EP0125387A1 - Risk signalling method and apparatus - Google Patents

Abstract

In a danger detection system, a signaling center (S) periodically interrogates signals, preferably in the form of infrared radiation packets, to danger detectors (F ₁ , F ₂ .., B ₁ , B ₂ , G ₁ , G ₂ , U) arranged at a distance from them sent out, which return a response signal to the signaling center after different time delays characteristic of the individual hazard detectors, the origin of the response signals being able to be localized from the time delay. In the event of danger, the hazard detectors respond to every query signal, in normal operation only to every meter. Interrogation signal, that is, less frequently, and even less frequently only with every p when the battery voltage drops. Interrogation signal. The state of the individual hazard detectors is inferred from the frequency of the response signals returned by the hazard detectors.

Description

The invention relates to a method for signal transmission in an alarm system with a central signal station and are being sent from the central signal station interrogation signals remote therefrom hazard detectors and, after receipt of the _A bfragesignale from the hazard detectors with a characteristic for each hazard detector delay time the state of the hazard detector corresponding Response signals are sent, which are received and evaluated by the signal center.

The hazard detectors can react to the conditions to be expected and reported for the respective use and can have appropriate sensors that respond, for example, to a fire, smoke, flames or certain gases, or to a break-in or theft.

Such methods and devices are known, for example, from DE 25 33 330 and allow the origin of the response signal and the location of the hazard detector to be determined and identified from the delay time of the response signals, and the presence and degree of a hazardous situation, for example, from the duration of the response signal the smoke density. The disadvantage here is that for the _S Ig nalübertragung only the two mentioned parameters are available, and therefore further desired in the signal Central information can not be easily transferred from the hazard detectors. The operational readiness and the correct functioning of the danger detectors cannot be determined in the signaling center in this way, and the device can deliver faulty signals or become inoperable without being noticed.

Another disadvantage of such pre-warmed facilities is that that the hazard detectors designed in this way have a relatively high energy consumption. In the case of signal transmission via electrical lines, there is usually sufficient power for the energy supply of the individual hazard detectors connected to the signaling center via the lines. With a large number of danger detectors connected in parallel to the signal center via the same lines, as is often required in practice, the currents and the energy losses in the lines can assume values such that a uniform energy supply to all device detectors becomes difficult and cannot be ensured can be.

Difficulties of this kind can be avoided by signal transmission by wireless means, e.g. by means of electromagnetic radiation, such as radio waves or infrared radiation, or by means of ultrasound. The energy supply to the individual hazard detectors is usually provided by batteries provided in each hazard detector.To ensure the longest possible service life of these batteries and the long-term availability of such a hazard detection system of at least one year, the energy consumption of the hazard detectors must be kept to a minimum and it is imperative to continuously and automatically monitor the operating state of the battery and thus the functionality of the individual hazard detectors in the signaling center, and to locate and remedy a defect immediately. Previously known hazard detection systems were not able to do this, or only to a limited extent.

The invention sets itself the task of eliminating the disadvantages of the prior art mentioned, and in particular to provide a method and a device for hazard reporting that a fail-safe signal transmission with the lowest possible energy consumption of the hazard detector and with simultaneous monitoring of the function and operational readiness of the hazard detector guaranteed.

According to the invention, this object is achieved in that the danger detectors in the state of a danger send out a response signal after every n interrogation signal, where n is a predetermined integer, and that the danger detectors in the operational state without a danger being present, however, after every m. Send a query signal a response signal, where m is an integer greater than n.

It may be expedient to choose n = 1, the hazard detectors sending out a response signal after each query signal, provided that there is a dangerous state, but without such a situation, first allowing several query signals to pass without an answer before an answer is given, e.g. only after every fifth interrogation signal, so that the danger detectors report the danger immediately and without delay in the state of danger, but in the normal state they are in the waiting state with the least possible energy consumption while protecting the battery as much as possible, but nevertheless the operating state is periodically monitored and reported at short intervals .

In an expedient development of the invention, it can be provided that the hazard detectors when operational readiness decreases, e.g. due to decreasing battery voltage only on every p. Answer the interrogation signal, where p is greater than m, i.e. that the hazard detectors only respond in longer intervals. In this way, an impending inoperability of a hazard detector can be recognized in good time and the battery replaced, and the battery can also be spared if the battery voltage decreases.

The evaluation can advantageously be carried out in the signaling center in such a way that from the incoming response signals for each hazard detector it is determined according to their individual time delay how many response signals have been received after a certain number q of query signals. With a number of at least x, i.e. when responding to almost every query signal, a danger is signaled, with a smaller number y the operational readiness.

It proves to be particularly favorable if the interrogation and response signals consist of vibration or pulse packets with a specific frequency and duration. This not only improves the interference immunity of the transmission, it can also be used to transmit additional parameters, e.g. of the value of a parameter that characterizes the dangerous situation.

In principle, the invention can be applied to all known signal transmission methods, including, among other things, transmission using electrical lines or optical fibers. Particular advantages, for example a particularly simple installation, result, however, in the case of wireless transmission, for example by means of radio waves or ultrasound, and in particular in the case of transmission by means of infrared radiation. The external interference that is common with radio waves and ultrasound can be avoided, and furthermore, when using infrared radiation, there are no official requirements that hinder the application. The high bandwidth of the optical transmitters also makes it possible to provide a larger number of transmission channels than in other transmission methods, and to monitor a larger number of hazard detectors, up to more than one hundred, from a single signaling center, to a large extent in a fail-safe and particularly simple manner, without Installation effort, and with automatic function monitoring of the entire system.

The invention is explained on the basis of the exemplary embodiments shown in the figures.

• Figure 1 shows the diagram of a hazard detection system.
• Figure 2 shows diagrams to explain the method.
• Figure 3 shows the circuit of a Cefahren detector.
• Figure 4 shows the circuit of a signal center.

FIG. 1 shows the arrangement of a hazard detection system using the example of a device for monitoring a room R, for example a warehouse, a factory room or an open-plan office. A signaling center S is located at a central point, for example on a longitudinal wall of room R. Various types of danger detectors are distributed over room R according to the risks to be expected. Thus, at different points of the room ceiling edge detector _B F _1, F ₂ ... F _4, for example, heat, smoke or flame detector, arranged so that it covers the whole space Ueberwachungsbereich. Intrusion detectors B ₁ are located at the inputs. B ₂ which can be designed, for example, as light or infrared barriers, as door contacts or as vibration sensors. Glass breakage detectors G ₁ , G _{2 are} installed on the windows, and a motion detector U is located at the central point of the room, which can be designed, for example, as an infrared body radiation detector or as a Doppler effect ultrasound detector. With this arrangement, a day / night circuit can also be provided, in which certain hazard detectors, for example intrusion detectors B ₁ , B ₂ and motion detector U, can be switched off during the day, but all hazard detectors are switched on during the night. The individual hazard detectors are as low-power as possible and are powered by batteries.

All hazard detectors are connected to the signal center S by means of a specific signal transmission means. These can be electrical lines. To avoid a large installation work, particularly when a plurality of hazard detectors which are to be monitored ignalzentrale by the same _S, but is advantageously provided a wireless signal transmission. It should be noted that the device must not be sensitive to external interference, as is often the case with ultrasound systems, or may itself interfere with the surroundings and other systems, like most radio waves, and the effect as far as possible must be limited to the actual protection area, and a sufficiently large number of transmission channels must be available for a large number of hazard detectors. The transmission medium for the special application must be selected accordingly. Although other transmission means are often quite usable, for applications with particularly unfavorable conditions, signal transmission by means of infrared radiation has proven to be particularly favorable for meeting all requirements.

The signal center S in the exemplary embodiment shown is therefore set up to periodically transmit interrogation signals in the form of infrared radiation to all hazard detectors at certain time intervals. Each hazard detectors are either in the visual range of the signal center and receive the interrogation signals directly, or they eralten this by reflection at walls or special reflectors, and enter the _S ignalzentrale response signals corresponding to the respective state of the alarm indicator on, and likewise in the form of infrared -Radiation, which are evaluated in the signal center for display and notification. According to the invention, it is provided that each hazard detector only emits its response signal with a certain delay time, which is characteristic of the hazard detector concerned, after the query signal arrives. The individual response signals are therefore staggered in time with respect to the interrogation signals and follow one another at different time intervals between two interrogation signals, so that the origin of the response signal can be determined from the time difference between the interrogation and response signal in the signaling center and the corresponding hazard detector can be located. The individual hazard detectors contain a specific sensor for the phenomenon to be monitored. This sensor now controls the transmission of the response signals in such a way that, in the normal case, when there is no dangerous state, that is to say no smoke or no movement in the monitored room, the response signals for a certain time or up to a certain time Number of query signals can be suppressed, or it is only after every m. Interrogation signal, for example after every fifth, a response signal is given. In the event of danger, however, for example in the event of smoke or unauthorized intrusion into the room, a response signal is triggered after every n interrogation signal, i.e. more frequently than in the normal state. It is expedient to choose n = 1, which means that in the event of danger, the corresponding hazard detector gives an answer signal to each query signal. It is advantageous here that in the normal state energy is consumed only by the relatively rare delivery of a response signal, but in the event of danger, a danger message is sent without a time delay. The battery for the intrinsic voltage supply required for each hazard detector in the case of wireless signal transmission is therefore loaded as little as possible, and the hazard detectors allow a particularly long operating time without the battery having to be replaced.

In an advantageous development of the invention, it is provided that with a slowly decreasing battery voltage, signals are even rarer, for example only after every p. Query signal are given, for example instead of after every fifth only after every tenth query signal. This longer time interval of the response signals can be evaluated in the signaling center to signal an impending battery defect, so that the used battery can be replaced in good time. A complete battery failure, a detector defect or a sabotage attempt can be determined by the fact that no response signals are received by a danger detector in the signaling center.

FIG. 2 shows the time diagrams of the interrogation signals sent by the signal center S and of the response signals returned by four selected danger detectors F ₁ , B ₁ , G ₁ , U for an assumed dangerous situation, for example. The signal center S sends periodically at certain times t ₀ , t _l , t ₂ ..., for example at time intervals Δt of approximately one second interrogation signals. These consist, as shown enlarged in the first interrogation signal of a vibration or pulse packet with a frequency of about ₃₀ to 100 kHz and a time duration of about 1 lOmsec, the t _o between within the prescribed for the interrogation signal period Δ t and t _ol of a total of 3 - 30 msec duration. The following time periods t _o1 -t _o2 , t _o2 ... are reserved for the time-graded response signals of the individual hazard detectors, and have an analog time duration of likewise 3 msec, with safety intervals t of approx. 1-10 msec duration between the time periods for the individual signals to avoid interference from different hazard detectors and to compensate for the inevitable tolerances of the components used. In this way, approximately 250 channels can be created for the simultaneous monitoring of hazard detectors, the status of each hazard detector being able to be determined individually and independently of one another in the signaling center. For an efficient evaluation, it can be useful to group the hazard detectors in groups according to their type or location, e.g. the first 25 channels for fire detectors, the following 25 for intrusion detectors, etc. ... or 25 channels for each of 10 sub-areas of the monitored room.

The following diagrams show the response signals for four selected hazard detectors that are in different states. The first danger detector F ₁ , for example a fire detector, only emits a response signal with its own time delay after every fifth interrogation signal. This is interpreted in the signaling center in such a way that there is no dangerous condition, i.e. no fire. The second hazard detector B ₁ , for example an intrusion detector, only delivers a response signal after every tenth interrogation signal. This indicates that although there is no dangerous condition, the battery of this hazard detector has deteriorated and must be replaced urgently. The third danger Detector G ₁ , for example a glass break detector does not provide a response signal at all, which means that this hazard detector is not functional, for example due to component failure or sabotage. The fourth hazard detector U, for example a motion detector, gives an answer signal after each interrogation signal. This shows that there is an alarm situation because a person is moving in the monitored room without authorization. For some reason, individual response signals may not appear, for example at time t ₃ in the diagram. The evaluation in the signaling center expediently takes this into account and also delivers a danger signal if individual response signals should fail to appear.

Figure 3 shows an example of a possible circuit of a hazard detector. The various components of the hazard detector are supplied with a DC voltage of approximately 9 V from a battery 1 via lines 2, 3. A photo diode 4, for example of the type Siemens BP 104 with a maximum sensitivity at a wavelength of 950 nm, picks up the infrared radiation emitted by the signal center and passes it on to a decoding circuit 5, which emits a trigger signal at its output. if the incoming interrogation signals have the correct form, ie duration and frequency. The trigger signal sets a time delay. member 6 in operation, which provides an output signal after a predetermined time. The time delay can be adjustable and is different for each hazard detector. The time-delayed output signal is fed to a digital counter 7, which outputs an output pulse after a predetermined and set number m of incoming trigger pulses, for example after every fifth pulse. The digital counter 7 is bridged by an electronic switch 8 which is controlled by a sensor 9 in such a way that it closes and bridges the counter 7 when the sensor 9 detects a dangerous situation, in the normal state, however, is open. In the event of danger, therefore, every trigger pulse is forwarded, but normally only every fifth pulse. In the example shown, the sensor is designed as an ionization smoke detector with two series, differently smoke-sensitive ionization chambers 10, 11, the voltage characteristic for the smoke density at the connection point of the two chambers being converted into a digital signal via a threshold switch 12, for example a MOS-FET , which controls the electronic switch 8. The output pulses of the counter 7, or of the switch 8, arrive at the input of a driver circuit 13, which has its own battery, and which has a light-emitting diode 14, for example of the Siemens LD 271 type, with a radiation maximum at 950 nm, for sending out a response signal in the form of a pulse packet with a different pulse frequency and possibly also other than the query signal. Optical focusing means 15 can be provided to align the radiation with the receiver in the signal center. The time difference between the interrogation signal and the response signal depends on the delay time of the timing element 6. In addition to the batteries 1 and / or 13, a voltage sensor 16 can be provided, which switches the counter 7 from m to a higher value p, for example to ten, when the battery voltage drops below a predetermined value. This means that the relevant hazard detector responds with a reduced battery voltage to every tenth instead of every fifth interrogation signal. Furthermore, the sensor 9 can have an additional analog output 17, from which the driver circuit 13 is additionally controlled, whereby, for example, the frequency or duration of the pulse packet of the output signal is changed, whereby the value of the smoke density, ie a measure of the magnitude of the danger, is signaled.

In the example of the switching of a signal center shown in FIG. 4, a clock generator 18 is provided which periodically generates a control pulse at intervals of approximately 1 second delivers. A driver circuit 19 causes one or more light-emitting diodes 20, which can also be of the LD 271 type, to periodically transmit interrogation signals in the form of pulse packets. The pulse frequency must be sufficiently different from that of the response signals so that there can be no mutual interference between the detectors by the response signals. The radiation arriving from the danger detectors is picked up by a photodetector 21, which can also be of the type _BP 1 ₀ 4, and fed to a decoding circuit 22, which only forwards the signals if they have the intended shape or frequency. If this is the case, the signals are fed to a series of parallel time gates 23, 24, 25, 26, which are controlled simultaneously by the clock 18, and only let a signal pass if this arrives within a certain time interval after a clock. These time intervals are selected differently for the individual time gates, so that the individual intervals do not overlap, and a number of time-graded evaluation channels are created, of which only four are shown, but the number in practice is several hundred can. If a response signal arrives during the opening side interval of one of the time gates, it is forwarded by this to an assigned digital counter 27, 28, 29, 30. Another counter 31, controlled by the clock generator 18, supplies this digital counter 27 ... 30 after each q. Cycle, for example after every tenth cycle, a trigger signal that resets it. The count of the digital counters for the next reset pulse is individually displayed on a display panel 32 for the individual hazard detectors, in the example shown for four different detectors F ₁ , B1, G ₁ , U. If the number of registered response signals z within the evaluation time 9 or 1 is ₀ , a hazard signal r (red light) is triggered, operational readiness g (green light) is signaled with a counter reading between 4 and 8, low battery y (yellow light) is displayed with a number between 1 and 3, and fault signals are displayed if the signals are completely absent o (orange) triggered. In addition to the display on the panel 32 of the signaling center, circuits can be provided which automatically forward a hazard report to the police or fire service or trigger protective and control measures, the addressee being able to be selected according to the type of hazard detector addressed.

Provision can also be made for the individual hazard detectors to be supplied locally by the network, but for the signals to be transmitted wirelessly, for example optically. A complex installation for the signal lines can be saved. Instead of separate signal lines, it is also conceivable to use the mains lines to transmit the signals in the form of high-frequency pulse packets.

For the simultaneous monitoring of several rooms, a sub-control center can be provided in each room, which monitors several hazard detectors, the individual sub-control centers being connected to a common signal control center which processes and displays the signals of the entire system.

It should be noted that different designs of the hazard detectors or signaling center are possible without leaving the scope of the invention. Such modifications are within the scope of the skill of a person skilled in the art, provided that he has acquired the inventive concept. It is thus possible to use integrated circuits with the same function instead of discrete components; instead of separate channels, a time-division multiplex method can be provided, or a microprocessor programmed according to the method according to the invention, the received response signals being stored in corresponding memory locations depending on the delay time , and with a periodic evaluation of all memory locations, the state of the entire system, in particular all abnormal states of danger detectors, indicating the location and the type of state, can be displayed on a screen or printed out with a printer.

It is particularly advantageous for the described method that the signal center only needs to determine the presence of a pulse packet with a specific frequency and duration, but does not have to resolve individual bits. As a result, the power of the driver circuits for the response signal transmitters can be reduced, or the range can be increased considerably while the power remains the same. For example, it has been shown that with a system of the type described with optical signal transmission in the absence of strong optical interference radiation, ranges of up to 100 meters can be achieved, in the presence of strong solar radiation it is still about 20 meters without interference, and with a service life of at least one year when using C batteries in the driver circuits.

Claims (10)

1. A method for signal transmission and processing in a hazard detection system with a signal center (S) and distant hazard detectors (F ₁ .., B ₁ .., G ₁ .., U), whereby signal signals are sent from the signal center , and after receiving the query signals from the danger detectors with a time delay characteristic of the individual danger detectors, the response signals corresponding to the state of the danger detectors are sent, which are received and evaluated by the signaling center, characterized in that the danger detectors in the state of danger after each n. Send query signal a response signal, where n is a predetermined integer, and that the hazard detector in the operational state without the presence of a danger only after every m. Send a query signal a response signal, where m is an integer greater than n. 2. The method according to claim 1, characterized in that the hazard detectors with decreasing operational readiness only after every p. Send an interrogation signal a response signal, where p is an integer greater than m. 3. The method according to any one of claims 1 or 2, characterized in that n = 1, that is to say that the danger detectors emit a response signal after each query signal in the dangerous state. 4. The method according to any one of claims 1 to 3, characterized in that the query signals and the response signals consist of oscillation or pulse packets with a certain frequency and duration. 5. The method according to claim 4, characterized in that the frequency or the time duration of the response signal packets depend on the value of a parameter which characterizes the danger. 6. The method according to any one of claims 1 to 5, characterized in that the signal center evaluates the response signals received in such a way that a danger is signaled after transmission of q query signals if at least x response signals arrive from a hazard detector within the period of the q query signals, and that the operational readiness is signaled if at least y response signals from a hazard alarm arrive in the same period, but less than x, where q, x, y are integers and x is greater than y. "7. The method according to any one of claims 1 to 6, characterized in that the transmission of the query signals from the signaling center to the hazard detectors and the transmission of the response signals from the hazard detectors to the signaling center takes place wirelessly. 8. The method according to claim 7, characterized in that the transmission of the query signals and the response signals takes place by means of infrared radiation. 9. The method according to claim 8, characterized in that the response signals are transmitted from the hazard detectors to the signaling center by means of infrared radiation bundled with optical bundling means. 10.Device for hazard reporting with a signaling center ( _S ) and distant hazard detectors (F ₁ , B ₁ , G ₁ , U), the signaling center having at least one signal transmitter (20) for transmitting interrogation signals, the hazard detector having a signal receiver ( 4) for receiving the interrogation signals, a signal transmitter (14) for sending out response signals, as well as a danger sensor (9) for influencing the response signals, and a delay device (6) for time delaying the response signals by a delay time after receiving an interrogation signal, which is characteristic of the individual hazard detectors and that the signaling center has a signal receiver (21) for receiving the response signals emitted by the individual danger detectors, characterized in that the danger detectors are designed in the danger state after every n. interrogation signal received, and in the state of operational readiness without the presence of one Danger after every m to send a received response signal, where n and m are predetermined integers and m is greater than n, and the signal center has an evaluation device (27, 28, 29, 30, 31) which is designed to emit a danger signal (r) give if at least x response signals are received by q a query signal, and a ready signal (g) if at least y response signals are received, but less than x, where q, x, y are integers, and q is at least equal to x , and x is greater than y, and y is at least equal to 1.

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