Replacing CCFL is not a dream LED backlight technology has obvious advantages

In recent years, the discussion on "LED backlight can replace CCFL" has been continued, in fact as early as 2007, in Japan's High Tech Expo, SONY unveiled the LED backlight technology 70 inch LCD TV, and hopes to further promote the new type of LED backlight technology. Then, Samsung also released its 70 inch LCD TV with LED backlight source, Samsung's series of products in China is even embedded in the symbol of the clouds, quite eye-catching.

So many global LCD TV manufacturers have begun to focus on the development of this new type of backlight technology, hope in the future can be more competitive on the market to win the upper hand. But in the early years, LCD TVs use LED backlight panel after the cost is even more than 3 times the CCFL, which has become one of the factors hindering its further growth.

Still have good news, originally LED backlight module BLU the obvious advantage of cost though it is higher than that of traditional CCFL, between the two gap is gradually narrowing, including iSuppli, DisplaySearch, a research company, many industry experts predict that in 2010, about 30% of the LCD TV the LED back light source, then the cost of LED will be equivalent with CCFL or a bright prospect.

The defect CCFL backlight

First, we still have to look at the defects of the traditional CCFL backlight where, or from the liquid crystal to talk about it. As we know, is a kind of liquid crystal between liquid and crystal material, its principle is shown to change the molecular arrangement through different voltage applied to the liquid crystal, so as to control the amount of light through, in order to show the variety of image. The liquid crystal itself does not emit light, it is only through the control of the light or not, so all LCD panels need backlight source to provide lighting.

At present, the majority of backlight LCD TV or CCFL, cold cathode fluorescent lamp that is usually said. This kind of light source is not a plane light source. In order to realize the uniform luminance output of the backlight, we also need many auxiliary devices such as diffuser, light guide plate, reflecting plate and so on.

Even so, to get the brightness of the output is still like CRT even difficult, most in the liquid crystal display all white or all black screen, differences between the edges and the center of the screen brightness is very obvious. In addition, in the image display effect, compared with CRT, the color gamut performance of CCFL is obviously insufficient.

In the industry, we have been with US National Television Systems Committee published NTSC standard video equipment color reproduction, this index refers to the entire gamut, display device in color display, color saturation, for most of the traditional LCD panel, can cover the color range of only NTSC the standard 65% ~ 75%, the specific performance in green, yellow and red color regions, the difference with the standard value.

The structure principle of CCFL backlight LCD

CCFL belongs to the tubular light will emit light evenly spread to every region of the panel requires auxiliary component rather complex, in addition to the brightness uniformity enough outside, the structure of CCFL is very complicated, the application of LCD TV screen and its thickness are difficult to control, and with the panel you must use a plurality of light source increases. In addition, CCFL also has the disadvantages of low luminous efficiency, high discharge voltage, low discharge characteristics at low temperature, long time to reach stable gray time, and CCFL contains harmful metals, which do not meet the requirements of environmental protection.

Of course,, one of the biggest problems in the application of CCFL as LCD panel backlight facing or short life. Most of the CCFL backlight in 2 to 3 years after the brightness decline is very obvious, many LCD TV screen will appear yellow, dark phenomenon in use after a few years, this is the use of CCFL attenuation for a shorter period caused by defects. To this field, consumers in addition to the replacement of LCD backlight, there is no other solution.

Introduced above, the CCFL backlight must optical device including the diffuser plate and the reflecting plate complex, so the liquid crystal panel volume cannot be further reduced, and the current trend of ultra-thin LCD TV is inconsistent. In terms of power consumption, LCD TV with CCFL backlight is a big flaw, someone to do the experiment, a 42 inch LCD TV often need to consume 250W even more power, and the current construction of a conservation minded society concept is not taken.

In order to solve the CCFL backlight LCD TV to bring the "pain", many LCD TV manufacturers all these years in search of a more liquid crystal backlight excellent as a substitute, and LED backlight technology came into being. Introduction of LED backlight

In LED, also known as light emitting diodes, more popular, it is the carrier injection in the PN junction, the minority carrier carrier and the majority after the release of energy, in the form of light, so as to realize electroluminescence. It is not a new thing, these years have been used in outdoor advertising, signs, lights, car headlights, electrical appliances, such as backlight backlight.

LED significant feature is the high photoelectric conversion efficiency, high color saturation, small volume, shock resistance, impact resistance, do not contain toxic substances, low voltage power supply to the human body, safety, long service life etc..