Patent ID: 8050144

Claim:
A geophone ( 110 ) comprising: a cylindrical magnet ( 114 ); upper and lower pole piece caps ( 116 , 118 ) receiving the upper and lower ends of said magnet ( 114 ), respectively; a tubular outer cylindrical housing ( 120 ), said magnet ( 114 ) and upper and lower pole piece caps ( 116 , 118 ) being coaxially received within and connected to said housing ( 120 ) and defining an annular region within said housing ( 120 ); upper and lower end caps ( 128 , 126 ) connected to the upper and lower ends of said housing ( 120 ), respectively, said magnet ( 114 ) and said upper and lower pole piece caps ( 116 , 118 ) being coaxially centered within said housing ( 120 ) and captured by said upper and lower end caps ( 128 , 126 ); an electrical coil ( 140 , 142 ) disposed in said annular region and movable in an axial direction with respect to said housing ( 120 ) whereby an electrical potential is induced in said coil ( 140 , 142 ) by movement of said coil ( 140 , 142 ) relative to said housing ( 120 ), said coil having first and second electrical leads ( 182 , 180 ); an electrically conductive lower spring ( 134 ) rigidly carried by said lower end cap ( 126 ), said lower spring ( 134 ) resiliently supporting said coil ( 140 , 142 ), said lower spring electrically connected to said first electrical lead ( 182 ); and an electrically conductive contact spring ( 136 ) disposed and compressed between said lower spring ( 134 ) and said lower pole piece cap ( 118 ), whereby said contact spring provides a rotatable electrical connection between said lower spring ( 134 ) and said lower pole piece cap ( 118 ).