The Next "Dominant" HDTV Technology

LED Backlit LCD HDTVs, which is still in its infancy, is poised to dominate the high-end HDTV landscape going forward. At the 2008 IFA (Internationale Funkausstellung Berlin), which is the world’s largest consumer electronics trade show, the world’s leading manufacturers of HDTVs were introducing LED backlit HDTV. LED HDTVs that will be made available for consumer purchase will be pricey, as much as double the price of a very well equipped conventional LCD HDTV. Costs of LEDs have been dropping and will continue to drop as production of these sets increases. The technology behind LED lighting has also been progressing swiftly, which will help shorten the maturation period of LED based HDTVs. Eventually, the prices of these sets will drop to a level that is more palatable to more and more of us, so here is the background information to help you understand what this technology has to offer.

Close-up of an RGB LED Display Panel

LED, which stands for “light-emitting-diode”, is currently used in many different types of electronic devices including reader boards, calculators, Christmas lights, flashlights and even the light bars of some emergency vehicles. LED is a semiconductor, the first LED as we know it today dates back to the early 1960’s. Being a semiconductor like its cousin the computer processor, LED has had exponential advancements in light output and energy efficiency. Currently, LED will use about 30% less power to produce the same level of brightness as conventional florescent backlighting in an HDTV application. That energy savings number will continue to grow as time marches forward. LED lighting also possesses greater variability with regard to levels of brightness. This translates into increased gray scale gradation, and thus broadens the color depth it can reproduce in comparison to florescent backlighting. That’s not all. With the worldwide Green movement reaching critical mass, LED is a marketer’s dream as it lasts longer and gives off no radiation! And unlike florescent lighting, LED doesn’t contain any mercury. LED is also lightening fast; its ability to go from off to full brightness is somewhere in the neighbourhood of a 100 nanosecond, (a nanosecond is a billionth of a second, the millisecond used to measure HDTV response times is only a thousandth of a second). This kind of speed is obviously very useful with the active content HDTV.

LED and florescent backlit LCD HDTV will not differ significantly in overall design, since currently only the backlight of the LCD panel is different between the two. The size of LEDs which are now being produced, as small as 1.0 x 0.8 mm, will allow LED HDTV innovation to move in two different directions. HDTV manufacturers can utilize this backlighting technology to either place the LED backlight directly at the back of the panel, or they can align the LED along the edge of the panel.

Placing the LED at the back of the panel is the dominant method currently; LEDs are arranged in clusters and diffusers and used to ensure equalized lighting across the panel. The clusters are then used independently to brighten and/or darken areas on the screen (as needed by the scene), a technique call “localized dimming”. Upwards of a 1000 individual LEDs are currently in sets that place them directly behind the panel. As the price of the smaller and smaller LEDs drop, manufacturers can increase the count of LEDs in the sets, which will allow for greater precision in “localized dimming”. The increased ability to control the lighting in smaller areas of the screen will push the contrast level and color depth to new boundaries.

Placing the LEDs along the edge of the panel requires less LEDs; somewhere between 400 to 600 units. This method projects the light equally across the back of the panels with the aid of transmitters. The small size of LEDs and their placement along the edge of the LCD panel will allow HDTVs using this design to be very slim. The Sony ZX1 is a good example of this design; it is only 1 cm thick.

Right now price remains the biggest obstacle for LED HDTV to get significant market penetration, but recent history tells us that the prices will move in only one direction, down; and that downward movement will happen rather quickly.