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Timeline of lighting technology
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<h2 id="antiquity">Antiquity</h2> <ul><li>125,000 BC Widespread <a href="/facts/Control_of_fire_by_early_humans/fkuAeEAV">control of fire by early humans</a>.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a></li> <li>17,500 BC oldest documented lamp, utilizing animal fat as fuel<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a></li> <li>c. 4500 BC <a href="/facts/Oil_lamp/g69IsMsg">oil lamps</a></li> <li>c. 3000 BC <a href="/facts/Candle/3d0EwvR6">candles</a> are invented.</li> <li>577 CE Use of <a href="/facts/Match/EQPsJa7J">matches</a> in China.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a></li></ul> <h2 id="18th-century">18th century</h2> <ul><li>1780 <a href="/facts/Ami_Argand/P1uFmyEU">Ami Argand</a> invents the <a href="/facts/Argand_lamp/E2XRFH6m">central draught fixed oil lamp</a>.</li> <li>1784 Argand adds glass chimney to central draught lamp.</li> <li>1786 <a href="/facts/William_Nicholson_(chemist)/xyogcehY">William Nicholson</a> proposes use of concentric wicks.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a></li> <li>1792 <a href="/facts/William_Murdoch/4X6T0wYG">William Murdoch</a> begins experimenting with <a href="/facts/Gas_lighting/HDfak36f">gas lighting</a> and probably produced the first gas light in this year.</li> <li>1800 French watchmaker Bertrand Guillaume Carcel [fr] overcomes the disadvantages of the Argand-type lamps with his clockwork fed <a href="/facts/Carcel_lamp/fg7PzNAu">Carcel lamp</a>.</li></ul> <h2 id="19th-century">19th century</h2> <ul><li>1800–1809 <a href="/facts/Humphry_Davy/aDNRfNou">Humphry Davy</a> invents the <a href="/facts/Arc_lamp/1y99ep6E">arc lamp</a> when using Voltaic piles (battery) for his electrolysis experiments.</li> <li>1802- <a href="/facts/Vasily_Vladimirovich_Petrov/U7Gm7Unh">Vasily Vladimirovich Petrov</a> developed the first persistent <a href="/facts/Electric_arc/1hUPPAG0">electric arc</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></li> <li>1802 William Murdoch illuminates the exterior of the <a href="/facts/Soho_Foundry/j2rgJsNa">Soho Foundry</a> with gas.</li> <li>1805 Philips and Lee's Cotton Mill, <a href="/facts/Manchester/2Do01QHs">Manchester</a> was the first industrial factory to be fully lit by gas.</li> <li>1809 Humphry Davy publicly demonstrates the first electric lamp over 10,000 lumens, at the Royal Society.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></li> <li>1813 National Heat and Light Company formed by <a href="/facts/Frederick_Albert_Winsor/IH9M61Ml">Frederick Albert Winsor</a>.</li> <li>1815 Humphry Davy invents the <a href="/facts/Davy_lamp/PfePf9j6">miner's safety lamp</a>.</li> <li>1823 <a href="/facts/Johann_Wolfgang_D%25C3%25B6bereiner/pKdvmjpt">Johann Wolfgang Döbereiner</a> invents the <a href="/facts/D%25C3%25B6bereiner%2527s_lamp/XBolbhxn">Döbereiner's lamp</a>.</li> <li>1835 <a href="/facts/James_Bowman_Lindsay/nDuAh574">James Bowman Lindsay</a> demonstrates a <a href="/facts/Light_bulb/v3fb5WBp">light bulb</a> based electric lighting system to the citizens of <a href="/facts/Dundee%2c_Scotland/Auu4EE4K">Dundee</a>.</li> <li>1841 Arc-lighting is used as experimental public lighting in Paris.</li> <li>1853 <a href="/facts/Ignacy_%25C5%2581ukasiewicz/5IfbLvGb">Ignacy Łukasiewicz</a> invents the modern <a href="/facts/Kerosene_lamp/tFBCrVm5">kerosene lamp</a>.</li> <li>1856 <a href="/facts/Glassblowing/dWf2rYAD">glassblower</a> <a href="/facts/Heinrich_Geissler/uSQxuMG8">Heinrich Geissler</a> confines the electric arc in a <a href="/facts/Geissler_tube/SHjKIVjf">Geissler tube</a>.</li> <li>1867 <a href="/facts/Edmond_Becquerel/DpKmDnXH">Edmond Becquerel</a> demonstrates the first <a href="/facts/Fluorescent_lamp/R8SlXCyg">fluorescent lamp</a>.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></li> <li>1874 <a href="/facts/Alexander_Lodygin/Wrb2L7Uq">Alexander Lodygin</a> patents an <a href="/facts/Incandescent_light_bulb/31frjg0A">incandescent light bulb</a>.</li> <li>1875 <a href="/facts/Henry_Woodward_(inventor)/rYmkEKPn">Henry Woodward</a> patents an electric light bulb.</li> <li>1876 <a href="/facts/Pavel_Yablochkov/Vz51VAuz">Pavel Yablochkov</a> invents the <a href="/facts/Yablochkov_candle/ypnHky3E">Yablochkov candle</a>, the first practical carbon arc lamp, for public street lighting in Paris.</li> <li>1879 (About Christmas time) Col. <a href="/facts/R._E._Crompton/43DnGjGS">R. E. Crompton</a> illuminated his home in <a href="/facts/Porchester_Gardens/0ztXR8rA">Porchester Gardens</a>, using a primary battery of Grove Cells, then a generator which was better. He gave special parties and illuminated his drawing room and dining room. Source: Practical Electrical Engineering, Newnes. Article entitled "The Development of Electric Lighting".</li> <li>1879 <a href="/facts/Thomas_Edison/IeDbdyP4">Thomas Edison</a> and <a href="/facts/Joseph_Swan/31u13aFB">Joseph Swan</a> patent the carbon-thread <a href="/facts/Incandescent_lamp/31frjg0A">incandescent lamp</a>. It lasted 40 hours.</li> <li>1880 Edison produced a 16-watt lightbulb that lasted 1500 hours.</li> <li>1882 Introduction of large scale <a href="/facts/Direct_current/r9MNUx84">direct current</a> based indoor incandescent lighting and lighting <a href="/facts/Utility/wlMDG74L">utility</a> with Edison's first <a href="/facts/Pearl_Street_Station/HFlA5YMo">Pearl Street Station</a></li> <li>c. 1885 Incandescent <a href="/facts/Gas_mantle/d56ATf6b">gas mantle</a> invented, revolutionises <a href="/facts/Gas_lighting/HDfak36f">gas lighting</a>.</li> <li>1886 <a href="/facts/Great_Barrington%2c_Massachusetts/VYlgzTPb">Great Barrington, Massachusetts</a> demonstration project, a much more versatile (long-distance transmission) <a href="/facts/Transformer/EYYfXWrF">transformer</a> based <a href="/facts/Alternating_current/qxICS3xa">alternating current</a> based indoor incandescent lighting system introduced by <a href="/facts/William_Stanley%2c_Jr./DkDGEQjA">William Stanley, Jr.</a> working for <a href="/facts/George_Westinghouse/XfKhz8MG">George Westinghouse</a>.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Stanley lit 23 businesses along a 4000 feet length of main street stepping a 500 AC volt current at the street down to 100 volts to power incandescent lamps at each location.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a></li> <li>1893 GE introduces the first commercial fully enclosed carbon arc lamp. Sealed in glass globes, it lasts 100h and therefore 10 times longer than hitherto carbon arc lamps <a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a><a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></li> <li>1893 <a href="/facts/Nikola_Tesla/MzqGhnkj">Nikola Tesla</a> puts forward his ideas on high frequency and wireless electric lighting<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> which included public demonstrations where he lit a <a href="/facts/Geissler_tube/SHjKIVjf">Geissler tube</a> wirelessly.</li> <li>1894 <a href="/facts/Daniel_McFarlan_Moore/WIemnXKE">Daniel McFarlan Moore</a> creates the <a href="/facts/Moore_tube/WIemnXKE">Moore tube</a>, precursor of <a href="/facts/Glow_discharge/B7SWIEjL">electric gas-discharge</a> lamps.</li> <li>1897 <a href="/facts/Walther_Nernst/B2bYwpQp">Walther Nernst</a> invents and patents his <a href="/facts/Nernst_lamp/oEYrvMCW">incandescent lamp</a>, based on <a href="/facts/Solid_state_(electronics)/US0Qbq28">solid state</a> <a href="/facts/Electrolyte/4YE8bIVa">electrolytes</a>.</li></ul> <h2 id="20th-century">20th century</h2> <ul><li>1900 Frederick Baldwin patents a <a href="/facts/Carbide_lamp/YQkr2aGe">carbide lamp</a> for use on bicycles.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> The invention builds on acetylene lamps from the 1890s.</li> <li>1901 <a href="/facts/Peter_Cooper_Hewitt/aDtP2N8C">Peter Cooper Hewitt</a> creates the first commercial <a href="/facts/Mercury-vapor_lamp/cVCl1CSY">mercury-vapor lamp</a>.</li> <li>1904 <a href="/facts/Alexander_Just/L9Pm9yhn">Alexander Just</a> and <a href="/facts/Franjo_Hanaman/1zEDvxDA">Franjo Hanaman</a> invent the <a href="/facts/Tungsten/WYwbNDYX">tungsten</a> filament for incandescent lightbulbs.</li> <li>1910 <a href="/facts/Georges_Claude/9tdWozpQ">Georges Claude</a> demonstrates <a href="/facts/Neon_lighting/RIo03t4t">neon lighting</a> at the <a href="/facts/Paris_Motor_Show/NJg8rLWR">Paris Motor Show</a>.</li> <li>1912 Charles P. Steinmetz invents the <a href="/facts/Metal-halide_lamp/kxCKb1E9">metal-halide lamp</a>.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></li> <li>1913 <a href="/facts/Irving_Langmuir/mPt8xwUp">Irving Langmuir</a> discovers that <a href="/facts/Inert_gas/3EkBEoYh">inert gas</a> could double the luminous efficacy of incandescent lightbulbs.</li> <li>1917 <a href="/facts/Burnie_Lee_Benbow/3AfMobx7">Burnie Lee Benbow</a> patents the <a href="/facts/Coiled_coil/U0YEzcB4">coiled coil</a> filament.</li> <li>1920 <a href="/facts/Arthur_Compton/FrNYLBj4">Arthur Compton</a> invents the <a href="/facts/Sodium-vapor_lamp/STEH8FgR">sodium-vapor lamp</a>.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></li> <li>1921 Junichi Miura creates the first incandescent lightbulb to utilize a coiled coil filament.</li> <li>1925 <a href="/facts/Marvin_Pipkin/Dk9VbPwh">Marvin Pipkin</a> invents the first internal frosted lightbulb.</li> <li>1926 <a href="/facts/Edmund_Germer/AGvtIE4p">Edmund Germer</a> patents the modern fluorescent lamp.</li> <li>1927 <a href="/facts/Oleg_Losev/UJx3JCle">Oleg Losev</a> creates the first <a href="/facts/Light-emitting_diode/gE8x4MDb">LED</a> (light-emitting diode).</li> <li>1953 Elmer Fridrich invents the <a href="/facts/Halogen_lamp/p2Cvtvc9">halogen lamp</a>.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></li> <li>1953 André Bernanose and several colleagues observe <a href="/facts/Electroluminescence/geazduXd">electroluminescence</a> in organic materials.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a><a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></li> <li>1960 <a href="/facts/Theodore_H._Maiman/lbykgHqX">Theodore H. Maiman</a> creates the first <a href="/facts/Laser/jk6PTvvT">laser</a>.</li> <li>1962 <a href="/facts/Nick_Holonyak/9y6JoMJ9">Nick Holonyak</a> Jr. develops the first practical visible-spectrum (red) light-emitting diode.</li> <li>1963 Kurt Schmidt invents the first <a href="/facts/Sodium-vapor_lamp/STEH8FgR">high pressure sodium-vapor lamp</a>.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a></li> <li>1972 <a href="/facts/M._George_Craford/l2dRWk3K">M. George Craford</a> invents the first yellow light-emitting diode.</li> <li>1972 Herbert Paul Maruska and Jacques Pankove create the first violet light-emitting diode.</li> <li>1981 Philips sells their first Compact Fluorescent Energy Saving Lamps, with integrated conventional ballast.</li> <li>1981 Thorn Lighting Group exhibits the <a href="/facts/Ceramic_metal-halide_lamp/oAheeCNv">ceramic metal-halide lamp</a>.</li> <li>1985 <a href="/facts/Osram/nSPt8NIK">Osram</a> answers with the first electronic Energy Saving Lamps to be very successful.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a></li> <li>1987 <a href="/facts/Ching_Wan_Tang/acfT3KQP">Ching Wan Tang</a> and <a href="/facts/Steven_Van_Slyke/N36URqej">Steven Van Slyke</a> at <a href="/facts/Eastman_Kodak/zMnK74Cp">Eastman Kodak</a> create the first practical <a href="/facts/OLED/219L1aMJ">organic light-emitting diode</a> (OLED).</li> <li>1990 Michael Ury, Charles Wood, and several colleagues develop the <a href="/facts/Sulfur_lamp/JzjsShky">sulfur lamp</a>.</li> <li>1991 <a href="/facts/Philips/Xp4uczGg">Philips</a> invents a fluorescent lightbulb that lasts 60,000 hours using <a href="/facts/Electromagnetic_induction/T36JjtgY">magnetic induction</a>.</li> <li>1994 T5 lamps with cool tips are introduced to become the leading fluorescent lamps with up to 117 lm/W with good color rendering. These and almost all new fluorescent lamps are to be operated on electronic ballasts only.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a></li> <li>1994 The first commercial <a href="/facts/Sulfur_lamp/JzjsShky">sulfur lamp</a> is sold by Fusion Lighting.</li> <li>1995 <a href="/facts/Shuji_Nakamura/no9rGS9M">Shuji Nakamura</a> at <a href="/facts/Nichia/2NyxGeHJ">Nichia labs</a> invents the first practical blue and with additional phosphor, white LED, starting an LED boom.<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a></li></ul> <h2 id="21st-century">21st century</h2> <ul><li>2008 Ushio Lighting demonstrates the first <a href="/facts/LED_filament/eLxnNql4">LED filament</a>.<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a></li> <li>2011 <a href="/facts/Philips/Xp4uczGg">Philips</a> wins <a href="/facts/L_Prize/CJXkQKql">L Prize</a> for LED screw-in lamp equivalent to 60 W incandescent A-lamp for general use.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"First Control of Fire by Human Beings—How Early?". Retrieved 2007-11-12. <a href="http://www.beyondveg.com/nicholson-w/hb/hb-interview2c.shtml" target="_blank">http://www.beyondveg.com/nicholson-w/hb/hb-interview2c.shtml</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>de Beaune, Sophie A.; White, Randall (1993). "Ice Age Lamps". Scientific American. 268 (3): 108–113. Bibcode:1993SciAm.266c.108D. doi:10.1038/scientificamerican0393-108. ISSN 0036-8733. JSTOR 24941409. <a href="https://www.jstor.org/stable/24941409" target="_blank">https://www.jstor.org/stable/24941409</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Needham, Joseph (1 January 1962). Science and Civilization in China: Volume 4, Physics and Physical Technology; Part 1, Physics. Cambridge University Press. pp. 70–71. ISBN 978-0-521-05802-5. Archived from the original on 2 January 2014. sulphur matches were certainly sold in the markets of Hangchow when Marco Polo was there {{cite book}}: ISBN / Date incompatibility (help) <a href="978-0-521-05802-5" target="_blank">978-0-521-05802-5</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Nicholson, William (May 1785). "The London Magazine, of May 1785". Hathi Trust. Retrieved 28 October 2024. <a href="https://babel.hathitrust.org/cgi/pt?id=nyp.33433081682787&seq=7" target="_blank">https://babel.hathitrust.org/cgi/pt?id=nyp.33433081682787&seq=7</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Guarnieri, M. (2015). "Switching the Light: From Chemical to Electrical" (PDF). IEEE Industrial Electronics Magazine. 9 (3): 44–47. doi:10.1109/MIE.2015.2454038. hdl:11577/3164116. S2CID 2986686. Archived (PDF) from the original on 2022-02-14. Retrieved 2019-09-02. <a href="https://www.research.unipd.it/bitstream/11577/3164116/5/21%20LightElectric.pdf" target="_blank">https://www.research.unipd.it/bitstream/11577/3164116/5/21%20LightElectric.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Dr. Thomas Klett, Geschichte der Lichttechnik [History of Lighting] <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"In The Beginning: 10 Inventors of the Incandescent Lightbulb". Txchnologist. Archived from the original on 2021-04-17. Retrieved 2025-05-06. <a href="http://web.archive.org/web/20210417195155/https://txchnologist.com/post/77710091911/in-the-beginning-10-inventors-of-the-incandescent#_=_" target="_blank">http://web.archive.org/web/20210417195155/https://txchnologist.com/post/77710091911/in-the-beginning-10-inventors-of-the-incandescent#_=_</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Great Barrington Historical Society, Great Barrington, Massachusetts <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"Great Barrington Experiment". edisontechcenter.org. Retrieved 2025-05-06. <a href="http://edisontechcenter.org/GreatBarrington.html" target="_blank">http://edisontechcenter.org/GreatBarrington.html</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Dr. Thomas Klett, Geschichte der Lichttechnik [History of Lighting] <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Bernard Gorowitz Ed., The General Electric Story <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Carlson, W. Bernard (April 27, 2015). Tesla: Inventor of the Electrical Age. Princeton University Press. p. 132. ISBN 978-0691165615. <a href="978-0691165615" target="_blank">978-0691165615</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>note: at St. Louis, Missouri, Tesla public demonstration called, "On Light and Other High-Frequency Phenomena", (Journal of the Franklin Institute, Volume 136 By Persifor Frazer, Franklin Institute, Philadelphia, Pa) <a href="/wiki/St._Louis,_Missouri" target="_blank">/wiki/St._Louis,_Missouri</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>U.S. patent 656,874 <a href="https://patents.google.com/patent/US656874" target="_blank">https://patents.google.com/patent/US656874</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>"A brief history of high intensity discharge hid lighting". Shine Retrofits. Retrieved 21 December 2017. <a href="https://www.shineretrofits.com/knowledge-base/lighting-learning-center/a-brief-history-of-high-intensity-discharge-hid-lighting.html" target="_blank">https://www.shineretrofits.com/knowledge-base/lighting-learning-center/a-brief-history-of-high-intensity-discharge-hid-lighting.html</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>"Sodium Lamp". Edison Center. Archived from the original on 20 September 2014. Retrieved 21 December 2017. <a href="https://web.archive.org/web/20140920234320/http://www.edisontechcenter.org/SodiumLamps.html" target="_blank">https://web.archive.org/web/20140920234320/http://www.edisontechcenter.org/SodiumLamps.html</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>"20th Century Inventors: Tungsten Halogen Lamp". American History. Retrieved 21 December 2017. <a href="http://americanhistory.si.edu/lighting/bios/frid.htm" target="_blank">http://americanhistory.si.edu/lighting/bios/frid.htm</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Bernanose, A.; Comte, M.; Vouaux, P. (1953). "A new method of light emission by certain organic compounds". J. Chim. Phys. 50: 64. doi:10.1051/jcp/1953500064. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Bernanose, A.; Vouaux, P. (1953). "Organic electroluminescence type of emission". J. Chim. Phys. 50: 261. doi:10.1051/jcp/1953500261. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Schmidt, Kurt. "High pressure sodium vapor lamp". Google Patents. Retrieved 21 December 2017. <a href="https://patents.google.com/patent/US3248590" target="_blank">https://patents.google.com/patent/US3248590</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Dr. Thomas Klett, Geschichte der Lichttechnik [History of Lighting] <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>Dr. Thomas Klett, Geschichte der Lichttechnik [History of Lighting] <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>Dr. Thomas Klett, Geschichte der Lichttechnik [History of Lighting] <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>"The Next Generation of LED Filament Bulbs". Retrieved 2025-05-10. <a href="https://www.ledinside.com/knowledge/2015/2/the_next_generation_of_led_filament_bulbs" target="_blank">https://www.ledinside.com/knowledge/2015/2/the_next_generation_of_led_filament_bulbs</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> </ol>