US3854045A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Measuring the dust concentration in air
Assignee: Bergwerksverband GmbH
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Filing: 1973-01-31
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Granted: 1974-12-10
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Expires: 1993-01-31
Abstract
Abstract A light beam having a wavelength between 800 nm and 2,000 nm shines into a chamber having dust-containing air. Light dispersed by the dust at an angle between 60* and 80* to the beam direction is guided to photoelectric means where its intensity is measured. Preferably, the beam of light is modulated at a particular frequency and, following reception by a photosensitive element, a phase sensitive detector is employed to filter the desired light component from any interfering light components. The output signal of the phase sensitive detector, after amplification constitutes a measure of the dust concentration in the air.
Inventors
- 👤 H Breuer
- 👤 J Gebhart
- 👤 K Robock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:58
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
93 words
A method for measuring the dust concentration in dustcontaining air, comprising, in combination, the steps of illuminating said dust-containing air with a beam of light having a wavelength between 800 nm and 2,000 nm and travelling in a predetermined direction; detecting light which is forwardly scattered by the dust particles at an angle between 60* and 80* to said predetermined direction; and measuring the intensity of the so-scattered light, said so-measured intensity constituting a measure of said dust concentration of dust having a grain size within a predetermined continuous range in said air.
Claim 2
Independent Claim
93 words
A method for measuring the dust concentration in dustcontaining air, comprising, in combination, the steps of illuminating said dust-containing air with a beam of light having a wavelength between 800 nm and 2,000 nm and travelling in a predetermined direction; detecting light which is forwardly scattered by the dust particles at an angle between 60* and 80* to said predetermined direction; and measuring the intensity of the so-scattered light, said so-measured intensity constituting a measure of said dust concentration of dust having a grain size within a predetermined continuous range in said air.
Claim 3
Dependent Claim
47 words
Method as set forth in claim 1, wherein step of illuminating said dust-containing air with a light beam comprises generating a primary light beam; dividing said primary light beam into a first beam and a second beam; and illuminating said dust-containing air with said first beam only.
Claim 4
Dependent Claim
32 words
Method as set forth in claim 2, wherein measuring the light intensity of said so-received light comprises comparing the light intensity of said so-received light with the intensity of said second beam.
Claim 5
Dependent Claim
62 words
Method as set forth in claim 3, wherein the step of comparing the intensity of said so-received light with the intensity of said second beam comprises attenuating the light of said second beam until the intensity thereof is equal to the intensity of said so-received light, whereby the degree of required attenuation is a measure of said dust concentration in said air.
Claim 6
Dependent Claim
15 words
Method as set forth in claim 1, wherein said angle is an angle of 70*.
Claim 7
Dependent Claim
164 words
Apparatus for measuring the dust concentration of dust-containing air, comprising, in combination, means for furnishing a first beam of light having a wavelength between 800 nm and 2, 000 nm; and at least partially enclosed chambers filled with said dust-containing air and having a first window for entry of said first beam into said chamber so that the dust particles in said chamber disperse the light of said first beam, and having a second window disposed to permit passage of light dispersed by said dust particles at an angle between 60* and 80* to the direction of said first beam; photoelectric means for furnishing a light intensity signal corresponding to the intensity of light falling thereon; and first optical means for guiding light dispersed at an angle between 60* and 80* to the direction of said first beam and passing through said second window to said photoelectric means, whereby said light intensity signal constitutes a measure of the dust concentrations of said dust-containing air.
Claim 8
Dependent Claim
164 words
Apparatus for measuring the dust concentration of dust-containing air, comprising, in combination, means for furnishing a first beam of light having a wavelength between 800 nm and 2, 000 nm; and at least partially enclosed chambers filled with said dust-containing air and having a first window for entry of said first beam into said chamber so that the dust particles in said chamber disperse the light of said first beam, and having a second window disposed to permit passage of light dispersed by said dust particles at an angle between 60* and 80* to the direction of said first beam; photoelectric means for furnishing a light intensity signal corresponding to the intensity of light falling thereon; and first optical means for guiding light dispersed at an angle between 60* and 80* to the direction of said first beam and passing through said second window to said photoelectric means, whereby said light intensity signal constitutes a measure of the dust concentrations of said dust-containing air.
Claim 9
Dependent Claim
86 words
Apparatus as set forth in claim 6, wherein said means for furnishing a first beam of light comprise a source of primary light having a wavelength between 800 nm and 2,000 nm, and optical splitting means for splitting said primary light into a first and second beam; further comprising second optical means for guiding said second beam to said photoelectric means; and wherein said photoelectric means comprise comparing means for comparing the light intensity of said dispersed light with the light intensity of said second beam.
Claim 10
Dependent Claim
37 words
Apparatus as claimed in claim 7 wherein said photoelectric means includes a light responsive receiver, and means for alternately impinging onto said receiver light of said second beam and said dispersed light passing through said second windoW.
Claim 11
Dependent Claim
32 words
Apparatus as claimed in claim 7 wherein said photoelectric means includes first and second light responsive receivers receiving dispersed light passing through said second window and light of said second beam, respectively.
Claim 12
Dependent Claim
33 words
Apparatus as claimed in claim 7 wherein said second optical means include two polarizing filters, and manually turnable means operating said filters for varying the intensity of the light of said second beam.
Claim 13
Dependent Claim
43 words
Apparatus as claimed in claim 7 wherein said chamber has a first wall perpendicular to said first beam and having said first window, and a second wall extending at an angle of substantially 70* to said first wall and having said second window.
Claim 14
Dependent Claim
27 words
Apparatus as claimed in claim 11, wherein said splitting means include a semitransparent mirror positioned so that said first and second beams are perpendicular to each other.
Claim 15
Dependent Claim
15 words
Apparatus as set forth in claim 6, wherein said photoelectric means comprise a silicon photodiode.
Claim 16
Dependent Claim
23 words
An arrangement as set forth in claim 6, wherein said chamber is a tubular chamber, open on two sides in the axial direction.
Claim 17
Dependent Claim
31 words
Apparatus as set forth in claim 14, further comprising light traps arranged in said chamber for preventing light deflected from the walls of said chamber from inpinging on said photoelectric means.
Claim 18
Dependent Claim
83 words
Apparatus as set forth in claim 6, further comprising modulating means for modulating said first light beam with a signal having a predetermined frequency, thereby creating a modulated light beam; wherein said photoelectric means comprise a photoelectric element for receiving said modulated light beam and furnishing a corresponding electrical signal; phase sensitive rectifier means connected to said photoelectric element for furnishing a rectifier output signal corresponding to said electrical signal; and indicator means for furnishing a visual indication of said rectifier output signal.
Claim 19
Dependent Claim
14 words
Apparatus as set forth in claim 16, wherein said indicator means comprise recorder means.
Claim 20
Dependent Claim
33 words
Arrangement as set forth in claim 16, further comprising analog-digital converter means connected between said indicator means and said phase sensitive rectifier means; and wherein said indicator means comprise light emitting diode means.
Claim 21
Dependent Claim
21 words
Apparatus as set forth in claim 16, further comprising calibrating means connected to the output of said phase sensitive rectifier means.
Claim 22
Dependent Claim
18 words
Apparatus as set forth in claim 19, wherein said calibrating means comprise amplifier means having an adjustable gain.
References Cited (Backward Citations)
US2076553A
Cited
US3317730A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |