Incandescent light bulb granted a Hungarian patent (No. 34541) for a tungsten filament lamp that lasted longer and gave brighter light than the carbon filament. Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1904. This type is often called Tungsram-bulbs in many European countries. Filling a bulb with an inert gas such as argon or nitrogen slows down the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater efficacy with less reduction in filament life. In 1906, William D. Coolidge developed a method of making "ductile tungsten" from
Phase-out of incandescent light bulbs to 40 percent more efficient than standard incandescent lamps designed for a 2000-hour life. Depending on size, voltage, and designed life, small low-voltage halogen lamps can have 70% higher efficacy than large line-voltage lamps. The high operating temperature of halogen bulbs may be a safety hazard in some applications. A compact fluorescent lamp (CFL) uses a fluorescent lamp tube which is curved or folded to fit into the space of an incandescent bulb and contains a compact electronic ballast in the base of the lamp. Compared to general-service incandescent lamps giving the same amount of visible light, CFLs use one-fifth