Title: Photoelectric detector for smoke or the like

Do you think this is a good invention? Vote now:

Votes so far: For:(0) Against:(0)
Claims: What is claimed as new and what it is desired to secure by Letters Patent of the United States is:

1. 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.

2. 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.

3. 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.

4. 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.

Other info:

Inventors: Parkinson, Thomas F. (Columbia, MO, US)

Application Number: 550626
Filing Date: 1975-02-18
Publication_date: 1976-08-24
Assignee: Electra-Tronics, Inc. (Sarasota, FL)
Primary Class(es): 250/575 250/227.11, 340/630, 356/439
Other Classes:
US Patent Ref:

3447370	Jun, 1969	Tanzman	356/207.
3619624	Nov, 1971	Sorenson	250/575.
3652850	Mar, 1972	Briggs	356/208.
3677652	Jul, 1972	Little	250/573.
3772525	Nov, 1973	Goodwin	250/575.
3784307	Jan, 1974	Jackson et al.	250/575.
3805066	Apr, 1974	Chijuma et al.	340/237.
3809913	May, 1974	Prellwitz	356/207.

Other Refs:
Primary Examiner: Smith, Alfred E.
Assistant Examiner: Nelms, D. C.
Attorney: Baldwin; George H., Yeager; Arthur G.