LCD (LiquidCrystalDisplay) liquid crystal display. The structure of the LCD is placed in the liquid crystal box two parallel glass substrate, glass substrate is provided under the TFT (thin film transistor), on the glass substrate is arranged on the color filter, rotation direction signal and the voltage change by TFT to control the liquid crystal molecules, so as to achieve the control of each pixel or to exit light to display.
LED is the abbreviation of LED LightEmittingDiode. LED applications can be divided into two major categories: one is LED display; two is LED single tube applications, including backlight, LED, infrared, LED and so on. Now, as far as LED displays are concerned, the design and production technology in China is basically in line with international standards. The LED display is made up of light-emitting diodes. It uses low voltage scanning drive, with less power consumption, long service life, low cost, high brightness, little failure, large angle of view, far distance and so on.
Two, backlight principle distinction
In the current market, liquid crystal display is mainly divided into two categories, one is the use of traditional CCFL (cold cathode fluorescent tube) LCD, and the other is the use of LED (LED) backlit lcd. Many consumers directly refer to the first type of monitor as LCD, and the second type of monitor is called LED. In fact, such statements are incorrect. As a result, LCD and LED can also be distinguished from their backlight principle.
LED backlight principle
LED backlight uses LED as backlight source. Made of doped semiconductor materials led by a number of very thin layer, a layer with an excess of electrons, another layer is the lack of electronic form positively charged holes, through the current work, combination of electrons and holes, the excess energy in the form of light radiation is released. Light emitting diodes with different luminous characteristics can be obtained by using different semiconductor materials.
LED light-emitting technology has obvious advantages of color, so it is very popular in display manufacturing. At present, the obsolete CCFL (cold cathode backlight) technology because of its limitation of spectrum, the color gamut is restricted, so the best performance of only 70% NTSC color gamut, more effective to pay a high cost.
CCFL backlight principle
CCFL (cold cathode fluorescent lamp) a backlight source is enclosed in physical inert gas Ne+Ar mixed gas in a glass tube, which contains trace mercury vapor (mg), and on the inner wall of the glass coated phosphor. The working principle is when the high voltage is applied on both ends of the lamp, the lamp a few electronic high speed impact electrode produces two secondary electron emission, discharge tube, mercury or inert gas by electron impact excitation radiation, 253.7nm ultraviolet light, the ultraviolet excitation in the fluorescent powder coated on the inner wall of the tube and produce visible light. CCFL lamp life is generally defined as: at 25 degrees Celsius ambient temperature, with the rated current to drive the tube, brightness down to 50% of the initial brightness of the working time, length of the lamp life. At present, LCD TV backlight nominal life can reach 60000 hours. CCFL (cold cathode fluorescent lamp) backlight is characterized by low cost, but the color performance is less than LED backlight.
Three, advantages and disadvantages distinguish:
The advantages and disadvantages of LED backlight source
1. screen can be made thinner, we look at some of the liquid crystal display, you can see the CCFL lamp arranged several filamentous, in order to make the screen uniform light, also need to add some other devices, it can not be very thin; and the backlight, LED backlight source itself is flat without luminescent material. With other devices.
2. not the yellow dark CCFL fluorescent lamp and fluorescent lamp, a long time will be aging, so the traditional notebook screen will be two or three years after the yellow dark, LED backlight screen life is much longer, at least two or three times.
3. more power saving, LED is a semiconductor, working at low voltage, simple structure, low power consumption.
4., more environmentally friendly, CCFL lights in the mercury on the environment has great pollution, harmless recovery has great difficulties.
1., relatively high prices, at present in the same specifications, and the traditional CCFL backlight display difference between 100 - 300 yuan.
The advantages and disadvantages of CCFL backlight
1., the market for a long time, relatively mature technology
2., more stable color, professional display is still used
3., the price is relatively low
1., the service life is short. CCFL backlight service life is generally 15000 hours to 25000 hours, after 2~3 years of use, the LCD screen will be dark and yellow, which is the CCFL service life of the shortcomings caused by a relatively short period.
2., complex structure, brightness, poor output uniformity. When displaying full white or full black pictures, the difference between the screen edge and the center brightness is very obvious.
3. larger volume
4. high power consumption, high heating capacity