Communications: electrical – Condition responsive indicating system – With particular system function
Patent
1997-06-05
1998-09-29
Hofsass, Jeffery A.
Communications: electrical
Condition responsive indicating system
With particular system function
340511, 340514, 340628, G08B 2900
Patent
active
058150757
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to fire detectors including a non-volatile memory.
More particularly, the invention relates to a fire detector comprising: representative of at least one characteristic element specific to said fire detector; and detect the existence of a fire in the vicinity of the fire detector, said fire sensor delivering an analog electrical signal referred to as a "measurement" signal to the CPU, the value of the measurement signal being representative of the physical magnitude measured by the fire sensor, the above-mentioned characteristic element including a normal value iO for the measurement signal in the absence of a fire.
BACKGROUND OF THE INVENTION
Such a fire detector is disclosed in the document: Research Disclosure No. 357, January 1995 (Emsworth, GB, "Smoke detector with dirty chamber signal").
Fire detectors of the kind in question need to be maintained at regular time intervals in order to keep them reliable.
Nevertheless, when several types of fire detector are installed in the same building, or when the fire detectors are installed at different dates, it can happen that detectors need to be maintained at different dates.
Managing such maintenance then becomes complex, particularly since it can happen that the fire detectors were interchanged or replaced on the last occasion they were dismantled for maintenance: under such circumstances, it is extremely difficult for maintenance personnel to identify exactly which fire detectors need to be maintained at a given date, particularly since such detectors are generally difficult of access.
Also, it is usual for maintenance services to be content with observing the date of the last occasion on which a fire detector was dismantled for maintenance purposes, without always systematically verifying in reliable manner that the maintenance was effective. Consequently, if the periodic maintenance of a fire detector is poorly performed, it can subsequently give unreliable information, at least until the next date on which it is dismantled for maintenance.
OBJECTS AND SUMMARY OF THE INVENTION
A particular object of the present invention is to mitigate these drawbacks.
To this end, according to the invention, a fire detector of the kind in question further includes interface means giving access to the contents of the non-volatile memory without dismantling the fire detector, (i.e. in particular without removing its base, or without unscrewing it from the ceiling, or without opening its housing), the non-volatile memory further includes dates on which maintenance operations of said fire detector have been preformed, and the CPU is programmed to compare the measurement signal with the normal value iO of the measurement signal on each occasion that it receives an instruction from the interface means to record a maintenance date, and to refuse to record it whenever the measurement signal does not lie within the range iO-.DELTA.1 to iO+.DELTA.2, where .DELTA.1 and .DELTA.2 are predetermined values.
By means of these dispositions, maintenance services can easily access at least the most recent date of preventative maintenance on each fire detector, and can do this without needing to dismantle the fire detector, which is often difficult to access since it is located at a height.
Maintenance services can thus determine easily and reliably whether a particular fire detector needs preventative maintenance.
Also, because the new maintenance date on each operation of preventative maintenance is recorded in the non-volatile memory of the detector only if said maintenance has made it possible to bring the measurement signal in the absence of fire to a value that is sufficiently close to the normal value iO, it is easy to detect which fire detectors have been poorly maintained or insufficiently maintained, and this can be done without waiting for the next round of preventative maintenance. Consequently, the reliability of fire detection is improved.
In preferred embodiments of the invention, use is also made of one or more of
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French Search Report, dated 21 Apr., 1995, French Appl. No. FR9409476.
International Search Report, Appl. No. PCT/FR95/01011.
Havant, "Smoke Detector With Dirty Chamber Signal", Reasearch Disclosure No. 357, Jan. 1994, Emsworth, GB, pp. 8-13.
Tavora, "The Remote Link Unit-An Advanced Remote Terminal Concept," IEEE Transactions on Industrial Electronics, vol. 26, No. 3, New York (Aug. 26, 1979).
Mayr et al., "Module Documentation Chip," IBM Technical Disclosure Bulletin, vol. 26, No. 8, Jan. 1984.
Lewiner Jacques
Smycz Eugeniusz
Hofsass Jeffery A.
Huang Shiong
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