Patent Cooperation Treaty (PCT) is the most important international treaty in the patent field after the Paris Convention for the Protection of Industrial Property, and it is another milestone in the development history of the international patent system. The treaty was signed by 35 countries in Washington on June 1970. 1978 was implemented on June 1 day. As of July 20 13, * * has 148 member countries and belongs to the Geneva-based World Intellectual Property Organization.