White leds and its importance

EXPLAIN WHITE LEDS AND z ITS IMPORTANCE TODAY

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LEDs are not that weak like ordinary conventional bulbs as they don’t have filament to burn out or break. They also have an advantage of getting on instantly like halogen lamps and therefore they can be used in applications like frequent­on off cycling. They are more fragile and hard to heat up soon. There is a rapid development in LED technology and it is guaranteed that it will outnumber the HID lighting.

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LED- a source of light Light emitting diode is considered as the source of light for using diodes that emit light when the circuit is connected to it. A large number of photons is released by the LED and the effect is called as electro luminescence. A semiconductor chip located in the center of the light source is an important part of the LED. P and N regions are the regions in it with a junction between them. Positive electric charge dominates the P region and the negative electric charge dominates the N region. A block between the two region is called a junction which blocks the passage of carriers between the two regions.

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If sufficient voltage is applied to the semiconductor chip then you can find electrons crossing the junction to the opposite attractions and then two charges recombine with each other.

An emission of photon light is possible because of electron and a positive ion combination the electric potential energy is converted into electromagnetic energy.

The characteristics of the semiconductor material is determined by the photon frequency. Different semiconductor materials emits different LED colors. There are small electrical circuit components like bulb without any need of filament. By the movement of electrons LEDs are illuminated and extremely reliable on the long run.

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TYPE OF LED USED IN LIGHTING APPLICATIONS : The most fascinating technology since the introduction of fluorescent lamps is called White LED. Because of high low current requirements, high intensity LEDs are now popular and in demand. Lighting applications uses white LEDS for conserving energy. Back light illuminations in mobile phone, LCD back lights, vehicle and home lighting are some of the applications of White LED. With little energy consumption it can effectively convert electricity into light.

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Reason behind preference for White LED As white LED produces around 75­100 lumen’s per watt with a minimal current of 350 Milliampere, White LED is preferred.

LEDs have zero energy loss through heat. There is no mercury or lead in LEDS and hence they are Eco friendly.

If you consider a 1 Watt LED it gives about 100lm luminous flux which is more than enough for a particular area. Lumen is the unit for the amount of light emitted by a light source. A 730 lumen light is emitted by a 60 Watt bulb. Whereas a 900 lumen of light is emitted by 50 Watt halogen lamp.

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White LED provides 3.3 volts with a forward voltage drop of 1 watt and it consumes 350 Milli amperes. A 3 volt normal white LED requires 40 mA current for maximum brightness. With a range from hundreds of milli ampere to an Ampere producing high intensity light, High power LEDS are driven with higher current.

For avoiding damage of the device the High Power LEDS are kept on a heat sink for heat dissipation.

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CONSTRUCT WHITE LEDs using these 2 ways: ­ Coat an LED chip with blue made Indium Gallium Nitride with a lot of colors for producing White LED. Light spectrum part with respect to the blue light is transferred for a longer wavelength.

There is an operational wavelength from green to ultraviolet by varying amounts of gallium and indium during production.

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­ By Coating near UV emitting LEDs, white LEDs are formed with a combination of high efficiency Europium based blue and red emitting phosphors with green emitting copper and aluminum doped zinc sulphide.

For more information join the electrical training institute for becoming a certified electrical engineer in this field.

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