) TV is simply a LCD TVs with a different kind of backlighting. The screen remains the same but LEDs are used in place of Cold Cathode Fluorescent Lamps (CCFL) that are found in most LCD TVs
LED TV vs. LCD TV
LED TVs are technically a member of the LCD TV family. The display screen on a LED is a liquid crystal display the same as it is on any other LCD TV. The main difference between the two lies with different backlighting techniques which may change the picture quality characteristics dramatically.
Traditional LCDs have used some form of flourescent lighting from tubes to much more advanced flat arrays of lights. LED TVs use Light Emitting Diodes to light the LCD panel. Just as there are different styles of flourescent lights in traditional LCDs there are also different styles of LED backlighting.
PICTURE CONSIDERATIONS
CONTRAST / BLACK LEVELS
Traditional LCD televisions always have their backlight on when the TV is on. To create black or dark areas the screen must block the light by twisting the crystals to a closed position, often resulting in a lower contrast ratio and less detail in dark areas of the picture. This is a shortcoming in LCD technology that LED TVs with local dimming are attempting to correct. With the controlled backlighting the LEDs can be dimmed in dark areas of the picture to create darker blacks and better detail in dark scenes.
ADVANTAGE: Local dimming LED TV technology has a clear advantage in contrast and black levels.
COLOR ACCURACY
With white LED backlights the difference between the two technologies isn't very significant, but with RGB colored lights or a color wheel to affect the backlight color the LED TVs have an advantage in displaying realistic color.
ADVANTAGE: Without colored LEDs or another way to affect the backlight color these two technologies are nearly equal. With colored backlighting LED takes the advantage.
LED TV vs. Plasma
New LED TVs are changing the nature of how we view LCD TV in such a way that we must re-assess the advantages of LCD and Plasma over one another. All LED TVs contain an LCD display element (front panel). The difference of LED TVs lies in the backlight. Rather than the standard florescent backlighting systems of the past, LED TVs have LED bulbs (light emitting diode) as the backlight for the LCD panel. This has been a godsend for LCD TV manufacturers as it has allowed them to better compete in picture quality against plasma TV technology
DEPTH PERCEPTION
This is an interesting comparison due to the new 120Hz and 240Hz refresh rate technologies in LED TVs. These faster frame rate conversions were originally presented to reduce motion lag in LCD TVs. But they also do strange things to background information, especially from film based material. Overall, I think LED backlighting has helped LCD TVs a lot in this area. The backlight can be manipulated much easier than can the pixels of a plama.