US3706987A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alarm loop circuit system with light-emitting current-detection means
Assignee: Bay Alarm Co
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Filing: 1971-08-23
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Granted: 1972-12-19
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Expires: 1991-08-23
Abstract
Abstract An alarm system comprising a loop circuit having several remote, code-generating switches connected in series, and a receiving station connected to the loop ends which applies an electrical potential to the loop. Wherein the receiving station provides, in series with the loop ends, light-emitting diodes which emit light when current flows through the loop onto corresponding photosensitive circuit elements, such as photo transistors, which are connected, through amplifiers, to a controlled device, such as printing relays and/or further transmission means which indicate which diode emits more or less light than the other. Preferably, the amplifier outputs are connected through a time-delay circuit which produces an ''''off normal'''' signal if either of the diodes has a reduced light output for longer than a predetermined time, such as one to several seconds; this signal may energize another light-emitting diode or switch the power supply to apply a different voltage to a loop end.
Inventors
- 👤 Bruce A Westphal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:01
CPC Classifications
G; G08; G08B; G08B25/00; G08B25/01; G08B25/04; G08B25/045
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
95 words
In an alarm system which comprises a loop circuit having coded switching stations connected in series and a receiving station connected to the loop ends and including means for applying an electrical potential to the loop circuit, the improvement wherein the receiving station includes in series with at least one loop end a light-emitting circuit element which emits light in response to current flow, a photo-sensitive circuit element positioned to receive light from the lightemitting element, and an output circuit connected to the photosensitive element for controlling a device in accordance with the signal therein.
Claim 2
Dependent Claim
95 words
In an alarm system which comprises a loop circuit having coded switching stations connected in series and a receiving station connected to the loop ends and including means for applying an electrical potential to the loop circuit, the improvement wherein the receiving station includes in series with at least one loop end a light-emitting circuit element which emits light in response to current flow, a photo-sensitive circuit element positioned to receive light from the lightemitting element, and an output circuit connected to the photosensitive element for controlling a device in accordance with the signal therein.
Claim 3
Dependent Claim
33 words
The alarm system according to claim 1 which includes a light-emitting circuit element in series with each loop end, there being a photo-sensitive element and an output circuit associated with each light-emitting element.
Claim 4
Dependent Claim
45 words
The alarm system according to claim 2 wherein said photo-sensitive devices are connected to said output circuits through amplifiers and said output circuits are connected to the coils of relay means which control printing of a record of the coded operations of the switching stations.
Claim 5
Dependent Claim
23 words
The alarm system according to claim 1 wherein said light-emitting element is a light-emitting diode and the photo-sensitive element is a photo transistor.
Claim 6
Dependent Claim
60 words
The alarm system according to claim 1 wherein said output circuit is connected to the input of a time-delay circuit having a delay longer than the period of operation of said switching stations and an output circuit connected to the time-delay circuit which is energized only when the signal from the photo-sensitive element persists for longer than a predetermined time.
Claim 7
Dependent Claim
21 words
The alarm system according to claim 5 wherein said output circuit from the time-delay circuit is connected to an alarm device.
Claim 8
Dependent Claim
63 words
The alarm system according to claim 5 wherein there is a light-emitting circuit element in series with each loop end, there are a photo-sensitive circuit element and a separate output circuit associated with each light-emitting element, and an ''''or'''' gate having its inputs connected to said separate output circuits and its common output circuit connected to the said input of the time-delay circuit.
Claim 9
Dependent Claim
42 words
The alarm system according to claim 7 wherein at least one of said photo-sensitive circuit elements is, additionally, connected through an amplifier to the coil of relay means which controls printing of a record of the coded operations of the switching stations.
Claim 10
Dependent Claim
32 words
In combination with the alarm system according to claim 5, switching means in said receiving station for altering the electrical potential which is applied to at least one of said loop ends.
Claim 11
Dependent Claim
86 words
The alarm system according to claim 5, wherein said receiving station includes switching means for normally applying a direct current potential to said loop ends and grounding one of said loop ends to earth, said switching means being responsive to the signal in said output circuit from the time-delay circuit for opening the connection between ground and said one loop end and applying to said one loop end an electrical potential, and for restoring said switching means to normal conditions upon cessation of the said signal.
References Cited (Backward Citations)
US3626403A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-19 | 1976-06-19 | 1976-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-19 | 1980-06-19 | 1980-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-19 | 1984-06-19 | 1984-12-19 | $7700.00 | Window Closed / Lapsed |