US3600946A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid level sensor
Assignee: Solid State Radiations Inc
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Filing: 1969-07-10
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Granted: 1971-08-24
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Expires: 1989-07-10
Abstract
Abstract An improved liquid level sensor is provided which includes a first semiconductor element exhibiting particular resistance/temperature characteristics so as to have a first resistance value when the element is submerged in a liquid and a second resistance value when the liquid level drops to expose the element to the ambient temperature, and which includes a second element in series with the first element and exhibiting a positive resistance/temperature characteristic so as to render the sensor essentially independent of ambient temperature conditions.
Inventors
- 👤 Francis P Ziemba
- 👤 John R Moross
- 👤 Henry S Katzenstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 02:51
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/24; G01F23/246; G01F23/247
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
85 words
Thermal sensing means for operating throughout a particular temperature range, including: a first element exhibiting a peak resistivity at a predetermined temperature within said particular temperature range and having a negative temperature coefficient of resistivity above said predetermined temperature and a positive temperature coefficient of resistivity below said predetermined temperature; a second element connected in series with said first element and exhibiting a positive temperature coefficient of resistivity within said particular temperature range; and current limiting means in series with said first and second elements.
Claim 2
Dependent Claim
85 words
Thermal sensing means for operating throughout a particular temperature range, including: a first element exhibiting a peak resistivity at a predetermined temperature within said particular temperature range and having a negative temperature coefficient of resistivity above said predetermined temperature and a positive temperature coefficient of resistivity below said predetermined temperature; a second element connected in series with said first element and exhibiting a positive temperature coefficient of resistivity within said particular temperature range; and current limiting means in series with said first and second elements.
Claim 3
Dependent Claim
28 words
The thermal sensing means defined in claim 1, in which said current limiting means comprises means indicating when the current in said circuit departs from a predetermined range.
Claim 4
Dependent Claim
36 words
The thermal sensing means defined in claim 1, in which said first element comprises a semiconductor silicon crystal of n-type having a resistivity of approximately 10 ohm-cm at a temperature of the order of 70* F.
Claim 5
Dependent Claim
36 words
The thermal sensing means defined in claim 1, in which said second element comprises a silicon semiconductor crystal exhibiting a resistance of the order of 8 ohms at a temperature of the order of 70* F.
Claim 6
Dependent Claim
126 words
A thermal fluid sensor for indicating the presence of a fluid within a vessel, and for operation throughout a predetermined temperature range, said sensor including: a first element positioned within said vessel for thermal contact with said fluid and exhibiting a peak resistivity at a predetermined temperature within said particular temperature range and having a negative temperature coefficient of resistivity above said predetermined temperature and a positive temperature coefficient of resistivity below said predetermined temperature; and a second element positioned to be in thermal contact with the wall of said vessel and series connected with said first element and exhibiting a positive temperature coefficient of resistivity in said particular temperature range and in which said first element and second element are comprised of semiconductor crystal wafers.
Claim 7
Dependent Claim
126 words
A thermal fluid sensor for indicating the presence of a fluid within a vessel, and for operation throughout a predetermined temperature range, said sensor including: a first element positioned within said vessel for thermal contact with said fluid and exhibiting a peak resistivity at a predetermined temperature within said particular temperature range and having a negative temperature coefficient of resistivity above said predetermined temperature and a positive temperature coefficient of resistivity below said predetermined temperature; and a second element positioned to be in thermal contact with the wall of said vessel and series connected with said first element and exhibiting a positive temperature coefficient of resistivity in said particular temperature range and in which said first element and second element are comprised of semiconductor crystal wafers.
Claim 8
Dependent Claim
66 words
The thermal sensor defined in claim 5 and which includes a metallic housing adapted to be mounted in the wall of said vessel and a metallic probe extending from said housing into the interior of said vessel, and in which said first element is mounted in said probe and in thermal contact therewith, and said second element is mounted in said housing in thermal contact therewith.
Claim 9
Dependent Claim
53 words
The thermal sensor defined in claim 6 in which sAid probe and housing are electrically interconnected to form a common electrical connection to one side of said first element; and which includes an electrically conductive spring member electrically interconnecting one side of said second element to the other side of said first element.
Claim 10
Dependent Claim
36 words
The thermal sensor defined in claim 6 and which includes an electrical terminal member mounted in said housing and electrically insulating therefrom, said terminal member being electrically connected to the other side of said second element.
Claim 11
Dependent Claim
37 words
The thermal sensor defined in claim 5, in which said first element comprises a semiconductor silicon crystal of the n- type having a resistivity of approximately 10 ohms-cm. at a temperature of the order of 70* F.
Claim 12
Dependent Claim
34 words
The thermal sensor defined in claim 5, in which said second element comprises a silicon semiconductor crystal exhibiting a resistance of the order 8 ohms at a temperature of the order of 70* F.
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) | 1974-08-23 | 1975-02-22 | 1975-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-23 | 1979-02-22 | 1979-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-23 | 1983-02-22 | 1983-08-24 | $7700.00 | Window Closed / Lapsed |