JP2019075138A - Flame detector - Google Patents

Abstract

To provide a flame detector capable of accurately determining presence of combustion flame on the basis of simultaneity of temporal change of a light reception output by a plurality of light reception units for a plurality of wavelength bands of a radiation energy radiated from the combustion flame.SOLUTION: In a flame detector 10, a plurality of light reception units 12a and 12b is provided. The light reception units 12a and 12b observe different wavelength band portions of radiation energy, and output corresponding light reception signals E1 and E2. A determination part 15 checks, for a predetermined time period, correlations each between the light reception signals observed and output at each of substantially same moments by the light reception units 12a and 12b as one of factors to be used for determination on presence of combustion flame, and permits the determination on presence of combustion flame on the basis of the integrated light reception signals E1 in the case where the correlation is strong, meanwhile suppresses the determination on presence of combustion flame in the case where the correlation is weak.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a smoke detector in which a sensor main body provided with a smoke detector is disposed in a sensor cover.

  Conventionally, in a flame detection device that detects radiation energy generated by flame combustion and detects the presence or absence of flame, it is generated at flame combustion to discriminate between flames and infrared radiators other than flames. Two-wavelength, three-wavelength, etc. flame detection that detects the radiation intensity in a plurality of wavelength bands including wavelength bands due to resonance radiation of CO 2 and detects the presence or absence of a flame based on the relative ratio of detected values in the plurality of wavelength bands Devices and flame detection methods are well known.

  Here, the two-wavelength and three-wavelength flame detection devices in the prior art will be briefly described.

  FIG. 14 is a conceptual diagram showing a radiation spectrum in the infrared wavelength range of a combustion flame and other typical radiators, the horizontal axis showing the wavelength of radiation, and the vertical axis showing the relative intensity of radiation.

  As shown in FIG. 14, in the spectral characteristic 100 of the combustion flame, there is a peak of relative radiation intensity in a wavelength band around 4.5 μm due to resonance radiation of CO 2, and a characteristic existing near this peak wavelength As a wavelength, for example, a wavelength band having a low relative radiation intensity exists in the vicinity of 5.1 μm on the long wavelength side.

  In addition, it is known that the peak of the radiation intensity by the resonant radiation of CO2 exists in a 4.3 micrometer band theoretically. However, when the combustion flame is actually observed, it is empirically shown that the peak of the radiation intensity appears in the vicinity of 4.4 to 4.5 μm. Therefore, in the following, unless otherwise specified, the CO2 resonance radiation band refers to the 4.4 to 4.5 μm band.

  And, in a two-wavelength type flame detection device, for example, each radiation energy in a wavelength band around 4.4 to 4.5 μm and a wavelength band around 5.1 μm can be detected by a narrow band optical wavelength band pass filter Selective transmission (pass), the radiation energy is detected by the light reception sensor, and this radiation is photoelectrically converted, and then given processing such as amplification is performed to obtain an electrical signal (hereinafter referred to as “light reception signal”) corresponding to the amount of energy. The relative ratio of the light reception signal level of each wavelength band is obtained, and the presence or absence of a flame is determined by comparing with a predetermined threshold.

  As a result, infrared emitters other than flames, for example, high-temperature emitters such as sunlight (6000.degree. C.) shown in spectral characteristic 102, relatively low temperature radiators shown in spectral characteristic 104 at about 300.degree. C., spectral characteristics It is possible to distinguish between a low temperature radiator or the like such as a human body shown in 106 and a flame.

  Also, for example, in addition to the two wavelengths described above, radiation energy in a wavelength band around 3.8 μm, for example, on the short wavelength side with respect to the 4.4 to 4.5 μm band that is a resonant emission band of CO 2 is There is also known a three-wave type flame detection device which detects by the same method and determines the presence or absence of a flame by the relative ratio of light reception signals in these three wave bands, and the discrimination performance between flames and infrared emitters other than flames Is further improved.

  When such a flame detection device is installed in a tunnel to monitor vehicle flames in a road tunnel, the flame detection device has detection areas in both the left and right directions, and is disposed adjacent to each other along the longitudinal direction of the tunnel. For example, the detection areas are continuously arranged at intervals of 25 m or 50 m so that detection areas with the flame detector overlap each other in a complementary manner. Further, as a light receiving element, for example, a pyroelectric material is used.

Japanese Patent Publication No. 55-33119 Japanese Examined Patent Publication 59-34252 Patent No. 3357330 gazette

  By the way, in the conventional flame detection device, each light reception signal by the radiation energy in the wavelength band around 4.5 μm due to the resonant radiation of CO 2 from the combustion flame and the wavelength band around 5.1 μm which does not include this wavelength band Although the relative ratio of the levels is taken and the presence or absence of the flame is determined by comparison with a predetermined threshold value, depending on the setting of the threshold value, it may be assumed that the presence or absence of the flame can not be accurately determined. In order to judge more accurately, it is desirable to incorporate elements other than the relative ratio of light reception signal levels of different wavelength bands to judge the presence or absence of a flame.

  The present invention provides a flame detection device capable of reliably determining the presence or absence of a combustion flame based on the simultaneousness of temporal changes in light reception output by a plurality of light reception units for a plurality of wavelength bands of radiation energy radiated from a combustion flame. Intended to be provided.

  Here, the light receiving unit is a light receiving sensor including an optical wavelength filter and a photoelectric conversion unit including a light receiving element, and the photoelectric conversion signal from the light receiving sensor is appropriately processed, for example, amplified and processed as necessary. It refers to a signal detection circuit unit including an electric circuit that outputs as

(Flame detector)
The present invention is a flame detection device that observes radiation energy emitted from a combustion flame to determine and detect the presence or absence of the combustion flame,
A plurality of light receiving units for outputting light reception signals obtained by observing different predetermined wavelength bands emitted from the combustion flame;
A determination unit that uses the correlation between light reception signals of a predetermined period, which are observed and output at substantially the same time by each light reception unit, as one element of the presence or absence of a combustion flame;
Equipped with
The determination unit divides the correlation between the respective light reception signals into a plurality of time intervals for each light reception signal for a predetermined period, and integrates the signal of the other divided intervals with respect to the ratio of the signal integration value of the divided intervals serving as a reference. It is characterized in that the determination is made based on the ratio of values.

  The determination unit divides the correlation of the respective light reception signals into a plurality of time intervals for each light reception signal for a predetermined period, and integrates the signal of the other divided intervals with respect to the ratio of the signal integration value of the first divided intervals. Determine based on the ratio of values.

  The determination unit divides the correlations of the respective light reception signals into a plurality of time intervals at regular intervals, dividing each light reception signal for a predetermined period, and the other divided intervals to the ratio of the signal integral value of the first divided intervals Based on the ratio of the signal integral value of

  When all the ratios of the signal integrals of the other plurality of divided sections to the ratio of the signal integrals of the first divided sections to the ratio of the signal integrals of the first divided sections are within the predetermined flame determination threshold range, Do.

  The determination unit sets a predetermined upper limit value and a lower limit value as the flame determination threshold range with respect to the ratio of the signal integral value of the first divided sections.

(Basic effect)
The present invention is a flame detection device that observes radiation energy emitted from a combustion flame to determine the presence or absence of the combustion flame and detects light reception signals of different predetermined wavelength bands emitted from the combustion flame. A plurality of light receiving units to be output, and a determination unit that makes mutual correlation of light reception signals of a predetermined period observed and output at substantially the same time by each light reception unit be one element of the presence or absence of combustion flame Therefore, if the correlation is high, the temporal change in the radiation energy emitted from the combustion flame is substantially the same, and the light input to the light receiving unit is considered to be possibly due to the radiation from the flame. By setting it as one element of the flame presence determination, the presence or absence of the combustion flame can be more reliably determined and detected.

(Effect by light receiving unit)
The light receiving unit 1 also includes an optical wavelength filter for selectively transmitting light of a predetermined wavelength band including the CO2 resonance radiation band emitted from the combustion flame, and a light receiving element for receiving light transmitted through the optical wavelength filter. The light receiving sensor has one or more light receiving elements for outputting a light receiving signal based on the converted electric signal, and the other light receiving unit emits light of a predetermined wavelength band not included in the CO2 resonance radiation band emitted from the combustion flame A light receiving sensor having an optical wavelength filter for selectively transmitting light, and one or more light receiving elements for outputting a light receiving signal based on an electric signal obtained by receiving light transmitted through the optical wavelength filter with a light receiving element and photoelectrically converting it; Each of the light receiving units further includes a frequency selection unit for selectively extracting a signal component of a predetermined frequency band from the electric signal from the light reception sensor, and an output from the frequency selection unit. And each of the photoelectric units emits radiation energy of a band wavelength having a central wavelength of about 4.5 μm and radiation of a band wavelength different from that, which are emitted from the combustion flame. It is possible to perform photoelectric conversion of energy with certainty and output a light reception signal.

  Further, by providing a plurality of light receiving elements in the light receiving sensor, for example, it is possible to suppress and equalize variations due to differences in light receiving characteristics of a plurality of light receiving elements by adding light receiving outputs photoelectrically converted by a plurality of light receiving elements. I assume.

(2 light receiving units)
In addition, by providing at least two light receiving units, the determination unit mutually correlates the light reception signals of a predetermined period in different wavelength bands that are observed and output at substantially the same time by the two light receiving units. It is possible to make it one other element of the flame judgment.

(Effect of flame judgment by correlation of signal amplitude)
In addition, the determination unit divides the correlation of each light reception signal into a plurality of time sections by dividing each light reception signal for a predetermined period into a plurality of time sections, and all the ratios of signal integral values of the divided sections are predetermined flame determination threshold ranges If it is inside, the light input to the light receiving unit is considered to have the possibility of radiation from the flame, and it is possible to more reliably determine and detect the presence of the combustion flame by using it as one element of the flame presence determination. Do.

(Effect of flame judgment details by correlation of signal amplitude)
In addition, when the determination unit divides each of the light reception signals E1 to Em for a predetermined period output from the plurality of light reception units into time intervals of an integer n greater than or equal to 1, light reception of 1 is performed for each of the n divided intervals. Ratios R1 to Rn of signal integral values .SIGMA.E11 to .SIGMA.E1n of the signal E1 and integral values .SIGMA.Em1 to .SIGMA.Emn of the other light reception signal Em corresponding to the same time interval,
R1 to Rn = ΣE11 // Em1 to EE1n / ΣEmn
When all of the ratios R2 to Rn of the signal integrals of the remaining time interval to the ratio R1 of the signal integrals of the first time interval are within the predetermined flame judgment threshold range, the signal is input to the light receiving unit Since the light is considered to be the possibility of radiation from the flame and one of the elements of the judgment of the presence of flame, based on the correlation in which the amplitude changes of the two light reception signals E1 and E2 in the first time interval are substantially coincident, It is possible to compare the deviation of correlation in the remaining time intervals, and when the deviation of correlation is small, it is possible to judge and detect the presence of a combustion flame.

(Effect of flame judgment by correlation of frequency distribution)
Further, the determination unit determines the relative level distribution of the frequency within a predetermined range obtained by dividing each light reception signal correlation into a plurality of time sections by dividing each light reception signal for a predetermined period, and the frequency relative level distribution of each divided section If all the ratios of the integral values of the light are within the predetermined flame judgment threshold range, the light input to the light receiving unit is considered to be a possibility due to the radiation from the flame, and is regarded as one element of the flame judgment. It is possible to more reliably determine and detect the presence of

Block diagram showing an embodiment of the flame detection device Explanatory drawing which showed schematic structure of the light reception unit applied to the flame detection apparatus of FIG. A circuit diagram showing an equivalent circuit of the light receiving sensor of FIG. 2 Characteristic chart showing radiation spectrum of combustion flame Characteristic diagram showing the transmittance at each wavelength of the optical wavelength filter and the light transmitting window applied to the embodiment of FIG. 1 A signal waveform diagram showing a light reception signal output from each of the light receiving units of FIG. 1 when radiation energy radiated from a combustion flame is observed The flowchart which showed the procedure of the processing operation of the judgment part of FIG. 1 which judges the correlation of the amplitude change of two light reception signals Explanatory drawing which showed the frequency distribution of the light reception signal output from each of the light reception unit of FIG. 1 when radiation energy radiated from a combustion flame was observed The flowchart which showed the procedure of the processing operation of the judgment part of FIG. 1 which judges the correlation of the frequency distribution of two light reception signals A block diagram showing an embodiment of a flame detection device for adding light reception signals from a plurality of light reception elements provided in a light reception unit A circuit diagram showing an equivalent circuit of the light receiving sensor of FIG. Block diagram showing another embodiment of a flame detection device installed in a tunnel to monitor a fire The characteristic chart which showed the transmissivity in each wavelength of the optical wavelength filter and translucent window applied to the embodiment of Drawing 12 Characteristic diagram showing the radiation spectrum of the combustion flame and other typical radiators

[Outline of flame detection device]
FIG. 1 is a block diagram showing an embodiment of a flame detection apparatus according to the present invention by a functional configuration, FIG. 2 is an explanatory view showing a schematic configuration of a light receiving unit applied to the flame detection apparatus of FIG. FIG. 4 is a characteristic diagram showing a radiation spectrum of a combustion flame, and FIG. 5 is each wavelength of an optical wavelength filter and a translucent window applied to the embodiment of FIG. It is the characteristic view which showed the transmissivity in.

  As shown in FIG. 1, the flame detection device 10 of the present embodiment observes the radiation energy having the spectrum characteristic 50 shown in FIG. 4 emitted from the combustion flame existing in the monitoring area, A light receiving unit 12a for observing radiation energy in a narrow wavelength band having a central wavelength of approximately 4.5 μm emitted from a flame by CO2 resonance and outputting a light reception signal E1 by photoelectric conversion, and emission from CO2 resonance from a combustion flame The light receiving unit 12b which observes radiation energy of a narrow band wavelength band having a central wavelength of, for example, about 2.3 μm which does not include about 4.5 μm, and the light receiving unit 12a and 12b Judgment part 15 which makes mutual correlation of light reception signals E1 and E2 for a predetermined period which were observed and outputted approximately at the same time as one element of the judgment of the presence or absence of a combustion flame Equipped with a.

(Light receiving unit configuration)
The light receiving unit 12a converts light energy having a narrow wavelength band having a central wavelength of approximately 4.5 μm, which is emitted from the combustion flame by CO 2 resonance, into an electric signal and outputs the electric signal, and the light receiving sensor 16a From the light reception signal to be output, a prefilter 24a for passing only a signal component of a predetermined frequency band, a preamplifier 26a for amplifying the signal component passed through the prefilter 24a at the first stage, and an output from the preamplifier 26a will be described later. It comprises with the main amplifier 28a which amplifies to the signal level suitable for a flame judgment process, and outputs the light reception signal E1.

  Further, the light receiving unit 12b converts light energy having a narrow wavelength band having a central wavelength of approximately 2.3 μm, which is emitted from the combustion flame, into an electric signal and outputs the electric signal, and the light receiving sensor 16b From the light reception signal to be output, a prefilter 24b passing only a signal component of a predetermined frequency band, a preamplifier 26b amplifying a signal component passed through the prefilter 24b at the first stage, and an output from the preamplifier 26b will be described later. The main amplifier 28b amplifies the signal level suitable for the flame judgment processing and outputs the light reception signal E2.

  Here, the light receiving sensors 16a and 16b are provided with a light transmitting window 18 shared by using an infrared light transmitting member such as sapphire glass, optical wavelength filters 20a and 20a, and pyroelectric light receiving elements 22a and 22b. ing.

  The light reception signal E1 and the light reception signal E2 output from the light reception units 12a and 12b via the amplifiers 28a and 28b are converted into digital light reception signals and read by A / D conversion ports 30a and 30b provided in the determination unit 15, A flame judgment to be described later is executed. Each configuration will be specifically described below.

(Light receiving sensors 16a, 16b)
The light receiving sensor 16a provided in the light receiving unit 12a includes an optical wavelength filter 20a, a light receiving element 22a, and a translucent window 18 shared. As shown in FIG. 5, the optical wavelength filter 20a has a transmission characteristic 54 that transmits only light of a predetermined band including a wavelength band of about 4.5 μm emitted by CO 2 resonance generated at the time of flame combustion with high transmittance. An optical band pass filter, for example, that selectively transmits light of a predetermined band that includes 4.5 μm and does not include other wavelength bands described later. The light receiving element 22a has a photoelectric conversion function of a pyroelectric material and an FET, receives light transmitted through the optical wavelength filter 20a, converts the light into an electric signal, and outputs the electric signal.

  Specifically, as shown in FIG. 2, the light receiving sensor 16a includes a plurality of pyroelectric members 25a disposed on the front surface of the substrate 36a and a light receiving element 22a including the FET 27a disposed on the back surface of the substrate 36a; Substrate mounting portion 40a for supporting 36a on base portion 38a, Base portion 38a provided with terminal 42a extending from the back side on the substrate mounting portion 40a side, Narrow band pass filter in front of light receiving element 22a And a cover member 44a provided with the optical wavelength filter 20a.

  Further, as shown in FIG. 3, the equivalent circuit of the light receiving element 22a is connected from the gate of the FET 27a to the gate terminal G via, for example, a parallel circuit of the pyroelectric 25 and the high resistance 29. They are connected to the drain terminal D and the source terminal S, respectively.

  On the other hand, the light receiving sensor 16b is composed of an optical wavelength filter 20b, a light receiving element 22b, and a translucent window 18 which is shared. As shown in FIG. 5, the optical wavelength filter 20b has an optical band pass having a transmission characteristic 58 that transmits only light of a predetermined band including a wavelength band of about 2.3 μm emitted from a combustion flame with high transmittance. The filter selectively transmits light of a predetermined band which includes, for example, 2.3 μm and does not include the wavelength band of the approximately 4.5 μm wavelength band emitted by the CO 2 resonance. The light receiving element 22b has a photoelectric conversion function of a pyroelectric material and an FET, receives light transmitted through the optical wavelength filter 20b, converts the light into an electric signal, and outputs the electric signal.

  Specifically, as shown in FIG. 2, the light receiving sensor 16b includes a plurality of pyroelectric members 25b disposed on the front surface of the substrate 36b and a light receiving element 22b including the FET 27b disposed on the back surface of the substrate 36b; Substrate mounting portion 40b for supporting 36b on base portion 38b, Base portion 38b provided with terminal 42b extending from the back side on the substrate mounting portion 40b side, and a narrow band pass filter in front of light receiving element 22b And a cover member 44b provided with the optical wavelength filter 20b. The equivalent circuit of the light receiving element 22b is the same as that of the light receiving element 22a shown in FIG.

  The light receiving sensors 16 a and 16 b are arranged in a predetermined arrangement close to each other on a common attachment member 48 provided in the main body cover 46.

  Here, the optical wavelength filters 20a and 20b can be formed on a substrate of, for example, silicon, germanium, sapphire or the like by a known method.

(Transparent window 18)
The translucent window 18 is disposed on a predetermined opening provided on the front surface side of the light receiving sensors 16a and 16b on the upper surface side corresponding to the monitoring area side of the main body cover 46 in which the light receiving sensors 16a and 16b are stored. For example, it is formed of an infrared light transmitting member such as sapphire glass. Therefore, in the light receiving elements 22a and 22b, detection fields having substantially the same spread angle are set by restricting the light reception limit fields of view of the light receiving elements 22a and 22b at the edge of the light transmitting window 18.

  Here, as shown in FIG. 5, the sapphire wave constituting the light-transmissive window 48 has a short wave path characteristic 52 which transmits radiation of a wavelength band of about 7.0 μm or less favorably, in other words, about 7 It functions as a filter member having a long wave cut characteristic that blocks radiation of longer wavelength than around 0 μm. Further, in the present embodiment, the translucent window 18 is described as being included in the light receiving sensors 16a and 16b as a common member.

(Light receiving sensor 16a, 16 this wavelength transmission characteristic)
FIG. 5 is a characteristic diagram showing the transmittance at each wavelength of the optical wavelength filter and the light transmitting window applied to the embodiment of FIG.

  A short wave path characteristic 52 in which radiation of around 7.0 μm or less is favorably transmitted by sapphire glass which is the translucent window 18 of FIG. 1 and an optical wavelength filter 20 a, center wavelength of around 4.5 μm The radiation energy of a wavelength band of approximately 4.5 μm is transmitted at a high transmittance by the combination of the band pass filter to be used with the transmittance characteristic 54 which transmits the radiation energy of the wavelength band near the central wavelength with high transmittance. The transmission characteristic 56 constitutes a narrow band pass filter.

  In addition, short wave path characteristics 52 in which radiation of around 7.0 μm or less is favorably transmitted by sapphire glass which is the light-transmissive window 18, and around 2.3 μm constituting the optical wavelength filter 20a have a central wavelength Transmission of radiation energy of approximately 2.3 μm wavelength band with high transmittance by combination of the band pass filter with the transmittance characteristic 58 which transmits the radiation energy of the wavelength band near the center wavelength with high transmittance A narrow band pass filter with characteristic 60 is constructed.

(Pre-filters 24a, 24b)
The prefilters 24a and 24b function as frequency selectors, and from the light reception signal output from each of the light receiving elements 22a and 22b of the light reception sensors 16a and 16b, only the signal component of the specific frequency band used for the flame determination process For example, it is an active filter that passes through and outputs a light reception signal including a signal component of a specific frequency band to the preamplifiers 26a and 26b in the subsequent stage.

(Preamplifiers 26a, 26b and main amplifiers 28a, 28b)
The preamplifiers 26a and 26b amplify the light reception signals input through the prefilters 24a and 24b at a first stage by a predetermined amplification factor, and the main amplifiers 28a and 28b describe light reception signals from the preamplifiers 26a and 26b, which will be described later. It amplifies to the signal level suitable for a flame judgment process, and outputs as light reception signal E1, E2.

(A / D conversion port 30a, 30b)
The A / D conversion ports 30a and 30b are A / D converters provided as input ports of the determination unit 15, and convert the light reception signals (analog light reception signals) E1 and E2 into digital signals suitable for digital processing of the determination unit 15. And read.

(Judgment unit 15)
The determination unit 15 is configured by hardware such as a microprocessor unit (MPU) provided with a CPU, a memory, various input / output ports including the A / D conversion ports 30a and 30b, and the like. Further, the determination unit 15 realizes the control function of the flame determination by the execution of the program by the CPU.

  The determination unit 15 performs control such that the correlation between the light reception signals E1 and E2 for a predetermined period, which are observed and output at substantially the same time by the light reception units 12a and 12b, is one element of the presence / absence judgment of the combustion flame.

  That is, the determination unit 15 obtains the correlation between the light reception signals E1 and E2 for the predetermined period, which are observed and output at substantially the same time by the light reception units 12a and 12b, and the mutual correlation satisfies the predetermined standard. The light input to the light receiving units 12a and 12b is considered to have a possibility due to the radiation from the flame, and control is performed to determine and detect the presence or absence of the flame as one element of the presence of the flame.

(The flame judgment by the mutual correlation of the light reception signals E1 and E2)
The details of the flame judgment performed by obtaining the correlation between the light reception signals E1 and E2 for the predetermined period observed and output by the light reception units 12a and 12b at substantially the same time by the judgment unit 15 will be described as follows.

  FIG. 6 shows a light reception signal E1 of radiation energy in a narrow wavelength band having a central wavelength of 4.5 μm output from the light reception unit 12a of FIG. 1 when radiation energy emitted from a combustion flame is observed, and a light reception unit 12b. The light reception signal E2 by radiation energy of a narrow band wavelength band having a central wavelength of 2.3 μm output from the light reception signal E1 has a waveform similar in level to the light reception signal E1.

  Further, the signal waveforms of the reception signals E1 and E2 shown in FIG. 6 are converted into digital light reception signals by sampling the respective light reception signals E1 and E2 at, for example, 64 Hz by the A / D conversion ports 30a and 30b provided in the determination unit 15. A state where light reception signals E1 and E2 of a predetermined period T = 2 seconds are temporarily stored in the buffer memory as a target of one correlation calculation is shown as an analog waveform.

  The determination unit 15 divides the predetermined period T = 2 seconds into, for example, four time intervals T1, T2, T3, and T4 of 500 milliseconds, plus and minus from the reference potential which is the middle point of the light reception signals E1 and E2. The integrals .SIGMA.E11, .SIGMA.E12, .SIGMA.E13, .SIGMA.E14 of the time periods T1 to T4 are determined for the light reception signal E1 as an integral value which is an absolute value of the difference from the amplitude on the side. Integral values EE21, EE22, EE23, ΣE24 of ~ T4 are determined.

Next, the determination unit 15 calculates the ratio R1, R2 of the signal integral values ΣE11, EE12, EE13, EE14 of the light reception signal E1 and the integral values EE21ΣE22, EE23, ΣE24 of the light reception signal E2 for each of the same time intervals T1 to T4. , R3, R4,
R1 = .SIGMA.E11 / .SIGMA.E21 Formula (1)
R2 = .SIGMA.E12 / .SIGMA.E22 Formula (2)
R3 = ΣE13 / ΣE23 Formula (3)
R4 = ΣE14 / ΣE24 Formula (4)
As the correlation of the light reception signals E1 and E2 with each other.

  In order to determine the correlation between the light reception signals E1 and E2, the determination unit 15 sets a flame determination threshold range having the lower limit threshold TH1 and the upper limit threshold TH2 based on the ratio R1 of the integral values of the first time interval T1.

  The determination unit 15 sets the lower limit threshold TH1 and the upper limit threshold Th2 to, for example, ± 10% upper and lower thresholds TH1 and TH2 with respect to the ratio R1 of the first time interval T1, TH1 = 0.9 · R1 and TH2 = 1 Set the flame judgment threshold range as 1 · R1. Generally speaking, the lower limit threshold TH1 (= .alpha..R1) is set by multiplying the ratio R1 of the signal integral value of the first section T1 by a predetermined constant .alpha. This means that the upper limit threshold TH2 (= β · R1) is set by multiplying the constant β, and appropriate values can be set as the values of the coefficients α and β as necessary.

When the flame determination threshold range having the lower limit threshold TH1 and the upper limit threshold TH2 is set as described above, the determination unit 15 determines whether the following condition is established.
0.9R1 ≦ R2 ≦ 1.1R1 Formula (5)
0.9R1 ≦ R3 ≦ 1.1R1 Formula (6)
0.9R1 ≦ R4 ≦ 1.1R1 Formula (7)
If the determination unit 15 determines that all the conditions of the equations (5) to (7) are satisfied, that is, for the ratio R1 of the signal integral value of the first time interval T1, the remaining time intervals T2 to T4 are obtained. When the ratio R2 to R4 of all the signal integral values is within the predetermined flame determination threshold range, the amplitude waveforms of the light reception signals E1 and E2 are substantially similar, and both of the light reception units 12a and 12b respectively receive the radiation energy from the combustion flame. In this case, since it can be estimated that observation is performed in a different wavelength band, radiation in a narrow wavelength band with a central wavelength of 4.5 μm emitted from a combustion flame by CO 2 resonance, for example Allowing the flame judgment based on the light reception signal E1 having a sufficient amplitude level by energy.

  As the flame judgment based on the light reception signal E1 in this case, the determination unit 15 obtains a frequency distribution from the light reception signal E1 by an arithmetic method such as fast Fourier transform (FFT), for example, and a frequency distribution of 8 Hz or less including fluctuation frequency unique to the flame. In the case where the integrated value is equal to or greater than a predetermined threshold value, it is determined that there is a possibility of a flame, and a process of determining the flame in consideration of other elements of the flame determination is performed.

  In addition, when the determination unit 15 determines that the condition of at least one of the expressions (5) to (7) is not satisfied, that is, the remaining time interval with respect to the ratio R1 of the signal integral value of the first time interval T1. When at least one of the ratios R2 to R4 of the signal integral values of T2 to T4 deviates from the predetermined flame determination threshold range, it can be estimated as the received light signals E1 and E2 by radiation energy from other than the combustion flame, so 1 with flame It does not use an element, and suppresses the flame judgment based on the light reception signal E1.

(Generalized judgment of mutual correlation)
Here, when the number i of sections into which the predetermined period T is divided is generalized as i = 1 to n and the light reception signal is generalized as E1 to Em, the determination unit 15 divides the predetermined period T into sections T1 to Tn. The integrated values 積分 E11 to EE1n of the time intervals T1 to Tn are determined for the light reception signal E1 as a value (amplitude integral value) obtained by integrating the absolute value of the difference from the reference potential which is the middle point of the light reception signals E1 and Em. Further, for the light reception signal Em, integrated values EEm1 to mnEmn of each time interval T1 to Tn are determined, and further, the ratio R1 to Rn of the both is
R1 to Rn = ΣE11 // Em1 to EE1n / ΣEmn
As the correlation of the light reception signals E1 and Em with each other.

Next, when the lower limit threshold TH1 and the upper limit threshold TH2 are set in the same manner as described above, the determination unit 15 determines whether the condition for becoming the next flame determination threshold range is established.
0.9R1 ≦ R2 ≦ 1.1R1 to 0.9R1 ≦ Rn ≦ 1.1R1
When it is determined that the conditions for being within the flame determination threshold range are determined, the amplitude waveforms of the light reception signals E1 and E2 are substantially similar, and it can be estimated that the light reception units 12a and 12b are observing the radiation energy from the combustion flame. As one element of the judgment of the presence of flame, the flame judgment based on the light reception signal E1 is permitted.

  On the other hand, when the determination unit 15 determines that at least one condition out of the flame determination threshold range is not met, it can be estimated as the light reception signals E1 and E2 by radiation energy from other than the combustion flame, so 1 of flame presence It does not use an element, and suppresses the flame judgment based on the light reception signal E1.

(Process operation of flame judgment)
FIG. 7 is a flow chart showing the procedure of the processing operation of the determination unit of FIG. 1 for determining the correlation of the amplitude change of two light reception signals.

(Step S1)
First, the determination unit 15 takes in the light reception signals E1 and E2 output from the light reception units 12a and 12b through the A / D conversion ports 30a and 30b in a predetermined sampling cycle for a predetermined time T, for example, T = 2 seconds. Temporarily store in buffer memory.

(Step S2)
Next, the determination unit 15 divides the light reception signals E1 and E2 of the predetermined period T fetched in step S1 into four time sections T1, T2, T3 and T4, and the signal amplitude of the light reception signal E1 of each divided section T1 to T4. The integrated values .SIGMA.E11, .SIGMA.E12, .SIGMA.E13, and .SIGMA.E14 of the light reception signal and the integrated values .SIGMA.E21, .SIGMA.E22, .SIGMA.E23 and .SIGMA.E24 of the light reception signal E2 are calculated.

  It is desirable that the processing after step S2 be executed when the signal level of the light reception signal E1 taken in by the determination unit 15 from the A / D conversion port 30a becomes equal to or higher than a predetermined threshold.

(Step S3)
Next, the determination unit 15 calculates the ratios R1, R2, R3, and R4 of the integral values of the divided sections T1 to T4 of the light reception signals E1 and E2 calculated in step S2 according to the equations (1) to (4).

(Step S4)
Next, based on the ratio R1 of the integral values of the first time interval T1, the determination unit 15 determines the flame with the lower threshold TH1 and the upper threshold TH2 set to, for example, TH1 = 0.9 · R1 and TH2 = 1.1 · R1. Set the threshold range.

(Step S5)
Next, the determination unit 15 determines that the ratios R2, R3, and R4 of the integral values of the remaining time intervals T2 to T4 following the first time interval T1 of the light reception signals E1 and E2 calculated in step S3 have the above formulas (5) to (5) 7) It is determined whether or not it is within the flame determination threshold range having the lower limit threshold TH1 and the upper limit threshold TH2.

(Steps S6 and S7)
Next, the determination unit 15 determines that all the ratios of the integral values of the time interval T2 to T4 are the flame determination threshold range when all the conditions of the equations (5) to (7) are satisfied in step S6. If it is determined that it is within the range, it is assumed that the amplitude waveforms of the light reception signals E1 and E2 are substantially similar and it is assumed that it is a light reception signal by radiation energy from the combustion flame, and it is judged as one element of flame judgment. To allow the flame judgment based on the light reception signal E1.

(Steps S6 and S8)
On the other hand, when the determination unit 15 determines that the condition of at least one of the expressions (5) to (7) is not satisfied in step S6, that is, TH1 = 0.9 · R1 and TH2 = 1.1 · R1. If it is determined that the light reception signals E1 and E2 from the light reception units 12a and 12b are not due to the radiation energy from the combustion flame, the process proceeds to step S8, and the light reception signal is determined. Suppress the flame judgment based on E1.

[Determination of the frequency distribution of the light reception signals E1 and E2 by mutual correlation]
(Outline of judgment unit 15)
As another embodiment of the determination unit 15 shown in FIG. 1, the flame determination can be performed by obtaining the mutual correlation from the frequency distribution of the light reception signals E1 and E2.

  In this case, the determination unit 15 divides the correlation between the light reception signals E1 and E2 output from the light reception units 12a and 12b into a plurality of time sections for each light reception signal for a predetermined period, and receives light in each divided section. The relative level distribution (frequency distribution) of the frequency within a predetermined range is determined from the signal, and when all the ratios of the integrals of the relative level distribution of the frequencies among the divided sections are within the predetermined flame determination threshold range, the light receiving units 12a and 12b. There is a possibility that the light input to the light is emitted from the flame, and control is performed to judge and detect the presence or absence of the flame as one element of the judgment on the presence of flame.

(Fire judgment based on cross-correlation of frequency distribution in judgment unit)
FIG. 8 is an explanatory view showing the frequency distribution of the light reception signals E1 and E2 outputted from each of the light reception units 12a and 12b of FIG. 1 when the radiation energy radiated from the combustion flame is observed.

  As shown in FIG. 8, when the radiation energy emitted from the combustion flame is observed on the frequency axis, a frequency characteristic showing a high output level on the lower frequency side than approximately 8 Hz is obtained. Exists in the frequency band up to 8 Hz, and the high frequency side up to 8 Hz, for example, up to 16 Hz shows a low level. Therefore, the correlation between the frequency distributions of the light reception signals E1 and E2 may be determined by, for example, the correlation of the frequency distribution on the low frequency side in the range up to 8 Hz.

  First, the determination unit 15 A / D converts the light reception signals E1 and E2 of the predetermined period T = 2 seconds output from the light reception units 12a and 12b and stores them in the buffer memory, for example, four time intervals of 500 milliseconds. The light reception signals E1 and E2 of each of the time intervals T1 to T4 are respectively subjected to fast Fourier transform (FFT) to obtain relative level distribution of frequency in each time interval.

  Subsequently, the determination unit 15 obtains integral values Σf11, ff12, ff13, Σf14 of the relative level distribution of the frequencies of the sections T1 to T4 of the light reception signal E1, and the light reception signal E2 is also obtained for the sections T1 to T4. The integrals Σ f 21, f f 22, f f 23 and Σ f 24 of the relative level distribution of frequency are determined.

Next, the determination unit 15 calculates integral values Σf11, ff12, ff13, Σf14 of the frequency distribution of the light reception signal E1 and integral values ff21Σf22, ff23, ff24 of the frequency distribution of the light reception signal E2 for each of the same time interval T1 to T4. Ratio Rf1, Rf2, Rf3, Rf4,
Rf1 = Σf11 / Σf21 Formula (8)
Rf2 = Σf12 / Σf22 Formula (9)
Rf3 = Σf13 / Σf23 Formula (10)
Rf4 = Σf14 / Σf24 Formula (11)
As the correlation between the frequency distributions of the light reception signals E1 and E2.

  In order to determine the correlation between the relative level distributions of the frequencies of the light reception signals E1 and E2, the determination unit 15 determines the flame having the lower threshold TH1 and the upper threshold TH2 based on the ratio Rf1 of the integral values of the first time interval T1. Set the threshold range.

  The determination unit 15 sets the lower limit threshold THf1 and the upper limit threshold THf2 to, for example, a flame determination threshold range of ± 10% with respect to the ratio Rf1 of the first time interval T1, THf1 = 0.9 · Rf1, THf2 = 1.1 · Rf1 Set to

When the flame determination threshold range having the lower limit threshold TH1 and the upper limit threshold TH2 is set as described above, the determination unit 15 determines whether the following condition is established.
0.9 R f 1 ≦ R f 2 ≦ 1.1 R f 1 Formula (12)
0.9 R f 1 ≦ R f 3 ≦ 1.1 R f 1 Formula (13)
0.9 R f 1 ≦ R f 4 ≦ 1.1 R f 1 Formula (14)
If the determination unit 15 determines that all the conditions of the equations (12) to (14) are satisfied, that is, the remaining time with respect to the ratio Rf1 of the integral value of the relative level distribution of the frequency in the first time interval T1. When the ratios Rf2 to Rf4 of integral values of relative level distributions of all frequencies in the sections T2 to T4 are within a predetermined flame determination threshold range, the frequency distributions of the light reception signals E1 and E2 are substantially similar, and the light reception units 12a and 12b It can be estimated that both light reception signals E1 and E2 by radiation energy from the combustion flame are output, which is one element of the judgment of the presence of flame, for example, allowing the flame judgment based on the light reception signal E1.

  In addition, when the determination unit 15 determines that the condition of at least one of the expressions (12) to (14) is not satisfied, that is, the ratio Rf1 of the integral value of the frequency distribution of the first time interval T1 remains. When at least one of the ratios Rf2 to Rf4 of the integrals of the relative level distribution of the frequency in the time interval T2 to T4 deviates from the predetermined flame determination threshold range, the light receiving units 12a and 12b receive light by radiation energy from other than the combustion flame. It can be estimated that the signals E1 and E2 are output, and the flame judgment based on the light reception signal E1 is suppressed without using one element with flame.

(Process operation of flame judgment based on the correlation of frequency distribution)
FIG. 9 is a flowchart showing the procedure of the processing operation of the determination unit of FIG. 1 for determining the correlation of the frequency distribution of two light reception signals.

(Step S11)
First, the determination unit 15 takes in the light reception signals E1 and E2 output from the light reception units 12a and 12b through the A / D conversion ports 30a and 30b in a predetermined sampling cycle for a predetermined time T, for example, T = 2 seconds. Temporarily store in buffer memory.

(Step S12)
Next, the determination unit 15 divides the light reception signals E1 and E2 of the predetermined period T taken in step S11 into four sections T1, T2, T3 and T4, and fast Fourier transforms the light reception signal E1 in each of the sections T1 to T4. The integrated values ff21, ff22, ff23, ff24 of relative levels in the frequency range of 8 Hz or less with respect to the integrated values ff11, ff12, ff13, Σf14 of the relative level distribution in the frequency range of 8 Hz or less and the light reception signal E2. Calculate

  It is preferable that the process after step S12 is executed when the signal level of the light reception signal E1 taken by the determination unit 15 from the A / D conversion port 30a becomes equal to or higher than a predetermined threshold.

(Step S13)
Next, the determination unit 15 calculates the ratios Rf1, Rf2, Rf3, and Rf4 of the integrals of the relative level distributions of the frequencies of the sections T1 to T4 of the light reception signals E1 and E2 calculated in step S12 to the above formulas (8) to (11). Calculated by).

(Step S14)
Next, the determination unit 15 determines the lower limit threshold THf1 and the upper limit threshold THf2, for example, THf1 = 0.9 · Rf1, THf2 = 1.1 ··· based on the ratio Rf1 of the integral value of the relative level distribution of the frequency in the first section T1. Set to Rf1.

(Step S15)
Next, the determination unit 15 sets the ratios Rf2, Rf3, and Rf4 of the integrals of the relative level distributions of the frequencies of the remaining sections T2 to T4 following the first section T1 of the light reception signals E1 and E2 calculated in step S13 to the above equation (12 ) Through (14), it is determined whether or not it falls within the flame determination threshold range having the lower limit threshold TH1 and the upper limit threshold TH2.

(Steps S16 and S17)
Next, if it is determined in step S16 that all the conditions of the equations (12) to (14) are satisfied in step S16, the determination unit 15 determines that the flame determination threshold range is satisfied, the frequency distribution of the light reception signals E1 and E2 The light receiving units 12a and 12b are roughly similar, and estimate that light reception signals E1 and E2 by radiation energy from the combustion flame are output, determine it as one element of flame judgment, and proceed to step S17, based on the light reception signal E1. Allow fire judgment.

(Steps S16 and S18)
On the other hand, when the determination unit 15 determines that the condition of at least one of the expressions (12) to (14) is not satisfied in step S16, that is, THf1 = 0.9 · Rf1, THf2 = 1.1 · Rf1. If the light receiving units 12a and 12b determine that they are outside the flame determination threshold range, the light receiving units 12a and 12b estimate that light receiving signals E1 and E2 of radiation energy other than the combustion flame are output, and the process proceeds to step S18. Inhibit the E1 fire judgment.

[Embodiment of a light receiving unit provided with a plurality of light receiving elements]
FIG. 10 is a block diagram showing a functional configuration according to another embodiment of the flame detection device for adding light reception signals from a plurality of light reception elements provided in the light reception unit.

  As shown in FIG. 10, the light receiving sensors 16a and 16b provided in the light receiving units 12a and 12b of the present embodiment each include four light receiving elements 22a and 22b. In the light receiving elements 22a and 22b, for example, four pyroelectric members 25a and 25b are disposed on the front side of the substrates 36a and 36b disposed in the inside of the cover members 44a and 44b shown in FIG. As shown in the equivalent circuit, four light receiving elements 22a composed of a pyroelectric 25a, high resistance 29 and FET 27a are provided, and the drain and gate of each FET 27a are commonly connected to the drain terminal D and gate terminal G, respectively. The sources of R are individually connected to the source terminals S1 to S4.

  Referring again to FIG. 10, after the outputs of the four light receiving elements 22a and 22b pass through the four prefilters 24a and 24b, four light receiving signals as current outputs are added (current addition) to obtain the preamplifier 26a, It is input to 26b.

  Here, the light reception output from the four light reception elements 22a is added to the preamplifier 26a after adding the light reception current after passing through the four pre-filters 24a, so the random noise component is increased by the current addition. There is almost no noise, and it is the current addition of signal components obtained by photoelectric conversion of radiation energy in a narrow wavelength band centered on about 4.5 μm emitted from the combustion flame by CO 2 resonance, without lowering the S / N ratio. A light reception signal can be generated as a light reception current corresponding to approximately four times the light reception output of one light reception element.

  This point is the same for the outputs from the four light receiving elements 22b, and after passing through the four prefilters 24b, the light reception current is added and input to the preamplifier 26b. There is almost no increase due to current addition, and the signal addition of the photoelectric conversion of radiation energy in a narrow wavelength band centered on about 2.3 μm, emitted from the combustion flame, results in the reduction of the S / N ratio. Instead, it is possible to generate a light reception signal as a light reception current corresponding to approximately four times the light reception output of one light reception element.

  As described above, even if the radiation energy emitted from the combustion flame to be received is weak, the optical units 12a and 12b add the light reception signals photoelectrically converted by the four light reception elements 22a and 22b, thereby the light reception unit 12a, 12 can output the light reception signals E1 and E2 having a sufficient level without lowering the S / N ratio, and the flame detection area can be greatly expanded.

  The configurations and functions from the preamplifiers 26a and 26b to the determination unit 15 are the same as those in the embodiment of FIG.

  Further, the number of light receiving elements 22a and 22b provided in the light receiving sensors 16a and 16b can be appropriately determined as needed. Further, the number of light receiving elements 22a and 22b provided in the light receiving sensors 16a and 16b may be the same or different.

[Flame detection device for tunnel]
Next, an embodiment in which the configuration of the flame detection device shown in the embodiment of FIG. 1 is applied to a flame detection device for tunnel will be described.

  FIG. 12 is a block diagram illustrating another embodiment of a flame detection device installed in a tunnel to monitor flames.

(Light receiving unit 12a, 12b)
As shown in FIG. 12, the light receiving units 12a and 12b are the same as the embodiment of FIG. 1, and the radiation energy of a narrow wavelength band having a central wavelength of about 4.5 μm emitted from the combustion flame by CO2 resonance. And a light reception signal E2 obtained by observing radiation energy in a narrow wavelength band having a central wavelength of approximately 2.3 μm, and each of the A / D conversion ports 30a and 30b provided in the determination unit 15 Converted to a digital light reception signal.

(Light receiving unit 12c)
The light receiving unit 12c includes a light receiving sensor 16c that converts radiation energy having a predetermined wavelength band different from that of the light receiving sensors 16a and 16b into an electric signal and outputs the electric signal. That is, the light receiving unit 12c outputs a light receiving signal E3 obtained by converting radiation energy in a wavelength band of approximately 5.0 μm to 7.0 μm into an electric signal.

  Further, the light receiving unit 12c is a light receiving signal output from the light receiving sensor 16c following the light receiving sensor 16c, a prefilter 24c that passes only a signal component of a predetermined frequency band, and a signal passing through the prefilter 24c. It comprises a preamplifier 26c for amplifying the components in the first stage, and a main amplifier 28c for amplifying the output from the preamplifier 26c. The light reception signal E3 output from the main amplifier 28c of the light reception unit 12c is converted into a digital light reception signal and read by the A / D conversion port 30c of the determination unit 15, and is used for the flame determination process.

(Configuration of the light receiving sensor 16c)
The light receiving sensor 16c receives the light transmitted through the optical wavelength filter 20c, which is a long pass filter configured of a cut-on filter that transmits radiation of a predetermined wavelength band approximately exceeding 5.0 μm well, and the optical wavelength filter 20c. Light receiving element 22c of the equivalent circuit of FIG. 3 which converts the light signal into an electric signal and outputs the same, and has a packaged structure with a structure similar to that shown in FIG. 2, and the light receiving sensor 16a of the optical unit 12a, 12b. , 16b on a common mounting member 48 provided in the main body cover 46, arranged in a predetermined arrangement close to each other.

(Transparent window 18)
The translucent window 18 is disposed at a predetermined opening provided on the front side which is the monitoring area side of the main body cover 46 in which the light receiving sensor 16c is housed together with the light receiving sensors 16a and 16b shown in FIG. The light receiving elements 22a, 22b and 22c of the light receiving sensors 16a, 16b and 16c are formed of infrared light transmitting members such as sapphire glass, and the light receiving limit fields of the light receiving elements 22a, 22b and 22c are restricted by the edge of the light transmitting window 18. Thus, detection areas having substantially the same spread angle are set.

(Wavelength transmission characteristics of the light receiving sensors 16a to 16c)
FIG. 13 is a characteristic diagram showing the transmittance at each wavelength of the optical wavelength filter and the light transmitting window applied to the embodiment of FIG.

  As shown in FIG. 13, the transmission characteristic 56 of the light receiving sensor 16a and the transmission characteristic 60 of the light receiving sensor 16b are the same as in FIG.

  On the other hand, the light receiving sensor 16c is a short wave path characteristic 52 in which radiation energy of about 7.0 μm or less is favorably transmitted by sapphire glass as the light transmitting window 18, and a long pass filter constituting the optical wavelength filter 20c. The radiation energy of the wavelength band of approximately 5.0 μm to 7.0 μm is high by the combination with the transmittance characteristic 62 having the cut-on filter characteristic of favorably transmitting the radiation energy of the predetermined wavelength band exceeding approximately 5.0 μm. A wide band pass filter is constructed with a transmission characteristic 64 that transmits at transmission.

(Fire judgment)
The determination unit 15 determines the light reception signal E1 and the light reception signal output from the light reception unit 12c when determining one element with flame from the correlation between the predetermined periods of the light reception signals E1 and E2 output from the light reception units 12a and 12b. E3 is taken in for a predetermined time via the A / D conversion ports 30a and 30c, and time integration processing of the signal amplitude is performed for each of the light reception signals E1 and E3 to calculate integral values EE1 and ΣE3. Here, the integrals ΣE1 and ΣE3 are distinguished as flame integral ΣE1 and non-flame integral ΣE3 for the sake of convenience.

  Next, when the flame integral value EE1 is equal to or less than a preset reference level, the determination unit 15 determines that the light reception output corresponding to the flame is not detected, while the flame integral value EE1 is the reference level If the relative ratio (.SIGMA.E1 / .SIGMA.E3) with the non-flame integral value .SIGMA.E3 is exceeded, and if the relative ratio (.SIGMA.E1 / .SIGMA.E3) exceeds the preset threshold value, it is judged as a flame. It is regarded as one element of the flame judgment, and when it is below the threshold value, the flame judgment is not performed, for example, assuming that there is a light reception output by a relatively low temperature radiation source other than flames such as human body and vehicles.

  As shown in the embodiment of FIG. 1, the determination unit 15 determines one element with flame from the correlation between the predetermined periods of the light reception signals E1 and E2 output from the light reception units 12a and 12b. , The frequency distribution of the frequency band of 8 Hz or less by fast Fourier transform of the light reception signal E1 captured for a predetermined time through the A / D conversion port 30a is taken as another element to perform complex flame judgment based on a plurality of elements You may

[Modification of the present invention]
The above embodiment determines the presence or absence of the combustion flame from the ratio of the signal integral value of each divided section obtained by dividing each light received signal for a predetermined period into a plurality of time sections by correlating the mutual correlation of each light received signal with each other. However, the present invention is not limited to the ratio of the signal integral value, and the presence or absence of the combustion flame may be determined from the mutual correlation by an appropriate value such as the correlation coefficient of each light reception signal.

  In the above embodiment, as a flame detection device for tunnel, correlation by observation of radiation energy in a wavelength band near 4.5 μm and a wavelength band near 2.3 μm, which is a CO 2 resonance radiation band of a combustion flame, The flame is determined by observing the radiation energy in the wavelength band around 5.0 μm, but the correlation by observation of the radiation energy in the wavelength band around 4.5 μm and the wavelength band in 2.3 μm and around 3.8 μm The radiation energy in the wavelength band may be observed to determine the presence or absence of a flame.

  In addition to the correlation by observation of radiation energy in the wavelength band around 4.5 μm and the wavelength band in 2.3 μm, radiation energy in the wavelength band around 3.8 μm and the wavelength band around 5.0 μm is observed to The presence or absence may be determined.

  In addition, the present invention includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited by the numerical values shown in the above-described embodiment.

10: flame detection devices 12a, 12b, 12c: light receiving units 15: judgment units 16a, 16b, 16c: light receiving sensors 18: light transmitting windows 20a, 20b, 20c: optical wavelength filters 22a, 22b, 22c: light receiving elements 24a, 24b, 24c: pre-filters 25a, 25b: pyroelectrics 26a, 26b, 26c: preamplifiers 27a, 27b: FET
28a, 28b, 28c: main amplifiers 30a, 30b, 30c: A / D conversion port

Claims (5)

A flame detection device that observes radiation energy emitted from a combustion flame to determine and detect the presence or absence of the combustion flame,
A plurality of light receiving units for outputting light reception signals obtained by observing different predetermined wavelength bands emitted from the combustion flame;
A determination unit that uses a correlation between light reception signals of a predetermined period, which are observed and output at substantially the same time by each of the light reception units, as one element of the presence / absence judgment of the combustion flame;
Equipped with
The determination unit divides the correlation between the light reception signals into a plurality of time intervals for each light reception signal of a predetermined period, and makes the other division intervals with respect to the ratio of the signal integral value of the division intervals serving as a reference. A flame detection apparatus characterized by making judgment based on a ratio of signal integral values.
The flame detection apparatus according to claim 1, wherein the determination unit divides the correlation between the light reception signals into a plurality of time sections for a predetermined period, and sets the first divided sections to each other. A flame detection apparatus characterized by making judgment based on a ratio of signal integral values of other divided sections to a ratio of signal integral values.
The flame detection apparatus according to claim 1, wherein the determination unit divides the correlation between the light reception signals into a plurality of time intervals at equal intervals for a predetermined period, and first divides the light reception signals. A flame detection apparatus characterized by making judgment based on a ratio of signal integral values of other divided sections to a ratio of signal integral values of sections.
The flame detection device according to claim 2 or 3, wherein the determination unit is configured to determine all of the ratios of signal integrals of the plurality of other divided sections to the ratio of the signal integral of the first divided sections to each other. A flame detection device characterized in that when it is within the flame judgment threshold range, it is regarded as one element of the flame judgment.
The flame detection apparatus according to claim 4, wherein the determination unit sets a predetermined upper limit value and a lower limit value as a ratio of the signal integral value of the first divided sections as the flame determination threshold range. A flame detector characterized in that.

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