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I have just finished my new book "Eureka!". It is all about those dramatic moments in history when a new product or process was first discovered (if you want a copy please email me at VernonStent@hotmail.com) . One of the inventions that did not make it into the book was the fluorescent lamp (or tube). That is not to say it isn't a fascinating story - it certainly is. The trouble is that there is not one big "eureka" moment. It could be said that the fluorescent lamp was never really invented at all but that it evolved over time.
The creation of the fluorescent lamp was a truly joint effort spanning a century: Here are the milestones:
1675: Jean Picard, a French astronomer, noted that mercury in a barometer tube would glow when shaken. He recorded this observation but did not understand it
1846: Julius Plücker, German mathematician and physicist, theorized and experimented with coloured light produced by passing electricity through various gasses. He worked with glassblower Heinrich Geissler who invented what was to become known as the Geissler tube in which the experiments were conducted.
1850's: Heinrich Geissler continued to develop light emitting tubes
1857: Frenchman Alexandre Edmond Becquerel experimented with electric discharge tubes coated on the inside with various luminescent materials
1868: Becquerel published his landmark treatise La Lumiere, ses causes et ses effets
1893 Nikola Tesla, originally from Serbia, developed the fluorescent light using high frequency lighting ballasts
1894 Daniel McFarlane Moore, a U.S. inventor created the gas discharge lamp using carbon dioxide and nitrogen to produce white and pink light respectively
1901: Serial inventor Peter Cooper Hewitt from New York, invented the mercury vapour lamp. For the first time fluorescent lamps were being produced commercially, albeit on a small scale
1926: Edmund Germer, Friedrich Meyer and Hans J. Spanner - all from Germany - managed to produce a fluorescent tube with greater gas pressure and a fluorescent inner coating that converted ultra violet light into visible white light.
1938: Having purchased the patent from Edmund Germer, General Electric mass produced fluorescent lamps.
1974: GE Lighting invented the energy-efficient compact fluorescent bulb
How Does it Work?
First you need a glass tube that has small amount of a certain gas and some mercury sealed inside - and nothing else. The gas will be argon or neon or any of a number of other gasses (each produces its own unique colour). Electricity is passed from one end of the tube to another. The electrons that pass through ionise the atoms in the mixture and cause it to emit ultra violet light. The electricity output must be limited before it can pass through, using a choke or ballast. Without this limiting factor, fluorescent tubes could explode! By contrast, a high voltage is required to get the whole process started. When the lamp is first switched on, a starter is used to provide this "kick-start". The starter may be an integral part of the lamp build and may be automatic or it may be a separate unit, typically a small plug that twists into position.
The fluorescent lamp has had quite a journey from Jean Picard's early musings to the energy-efficient lamps of today. They are used in may applications. One of these applications is the fly killer machine. Insectocutor fly killers use ultra violet fluorescent tubes that attract flies in order to trap and kill them. Each uv bulb comes complete with a starter and a choke. |