Author: Ye Yang Zhe
First, the LED is applied to the backlight module to have the advantage of power saving
LED is applied to the backlight module as a light source, replacing the traditional cold cathode fluorescent lamp (CCFL), which not only has the advantages of light and power saving, small size, long life, low voltage and fast start-up, but also has the concept of environmental protection. For notebook computers, depending on the processor and size, the LCD panel consumes about one-third of the power consumption of the whole machine. Due to the low power consumption of the LED, the current use of the LED backlight NB can be extended by more than 1.5 hours; The thickness of the light guide plate with LED can be reduced from 2mm to 0.6mm (13.3å‹ product), the thickness of the screen can be reduced, and the weight of the whole machine will be reduced. Currently, each CCFL contains about 2mg of mercury, using LED as the light source. It can reduce the use of mercury. If you use RGB three colors to mix white light, you can provide better color saturation, and the color of the TV screen will be more vivid. The LED can be dynamically controlled in the area, and is extinguished in a black area in some areas to improve the contrast between light and dark, and at the same time save power. The LED reaction speed is fast, and the RGB three-color LED is used together with the fast-reacting liquid crystal, and the color filter method (Color Sequituonal) can be used to omit the use of the color filter.
LED luminous efficiency is only 20 ~ 40lm / W, not as good as CCLM's 80lm / W, while the cost is too high will be the biggest weakness of LED backlight module. A CCFL and a high-brightness LED are priced at around $1.50, but the number of LEDs used far exceeds that of the CCFL. In addition, LED heat dissipation is not good, and the large-size TV needs to be added with a heat-dissipating substrate, which will be another expense. The decay speed of each LED color is different, and the long-term use will have the problem of uneven color.
LCD upstream and downstream manufacturers have invested in LED factories, the main purpose is not to obtain LED production capacity but to consider technology. Technically, the LED package form, the wavelength of light, and the angle of light output all affect the backlight module. The panel manufacturer and the backlight module factory need to cooperate with LED manufacturers with close relationship to provide special specifications for various experiments and reliability tests. In addition, the panel factory and the backlight module factory have faced the shortage of CCFL. Mastering the material source has become an important issue for the panel factory and the backlight module factory. Investing in the LED factory to prevent the shortage of LED after heavy use, rather than focusing on short-term benefits.
Second, the impact and observation focus
Compared with CCFL, the use of LED as a backlight has the advantages of lightness, environmental protection, power saving, etc., but the cost is the biggest disadvantage. It is expected that the proportion of LED backlight used in notebook computers in 2007 will be less than 8%, the main reason In the competitive demand of other application fields, LEDs must be screened. How to replace the LEDs that do not meet the requirements of the backlight module will be the most important problem to be solved; at the same time, the TFT-LCD factory and the backlight module want to lower the price to reduce the cost, and the LED In the case of better gross margins for other applications, it is also crucial to be able to supply large quantities.
In 2006, notebook manufacturers only introduced 11.3" and 12.1" LED-backlit notebooks. Due to the small number of notebooks under 12.1 inches, LED backlights are regarded as high-end models, and the demand is limited. Since 2007, Apple, ASUS, DELL and other computer manufacturers will gradually launch 13.3 inches, and even larger 15.4 inches using LEDs as backlight products, but still positioned as high-end models, and are not willing to ship in large quantities. If the computer manufacturer's positioning of the product using the LED backlight module has not changed, it will not help the LED industry.
As for environmental protection, the European Union (European Union) implemented the Restriction of Hazardous Substances in Electrical and Electronic Equipment in July 2006. Although mercury is a regulated project, it is now subject to exclusion clauses. At present, CCFL can still continue to use, and the exclusion clause is not abolished, and it is impossible to forcibly exclude the use of CCFL.
In the field of LCD TVs, the cost of LED backlight modules is currently too high, almost three times that of CCFL backlight modules of the same size, and LCD TVs using LED backlights are more than 30% of the price of the same size models. The CCFL factory also has a wide color gamut fluorescent tube (Wide Colour Gamut-CCFL), NTSC can reach more than 92%, and currently the TV signal is only NTSC 82%, the effect of high color saturation is still limited, so SONY, Samsung are The LED backlight module LCD TV has been introduced, but the sales are not good, and the index of the declared technology is more than the actual profit.
At present, LEDs will still be used in small and medium sizes below 10 inches. Notebook computers still need to wait for computer manufacturers to launch mid-range products using LED backlight modules. The market can expand. As for TV, there are still costs and technical issues. Need to be resolved, I am afraid that in 2 to 3 years, it is still based on high-end products and even technical strength.
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