JP7166386B2 - Smoke detectors - Google Patents

Description

TECHNICAL FIELD The present invention relates to a smoke sensor that uses a plurality of light emitting elements to determine the type of smoke or the like.

2. Description of the Related Art Conventionally, a photoelectric smoke sensor is known that emits light from a light emitting element and receives scattered light generated from smoke particles by a light receiving element to detect smoke and fire. 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 sensor has been proposed that detects a scattered light intensity for each different wavelength and determines a fire while determining the type of smoke (see, for example, Patent Documents 1 to 3).

Patent Documents 1 and 2 disclose 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 the light from the first light emitting element and the second light emitting element. A photoelectric smoke detector is disclosed. Among them, 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). It discloses 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 the scattered light. It is Further, Patent Document 3 has one light projecting part that emits near-infrared light (wavelength 950 nm) and two light receiving parts, and the two light receiving parts are forward scattered light and back scattered light of smoke. A photoelectric smoke detector that receives light is disclosed.

Japanese Patent Application Laid-Open No. 2004-325211 Japanese Patent Application Laid-Open No. 2001-236575 JP-A-11-160238

However, when light-emitting elements that emit light of different wavelengths are used, as in Patent Document 1, the accuracy of fire detection decreases due to differences in characteristics of output changes due to temperature and deterioration over time of the light-emitting elements. It may deteriorate. Moreover, 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.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a smoke sensor capable of suppressing deterioration in accuracy of fire detection.

A smoke sensor according to the present invention includes a first light emitting element that emits light toward a smoke detection space, a second light emitting element that emits light having the same wavelength as the first light emitting element toward the smoke detection space, and a second light emitting element that emits light toward the smoke detection space. a light receiving element arranged at an acute angle with respect to the optical axis of one light emitting element and arranged at an obtuse angle with respect to the optical axis of the second light emitting element; a first output signal received by the light receiving element due to light emitted from the first light emitting element; A control unit that determines a fire based on a second output signal received by the light receiving element due to light emission of the second light emitting element , and the first light emitting element and the second light emitting element have a wavelength in the range of 600 nm to 700 nm. A light having a peak wavelength is emitted within .

Note that the control unit may correct the first output signal and use the corrected first output signal to determine whether there is a fire.

According to the smoke sensor of the present invention, the first light emitting element and the second light emitting element emit light having a peak wavelength within the wavelength range of 600 nm to 700 nm. Since the output change due to temperature and aging deterioration are almost the same, the deterioration of fire detection accuracy can be suppressed.

1 is a schematic diagram showing an embodiment of a smoke detector of a smoke sensor according to the present invention; FIG. 1 is a block diagram showing an embodiment of a smoke sensor according to the invention; FIG. 4 is a graph showing the relationship between the power ratio and the frequency distribution of the first combination (red/red) and the second combination (blue/red) for various types of smoke. FIG. 3 is a graph showing an example of a correction table stored in the storage unit of FIG. 2; FIG. FIG. 10 is a graph showing the relationship between the first combination (red/red) and second combination (blue/red) output ratios and frequency distributions for various smokes; FIG. FIG. 5 is a graph in which frequency distributions for various smoke output ratios are superimposed on the correction table for the first combination (red-red); FIG. 10 is a graph in which the frequency distribution for various smoke power ratios is superimposed on the correction table for the second combination (blue/red); It is a graph which shows time transition of the 1st output signal after smoke density|concentration and correction|amendment when filter paper is smoldered. FIG. 4 is a graph showing temporal changes in the smoke concentration and the corrected first output signal when heptane-toluene mixed fuel (black smoke) is burned; FIG. 4 is a graph showing temporal changes in smoke density and corrected first output signal when a trash can containing resin, paper, etc. is burned. 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 densities of various types of smoke measured by the CS meter. It is a graph which plots the 1st output signal at the time of receiving the forward scattered light of a signal and near-infrared light, and shows the regression line. 3 is a graph showing a modified example of the correction table stored in the storage unit of FIG. 2; FIG. 5 is a graph in which frequency distributions for various smoke output ratios are superimposed on the correction table for the first combination (red-red);

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

The first light emitting element 11 and the second light emitting element 12 are, 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 controller 20 so as to alternately emit light. Both the first light emitting element 11 and the second light emitting element 12 emit red light in the visible light region (for example, wavelength 655 nm) toward the smoke detection space 2a. Note that the first light emitting element 11 and the second light emitting element 12 are not limited to emitting red light with a wavelength of 655 nm, and may emit light having a peak wavelength within 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 the smoke generated by the light from 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 (eg 60°), and the second angle θ2 with respect to the optical axis of the second light emitting element 12 is an obtuse angle (eg 110°). ). Further, the light receiving element 13 is provided at a position where the light emitted from the first light emitting element 11 and the second light emitting element 12 does not directly enter. Therefore, the light receiving element 13 alternately receives the forward scattered light of smoke caused by the light of the first light emitting element 11 and the backward scattered light of smoke caused by the light of the second light emitting element 12 . It should be noted that the first angle θ1 may be an acute angle, and is more preferably selected appropriately from an angle range of 50 degrees to 70 degrees. Also, 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 scattered from the smoke caused by the light of the first light emitting element 11 as the first output signal S1, and the scattered light from the smoke caused by the light of the second light emitting element 12 is output as the first output signal S1. is output as the second output signal S2.

The control unit 20 in FIG. 2 determines whether or not there is a fire using the first output signal S1 and the second output signal S2 output from the light receiving element 13. 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 an output ratio R (=first output signal S1/second output signal S2) between the first output signal S1 and the second output signal S2, and calculates the first output signal based on the calculated output ratio R. Correct the output signal S1. 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 refers to the correction table to acquire the correction coefficient Cf from the output ratio R. Then, the acquired correction coefficient Cf is used to correct the first output signal S1 to generate the corrected first output signal SC1.

The fire determination unit 22 performs fire determination using the corrected first output signal SC1. The storage unit 23 stores, for example, a threshold value for fire judgment corresponding to a light attenuation rate of 10%/m by a CS meter (light attenuation 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, and the transmission unit 24 transmits a fire signal to the fire receiver.

It should be noted that instead of the fire signal being transmitted from the transmitting unit 24, the corrected smoke density may be transmitted as an analog value. In that case, the fire receiver that receives the analog value determines the fire. Further, the control unit 20 is not limited to always obtaining the output ratio R by alternately causing the first light emitting element 11 and the second light emitting element 12 to emit light as described above. For example, the control unit 20 always 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 fire determination threshold. The setting values are stored in the storage unit 23 . Then, the control unit 20 may obtain the output ratio R by alternately causing the first light emitting element 11 and the second light emitting element 12 to emit light when the amount of light received exceeds the set value.

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, black smoke, etc., are generated depending on what is burned. The smoke sensor 1 is required to detect a fire and give an alarm when any of these various types of smoke are generated. On the other hand, 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 have different sensitivities to the type of smoke, and the output ratio R also has a value corresponding to the type of smoke. Therefore, it is necessary to set the wavelength, the first angle θ1, 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 smoke (white smoke), cotton lamp wick smoke (gray smoke between white and black smoke), and kerosene combustion 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 various smoke atmospheres with a light attenuation rate of 10%/m by a CS meter, and the wavelength and scattering angle are changed. The smoke consists of filter paper smoke (white smoke), cotton lamp wick smoke (intermediate smoke between white smoke and black smoke), and smoke similar to kerosene combustion smoke (black smoke). ) and In addition, relative sensitivity was calculated as the relative value of the output of cotton lamp wick smoke or kerosene combustion smoke when the output of filter paper smoke was set to 1. Then, the relative sensitivity was measured while changing the scattering angle for light with three wavelengths of 465 nm (blue light), 655 nm (red light) and 940 nm (near-infrared light).

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

Table 2 below shows the output ratio R (= S2/S1 ).

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

As can be seen from Table 1, the output ratio R is 1 for the smoke (white smoke) from the smoldering of the filter paper. 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 obtuse angle (940 nm in Tables 2 and 3: 60 ° to 80 ° forward scattered light and 465 nm: 90 ° ~ 120 °), the output ratio R of white smoke is 1, whereas the output ratio R of black smoke in Table 3 is greater than 2. Judgment can be made. However, regarding the smoke (gray smoke) of the cotton lamp wick in Table 2, the output ratio R is about the same as that of graphite, making it difficult to distinguish between gray smoke and black smoke. Since the first output signal due to 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 difficult to distinguish between gray smoke and black smoke. is necessary.

When red light is arranged at an acute angle and blue light is arranged at an obtuse angle (655 nm in Tables 2 and 3: 60 ° to 80 ° forward scattered light and 465 nm: combination of 90 ° to 120 ° back scattered light case), while the output ratio R of white smoke is 1, the output ratio R of black smoke in Table 3 is greater than 2, so white smoke and black smoke can be discriminated. Also, regarding the smoke of the cotton lamp wick in Table 2, the output ratio R is a value between the white smoke and the black smoke, and it is possible to distinguish between the white smoke, the gray smoke and the black smoke.

When red light is placed at both acute and obtuse angles (655 nm: combination of 60°-80° forward scattered light and 655 nm: 90°-120° backscattered light in Tables 2 and 3), white While the output ratio R of smoke is 1, the output ratio R of black smoke in Table 3 is greater than 1 and less than 2, so white smoke and black smoke can be discriminated. On the other hand, the output ratio R for the smoke from the cotton lamp wick in Table 2 is approximately 1, making it difficult to distinguish the smoke from the filter paper based on the output ratio. However, since the first output signal due to forward scattered red light is about the same in the case of smoke from the filter paper and the smoke from the cotton lamp wick, even if the type of smoke is not identified and the correction coefficient is set, Fire discrimination can be performed. That is, when the red light is arranged at both an acute angle and an obtuse angle, it is sufficient to be able to distinguish between white smoke, gray smoke, and black smoke.

When the near-infrared light is arranged at both acute and obtuse angles (940 nm in Tables 2 and 3: 60° to 80° forward scattered light and 940 nm: 90° to 120° backward scattered light) , the output ratio R of white smoke is 1, whereas the output ratio R of black smoke in Table 3 is greater than 1 and less than 2, so white smoke and black smoke can be discriminated. However, the output ratio R for the smoke from the cotton lamp wick in Table 2 is approximately 1, making it difficult to distinguish the smoke from the filter paper by the output ratio R. However, in the case of near-infrared light, since the sensitivity (output value) to the smoke of the cotton lamp wick is low, it is necessary to distinguish it from the smoke of the filter paper and correct it with the correction coefficient Cf. Smoke cannot be identified.

From Tables 1 to 3 above, two combinations of wavelengths of the first light emitting element 11 and the second light emitting element 12 can be considered. That is, as a 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. is generated and the second light emitting element 12 is arranged at a position where it generates backscattered light. As a second combination (blue and red), the first light emitting element 11 is arranged at a position where it emits red light (wavelength: 655 nm) in the visible light region to generate forward scattered light, and the second light emitting element 12 emits blue light ( (wavelength 465 nm) can be considered to be placed at a position to generate backscattered light. Although a case where the wavelength of the blue light is 465 nm is exemplified, any light having a peak wavelength within the wavelength range of 450 nm to 500 nm may be used.

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

Here, as shown in Tables 1 to 3, the sensitivity to white smoke and gray smoke is higher than that to black smoke regardless of whether it is red light or blue light. For example, when the black smoke is heptane/toluene combustion smoke, the relative sensitivity to heptane/toluene combustion smoke (black smoke) is 1/5 to 1/4 of the relative sensitivity of filter paper to smoke (white smoke). become. Therefore, when the correction by the correction coefficient Cf is performed, 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 the correction table stored in the storage section of FIG. In FIG. 4, the dotted line indicates the correction table for the first combination (red/red), and the solid line indicates the correction table for the second combination (blue/red). As shown in FIG. 4, a first region RR1 in which the correction coefficient Cf for the output ratio R is set to a first correction coefficient Cf1 (for example, 1), and a second region RR1 in which the correction coefficient Cf for the output ratio R is larger than the first correction coefficient Cf1. A second region RR2 set to 2 correction coefficients Cf2 (for example, 4) and a second region RR2 set between the first region RR1 and the second region RR2. and a transition region TR that changes to a coefficient Cf2.

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

In addition, 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 formula (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 to have an output ratio in the range of 1.3 to 1.6, and the transition region TR of the second combination (blue/red) has an output ratio of 1. .6 to 2.3.

Also, the case where the transition region TR is set by the sigmoid function of formula (1) is exemplified, 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 section of FIG. As shown in FIG. 5, a linear function may be set such that the correction coefficient Cf increases in proportion to the output ratio R.

FIG. 6 is a graph in which frequency distributions for various smoke output ratios are superimposed on the correction table for the first combination (red/red). FIG. 7 is a graph in which frequency distributions for various smoke output ratios are superimposed on the correction table for 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 with 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 in 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 using, for example, the corrected first output signal SC1=Cf×S1. Note that the signal corrector 21 may perform correction using the correction coefficient Cf when the first output signal S1 is larger than a set threshold value (for example, a value corresponding to 1.0%/m). This is because when the smoke density is low, the output ratio R changes unstably, and the correction coefficient Cf unstably fluctuates accordingly. This is to prevent the judgment of fire from being adversely affected.

Below, when the first output signal S1 is corrected using the correction tables of FIGS. , the corrected first output signal SC1 is made to follow the measured value by the CS meter, and highly accurate fire determination can be performed.

FIG. 8 is a graph showing temporal transitions of the smoke density and the corrected first output signal when the filter paper is smoldered. In the case of filter paper smoke (white smoke), both the first combination (red/red) and the second combination (blue/red) have a correction coefficient Cf near 1, 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 density measured by the CS meter.

FIG. 9 is a graph showing temporal changes in smoke density and corrected first output signal when heptane-toluene mixed fuel (black smoke) is burned. In FIG. 9, the measured value by the CS meter increases with time. In contrast, the first output signal S1 before correction shows only a slight increase over time. On the other hand, the corrected first output signal SC1 increases as the smoke density increases, almost like the value measured by the CS meter. Thus, in the first combination (red/red) and the second combination (blue/red), the sensitivity of the wavelength to the type of smoke is corrected by the correction coefficient Cf, and the first output signal SC1 after correction is fire. It can be seen that the state of

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

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

FIG. 11 shows the first output signal after correction by the first combination (red/red) and after correction by the second combination (blue/red) for smoke densities of various types of smoke measured by the CS meter. 1 is a graph plotting the first output signal of and the first output signal when forward scattered light of near-infrared light is received, and showing a regression line thereof. In FIG. 11, it means that 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 after correction by the first combination (red/red) is positioned near the line that coincides with the CS meter. It should be noted that the first output signal SC1 after correction by the second combination (blue and red) has a case where a result with good accuracy is obtained and a case where a result with bad accuracy is obtained. rice field.

According to the above embodiment, the first combination (red/red) in which both the first light emitting element 11 and the second light emitting element 12 emit red light changes from white smoke to black smoke over time. It is possible to perform highly accurate determination of fire even for such smoke. In addition, 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 aging deterioration characteristics of the light emitting elements become substantially the same, and deterioration in fire detection accuracy can be suppressed. can.

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

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 due to particles other than smoke has occurred, and that the fire determination result based on the corrected first output signal SC1 is reliably determined to be non-fire. You may make it set small.

FIG. 12 is a graph showing a modified example of the correction table stored in the storage unit of FIG. is a superimposed graph. As shown in FIGS. 12 and 13, the correction table contains a non-fire correction coefficient Cf0 (for example, 0.5 ) is set as the non-fire area RR0. Steam and the like have a larger particle diameter than white smoke and tend to have an output ratio R smaller than 1, contrary to black smoke. Therefore, the non-fire correction coefficient Cf0 is set in the non-fire region RR0 where the steam frequency distribution is large. 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 judgment unit 22 reliably judges that there is no fire, thus increasing the judgment accuracy. can be improved.

Embodiments of the present invention are not limited to the above embodiments, and various modifications can be made. For example, the case of having two first light emitting elements 11 and second light emitting elements 12 and one light receiving element 13 is illustrated, but the first light emitting element 11 and the second light emitting element 12 emit white light, for example. , and the light-receiving element may receive scattered light of different wavelengths by means of an optical filter or the like.

1 smoke detector, 2 smoke detection unit, 2a smoke detection space, 11 first light emitting element, 12 second light emitting element, 13 light receiving element, 20 control unit, 21 signal correction unit, 22 fire determination 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 region, RR1 first region, RR2 second region, TR transition region, S1 second 1 output signal, S2 second output signal, SC1 corrected first output signal, a, b, c, d parameters, θ1 first angle, θ2 second angle.

Claims (2)

a first light emitting element that emits light toward the smoke detection space;
a second light emitting element that emits light having the same wavelength as that of the first light emitting element toward the smoke detection space;
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 for determining a fire based on a first output signal received by the light receiving element due to light emission of the first light emitting element and a second output signal received by the light receiving element due to light emission of the second light emitting element Department and
with
The first light emitting element and the second light emitting element emit light having a peak wavelength within a wavelength range of 600 nm to 700 nm.
A smoke detector characterized by : 2. The smoke sensor according to claim 1, wherein the control unit corrects the first output signal, and uses the corrected first output signal to determine whether there is a fire.

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