Take time to direct type LED backlight TV architecture for large-scale development

Backlight technology large size LCD screen is divided into side type (or edge) and direct type (or matrix) in two ways. Due to its low cost and simple architecture, the side down backlight occupies more than 90% of the large LCD Backlight Market share. At present, the domestic first-line brands such as Hisense, Haier, Konka, SKYWORTH, TCL, Changhong and so on, are committed to the development of LED backlight side of the TV. However, due to the direct type architecture has more power, cooling, simple image contrast, better local dimming and other advantages, on the use of direct type (or matrix) to discuss the LED backlight structure also began to rise in the industry.

According to Displaybank analysis, the global LED market will grow at an annual rate of 19% growth. One of the most important driving force is from the large size LCD screen, including LCD and LED TV backlight market. There is no doubt that if the LED backlight architecture from the current mainstream of the scale of the edge of the straight down (or matrix), the industry's demand for LED will surge.

The main driving force for the growth of the global LED market comes from the large LCD screen

At present, the Japanese Sharp company has been pushing straight down concept, and develop a LED+LENS solution. However, because only the high-end models are used straight down technology, the major domestic manufacturers have not been a positive response, so the technology is not large shipments of products.

REFOND optelectronics Limited by Share Ltd TV Project Manager Yang Zhiyong analysis, there are three main reasons: one is the cost, direct cost is now slightly above the side; two is the volume, compared with the side type, the thickness of TV direct type increased; three is a technology problem, direct type (FULL LED &LENS) the production process is under the complicated side.

Taking into account the possibility of a light guide plate and the lower part of the light with the unique features of the light, is actively developing and reserves this technology (COB, Full LED, Lens+LED model). Yang Zhiyong said that the current Ruifeng optoelectronics has been working with Konka, SKYWORTH, TCL joint development of straight down projects.

Outlook this year, direct backlight technology will remain vulnerable. The Fairchild Korea power conversion division vice president Zhao Donghui said, now the direct type LED backlight (matrix) accounted for LED TV overall yield of less than 5%, the proportion of direct type LED backlight is not expected to increase this year, because the LED in terms of price adjustment is slow, while the LCD TV manufacturers are focus on reducing the LED backlight module (BLU Back Light Unit TV) the cost to replace the cold cathode fluorescent lamp (CCFL) backlight LCD TV.

TI China district power products business development engineer Wu Tao estimates, in 2012 the market will develop more types of direct type backlight technology products. Therefore, the phenomenon of large-scale use of straight down LED backlight TV phenomenon will occur at least two years later.

While in the side type backlight technology, with Hisense, Haier, to SKYWORTH, Konka, TCL, Changhong and other domestic brands manufacturers, side type backlight structure LED TV development getting better. Because of the brightness of LED, single lamp price is greatly reduced, the backlight is also from the previous multilateral rapid transition to narrow unilateral now, in the overall cost to CCFL. At present, the number of major manufacturers to develop LED TV project is also significantly redundant CCFL.

Core Kay Electronic Technology Co., Ltd. CEO Kin Shum believes that the main reason for the low cost of the lower side of the backlight can be connected in a LED string dozens or even more LED lights, thereby reducing the cost of the system. Therefore, the high voltage LED driver chip will become the main driver of the side of the backlight.

Core Kay electronic technology CEO Kin Shum introduction, due to the leading high pressure process, core Kay can provide a series of high voltage LED driver chip, can drive up to 60 LED. As a result, our competitors LED driver chip can only drive a single string of 10 to 15 LED, so the use of our LED driver chip will greatly reduce the cost of the system. He stressed that the high system cost is a bottleneck for faster development of the LED market, so the production cost decreased along with the LED itself, the unique core Kay LED driver chip will have no small cost competitiveness.

LED backlight drive IC number

The industry does not currently have a specific size of the TV standard LED chip requirements. In fact, the number of different LED TV backlight scheme used by LED is not the same, depending on its forward current (Forward Current) and Intensity (Luminous) and other LED characteristics. Wu Tao estimates that about 200 to 300 LED chips can meet the needs of 42 inches or 47 inches LED tv. And Zhao Donghui believes that many TV manufacturers in the 42-49 inch LED backlit TV only need to use 70~140 LED chip.

The number of LED drives depends on the lamp bar configuration, Zhao Donghui said, most TV manufacturers in the system using 1-4 LED driver IC. Wu Tao from TI has a different opinion, we usually choose to use a LED driver for all lights. Although 2 will be used at the same time, but will not use the same TV in the 3 LED drive. Said Wu Tao.

There are great differences in the configuration of the LED lamps in different scenarios, and the customer may have different considerations about the cost, the dimming requirement or the maximum luminous intensity. Wu Tao, one of the common configuration for the 4 string LED, each string using 50 LED.

In terms of the choice of the LED power level, according to Yang Zhiyong, Limited by Share Ltd project manager, LED, introduced the side of the 32 TV above the structure of the main power of the LED 0.4-0.8W