US3760397A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alarm system
Assignee: Individual
•
Filing: 1970-11-17
•
Granted: 1973-09-18
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Expires: 1990-11-17
Abstract
Abstract A photocell-activated intruder alarm system, including a control circuit adapted to automatically adjust system operation to ambient light conditions and adapted to facilitate bore sighting of the apparatus on an external light source. A time delay inherently present in said circuit provides delay in arming of the alarm after activation of the system, whereby a user may remove himself from the protected area without discharging the alarm.
Inventors
- 👤 J Taggart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:33
CPC Classifications
G; G08; G08B; G08B29/00; G08B29/18; G08B29/20; G08B29/24; G08B13/00; G08B13/18; G08B29/185
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
196 words
A light sensor-activated intruder alarm system, comprising: a. light sensor means sightable on a spaced light source; b. a control unit connected to receive the output from said light sensor means, said unit including means for providing a signal output at a relatively fixed quiescent level in the presence of slow light changes at said sensor and at levels detectably removed from said quiescent level in the presence of transient light changes at said sensor, said means comprising a self-stabilizing DC closed loop circuit in series with said sensor, said loop including amplifier means and having a relatively long time constant with respect to said transient signals, but not with respect to said slow light changes sought to be compensated; c. bore sight detector means connected to said signal output of said loop, said means being adapted to provide indication of sudden incReases in light at said sensor, whereby sighting of said sensor on said light source may be detected; and d. alarm means connected to said signal output, said means being adapted to provide indication of sudden decreases in light at said sensor, whereby intrusion between said sensor and said light source may be detected.
Claim 2
Dependent Claim
196 words
A light sensor-activated intruder alarm system, comprising: a. light sensor means sightable on a spaced light source; b. a control unit connected to receive the output from said light sensor means, said unit including means for providing a signal output at a relatively fixed quiescent level in the presence of slow light changes at said sensor and at levels detectably removed from said quiescent level in the presence of transient light changes at said sensor, said means comprising a self-stabilizing DC closed loop circuit in series with said sensor, said loop including amplifier means and having a relatively long time constant with respect to said transient signals, but not with respect to said slow light changes sought to be compensated; c. bore sight detector means connected to said signal output of said loop, said means being adapted to provide indication of sudden incReases in light at said sensor, whereby sighting of said sensor on said light source may be detected; and d. alarm means connected to said signal output, said means being adapted to provide indication of sudden decreases in light at said sensor, whereby intrusion between said sensor and said light source may be detected.
Claim 3
Dependent Claim
37 words
Apparatus in accordance with claim 1, wherein said bore sight detection means comprises an indicator lamp and D.C. amplifier means for receiving said signal output and providing power to said lamp in accordance with said signal output.
Claim 4
Dependent Claim
73 words
Apparatus in accordance with claim 1 wherein said sensor comprises a photocell, the resistance of which varies in response to the incident light level and wherein said loop includes differential amplifier means, the output from one side of said photocell being one input to said differential amplifier means, and the output from said differential amplifier means being provided in series to the other side of said photocell for feeding back in said loop.
Claim 5
Dependent Claim
68 words
Apparatus in accordance with claim 3, wherein said control unit includes power switching means and means for switching said system to an arm mode, said RC circuit means having a sufficient time constant to provide upon switching to said arm mode a sufficient delay in said signal output attaining said quiescent level to permit the system operator to remove himself from the intruder detection zone of said system.
Claim 6
Dependent Claim
12 words
Apparatus in accordance with claim 1 including a plurality of light sensors.
Claim 7
Dependent Claim
41 words
Apparatus in accordance with claim 5 including a plurality of said alarm means, at least one of said means together with said control unit, bore sight indicator, and at least one of said light sensors being contained within a compact module.
Claim 8
Dependent Claim
46 words
Apparatus in accordance with claim 6, further including smoke/heat detector means connected to said control unit, said control unit further including means adapted to discharge at least one of said alarm means upon receipt of a signal from said detector means indicative of smoke or heat.
Claim 9
Dependent Claim
23 words
Apparatus in accordance with claim 3, wherein an emitter follower and RC circuit means couples said differential amplifier means back to said sensor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-17 | 1977-03-19 | 1977-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-17 | 1981-03-19 | 1981-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-17 | 1985-03-19 | 1985-09-18 | $7700.00 | Window Closed / Lapsed |