Analysis of advantages and disadvantages of LED applied in backlight module

A, LED applied to the backlight module has the advantage of saving electricity

The application of LED in the backlight module as the light source to replace the traditional cold cathode fluorescent lamp (CCFL), not only has light saving, small volume, long service life, low voltage, fast start benefits, at the same time with the concept of environmental protection. For notebook computer, as the processor of different size and power consumption, LCD panel accounted for about 1/3 of the whole machine, because the LED low power consumption, the current use of LED backlight NB which can be used to extend the time more than 1.5 hours; and the light guide plate thickness LED collocation can be reduced from 2mm to 0.6mm (13.3 inch products), the thickness of the screen can be thinned, the weight will be reduced; and the current of each CCFL contains about 2mg of mercury, using LED as the light source can reduce the use of mercury. If the use of RGB tricolor mixed white light, can provide a better color saturation, color TV screen will be more bright. LED can do regional dynamic control, in some areas when the black screen to improve the contrast of the light and shade, but also can save electricity. The LED reaction speed, the use of RGB tricolor LED with fast response liquid crystal, can use the color sequence method (Color Sequituonal), omitted the use of color filters.

LED luminous efficiency of only 20 ~ 40lm/W, not as good as CCFL 80lm/W, while the cost is too high will be the biggest weakness of the LED backlight module. A CCFL with a high brightness LED unit price of $1.5 up and down, but the number of LED is far more than CCFL. In addition, LED heat is not good, the use of large size TVs need to be coupled with the heat sink substrate, will be another spending. And each LED color attenuation speed is different, long-term use will be uneven color problem.

LCD upstream and downstream manufacturers have invested in LED plant, the main purpose is not to obtain the capacity of LED but to consider technology. The technology of light package, LED wavelength, light angle will influence the backlight module, backlight module and panel factory factory requires a close relationship with the LED vendor, experiment and reliability test of the products with special specifications. In addition, the panel and the backlight module factory factory has faced CCFL shortage, grasp the source material become an important issue for the panel factory and backlight module factory, LED factory investment to prevent a large number of LED after the use of shortage concerns, rather than focusing on short-term interests.

Two, impact and focus

Compared with CCFL, the use of LED as a backlight source has light, environmental protection, energy saving and so on merits, but the cost is the biggest disadvantage, is expected in 2007 notebook computer using LED backlight ratio of less than 8%, the main reason is that other applications in the field of competition needs, LED must be screened, how to meet the requirements without backlight module the LED will be the problem to be solved; at the same time in the TFT-LCD factory and the backlight module to lower prices in order to reduce costs, while the LED manufacturers in other applications in the field of gross margin good circumstances, whether a large supply has become a key.

2006 notebook computer manufacturers only launched LED backlight notebook computer 11.3 inch and 12.1 inch, 12.1 inch notebook computer as the number of the following is not much, at the same time will be regarded as high order LED backlight model, demand is limited; the beginning of 2007, apple, ASUS, DELL and other computer manufacturers will launch a 13.3 inch, or even more the 15.4 inch LED as backlight products, but still as high order models, and willing to a large number of shipments. If the computer manufacturer for the use of LED backlight module positioning has not changed, the LED industry will not be much help.

As for the aspect of environmental protection, the EU (European Union) in July 2006 the implementation of Hazardous Substances Directive RoHS to disable electronic products (The Restriction of Hazardous Substances in Electrical and Electronic Equipment), although the mercury control project, but now because of the exclusion clause, CCFL can continue to use, without exclusion clause before the abolition, and cannot be forced to exclude CCFL the use of.

In the field of LCD TV, the current cost of LED backlight module is too high, almost three times the size of the same CCFL backlight module, the use of LED backlight LCD TV is also more than the same size models more than 30% of the price. CCFL fluorescent lamp factory also has launched a wide gamut of (Wide Colour Gamut-CCFL), NTSC can reach more than 92%, while the present TV signal only NTSC 82%, high color saturation effect is still limited, so SONY, Samsung have launched the LED backlight module of LCD TV, but sales were poor indicators of significance that technology more than the actual profit.

At present, LED will continue to be used for small and medium size to 10 inches below the main, notebook computer still need to wait for the computer giant launched products using the LED backlight module in order, we can expand the market, TV is still the cost and technical problems to be solved, 2~3 years is probably to high order products, and technology the main show of strength.

Source: pcbtech