Patent US3987428A successfully refreshed from Google Patents.
US3987428A
Expired / Lapsed
US
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Optical laser security system
Assignee: Lee Raymond Organization Inc
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Filing: 1975-06-16
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Granted: 1976-10-19
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Expires: 1995-06-16
Abstract
Abstract An optical laser is operated in a continuous mode and modulated by a random noise generator. The laser beam is split into parallel beams which are reflected throughout the area by mirrors and each directed into a photo sensitive electronic receptor circuit which electronically combines the output signals of the parallel beams of laser light. The combined output is electronically compared with the signal employed to modulate the laser beams, with an alarm circuit triggered when any difference is detected between the output signal generated by the laser beams and the input modulating signal.
Inventors
- 👤 David John Todeschini
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:50
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/18; G08B13/181; G08B13/183; G08B13/184
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
188 words
A security system for giving an alarm when an intruder in a protected area interrupts a laser beam of light, said system comprising a modulated laser which emits a continuous modulated beam of coherent light, a signal generator which modulates the said laser, a photo-electric light detector which transforms the light emitted by the laser to electronic signals, a dual operational amplifier which transmits the output of the signal generator both to the laser and to a Compare circuit, said Compare circuit also connected to the output of the photo-electric light detector circuit so as to compare the signal received by the said light detector circuit from the laser beam, with the laser modulation signal produced by the signal generator, and alarm triggering means connected to the Compare circuit, which means are energized when the Compare circuit distinguishes a difference between the signal produced by the signal generator and the signal received through the photo-electric light detector, in which the signal generator is a random noise generator connected to a Schmitt Trigger circuit, which Schmitt Trigger circuit converts the output of said random noise generator into digital pulses.
Claim 2
Dependent Claim
188 words
A security system for giving an alarm when an intruder in a protected area interrupts a laser beam of light, said system comprising a modulated laser which emits a continuous modulated beam of coherent light, a signal generator which modulates the said laser, a photo-electric light detector which transforms the light emitted by the laser to electronic signals, a dual operational amplifier which transmits the output of the signal generator both to the laser and to a Compare circuit, said Compare circuit also connected to the output of the photo-electric light detector circuit so as to compare the signal received by the said light detector circuit from the laser beam, with the laser modulation signal produced by the signal generator, and alarm triggering means connected to the Compare circuit, which means are energized when the Compare circuit distinguishes a difference between the signal produced by the signal generator and the signal received through the photo-electric light detector, in which the signal generator is a random noise generator connected to a Schmitt Trigger circuit, which Schmitt Trigger circuit converts the output of said random noise generator into digital pulses.
Claim 3
Dependent Claim
66 words
The combination as recited in claim 1 in which the laser beam is split into two or more parallel beams, with each beam focused on an individual photo-electric light detector and with an OR circuit that adds the output of the circuits of the individual light detectors so that a momentary interruption of one of the multiple parallel laser beams will not produce an alarm effect.
References Cited (Backward Citations)
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US3623057A
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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) | 1979-10-19 | 1980-04-19 | 1980-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-19 | 1984-04-19 | 1984-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-19 | 1988-04-19 | 1988-10-19 | $7700.00 | Window Closed / Lapsed |