Patent US4489312A successfully refreshed from Google Patents.
US4489312A
Expired / Lapsed
US
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Selective test circuit for fire detectors
Assignee: Nittan Co Ltd
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Filing: 1982-04-14
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Granted: 1984-12-18
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Expires: 2002-04-14
Abstract
Abstract A circuit for selectively or extractively testing a fire detector among a plurality of fire detectors which are connected between an alarming line extending from the section relay of a receiving unit and a common line is disclosed. An inherent address code is allotted to each fire detector. When an address signal transmitted through the alarming line coincides with the allotted inherent address code, a coincidence signal is produced and in response to said coincidence signal a test voltage is generated for each fire detector.
Inventors
- 👤 Yukio Yoshizaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:27
CPC Classifications
G; G08; G08B; G08B29/00; G08B29/12; G08B29/14; G08B29/145
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
177 words
A circuit for selectively testing detectors connected between one of a plurality of alarming lines each extending from a section relay of a receiving unit and a common line comprising: an address-signal-sensing circuit for producing a coincidence signal when coincidence is sensed between an address signal transmitted through the alarming line and the inherent address code allotted to each fire detector beforehand; a test-voltage-generating circuit for generating a test voltage to be applied to each fire detector in response to said coincidence signal; a serial connection of a first Zenner diode and a condenser connected between the alarming line and the common line; and means for generating a resetting signal to reset the address-signal-sensing circuit and the test-voltage-generating circuit when the alarming line voltage is in excess of a predetermined value; whereby the condenser is charged at a voltage exceeding a predetermined value and, at the same time, resets the address-signal-sensing circuit and the test-voltage-generating circuit; and the voltage charged on the condenser acts as the power source for actuating the address-signal-sensing circuit and the test-voltage-generating circuit.
Claim 2
Dependent Claim
177 words
A circuit for selectively testing detectors connected between one of a plurality of alarming lines each extending from a section relay of a receiving unit and a common line comprising: an address-signal-sensing circuit for producing a coincidence signal when coincidence is sensed between an address signal transmitted through the alarming line and the inherent address code allotted to each fire detector beforehand; a test-voltage-generating circuit for generating a test voltage to be applied to each fire detector in response to said coincidence signal; a serial connection of a first Zenner diode and a condenser connected between the alarming line and the common line; and means for generating a resetting signal to reset the address-signal-sensing circuit and the test-voltage-generating circuit when the alarming line voltage is in excess of a predetermined value; whereby the condenser is charged at a voltage exceeding a predetermined value and, at the same time, resets the address-signal-sensing circuit and the test-voltage-generating circuit; and the voltage charged on the condenser acts as the power source for actuating the address-signal-sensing circuit and the test-voltage-generating circuit.
Claim 3
Dependent Claim
27 words
A circuit for selectively testing fire detectors as recited in claim 1, wherein the means for generating the resetting signal is comprised of a third Zenner diode.
Claim 4
Dependent Claim
86 words
A circuit for selectively testing fire detectors as recited in claim 1 or claim 2, which is further provided with means for producing detector-operation signal upon actuation of one of the section relays of the receiving unit; means for producing a finish signal when transmission of the address signal finishes; and a non-operation sensing circuit for producing a detector non-operation signal after receiving the finish signal and the detector-operation signal provided that no detector-operation signal is further received after transmission of the address signal has finished.
Claim 5
Dependent Claim
34 words
A circuit for selectively testing fire detectors as recited in claim 3, wherein a display device is provided for indicating the address code selectively sent forth in accordance with the detector non-operation sensing signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-12-18 | 1988-06-18 | 1988-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-18 | 1992-06-18 | 1992-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-18 | 1996-06-18 | 1996-12-18 | $7700.00 | Window Closed / Lapsed |