US Patent system is obviously broken. They granted a patent for two-wire coin collector 1981, while Swedish LM Ericsson had such in production since 1960s. All coin telephones in Nordic countries were like that in 1970s.
Ouch I actually read the patent. It is a modification of existing system for long wires, where high current pulse is not feasible. Energy is slowly collected to a capacitor and triggered with a tone signal.
-- So I was totally wrong this time, but US Patent System still sucks.