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US 4,712,094 AGranted
Self-orienting passive marker structure
AssigneeMinnesota Mining and Manufacturing Company
InventorJohn H. Bolson, Sr.
Life of this patent
Estimating the term…
Abstract
A passive marker including a tuned circuit having an inductance and a capacitance carried by a carrier enclosed within a hollow sphere that is partially filled with a liquid to freely float the carrier. The inductance includes a coil which, when the carrier is floating, positions the axis of the coil so it is closer to the vertical than the horizontal. The passive marker is of a type that is buried relative to portions of utilities such as gas, telephone, water and power lines, for use in locating such portions when necessary.
Claims6
A passive marker including;
- an inductance-capacitance tuned circuit wherein said inductance includes a coil having an axis;
- a hollow sphere partially filled with a liquid;
- and
- a buoyant carrier carrying said tuned circuit and floating freely in said liquid for positioning said axis of said coil closer to the vertical than the horizontal when said buoyant carrier is floating freely in said liquid.
1 more element
Dependencies are inferred from the claim text.