US4429343A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Humidity sensing element
Assignee: Leeds and Northrup Co
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Filing: 1981-12-03
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Granted: 1984-01-31
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Expires: 2001-12-03
Abstract
Abstract A humidity sensing element of the capacitance sensing type having two sets of interdigitated fingers of thin film platinum deposited on a glass substrate, all covered by a coating of water absorbing material such as cellulose acetate butyrate or a silicone rubber. The coating is of thickness such that it is substantially equal to or greater than the period of the fingers of the interdigitated electrodes.
Inventors
- 👤 Paul J. Freud
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:21
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/22; G01N27/223; G01N27/225
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
88 words
A fast, precise capacitance humidity sensing element comprising: a planar non-conducting substrate; two separate closely spaced interdigitated thin metal film electrodes deposited on said substrate with fingers having a certain period; and a thin water absorbing coating covering said interdigitated electrodes, said coating being of thickness substantially equal to or greater than the period of the fingers of said interdigitated electrodes to place the surface of the coating far enough from the surface of the fingers so that the influence of contaminants on the coating surface is negligible.
Claim 2
Dependent Claim
88 words
A fast, precise capacitance humidity sensing element comprising: a planar non-conducting substrate; two separate closely spaced interdigitated thin metal film electrodes deposited on said substrate with fingers having a certain period; and a thin water absorbing coating covering said interdigitated electrodes, said coating being of thickness substantially equal to or greater than the period of the fingers of said interdigitated electrodes to place the surface of the coating far enough from the surface of the fingers so that the influence of contaminants on the coating surface is negligible.
Claim 3
Dependent Claim
18 words
A capacitance humidity sensing element as set forth in claim 1 in which said coating is a polymer.
Claim 4
Dependent Claim
21 words
A capacitance humidity sensing element as set forth in claim 2 in which said polymer is solvent cast cellulose acetate butyrate.
Claim 5
Dependent Claim
19 words
A capacitance humidity sensing element as set forth in claim 1 in which said coating is a silicone rubber.
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) | 1987-01-30 | 1987-08-01 | 1988-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-30 | 1991-08-01 | 1992-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-30 | 1995-08-01 | 1996-01-31 | $7700.00 | Window Closed / Lapsed |