JPS63167242A - Fire judging device - Google Patents

Abstract

PURPOSE:To accurately judge a fire by comparing time variation in photodetection output of each of different wavelength light beams obtained from a photodetecting means, and judging the fiber when specific mutual relation of time variation is obtained. CONSTITUTION:Three light emitting elements 2B, 2G, and 2R emit light beams which differ in wavelength and the output of light receiving elements 4B, 4G, and 4R which generate light reception outputs with the light beams attenuated by smoke which flows in are supplied to a rate comparison part 6 through amplifiers 5B, 5G, and 5R. Then the rate comparison part 6 samples the light reception outputs of each wavelength at a specific sampling period and judges a fire to generate a fire judgement output when the time variation rate of the light reception output of each wavelength varies according to a fire judgement characteristic. Further, the addition output of an adder 7 is inputted to a comparator 8 and the fire is judged when the input voltage drops below a threshold voltage corresponding to specific smoke concentration set by a reference voltage source 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fire determination device that determines a fire based on changes in the light output of a plurality of wavelengths of light due to smoke.

(Prior art) Conventionally, in so-called dimming type smoke detectors, a light receiving element receives light emitted from a light emitting element and is attenuated by smoke, and the received light output is determined to be below a predetermined threshold depending on the smoke density. When this happens, a fire detection output is generated.

(Problem to be Solved by the Invention) Conventional dimming type smoke detectors use a light-receiving element that has light-receiving sensitivity within the light source wavelength band of the light-emitting element. Fires are determined only from changes in the amount of detected light due to smoke, without taking this into account.

Therefore, the inventors of the present application attempted to analyze through fire experiments whether there is a correlation between the wavelength of smoke detection light in conventional dimming type smoke detectors and the change in light amount due to smoke. We have come to the knowledge that the amount of light changes due to smoke differs depending on the wavelength of the light.

(Means for Solving the Problems) The present invention was made in view of the above situation, and effectively utilizes the correlation between the wavelength of smoke detection light and the change in light ω caused by smoke to accurately detect smoke. The purpose of the present invention is to provide a fire determination device that can determine whether there is a fire or not.

In order to achieve this object, the present invention includes a light emitting means that emits light of at least two different wavelengths, and a light emitting means that receives attenuated light due to smoke of the plurality of wavelength lights emitted from the light emitting means. A light receiving means and a fire determining means are provided for comparing temporal changes in the received light output for each different wavelength light obtained from the light receiving means and determining a fire when a predetermined correlation of temporal changes is obtained. It is something.

(Function) According to the configuration of the present invention, for example, low wavelength light in the visible light region (
For example, for blue), the time change in light intensity is large in the early stage of a fire, and as time passes, the time change in light intensity decreases.On the other hand, for high wavelengths in the visible light region (for example, red), Since there is a relationship in which the temporal change in the amount of light is small at this stage, and the temporal change in the optical signal increases as time passes, the temporal changes in the received light output due to at least two different wavelengths of light are compared, and the above-mentioned predetermined interaction is compared. When a relationship is established, it is determined that there is a fire.

(Example) FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

First, to explain the structure, 1 is a smoke detection chamber, which has a so-called labyrinth structure that allows smoke to flow in from the outside but blocks light from entering the room. In this embodiment, the smoke detection section 1 includes three light emitting elements 2B.
, 2G, and 2R are installed. For example, the light emitting element 2B emits blue light with a center wavelength of 45 Q nm, and the light emitting element 2G emits green light with a center wavelength of 550 nm.
Further, the light emitting element 2R emits red light having a center wavelength of 700 nm. These light emitting elements 2B, 2G, and 2R are driven to emit light continuously or intermittently by a light emitting drive circuit 3.

At positions facing the light emitting elements 28.2G and 2R, light receiving elements 4B, 4G and 4R are installed at a predetermined smoke inspection distance, and light with different center wavelengths from the light emitting elements 28.2G and 2R flows in. The received light output is attenuated by the smoke. The output of light receiving elements 48.4G, 4R is output from amplifiers 5B, 5G, 5.
After being amplified by R, the ratio comparison unit 6 serves as a fire judgment means.
is given to.

The principle of fire judgment based on the light reception outputs of three different wavelengths of light in the ratio comparison section 6 will be explained as follows.

Figure 2 is a characteristic diagram that uses a light source with approximately flat spectral characteristics in the visible light region from 380 nm to 780 nm, and shows the relationship between transmittance for each wavelength using the change in time from the occurrence of a fire as a parameter. .

As is clear from Figure 2, at the initial stage of the fire, at time to, there is almost no inflow of smoke, so the transmittance is flat in all visible light wavelengths, and the transmittance is flat in all visible light wavelengths. Time tl, t2. t3
．． At t4, the changes shown occur.

That is, in the early stages of a fire, the change in transmittance in the low wavelength range is large, while the change in the high wavelength range is small. Then, as the fire progresses and time passes, a relationship is obtained in which the change in transmittance in the low wavelength range decreases and the change in the transmittance in the high wavelength range increases.

Figure 3 shows the wavelength of 450 nm (blue) in Figure 2, and 550 nm.
This shows the change in transmittance over time at 700 nm (green) and 700 nm (red).As shown in curve B for blue in the lower wavelength range, there is no change in transmittance in the early stages of a fire. On the other hand, for red in the high wavelength range, as shown by curve R, there is little change in transmittance in the early stages of a fire, but as time passes, the change in transmittance decreases. The changes become greater. Furthermore, for green, which is between the two, as shown by curve G, the transmittance changes over time, which is approximately halfway between the two.

The ratio comparator 6 shown in FIG. 1 determines the presence of a fire based on the interrelationship between the wavelength of the smoke detection light and the time change in transmittance shown in FIGS. 2 and 3. That is, the ratio comparator 6 samples the received light output for each wavelength obtained through the antennas 158.5G and 5R at every predetermined sampling period T, as shown on the time axis in FIG. 3, for example. ,
When the time rate of change (slope) of the received light output for each wavelength determined from this sampling data changes in accordance with the preset fire judgment characteristics as shown in Figure 3, for example, a fire is detected. A fire judgment output is generated based on the judgment.

Furthermore, in the embodiment of FIG. 1, an amplifier 5B.

The outputs of 5G and 5R are added by an adder 7, and the added output of the adder 7 is inputted to a comparator 8. It is designed to generate an H level when
In addition to determining a fire based on the correlation between time changes in the received light output due to light of different wavelengths in the ratio comparison section 6, a means for determining a fire based on changes in the received light level is added.

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

In the embodiment shown in FIG. 1, the light emitting elements 2B,
2G and 2R have three different wavelengths of light (blue, green,
Red) is emitted and received by each of the light receiving elements 4B, 4G, and 4R, and the time change of the received light output for each different wavelength is compared in the ratio comparing section 6, and the result is obtained in advance as shown in FIGS. 2 and 3. A fire can be determined when a correlation between the temporal changes in the received light output for each wavelength is obtained, and the presence or absence of a fire can be determined from the changes in the received light output depending on two or more different wavelengths of light. Therefore, it is possible to clearly distinguish it from cigarette smoke, etc., which is a cause other than fire, and to make an accurate fire judgment without generating false alarms.

On the other hand, when determining a fire using the ratio comparison unit 6, it takes a certain amount of processing time to obtain the correlation between predetermined time changes for each wavelength. A fire is determined from a decrease in the received light level, and a fire detection signal can be sent to the outside from the fire output section 10 without waiting for the fire determination by the ratio comparison section 6, thereby further increasing the reliability of fire determination.

FIG. 4 is an explanatory diagram showing another embodiment of the light emitting means and light receiving means provided in the smoke detection chamber 1 shown in FIG. 1, and in this embodiment, the light emitting elements 2B and 2G.

The same light-emitting element with flat spectral characteristics in the visible light region is used as 2R, and light-emitting elements 2B and 2G.

Filter 1 that transmits only light of a specific wavelength on the front of 2R
28.12G and 12R are provided. 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 12B transmits only green light with a center wavelength of 550 nm.
R is designed to transmit only red light with a center wavelength of 700 nm. Of course, the filters 12B, 12G, and 12R are light emitting elements 2B.

Instead of providing the light receiving elements 4B and 4 in front of 2G and 2R,
It is installed in front of G and 4R, and from the light that passes through the smoke detector, blue,
Extracts only green and red light and uses light receiving elements 4B, 4G, 4R
It may also be made to be incident on the .

FIG. 5 is an explanatory diagram showing another embodiment of the light emitting means and 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, each is blue.

A light-receiving cable 4 is provided that outputs green and red wavelength light and waits for uniform spectral sensitivity in the visible light region for these light-receiving elements.
It is characterized in that the light emitting elements 28.2G and 2R are sequentially driven to emit light so that light of different wavelengths is made to enter the light receiving element 4 via the smoke detection area.

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 red and green two-color light emitting diode, there is a red light emitting drive, a green light emitting drive, and a three color light emitting drive that is a composite color of both light emitting drives.
It is possible to obtain light receiving outputs of different types of wavelength light.

In the above embodiment, the fire judgment is performed using three types of wavelength light, but two or more types of appropriate wavelength light may be used.

(Effects of the Invention) As explained above, according to the present invention, there is provided a light emitting means that emits light of at least two or more different wavelengths, and attenuation due to smoke of the plurality of wavelength lights emitted from the light emitting means. A light receiving means for receiving light, and a fire determining means for comparing time changes in the light receiving output for each different wavelength light obtained from the light receiving means and determining a fire when a predetermined correlation of time changes is obtained. As a result, a fire can be determined based on the difference in the time change in light intensity caused by smoke with different wavelengths of light that occurs only in the event of a fire, making it possible to make more accurate fire determinations and greatly improving the reliability of fire determination. can be improved.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the 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. 2. Figures 4 and 5 are explanatory diagrams showing other embodiments of the light emitting means and light receiving means used in the present invention. It is. 1: Smoke detection chamber 2B, 2G, 2R: Light emitting element 3: Light emitting drive circuit 4. 48.4G, 4R 2 light receiving elements 58.5G, 5R: Amplifier 6: Ratio comparison section 7: Adder 8: Comparator 9: Reference voltage source 10: Fire output section

Claims (1)

[Claims] a light emitting means for emitting light of at least two or more different wavelengths; a light receiving means for receiving attenuated light according to the smoke concentration of the plurality of wavelength lights emitted from the light emitting means; 1. A fire determining device comprising: fire determining means for comparing temporal changes in received light output for different wavelengths of light and determining a fire when a predetermined interrelationship of temporal changes is obtained.