Many ways of turning electricity into light have been developed over the two centuries since Sir Humphrey Davy (also the inventor of the “Davy” miner’s lamp) first demonstrated the electric arc in 1802. This section explores some of the history, the technologies developed and the people who created this amazing evolution.
Glowing strands of carbon
The German, Henricq Goebel, is acknowledged by many to be the first to create a true “light bulb” using a carbonised filament of bamboo inside a glass bulb in 1854. It was, however, several years before Sir Joseph Swan, the English physicist, developed the first practical “incandescent” lamp based upon very similar technology in the 1870s. Thomas Edison then turned this into a commercially viable product in 1879 and is thus generally thought of as the “inventor” of the electric lamp. Edison put so much of his time into the development of the electric light that he lodged over 1000 patents between 1878 and 1928. To this day, many lamps still use the “Edison Screw” cap.
Edison spent many winters in his home and laboratory near Fort Myers on the west coast of Florida alongside close friend Henry Ford’s estate. You can still see many of his inventions in the fascinating Edison-Ford Estate Museums.
The tungsten filament
Early lamps with carbon filaments were both inefficient and fragile and were soon replaced by tungsten filament lamps after their invention by The General Electric Company (now GE) in 1906. Companies such as Westinghouse vied with GE and The Thomas Edison Company for a share of this exciting new market and innovations came thick and fast. Other well-known names like Osram, Mazda, Philips and Siemens who developed this market throughout the 20th Century are still very much at the forefront of this market today.
As well as the incandescent lamp developments, the proponents of the electric arc lamp continued their work and this spawned a huge range of “discharge” lamps. By filling the lamp first with carbon dioxide and then the so-called “noble” gases of argon, krypton, neon and xenon, brighter and more efficient lamps were introduced in a range of colours and for a whole spectrum of industrial and commercial applications.
In 1901, the American Engineer, Peter Cooper Hewitt invented and patented the first mercury vapour lamp. This highly efficient lamp gave off a bright bluish-white light which although it had poor colour rendering properties, was often used for street lighting or early (black and white) studio photography.
Further development of the discharge lamp principle then led to the invention of the Fluorescent Light by GE, first exhibited at the New York World Fair in 1938.
In parallel with this work, yet another variant of the discharge lamp – the high pressure sodium vapour lamp (SON) was also invented. Producing a characteristic yellow light, these lamps are extremely efficient and are often used in street lighting.
From streetlights to street racers
In the 1960s, GE further extended the work on the arc lamp to produce the first generation of metal halide lamps. These are even more efficient than the original mercury vapour lamps and give a bright white light with a bluish tinge. Initially metal halide lamps were slow to start up and often took several minutes to reach full brightness. Recent advances in electronic control circuitry have now made this much less of an issue and ultra-compact versions of these lamps are now available in high-end sports cars or even for use on bicycles.
Halogen to the fore
In the late 1950s, engineers at General Electric, still pioneers in lighting technology invented the tungsten halogen lamp. This uses a very high temperature tungsten filament inside a special halogen filled quartz envelope and produces a very strong, bright white light with an efficiency about 10-15% better and generally a much longer life than ordinary incandescent lamps. Their compact size and high colour temperature have made them extremely popular in display spotlighting and “high tech” luminaires.
Recent advances have continued to focus developments on greater energy efficiency, longer life and lower environmental impact. Towards the end of the 20th century, the compact fluorescent “energy saving” lamp became more and more accepted both for domestic and commercial applications. In line with this trend, lighting based upon light emitting diodes (“LEDs”) is now starting to emerge. These have excellent energy efficiency and extremely long operating life but have yet to achieve the brilliance or colour rendering properties of other technologies.
For further information of the history of electric light, please follow these links.