JP2002162293A - Fire alarm and fire detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of fire judgment by directly examining the distribution pattern of a frequency spectrum for the central frequency intensity of a fire and preventing error information by a rotating lamp or the like. SOLUTION: A first fire judgment part judges whether the spectral pattern of the fire exists in a first prescribed frequency band 16 or not, if it exists, a second fire judgment part judges whether the spectral component of the rotating lamp exists in a second prescribed frequency band 17, if it does not exist, a third fire judgment part judges the fire if the integral value of a low frequency band component is prescribed times or more larger than the integral value of a high frequency band component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving detection signal output from a detection sensor for receiving light energy in a monitored area and converting the light energy into an electric signal. The present invention relates to a fire detector for judging a fire and a fire detection method.

[0002]

2. Description of the Related Art Conventionally, a fire detector for detecting a fire in a tunnel is installed in a predetermined monitoring area, for example, a wall surface or a ceiling in the tunnel, and detects a fire in both sides in the longitudinal direction of the tunnel. As such a fire detector, there is a fire detector that detects a fire by using a detection sensor that receives light or radiant heat from a flame and sends a fire signal to a disaster prevention receiver.

As a method of distinguishing between a fire flame and other non-fire sources, for example, a rotating lamp, the present inventors have applied a light receiving detection signal from a detection sensor that converts light energy to an electric signal to an MPU (microprocessor). A method has been proposed in which a fire is determined by frequency analysis using a fast Fourier transform method as input (JP-A-2000-57456).

In this fire detection method, it is effective to examine the intensity distribution of the frequency spectrum in a frequency band of 8 Hz or more in order to improve the discrimination performance from an energy radiation source such as a rotating light having periodic fluctuations. The following steps are taken.

[0005] (1) The first frequency band 0.5 including the center frequency of the fluctuation of the light energy of the flame from the light receiving detection signal.
A power spectrum component of Hz to 8.0 Hz is extracted by a fast Fourier transform method.

(2) The first frequency band 0.5 including the center frequency of fluctuation of the light energy of the flame from the received light detection signal.
8.5, which is a second frequency band that does not include a component of ~ 8.0 Hz and is a frequency higher than the first frequency band.
A power spectrum component of 1 Hz to 16.0 Hz is extracted by a fast Fourier transform method.

(3) When the extracted component in the first frequency band has a level equal to or higher than a first predetermined value and the extracted component in the second frequency band does not have a level equal to or higher than a second predetermined value, or when the ratio between the two is predetermined. If the value is greater than or equal to the value, it is determined that a fire has occurred.

As a result of the applicant's various experiments, the frequency of the substantial flame fluctuation is in the range of up to 8.0 Hz, while the frequency of the non-fire source rotating lamp exceeds 8.0 Hz. This is because it was found that there was a range. In the case of a general fire model, the center frequency f
It is known that c is 4.0 to 5.0 Hz or less, for example, at about 2.5 Hz or about 1.8 Hz.

[0009]

By the way, when the distribution pattern of the frequency spectrum of the flame and that of the rotating lamp obtained by the Fourier transform is compared, in the case of the flame, the peak relative intensity of the center frequency is stepwisely shifted on both sides thereof. While the relative intensity decreases, in the case of a rotating lamp, the relative intensity is extremely low at frequencies other than the fundamental component of the rotation frequency and a harmonic component that is an integral multiple of the rotation frequency.

[0010] Therefore, if the distribution pattern shape of the frequency spectrum itself obtained by the Fourier transform can be examined, the problem of false alarm by the rotating lamp can be solved.

However, an algorithm that can easily compare the difference in the distribution pattern shape between the frequency spectrum of the flame and the rotating light has not been established.
5-8.0 Hz frequency spectral component and 8.5H
A fire is determined by comparing the level of the frequency spectrum component of z to 16.0 Hz with the threshold value, and it is difficult to make a determination that sufficiently captures the difference between the distribution patterns of the frequency spectrum of the flame and the rotating light.

Since the MPU of the fire detector uses a low-power consumption MPU that operates at a very low-speed base clock of, for example, 1 MHz, the processing time for the fire detection processing especially when there is no fire is required. Is desired to be as short as possible.

According to the present invention, the distribution pattern of the frequency spectrum with respect to the intensity of the center frequency of the flame is directly examined to prevent false alarms caused by a rotating light or the like, thereby improving the reliability of fire judgment.
It is another object of the present invention to provide a fire detector in which the processing time for fire detection is reduced as much as possible in the case of no fire, thereby reducing the processing load on the MPU.

[0014]

In order to achieve this object, the present invention is configured as follows. (Fire detector) The present invention relates to a fire detector which receives a light-receiving detection signal output from a detection sensor which receives light energy and converts it into an electric signal, and inputs the light-receiving detection signal to a processor, and determines a fire by frequency analysis using a fast Fourier transform method. The present invention is characterized in that a complicated fire determination process is performed stepwise from a simple fire determination process for a detector.

That is, the fire detector of the present invention has a first frequency band (for example, 0.5 Hz to 8.0 Hz) including the center frequency of the fluctuation of the energy of the flame and a first frequency band not including the center frequency of the fluctuation of the flame. A light receiving detection signal including a signal component of a second frequency band (for example, 8.5 Hz to 16.0 Hz) including a frequency on the higher frequency side is sampled at a predetermined sampling frequency, and then Fourier-transformed to perform a first frequency band. And a Fourier transform unit for calculating a power spectrum component of the second frequency band, and a case where it is detected that a flame spectrum pattern exists in a specified frequency band (for example, 0.5 Hz to 5.0 Hz) in the first frequency band. A first fire determination unit that determines that there is a possibility of a fire, otherwise determines that a fire has not occurred, and ends the process; When it is determined that there is a possibility of a fire in the above, if it is detected that there is no harmonic component caused by the energy radiation source with periodic fluctuation on the second frequency band side, it is determined that there is a possibility of a fire. A second fire determination unit that determines that a fire has not occurred when detecting the presence of a harmonic component and terminates the process; and a case where the second fire determination unit determines that there is a possibility of a fire. Calculating an integral value of the power spectrum component of the first frequency band and an integral value of the power spectrum component of the second frequency band, wherein the integral value of the first frequency band is at least a predetermined number of times greater than the integral value of the second frequency band. A third fire determination unit that determines that a fire has occurred when the size is larger, and otherwise determines that no fire has occurred, and ends the process.

As described above, by performing the fire judgment in order from the simple processing to the complicated processing, false alarms due to the rotating lights and the like are prevented, the reliability of the fire judgment is improved, and there is no fire. In this case, it is possible to reduce the processing time of fire detection in a case where there is no fire by terminating the processing assuming that a fire has not occurred at a simple processing stage.

Here, the first fire judging section searches for at least three power spectrum components in descending order from the power spectrum components, and finds all the power spectrum components in a specified frequency band (for example, 0.5 Hz to 5.0 H).
If it exists in z), it is determined that there is a possibility of a fire, otherwise, it is determined that no fire has occurred and the process is terminated.

It has been found that in the case of a flame, the fluctuation center frequency is 4.0 Hz to 5.0 Hz or less, and that the intensity gradually decreases stepwise with the center frequency as a peak. In the case of a rotating lamp, it has been found that there is a harmonic component at a frequency (4.0 Hz, 6.0 Hz,...) That is an integral multiple of the peak of the fundamental component (for example, 2.0 Hz) of the rotating frequency. ing.

Therefore, the specified frequency band of 0.5 Hz to
When viewed at 5.0 Hz, in the case of a flame, all the frequencies of the three power spectrum components M1, M2, and M3 are included in descending order. In the case of a rotating lamp, the power spectrum components of the larger two power spectrum components M1 and M2 are included. Frequency 2.0Hz, 4.0H
Since only z is included, it is possible to determine whether it is a fire or a non-fire.

If the first fire determination unit determines that there is a possibility of fire, the first fire spectrum unit M3 multiplies a predetermined value (for example, 8) by a predetermined value (for example, 8) or more. Determines that there is a possibility of a fire, and if it is less than that, determines that no fire has occurred and terminates the process.

This is because the frequency spectrum of the rotating lamp fluctuates due to uneven rotation of the rotating lamp and the like. Therefore, the spectral component is detected at a position shifted from the peak of the fundamental component and the harmonic component. There is a possibility that the frequencies of the three power spectrum components M1, M2, and M3 are all included in the specified frequency band of 0.5 Hz to 5.0 Hz in descending order.

If the value obtained by multiplying the smallest component M3 by, for example, eight times is equal to or greater than the largest value M1 (the change in the power spectrum is gentle), it is determined that there is a possibility of fire, and the largest value M1 is determined. If it is less than (the power spectrum changes rapidly), it is determined to be due to, for example, a rotating light.

When the first fire determination unit determines that there is a possibility of a fire, the second fire determination unit sums the absolute value of the difference between each component with respect to the average value of the power spectrum components on the second frequency band side. Is calculated, and if this sum is less than the predetermined value, it is determined that there is a possibility of a fire. Otherwise, it is determined that no fire has occurred and the process is terminated.

This is because the substantial flame fluctuation frequency is the first
It has been found that while the frequency range is up to 8.0 Hz, which is the upper limit of the frequency band, the harmonic component of the non-fire source is up to 8.0 Hz.
Therefore, the second frequency band of 8.0 Hz to 16.
When the average value of 0 Hz is obtained and the difference between the average value and each component is obtained, the sum of the absolute values of the differences is small because there is almost no difference in the case of a flame, but in the case of a rotating lamp, the sum of the absolute values of the differences is small. Since the difference increases, the total value of the absolute values of the differences also increases, and it is possible to determine whether the fire or the rotating light.

The third fire determination unit determines that a fire has occurred when a value obtained by multiplying the integral value of the second frequency band by a predetermined value (for example, 3.25) is less than the integral value of the first frequency band. Otherwise, it is determined that no fire has occurred and the process is terminated.

This corresponds to the first frequency band (for example, 0.5H
Z to 8.0 Hz) and the integrated value of the second frequency band (for example, 8.5 Hz to 16.0 Hz),
In the case of a flame, it has been found that the integrated value of the first frequency band is larger than the integrated value of the second frequency band by a predetermined factor or more.
Therefore, the second frequency band of 8.5 Hz to 16.
For example, when a value obtained by multiplying the integrated value of 0 Hz by 3.25 is less than the integrated value of the first frequency band of 0.5 Hz to 8.0 Hz, it is determined that a fire has occurred. judge.

Further, according to the present invention, it is also possible to judge a fire by using each of the first fire judging section and the second fire judging section alone.

According to the present invention, there is provided a fire detector for inputting a light reception detection signal output from a detection sensor for receiving light energy and converting the light energy into an electric signal to a processor and determining a fire by frequency analysis using a fast Fourier transform method. And a signal component of a first frequency band including a fluctuation center frequency of light energy of the flame and a signal component of a second frequency band not including the fluctuation center frequency of the flame and including a frequency higher than the first frequency band. A Fourier transform unit that performs Fourier transform after sampling the light reception detection signal at a predetermined sampling frequency to calculate power spectrum components of the first frequency band and the second frequency band; A power spectrum component is searched, and all the searched power spectrum components are first.
A specified frequency band within the frequency band (for example, 0.5 Hz to
(5.0 Hz), it is determined that there is a possibility of a fire, and otherwise, it is determined that a fire has not occurred, and a fire determination unit that ends the process is provided.

In this case, if the fire determination unit determines that there is a possibility of a fire, the fire power is determined to be higher than the first power spectrum component by multiplying the third power spectrum component by a predetermined value (for example, 8). It is determined that there is a possibility, and in other cases it is determined that no fire has occurred and the process is terminated.

According to the present invention, there is provided a fire detection system in which a light reception detection signal output from a detection sensor that receives light energy and converts the light energy into an electric signal is input to a processor and a fire is determined by frequency analysis using a fast Fourier transform method. In the vessel,
A light-receiving detection signal including a signal component of a first frequency band including the fluctuation center frequency of the light energy of the flame and a second frequency band not including the fluctuation center frequency of the flame and including a frequency higher than the first frequency band. A Fourier transform unit that performs a Fourier transform after sampling at a predetermined sampling frequency to calculate power spectrum components of the first frequency band and the second frequency band, and a variation of each component of a power spectrum component on the second frequency band side. If it is less than a predetermined value, it is determined that there is a possibility of a fire, otherwise, it is determined that a fire has not occurred and a fire determination unit that ends the process is provided.

In this case, the fire determination unit calculates the sum of the absolute values of the differences between the respective components with respect to the average value of the power spectrum components in the second frequency band, and this sum is a predetermined value, for example, 50.
If it is less than 00, it is determined that there is a possibility of a fire, otherwise, it is determined that no fire has occurred.

(Fire Detection Method) According to the present invention, a light reception detection signal output from a detection sensor that receives light energy and converts it into an electric signal is input to a processor, and a fire is detected by frequency analysis using a fast Fourier transform method. It is intended to provide a fire detection method for determining a first frequency band including a fluctuation center frequency of light energy of a flame and a first frequency band not including a fluctuation center frequency of a flame and including a frequency on a higher frequency side than the first frequency band. A Fourier transform step of performing a Fourier transform after sampling the light reception detection signal including the signal components of the two frequency bands at a predetermined sampling frequency to calculate the power spectrum components of the first frequency band and the second frequency band; If it is detected that a flame spectrum pattern exists in a specified frequency band within one frequency band, a fire may occur. A first fire determination step of determining that no fire has occurred and terminating the process otherwise; and determining that there is a possibility of a fire in the first fire determination step, If it is detected that there is no harmonic component of the energy radiation source with periodic fluctuations in the two frequency bands, it is determined that there is a possibility of a fire, and if it is detected that a harmonic component is present, a fire occurs. A second fire determination step of ending the processing by determining that the fire has not been performed;
When it is determined in the second fire determination step that there is a possibility of a fire, an integrated value of the power spectrum component of the first frequency band and an integrated value of the power spectrum component of the second frequency band are calculated, and the integrated value of the first frequency band is calculated. A third fire determination step of determining that a fire has occurred when the integrated value is greater than or equal to the integrated value of the second frequency band by a predetermined factor or more, otherwise determining that no fire has occurred and terminating the process; ; Characterized by having;

Here, in the first fire determination step, at least three power spectrum components are searched in descending order from the power spectrum components, and if all the searched power spectrum components are present in the specified frequency band, the possibility of a fire is determined. It is determined that there is a fire, otherwise, it is determined that no fire has occurred, and the process is terminated.

That is, in the first fire determination step, when it is determined that there is a possibility of a fire, if the value obtained by multiplying the third power spectrum component by a predetermined value is equal to or more than the first power spectrum component, the possibility of a fire is determined. It is determined that there is a fire, and if it is less than that, it is determined that no fire has occurred and the process is terminated.

In the second fire determination step, when it is determined in the first fire determination step that there is a possibility of fire, the absolute value of the difference between each component and the average value of the power spectrum components on the second frequency band side is determined. The sum is calculated. If the sum is less than a predetermined value, it is determined that there is a possibility of a fire. Otherwise, it is determined that a fire has not occurred, and the process is terminated.

In the third fire determination step, a fire is determined when a value obtained by multiplying the integral value of the second frequency band by a predetermined value is less than the integral value of the first frequency band. Is determined not to have occurred, and the process is terminated.

According to the present invention, there is provided a fire detection method in which a light reception detection signal output from a detection sensor which receives light energy and converts the light energy into an electric signal is input to a processor, and a fire is determined by frequency analysis using a fast Fourier transform method. And a signal component of a first frequency band including a fluctuation center frequency of the light energy of the flame and a signal component of a second frequency band not including the fluctuation center frequency of the flame and including a frequency higher than the first frequency band. And a Fourier transform step of performing a Fourier transform after calculating the light reception detection signal containing the signal at a predetermined sampling frequency to calculate the power spectrum components of the first frequency band and the second frequency band; Search for at least three power spectrum components, and find all power spectrum components A fire judging step of judging that there is a possibility of a fire if it exists in a specified frequency band within one frequency band, and judging that no fire has occurred otherwise, and terminating the processing. It is characterized by.

In this fire determination step, when it is determined that there is a possibility of fire, if a value obtained by multiplying the third power spectrum component by a predetermined value is equal to or greater than the first power spectrum component, it is determined that there is a possibility of fire. Otherwise, it is determined that no fire has occurred, and the process is terminated.

According to the present invention, there is provided a fire detection method in which a light reception detection signal output from a detection sensor which receives light energy and converts the light energy into an electric signal is input to a processor and a fire is determined by frequency analysis using a fast Fourier transform method. And a signal component of a first frequency band including a fluctuation center frequency of the light energy of the flame and a signal component of a second frequency band not including the fluctuation center frequency of the flame and including a frequency higher than the first frequency band. A Fourier transform step of performing a Fourier transform after calculating the light reception detection signal including the following at a predetermined sampling frequency to calculate the power spectrum components of the first frequency band and the second frequency band; and a power spectrum on the second frequency band side If the variation of each component is less than the specified value, it is judged that there is a possibility of fire. There the fire determination step for ending the process is determined not to have occurred; characterized by comprising a.

In this fire determination step, the sum of the absolute values of the differences between the respective components with respect to the average value of the power spectrum components on the second frequency band side is calculated. If the sum is less than a predetermined value, there is a possibility of a fire. Otherwise, it is determined that no fire has occurred, and the process is terminated.

[0041]

FIG. 1 is a block diagram showing the configuration of a fire detector according to the present invention. In FIG. 1, a fire detector 1 includes a detection sensor 2 having an optical wavelength bandpass filter 3, a pre-filter 5, an amplifier 6, an AD converter 7, and an MPU 8.

The optical wavelength band-pass filter 3 has a characteristic of selectively passing a wavelength band having a high peak value at a wavelength of about 4.4 μm and having a high peak value by CO ₂ resonance radiation inherent to the flame. The light energy 4 incident from the monitoring area enters the detection sensor 2 through a component in a wavelength band centered on a wavelength of 4.4 μm. The optical wavelength bandpass filter 3 is provided as needed.

The detection sensor 2 receives the light energy incident through the optical wavelength bandpass filter 3, converts the light energy into an electric signal, and outputs a light reception detection signal. For example, a pyroelectric sensor can be used as the detection sensor 2. The pre-filter 5 passes a signal component of a predetermined wavelength band in a received light detection signal necessary for judging a fire from a spectrum pattern by the fast Fourier transform of the present invention, and a low-pass filter is used.

That is, in the present invention, for example, a frequency band of 0.5 Hz to 8.0 Hz, which is a substantial flame fluctuation frequency band including the center frequency of the flame fluctuation, for example, 1 including a frequency band of 0.5 Hz to 8.0 Hz.
A low-pass filter that passes a frequency band up to 6.0 Hz and cuts a frequency component of 16.0 Hz or more is used.

The amplifying section 6 has a range of 0 to 0 extracted by the pre-filter 5.
A light reception detection signal having a frequency component of 16.0 Hz is amplified. The AD converter 7 takes in the MPU 8 by sampling the light reception detection signal from the amplifier 6 at a predetermined sampling frequency and converting it into a digital light reception detection signal. The AD converter 7 is usually provided as an internal circuit of the MPU 8.
Is provided.

Here, the sampling frequency of the AD converter 7 is set to 32 Hz, which is twice as large as 16.0 Hz when the upper limit frequency for frequency analysis by the fast Fourier transform of the MPU 8 is 16.0 Hz. In the embodiment, the sampling frequency is set to twice as high as 64 Hz in order to improve the accuracy of the frequency analysis.

For this reason, in the fast Fourier transform in the MPU 8, power spectrum components up to 32 Hz can be analyzed. In the embodiment of the present invention, 16 of them can be analyzed.
Hz are treated as effective analysis results.

The MPU 8 converts the received light detection signal in the frequency band up to 16 Hz into digital data by sampling by the AD converter 7 and inputs the digital data, and performs a fast Fourier transform (F
A fire is determined by frequency analysis using FT).

FIG. 2 is a functional block diagram of an embodiment of the fire detection processing of the present invention realized by the program control of the MPU 8 in FIG.

In FIG. 2, this fire detection processing is performed by a Fourier transform unit 9, a first fire judgment unit 10, and a second fire judgment unit 1.
1, a third fire determination unit 12 and a timing control unit 13. The Fourier transform unit 9 performs a fast Fourier transform (FFT) on the received light detection signal input as sampling data to calculate a power spectrum component.

For example, the Fourier transform unit 9 applies a fast Fourier transform algorithm to the sampled data fetched by the AD converter 7 shown in FIG. 1 at a sampling frequency of 64 Hz and a sampling number N = 128 over a sampling period of 2 seconds, for example. Therefore, a complex spectrum component consisting of a real part and an imaginary part is calculated for a frequency band of 0 to 16.0 Hz.

Next, the power spectrum component is calculated by adding the squares of the real part and the imaginary part of the complex spectrum component in the frequency band of 0 to 16.0 Hz and performing an absolute value calculation for opening a square root.

FIG. 3A shows the calculation result of the power spectrum component of the received light detection signal obtained from the flame calculated by the Fourier transform unit 9 in FIG. 2, and is calculated at a pitch frequency of 0.5 Hz. 32 power spectrum components are calculated for a frequency band of 0.5 to 16.0 Hz.

Here, the frequency band from 0 to 16.0 Hz is as follows.
0.5-8.0 Hz first frequency band 14 and 8.5-1
It is divided into a second frequency band 15 of 6.0 Hz. The first frequency band 14 includes the fluctuation center frequency of the light energy of the flame. On the other hand, the second frequency band 15 is a region that does not include the center frequency of the fluctuation of the flame and that includes frequencies higher than the first frequency band 14. The high frequency side of the first frequency band 14 and the low frequency side of the second frequency band 15 may partially overlap.

For the first frequency band 14, 0.5
A first prescribed frequency band 16 of ~ 5.0 Hz is set, which is defined by a first fire determination unit 1 to be described later.
0 is a band used in the process of 0. 8.0-16.0
The second prescribed frequency band 17 of Hz is set on the second frequency band 15 side, and this band is used for the determination of the second fire determination unit 11 which will be described later.

0.5 to 16.0 Hz in FIG.
The power spectrum components at 32 points in the frequency band are represented by power spectrum components P1 to P32. In the pattern of the power spectrum component of the flame, the power spectrum component P5 of 2.5 Hz is the largest, and the distribution pattern has a power spectrum component that gradually decreases on both sides.

FIG. 3 (B) shows the calculation result of the power spectrum component in the frequency band of 0 to 16.0 Hz of the light reception detection signal obtained from the rotating lamp causing the non-fire report.
For example, a light receiving detection signal from a rotating lamp rotating at 2 Hz is taken as an example.

The power spectrum component of the rotating lamp has a fundamental component having a strong relative intensity with the rotation frequency of 2 Hz as a fundamental frequency f0, and the fundamental frequency f0 = 2 Hz
2f0 = 4 Hz, 3f0 = 6 Hz, 4f
There is a harmonic component that attenuates almost stepwise at 0 = 8 Hz,... 8f0 = 16 Hz, and the relative intensity is extremely low at other frequencies.

The 0 to 0 calculated by the Fourier transform unit 9 in FIG.
For the power spectrum component in the 16.0 Hz band, the first fire determination unit 10, the second fire determination unit 11, and the third
The fire determination unit 12 performs a fire determination step by step from simple processing to complicated processing. The timing control unit 13 controls the cooperation of the Fourier transform unit 9, the first fire determination unit 10, the second fire determination unit 11, and the third fire determination unit 12 with the start and end of the processing.

The first fire judging section 10 detects whether or not a flame spectrum pattern exists in a first prescribed frequency band 16 of 0.5 to 5.0 Hz in the first frequency band 14 of FIG. If there is a spectrum pattern of the above, it is determined that there is a possibility of a fire, and if there is no spectrum pattern of the flame, it is determined that a fire has not occurred and the process is terminated.

The first fire judging section 10 judges whether or not a flame spectrum pattern exists in the first prescribed frequency band 16 in the range of 0.5 to 16.0H as shown in FIG.
The three power spectrum components M1, M2, and M3 are searched in ascending order for the power spectrum components P1 to P32 of z, and the three searched power spectrum components M1 and M3 are searched.
It is determined whether all the frequencies of M2 and M3 are present in the first prescribed frequency band 16 of 0.5 to 5.0 Hz.

If all three power spectrum components M1, M2, and M3 searched in the descending order exist in the first prescribed frequency band 16, it is determined that there is a possibility of a fire. Transfer. On the other hand, if all of the three power spectrum components M1, M2, and M3 searched in the descending order do not exist in the first prescribed frequency band 16, it is determined that it is not a fire, and the process is terminated.

FIG. 4 shows the power spectrum components of the fire detection signal of the flame in the frequency band of 0 to 8.0 Hz when the first fire determination unit 10 determines that there is a possibility of a fire.

In the case of a flame, the fluctuation center frequency is 4.0H
For example, about 2.5 Hz or about 1.8 H below z to 5.0 Hz
It is known to be at z, and has a power spectrum pattern in which the intensity gradually decreases step by step with the fluctuation center frequency as a peak.

Therefore, the first fire judging section 10 sets the value of 0.1.
When three power spectrum components are searched in descending order for 32 power spectrum components in a frequency band of 5 to 16.0 Hz, as shown in FIG. 4, the largest power spectrum component is a component M1 having a frequency of 2.0 Hz and a second largest power spectrum component. The component M2 of 2.5 Hz is searched for the largest component, and the component M3 of 1.0 Hz is searched for the third largest component. Since all components are found in the first specified frequency band 16, there is a possibility that a fire may occur in this case. Is determined.

FIG. 5 shows that the power spectrum component of the rotating light judged as not a fire by the first fire judgment unit 10 is 0.
The frequency band of up to 8.0 Hz is shown. In the case of a rotating lamp, assuming that the rotation frequency is, for example, 2.0 Hz, this is set as a fundamental frequency f0 and a frequency that is an integral multiple thereof, that is, 2f0 = 4 Hz, 3f0 = 6 Hz, 4f0 = 8 Hz,.
・ ・ Has harmonic components.

For this reason, the rotating light of 0.5 to 16.0 Hz
The three power spectrum components M1 and M
2 and M3, the fundamental frequency fo =
2 Hz component M1, double frequency 2f0 = 4 Hz component M
The component M3 of 2 and 3 times frequency 3f0 = 6 Hz is searched, and the first and second power spectrum components M1, M2
Is included in the first prescribed frequency band 16 of 0.5 to 5.0 Hz, but does not include the third power spectrum component M3, thereby determining that the fire is not a fire.

Further, in the first fire judging section 10 shown in FIG. 2, the power spectrum component of the rotating lamp may be erroneously determined to be a fire due to the fluctuation of the frequency of the rotating lamp. , The largest power spectrum component M1 and the third largest power spectrum component M3
Is multiplied by a predetermined value, for example, a predetermined value = 8.
If, for example, the value obtained by multiplying the third value by eight is smaller than the largest power spectrum component M1, it is determined that there is no fire.

FIG. 6 shows a power spectrum component when a fire is erroneously determined due to fluctuations in the frequency of the rotating lamp. In the power spectrum component of the rotating light shown in FIG. 6, the rotating frequency is f0 = 2 Hz as a fundamental frequency. However, in an actual rotating light, unevenness of rotation, impact during emergency vehicle running, and other The fundamental frequency f0, which is the rotation frequency, depends on factors and the like.
May fluctuate slightly.

FIG. 6 shows power spectrum components when the fundamental frequency f0 fluctuates from 2.0 Hz to a lower frequency.
When such a fluctuation of the rotating frequency of the rotating lamp occurs, F
The power spectrum component obtained by the FT deviates from the peak portion. For this reason, when the first fire determination unit 10 searches for the three power spectrum components M1, M2, and M3 in descending order, in this case, the first power spectrum components M1, M2, and M3 are all 0.5 to 5.0 Hz.
It is included in the specified frequency band 16, and it is determined that there is a possibility of fire even though it is a power spectrum component of the rotating lamp.

Therefore, the largest power spectrum component M
Comparing, for example, a value obtained by multiplying the first and third smallest power spectrum components M3 by eight, M1> (8 × M3), and
Even if all of the three power spectrum components M1 to M3 are present in the first prescribed frequency band 16 in descending order, it is determined that a fire has not occurred in this case.

This largest power spectrum component M1
The reason for comparing the power spectrum component M3 with the third power spectrum component by a specified value is that in the case of a rotating lamp, the power spectrum component abruptly attenuates with respect to the peak value and has a steep pattern. It is determined that it is not a fire.

Next, the processing of the second fire judging section 11 of FIG. 2 will be described. The second fire determination unit 11 is activated when the first fire determination unit 10 determines that there is a possibility of a fire, and the second fire determination unit 11 of FIG.
Detects whether there is an energy radiation source with periodic fluctuations on the frequency band 15 side, for example, a harmonic component due to a rotating lamp. If it does not exist, it is determined that there is a possibility of a fire. It is determined that it has not been performed.

The second fire judging section 11 for judging whether or not the spectrum pattern of the rotating light exists in the frequency band on the high frequency side specifically performs the following arithmetic processing.

First, 8.0 to 1 on the second frequency band 15 side.
A second specified frequency band 17 of 6.0 Hz is set, and an average value is calculated for 17 power spectrum components. Next, the sum of absolute values of the difference between the calculated average value and each power spectrum component is calculated. Then, this sum is compared with a predetermined value, for example, 5000, which is experimentally obtained in advance, and a predetermined value 5000 is obtained.
If less than 500, it is judged that there is a possibility of fire and the specified value is 500
If it exceeds 0, it is determined that no fire has occurred.

The principle of the fire judgment process by the second fire judgment unit 11 is that the substantial power spectrum pattern of the flame exists in the first frequency band 14 up to 8 Hz, and the power spectrum component of the rotating lamp which is a non-fire source. Is 8H
Since it is known that there is a second frequency band 15 exceeding z, 8.0 to 8.0 including the second frequency band 15 is included.
The power spectrum components at 17 points in the second prescribed frequency band 17 of 16.0 Hz are examined for variations in the spectrum components with respect to the average value, and when the variations are large, it is determined that the power spectrum components of the rotating lamp are present. I have.

That is, 8.0 to 1 including the second frequency band 15
When the sum of the absolute values of the differences from the average value with respect to the 17 power spectrum components of the second prescribed frequency band 17 of 6.0 Hz is found, in the case of a flame, there is almost no difference as is clear from FIG. Therefore, in the case of the revolving light shown in FIG. 3B, the difference is larger than the average value, so that the total value becomes larger, thereby determining whether there is a possibility of a fire or not. Can be.

In the above embodiment, the dispersion of the spectral components is checked by the sum of the absolute values of the differences between the respective power spectral components in the second prescribed frequency band 17 and the average value of the respective power spectral components. Needless to say, it may be possible to check by the processing of. Further, as the second specified frequency band 17, a predetermined band including the second frequency band 15 can be appropriately set.

Next, the processing of the third fire determining unit 12 in FIG. 2 will be described. The third fire determination unit 12 is activated when the second fire determination unit 11 obtains a determination result indicating that there is a possibility of a fire,
With respect to the 32 power spectrum components at 0.5 to 16.0 Hz in FIG. 3, the distribution of the pattern is examined separately for the first frequency band 14 and the second frequency band 15 to make a comparison judgment.

That is, the third fire determination unit 12 calculates the integral value W of the power spectrum components P1 to P16 of the first frequency band 14.
L and the power spectrum component P1 of the second frequency band 15
The integral value WH of 7 to P32 is calculated. Subsequently, a value (3.25 WH) obtained by multiplying the integral value WH of the second frequency band by a predetermined value, for example, a predetermined value = 3.25, is compared with the integral value WL of the first frequency band. WL> (3.25 WH) In this case, it is determined that a fire has occurred. Otherwise, it is determined that a fire has not occurred, and the process is terminated.

The comparison judgment of the third fire judging unit 12 can be modified to (WL / WH)> 3.25 by using the ratio of the integral values, but the division processing for calculating the ratio is performed by the MPU. Takes a long time, so in the present invention, the processing load of the MPU is reduced as compared with the multiplication processing.

As described above, the processing of obtaining the integral value of the power spectrum component for each of the first frequency band 14 and the second frequency band 15 and comparing the magnitude relations is performed by the first fire determination unit 10 and the second fire determination unit 11 Although the processing takes the longest time as compared with the processing time, the discriminating performance of whether it is a flame or a non-fire source rotating light is sufficiently obtained.

Further, in the present invention, the first fire judging unit 10 and the second fire judging unit 11 make the third fire judging unit 1
Since the non-fire factors that cannot be removed by the determination process by No. 2 are removed in advance, the performance of the third fire determination unit 12 for determining a fire is extremely high.

FIG. 7 is a flowchart of the fire detection process of the present invention according to the embodiment of FIG. In the fire detection processing of the present invention, the light reception detection signal is converted into digital data by the AD converter 7 in step S1, and the digital data is acquired in step S2.
Performs FFT operation (fast Fourier transform) on
The power spectrum component is calculated at a pitch frequency of, for example, 0.5 Hz for a frequency band of Hz.

Subsequently, in step S3, the first fire determination unit 10
Is performed, and if there is no possibility of a fire in step S4, the process is immediately terminated. If there is a possibility of a fire, the second fire determination unit 11 performs a second fire determination state in step S5. If there is no possibility of a fire in step S6, the second fire determination process ends.

If there is a possibility of a fire, a third fire determination process is performed by the third fire determination unit 12 in step S7. If it is not a fire in step S8, the process is terminated. If it is a fire, a fire determination process is performed in step S9.
This fire determination process is a process of transmitting a fire detection signal to the receiver side in a fire detector.

FIG. 8 shows the fire determination process in step S3 of FIG. 7 as a subroutine. In the first fire determination process, in step S1, three power spectrum components M1, M2, and M3 are searched in ascending order for 32 power spectrum components in a frequency band of 0.5 to 16.0 Hz. Next, it is checked whether or not all of the power spectrum components M1, M2, M3 searched in step S2 are present in the first prescribed frequency band 16 of 0.5 to 5.0 Hz,
If it does not exist, the process ends. If it does, the process proceeds to step S3.

In step S3, the value obtained by multiplying the largest power spectrum component M1 and the third power spectrum component M3 by a predetermined value = 8 is compared, and (M3 × predetermined value) is found to be greater than the power spectrum component M1. If it is larger, it is determined that there is a possibility of fire, and if not, the process is terminated.
This prevents the power spectrum component of the rotating light from being erroneously determined to be a fire due to fluctuations in the rotating frequency of the rotating light as shown in FIG.

FIG. 9 shows the details of the second fire determination process in step S5 of FIG. 7 in a subroutine. In the second fire determination process, 8.0 to 16.0 in step S1.
First, the average value of the power spectrum components of the second prescribed frequency band 17 of Hz is calculated, and then the absolute value of the difference between the average value calculated in step S2 and each power spectrum component is added.

If the total value is smaller than the predetermined value = 5000 determined in advance in step S3, it is determined that there is a possibility of a fire, and the process returns to the main routine of FIG.
If it is not less than 00, for example, it is determined as the power spectrum component of the rotating lamp, and the process is terminated.

FIG. 10 shows the details of the third fire determination process in step S7 of FIG. 7 in a subroutine. In this third fire determination process, 0.5 to 8.0 in step S1.
Hz of the power spectrum component of the first frequency band 14 and the second frequency band 15 of 8.5 to 16.0 Hz.
Is calculated.

Next, in step S2, a value obtained by multiplying the integral value WL of the first frequency band 14 and the integral value WH of the second frequency band 15 by a predetermined value 3.25 is compared, and WL> (WH × predetermined value). If there is, it is determined that it is a fire, and the process returns to the main routine of FIG. 7; otherwise, a series of processes is ended.

In the above-described embodiment, the first fire judgment unit 10 and the second fire judgment unit 11 target the power spectrum components obtained by the fast Fourier transform of the received light detection signal.
And the processing of the third fire determination unit 12 is performed stepwise each time the possibility of a fire is determined. However, as another embodiment of the present invention, the first fire determination unit 10 and the second fire determination unit Each of the 11th and third fire determination units 12 can independently function as a fire detection process.

That is, in the embodiment of FIG. 2, the configuration of only the Fourier transform unit 9 and the first fire determination unit 10, the configuration of only the Fourier transform unit 9 and the second fire determination unit 11, and the Fourier transform unit 9 and the third fire determination unit Any embodiment of the configuration with the determination unit 12 can be adopted.

Further, in the processing of FIG. 7, fire determination is performed in the order of the first fire determination processing, the second fire determination processing, and the third fire determination processing. Can be combined in any order in the three fire determination processes, and when the three are combined, the reliability of the fire determination has the same result.

Further, the present invention includes appropriate modifications which do not impair the objects and advantages thereof, and is not limited by the numerical values shown in the above embodiments.

[0097]

As described above, according to the present invention, a non-fire factor such as a flame and a rotating light other than the flame is determined by using the power spectrum component obtained by the fast Fourier transform on the received light detection signal. By providing fire judgment processing in multiple stages and performing fire judgment processing in stages from simple processing, it is possible to accurately judge a fire when flames due to fire are detected, while in the case of non-fire, Since it is possible to determine that the fire is not a fire by simple fire determination processing and terminate the processing without performing more complicated fire determination processing, it is possible to reduce the processing time of fire detection when the fire is not a fire.

Also, in the present invention, the first fire judgment unit,
Although the fire judgment by the second fire judgment unit and the third fire judgment unit is performed step by step, each has the following effects.

The first fire judging section searches for at least three power spectrum components in descending order from the power spectrum components, and finds all the power spectrum components in a specified frequency band not exceeding the upper limit of the flame fluctuation center frequency. If there is a fire, it is determined that there is a possibility of fire.Otherwise, it is determined that a fire has not occurred. Non-fire factors such as can be eliminated.

The second fire judging section surely recognizes that it is not a fire by examining the power spectrum component, which is the harmonic component of the rotating lamp, in the specified frequency band where the power spectrum component of the flame hardly exists. Misinformation due to the above can be reliably prevented.

Further, the third fire judging unit compares the integrated value of the power spectrum component of the low frequency band where the power spectrum component of the flame exists and the integrated value of the power spectrum component of the high frequency band where the harmonic power spectrum component of the rotating lamp exists, thereby achieving extremely high reliability. High fire judgment can be made. In addition, in the comparison between the integrated value of the low frequency band and the integrated value of the high frequency band, a value obtained by multiplying the integrated value of the high frequency band by a predetermined value is compared with the integrated value of the low frequency band.
Compared to the processing of the MPU that calculates the ratio of the two and compares the magnitude relation, the processing load on the MPU is smaller, and a higher-speed fire determination process can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a fire detector according to the present invention.

FIG. 2 is a block diagram of a functional configuration of the present invention using the MPU of FIG. 1;

FIG. 3 is an explanatory diagram of a flame and a spectrum component of a rotating light obtained by Fourier transform.

FIG. 4 is an explanatory diagram of a first fire determination process for a spectral component of a flame.

FIG. 5 is an explanatory diagram of a first fire determination process for a spectrum component of a rotating light.

FIG. 6 is an explanatory diagram of a first fire determination process for a spectrum component of a rotating light when a frequency fluctuates.

FIG. 7 is a flowchart of a fire detection process according to the present invention.

FIG. 8 is a flowchart of a first fire determination process in FIG. 7;

FIG. 9 is a flowchart of a second fire determination process in FIG. 7;

FIG. 10 is a flowchart of a third fire determination process in FIG. 7;

[Explanation of symbols]

1: Fire detector 2: Detection sensor 3: Optical wavelength band-pass filter (4.4 μm narrow band-pass filter) 4: Light energy 5: Pre-filter 6: Amplifying unit 7: AD converter 8: MPU (Microprocessor 9: Fourier transform unit 10: First fire judgment unit 11: Second fire judgment unit 12: Third fire judgment unit 13: Timing control unit 14: First frequency band 15: Second frequency band 16: First specified frequency Band 17: Second specified frequency band

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[Procedure amendment]

[Submission date] December 25, 2000 (200.12.
25)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 18

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

[0022] Therefore (or changes in the power spectrum is slow) If the 1st small value components M3 which was 8 times for example that flies high value M1 or more, determines that there is potential for fire, No.1 large value M1 If it is less than (the power spectrum changes rapidly), it is determined to be due to, for example, a rotating light.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masato Aizawa 2-1043 Kami-Osaki, Shinagawa-ku, Tokyo F-term in Fuchiki Corporation (reference) 2G065 AA04 AB02 BA01 BB26 BC03 BC07 BC13 BC14 BC28 BC35 CA05 DA06 5C085 AA11 AB01 AC03 AC14 BA35 CA02 EA51 FA38

Claims (18)

[Claims] 1. A fire detector which inputs a light detection signal output from a detection sensor which receives light energy and converts it into an electric signal to a processor and determines a fire by frequency analysis using a fast Fourier transform method. A light receiving device that includes a first frequency band including a center frequency of fluctuation of light energy of the flame and a signal component of a second frequency band that does not include the center frequency of fluctuation of the flame and includes a frequency higher than the first frequency band. A Fourier transform unit that performs a Fourier transform after sampling the detection signal at a predetermined sampling frequency to calculate a power spectrum component of the first frequency band and the second frequency band; and a specified frequency band within the first frequency band. If the presence of a flame spectrum pattern is detected, it is determined that there is a possibility of a fire. A first fire determination unit that determines that a fire has not occurred and ends the process; and if the first fire determination unit determines that there is a possibility of a fire, the first fire determination unit involves a periodic variation on the second frequency band side. When it is detected that the harmonic component of the energy radiation source does not exist, it is determined that there is a possibility of a fire, and when it is detected that the harmonic component is present, it is determined that a fire has not occurred and the process is performed. A second fire determining unit to be terminated; and an integrated value of a power spectrum component of the first frequency band and a power spectrum component of the second frequency band when the second fire determining unit determines that there is a possibility of a fire. Is calculated, and the integral value of the first frequency band is calculated as the integral value of the second frequency band.
A third fire determination unit that determines that a fire has occurred when the value is greater than or equal to the integral value of the frequency band by a predetermined value or more, and otherwise determines that no fire has occurred and terminates the process. Features a fire detector. 2. The fire detector according to claim 1, wherein the first fire determination unit searches for at least three power spectrum components in descending order from the power spectrum components, and searches all power spectra. A fire detector characterized by determining that there is a possibility of a fire if the component exists in the specified frequency band, and otherwise determining that no fire has occurred and terminating the process. 3. The fire detector according to claim 2, wherein the first fire determining unit determines that there is a possibility of a fire.
When the value obtained by multiplying the third power spectrum component by the predetermined value is equal to or larger than the first power spectrum component, it is determined that there is a possibility of a fire. A fire detector characterized by terminating. 4. The fire detector according to claim 1, wherein the second fire judging unit, when the first fire judging unit judges that there is a possibility of a fire, the second frequency band side. Calculates the sum of the absolute values of the differences between the respective components with respect to the average value of the power spectrum components, and if the sum is less than a predetermined value, it is determined that there is a possibility of a fire; otherwise, no fire has occurred. A fire detector characterized in that the process is terminated after the determination. 5. The fire detector according to claim 1, wherein the third fire determination unit calculates a value obtained by multiplying an integral value of the second frequency band by a predetermined value to an integral value of the first frequency band. A fire detector characterized by determining that a fire has occurred when the value is less than the threshold value, and otherwise determining that no fire has occurred and terminating the process. 6. A fire detector which inputs a light detection signal output from a detection sensor which receives light energy and converts the light energy into an electric signal to a processor and determines a fire by frequency analysis using a fast Fourier transform method. A light receiving device that includes a first frequency band including a center frequency of fluctuation of light energy of the flame and a signal component of a second frequency band that does not include the center frequency of fluctuation of the flame and includes a frequency higher than the first frequency band. A detection signal, a Fourier transform unit that performs a Fourier transform after sampling at a predetermined sampling frequency to calculate a power spectrum component of the first frequency band and the second frequency band, and at least in descending order from among the power spectrum components. The three power spectrum components are searched, and all the searched power spectrum components are the first frequency components. A fire determining unit that determines that there is a possibility of a fire if the signal is present in a specified frequency band within the band, and otherwise determines that no fire has occurred and terminates the process. And fire detector. 7. The fire detector according to claim 6, wherein when the fire determination unit determines that there is a possibility of a fire, a value obtained by multiplying a third power spectrum component by a predetermined value is the first power spectrum component. A fire detector characterized by determining that there is a possibility of a fire when the power spectrum component is equal to or more than the power spectrum component, and otherwise determining that no fire has occurred and terminating the process. 8. A fire detector which inputs a light detection signal output from a detection sensor which receives light energy and converts the light energy into an electric signal to a processor and determines a fire by frequency analysis using a fast Fourier transform method. A light receiving device that includes a first frequency band including a center frequency of fluctuation of light energy of the flame and a signal component of a second frequency band that does not include the center frequency of fluctuation of the flame and includes a frequency higher than the first frequency band. A detection signal, performing a Fourier transform after sampling at a predetermined sampling frequency to calculate a power spectrum component of the first frequency band and the second frequency band; and a power spectrum component of the second frequency band. If the variation of the components is less than the specified value, it is determined that there is a possibility of a fire. Fire detectors, characterized in that it comprises a fire determination unit to terminate the constant and the process, the. 9. The fire detector according to claim 8, wherein the fire judging section calculates a sum of absolute values of a difference between each component with respect to an average value of the power spectrum components on the second frequency band side, A fire detector characterized in that if the sum is less than a predetermined value, it is determined that there is a possibility of a fire; otherwise, it is determined that no fire has occurred and the process is terminated. 10. A fire detection method in which a light reception detection signal output from a detection sensor that receives light energy and converts the light energy into an electric signal is input to a processor, and a fire is determined by frequency analysis using a fast Fourier transform method. A light receiving device that includes a first frequency band including a center frequency of fluctuation of light energy of the flame and a signal component of a second frequency band that does not include the center frequency of fluctuation of the flame and includes a frequency higher than the first frequency band. Performing a Fourier transform after sampling the detection signal at a predetermined sampling frequency to calculate a power spectrum component of the first frequency band and the second frequency band; and a specified frequency band within the first frequency band. If the presence of a flame spectrum pattern is detected, a fire may be determined. Is a first fire determination step of determining that a fire has not occurred and terminating the processing; and, if it is determined in the first fire determination step that there is a possibility of a fire, the first fire determination step is periodically performed on the second frequency band side. If it is detected that there is no harmonic component of the energy radiation source with fluctuation, it is determined that there is a possibility of a fire, and if it is detected that the harmonic component is present, it is determined that no fire has occurred. A second fire determination step of terminating the process, and when it is determined that there is a possibility of a fire in the second fire determination step, the integrated value of the power spectrum component of the first frequency band and the integrated value of the second frequency band The integrated value of the power spectrum component is calculated. If the integrated value of the first frequency band is larger than the integrated value of the second frequency band by a predetermined value or more, it is determined that a fire has occurred. Otherwise, a fire has occurred. Fire detection method characterized by third and fire determination step, with the ending judgment to processing no. 11. The fire detection method according to claim 10, wherein the first fire determination step searches for at least three power spectrum components in descending order from the power spectrum components, and searches all power spectrum components. A fire detection method comprising: determining that there is a possibility of a fire if a component exists in the specified frequency band; otherwise determining that a fire has not occurred and terminating the process. 12. The fire detection method according to claim 11, wherein the first fire determination step includes a step of multiplying a third power spectrum component by a predetermined value when it is determined that there is a possibility of a fire. A fire detection method comprising: determining that there is a possibility of a fire if the power spectrum component is equal to or more than the first power spectrum component; and determining that a fire has not occurred if the power spectrum component is less than the first power spectrum component and terminating the process. 13. The fire detecting method according to claim 10, wherein the second fire judging step is performed when the first fire judging step judges that there is a possibility of a fire. Calculates the sum of the absolute values of the differences between the respective components with respect to the average value of the power spectrum components, and if the sum is less than a predetermined value, it is determined that there is a possibility of a fire; otherwise, no fire has occurred. A fire detection method characterized in that the process is terminated after the determination. 14. The fire detection method according to claim 10, wherein the third fire determination step comprises the step of: multiplying an integral value of the second frequency band by a predetermined value to an integral value of the first frequency band. A fire detection method characterized by determining that a fire has occurred when the value is less than the threshold value, otherwise determining that no fire has occurred and terminating the process. 15. A fire detection method for receiving a light reception detection signal output from a detection sensor for receiving light energy and converting the light energy into an electric signal to a processor and determining a fire by frequency analysis using a fast Fourier transform method. A light receiving device that includes a first frequency band including a center frequency of fluctuation of light energy of the flame and a signal component of a second frequency band that does not include the center frequency of fluctuation of the flame and includes a frequency higher than the first frequency band. A detection signal, performing a Fourier transform after sampling at a predetermined sampling frequency to calculate a power spectrum component of the first frequency band and the second frequency band; and Search for three power spectrum components, and find all power spectrum components before A fire judging step of judging that there is a possibility of a fire if it exists in a prescribed frequency band within the first frequency band, and judging that no fire has occurred otherwise, and terminating the process. A fire detection method characterized in that: 16. A fire detecting method according to claim 15, wherein, when it is determined that there is a possibility of fire, the value obtained by multiplying a third power spectrum component by a predetermined value is equal to the first power spectrum component. A fire detection method comprising: determining that there is a possibility of a fire if the power spectrum component is equal to or more than the power spectrum component; otherwise, determining that no fire has occurred and terminating the process. 17. A fire detection method in which a light reception detection signal output from a detection sensor that receives light energy and converts it into an electric signal is input to a processor, and a fire is determined by frequency analysis using a fast Fourier transform method. A light receiving device that includes a first frequency band including a center frequency of fluctuation of light energy of the flame and a signal component of a second frequency band that does not include the center frequency of fluctuation of the flame and includes a frequency higher than the first frequency band. A detection signal, performing a Fourier transform after sampling at a predetermined sampling frequency to calculate a power spectrum component of the first frequency band and the second frequency band; and a power spectrum component of the second frequency band. If the variation of the components is less than the specified value, it is judged that there is a possibility of fire.Otherwise, a fire may occur. Fire detection method characterized by comprising: a fire determination step for terminating the determination and the process with no, the. 18. A fire detecting method according to claim 17, wherein said fire determining step calculates a sum of absolute values of differences between respective components with respect to an average value of the power spectrum components on the second frequency band side, A fire detection method comprising: determining that there is a possibility of a fire if the sum is less than a predetermined value; otherwise, determining that a fire has not occurred and terminating the process.