The so-called LED refers to Light Emitting Diode, that is, we often say light-emitting diodes. In layman’s terms, he is the carrier injected in the PN junction. After the minority carrier and the majority carrier recombine, the energy is released. Represented in the form of light, so as to achieve electroluminescence. This product and its application are not only available now, and its application is everywhere in our real life, such as roadside billboards, various indicators on home appliances, and backlighting on mobile phone keyboards, etc. LED is used as the light source, so when we talk about LED, we should not feel fresh, so there is no need to explain this product and its working principle in detail, but its application in display products In other words, it should be counted as an emerging technology product.
Due to some inherent shortcomings of CCFL (Cold Cathode Fluorescent Lamps) backlight technology and products on traditional LCD display devices, such as narrow color gamut, low energy utilization, high power consumption and short life, etc., people have been looking for With its alternative technologies and products, LED backlight technology products have been included in people’s choices in this process. From the principle of light emission, LED is made of several layers of very thin doped semiconductor materials, one layer has excessive electrons, and the other layer lacks electrons to form positively charged “holes”, working current Through the combination of electrons and holes, the excess energy is released in the form of light radiation. LED is based on this principle to realize the conversion of electro-optic, and according to the different physical properties of semiconductor materials, LED can emit from ultraviolet to infrared Lights of different colors under different spectrums, especially the technical problem that LEDs cannot emit white light, have laid a fundamental foundation for the application of LEDs in the display field.
The main purpose of using LED as the backlight of the LCD TV is to improve the picture quality, especially in the color saturation, the display screen of the LED backlight technology can obtain a wide enough color gamut to make up for the shortcomings of the lack of the number of colors displayed by the liquid crystal display device, so that It can meet or even exceed the requirements of Adobe RGB and NTSC color standards, and can reach more than 100% of NTSC ratio. Among them, Sony introduced LCD TV panels with LED backlighting, with special emphasis on bright red and dark green performance, which can display more realistic than the previous methods. s color. At the same time, because of the planar light source characteristics of the LED, the LED backlight can also realize the color and chromaticity adjustment function of the sub-area that CCFL can not match, so as to achieve more accurate color reproduction, to meet the needs of print publishing and graphic design work, screen The dynamic adjustment can make the brightness and contrast can be dynamically corrected when displaying different pictures to achieve better picture quality.
In addition, the advantage of LED as a backlight is that it can replace the use of color filters. Three-color RGB LEDs use color sequential technology, using the characteristics of human vision to achieve full color effect, so they can replace color filters. Of course, this must be achieved with the response speed of the liquid crystal. However, to reach this level, there are still many difficulties that must be overcome. The remarkable features of LED are high photoelectric conversion rate, high color saturation, small size, vibration resistance, no toxic substances, low voltage power supply, safety to human body, and long life.
However, the LED backlight module is not without its shortcomings. The problem of power consumption is still an important issue that the LED backlight module must overcome. As more LEDs are used, in addition to the increase in power consumption, it also causes a problem of increased temperature. Therefore, cooling systems and sensors must also be added to solve this problem. Therefore, the thickness is thicker than that of CCFL backlight products. .
Although LED backlight technology has many advantages, it also has unavoidable difficulties in popularization and application. First of all, products using this new technology have no advantage in terms of price. Furthermore, LED technology is in the hands of a few manufacturers. Difficulties caused by its popularization, and finally the reason for the technology itself, LED backlight technology is not very good in luminous efficiency, current control and heat dissipation, from a long-term trend, LED backlight technology as an alternative The existence of technology products will surely spread slowly, and according to related industry expectations, this large-scale application should be in 2008. Of course, with the rapid development of new panel technologies of Samsung and LG, it may also be applied in large areas in advance.