US3882381A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for detecting wet and icy surface conditions
Assignee: Surface Systems Inc
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Filing: 1973-11-05
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Granted: 1975-05-06
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Expires: 1993-11-05
Abstract
Abstract A system for detecting wet and icy conditions on the surface of highways, airport runways and the like. A first capacitor is positioned on a surface the condition of which is being detected. This capacitor has first and second spaced-apart electrodes which are positioned substantially coplanar with the surface and exposed to atmospheric precipitation which affects the capacitor''s dielectric and capacitance. A second capacitor having first and second spaced-apart electrodes is positioned so as not to be exposed to atmospheric precipitation. Respective out-ofphase time-varying signals are applied to the first electrodes of said capacitors and the second electrodes are commonly connected. Means for indicating when the magnitude of a signal coupled to the commonly connected second electrodes reaches a predetermined magnitude provides an indication of the presence of any atmospheric precipitation on said surface.
Inventors
- 👤 Robert O Gregory
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:06
CPC Classifications
G; G08; G08B; G08B19/00; G08B19/02; G01; G01W; G01W1/00; G01W1/14; G01N; G01N27/00; G01N27/02; G01N27/22; G01N27/226
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
159 words
A system for detecting wet and icy conditions on the surface of highways, airport runways and the like comprising: a first capacitor adapted to be positioned on a surface the condition of which is to be detected, said capacitor having first and second spaced-apart electrodes adapted to be positioned substantially coplanar with said surface and exposed to atmospheric precipitation thereby to affect the dielectric and capacitance thereof; a second comparator comprising first and second electrodes spaced from and substantially identical to and in registration with the aforesaid electrodes and adapted to be positioned so as not to be exposed to atmospheric precipitation; means for concurrently applying respective out-of-phase timevarying signals to the first electrodes of said capacitors, said second electrodes being commonly connected; and means for indicating when the magnitude of a signal coupled to the commonly connected second electrodes reaches a predetermined magnitude thereby to provide an indication of the presence of any atmospheric precipitation on said surface.
Claim 2
Independent Claim
159 words
A system for detecting wet and icy conditions on the surface of highways, airport runways and the like comprising: a first capacitor adapted to be positioned on a surface the condition of which is to be detected, said capacitor having first and second spaced-apart electrodes adapted to be positioned substantially coplanar with said surface and exposed to atmospheric precipitation thereby to affect the dielectric and capacitance thereof; a second comparator comprising first and second electrodes spaced from and substantially identical to and in registration with the aforesaid electrodes and adapted to be positioned so as not to be exposed to atmospheric precipitation; means for concurrently applying respective out-of-phase timevarying signals to the first electrodes of said capacitors, said second electrodes being commonly connected; and means for indicating when the magnitude of a signal coupled to the commonly connected second electrodes reaches a predetermined magnitude thereby to provide an indication of the presence of any atmospheric precipitation on said surface.
Claim 3
Dependent Claim
21 words
A system as set forth in claim 1 wherein the electrodes of said capacitors are covered by layers of electrical insulation.
Claim 4
Dependent Claim
36 words
A system as set forth in claim 2 wherein the electrodes of said second capacitor are covered by a layer of electrical insulation thicker than that of the layer covering the electrodes of said first capacitor.
Claim 5
Dependent Claim
23 words
A system as set foth in claim 2 wherein the electrodes of said first and those of said second capcitors are respectively interdigitated.
Claim 6
Dependent Claim
40 words
A system as set forth in claim 4 wherein the electrodes of said first capacitor are positioned on one surface of an insulative substrate and the electrodes of said second capacitor are positioned on the opposite surface of the substrate.
Claim 7
Dependent Claim
18 words
A system as set forth in claim 1 wherein said respective signals are substantially identical and 180* out-of-phase.
Claim 8
Dependent Claim
38 words
A system as set forth in claim 6 further comprising means for balancing the signals coupled to said second electrodes so that in the absence of any precipitation substantially no resultant signal is present at the second electrodes.
Claim 9
Dependent Claim
31 words
A system as set forth in claim 7 wherein the balancing means includes means for adjusting the magnitude of the signal applied to the first electrode of one of the capacitors.
Claim 10
Dependent Claim
64 words
A system as set forth in claim 1 wherein said respective time-varying signals are composites of a substantially constant amplitude lower frequency signal component and a substantially constant amplitude higher frequency signal component, and wherein said system further comprises a filter for separating the lower frequency signal component and the higher frequency signal component of any signal coupled to the commonly connected second electrodes.
Claim 11
Dependent Claim
43 words
A system as set forth in claim 9 in which the indicating means includes means responsive to the magnitude of any signal coupled to said second electrodes failing to reach said predetermined magnitude thereby to provide an indication of a clear surface condition.
Claim 12
Dependent Claim
36 words
A system as set forth in claim 10 in which the indicating means includes means responsive to the magnitudes of the responsive coupled signal components reaching said predetermined magnitude thereby to indicate a wet surface condition.
Claim 13
Dependent Claim
49 words
A system as set forth in claim 11 in which the indicating means includes means responsive to a change in the ratio of the magnitude of the coupled higher frequency signal component to the magnitude of the coupled lower frequency signal component thereby to indicate an icy surface condition.
Claim 14
Dependent Claim
27 words
A system as set forth in claim 9 wherein said respective time-varying signals applied to the first electrodes of said capacitors are substantially identical and 180* out-of-phase.
Claim 15
Dependent Claim
80 words
A system as set forth in claim 13 further comprising means for adjusting the magnitude of the signal applied to the first electRodes of one of the capacitors so that in the absence of any precipitation substantially no resultant signal is present on the second electrodes, and in which the indicating means includes means responsive to the substantial absence of any resultant signal being present at the commonly connected electrodes thereby to provide an indication of a clear surface condition.
Claim 16
Dependent Claim
31 words
A system as set forth in claim 14, which further includes means for adjusting the amplitudes of the lower frequency signal component and the higher frequency signal component to be equal.
Claim 17
Dependent Claim
47 words
A system as set forth in claim 15 in which the indicating means includes means responsive to higher and lower frequency signal components of substantially equal amplitudes in excess of said predetermined magnitude being coupled to the commonly connected electrodes thereby to indicate a wet surface condition.
Claim 18
Dependent Claim
40 words
A system as set forth in claim 16 in which the indicating means includes means responsive to a change in the ratio of magnitudes of said coupled higher and lower frequency signal components thereby to indicate an icy surface condition.
Claim 19
Dependent Claim
30 words
A systen as set forth in claim 9 wherein said lower frequency is in the order of 1000 Hz and said higher frequency is in the order of 200 KHz.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |