GLT and Luminous join forces to deliver edge-lighting for LCD TVs

09 Jun 2006

A 24-inch working prototype of an edge-lit LCD TV was demonstrated by GLT at the Society for Information Display (SID) conference & exhibition this week, as Tim Whitaker reports.

Global Lighting Technologies (GLT), a developer of LCD backlighting technology, has formed a partnership with LED manufacturer Luminus Devices to produce modular edge-lighting assemblies for large-screen LCD TVs. The assemblies combine high-brightness LED sources with micro-optical extraction techniques, and significantly reduce the number of LEDs needed to light an LCD panel.

Luminus emerged from stealth mode at the start of 2006, when several TV manufacturers unveiled rear-projection TVs exploiting Luminus' PhlatLight™ LED chipsets. Luminus' PhlatLight technology exploits photonic lattices to achieve very high-brightness light emitters, and has so far mainly been exploited in microdisplay applications.

GLT has now combined these high-brightness chipsets its MicroLens pixel-based light extraction technology, which is based on micro-optical elements molded directly into a light guide. The elements are optimized to deliver more collimated light, which increases the efficiency of the optical system.

This combination of technologies enables large-size LCD panels to be edge-lit, as opposed to conventional direct backlighting. This dramatically reduces the LED count, and offers simplified color and thermal management than conventional LED-based backlighting solutions.

"The breakthrough for this application is that we're using the PhlatLight chipsets to edge-light, not backlight, the panels," said David DeAgazio, Director of Sales Worldwide at GLT. "These edge-lit units are modular and scalable to screen sizes of 50-inches and larger. We are using a handful of PhlatLight chipsets instead of hundreds or thousands of LEDs. This is not possible with any other type of LED."

Small-sized color LCD displays, ranging in size from those used in mobile phone handsets to the 11.1-inch screen in some Sony Vaio laptops, already use white LEDs arranged on the edges of the display. However, at a size of around 20 inches it becomes necessary to use direct backlighting to achieve the necessary uniformity and brightness.

Luminus and GLT claim that a 32-inch LCD TV that once required hundreds of LEDs in the backlight can now be edge-lit with less than 12 PhlatLight chipsets - each containing a single red, green and blue die - for optimal brightness, color, and significantly reduced thickness. The resulting LCD TVs are less than 5 mm thick in production units), offer a brightness of 8500 cd/m² at the backlight surface, require only passive thermal management, and lead to significantly lower production costs.

The companies say that the benefits of the new edge-lighting assemblies increase with panel size, and that their strategy will be to achieve edge-lighting of LCD TVs measuring 40 inches and larger. Future developments are also expected to reduce the number of chipsets even further.