US Patent 10541095 Four-contact magnetic switch apparatus

Switch apparatus (54), designed to detect relative movement between first and second members (60, 62), includes a switch assembly (48) comprising a switch unit (20), a biasing element (50), and an operating member (52). The unit (20) has a conductive housing (22) with first, second, and third electrical pin contacts (36-40) and a shiftable body (46). The body (46) is magnetically correlated with both the element (50) and operating member (52). When the members (60, 62) are close, the operating member (52) maintains the shiftable body (46) in one switch position, whereas when the members (60, 62) are separated, the biasing element (50) magnetically moves body (46) to another switch position, thereby detecting the relative movement).