LCD backlight technology development speed, CCFL and solid state lighting competition

Author: PAUL SEMENZA

Because of the long-term position in second, LCD backlight in the display industry is gaining more and more attention. With the 40 inch or larger size thin film transistor liquid crystal display (TFT-LCD) production soared, the traditional cold cathode fluorescent lamp (Cold Cathode Fluorescent tubes) performance and cost limitations become more and more obvious. But at this time, the solid state light source (LED and laser) and CCFL in favor of continuous innovation is accelerating.

At the 2007 International Conference on information display (SID) held in Losangeles in May (International Symposium, seminars and exhibitions), a number of suppliers to demonstrate the LED backlight program. Luminus Devices and Global Technologies Inc. (GLT) demonstrated a 52 Inch edge lighting backlight unit prototype, which uses Luminus's PhlatLight LED and GLT MicroLens optical waveguide. Two, the company said it was so far demonstrated the largest edge lighting backlight unit. Luminus PhlatLight is a LED array, which uses patented photonic crystal (photonic lattice) technology to enhance the efficiency of light extraction (light extraction), PhlatLight technology won the silver medal in SID display.

Germany's OSRAM Opto Semiconductors display a 70 inch diagonal LCD-TV backlight scheme based on its Golden Dragon Argus LED cluster, which uses indium gallium technology. The device is packaged into a "diamond" consisting of 2 green, one blue and one red LED". The diamond can be any combination of horizontal and vertical, can be extended into different sizes.

OSRAM said its Golden Dragon Argus products have several advantages, including the ability of light emitting efficiency, wide range of bright and mixed red, green and blue better produce white light (with a single tone control), which is beyond the standard of NTSC. Other advantages include the package height of only 4 mm, switching time less than 100 ns, without the need for active cooling equipment and reduced power consumption - compared with the CCFL scheme, the 32 inch backlight power consumption reduced by 20%! Hazardous substances restrictions (RoHS). Also after the vibration and shock detection, life of more than 50000 hours. In fact, LED is not currently available only solid state light source, Novalux shows a red, green and blue semiconductor laser 32 inch LCD-TV backlight program. The scheme is not specifically optimized in which the laser is simply coupled to the light management film in the standard backlight, but they show a good wide color gamut.

These solid-state light source will have to compete with the standard CCFL, they have improved in the color gamut, in terms of R & D has evolved, such as external electrode fluorescent lamp (EEFL) and flat fluorescent lamp (FFL) has entered mass production.

The development of advanced light source technology is not confined to LED - Novalux and Luminus backlight also took aim at the rear projection TV micro display based on (RPTV) and its goal is to replace the high intensity discharge lamps, such as PHILPS UHP, and the color wheel and the dichroic mirror. Here, there are other competing light sources, including the Luxim LiFi, which is a microwave cavity instead of a high voltage arc wide spectrum halogen lamps, can extend the life of the lamp.

Corelle has spent some time exploring its LCD substrate technology in order to highlight the development of its semiconductor laser technology, which works in the challenging spectrum of laser semiconductors - green light. The development of semiconductor laser technology has opened new opportunities for micro projector, SID exhibits several schemes, please refer to Jennifer Colegrove entitled "SID2007" light emerging display technology reports.

Encouraged by the availability of these light sources, coupled with the frustration of competition in the RPTV market, some of the company's former RPTV focused companies are re planning their role in this emerging market share.

Source: Electronic Engineering album