1850, English Joseph? Wilson? Joseph Wilson Swan began to study electric lights. 1878, he obtained a British patent for a light bulb powered by carbon wire under vacuum, and started to set up a company in Britain to install electric lights in every household.
1874, two Canadian electrical technicians applied for a patent for electric lamps. They filled helium gas under the glass bubble, and the charged carbon rod would glow. But they didn't have enough financial resources to continue developing this invention, so they sold the patent to Edison at 1875.
Edison tried to improve the filament after buying the patent. 1879, he changed to carbon filament to make a light bulb, which successfully lasted 13 hours. By 1880, his carbonized bamboo filament bulb had been successfully maintained in the laboratory 1200 hours. But in Britain, Swan sued Edison for patent infringement and won. Edison's electric light company in England was forced to make Swan a partner. But later Swan sold his rights and patents to Edison. In America, Edison's patent has also been challenged. The United States Patent Office once ruled that his invention had a criminal record and was invalid. Finally, after years of litigation, Edison obtained the patent right of carbon filament incandescent lamp.
Edison's greatest discovery was that tungsten was used as the filament instead of carbon. Later, in 1906, General Electric invented the manufacturing method of tungsten wire for electric lamps. Finally, the method of manufacturing tungsten filament at a low price was solved, and the tungsten filament bulb has been used ever since.