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,
Thomas Edison flaws as an extremely short life, high expense to produce, and high electric current drawn, making them difficult to apply on a large scale commercially. Edison realized that to connect a series of electric lights to an economically manageable size and using the necessary thickness of copper wire, he would have to develop a lamp that used a low amount of current. This lamp must have high resistance and use relatively low voltage (around 110 volts). After many experiments, first with carbon filaments and then with platinum and other metals, Edison returned to a carbon filament. The first successful test