JPH08271424A - Microparticle sensor - Google Patents

Abstract

PURPOSE: To provide a microparticle sensor for detecting the smoke reliably by monitoring fluctuation in the quantity of light emitted from a first light emitting element and in the quantity of scattering light caused by contamination in smoke detecting section. CONSTITUTION: Light emitted from a first light emitting element 7a is scattered by smoke having light attenuation rate of 2%/m or less flowing through a smoke detecting section and received by a first photoreceptor element 8a thus detecting the smoke. On the other hand, a second photoreceptor element 8b receives the light emitted from a first light emitting element 7a and monitors the quantity of light emitted therefrom. At the same time, the first photoreceptor element 8a is irradiated with a specified quantity of light emitted from a second light emitting element 7b and the operation is tested.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine particle detection sensor for detecting fine particles such as smoke generated during a fire or dust contained in the air, and in particular, the presence of fine particles can be detected by detecting scattered light from the fine particles. The present invention relates to a photoelectric type particle detection sensor for detecting.

[0002]

2. Description of the Related Art Conventionally, in smoke detectors as an example of this type of particulate matter detection sensor, a large amount of light source such as a discharge tube or a laser is used, or a photomultiplier tube, an avalanche photodiode, etc. The high-sensitivity light-receiving element was used to obtain high sensitivity. These smoke detectors indirectly reduce the light amount of the light emitting element by monitoring the level of noise light that is emitted from the light emitting element in the smoke detecting section and is incident on the light receiving element when the light emitted from the light emitting element is reflected in the smoke detecting section. , Estimated the pollution. Alternatively, by adopting a method of counting the number of pulses of scattered light generated every time a smoke particle passes through the smoke detecting section, the influence of fluctuations in the light quantity of the light emitting element and fluctuations in the scattered light quantity due to contamination in the smoke detecting section I was trying to avoid it.

[0003]

However, in the above-described method for monitoring the level of noise light, there are many factors that cause fluctuations in the level of noise light. Fouling of the element, fouling of the light receiving element or its optical system, fouling of the smoke detector wall,
It was not possible to determine whether the noise light fluctuated due to dew condensation or fluctuations of fine particles such as dust in the environment where the detector was installed. Further, the method of counting the number of pulses of scattered light has not yet solved the problem that the sensitivity fluctuates according to the fluctuation of the flow velocity of the inflowing smoke. In addition, smoke detectors that have the function of determining the particle size of smoke particles based on the size of the pulse waveform of scattered light, and the function of not counting weak light as noise and counting it There is also a possibility that fluctuations in the amount of scattered light due to contamination in the smoke section may lead to counting errors.

The present invention has been made in order to solve such a problem, and monitors smoke fluctuations with high reliability by monitoring fluctuations in the light quantity of the light emitting element and fluctuations in the scattered light quantity due to contamination in the smoke detector. An object of the present invention is to provide a particle detection sensor that can be used.

[0005]

According to a first aspect of the present invention, there is provided a fine particle detection sensor in which a first light emitting element and a first light receiving element are arranged with a predetermined angle offset from each other so as to sandwich a smoke detecting section. In a fine particle detection sensor that detects fine particles such as dust contained in the smoke or air generated in a fire that has flowed into the smoke detector, the first light emitting element emits light in order to monitor the output light amount of the first light emitting element. A second light receiving element for receiving the emitted light, and a first light trap portion for preventing the light from the first light emitting element transmitted through the smoke detecting portion from being reflected and returning to the smoke detecting portion. And the second light receiving element is provided in the first optical trap portion.

In the fine particle detection sensor according to the second aspect, the first light emitting element and the first light receiving element are arranged so as to be sandwiched by the smoke detecting section and shifted from the facing position by a predetermined angle, and flow into the smoke detecting section. A fine particle detection sensor for detecting fine particles such as smoke generated in a fire or dust contained in air, the second light emitting element for irradiating a first light receiving element with a predetermined amount of light for performing an operation test After the light emitted from the second light emitting element is reflected at least once on the wall surface of the case forming the space for detecting particles, the first light receiving element is provided at the position where the reflected light is incident. is there. The particle detection sensor according to claim 3 is the sensor according to claim 2, wherein the second light emitting element prevents the light reflected in the smoke detector from directly entering the first light receiving element. It is provided in the optical trap section. The particle detection sensor according to a fourth aspect is the sensor according to any one of the first to third aspects, wherein a slit-shaped suction side nozzle disposed so as to face the smoke detection section, and a suction side nozzle facing each other. A slit-shaped exhaust side nozzle arranged so as to face the smoke detection section, a suction side air chamber and an exhaust side air chamber connected to the suction side nozzle and the exhaust side nozzle, respectively, and the suction side nozzle to the smoke detection section A smoke passage having a slit-shaped cross-sectional shape passing through to the exhaust side nozzle is formed.

In the fine particle detection sensor according to a fifth aspect, the first light emitting element and the first light receiving element are arranged so as to be sandwiched by the smoke detecting section, and are displaced from each other by a predetermined angle, and the particles flow into the smoke detecting section. A fine particle detection sensor for detecting fine particles such as smoke or dust contained in the air generated in the case of a fire; a second light emitting element for irradiating a first light receiving element with a predetermined amount of light for performing an operation test; A second light trap portion for preventing the light reflected in the smoke detecting portion from directly entering the first light receiving element, wherein the second light emitting element is provided in the second light trap portion. Is.

[0008]

In the fine particle detection sensor according to claim 1,
The first light emitting element and the first light receiving element detect fine particles, and the second light receiving element provided in the first light trap portion receives the light emitted from the first light emitting element to receive the first light.
The output light amount of the light emitting element is monitored.

In the fine particle detection sensor according to the second aspect, the fine particles are detected by the first light emitting element and the first light receiving element, and a predetermined amount of light is emitted from the second light emitting element to at least the case wall surface. After being reflected once, the reflected light is incident on the first light receiving element and an operation test is performed. When a light-emitting element for operation test is provided on the optical axis of the light-receiving element and the amount of light emitted corresponding to a fire is incident on the light-receiving element, the light-receiving element will operate normally if the predetermined particles are in the smoke detector. I only understand. In the present invention, since the fire operation test is performed by reflected light instead of direct light, it can be known whether the inner wall surface of the case is dirty. That is, if the inner wall surface of the case is not dirty, it operates normally, but if it is dirty, the output of the light receiving element becomes a value outside the threshold value. The present invention is a fine particle detection sensor that detects dust in the air and extremely thin smoke (extinction rate 2% / m), and uses a light receiving element that can detect even very small scattered light. There is.
If a light emitting element for operation test is provided on the optical axis of such a light receiving element and light is directly incident on the light receiving element, not only the light receiving element is saturated immediately but also it may cause a failure. Absent. Therefore, these problems can be solved by making reflected light incident instead of direct light.

In the particle detecting sensor according to the third aspect, the second light emitting element is provided in the second light trap portion, and the second light trap portion prevents stray light from entering the light receiving element. Further, in the particulate matter detection sensor according to claim 4, a smoke passage having a slit-shaped cross section is formed from the slit-shaped suction side nozzle to the slit-shaped exhaust side nozzle through the smoke detector, and the smoke passage is formed. The scattered light of the light from the first light emitting element due to the smoke is received by the first light receiving element.

In the fine particle detection sensor according to the fifth aspect, the first light emitting element and the first light receiving element detect fine particles, and a predetermined amount of light is emitted from the second light emitting element provided in the second optical trap portion. Is irradiated to the first light receiving element to perform an operation test.

In a conventional smoke sensor or the like, a light shielding member and a light trap are formed so that light of the light emitting element, that is, direct light or primary reflected light of direct light does not enter the light receiving element, and the inner wall surface of the case is black. By doing so, the reflected light is attenuated. Further, it is a well-known technique to provide a light receiving element for monitoring the amount of emitted light on the optical axis of the light emitting element, or to provide a light emitting element for an operation test on the optical axis of the light receiving element. However, if these elements are simply exposed on the optical axis, the light from the original light-emitting element will be reflected and reflected in the smoke detector to cause stray light (actually, this problem is solved. For that the device is covered with a black holder). Therefore, the device of the present invention is used in the optical trap section
By providing the light emitting element for the operation test or the light receiving element for monitoring the emitted light amount, the reflected light is processed in the optical trap section. Therefore, stray light does not increase even if these elements are provided.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan sectional view showing a particle detection sensor according to an embodiment of the present invention. The suction side air chamber 2 is connected to the suction port 1, and the suction side nozzle 3 is connected to the suction side air chamber 2. An exhaust side nozzle 4 is arranged to face the suction side nozzle 3, and the exhaust side air chamber 5 is provided in the exhaust side nozzle 4.
The exhaust port 6 is connected via. The suction side nozzle 3 and the exhaust side nozzle 4 each have a slit-shaped nozzle hole of the same shape extending in a direction perpendicular to the paper surface, and the space between the suction side nozzle 3 and the exhaust side nozzle 4 is Smoke contained in the air is irradiated with light from a light emitting element 7a, which will be described later, to form a smoke detecting section that emits scattered light.

The first light emitting element 7a is arranged so as to face the smoke detecting section, while the first light receiving element 8a is arranged with a predetermined angle offset from the facing position of the light emitting element 7a sandwiching the smoke detecting section. . In addition, this smoke sensor is provided with the first light emitting element 7a.
And a second optical trap portion 10 arranged to face the first light receiving element 8a.

A second light receiving element 8b is provided on the optical axis of the first light emitting element 7a so as to face the first light emitting element 7a and at a deep position in the first optical trap portion 9. Further, the second light emitting element 7b is provided in a recessed portion in the second optical trap portion 10. The second light emitting element 8b is provided at a position where the light is reflected by the wall surface in the second light trap portion 10 and the reflected light is incident on the first light receiving element 8a.

When an air sampling pipe (not shown) opening in the monitoring space is connected to the suction port 1 and a suction fan (not shown) is connected to the exhaust port 6 to drive the suction fan,
The air in the monitoring space is sucked by negative pressure through the air sampling pipe, introduced into the smoke detector through the suction port 1, the suction side air chamber 2, and the suction side nozzle 3, and further, the exhaust side nozzle 4 and the exhaust side air. It is discharged through the chamber 5 and the exhaust port 6. At this time, part of the light L1 emitted from the first light emitting element 7a is scattered by smoke particles contained in the introduced air,
The scattered light L2 enters the first light receiving element 8a. First
Most of the light L1 emitted from the light emitting element 7a of the above-mentioned transmits through the smoke detecting section and goes straight, but the transmitted light L3 is attenuated while being repeatedly reflected on the wall surface of the first optical trap section 9. A part of the light L4 returning from the optical trap portion 9 toward the smoke detecting portion is included in the exhaust side nozzle 4 and the first light receiving element 8.
It has a labyrinth structure which is reflected by the wall surface of a and is introduced into the first optical trap portion 9 again. Further, the light leaking from the maze structure to the smoke detecting portion is attenuated while being repeatedly reflected on the wall surface of the second optical trap portion 10 and does not enter the first light receiving element 8a. The first light trap portion 9 and the second light trap portion 10 are both formed in a cylindrical shape. In addition, 3a is a light emitting element 7a of the suction side nozzle 3 in order to prevent light from the first light emitting element 7a from being reflected by the tip of the suction side nozzle 3 and directly entering the second light trap section 10. It is a light shielding member formed on the outer wall surface of the side.

Next, the flow of air in the smoke sensor of this embodiment will be described with reference to FIGS. Due to the negative pressure generated by the suction fan connected to the exhaust port 6, the air in the monitoring space is sucked into the air sampling tube and the suction port 1
Will be introduced to. After that, the air that has entered the suction side air chamber 2 having a large flow passage cross section becomes a laminar flow with a low flow velocity, and if there is smoke in the air, the smoke becomes homogeneous due to diffusion. Foreign matter having a high sedimentation velocity that has entered the air is sedimented and adhered in the suction side air chamber 2 and is prevented from entering the smoke detecting portion. Next, the air is guided to the suction side nozzle 3 having a long flow passage cross-section, the flow velocity is increased, and a slit-shaped cross section is formed to reach from the nozzle hole of the suction side nozzle 3 to the smoke detecting portion. Here, the cross-sectional shape of the airflow is slit-shaped because the width of the smoke (air) flow passage is narrowed in order to prevent the first light emitting element 7a and the first light receiving element 8a from being contaminated by smoke particles. The first light emitting element 7a and the first
The smoke flow path is slightly separated from the light receiving element 8a, and the height of the smoke flow path is increased for the purpose of preventing pressure loss due to the decrease of the flow path cross-sectional area. This is also to prevent dust from clogging the nozzle. The air having the slit-shaped cross section is sucked by the exhaust side nozzle 4 having the nozzle hole of the same shape as the suction side nozzle 3, so that the first light emitting element 7 which is the dead end is formed.
a, the first light receiving element 8a, and the first and second optical trap portions 9 and 10 are not reached and they are not contaminated. The air chamber 5 on the exhaust side is provided for the purpose of uniformly exhausting the air from the nozzle 4 on the exhaust side because the air sucked and exhausted by the suction fan provided in the subsequent stage of the exhaust port 6 has a negative pressure.

The second optical trap portion 9 is provided in the second optical trap portion 9.
The light receiving element 8b is for monitoring the output light amount of the first light emitting element 7a. Strictly speaking, since it is affected by scattering and absorption by smoke particles, the amount of light incident on the second light receiving element 8b is attenuated more than the amount of light emitted from the first light emitting element 7a. Since the thin smoke with the extinction rate of 2% / m or less is the object of detection, the amount of attenuation is extremely small. Therefore, practically, the output of the second light receiving element 8b is proportional to the output light amount of the first light emitting element 7a. Therefore, by obtaining the output of the second light receiving element 8b,
The output light amount of the light emitting element 7a can be monitored.
Further, by feeding back the output of the second light receiving element 8b, the output of the first light emitting element 7a can be controlled to a constant value, and the sensitivity of this particle detection sensor can be stabilized.

The installation position of the second light receiving element 8b is
It suffices if it is within the irradiation region of the first light emitting element 7a, and if this condition is satisfied, the position of the first light emitting element 7a on the optical axis,
The same effect can be obtained even if it is installed at a position deviated from the optical axis or a position in the immediate vicinity of the first light emitting element 7a.

The second light emitting element 7b provided in the second optical trap portion 10 receives the test signal from a receiver (not shown) connected to the particle detection sensor by a signal line, and outputs the second light emitting element 7b. The first light receiving element 8a is irradiated with a predetermined amount of light to perform an operation test, and the light L5 emitted from the second light emitting element 7b is the inner wall surface of the second light trap portion 10 (fine particle detection). After being reflected by the wall surface of the case forming a space for use and passing through the smoke detecting portion, the light is received by the first light receiving element 8a. Here, if the output light quantity of the second light emitting element 7b is set so that the light quantity of the light received by the first light receiving element 8a becomes equal to the light quantity of the scattered light from the smoke detecting section at the time of fire occurrence, the pseudo light quantity is simulated. Therefore, it is possible to perform the same operation test as when a fire occurs.

Further, if the output light quantity of the second light emitting element 7b is set so that the light quantity of the light received by the first light receiving element 8a becomes a preset value, the output of the first light receiving element 8a By monitoring the above, it is possible to detect the stain in the smoke detecting section, that is, the inner wall surface of the case or the change in the sensitivity of the first light receiving element 8a. Alternatively, by setting the output light amount of the second light emitting element 7b to a preset value and storing the output of the first light receiving element 8a in normal times, the output change of the first light receiving element 8a can be changed. It is possible to monitor and detect a stain in the smoke detecting section or a change in sensitivity of the first light receiving element 8a.

The installation position of the second light emitting element 7b is
On the optical axis of the field of view of the first light receiving element 8a, within the field of view, or the light emitted from the second light emitting element 7b is reflected in the smoke detector to indirectly irradiate the first light receiving element 8a. It suffices if it is located within the region, and if this condition is satisfied, the same effect can be obtained even if it is installed in the immediate vicinity of the first light receiving element 8a. Since the second light emitting element 7b and the second light receiving element are provided apart from each other by 8b, they do not interfere with each other. That is, even if the second light emitting element 7b emits light, the light emission does not affect the second light receiving element 8b.

As the first light emitting element, as shown in FIG. 4, a plurality of light emitting elements 17a are arranged on the circumference of a circle equidistant from the center of the smoke detecting portion and focused on the center of the smoke detecting portion. You may do it. The luminous fluxes emitted from the individual light emitting elements 17a intersect and overlap at the center of the smoke detector (that is, overlap with the air flow path), and the amount of incident light at this portion is increased.
As each light emitting element 17a, an LED having a dull directivity due to a condenser lens is used. This kind of LED
Emits not only the necessary radiation to the front of the LED but also unnecessary light that becomes a noise source to the surroundings because it is not a point light source and the lens has aberrations. Therefore, a pinhole 17b is provided immediately before each LED, and unnecessary radiation is shielded via a plurality of slits 17c.

In each of the above embodiments, an example in which the present invention is applied to an air sampling type scattered light type smoke sensor for detecting smoke by introducing air sucked from the monitoring space through the air sampling tube As described above, the present invention can be similarly applied to a spot-type scattered light type smoke sensor in which smoke naturally enters due to a hot air flow or convection. The present invention can also be applied to a sensor that detects fine particles such as dust contained in the air.

[0025]

As described above, in the particle detection sensor according to the first aspect, the first light emitting element and the first light receiving element are arranged so as to be offset from the facing position by a predetermined angle so as to sandwich the smoke detecting section. In a fine particle detection sensor for detecting fine particles such as dust contained in the smoke or air generated in the case of a fire that has flowed into the smoke detection section, from the first light emitting element to monitor the output light amount of the first light emitting element. A second light receiving element for receiving the emitted light, and a first for preventing the light from the first light emitting element transmitted through the smoke detecting section from being reflected and returning to the smoke detecting section.
Since the second light receiving element is provided in the first light trap section, it is possible to perform highly reliable smoke detection by monitoring the fluctuation of the light amount of the first light emitting element. it can.

In the fine particle detection sensor according to a second aspect, the first light emitting element and the first light receiving element are arranged so as to be sandwiched by the smoke detecting section and displaced from the facing position by a predetermined angle, and flow into the smoke detecting section. A fine particle detection sensor for detecting fine particles such as smoke generated in a fire or dust contained in air, comprising a second light emitting element for irradiating a first light receiving element with a predetermined amount of light in order to perform an operation test, Since the light emitted from the second light emitting element is reflected at least once on the wall surface of the case forming the space for detecting fine particles, the first light receiving element is provided at the position where the reflected light is incident. It is possible to detect smoke with high reliability by monitoring fluctuations in the amount of scattered light due to contamination in the smoke detector.

Further, the second light emitting element is provided with a second light emitting element for preventing the light reflected in the smoke detecting section from directly entering the first light receiving element.
If it is provided in the optical trap portion, the second optical trap portion can prevent stray light from entering the first light receiving element and improve the S / N ratio. Further, a slit-shaped suction side nozzle arranged so as to face the smoke detection section, a slit-shaped exhaust side nozzle arranged so as to face the smoke detection section so as to face the suction side nozzle, a suction side nozzle and an exhaust gas. If a smoke passage having a slit-shaped cross section that is provided with a suction-side air chamber and an exhaust-side air chamber that are respectively connected to the suction-side nozzles and goes from the suction-side nozzle to the exhaust-side nozzle through the smoke detector, It is possible to obtain a high-sensitivity particle detection sensor that is difficult to do.

In the fine particle detection sensor according to the fifth aspect, the first light emitting element and the first light receiving element are arranged so as to be sandwiched by the smoke detecting section and displaced by a predetermined angle from the facing position, and the particles flow into the smoke detecting section. A fine particle detection sensor for detecting fine particles such as smoke or dust contained in the air generated in the case of a fire; a second light emitting element for irradiating a first light receiving element with a predetermined amount of light for performing an operation test; The second light trap portion for preventing the light reflected in the smoke detecting portion from directly entering the first light receiving element, and the second light emitting element is provided in the second light trap portion. , The smoke detection with high reliability can be performed by monitoring the fluctuation of the light amount of the first light emitting element.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing a particle detection sensor according to an embodiment of the present invention.

FIG. 2 is a plan sectional view showing the flow of air in the embodiment of FIG.

FIG. 3 is a front sectional view showing the flow of air in the embodiment of FIG.

FIG. 4 is a side sectional view showing a light emitting unit in another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Suction port 2 Suction side air chamber 3 Suction side nozzle 4 Exhaust side nozzle 5 Exhaust side air chamber 6 Exhaust port 7a 1st light emitting element 7b 2nd light emitting element 8a 1st light receiving element 8b 2nd light receiving element 9th 1 optical trap section 10 2nd optical trap section

Claims (5)

[Claims] 1. The smoke or air generated at the time of a fire or air which has flown into the smoke detecting section by arranging the first light emitting element and the first light receiving element so as to sandwich the smoke detecting section with a predetermined angle offset from the facing position. A fine particle detection sensor for detecting fine particles such as dust contained in the second light receiving element for receiving light emitted from the first light emitting element for monitoring the output light amount of the first light emitting element; A first light trap portion for preventing the light from the first light emitting element transmitted through the second portion from being reflected and returning to the smoke detecting portion, and the second light receiving element as the first light trap. A fine particle detection sensor provided inside the section. 2. The smoke or air generated during a fire, which flows into the smoke detecting section, is arranged such that the first light emitting element and the first light receiving element are displaced from each other by a predetermined angle so as to sandwich the smoke detecting section. A fine particle detection sensor for detecting fine particles such as dust contained in is provided with a second light emitting element that irradiates a first light receiving element with a predetermined amount of light for performing an operation test, and emits light from the second light emitting element. A particle detection sensor, wherein the first light receiving element is provided at a position where the reflected light is incident after the reflected light is reflected at least once on the wall surface of the case forming the space for detecting the particles. 3. The second light emitting element is provided in a second optical trap portion for preventing light reflected in the smoke detecting portion from directly entering the first light receiving element. The particle detection sensor according to claim 2. 4. A slit-shaped suction side nozzle arranged so as to face the smoke detection section, a slit-shaped exhaust side nozzle arranged so as to face the smoke detection section so as to face the suction side nozzle, and a suction side. A suction-side air chamber and an exhaust-side air chamber connected to the nozzle and the exhaust-side nozzle, respectively, to form a smoke passage having a slit-shaped cross-section from the suction-side nozzle through the smoke detector to the exhaust-side nozzle. The fine particle detection sensor according to any one of claims 1 to 3, wherein 5. The first light emitting element and the first light receiving element are arranged so as to sandwich the smoke detecting section with a predetermined angle offset from the facing position, and the smoke or the air generated at the time of fire that flows into the smoke detecting section In a fine particle detection sensor for detecting fine particles such as dust contained in, a second light emitting element that irradiates a first light receiving element with a predetermined amount of light in order to perform an operation test, and the light reflected in the smoke detecting section A second light trap portion for preventing direct incidence on the first light receiving element;
The light-emitting element of 1. is provided in the second optical trap section.