LED light Working Advantages Disadvantages and Application

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LED light Working :
(a) Electro luminescent lamps LED :

  • Electroluminescence is the emission of light due to the interaction of an electric-field with a suitable solid.
  • These solids may be panels, Light Emitting Diodes (LEDs), light emitting films.
  • The panels employ microcrystalline powder phosphors based on the compounds like zine sulphide. whereas in case of LEDs, compounds like “gallium phosphide” is used. Panels require high voltage to active where as LEDs require a small voltage about 2 volts D.C. and their current densities are of higher order.
  • In this chapter our study is limited to LEDs only.

(b) Lighting emitting diode (LED) :

  • It was noted in 1962 that a gallium-arsenide junction biased in the forward direction was found to be an efficient emitter of radiation.
  • Electroluminescent p-n junctions are similar to conventional silicon or germanium diodes so far as electrical characteristics are concerned.
  • However, when biased in the forward direction, some of the energy dissipated is converted into light rather than into resistive heating and hence called as “semiconductor lamps”.
  • A single crystal material is produced in the form of a rod by slowly withdrawing a seed crystal of gallium phosphide or gallium arsenide from a saturated melt.
  • LED lamp LEDs have similar electrical characteristics as the normal rectifying diodes have.
  • LEDs are virtually point sources of high intensity radiation. Life of LED device is very long (i.e. upto 100000 hours). These are mechanically robust, low current consuming.

Advantages of LED :

  1. Low power consumption.
  2. Long life (about 50000 hours) if stable voltage source is used.
  3. It starts quickly i.e. no warm up time is required.
  4. Not affected by surrounding temperature.
  5. Less self heating.
  6. The light is directional so it can be focused onto working plane directly. Wastage of light is avoided.
  7. It does not contain mercury and gases.
  8. Colour rendering is excellent.
  9. Small in size and weight.
  10. More energy efficient.
  11. Not damaged due to external shock.

Disadvantages of LED :

  1. Stable voltage source is required.
  2. Life is affected due to voltage fluctuations.
  3. Initial cost is more.

Applications of LED :

  1. Indicating lamps.
  2. Bi-colour indicators.
  3. Fault-indicators.
  4. Display-boards.
  5. Decorative lighting.
  6. Wrist watches.
  7. In automobile industries as electro-mechanical control.
  8. In instrumentation.

Types of LEDs :

  1. LED strip
  2. LED bulb
  3. Automotive LED bulbs.

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