PhlatLight LEDs illuminate new Samsung TVs
Consumer electronics colossus Samsung has released six new rear-projection TVs that are illuminated with red, green and blue LEDs made by the US chip firm Luminus Devices.
The 50 inch, 56 inch and 61 inch TVs are in US stores now and, unlike previous attempts by Sony to introduce LED backlights into TVs, Samsung appears to be having great success with the technology.
The Korean company, which is ranked number one in world market share for TV sales by analysts at DisplaySearch, ultimately has plans to introduce LED lighting into all of its large-area display screens. It says that the first of its LED-based TVs, launched last year, were so well received that it decided to expand the range for 2007.
Whereas Sony s LED-based Qualia TVs were extremely costly, Samsung s are much more affordable and are priced at around $2500.
LED chips improve on-screen color reproduction compared with traditional lighting technologies, largely because of the extra brightness provided in the red part of the spectrum.
Combined with digital light processor (DLP) chipsets from Texas Instruments, the PhlatLight chips produce sequential red, blue and green light at a cycle rate of 2.9 kHz - 48 times faster than conventional TV frame rates.
The LEDs used in the PhlatLight chipsets incorporate textured patterns that increase light extraction efficiency. Luminus manufactures the chips at its semiconductor facility in Boston, close to the Massachusetts Institute of Technology (MIT) where the novel approach was pioneered.
The new Samsung TVs feature the PT120 LED chipset, which has an emitting area of 12 mm2. The red chip emits 660 lumens, the green 1550 lumens, and the blue 250 lumens.
Because they emit such a lot of light, the photonic lattice chips cut down the overall complexity of more conventional LED backlighting systems that require hundreds of individual emitters to illuminate a large screen.
Although Luminus has not revealed too much about its technology, early structures developed at MIT were based on GaAs substrates and featured six-period GaAs/AlxOy distributed Bragg reflectors.
The top of those structures featured a photonic crystal, which sat on top of an InGaP cladding layer and an InGaAs quantum well layer. The novel design, says Luminus, yields both high extraction efficiency and a collimated beam of light, which helps with device packaging.
Luminus has also been sampling a higher-power chipset, the PT180, which emits a total of 2600 lumens and features four chip die per color.
Having made good penetration in the rear-projection TV space, the company is now planning to attack the much bigger market for liquid-crystal display TVs. Working with optics specialist Global Lighting Technologies, Luminus has backlight units for 46 inch and 52 inch LCD TVs in development at the moment.
