JP6878197B2 - Smoke detectors - Google Patents

Description

The present invention relates to a smoke detector that determines the type of smoke or the like using a plurality of light emitting elements.

Conventionally, there has been known a photoelectric smoke detector that detects smoke and detects a fire by emitting light from a light emitting element and receiving scattered light generated from smoke particles by a light receiving element. The smoke to be detected by the photoelectric smoke detector is not uniform, and the characteristics of scattered light generation in the smoke detector differ depending on the type of smoke. Therefore, a photoelectric smoke detector has been proposed that detects a scattered light intensity for each different wavelength and determines a fire while determining the type of smoke or the like (see, for example, Patent Documents 1 to 3).

Patent Documents 1 and 2 describe two first light emitting elements and a second light emitting element, and a light receiving element that receives forward scattered light and backward scattered light emitted from smoke by light from the first light emitting element and the second light emitting element. A photoelectric smoke detector equipped with the above is disclosed. Of these, in Patent Document 1, the first light emitting element emits near-infrared light (wavelength 900 nm), and the second light emitting element emits blue light (wavelength 500 nm). Then, it is disclosed that the angle between the first light emitting element and the light receiving element is set to an acute angle (30 °) and the angle between the second light emitting element and the light receiving element is set to an obtuse angle (120 °) to receive scattered light. Has been done. Further, Patent Document 3 has one light projecting unit that emits near-infrared light (wavelength 950 nm) and two light receiving parts, and the two light receiving parts scatter the smoke forward and backward. A photoelectric smoke detector that receives light is disclosed.

Japanese Unexamined Patent Publication No. 2004-325211 Japanese Unexamined Patent Publication No. 2001-236575 Japanese Unexamined Patent Publication No. 11-160238

However, when a light emitting element that emits light having a different wavelength is used as in Patent Document 1, the accuracy of fire detection is improved due to the difference in output change and aging deterioration characteristics depending on the temperature of the light emitting element. May deteriorate. Further, when near-infrared light is used as the light emitting element as in Patent Documents 1 and 3, the sensitivity to black smoke is low, and the accuracy of fire detection may deteriorate.

Therefore, an object of the present invention is to provide a smoke detector capable of suppressing deterioration of fire detection accuracy.

The smoke detector according to the present invention has a first light emitting element that emits red light in the visible light region toward the smoke detection space and a second light emitting element that emits the same red light as the first light emitting element toward the smoke detection space. A light emitting element, a light receiving element arranged at a sharp angle with respect to the optical axis of the first light emitting element and an oblique angle with respect to the optical axis of the second light emitting element, and a second light receiving element received by the light emitting element of the first light emitting element. It includes a control unit that determines a fire based on the one output signal and the second output signal received by the light receiving element by the light emitted from the second light emitting element.

The control unit obtains a correction coefficient from the output ratio of the first output signal and the second output signal, corrects the first output signal using the obtained correction coefficient, and uses the corrected first output signal. A fire may be determined.

Further, the control unit has a correction table showing the relationship between the output ratio and the correction coefficient, and the correction table includes a first region in which the correction coefficient for the output ratio is set as the first correction coefficient, and a correction for the output ratio. A second region whose coefficient is set to a second correction coefficient larger than the first correction coefficient is set between the first region and the second region, and the first correction coefficient to the second correction coefficient are set as the output ratio increases. A transition region that changes to may be set.

Further, the correction coefficient of the transition region may increase in proportion to the output ratio.

Further, in the correction table, a non-fire region in which the correction coefficient is set to a non-fire correction coefficient smaller than the first correction coefficient in a region having an output ratio smaller than that of the first region may be set.

According to the smoke detector according to the present invention, the first light emitting element and the second light emitting element emit red light in the same visible light region, thereby ensuring sensitivity to black smoke and the first light emitting element. Since the output change and aging deterioration due to temperature are almost the same as those of the second light emitting element, deterioration of fire detection accuracy can be suppressed.

It is a schematic diagram which shows the embodiment of the smoke detection part of the smoke detector which concerns on this invention. It is a block diagram which shows the embodiment of the smoke detector which concerns on this invention. It is a graph which shows the relationship between the output ratio of the 1st combination (red / red) and the 2nd combination (blue / red) with respect to various smokes, and a frequency distribution. It is a graph which shows an example of the correction table stored in the storage part of FIG. It is a graph which shows the relationship between the output ratio of the 1st combination (red / red) and the 2nd combination (blue / red) for various smokes, and a frequency distribution. It is a graph which superposed the frequency distribution with respect to the output ratio of various smokes on the correction table in the first combination (red, red). It is a graph in which the frequency distribution with respect to the output ratio of various smokes is superimposed on the correction table in the second combination (blue / red). It is a graph which shows the smoke density at the time of burning a filter paper, and the time transition of the 1st output signal after correction. It is a graph which shows the smoke concentration at the time of burning a heptane-toluene mixed fuel (black smoke), and the time change of the 1st output signal after correction. It is a graph which shows the smoke density at the time of burning a trash can containing resin, paper, etc., and the time change of the 1st output signal after correction. The first output signal after correction by the first combination (red / red) and the first output after correction by the second combination (blue / red) for the smoke concentrations of various smoke types measured by the CS meter. It is a graph which plots the 1st output signal at the time of receiving a signal and the forward scattered light of near-infrared light, and shows the regression line. It is a graph which shows the modification of the correction table stored in the storage part of FIG. It is a graph which superposed the frequency distribution with respect to the output ratio of various smokes on the correction table in the first combination (red, red).

FIG. 1 is a schematic view of an embodiment of the smoke detector according to the present invention, and FIG. 2 is a block diagram showing an embodiment of the smoke detector according to the present invention. The smoke detector 1 of FIGS. 1 and 2 emits light toward the smoke detection space 2a formed in the smoke detection unit 2 and receives scattered light from smoke existing in the smoke detection space 2a. It is a photoelectric smoke detector that detects smoke. The smoke detector 1 includes a first light emitting element 11, a second light emitting element 12, a light receiving element 13, and a control unit 20.

The first light emitting element 11 and the second light emitting element 12 are composed of, for example, LEDs, and emit light toward the smoke detection space 2a. The first light emitting element 11 and the second light emitting element 12 are controlled by the control unit 20 so as to emit light alternately. Both the first light emitting element 11 and the second light emitting element 12 emit red light (for example, a wavelength of 655 nm) in the visible light region toward the smoke detection space 2a. The first light emitting element 11 and the second light emitting element 12 are not limited to those that emit red light having a wavelength of 655 nm, and may emit light having a peak wavelength in the wavelength range of 600 nm to 700 nm. ..

The light receiving element 13 is composed of, for example, a photodiode, and receives scattered light from smoke generated by the light of the first light emitting element 11 and the second light emitting element 12. The light receiving element 13 is located at a position where the first angle θ1 with respect to the optical axis of the first light emitting element 11 is an acute angle (for example, 60 °), and the second angle θ2 with respect to the optical axis of the second light emitting element 12 is an obtuse angle (for example, 110 °). ). Further, the light receiving element 13 is provided at a position where the light emitted by the first light emitting element 11 and the second light emitting element 12 is not directly incident. Therefore, the light receiving element 13 alternately receives the forward scattered light of smoke generated by the light of the first light emitting element 11 and the backscattered light of smoke generated by the light of the second light emitting element 12. The first angle θ1 may be an acute angle, and is more preferably selected from an angle range of 50 degrees to 70 degrees. Further, the second angle θ2 may be an obtuse angle, and more preferably, it is appropriately selected from an angle range of 100 degrees to 120 degrees. Then, the light receiving element 13 outputs the amount of light received from the smoke generated by the light of the first light emitting element 11 as the first output signal S1, and the scattered light from the smoke generated by the light of the second light emitting element 12. Is output as the second output signal S2.

The control unit 20 of FIG. 2 uses the first output signal S1 and the second output signal S2 output from the light receiving element 13 to determine whether or not there is a fire, and the signal correction unit 21 and the fire determination unit 22 , A storage unit 23, and a transmission unit 24. The signal correction unit 21 calculates the output ratio R (= first output signal S1 / second output signal S2) of the first output signal S1 and the second output signal S2, and the first is based on the calculated output ratio R. The output signal S1 is corrected. Here, the storage unit 23 stores a correction table showing the relationship between the output ratio R and the correction coefficient Cf, and the signal correction unit 21 acquires the correction coefficient Cf from the output ratio R with reference to the correction table. Then, the first output signal S1 is corrected using the acquired correction coefficient Cf, and the corrected first output signal SC1 is generated.

The fire determination unit 22 determines a fire using the corrected first output signal SC1. The storage unit 23 stores, for example, a threshold value for fire determination corresponding to a dimming rate of 10% / m by a CS meter (dimming rate meter). Then, the fire determination unit 22 determines that a fire has occurred when the corrected first output signal SC1 is larger than the threshold value, and the transmission unit 24 transmits the fire signal to the fire receiver.

It should be noted that the transmission unit 24 may transmit the corrected smoke concentration as an analog value instead of the fire signal. In that case, the fire receiver that receives the analog value determines the fire. Further, as described above, the control unit 20 is not limited to the case where the first light emitting element 11 and the second light emitting element 12 are constantly made to emit light alternately to acquire the output ratio R. For example, the control unit 20 constantly causes the first light emitting element 11 to emit light, and monitors whether or not the amount of light received by the light receiving element 13 exceeds a set value smaller than the threshold value for fire determination. The set value is stored in the storage unit 23. Then, when the light receiving amount exceeds the set value, the control unit 20 may cause the first light emitting element 11 and the second light emitting element 12 to alternately emit light to acquire the output ratio R.

Here, when a fire breaks out, not only one type of smoke is generated, but various types of smoke such as white smoke, gray smoke, and black smoke are generated depending on the combustibles. The smoke detector 1 needs to detect and issue a fire regardless of any of these various types of smoke. On the other hand, the sensitivity to the type of smoke differs depending on the wavelengths of the first light emitting element 11 and the second light emitting element 12, the first angle θ1 and the second angle θ2, and the output ratio R also becomes a value according to the type of smoke. Therefore, it is necessary to set the wavelength, the first angle θ1 and the second angle θ2, and the correction coefficient Cf according to the type of smoke so that a fire can be detected regardless of the type of smoke generated. Therefore, an experiment was conducted using filter paper smoky smoke (white smoke), cotton wick smoky smoke (gray smoke intermediate between white smoke and black smoke), and kerosin burning smoke (black smoke). , The conditions of the wavelength, the first angle θ1 and the second angle θ2, and the correction coefficient Cf were verified as follows.

Table 1 below shows the output when the light emitting element and the light receiving element are installed in the atmosphere of various smokes with a dimming rate of 10% / m by a CS meter and the wavelength and the scattering angle are changed. The smoke is filter paper smoke (white smoke), cotton wick smoke (intermediate smoke between white smoke and black smoke), and kerosine combustion smoke (black smoke). ) And. Further, the relative value of the output in the case of the smoke of the cotton wick or the output in the case of the combustion smoke of kerosene when the output in the case of the smoke of the filter paper was set to 1 was calculated as the relative sensitivity. Then, the relative sensitivities of light having three kinds of wavelengths of 465 nm (blue light), 655 nm (red light) and 940 nm (near infrared light) were measured while changing the scattering angle.

In Table 1, when blue light, red light, and near-infrared light are compared, blue light is more sensitive to black smoke (kerosin) than red light and near-infrared light. Also, blue light is more sensitive to cotton wick smoke (gray smoke) than filter paper smoke (white smoke). Red light has similar sensitivity to filter paper and cotton wick. Also, red light is less sensitive to black smoke than blue light and higher than near infrared light. It can be seen that near-infrared light has the lowest sensitivity to black smoke and also has the lowest sensitivity to cotton wicks.

Table 2 below shows the output ratio R (= S2 / S1) of the first output signal S1 and the second output signal measured while changing the wavelength and scattering angle of the smoke (gray smoke) of the cotton wick. ) Is shown.

Table 3 below shows the output ratio R (= S2 / S1) of the first output signal S1 and the second output signal measured while changing the wavelength and the scattering angle of kerosene smoke (black smoke). ..

As can be seen from Table 1, the output ratio R of the smoke (white smoke) of the filter paper is 1. As can be seen from Tables 1 to 3, when the near-infrared light is arranged at an acute angle and the blue light is arranged at an acute angle (940 nm: 60 ° to 80 ° forward scattered light and 465 nm: 90 in Tables 2 and 3). (In the case of a combination of backscattered light from ° to 120 °), the output ratio R of white smoke is 1, whereas the output ratio R of black smoke in Table 3 is larger than 2, so white smoke and black smoke The determination can be made. However, the output ratio R of the cotton wick smoke (gray smoke) in Table 2 is about the same as that of graphite, and it becomes difficult to distinguish between gray smoke and black smoke. Since the first output signal due to the forward scattered light of near-infrared light differs greatly between gray smoke and black smoke, it is necessary to correct the signal using the correction coefficient Cf, so it is possible to distinguish between gray smoke and black smoke. is necessary.

When the red light is arranged at an acute angle and the blue light is arranged at an acute angle (the combination of the forward scattered light of 655 nm: 60 ° to 80 ° and the backscattered light of 465 nm: 90 ° to 120 ° in Tables 2 and 3). Case), since the output ratio R of white smoke is 1, while the output ratio R of black smoke in Table 3 is larger than 2, it is possible to distinguish between white smoke and black smoke. Further, the output ratio R of the cotton wick smoke in Table 2 is also a value between white smoke and black smoke, and any of white smoke, gray smoke and black smoke can be discriminated.

When red light is arranged at both acute and obtuse angles (in the case of a combination of forward scattered light of 655 nm: 60 ° to 80 ° in Tables 2 and 3 and backscattered light of 655 nm: 90 ° to 120 °), white While the output ratio R of smoke is 1, the output ratio R of black smoke in Table 3 is larger than 1 and smaller than 2, so that white smoke and black smoke can be discriminated from each other. On the other hand, the output ratio R is almost 1 with respect to the smoke of the cotton wick in Table 2, and it is difficult to distinguish it from the smoke of the filter paper based on the output ratio. However, since the first output signal due to the forward scattered light of red light is as large as the smoke of filter paper and the smoke of cotton wick, it is not necessary to identify the type of smoke and set the correction coefficient. It is possible to discriminate a fire. That is, when the red light is arranged at both acute and obtuse angles, it suffices to distinguish between white smoke and gray smoke and black smoke.

When near-infrared light is arranged at both acute and obtuse angles (in the case of a combination of forward scattered light of 940 nm: 60 ° to 80 ° and backscattered light of 940 nm: 90 ° to 120 ° in Tables 2 and 3) Since the output ratio R of white smoke is 1, while the output ratio R of black smoke in Table 3 is larger than 1 and smaller than 2, it is possible to distinguish between white smoke and black smoke. However, the output ratio R is almost 1 with respect to the smoke of the cotton wick in Table 2, and it is difficult to distinguish it from the smoke of the filter paper by the output ratio R. However, in the case of near-infrared light, since the sensitivity (output value) of the cotton wick to smoke is low, it is necessary to distinguish it from filter paper smoke and correct it with the correction coefficient Cf. Unable to identify smoke.

From Tables 1 to 3 above, two combinations can be considered as the combination of the wavelengths of the first light emitting element 11 and the second light emitting element 12. That is, as the first combination (red / red), both the first light emitting element 11 and the second light emitting element 12 emit red light (wavelength 655 nm) in the visible light region, and the first light emitting element 11 emits forward scattered light. It is conceivable that the second light emitting element 12 is arranged at a position where the back scattered light is generated. As a second combination (blue / red), the first light emitting element 11 is arranged at a position where red light (wavelength 655 nm) in the visible light region is emitted to generate forward scattered light, and the second light emitting element 12 is blue light (blue light (blue / red). It is conceivable to arrange the light at a position where it emits (wavelength 465 nm) and generates backward scattered light. Although the case where the wavelength of blue light is 465 nm is illustrated, any light having a peak wavelength in the wavelength range of 450 nm to 500 nm may be used.

Next, the setting of the correction coefficient Cf in consideration of each type of smoke will be described. FIG. 3 is a graph showing the relationship between the output ratio of the first combination (red / red) and the second combination (blue / red) and the frequency distribution for various types of smoke. In FIG. 3, the first combination (red / red) of the smoke from the filter paper (white smoke), the smoke from the cotton wick (gray smoke), and the smoke from the combustion of heptane / toluene (black smoke) The frequency distribution when the output ratio R is calculated by the second combination (blue / red) is shown. In the first combination (red / red), the output ratio R of the filter paper smoke (white smoke) and the cotton wick smoke (gray smoke) is close to 1.05 times, and that of heptane / toluene. The output ratio R of combustion smoke (black smoke) is close to 2.05 times. In the second combination (blue / red), the output ratio R of the filter paper smoke (white smoke) tends to be close to 0.95 times, and the output ratio of the cotton wick smoke (gray smoke). R is in the vicinity of 1.5 times, and the output ratio R of combustion smoke (black smoke) of heptane / toluene is in the vicinity of 2.25 times.

Here, as shown in Tables 1 to 3, the sensitivity to white smoke and gray smoke is higher than that of black smoke regardless of whether the light is red light or blue light. For example, when the black smoke is the combustion smoke of heptane / toluene, the relative sensitivity of the heptane / toluene to the combustion smoke (black smoke) is 1/5 to 1/4 of the relative sensitivity of the filter paper to the smoldering smoke (white smoke). become. Therefore, when correction is performed by the correction coefficient Cf, it is necessary to set the correction coefficient Cf in the case of black smoke to be large so that the first output signal S1 follows the measured value by the CS meter. ..

FIG. 4 is a graph showing an example of a correction table stored in the storage unit of FIG. In FIG. 4, the dotted line shows the correction table of the first combination (red / red), and the solid line shows the correction table of the second combination (blue / red). As shown in FIG. 4, the first region RR1 in which the correction coefficient Cf for the output ratio R is set to the first correction coefficient Cf1 (for example, 1) and the correction coefficient Cf for the output ratio R are larger than the first correction coefficient Cf1. 2 Correction coefficient Cf2 (for example, 4) is set between the second region RR2 and the first region RR1 and the second region RR2, and the first correction coefficient Cf1 to the second correction as the output ratio R increases. It has a transition region TR that changes to a coefficient Cf2.

The correction coefficient Cf of the transition region TR is set as, for example, the sigmoid function of the following equation (1). In the formula (1), the parameters a, b, c and d are predetermined constants.

In the first combination (red / red) and the second combination (blue / red), the range of the output ratio R of the transition region TR and the values of the parameters a, b, c, and d in the above equation (1). Is different. This is because the output ratio R when black smoke is detected differs between the first combination (red / red) and the second combination (blue / red) due to the difference in sensitivity depending on the wavelength. to cause. For example, the transition region TR of the first combination (red / red) is set in the range of the output ratio of 1.3 to 1.6, and the transition region TR of the second combination (blue / red) has an output ratio of 1. It is set in the range of .6 to 2.3.

Further, the case where the transition region TR is set by the sigmoid function of the equation (1) is illustrated, but the present invention is not limited to this. FIG. 5 is a graph showing another example of the correction table stored in the storage unit of FIG. As shown in FIG. 5, the linear function may be set so that the correction coefficient Cf increases in proportion to the output ratio R.

FIG. 6 is a graph in which the frequency distributions for the output ratios of various smokes are superimposed on the correction table in the first combination (red / red). FIG. 7 is a graph in which the frequency distributions for the output ratios of various smokes are superimposed on the correction table in the second combination (blue / red). As shown in FIGS. 6 and 7, a first correction coefficient Cf1 (for example, 1) is set for white smoke or gray smoke having a large first output signal S1. On the other hand, for black smoke, a second correction coefficient Cf2 (for example, 4) larger than the first correction coefficient Cf1 is set.

Then, the signal correction unit 21 of FIG. 2 corrects the first output signal S1 using the correction coefficient Cf, and calculates the corrected first output signal SC1. At this time, the signal correction unit 21 calculates the corrected first output signal SC1 by using, for example, the corrected first output signal SC1 = Cf × S1. The signal correction unit 21 may perform correction by the correction coefficient Cf when the first output signal S1 is larger than the set threshold value (for example, a value corresponding to 1.0% / m). This is because the output ratio R changes unstablely when the smoke concentration is low, and the correction coefficient Cf fluctuates unstable accordingly. Therefore, when the first output signal S1 is less than the set threshold value, correction is performed. This is to prevent adverse effects on the judgment of fire.

Below, when the first output signal S1 is corrected using the correction tables of FIGS. 4 to 7, the first combination (red / red) has more various combustibles than the second combination (blue / red). It will be described that the corrected first output signal SC1 can be made to follow the measured value by the CS meter to make a highly accurate fire determination.

FIG. 8 is a graph showing the smoke concentration when the filter paper is burnt and the time transition of the first output signal after correction. In the case of filter paper smoke (white smoke), the correction coefficient Cf is around 1 for both the first combination (red / red) and the second combination (blue / red), and the first output signal. S1 and the corrected first output signal SC1 have the same value. As shown in FIG. 8, it can be seen that the corrected first output signal SC1 substantially follows the smoke concentration measured by the CS meter.

FIG. 9 is a graph showing the smoke concentration when the heptane-toluene mixed fuel (black smoke) burns and the time change of the corrected first output signal. In FIG. 9, the value measured by the CS meter increases with the passage of time. On the other hand, the first output signal S1 before correction shows only a slight increase over time. On the other hand, the corrected first output signal SC1 becomes larger as the smoke concentration increases, almost the same as the value measured by the CS meter. In this way, in the first combination (red / red) and the second combination (blue / red), the sensitivity of the wavelength with respect to the type of smoke is corrected by the correction coefficient Cf, and the corrected first output signal SC1 is fired. It can be seen that the situation of is reflected accurately.

FIG. 10 is a graph showing the smoke concentration when the trash can containing resin, paper, etc. is burned and the time change of the corrected first output signal. When burning a trash can like this time, black smoke is generated when a fire breaks out, and black smoke and white smoke tend to be mixed with each other over time. As shown in FIG. 10, the value measured by the CS meter shows that the smoke concentration increases with the passage of time from the occurrence of the fire to the period in which black smoke is mainly generated (for example, 0 to 640 seconds). After that, when black smoke and white smoke start to mix, the smoke concentration shows almost flat. On the other hand, the first output signal S1 before correction shows only a slight increase over time. On the other hand, the first output signal SC1 corrected by the first combination (red / red) has a detection result of smoke concentration substantially the same as the value measured by the CS meter.

However, the first output signal SC1 corrected by the second combination (blue / red) does not follow the smoke concentration of the CS meter, and the fluctuation range becomes large. Specifically, although the first output signal S1 before correction is increasing, the first output signal SC1 after correction is decreasing. This is due to the following reasons. This is because red light is more sensitive to white smoke than blue light. In the state where white smoke is generated, blue light may fall below the threshold because it has low sensitivity to white smoke, but red light always exceeds the threshold because it has high sensitivity to white smoke. Since the blue light may fall below the threshold value, the fluctuation range of the first output signal SC1 after correction by the second combination (blue / red) becomes large.

FIG. 11 shows the first output signal after correction by the first combination (red / red) and the correction by the second combination (blue / red) for the smoke concentrations of various smoke types measured by the CS meter. It is a graph which plots the 1st output signal and the 1st output signal at the time of receiving the forward scattered light of near-infrared light, and shows the regression line. In FIG. 11, the closer the first output signal is to the straight line of the CS meter, the better the result. As can be seen from FIG. 11, the first output signal SC1 corrected by the first combination (red / red) is located near the line corresponding to the CS meter. It was found that the first output signal SC1 corrected by the second combination (blue / red) varies depending on the case where a result with good accuracy can be obtained and the case where a result with poor accuracy can be obtained. It was.

According to the above embodiment, by using the first combination (red / red) in which the first light emitting element 11 and the second light emitting element 12 are both red light, the smoke changes from white smoke to black smoke over time. It is possible to make a highly accurate fire judgment even for such smoke. Further, since the same LED or the like can be used for the first light emitting element 11 and the second light emitting element 12, the characteristics of the aged deterioration of the light emitting element become almost the same, and it is possible to suppress the deterioration of the accuracy of fire detection. it can.

Further, by correcting the sensitivity of the wavelength with respect to the type of smoke with the correction coefficient Cf, the corrected first output signal SC1 can accurately reflect the situation of fire. In particular, when a correction table in which the correction coefficient Cf is set according to the output ratio R as shown in FIGS. 4 to 7 is used, even if the type of smoke changes with the passage of time, CS is used before and after the change. It is possible to maintain the same sensitivity as the reference sensitivity set based on the measured value by the meter.

In the correction table of FIGS. 4 to 8, the case where the correction coefficient Cf is divided into the first region RR1, the transition region TR, and the second region RR2 according to the output ratio R is illustrated. The correction coefficient Cf is set so that it is determined from the output ratio R that scattered light is generated by particles other than the smoke of the above, and the fire judgment result by the corrected first output signal SC1 is surely determined to be non-fire. It may be set small.

FIG. 12 is a graph showing a modification of the correction table stored in the storage unit of FIG. 2, and FIG. 13 shows a frequency distribution with respect to the output ratio of various smokes in the correction table in the first combination (red / red). It is a graph in which. As shown in FIGS. 12 and 13, in the correction table, the non-fire correction coefficient Cf0 (for example, 0.5) in which the correction coefficient Cf is smaller than the first correction coefficient Cf1 in the region where the output ratio R is smaller than the first region RR1 The non-fire area RR0 set in) is set. Steam and the like have a larger particle size than white smoke, and on the contrary to black smoke, the output ratio R tends to be smaller than 1. Therefore, in the non-fire region RR0 where the frequency distribution of steam is large, the non-fire correction coefficient Cf0 is set. As a result, in the case of steam or the like, the corrected first output signal SC1 becomes smaller than the uncorrected first output signal S1, and the fire determination unit 22 determines that the fire is definitely non-fire, and the determination accuracy is improved. It can be improved.

The embodiment of the present invention is not limited to the above embodiment, and various modifications can be made. For example, a case where two first light emitting elements 11 and a second light emitting element 12 and one light receiving element 13 are provided is illustrated, but the first light emitting element 11 and the second light emitting element 12 include, for example, white light or the like. It may be composed of one light emitting element having a predetermined wavelength range of the above, and the light receiving element may be configured to receive scattered light of different wavelengths by an optical filter or the like.

1 Smoke detector, 2 Smoke detector, 2a Smoke detector space, 11 1st light emitting element, 12 2nd light emitting element, 13 Light receiving element, 20 Control unit, 21 Signal correction unit, 22 Fire judgment unit, 23 Storage unit, 24 Transmitter, Cf correction coefficient, Cf0 non-fire correction coefficient, Cf1 first correction coefficient, Cf2 second correction coefficient, R output ratio, RR0 non-fire area, RR1 first area, RR2 second area, TR transition area, S1 first 1 output signal, S2 2nd output signal, SC1 corrected first output signal, a, b, c, d parameters, θ1 first angle, θ2 second angle.

Claims (5)

The first light emitting element that emits red light in the visible light region toward the smoke detection space,
A second light emitting element that emits the same red light as the first light emitting element toward the smoke detection space, and
A light receiving element arranged at an acute angle with respect to the optical axis of the first light emitting element and at an obtuse angle with respect to the optical axis of the second light emitting element.
Control to determine a fire based on the first output signal received by the light receiving element by the light emission of the first light emitting element and the second output signal received by the light receiving element by the light emission of the second light emitting element. Department and
A smoke detector characterized by being equipped with. The control unit obtains a correction coefficient from the output ratio of the first output signal and the second output signal, corrects the first output signal using the obtained correction coefficient, and corrects the first output. The smoke detector according to claim 1, wherein a fire is determined using a signal. The control unit has a correction table showing the relationship between the output ratio and the correction coefficient.
In the correction table,
The first region in which the correction coefficient with respect to the output ratio is set as the first correction coefficient, and
A second region in which the correction coefficient with respect to the output ratio is set to a second correction coefficient larger than the first correction coefficient, and
The second aspect of the present invention, wherein a transition region is set between the first region and the second region and changes from the first correction coefficient to the second correction coefficient as the output ratio increases. Smoke detector. The smoke detector according to claim 3, wherein the correction coefficient in the transition region increases in proportion to the output ratio. Claim 3 or claim 3 or the correction table is set to a non-fire region in which the correction coefficient is set to a non-fire correction coefficient smaller than the first correction coefficient in a region having an output ratio smaller than that of the first region. 4. The smoke detector according to 4.

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