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LEDs are a solid state light source that have extraordinarily long lifetimes, and do not use mercury or other environmentally hazardous chemicals that are found in the fluorescent lamps traditionally used as backlights for LCD panels in devices such as computer monitors, notebook displays, and HDTVs. In addition, LED backlights provide better color performance, resulting in better image quality. And LCD HDTV makers are rapidly shifting to LED backlights for their products. At CES 2010, Toshiba announced 10 new TV lines, seven of which rely on LED backlights. Five of the new series of LCD TVs introduced by Sharp at the show have LED backlights. Samsung has eight lines with LED backlights. LG announced six of 11 new lines with LED backlights. LEDs also make it possible to create much thinner sets, which appeal to consumers and also save weight and shipping volume. The thinnest sets use “edge-lighting” that places the LEDs along the sides of the LCD panels, using complex light guides to deliver the light to the panel. LG showed models that were less than an inch thick, but still had the LEDs behind the panel, which enables local dimming: a feature that can increase image contrast and lower power consumption. The broader use of LEDs will improve image quality, and the increased competition should mean that the price premiums charged for LED models will start to come down. (The increased demand for LEDs should result in competition and greater economies in the LED component industry, which should also help lower prices.) If there’s a down side to the development, it is the fact that more companies have chosen to follow Samsung’s lead, calling these models “LED TVs”. Too many consumers think that these are not LCD TVs, but rather have the image made by LEDs. (I also suspect that more than a few think that these are the OLED TVs that so many people are hungry to see.) So we have to keep repeating that these are just LCD TVs with a different type of backlight. Spread the word.
Posted by Alfred Poor, January 12, 2010 5:00 AM
Reader Commentary You wrote "LEDs are a solid state light source that have extraordinarily long lifetimes, and do not use mercury or other environmentally hazardous chemicals that are found in the fluorescent lamps traditionally used as backlights for LCD panels in devices such as computer monitors, notebook displays, and HDTVs. " Actually, LEDs are made of various compounds including gallium arsenide, gallium aluminum arsenide, gallium aluminum arsenide nitride, etc. The arsenide is Arsenic in compound. Some people might classify this as hazardous, although the arsenic in these doesn't readily transfer to the environment as mercury does.... lmarks: you're certainly correct. The difference is that the amount of arsenic in an LED -- or all the LEDs ina single TV -- is tiny compared with the amount of mercury used by an equivalent fluorescent backlight. And, as you point out, it is much less likely to find its way back into the environment in any significant way. Alfred... Now if they'd just come up with a retrofit that would allow the use of LEDs to replace original backlights for LCDs. Or have they?... Very few LCD panels make provisions for replacement of backlights, let alone retrofits. After the five years or so that it would take for a computer monitor backlight to dim appreciably, it would no doubt be cheaper and easier to replace the entire display than try to find a compatible fluorescent backlight. Replacing the backlight with LEDs would require new light guides, diffusers, light recovery layers, as well as major changes to the controller circuitry (which probably exists on a monolithic board that does not change components easily). And when you're done, it's possible that the color filters used on the LCD panel will not be optimized for the new LED light source. Yes, you can drop a classic Ford 289 V8 into a VW Beetle chassis, but it's not easy and probably not worth the expense. A similar case would apply to LCD displays. Alfred... More from Alfred Poor
More in Category: General Interest
About Alfred PoorAlfred Poor is a well-known display industry expert, who writes the daily HDTV Almanac. He wrote for PC Magazine for more than 20 years, and now is focusing on the home entertainment and home networking markets. |
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