and described contactless communication via inductive coupling. Its primary use was intended to provide individual copy-protected keys for releasing the tapping process at unmanned gas stations. In September 1968, Gröttrup, together with Jürgen Dethloff as an investor, filed further patents for this identification switch, first in Austria and in 1969 as subsequent applications in the United States, Great Britain, West Germany and other countries.

Independently, Kunitaka Arimura of the Arimura