The working principle of EL backlight driver

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With the popularity of high-tech civilian products, the former only in the aircraft cabin seat use EL technology has been widely used in commercial handheld devices, cell phones,LED Writing Board, pagers, cordless phones, personal digital assistants, remote control, etc. products, the method has the volume of filial piety EL backlight, light weight, low temperature,menu signs, low power consumption, without blinking, light uniformity and other characteristics, is now gradually replacing the traditional way of LED backlighting. EL backlight system is composed of EL and the EL lamp driver chip components. EL light film of thickness less than 0.2mm, is sprayed from the insulating substrate and the electroluminescent material sandwiched between two layers of electrode composition. EL electroluminescent lamp suppliers by using different light-emitting materials, such as zinc sulfide, calcium sulfide or strontium sulfide, and then doped with other elements such as magnesium, samarium, europium or add a fluorescent dye, etc., to adjust the brightness of light and color. change the excitation frequency can also cause color changes of light when the frequency increases, the direction of the color changes to bluish, and when the frequency is reduced to the greenish color of the direction of change, EL light film that inspired the original color is EL light when voltage is 200V/400Hz luminous color film. EL light film with strong flexibility, without impairment under the premise of the electrode can be cut or bent without affecting any luminescence; but, EL light film is a relative to the LED light source, light guide plate so the diffuser can not achieve full surface uniform light; In addition, LED is a , while the EL lamp is a cold light source chip. relative to the LED backlight, EL backlight system, another advantage is reduced power consumption. EL light film of the need is high-voltage, load current required is very small, about the range of 0.03 to 1mA/cm2, in general, the area of the EL lamp is less than 10 cm2, the operating current In a few mA or so. However, you need only drive an LED 5 to 10mA of current. Low power consumption for battery-powered equipment, has considerable significance. From the point of view of electrical characteristics, EL light film with a resistance-capacitance characteristic, equivalent circuit shown in Figure 1, the capacitor capacity is usually 2 to 6nF/in2 (EL lamp capacitance of the smaller the better the quality.) resistor is usually 50 to 15000KOhm/in2. EL drive circuit with a maximum brightness of drive space and drive EL lamps because of the different pieces which were quite different. EL lamp brightness film is the combined effect of several electrical parameters. In general, peak to peak driving voltage increases, the brightness increase; drive voltage increases, the brightness increase (when the frequency increased to several thousand Hz, the increase in brightness will gradually decrease); on the other hand, the driver increased frequency of the voltage, EL light-emitting efficiency will reduce the film; course, EL light film of material, quality and structure of the luminance and efficiency have a great impact, for example, different colors different EL light film efficiency, the efficiency of green the highest. In addition, EL light film mapping unit is the brightness of light reflected active fL (foot Lamberts) or nits (cd/m2, candles / square meter), 1fL = 0.2919nits, rather than the reflected light intensity measurement of body The Lux (lux). EL EL lamp life is measured in half-life, that film EL lamp brightness down to half the initial EL light film of continuous work time. typical EL LED lights of the half-life is 5,000 to 10,000 hours, depending on the light-emitting material, excitation voltage and operating frequency. higher voltage and higher frequency will reduce the drive the service life of EL lamp sheet, high humidity and high temperature conditions also reduces the service life of LED lights. It should be noted that the introduction of the driving voltage of the DC component will greatly reduce the life of EL lamp pieces,Neon Signs, some of the EL driver with one end grounded EL lamp driver chip end of the practice is highly undesirable, because it EL light film not only introduced to the DC component, and the introduction of the system ground is also more interference signals. on the electrical characteristics, EL light film reduces the life of the reduction means that the equivalent capacitance and equivalent resistance value increases. EL EL lamp applications in most cases is the direct current low voltage systems, such as batteries. But the EL EL lamps to be driven by high pressure, usually require to be efficiently drive circuit DC voltage is converted to the frequency of 200Hz to 1KHz, amplitude of 50 to 200V AC voltage, and do not use too much electronic components.