JP2606749B2 - Fire detection method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a fire detection technology based on an infrared detection method, and more particularly to a method for separating incident infrared light into a plurality of wavelength bands, and detecting the infrared intensity of each separated wavelength band. With a sensor, calculate the temperature from the output ratio, calculate the fire area from the infrared intensity of any wavelength band and the sensor output,
The present invention relates to a fire detection method for judging a fire and grasping the progress of a fire from a temperature and an area.

[Prior Art] Many fire detection methods and apparatuses for automatically detecting the occurrence of a fire have been proposed. These are intended to detect the presence or absence of a fire within a certain monitoring range,
It is demanded that fires can be detected with high sensitivity with less malfunction due to a heat source that is not a fire such as a stove.

Until now, fire detectors using, for example, phototubes and bimetals have been provided.However, phototubes are sensitive to wavelengths in the ultraviolet region, and are susceptible to malfunction due to sunlight or light from electric lamps. There is. on the other hand,
Bimetallic types are too low in sensitivity and poor in effectiveness.

Under these circumstances, there has recently been a great deal of interest in infrared detection methods for detecting infrared rays emitted from flames. In such an infrared detection method as well, one step forward from the simple method of judging a fire when simply detecting infrared light of a certain level or more, is to check whether the output signal level of the infrared detector is increasing for a certain time or more. A fire detector incorporating an identification circuit has been proposed.
No. 56-7196).

In order to improve reliability, the infrared radiation
Efforts have been made to develop a technology for detecting separately in different wavelength bands and determining whether there is a fire based on such information. One is to use two types of sensors, a sensor that detects the visible or near-infrared region and a sensor that detects the infrared, and compare the intensity of visible or near-infrared radiation such as radiation from electric lights. When the radiation intensity in the infrared region is large, it is determined that a fire is not occurring.

Another method is to detect a peculiar spectral distribution. In general, the spectral distribution of infrared radiation emitted from an infrared radiation source without a flame follows the law of blanks as shown by the solid lines A and C in FIG. 2, and the peak value of the spectrum shifts to shorter wavelengths as the temperature of the heating object increases. .
In contrast, infrared emitting objects with flames exhibit other unique properties. That is, as shown by a solid line B in FIG. This is caused by a phenomenon known as CO ₂ molecular resonance radiation,
It shows a high peak around 4.3 μm. Therefore, in principle, a flame can be detected by detecting a peak near a wavelength of 4.3 μm due to the CO ₂ molecule resonance radiation.

Therefore, some attempts have been conventionally proposed to catch the peak at the wavelength of 4.3 μm. For example, Japanese Patent Application Laid-Open No. 50-2497 detects a radiation dose at 4.3 μm and two wavelengths before and after 4.3 μm, and determines that a flame is present when the radiation dose at 4.3 μm and the other two wavelengths exceeds a certain value. I have. Japanese Patent Application Laid-Open No. 57-96492 proposes that the occurrence of a flame is detected by determining whether or not a valley exists between two convex portions.

[Problems to be Solved by the Invention] However, when the radiation intensity in the visible or near-infrared region is larger than the radiation intensity in the infrared region such as electric light, it is determined that the fire is not a fire. Although false alarms are reduced, for example, if a heating element other than a fire such as an electric heater does not emit visible or near-infrared rays or if it is weak, a fire will be judged and a false alarm will be issued. Many.

In the method of detecting the radiation dose at the wavelength 4.3 μm and the two wavelengths before and after that, and judging it as a flame when the radiation dose at 4.3 μm and the other two wavelengths exceeds a certain value, it is not possible to detect the flame. If possible, it is not possible to detect whether the flame is from a fire or a useful heat source. That is, there is a defect that a false alarm is generated by a flame of a gas range, a gas stove, or the like.

Furthermore, the conventional fire detection device focuses on when and when to determine the occurrence of a fire and reports the occurrence of the fire, and there is no device that can accurately grasp the progress of the fire.

An object of the present invention is to eliminate the above-described drawbacks, to minimize false alarms based on a useful heat source in a living environment such as an electric heater, a gas stove, a stove, and to detect a fire with high sensitivity and to determine the progress of the fire. It is an object of the present invention to provide a fire detection method that can detect a fire.

[Means for Solving the Problems] The present inventors have considered based on the phenomenal difference between fire and non-fire, and found the following difference.

That is, in the case of a heat source other than a fire, the heating area and the temperature reach a steady state within a certain or several minutes. For example, in a heating appliance or the like, the heat generation area is constant, and the temperature reaches a steady state within several minutes. In addition, matches, lighters, etc., not only have constant temperature and heat generation area, but also disappear in seconds or minutes.

On the other hand, in the case of a fire, both the heating area and the temperature increase,
In addition, there is a characteristic that it shows an increasing tendency even after several minutes. FIG. 3 shows the temperature change in the process from the smoldering state to the fire, and FIG. 4 shows the change in the heating area. Here, TF is the point of time of inflammation. Further, in the case of a fire that does not pass through a smoldering state, for example, a fire such as an arson, etc., FIG.
It shows the temperature change and the heat generation area change after the TF point.

Furthermore, in the case of fire, if the emitted infrared rays are separated into multiple wavelength bands ranging from short to long wavelengths, the detection output of each wavelength band will increase with time, and the temporal change in the ratio of the detection output will also be a unique behavior. Is shown. In other words, while the magnitude of the detection output reflects the area and temperature of the heat-generating part,
Since the ratio of the detection output reflects the temperature of the heat-generating part, in the case of a smoldering fire, the detection output of each wavelength and the ratio of the detection output both tend to increase gradually, and at the time of transition to a flaming fire Thus, the detection output and its ratio increase rapidly.
After that, since the temperature rise tends to be saturated with the increase in the area of the heat source, the detection output increases, but the ratio becomes almost constant. Then, at the time of the transition to the flaming fire, the resonance emission of the CO ₂ molecule increases remarkably, and the intensity increases as the fire area increases. On the other hand, in the case of a flame other than a fire, such a temporal change is not observed after reaching a steady state.

The present invention has been made based on the above findings, and calculates the temperature of an infrared source based on the ratio of the outputs of a plurality of infrared detectors that detect two or more wavelength bands of infrared radiation emitted from a monitoring area. From this temperature, the infrared radiation intensity of any of the above-mentioned wavelength bands is obtained, and the heat generation area is calculated based on the infrared radiation intensity and the output of the infrared detector that detects the wavelength band to determine the fire situation. .

In addition, one of the infrared detectors includes an infrared detector for detecting a resonance radiation wavelength band of CO ₂ molecules, and the temperature and heat calculated by a predetermined calculation formula based on the outputs of the other infrared detectors. the black body radiation intensity of the infrared source at the resonant wavelength band of CO ₂ molecules from the area calculated, and its value, CO ₂
It is proposed to detect the presence or absence of resonance emission of CO ₂ molecules by comparing the output of an infrared detector that detects the resonance emission wavelength band of the molecule, and to judge a fire when the resonance emission is detected.

[Action] According to the above-described means, in the case of a useful heat source involving a flame such as a gas stove or a stove, although resonance emission of CO ₂ molecules is detected, the area is not increased and after a certain time,
Since it settles in a steady state, it can be determined that there is no fire. In addition, in the case of a useful heat source without a flame such as an electric heater, not only the area becomes a steady state after a certain period of time but also the resonance emission of CO ₂ molecules is not detected, so that it is judged as non-fire. As a result, a malfunction due to a useful heat source can be eliminated, fire detection can be performed with high accuracy, and the progress of a fire can be grasped by displaying an increase in area on a monitor or the like.

[Specific description of the invention] Fig. 1 is a basic configuration diagram of a fire detection device to which the method of the present invention is applied. The infrared light emitted from the infrared light source S enters the infrared light detection unit D. In the infrared detecting section D, the infrared light is separated into a plurality of wavelength bands, and the infrared intensity in each wavelength band is detected.

The infrared detecting section D includes a rotary chopper 1 for periodically separating infrared rays, a band pass filter 2a, 2b, 2c, 2d including, but not limited to, four optical filters each having a different transmission band. Infrared detectors 3a, 3b, 3 for detecting transmitted infrared rays in connection with filters 2a to 2d
c, 3d. The center wavelength of the transmission band of the bandpass filters 2a to 2d is, for example, 2 to 3 μm for the filter 2a and 3 to 4.5 μm for the filter 2b in the case of the four-division system shown here.
m, filter 2c is 4 ~ 5.5μm, filter 2d is 8 ~ 15μ
An appropriate wavelength is selected within the range of m, and the transmission wavelength bandwidths are each 0.1 to 1.5 μm. One of these filters 2a to 2d is selected to transmit the resonance radiation wavelength band (4.3 μm) of the CO ₂ molecule. here,
The filter 2b transmits the resonance radiation wavelength band of the CO ₂ molecule. Further, the wavelength band of 5.5 to 8 μm is avoided because the absorption by water vapor in the air is very large.
The number of divided wavelength bands is not limited to four as described above, and can be divided into any number of two or more. However, three divisions are possible, and practically five to six divisions are sufficient. .

The optical filter is formed by alternately vacuum depositing ZnSe, ZnS, Ge, or another dielectric material on a substrate such as Si to form a multilayer film, and the film thickness is determined according to a target transmission wavelength band.

As the infrared detectors 3a to 3d, a semiconductor infrared detector,
Although any of a thermopile and a pyroelectric infrared detector can be used, a semiconductor infrared detector is not suitable because it requires cooling, and a thermopile or a pyroelectric infrared detector is desirable, and a pyroelectric one is particularly preferable. . Further, the chopper 1 can be omitted when a thermopile is used for the infrared detector.

The pyroelectric detector is one in which electrodes are formed on the front and back surfaces of a thin plate of a pyroelectric material represented by lithium tantalate or PbxZryO ₃ by vapor deposition or the like. When detecting a near-infrared region near a wavelength of 1 μm, a Si photodiode can be used.

A pulse motor, a DC motor, or the like is suitable for rotationally driving the chopper 1, but a DC motor requires a rotation detector 4 such as a photo interrupter for detecting the number of rotations of the chopper. When the chopper is driven by the pulse motor, the number of rotations can be known from the drive circuit, so that the photo interrupter is unnecessary.

Output signals from the infrared detectors 3a to 3d and chopper rotation detection signals are processed by the signal processing circuit 10. The signal processing circuit 10 calculates the magnitude of the output from each of the infrared detectors 3a to 3d, the relative ratio of those outputs, and their temporal changes, and determines whether the target infrared source is a fire based on the result. When it is determined that a fire has occurred, a drive signal for an alarm or monitor is output.

FIG. 5 shows a configuration example of the signal processing circuit 10. Output signals from the infrared detectors 3a to 3d are amplified by amplifier circuits 11a, 11b, 11c, 11
d and amplified to the desired level. The amplified detection output is A / D converted by the A / D converters 17a to 17d, supplied to the synchronous detection circuit 13, and detected. The detection output of the synchronous detection circuit 13 is supplied to a signal processing device 18 composed of a microcomputer or the like, and by taking the root mean square of the two detection outputs shifted in phase by 90 °, the positional shift between the chopper and the infrared detector is obtained. And so on, and the phase shift due to the above is removed.

Further, the signal processing device 18 performs a calculation every few seconds by a timer interrupt or the like based on the synchronous detection output, and increases the temperature and heat generation area of the infrared source, and furthermore, the data on the presence or absence of CO ₂ molecule resonance radiation for several minutes. Is accumulated, and based on the data, it is checked whether the temperature and the heating area are constantly increasing. If the temperature and the heating area are increasing, it is determined that a fire has occurred, the alarm 20 is driven, and the calculated increase in the heating area is checked. Monitor 21
Or to be displayed.

In the embodiment, the synchronous detection circuit 13 and the signal processing device 18 are shown as separate functional circuits. However, these may be replaced by one microcomputer, and each function may be processed by the microcomputer.

Next, a method of calculating the temperature and the heat generation area in the signal processing device 18 will be specifically described.

The intensity per unit area of the light receiving surface of the infrared light incident on the infrared detectors 3a to 3d is Pa, Pb, Pc, Pd, and the synchronous detection circuit 1
Assuming that the output of 3 is Va, Vb, Vc, Vd, Va to Vd are Va = Pa · Aa Vb = Pb · Ab Vc = Pc · Ac Vd = Pd · Ad, respectively. Here, Aa to Ad are constants determined by characteristics of sensors, filters, and amplifiers. By the way, according to Planck's law of radiation, the blackbody radiation intensity per unit area of infrared rays emitted by an object at a certain temperature T in half space at a wavelength λ is expressed by the following equation.

Here, C ₁ and C ₂ are constants determined by C ₁ = 2πhc ² and C ₂ = h · c / k. Here, h is Planck's constant, c is light speed, and k is Boltzmann's constant.

By substituting the detection wavelength bands λ ₁ and λ _{2 of the two} detectors and the infrared intensities P ₁ and P ₂ in the wavelength bands into the above equation (1), an approximate expression for obtaining the temperature T is derived. Becomes

Here, the infrared intensities P ₁ and P ₂ of λ ₁ and λ ₂ in the above equation (2)
Is the detection output V of the outputs of the detectors 3a and 3b in the wavelength bands of λa and λb.
When expressed by replacing a and Vd, equation (2) is Becomes Here C 'is a constant Aa of the detection output of each wavelength band to a constant C _2, a constant by the action of Ad. It can be seen that by providing infrared detectors of two different wavelengths from the above equation, the fire or the temperature of the heating element can be determined from the output ratio.

Next, from the temperature T obtained by the above equation (3), the blackbody radiation intensity per unit area at λa (this is expressed as Pa ′) is obtained from Planck's radiation law, that is, equation (1).

On the other hand, since the infrared radiation emitted from the heating element is dispersed or absorbed by air, the incident intensity on the detector does not match the radiation intensity of the object, and is inversely proportional to the distance between the detector and the radiating object . Also, since Pa 'is the blackbody radiation intensity per unit area, the incident intensity on the detector is considered to be proportional to the area. According to the experience of the present inventors, the detection output Va ′ of the detection system at the wavelength λa is expressed by the following equation (4). And it was found that it was in good agreement with the actual detection output Va. Here, S is the area of the radiating object, Aa is a constant based on the characteristics of the sensor, filter, and amplifier at λa,
l is the distance between the detector and the radiating object. Therefore, the area S of the radiating object is given by Can be calculated.

In this embodiment, the heat generation area is obtained by using the equation (5) to grasp the progress of the fire.

In the above description, the method of obtaining the temperature T and the area S of the heating element using the detection outputs of the detectors 3a and 3d has been described. However, similarly, the detection output of the detectors 3a and 3c or the detection output of the detectors 3c and 3d is used. The temperature and area of the body may be obtained.

Further, according to the experience of the present inventors, if the detector used for the calculation is changed according to the magnitude of the detected temperature T, the temperature and the area can be calculated more accurately.

FIG. 6 shows λa = 3 μm λc = 5 μm λd = 8 as the center wavelength of the detectors 3a, 3c, 3d in the embodiment of FIG.
The figure shows the relative ratio of the detection output of each detector when 5 μm is selected. In the figure, it is shown that the closer to the apex of the triangle, the greater the ratio of the output in that wavelength band. From the figure, it can be seen that when the temperature of the heating
It can be seen that the temperature dependence of the ratio of the detection outputs of c and λd is large, and that at 400 ° C. or higher, the temperature dependence of the ratio of the detection outputs of λa and λc is large. That is, when detecting a heating element in a relatively low temperature range of 300 to 400 ° C. or less, the detectors 3a and 3d
In the case of detecting the heat generation in a high temperature range of 400 ° C. or higher, a good measurement accuracy can be obtained by combining the outputs of the detectors 3a and 3c. Therefore, by preparing three types of wavelength bands for temperature measurement, it is possible to accurately measure the temperature and the area in a wide temperature range from a low temperature to a high temperature.

The temperature T of the heat generating portion by the method described above, calculates the area S, the resonance of the CO ₂ by substituting a wavelength Ramudaco ₂ resonance radiation band of temperature T and CO ₂ in the formula (1) showing the Planck's law the radiation The radiation intensity Pco ₂ in the band is calculated, and this is calculated using the equation (5).
By substituting the area S calculated by
The detection output Vb in the CO ₂ resonance radiation band λco ₂ can be estimated. Vb obtained here is based on the assumption that the heating element is a black body, and when the heating element is a flame, as shown in FIG.
A strong peak is observed in the resonance emission band of CO ₂ . Therefore, the detected output Vb 'estimated here is compared with the detected output Vb actually obtained from the detector 3b, and when Vb is larger than the estimated value Vb', it can be determined that the heating element is a flame.

(Example) An experimental device having three infrared detectors having center wavelengths of 3.629 μm, 4.736 μm, and 12.048 μm, respectively, was installed at a height of 2.4 m from the floor, and a 16 × 16 cm heater was used. The panel, the detection of the flame of methanol in a 10 × 10 cm container, and the ignition experiment of 10 newspapers of 18 × 18 cm placed on the heater panel were performed. The monitoring area of the detector in the above embodiment was a circle having a diameter of 7 m.

FIG. 7 shows the detection output of each detector in the experimental machine,
100 in the temperature range of 100 to 800 ° C with the area of the heat source as 256 cm ²
The relative ratio of the theoretical value calculated by using the equations (1) and (4) is shown for each ° C.

On the other hand, FIG. 8 shows the relative ratio of the detection output of each detector of the experimental machine when the heater panel was heated. The surface temperature of the heater panel was measured with a thermometer during heating of the heater panel.
After 400 minutes, the temperature reached 400 ° C.

The theoretical values in FIG. 7 and the experimental results in FIG. 8 agree very well, which explains that the setting of the constant used in the arithmetic expression from the output of the experimental machine is correct.

FIG. 9 (A) shows the temporal change of the temperature calculated by using equation (3) from the output of the detector at the center wavelength of 3.629 μm and the detector of 12.048 μm in the heating experiment of the heater panel. Have been. In the figure, the highest temperature among the values measured by the other plural thermometers is plotted with a circle, and the average temperature thereof is plotted with a triangle. From this, it can be seen that the temperature calculation formula (3) used is correct at 100 ° C. or higher.

Further, FIG. 9 (B) shows a temporal change in the area of the heat source obtained from the output of the experimental machine using the equation (5) in the heating experiment of the heater panel. In the figure, the dashed line H indicates the size of the heater panel, which shows that the calculation formula (5) of the area of the heat source used by the experimental machine from about 150 ° C. or more agrees with the actual one. I understand.

Further, FIG. 9 (c) shows the blackbody radiation intensity in the CO ₂ resonance wavelength band calculated based on the output of the detector at the center wavelength of 3.3629 μm and 12.04 μm in the heating experiment of the heater panel. Expected detector output Vc from Pco ₂
The ratio between o ₂ ′ and the actual experimental machine output Vco ₂ from the detector having the center wavelength of 4.736 μm (hereinafter referred to as the CO 2 ratio) is shown. In the figure, the calculated value is close to 1 when the wavelength is 4.736.
This means that the μm detector has not detected the CO ₂ resonance radiation component.

On the other hand, FIG. 10 (A) shows the temporal change of the temperature output by the experimental machine in the methanol flame detection experiment.
FIG. 10 (B) also shows a change in the area of the heat source output from the experimental machine in the methanol flame detection experiment.
In this experiment, the area of the methanol flame used the container (10 ×
It came out smaller than 10cm). However, in the case of the experimental methanol flame, the temperature inside the container does not become uniform, and the temperature becomes higher toward the center. Therefore, it can be considered that the experimental machine output the area of the high temperature part. Since the CO2 ratio was over-scaled (4 to 5 times the blackbody radiation), the illustration is omitted.

FIG. 11 (A) shows the temporal change of the temperature output by the experimental machine in the newspaper ignition experiment, FIG. 11 (B) shows the temporal change of the area, and FIG. The change in ratio is shown.

In this newspaper ignition experiment, it was observed that the newspaper started to smoke about 10 minutes after the heater was started and ignited about 17 minutes later. Newspapers burned within tens of seconds after ignition.

From FIGS. 11 (A) to 11 (C), the temperature, the area, and the CO2 ratio sharply rise at the time of the transition from the smoldering state to the flaming state, which agrees well with the actual situation. At the time when 20 minutes have passed after the start of the experiment, the steady state is almost the same as that of the heater panel experiment. This is because the lower heater panel became visible after the newsprint burned.

According to the above experimental results, according to the fire detection method of the above embodiment, the temperature and the area of the heat source can be measured with considerable accuracy by paying attention to the noise generated when the temperature is low. Therefore, it is possible to grasp in real time the situation of the expansion of the heat generating portion in the case of a fire spread or the like, to display an increase in the heat generating area on a monitor or the like in a security room, or to issue an appropriate alarm.

[Effects of the Invention] As described above, the present invention calculates the temperature of an infrared source based on the ratio of the outputs of a plurality of infrared detectors that detect two or more wavelength bands of infrared radiation emitted from a monitoring area, From this temperature, the infrared radiation intensity of any of the above-mentioned wavelength bands is obtained, and the heat generation area is calculated based on the infrared radiation intensity and the output of the infrared detector that detects the wavelength band, so as to determine the fire situation. Therefore, in the case of a useful heat source with a flame such as a gas stove or stove, although resonance emission of CO ₂ molecules is detected, the area does not increase, and after a certain period of time, it settles to a steady state, and as a result a non-flame it is possible to determine, in the case of beneficial heat without a flame like electric heater, not only the area becomes a steady state after a certain time, resonance radiation of CO ₂ molecules can be determined that the non-fire order not detected As a result, it is possible to eliminate a malfunction caused by a useful heat source, to enable accurate fire detection, and to grasp the progress of the fire by displaying the fire on an area increase monitor or the like. .

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing one embodiment of a fire detection system to which a fire detection system according to the present invention is applied, and FIG. 2 shows a relationship between an infrared wavelength radiated from an infrared radiation source and an amount (relative value). FIG. 3 is a diagram showing a temperature change when a fire occurs, FIG. 4 is a diagram showing a change in a heating area when a fire occurs, FIG. 5 is a circuit diagram showing an embodiment of a signal processing circuit, FIG. 6 is a diagram showing the relative ratio of the detection output of each detector of the fire detection system, FIG. 7 is a diagram showing the relative ratio of the theoretical value of the detection output of each infrared detector in the experimental machine, and FIG. 8 is a heater panel FIG. 9 is a diagram showing the relative ratio of the detection output of each infrared detector when observed with an experimental device. FIG. 9 is a graph showing the change in temperature calculated from the detection output of each infrared detector when the heater panel was observed with the experimental device. And detection of each infrared detector when observing the heater panel with an experimental machine Diagram showing the change in the heat generation area calculated from the force and the change in the CO2 ratio calculated from the detection output of each infrared detector when the heater panel was observed with the experimental device. FIG. 11 shows a change in the temperature calculated from the detection output of each infrared detector at the time of the change, and a change in the heat generation area calculated from the detection output of each infrared detector when the methanol flame is observed with the experimental device. , The temperature change calculated from the detection output of each infrared detector when the newspaper ignition experiment was observed with the experimental machine, and the heating area calculated from the detection output of each infrared detector when the newspaper ignition experiment was observed with the experimental machine FIG. 6 is a diagram showing a change in CO2 ratio calculated from a detection output of each infrared detector when a newspaper ignition experiment was observed with an experimental machine. 1 ... Chopper, 2a ~ 2d ... Bandpass filter, 3a ~
3d… Infrared detector, 4… Rotation detector.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroomi Sato 2-9-1-1, Tobita-Shi, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Institute (56) References JP-A-64-74695 (JP, A) JP-A-60-46433 (JP, A) JP-A-50-2497 (JP, A)

Claims (4)

(57) [Claims] In a fire detecting apparatus using an infrared detector, an infrared ray radiated from a monitoring area is transmitted at a central wavelength of 2 to 3 μm, 3 to 4.5 μm, 4 to 5.5 μm, and 8 to 15 μm.
Λa, where the transmission wavelength bandwidth is in the range of 0.1 to 1.5 μm.
A filter for separating the light into λb, λc, and λd, and four infrared detectors for respectively detecting the infrared light transmitted through the filters are provided. Among these infrared detectors, the resonance radiation wavelength band (4.3 μm) of CO ₂ molecules is set. Output V other than infrared detector to detect
a, Vc, Vd The temperature T of the infrared source is calculated by the following formula. From this temperature, the infrared radiation intensity of any one of the above wavelength bands is obtained, and based on the infrared radiation intensity and the output of the infrared detector for detecting the infrared light of the wavelength band, formula A fire detection method characterized in that a heat generation area S is sequentially calculated by the following formula, and a fire or a non-fire is determined based on a temporal change of the heat generation area obtained by the above equation. 2. A fire detecting apparatus using an infrared detector, wherein infrared rays radiated from a monitoring area are transmitted at central wavelengths of 2 to 3 μm, 3 to 4.5 μm, 4 to 5.5 μm, and 8 to 15 μm, respectively.
Λa, where the transmission wavelength bandwidth is in the range of 0.1 to 1.5 μm.
A filter for separating λb, λc, and λd, and four infrared detectors for respectively detecting infrared light passing through the filters are provided. Among these infrared detectors, the resonance radiation wavelength band (4.3 μm) of CO ₂ molecules is set. Output V other than infrared detector to detect
a, Vc, Vd The temperature T of the infrared source is calculated by the following formula. From this temperature, the infrared radiation intensity of any one of the above wavelength bands is obtained, and based on the infrared radiation intensity and the output of the infrared detector for detecting the infrared light of the wavelength band, formula The fire detection method is characterized in that a heat generation area S is sequentially calculated by the following formula, and a fire is determined when the heat generation area obtained by the above equation is increasing. 3. A fire detecting apparatus using an infrared detector, wherein infrared rays radiated from a monitoring area are transmitted at central wavelengths of 2 to 3 μm, 3 to 4.5 μm, 4 to 5.5 μm, and 8 to 15 μm, respectively.
Λa, where the transmission wavelength bandwidth is in the range of 0.1 to 1.5 μm.
A filter for separating λb, λc, and λd, and four infrared detectors for respectively detecting infrared light passing through the filters are provided. Among these infrared detectors, the resonance radiation wavelength band (4.3 μm) of CO ₂ molecules is set. Output V other than infrared detector to detect
a, Vc, Vd The temperature T of the infrared source is calculated by the following formula. From this temperature, the infrared radiation intensity of any one of the above wavelength bands is obtained, and based on the infrared radiation intensity and the output of the infrared detector for detecting the infrared light of the wavelength band, formula The heat generation area S is sequentially calculated by the following formula, and a fire or a non-fire is determined based on the temporal change of the heat generation area obtained by the above equation, and the infrared source is determined from the temperature T and the heat generation area S calculated by the above equation. calculate the blackbody radiation intensity at the resonant wavelength band of CO ₂ molecules, the calculated values, the heating element by comparing the output of the infrared detector to detect resonance radiation wavelength band of CO ₂ molecules of the infrared detector A fire detection method characterized in that the presence or absence of a flame is determined. 4. A fire detecting apparatus using an infrared detector, wherein infrared rays radiated from a monitoring area are respectively transmitted at central wavelengths of 2 to 3 μm, 3 to 4.5 μm, 4 to 5.5 μm, and 8 to 15 μm.
Λa, where the transmission wavelength bandwidth is in the range of 0.1 to 1.5 μm.
A filter that separates into λb, λc, and λd, and four infrared detectors that detect infrared rays that have passed through the filters are provided. Among these infrared detectors, the resonance emission wavelength band of CO2 molecules (4.3 μm) is detected. Output V other than infrared detector
a, Vc, Vd The temperature T of the infrared source is calculated by the following formula. From this temperature, the infrared radiation intensity of any one of the above wavelength bands is obtained, and based on the infrared radiation intensity and the output of the infrared detector for detecting the infrared light of the wavelength band, the following is obtained. formula Is calculated sequentially, and it is determined that a fire occurs when the heat generation area calculated by the above equation is increasing, and
The black body radiation intensity at the resonant wavelength band of CO ₂ molecules infrared source and a temperature T and the calculated heat generation area S calculated by formula, its calculated values, resonance radiation of CO ₂ molecules of the infrared detector A fire detection method characterized by comparing the output of an infrared detector for detecting a wavelength band and determining that the heating element has a flame when the output of the detector is larger than the above calculated value. .