Thomas Edison of the Edison patent to charge a more reasonable rate for the use of the Edison patent rights and lowering the price of the electric lamp. On October 8, 1883, the US patent office ruled that Edison's patent was based on the work of William E. Sawyer and was, therefore, invalid. Litigation continued for nearly six years, until October 6, 1889, when a judge ruled that Edison's electric light improvement claim for "a filament of carbon of high resistance" was valid. To avoid a possible court battle with Joseph Swan, whose British patent had been awarded a year before Edison's,
Moscow Electric Lamp Plant and the Electrovacuum Instrument Plant in Voronezh. The Moscow Electrovacuum Instrument Plant, with its two associated special design bureaus, specializes in developing and producing a variety of vacuum tube products (photoelectric cells, xenon and mercury tubes, gas-filled and gas discharge devices, photoelectronic multipliers and others). This plant dates back to before World War II, and was known, until 1972, as the Moscow Electric Lamp Plant (MELZ). The Khromatron Plant in Moscow and the Electrovacuum Instrument Plant in Voronezh, produce mainly CRT's for color television. Moscow Electric Lamp Plant Moscow Electric Lamp Plant () is a company based in Moscow, Russia.