Editing Incandescent light bulb (section)

====Tungsten filament====
[[File:Dr. Just Sándor és Hanaman Ferenc.jpg|thumb|upright|Hanaman (left) and Just (right), the inventors of the tungsten bulbs]]
[[File:Tungsram advertisement.jpg|thumb|upright|[[Hungarian language|Hungarian]] advertising of the [[Tungsram]]-bulb from 1906. This was the first light bulb that used a filament made from [[tungsten]] instead of carbon. The inscription reads: ''wire lamp with a drawn wire – indestructible''.]]

On 13 December 1904, [[Hungary|Hungarian]] [[Sándor Just]] and [[Croats|Croatian]] [[Franjo Hanaman]] were granted a Hungarian patent (No. 34541) for a [[tungsten]] filament lamp that lasted longer and gave brighter light than the carbon filament.<ref name="guarnieri 7-1"/> Tungsten filament lamps were first marketed by the [[Hungary|Hungarian]] company [[Tungsram]] in 1904. This type is often called Tungsram-bulbs in many European countries.<ref>{{cite web|title=The History of Tungsram|archive-url=https://web.archive.org/web/20050530094858/http://www.tungsram.hu/tungsram/downloads/tungsram/tu_short_history_1896-1996.pdf |archive-date=30 May 2005|url=http://www.tungsram.hu/tungsram/downloads/tungsram/tu_short_history_1896-1996.pdf}}</ref> Filling a bulb with an [[inert gas]] such as [[argon]] or [[nitrogen]] slows down the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater [[Luminous efficacy|efficacy]] with less reduction in filament life.<ref>{{cite book|last1=Giridharan|first1=M. K.|title=Electrical Systems Design|date=2010|publisher=I. K. International|location=New Delhi|isbn=9789380578057|page=25|url=https://books.google.com/books?id=Tt6G60zZF3cC&pg=PA25|url-status=live|archive-url=https://web.archive.org/web/20160102022536/https://books.google.com/books?id=Tt6G60zZF3cC&pg=PA25&lpg=PA25|archive-date=2 January 2016}}</ref>

In 1906, [[William D. Coolidge]] developed a method of making "ductile tungsten" from [[sintered]] [[tungsten]] which could be made into filaments while working for [[General Electric|General Electric Company]].<ref>{{cite journal|doi=10.1557/S0883769400045164| journal = MRS Bulletin| volume =20 | issue = 8 | year = 1995 | pages = 67–73| title = The Coolidge Process for Making Tungsten Ductile: The Foundation of Incandescent Lighting | first1 = C.L. |last1= Briant and | first2 =Bernard P. | last2=Bewlay| bibcode = 1995MRSBu..20...67B| s2cid = 138257279}}</ref> By 1911 General Electric had begun selling incandescent light bulbs with ductile tungsten wire.<ref>{{Cite book|last1=Nair|first1=Govind B.|url=https://books.google.com/books?id=znbhDwAAQBAJ&q=By+1911+incandescent+light+bulbs+with+ductile+tungsten+wire&pg=PA22|title=The Fundamentals and Applications of Light-Emitting Diodes: The Revolution in the Lighting Industry|last2=Dhoble|first2=Sanjay J.|date=9 July 2020|publisher=Woodhead Publishing|isbn=978-0-12-823161-6|page=22|language=en|access-date=5 August 2021|archive-date=17 August 2021|archive-url=https://web.archive.org/web/20210817015813/https://books.google.com/books?id=znbhDwAAQBAJ&q=By+1911+incandescent+light+bulbs+with+ductile+tungsten+wire&pg=PA22|url-status=live}}</ref>

In 1913, [[Irving Langmuir]] found that filling a lamp with [[inert gas]] (nitrogen at first, and later argon) instead of a vacuum resulted in twice the luminous efficacy and reduced bulb blackening.{{citation needed|date=January 2021}}. He patented his device on April 18, 1916.<ref>[https://www.aps.org/archives/publications/apsnews/200304/history.cfm April 18, 1916: Langmuir Patents the Incandescent Lamp]</ref>

In 1917, [[Burnie Lee Benbow]] was granted a patent for the ''coiled coil filament'', in which a coiled filament is then itself wrapped into a coil by use of a [[mandrel]].<ref>{{cite web|title=Burnie Lee Benbow|url=http://home.frognet.net/~ejcov/benbow10.html|website=frognet|access-date=19 February 2017|url-status=dead|archive-url=https://web.archive.org/web/20120612194145/http://home.frognet.net/~ejcov/benbow10.html|archive-date=12 June 2012}}</ref><ref>Benbow, B.L., {{US patent|1247068|US patent 1247068: "Filament"}}, filed 4 October 1913</ref> In 1921, [[Junichi Miura]] created the first double-coil bulb using a coiled coil tungsten filament while working for [[Hakunetsusha]] (a predecessor of [[Toshiba]]). At the time, machinery to mass-produce coiled coil filaments did not exist. Hakunetsusha developed a method to mass-produce coiled coil filaments by 1936.<ref>{{cite web|title=Trial Production of the World's First Double-Coil Bulb|url=http://toshiba-mirai-kagakukan.jp/en/learn/history/ichigoki/1921lamp/index.htm|website=Toshiba|publisher=TOSHIBA CORP|access-date=19 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170219184124/http://toshiba-mirai-kagakukan.jp/en/learn/history/ichigoki/1921lamp/index.htm|archive-date=19 February 2017}}</ref>

Between 1924 and the outbreak of the Second World War, the [[Phoebus cartel]] attempted to fix prices and sales quotas for bulb manufacturers outside of North America.<ref name=ieee-bulb>{{Cite journal
  |title=The Great Lightbulb Conspiracy
  |journal=[[IEEE Spectrum]]
  |date=24 September 2014
|author=Markus Krajewski
  |url=https://spectrum.ieee.org/the-great-lightbulb-conspiracy
  |access-date=3 November 2017
|archive-url=https://web.archive.org/web/20171029040239/https://spectrum.ieee.org/tech-history/dawn-of-electronics/the-great-lightbulb-conspiracy
  |archive-date=29 October 2017
|url-status=live
  }}</ref>

In 1925, [[Marvin Pipkin]], an American chemist, patented a process for [[Frosted glass|frost]]ing the inside of lamp bulbs without weakening them.<ref name=10Kaccident>{{cite magazine |last= Payne |first= Kenneth Wilcox |date= 1927 |title= A $10,000 Accident |url= https://books.google.com/books?id=ICoDAAAAMBAJ&q=%22Marvin+Pipkin%22+awarded+the+Charles+A.+Coffin+award&pg=PA24 |page= 24 |magazine= Popular Science |location= New York City |publisher= Bonnier Corporation |access-date= 31 July 2020 |archive-date= 4 February 2021 |archive-url= https://web.archive.org/web/20210204021048/https://books.google.com/books?id=ICoDAAAAMBAJ&q=%22Marvin+Pipkin%22+awarded+the+Charles+A.+Coffin+award&pg=PA24 |url-status= live }}</ref> In 1947, he patented a process for coating the inside of lamps with [[silica]].<ref>{{cite journal |last=Bonnier Corp |title=Popular Science |journal=The Popular Science Monthly |url=https://books.google.com/books?id=lSQDAAAAMBAJ&pg=PA125 |date=March 1949 |page=125 |publisher=Bonnier Corporation |issn=0161-7370 |access-date=4 January 2021 |archive-date=4 February 2021 |archive-url=https://web.archive.org/web/20210204011225/https://books.google.com/books?id=lSQDAAAAMBAJ&pg=PA125 |url-status=live }}</ref>

In 1930, [[Hungary|Hungarian]] [[Imre Bródy]] filled lamps with krypton gas rather than argon, and designed a process to obtain krypton from air. Production of krypton filled lamps based on his invention started at [[Ajka]] in 1937, in a factory co-designed by Polányi and Hungarian-born physicist [[Egon Orowan]].<ref>{{cite web|url=http://energyhistory.energosolar.com/en_20th_century_electric_history.htm |title=Ganz and Tungsram – the 20th century|archive-url=https://web.archive.org/web/20090330212227/http://energyhistory.energosolar.com/en_20th_century_electric_history.htm |archive-date=30 March 2009}}</ref>{{Full citation needed |date=November 2024}}

By 1964, improvements in efficiency and production of incandescent lamps had reduced the cost of providing a given quantity of light by a factor of thirty, compared with the cost at introduction of Edison's lighting system.<ref name="GETP110">''Incandescent Lamps, Publication Number TP-110'', General Electric Company, Nela Park, Cleveland, OH (1964) pg. 3</ref>

Consumption of incandescent light bulbs grew rapidly in the US. In 1885, an estimated 300,000 general lighting service lamps were sold, all with carbon filaments. When tungsten filaments were introduced, about 50 million lamp sockets existed in the US. In 1914, 88.5 million lamps were used, (only 15% with carbon filaments), and by 1945, annual sales of lamps were 795 million (more than 5 lamps per person per year).<ref name=Kane2001>Raymond Kane, Heinz Sell ''Revolution in lamps: a chronicle of 50 years of progress (2nd ed.)'', The Fairmont Press, Inc. 2001 {{ISBN|0-88173-378-4}} page 37, table 2-1</ref>