US4006988A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photo-electric depth or turbidity meter for fluid suspensions
Assignee: Individual
•
Filing: 1975-03-26
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Granted: 1977-02-08
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Expires: 1995-03-26
Abstract
Abstract An instrument functioning as either a turbidimeter or as a depth meter for measuring the distance from the instrument to the level of a turbid fluid. A light source provided with an optical system emits a beam of light to the fluid, and the volume or "beam of vision" viewed by a photo-cell likewise provided with an optical system intersects said beam of light. The two beams include a relatively small angle so that a tapered or conical volume of intersection in the fluid is obtained. Thus, the quantity of light scattered or reflected within this volume and reaching the photo-cell is dependent on the turbibity and the position of this level. The light emitted by the light source is modulated at a relatively high frequency. The output of the photo-cell passes through a frequency filter and is, then, indicated or recorded as a measure of turbidity or of depth of said layer.
Inventors
- 👤 Per-Henric Sebastian Tamm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:24
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53; G01C; G01C3/00; G01C3/02; G01C3/06; G01C3/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
183 words
An apparatus for measuring the level of turbidity in a fluid comprising: a fluidtight housing for placement in said fluid and having an optical window; a light source mounted in said housing for producing a beam of light which is directed via said window into said fluid and which diverges about an axis at an angle of between 3 and 10°; photosensitive means mounted in said housing separated from said light source and having a field of view into said fluid which diverges about an axis at an angle of between 3 and 10° and which intersects said divergent beam of light in said fluid, the area of intersection being symmetrically disposed about an axis extending away from said light source and the angle between the axes of said beam and field being no greater than 25° for measuring the light in said field scattered or reflected by particles causing said turbidity condition and producing an electrical turbidity signal which varies as a function of the cross-sectional area of said intersection at the level of said particles and, hence, the level of turbidity.
Claim 2
Independent Claim
183 words
An apparatus for measuring the level of turbidity in a fluid comprising: a fluidtight housing for placement in said fluid and having an optical window; a light source mounted in said housing for producing a beam of light which is directed via said window into said fluid and which diverges about an axis at an angle of between 3 and 10°; photosensitive means mounted in said housing separated from said light source and having a field of view into said fluid which diverges about an axis at an angle of between 3 and 10° and which intersects said divergent beam of light in said fluid, the area of intersection being symmetrically disposed about an axis extending away from said light source and the angle between the axes of said beam and field being no greater than 25° for measuring the light in said field scattered or reflected by particles causing said turbidity condition and producing an electrical turbidity signal which varies as a function of the cross-sectional area of said intersection at the level of said particles and, hence, the level of turbidity.
Claim 3
Dependent Claim
24 words
An apparatus as in claim 1, further including meter means connected to said photosensitive means for displaying the condition indicated by said electrical signal.
Claim 4
Dependent Claim
37 words
An apparatus as in claim 1 further including an optical screen extending outward from said window between said beam and said field of view for preventing direct inpingement of light from said source onto said photosensitive means.
Claim 5
Dependent Claim
72 words
An apparatus as in claim 1 including means for supplying an A.C. current to said source and said photosensitive means, and means connected to said source for modulating said A.C. signal at a frequency several times higher than the frequency of said A.C. signal and a filter connected to said photosensitive means having a lower limit frequency several times higher than the frequency of said A.C. signal but below the modulating frequency.
Claim 6
Dependent Claim
36 words
An apparatus as in claim 4, including an amplifier connected to said filter having a manually adjustable gain such that the output of said amplifier represents a zero level at a nominal zero for turbidity level.
Claim 7
Dependent Claim
21 words
An apparatus as in claim 1, wherein said light source is a luminous diode and said photosensitive means is a photocell.
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) | 1980-02-08 | 1980-08-09 | 1981-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-08 | 1984-08-09 | 1985-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-08 | 1988-08-09 | 1989-02-08 | $7700.00 | Window Closed / Lapsed |