LED Basics

Basic advantages of LED Light

  1. Energy efficient – LED’s are now capable of outputting 135 lumens/watt
  2. Long Lifetime – 50,000 hours or more if properly engineered
  3. Rugged – LED’s are also called “Solid State Lighting (SSL) as they are made of solid material with no filament or tube or bulb to break
  4. No warm-up period – LED’s light instantly – in nanoseconds
  5. Not affected by cold temperatures – LED’s “like” low temperatures and will startup even in subzero weather
  6. Directional – With LED’s you can direct the light where you want it, thus no light is wasted
  7. Excellent Color Rendering – LED’s do not wash out colors like other light sources such as fluorescents, making them perfect for displays and retail applications
  8. Environmentally friendly – LED’s contain no mercury or other hazardous substances
  9. Controllable – LED’s can be controlled for brightness and color

Why LED’s are chosen for many applications

  • LEDs are ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently, or HID lamps that require a long time before restarting.
  • LEDs can very easily be dimmed or strobed
  • LEDs light up very quickly. A typical red indicator LED will achieve full brightness in microseconds.
  • LEDs mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs
  • LEDs, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile.
  • LEDs can be very small and are easily populated onto printed circuit boards.
  • LEDs do not contain mercury, unlike compact fluorescent lamps

Disadvantages and challenges in using LEDs

  1. LEDs are currently more expensive, price per lumen, on an initial capital cost basis, than more conventional lighting technologies. However, when considering the total cost of ownership (including energy and maintenance costs), LEDs far surpass incandescent or halogen sources and begin to threaten compact fluorescent lamps.
  2. LED performance largely depends on correctly engineering the fixture to manage the heat generated by the LED, which causes deterioration of the LED chip itself. Over-driving the LED or not engineering the product to manage heat 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. The most common design of a heat sink is a metal device with many fins, which conducts the heat away from the LED.
  3. LEDs must be supplied with the correct voltage and current at a constant flow. This requires some electronics expertise to design the electronic drivers.
  4. LED’s can shift color due to age and temperature. Also two different white LED will have two different color characteristics, which affect how the light is perceived.

 

From Continental Lighting