LED backlight features

Compared with traditional CCFL backlight, the most significant advantage of LED backlight is that it can provide unprecedented color reproduction. By selecting LEDs with appropriate wavelengths and matching color films, the color reproduction range of LED backlight can reach 105% or even more than 120% of the NTSC standard. In comparison, traditional CRT TVs are only about 85%, and CCFL backlit LCD TVs are only 65-75%.

In the display industry where picture quality is life, having more vivid colors will be an overwhelming advantage. According to traditional concepts, LCD monitors, especially LCD TVs, have been criticized for their inferior colors and response speeds to CRTs or even PDPs. However, once LED backlights are adopted, they will overwhelm their main competitors, CRTs and PDPs, in terms of color. In addition, LED backlights can solve the tailing phenomenon caused by slow response speed to a certain extent. LEDs can start instantly, and the response speed reaches the nanosecond level, which is a million times that of CCFL. With such a fast-responding backlight source, LCD display devices can eliminate the tailing blur phenomenon that occurs when ordinary LCDs display fast-moving objects through instant backlight flashing technology, and the picture quality will be significantly improved. More importantly, by using the instantaneous switching of different monochromatic lamps in the LED backlight, field sequential color display can be achieved, so that the color filter that accounts for about 30% of the cost of LCD monitors can be completely removed.

In terms of service life, LED can reach more than 100,000 hours, which is twice that of the best CCFL. Even if you watch TV for 8 hours a day, you can watch TV for more than 30 years. Unlike CCFL, which contains deadly mercury vapor, LED is a semiconductor solid light source and is a completely ideal green light source. Since the European Union has begun to fully restrict the entry of electronic products containing harmful elements such as mercury in July 2006, it has created an excellent opportunity for LCD products using LED backlights to replace CCFL and go global during this period. Cold cathode fluorescent tubes require high-voltage AC drive, and the power transformer and rectifier group is complex, while the auxiliary optical components required by LEDs can be made very simple, do not require a lot of space, and the body can be made very light and thin, and the weight is also reduced a lot. Take Sony's TX series of notebook computers as an example. Compared with the VAIO T series using cold cathode fluorescent tube LCDs, the thickness has dropped from 9mm to 4.5mm, and the weight has been reduced by 26%. The LCD TV with six primary color LED backlight released by Mitsubishi Electric at SID2005 is only 5 cm thick! In addition, LED can start up quickly in an environment below -40 ℃, while CCFL can no longer work normally in such an environment. The good adaptability to the environment makes LED backlit LCD displays favored by military, aviation, exploration and other fields.

Of course, there are some problems with LED backlights. Currently, the price of LED backlights is about 3-5 times that of similar CCFL backlights. Such a difference is enough to deter most manufacturers and users. The second is the heat dissipation problem. LED backlights will generate a lot of heat when working, especially for large-size LCD TVs. Therefore, some forced heat dissipation measures, such as fans, are often required. In addition, there is the problem of luminous efficiency. The highest luminous efficiency of commercial LEDs is about 30-35lm/W, which is only about half of that of CCFL (the luminous efficiency of CCFL is about 60-70 lm/W), so LEDs need more power consumption to achieve the same brightness as CCFL.

However, the above problems are expected to be resolved in a relatively short period of time.