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,
Edison screw out of use. In response to Edison's patent, Reginald Fessenden invented the bi-pin connector for the 1893 World's Fair. Other lamp bases include the bayonet mount and wedge base. Specifications for all lamp mount types are defined in the following American National Standards Institute (ANSI) and International Electrotechnical Commission (IEC) publications: Generally, the two standards are harmonized, although several types of screw mount are still defined in only one standard. In the designation "Exx", "E" stands for "Edison" and "xx" indicates the diameter in millimeters as measured across the peaks of the thread on the base (male), e.g., E12 has