US3847351A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Soil matric potential sensor
Assignee: WATER CONSERVATION SYSTEMS Inc 141 SOUTH SPRING STREET CLAREMONT CA A CORP OF CA
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Filing: 1973-06-29
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Granted: 1974-11-12
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Expires: 1993-06-29
Abstract
Abstract A matric potential sensor comprises a heat diffusion sensor whose output varies as a function of changes in heat diffusion to and from the sensor, and porous granular material extending in adjacent, heat transfer relations with the sensor and capable of absorbing water when pressure in the surrounding soil is greater than the porous material about the sensor, and losing water content as the soil matric potential increases.
Inventors
- 👤 H Hasenbeck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 05:45
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/24; G01N33/246; A; A01; A01G; A01G25/00; A01G25/16; A01G25/167
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
117 words
In a matric potential sensor for use in underground soil and in combination with an automatic, closed-lOop, irrigation control, the combination comprising a. a heat diffusion sensor in the form of a solid state, heat diffusion thermistor having an output which varies as a function of changes in heat diffusion from or to the sensor, and b. porous granular material in the form of glass beads extending in adjacent, heat transfer relation with the heat diffusion sensor and characterized as capable of absorbing water when pressure in the soil is greater than the porous material and losing water content as the matric potential of the soil increases, thereby providing the required increase or decrease in sensor heat-diffusion.
Claim 2
Dependent Claim
117 words
In a matric potential sensor for use in underground soil and in combination with an automatic, closed-lOop, irrigation control, the combination comprising a. a heat diffusion sensor in the form of a solid state, heat diffusion thermistor having an output which varies as a function of changes in heat diffusion from or to the sensor, and b. porous granular material in the form of glass beads extending in adjacent, heat transfer relation with the heat diffusion sensor and characterized as capable of absorbing water when pressure in the soil is greater than the porous material and losing water content as the matric potential of the soil increases, thereby providing the required increase or decrease in sensor heat-diffusion.
Claim 3
Dependent Claim
28 words
The combination of claim 1 including a porous container containing said material, and adapted to be located underground in heat and water transfer relation with the underground formation.
Claim 4
Dependent Claim
22 words
The combination of claim 2 wherein said heat diffusion sensor is embedded in the porous material which is located in the container.
Claim 5
Dependent Claim
13 words
The combination of claim 3 wherein the container is located in situ, underground.
Claim 6
Dependent Claim
41 words
The combination of claim 1 including said irrigation control operatively coupled with the sensor to initiate irrigation when the sensed matric potential increases above a predetermined level and deactivates irrigation when the soil matric potential reduces below the sensor initiation point.
Claim 7
Dependent Claim
20 words
The combination of claim 1 wherein said sensor is embedded in the porous material which is located in situ, underground.
Claim 8
Dependent Claim
41 words
The combination of claim 6 including said irrigation control operatively coupled with the sensor to initiate irrigation when the sensed matric potential increases above a predetermined level and deactivates irrigation when the soil matric potential reduces below the sensor initiation point.
Claim 9
Dependent Claim
30 words
The combination of claim 2 wherein said glass beads have cross dimensions between 0.002 and 250 microns to provide a matric potential control range of from -0.01 to -15 bars.
Claim 10
Dependent Claim
41 words
The combination with claim 6 wherein various sizes of porous material are mixed to form various linear matric potential sensors suitable for soil matric potential measurements over the measurement range or for irrigation control at selected values within the measurement range.
References Cited (Backward Citations)
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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) | 1977-11-11 | 1978-05-13 | 1978-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-11 | 1982-05-13 | 1982-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-11 | 1986-05-13 | 1986-11-12 | $7700.00 | Window Closed / Lapsed |