Audio-Technica was established in 1962 in Tokyo, Japan by Hideo Matsushita as a phonograph cartridge manufacturer. Its first products were the AT-1 and the AT-3 MM stereo phono cartridges. Business rapidly developed and Audio-Technica expanded into other fields. One of their most famous products are a battery-operated, portable record player called Mister Disc that was sold in the U.S. in the early 1980s. In 2005, Audio-Technica developed "Uniguard", a method for making microphones resistant to radio frequency interference from cell phones, Bluetooth devices, wireless computer networks and walkie-talkies. 13 patents were involved in bringing the feature to fruition, as company engineers modified many different elements of microphone construction and operation. Over 50 existing Audio-Technica microphone models have been upgraded with the new RFI-resistant technology.