Flame detector

Abstract

To enable accurate fire determination by performing dirt correction for each light receiving element even when dirt of a translucent window is uneven.SOLUTION: A flame detector comprises flame detection units 12a and 12b that receive infrared energy emitted from a combustion flame by flame detection sensors 16a and 16b through a translucent window 18 and output a flame light reception signal, and a non-flame detection unit 12c that receives the infrared energy emitted from a flame other than the combustion flame by a non-flame detection sensor 16c through the translucent window and output non-flame light reception signal. A test control unit 38 emits test light from a test light source through the translucent window to obtain a light reduction rate due to dirt of the translucent window for each detection unit. A fire determination unit 36 corrects the flame light reception signal and the non-flame light reception signal based on this, detects the presence or absence of the combustion flame based on each corrected light reception signal to determine fire, and outputs a fouling warning or a fouling announcement warning to a reception device in accordance with the light reduction rate of the flame light reception signal or a difference between the flame light reception signals.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, in the field of flame detection devices and flame detection methods that detect the presence or absence of a flame by detecting infrared energy generated by flaming combustion, a well-known flame detection device or method detects the presence or absence of a flame by detecting the infrared intensity in the resonant radiation wavelength band of CO2 generated during flaming combustion.

[0003] Here, we will briefly explain a conventional two-wavelength flame detection device. Figure 16 is a conceptual diagram showing the infrared spectra of a combustion flame and other typical radiators in the infrared wavelength range, with the horizontal axis representing the infrared wavelength and the vertical axis representing the relative intensity of the infrared.

[0004] 16, in the spectral characteristics 100 of a combustion flame, there is a peak in the relative infrared intensity associated with the resonance radiation of CO2 in a wavelength band around 4.5 μm, and as a characteristic wavelength near this peak wavelength, there is a wavelength band with low relative infrared intensity near 5.0 μm on the long wavelength side. Hereinafter, unless otherwise specified, the CO2 resonance radiation band refers to the 4.5 μm band.

[0005] In a two-wavelength flame detection device, for example, infrared energy in the wavelength bands around 4.5 μm and around 5.0 μm is selectively transmitted by a narrow-band optical wavelength bandpass filter, and the infrared energy is detected by a detection sensor for each. This infrared energy is then photoelectrically converted and subjected to predetermined processing such as amplification to produce an electrical signal corresponding to the amount of energy (hereinafter referred to as the "received light signal"). The relative ratio of the received light signal levels in each of the above wavelength bands is then taken and compared with a predetermined threshold to determine the presence or absence of a flame.

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

[0007] The flame detection device detects infrared energy generated by flaming combustion through a light-transmitting window to monitor the presence or absence of a flame, and in order to maintain the flame monitoring function, a dirt test is performed as a self-test to monitor dirt on the light-transmitting window.

[0008] In the contamination test, when a test signal transmitted periodically from the fire receiving panel is received, test light that simulates flames is projected from a test light source located outside the flame detector onto a translucent window, received by the detection unit, and the received light signal is compared with the initial, uncontaminated state to determine the light attenuation rate.If the light attenuation rate exceeds a predetermined contamination threshold, a contamination alarm signal is sent to the fire receiving panel, causing a contamination alarm to be output.

[0009] In addition, a dirt correction is performed by multiplying the received light signal by the inverse of (1 - extinction rate) to obtain a received light signal equivalent to when there is no dirt, and the presence or absence of a flame is determined based on the dirt-corrected received light signal.

[0010] Furthermore, if the light-transmitting window becomes so dirty that the light attenuation rate reaches, for example, 0.7 or more, a contamination problem is detected and a contamination alarm is output from the receiving device to prompt the development of a cleaning plan.Since the correction of the light-receiving signal has reached its limit, the presence or absence of a flame is not determined based on the light-receiving signal. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 06-325268 [Patent Document 2] Patent No. 4817285 [Patent Document 3] Patent No. 3357330 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-42263 [Patent Document 5] Patent No. 4623608 Summary of the Invention [Problem to be solved by the invention]

[0012] However, in such conventional fouling tests that measure the light attenuation rate of a translucent window and correct the light-receiving signal for fouling, the light attenuation rate due to the translucent window is determined as a representative value based on the flame light-receiving signal from a light-receiving element that receives infrared energy in the flame wavelength band around 4.5 μm, for example, and fouling correction is performed on the flame light-receiving signal, as well as fouling correction on the non-flame light-receiving signal from a non-flame light-receiving element that receives infrared energy in the non-flame wavelength band around 5.0 μm.However, fouling on the translucent window is uneven, and the light attenuation rate may differ for each light-receiving element.Despite this, if the light attenuation rate of a specific light-receiving element is used as a representative value to correct for fouling on the light-receiving signals from other light-receiving elements, the fouling correction will not be accurate, and there is a possibility that the fouling-corrected light-receiving signal will not be able to be used to accurately determine whether a fire has occurred.

[0013] An object of the present invention is to provide a flame detection device that can accurately determine whether a fire has occurred by correcting for dirt based on the light attenuation rate of each light-receiving element, even if the dirt on the light-transmitting window is uneven. [Means for solving the problem]

[0014] (Flame detection device) The present invention is a flame detection device that observes infrared energy radiated from a monitoring area, detects the presence or absence of a combustion flame, and determines whether a fire has occurred, a plurality of detection units that receive infrared energy radiated from a monitoring area through a light-transmitting window and output a light-receiving signal; a test control unit that irradiates a plurality of detection units with test light from a test light source through a light-transmitting window, and compares a light-receiving signal from the test light with an initial state for each detection unit, thereby determining an attenuation rate of infrared energy transmitted through a portion of the light-transmitting window corresponding to each detection unit, compared to the initial state; a fire detection unit that corrects the light receiving signals of all the detection units based on the light attenuation rate calculated for each detection unit, and detects the presence or absence of a combustion flame based on each corrected light receiving signal to determine whether a fire is present; Equipped with The plurality of detection units are characterized by including a plurality of flame detection units that detect infrared rays emitted from a flame, and one or more non-flame detection units that detect infrared rays emitted from sources other than a flame.

[0015] In addition, when the light receiving signal of any of the multiple detection units reaches a predetermined correction limit, the fire judgment unit excludes the light receiving signal that has reached the correction limit from the fire judgment elements, and makes a fire judgment by using at least the light receiving signal from the flame detection unit that has not reached the correction limit as a fire judgment element.

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

[0017] (Basic effect) The present invention is a flame detection device that observes infrared energy radiated from a combustion flame and determines and detects the presence or absence of a combustion flame, and is provided with a plurality of detection units that receive the infrared energy radiated from the combustion flame through a light-transmitting window and output a light-receiving signal; a test control unit that irradiates test light from a test light source through the light-transmitting window and determines the light-attenuation rate relative to the initial state for each detection unit; and a fire judgment unit that corrects the light-receiving signal for each detection unit based on the light-attenuation rate determined for each detection unit, and detects the presence or absence of a combustion flame based on each corrected light-receiving signal to determine a fire.Therefore, by determining the light-attenuation rate for each detection unit and correcting the dirt on the light-receiving signal, the dirt correction for each light-receiving signal can be performed correctly even if the dirt on the light-transmitting window is uneven, and an accurate fire judgment can be made using the corrected light-receiving signal.

[0018] (Effect of fire judgment according to correction state) The fire judgment unit makes different fire judgments depending on the correction state of the light receiving signal.For example, when the light receiving signal of one of the detection units reaches a predetermined correction limit, the fire judgment unit makes a fire judgment based on the other light receiving signals that have not reached the correction limit.Therefore, in the case of a two-wavelength system, for example, when the light receiving signal of a non-flame detection unit reaches the correction limit due to partial dirt on the translucent window, the unit switches to a one-wavelength fire judgment based only on the light receiving signal of the flame detection unit that has not reached the correction limit.Even if a dirt fault or a dirt warning fault is detected based on the correction limit, flame detection can be continued with a limited fire judgment, thereby increasing the reliability of the flame detection device.

[0019] (Effect of Defacement Warning or Defacement Pre-warning Warning) In addition, the fire judgment unit detects a specified fault depending on the correction state of the received light signal and outputs an alarm to the receiving device. Therefore, when any of the received light signals from each detection unit reaches a specified correction limit, the receiving device outputs, for example, a contamination alarm or a contamination warning alarm. The receiving device notifies the user that partial contamination of the translucent window has progressed to the point where the correction limit has been reached, and this contamination alarm or contamination warning alarm can prompt the manager, etc. to formulate a cleaning plan for the flame detection device, etc. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a block diagram illustrating an embodiment of a flame detection unit incorporated into a flame detection device. [Figure 2] An explanatory diagram showing the appearance of a flame detection device [Figure 3] An explanatory diagram showing the flame detection device of Figure 2 from the front. [Figure 4] An explanatory diagram showing the flame detection device of Figure 2 as seen from below, with a partial cross section of the test light source and test window located in the central convex part, and the flame detection part inside the light-transmitting window. [Figure 5] FIG. 2 is an explanatory diagram showing the detection unit incorporated in the flame detection device of FIG. 1 in an assembled and disassembled state. [Figure 6]An explanatory diagram showing the schematic configuration of a flame detection sensor [Figure 7] Circuit diagram showing the equivalent circuit of the flame detection sensor in Figure 6 [Figure 8] FIG. 2 is a characteristic diagram showing the infrared transmittance at each wavelength of the optical wavelength filter and the light-transmitting window applied to the embodiment of FIG. 1. [Figure 9] Signal waveform diagram showing the flame reception signal output from the flame detection unit in Figure 1 when infrared energy emitted from a combustion flame is observed. [Figure 10] An explanatory diagram showing the frequency distribution of the flame reception signal E3 obtained from the flame detection unit of Figure 1 when observing infrared rays emitted from a combustion flame. [Figure 11] 1 is a timing chart showing a driving signal for pulse-driving a test light source; [Figure 12] FIG. 2 is an explanatory diagram showing in a table format the relationship between effective light receiving signals, fire determination, and alarms in relation to the state of contamination in the embodiment of FIG. 1. [Figure 13] A flowchart showing the soiling test control in the embodiment of FIG. 1. [Figure 14] 1 is a block diagram showing an embodiment of a three-wavelength flame detection unit incorporated in a flame detection device. [Figure 15] FIG. 15 is an explanatory diagram showing in a table format the relationship between the effective light receiving signal, fire determination, and alarm with respect to the state of contamination in the embodiment of FIG. 14. [Figure 16] A characteristic diagram showing the infrared spectra of combustion flames and other typical radiators in the infrared wavelength range. DETAILED DESCRIPTION OF THE INVENTION

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

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

[0023] Flame detection section 11-1 is made up of flame detection units 12a and 12b, non-flame detection unit 12c, a fire determination section 36 provided in MPU (microprocessor unit) 15, and a test control section 38.

[0024] The flame detection units 12a and 12b observe the infrared energy emitted from the combustion flame present in the monitoring area, receive infrared light in a predetermined wavelength band centered on 4.5 μm that is emitted from the combustion flame due to CO2 resonance, perform photoelectric conversion, and output flame reception signals E1 and E2.

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

[0026] In addition, 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 detection section 36 of the MPU 15 and used for fire detection as an added light reception signal (added flame light reception signal) E3.

[0027] The non-flame detection unit 12c observes infrared energy emitted from heating elements other than combustion flames present in the monitoring area, and receives infrared energy in the wavelength band of approximately 5.0 μm to 7.0 μm and converts it into an electrical signal to output a non-flame reception signal E4.

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

[0029] When the signal level of the added light receiving signal E3 obtained by adding the flame light receiving signals E1' and E2', for example, the integral value ΣE3 of the added light receiving signal E3 over a predetermined period, is above or exceeds a predetermined threshold, the fire judgment unit 36 ​​calculates the ratio ΣE3 / Σ4' of the integral values ​​of the added light receiving signal E3 and the non-flame light receiving signal E4' over the same period, and if this is above or exceeds another threshold, it judges that a flame is present (the first requirement described below is met).

[0030] In the following description, when there is no need to distinguish between flame light receiving signals and non-flame light receiving signals, or when they are referred to collectively, they may be simply referred to as light receiving signals.

[0031] (Outline of soiling test) A test light source 60-1 that functions as a test light source is provided for the light-transmitting window 18 of the flame detection unit 11-1. The test light source 60-1 is arranged in a central convex portion 54 on the front surface of the housing (case body) 50 of the flame detection device 10, which will be explained later, and during a dirt test, which is one item in the self-test, the test light source 60-1 is driven to output test light that becomes flame-simulating light from the light-transmitting test window 56-1, and this test light is received by the flame detection sensors 16a, 16b and the non-flame detection sensor 16c that are arranged inside the light-transmitting window 18.

[0032] A test light source 60-2 and a test window 56-2 used for a stain test on the light-transmitting window 18 of another flame detection unit 11-2 are also arranged in the central convex portion 54 in the same manner.

[0033] For example, krypton lamps are used as the test light sources 60-1 and 60-2. The test light source 60-1 is provided with a reflective hood 70 that functions as a reflector that reflects the test light toward the test window 56-1, i.e., toward each detection sensor. The reflective hood 70 allows the test light from the test light source 60-1 to be emitted only through the test window 56-1 and not to be transmitted to the test window 56-2. The test light source 60-2 is also provided with a similar reflective hood 70, allowing the test light to be emitted only through the test window 56-2. The two reflective hoods 70 corresponding to the test light sources 60-1 and 60-2 may be integrated.

[0034] The contamination test for the light-transmitting window 18 is performed individually based on the flame reception signals E1', E2' from the flame detection units 12a, 12b and the non-flame reception signal E4' from the non-flame detection unit 12c. When the test control unit 38 provided in the MPU 15 receives a test signal periodically transmitted from a fire reception panel (not shown), it sequentially drives the test light sources 60-1, 60-2 to output test light (the test for the flame detection unit 11-1 in FIG. 1 is performed by driving the test light source 60-1), reads the flame reception signals E1', E2' and the non-flame reception signal E4' output from the final stage amplifiers 30a, 30b, 30c, and compares them with the initial state (a clean state) to calculate the light attenuation rates D1, D2, D4, and output them to the fire judgment unit 36.

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

[0036] Furthermore, when the dimming rates D1, D2, and D4 calculated by the test control unit 38 become equal to or greater than a predetermined threshold, for example, the threshold Dth=0.7, the fire judgment unit 36 ​​judges that the received light signal has reached the correction limit, detects a contamination fault or a contamination warning fault, and causes the fire receiving panel to output a contamination alarm or a contamination warning alarm, which prompts the administrator to formulate a cleaning plan for the flame detection device 10, etc.

[0037] Furthermore, when 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 to the extent possible.

[0038] (Appearance of the device and sensor unit) FIG. 2 is an explanatory diagram showing the appearance of the flame detection device, FIG. 3 is an explanatory diagram showing the flame detection device of FIG. 2 from the front, and FIG. 4 is an explanatory diagram showing the test light source and test window in the central convex part and the flame detection part inside the translucent window as viewed from below.

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

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

[0041] Within each of the light-transmitting windows 18, the flame detection section 11-1 shown in Figure 1 and the flame detection sensors 16a, 16b of the flame detection units 12a, 12b and the non-flame detection sensor 16c of the non-flame detection unit 12c in the other flame detection section 11-2 are arranged.

[0042] A central protrusion 54 is formed to protrude between the light-transmitting windows 18 provided in the sensor housing 52. Test light sources 60-1 and 60-2 are built into the central protrusion 54, and test windows 56-1 and 56-2 are arranged on the left and right side walls.

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

[0044] 2 and 3, a sensor unit is incorporated inside the pair of light-transmitting windows 18 as shown in Fig. 5. The sensor unit is composed of a unit body 62 and a unit cover 64, and houses the circuit board 48 inside, fixed with screws 68.

[0045] Flame detection sensors 16a and 16b are disposed adjacent to circuit board 48. Light-receiving openings 66a and 66b are formed in unit cover 64 at positions facing flame detection sensors 16a and 16b, allowing flame detection sensors 16a and 16b to receive light that passes through light-transmitting window 18 from the monitoring area side.

[0046] In addition, a non-flame detection sensor 16c is arranged on the circuit board 48, and a light receiving opening 66c is formed in the unit cover 64 at a position opposite the non-flame detection sensor 16c, so that light that passes 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 emitted from the combustion flame due to CO2 resonance into an electrical signal and output it as a light-receiving signal. The pre-filters 24a and 24b selectively pass only signal components in a predetermined frequency band corresponding to the flame fluctuation frequency from the light-receiving signals output from the flame detection sensors 16a and 16b. The pre-amplifiers 26a and 26b initially amplify the signal components that passed through the pre-filters 24a and 24b. The main amplifiers 28a and 28b further amplify the signal components to output flame-receiving signals E1 and E2. The final-stage amplifiers 30a and 30b then amplify the signal components to a signal level suitable for flame determination processing and output flame-receiving signals E1' and E2'.

[0048] Here, the flame detection sensors 16a and 16b include optical wavelength filters 20a and 20b, and light receiving element portions 22a and 22b.

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

[0050] Furthermore, the flame light receiving 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 section 36 of the MPU 15, and the presence or absence of a flame is determined based on this added light receiving signal E3. Each component will be described in detail below.

[0051] In this embodiment, the flame light receiving signals E1' and E2' are not used to determine whether or not a flame is present, but they may be used appropriately to make the determination.

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

[0053] As shown in Figure 6, the flame detection sensor 16a has a pyroelectric element 45 supported and arranged on the surface of a substrate 40, on which a light-receiving electrode 25 is provided, and has a package configuration consisting of a light-receiving element section 22a having an FET 27 arranged on the back side of the substrate 40, a high resistor (not shown), a terminal 42 that supports the substrate 40 on a base 37 and penetrates the base 37, and a cover member 44 that has an optical wavelength filter 20a in front of (above in the figure) the light-receiving element section 22a.

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

[0055] Here, optical wavelength filter 20a selectively transmits a predetermined wavelength band centered at 4.5 μm, and can be formed by a known method on a substrate such as silicon or sapphire.Furthermore, flame detection sensor 16b of flame detection unit 12b has the same structure as 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 the optical wavelength filter 20c is a cut-on filter (long wave pass filter) that effectively transmits infrared rays in a specified wavelength band exceeding approximately 5.0 μm.

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

[0058] Therefore, the flame detection sensors 16a, 16b and non-flame detection sensor 16c have their light receiving limit fields of view restricted by the edges of the light-transmitting window 18, so that a detection area with a field range having a predetermined spread angle is set.

[0059] The sapphire glass that constitutes the light-transmitting window 18 functions as a filter member having a short-wave pass characteristic that allows infrared light in a wavelength band of approximately 7.0 μm or less to pass through well, in other words, a long-wave cut characteristic that blocks infrared light with a wavelength longer than approximately 7.0 μm. In this embodiment, the light-transmitting window 18 is shared by the flame detection sensors 16 a, 16 b and the non-flame detection sensor 16 c.

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

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

[0062] Such frequency selective filters are not only used as pre-filters but are also arranged appropriately from the preamplifier to the final amplifier, so that signals are amplified while selecting (extracting) frequencies.

[0063] (Preamplifiers 26a, 26b, and 26c and main amplifiers 28a, 28b, and 28c) The preamplifiers 26a and 26b initially amplify the received light signals input via the pre-filters 24a and 24b at a predetermined amplification factor, and the main amplifiers 28a and 28b amplify the flame received light signals from the preamplifiers 26a and 26b and output them as flame received light 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 finally suitable for the flame determination process, and output them to the A / D conversion ports 35a and 35b of the MPU 15 as flame reception signals E1' and E2'.

[0065] Similarly, the preamplifier 26c initially amplifies the non-flame light receiving signal output via the pre-filter 24c at a predetermined amplification factor, 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 determination process described below, 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) A / D conversion ports 35a and 35b are A / D converters provided as input ports of the MPU 15, and convert the flame 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) Non-flame detection unit 12c includes non-flame detection sensor 16c that converts infrared energy in a predetermined wavelength band different from that of flame detection sensors 16a and 16b into an electrical signal and outputs the signal. That is, flame detection units 12a and 12b output flame receiving signals E1 and E2 by converting infrared energy in a wavelength band centered at approximately 4.5 μm, which is emitted from a combustion flame due to CO resonance, into an electrical signal, whereas non-flame detection unit 12c outputs non-flame receiving signal E4 by converting infrared energy in a wavelength band of approximately 5.0 μm to 7.0 μm into an electrical signal.

[0068] In addition, the non-flame detection unit 12c is composed of, following the non-flame detection sensor 16c, a pre-filter 24c that passes only signal components in a predetermined frequency band from the light receiving signal output from the non-flame detection sensor 16c, a pre-amplifier 26c that initially 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 light 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 light receiving signal E4', which is converted into a digital signal by the A / D conversion port 35c of the MPU 15 and read as the non-flame light receiving signal E4', and used in the flame detection process by the fire detection unit 36.

[0070] (Configuration of non-flame detection sensor 16c) The non-flame detection sensor 16c is equipped with an optical wavelength filter 20c, which is a long-pass filter made up of a cut-on filter that effectively transmits infrared rays in a predetermined wavelength band exceeding approximately 5.0 μm, and a light-receiving element unit 22c consisting of an equivalent circuit similar to that shown in Figure 7 that receives light that has passed through the optical wavelength filter 20c, converts it into an electrical signal, and outputs it, and is packaged with a structure similar to that shown in Figure 6.

[0071] (Wavelength transmission characteristics of non-flame detection sensor 16c) FIG. 8 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.

[0072] As shown in FIG. 8, the sapphire glass that is the light-transmitting window 18 in FIG. 1 provides a transmittance characteristic 80 having short wave pass characteristics (or long wave cut characteristics) that allows infrared light of approximately 7.0 μm or less to be transmitted well.

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

[0074] Meanwhile, the long-pass filter constituting the optical wavelength filter 20c provides a transmittance characteristic 86 having a cut-on filter characteristic that selectively transmits infrared rays in a predetermined wavelength band exceeding approximately 5.0 μm. By combining this with the transmittance characteristic 80 of sapphire glass, a wideband band-pass filter is formed that has a composite 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 of Figure 1 when infrared energy emitted from a combustion flame is observed, where 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] 9(A) and (B) are similar because they were obtained simultaneously via flame detection units 12a and 12b with the same configuration. Furthermore, if the amplification factors of final stage amplifiers 30a and 30b are the same, the waveforms will be nearly identical. The added light receiving signal E3 has a waveform obtained by adding together the waveforms in FIGS. 9(A) and 9(B).

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

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

[0079] The fire judgment unit 36 ​​calculates the flame integral value ΣE3, which is the sum of the absolute values ​​of the differences from the reference potential for each T = 2 seconds (128 data) for the flame reception signal shown in Figure 9, and if the flame integral value ΣE3 is equal to or exceeds a predetermined threshold value, proceeds to the relative ratio judgment described next.

[0080] When the flame integral value ΣE3 is equal to or exceeds a predetermined threshold value, the fire determination unit 36 ​​calculates the non-flame integral value ΣE4' for the same two seconds as this time in the same manner as the flame integral value ΣE3 was calculated.

[0081] Next, the fire judgment unit 36 ​​calculates the relative ratio (ΣE3 / ΣE4') between the flame integral value ΣE3 and the non-flame integral value ΣE4', and if the relative ratio (ΣE3 / ΣE4') exceeds a predetermined threshold, it judges that there is a flame and that the first requirement for judging that there is a flame is met.

[0082] In addition, the fire judgment unit 36 ​​performs a fast Fourier transform on the added light receiving signal E3 for the same 2 seconds (128 data points) as used to calculate the flame integral value ΣE3, analyzes the results, and determines that the second requirement for determining whether a flame is present is met if, for example, the main component is in the frequency band below 8 Hz, and determines that a flame is present if both the first and second requirements are met.

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

[0084] As shown in Figure 10, when infrared rays emitted from a combustion flame are observed on the frequency axis, a frequency distribution showing high intensity in the frequency band FL on the lower frequency side of approximately 8 Hz is obtained. This shows that the main frequency components of the added light receiving signal E3 exist in the frequency band FL up to 8 Hz. On the other hand, the high frequency band FH, which is above 8 Hz and up to 16 Hz, shows a distribution with relatively low intensity. This distribution characteristic is characteristic of signals observed when a flame is observed.

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

[0086] (Test control unit 38) 11A and 11B are time charts showing drive signals for pulse-driving the test light sources, where FIG. 11A shows the drive signal E11 for the test light source 60-1, and FIG. 11B shows the drive signal E12 for the test light source 60-2.

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

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

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

[0090] Therefore, the test time for the test control unit 38 to test for dirt on both sides of the light-transmitting window 18 is T1+(T2 / 2) which is the driving period T1 plus the phase shift (T2 / 2).

[0091] In contrast, if two sets of translucent windows 18 are tested in sequence, for example, the operation shown in FIG. 11(A) is performed to test for dirt on the translucent windows 18, and then the operation shown in FIG. 11(B) is performed to test for dirt on the translucent windows 18, and the total test time for one flame detection device 10 is, for example, T=4 seconds. In this embodiment, however, the test time is just over 2 seconds, which is approximately half the time required in the conventional case.

[0092] Therefore, when contamination tests of a large number of flame detection devices 10 are performed in sequence by transmitting test signals from the fire receiving panel, the time during which the control load due to the contamination test is applied to the fire receiving panel can be reduced to about half compared to the conventional method, making it possible to reduce the time during which the control load is applied to the fire receiving panel as much as possible and maintain its original fire monitoring function.

[0093] The test light source may be pulse-driven not by the drive signals of FIG. 11 but by outputting drive signals E11 and E12 in sequence at a period T.

[0094] [Stain test control] When the test control unit 38 provided in the MPU 15 in Figure 1 receives a test signal from the fire receiving panel, it drives the test light sources 60-1 and 60-2 to emit light using the drive signal shown in Figure 11, and irradiates the test light onto the flame detection units 11-1 and 11-2 through the corresponding translucent windows 18 to perform a dirt test.

[0095] For example, test control unit 38 drives test light source 60-1 to emit light using drive signal E11 in Fig. 11, causing flame simulating light corresponding to a fire flame to be output through test window 56-1 and incident on flame detection sensors 16a, 16b and non-flame detection sensor 16c via corresponding light-transmitting windows 18. The flame simulating light from test light source 60-1 includes a wavelength band received by flame detection sensors 16a, 16b and non-flame detection sensors, and is light having a fluctuation frequency of 2 to 8 Hz, for example, that is specific to flames, as a frequency band extracted by pre-filters 24a, 24b, 24c.

[0096] The light-transmitting window 18 is free of dirt when shipped from the factory, and the light reception levels of the flame light reception signals E1', E2' and the non-flame light reception signal E4' obtained in the dirt test at that time are stored in the memory of the MPU 15 as reference light reception levels, and are used to calculate the light attenuation rates D1, D2, and D4.

[0097] That is, the test control unit 38 calculates the light attenuation rates D1, D2, and D4 from the flame light reception signals E1', E2' and non-flame light reception signal E4' read by driving the test light source 60-1 to emit light, and from the respective reference light reception levels stored in memory. The light attenuation rates D1, D2, and D4 are set to 0 at the time of shipment, but as the operating period passes in the installed environment, dirt accumulates on the translucent window 18, gradually increasing the light attenuation rates. Furthermore, because the dirt is uneven, differences in the degree of dirt in different parts of the system can result in different values ​​for the light attenuation rates.

[0098] Next, the fire determination unit 36 ​​calculates the flame light receiving signals E1', E2' and the non-flame light receiving signal E4' after correction using the light attenuation rates D1, D2, and D4 obtained by the soiling test of the test control unit 38. Corrected E1' = E1' / (1-D1) Corrected E2' = E2' / (1-D2) Corrected E4' = E4' / (1-D4) A contamination correction is performed, and a fire is judged based on the contamination-corrected flame reception signals E1', E2' and the non-flame reception signal E4'. Here, the contamination-corrected flame reception signals E1' and E2' are added together, and E1' + E2' = E3 is also used to judge a fire.

[0099] It is also possible to detect a light attenuation rate D3 for the added light receiving signal E3 and perform a dirt correction such that the corrected E3=E3 / (1-D3).

[0100] [Defacement and damage treatment] The fire judgment unit 36 ​​is preset with a threshold value Dth, for example, Dth=0.7, which is the dimming rate corresponding to the dirt correction limit, and when the dimming rates D1, D2, D4 obtained in the dirt test by the test control unit 38 are equal to or greater than the threshold value, it judges that this is a dirt correction limit (for example, a state in which the entire specified monitoring area cannot be monitored even with correction) and judges it to be a dirt failure or a dirt warning failure, and controls the unit to send a dirt warning signal or a dirt warning warning signal to the fire receiving panel to output a dirt warning or a dirt warning.

[0101] FIG. 12 is an explanatory diagram showing in a table format the relationship between the effective light receiving signal, fire determination, and alarm for the state of contamination in the embodiment of FIG.

[0102] FIG. 12 shows the flame detection sensors 16a, 16b and the non-flame detection sensor 16c as sensor contamination states (the contamination states of the portions of the light-transmitting window 18 corresponding to each sensor), and as correction states, a circle indicates that the correction limit has not been reached, and an 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 light attenuation rate has not reached the correction limit and is a valid signal, while an cross indicates that the light attenuation rate has reached the correction limit and is invalid.

[0104] Furthermore, fire detection is indicated by (additional 2 wavelengths) when E3, the sum of flame reception signals E1' and E2', and non-flame reception signal E4', while (additional 1 wavelength) when limited fire detection is only E3, the sum of flame reception signals E1' and E2'. Furthermore, alarms are either contamination alarms or contamination warning alarms. Figure 12 divides the sensor contamination state into modes 1 and 2, as follows:

[0105] (Mode 1) In mode 1, none of the light receiving signals from the flame detection sensors 16a, 16b and the non-flame detection sensor 16c have reached the correction limit, and the flame light receiving signals E1', E2' and the non-flame light receiving signal E4' are all validly obtained. Therefore, the fire is judged as it should be by using the added light receiving signal E3 of the flame light receiving signals E1', E2' (addition of two wavelengths), and no contamination failure has occurred, so no alarm is issued.

[0106] (Mode 2) Mode 2 is the case where only the non-flame light receiving signal E4' of the non-flame detection sensor 16c has reached the correction limit. Therefore, since the non-flame light receiving signal E4' is invalid and the flame light receiving signals E1' and E2' are valid, the fire detection is limited (degenerate compared to (addition + 2 wavelengths)) by using the added light receiving signal E3 of the flame light receiving signals E1' and E2' (addition + 1 wavelength).

[0107] In this case, if the flame integral value ΣE3 is equal to or exceeds a predetermined threshold value, the first requirement for determining whether a flame is present is considered to be met, and no determination is made based on the relative ratio (ΣE3 / ΣE4') between the flame integral value ΣE3 and the non-flame integral value ΣE4'.

[0108] In addition, the fault processing detects a contamination fault or contamination notice fault when the non-flame detection sensor 16c reaches its correction limit, and notifies the fire receiving panel to output a contamination alarm or contamination notice alarm. The contamination alarm and contamination notice 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). If both or either of the dimming rates is equal to or exceeds Dth1, it is determined that the correction limit has not 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 Dth2, a contamination notice alarm is issued.

[0109] Alternatively, the selection may be made based on the difference between the light receiving signals E1' and E2', in which case a contamination alarm is issued when the difference is equal to or greater than a predetermined threshold, and a contamination advance warning alarm is issued when the difference is less than the predetermined threshold. Of course, the selection may be made by combining both the light reduction rate and the difference between the light receiving signals.

[0110] If either or both of the flame light receiving signals E1' and E2' reach the correction limit, the fire determination unit 36 ​​detects a contamination fault and notifies the fire receiving panel, causing a contamination alarm to be output.

[0111] [Stain test control] FIG. 13 is a flowchart showing the soiling test control in the embodiment of FIG.

[0112] As shown in FIG. 13, when the MPU 15 determines in step S1 that it has received a test signal from the fire receiving panel, it proceeds to step S2, where it drives 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 calculates the light attenuation rate individually based on the light reception signal from each detection sensor (detection unit), and in step S4 determines whether there is any detection sensor (detection unit) that has reached the correction limit and is above a predetermined threshold Dth.If there is any detection sensor (detection unit) that has reached the correction limit, the MPU 15 proceeds to step S5, detects contamination or a warning of contamination, and outputs a contamination alarm or a warning of contamination alarm from the fire receiving panel, and then proceeds to step S6, where a limited fire judgment is made using the added light reception signal E3 of the flame light reception signals E1' and E2' in mode 2 of Figure 12 (addition x 1 wavelength).

[0114] [Three-wavelength flame detection device] FIG. 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 FIG. 14, the detection unit of the flame detection device 10 of this embodiment incorporates two sets of flame detection section 11-1 and another flame detection section 11-2 (not shown) of the same configuration.

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

[0117] The flame detection unit 12a is the same as the non-flame detection unit 12a in Figure 1, and observes the infrared energy emitted from a combustion flame present in the monitoring area. It receives infrared energy in a predetermined wavelength band centered on 4.5 μm that is emitted from the combustion flame in association with CO2 resonance, converts it photoelectrically, 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, and observes infrared energy emitted from heating elements other than combustion flames that are present in the monitoring area.It receives infrared energy in the wavelength band of approximately 5.0 μm to 7.0 μm and converts it into an electrical signal to output a non-flame reception signal E4.

[0119] In contrast, non-flame detection unit 12d is basically the same as non-flame detection unit 12c except for optical wavelength filter 20d (however, the amplification factor of each amplifier may differ as appropriate). Optical wavelength filter 20d of non-flame detection unit 12d receives infrared energy in a wavelength band around 2.3 μm (e.g., 2.1 to 2.5 μm) different from that of optical wavelength filter 20c of non-flame detection unit 12c, converts it into an electrical signal, and outputs non-flame light-receiving signal E5. Other structures of non-flame detection sensor 16d are similar to those of flame detection sensor 16a shown in FIG. 6. The equivalent circuit of light-receiving element section 22d is also the same as that of light-receiving element section 22a shown in FIG. 7.

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

[0121] The flame light receiving signal E1' and non-flame light receiving signals E4' and E5' are converted into digital light receiving signals by the A / D conversion ports 35a, 35c, and 35d of the MPU 15 and are then taken in.

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

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

[0124] The fire detection unit 36 ​​detects a fire at three wavelengths by calculating the relative ratio (ΣE1' / 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, and determining that a flame is present if the relative ratio (ΣE1' / ΣE4') is equal to or exceeds the threshold; then calculating the relative ratio (ΣE1' / ΣE5') between the flame integral value ΣE1' and the non-flame integral value ΣE5'; determining that a flame is present if the relative ratio (ΣE1' / ΣE5') is equal to or exceeds the threshold; and finally, determining that a flame is present based on the frequency distribution of the flame reception signal E1'.If all three of these requirements are met and this occurs a predetermined number of times in a row, the fire detection unit 36 ​​confirms the detection of a flame and outputs a fire detection signal to the outside.

[0125] Furthermore, if any of the dimming rates D1, D4, D5 calculated by the test control unit 38 becomes equal to or exceeds a predetermined threshold, or becomes equal to or exceeds a predetermined threshold and reaches the correction limit, for example, becomes equal to or exceeds a threshold of 0.7, the fire judgment unit 36 ​​detects a contamination fault or a contamination warning fault, and transmits a contamination alarm signal or a contamination warning alarm signal to the fire receiving panel to output a contamination alarm or a contamination warning alarm, and prompts the administrator to formulate a cleaning plan for the flame detection device 10, etc.

[0126] In addition, when the test control unit 38 determines that one or both of the non-flame receiving signals E4', E5' have reached the correction limit while the flame receiving signal E1' has not reached the correction limit, the fire judgment unit 36 ​​makes a limited fire judgment based on the flame receiving signal E1', or based on the flame receiving signal E1' and the non-flame receiving signal E4' or E5' that has not reached the correction limit.

[0127] Figure 15 is an explanatory diagram showing in a list format the relationship between the effective light receiving signal, fire judgment, and alarm in relation to the contamination state in the embodiment of Figure 14, and shows the flame detection sensor 16a and non-flame detection sensors 16c, 16d as the contamination state (the contamination state of the part of the translucent window 18 corresponding to each sensor), the flame detection signal E1' and the non-flame detection signals E4', E5' as the effective light receiving signal, the fire judgment shows 3 wavelengths, 2 wavelengths, and 1 wavelength, and further the alarm is 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 light receiving signals of the flame detection sensor 16a and the non-flame detection sensors 16c and 16d have not reached the correction limit, and the flame light receiving signal E1' and the non-flame light receiving signals E4' and E5' are all validly obtained. Therefore, the fire detection is the original fire detection based on (three wavelengths), no contamination failure has occurred, and no alarm is issued.

[0129] (Mode 2) Mode 2 is the case where only the light receiving signal of the non-flame detection sensor 16d reaches the correction limit. Therefore, the non-flame light receiving signal E5' is invalid, and the flame light receiving signal E1' and the non-flame light receiving signal E4' are valid, so the fire detection is limited to (two wavelengths) (degenerate compared to (three wavelengths)).

[0130] In the (two wavelength) fire judgment, when the flame integral value ΣE1' is equal to or exceeds a predetermined threshold, the relative ratio (ΣE2' / ΣE4') between the flame integral value ΣE1' and the non-flame integral value ΣE4' is calculated, and if the relative ratio (ΣE1' / ΣE4') is equal to or exceeds the threshold, both the first requirement of determining that a flame is present and the second requirement of determining that a flame is present based on the frequency distribution of the flame reception signal E1' are met (the two conditions are met), and if this occurs a predetermined number of times in succession, the judgment of a flame is confirmed and a fire detection signal is output to the outside.

[0131] Furthermore, the fault processing detects a contamination fault or a contamination notice fault when the non-flame detection sensor 16d reaches the correction limit, and notifies the fire receiving panel to output a contamination alarm or a contamination notice alarm.

[0132] The contamination alarm and contamination advance warning alarm are selected, for example, 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), and if the dimming rate is equal to or greater than Dth1, it is determined that the correction limit has not 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), and if the dimming rate is less than Dth2 or less, a contamination advance warning alarm is issued. The same applies to modes 3 and 4.

[0133] (Mode 3) Mode 3 is the case where only the light receiving signal of the non-flame detection sensor 16c reaches the correction limit. Therefore, the non-flame light receiving signal E4' is invalid, and the flame light receiving signal E1' and the non-flame light receiving signal E5' are valid, so the fire detection is limited to the two wavelengths.

[0134] For (two wavelength) fire detection, when the flame integral value ΣE1' is equal to or exceeds a predetermined threshold, the relative ratio (ΣE1' / ΣE5') between the flame integral value ΣE1' and the non-flame integral value ΣE5' is calculated, and if the relative ratio (ΣE1' / ΣE5') is equal to or exceeds the threshold, both the third requirement of determining that a flame is present and the second requirement of determining that a flame is present based on the frequency distribution of the flame reception signal E1' are met, and if this occurs a predetermined number of times in a row, the determination that there is a flame is confirmed and a fire detection signal is output to the outside.

[0135] In addition, the fault processing detects a contamination fault or a contamination warning fault when the light receiving signal of the non-flame detection sensor 16c reaches the correction limit, and notifies the fire receiving panel to output a contamination alarm or a contamination warning alarm.

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

[0137] For fire detection (one wavelength), when the flame integral value ΣE1' is equal to or exceeds a threshold value, the first requirement for determining whether a flame is present is deemed to be met, and when both of the second requirements for determining whether a flame is present based on the frequency distribution of the flame reception signal E1' are met and this occurs a predetermined number of times in succession, the determination of a flame is confirmed and a fire detection signal is output to the outside.

[0138] In addition, the fault processing detects a contamination fault or a contamination warning fault when the light receiving signal of the non-flame detection sensors 16c, 16d reaches the correction limit, and notifies the fire receiving panel to output a contamination alarm or a contamination warning alarm.

[0139] If the light receiving signal (flame light receiving signal E1') of the flame detection sensor 16a reaches the correction limit, the fire determination unit 36 ​​detects a contamination failure, notifies the fire receiving panel, and causes a contamination alarm to be output.

[0140] [Modifications of the present invention] (average of received light signal) In the embodiment of FIG. 1, the fire judgment unit 36 ​​judges whether or not a flame is present using an added light reception signal E3 obtained by adding the flame light reception signals E1' and E2' from the flame detection units 12a and 12b, but this is not limited to this. For example, the flame light reception signals E1' and E2' from the flame detection units 12a and 12b may be averaged, and the average light reception signal may be taken in to allow the fire judgment unit 36 ​​to judge whether or not a flame is present.

[0141] (Wavelength method) Although the above embodiments have been described using a one-wavelength system (multiple detection units), a two-wavelength system, and a three-wavelength system, other systems of flame detection devices may also be used.Furthermore, the present invention may be applied to flame detection devices that observe radiation energy other than infrared light.

[0142] (Compensation of received light signals for factors other than contamination) The functions and effects of the present invention also include those not described above. For example, not only when the light-transmitting window 18 is dirty or unevenly dirty, but also when the light-receiving signal decreases due to malfunction or deterioration of the detection sensor of the detection unit, the light-receiving signal is corrected based on the light attenuation rate for each detection unit, and a contamination alarm signal or a contamination warning alarm signal is sent to the fire receiving panel depending on the degree of signal deterioration. In response, the manager cleans the light-transmitting window 18, and if this does not resolve the contamination or contamination warning state, it can be assumed that there is an abnormality in the detection sensor of the detection unit, etc.

[0143] (others) Furthermore, the present invention includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to 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 sensors 16c, 16d: Non-flame detection sensor 18: Translucent window 20a, 20b, 20c, 20d: Optical wavelength filters 22a, 22b, 22c, 22d: Light receiving element 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 50: Cabinet 52: Sensor storage section 54: Central convex part 56-1, 56-2: Test window 60, 60-1, 60-2: Test light source 70:Reflective hood

Claims

[Claim 1] A flame detection device that observes infrared energy radiated from a monitoring area, detects the presence or absence of a combustion flame, and determines whether a fire has occurred, a plurality of detection units that receive the infrared energy radiated from the monitoring area through a light-transmitting window and output a light-receiving signal; a test control unit that irradiates test light from a test light source onto the plurality of detection units through the light-transmitting window, and compares a light-receiving signal generated by the test light with an initial state for each of the detection units to determine an attenuation rate, relative to the initial state, of the infrared energy that passes through a portion of the light-transmitting window that corresponds to each detection unit; a fire detection unit that corrects the light receiving signals for all of the detection units based on the light attenuation rate calculated for each of the detection units, and detects the presence or absence of a combustion flame based on each corrected light receiving signal to determine whether a fire is present; Equipped with the plurality of detection units include a plurality of flame detection units that detect infrared rays emitted from a flame, and one or more non-flame detection units that detect infrared rays emitted from sources other than a flame; The fire detection device is characterized in that, when the light receiving signal of any of the multiple detection units reaches a predetermined correction limit, the fire judgment unit excludes the light receiving signal that has reached the correction limit from the fire judgment elements, and performs fire judgment using at least the light receiving signal from the flame detection unit that has not reached the correction limit as a fire judgment element.

Images