Light bulb. When it comes to electric lights, I believe the famous inventor Thomas Edison comes to mind. However, during the process of invention and patent application, some episodes occurred: In 1850, the Englishman Joseph Wilson Swan began to study electric lights. In 1878, he obtained a British patent for a light bulb powered by carbon filaments under vacuum, and began to establish a company in the United Kingdom to install electric lights in homes. In 1875, Edison purchased an electric light patent from a Canadian electrician. (Because they did not have enough financial resources to continue research), after Edison purchased the patent, he tried to improve the filament used. In 1879, he changed to using carbon filament to make a light bulb, which successfully lasted for 13 hours. By 1880, the carbonized bamboo filament light bulb he created successfully lasted 1,200 hours in the laboratory. But in England, Swann sued Edison for patent infringement and won. Edison's electric light company in England was forced to bring Swann on as a partner. But later Swann sold his rights and patents to Edison. In the United States, Edison's patents were also challenged. The U.S. Patent Office once ruled that his invention had a criminal record and was invalid. Finally, after years of legal battles, Edison obtained the patent for the carbon filament incandescent lamp. Edison's greatest discovery was the use of tungsten as a filament instead of carbon. Then in 1906, General Electric invented a method of making tungsten filament for electric lights. Eventually a cheap method of manufacturing tungsten filament was solved, and tungsten filament light bulbs are still in use today.