US4041437A
Expired / Lapsed
US
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Humidity sensor
Assignee: Panasonic Holdings Corp
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Filing: 1975-12-24
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Granted: 1977-08-09
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Expires: 1995-12-24
Abstract
Abstract This invention provides a humidity sensor having a negative coefficient of resistivity for relative humidity, which comprises 99.99 to 10 mole percent of iron oxide (Fe2O3) and 0.01 to 90 mole percent of at least one member selected from alkali metal oxides, which are lithium oxide (Li2O), sodium oxide (Na2O), potassium oxide (K2O) and cesium oxide (Cs2O). The amount of the alkali metal oxide in the sensor is preferably 0.01 to 25 mole percent. This sensor is advantageous because it can accurately detect the changes in humidity and it has a long, stable life.
Inventors
- 👤 Mikio Matsuura
- 👤 Nobuji Nishi
- 👤 Masatsugu Yamaguchi
- 👤 Michio Matsuoka
- 👤 Takeshi Masuyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 23:51
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/121; Y; Y10; Y10S; Y10S252/00; Y10S252/963
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
76 words
A humidity sensor comprising a sintered material having electrodes applied thereto, said sintered material having a negative coefficient of resistivity for relative humidity and comprising 99.99 to 10 mole percent of iron oxide (Fe 2 O 3 ) and 0.01 to 90 mole percent of at least one member selected from the group consisting of lithium oxide (Li 2 O), sodium oxide (Na 2 O), potassium oxide (K 2 O) and cesium oxide (Cs 2 O).
Claim 2
Dependent Claim
76 words
A humidity sensor comprising a sintered material having electrodes applied thereto, said sintered material having a negative coefficient of resistivity for relative humidity and comprising 99.99 to 10 mole percent of iron oxide (Fe 2 O 3 ) and 0.01 to 90 mole percent of at least one member selected from the group consisting of lithium oxide (Li 2 O), sodium oxide (Na 2 O), potassium oxide (K 2 O) and cesium oxide (Cs 2 O).
Claim 3
Dependent Claim
16 words
A humidity sensor according to claim 1, wherein said member is potassium oxide (K 2 O).
Claim 4
Dependent Claim
21 words
A humidity sensor according to claim 1, wherein said member is present in an amount of 0.01 to 25 mole percent.
Claim 5
Dependent Claim
25 words
A humidity sensor according to claim 2, wherein said potassium oxide (K 2 O) is present in an amount of 0.01 to 25 mole percent.
Claim 6
Dependent Claim
25 words
A humidity sensor according to claim 4, wherein said potassium oxide (K 2 O) is present in an amount of 0.01 to 2.0 mole percent.
Claim 7
Dependent Claim
26 words
A humidity sensor according to claim 4, wherein said potassium oxide (K 2 O) is present in amount of 2.0 to less than 4.0 mole percent.
Claim 8
Dependent Claim
25 words
A humidity sensor according to claim 4, wherein said potassium oxide (K 2 O) is present in an amount of 4.0 to 25 mole percent.
Claim 9
Dependent Claim
18 words
A humidity sensor according to claim 1, wherein said alkali metal, oxide is lithium oxide (Li 2 O).
Claim 10
Dependent Claim
18 words
A humidity sensor sccording to claim 1, wherein said alkali metal oxide is sodium oxide (Na 2 O).
Claim 11
Dependent Claim
18 words
A humidity sensor according to claim 1, wherein said alkali metal oxide is cesium oxide (Cs 2 O).
Claim 12
Dependent Claim
20 words
A humidity sensor according to claim 1 wherein said sintered material is in the form of a disc or film.
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) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |