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The hottest view from CCFL to LED is the backlight

2022-10-03

Detail

From CCFL to LED, we can see the innovation of human-machine interface backlight module technology

ccfl. The widely used human-machine interface backlight module technology

backlight module is one of the key components of LCD panel. Because the LCD itself does not emit light, the function of backlight module is to supply sufficient brightness and evenly distributed light sources, so that the LCD panel can display images normally. At present, in the field of man-machine interface, CCFL (cold cathode fluorescent lamps) backlight module is the technology adopted by most manufacturers

ccfl is a low-pressure mercury discharge lamp, which is coated with a layer of phosphor on the inner wall of the glass tube, and sealed with a small amount of inactive gas and a small amount of mercury inside the fluorescent lamp. The mercury atom is impacted by electrons in the discharge to produce ultraviolet light, which is transformed into visible light through the phosphor. When the power supply is added and the discharge begins, high voltage is directly added from both ends to make the mercury electrons and gas atoms in the tube collide with each other to produce ultraviolet light, which is converted into visible light by touching the phosphor on the tube wall. Because adding mercury into the cathode tube can get quite good luminous brightness and efficiency, in addition to portable small-size panels, including liquid crystal displays and liquid crystal TVs, at present, LCD panels mostly use mercury discharge cold cathode fluorescent tubes (CCFL) as backlight sources

led, a new generation of backlight module technology leading CCFL

but due to the addition of mercury, the current cathode fluorescent tubes are also facing many technical difficulties and problems that must be solved: blackening, dark start, low-temperature start, environmental protection, etc. Especially with the implementation of EU ROHS regulations, from July 1st, 2006, the import of elements or application products containing lead, cadmium, mercury, hexavalent chromium and brominated plastics, which are viscoelastic plastic flame retardants, has been controlled, and LED backlight module technology has entered the vision of the majority of scientific researchers! LED (lighting emitting diode) is a semiconductor solid-state light-emitting device. It is a display screen that uses solid semiconductor chips as light-emitting materials and emits excess energy through carrier recombination in semiconductors to cause photon emission, which is used to display text, graphics, images, animation, market, video, video signals and other information

The heart of the LED is a semiconductor chip. One end of the chip is attached to a bracket, one end is a negative pole, and the other end is connected to the positive pole of the power supply, so that the whole chip is encapsulated by epoxy resin. The semiconductor chip is composed of two parts, one is a p-type semiconductor, in which holes dominate, and the other is an n-type semiconductor, mainly electrons. But when these two semiconductors are connected, a p-n junction is formed between them. When the current acts on the chip through the wire, the electrons will be pushed to the P area, where the electrons and holes compound, and then they will emit energy in the form of photons. This is the principle of LED light-emitting

led, the future development trend of human-machine interface backlight module technology

compared with traditional light-emitting sources and CCFL, LED is known as the fourth generation lighting source or green light source. Some economically developed countries in the world have launched a fierce technical competition around the development of LED. The United States has invested $500million since 2000 to implement the "National Semiconductor Lighting Plan", and the European Union announced the launch of a similar "Rainbow plan" in July 2000. With the support of the "863" program, the Ministry of science and technology of China first proposed the development plan of semiconductor lighting in June 2003

especially the practical application of LED backlight module technology in weinview MT505TV5, the advantage of LED backlight module intersecting with CCFL backlight module is highlighted again

1) the color gamut of LED is wider, and the color saturation can reach more than 100%; The color gamut of CCFT is relatively narrow, and most of it can only reach more than 80%

2) the light source of LED is very fast, which can help LCD eliminate tailing

3) led is a green environmental protection product without mercury; CCFT contains mercury, which produces radiant light when emitting light, which does not meet environmental requirements

4) CCFL needs high-voltage AC drive. Due to high temperature, many backlit LCD products have yellow screen and significantly dimmed brightness after several years of use, affecting the service life of LCD

5) led has wide temperature range, low voltage, good shock resistance and shock resistance. Solid state light-emitting device is adopted, with stable quality. LED backlight has no delicate (inactive gas) components, and has strong adaptability to the environment

6) long service life of LED. Due to low power consumption and less heating, the average service life is longer; The service life of ordinary CCFT backlight is 10000 hours

summary:

we believe that the outstanding performance of LED backlight module will become the most important LCD backlight, and Weilun technology will continue to promote the application of new technology in the field of human-computer interface. (end)