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Even if the next LCD you buy has pretty much the same characteristics as the last LCD you bought, a change is likely to have occurred behind the scenes. In display sizes below about 15 inches, the tried-and-true cold-cathode fluorescent lamp (CCFL) lighting system for the LCD is rapidly being replaced by lightemitting diodes.
There are a number of reasons for the transition - which is analogous to the transistor's displacement of the vacuum tube-and it has a number of ramifications. At the foundation of the change is that recent brightness improvements in white LEDs have made them feasible for back- or edgelighting an LCD that's bigger than a 4- to 6-inch PDA-class display. Dropping prices are also a factor.
"CCFL will eventually go the way of the dinosaur," said Richard McKay, managing director at display VAR Apollo Display Systems (Ronkonkoma, N.Y.), and a number of other sources agreed.
"LEDs will quickly take over LCD backlighting in sizes of 10 inches and above," said Stewart Hough, vice president for business development at Lynk Labs (Elgin, IU.), a specialist in LED driver technology. Pretty much all the CCFL backlight suppliers, he said, "now also have LED backlights."
Environmental factors
One major reason for the ascent of LED backlights and edgelights is the European Union's RoHS initiative, which has sought to purge lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl and polybrominated diphenyl ether from in electronic equipment sold in EU member countries since July 1,2006.
Mercury is a prominent component of CCFL tubes and other types of fluorescent lighting. Although vendors have reduced mercury levels in their fluorescent tubes, with mercury-free versions under discussion, additional benefits of the LCD...