JP7637522B2 - Fire detectors - Google Patents

Description

The present invention relates to a fire detector.

Conventionally, fire detectors have been known that detect fires based on smoke generated in a target area (see, for example, Patent Document 1).

Patent Publication No. 2020-126700

Conventional fire detectors require smoke to be introduced into the detector, but there has been a demand for technology to detect fires without introducing smoke.

The present invention was made in consideration of the above problems, and aims to provide a fire detector that can reliably detect fires without introducing smoke.

In order to solve the above-mentioned problems and achieve the object, the fire detector described in claim 1 is a fire detector that detects a fire that occurs in a target area, and is equipped with a fire detection means that detects a fire that occurs in the target area based on sound speed information in the target area and an attenuation coefficient that indicates the degree of attenuation of sound waves in the target area, a transmitting means that transmits sound waves to the target area, and a receiving means that receives the sound waves, and the fire detection means performs a first process of calculating the sound speed information and the attenuation coefficient based on the sound waves received by the receiving means, a second process of identifying the temperature of the target area based on the calculated sound speed information and the attenuation coefficient, and a third process of detecting a fire that occurs in the target area based on the identified temperature.

In addition, the fire detector of claim 2 is the fire detector of claim 1 , wherein the fire detection means identifies the temperature and humidity of the target area in the second processing, and detects a fire occurring in the target area based on the identified temperature and humidity in the third processing.

Furthermore, the fire detector of claim 3 is the fire detector of claim 1 or 2 , wherein the wave receiving means comprises a first wave receiving means provided in the vicinity of the wave transmitting means and a second wave receiving means provided at a position farther away from the wave transmitting means than the first wave receiving means, and the fire detection means calculates at least the attenuation coefficient based on the sound waves received by the first wave receiving means and the second wave receiving means in the first processing.

Furthermore, the fire detector of claim 4 is a fire detector of any one of claims 1 to 3 , wherein the fire detection means calculates the sound speed information based on a propagation distance traveled by the sound wave transmitted from the transmitting means until it is received by the receiving means in the first processing, and the fire detector further includes a correction means for correcting the propagation distance.

According to the fire detector of claim 1, by detecting a fire occurring in a target area based on sound speed information and an attenuation coefficient, it is possible to reliably detect a fire, for example, without introducing smoke into the fire detector.
Furthermore, by detecting a fire occurring in a target area based on the temperature within the target area, it becomes possible to reliably detect a fire, for example.

According to the fire detector of claim 2 , by detecting a fire occurring in a target area based on the temperature and humidity in the target area, it becomes possible to reliably detect a fire, for example.

According to the fire detector described in claim 3 , by calculating at least the attenuation coefficient based on the sound waves received by the first wave receiving means and the second wave receiving means, for example, the accuracy of calculating the attenuation coefficient can be improved, thereby making it possible to reliably detect fires.

According to the fire detector of claim 4 , by correcting the propagation distance, for example, it is possible to calculate sound speed information using a propagation distance suitable for the environment in which the fire detector is installed, thereby making it possible to reliably detect fires.

FIG. 2 is a diagram showing an example of installation of a sensor according to the present embodiment. FIG. 2 is a block diagram showing a sensor. 13 is a flowchart of a fire detection process. FIG. 11 is a diagram illustrating an example of a change in propagation time over time. FIG.

Below, an embodiment of a fire detector according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment.

[Basic Concept of the Embodiment]
First, a basic concept of the present embodiment will be described. The present embodiment generally relates to a fire detector.

A "fire detector" is a device that detects fires occurring in a target area, and is a concept that includes, for example, reflective fire detectors and opposing fire detectors. In addition, possible methods for fire detectors to detect fires include, for example, quantitative and differential types.

The "target area" is the area in which fires are to be detected, and is a concept that includes any area, such as a parking space in a parking lot or a room in a building.

The term "reflective fire detector" refers to a concept that includes, for example, devices that detect fires using sound waves reflected by a reflective surface within a target area. The term "opposing fire detector" refers to a concept that includes, for example, devices that have a transmitting device and a receiving device that are separated from each other and are placed on either side of a target area, and that detect fires using sound waves that are output from the transmitting device and then directly received by the receiving device.

The term "quantitative" refers to a concept that includes methods of detecting fires based on the values of physical quantities in the target area (e.g., temperature, humidity, etc.). The term "differential" refers to a concept that includes methods of detecting fires based on the changes over time in physical quantities in the target area (e.g., slope, etc.).

In the embodiment described below, the "target area" is a parking space in a parking lot, and a quantitative method is used for a reflective fire detector. Other matters will be described in modified examples.

[Specific Contents of the Embodiment]
Next, the specific contents of the embodiment will be described.

(composition)
First, the configuration of a sensor according to the present embodiment will be described. Fig. 1 is a diagram showing an installation example of a sensor according to the present embodiment, and Fig. 2 is a block diagram showing the sensor. In Fig. 1, some components of the sensor 1 are shown as rectangles, and the overall shape of the sensor 1 is shown in an enlarged manner.

Detector 1 in FIG. 1 is a reflective fire detector, and is a device for detecting fires that occur, for example, in a parking space (i.e., a target area) in a parking lot. Detector 1 is a quantitative type (more specifically, a constant temperature type) that detects fires based on the temperature value of the parking space itself, and is installed, for example, on the ceiling, sends sound waves toward the floor surface, and receives the sound waves reflected by the floor surface.

As shown in FIG. 2, the detector 1 includes, for example, an acoustic unit 11, an alarm unit 12, a recording unit 13, and a control unit 14.

(Configuration - Sound wave section)
The sonic unit 11 transmits or receives sonic waves, and includes, for example, a transmitting unit 111, a first receiving unit 112A, and a second receiving unit 112B. Note that in the present application, any frequency band of sonic waves may be used, but for example, a case where a frequency band corresponding to ultrasonic waves is used will be described.

(Configuration-sound wave section-transmitting wave section)
The wave transmitting unit 111 is a wave transmitting means that transmits sound waves to a target area, and is provided at a predetermined position in the housing of the sensor 1, for example, as shown in Fig. 1. As this wave transmitting unit 111, for example, a known ultrasonic wave transmitter using a piezoelectric ceramic vibrator can be used.

(Configuration: Sound wave section: First receiving section)
The first wave receiving unit 112A is a wave receiving means for receiving sound waves, and is, for example, as shown in Fig. 1, a first wave receiving means provided near the wave transmitting unit 111. As the first wave receiving unit 112A, for example, a known ultrasonic receiver using a piezoelectric ceramic vibrator can be used (the same can be used for the second wave receiving unit 112B).

(Configuration: Sound wave section: Second receiving section)
The second wave receiving section 112B is a wave receiving means that receives sound waves, and is, for example, a second wave receiving means that is provided at a position farther away from the wave transmitting section 111 than the first wave receiving section 112A, as shown in FIG.

(Configuration - Alarm section)
The alarm unit 12 is an alarm means for outputting an alarm. As the alarm unit 12, for example, an indicator light or a speaker (neither of which are shown) can be used.

(Configuration - Recording Section)
The recording unit 13 is a recording means for recording programs and various data necessary for the operation of the sensor 1, and can be configured using, for example, a flash memory etc. The recording unit 13 stores distance information.

(Configuration-Recording section-Distance information)
"Distance information" is information for identifying the distance the sound wave propagates (i.e., the propagation distance); specifically, as illustrated by the dotted line in Figure 1, it is information for identifying the distance the sound wave propagates when the sound wave transmitted from the wave transmitting unit 111 is reflected by a reflecting object within the target area (i.e., an object to which the sound wave is reflected) and reaches the second wave receiving unit 112B.

In this embodiment, the distance information is explained by taking as an example a case where information corresponding to the length of the distance L between the ceiling and the floor surface in the vertical direction (the up-down direction in the drawing) is stored as the initial value of the distance information.

(Configuration - Control Unit)
The control unit 14 in FIG. 2 is also a control means for controlling the sensor 1, and specifically, is a computer comprising a CPU, various programs interpreted and executed on the CPU (including basic control programs such as an OS, and application programs that are started on the OS and realize specific functions), and an internal memory such as a RAM for storing the programs and various data.

The control unit 14, for example, conceptually functionally includes a fire detection unit 141 and a correction unit 142. The fire detection unit 141 is a fire detection means that detects a fire occurring in a target area based on sound speed information in the target area and an attenuation coefficient that indicates the degree of attenuation of sound waves in the target area. The correction unit 142 is a correction means that corrects the propagation distance. The processing performed by each part of the control unit 14 will be described later.

Note that "sound speed information" is information that indicates the sound speed in the target area. "Attenuation coefficient" is information that indicates the degree of attenuation of sound waves in the target area, and is determined, for example, according to the ratio between the amplitude of the sound wave before propagation in the target area and the amplitude of the sound wave after propagation in the target area.

(process)
Next, the fire detection process executed by the detector 1 configured as above will be described. Fig. 3 is a flowchart of the fire detection process (in the following description of each process, steps are abbreviated as "S"). The "fire detection process" is a process for detecting a fire in a parking space. The timing for executing this fire detection process is arbitrary, but for example, when the detector 1 is powered on, repeated execution is started, and the description will begin from the point where execution of the fire detection process starts.

First, in SA1 of FIG. 3, the fire detection unit 141 transmits sound waves from the wave transmitting unit 111, and receives the sound waves at the first wave receiving unit 112A and the second wave receiving unit 112B. Here, for example, the first wave receiving unit 112A receives the pre-propagation sound waves (hereinafter also referred to as "pre-propagation sound waves") transmitted from the wave transmitting unit 111 in the target area. Also, the second wave receiving unit 112B receives the post-propagation sound waves (hereinafter also referred to as "post-propagation sound waves") transmitted from the wave transmitting unit 111 and reflected by a reflecting object (e.g., the floor surface) in the target area.

Next, in SA2 of FIG. 3, the fire detection unit 141 measures the propagation time and amplitude and stores the measurement results. Note that "propagation time" is a concept that indicates the time it takes for a sound wave transmitted by a detector 1 to return to the detector 1, and corresponds to, for example, TOF (Time of Flight).

Specifically, the propagation time is measured as the time from when the transmitting unit 111 transmits the sound wave to when the second receiving unit 112B receives the "propagation sound wave". In addition, the amplitude of the "pre-propagation sound wave" received by the first receiving unit 112A and the amplitude of the "propagation sound wave" received by the second receiving unit 112B are also measured. These measurement results are then stored in the recording unit 13.

Next, in SA3 of FIG. 3, the fire detection unit 141 determines whether the propagation time and amplitude values measured in the most recent SA2 are different from the propagation time and amplitude values measured in the previous SA2. If it is determined that they are different (YES in SA3), it proceeds to SA4. On the other hand, if it is determined that they are not different (i.e., they are the same) (NO in SA3), it proceeds to SA1 and repeats the above-mentioned processing.

Here, for example, the temperature or humidity of the parking space in FIG. 1 may change, or a car may be parked in the parking space, causing the reflection surface of the sound waves to be located higher than in FIG. 1 (for example, on the top of the parked car), changing the propagation distance. In such cases, the propagation time and amplitude values measured in the most recent SA2 will differ from the propagation time and amplitude values measured in the previous SA2, so it is determined that they are different (YES in SA3) and the process moves to SA4.

Next, in SA4 of FIG. 3, the fire detection unit 141 measures the propagation time and amplitude N times (for example, 5 to 10 times, or 50 to 100 times, etc.) and stores the N measurement results (i.e., N sets of measurement results) in the recording unit 13. Note that the specific processing is the same as the processing in SA1 and SA2.

Next, in SA5 of FIG. 3, the fire detection unit 141 determines whether the propagation time is stable after the sudden time change in the N sets of measurement results measured in SA4. If it is determined that the propagation time is stable after the sudden time change (YES in SA5), it proceeds to SA6. On the other hand, if it is determined that the propagation time is not stable after the sudden time change (i.e., other than YES in SA5) (NO in SA5), it proceeds to SA7.

Figure 4 is a diagram illustrating the change in propagation time over time. For example, if a car parks in an empty parking space at time t1, as shown in Figure 4(a), the propagation time changes relatively significantly at time t1, and then becomes a constant value. Also, for example, if a fire breaks out at time t1 and the temperature of the parking space gradually rises, the propagation time will continue to change gently from time t1, as shown in Figure 4(b).

In the processing of SA5, for example, a method is applied in which if the propagation time changes as shown in FIG. 4(a), it is judged as "SA5 YES", and if the propagation time changes other than as shown in FIG. 4(a) (for example, if the propagation time changes as shown in FIG. 4(b)), it is judged as "SA5 NO". More specifically, for example, if the propagation time changes by more than a first width and then changes within a second width (a width that is much smaller than the first width), it may be judged as "SA5 YES", and if not, it may be judged as "SA5 NO".

Next, in SA6 of FIG. 3, the correction unit 142 performs a distance information correction process. The "distance information correction process" is a process for correcting and updating the distance information stored in the recording unit 13 of FIG. 2, that is, a process for correcting the propagation distance.

In the processing of SA6, for example, the propagation time from the measurement results of SA5 when it becomes stable after a sudden time change is used to calculate the propagation distance based on a predetermined calculation (the propagation distance is calculated by multiplying the value of the sound speed (here, for example, a predetermined value) by the propagation time), and information for identifying the calculated propagation distance is stored in the recording unit 13 as distance information indicating the corrected propagation distance, and is updated.

The propagation time used in this calculation is the propagation time that is stable after a sudden change in the N propagation times in the N sets of measurement results measured in SA4. That is, in the example of FIG. 4(a), the propagation time measured after timing t1 is used. After this, the process moves to SA1 and the above-mentioned processes are repeated.

Next, in SA7 after NO in SA5 in FIG. 3, the fire detection unit 141 determines the temperature based on the N sets of measurement results (i.e., N sets of propagation times, amplitudes of "pre-propagation sound waves", and amplitudes of "post-propagation sound waves"). Any specific method may be used to determine the temperature here, but for example, the following first to third methods may be used.

<First Method>
The first method uses a first equation for determining the speed of sound using temperature and humidity as variables, and a second equation for determining the attenuation coefficient using temperature and humidity as variables.

When using this first method, first, the distance information from the recording unit 13 is acquired, and then the propagation distance (propagation distance specified by the acquired distance information) is divided by the propagation time (measurement result) to calculate the calculation result as the sound speed.

Next, the attenuation coefficient is calculated by calculating "(20 ÷ distance) × log (amplitude of the "sound wave before propagation" ÷ amplitude of the "sound wave after propagation")" (note that the log base is "10"). Note that the "distance" in this formula indicates the propagation distance of the sound wave from the first receiving unit 112A to the second receiving unit 112B with respect to the sound wave reflected by the reflecting object as shown in Figure 1. This "distance" may be calculated by subtracting a predetermined distance (for example, a distance that is a predetermined propagation distance of the sound wave from the sound wave transmitted from the transmitting unit 111 to the first receiving unit 112A directly) (hereinafter, also referred to as the "distance from the transmitting unit 111 to the first receiving unit 112A") from the distance information recorded in the recording unit 13 in FIG. 2 (i.e., the distance that the sound wave transmitted from the transmitting unit 111 propagates until the sound wave reaches the second receiving unit 112B after being reflected by a reflecting object in the target area) (hereinafter, also referred to as the "distance from the transmitting unit 111 to the second receiving unit 112B"). Note that this predetermined distance may be a numerical value obtained by performing a predetermined experiment or simulation.

Alternatively, as a modified example, since the "distance from the wave transmitting unit 111 to the second wave receiving unit 112B" is much longer than the "distance from the wave transmitting unit 111 to the first wave receiving unit 112A", the "distance from the wave transmitting unit 111 to the first wave receiving unit 112A" can be ignored and the "distance from the wave transmitting unit 111 to the second wave receiving unit 112B" can be used as the "distance" in the formula for calculating the attenuation coefficient described above.

Next, the calculated sound speed value is substituted into the first equation, and the calculated attenuation coefficient is substituted into the second equation to derive two mutually independent equations with temperature and humidity as variables. Next, the temperature and humidity are calculated based on these derived two equations to determine the calculated temperature.

For the above-mentioned first and second formulas, publicly known formulas may be used, or formulas defined based on a specified experiment or simulation may be used.

<Second Method>
The second method uses another equation that shows the relationship between temperature and sound speed. When using this second method, the sound speed is calculated in the same manner as in the above-mentioned case, and the temperature is calculated by applying the calculation result to the other equation, and the calculated temperature is identified.

<Third Method>
The third method is a method using predetermined table information showing the relationship between temperature and humidity and sound speed and attenuation coefficient. When using this third method, the sound speed and attenuation coefficient are calculated in the same manner as in the above-mentioned case, and the temperature and humidity corresponding to the calculated sound speed and attenuation coefficient are obtained by referring to the table information, and the obtained temperature is specified.

Next, in SA8 of FIG. 3, the fire detection unit 141 determines whether or not a fire has occurred based on the temperature identified in SA7. Specifically, it is assumed that a temperature threshold value that serves as a criterion for determining whether a fire has occurred is set in advance. If the temperature identified in SA7 is below the temperature threshold value, it is determined that a fire has not occurred (NO in SA8), and the process ends without detecting a fire. On the other hand, if the temperature identified in SA7 is equal to or higher than the temperature threshold value, it is determined that a fire has occurred (YES in SA8), and a fire is detected, and the process proceeds to SA9.

Here, for example, in SA7, N temperatures are identified based on N sets of measurement results, and if a predetermined number or more of the N temperatures are equal to or above a temperature threshold, it may be determined that a fire has occurred, or if the average value of the N temperatures is equal to or above a temperature threshold, it may be determined that a fire has occurred.

Next, in SA9 of FIG. 3, the fire detection unit 141 notifies the occurrence of a fire by transmitting a fire signal indicating that a fire has occurred to a disaster prevention receiver (not shown) and/or by outputting an alarm via the alarm unit 12.

Next, in SA10 of FIG. 3, when the fire detection unit 141 receives a recovery signal (i.e., a signal to restore the state for reporting a fire) transmitted from the disaster prevention receiver, the fire detection unit 141 ends the reporting of the fire and recovers. This concludes the explanation of the fire detection process.

(Effects of the embodiment)
Thus, according to this embodiment, by detecting a fire occurring in a target area based on sound speed information and attenuation coefficient, it is possible to reliably detect a fire without introducing smoke into detector 1, for example.

Furthermore, by detecting a fire occurring in a target area based on the temperature within the target area, it is possible to reliably detect a fire, for example.

Furthermore, by calculating at least the attenuation coefficient based on the sound waves received by the first receiving section 112A and the second receiving section 112B, for example, the accuracy of the calculation of the attenuation coefficient can be improved, making it possible to reliably detect fires.

[Modifications to the embodiment]
Although the embodiment of the present invention has been described above, the specific configuration and means of the present invention can be modified and improved as desired within the scope of the technical ideas of each invention described in the claims. Such modifications will be described below.

(About the problem to be solved and the effects of the invention)
First, the problems that the invention aims to solve and the effects of the invention are not limited to those described above, and may vary depending on the implementation environment of the invention and the details of the configuration, and may solve only some of the problems described above or achieve only some of the effects described above.

(Regarding decentralization and integration)
In addition, the above-mentioned configuration is a functional concept, and does not necessarily have to be physically configured as shown in the drawings. In other words, the specific form of distribution or integration of each part is not limited to that shown in the drawings, and all or part of it can be functionally or physically distributed or integrated in any unit.

(Regarding the receiving section)
In the above embodiment, the first wave receiving unit 112A is provided, but this component may be omitted. In that case, for example, a predetermined value may be used as the amplitude value of the "pre-propagation sound wave."

(Fire Determination)
In the above embodiment, the occurrence of a fire is determined (i.e., a fire is detected) based on temperature in SA8 in Fig. 3, but this is not limiting. For example, SA7 may be configured to specify humidity in addition to temperature, and SA8 may be configured to determine the occurrence of a fire using humidity in addition to temperature. In such a configuration, a fire occurring in the target area is detected based on the temperature and humidity in the target area, making it possible to reliably detect a fire, for example.

(Regarding the correction section)
The correction unit 142 may be configured to perform the following first to third correction processes. Each of these correction processes may be performed, for example, when the detector 1 is installed, or at any other arbitrary timing.

<First Correction Process>
The first correction process is a process of performing correction based on a user's operation. In this case, for example, an operation means (e.g., a DIP switch or the like) for inputting distance information to the detector 1 is provided, and when the user inputs distance information through the operation of the operation means, the correction unit 142 acquires the input distance information and stores it in the recording unit 13 to perform correction.

<Second Correction Process>
The second correction method is a method of correction based on communication. In this case, for example, when distance information is transmitted to the detector 1 from an external device (such as a user's terminal device or a disaster prevention receiver), the correction unit 142 receives the distance information and stores it in the recording unit 13 to perform correction. Note that the method of transmitting the distance information here is arbitrary, and may be, for example, a signal in wired communication, radio waves in wireless communication, or sound wave communication.

<Third Correction Process>
The third correction method is a method of correction using a correction jig. Fig. 5 is a diagram showing the correction jig. The correction jig 900 is a device used to correct distance information, and includes a reflector 901 that reflects sound waves that are a predetermined distance from the sensor 1. Correction propagation distance information for specifying the propagation distance of sound waves when the correction jig 900 is installed is stored in advance in the recording unit 13.

Then, when the user presses the correction operation button (not shown) of the detector 1 after installing the correction jig 900, the correction unit 142 measures N sets of propagation times and amplitudes by performing a process similar to SA4 in FIG. 3, and stores the measurement results. Next, the correction unit 142 calculates the propagation distance specified by the correction propagation distance information of the recording unit 13 divided by the measured propagation time (more specifically, the average value of N measured propagation times), and calculates the calculation result as the sound speed under the current environment. Next, when the user removes the correction jig 900 and presses the correction operation button (not shown) of the detector 1 again, the correction unit 142 measures N sets of propagation times and amplitudes by performing a process similar to SA4 in FIG. 3, and stores the measurement results. Next, the correction unit 142 performs a calculation of the calculated sound speed value multiplied by the measured propagation time (more specifically, the average of N measured propagation times), calculates the calculation result as the propagation distance of the target area (e.g., the parking space in FIG. 1), and corrects the calculated propagation distance by storing information specifying the calculated propagation distance as distance information in the recording unit 13.

When configured in this way, by correcting for the propagation distance, for example, sound speed information can be calculated using a propagation distance appropriate for the environment in which the detector 1 is installed, making it possible to reliably detect fires.

(Differential type)
The above-mentioned sensor 1 may also be configured as a differential type. In this case, for example, since a fire can be detected even if the absolute value of the propagation distance is deviated, SA6 in FIG. 3 may be omitted. In this case, after YES in SA5, SA6 may not be executed and the process may proceed to SA1. In addition, when configured in this way, in SA8, for the N temperatures identified in SA7, the slope of a straight line showing the change in temperature when the horizontal axis is the elapsed time and the vertical axis is the temperature value may be calculated, and the calculated slope may be compared with a predetermined slope for fire judgment, and whether or not a fire has occurred may be judged based on the comparison result.

(Regarding the facing type)
The sensor 1 may be configured as an opposed type. In this case, for example, the sensor 1 is separated into a first device having at least the wave transmitting unit 111 and the first wave receiving unit 112A, and a second device having the second wave receiving unit 112B, and these devices are arranged to face each other across the target area, so that the devices communicate with each other. In this case, after YES in SA3 in FIG. 3, SA4 to SA6 may be omitted, and SA7 to SA10 may be executed.

(Other application examples)
Furthermore, a configuration may be adopted in which, based on the results of measuring the propagation time or amplitude, a target object in a target region or a distance to the target object is detected.

(Features)
Furthermore, the features of the above-described embodiments and the features of the modifications may be combined in any manner.

(Additional Note)
The fire detector of Appendix 1 is a fire detector that detects a fire that occurs in a target area, and is equipped with a fire detection means that detects a fire that occurs in the target area based on sound speed information in the target area and an attenuation coefficient that indicates the degree of attenuation of sound waves in the target area.

The fire detector of Appendix 2 is the fire detector of Appendix 1, further comprising a wave transmitting means for transmitting sound waves to the target area and a wave receiving means for receiving the sound waves, and the fire detection means performs a first process of calculating the sound speed information and the attenuation coefficient based on the sound waves received by the wave receiving means, a second process of identifying the temperature of the target area based on the calculated sound speed information and the attenuation coefficient, and a third process of detecting a fire occurring in the target area based on the identified temperature.

The fire detector of Appendix 3 is the fire detector of Appendix 2, in which the fire detection means identifies the temperature and humidity of the target area in the second process, and detects a fire occurring in the target area based on the identified temperature and humidity in the third process.

The fire detector of Supplementary Note 4 is the fire detector of Supplementary Note 2 or 3, in which the wave receiving means comprises a first wave receiving means provided near the wave transmitting means and a second wave receiving means provided at a position farther from the wave transmitting means than the first wave receiving means, and the fire detection means calculates at least the attenuation coefficient in the first process based on the sound waves received by the first wave receiving means and the second wave receiving means.

The fire detector of Supplementary Note 5 is a fire detector as described in any one of Supplementary Notes 2 to 4, in which the fire detection means calculates the sound speed information based on a propagation distance that the sound wave transmitted from the wave transmitting means travels until it is received by the wave receiving means in the first process, and the fire detector further includes a correction means for correcting the propagation distance.

(Effect of supplementary notes)
According to the fire detector described in Appendix 1, by detecting a fire occurring in a target area based on sound speed information and an attenuation coefficient, it is possible to reliably detect a fire, for example, without introducing smoke into the fire detector.

The fire detector described in Appendix 2 can reliably detect a fire occurring in a target area based on the temperature within the target area, for example.

The fire detector described in Appendix 3 can reliably detect a fire occurring in a target area based on the temperature and humidity within the target area, for example.

According to the fire detector described in Appendix 4, by calculating at least the attenuation coefficient based on the sound waves received by the first wave receiving means and the second wave receiving means, for example, the accuracy of calculating the attenuation coefficient can be improved, thereby making it possible to reliably detect a fire.

According to the fire detector described in Appendix 5, by correcting the propagation distance, for example, sound speed information can be calculated using a propagation distance appropriate for the environment in which the fire detector is installed, making it possible to reliably detect fires.

Reference Signs List 1: Detector 11: Sound wave unit 12: Alarm unit 13: Recording unit 14: Control unit 111: Wave transmission unit 112A: First wave receiving unit 112B: Second wave receiving unit 141: Fire detection unit 142: Correction unit 900: Correction jig 901: Reflector L: Distance

Claims (4)

A fire detector that detects fires occurring in a target area,
A fire detection means for detecting a fire occurring in the target area based on sound speed information in the target area and an attenuation coefficient indicating the degree of attenuation of sound waves in the target area ;
A wave transmitting means for transmitting a sound wave to the target area;
A wave receiving means for receiving a sound wave,
The fire detection means includes:
A first process of calculating the sound speed information and the attenuation coefficient based on the sound wave received by the wave receiving means;
A second process of identifying a temperature of the target region based on the calculated sound speed information and the attenuation coefficient;
and a third process of detecting a fire occurring in the target area based on the identified temperature.
Fire detector. The fire detection means includes:
In the second process, a temperature and a humidity of the target area are identified;
In the third process, a fire occurring in the target area is detected based on the identified temperature and humidity.
2. The fire detector of claim 1 . The wave receiving means is
A first wave receiving means provided in the vicinity of the wave transmitting means;
A second wave receiving means is provided at a position farther from the wave transmitting means than the first wave receiving means,
The fire detection means includes:
In the first processing, at least the attenuation coefficient is calculated based on the sound waves received by the first wave receiving means and the second wave receiving means.
3. A fire detector according to claim 1 or 2 . The fire detection means includes:
In the first process, the sound speed information is calculated based on a propagation distance over which the sound wave transmitted from the wave transmitting means is received by the wave receiving means,
The fire detector comprises:
A correction means for correcting the propagation distance is further provided.
A fire detector according to any one of claims 1 to 3 .

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