Fire alarm system

Abstract

To provide a fire alarm system capable of determining occurrence of a fire while preventing an erroneous alarm.SOLUTION: A receiver comprises: a signal reception section for receiving output of a plurality of analog sensors; a storage section for storing installation position information and fire alarm thresholds of the plurality of analog sensors; sensitivity adjustment means for changing and adjusting the fire alarm thresholds; and fire determination means for determining occurrence of a fire in a monitoring area when the output of the analog sensor exceeds the fire alarm threshold. In a case where one analog sensor whose output exceeds a smaller adjustment starting threshold than the fire alarm threshold is present in the plurality of analog sensors, the sensitivity adjustment means changes the fire alarm thresholds of the other analog sensors installed in a periphery in a direction to improve sensitivity as a difference between the output of the one analog sensor and the adjustment starting threshold is greater. The fire determination means determines the occurrence of the fire in a case where both the output of the one analog sensor and the output of the other analog sensors exceed the fire warning thresholds.SELECTED DRAWING: Figure 3

Description

Technical Field

[0004] ,

[0003] , ,

[0001] The present invention relates to a technology effective for application to a fire alarm system using a smoke detector, and relates to a technology capable of improving the accuracy of fire occurrence determination in consideration of the spread of smoke.

Background Art

[0002] In a fire alarm system, signal lines drawn from a fire receiver installed in a disaster prevention management center or the like are extended to each floor of a building, and a plurality of detectors are connected. Further, one or more detectors are installed for each room according to the floor layout. There are several types of fire detectors constituting a fire alarm system, such as a type that detects smoke, a type that detects heat, and a type that detects infrared rays (flames). There is also a type that sends the detected smoke concentration to a fire receiver, such as a smoke detector. When the received smoke concentration exceeds a preset concentration, the fire receiver determines that a fire has occurred and notifies (issues a fire alarm) the occurrence of the fire.

[0003] Conventionally, in a fire alarm system using a smoke detector, there may be a non-fire alarm (false alarm) that determines and reports that a fire has occurred even though no fire has actually occurred. For example, there are reports of cases where false alarms occur due to the detector output increasing due to reacting to the smoke of cigarettes or cooking, or due to condensation occurring inside the smoke detector or dust accumulating.

[0004] In this regard, Patent Document 1 discloses an invention related to an analog fire determination circuit that groups a plurality of smoke detectors and determines that a fire has occurred not only when the smoke concentration detected by each smoke detector exceeds a reference value but also when the total value (exemplified by an average value) of the outputs of the smoke detectors included in the group exceeds a reference value set for each group. Furthermore, Patent Document 2 discloses a fire alarm system that determines whether or not there is a possibility of a fire based on the multi-stage fire level from a fire detector, and if the multi-stage fire level from a detector adjacent to a detector determined to have a possibility of a fire exceeds a predetermined threshold, it determines that a fire has occurred and transmits fire alarm information to a fire alarm receiver, and if the multi-stage fire level from adjacent detectors exceeds a predetermined threshold, it shortens the storage time. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 170895 / 1983 [Patent Document 2] Japanese Patent Application Publication No. 09-288779 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Although all of the above patent documents claim that false alarms can be prevented or reduced by using the outputs from multiple smoke detectors in combination, Patent Document 1 determines the occurrence of a fire based on the output of each smoke detector individually, so it cannot completely prevent non-fire alarms (false alarms). Furthermore, Patent Document 2 states that, depending on the spacing between smoke detectors and the extent to which smoke spreads from the smoke detector of interest, the measured concentration of any adjacent smoke detector may not meet the conditions, resulting in a false alarm, or conversely, the conditions may be easily met, making it difficult to completely prevent false alarms.

[0007] This invention was made in view of the above-mentioned problems, and its objective is to provide a fire alarm system that can determine the occurrence of a fire while preventing false alarms by using the measured concentrations from multiple smoke detectors in combination as criteria for determining the occurrence of a fire. Another object of the present invention is to provide a fire alarm system that can motivate building and system managers to take measures to eliminate the causes of false alarms. [Means for solving the problem]

[0008] To solve the above problems, this invention provides: In a fire alarm system comprising a receiver and multiple analog detectors connected to signal lines drawn from the receiver and installed in a monitoring area, The aforementioned receiver is A signal receiving unit that receives the outputs of the plurality of analog sensors via the signal line, A storage unit that stores installation location information of the plurality of analog detectors in the monitoring area and fire alarm thresholds corresponding to each of the analog detectors, A sensitivity adjustment means for changing and adjusting the aforementioned fire alarm threshold, A fire determination means that determines the occurrence of a fire in the monitoring area when the output of the analog detector exceeds the fire alarm threshold, Equipped with, The sensitivity adjustment means, when there is one analog detector among the plurality of analog detectors whose output exceeds an adjustment start threshold that is smaller than the fire alarm threshold, changes the fire alarm threshold corresponding to each of the other analog detectors installed around that one analog detector in a direction that increases sensitivity, as the difference between the output of that one analog detector and the adjustment start threshold increases. The fire detection means is configured to determine that a fire has occurred when the output of the first analog detector and the output of the other analog detector both exceed the corresponding fire alarm threshold.

[0009] Here, an analog detector refers to a detector that has the function of detecting a physical quantity related to a fire and transmitting information about the detected quantity. With a fire alarm system having the above configuration, when the output of any one analog detector exceeds the adjustment start threshold, the fire alarm threshold of other analog detectors installed in the vicinity is changed to increase sensitivity. A fire is determined to have occurred when the output of one analog detector and the outputs of the surrounding analog detectors each exceed the fire alarm threshold, thus enabling fire alarms to be reported while preventing false alarms.

[0010] Preferably, the fire detection means is configured to immediately determine the occurrence of a fire, regardless of the outputs of the other analog detectors, when the output of any one of the analog detectors exceeds the maximum fire alarm threshold. With this configuration, false alarms can be reliably prevented by triggering an alarm when the maximum fire alarm threshold is exceeded.

[0011] Preferably, the sensitivity adjustment means is configured to change the fire alarm threshold of the 1 analog detector that exceeds the adjustment start threshold, so that the sensitivity decreases as the difference between the output of the 1 analog detector and the adjustment start threshold increases, up to the maximum fire alarm threshold limit. With this configuration, the sensitivity of the detector, whose output (detection concentration) is increasing due to dust accumulation or moisture adhesion from condensation, is reduced, thereby preventing the receiver from mistakenly determining that a fire has occurred due to noise or other factors.

[0012] Preferably, the sensitivity adjustment means is configured to change the fire alarm threshold of the other analog detector so that the sensitivity increases as the installation distance between the other analog detector and the first analog detector increases. With this configuration, even if false alarms are prevented by ignoring the output (detection concentration) of a detector whose output (detection concentration) has increased due to dust accumulation or moisture adhesion due to condensation, the increased sensitivity of surrounding detectors can prevent situations where a genuine fire is missed.

[0013] Furthermore, preferably, the receiver further comprises transmitting means and timing means. The timing means measures the period during which false alarm prevention occurs when the output of the first analog detector exceeds the fire alarm threshold, while the output of any of the other analog detectors does not exceed the fire alarm threshold. The transmission means is configured to send a message to an information terminal used by the administrator requesting that a predetermined task be performed on the analog sensor mentioned in 1 if the false alarm prevention period continues for a certain period of time or longer. With this configuration, if the period of false alarm prevention continues for a certain amount of time or longer, a message is sent to the administrator's information terminal, thereby motivating building and system administrators to take measures to eliminate the cause of the false alarm.

[0014] Preferably, the message requests the administrator to remove or investigate non-fire factors and includes at least one of the following: a request to clean the analog detector 1, a request to replace the components of the analog detector 1, or a request to replace the analog detector 1. With this configuration, if the period of false alarm prevention continues for a certain amount of time or longer, the administrator can be specifically presented with the tasks that need to be performed and encouraged to carry them out.

[0015] Preferably, the installation location information includes information indicating the correspondence between each of the multiple analog sensors and analog sensors located within a certain installation distance from that analog sensor. With this configuration, the receiver can easily identify detectors installed around a detector that has exceeded the fire alarm threshold, and can quickly perform the process of changing the fire alarm threshold of the surrounding detectors. [Effects of the Invention]

[0016] According to the fire alarm system of the present invention, by using the measured concentrations from a plurality of smoke detectors as materials for determining the occurrence of a fire in combination, it is possible to determine the occurrence of a fire while preventing non-fire alarms (false alarms). In addition, there is an effect that it is possible to motivate the administrator of a building or a system to implement measures to eliminate the cause of false alarms.

Brief Description of the Drawings

[0017] [Figure 1] It is a system configuration diagram showing an embodiment of the fire alarm system according to the present invention. [Figure 2] It is a graph showing the basic concept of the method for setting the fire alarm threshold as the discrimination value for the occurrence of a fire in the fire alarm system of the embodiment. [Figure 3] It is a graph showing how the fire alarm threshold of the surrounding detectors in the fire alarm system of the embodiment is changed. [Figure 4] It is a graph showing how the fire alarm threshold of the detectors exceeding the adjustment start threshold in the fire alarm system of the embodiment is changed. [Figure 5] It is a graph showing another way of changing the fire alarm threshold of the surrounding detectors in the fire alarm system of the embodiment. [Figure 6] It is a flowchart showing an example (first half) of the procedure of the fire occurrence determination process in the arithmetic processing unit of the fire receiver constituting the fire alarm system of the embodiment. [Figure 7] It is a flowchart showing the continuation (second half) of the flowchart of the fire occurrence determination process in FIG. 6. [Figure 8] It is a graph showing how the fire alarm threshold of the surrounding detectors in a modification of the fire alarm system of the embodiment is changed.

Modes for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the fire alarm system to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a system configuration diagram showing an example of the schematic configuration of the fire alarm system of the present embodiment. As shown in Figure 1, the fire alarm system of this embodiment consists of a plurality of detectors 11 installed in the monitoring area MA and a fire alarm receiver (hereinafter referred to as the receiver) 12 installed in the disaster prevention management center or the like. Signal lines 13 extending from the receiver 12 are run to each floor of the building, and a plurality of detectors 11 are connected to each floor.

[0019] Here, the sensor 11 is an analog sensor that outputs values ​​(analog values) that can be considered continuous, and has the function of transmitting information on the detected smoke concentration to the receiver 12, like a smoke detector, and multiple sensors are installed in one space depending on the floor layout. The information transmitted to the receiver 12 may be an analog signal (voltage, current) or a digital signal (binary code) obtained by A / D conversion. In this embodiment, the floor layout is assumed to be a system in which multiple sensors 11 are installed in a space such as an office that is the entire floor or a space that is divided into several relatively large rooms, conference rooms, or halls. In addition, repeaters and the like may be connected to the signal line 13.

[0020] The receiver 12 includes a signal receiving unit 21 that receives information signals sent from the detector 11 via the signal line 13, an arithmetic processing unit 22, a storage unit 23, and a data transmission unit 24. The storage unit 23 stores information such as the shape and layout of the floor (room layout), installation location information indicating where the detector 11 is installed on the floor, correspondence table information indicating which "other detectors" correspond to each "detector 1", fire alarm threshold information for determining whether or not a fire has occurred, and message information (example sentences) to be notified externally. Furthermore, the distance between each "detector 1" and "other detectors" is pre-calculated based on the floor shape and layout information, and stored along with the corresponding table information. Here, "other detectors" refers to detectors installed around "detector 1" ("detector of interest"), and does not include detectors installed at relatively distant locations.

[0021] The arithmetic processing unit 22 includes a fire determination means 22A that determines whether a fire has occurred by comparing the smoke concentration received from multiple sensors 11 with a preset fire alarm threshold Th or an immediate fire alarm threshold (maximum value) Thmax; a sensitivity adjustment means 22B that adjusts the sensitivity of each sensor by changing the threshold used to determine whether a fire has occurred; a timing means (timer) 22C that measures time; a message creation means 22D; and other means. These means are realized by the CPU (microprocessor) that constitutes the arithmetic processing unit 22 and the program executed by the CPU. The storage unit 23 is composed of a storage device such as a semiconductor memory or a hard disk. The arithmetic processing unit 22 can also be configured as an electronic circuit consisting of multiple elements.

[0022] The purpose of the fire alarm system of the present invention is to prevent false alarms while avoiding missed alarms by adjusting the fire alarm threshold of each detector, as the detection concentration of detectors installed in the monitoring area may change due to the accumulation of dust or moisture due to condensation, potentially causing false alarms. Next, using Figure 2, we will explain the basic concept of how to set the fire alarm threshold, which serves as the threshold for determining the occurrence of a fire in the fire alarm system of the above embodiment.

[0023] Figure 2 shows an example of the detection concentrations of detector A (detector of interest) whose detection output (concentration) is high due to the accumulation of dust and moisture, and detectors B1 and B2 in the vicinity of detector A that are free from dust and moisture and have normal detection output. Figure 2(A) shows the detection concentrations of each detector when it is assumed that a fire has occurred near detector A, and Figure 2(B) shows the detection concentrations of each detector when it is assumed that no fire has occurred. In Figure 2, Th is the initial fire alarm threshold (default value) for each detector.

[0024] In Figure 2, in both (A) and (B), the detection concentration of detector A exceeds the fire alarm threshold Th. However, in Figure 2(A), the detection concentrations of detectors B1 and B2 also rise to some extent, but in Figure 2(B), the detection concentrations of detectors B1 and B2 remain low. Therefore, if the fire alarm thresholds for each detector remain at their default values, as in Figure 2(B), where it is assumed that no fire has actually occurred, the receiver 12 will mistakenly determine that a fire has occurred based on the fact that the detection concentration of detector A, which has accumulated dust and moisture due to condensation, has risen due to even a small amount of smoke such as cigarette smoke or noise, resulting in a false alarm.

[0025] Therefore, if it is determined that the detection concentration of detector A exceeds the adjustment start threshold Ths, which is lower than the fire alarm threshold Th, the fire alarm thresholds of the surrounding detectors B1 and B2 are lowered from Th to the lower Th1 and Th2, respectively, as shown in Figure 2(C), to increase their sensitivity. Specifically, if the detection concentration of detector A is Sa, then the fire alarm thresholds Th1 and Th2 of detectors B1 and B2 can be defined, for example, by the following formula Th1 = Th - C1 × (Sa - Ths) Th2 = Th - C2 × (Sa - Ths) The calculation is performed using the following formula. Here, C1 and C2 are constants that are experimentally determined according to the conditions of sensors B1 and B2.

[0026] As described above, by lowering the sensitivity of the sensors installed around the sensor A of interest, even if the detection concentration of sensor A exceeds the fire alarm threshold Th, it will not be judged as a fire solely on that basis. A fire will be judged as occurring when the detection concentration of sensors B1 and B2, due to smoke from an actual fire, becomes higher than that of Th1 and Th2. Conversely, if the detection concentration of sensors B1 and B2 is lower than that of Th1 and Th2, it will be judged as not having occurred. This prevents false alarms while avoiding missed alarms. In the above explanation, two surrounding sensors were used, but the same process of lowering the fire alarm threshold may be applied to three or more sensors as well.

[0027] In the fire alarm system of this embodiment, in order to enable the modification of the fire alarm threshold as described above, the adjustment start threshold Ths is stored in the storage unit 23, and a sensitivity adjustment means 22B is provided in the calculation processing unit 22 of the receiver 12. When the sensitivity adjustment means 22B determines that the output (detection concentration) of any detector exceeds the adjustment start threshold Ths, it extracts detectors B1, B2... around the detector based on the installation location information in the storage unit 23, and lowers their fire alarm thresholds to Th1, Th2... The fire determination means 22A is configured to determine whether a fire has occurred by comparing the output of the surrounding detectors B1, B2... with the modified fire alarm thresholds Th1, Th2...

[0028] Furthermore, in this embodiment, even if no fire has occurred, as shown in Figure 3, if the detection concentration of a certain detector A is increasing and exceeds the adjustment start threshold Ths, the amount ΔTh is used to lower the fire alarm thresholds of the surrounding detectors B1 and B2 to Th1 and Th2, respectively, according to the magnitude of the increase δTh that has risen above Ths. This makes it possible to compensate for the reduced reliability of individual detection due to the accumulation of dust and condensation by increasing the sensitivity of the surrounding detectors, thereby avoiding false alarms. Note that the adjustment start threshold Ths may be set differently for each detector depending on the installation conditions, etc.

[0029] Furthermore, even if no fire has occurred, as shown in Figure 4, if the detection concentration of a certain detector A is increasing and exceeds the adjustment start threshold Ths, and the increase δTh becomes larger than a predetermined amount, the fire alarm threshold of detector A may be changed to Th', which is higher than Th, and the increase ΔTh may be increased in proportion to the magnitude of the increase δTh that exceeded Ths. At the same time, the fire alarm threshold Th of surrounding detectors may be lowered. This makes it possible to suppress false alarms even if dust accumulation or condensation progresses, and to avoid a decrease in the reliability of the fire alarm system's fire detection judgment. Note that the processing in this embodiment is effective when the initial value of the fire alarm threshold Th is set to a value (5-10% / m) lower than the maximum fire alarm threshold Thmax (15% / m), which is the threshold above which a fire will definitely be determined to have occurred. In this case, the modified Th' will not exceed Thmax.

[0030] Next, other characteristic processes in the fire alarm system of this embodiment will be described. The first characteristic process involves timing the period during which a fire was not detected and an alarm was not triggered (false alarm period) because, although the detection concentration of a certain detector A exceeded the fire alarm threshold Th as described above, the detection concentrations of surrounding detectors B1, B2, etc. did not exceed the revised fire alarm thresholds Th1, Th2. If this period continues for a predetermined time or longer, a notification is sent to the building or system administrator. Notification to the administrator is performed, for example, by pre-registering the address of the information terminal used by the administrator and example messages in the storage unit 23, and then sending a predetermined message from the data transmission unit 24 to the registered administrator address if the false alarm condition persists for a predetermined period of time or longer.

[0031] The content of the message sent could include information about the location of the sensor that is triggering a false alarm, a message urging inspection of the sensor, or a message encouraging cleaning, replacement of equipment or parts, or switching to a different model. In other words, the message should notify users that the cause of the false alarm can be relatively easily eliminated through the administrator's knowledge and skills.

[0032] By notifying building and system administrators of the message as described above, if the cause of a false alarm is the accumulation of dust or condensation on the detector, it becomes possible to remove the cause and allow the detector to function properly. Furthermore, since a malfunction in the detector may also be the cause of the false alarm, it provides an opportunity to contact the manufacturer, request an investigation and inspection, and replace parts (such as insect screens or dark boxes) or the equipment itself before a false alarm occurs. Additionally, if necessary, it is possible to recommend changing to a model more suitable for the installation environment. The message may be sent directly to the sensor manufacturer or indirectly, allowing the manufacturer to use the information as basic data for improving product performance.

[0033] The second characteristic process involves lowering the fire alarm thresholds Th1, Th2, etc. of surrounding detectors B1, B2, etc., in response to the detection concentration of a certain detector A exceeding the adjustment start threshold Ths. As shown in Figure 5, the amount of the reduction ΔTh is increased in proportion to the distance DA_B1, DA_B2, etc. from detector A to detectors B1, B2, etc. Specifically, the following equation Thn = Th - E × DA_Bn (where n = 1, 2, ...) Use this to change the fire alarm threshold.

[0034] In the above formula, E is a coefficient used to convert distance into a quantity of the dimension "% / m," and it may be common to all sensors or determined for each sensor. More precisely, in the example above, the E multiplied by the distances DAB1, DAB2, etc. to the surrounding sensors B1, B2, etc. must be common, but it may be different for sensor A and the other sensors. If detectors A, B1, B2, etc. are smoke detectors, smoke generated by a fire near detector A is expected to thin out as it travels to the detectors located further away. Therefore, it is reasonable to use a lower fire alarm threshold for detectors further away from detector A, thereby increasing the reliability of the detection results.

[0035] Next, an example of the procedure for fire occurrence determination processing by the arithmetic processing unit 22 of the receiver 12, which constitutes the fire alarm system of this embodiment, will be explained using the flowchart shown in Figures 6 and 7. This flowchart starts, for example, when the power to the receiver 12 is turned on. When the receiver 12 is powered on, the arithmetic processing unit 22 first performs initialization processing such as clearing all counters and turning off all alarm flags (step S1). Next, the arithmetic processing unit 22 receives detected concentration information from the sensors 11 connected to each signal line 13 and determines whether or not there are any sensors that have exceeded the adjustment start threshold (step S2).

[0036] Then, if it is determined that there is a detector that has exceeded the adjustment start threshold (hereinafter referred to as the "detector of interest") (Yes), the process proceeds to step S3, where it is determined whether the output (detection concentration) of each detector of interest is higher than the adjustment start threshold by a predetermined amount or more. If it is determined that the output is higher than the adjustment start threshold (Yes), the fire alarm threshold of the detector of interest is changed to a value higher by an amount corresponding to the difference between the current output and the adjustment start threshold (step S4), and then the process proceeds to step S5.

[0037] On the other hand, if it is determined in step S3 that the output (detection concentration) is not higher than the adjustment start threshold (No), the process proceeds to step S14. In step S5, it is determined whether the output of the sensor of interest exceeds the fire alarm threshold. If it is determined that the fire alarm threshold is not exceeded (No), the process proceeds to step S14. If it is determined that the fire alarm threshold is exceeded (Yes), the process proceeds to step S6, where it is determined whether the fire alarm threshold of the sensor of interest is at its maximum value (15% / m). If it is determined that the fire alarm threshold is not at its maximum value (15% / m) (No), the process proceeds to step S7, where the surrounding sensors are identified by referring to the table in the storage unit 23.

[0038] Next, the arithmetic processing unit 22 changes the fire alarm threshold for each identified ambient detector to a lower value corresponding to the distance from the detector of interest and the difference between the output of the detector of interest and the adjustment start threshold (step S8). Next, it determines whether the output of the ambient detector exceeds the fire alarm threshold (step S9), and if it determines that the fire alarm threshold has been exceeded (Yes), it proceeds to step S10 and turns on the alarm flag corresponding to the detector of interest. On the other hand, if the arithmetic processing unit 22 determines in step S9 that the fire alarm threshold has not been exceeded (No), it proceeds to step S11 and increments the counter corresponding to the sensor of interest without issuing an alarm. After that, it determines whether the value of the counter has exceeded a certain value (step S12), and if it determines that the value of the counter has exceeded a certain value (Yes), it proceeds to step S13 and sends a message to the administrator's information terminal prompting inspection of the sensor of interest.

[0039] Subsequently, the arithmetic processing unit 22 determines whether or not there is a target sensor with the alarm flag turned on (step S14). If it determines that there is a target sensor with the alarm flag turned on (Yes), it proceeds to step S15 and issues a notification (alarm) indicating that a fire has occurred near the installation location of the target sensor. On the other hand, if it determines in step S14 that there is no target sensor with the alarm flag turned on (No), it returns to step S2 and repeats the above process.

[0040] Next, a modified example of the fire alarm system of the above embodiment will be described using Figure 8. The fire alarm system of the above embodiment assumes that a particular detector has more dust accumulation and moisture due to condensation compared to surrounding detectors. However, depending on the building structure, it is also possible that multiple detectors installed in a certain area may simultaneously experience increased dust accumulation and moisture due to condensation.

[0041] Therefore, in the modified example shown in Figure 8, the detection concentration of all sensors installed in the monitoring area is stored as historical information in the storage unit 23. When the detection concentration of a certain sensor A exceeds the adjustment start threshold Ths, the fire alarm thresholds Th1, Th2, etc. of the surrounding sensors B1, B2, etc. are lowered, the historical information of the surrounding sensors B1, B2, etc. is referenced as shown in Figure 8. Furthermore, if it is determined that the detection concentration of the surrounding sensors B1, B2, etc. has increased due to dust accumulation or moisture adhesion due to condensation, the fire alarm thresholds Th1, Th2, etc. of the surrounding sensors B1, B2, etc. are not lowered, or the amount ΔTh by which they are lowered is made smaller compared to the previous embodiment. By doing so, even when the detection concentration increases due to increased dust accumulation or moisture buildup from condensation on multiple detectors, a highly accurate determination of fire occurrence can be made.

[0042] Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments and can be modified as appropriate without departing from the spirit of the invention. For example, in the above embodiments, a fire alarm system using a smoke detector to detect smoke concentration as an analog detector has been described, but the analog detector is not limited to a smoke detector, and may also be a gas detector that has elements such as a gas sensor to detect harmful gases such as CO and an amplification circuit to amplify the signals from these elements, and the present invention can be applied to a fire alarm system in which smoke detectors and gas detectors are mixed. [Explanation of symbols]

[0043] 11. Smoke detector (analog detector) 12. Fire alarm receiver (receiver) 13 signal lines 21 Signal receiving section 22 Arithmetic Processing Unit 23 Memory section 24 Data transmission unit 22A Fire detection means 22B Sensitivity adjustment means 22C Timer 22D Message Creation Method

Claims

1. A fire alarm system comprising a receiver and a plurality of analog detectors connected to a signal line drawn from the receiver and installed in a monitoring area, The aforementioned receiver is A signal receiving unit that receives the outputs of the plurality of analog sensors via the signal line, A storage unit that stores installation location information of the plurality of analog detectors in the monitoring area and fire alarm thresholds corresponding to each of the analog detectors, A sensitivity adjustment means for changing and adjusting the aforementioned fire alarm threshold, A fire determination means that determines the occurrence of a fire in the monitoring area when the output of the analog detector exceeds the fire alarm threshold, Equipped with, The sensitivity adjustment means, when there is one analog detector among the plurality of analog detectors whose output exceeds an adjustment start threshold that is smaller than the fire alarm threshold, changes the fire alarm threshold corresponding to each of the other analog detectors installed around that one analog detector in a direction that increases sensitivity, as the difference between the output of that one analog detector and the adjustment start threshold increases. The fire detection means determines that a fire has occurred when the output of the first analog detector and the output of the other analog detector both exceed the corresponding fire alarm threshold. A fire alarm system characterized by the following features.

2. The fire alarm system according to claim 1, characterized in that the sensitivity adjustment means changes the fire alarm threshold of the 1 analog detector that has exceeded the adjustment start threshold, in a direction that lowers the sensitivity as the difference between the output of the 1 analog detector and the adjustment start threshold increases, up to the maximum fire alarm threshold.

3. The fire alarm system according to claim 2, characterized in that the fire determination means immediately determines the occurrence of a fire, regardless of the output of the other analog detectors, when the output of any one of the analog detectors exceeds the maximum fire alarm threshold.

4. The fire alarm system according to any one of claims 1 to 3, characterized in that the sensitivity adjustment means changes the fire alarm threshold of the other analog detector so that the sensitivity increases as the installation distance between the other analog detector and the first analog detector increases.

5. The receiver further comprises a transmitting means and a timing means, The timing means measures the period during which false alarm prevention occurs when the output of the first analog detector exceeds the fire alarm threshold, while the output of any of the other analog detectors does not exceed the fire alarm threshold. The fire alarm system according to claim 4, characterized in that the transmitting means sends a message to an information terminal used by the administrator requesting that a predetermined task be performed on the analog detector 1 if the false alarm prevention period continues for a certain period of time or longer.

6. The fire alarm system according to claim 5, characterized in that the message requests the administrator to remove or investigate non-fire factors, and includes at least one of the following: a request to clean the analog detector 1, a request to replace the components of the analog detector 1, or a request to replace the analog detector 1.

7. The fire alarm system according to claim 6, characterized in that the installation location information includes information indicating the correspondence between each of the plurality of analog detectors and analog detectors located within a certain installation distance from said analog detector.

Images