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advantages and disadvantages of using light emitting diodes

Advantages of using LEDs

LEDs produce more light per Watt than do incandescent bulbs; this is useful in battery powered devices.

LEDs can emit light of an intended color without the use of color filters that traditional lighting methods require. This is more efficient and can lower initial costs.

The solid package of an LED can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.

When used in applications where dimming is required, LEDs do not change their colour tint as the current passing through them is lowered, unlike incandescent lamps, which yellow.

LEDs are built inside solid cases that protect them, unlike incandescent and discharge sources, making them extremely durable.

LEDs have an extremely long life span when conservatively run: upwards of 100,000 hours, twice as long as the best fluorescent bulbs and twenty times longer than the best incandescent bulbs. (Incandescent bulbs can also be made to last an extremely long time by running at lower than normal voltage, but only at a huge cost in efficiency; LEDs have a long life when operated at their rated power.)

Further, LEDs mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs.

LEDs light up very quickly. A typical red indicator LED will achieve full brightness in microseconds; LEDs used in communications devices can have even faster response times.

LEDs can be very small and are easily populated onto printed circuit boards.

Disadvantages of using LEDs

LEDs are currently more expensive, price per lumen, than more conventional lighting technologies. The additional expense partially stems from the relatively low lumen output and the drive circuitry and power supplies needed.

LED performance largely depends on the ambient temperature of the operating environment. "Driving" an LED "hard" in high ambient temperatures may result in overheating of the LED package, eventually leading to device failure. Adequate heat-sinking is required to maintain long life. This is especially important when considering automotive, medical, and military applications where the device must operate over a large range of temperatures, and are required to have a low failure rate.

LEDs require complex power supply setups to be efficiently driven. In indicator applications a simple series resistor can be used; however, this sacrifices a large amount of energy efficiency.

LEDs typically cast light in one direction at a narrow angle compared to an incandescent or fluorescent lamp of the same lumen level.

LEDs usually emit spectrally impure light which means that a white LED usually does not have the same spectral power distribution as sunlight or even moonlight.

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