An electric connector has a frame made of insulation, and a double-ended volute spring composed by an outermost base cylinder, and a pair of volute spring portions extending from the base cylinder so as to be contact with terminals of an electronic instrument. The base cylinder is secured in a hole formed...http://www.google.se/patents/US6843658?utm_source=gb-gplus-sharePatent US6843658 - Electric connector for connecting electronic instruments
