US3924252A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser smoke detection
Assignee: Espey Mfg and Electronics Corp
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Filing: 1974-08-29
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Granted: 1975-12-02
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Expires: 1994-08-29
Abstract
Abstract A smoke detecting system for detecting smoke in a building having two opposing walls having an amplitude modulated laser beam transmitter, including means for directing the beam along a predetermined path. Mounting means are connected to the laser beam transmitted, for mounting the laser beam transmitter and directing means on one opposing wall of the building, to direct a laser beam transmitted thereby toward the opposing wall of the building. There is a retroreflector, including means for mounting the same on the other opposing wall of a building in the path of the laser beam thereby causing the laser beam to be returned upon itself to the transmitter. A detector responsive to forward and backward scattered light provides a signal having a level which is proportional to the quantity of scattered light caused by any formed aerosol in the laser beam path, including mounting means mounting the detector so as to be disposed to read scattered light in the laser beam. Logic means are coupled to the detector for measuring the signal from the detector and for differentiating the signal to determine a rate of change in the quantity of scattered light. An alarm system is coupled to the logic means which has alarm operating means responsive to a predetermined rate of change in the logic means to operate the alarm system.
Inventors
- 👤 David Kenneth Duston
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:26
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/103; G08B17/107; G08B17/11; G08B17/113
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
228 words
A smoke detecting system for detecting smoke in a building having two opposing walls comprising in combination: a. an amplitude modulated laser beam transmitter including means for directing the beam along a predetermined path; b. first mounting means connected to said laser beam transmitted for mounting said laser beam transmitter and directing means on one opposing wall of said building to direct a laser beam transmitted thereby toward the opposing wall of said building; c. a retroreflector including means for mounting the same on the other opposing wall of said building in the path of said laser beam thereby causing said laser beam to be returned upon itself to the transmitter; d. a detector responsive to forward and backward scattered light to provide a signal having a level which is proportional to the quantity of scattered light caused by any formed aerosol in the laser beam path, including Second mounting means mounting the detector so as to be disposed to read scattered light in said laser beam; e. logic means coupled to said detector for measuring the signal from the detector and for differentiating the signal to determine a rate of change in the quantity of scattered light; f. an alarm system, coupled to said logic means; and g. alarm operating means responsive to a predetermined rate of change in said logic means to operate said alarm system.
Claim 2
Dependent Claim
228 words
A smoke detecting system for detecting smoke in a building having two opposing walls comprising in combination: a. an amplitude modulated laser beam transmitter including means for directing the beam along a predetermined path; b. first mounting means connected to said laser beam transmitted for mounting said laser beam transmitter and directing means on one opposing wall of said building to direct a laser beam transmitted thereby toward the opposing wall of said building; c. a retroreflector including means for mounting the same on the other opposing wall of said building in the path of said laser beam thereby causing said laser beam to be returned upon itself to the transmitter; d. a detector responsive to forward and backward scattered light to provide a signal having a level which is proportional to the quantity of scattered light caused by any formed aerosol in the laser beam path, including Second mounting means mounting the detector so as to be disposed to read scattered light in said laser beam; e. logic means coupled to said detector for measuring the signal from the detector and for differentiating the signal to determine a rate of change in the quantity of scattered light; f. an alarm system, coupled to said logic means; and g. alarm operating means responsive to a predetermined rate of change in said logic means to operate said alarm system.
Claim 3
Dependent Claim
129 words
The system as claimed in claim 1 with the addition of a device for determining if the transmitted laser beam is being redirected along itself by said retro-reflector, comprising: a. a beam splitter mounted in the path of the laser beam; b. a second detector including circuitry responsive to a directly returned laser beam having mounting means for mounting said second detector in the intended path of the returned laser beam, said second detector in the intended path of the returned laser beam, said second detector circuitry emitting a signal proportional to the amount of beam returned; c. an alarm and switching device coupled to said second detector circuitry including a threshold circuit activated when the level of signal from the return beam detector falls below a predetermined value.
Claim 4
Dependent Claim
122 words
A smoke system for detecting smoke in a building having opposing walls comprising in combination: a. laser beam transmitter (11a) including means for mounting the same at one wall of the building; b. retro-reflector (15a) including means for mounting the same at the other wall of the building; c. detector means (19a) including light collecting and focusing means for reading light scattered by particles passing through said reflected laser beam; d. logic means (22a) coupled to said detector means and responsive to a change in level of said scattered light to indicating an atmospheric change (smoke); and, e. alarm means coupled to said logic means to be activated thereby in response to the detection of change in level of said scattered light.
Claim 5
Dependent Claim
122 words
A smoke system for detecting smoke in a building having opposing walls comprising in combination: a. laser beam transmitter (11a) including means for mounting the same at one wall of the building; b. retro-reflector (15a) including means for mounting the same at the other wall of the building; c. detector means (19a) including light collecting and focusing means for reading light scattered by particles passing through said reflected laser beam; d. logic means (22a) coupled to said detector means and responsive to a change in level of said scattered light to indicating an atmospheric change (smoke); and, e. alarm means coupled to said logic means to be activated thereby in response to the detection of change in level of said scattered light.
Claim 6
Dependent Claim
100 words
An alarm system responsive to reflected light comprising in combination: a. an amplitude modulated laser beam transmitter (11a) including means for mounting the same at one wall of a building having two opposing walls; b. a detector (19a) including light collecting and focusing means for reading light scattered by particles passing through said laser beam including mounting means for mounting the detector on the opposing wall; c. logic means (22a) coupled to said detector and responsive to a change in level; and, d. alarm means coupled to said logic means to be activated thereby in response to the detector signal.
Claim 7
Dependent Claim
100 words
An alarm system responsive to reflected light comprising in combination: a. an amplitude modulated laser beam transmitter (11a) including means for mounting the same at one wall of a building having two opposing walls; b. a detector (19a) including light collecting and focusing means for reading light scattered by particles passing through said laser beam including mounting means for mounting the detector on the opposing wall; c. logic means (22a) coupled to said detector and responsive to a change in level; and, d. alarm means coupled to said logic means to be activated thereby in response to the detector signal.
Claim 8
Dependent Claim
192 words
A smoke detecting system for detecting smoke in a building having two opposing walls comprising in combination: a. an amplitude modulated laser beam transmitter including directing means for directing the beam along a predetermined path; b. first mounting means for mounting said laser beam transmitter and directing means on one wall of said building to direct a laser beam transmitted thereby toward the opposing wall of said building; c. a detector including signal giving means responsive to forward and backward scattered light to provide a signal having a level which is proportional to the quantity of scattered light caused by an aerosol in the laser beam; including second mounting means for mounting the detector on the wall opposing the transmitter to detect the forward scattered laser beam and the direct laser beam; d. logic means coupled to the detector for measuring the signal from the detector and differentiating the signal to determine a rate of change in the quantity of scattered light; e. an alarm system coupled to the logic means; and, f. alarm operating means responsive to a predetermined rate of change in said logic means to operate said alarm system.
Claim 9
Dependent Claim
192 words
A smoke detecting system for detecting smoke in a building having two opposing walls comprising in combination: a. an amplitude modulated laser beam transmitter including directing means for directing the beam along a predetermined path; b. first mounting means for mounting said laser beam transmitter and directing means on one wall of said building to direct a laser beam transmitted thereby toward the opposing wall of said building; c. a detector including signal giving means responsive to forward and backward scattered light to provide a signal having a level which is proportional to the quantity of scattered light caused by an aerosol in the laser beam; including second mounting means for mounting the detector on the wall opposing the transmitter to detect the forward scattered laser beam and the direct laser beam; d. logic means coupled to the detector for measuring the signal from the detector and differentiating the signal to determine a rate of change in the quantity of scattered light; e. an alarm system coupled to the logic means; and, f. alarm operating means responsive to a predetermined rate of change in said logic means to operate said alarm system.
Claim 10
Dependent Claim
50 words
The system of claim 1 wherein the said detector includeS circuit means for analyzing and gating the detected signal to filter extraneous signals so that the signal emitted by the detector is responsive only to the scattered light caused by the frequency phase and amplitude modulation of the laser beam.
References Cited (Backward Citations)
US3406289A
Cited
US3447370A
Cited
US3566385A
Cited
US3723746A
Cited
US3683352A
Cited
US3788742A
Cited
US3711210A
Cited
US3820901A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |