JPH06109631A - Fire alarm - Google Patents

Abstract

(57) [Summary] [Purpose] It is an object to provide a fire alarm device that performs accurate fire detection according to the type of smoke to be detected. [Structure] The smoke detection space is irradiated with light of two types of wavelengths, and the type of smoke is determined based on the ratio of the light intensities of the scattered light of the respective wavelengths when the smoke invades. The smoke detection space is irradiated with light of wavelengths, and it is detected from the scattered light when smoke enters through the optical filter of the light of two specific wavelengths, based on the ratio of the light intensity of the light of each wavelength. Determine the type of smoke,
Further, the presence or absence of a fire is determined by further comparing the light intensity of these with a threshold value set according to the determined type of smoke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire alarm device for detecting the presence or absence of a fire and the type of smoke from scattered light due to smoke during a fire.

[0002]

2. Description of the Related Art A scattered light type smoke detector is known as a device for judging a fire from scattered light caused by smoke during a fire. As shown in FIG. 7, with respect to the light emitting element 2 such as a light emitting diode that emits directional light toward the center X of the smoke detection chamber (smoke detection space), and the optical axis of the light emitting element 2. A light receiving lens 4 and a light receiving element 6 such as a photodiode whose optical axes are aligned at a predetermined angle (hereinafter, referred to as a scattering angle) θ, and a signal output from the light receiving element 6 that is larger than a predetermined threshold indicates that a fire has occurred. A comparator 8 for outputting the detection signal So is provided.

The principle that there is a correlation between the scattered light incident on the light-receiving element 6 and the smoke concentration in the smoke detection space, that is, the smoke detection chamber 1 smoke 1 during normal times when no fire occurs
Since 0 does not enter, the intensity of the scattered light reaching the light receiving element 6 is small, while the intensity of the scattered light reaching the light receiving element 6 increases when the smoke 10 enters due to fire. The presence or absence of fire is detected by setting the threshold value of 8.

[0004]

Such a conventional scattered light type smoke detector does not have a function of judging the type of smoke, but simply has a uniform concentration of smoke that has entered the smoke detection space. It only determines the presence of a fire by comparing it to a threshold level. However, in reality, smoke generated by combustion of gasoline and the like and smoke generated by combustion of wood have different colors and particle diameters. Also causes a phenomenon in which the intensity of scattered light detected by the light receiving element is different. From this,
To make a fire judgment based on a uniform threshold level regardless of the type of smoke is to judge non-fire as a fire,
There were problems such as delaying fire judgment.

In general, such a fact is empirically found that, for example, a scattered light type smoke detector installed in a room filled with cigarette smoke malfunctions with cigarette smoke even though it is not a fire. Are known. Further, there is a problem that the intensity of scattered light becomes small with respect to the black smoke generated by the combustion of gasoline or the like, and the fire judgment is delayed. The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a fire alarm device that performs accurate fire detection according to the type of smoke to be detected.

[0006]

In order to achieve such an object, the present invention irradiates the smoke detection space with light of two kinds of wavelengths, and scatters light of each wavelength when smoke enters. The type of smoke is determined based on the ratio of the light intensity of light, and the presence or absence of a fire is determined by further comparing the light intensity with a threshold value set according to the determined type of smoke. It was decided to.

Further, the smoke detection space is irradiated with light of a plurality of wavelengths,
Light of two specific wavelengths is detected from the scattered light when smoke enters through an optical filter, and the type of smoke is determined based on the light intensity ratio of the light of each wavelength. Whether or not there is a fire is determined by further comparing the received light intensity of these with the threshold value set according to the type of smoke.

[0008]

According to the fire alarm device of the present invention having such a configuration, since there is a unique correlation between the ratio of the light intensity of scattered light having different wavelengths and the type of smoke, the type of smoke can be determined. can do. In addition, a threshold value for determining the presence or absence of a fire is set according to the determined smoke type, and the presence or absence of a fire is finally determined by comparing this threshold value with the magnitude relationship of the light intensity of scattered light. Therefore, it is possible to improve the accuracy of judgment and prevent false fire alarms, as compared with the case of judging the presence or absence of a fire with a uniform threshold value regardless of the type of smoke as in the related art.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a scattered light type fire detector will be described below with reference to the drawings. First, the structure will be described with reference to FIG. 1. Reference numeral 12 is a light emitting element that irradiates the central portion X of the smoke detection space with directional light, and a halogen lamp or the like that emits light having a plurality of wavelength components is used. Has been applied.

Reference numeral 14 denotes a first light receiving element such as a photodiode, which is provided so that its light receiving axis has a predetermined scattering angle θ1 with respect to the optical axis direction of the light emitting element 12. 1
Reference numeral 6 denotes a first optical filter that transmits only light having a predetermined wavelength λ1 and is provided in front of the light receiving surface of the first light receiving element 14. Reference numeral 18 denotes a second light receiving element such as a photodiode, which is provided so that its light receiving axis has a predetermined scattering angle θ2 with respect to the optical axis direction of the light emitting element 12.

Reference numeral 20 denotes a second optical filter which transmits only light having a predetermined wavelength λ2 and is provided in front of the light receiving surface of the second light receiving element 18. In this embodiment, the scattering angles θ1 and θ2 of the first light receiving element 14 and the second light receiving element 18 are both set to be equal to 30 °, and the transmission wavelength λ1 of the first optical filter 16 is set to 0. 5 μm, and the transmission wavelength λ2 of the second optical filter 20 is set to 0.9 μm. It goes without saying that the scattering angles θ1 and θ2 and the transmission wavelengths λ1 and λ2 can be set appropriately.

Reference numeral 22 denotes an arithmetic unit, which inputs the output signals S1 and S2 of the first and second light receiving elements 14 and 18 and calculates a ratio S1 / S2 of these output levels. Reference numeral 24 denotes a determination unit that compares the output level ratio β (= S1 / S2) with a threshold value Tth for determining the type of smoke, and determines the type of smoke according to the magnitude relationship between the ratio β and the threshold value Tth. To judge. Further, a threshold value Tv for detecting fire is set for each type of smoke, and the output levels of the output signals S1 and S2 of the first and second light receiving elements 14 and 18 exceed the threshold value Tv. When this is detected, it is determined that a fire has occurred, and the fire alarm signal So is output. That is, the threshold value Tth is set to determine the type of smoke, and the threshold value Tv is a unique threshold value according to the type of smoke determined based on the threshold value Tth. It enables fire detection according to the type of.

Reference numeral 26 is a reference data storage unit for pre-storing data for the judgment unit 24 to use as a basis for a fire occurrence condition. The type of combustible material in the monitoring area in which the scattered light smoke detector of this embodiment is installed. And data of a plurality of threshold values Tth and Tv corresponding to the set angles of the scattering angles θ1 and θ2 of the first and second light receiving elements 14 and 18 are stored.

Although not shown in the figure, when the data of the combustible material and the scattering angles θ1 and θ2 of the first and second light receiving elements 14 and 18 are initialized by an initial setting switch or the like, thereafter, the respective data is set. Unique thresholds Tth and T
v is supplied to the judgment unit 24, and the judgment unit 24 judges the type of smoke and the presence / absence of fire based on these threshold values Tth and Tv.

As described above, by providing the reference data storage unit 26, it is possible to cope with various fires that are expected in advance in accordance with the situation in the monitored area. Next, the operation of the embodiment having such a configuration will be described together with the principle of fire detection. First, the fire detection principle applied to this embodiment will be described. As a result of many experiments and studies, the inventor of the present application has found that the smoke concentration in the smoke detection chamber of the scattered light type smoke sensor is determined by the difference in the scattering angle θ formed by the optical axes of the light emitting element and the light receiving element and the transmission wavelength λ of the optical filter. It is confirmed that the received light intensity received by the light receiving element is different even if the value is constant, and that such a correlation between the scattering angle θ, the transmitted wavelength λ, and the received light intensity has unique characteristics for each type of smoke. did.

FIG. 2 shows an example of the result of such an experiment. However, the horizontal axis represents the scattering angle θ, and the vertical axis represents the received light intensity received by the light receiving element when the smoke detection space is filled with smoke of a predetermined concentration (1.0% / m). Ratio with (below,
(Referred to as scattering efficiency), and the vertical axis is logarithmic.
Characteristic curves a, b, and c are measurement results of smoke due to kerosene (liquid fire), and characteristic curve a is a scattering efficiency and characteristic curve when an optical filter having a transmission wavelength λ1 = 0.5 μm is applied. b shows the scattering efficiency when the optical filter having the transmission wavelength λ2 = 0.9 μm is applied, and the characteristic curve c shows the scattering efficiency when the optical filter having the transmission wavelength λ3 = 1.3 μm is applied. Characteristic curves d, e, and f are measurement results of smoke from a cotton wick (smoke fire), and characteristic curve d is a scattering efficiency and characteristic curve when an optical filter with a transmission wavelength λ1 = 0.5 μm is applied. e is the transmission wavelength λ2 =
Scattering efficiency when applying a 0.9 μm optical filter,
A characteristic curve f shows the scattering efficiency when an optical filter having a transmission wavelength λ3 = 1.3 μm is applied.

As is clear from FIG. 2, for each type of smoke,
It can be seen that the scattering efficiency I has an inherent correlation between the scattering angle θ and the transmission wavelength λ. Therefore, the inventor of the present application, for each type of smoke, the ratio β (= I1 / I) between the scattering efficiency I1 at the transmission wavelength λ1 and the scattering efficiency I2 at the transmission wavelength λ2.
2) was obtained, and the type of smoke was determined from the value of this ratio β.

The table of FIG. 3 shows the scattering angle θ = 150 for each of the liquid fire and the smoldering fire based on the characteristic curve of FIG.
This is an experimental example in which the ratio β of the scattering efficiency when the transmission wavelength λ1 = 0.5 μm and λ2 = 0.9 μm was obtained. The ratio β1 for liquid fire was about 3.8, and the ratio β2 for smoldering fire was about 2.1, these ratios β1 and β2 represent the unique characteristics of each smoke.

Therefore, for example, the threshold value Tth is set to 3.
It is set to 0, and the type of smoke is determined by detecting the magnitude relationship between the ratio β and this threshold value Tth. The photoelectric conversion output S1 of the first light receiving element 14 and the second
Since the ratio of the photoelectric conversion output S2 of the light receiving element 18 is equivalent to the scattering efficiency ratio β, the ratio of the outputs S1 and S2 of the first and second light receiving elements 14 and 18 is applied in this embodiment. is doing.

Next, the operation will be described. First, when the sensor is installed, the type of combustible material provided in the monitored area and the scattering angle θ are initialized to specify the type of smoke that will be generated during a fire. Light having a plurality of wavelengths λ1 = 0.5 μm and λ2 = 0.9 μm is emitted from the light emitting element 12, and the calculation unit 22 outputs the photoelectric conversion signal S1 output from the first light receiving element 14 and the second light receiving element 18. And a ratio β of S2 (= S1 / S2) are calculated for each predetermined period τ.

The determination unit 24 compares the ratio β with the threshold value Tth in synchronization with the period τ. Also, the ratio β is the threshold value Tth
If it is larger, the first threshold value Tv1 for detecting smoke due to liquid fire is automatically read from the reference data storage unit 26. Conversely, if the ratio β is smaller than the threshold value Tth, The second threshold value Tv2 for detecting smoke due to a smoldering fire is automatically read from the reference data storage unit 26 to set the threshold value Tv according to a liquid fire or a smoldering fire.

When the threshold value Tv1 is set, the photoelectric conversion output S of the first and second light receiving elements 14 and 18 is obtained.
When the output levels of 1 and S2 exceed the threshold Tv1, it is judged that there is a liquid fire and the fire alarm signal So is output. When it does not exceed the threshold Tv1, it is judged that there is no fire. Then, the monitoring operation is continued without outputting the fire alarm signal So. Also, when the threshold Tv2 is set,
Photoelectric conversion outputs S1 of the first and second light receiving elements 14 and 18
When the output level of S2 exceeds the threshold Tv2, it is determined that it is a smoldering fire, and the fire alarm signal So is output. When it does not exceed the threshold Tv2, it is determined that it is not a fire. The monitoring operation is continued without outputting the fire alarm signal So.

As described above, according to this embodiment, the type of smoke caused by a fire is determined, and the presence or absence of a fire is determined based on a specific threshold value Tv for each type of smoke. Enable notification. In this embodiment, the calculation unit 22, the judgment unit 24, and the reference data storage unit 26 are incorporated in the scattered light smoke detector, but the light emitting element 12, the first and second light receiving elements 14, 18 and the optical filter 16,
Only the optical system of 20 is built into the scattered light type smoke sensor, and a calculation unit 22, a judgment unit 24, and a reference data storage unit 26 for performing calculation and judgment based on the photoelectric conversion outputs S1 and S2, a so-called receiver or You may make it provide in a repeater.

Next, another embodiment will be described with reference to FIG.
In FIG. 4, the same or corresponding parts as in FIG. 1 are designated by the same reference numerals. The difference from the first embodiment will be described. Instead of the optical filters provided on the light receiving surfaces of the respective light receiving elements 14 and 18, an optical filter 28 that rotates at a predetermined angular velocity is provided on the output side of the light emitting element 12. ing. This optical filter 28 has λ1 = 0.5 μ when the rotation angle is 0 ° to 180 °.
m, when the rotation angle is 180 ° to 360 °, λ2 = 0.9
It has a structure in which two types of filters that transmit μm light are integrally combined, and is rotationally driven by a constant speed rotation motor 30 that is driven to rotate in synchronization with a synchronization signal from the timing control unit 32.

Therefore, when the rotation angle is 0 ° to 180 °, the smoke detection space is irradiated with light of λ1 = 0.5 μm, and 180 °
When the rotation angle is ˜360 °, the smoke detection space is irradiated with light of λ2 = 0.9 μm. Further, the calculation unit 22 synchronizes with the synchronization signal from the timing control unit 32, and 0 ° to
The photoelectric conversion output S1 of the first light receiving element 14 is input at a rotation angle of 180 °, and the photoelectric conversion output S2 of the second light receiving element 18 is input at a rotation angle of 180 ° to 360 °.
Each time the rotation of 0 ° is completed, the respective photoelectric conversion outputs S1 and S
The ratio β (= S1 / S2) of 2 is calculated, and the determination unit 24 determines the threshold value T based on the calculation result as in the first embodiment.
Set v1 and Tv2, and judge the occurrence of fire under each set condition.

According to this embodiment, the number of optical filters can be reduced. Next, a third embodiment will be described with reference to FIG. In FIG. 5, the same or corresponding parts as in FIG. 1 are designated by the same reference numerals. In this embodiment, the wavelength λ1 =
First light-emitting element 34 that emits light of a single wavelength of 0.5 μm
And a second single wavelength light having a wavelength λ2 = 0.9 μm.
The light emitting element 36 of the second light emitting element 36 is provided with the optical axis directed in the same direction, and the scattered light by the first light emitting element 34 is received only by the first light receiving element 14, and the scattered light by the second light emitting element 36 is In order to receive light only by the light receiving element 18, a shield plate 38 for preventing light mixing is provided so as to divide the smoke detection space into two.

Then, as described in the first embodiment, the arithmetic unit 22 calculates the ratio β (= S1 / S2) of the photoelectric conversion output signals S1 and S2 of the first and second light receiving elements 14 and 18. The determination section 24 compares the ratio β with the threshold value Tth to determine the type of smoke, and further sets the threshold value Tv and the photoelectric conversion output signal S1, which are set for each determined type of smoke. The presence or absence of fire is detected from the magnitude relationship with the output level of S2.

According to this embodiment, no optical filter is required, and the semiconductor laser diode is applied to the light emitting elements 34 and 36, so that the size can be reduced. Next, a fourth embodiment will be described with reference to FIG. In FIG. 6, the same or corresponding parts as in FIG. 1 are designated by the same reference numerals.
In this embodiment, an optical axis of a first light emitting element 40 that emits a single wavelength light having a wavelength λ1 = 0.5 μm and an optical axis of a second light emitting element 42 that emits a single wavelength light having a wavelength λ2 = 0.9 μm. Are arranged in the same direction, and the scattering angle formed by the light receiving axis of the light receiving element 44 and the optical axes of these light emitting elements 40 and 42 is θ.
, And the first light emitting element 40 and the second light emitting element 42 are alternately blinked every cycle of τ / 2 in synchronization with the synchronization signal output from the timing control section 46.

Further, the arithmetic unit 22 synchronizes the photoelectric conversion output output from the light receiving element 44 with the output S1 when the first light emitting element 40 is lit and the second light emitting element in synchronization with the synchronization signal. Distinguish from the output S2 when 42 is lit,
A ratio β (= S for each period τ for inputting both outputs S1 and S2)
1 / S2) is calculated. Further, the judging section 24 judges the type of smoke by comparing the ratio β with the threshold value Tth, and further sets the threshold value Tv and the photoelectric conversion output signals S1, S2 set for each judged type of smoke. The presence or absence of fire is detected based on the magnitude relationship with the output level of.

According to this embodiment, since there is no mechanically moving part, the durability is excellent.

[0031]

As described above, according to the present invention, the ratio of the light intensities of the scattered light of the respective wavelengths when the smoke penetrates by irradiating the smoke detection space with the light of two kinds of wavelengths. The type of smoke is determined based on the above, and the presence or absence of fire is determined by further comparing the light intensity with a threshold value set according to the determined type of smoke, or a plurality of Irradiating the smoke detection space with the light of the wavelength of the above, detecting from the scattered light when smoke enters through the optical filter of the light of two specific wavelengths, based on the ratio of the light intensity of the light of each wavelength It is decided to judge the presence or absence of fire by further comparing the light intensity with the threshold value set according to the type of smoke determined by this method. The difference between the light intensity ratio of different scattered light and the type of smoke. Based on the correlation, it is possible to determine the type of smoke.

In addition, a threshold value for determining the presence or absence of fire is set according to the determined smoke type, and the presence or absence of fire is compared by comparing this threshold value with the magnitude relationship of the light intensity of scattered light. Since the final judgment is, rather than judging the presence of fire with a uniform threshold regardless of the type of smoke as in the past,
The accuracy of judgment is improved, and it is possible to prevent false fire reports.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the principle of smoke discrimination of the present invention.

FIG. 3 is another explanatory diagram for explaining the principle of smoke discrimination according to the present invention.

FIG. 4 is a structural explanatory view showing a structure of a second exemplary embodiment of the present invention.

FIG. 5 is a configuration explanatory view showing a configuration of a third embodiment of the present invention.

FIG. 6 is a structural explanatory view showing the structure of a fourth exemplary embodiment of the present invention.

FIG. 7 is a configuration explanatory view for explaining a configuration of a conventional scattered light type smoke sensor.

[Explanation of symbols]

 12, 34, 36, 40, 42; light-emitting element 14, 18, 44; light-receiving element 16, 20, 28; optical filter 22; calculation unit 24; determination unit 26; reference data storage unit 32, 46; timing control unit 30 ; Constant speed rotary motor

Claims (4)

[Claims] 1. A light emitting means for irradiating a smoke detecting space with light having a plurality of wavelengths, and a first light transmitting means for transmitting only light of a first wavelength among scattered light due to smoke existing in the smoke detecting space. An optical filter, a second optical filter that transmits only light of a second wavelength among scattered light due to smoke existing in the smoke detection space, and a first light receiving that receives light that has passed through the first optical filter. Means, a second light receiving means for receiving the light transmitted through the second optical filter, a computing means for computing a ratio between the output of the first light receiving element and the second output, and a computation of the computing means. The type of smoke is determined based on the magnitude relationship between the ratio and the preset threshold for smoke detection, and the threshold for fire detection corresponding to the determined type of smoke and the first or second light reception. A determination means for determining the presence or absence of a fire based on the magnitude relationship of the output of the means, Notification device. 2. A light emitting means for emitting light having a plurality of wavelengths, a filter portion for transmitting light of a first wavelength and a filter portion for transmitting light of a second wavelength are alternately arranged to emit light and smoke. An optical filter that alternately irradiates the smoke detection space with the light of the first wavelength and the light of the second wavelength by interposing between the space and the space, and receives the scattered light due to the smoke existing in the smoke detection space. The light receiving means, a calculating means for calculating the ratio of the output of the light receiving element to the scattered light of the light of the first wavelength and the output of the light receiving element to the scattered light of the light of the second wavelength, and the calculation of the calculating means. The type of smoke is determined based on the magnitude relationship between the ratio and the preset threshold for smoke detection, and the threshold for fire detection corresponding to the determined type of smoke and the first or second light reception. Determination means for determining the presence or absence of a fire based on the magnitude relationship of the output of the means. Fire alarm device. 3. A first irradiating smoke detecting space with light of a first wavelength.
And a second light emitting means for irradiating the smoke detection space with light of the second wavelength, and a first light receiving means for receiving only scattered light of light of the first wavelength generated by smoke existing in the smoke detection space. Ratio of the output of the first light receiving element and the second output of the first light receiving element, the second light receiving means for receiving only the scattered light of the light of the second wavelength generated by the smoke existing in the smoke detection space, The type of smoke is determined based on the magnitude relation between the ratio calculated by the calculation unit and the preset threshold for smoke detection, and the fire detection corresponding to the determined type of smoke. A fire alarm device, comprising: a judgment threshold value for judging the presence or absence of a fire based on the magnitude relationship between the threshold value for use and the output of the first or second light receiving means. 4. A first irradiating the smoke detection space with light of a first wavelength.
Light emitting means, second light emitting means for irradiating the smoke detection space with light of the second wavelength, control means for alternately blinking control of the first light emitting means and the second light emitting means, and the smoke detecting space. Receiving means for receiving the scattered light of the first wavelength and the scattered light of the second wavelength, which are generated by the smoke existing in the space, and the scattering of the light of the first wavelength, which is generated by the smoke existing in the smoke detection space. Arithmetic means for computing the ratio of the output of the light receiving means when receiving light and the output of the light receiving means when receiving scattered light of the second wavelength light generated by smoke existing in the smoke detection space. And a threshold value for fire detection corresponding to the determined smoke type, the type of smoke being determined from the magnitude relationship between the ratio calculated by the calculating means and a preset threshold value for smoke detection. And a judgment means for judging the presence or absence of a fire based on the magnitude relationship between the output of the first or second light receiving means. Fire alarm device comprising the, the.