Phase-out of incandescent light bulbs were no longer available from European sources. Russia is phasing out incandescent light bulbs. The production of lamps of 100 watt and more is banned. There are also discussions to ban light bulbs of 50 watts and more. Switzerland banned the sale of all light bulbs of the Energy Efficiency Class F and G, which affects a few types of incandescent light bulbs. Most normal light bulbs are of Energy Efficiency Class E, and the Swiss regulation has exceptions for various kinds of special-purpose and decorative bulbs. In line with EU rules, Switzerland banned the import and manufacture of halogen
Incandescent light bulb sintered tungsten which could be made into filaments while working for General Electric Company. By 1911 General Electric began selling incandescent light bulbs with ductile tungsten wire. In 1913, Irving Langmuir found that filling a lamp with inert gas instead of a vacuum resulted in twice the luminous efficacy and reduction of bulb blackening. In 1917, Burnie Lee Benbow was granted a patent for inventing the coiled coil filament. 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