The wide application of large screen LED backlight needs to solve the two major problems of high cost and matrix design uncertainty

As new technologies continue to emerge, the competition between liquid crystal display (LCD) and plasma display panel (PDP) is becoming more and more intense. As a result, the price of products decreases with the increase of the optional technology. Because the market is close to saturation, and now seems to be a major change in time, many people think that it is the LED BLU (backlight module) as the next generation of display applications debut opportunity.

LED BLU has been sought after because of the advanced features that are significantly different from those of the cold cathode fluorescent tube (CCFL) BLU. LED BLU has the advantages of high color gamut, high contrast, no mercury reflective material, RoHS environmental protection standards, low voltage and fast response. In addition to evaluating the overall advantages of LED, it is time for designers to learn more about LED BLU power solutions.

High cost is the only obstacle to creating a new era of display applications. Even if the LED BLU shows superior visual performance, its application is limited by the high cost of the relevant. LED BLU for mobile devices with small screens have been popular for several years, but the manufacturers continue to strive to overcome the price barriers under the impetus of this technology have begun to gradually shift to medium size display applications, such as digital photo frame, car navigation equipment, notebook computer and monitor. In addition, many mainstream TV manufacturers have also begun to try to launch a number of new products to create LED BLU TV market, although they can not meet the market requirements of low-cost targets.

In order to use LED BLU to achieve a larger display, it must be able to meet the higher requirements of the driver IC. The LED BLU circuit for large screen TVs must take into account at least two functions: to obtain a better contrast of the local dimming function and to reduce the motion blurred image required for pulse drive. And these two functions is the LED BLU of the advantages of the two. LED BLU driver IC can complete dynamic backlight lighting control, which is different from other LED lighting technology advantage, especially for large screen applications. Small screen for mobile devices display or digital photo frame does not need to use local dimming technology or pulse drive, but also do not like the big screen as a very good visual display.

When designing LED BLU TV's dynamic control driver IC, it is important to carefully arrange the LED array, since the number of channels and the current and voltage levels of each channel are important in the IC specification.

However, the LED backlight module to obtain a wide range of market recognition, but also need to solve the two major problems, namely, the high cost of LED and LED matrix design uncertainties. It is believed that the RGB LED is much better than the white LED visual effect, especially in color gamut. Studies have shown that the human eye can hardly tell the difference between RGB LED and white light LED, because the human eye is most sensitive to the brightness of the first eye effect. RGB LED and white LED brightness is almost the same. White LED is much cheaper than RGB LED (but still more expensive than CCFL), therefore, for the rapid creation of new markets, TV manufacturers widely used white LED.

The result of this choice is to speed up the array design. In addition to the need to control each RGB color group, designers do not have to bother to consider local dimming. In addition, the use of white LED also reduces the number of other designers to make a headache.

The development of LED BLU is open innovation power IC market opportunities, such as with the DC/DC module, the input voltage is 24V or 40V SMPS requires at least 16~32 output channels (depending on the screen size), each channel requires at least 60mA current. This means that we expect the LED BLU market will be more changes, not only related to MOSFET, but also includes drive IC.

In the CCFL BLU market, there are only a few key patents IC manufacturers, so when there is a new competition to enter the market, there will be a serious conflict. But the LED BLU market does not exist in this law, because the main components can be converted into DC/DC system from the inverter. The most critical factor in the success of the LED BLU domain is the degree of optimization of the drive IC in order to provide customers with a specific system oriented IC. The LED BLU design concept is still likely to undergo change and improve the cost structure in different screen sizes.

Judging from the market size, many people in the face of "LED BLU will become the next backlighting solutions," the issue of caution. CCFL has been constantly innovating in terms of cost and performance, and active matrix organic light emitting diodes (AMOLED) are becoming a technology that makes LED obsolete. According to Displaybank's survey, the LED market is expected to occupy 40% of the share of the entire BLU market in 2010.

As many technical barriers are being eliminated by a number of market and technology leading companies, coupled with the emergence of new LED BLU prototype products, so the market will change. From a technical point of view, the LED drive IC market provides more opportunities than the CCFL inverter market, because the former relies on generic DC/DC technology, rather than a unique technology involving patent issues. Any power supply company, if you can achieve an ideal system applications, will become the market leader. Many power solutions experts to design the appropriate circuit, and provides a balanced IC powerful and precise, but the SMPS and DC/DC modules are integrated together in order to reduce the cost of the manufacturer's design concept is the ideal solution.

Author: Luke Chung
MCCC (mobile, computing, communications, consumer) market development manager
Fairchild Semiconductor