Understanding the light-emitting diode

LED History

The first known report of a solid-state light-emitting diode (LED) was made in 1907 by the British experimenter H. J. Round; however, no practical use was made of the discovery for several decades.

Nick Holonyak, Jr., invented the first practical LED in 1962, leading to the first visible spectrum (colored-Red) LEDs that became commercially available in late 1960s. They were commonly used as replacements for incandescent indicators and in seven-segment displays. First in expensive equipment such as laboratory and electronics test equipment, then later in TVs, radios, telephones, calculators, and even watches. Red LEDs were only bright enough for use as indicators, as the light output could not illuminate an area.

Later, other colors became widely available and also appeared in appliances and equipment. Blue LEDs were invented in 1971. White, Green, Blue, UV, Yellow, Amber, and Yellow LEDs went into commercial production in the early 90's.

As LED materials technology became more advanced, the light output was increased, and LEDs became bright enough to be used for illumination. But with higher power, it has become increasingly necessary to get rid of the heat, so the packages have become more complex and adapted for heat dissipation.

In 1994, Peter Hochstein founded Relume and began his quest to increase the efficacy of LED light engines and arrays that could be practically incorporated into commercial products. Relume has developed and patented novel thermal management protocols, which optimize the extraction of heat, generate more light and increase the longevity of LEDs.

LED Advantages

Energy Efficiency

LEDs produce more light per watt and consume considerably less energy than traditional lamp sources.

Longer Life

LEDs have a long useful life, up to 100,000. By comparison, fluorescent tubes typically are rated at about 10-15,000 hours, depending on conditions of use, and incandescent light bulbs just 1-2,000 hours.

Color Range

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

Small Size

Single LEDs are very small and can be combined in any shape to produce desired lumen packages. Small size allows LEDs to easily populate printed circuit boards.

No Delay or Warm-up Time

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

Instant Cycling

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.

Easily Dimmable

LEDs can be easily dimmed either by pulse-width modification or lowering the forward current..

Slow to Fail

LEDs mostly fail by dimming over time, rather than the abrupt burnout of incandescent bulbs.

Rugged Durability

As solid-state components, LEDs are difficult to damage with external shock, unlike fluorescent and incandescent bulbs, which have fragile filaments and tubes to contend with.

Highly Directional

The solid package of the LED is designed to focus light in the direction where needed without waste. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.

Environmentally Friendly

Unlike fluorescent lamps, LEDs do not contain mercury or lead and are free of UV and IR emissions.

Silent Operation

With frictionless parts, LED operation is noiseless.

Enhanced Safety

The low level of heat produced and low-voltage power supply required by LEDs, make them a much safer source of light than competitive sources.