US3976891A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photoelectric detector for smoke or the like
Assignee: Electra Tronics Inc
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Filing: 1975-02-18
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Granted: 1976-08-24
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Expires: 1995-02-18
Abstract
Abstract A photoelectric detector in which partial light beam obfuscation caused by dirty windows is balanced out by providing two beams of light passed through the gaseous medium in which smoke or the like is to be detected, the beam windows being subject to substantially equal accumulation thereon over a period of time of soot or the like which causes the windows to become dirty or clouded. The windows are so spaced that the respective beams pass different distances through the smoke. The relative beam intensities as received are compared by connecting photoresponsive devices in a bridge circuit. A meter is connected to the bridge and preferably calibrated to read directly in Ringlemann numbers.
Inventors
- 👤 Thomas F. Parkinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:55
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53; G01N21/534
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
288 words
A detector responsive to smoke or the like particles present in a gas, comprising a chamber through which the gas to be tested may pass, a first pair of straight, axially aligned spaced light transmitting rods having respective confronting inner end faces within said chamber, a second pair of straight, axially aligned spaced light transmitting rods having respective confronting inner end faces within said chamber, each of said rod inner end faces being subject to gradual obfuscation by the accumulation thereon of dust or the like particles from said gas, each of said rods of each said pair having a respective outer end face at its end opposite its said inner end face and said outer end faces being disposed outwardly of said chamber, light producing means including means to pass light into one rod of each said pair through its said outer end face and through the respective said one rod and out through such inner end face thereof and thence through the gas between such face and into such other rod of the respective pair through the said confronting inner end face thereof, the distance between said confronting inner end faces of said first pair of rods being at least about twice the distance between said confronting inner end faces of said second pair of rods, each of said rod end faces being flat and perpendicular to the axis of its respective said rod, a respective photoelectric responsive means disposed adjacently opposite each said outer end face of each of said other rods for receiving the light transmitted along the respective said other rod from their said respective said inner confronting faces, and bridge circuit means for comparing the respective responses of said photoelectric responsive means.
Claim 2
Dependent Claim
288 words
A detector responsive to smoke or the like particles present in a gas, comprising a chamber through which the gas to be tested may pass, a first pair of straight, axially aligned spaced light transmitting rods having respective confronting inner end faces within said chamber, a second pair of straight, axially aligned spaced light transmitting rods having respective confronting inner end faces within said chamber, each of said rod inner end faces being subject to gradual obfuscation by the accumulation thereon of dust or the like particles from said gas, each of said rods of each said pair having a respective outer end face at its end opposite its said inner end face and said outer end faces being disposed outwardly of said chamber, light producing means including means to pass light into one rod of each said pair through its said outer end face and through the respective said one rod and out through such inner end face thereof and thence through the gas between such face and into such other rod of the respective pair through the said confronting inner end face thereof, the distance between said confronting inner end faces of said first pair of rods being at least about twice the distance between said confronting inner end faces of said second pair of rods, each of said rod end faces being flat and perpendicular to the axis of its respective said rod, a respective photoelectric responsive means disposed adjacently opposite each said outer end face of each of said other rods for receiving the light transmitted along the respective said other rod from their said respective said inner confronting faces, and bridge circuit means for comparing the respective responses of said photoelectric responsive means.
Claim 3
Dependent Claim
53 words
The combination according to claim 1 and means to adjust the intensity of the light passed into said one rod of each said pair, said bridge circuit means comprising adjustable bridge balancing means and calibrated meter means for indicating the extent of bridge unbalance resulting from different responses of said photoelectric responsive elements.
Claim 4
Dependent Claim
93 words
The combination according to claim 1 wherein the axis of said first pair of rods is parallel to the axis of said second pair, the combined length dimension of the rods of said first pair being less than the combined length dimension of the rods of said second pair by an amount equal to the difference in said distances, and said outer end faces of said one rod of each said pair being adjacent each other and said outer end faces of said other rod of each said pair being adjacent each other.
Claim 5
Dependent Claim
251 words
A detector for detecting the presence of smoke in a gas comprising a chamber through which the gas to be tested may pass upwardly along at least one substantially uninterrupted path generally centrally of said chamber, a first and a second pair of straight, respectively axially aligned light transmitting rods, each pair including a light entrance rod and a light exit rod and each said rod having a first end face disposed outwardly of said chamber and a second end face disposed inwardly thereof, said second end faces of both said pairs being disposed in said path with such faces of each pair being disposed symmetrically on opposite sides of the center of the path, whereby all of said second end faces are substantially equally subject to gradual obfuscation by the accumulation of dust or the like particles thereon, each said end face being planar and normal to the axis of the respective said rod, the distance between the said second end faces of said first pair of rods being at least twice the distance between said second end faces of said second pair of rods, light source means outwardly of said chamber including means to direct light into said light entrance rod of each said pair through its respective said first end face, a respective photoelectric responsive element outwardly of said chamber adjacent and alignedly opposite said first end face of each said light exit rod, and bridge circuit means for comparing the respective reponses of said photoelectric responsive elements.
Claim 6
Dependent Claim
251 words
A detector for detecting the presence of smoke in a gas comprising a chamber through which the gas to be tested may pass upwardly along at least one substantially uninterrupted path generally centrally of said chamber, a first and a second pair of straight, respectively axially aligned light transmitting rods, each pair including a light entrance rod and a light exit rod and each said rod having a first end face disposed outwardly of said chamber and a second end face disposed inwardly thereof, said second end faces of both said pairs being disposed in said path with such faces of each pair being disposed symmetrically on opposite sides of the center of the path, whereby all of said second end faces are substantially equally subject to gradual obfuscation by the accumulation of dust or the like particles thereon, each said end face being planar and normal to the axis of the respective said rod, the distance between the said second end faces of said first pair of rods being at least twice the distance between said second end faces of said second pair of rods, light source means outwardly of said chamber including means to direct light into said light entrance rod of each said pair through its respective said first end face, a respective photoelectric responsive element outwardly of said chamber adjacent and alignedly opposite said first end face of each said light exit rod, and bridge circuit means for comparing the respective reponses of said photoelectric responsive elements.
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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) | 1979-08-24 | 1980-02-23 | 1980-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-24 | 1984-02-23 | 1984-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-24 | 1988-02-23 | 1988-08-24 | $7700.00 | Window Closed / Lapsed |