There is another new HDTV on the block. It is called an LED HDTV. LED may seem like a new technology, but is is not. It is just improved engineering of existing LCD technology. LED refers to the way the HDTV is back lit. It is not a new screen technology. The screen technology of and LED television is LCD as opposed to Plasma HDTV.

LCD stands for Liquid Crystal Display. LCD screens are made from lighter weight liquid crystal panels that use less power than other technologies with no risk of burn-in. Some screens have automatically adjustable back lighting. The back lighting changes to match the ambient light in the room. Traditionally, this back lighting has been with flourescent technology.

LCD monitors reproduce colors by blocking out particular color wavelengths from the spectrum of white light provided by the back light until the desired color is produced. The intensity of the light which passes through the liquid-crystal matrix enables LCD televisions to display bright color images.

The light is typically provided by cold cathode fluorescent lamps behind the screen. The lifespan of these lamps vary in LCD televisions. It depends on transient voltage surges, humidity and temperature.

Variable back lighting is a way for LCD TV sets to meet new energy efficiency regulations. Variable lighting also improves the perceived contrast range. However, the fluorescent lamps are limited in how much they can be dimmed causing erratic operation and shortened life. Another little known fact is that the backlight changes colors slightly when it ages. This throw off the white balance of the entire TV.

Manufacturers are now using high-efficiency white LEDs for back lighting to overcome these issues. This type of HDTV is referred to as an LED TV. There are two variations of LED back lighting: edge lit and local dimming.

In edge lit TVs, the LEDs are placed around the edge of the TV. The advantage to this is that is allows the manufacturer to make very thing televisions. For local dimming the LEDs are localized behind the screen of the TV. Local dimming provides a higher contrast than edge lit screens. On the other hand edge lit TVs are less expensive than local dimming LED TVs.

Manufactures are now replacing their line of fluorescent back lit televisions with LED back lit televisions. The LED televisions have better contrast ratios and better efficiency over the older style back lit designs. Life expectancy of the television should also improve.