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The Incandescent Light Bulb Patent Case
Transcript of The Incandescent Light Bulb Patent Case
An electric current is passed through a
thin wire until it glow which is protected
from oxidation with a glass bulb which
is filled with inert gas.
Historians Robert Friedel
and Paul Israel list 22
inventors of incandescent
lights prior to Joseph Swan
and Thomas Edison.
Thomas Alva Edison was an American inventor and businessman.He developed many devices that greatly influenced life around the world including the phonograph, motion picture camera and the longer lasting light bulb.
"The Wizard of Menlo Park"
Edison did not invent the light bulb but instead invented the first commercially practical incandescent light bulb.Some of the eatly light bulbs had flaws such as extremely short life,high expense to produce and high electric current drawn thus making them difficult to produce at a commercial stage.
Edison's first successful light
bulb model used in public
demonstration at Menlo Park,
The first successful experiment was on 22 October 1879,it lasted 13.5 hours.After further improvements to this design,on November 4,filed for US patent 223898 which was granted on January 27
The original Patent application
Swan was a British physicist and chemist. He first demonstrated the light bulb at a lecture in Newcastle upon Tyne on 18 December 1878, but did not receive a patent until 27 November 1880 (patent No. 4933) after improvement to the original lamp.
Sir Joseph Swan
How it Works
"Your favor of the 19th was duly received. The megaphone is not yet completed and I am quite unable to say when it will be as at present I am busily engaged on the electric light."
Autograph letter signed ("T.A.Edison"), 1 page octavo, Menlo Park, New Jersey, October 22,1879. To Ellanor Hallowell Stroud.
Edison's Menlo Park Laboratory, reconstructed at Greenfield Village at Henry Ford Museum in Dearborn, Michigan. (Note the organ against the back wall)
On 3 February 1879 he publicly demonstrated a working lamp to an audience of over seven hundred people in the lecture theatre of the Literary and Philosophical Society of Newcastle upon Tyne
Like other early inventors, Swan used a carbon rod with low electrical resistance in his lamp. Due to the relationship between resistance and current, a low resistance element required lots of current in order to become hot and glow. This meant that the conductors bringing electricity to the lamp would have to be relatively short (or impossibly thick), acceptable for an experiment or demonstration, but not for a commercial electrical system
Joseph Swans house,the first building in the world to be lit by electric light.
Underhill, 99 Kells Lane, Low Fell,Gateshead
In America, Edison had been working on copies of the original light bulb patented by Swan, trying to make them more efficient. Though Swan had beaten him to this goal, Edison obtained patents in America for a fairly direct copy of the Swan light, and started an advertising campaign that claimed that he was the real inventor. Swan, who was less interested in making money from the invention, agreed that Edison could sell the lights in America while he retained the rights in Britain.
On October 8, 1883, the US patent office ruled that Edison's patent was based on the work of William Sawyer and was therefore invalid. Litigation continued for nearly six years, until October 6, 1889, when a judge ruled that Edison's electric-light improvement claim for "a filament of carbon of high resistance" was valid.
To avoid a possible court battle with Joseph Swan, whose British patent had been awarded a year before Edison's, he and Swan formed a joint company called Ediswan to manufacture and market the invention in Britain.
The company sold lamps made with a cellulose filament that Swan had invented in 1881. Variations of the cellulose filament became an industry standard, except with the Edison Company. Edison continued using bamboo filaments until the 1892 merger that created Edison General Electric, and that company then shifted to cellulose.