JP2585559B2 - Fire judgment device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fire judging device for judging a fire from a change in a light receiving output due to smoke of a plurality of wavelengths of light.

(Prior Art) Conventionally, in a so-called dimming type smoke detector, attenuated light due to smoke of light from a light emitting element is received by a light receiving element, and a light receiving output is equal to or less than a predetermined threshold value according to smoke density. When this happens, a fire detection output is generated.

(Problems to be Solved by the Invention) By the way, in the conventional dimming smoke detector, a light receiving element having a light receiving sensitivity within a light source wavelength band by the light emitting element is used, and the wavelength of the smoke detection light is used. Without taking into account
A fire is determined only from a change in the amount of detection light due to smoke.

Therefore, the inventors of the present application attempted to analyze through a fire experiment whether or not there is a correlation between the wavelength of smoke detection light and the change in the amount of light due to smoke in a conventional extinction smoke detector. It has been found that the change in the amount of light due to smoke varies depending on the wavelength of the detection light.

(Means for Solving the Problems) The present invention has been made in view of such a situation,
An object of the present invention is to provide a fire judging device capable of accurately judging a fire by effectively utilizing a correlation between a wavelength of smoke detection light and a change in light amount due to smoke.

In order to achieve this object, according to the present invention, there is provided a light emitting unit that emits at least two types of light having different emission wavelengths, and an attenuated light according to a smoke density of the plurality of wavelengths emitted from the light emitting unit. And a fire determining means for determining a fire based on the received light output from the light receiving means, wherein the fire determining means includes a change pattern of the received light output with respect to an elapsed time and a predetermined fire. A first comparison unit that compares a reference pattern of a change in received light output with respect to an elapsed time at the time of occurrence for each wavelength, and determines that a fire has occurred when at least two types of wavelengths have a correspondence relationship with the reference pattern, and outputs the result; And an adding means for adding the plurality of light receiving outputs, and comparing the added output of the adding means with a predetermined threshold value, determining that a fire has occurred when an added output of a predetermined threshold level or less is obtained, and outputting the fire. A comparing unit for, when each fire determination output of the first comparison unit and the second comparing unit is obtained, is obtained by so providing the fire output unit for outputting a fire detection signal.

(Operation) According to the configuration of the present invention, for example, with respect to an increase in smoke density due to the progress of fire, for example, light of low wavelength (for example, blue) in the visible light region has a light amount at an early stage of fire. The temporal change is large, and the temporal change of the light amount decreases as time elapses, while the high wavelength in the visible light region (for example, red)
In the early stage of the fire, the temporal change in the light amount is small, and the temporal change in the light amount is large as time passes. When the above-mentioned predetermined correlation is obtained, it is determined that a fire has occurred. In addition, a fire is also determined when the result of calculating the light receiving output of each wavelength is equal to or less than a predetermined threshold level.

(Embodiment) FIG. 1 is an explanatory view showing an embodiment of the present invention.

First, the configuration will be described. Reference numeral 1 denotes a smoke detection chamber, which has a so-called labyrinth structure which allows the inflow of smoke from the outside but blocks the incidence of light from the outside. In this embodiment, three light emitting elements 2
B, 2G, 2R are installed, for example, the light emitting element 2B emits blue light having a center wavelength of 450 nm, the light emitting element 2G emits green light having a center wavelength of 550 nm, and further, the light emitting element 2R It emits red light with a center wavelength of 700 nm. These light emitting elements 2B, 2G, and 2R are driven by the light emission driving circuit 3 to continuously emit light.
Alternatively, it is driven intermittently.

At positions facing the light emitting elements 2B, 2G, 2R, light receiving elements 4B, 4G, 4R are installed at a predetermined smoke detection distance, and the light emitting elements 2B, 2R
A light receiving output of attenuated light due to smoke in which light having different center wavelengths from G and 2R flows is generated. After the outputs of the light receiving elements 4B, 4G, 4R are amplified by the amplifiers 5B, 5G, 5R, they are given to a comparison unit 6 for judging a fire.

The principle of the fire judgment based on the light receiving outputs of the three different wavelength lights in the ratio comparing unit 6 will be described as follows.

FIG. 2 is a characteristic diagram showing a relationship between transmittance with respect to each wavelength in a visible light region of 380 nm to 780 nm using a light source having a substantially flat spectral characteristic, with time change from a fire occurrence as a parameter. .

As is apparent from Figure 2, in the stage of a fire early time t _0, the transmittance since the smoke influx little has a flat at the wavelength of the entire visible light region, from the fire At the times t1, t2, t3, t4 with the passage of time.

That is, in the initial stage of a fire, the change in transmittance in a low wavelength range is large, while the change is small in a high wavelength range. Then, when the time elapses after the fire progresses, the change in the transmittance in the low wavelength range is reduced and the change in the transmittance in the high wavelength range is increased.

FIG. 3 shows wavelengths of 450 nm (blue) and 500 nm in FIG.
(Green) and 700 nm (Red) show the change over time in transmittance. For blue in the low wavelength range, curve B
As shown in the figure, in the initial stage of the fire, the change in the transmittance is large, and the change in the transmittance becomes small as time elapses. In the initial stage, the change in the transmittance is small and the change in the transmittance increases as the time elapses. Further, as for the green between the two, as shown by the curve G, a change in the transmittance with time, which is substantially intermediate between the two, occurs.

The ratio comparison unit 6 shown in FIG. 1 judges a fire from the correlation of the time change of the transmittance with respect to the wavelength of the smoke detection light shown in FIGS. That is, the ratio comparing section 6 samples the received light output for each wavelength obtained through the amplifiers 5B, 5G, and 5R at a predetermined sampling period T, for example, as shown on the time axis of FIG. When the time change rate (slope) of the received light output for each wavelength obtained from the sampling data changes, for example, according to a preset fire judgment characteristic as shown in FIG. 3, it is judged that a fire has occurred. As a result, a fire judgment output is generated.

Further, in the embodiment of FIG. 1, the outputs of the amplifiers 5B, 5G, and 5R are added by an adder 7, and the added output of the adder 7 is input to a comparator 8, which outputs a reference voltage source. 9 to generate an H-level output when the voltage falls below a threshold voltage corresponding to the predetermined smoke density.
In addition to the above, in addition to the fire judgment based on the interrelationship of the temporal change of the light reception output due to the different wavelength light, means for judging a fire from the change in the light reception level is added.

The outputs of the ratio comparing unit 6 and the comparator 8 are given to a fire output unit 10, and the fire output unit 10 outputs to the outside when the fire judgment output of either the ratio comparing unit 6 or the comparator 8 is obtained. A fire detection signal is output, or a fire detection signal is output to the outside when both fire judgment outputs are obtained.

In the embodiment shown in FIG. 1, the light emitting elements 2B, 2B
Lights of three wavelengths (blue, green, red) having different wavelengths than G and 2R are emitted and received by the light receiving elements 4B, 4G and 4R, respectively, and the time change of the light receiving output for each different wavelength is compared by the ratio comparing unit 6 When the correlation of the time change of the received light output different for each wavelength obtained in advance as shown in FIGS. 2 and 3 is obtained, it can be determined that a fire has occurred. Since the presence or absence of a fire is determined from the change in the received light output depending on the wavelength of light, it is possible to make a clear distinction from cigarette smoke, which is a cause other than a fire, and make an accurate fire determination without generating false alarms. .

On the other hand, in the fire judgment by the ratio comparing unit 6, since a certain processing time is required until a predetermined correlation of the time change for each wavelength is obtained, the rapid fire progress is determined by the comparator 8. A fire is determined from a decrease in the light receiving level, and a fire detection signal can be sent to the outside from the fire output unit 10 without having a fire determination by the ratio comparing unit 6, so that the reliability of the fire determination can be further enhanced.

FIG. 4 is an explanatory view showing another embodiment of the light emitting means and the light receiving means provided in the smoke detection chamber 1 shown in FIG. 1. In this embodiment, the light emitting elements 2B, 2G, and 2R are used. The same light-emitting element with flat spectral characteristics in the visible light region is used, and filters 12B, 12G, and 12R that transmit only light of a specific wavelength are provided in front of the light-emitting elements 2B, 2G, and 2R. And That is, the filter 12B transmits only blue light with a center wavelength of 450 nm, the filter 12G transmits only green light with a center wavelength of 550 nm, and the filter 12R transmits only red light with a center wavelength of 700 nm. Like that. Of course, filter 12
B, 12G, and 12R are provided in front of the light-receiving elements 4B, 4G, and 4R instead of being provided in front of the light-emitting elements 2B, 2G, and 2R, and only blue, green, and red light is selected from the light that has passed through the smoke detector. Take out the light receiving element 4B, 4
The light may be incident on G and 4R.

FIG. 5 is an explanatory view showing another embodiment of the light emitting means and the light receiving means provided in the smoke detection chamber 1 of FIG. 1. In this embodiment, the light emitting elements 2B, 2G and 2R are As in the embodiment of FIG. 1, blue, green and red wavelength lights are output, respectively.
A light-receiving element 4 having uniform spectral sensitivity in the visible light region is provided for these light-receiving elements, and light-emitting elements 2B, 2G, and 2R are sequentially driven to emit light to emit light of different wavelengths through the smoke detection area.
Characterized in that the light is made to enter.

Further, as the light emitting element of the present invention that emits light of two or more different wavelengths, a two-color light emitting diode can be used. For example, in the case of a two-color light emitting diode of red and green, light emission output of three kinds of different wavelength light is performed by driving light emission of red, driving of light emission of green, and light emission driving of three colors to be a combined color by both light emission driving. Can be obtained.

In the above-described embodiment, the fire determination using three types of wavelength light is taken as an example. However, two or more types of appropriate wavelength light may be used.

(Effects of the Invention) As described above, according to the present invention, a light emitting unit that emits light of at least two or more wavelengths having different emission wavelengths and a smoke density of a plurality of wavelength lights emitted from the light emitting unit are provided. A fire detecting means having a light receiving means for receiving the attenuated light and a fire judging means for judging a fire based on a light receiving output from the light receiving means. The reference pattern of the change of the received light output with respect to the elapsed time at the time of the determined fire is compared for each wavelength, and when at least two types of wavelengths have a correspondence relationship with the reference pattern, it is determined to be a fire and output. One comparing unit, an adding means for adding a plurality of light-receiving outputs, and comparing the added output of the adding means with a predetermined threshold, and determining that a fire has occurred when an added output equal to or less than a predetermined threshold level is obtained. A first comparison unit that outputs a fire detection signal when each fire judgment output of the first comparison unit and / or the second comparison unit is obtained. The unit detects the difference in the time variation of the light amount change due to smoke of different wavelength light generated only at the time of a fire, determines that the fire has occurred, and sends out a fire detection signal with the fire determination output of the first comparison unit or the second comparison unit. In such a case, a rapid fire progress can be judged based on a decrease in the light receiving level by the second comparing section, and a fire detection signal can be sent to the outside without waiting for the first comparing section to judge the fire. Since the reliability of the determination can be further improved, a more accurate fire determination can be made, and the reliability of the fire determination can be greatly improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is a characteristic diagram showing a change in transmittance with respect to the wavelength of smoke detection light using elapsed time as a parameter, and FIG. 3 is based on FIG. FIG. 4 is a characteristic diagram showing the time change of the transmittance of the blue, green, and red smoke detection light obtained by the method. FIGS. 4 and 5 are explanatory diagrams showing another embodiment of the light emitting unit and the light receiving unit used in the present invention. It is. 1: Smoke detection room 2B, 2G, 2R: Light emitting element 3: Light emitting drive circuit 4, 4B, 4G, 4R: Light receiving element 5B, 5G, 5R: Amplifier 6: Ratio comparator 7: Adder 8: Comparator 9: Reference voltage source 10: Fire output section 12B, 12G, 12R: Filter

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-128831 (JP, A) JP-A-58-78290 (JP, A)

Claims (2)

(57) [Claims] A light-emitting means for emitting at least two types of wavelength lights having different emission wavelengths; a light-receiving means for receiving attenuated light corresponding to a smoke density of a plurality of wavelength lights emitted from the light-emitting means; In a fire judging device having fire judging means for judging a fire based on a light receiving output from a light receiving means, the fire judging means comprises: a change pattern of the light receiving output with respect to an elapsed time; and a predetermined elapsed time when a fire occurs. A first comparison unit that compares a reference pattern of the change of the received light output with respect to each wavelength for each wavelength, and determines that a fire has occurred when a correspondence relationship with the reference pattern is obtained for at least two wavelengths; An adding means for adding the received light output of the second means, and comparing the added output of the adding means with a predetermined threshold value, determining that a fire has occurred when an added output equal to or less than a predetermined threshold level is obtained, and outputting a second signal. A fire judging device comprising: a comparing unit; and a fire output unit that outputs a fire detection signal when each of the fire judging outputs of the first comparing unit and the second comparing unit is obtained. 2. A light emitting means for emitting at least two kinds of wavelength light having different emission wavelengths; a light receiving means for receiving attenuated light corresponding to a smoke density of a plurality of wavelength lights emitted from the light emitting means; In a fire judging device having fire judging means for judging a fire based on a light receiving output from a light receiving means, the fire judging means comprises: a change pattern of the light receiving output with respect to an elapsed time; and a predetermined elapsed time when a fire occurs. A first comparison unit that compares a reference pattern of the change of the received light output with respect to each wavelength for each wavelength, and determines that a fire has occurred when a correspondence relationship with the reference pattern is obtained for at least two wavelengths; An adding means for adding the received light output of the second means, and comparing the added output of the adding means with a predetermined threshold value, determining that a fire has occurred when an added output equal to or less than a predetermined threshold level is obtained, and outputting a second signal. A fire judging device comprising: a comparing unit; and a fire output unit that outputs a fire detection signal when each of the fire judging outputs of the first comparing unit and the second comparing unit is obtained.