JP2023161638A - fire alarm system - Google Patents

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

The present invention relates to a technique that is effective when applied to a fire alarm system using a smoke detector, and relates to a technique that can improve the accuracy of determining the occurrence of a fire by taking into consideration the spread of smoke.

In a fire alarm system, a signal line drawn out from a fire receiver installed at a disaster prevention management center or the like is extended to each floor of a building and connected to a plurality of detectors. Furthermore, one or more sensors are installed in each room depending on the layout of the floor.
There are several types of fire detectors that make up a fire alarm system, including types that detect smoke, types that detect heat, and types that detect infrared rays (flame). There is also a type that sends the fire signal to a fire receiver. When the received smoke concentration exceeds a preset concentration, the fire receiver determines that a fire has occurred and notifies the fire (fire alarm).

BACKGROUND ART Conventionally, in fire alarm systems using smoke detectors, non-fire alarms (false alarms) may occur in which a fire is determined to be occurring and a notification is made even though no fire has actually occurred. For example, there have been reports of cases in which non-fire alarms were generated due to a reaction to smoke from cigarettes or cooking, or due to dew condensation or dust accumulation inside the smoke detector, resulting in a high sensor output. ing.

In this regard, Patent Document 1 discloses that when a plurality of smoke detectors are grouped and the smoke density detected by each smoke detector exceeds a reference value, the total value of the output of the smoke detectors included in the group is An invention related to an analog fire determination circuit that determines that there is a fire even when the average value (the average value is an example) exceeds a reference value set for each group is disclosed.
Furthermore, Patent Document 2 discloses that the presence or absence of the possibility of fire outbreak is determined based on multi-level fire levels from fire detectors, and the presence or absence of the possibility of fire outbreak is determined based on the multi-stage fire level from the fire detector, and the If the multi-stage fire level exceeds a predetermined threshold, it is determined that a fire has occurred and information on the occurrence of fire is transmitted to the fire receiver, and the multi-stage fire level from the adjacent detector is set in advance. A fire alarm system is disclosed in which the accumulation time is shortened if a predetermined threshold is exceeded.

Japanese Unexamined Patent Publication No. 170895/1989 Japanese Patent Application Publication No. 09-288779

Although both of the above patent documents claim that false alarms can be prevented or reduced by using the output from multiple smoke detectors together, Patent Document 1 states that the output from each smoke detector alone can be used to prevent or reduce false alarms. Since the system is determining whether a fire has occurred, it is not possible to completely prevent non-fire alarms (false alarms).
In addition, in Patent Document 2, depending on the installation interval of smoke detectors and the degree of spread of smoke from the smoke detector of interest, the measured concentration of any adjacent smoke detector may not meet the conditions and a false alarm may occur. On the other hand, there is a problem that false alarms cannot be prevented because the conditions may be easily met.

The present invention has been made with a focus on the above-mentioned problems, and its purpose is to use the measured concentrations from multiple smoke detectors together as a basis for determining the occurrence of a fire, thereby preventing non-fire alarms (false alarms). ) The object of the present invention is to provide a fire alarm system capable of determining the occurrence of a fire while preventing 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 causes of false alarms.

In order to solve the above problems, this invention
In a fire alarm system comprising a receiver and a plurality of analog detectors connected to a signal line drawn out from the receiver and installed in a monitoring area,
The receiver includes:
a signal receiving unit that receives outputs of the plurality of analog sensors via the signal line;
a storage unit that stores installation position information of the plurality of analog sensors in the monitoring area and a fire alarm threshold corresponding to each of the analog sensors;
Sensitivity adjustment means for changing and adjusting the fire alarm threshold;
fire determination means for determining the occurrence of a fire in the monitoring area when the output of the analog sensor exceeds the fire alarm threshold;
Equipped with
The sensitivity adjustment means is configured to adjust the sensitivity of the one analog sensor when there is one analog sensor among the plurality of analog sensors whose output exceeds an adjustment start threshold that is smaller than the fire alarm threshold. The larger the difference between the output and the adjustment start threshold, the more the fire alarm threshold corresponding to each of the other analog sensors installed around the first analog sensor is changed in a direction to increase the sensitivity;
The fire determining means is configured to determine that a fire has occurred when the output of the first analog sensor and the output of the other analog sensor both exceed the corresponding fire alarm threshold. be.

Here, the analog sensor refers to a sensor that has a function of detecting a physical quantity related to fire and transmitting information on the detected quantity.
According to the fire alarm system having the above configuration, when the output of any one analog sensor exceeds the adjustment start threshold, the fire alarm threshold of the other analog sensors installed around the This change has been made in the direction of increasing the fire alarm, and it is determined that a fire has occurred when the output of the first analog sensor and the output of the surrounding analog sensors exceed the fire alarm threshold, while preventing non-fire alarms (false alarms). It is possible to notify the occurrence of a fire.

Preferably, the fire determining means immediately determines that a fire has occurred when the output of any one of the analog sensors exceeds a maximum fire alarm threshold, regardless of the outputs of the other analog sensors. Configure it to do so.
According to this configuration, failure to report can be reliably prevented by issuing an alarm when the maximum fire alarm threshold is exceeded.

Preferably, the sensitivity adjustment means sets the fire alarm threshold of the one analog sensor that exceeds the adjustment start threshold to the output of the one analog sensor and adjusts the fire alarm threshold of the one analog sensor up to a maximum fire alarm threshold. The configuration is such that the larger the difference from the start threshold, the lower the sensitivity.
According to this configuration, the sensitivity of the sensor whose output (detection concentration) is increasing is lowered due to the accumulation of dust or the adhesion of moisture due to dew condensation, so noise etc. can cause the receiver to accidentally cause a fire. It is possible to suppress the judgment that it has occurred.

Preferably, the sensitivity adjustment means changes the fire alarm threshold of the other analog sensor so that the greater the installation distance between the other analog sensor and the first analog sensor, the higher the sensitivity becomes. Configure it to do so.
According to this configuration, if the output (detected concentration) of the sensor increases due to accumulation of dust or moisture due to condensation, and the output exceeds the fire alarm threshold, it is ignored. Even if this prevents false alarms, increasing the sensitivity of surrounding detectors can prevent a situation in which the actual occurrence of a fire is overlooked.

Furthermore, desirably, the receiver further includes a transmitting means and a clocking means,
The timing means determines a false alarm prevention period in which the output of the first analog sensor exceeds the fire alarm threshold while the output of any of the other analog sensors does not exceed the fire alarm threshold. Timekeeping,
The transmitting means is configured to transmit a message requesting execution of a predetermined operation regarding the first analog sensor to an information terminal used by the administrator when the false alarm prevention period continues for a certain period of time or more. Configure.
According to this configuration, if the false alarm prevention period continues for a certain period of time or more, a message is sent to the administrator's information terminal, which gives building and system administrators an incentive to take measures to eliminate the cause of false alarms. It is possible to give an attachment.

Preferably, the message requests the administrator to remove or investigate non-fire causes, and includes at least a request to clean the first analog sensor and a request to replace components of the first analog sensor. , including any one of the above-mentioned requests for replacing the analog sensor.
According to this configuration, when the false alarm prevention period continues for a certain period of time or more, it is possible to specifically present the work to be performed to the administrator and urge the administrator to perform the work.

Preferably, the installation position information includes information indicating a correspondence relationship between each of the plurality of analog sensors and an analog sensor located within a certain installation distance from the analog sensor. do.
According to this configuration, the receiver can easily know which sensors are installed around the sensor whose fire alarm threshold has been exceeded, and promptly change the fire alarm threshold of the surrounding sensors. processing can be executed.

According to the fire alarm system according to the present invention, by using the measured concentrations from a plurality of smoke detectors together as materials for determining the occurrence of a fire, it is possible to determine the occurrence of a fire while preventing non-fire alarms (false alarms). . It also has the effect of motivating building and system managers to take measures to eliminate the causes of false alarms.

1 is a system configuration diagram showing an embodiment of a fire alarm system according to the present invention. It is a graph which shows the basic idea of the setting method of the fire alarm threshold value as a discrimination value of the fire outbreak in the fire alarm system of embodiment. It is a graph showing how to change the fire alarm threshold of the surrounding sensor in the fire alarm system of the embodiment. It is a graph showing how to change the fire alarm threshold of a sensor that exceeds the adjustment start threshold in the fire alarm system of the embodiment. It is a graph which shows the other way of changing the fire alarm threshold of a surrounding sensor in the fire alarm system of embodiment. It is a flowchart which shows an example (first half) of the procedure of the fire outbreak determination process in the arithmetic processing part of the fire receiver which comprises the fire alarm system of embodiment. 7 is a flowchart showing a continuation (second half) of the flowchart of the fire occurrence determination process of FIG. 6; It is a graph showing how to change the fire alarm threshold of the surrounding sensor in a modified example of the fire alarm system of the embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a 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 a schematic configuration of a fire alarm system of this embodiment.
As shown in FIG. 1, the fire alarm system of this embodiment includes a plurality of detectors 11 installed in a monitoring area MA, and a fire receiver (hereinafter referred to as receiver) 12 installed in a disaster prevention management center, etc. A signal line 13 drawn out from a receiver 12 is extended to each floor of the building, and a plurality of sensors 11 are connected to each floor.

Here, the sensor 11 is an analog sensor that outputs a value that can be considered continuous (analog value), and has a function of transmitting information on detected smoke concentration to the receiver 12, for example, like a smoke detector. Multiple units can be installed in one space depending on the floor layout. The information transmitted to the receiver 12 may be an analog signal (voltage, current) or may be a digital signal (binary code) obtained by A/D converting it. Note that this embodiment is a system in which a plurality of sensors 11 are installed in a floor layout such as a relatively large room, conference room, or hall where the entire floor is divided into one office or several parts. is assumed. Further, a repeater or the like may be connected to the signal line 13.

The receiver 12 includes a signal receiving section 21 that receives information signals sent from the sensor 11 via a signal line 13, an arithmetic processing section 22, a storage section 23, and a data transmission section 24. 23 includes the floor shape, layout (room floor plan), installation position information indicating where on the floor the sensor 11 is installed, and "other sensors" corresponding to each of "sensor 1". Correspondence table information indicating which one is, fire alarm threshold information for determining whether a fire has occurred, message information (example sentences) for notification to the outside, etc. are stored.
Note that the distance between each "one sensor" and "another sensor" is also calculated in advance based on the floor shape and layout information, and is stored together with the correspondence table information. Here, "other sensors" refer to sensors installed around "sensor 1"("sensor of interest"), and sensors that are installed relatively far away. is not included.

The arithmetic processing unit 22 compares the smoke concentration received from the plurality of sensors 11 with a preset fire alarm threshold Th or an immediate fire alarm threshold (maximum value) Thmax to determine the occurrence of a fire. It is equipped with a judgment means 22A, a sensitivity adjustment means 22B that adjusts the sensitivity of each sensor by changing the threshold value used for determining the occurrence of a fire, a timer 22C that measures the time, a message creation means 22D, and other means. These means are realized by a CPU (microprocessor) constituting the arithmetic processing unit 22 and a program executed by the CPU. The storage unit 23 is constituted by a storage device such as a semiconductor memory or a hard disk. The arithmetic processing section 22 can also be configured as an electronic circuit consisting of a plurality of elements.

The purpose of the fire alarm system of the present invention is to prevent the detection concentration of the sensors installed in the monitoring area from changing due to adhesion of dust or moisture due to condensation, which may cause false alarms. The aim is to prevent non-fire alarms (false alarms) while avoiding missed alarms by devising the fire alarm threshold of the device.
Next, with reference to FIG. 2, the basic concept of a method for setting a fire alarm threshold as a threshold for determining the occurrence of a fire in the fire alarm system of the above embodiment will be explained.

Figure 2 shows sensor A (sensor of interest) whose detection output (concentration) has become high due to the adhesion of dust and moisture, and the sensors around sensor A that are free of dust and moisture. Figure 2 (A) shows an example of the detected concentrations of sensors B1 and B2, which have normal detection outputs. FIG. 2(B) shows the detected concentration of each sensor assuming that no fire has occurred. In addition, in FIG. 2, Th is the initially set fire alarm threshold value (default value) of each sensor.

In FIG. 2, in both (A) and (B), the detected concentration of sensor A exceeds the fire alarm threshold Th. However, in FIG. 2(A), the detected concentrations of the sensors B1 and B2 also become high to some extent, but in FIG. 2(B), the detected concentrations of the sensors B1 and B2 remain low. Therefore, if the fire alarm threshold of each sensor remains at the default value, the receiver 12 will be exposed to moisture due to dust and condensation, as shown in Figure 2 (B), which assumes that no fire has actually occurred. The attached sensor A determines that a fire has occurred based on the detected concentration increasing due to slight smoke or noise such as cigarette smoke, which means that a non-fire alarm (false alarm) is issued. .

Therefore, when it is determined that the detected concentration of sensor A exceeds the adjustment start threshold Ths, which is lower than the fire alarm threshold Th, the surrounding sensors B1 and B2 are Sensitivity is increased by lowering the fire alarm threshold from Th to lower values Th1 and Th2.
Specifically, if the detected concentration of sensor A is Sa, then the fire alarm thresholds Th1 and Th2 of sensors B1 and B2 are calculated using the following formula, for example, Th1 = Th - C1 x (Sa - Ths)
Th2= Th-C2×(Sa-Ths)
Calculate using. Here, C1 and C2 are constants determined experimentally depending on the conditions of the sensors B1 and B2.

By lowering the sensitivity of the sensors installed around the sensor A of interest as described above, even if the concentration detected by the sensor A exceeds the fire alarm threshold Th, it is not determined that a fire has occurred. If the concentration of smoke detected by detectors B1 and B2 is higher than Th1 and Th2 due to the smoke associated with the actual fire, it is determined that a fire has occurred, and if the concentration detected by detectors B1 and B2 is lower than Th1 and Th2, a fire has occurred. It is determined that this has not occurred. This makes it possible to prevent false alarms while avoiding missed alarms. In the above description, the number of surrounding sensors is two, but the fire alarm threshold may be similarly lowered for three or more sensors.

In the fire alarm system of this embodiment, in order to make it possible to change the fire alarm threshold as described above, the adjustment start threshold Ths is stored in the storage unit 23, and the arithmetic processing unit 22 of the receiver 12 A sensitivity adjustment means 22B is provided. When the sensitivity adjustment means 22B determines that the output (detection concentration) of any sensor exceeds the adjustment start threshold Ths, the sensitivity adjustment means 22B selects the sensor B1 around the sensor based on the installation position information in the storage unit 23. , B2... are extracted, and the fire alarm thresholds are lowered to Th1, Th2..., and the fire determining means 22A extracts the outputs of the surrounding sensors B1, B2... and the changed fire alarm thresholds Th1, Th2. It is configured to determine whether a fire has occurred by comparing the...

In addition, in this embodiment, as shown in FIG. 3, even though no fire has occurred, if the detected concentration of a certain sensor A tends to increase and exceeds the adjustment start threshold Ths, The amount ΔTh by which the fire alarm thresholds of the surrounding sensors B1 and B2 are lowered to Th1 and Th2 is increased in accordance with the magnitude of the increase δTh that exceeds the threshold value ΔTh. This makes it possible to compensate for the decrease in the reliability of judgment due to the progress of dust and condensation by increasing the sensitivity of the surrounding sensors, thereby avoiding false alarms. can. Note that the adjustment start threshold Ths may be made different for each sensor depending on the installation conditions and the like.

Furthermore, as shown in Figure 4, even though no fire has occurred, the detected concentration of a certain sensor A tends to increase and exceeds the adjustment start threshold Ths, and the increased amount δTh becomes larger than a predetermined value. In this case, the fire alarm threshold of the sensor A may be changed to Th' which is higher than Th, and the amount of increase ΔTh may be increased according to the size of the increase δTh that exceeds Ths. good. At the same time, the fire alarm threshold Th of surrounding sensors is lowered. As a result, even if the accumulation of dust or the adhesion of dew progresses, false alarms can be suppressed, and the reliability of the fire alarm system's determination of the occurrence of a fire can be prevented from decreasing.
In addition, in the process of this embodiment, the initial value of the fire alarm threshold Th is a value lower than the maximum fire alarm threshold Thmax (15%/m) for determining that a fire has occurred if the concentration becomes higher than this. (5 to 10%/m), and Th' after the change will not exceed Thmax.

Next, other characteristic processing in the fire alarm system of this embodiment will be explained.
The first characteristic process is when the detected concentration of a certain sensor A exceeds the fire alarm threshold Th as described above, but the detected concentration of the surrounding sensors B1, B2... The timer 22C measures the period during which it was determined that a fire had not occurred and did not issue an alarm because the alarm thresholds Th1 and Th2 were not exceeded (false alarm state duration period), and if this period continued for a predetermined time or more, the building or system The system will notify the administrator of the system.
The notification to the administrator can be made by registering, for example, the address of the information terminal used by the administrator and an example of the content to be sent in the storage unit 23 in advance, and when the false alarm state continues for a predetermined period of time or more. This is done by transmitting a predetermined message from the data transmitting unit 24 to the address of the administrator.

The contents of the message to be sent include the installation location of the sensor that is in a false alarm state, a text urging the sensor to be inspected, and a message urging cleaning the sensor, replacing the device or parts, or changing to a different model. Sentences, etc. can be considered. In other words, the system notifies the administrator of information that can be taken to relatively easily eliminate the cause of the false alarm, depending on the knowledge and skills of the administrator.

By notifying the building or system administrator of the message as described above, if the cause of the false alarm is the accumulation of dust or condensation on the sensor, it becomes possible to eliminate the cause so that it can operate normally. In addition, it is possible that the cause of the false alarm is a malfunction in the sensor, so contact the manufacturer and request an investigation and inspection. This can provide an opportunity for exchange. Furthermore, if necessary, it is possible to recommend changing to a model that is most suitable for the installation environment.
Note that the message may be sent directly or indirectly to the manufacturer of the sensor, so that the manufacturer can use the information as basic data for improving the performance of the product.

The second characteristic process is to lower the fire alarm thresholds Th1, Th2... of surrounding sensors B1, B2... in response to the detected concentration of a certain sensor A exceeding the adjustment start threshold Ths. , as shown in FIG. 5, the reduction amount ΔTh is increased in proportion to the distances DA_B1, DA_B2, . . . from the sensor A to the sensors B1, B2, . Specifically, the following formula Thn= Th-E×DA_Bn (however, n=1, 2,...)
to change the fire alarm threshold.

In the above equation, E is a coefficient for converting the distance into a dimensional quantity of "%/m", and it may be common to all sensors or may be determined for each sensor. To be precise, in the above example, E multiplied by the distances DAB1, DAB2... to the surrounding sensors B1, B2... must be the same, but it is different for sensor A and other sensors. It may be made to differ.
If detectors A, B1, B2, etc. are smoke detectors, it is thought that the smoke generated by a fire occurring near detector A will be diluted as it flows to the detector located further away. It is reasonable to judge the occurrence of a fire using a lower fire alarm threshold for a sensor located at a greater distance from the sensor A, thereby increasing the reliability of the judgment result.

Next, an example of the procedure of fire occurrence determination processing by the arithmetic processing unit 22 of the receiver 12 that constitutes the fire alarm system of this embodiment will be explained using the flowcharts shown in FIGS. 6 and 7. This flowchart is started, for example, when the receiver 12 is powered 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 there is any sensor whose concentration exceeds the adjustment start threshold (step S2).

If it is determined that there is a sensor that exceeds the adjustment start threshold (hereinafter referred to as a sensor of interest) (Yes), the process advances to step S3, and the output (detected concentration) of each sensor of interest is set to the adjustment start threshold. If it is determined that the output is higher than the adjustment start threshold (Yes), the fire alarm threshold of the sensor of interest is set to the difference between the current output and the adjustment start threshold. The value is changed to a higher value according to the amount (step S4), and the process then proceeds to step S5.

On the other hand, if it is determined in step S3 that the output (detected concentration) is not higher than the adjustment start threshold (No), the process moves to step S14.
In step S5, it is determined whether the output of the sensor of interest exceeds a fire alarm threshold. If it is determined that the fire alarm threshold is not exceeded (No), the process proceeds to step S14, and if it is determined that the fire alarm threshold is exceeded (Yes), the process proceeds to step S6, where the attention detection Determine whether the fire alarm threshold of the device is at the maximum value (15%/m). Here, if it is determined that the fire alarm threshold is not the maximum value (15%/m) (No), the process advances to step S7, and the sensor surrounding the sensor is checked by referring to the table in the storage unit 23. Identify.

Next, the arithmetic processing unit 22 changes the fire alarm threshold of each identified surrounding sensor by an amount corresponding to the distance from the sensor of interest and the difference between the output of the sensor of interest and the adjustment start threshold. The value is changed to a lower value (step S8). Next, it is determined whether the output of the surrounding sensor exceeds the fire alarm threshold (step S9), and if it is determined that the output exceeds the fire alarm threshold (Yes), the process proceeds to step S10, and the attention is Turn on the alarm flag corresponding to the sensor.
On the other hand, if the arithmetic processing unit 22 determines in step S9 that the fire alarm threshold is not exceeded (No), the process proceeds to step S11, and without issuing an alarm, the counter corresponding to the sensor of interest is Increment. Thereafter, it is determined whether or not the value of the counter has exceeded a certain value (step S12), and when it is determined that the value of the counter has exceeded a certain value (Yes), the process proceeds to step S13, where attention is sensed. Sends a message to the administrator's information terminal urging inspection of the equipment.

Thereafter, the arithmetic processing unit 22 determines whether there is an attention sensor whose alarm flag is on (step S14), and if there is an attention sensor whose alarm flag is on (Yes). If it is determined, the process proceeds to step S15, where a notification (issue) is executed on the assumption that a fire has occurred in the vicinity of the installation position of the sensor of interest. On the other hand, if it is determined in step S14 that there is no sensor of interest whose alarm flag is turned on (No), the process returns to step S2 and the above process is repeated.

Next, a modification of the fire alarm system of the embodiment will be described using FIG. 8.
In the fire alarm system of the embodiment, it is assumed that a certain sensor has more moisture attached due to dust accumulation or dew condensation than surrounding sensors. However, depending on the structure of the building, etc., there may be cases where a plurality of sensors installed in a certain area have a large amount of moisture attached due to dust accumulation or dew condensation at the same time.

Therefore, in the modification shown in FIG. 8, the detected concentrations of all the sensors installed in the monitoring area are stored in the storage unit 23 as historical information, and the detected concentration of a certain sensor A becomes the adjustment start threshold Ths. In order to lower the fire alarm thresholds Th1, Th2... of the surrounding sensors B1, B2... in response to the exceedance, the history information of the surrounding sensors B1, B2... refer. If it is determined that the detected concentration has increased in the surrounding sensors B1, B2... due to the accumulation of dust or moisture adhesion due to dew condensation, a fire can occur in the surrounding sensors B1, B2... In this embodiment, the threshold values Th1, Th2, . . . are not lowered, or the amount ΔTh by which they are lowered is made smaller than in the previous embodiment.
By doing the above, by increasing the amount of moisture adhering to multiple detectors due to dust accumulation and dew condensation, it is possible to detect a fire with high accuracy even if the detected concentration increases in a situation where no fire has occurred. can make judgments.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the gist thereof. For example, in the above embodiment, a fire alarm system using a smoke detector that detects smoke concentration as an analog detector was described, but the analog detector is not limited to smoke detectors, and can detect harmful gases such as CO. The gas sensor may be equipped with an element such as a gas sensor that detects gas and an amplifier circuit that amplifies the signal from these elements, and the present invention is applicable to a fire alarm system that includes a smoke detector and a gas detector. Can be applied.

11 Smoke detector (analog detector)
12 Fire receiver (receiver)
13 Signal line 21 Signal receiving section 22 Arithmetic processing section 23 Storage section 24 Data transmitting section 22A Fire judgment means 22B Sensitivity adjustment means 22C Time measuring means (timer)
22D Message creation means

Claims (7)

A fire alarm system comprising a receiver and a plurality of analog detectors connected to a signal line drawn out from the receiver and installed in a monitoring area,
The receiver includes:
a signal receiving unit that receives outputs of the plurality of analog sensors via the signal line;
a storage unit that stores installation position information of the plurality of analog sensors in the monitoring area and a fire alarm threshold corresponding to each of the analog sensors;
Sensitivity adjustment means for changing and adjusting the fire alarm threshold;
fire determination means for determining the occurrence of a fire in the monitoring area when the output of the analog sensor exceeds the fire alarm threshold;
Equipped with
The sensitivity adjustment means is configured to adjust the sensitivity of the one analog sensor when there is one analog sensor among the plurality of analog sensors whose output exceeds an adjustment start threshold that is smaller than the fire alarm threshold. The larger the difference between the output and the adjustment start threshold, the more the fire alarm threshold corresponding to each of the other analog sensors installed around the first analog sensor is changed in a direction to increase the sensitivity;
The fire determining means determines that a fire has occurred when the output of the first analog sensor and the output of the other analog sensor both exceed the corresponding fire alarm threshold. Notification system. The sensitivity adjustment means sets the fire alarm threshold of the one analog sensor that exceeds the adjustment start threshold to the difference between the output of the one analog sensor and the adjustment start threshold up to a maximum fire alarm threshold. 2. The fire alarm system according to claim 1, wherein the larger the value, the lower the sensitivity. The fire determining means is characterized in that when the output of any one of the analog sensors exceeds a maximum fire alarm threshold, it immediately determines that a fire has occurred, regardless of the outputs of the other analog sensors. The fire alarm system according to claim 2. The sensitivity adjustment means changes the fire alarm threshold of the other analog sensor so that the greater the installation distance between the other analog sensor and the first analog sensor, the higher the sensitivity becomes. The fire alarm system according to any one of claims 1 to 3. The receiver further includes a transmitting means and a clocking means,
The timing means determines a false alarm prevention period in which the output of the first analog sensor exceeds the fire alarm threshold while the output of any of the other analog sensors does not exceed the fire alarm threshold. Timekeeping,
The transmitting means is configured to transmit a message requesting execution of a predetermined work regarding the first analog sensor to an information terminal used by the administrator when the false alarm prevention period continues for a certain period of time or more. The fire alarm system according to claim 4, characterized in that: The message requests the administrator to eliminate or investigate the non-fire cause, and includes at least a request to clean the first analog sensor, a request to replace components of the first analog sensor, and a request to replace the component parts of the first analog sensor. 6. The fire alarm system according to claim 5, further comprising any one of a sensor replacement request. Claim characterized in that the installation position information includes information indicating a correspondence relationship between each of the plurality of analog sensors and an analog sensor located within a certain installation distance from the analog sensor. 6. The fire alarm system described in 6.

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