US3772798A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Suspension type levelling device
Assignee: Topcon Corp
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Filing: 1971-09-15
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Granted: 1973-11-20
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Expires: 1991-09-15
Abstract
Abstract A suspension type levelling device comprising a fixed member provided with a convex or concave bottom surface and a suspended member provided with a concave or convex top surface complementary to the bottom surface of the fixed member having substantially the same curvature. A thin liquid film is interposed therebetween so as to produce an attractive force between the both members. The suspended member maintains a position representing the true level or, in other words, the line connecting the center or axis of curvature of the top surface of the suspended member and its center of gravity remains in a vertical position independent of an inclined position of the fixed member. The vertical position can be obtained by suitably the surface tension of the liquid, viscosity of the liquid, weight of the suspended member, the contacting surface, the thickness of the liquid film and the radius of curvature.
Inventors
- 👤 H Kijima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:59
CPC Classifications
G; G01; G01C; G01C5/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
186 words
A levelling device comprising a body inclinable at an angle corresponding to the inclination of a support surface, a weightengaging member integrally secured to said body, said weightengaging member having a downwardly curved convex surface, said curved surface having a circular cross section extending about a datum of curvature, a liquid film coated on the curved surface of the weight-engaging member, and a weight member having an upwardly curved concave surface, so curved as to match said curved convex surface of said weight-engaging member, said curved concave surface of the weight member having a radius of curvature substantially identical with that of said curved convex surface of said weight-engaging member, said liquid film having a surface tension sufficient to suspendingly support said weight member on said curved surface of said weight-engaging member in a slidable fashion while keeping the concave surface of said weight member in snug contact with said liquid film on said weight-engaging member, whereby a line connecting the center of gravity of said weight member and said datum of curvature of said weight-engaging member remains vertical, regardless of the posture of said body.
Claim 2
Dependent Claim
186 words
A levelling device comprising a body inclinable at an angle corresponding to the inclination of a support surface, a weightengaging member integrally secured to said body, said weightengaging member having a downwardly curved convex surface, said curved surface having a circular cross section extending about a datum of curvature, a liquid film coated on the curved surface of the weight-engaging member, and a weight member having an upwardly curved concave surface, so curved as to match said curved convex surface of said weight-engaging member, said curved concave surface of the weight member having a radius of curvature substantially identical with that of said curved convex surface of said weight-engaging member, said liquid film having a surface tension sufficient to suspendingly support said weight member on said curved surface of said weight-engaging member in a slidable fashion while keeping the concave surface of said weight member in snug contact with said liquid film on said weight-engaging member, whereby a line connecting the center of gravity of said weight member and said datum of curvature of said weight-engaging member remains vertical, regardless of the posture of said body.
Claim 3
Dependent Claim
56 words
A levelling device according to claim 1, wherein said curved convex surface of the weight-engaging member of the body is a downwardly convex spherical surface, and said concave surface of the weight member is an upwardly concave spherical surface whose radius of curvature is substantially identical with that of said spherical surface of said weight-engaging member.
Claim 4
Dependent Claim
56 words
A levelling device according to claim 1, wherein said curved convex surface of the weight-engaging member of the body is a downwardly convex cylindrical surface, and said concave surface of the weight member is an upwardly concave cylindrical surface whose radius of curvature is substantially identical with that of said cylindrical surface of said suspending member.
Claim 5
Dependent Claim
83 words
A levelling device according to claim 2, wherein said weight-engaging member is a plano-convex lens, said weight member is a plano-concave lens being suspended by said plano-convex lens through a liquid film applied on the outer surface of the convex portion of the plano-convex lens, and said plano-convex lens and said plano-concave lens form a prism so as to deflect a light beam incident on the prism by an angle corresponding to the deflection angle of said plano-convex lens relative to a vertical.
Claim 6
Dependent Claim
106 words
A levelling device according to claim 2, wherein said weight-engaging member is a transparent plano-convex lens, said weight member is non-transparent, the vertical projection of said weight member on a horizontal plane is a circle whose radius is smaller than the radius of said plaNo-convex lens, and an annular ring whose radius is substantially identical with said radius of said vertical projection of said weight member is secured to the top surface of said plano-convex lens in a concentric fashion, whereby said body is brought to a horizontal posture when the projection of said weight member on said plano-convex lens is concentric with said annular ring.
References Cited (Backward Citations)
CA615406A
Cited
US925058A
Cited
US1300602A
Cited
US2385425A
Cited
US3160237A
Cited
US3051425A
Cited
US3141242A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |