To the question: Who invented the light bulb? is difficult to answer. Because in the form that we see now, the light bulb was invented by several people and each made his own improvement. It is believed that the first to create a light bulb was the Russian inventor A.N. Lodygin. As a filament, he used a carbon rod placed in a vacuum vessel. On July 11, 1874, he received a patent number 1619 for a filament lamp. In parallel, he investigates the properties of refractory metals and tries to use them as a filament.
In 1875, V.F.Didrikhson improved the Lodygin lamp by evacuating air from it and using several hairs in the lamp, which increased the lamp's service life.
American inventor Thomas Edison knew about Lodygin's invention and conducted parallel research in this area. In 1879 he patented a lamp with a platinum filament, but its cost is too high. In 1880 he returned to carbon fiber and created a lamp with a 40 hour lifetime. Interesting fact, the filament for the Edison lamp was made from bamboo fibers. Simultaneously, Edison invented the cartridge and the base. Moreover, he released the light bulb to the masses, setting up the production of light bulbs at $ 2.50 apiece.
In 1906, Lodygin sold a patent for a tungsten filament to General Electric. The problem with the rapid evaporation of the filament in a vacuum was solved by the American scientist Irving Langmuir, who, working since 1909 at General Electric, came up with the idea of filling the lamp with argon, which significantly increased their operating time and increased light output.
In 1910, William David Coolidge invents an improved method for producing tungsten filament. Gradually, tungsten incandescent lamps replaced other lamp models. Interestingly that after the invention of the light bulb, people began to sleep 20 percent less.