EP0772850B1 - Fire detector with a non-volatile memory - Google Patents

Description

The present invention relates to detectors fire including non-volatile memory.

• une unité centrale comportant une mémoire rémanente dans laquelle est enregistré un code représentatif d'au moins un élément caractéristique propre audit détecteur d'incendie,
• un capteur d'incendie qui mesure une grandeur physique dont les variations permettent de détecteur l'existence d'un incendie au voisinage du détecteur d'incendie, ce capteur d'incendie fournissant à l'unité centrale un signal électrique analogique, dit signal de mesure, qui a une valeur représentative de la grandeur physique mesurée par le capteur d'incendie, l'élément caractéristique susmentionné incluant une valeur normale i0 du signal de mesure en l'absence d'incendie.

More particularly, the invention relates to a fire detector comprising:

• a central unit comprising a non-volatile memory in which a code representative of at least one characteristic element specific to said fire detector is recorded,
• a fire sensor which measures a physical quantity, the variations of which make it possible to detect the existence of a fire in the vicinity of the fire detector, this fire sensor supplying the central unit with an analog electrical signal, known as the measurement, which has a value representative of the physical quantity measured by the fire sensor, the aforementioned characteristic element including a normal value i0 of the measurement signal in the absence of fire.

Such a fire detector is disclosed in the document: Research Disclosure No. 357, January 1994 (Emsworth, GB, "Smoke detector with dirty chamber signal").

Fire detectors of the type in question must be maintained at regular time intervals, from way to stay reliable.

However, when several types of detectors are installed in the same building, or when these fire detectors were installed on dates different, these detectors may need to be serviced on different dates.

The management of these interviews then becomes complex, especially since fire detectors can possibly have been reversed or replaced during their last disassembly for maintenance: in this case, it is extremely difficult for maintenance technicians identify exactly the fire detectors that must be maintained on a given date, especially since these detectors are generally difficult to access.

In addition, usually, the services of maintenance only note the date of the last disassembly of a fire detector for maintenance, without always check systematically and reliably the effectiveness of this interview. Therefore, if the interview of a fire detector was badly done, it can then give unreliable indications at least until its next disassembly date for maintenance.

The object of the present invention, which is defined by the claims, is in particular to overcome these drawbacks.

For this purpose, according to the invention, a fire detector of the genre in question is essentially characterized in that the fire detector further includes interface means allowing access to the contents of the memory retentive without dismantling the fire detector, (i.e. in particular without removing it from its base, or without unscrew from the ceiling, or without opening its case), in that non-volatile memory also includes dates when have been carried out maintenance operations of said fire detector, and in that the central unit is programmed to compare the measurement signal to the value normal iO of the measurement signal each time it receives interface means an instruction to record a maintenance date, and to refuse this registration if the measurement signal is not between i0 - Δ1 and i0 + Δ2, where Δ1 and Δ2 are predetermined values.

Thanks to these provisions, maintenance services can easily access at least the last date of preventive maintenance of each fire detector, and this without having to dismantle the fire detector, often difficult to access since it is placed high up.

Maintenance services can therefore determine easily reliably if a particular fire detector must be subject to preventive maintenance.

In addition, the fact that during each operation of preventive maintenance, the new maintenance date is only written to the non-volatile memory of the detector if this maintenance made it possible to bring the measurement signal back the absence of fire at a value sufficiently close to the normal value i0, it is easy to locate the detectors for which maintenance was poorly done or turns out to be insufficient, without waiting for the next Preventive maintenance. Therefore, the reliability of the fire detection is improved.

• les moyens d'interface comprennent un connecteur relié à l'unité centrale, le connecteur pouvant recevoir un connecteur complémentaire relié à un appareil extérieur en vue de faire communiquer cet appareil extérieur avec l'unité centrale ;
• les moyens d'interface comprennent une liaison de communication entre le détecteur d'incendie et une centrale d'alarme : ce mode de réalisation est particulièrement avantageux, dans la mesure où il permet de connaítre, à partir de la centrale d'alarme, au moins la date de dernière maintenance de tous les détecteurs d'incendie reliés à cette centrale d'alarme ;
• l'élément caractéristique susmentionné inclut en outre une date de fabrication dudit détecteur,
• l'élément caractéristique susmentionné inclut en outre un numéro d'identification propre audit détecteur,
• la mémoire rémanente contient en outre, pour chaque date de maintenance, la valeur du signal de mesure transmis à l'unité centrale par le capteur d'incendie au moment de l'enregistrement de ladite date de mesure ;
• la valeur normale i0 du signal de mesure est une valeur mesurée en l'absence d'incendie pour le capteur d'incendie considéré, lors de sa fabrication ou de sa première mise en service.

In preferred embodiments of the invention, use is also made of one and / or the other of the following arrangements:

• the interface means comprise a connector connected to the central unit, the connector being able to receive a complementary connector connected to an external device in order to make this external device communicate with the central unit;
• the interface means comprise a communication link between the fire detector and an alarm center: this embodiment is particularly advantageous, insofar as it makes it possible to know, from the alarm center, at minus the date of the last maintenance of all the fire detectors connected to this alarm center;
• the aforementioned characteristic element further includes a date of manufacture of said detector,
• the aforementioned characteristic element also includes an identification number specific to said detector,
• the non-volatile memory also contains, for each maintenance date, the value of the measurement signal transmitted to the central unit by the fire sensor at the time of recording of said measurement date;
• the normal value i0 of the measurement signal is a value measured in the absence of fire for the fire sensor in question, during its manufacture or when it is put into service for the first time.

Other characteristics and advantages of the invention will appear during the detailed description following of one of its embodiments, given as non-limiting example, with reference to the attached drawing.

In the drawing, the single figure represents a fire detector according to an embodiment of the invention, connected to an alarm center and capable of to be connected to an external interface box.

The fire detector 1 according to the invention comprises a microprocessor 2 including a non-volatile memory 2a in particular EEPROM type. More generally, the fire sensor 1 has a central unit which includes a circuit programmable electronics such as a microprocessor and a non-volatile memory which may or may not be included in the microprocessor.

Microprocessor 2 has an analog input 2a which is connected to a fire sensor 3, which sensor measure a physical quantity whose variations allow to detect the existence of a fire in the vicinity of the fire detector 1. The fire sensor 3 can be an ionic smoke sensor, an optical sensor of smoke, a thermal sensor, or other.

Fire sensor 3 sends to analog input 2a of the microprocessor an analog electrical signal i, called measurement signal, the value of which is representative of the physical quantity measured by the fire sensor. The value of signal i which is representative of the quantity measured physics can be for example the intensity or the voltage of this signal.

Microprocessor 2 compares the measurement signal i at a normal value i0 of this measurement signal in the absence fire, and when the measurement signal i is sufficient far from its normal value i0, microprocessor 2 determines the existence of a fire in the vicinity of the detector fire 1, and it reacts for example by sending a alarm message to an alarm center 4, via a link 5, which preferably also allows send messages from alarm center 4 to the microprocessor 2.

The non-volatile memory 2a of the microprocessor 2 comprises not only the normal value iO mentioned above, measured immediately after manufacture of the fire detector 1 or after its first commissioning, but still the date maintenance operations undergone by the detector, or minus the date of the last maintenance operation. Of moreover, the non-volatile memory 2a preferably also includes the date of manufacture and the serial number specific to the fire detector 1.

This data is accessible to a user from the alarm center 4, which can be provided for this by example of a screen 4a and a keyboard 4b.

It is thus possible to plan very easily maintenance of the various fire detectors of a complete installation, and check the references of a particular fire detector in this installation, without having to physically access this detector, which is usually placed under a ceiling, so is hardly accessible.

In addition, the fire detector 1 includes a connector 6 connected to microprocessor 2.

During detector maintenance operations fire 1, when said detector is removed, it is thus possible to connect to connector 6 a connector complementary 7 which is connected to an interface box 8 via a cable 9, the interface box 8 comprising for example a screen 8a and a keyboard 8b.

Thus, at the end of maintenance operations, it can be stored in non-volatile memory 2a, via the interface box 8, the date said maintenance operations.

Microprocessor 2 is programmed to compare the value of the measurement signal i at said normal value i0 at time when said microprocessor receives interface box 8 the order to record the maintenance date.

If this value i of the measurement signal is not between values i0 - Δ1 and i0 + Δ2, where Δ1 and Δ2 are predetermined values (for example, Δ1 and Δ2 can be worth 5% of i0), microprocessor 2 is programmed to refuse the recording of the maintenance date in nonvolatile memory 2a, and to send to interface box 8 a message indicating this refusal.

Thus, microprocessor 2 can control the efficiency maintenance operations, and this efficiency is also controllable from alarm center 4 if the fire detector was reassembled despite refusal to register from the last maintenance date.

As it goes without saying, and as it results from elsewhere already from the above, the invention is in no way limited to those of its modes of application and embodiments which have been more specifically contemplated; she embraces it, at otherwise, all variants that are claimed.

Claims (7)

1. A fire detector (1) comprising:

   a CPU (2) including a non-volatile memory (2a) in which a code is recorded representative of at least one characteristic element specific to said fire detector; and

   a fire sensor (3) that measures a physical magnitude whose variation serves to detect the existence of a fire in the vicinity of the fire detector, said fire sensor delivering an analog electrical signal (i) referred to as a "measurement" signal to the CPU (2), 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 i0 for the measurement signal in the absence of a fire;

      the detector being characterized in that:

   the fire detector further includes interface means (5, 6) giving access to the contents of the non-volatile memory (2a) without dismantling the fire detector;

   the non-volatile memory (2a) further includes dates on which maintenance operations of said fire detector have been preformed; and

   the CPU (2) is programmed to compare the measurement signal (i) with the normal value 10 of the measurement signal on each occasion that it receives an instruction from the interface means (5, 6) to record a maintenance date, and to refuse to record it whenever the measurement signal (i) does not lie within the range i0-Δ1 to i0+Δ2, where Δ1 and Δ2 are predetermined values.
2. A fire detector according to claim 1, in which the interface means comprise a connector (6) connected to the CPU (2), the connector (6) being capable of receiving a complementary connector (8) connected to an external compliance (7) for the purpose of putting said external appliance into communication with the CPU (2).
3. A fire detector according to claim 1, in which the interface means comprise a communications link (5) between the fire detector and an alarm center (4).
4. A fire detector according to any preceding claim, in which the above-mentioned characteristic element further includes the date on which said detector was manufactured.
5. A fire detector according to any preceding claim, in which the above-mentioned characteristic element further includes an identification number specific to said detector.
6. A fire detector according to any preceding claim, in which the non-volatile memory (2a) further contains, for each maintenance date, the value (i) of the measurement signal transmitted to the CPU (2) by the fire sensor (3) at the moment of recording said maintenance date.
7. A fire detector according to any preceding claim, in which the normal value iO of the measurement signal is a value measured in the absence of a fire by the fire sensor (3) under consideration, during manufacture or on first commissioning.

Images