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US3693079A
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US
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Apparatus for measuring percent moisture content of particulate material using microwaves and penetrating radiation
Assignee: Individual
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Filing: 1970-04-14
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Granted: 1972-09-19
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Expires: 1990-04-14
Abstract
Abstract Apparatus for measuring the percent moisture content of particulate materials, such as wood chips and grain, is described in which a beam of microwaves and a beam of penetrating radiation, such as gamma rays, X-rays, beta rays or high-velocity electrons, are transmitted through the same portion of a layer of such material. The beam of microwaves is directed at an acute angle to the particulate layer so that any microwave reflections do not strike the transmitting antenna and produce standing wave patterns. The microwaves are of a frequency that the microwave beam is partially absorbed by the water in the moist particulate material to produce a moisture signal, but has a wavelength greater than the dimensions of the particles to prevent diffraction effects. The beam of penetrating radiation is also partially absorbed by the total mass of the moist particulate material to produce a density signal. The moisture and density signals are then fed to an analog computer to determine the percent of moisture with an accuracy of within + OR - 0.25 percent of the reading over a moisture range of about 25 to 65 percent, and within + OR - 0.5 percent of the reading outside of this range and above 5 percent moisture.
Inventors
- 👤 Charles W E Walker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:24
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/48; G06G7/75; G01; G01N; G01N22/00; G01N22/04; G01N23/00; G01N23/02; G01N23/06; G01N23/12; G01N23/083
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
280 words
Apparatus for measuring the moisture content of particulate material, comprising: supply means for supplying a layer of moist particulate material; first radiation means including a first source means for directing a beam of microwaves free of frequency modulation through at least a portion of said layer, said microwaves having a frequency which is absorbed a greater amount by the water in said layer than by the solid particulate material and having a wavelength which is greater than the dimensions of the particles in said particulate material, and a first detector means for detecting the transmitted portion of said microwave beam to obtain a first electrical signal which is proportional to the amount of water in said layer portion; second radiation means including a second source means for directing a beam penetrating radiation through substantially the same portion of said layer, said penetrating radiation being of a type which is diverse from said microwaves and is absorbed in an amount proportional to the total mass of the moist particulate material, and a second detector means for detecting the transmitted portion of said beam of penetrating radiation to obtain a second electrical signal proportional to the total mass of the moist particulate material in said layer portIon; signal processing means for combining the first signal and the second signal to produce a third electrical signal proportional to the percent of water in said layer portion; and support means for supporting said first radiation means so that the beam of microwaves is directed through the particulate layer at an acute angle which is sufficiently small to prevent the microwaves reflected by said layer from producing standing wave interference patterns with said microwave beam.
Claim 2
Dependent Claim
280 words
Apparatus for measuring the moisture content of particulate material, comprising: supply means for supplying a layer of moist particulate material; first radiation means including a first source means for directing a beam of microwaves free of frequency modulation through at least a portion of said layer, said microwaves having a frequency which is absorbed a greater amount by the water in said layer than by the solid particulate material and having a wavelength which is greater than the dimensions of the particles in said particulate material, and a first detector means for detecting the transmitted portion of said microwave beam to obtain a first electrical signal which is proportional to the amount of water in said layer portion; second radiation means including a second source means for directing a beam penetrating radiation through substantially the same portion of said layer, said penetrating radiation being of a type which is diverse from said microwaves and is absorbed in an amount proportional to the total mass of the moist particulate material, and a second detector means for detecting the transmitted portion of said beam of penetrating radiation to obtain a second electrical signal proportional to the total mass of the moist particulate material in said layer portIon; signal processing means for combining the first signal and the second signal to produce a third electrical signal proportional to the percent of water in said layer portion; and support means for supporting said first radiation means so that the beam of microwaves is directed through the particulate layer at an acute angle which is sufficiently small to prevent the microwaves reflected by said layer from producing standing wave interference patterns with said microwave beam.
Claim 3
Dependent Claim
21 words
Apparatus in accordance with claim 1 in which the penetrating radiation is electromagnetic radiation having a wavelength less than 100 angstroms.
Claim 4
Dependent Claim
34 words
Apparatus in accordance with claim 1 in which the particulate material is wood chips, the penetrating radiation is gamma rays and the microwaves have a frequency in the range of 1 to 5 gigahertz.
Claim 5
Dependent Claim
42 words
Apparatus in accordance with claim 3 in which the wood chips are provided in a layer of substantially uniform thickness, at least 10 centimeters thick, and the microwaves have a frequency of about 2.45 gigahertz and a wavelength of about 12 centimeters.
Claim 6
Dependent Claim
21 words
Apparatus in accordance with claim 1 in which the acute angle is in the range of about 40* to 65* .
Claim 7
Dependent Claim
13 words
Apparatus in accordance with claim 3 in which said angle is about 53*.
Claim 8
Dependent Claim
80 words
Apparatus in accordance with claim 1 in which the supply means includes a conveyor belt with the first source means positioned above and the first detector means positioned below said conveyor belt and the first radiation means includes a microwave reflector member beneath said conveyor belt to change the direction of the microwave beam in the path between the layer and the first detector means so that said first detector means is positioned to the side of said conveyor belt.
Claim 9
Dependent Claim
24 words
Apparatus in accordance with claim 7 in which the beam of penetrating radiation intersects the microwave beam in said portion of the particulate layer.
Claim 10
Dependent Claim
33 words
Apparatus in accordance with claim 1 in which the particulate material is grain, the penetrating radiation is gamma rays and the microwaves have a frequency in the range of 5 to 30 gigahertz.
Claim 11
Dependent Claim
24 words
Apparatus in accordance with claim 9 in which the microwaves have a frequency of about 10 gigahertz and a wavelength of about 3 centimeters.
Claim 12
Dependent Claim
22 words
Apparatus in accordance with claim 1 in which the supply means includes a conveyor which provides a moving layer of particulate material.
Claim 13
Dependent Claim
34 words
Apparatus in accordance with claim 11 in which the supply means includes a leveling means for leveling the layer of particulate material to provide it with a substantially uniform thickness at the measurement position.
Claim 14
Dependent Claim
33 words
Apparatus in accordance with claim 12 in which the leveling means includes at least one rake means supported above the conveyor and having a plurality of projections which extend down into said layer.
Claim 15
Dependent Claim
28 words
Apparatus in accordance with claim 12 in which the leveling means includes at least one roller means having a central portion of larger diameter than its end portions.
Claim 16
Dependent Claim
20 words
Apparatus in accordance with claim 1 in which the particulate material has a moisture content of at least 25 percent.
Claim 17
Dependent Claim
72 words
Apparatus in accordance with claim 1 in which the signal processing means is an analog computer in which the first signal V1 is divided by the second signal V2 to produce the third signal V3, in accordance with the formula V3 K1 ((V0-V1)/V2) + K2, where V0 is the output signal of the first detector means when no particulate material is present, and where K1 and K2 are constants, as herein defined.
Claim 18
Dependent Claim
41 words
Apparatus in accordance with claim 1 in which the layer of particulate material is moving during the moisture and mass measurements, and the first detector means and the second detector means are electrical circuits each havinG the same response time constant.
Claim 19
Dependent Claim
17 words
Apparatus in accordance with claim 17 in which the time constant is about 0.1 to 0.5 second.
Claim 20
Dependent Claim
49 words
Apparatus in accordance with claim 1 in which the first detector means includes a microwave attenuator means and an electrical control means connected to form a negative feedback circuit between the output of said attenuator and its control input for electrically varying the microwave attenuation of said attenuator means.
Claim 21
Dependent Claim
87 words
Apparatus in accordance with claim 19 in which the macrowave attenuator means includes PIN diodes and the control means includes an attenuator driver means connected in the negative feedback circuit to said PIN diodes for providing said attenuator means with a microwave output signal of substantially constant amplitude related to the amplitude of a reference microwave signal applied to one input of a comparator means having its other input connected to the output of said attenuator means and having its output connected to said attenuator driver means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-19 | 1976-03-20 | 1976-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-19 | 1980-03-20 | 1980-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-19 | 1984-03-20 | 1984-09-19 | $7700.00 | Window Closed / Lapsed |