Flame detection device

Abstract

Even if there are inconsistencies in the dirt on the translucent window, dirt correction is performed for each light-receiving element, enabling accurate fire detection. [Solution] In the flame detection device, flame detection units 12a and 12b receive infrared energy emitted from a combustion flame through a translucent window 18 with flame detection sensors 16a and 16b and output a flame reception signal, and non-flame detection unit 12c receives infrared energy emitted from sources other than a combustion flame through a translucent window with a non-flame detection sensor 16c and output a non-flame reception signal. The test control unit 38 irradiates test light from a test light source through the translucent window and determines the attenuation rate due to contamination of the translucent window for each detection unit. The fire determination unit 36 ​​corrects the flame reception signal and the non-flame reception signal based on this, detects the presence or absence of a combustion flame based on each corrected reception signal and determines whether there is a fire, and also causes the receiving device to output a contamination alarm or contamination warning alarm according to the attenuation rate of the flame reception signal or the difference in the flame reception signal.

Description

[[Technical Field]]

[0001] The present invention relates to a flame detection device that detects infrared radiation generated by CO₂ resonance during flaming combustion to determine the presence or absence of a flame. [[Background Art]]

[0002] Conventionally, among flame detection devices that detect infrared energy generated by flaming combustion to detect the presence or absence of a flame, flame detection devices and flame detection methods that detect infrared intensity in the resonant radiation wavelength band of CO₂ generated during flaming combustion to detect the presence or absence of a flame are well known.

[0003] Here, a two-wavelength flame detection device in the prior art will be briefly described. FIG. 16 is a conceptual diagram showing infrared spectra in the infrared wavelength region of a combustion flame and other typical radiators, where the horizontal axis represents infrared wavelength and the vertical axis represents relative intensity of infrared radiation.

[0004] As shown in FIG. 16, in the spectral characteristic 100 of a combustion flame, there is a peak of relative infrared intensity accompanying resonant radiation of CO₂ in a wavelength band around 4.5 µm, and as a characteristic wavelength existing in the vicinity of this peak wavelength, for example, there is a wavelength band with low relative infrared intensity around 5.0 µm on the long wavelength side. Hereinafter, unless otherwise specified, the term CO₂ resonant radiation band refers to the 4.5 µm band.

[0005] In a two-wavelength flame detection device, for example, infrared energy in a wavelength band around 4.5 µm and a wavelength band around 5.0 µm is selectively transmitted through narrow-band optical wavelength bandpass filters, the infrared energy is detected by a detection sensor for each band, after photoelectric conversion, predetermined processing such as amplification is performed to obtain an electrical signal corresponding to the amount of energy (hereinafter referred to as "light reception signal"), the relative ratio of the light reception signal levels of the respective wavelength bands is calculated, and the presence or absence of a flame is determined by comparing the ratio with a predetermined threshold.

[0006] This makes it possible to distinguish flames from other infrared radiators, such as high-temperature radiators like sunlight shown in spectral characteristic 102, relatively low-temperature radiators shown in spectral characteristic 10.5, and low-temperature radiators like the human body shown in spectral characteristic 106.

[0007] Furthermore, the flame detection device monitors for the presence or absence of flames by detecting infrared energy generated by flammable combustion through a translucent window. To maintain its flame monitoring function, a fouling test is conducted as a self-test to monitor for fouling of the translucent window.

[0008] In the fouling test, when a test signal is periodically transmitted from the fire alarm receiving panel, test light, which simulates a flame, is emitted from a test light source located outside the flame detector and enters a translucent window. The light is received by the detection unit, and the received signal is compared with the initial, unfouled state to determine the attenuation rate. If the attenuation rate exceeds a predetermined fouling threshold, a fouling alarm signal is transmitted to the fire alarm receiving panel to output a fouling alarm.

[0009] Furthermore, by multiplying the received light signal by the reciprocal of (1 - dimming rate), a dirt correction is performed to obtain a received light signal equivalent to the absence of dirt, and the presence or absence of flames is determined based on the dirt-corrected received signal.

[0010] Furthermore, if the light-transmitting window becomes heavily soiled and the light reduction rate exceeds, for example, 0.7, the system detects the soiling problem and outputs a soiling alarm from the receiving device to prompt the development of a cleaning plan. Since the correction of the received light signal has reached its limit, the system does not make a judgment about the presence or absence of flames based on the received light signal. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 06325268 [Patent Document 2] Patent No. 4817285 [Patent Document 3] Patent No. 3357330 [Patent Document 4] Japanese Patent Publication No. 2002-42263 [Patent Document 5] Patent No. 4623608 [Overview of the project] [Problems that the invention aims to solve]

[0012] However, in conventional fouling tests that measure the attenuation rate of a translucent window and correct the fouling of the received light signal, for example, the attenuation rate due to the translucent window is determined as a representative value based on the flame received light signal from a photodetector that receives infrared energy in the flame wavelength band around 4.5 μm, and the fouling of the flame received light signal is corrected. At the same time, the fouling of the non-flame received light signal from a non-flame photodetector that receives infrared energy in the non-flame wavelength band around 5.0 μm is also corrected. However, the fouling of the translucent window is uneven, and the attenuation rate may differ for each photodetector. If, despite this, the attenuation rate of a specific photodetector is used as a representative value to correct the fouling of the received light signals from other photodetectors, accurate fouling correction may not be achieved, and it may become impossible to make an accurate fire judgment based on the fouling-corrected received light signal.

[0013] The present invention aims to provide a flame detection device that enables accurate fire detection even if there are inconsistencies in the soiling of the translucent window, by performing soiling correction based on the attenuation rate of each light-receiving element. [Means for solving the problem]

[0014] (Flame detection device) The present invention is a flame detection device that observes infrared energy emitted from a monitoring area, detects the presence or absence of a combustion flame, and determines whether a fire is burning. Multiple detection units receive infrared energy emitted from the monitoring area through a light-transmitting window and output a received signal, A test control unit irradiates multiple detection units with test light from a test light source through a translucent window, and for each detection unit, compares the received light signal from the test light with the initial state to determine the attenuation rate of the infrared energy transmitted through the portion of the translucent window corresponding to each detection unit relative to the initial state. A fire detection unit corrects the light received signal for all detection units based on the light attenuation rate determined for each detection unit, and detects the presence or absence of a combustion flame based on the corrected light received signal to determine whether a fire is occurring. Equipped with, The multiple detection units are characterized by including multiple flame detection units that detect infrared radiation emitted from flames, and one or more non-flame detection units that detect infrared radiation emitted from sources other than flames.

[0015] Furthermore, when the light-receiving signal from any of the multiple detection units reaches a predetermined correction limit, the fire determination unit excludes the light-receiving signal that has reached the correction limit from the fire determination elements, and performs a fire determination using the light-receiving signals from at least the flame detection units that have not reached the correction limit as fire determination elements.

[0016] (Damage alarm or damage warning alarm) The fire detection unit causes the receiving device to output a contamination alarm or contamination warning alarm according to the attenuation rate of the received signals from multiple flame detection units, or the difference between said received signals, and causes the receiving device to output a predetermined fault alarm when the received signals from at least one flame detection unit reach the correction limit. [Effects of the Invention]

[0017] (Basic effects) The present invention provides a flame detection device that observes infrared energy emitted from a combustion flame to determine and detect the presence or absence of a combustion flame. The device includes a plurality of detection units that receive infrared energy emitted from a combustion flame through a translucent window and output a received signal; a test control unit that irradiates test light from a test light source through the translucent window and determines the attenuation rate relative to the initial state for each detection unit; and a fire determination unit that corrects the received signal for each detection unit based on the attenuation rate determined for each detection unit, and detects the presence or absence of a combustion flame and determines a fire based on the corrected received signal. By determining the attenuation rate for each detection unit and correcting the contamination of the received signal, even if there is uneven contamination of the translucent window, the contamination correction of each received signal can be performed correctly, and an accurate fire determination can be made using the corrected received signal.

[0018] (Effect of fire determination according to correction state) The fire determination unit changes fire determination depending on the correction state of the light reception signal. For example, when any one of the light reception signals of each detection unit reaches a predetermined correction limit, the fire determination unit performs fire determination based on other light reception signals that have not reached the correction limit. Therefore, in the case of a two-wavelength method, for example, when the light reception signal of a non-flame detection unit reaches the correction limit due to partial contamination of the translucent window, by switching to one-wavelength fire determination using only the light reception signal of the flame detection unit that has not reached the correction limit, flame detection can be continued through limited fire determination even when a contamination failure or a preliminary contamination failure is detected based on the correction limit, and the reliability of the flame detection device can be improved.

[0019] (Effect of contamination alarm or preliminary contamination alarm) Furthermore, since the fire determination unit detects a predetermined failure according to the correction state of the light reception signal and causes the receiving device to output an alarm, when any of the light reception signals from each detection unit reaches a predetermined correction limit, the receiving device outputs, for example, a contamination alarm or a preliminary contamination alarm. The contamination alarm or preliminary contamination alarm from the receiving device notifies that partial contamination of the translucent window has progressed and locally reached the correction limit, which enables prompting an administrator or the like to formulate a cleaning plan for the flame detection device or the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] [Figure 1] Block diagram showing an embodiment of a flame detection unit incorporated in a flame detection device [Figure 2] Explanatory diagram showing the external appearance of a flame detection device [Figure 3] Explanatory diagram showing the flame detection device of FIG. 2 from the front [Figure 4] Explanatory diagram showing, in partial cross-section, a test light source and a test window disposed on a central convex part when viewing the flame detection device of FIG. 2 from below, and a flame detection unit inside the translucent window [Figure 5] Explanatory diagram showing an exploded assembly state of a detection unit incorporated in the flame detection device of FIG. 1 [Figure 6]Diagram illustrating the schematic configuration of the flame detection sensor. [Figure 7] Figure 6 shows the equivalent circuit of the flame detection sensor. [Figure 8] Characteristic diagram showing the infrared transmittance at each wavelength of the optical wavelength filter and light-transmitting window applied to the embodiment shown in Figure 1. [Figure 9] The signal waveform diagram shows the flame reception signal output from the flame detection unit in Figure 1 when observing the infrared energy emitted from a combustion flame. [Figure 10] This diagram illustrates the frequency distribution of the flame light receiving signal E3 obtained from the flame detection unit in Figure 1 when infrared radiation emitted from a combustion flame is observed. [Figure 11] A time chart showing the drive signals for pulsed driving of the test light source. [Figure 12] This diagram in Figure 1 shows a list of the relationships between the effective light receiving signal, fire detection, and alarm in relation to the contamination state in the embodiment shown. [Figure 13] A flowchart showing the fouling test control in the embodiment shown in Figure 1. [Figure 14] Block diagram showing an embodiment of a three-wavelength flame detection unit incorporated into a flame detection device. [Figure 15] Figure 14 is an explanatory diagram showing the relationship between the effective light receiving signal, fire detection, and alarm in relation to the contamination state in the embodiment shown in Figure 14. [Figure 16] Characteristic diagrams showing the infrared spectra of combustion flames and other representative radiators in the infrared wavelength range. [Modes for carrying out the invention]

[0021] [Flame detection device] (Device overview) Figure 1 is a block diagram showing an embodiment of a flame detection unit incorporated into a flame detection device, using a two-wavelength flame detection device as an example. The flame detection device in this embodiment is a fire detection device that detects the presence or absence of flames in a monitored area.

[0022] As shown in Figure 1, the flame detection device 10 of this embodiment incorporates two sets of detection units: a flame detection unit 11-1 and another flame detection unit 11-2 (not shown) with the same configuration.

[0023] The flame detection unit 11-1 consists of flame detection units 12a and 12b, a non-flame detection unit 12c, and a fire determination unit 36 ​​and a test control unit 38 provided on the MPU (microprocessor unit) 15.

[0024] The flame detection units 12a and 12b observe infrared energy emitted from combustion flames present in the monitoring area. They receive infrared radiation in a predetermined wavelength band centered around 4.5 μm, emitted from the combustion flames in association with CO2 resonance, convert it into photoelectric energy, and output flame reception signals E1 and E2.

[0025] The flame detection units 12a and 12b are equipped with flame detection sensors 16a and 16b, pre-filters 24a and 24b, pre-amplifiers 26a and 26b, and main amplifiers 28a and 28b. The flame reception signals E1 and E2 output from the main amplifiers 28a and 28b are further amplified by the final stage amplifiers 30a and 30b to become flame reception signals E1' and E2', which are then converted into digital reception signals by the A / D conversion ports 35a and 35b of the MPU (microprocessor unit) 15 and taken in. For the sake of explanation, the same code is used for each reception signal before and after A / D conversion. The same applies to the reception signals E4' and E5' described later.

[0026] Furthermore, the flame light reception signals E1' and E2' output from the flame detection units 12a and 12b and read from the A / D conversion ports 35a and 35b are added together in the fire determination unit 36 ​​of the MPU 15 and used as an added light reception signal (added flame light reception signal) E3 for fire determination.

[0027] The non-flame detection unit 12c observes infrared energy emitted from heat sources other than combustion flames present in the monitoring area. It receives infrared energy in the wavelength range of approximately 5.0 μm to 7.0 μm and outputs a non-flame reception signal E4, which is converted into an electrical signal.

[0028] The non-flame detection unit 12c is equipped with a non-flame detection sensor 16c, a pre-filter 24c, a preamplifier 26c, and a main amplifier 28c. The non-flame light received signal E4 output from the main amplifier 28c is further amplified by the final stage amplifier 30c to become the non-flame light received signal E4', which is then converted into a digital light received signal by the A / D conversion port 35c of the MPU 15 and acquired. A translucent window 18, for example made of sapphire glass, is placed on the front side (monitoring area side) of the flame detection units 12a, 12b and the non-flame detection unit 12c, which transmits infrared rays in a predetermined wavelength band.

[0029] The fire detection unit 36 ​​calculates the ratio ΣE3 / Σ4' of the integral values ​​ΣE3 / Σ4' of the integral values ​​ΣE3 / Σ4' of the summation signal E3 and the non-flame signal E4' over the same period if the signal level of the summation signal E3 obtained by adding the flame signal E1' and E2', for example, the integral value ΣE3 of the summation signal E3 over a predetermined period, is equal to or exceeds a predetermined threshold, and determines that there is a flame (satisfaction of the first requirement described later).

[0030] In the following explanation, when it is not necessary to distinguish between flame-received signals and non-flame-received signals, or when referring to them collectively, the term "received signal" may be used.

[0031] (Overview of the stain test) A test light source 60-1, which functions as a test light source, is provided for the translucent window 18 of the flame detection unit 11-1. The test light source 60-1 is located on the central protrusion 54 on the front of the housing (case body) 50 of the flame detection device 10, which will be explained later. During the fouling test, which is one of the self-testing items, the test light source 60-1 is driven to output test light, which is a simulated flame light, from the translucent test window 56-1, and this test light is received by the flame detection sensors 16a, 16b and the non-flame detection sensor 16c, which are located inside the translucent window 18.

[0032] Similarly, a test light source 60-2 and a test window 56-2, used for testing the fouling of the translucent window 18 of another flame detection unit 11-2, are arranged in the central protrusion 54.

[0033] For example, krypton lamps are used as test light sources 60-1 and 60-2. Test light source 60-1 is equipped with a reflective hood 70 that functions as a reflector, directing the test light towards test window 56-1, i.e., towards each detection sensor. The reflective hood 70 ensures that the test light from test light source 60-1 is output only from test window 56-1 and not transmitted to test window 56-2. Similarly, test light source 60-2 is also equipped with a reflective hood 70, which ensures that the test light is output only from test window 56-2. The two reflective hoods 70 corresponding to test light sources 60-1 and 60-2 may be integrated into a single unit.

[0034] The fouling test of the translucent window 18 is performed individually based on the flame light receiving signals E1', E2' from the flame detection units 12a, 12b and the non-flame light receiving signal E4' from the non-flame detection unit 12c. The test control unit 38, located in the MPU 15, receives test signals periodically transmitted from a fire receiving panel (a receiving device not shown), and sequentially drives the test light sources 60-1 and 60-2 to output test light (for the flame detection unit 11-1 in Figure 1, the test is performed by driving the test light source 60-1). The test control unit reads the flame light receiving signals E1', E2' and non-flame light receiving signal E4' output from the final stage amplifiers 30a, 30b, and 30c, calculates the attenuation rates D1, D2, and D4 by comparing them with the initial state (unfouled state), and outputs them to the fire judgment unit 36.

[0035] The fire detection unit 36 ​​corrects (contamination corrects) the flame reception signals E1', E2' and non-flame reception signal E4' by multiplying them by 1 / (1-D1), 1 / (1-D2), and 1 / (1-D4). At the same time, the summation reception signal E3 is corrected by adding the corrected flame reception signals E1' and E2', and this is used together with the corrected E4' for fire detection. For the sake of explanation, the same symbols are used for the signals before and after correction.

[0036] Furthermore, the fire detection unit 36 ​​determines that the received light signal has reached its correction limit when the attenuation rates D1, D2, and D4 calculated by the test control unit 38 reach a predetermined threshold, for example, threshold Dth = 0.7 or higher, or when the threshold Dth = 0.7 is exceeded. It then detects a contamination malfunction or a contamination warning malfunction and outputs a contamination alarm or contamination warning alarm from the fire receiving panel. These alarms prompt the administrator to formulate a cleaning plan for the flame detection device 10.

[0037] Furthermore, if the fire detection unit 36 ​​determines that the flame light reception signals E1' and E2' have not reached the correction limit, but the non-flame light reception signal E4' has reached the correction limit, it performs a limited fire detection determination to the extent possible.

[0038] (Appearance of the device and sensor unit) Figure 2 is an explanatory diagram showing the external appearance of the flame detection device, Figure 3 is an explanatory diagram showing the flame detection device of Figure 2 from the front, and Figure 4 is an explanatory diagram showing the flame detection device of Figure 2 from below, with a partial cross-section showing the central convex test light source and test window and the flame detection section inside the translucent window.

[0039] As shown in Figures 2 to 4, the flame detection device 10 has infrared light-transmitting windows 18 in the sensor housing section 52 of the front cover located on the front of the housing 50, corresponding to two sets of flame detection units, including the flame detection unit 11-1 shown in Figure 1.

[0040] In the following explanation, test windows 56-1 and 56-2 may also be referred to as test window 56.

[0041] Each of the translucent windows 18 is equipped with the flame detection sensors 16a and 16b of the flame detection units 12a and 12b in the flame detection unit 11-1 shown in Figure 1, and the non-flame detection sensor 16c of the non-flame detection unit 12c in the other flame detection unit 11-2.

[0042] Furthermore, a central protrusion 54 is formed between the light-transmitting windows 18 provided in the sensor housing section 52. Test light sources 60-1 and 60-2 are housed in the central protrusion 54, and test windows 56-1 and 56-2 are positioned on the left and right side walls.

[0043] Test light source 60-1 outputs test light from test window 56-1 toward the translucent window 18. Test light source 60-2 outputs test light from test window 56-2 toward the translucent window 18.

[0044] As shown in Figures 2 and 3, a pair of light-transmitting windows 18 house a sensor unit, as shown in Figure 5. The sensor unit consists of a unit body 62 and a unit cover 64, and houses a circuit board 48 inside, secured by screws 68.

[0045] Flame detection sensors 16a and 16b are located adjacent to each other on the circuit board 48. Light-receiving apertures 66a and 66b are formed on the unit cover 64 at positions facing the flame detection sensors 16a and 16b, so that light passing through the translucent window 18 from the monitoring area side can be received by the flame detection sensors 16a and 16b.

[0046] Furthermore, a non-flame detection sensor 16c is positioned on the circuit board 48, and a light-receiving aperture 66c is formed on the unit cover 64 at a position opposite the non-flame detection sensor 16c, so that light passing through the translucent window 18 from the monitoring area side can be received by the non-flame detection sensor 16c.

[0047] (Configuration of flame detection units 12a and 12b) In the flame detection units 12a and 12b shown in Figure 1, the flame detection sensors 16a and 16b convert infrared energy having an infrared wavelength band centered on approximately 4.5 μm, emitted from the combustion flame in conjunction with CO2 resonance, into an electrical signal and output it as a received signal. The pre-filters 24a and 24b selectively pass only the signal components in a predetermined frequency band corresponding to the flame fluctuation frequency from the received signal output from the flame detection sensors 16a and 16b. The pre-amplifiers 26a and 26b first-stage amplify the signal components that have passed through the pre-filters 24a and 24b, and the main amplifiers 28a and 28b further amplify them to output flame received signals E1 and E2. Finally, the final stage amplifiers 30a and 30b amplify these to a signal level suitable for flame judgment processing and output flame received signals E1' and E2'.

[0048] Here, the flame detection sensors 16a and 16b are equipped with optical wavelength filters 20a and 20b, and light receiving elements 22a and 22b.

[0049] The flame light reception signals E1' and E2' output from the flame detection units 12a and 12b via the final stage amplifiers 30a and 30b are converted into digital light reception signals E1' and E2' by the A / D conversion ports 35a and 35b provided on the MPU 15 and read out.

[0050] Furthermore, the flame light signals E1' and E2' output from the flame detection units 12a and 12b and read from the A / D conversion ports 35a and 35b are added together by the fire determination unit 36 ​​of the MPU 15, and a determination of the presence or absence of flames is made based on this added light signal E3. The following describes each configuration in detail.

[0051] In this embodiment, the flame light signals E1' and E2' are not used to determine the presence or absence of a flame, but they may be used as appropriate to make the determination.

[0052] (Flame detection sensors 16a, 16b) Figure 6 is an explanatory diagram showing the schematic configuration of the flame detection sensor, and Figure 7 is a circuit diagram showing the equivalent circuit of the flame detection sensor in Figure 6.

[0053] As shown in Figure 6, the flame detection sensor 16a has a package configuration consisting of a pyroelectric element 45 supported on the surface of a substrate 40, a photodetector 25 provided thereon, a photodetector 22a comprising an FET 27 and a high resistance (not shown) located on the back side of the substrate 40, a terminal 42 provided through the base 37 while supporting the substrate 40 on the base 37, and a cover member 44 equipped with an optical wavelength filter 20a in front of (upper in the figure) the photodetector 22a.

[0054] Furthermore, as shown in Figure 7, the equivalent circuit of the light-receiving element section 22a is connected from the gate of the FET 27 to the gate terminal G via, for example, a parallel circuit of the pyroelectric element 45 and a high resistance 29, and the drain and source of the FET 27 are connected to the drain terminal D and source terminal S, respectively.

[0055] Here, the optical wavelength filter 20a selectively transmits a predetermined wavelength band centered around 4.5 μm, and can be formed on a substrate such as silicon or sapphire using known methods. The flame detection sensor 16b of the flame detection unit 12b has the same structure as the flame detection sensor 16a.

[0056] Furthermore, the non-flame detection sensor 16c of the non-flame detection unit 12c has the same structure as the flame detection sensor 16a, but differs in that it uses a cut-on filter (long-wave pass filter) as the optical wavelength filter 20c that transmits infrared light in a predetermined wavelength band generally exceeding 5.0 μm well.

[0057] (Translucent window 18) As shown in Figures 2 and 3, the light-transmitting window 18 is located on the upper side of the sensor unit in Figure 6, which houses the flame detection sensors 16a, 16b and the non-flame detection sensor 16c. It is positioned in a predetermined opening of the sensor housing 52, which is located on the front side of the flame detection sensors 16a, 16b and the non-flame detection sensor 16c, and is formed from an infrared light-transmitting material such as sapphire glass, as described above.

[0058] Therefore, the flame detection sensors 16a, 16b and the non-flame detection sensor 16c have their light-receiving limit field of view restricted by the edge of the light-transmitting window 18, thereby setting a detection area with a field of view having a predetermined spread angle.

[0059] Here, the sapphire glass constituting the translucent window 18 functions as a filter member having short-wave path characteristics that transmit infrared rays in a wavelength band of approximately 7.0 μm or less well, or in other words, long-wave cut characteristics that block infrared rays with wavelengths longer than approximately 7.0 μm. Furthermore, in this embodiment, the translucent window 18 is shared by the flame detection sensors 16a, 16b and the non-flame detection sensor 16c.

[0060] (Pre-filters 24a, 24b, 24c) The pre-filters 24a and 24b of the flame detection units 12a and 12b in Figure 1 function as frequency selectors and are, for example, active filters that allow only signal components in a specific frequency band used for flame determination processing to pass from the received signals output from the photo-receiving element sections 22a and 22b of the flame detection sensors 16a and 16b. They output the received signals consisting of signal components in a specific frequency band to the subsequent preamplifiers 26a and 26b.

[0061] Similarly, the pre-filter 24c is an active filter that passes only the signal components of a specific frequency band used for flame detection processing from the light-receiving signal output from the light-receiving element 22c of the non-flame detection sensor 16c, and outputs the light-receiving signal consisting of signal components of a specific frequency band to the subsequent preamplifier 26c.

[0062] Such frequency-selective filters are not only used as pre-filters but are also appropriately placed from the preamplifier to the final amplifier, allowing for signal amplification while selecting (extracting) frequencies.

[0063] (Preamplifiers 26a, 26b, 26c and main amplifiers 28a, 28b, 28c) The preamplifiers 26a and 26b amplify the received light signals input via the pre-filters 24a and 24b in the first stage at a predetermined amplification factor, and the main amplifiers 28a and 28b amplify the respective flame light received signals from the preamplifiers 26a and 26b and output them as flame light received signals E1 and E2.

[0064] The final stage amplifiers 30a and 30b adjust and amplify the flame reception signals E1 and E2 to a signal level suitable for flame detection processing, and output them as flame reception signals E1' and E2' to the A / D conversion ports 35a and 35b of the MPU15.

[0065] Similarly, the preamplifier 26c amplifies the non-flame light-receiving signal output via the pre-filter 24c at a predetermined amplification factor in the first stage, and the main amplifier 28c and final stage amplifier 30c amplify the non-flame light-receiving signal from the preamplifier 26c to a signal level suitable for the flame detection processing described later, and output it as the non-flame light-receiving signal E4 and the non-flame light-receiving signal E4'.

[0066] (A / D conversion ports 35a, 35b) The A / D conversion ports 35a and 35b are A / D converters provided as input ports for the MPU 15, which convert the flame light reception signals E1' and E2' into digital signals suitable for digital processing by the fire detection unit 36 ​​and read them.

[0067] (Non-flame detection unit 12c) The non-flame detection unit 12c includes a non-flame detection sensor 16c that converts infrared energy in a predetermined wavelength band different from that of the flame detection sensors 16a and 16b into an electrical signal and outputs it. Specifically, while the flame detection units 12a and 12b output flame reception signals E1 and E2, which are obtained by converting infrared energy in a wavelength band centered on approximately 4.5 μm, emitted from the combustion flame by CO2 resonance, into an electrical signal, the non-flame detection unit 12c outputs a non-flame reception signal E4, which is obtained by converting infrared energy in a wavelength band of approximately 5.0 μm to 7.0 μm into an electrical signal.

[0068] Furthermore, the non-flame detection unit 12c consists of a non-flame detection sensor 16c, a pre-filter 24c that passes only signal components within a predetermined frequency band from the light signal output from the non-flame detection sensor 16c, a pre-amplifier 26c that first-stage amplifies the signal components that have passed through the pre-filter 24c, and a main amplifier 28c that amplifies the output from the pre-amplifier 26c.

[0069] The non-flame receiving signal E4 output from the main amplifier 28c of the non-flame detection unit 12c is further adjusted and amplified by the final stage amplifier 30c to become the non-flame receiving signal E4'. This signal is then converted into a digital signal by the A / D conversion port 35c of the MPU 15 and read as the non-flame receiving signal E4', which is then used by the fire determination unit 36 ​​for flame determination processing.

[0070] (Configuration of non-flame detection sensor 16c) The non-flame detection sensor 16c comprises an optical wavelength filter 20c, which is a long-pass filter composed of a cut-on filter that transmits infrared light in a predetermined wavelength band generally exceeding 5.0 μm well, and a light-receiving element section 22c, which has an equivalent circuit similar to that shown in Figure 7, that receives the light transmitted through the optical wavelength filter 20c, converts it into an electrical signal, and outputs it. The sensor is packaged in a structure similar to that shown in Figure 6.

[0071] (Wavelength transmission characteristics of non-flame detection sensor 16c) Figure 8 is a characteristic diagram showing the transmittance at each wavelength of the optical wavelength filter and light-transmitting window applied to the embodiment of Figure 1.

[0072] As shown in Figure 8, the sapphire glass, which is the translucent window 18 in Figure 1, provides a transmittance characteristic 80 with a short-wave path characteristic (or long-wave cut characteristic) that transmits infrared rays of approximately 7.0 μm or less well.

[0073] Furthermore, the bandpass filters constituting the optical wavelength filters 20a and 20b, with a center wavelength of approximately 4.5 μm, provide a transmittance characteristic 82 that selectively transmits infrared energy in the wavelength band near the center wavelength. By combining these, a bandpass filter having a combined transmittance characteristic 84 with a center wavelength of approximately 4.5 μm is constructed.

[0074] On the other hand, the long-pass filter constituting the optical wavelength filter 20c provides a transmittance characteristic 86 that has cut-on filter characteristics that selectively transmit infrared rays in a predetermined wavelength band exceeding approximately 5.0 μm. By combining this with the transmittance characteristic 80 of the sapphire glass, a broadband bandpass filter is constructed that has a combined transmittance characteristic 88 that selectively transmits infrared rays in a wavelength band of approximately 5.0 μm to 7.0 μm.

[0075] (Fire Judgment Department 36) Figure 9 is a signal waveform diagram showing the flame reception signal output from the flame detection unit in Figure 1 when infrared energy radiated from a combustion flame is observed. Figure 9(A) shows the signal waveform of the flame reception signal E1' from the A / D conversion port 35a, and Figure 9(B) shows the signal waveform of the flame reception signal E2' from the A / D conversion port 35b.

[0076] Figures 9(A) and (B) were obtained simultaneously via flame detection units 12a and 12b with the same configuration and exhibit similarity. Furthermore, if the amplification factors of the final stage amplifiers 30a and 30b are the same, the waveforms will be almost identical. The summed photodetection signal E3 is the waveform obtained by adding and combining Figures 9(A) and 9(B).

[0077] Furthermore, the flame light reception signals E1' and E2' are corrected (dirt correction) by the fire determination unit 36 ​​based on the attenuation rates D1 and D2 of the flame detection units 12a and 12b detected by the test control unit 38. The summation light reception signal E3 is corrected by adding the corrected flame light reception signals E1' and E2'.

[0078] In this embodiment, A / D conversion is performed by sampling the received signal at 64 Hz, meaning that 64 digital data points are obtained per second for each signal.

[0079] The fire detection unit 36 ​​calculates the flame integral value ΣE3, which is the sum of the absolute values ​​of the differences from the reference potential, for the flame light reception signal shown in Figure 9 in units of T=2 seconds (128 data). If the flame integral value ΣE3 is equal to or greater than a predetermined threshold, the unit proceeds to the relative ratio determination described below.

[0080] If the fire detection unit 36 ​​determines that the flame integral value ΣE3 is equal to or exceeds a predetermined threshold, it determines the non-flame integral value ΣE4' for the same 2-second period as when the flame integral value ΣE3 was determined, in the same manner.

[0081] Next, the fire determination unit 36 ​​calculates the relative ratio (ΣE3 / ΣE4') between the flame integral value ΣE3 and the non-flame integral value ΣE4'. If the relative ratio (ΣE3 / ΣE4') exceeds a predetermined threshold, it determines that there is a flame and satisfies the first requirement for determining the presence of a flame.

[0082] Furthermore, the fire detection unit 36 ​​analyzes the results of the summation light reception signal E3 by performing a Fast Fourier Transform on the same 2 seconds (128 data points) used to calculate the flame integral value ΣE3. For example, if the principal component is in a frequency band of 8 Hz or less, it is determined that the second requirement for determining the presence of a flame is met. If both the first and second requirements are met, it is determined that a flame is present.

[0083] Figure 10 is an explanatory diagram showing the frequency distribution of the summation received signal E3 obtained from the flame detection unit in Figure 1 when infrared radiation emitted from a combustion flame is observed. As described above, the fire determination unit 36 ​​performs a fast Fourier transform on the summation received signal E3 for T=2 seconds (128 data points) to obtain, for example, the frequency distribution shown in Figure 10.

[0084] As shown in Figure 10, when infrared radiation emitted from a combustion flame is observed along the frequency axis, a frequency distribution showing high intensity is obtained in the frequency band FL, which is generally lower than 8 Hz. This indicates that the main frequency component of the summation received signal E3 is present in the frequency band FL up to 8 Hz. On the other hand, in the high-frequency band FH, which is above 8 Hz and extends up to 16 Hz, the signal shows a relatively low intensity distribution. This distribution characteristic is typical of the signal when observing a flame.

[0085] Therefore, flame determination based on the frequency distribution of the summation received signal E3 is performed using the relative intensity integral value ΣFL on the low-frequency side, for example, up to 8 Hz, and the range from 8 Hz to 16 Hz. The relative intensity integral value ΣFH on the high-frequency side is calculated, and if the ratio of the two values ​​ΣFL / ΣFH is less than or equal to a preset threshold, it is determined that no light-receiving output corresponding to a flame was detected, and the second requirement for determining the presence of a flame was not met. On the other hand, if ΣFL / ΣFH exceeds the threshold, it is determined that the second requirement for determining the presence of a flame has been met. The fire detection unit 36 ​​repeats each of the above determinations every T=2 seconds.

[0086] (Test control unit 38) Figure 11 is a time chart showing the drive signals for pulsed driving of the test light sources. Figure 11(A) shows the drive signal E11 for test light source 60-1, and Figure 11(B) shows the drive signal E12 for test light source 60-2.

[0087] When the test control unit 38 receives a test signal periodically transmitted by the fire alarm receiving panel, it outputs drive signals E11 and E12 shown in Figure 11 to the test light sources 60-1 and 60-2 to drive the light emission, and outputs test light to the translucent window 18 to perform a fouling test.

[0088] The test control unit 38 outputs drive signals E11 and E12 for a period T1, for example, T1 = 2 seconds, the period of the drive signals E11 and E12 is T2, and furthermore, the drive signals E11 and E12 have a phase difference of (T2 / 2).

[0089] As a result, when the drive signal E11 is at an H level and the test light source 60-1 is emitting light, the drive signal E12 is at an L level and the test light source 60-2 is turned off. Conversely, when the drive signal E11 is at an L level and the test light source 60-1 is turned off, the drive signal E12 is at an H level and the test light source 60-2 is turned on. Test light is alternately output from the test windows 56-1 and 56-2 toward the translucent window 18.

[0090] Therefore, the test time for the fouling test of both light-transmitting windows 18 by the test control unit 38 is T1 + (T2 / 2), which is the drive period T1 plus a phase shift (T2 / 2).

[0091] In contrast, if the two sets of translucent windows 18 are tested sequentially, for example, the drive shown in Figure 11(A) is performed to test for contamination of the translucent window 18, and then the drive shown in Figure 11(B) is performed to test for contamination of the translucent window 18. The total test time for one flame detection device 10 would be, for example, T=4 seconds. However, in this embodiment, it can be completed in just over 2 seconds, which is roughly half the time of the conventional method.

[0092] Therefore, when fouling tests are performed sequentially on multiple flame detection devices 10 by transmitting test signals from the fire receiving panel, the time during which the fire receiving panel is subjected to a control load due to the fouling tests can be reduced by about half compared to conventional methods, thereby minimizing the time during which the fire receiving panel is subjected to a control load and enabling the maintenance of its original fire monitoring function.

[0093] Note that the pulsed drive of the test light source does not necessarily follow the drive signals shown in Figure 11; instead, drive signals E11 and E12 may be output sequentially with a period T.

[0094] [Fouling Test Control] When the test control unit 38 located in the MPU 15 in Figure 1 receives a test signal from the fire detection panel, it drives the test light sources 60-1 and 60-2 to emit light according to the drive signal shown in Figure 11, and irradiates the flame detection units 11-1 and 11-2 with test light through the corresponding translucent windows 18 to perform a fouling test.

[0095] For example, the test control unit 38 drives the test light source 60-1 to emit light using the drive signal E11 shown in Figure 11, thereby outputting flame-simulating light equivalent to a fire flame through the test window 56-1, and causing it to be incident on the flame detection sensors 16a, 16b and the non-flame detection sensor 16c via the corresponding translucent window 18. The flame-simulating light from the test light source 60-1 includes the wavelength band received by the flame detection sensors 16a, 16b and the non-flame detection sensor, and the frequency band extracted by the pre-filters 24a, 24b, and 24c is, for example, light with a fluctuation frequency of 2 to 8 Hz, which is characteristic of flames.

[0096] The translucent window 18 is free of contamination at the time of factory shipment, and the light reception levels of the flame reception signals E1', E2' and non-flame reception signal E4' obtained during the contamination test are stored in the memory of the MPU 15 as reference light reception levels, and are used in the calculation of the attenuation rates D1, D2, and D4.

[0097] In other words, the test control unit 38 determines the attenuation rates D1, D2, and D4 from the flame reception signals E1', E2' and non-flame reception signal E4' read by the light emission drive of the test light source 60-1, and their respective reference reception levels stored in memory. The attenuation rates D1, D2, and D4 are 0 at the time of shipment, but as the operating period in the installation environment progresses, dirt adheres to the translucent window 18, and the attenuation rates gradually increase. Furthermore, since the dirt is uneven, the attenuation rates may be different due to differences in the degree of dirt in different areas.

[0098] Next, the fire detection unit 36 ​​calculates the flame reception signals E1', E2' and non-flame reception signal E4' after correction using the attenuation rates D1, D2, D4 obtained by the fouling test of the test control unit 38. Corrected E1' = E1' / (1-D1) Corrected E2' = E2' / (1-D2) Corrected E4' = E4' / (1-D4) After applying a dirt correction, the fire is determined based on the received values ​​of the dirt-corrected flame reception signals E1', E2' and non-flame reception signal E4'. Here, the dirt-corrected flame reception signals E1' and E2' are added together, and E1'+E2'=E3 is also used for fire determination.

[0099] Alternatively, the light attenuation rate D3 may be detected for the summed light received signal E3, and a dirt correction may be performed so that the corrected E3 = E3 / (1-D3).

[0100] [Soiling and Damage Treatment] The fire detection unit 36 ​​has a preset threshold Dth, for example, threshold Dth = 0.7, which is the dimming rate corresponding to the dirt correction limit. If the dimming rates D1, D2, and D4 obtained in the dirt test by the test control unit 38 are equal to or exceed the threshold, the unit determines that the dirt correction limit has been reached (for example, a state where the entire predetermined monitoring area cannot be monitored even after correction) and determines that there is a dirt damage failure or a dirt damage warning failure. The unit then transmits a dirt damage alarm signal or a dirt damage warning alarm signal to the fire receiving panel and controls it to output a dirt damage alarm or a dirt damage warning alarm.

[0101] Figure 12 is an explanatory diagram showing, in a list format, the relationship between the effective light receiving signal, fire detection, and alarm in relation to the contamination state in the embodiment of Figure 1.

[0102] Figure 12 shows the sensor contamination status (contamination status of the parts of the translucent window 18 corresponding to each sensor) for the flame detection sensors 16a, 16b and the non-flame detection sensor 16c. In terms of correction status, a circle (○) indicates that the correction limit has not been reached, and a cross (×) indicates that the correction limit has been reached.

[0103] Furthermore, for the flame-receiving signals E1', E2' and the non-flame-receiving signal E4', a circle (○) indicates that the attenuation rate has not reached the correction limit and the signal is valid, while an "x" (×) indicates that the attenuation rate has reached the correction limit and the signal is invalid.

[0104] Furthermore, fire detection is indicated by (addition, 2 wavelengths) using E3, which is the sum of flame reception signals E1' and E2', and the non-flame reception signal E4', and by (addition, 1 wavelength) indicating a limited fire detection using only E3, which is the sum of flame reception signals E1' and E2'. In addition, the alarm will be either a contamination alarm or a contamination warning alarm. Figure 12 divides the sensor contamination state into modes 1 and 2, as follows.

[0105] (Mode 1) In Mode 1, the received signals from the flame detection sensors 16a, 16b and the non-flame detection sensor 16c have not reached the correction limit, and all flame received signals E1', E2' and non-flame received signal E4' are obtained effectively. Therefore, the fire determination is made using the summed received signal E3 of the flame received signals E1' and E2' (summed, 2 wavelengths), which is the original fire determination method, no contamination malfunction has occurred, and no alarm has been issued.

[0106] (Mode 2) Mode 2 occurs when only the non-flame detection signal E4' of the non-flame detection sensor 16c reaches its correction limit. As a result, the non-flame detection signal E4' is invalid, and the flame detection signals E1' and E2' are valid, so the fire detection is limited (degenerate compared to (addition of two wavelengths)) and uses the summation of the flame detection signals E1' and E2' to obtain the detection signal E3.

[0107] In this case, the first requirement for determining the presence of flames is met when the flame integral value ΣE3 is equal to or exceeds a predetermined threshold, and the determination is not made based on the relative ratio (ΣE3 / ΣE4') between the flame integral value ΣE3 and the non-flame integral value ΣE4'.

[0108] Furthermore, fault handling detects a contamination fault or a contamination warning fault when the non-flame detection sensor 16c reaches its correction limit, notifies the fire alarm receiving panel, and outputs a contamination alarm or contamination warning alarm. The contamination alarm and contamination warning alarm are selected, for example, according to the degree of correction of the flame detection sensors 16a and 16b, i.e., the dimming rate. Specifically, each dimming rate is compared with a predetermined threshold, for example Dth1 (e.g., 0.5), and if the dimming rate of both or one of them is equal to or exceeds Dth1, it is determined that the correction limit has not yet been reached, but will soon be reached, and a contamination alarm is issued. Similarly, if the dimming rate is less than or equal to Dth2 when compared with another threshold Dth2 (e.g., 0.3), a contamination warning alarm is issued.

[0109] Alternatively, the selection could be made based on the difference between the received light signals E1' and E2'. In this case, a contamination alarm would be issued if the difference is above or greater than a predetermined threshold, and a contamination warning would be issued if the difference is below or less than the predetermined threshold. Of course, the selection could also be made by combining both the attenuation rate and the difference between the received light signals.

[0110] Furthermore, if either or both of the flame light receiving signals E1' and E2' reach the correction limit, the fire detection unit 36 ​​detects the contamination failure, notifies the fire receiving panel, and outputs a contamination alarm.

[0111] [Fouling Test Control] Figure 13 is a flowchart showing the control of the fouling test in the embodiment of Figure 1, and represents the control operation by the MPU15.

[0112] As shown in Figure 13, when the MPU 15 detects the reception of a test signal from the fire alarm receiving panel in step S1, it proceeds to step S2, where it activates the test lamp to emit light and irradiates each detection sensor with test light through the test window and the translucent window.

[0113] Next, in step S3, the MPU 15 individually calculates the attenuation rate based on the light received signals from each detection sensor (detection unit), and in step S4, it determines whether there are any detection sensors (detection units) that have reached a predetermined threshold Dth or higher and have reached the correction limit. If there are any detection sensors (detection units) that have reached the correction limit, it proceeds to step S5, where it detects contamination or a warning of contamination and outputs a contamination alarm or a warning of contamination alarm from the fire receiving panel. Furthermore, it proceeds to step S6, where it performs a limited fire determination using the summation of the flame light received signals E1' and E2' in mode 2 of Figure 12 (summation, 1 wavelength).

[0114] [Three-wavelength flame detection device] Figure 14 is a block diagram showing an embodiment of a three-wavelength flame detection unit incorporated into a flame detection device.

[0115] As shown in Figure 14, the detection unit of the flame detection device 10 in this embodiment incorporates two sets: a flame detection unit 11-1 and another flame detection unit 11-2 (not shown) with the same configuration.

[0116] The flame detection unit 11-1 consists of a flame detection unit 12a, non-flame detection units 12c and 12d, and a fire determination unit 36 ​​and a test control unit 38 provided in the MPU 15.

[0117] The flame detection unit 12a is the same as the non-flame detection unit 12a in Figure 1, and observes infrared energy emitted from combustion flames present in the monitoring area. It receives infrared energy in a predetermined wavelength band centered on 4.5 μm emitted from the combustion flame in conjunction with CO2 resonance, converts it into photoelectric energy, and outputs a flame reception signal E1.

[0118] The non-flame detection unit 12c is the same as the flame detection unit 12c in Figure 1. It observes infrared energy emitted from heat sources other than combustion flames present in the monitoring area, and outputs a non-flame reception signal E4 which is obtained by receiving infrared energy in the wavelength band of approximately 5.0 μm to 7.0 μm and converting it into an electrical signal.

[0119] In contrast, the non-flame detection unit 12d differs from the non-flame detection unit 12c in its optical wavelength filter 20d, but is otherwise basically the same (however, the amplification factor of each amplifier differs as appropriate). The optical wavelength filter 20d of the non-flame detection unit 12d receives infrared energy in a wavelength band, for example, around 2.3 μm (for example, 2.1 to 2.5 μm), which is different from the optical wavelength filter 20c of the non-flame detection unit 12c, and outputs a non-flame received signal E5 converted into an electrical signal. The other structures of the non-flame detection sensor 16d are the same as those of the flame detection sensor 16a shown in Figure 6. The equivalent circuit of the photodetector section 22d is also the same as that of the photodetector section 22a shown in Figure 7.

[0120] The non-flame-detecting signal E5' is adjusted and amplified by the final stage amplifier 30d to become the non-flame-detecting signal E5', which is then input to the A / D conversion port 35d.

[0121] The flame-receiving signal E1' and non-flame-receiving signals E4' and E5' are converted into digital reception signals and captured by the A / D conversion ports 35a, 35c, and 35d of the MPU15.

[0122] The test control unit 38, located in the MPU 15, receives a test signal periodically transmitted from the fire detection panel. It then sequentially drives the test light sources 60-1 and 60-2 to output test light, reads the flame reception signal E1' and non-flame reception signals E4' and E5' output from the final stage amplifiers 30a, 30c, and 30d, and calculates the attenuation rates D1, D4, and D5 by comparing them with the initial state (clean state).

[0123] Furthermore, the fire detection unit 36 ​​provided in the MPU 15 corrects for contamination by multiplying the flame light reception signal E1' and non-flame light reception signals E4' and E5' respectively by the reciprocals 1 / (1-D1), 1 / (1-D4), and 1 / (1-D5) of the attenuation rates D1, D4, and D5 calculated by the test control unit 38, and performs a three-wavelength fire detection using the contamination-corrected flame light reception signal E1' and non-flame light reception signals E4' and E5'.

[0124] The three-wavelength fire detection by the fire detection unit 36 ​​has three requirements: firstly, when the flame integral value ΣE1' is equal to or exceeds a predetermined threshold, it calculates the relative ratio (ΣE1' / ΣE4') between the flame integral value ΣE1' and the non-flame integral value ΣE4', and if the relative ratio (ΣE1' / ΣE4') is equal to or exceeds a threshold, it determines that there is a flame; secondly, it calculates the relative ratio (ΣE1' / ΣE5') between the flame integral value ΣE1' and the non-flame integral value ΣE5', and if the relative ratio (ΣE1' / ΣE5') is equal to or exceeds a threshold, it determines that there is a flame; and thirdly, it has three requirements: firstly, when all three requirements are met, and all three conditions are met for a predetermined number of consecutive occurrences, it determines that there is a flame and outputs a fire detection signal to the outside.

[0125] Furthermore, the fire detection unit 36 ​​detects a contamination failure or contamination warning failure if any of the attenuation rates D1, D4, or D5 calculated by the test control unit 38 are above a predetermined threshold, or if they are above or above a predetermined threshold and exceed the correction limit, for example, if the threshold is 0.7 or higher, or if the threshold is exceeded by 0.7. The unit then transmits a contamination alarm signal or contamination warning alarm signal to the fire receiving panel to output a contamination alarm or contamination warning alarm, prompting the administrator to formulate a cleaning plan for the flame detection device 10.

[0126] Furthermore, if the test control unit 38 determines that either or both of the non-flame light receiving signals E4' and E5' have reached their correction limits while the flame light receiving signal E1' has not reached its correction limit, the fire determination unit 36 ​​makes a limited fire determination based on the flame light receiving signal E1', or based on the flame light receiving signal E1' and the non-flame light receiving signal E4' or E5' that has not reached its correction limit.

[0127] Figure 15 is an explanatory diagram showing in a list format the relationship between the effective light-receiving signal, fire detection, and alarm in relation to the contamination state in the embodiment of Figure 14. The contamination state (the contamination state of the parts of the translucent window 18 corresponding to each sensor) is shown as the flame detection sensor 16a and the non-flame detection sensors 16c and 16d. The effective light-receiving signals are shown as the flame light-receiving signal E1' and the non-flame light-receiving signals E4' and E5'. The fire detection is shown as 3 wavelengths, 2 wavelengths, and 1 wavelength. Furthermore, the alarm is either a contamination alarm or a contamination warning alarm, and the contamination state is divided into modes 1 to 4 as follows.

[0128] (Mode 1) In Mode 1, the received signals from the flame detection sensor 16a and the non-flame detection sensors 16c and 16d have not reached the correction limit, and all flame received signals E1' and non-flame received signals E4' and E5' are obtained effectively. Therefore, the fire detection is performed according to the original fire detection method (3 wavelengths), no contamination malfunction has occurred, and no alarm is issued.

[0129] (Mode 2) Mode 2 occurs when only the light signal received by the non-flame detection sensor 16d reaches the correction limit. As a result, the non-flame light signal E5' is invalid, and the flame light signal E1' and non-flame light signal E4' are valid, so the fire determination becomes limited to (2 wavelengths) (degenerate compared to (3 wavelengths)).

[0130] The (two-wavelength) fire detection system calculates the relative ratio (ΣE2' / ΣE4') between the flame integral value ΣE1' and the non-flame integral value ΣE4' when the flame integral value ΣE1' is equal to or exceeds a predetermined threshold. If the relative ratio (ΣE1' / ΣE4') is equal to or exceeds the threshold, it is determined that there is a flame. The system also checks if both of the following conditions are met (both conditions are met), and if this occurs for a predetermined number of consecutive times, it confirms that there is a flame and outputs a fire detection signal to the outside.

[0131] Furthermore, fault handling detects a contamination fault or contamination warning fault when the non-flame detection sensor 16d reaches its correction limit, notifies the fire alarm receiving panel, and outputs a contamination alarm or contamination warning alarm.

[0132] The contamination alarm and contamination warning alarm are selected according to the degree of correction of the flame detection sensor 16a, i.e., the dimming rate. Specifically, the dimming rate is compared with a predetermined threshold, for example, Dth1 (e.g., 0.5). If the dimming rate is equal to or greater than Dth1, it is determined that the correction limit has not yet been reached, but will soon be reached, and a contamination alarm is issued. Similarly, the dimming rate is compared with another threshold, Dth2 (e.g., 0.3). If the dimming rate is less than or equal to Dth2, a contamination warning alarm is issued. The same applies to modes 3 and 4.

[0133] (Mode 3) Mode 3 occurs when only the light signal received by the non-flame detection sensor 16c reaches the correction limit. Therefore, the non-flame light signal E4' is invalid, and the flame light signal E1' and non-flame light signal E5' are valid, resulting in a limited fire detection based on (two wavelengths).

[0134] The (two-wavelength) fire detection system calculates the relative ratio (ΣE1' / ΣE5') between the flame integral value ΣE1' and the non-flame integral value ΣE5' when the flame integral value ΣE1' is equal to or exceeds a predetermined threshold. If the relative ratio (ΣE1' / ΣE5') is equal to or exceeds a threshold, a flame is considered to be present. The system also satisfies both the third requirement, which is the determination of the presence of a flame based on the frequency distribution of the flame light-receiving signal E1', and this is confirmed for a predetermined number of consecutive times. In this case, the determination of a flame is finalized and a fire detection signal is output externally.

[0135] Furthermore, fault handling detects a contamination fault or contamination warning fault when the light signal received by the non-flame detection sensor 16c reaches the correction limit, notifies the fire alarm receiving panel, and outputs a contamination alarm or contamination warning alarm.

[0136] (Mode 4) Mode 4 occurs when the light signals received by the non-flame detection sensors 16c and 16d reach the correction limit. As a result, the non-flame light signals E4' and E5' are invalid, and only the flame light signal E1' is valid, so the fire detection becomes a limited fire detection based on (one wavelength).

[0137] For a (1 wavelength) fire, the first requirement for determining the presence of a flame is met when the flame integral value ΣE1' is equal to or exceeds a threshold. If both of the second requirements for determining the presence of a flame based on the frequency distribution of the flame reception signal E1' are met, and this occurs for a predetermined number of consecutive times, the determination of a flame is confirmed and a fire detection signal is output externally.

[0138] Furthermore, fault handling detects a contamination fault or contamination warning fault when the light signals received by the non-flame detection sensors 16c and 16d reach the correction limit, notifies the fire alarm receiving panel, and outputs a contamination alarm or contamination warning alarm.

[0139] Furthermore, if the light signal received by the flame detection sensor 16a (flame light signal E1') reaches the correction limit, the fire determination unit 36 ​​detects a contamination failure, notifies the fire receiving panel, and outputs a contamination alarm.

[0140] [Modified version of the present invention] (Average of received light signals) In the embodiment shown in Figure 1 above, the presence or absence of flames is determined by the fire determination unit 36 ​​using an added light-receiving signal E3 obtained by adding the flame-receiving signals E1' and E2' from the flame detection units 12a and 12b. However, the invention is not limited to this, and for example, the average of the flame-receiving signals E1' and E2' from the flame detection units 12a and 12b may be calculated, and the fire determination unit 36 ​​may use the average light-receiving signal to determine the presence or absence of flames.

[0141] (Wavelength method) Furthermore, while the above embodiments use a single-wavelength method (multiple detection units), a two-wavelength method, and a three-wavelength method as examples, other types of flame detection devices may also be used. Additionally, the invention may be applied to flame detection devices that observe radiation energy other than infrared radiation.

[0142] (Correction of the received light signal for factors other than contamination) Furthermore, the functions and effects of the present invention include those not described above. For example, not only when there is dirt or unevenness in the translucent window 18, but also when the received light signal decreases due to a malfunction or deterioration of the detection sensor of the detection unit, the received light signal will be corrected based on the attenuation rate for each detection unit, and a contamination alarm signal or contamination warning alarm signal will be sent to the fire alarm receiving panel according to the degree of signal reduction to provide notification. Upon receiving this, the administrator will clean the translucent window 18, and if the contamination or contamination warning condition is not resolved by this, it can be inferred that there is a malfunction in the detection sensor of the detection unit or the like.

[0143] (others) Furthermore, the present invention includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the numerical values ​​shown in the above embodiments. [Explanation of symbols]

[0144] 10: Flame detection device 11-1: Flame detection unit 12a, 12b: Flame detection unit 12c, 12d: Non-flame detection unit 15: MPU 16a, 16b: Flame detection sensor 16c, 16d: Non-flame detection sensor 18: Translucent window 20a, 20b, 20c, 20d: Optical wavelength filters 22a, 22b, 22c, 22d: Photodetector section 24a, 24b, 24c, 24d: Pre-filter 25: Light receiving electrode 26a, 26b, 26c, 26d: Preamplifier 27:FET 28a, 28b, 28c, 28d: Main amplifier 30a, 30b, 30c, 30d: Final stage amplifier 35a, 35b, 35c, 35d: A / D conversion port 36:Fire Judgment Department 38: Test Control Unit 45: Pyroelectric material 50: Cabinet 52: Sensor housing 54: Central protrusion 56-1, 56-2: Test window 60, 60-1, 60-2: Test light source 70: Reflective Hood

Claims

1. A flame detection device that observes infrared energy emitted from a monitoring area, detects the presence or absence of a combustion flame, and determines whether a fire is burning, Two flame detection units receive the infrared energy radiated from the monitoring area through a light-transmitting window and output a light-receiving signal. Each of the flame detection units comprises three detection units that detect infrared radiation of different wavelengths, A test light source equipped with a reflector that reflects test light corresponding to the infrared energy toward the other flame detection unit so that it does not pass through one of the flame detection units, A test control unit irradiates the two flame detection units with the test light from the test light source through the reflector and the light-transmitting window, and for each of the detection units, compares the received light signal from the test light with the initial state to determine the attenuation rate of the infrared energy transmitted through the portion of the light-transmitting window corresponding to each detection unit relative to the initial state. A fire determination unit that corrects the light reception signal for all of the detection units based on the light attenuation rate obtained for each of the detection units, and detects the presence or absence of a combustion flame based on each corrected light reception signal to determine whether a fire is occurring, Equipped with, The three detection units include two flame detection units that detect infrared radiation emitted from flames, and one non-flame detection unit that detects infrared radiation emitted from sources other than flames. The fire detection device is characterized in that, when the light received signal from any of the three detection units reaches a predetermined correction limit, the light received signal that has reached the correction limit is excluded from the fire detection elements, and the light received signals from at least the flame detection units that have not reached the correction limit are used as fire detection elements to make a fire determination.

2. A flame detection device that observes infrared energy emitted from a monitoring area, detects the presence or absence of a combustion flame, and determines whether a fire is burning, Two flame detection units receive the infrared energy radiated from the monitoring area through a light-transmitting window and output a light-receiving signal. Each of the flame detection units comprises three detection units that detect infrared radiation of different wavelengths, A test light source equipped with a reflector that reflects test light corresponding to the infrared energy toward the other flame detection unit so that it does not pass through one of the flame detection units, A test control unit irradiates the two flame detection units with the test light from the test light source through the reflector and the light-transmitting window, and for each of the detection units, compares the received light signal from the test light with the initial state to determine the attenuation rate of the infrared energy transmitted through the portion of the light-transmitting window corresponding to each detection unit relative to the initial state. A fire determination unit that corrects the light reception signal for all of the detection units based on the light attenuation rate obtained for each of the detection units, and detects the presence or absence of a combustion flame based on each corrected light reception signal to determine whether a fire is occurring, Equipped with, The three detection units include one flame detection unit that detects infrared radiation emitted from a flame, and two non-flame detection units that detect infrared radiation emitted from sources other than flames. The fire detection device is characterized in that, when the light received signal from any of the three detection units reaches a predetermined correction limit, the light received signal that has reached the correction limit is excluded from the fire detection elements, and the light received signals from at least the flame detection units that have not reached the correction limit are used as fire detection elements to make a fire determination.

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