The LED stands for Light-emitting diode. LED is a PN-junction diode mainly used as the source of light. The LED has a leg over common orthodox incandescent light in terms of efficiency, low consumption power, compact size, longer range, and an ability to retain the quality for a longer period of time.
It is based on the electroluminescence effect – A process where a diode converts electric current to light when electrons change their state inside the LED semiconductors. So LEDs, also known as infrared-emitting diodes.
The brightness of every LED depends on the current drawn by it – the most the current drawn the more brightness will be
Note: The LED is not symmetrical in nature, allowing current to flow in one direction only.
The beginnings of LED technology dates all the way back to the discovery of electroluminescence in 1907 by English experimenter H.J. Round of Marconi Labs using a crystal of silicon carbide and a cat’s-whisker detector. This created the foundation for the creation of the first LED in 1927 by Russian inventor Oleg Losev, who shared his research in Soviet, German and British scientific journals.
In the following decades, there were multiple experiments and advancements that touched on the concept of an LED in the decades following Losev’s work. However, it wasn’t until the discovery of near-infrared light emission by James R. Board and Gary Pittman of Texas Instruments in 1961 that the reality of practical LED usage was made possible. On August 8th of 1962, the two engineers filed a patent for “Semiconductor Radiant Diode” based on their work, which the U.S. Patent Office granted for their GaAs infrared light-emitting diode, under U.S. Patent No. 3,293,513.
The work from Texas Instruments was expanded upon by Hewlett-Packard (HP) to create cost effective LEDs for the commercial market. Beginning in 1962, HP engaged in research and development to find a way to improve the performance of LEDs, while simultaneously reducing their costs in order for them to be used in common consumer goods and electronics. In addition to HP’s own R&D team, there were also collaborative efforts with the Monsanto Company, who at the time were the sole manufacturer of raw Gallium Arsenide Phosphide semiconductor material, a critical component of LEDs.
This collaborative R&D effort paid off in 1968, with the simultaneous introduction of HP’s LED display and Mosanto’s LED indicator lamp. These were the first commercially viable LED products and sparked a revolution in digital display lighting, replacing nixie tubes as the primary display technology as well as neon and incandescent for indicator lights. Over the next several decades, LED technology continued to improve, offering additional colors as well as increased durability, longevity and overall performance.
With the advent of High-power LEDs (HP-LEDs) over the past decade, LEDs have come to completely dominate almost every concerable lighting application in existence. Beginning in specialty applications such as flashlights and compact spotlights for commercial, military, and industrial applications, HP-LEDs have made their way into common consumer lighting applications, such as LED tubes, bulbs, and even dedicated LED lighting fixtures.
With HP-LEDs, the quality of the light produced has progressively improved along with lumen output. This quality of light, measured using the Color Rendering Index (CRI), has now surpassed practically every other form of light outside of natural daylight.
Following Haitz’s law, the overall progression of LED technology will continue to increase exponentially with inversely proportional costs making the technology more economical for widespread use. Like their past, the future of LEDs continues to be bright.