Patent US4712094A successfully refreshed from Google Patents.
US4712094A
Expired / Lapsed
US
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Self-orienting passive marker structure
Assignee: 3M Co
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Filing: 1986-05-29
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Granted: 1987-12-08
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Expires: 2006-05-29
Abstract
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.
Inventors
- 👤 John H. Bolson, Sr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 04:05
CPC Classifications
H; H03; H03J; H03J3/00; G; G01; G01V; G01V15/00; G01C; G01C15/00; G01C15/02; G01C15/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
63 words
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.
Claim 2
Dependent Claim
63 words
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.
Claim 3
Dependent Claim
17 words
A passive marker according to claim 1 wherein said tuned circuit is enclosed in said buoyant carrier.
Claim 4
Dependent Claim
29 words
A passive marker according to claim 1 wherein said coil is a flat, air-core coil and said buoyant carrier includes a cup-shaped member in which said coil is positioned.
Claim 5
Dependent Claim
19 words
A passive marker according to claim 1 wherein said inductance includes a core about which said coil is wound.
Claim 6
Dependent Claim
26 words
A passive marker according to claim 4 wherein said core and coil are carried by said carrier with said core and coil extending through said carrier.
Claim 7
Dependent Claim
38 words
A passive marker according to claim 5 wherein said core and coil extending through said carrier has a portion on one side of said carrier that is heavier than the portion on the other side of said carrier.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-07 | 1991-06-08 | 1991-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-07 | 1995-06-08 | 1995-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-07 | 1999-06-08 | 1999-12-08 | $7700.00 | Window Closed / Lapsed |