JP2015200629A - Particle detection sensor, dust sensor, smoke detector, air cleaner, ventilator and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle detection sensor capable of precisely detecting fine particles even on a heating system which generates an air flow using a heating device such as heater resistance.SOLUTION: A particle detection sensor 1 includes: a light projection element 10; and a light receiving element 20 for detecting particles contained in a gas by receiving scattered light from a light projection element 10 due to particles in a detection area DA with a light receiving element 20. The particle detection sensor 1 includes: a heating device 50 for heating the gas; and a reflector 40 that reflects scattered light and guides the scattered light to the light receiving element 20.

Description

  The present invention relates to a particle detection sensor and a device including the particle detection sensor, such as a dust sensor, a smoke sensor, an air cleaner, a ventilation fan, or an air conditioner. More specifically, the present invention relates to a light-scattering particle detection sensor that detects particles (aerosol) floating in the atmosphere using scattered light of the particles, and an apparatus such as an air purifier using the same.

  The light scattering particle detection sensor is a photoelectric sensor including a light projecting element and a light receiving element, takes in a gas to be measured, irradiates the light of the light projecting element, and is contained in the gas by the scattered light. It detects the presence or absence of particles. For example, particles such as dust, pollen, and smoke floating in the atmosphere can be detected.

  As this type of light scattering type particle detection sensor, a sensor provided with a light trap at a position facing a light projecting element or a light receiving element is known in order to reduce the generation of stray light (see, for example, Patent Document 1). .

Japanese Patent Laid-Open No. 11-248629

  In recent years, there has been a demand for higher accuracy of particle detection sensors in order to detect fine particles with smaller particle diameters. For example, high accuracy can be obtained by generating a stream of air with a fan and capturing many particles in the particle detection sensor. It is considered to become.

  However, when the fan is provided, the cost of the whole particle detection sensor is increased or the particle detection sensor is increased in size. For this reason, it is conceivable to generate an air flow by low-cost heater resistance (resistance heating).

  However, the method using the heater resistance has a low flow rate and cannot detect fine particles having a small particle size with high accuracy.

  The present invention has been made in view of such problems, and provides a particle detection sensor or the like that can detect fine particles with high accuracy even in a heating method in which an air flow is generated by a heating device such as a heater resistor. With the goal.

  In order to achieve the above object, one aspect of a particle detection sensor according to the present invention includes a light projecting element and a light receiving element, and receives light scattered by the light projecting element due to particles in a detection region by the light receiving element. A particle detection sensor that detects particles contained in a gas by having a heating device that heats the gas and a reflector that reflects the scattered light and guides the scattered light to the light receiving element. Features.

  According to the present invention, fine particles can be detected with high accuracy even in a heating method in which an air flow is generated by a heating device such as a heater resistor.

(A) is a top view of the particle detection sensor according to Embodiment 1 of the present invention, (b) is a front view of the particle detection sensor, (c) is a bottom view of the particle detection sensor, and (d). These are sectional drawings of the same particle detection sensor in an AA line of (a). It is sectional drawing for demonstrating operation | movement of the particle | grain detection sensor when particle | grains do not exist in gas. It is sectional drawing for demonstrating operation | movement of the particle | grain detection sensor in case the particle | grains with a small particle diameter exist in gas. It is sectional drawing for demonstrating operation | movement of the particle | grain detection sensor in case the particle | grains with a large particle diameter exist in gas. It is sectional drawing of the particle | grain detection sensor of a comparative example. It is sectional drawing of the particle | grain detection sensor which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the positional relationship of the reflector in the particle | grain detection sensor which concerns on Embodiment 1 of this invention, a light receiving element, and a detection area. (A) is a top view of the particle detection sensor according to Embodiment 2 of the present invention, (b) is a front view of the particle detection sensor, (c) is a bottom view of the particle detection sensor, and (d). These are sectional drawings of the same particle detection sensor in an AA line of (a). It is a figure for demonstrating the positional relationship of the reflector in the particle | grain detection sensor which concerns on Embodiment 2 of this invention, a light projection element, a light receiving element, and a detection area. It is an expanded sectional view which shows the structure of the 1st light-shielding body periphery in the particle | grain detection sensor which concerns on Embodiment 2 of this invention. It is an expanded sectional view which shows the structure of the 2nd light shielding body periphery in the particle | grain detection sensor which concerns on Embodiment 2 of this invention. It is a figure for demonstrating the optical path of the light which radiate | emits from the light projection element in the particle | grain detection sensor which concerns on Embodiment 2 of this invention, and goes to a detection area. It is sectional drawing which shows schematic structure of the particle | grain detection sensor which concerns on the modification 1 of this invention. It is sectional drawing which shows schematic structure of the particle | grain detection sensor which concerns on the modification of the modification 1 of this invention. It is sectional drawing which shows schematic structure of the particle | grain detection sensor which concerns on the modification 2 of this invention. It is sectional drawing which shows schematic structure of the particle | grain detection sensor which concerns on the modification 3 of this invention. It is sectional drawing which shows schematic structure of the particle | grain detection sensor which concerns on the modification 4 of this invention. It is sectional drawing which shows schematic structure of the particle | grain detection sensor which concerns on the modification of the modification 4 of this invention. It is sectional drawing which shows schematic structure of the particle | grain detection sensor which concerns on the modification 5 of this invention. It is sectional drawing which shows schematic structure of the particle | grain detection sensor which concerns on the modification 6 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. Accordingly, numerical values, shapes, materials, components, arrangement positions and connection forms of components shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements.

  Each figure is a schematic diagram and is not necessarily illustrated strictly. Moreover, in each figure, the same code | symbol is attached | subjected to the substantially same structure, The overlapping description is abbreviate | omitted or simplified.

(Embodiment 1)
First, the configuration of the particle detection sensor according to Embodiment 1 of the present invention will be described with reference to FIG. 1A and 1B are diagrams showing a configuration of a particle detection sensor according to Embodiment 1 of the present invention. FIG. 1A is a top view, FIG. 1B is a front view, FIG. 1C is a bottom view, and FIG. It is sectional drawing in the AA of a). In the present embodiment, the direction from the air discharge hole 36 to the air introduction hole 35 in FIG. 1D is the vertically downward direction (the direction of gravity).

  As shown in FIG. 1, the particle detection sensor 1 according to the present embodiment is a photoelectric sensor including a light projecting element 10 and a light receiving element 20, and a light projecting element using particles in a detection region (light diffusion portion) DA. The light contained in the gas is detected by receiving the scattered light of light 10 from the light receiving element 20. The particle detection sensor 1 in the present embodiment further includes a reflector 40 having a reflecting surface and a heating device 50 that heats gas.

  The light projecting element 10 is a light source (light emitting unit) that emits light of a predetermined wavelength, and is, for example, a solid light emitting element such as an LED or a semiconductor laser. As the light projecting element 10, a light emitting element that emits infrared light, blue light, green light, red light, or ultraviolet light can be used. In this case, you may comprise so that the mixed wave of 2 wavelengths or more may be emitted.

  In addition, it becomes easy to detect a particle | grain with a small particle size, so that the light emission wavelength of the light projection element 10 is short. Moreover, the light emission control system of the light projecting element 10 is not particularly limited, and the light emitted from the light projecting element 10 can be continuous light or pulsed light by DC driving. Moreover, the magnitude | size of the output of the light projection element 10 may be changing temporally.

  The light receiving element 20 is a light receiving unit that receives light, and is an element (photodetector) that receives light and converts it into an electric signal, such as a photodiode, a photo IC diode, a phototransistor, or a high electron multiplier. .

  As shown in FIG. 1D, the light projecting element 10 and the light receiving element 20 are arranged in a housing 30 (case). The housing 30 is configured to hold the light projecting element 10 and the light receiving element 20. In the present embodiment, the light projecting element 10 and the light receiving element 20 are disposed in the housing 30 so that their optical axes intersect.

  In order to increase the light receiving sensitivity of the light receiving element 20, it is preferable to acquire a large amount of forward scattered light among the scattered light of particles in the detection area DA. In this case, the forward scattered light can be easily obtained by matching the optical axis of the light projecting element 10 and the optical axis of the light receiving element 20, but the optical axes of the light projecting element 10 and the light receiving element 20 are simply changed. If they are just matched, the light receiving element 20 will receive direct light from the light projecting element 10 in addition to the forward scattered light, and the particle detection accuracy will be reduced.

  For this reason, in this Embodiment, the optical axis of each of the light projection element 10 and the light receiving element 20 is made to cross | intersect. As an example, the angle formed by the optical axis of the light projecting element 10 and the optical axis of the light receiving element 20 is 60 degrees (120 degrees).

  In this way, by causing the optical axes of the light projecting element 10 and the light receiving element 20 to cross each other, the side scattered light in a portion close to the forward scattered light is not affected by the direct light from the light projecting element 10. Since it can acquire, the fall of the detection accuracy of particle | grains can be suppressed.

  As shown to (a)-(c) of FIG. 1, the external shape of the housing | casing 30 is a flat rectangular parallelepiped as an example. The housing 30 is composed of two members, a first housing portion 30a (lid portion) and a second housing portion 30b. A plurality of lead wires 11, 21, and 51 are exposed from the second housing portion 30b. The lead wires 11, 21, and 51 are electrically connected to the light projecting element 10, the light receiving element 20, and the heating device 50, respectively.

  In the housing 30, a light projecting region 31, which is a space region in which light from the light projecting element 10 is projected, and scattered light generated when the light from the light projecting device 10 hits particles in the detection region DA is guided to the light receiving device 20. For this purpose, a light receiving region 32 (diffuse light introducing portion) that is a space region for the particles, a particle flow path 33 that is a space region through which a gas (such as air) containing particles flows, and a trap portion 34 are provided.

  Each of the light projecting region 31, the light receiving region 32, the particle flow path 33, and the trap part 34 is a space region in the housing 30. The light projection area 31 is a spatial area from the light projecting element 10 to the detection area DA. The light receiving area 32 is a spatial area from the detection area DA to the light receiving element 20.

  For example, as shown in FIG. 1 (d), each of the light projecting region 31, the light receiving region 32, and the trap portion 34 has a substantially cylindrical shape or a substantially rectangular tube shape that is surrounded by the inner surface (inner wall) of the housing 30. The bottomed cylindrical space region has an opening at a connection portion with the particle channel 33. In other words, each of the light projecting region 31, the light receiving region 32, and the trap portion 34 has an opening that opens toward the particle channel 33, and is connected to the particle channel 33 at each opening. In the present embodiment, each opening of the light projecting area 31, the light receiving area 32, and the trap part 34 opens toward the detection area DA.

  The particle flow path 33 is a gas passage region through which a gas introduced into the housing 30 for measuring particles in a gas (such as the atmosphere) is passed. The particle channel 33 is a cylindrical space region having a substantially cylindrical shape or a substantially rectangular tube shape and surrounded by the inner surface (inner wall) of the housing 30 and is a space region including the detection region DA. In the present embodiment, the particle channel 33 includes the entire detection area DA. In the present embodiment, the particle flow path 33 is a straight flow path from the air introduction hole 35 toward the air discharge hole 36, and is connected to the light projecting area 31, the light receiving area 32, and the trap part on the way. Has been.

  Further, the inner surface (wall surface) of the housing 30 in the light projecting region 31, the light receiving region 32, the particle flow path 33, and the trap part 34 is preferably black in order to absorb stray light. For example, the housing 30 is a black resin molded product, and the exposed part has at least a black surface inside. Further, the inner surface of the housing 30 may be configured to absorb stray light by performing a surface treatment such as embossing.

  The detection area DA is an aerosol detection area (aerosol measurement unit) that is an area for detecting particles (aerosol) contained in the gas to be measured. The detection area DA is set so as to exist in the particle flow path 33, and in the present embodiment, the light projection area 31 and the light reception area 32 overlap with the particle flow path 33. Specifically, the detection area DA is an area including an intersection where the optical axis of the light projecting element 10 and the optical axis of the light receiving element 20 intersect. The gas to be measured is guided to the detection area DA through the particle channel 33. The detection area DA is, for example, φ2 mm.

  The trap part 34 reflects that the light that has passed through the detection area DA without hitting the particles in the detection area DA out of the light from the light projecting element 10 is reflected and scattered in the housing 30 and received by the light receiving element 20. It has a structure to prevent. Specifically, the trap unit 34 has an optical trap structure, and has a light absorption structure that prevents light once entering the trap unit 34 from exiting the trap unit 34. For example, the inner surface of the housing 30 in the trap portion 34 is provided with a plurality of black protrusions for multiple reflection and absorption of light. The trap part 34 may have a labyrinth structure.

  In the present embodiment, the trap part 34 (light trap structure) is provided at a position facing the light projecting element 10. Specifically, the opening of the trap portion 34 faces the opening of the light projecting region 31. In the present embodiment, the trap portion 34 is provided only at a position facing the light projecting element 10, but may be provided at a position facing both the light projecting element 10 and the light receiving element 20. However, it may be provided only at a position facing the light receiving element 20. However, when the trap portion 34 is provided only at a position facing the light receiving element 20, it is possible to provide a means such as making the trap portion 34 a through hole so that the light that has once entered the trap portion 34 does not return. Good.

  The housing 30 is provided with an air introduction hole 35 for introducing air into the particle flow path 33 and an air discharge hole (atmospheric discharge hole) 36 for discharging air from the particle flow path 33. Yes.

  The atmosphere introduction hole 35 is an atmosphere supply port (atmosphere inlet) for supplying a gas such as the atmosphere existing outside the particle detection sensor 1 to the inside of the particle detection sensor 1 (particle flow path 33). 30 is the atmospheric inlet.

  On the other hand, the air discharge hole 36 is an air exhaust port (atmosphere outlet) for discharging the air inside the particle detection sensor 1 (particle flow path 33) to the outside of the particle detection sensor 1. Is the exit.

  The air introduction hole 35 is connected to one of the particle flow paths 33, and the air discharge hole 36 is connected to the other of the particle flow paths 33. Thereby, the atmosphere containing the particles (the gas to be measured) is introduced into the casing 30 from the atmosphere introduction hole 35 and flows into the detection area DA through the particle flow path 33, and from the atmosphere discharge hole 36 to the casing 30. Discharged outside. In the present embodiment, the air introduction hole 35 has a larger opening area than the air discharge hole 36 in order to efficiently introduce and exhaust gas into the housing 30.

  In the present embodiment, the light projecting area 31 is provided with a light projecting lens (light emitting lens) 31a. The light projecting lens 31a is disposed in front of the light projecting element 10, and is configured to advance light (projected beam) emitted from the light projecting element 10 toward the detection area DA. That is, the light emitted from the light projecting element 10 reaches the detection area DA via the light projecting lens 31a. The light projection lens 31a is, for example, a transparent resin lens or a glass lens.

  The light projecting lens 31a may be a collimating lens that collimates the light emitted from the light projecting element 10 toward the detection area DA, or the light that collects the light emitted from the light projecting element 10 on the detection area DA. Although a lens may be used, a lens that increases the light intensity of the light projecting element 10 in the detection area DA may be used as the light projecting lens 31a. Further, if the light intensity varies depending on the location in the detection area DA, the intensity of the scattered light varies depending on the location in the detection area DA even if the particles have the same particle size. A lens that makes the light intensity distribution of the element 10 uniform in the entire detection area DA may be used. Further, when the light from the light projecting element 10 is reflected on the wall surface of the housing 30, unnecessary reflected light and scattered light are generated. Therefore, as the light projecting lens 31a, the light from the light projecting element 10 is projected into the light projecting area 31. It is preferable to use a lens that directly reaches the detection area DA without being reflected by the wall surface of the housing 30 in FIG. The light projection lens 31a may not be provided.

  In the present embodiment, the light emitting area 31 is provided with a light emission stop portion 31b. The light emission diaphragm 31b narrows the light of the light projecting element 10 after passing through the light projecting lens 31a to shield unnecessary light and reduce the condensed diameter. The light emission diaphragm 31b is made of resin or the like, and is formed in a predetermined shape on the inner wall of the light projecting region 31. The light emission diaphragm 31b is composed of a plurality of optical diaphragms each having a circular or polygonal opening (slit). In the present embodiment, the light emission stop portion 31 b (optical stop) is formed so as to protrude from the inner wall of the light projecting region 31. The light emission diaphragm 31b (optical diaphragm) is made of resin or the like, and may be integrally formed with the housing 30 or may be separate from the housing 30.

  The reflector 40 (reflecting plate) is a reflecting member that reflects scattered light of the light projecting element 10 by particles in the detection area DA and guides the scattered light to the light receiving element 20. In the present embodiment, the reflector 40 reflects the scattered light of the particles and collects it on the light receiving element 20. More specifically, the reflector 40 reflects the scattered light of the particles toward the light receiving element 20.

  As shown in FIG. 1D, the reflector 40 is provided in the light receiving region 32 in the present embodiment. Specifically, the reflector 40 is a condensing mirror provided along the inner surface of the housing 30 in the light receiving region 32, and the inner surface which is a reflecting surface is a curved surface. As shown in FIG.1 (d), the inner surface of the reflector 40 is a part of rotation surface of a spheroid. That is, the reflector 40 is an elliptical mirror in which the shape of the inner surface (reflecting surface) forms a part of the spheroid, and the cross-sectional shape of the inner surface of the reflector 40 is a part of the ellipse.

  The reflector 40 has an opening that opens toward the particle channel 33. Specifically, the opening of the reflector 40 opens toward the detection area DA. In the present embodiment, the opening of the reflector 40 substantially coincides with the opening of the light receiving region 32. That is, the reflector 40 is provided up to the vicinity of the opening of the light receiving region 32.

  As the reflector 40, the base member itself may be made of a reflective material such as metal so that the surface of the base member itself becomes a reflective surface, or a reflective film that becomes a reflective surface on the surface of a resin or metal base member May be formed.

As the reflection film, a metal reflection film such as aluminum, gold, silver or copper, a mirror reflection film, a dielectric multilayer film, or the like can be used. As the reflective film, a film having a low absorptance and a high reflectance is preferable. Moreover, you may use as a reflecting film what laminated | stacked the thin film thinner than the said aluminum film on the surface of the aluminum film formed by vapor deposition. As the thin film laminated on the aluminum film, for example, an MgF film, a SiO ₂ film, a SiO film, an AlN film, an alumina film, an enhanced reflection film, or the like is used. Thus, by laminating these thin films on the aluminum film, it is possible to suppress deterioration (corrosion and the like) of the aluminum film and improve optical characteristics by optical amplification.

  The heating device 50 is a heater that heats the atmosphere. The heating device 50 functions as an airflow generation device that generates an airflow for promoting the flow of gas flowing in the particle flow path 33. That is, the atmosphere including particles can be easily introduced into the detection area DA by heating the atmosphere with the heating device 50. The heating device 50 is, for example, a low-cost heater resistance.

  As shown in FIG. 1 (d), in the present embodiment, the heating device 50 is disposed in the particle channel 33. That is, the heating device 50 heats the gas in the particle channel 33. The heating device 50 is disposed in the vicinity of the air introduction hole 35.

  The heating device 50 is disposed vertically below the detection area DA. As a result, when the heating device 50 is a heater resistor, when a voltage is applied to the heater resistor, the heater resistor generates heat, the atmosphere around the heater resistor is heated, the density is reduced, and the vertical direction is opposite to gravity. Moving. That is, when the gas in the particle channel 33 is heated by the heating device 50, an upward airflow (upward airflow) can be generated.

  Thus, by heating the gas in the particle channel 33 by the heating device 50, the gas (atmosphere) to be measured can be easily drawn into the housing 30 (particle channel 33). Compared with the case where 50 is not provided, more particles can be taken into the particle detection sensor 1. Therefore, since the number of particles per unit volume in the detection area DA included in the particle flow path 33 can be increased, the sensitivity can be increased.

  Even when the heating device 50 is not operating, the gas can pass through the particle flow path 33 between the air introduction hole 35 and the air discharge hole 36. That is, even when the heating device 50 is not operating, it is possible to detect particles contained in the gas.

  Next, the operation of the particle detection sensor 1 according to the present embodiment will be described with reference to FIGS. 2A, 2B, and 2C. 2A to 2C show the operation of the particle detection sensor when there is no particle in the gas, when there is a particle with a small particle size in the gas, and when there is a particle with a large particle size in the gas, respectively. It is sectional drawing for demonstrating.

  When the heating device 50 is operated to generate an air flow in the particle passage 33, gas is drawn into the particle detection sensor 1 from the atmosphere introduction hole 35, and the gas passes through the particle passage 33 and enters the detection area DA. Led.

  In this case, as shown in FIG. 2A, when there is no particle (aerosol) in the gas introduced into the particle detection sensor 1, that is, when the particle does not flow into the detection area DA, it is emitted from the light projecting element 10. Since the light passes straight through the detection area DA, light scattered by particles is not generated. Therefore, in this case, basically, there is no reaction of the light receiving element 20, so that it can be seen that there are no particles in the gas introduced into the particle detection sensor 1.

  In this case, light that has traveled straight through the detection area DA may be reflected in the housing 30 and enter the light receiving element 20 as stray light. In the present embodiment, since the trap part 34 is provided, the light that passes straight through the detection area DA is attenuated and absorbed by the trap part 34. As a result, it is possible to prevent light that has traveled straight through the detection area DA from entering the light receiving element 20 as stray light.

  In addition, as shown in FIG. 2B, when the particle (aerosol) P1 having a small particle diameter exists in the gas introduced into the particle detection sensor 1, that is, when the particle P1 having a small particle diameter flows into the detection area DA. The light of the light projecting element 10 strikes the particle P1 existing in the detection area DA and is scattered, and the scattered light is reflected directly or by the reflector 40 and enters the light receiving element 20. When light enters the light receiving element 20, there is an output of a predetermined signal, so that it can be seen that particles are present in the gas introduced into the particle detection sensor 1.

  In this case, since the light intensity of the scattered light detected by the light receiving element 20 is relatively small, it can be seen that particles having a small particle diameter exist in the gas introduced into the particle detection sensor 1.

  In addition, as shown in FIG. 2C, when a particle (aerosol) P2 having a large particle diameter exists in the gas introduced into the particle detection sensor 1, that is, when a particle P2 having a large particle diameter flows into the detection area DA. The light of the light projecting element 10 strikes the particles P2 existing in the detection area DA and is scattered, and the scattered light is reflected directly or by the reflector 40 and enters the light receiving element 20. When light enters the light receiving element 20, there is an output of a predetermined signal. In this case as well, it can be seen that particles are present in the gas introduced into the particle detection sensor 1.

  In this case, since the light intensity of the scattered light detected by the light receiving element 20 is relatively high, it can be seen that particles P2 having a large particle size exist in the gas introduced into the particle detection sensor 1.

  In this way, it is possible to detect whether or not particles are contained in the gas introduced into the particle detection sensor 1 by the scattered light from the particles (presence / absence of particles). That is, particles in the gas can be detected.

  Further, the size (particle size) of the particle can be determined based on the size of the signal received by the light receiving element 20, that is, the light intensity of the scattered light from the particle.

Further, each output of the signal detected by the light receiving element 20, that is, each peak of the light intensity of the scattered light by the particles corresponds to each of the particles. The number (amount) of particles in the gas introduced into the gas can also be calculated.

  Next, the effect of the particle detection sensor 1 in this Embodiment is demonstrated using FIG.3 and FIG.4, comparing with the particle detection sensor 100 of a comparative example. FIG. 3 is a cross-sectional view of a particle detection sensor of a comparative example, and FIG. 4 is a cross-sectional view of the particle detection sensor according to Embodiment 1 of the present invention.

  As shown in FIG. 3, in the particle detection sensor 100 of the comparative example, the light receiving region 32 is not provided with a reflector, and a light receiving lens (condensing lens) 140 is provided. Thereby, restrictions by the light receiving lens 140 increase, and for example, it is necessary to make the optical axis of the light receiving lens 140 coincide with the optical axis of the light receiving element 20. Also, the shape of the light receiving lens 140 has a small degree of freedom that can be changed due to its function, and is, for example, symmetrical with respect to the lens optical axis. For these reasons, as shown in FIG. 3, when the light receiving lens 140 is used, the expected angle to the light receiving lens 140 with reference to the detection area DA is reduced.

  Moreover, in the first place, the light collected by the lens cannot take light of 180 ° or more, and it cannot take scattered light from various directions. Furthermore, since the focal point of the lens is the detection area DA, the detection area DA is small.

  Therefore, in the particle detection sensor 100 of the comparative example that collects the scattered light using only the light receiving lens 140, the light receiving sensitivity of the scattered light is low.

  In particular, fine particles having a small particle diameter such as PM2.5 (microparticulate matter) are also present in the particles floating in the gas. In order to detect such fine particles, the particle detection sensor is required to have an accuracy capable of detecting particles having a particle size of 0.3 μm or less, for example.

  In order to improve the particle detection accuracy of the particle detection sensor, for example, a fan may be provided. That is, it is conceivable to improve the detection accuracy of fine particles having a small particle size by increasing the amount of particles entering the particle detection sensor per unit time by increasing the flow of particles by a fan.

  However, when the fan is provided, the cost of the whole particle detection sensor is increased or the particle detection sensor is increased in size.

  On the other hand, instead of providing a fan, it is also conceivable to generate an air flow by providing a heating device such as a heater resistor that is low-cost and space-saving.

  However, in the case of the heating device, the flow velocity is slower than in the case of the fan, and the detection accuracy cannot be increased so much. For this reason, fine particles having a small particle diameter such as PM2.5 cannot be detected with high accuracy.

  On the other hand, the particle detection sensor 1 in the present embodiment includes a reflector 40 for reflecting scattered light from particles in the detection area DA and guiding the scattered light to the light receiving element 20 as shown in FIG. Have.

  As a result, more scattered light generated by particles in the detection area DA can be incident on the light receiving element 20 than in the case of the lens. That is, the reflector 40 has a greater degree of design freedom than the lens, and thus can be shaped so that more scattered light can be guided to the light receiving element 20.

  For example, as shown in FIG. 4, the opening of the reflector 40 can be extended to the limit of the opening of the light receiving region 32, and the expected angle to the reflector 40 based on the detection region DA can be increased. . Moreover, since the shape of the reflector 40 can be determined without making the prospective angle symmetric with respect to the optical axis of the reflector 40 (the optical axis of the light receiving element 20), the shape of the reflector 40 can be freely changed. Can do.

  As described above, in the particle detection sensor 1 according to the present embodiment, compared to the comparative example shown in FIG. 3, the solid angle for collecting scattered light can be increased, so that the light receiving sensitivity of the scattered light can be increased. The detection area DA can be enlarged.

  For this reason, even if the airflow is slow, the particles easily pass through the detection area DA. In particular, in the case of particles having a small particle size, the probability of particles passing through the detection area DA is small in the comparative example shown in FIG. 3, but in this embodiment shown in FIG. Is significantly improved, and the light receiving sensitivity is also increased. Therefore, fine particles having a small particle diameter can be detected with high accuracy.

  As mentioned above, since the particle | grain detection sensor 1 which concerns on this Embodiment is provided with the reflector 40, compared with the case where a lens is provided in the light reception area | region 32, it can make light reception sensitivity high. Thereby, even if it is the airflow of the grade which can be generated with the heating apparatuses 50, such as heater resistance, the particle | grains with a small particle diameter contained in gas can be detected with high precision. Therefore, even in a heating type particle detection sensor using the heating device 50, not only can the particle contained in the gas be dust, pollen, or smoke, but also PM2.5. Even fine particles having a small particle diameter such as (microparticulate matter) can be distinguished.

  Thus, according to the particle detection sensor 1 according to the present embodiment, a highly accurate particle detection sensor can be realized while being low cost and small in size.

  Further, in the present embodiment, the inner surface of the reflector 40 forms a part of the rotation surface of the spheroid. Thereby, most of the scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20, so that the sensitivity can be further increased.

  Here, regarding the reflector 40, the positional relationship among the reflector 40, the light receiving element 20, and the detection area DA and the operation effect thereof will be described in detail with reference to FIG. 5. FIG. 5 is a diagram for explaining the positional relationship among the reflector, the light receiving element, and the detection region in the particle detection sensor according to Embodiment 1 of the present invention.

  As shown in FIG. 5, the reflector 40 in the present embodiment has an inner surface that forms part of the rotational surface of the spheroid, and the cross-sectional shape of the inner surface of the reflector 40 is part of the ellipse. Yes. The reflector 40 is arranged such that one of the two focal points F1 and F2 (first focal point) in the ellipse constituting the spheroid exists in the detection area DA. The light receiving element 20 is disposed in the vicinity of the other focal point F2 (second focal point) of the ellipse.

  Thereby, the scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20 with a small number of reflections (one or several times). That is, attenuation of light due to multiple reflection can be avoided. Therefore, since the light receiving efficiency in the light receiving element 20 can be increased, the sensitivity can be further increased.

  Furthermore, since the light receiving efficiency of the light receiving element 20 can be increased, a small detector or the like can be used as the light receiving element 20. That is, it is not necessary to use a photodetector having a particularly large light receiving surface as the light receiving element 20.

(Embodiment 2)
Next, the configuration of the particle detection sensor 2 according to the embodiment of the present invention will be described with reference to FIG. 6A and 6B are diagrams showing the configuration of the particle detection sensor according to Embodiment 2 of the present invention. FIG. 6A is a top view, FIG. 6B is a front view, FIG. 6C is a bottom view, and FIG. It is sectional drawing in the AA of a). Also in this embodiment, the direction from the air discharge hole 36 to the air introduction hole 35 in FIG.

  As shown in FIG. 6, the particle detection sensor 2 in the present embodiment is a photoelectric sensor that includes a light projecting element 10 and a light receiving element 20 in the same manner as the particle detection sensor 1 in the first embodiment. The light contained in the atmosphere is detected by receiving the scattered light of the light from the light projecting element 10 by the particles in the region (light scattering part) DA by the light receiving element 20.

  The particle detection sensor 2 according to the present embodiment further includes a housing 30, and a reflector 40, a heating device 50, a first light shielding body 61, a second light shielding body 62, and a light projection diaphragm disposed in the housing 30. Unit 71, a light projection counter diaphragm unit 72, a light reception counter diaphragm unit 73, a first protection plate 81, and a second protection plate 82.

  Also in the present embodiment, the optical axes of the light projecting element 10 and the light receiving element 20 are crossed. In the present embodiment, the angle formed by the optical axis of the light projecting element 10 and the optical axis of the light receiving element 20. Is 120 degrees (60 degrees).

  In the present embodiment, the housing 30 includes a light projecting region 31, a light receiving region 32, a particle channel 33, a light projecting trap unit 34a (first trap unit), and a light receiving trap unit 34b (second trap). Part).

  Each of the light projecting area 31, the light receiving area 32, the particle flow path 33, the light projecting trap section 34a, and the light receiving trap section 34b is a space area surrounded by the inner surface (inner wall) of the housing 30. 33 has an opening at the connection portion. Each opening part of the light projection area | region 31, the light reception area | region 32, the light projection trap part 34a, and the light reception trap part 34b is opened toward the detection area DA.

  The inner surface (wall surface) of the housing 30 in the light projecting region 31, the light receiving region 32, the particle flow path 33, the light projecting trap unit 34a, and the light receiving trap unit 34b may be black in order to absorb stray light. For example, the inner surface of the housing 30 can be made a black surface by making the housing 30 a black resin molded product.

  In the present embodiment, the light projection area 31 is provided with a light projection diaphragm section (light emission diaphragm section) 71. The light projection aperture 71 (first aperture) narrows the light after passing through the light projection lens 31a to shield unnecessary light and reduce the light collection diameter. By providing the light projection aperture 71, stray light can be prevented, and the particle detection accuracy can be improved.

  The projection diaphragm 71 is composed of a plurality of optical diaphragms each having a circular or polygonal opening (slit). In the present embodiment, the light projection diaphragm 71 (optical diaphragm) is formed so as to protrude from the inner wall of the light projection area 31. The light projection aperture 71 (optical aperture) is made of resin or the like, and may be integrally formed with the housing 30 or may be separate from the housing 30.

  In addition, an end (end surface) of the aperture of the optical diaphragm in the light projection diaphragm 71 forms an acute angle with two straight lines in a cross section including the optical axis of the optical diaphragm, and includes a surface including one of the two straight lines ( Flat surface or curved surface) is a reflecting surface that reflects incident light in a direction other than the detection area DA. Thereby, since stray light can be prevented, the detection accuracy of particles can be improved.

  The light projecting trap unit 34a and the light receiving trap unit 34b have an optical trap structure, and light that has once entered the light projecting trap unit 34a and the light receiving trap unit 34b is transmitted from the light projecting trap unit 34a and the light receiving trap unit 34b. It has a light absorption structure that does not go out. The light projecting trap unit 34a and the light receiving trap unit 34b, for example, absorb and multi-reflect light that has entered the light projecting trap unit 34a and the light receiving trap unit 34b. By providing the light projecting trap part 34a and the light receiving trap part 34b, stray light in the housing 30 can be absorbed. Thereby, the detection accuracy of particles can be improved.

  Specifically, the light projecting trap part 34a receives and reflects and scatters light that has passed through the detection area DA without hitting the particles in the detection area DA out of the light emitted from the light projecting element 10. It has a structure that prevents the element 20 from receiving light. The light projecting trap part 34a is provided at a position facing the light projecting element 10 across the detection area DA.

  The light projection trap part 34a is provided with a light projection opposite diaphragm part 72 (second diaphragm part). That is, the light projection opposite diaphragm portion 72 is provided on the opposite side of the light projecting element 10 with the detection area DA interposed therebetween. By providing the light projection opposite stop portion 72, stray light can be prevented and particle detection accuracy can be improved.

  The light projection opposite stop 72 includes a plurality of optical stops each having an opening (slit) such as a circle or a polygon. In the present embodiment, the light projection opposite diaphragm portion 72 (optical diaphragm) is formed so as to protrude from the inner wall of the light projection trap portion 34a. The light projection opposite diaphragm portion 72 (optical diaphragm) is made of resin or the like, and may be integrally formed with the housing 30 or may be separate from the housing 30.

  Further, the end (end face) of the aperture of the optical diaphragm in the light projection opposite diaphragm section 72 forms an acute angle with two straight lines in the cross section including the optical axis of the optical diaphragm, and includes one of the two straight lines. (Plane or curved surface) is a reflecting surface that reflects incident light in a direction other than the detection area DA. Thereby, since stray light can be prevented, the detection accuracy of particles can be improved.

  In the present embodiment, a curved surface that guides light to the side opposite to the detection area DA side is formed on the back side of the light projection opposite diaphragm portion 72 in the light projection trap portion 34a. Thereby, it is possible to make it difficult for the light once entering the inside of the light projecting trap part 34a to go out of the light projecting trap part 34a. As a result, stray light can be prevented, so that the particle detection accuracy can be improved.

  On the other hand, the light receiving trap part 34b reflects and scatters the light traveling on the opposite side to the light receiving element 20 (light receiving area 32) among the scattered light of the particles in the detection area DA and receives it by the light receiving element 20. It has a structure which prevents it being done. The light receiving trap part 34b is provided at a position facing the light receiving element 20 across the detection area DA.

  The light receiving trap part 34b is provided with a light receiving opposite stop 73 (third stop). In other words, the light receiving opposite diaphragm portion 73 is provided on the opposite side of the light receiving element 20 with the detection area DA interposed therebetween. By providing the stop portion 73 opposite to the light reception, stray light can be prevented, and the particle detection accuracy can be improved.

  Similarly to the light projection counter diaphragm section 72, the light reception counter diaphragm section 73 is composed of a plurality of optical diaphragms each having an opening (slit) such as a circle or a polygon. In the present embodiment, the light receiving opposite stop portion 73 (optical stop) is formed so as to protrude from the inner wall of the light receiving trap portion 34b. The light receiving opposite diaphragm 73 (optical diaphragm) is made of resin or the like, and may be integrally formed with the housing 30 or may be separate from the housing 30.

  In addition, the end (end surface) of the aperture of the optical diaphragm in the opposite light receiving diaphragm 73 forms an acute angle with two straight lines in a cross section including the optical axis of the optical diaphragm, and includes a surface including one of the two straight lines ( A curved surface or a flat surface is a reflecting surface that reflects incident light in a direction other than the detection area DA. Thereby, since stray light can be prevented, the detection accuracy of particles can be improved.

  In the present embodiment, a curved surface that guides light to the side opposite to the detection area DA side is formed on the back side of the light receiving counter diaphragm portion 73 in the light receiving trap portion 34b. Thereby, it is possible to make it difficult for the light once entering the inside of the light receiving trap part 34b to go out of the light receiving trap part 34b. As a result, stray light can be prevented, so that the particle detection accuracy can be improved.

  Also in the present embodiment, the reflector 40 is disposed in the light receiving region 32. The scattered light of the particles in the detection area DA is guided to the light receiving element 20 by the reflector 40. In the present embodiment, the end of the reflector 40 on the opening side is in contact with the first protective plate 81.

  Here, in the particle detection sensor 2 in the present embodiment, the positional relationship among the reflector 40, the light projecting element 10, the light receiving element 20, and the detection area DA and the optical action thereof will be described in detail with reference to FIG. FIG. 7 is a diagram showing a positional relationship among a reflector, a light projecting element, a light receiving element, and a detection region in the particle detection sensor according to Embodiment 2 of the present invention.

  As shown in FIG. 7, the reflector 40 in the present embodiment is also an elliptical mirror, and is constituted by a spheroid. Similarly to the first embodiment, the reflector 40 has one focal point F1 (first focal point) of the two focal points F1 and F2 in the ellipse constituting the spheroid in the detection area DA. And the other focal point F2 (second focal point) is arranged in the vicinity of the light receiving element 20. That is, the light receiving element 20 is disposed in the vicinity of the focal point F2 in the ellipse.

  As shown in FIG. 7, in the present embodiment, the light from the light projecting element 10 is set to be condensed at the focal point F1 by the light projecting lens 31a. That is, the condensing point of the light emitted from the light projecting lens 31a coincides with the focal point F1. For example, when the light projection lens 31a is a condensing lens such as a convex lens, the focal point of the light projection lens 31a may be made coincident with the focal point F1 of the reflector 40 (elliptical mirror). When the light projecting lens 31a is a collimating lens, the light emitted from the light projecting lens 31a may be condensed at the focal point F1 by the light projecting diaphragm 71.

  Thus, by making the condensing point of the light emitted from the light projecting lens 31a coincide with the elliptical focus F1 of the reflector 40, the light density can be increased, and the scattered light of the particles in the detection area DA. Becomes larger. Therefore, the particle detection accuracy can be improved.

  Returning to FIG. 6D, in the present embodiment, the heating device 50 is disposed between the first light shield 61 and the air introduction hole 35 and is disposed so as to cover the air introduction hole 35. ing. In addition, the air introduction hole 35, the heating device 50, the first light shield 61, the detection area DA, the second light shield 62, and the air discharge hole 36 are arranged so as to exist on the same straight line. Yes.

  The first light shielding body 61 and the second light shielding body 62 shield at least one of light emitted from the heating device 50 (heater light) and light entering the inside from the outside of the particle detection sensor 2 (external light). The light heater light emitted from the heating device 50 includes visible light and infrared light. The first light shielding body 61 and the second light shielding body 62 are integrally formed with the housing 30 using the same material as the housing 30, but may be separate from the housing 30.

  Here, the first light shield 61 and the second light shield 62 will be described in detail with reference to FIGS. 8A and 8B with reference to FIG. FIG. 8A is an enlarged cross-sectional view showing the configuration around the first light shield in the particle detection sensor according to the embodiment of the present invention, and FIG. 8B is an enlarged view showing the configuration around the second light shield in the particle detection sensor. It is sectional drawing.

  As shown in FIGS. 6D and 8A, the first light shield 61 is a heater light shield that shields the heater light, and is disposed between the heating device 50 and the detection area DA. The first light shield 61 in the present embodiment is also an entrance outside light shield that shields light (external light) that enters the inside of the particle detection sensor 2 from the outside through the atmosphere introduction hole 35.

  In the present embodiment, the first light shield 61 is constituted by a first light shield wall 61a and a second light shield wall 61b. The first light shielding wall 61a and the second light shielding wall 61b are arranged side by side in the direction from the heating device 50 toward the detection area DA. Thus, the detection accuracy of the particles can be improved by shielding the heater light and the outside light.

  The first light shielding wall 61 a is disposed so as to face the heating device 50. The second light shielding wall 61b is formed in a substantially box shape so as to surround the first light shielding wall 61a and the side portion of the heating device 50 and to cover a part of the surface of the first light shielding wall 61a on the detection area DA side. Has been. The second light shielding wall 61b has an opening provided at a position facing the detection area DA. The first light shielding wall 61a is provided so as to cover the opening of the second light shielding wall 61b. The first light shielding wall 61a and the second light shielding wall 61b are provided so that the air introduced into the particle detection sensor 2 can be guided to the detection area DA.

  By configuring the first light shield 61 in this way, the particles introduced into the housing 30 from the air introduction hole 35 are caused to flow on both sides of the heating device 50 and the first light shield wall 61a and the second light shield wall 61b. It goes to the detection area DA through the opening of the second light shielding wall 61b through the space between the inner surface and the two. That is, the particle flow path 33 in the first light shielding body 61 is once branched into two near the inlet of the air introduction hole 35 and merged again into one on the surface of the first light shielding wall 61a on the detection area DA side. It has become. Thereby, the atmosphere introduced into the particle detection sensor 2 can be properly guided to the detection area DA while suppressing the heater light and the outside light from entering the detection area DA.

  Further, as shown in FIG. 6D and FIG. 8B, the second light blocking body 62 is an outlet that blocks light (external light) that enters the particle detection sensor 2 from the outside through the air discharge hole 36. It is an external light shield. Thus, by blocking external light, the particle detection accuracy can be improved.

  The second light shielding body 62 has a plurality of shielding walls arranged side by side in the direction from the detection area DA toward the air discharge hole 36. The plurality of shields are configured so that the air inside the particle detection sensor 2 can be discharged from the air discharge hole 36.

  The second light shielding body 62 in the present embodiment is configured by a first light shielding wall 62a, a second light shielding wall 62b, and a third light shielding wall 62c. The first light shielding wall 62 a is disposed so as to face the air discharge hole 36 and cover the air discharge hole 36. The second light shielding wall 62b is formed so as to surround the side portion of the first light shielding wall 62a. In the present embodiment, the third light shielding wall 62 c is a side wall of the reflector 40. Specifically, the third light shielding wall 62c is a side wall of the light receiving region 32 where the reflector 40 is disposed. However, the first light shielding wall 62a, the second light shielding wall 62b, and the third light shielding wall 62c are configured so that the atmosphere inside the particle detection sensor 2 can be discharged from the atmospheric discharge hole 36.

  By configuring the second light blocking body 62 in this way, the atmosphere can be exhausted from the particle detection sensor 2 while suppressing stray light and external light from entering the detection area DA.

  Further, as shown in FIG. 6D, in both the first light shield 61 and the second light shield 62, the scattered light from the particles in the detection area DA has reached the first light shield 61 and the second light shield 62. In such a case, the scattered light is prevented from being reflected on the detection area DA. For example, the first light shield 61 and the second light shield 62 have reflection surfaces that reflect the scattered light of the particles in the detection area DA in directions other than the detection area DA. Thereby, since it is possible to suppress unnecessary light from entering the detection area DA while shielding the heater light and the external light, it is possible to further improve the particle detection accuracy.

  In the present embodiment, in the first light shield 61, the surface of the first light shielding wall 61a on the detection area DA side guides the scattered light to the air introduction hole 35 when the scattered light from the detection area DA is incident. It has become a shape. Specifically, the surface on the detection area DA side of the first light shielding wall 61a is a reflection surface that reflects the scattered light so as to guide it to the air introduction hole 35. For example, as shown in FIG. 8A, the detection area DA It is a curved surface which forms a convex shape toward. That is, the surface of the first light shielding wall 61a on the detection area DA side has a shape that gradually falls vertically downward from the portion (center) facing the second light shielding wall 61b in all directions. Thereby, since stray light can be prevented from entering the detection area DA, the particle detection accuracy can be further improved.

  Further, the surface of the first light shielding wall 61a on the heating device 50 side (in this embodiment, also the surface of the first light shielding wall 61a on the air introduction hole 35 side) is the heater light from the heating device 50 and the air introduction hole. The external light entering the inside of the housing 30 via the 35 is guided to the air introduction hole 35. Specifically, the surface on the heating device 50 side of the first light shielding wall 61a is a reflective surface that reflects the heater light and the outside light so as to guide the air to the atmosphere introduction hole 35. It is a curved surface that forms a convex shape. That is, the surface of the first light shielding wall 61a on the heating device 50 side has a shape that gradually falls downward vertically from the center in all directions. Thereby, since unnecessary light can enter the detection area DA, the particle detection accuracy can be further improved.

  On the other hand, in the second light shielding body 62, the surface on the detection area DA side of the first light shielding wall 62a has a shape that guides the scattered light to the air discharge hole 36 when the scattered light from the detection area DA is incident. ing. Specifically, the surface on the detection area DA side of the first light shielding wall 62a is a reflection surface that reflects the scattered light so as to guide it to the air discharge hole 36. For example, as shown in FIG. 8B, the detection area DA It is a curved surface which forms a convex shape toward. That is, the surface of the first light shielding wall 62a on the detection area DA side has a shape that gradually rises vertically upward from the center in all directions. Thereby, since stray light can be prevented from entering the detection area DA, the particle detection accuracy can be further improved.

  In addition, the surface of the first light shielding wall 62 a on the atmosphere discharge hole 36 side is shaped to guide external light entering the inside of the housing 30 through the atmosphere discharge hole 36 to the atmosphere discharge hole 36. Specifically, the surface on the atmosphere discharge hole 36 side of the first light shielding wall 62a is a reflection surface that reflects external light so as to guide it to the atmosphere discharge hole 36, and in the present embodiment, toward the detection area DA. It is a curved surface having a convex shape. That is, the surface of the first light shielding wall 62a on the atmosphere exhaust hole 36 side has a shape that gradually rises vertically upward from the center in all directions. Thereby, since unnecessary light can enter the detection area DA, the particle detection accuracy can be further improved.

  Returning to FIG. 6D, the first protective plate 81 is a protective member for preventing particles from entering the light projecting region 31. The second protective plate 82 is a protective member for preventing particles from entering the light receiving region 32. Each of the first protective plate 81 and the second protective plate 82 is formed in the housing 30 while particles floating in the atmosphere (dust, pollen, smoke, PM2.5, etc.) are in operation and non-operation of the particle detection sensor 2. When entering, the particles are prevented from entering each of the light projecting region 31 and the light receiving region 32.

  As shown in FIG. 6 (d), the first protective plate 81 is disposed so as to cover an opening (an opening of the light projecting region 31) that becomes a connection portion with the particle flow path 33 in the light projecting region 31. Yes. Similarly, the second protective plate 82 is disposed so as to cover an opening (an opening of the light receiving region 32) serving as a connection portion between the light receiving region 32 and the particle flow path 33. More specifically, the second protective plate 82 covers the opening end surface of the reflector 40. By covering the openings of the light projecting region 31 and the light receiving region 32 with the first protective plate 81 and the second protective plate 82, the light projecting region 31 and the light receiving region 32 become a closed space region. It is possible to prevent particles such as dust, pollen and smoke from entering the interior of 32.

  The 1st protection board 81 and the 2nd protection board 82 are flat transparent plates with uniform thickness, for example, are comprised by transparent resin, such as glass or a polycarbonate, an acryl. As an example, the first protective plate 81 and the second protective plate 82 are transparent plates having a refractive index of 1.5 or less and a thickness of 200 μm or less. The total transmittance of the first protective plate 81 and the second protective plate 82 is, for example, 99% or more if the Fresnel reflection is ignored.

  The surface of the second protective plate 82 is preferably a smooth surface so that the scattered light of the particles is not scattered on the surface of the second protective plate 82. Thereby, the position shift of the optical path of the scattered light by the 2nd protection board 82 can be made small.

  As described in FIGS. 2A, 2B, and 2C, the particle detection sensor 2 in the present embodiment configured as described above detects particles by the same operation as the particle detection sensor 1 in the first embodiment. Can do.

  As described above, the particle detection sensor 2 in the present embodiment includes the reflector 40 as in the particle detection sensor 1 in the first embodiment.

  Thereby, compared with the case where a lens is provided in the light receiving region 32, the light receiving sensitivity can be increased. Therefore, even in a heating type particle detection sensor using the heating device 50, not only can the particle contained in the gas be dust, pollen, or smoke, but also PM2.5. Even fine particles having a small particle diameter such as (microparticulate matter) can be distinguished. Thus, even with the particle detection sensor 2 according to the present embodiment, a highly accurate particle detection sensor can be realized while being low-cost and small.

  Further, in the particle detection sensor 2 in the present embodiment, the first light shield 61 that blocks the heater light emitted from the heating device 50 (heater) and the external light entering the particle detection sensor 2 from the atmosphere introduction hole 35. And a second light shielding body 62 that shields external light that enters the particle detection sensor 2 from the air discharge hole 36.

  Thereby, since heater light and external light can be shielded, the detection accuracy of particles can be improved.

  Moreover, the first light shielding body 61 and the second light shielding body 62 have a shape that suppresses the scattered light of the particles in the detection area DA from being reflected by the first light shielding body 61 and the second light shielding body 62 toward the detection area DA. It has become.

  Thereby, since it is possible to suppress unnecessary scattered light (stray light) from entering the detection area DA while shielding the heater light and the outside light, it is possible to further improve the particle detection accuracy. Therefore, it is possible to realize a sensor with excellent detection accuracy at a low cost.

  Further, as shown in FIG. 6D, in the present embodiment, the reflector 40 (light receiving region 32) is provided so as to extend into the particle flow path 33, and the reflector 40 (light receiving region 32). Is present between the air discharge hole 36 and the first light shielding wall 62a of the second light shielding body 62 and the detection area DA. That is, a part of the reflector 40 (light receiving area 32) is positioned vertically above the detection area DA. The opening of the reflector 40 (light receiving region 32) is covered with a second protective plate 82.

  As a result, the atmosphere containing the particles introduced into the particle detection sensor 2 (housing 30) collides with the second protection plate 82 and temporarily stays in the vicinity of the second protection plate 82. In the present embodiment, since the detection area DA is set so as to be positioned in the vicinity of the second protective plate 82, the atmosphere containing particles once stays in the detection area DA. Therefore, even when air containing different particles is introduced, the speed can be made constant in the vicinity of the detection area DA, so that the particle detection accuracy can be further improved.

  Here, the optical path of the light emitted from the light projecting element 10 in the particle detection sensor according to the present embodiment and traveling toward the detection area DA will be described with reference to FIG. FIG. 5 is a diagram for explaining the optical path.

  As shown in FIG. 9, in the present embodiment, a virtual line 71L that connects the tips of the openings of the plurality of optical apertures in the light projection aperture section 71, and light emitted from the light projecting element 10 and traveling toward the detection area DA. The light line is designed so that the contour line (line) 10L is substantially parallel. Specifically, the virtual line 71L and the contour line 10L of the light emitted from the light projecting element 10 and refracted by the light projecting lens 31a are substantially parallel. That is, the light emitted from the light projecting element 10 and refracted by the light projecting lens 31a passes through the inside of the virtual space region formed by connecting the tips of the openings of the plurality of optical diaphragms in the light projecting diaphragm section 71, and the detection area. Proceed to DA.

  Thereby, since the light outside a design can be contained reliably, it can suppress that a stray light generate | occur | produces in the light projection area | region 31. FIG. Therefore, the particle detection accuracy can be further improved.

  Further, a virtual line 72L that connects the tips of the openings of the plurality of optical stops in the light projection opposite stop 72, and a contour line (line) 10L of light that is emitted from the light projecting element 10 and passes through the detection area DA. The light lines are designed to be substantially parallel. Specifically, the imaginary line 72L and the outline 10L of the light emitted from the light projecting element 10 and entering the light projecting trap part 34a through the detection area DA are substantially parallel. That is, the light that enters the light projecting trap part 34a so as to be emitted from the light projecting element 10 and once converged in the detection area DA by the light projecting lens 31a and then diverge is a plurality of light in the light projecting opposite aperture part 72. The light passes through the inside of a virtual space region formed by connecting the tips of the openings of the optical diaphragms and enters the depth of the light projection trap part 34a.

  Thereby, since the light outside a design can be contained reliably, it can suppress that a stray light generate | occur | produces in the light projection trap part 34a. Therefore, the particle detection accuracy can be further improved.

  The plurality of optical stops in the light receiving opposite stop portion 73 may have the same configuration with respect to the scattered light of the particles in the detection area DA.

  Further, as shown in the figure, in the present embodiment, a light outline (line) 10L emitted from the light projecting element 10 toward the detection area DA and a virtual line 40L connecting the end face of the reflector 40 are approximately. Parallel.

  Thereby, since a sensitivity can be improved, the detection accuracy of particles can be further improved.

(Modification)
Hereinafter, a particle detection sensor according to a modification of the present invention will be described with reference to the drawings. In the modification described below, only the main configuration is illustrated, and other configurations such as a housing can be appropriately changed according to the mode of each modification and are not illustrated.

(Modification 1)
FIG. 10 is a cross-sectional view showing a schematic configuration of a particle detection sensor 1A according to Modification 1 of the present invention.

  As shown in FIG. 10, the particle detection sensor 1A according to the present modification includes a light projecting element 10, a light projecting lens 31a, a light receiving element 20, a reflector 40A, a heating device (not shown), as in the above embodiment. The light receiving element 20 receives the scattered light of the light of the light projecting element 10 due to the particles in the detection area DA, thereby detecting the particles contained in the gas.

  In the reflector 40A in the present modification, the inner surface forms part of the rotational surface of the spheroid, as in the above embodiment. Further, two through holes 41a and 41b are provided on the side of the reflector 40A.

  In this modification, the flow direction of the particle flow path 33 in which the detection area DA is present is a direction perpendicular to the paper surface, and a heating device such as a heater resistance is installed in the particle flow path 33.

  The light projecting element 10 and the light projecting lens 31a are arranged so as to face the through hole 41a, and the optical axis of the light projecting element 10 and the light projecting lens 31a and the central axes of the two through holes 41a and 41b are arranged. Match. The light emitted from the light projecting element 10 passes through the through hole 41a and is projected onto the detection area DA set in the inner part of the reflector 40A. In addition, light that travels straight without hitting particles out of the light from the light projecting element 10 passes through the through hole 41 b and goes out of the reflector 40 </ b> A, and therefore does not enter the light receiving element 20.

  As described above, the particle detection sensor 1 </ b> A according to the present modification includes the reflector 40 </ b> A that reflects the scattered light of the particles in the detection area DA and guides the scattered light to the light receiving element 20.

  As a result, similarly to the above embodiment, even a heating type particle detection sensor using a heating device (not shown) can detect particles with a small particle size contained in gas with high accuracy. .

  Moreover, in this modification, as compared with the above-described embodiment, many portions of the rotation surface of the spheroid are used as the reflection surface of the reflector 40A. Specifically, the reflector 40A uses a portion of the spheroid excluding the portion where the two through holes 41a and 41b and the light receiving element 20 are provided as a reflecting surface.

  As a result, a large amount of scattered light of particles in the detection area DA can be obtained, so that a particle detection sensor with higher accuracy than that of the first embodiment can be realized.

  Also in the particle detection sensor 1A in the present modification, as in the above embodiment, the reflector 40A is arranged so that one of the ellipsoidal focal points exists in the detection area DA, and the light receiving element 20 Is arranged in the vicinity of the other focal point of the ellipse.

  Thereby, since the scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20 with a small number of reflections, a more accurate particle detection sensor can be realized. In addition, since the light receiving efficiency can be increased by arranging the light receiving element 20 in the vicinity of the focal point of the ellipse, a small photodetector or the like can be used as the light receiving element 20.

  In FIG. 10, the two through holes 41a and 41b are provided so that the central axes of the through holes 41a and 41b are orthogonal to the long axis of the ellipse, but the particle detection sensor 1A ′ shown in FIG. As described above, the central axes of the through holes 41a and 41b of the reflector 40A ′ may be provided so as to intersect with the long axis of the ellipse at an angle.

(Modification 2)
FIG. 12 is a cross-sectional view showing a schematic configuration of a particle detection sensor 1B according to Modification 2 of the present invention.

  As shown in FIG. 12, the particle detection sensor 1B according to the present modification includes a light projecting element 10, a light projecting lens 31a, a light receiving element 20, a reflector 40B, a heating device (not shown), as in the above embodiment. The light receiving element 20 receives the scattered light of the light of the light projecting element 10 due to the particles in the detection area DA, thereby detecting the particles contained in the gas.

  In the reflector 40B in the present modification, the inner surface forms part of the rotational surface of the spheroid, as in the above embodiment. The reflector 40B is arranged so that one of the focal points of the ellipse exists in the detection area DA, and the light receiving element 20 is arranged in the vicinity of the other focal point of the ellipse.

  In this modification, unlike the above embodiment, the optical axis of the light projecting element 10, the optical axis of the light receiving element 20, and the rotation axis (optical axis) of the reflector 40B are the same. In the reflector 40B, a through hole 42 is provided at the end of the major axis of the spheroid. The light emitted from the light projecting element 10 passes through the through hole 42 and is projected onto the detection area DA.

  Furthermore, in the present modification, a shielding plate 60 is disposed between the light projecting element 10 and the light receiving element 20. The shielding plate 60 is a shielding plate configured to absorb or cut light directly incident on the light receiving element 20 from the light projecting element 10. Thereby, even if the optical axes of the light projecting element 10 and the light receiving element 20 coincide with each other, the light that travels straight toward the light receiving element 20 without hitting the particles is blocked by the shielding plate 60. Therefore, erroneous detection of particles can be avoided.

  In this modification as well, the flow direction of the particle flow path 33 in which the detection area DA is present is the direction perpendicular to the paper surface, and a heating device such as a heater resistor is installed in the particle flow path 33.

  As described above, the particle detection sensor 1 </ b> B according to the present modification includes the reflector 40 </ b> B that reflects the scattered light of the particles in the detection area DA and guides the scattered light to the light receiving element 20.

  As a result, similarly to the above embodiment, even a heating type particle detection sensor using a heating device (not shown) can detect particles with a small particle size contained in gas with high accuracy. .

  Furthermore, in this modification, as compared with the above-described embodiment, many portions of the rotation surface of the spheroid are used as the reflection surface of the reflector 40B. Specifically, the reflector 40B uses a portion of the spheroid excluding the portion where the one through hole 42 and the light receiving element 20 are provided as a reflecting surface.

  As a result, a large amount of scattered light of particles in the detection area DA can be obtained, so that a particle detection sensor with higher accuracy than that of the first embodiment can be realized. In the present modification, there are more portions that use the rotation surface of the spheroid than Modification 1, and the area of the reflection surface is larger. Therefore, a highly sensitive particle detection sensor can be realized.

  Also in the particle detection sensor 1B in the present modification, as in the above embodiment, the reflector 40B is arranged so that one of the focal points of the ellipse exists in the detection area DA, and the light receiving element 20 is It is arranged near the other focus of the ellipse.

  Thereby, since the scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20 with a small number of reflections, a more sensitive particle detection sensor can be realized. In addition, since the light receiving efficiency can be increased by arranging the light receiving element 20 in the vicinity of the focal point of the ellipse, a small photodetector or the like can be used as the light receiving element 20.

(Modification 3)
FIG. 13 is a cross-sectional view showing a schematic configuration of a particle detection sensor 1C according to Modification 3 of the present invention.

  As shown in FIG. 13, the particle detection sensor 1 </ b> C in the present modification includes a light projecting element 10, a light projecting lens 31 a, a light receiving element 20, a reflector 40 </ b> C, a heating device (not shown), and the like. The light receiving element 20 receives the scattered light of the light of the light projecting element 10 due to the particles in the detection area DA, thereby detecting the particles contained in the gas.

  The reflector 40C in the present modification reflects scattered light from particles in the detection area DA and guides it to the light receiving element 20. However, unlike the above embodiment, the reflector 40C is not a rotating surface of a spheroid, but a rotating parabola. Part of the rotating surface.

  In this modification, the reflector 40C is arranged so that the parabolic focus F exists in the detection area DA, and the light receiving element 20 is positioned on the side opposite to the apex of the parabola across the parabolic focus F. Is arranged. That is, in the present modification, the optical axis of the light projecting element 10, the optical axis of the light receiving element 20, and the rotation axis (optical axis) of the reflector 40C are the same.

  The reflector 40C is provided with a through hole 43 at the top of the rotating parabola. The light emitted from the light projecting element 10 passes through the through hole 43 and is projected onto the detection area DA set in the inner part of the reflector 40C.

  Furthermore, in the present modification, a shielding plate 60 is disposed between the light projecting element 10 and the light receiving element 20. Thereby, even if the optical axes of the light projecting element 10 and the light receiving element 20 coincide with each other, the light that travels straight to the light receiving element 20 without hitting the particles is blocked by the shielding plate 60. Therefore, misdetection of particles can be avoided.

  In this modification as well, the flow direction of the particle flow path 33 in which the detection area DA is present is the direction perpendicular to the paper surface, and a heating device such as a heater resistor is installed in the particle flow path 33.

  As described above, the particle detection sensor 1 </ b> C in the present modification includes the reflector 40 </ b> C that reflects the scattered light of the particles in the detection area DA and guides the scattered light to the light receiving element 20.

  As a result, similarly to the above embodiment, even a heating type particle detection sensor using a heating device (not shown) can detect particles with a small particle size contained in gas with high accuracy. .

  Further, in this modification, the inner surface of the reflector 40C forms a part of the rotation surface of the rotating parabola, and the reflector 40 is arranged so that the focal point F of the parabola exists in the detection area DA, The light receiving element 20 is disposed so as to be located on the opposite side of the apex of the parabola across the parabolic focus F.

  With this configuration, when particles are present in the detection area DA, the light from the light projecting element 10 strikes and scatters the particles in the detection area DA, and the scattered light is reflected by the reflector 40C and becomes parallel light. Incident. Accordingly, a large amount of scattered light generated by the particles in the detection area DA can be obtained, and the scattered light can be incident on the light receiving element 20 with a small number of reflections, so that a highly sensitive particle detection sensor can be realized.

  Thereby, since the scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20 with a small number of reflections, a more sensitive particle detection sensor can be realized.

  In this modification, since the light reflected by the reflector 40C spreads as parallel light, the light receiving surface of the light receiving element 20 is enlarged or the lens that covers the light receiving surface of the light receiving element 20 is enlarged to produce parallel light. It is preferable to configure so that most of the light can be received by the light receiving element 20.

(Modification 4)
FIG. 14 is a cross-sectional view showing a schematic configuration of a particle detection sensor 1D according to Modification 4 of the present invention.

  As shown in FIG. 14, the particle detection sensor 1D in the present modification includes a light projecting element 10, a light projecting lens 31a, a light receiving element 20, a reflector 40D, and a heating device (not shown), as in the third modification. The light receiving element 20 receives the scattered light of the light projecting element 10 due to the particles in the detection area DA, and detects particles contained in the gas.

  The reflector 40D in the present modification reflects light scattered by particles in the detection area DA and guides it to the light receiving element 20, and the inner surface forms part of the rotation surface of the paraboloid as in the third modification. Yes. Further, two through holes 44a and 44b are provided on the side of the reflector 40D.

  The light projecting element 10 and the light projecting lens 31a are arranged so as to face the through hole 44a, and the optical axis of the light projecting element 10 and the light projecting lens 31a and the central axes of the two through holes 44a and 44b are arranged. Match. The light emitted from the light projecting element 10 passes through the through hole 44a and is projected onto the detection area DA set in the inner part of the reflector 40D. Further, light that travels straight without hitting the particles out of the light from the light projecting element 10 passes through the through hole 44b and goes out of the reflector 40D, and therefore does not enter the light receiving element 20.

  Also in the present modification, the reflector 40D is arranged so that the parabolic focus F exists in the detection area DA, and the light receiving element 20 is located on the opposite side of the parabola from the top of the parabola. Is arranged.

  In this modification as well, the flow direction of the particle flow path 33 in which the detection area DA is present is the direction perpendicular to the paper surface, and a heating device such as a heater resistor is installed in the particle flow path 33.

  As described above, the particle detection sensor 1D according to the present modification includes the reflector 40D that reflects the scattered light of the particles in the detection area DA and guides the scattered light to the light receiving element 20.

  As a result, similarly to the above embodiment, even a heating type particle detection sensor using a heating device (not shown) can detect particles with a small particle size contained in gas with high accuracy. .

  Further, in the present modification, as in the modification 3, the reflector 40D formed of the rotation surface of the rotating parabola is arranged so that the focal point F of the parabola exists in the detection area DA, and the light receiving element 20 is It is arranged so as to be located on the side opposite to the apex of the parabola across the focal point F of the parabola.

  As a result, similarly to the third modification, the scattered light of the particles in the detection area DA is reflected by the reflector 40D and becomes parallel light and enters the light receiving element 20, so that the scattered light generated by the particles in the detection area DA is reduced. A large amount can be obtained, and the scattered light can be incident on the light receiving element 20 with a small number of reflections. Therefore, a highly sensitive particle detection sensor can be realized.

  In this modification as well, since the light reflected by the reflector 40D spreads as parallel light, the light receiving surface of the light receiving element 20 is increased or the lens covering the light receiving surface of the light receiving element 20 is increased to generate parallel light. It is preferable to configure so that most of the light can be received by the light receiving element 20. Or you may arrange | position the condensing lens 70 in front of the light receiving element 20 like particle | grain detection sensor 1D 'shown by FIG.

(Modification 5)
FIG. 16 is a cross-sectional view showing a schematic configuration of a particle detection sensor 1E according to Modification 5 of the present invention.

  As shown in FIG. 16, the particle detection sensor 1E according to the present modification includes a light projecting element 10, a light receiving element 20, a reflector 40, and a heating device (not shown), as in the above embodiment. By detecting the scattered light of the light projecting element 10 by the particles in the detection area DA by the light receiving element 20, the particles contained in the gas are detected.

  Also in this modified example, as in the above embodiment, the reflector 40 formed of the rotation surface of the spheroid is arranged so that one focus of the ellipse exists in the detection area DA, and the light receiving element 20 is arranged in the vicinity of the other focus of the ellipse.

  And particle detection sensor 1E in this modification is further provided with auxiliary reflector 40E. The auxiliary reflector 40E reflects the scattered light that does not go to the reflector 40 out of the scattered light from the particles in the detection area DA toward the reflector 40. The auxiliary reflector 40E is, for example, a reflection mirror having a concave curved surface with a predetermined shape.

  In this modification as well, the flow direction of the particle flow path 33 in which the detection area DA is present is the direction perpendicular to the paper surface, and a heating device such as a heater resistor is installed in the particle flow path 33.

  As described above, the particle detection sensor 1E according to the present modification includes the reflector 40 that reflects the scattered light of the particles in the detection area DA and guides the scattered light to the light receiving element 20 as in the above embodiment. .

  As a result, similarly to the above embodiment, even a heating type particle detection sensor using a heating device (not shown) can detect particles with a small particle size contained in gas with high accuracy. .

  Furthermore, in this modification, since the auxiliary reflector 40E is provided, the scattered light that does not go to the reflector 40 among the scattered light by the particles in the detection area DA can be reflected toward the reflector 40.

  As a result, a large amount of scattered light from the particles in the detection area DA can be obtained, and a highly sensitive particle detection sensor can be realized.

  Further, in the particle detection sensor 1E in the present modification, the reflector 40 is arranged so that one of the ellipsoidal focal points exists in the detection area DA, as in the above-described embodiment. It is arranged near the other focus of the ellipse.

  Thereby, since the scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20 with a small number of reflections, a more sensitive particle detection sensor can be realized. In addition, since the light receiving efficiency can be increased by arranging the light receiving element 20 in the vicinity of the focal point of the ellipse, a small photodetector or the like can be used as the light receiving element 20.

(Modification 6)
FIG. 17 is a cross-sectional view showing a schematic configuration of a particle detection sensor 1F according to Modification 6 of the present invention.

  As shown in FIG. 17, the particle detection sensor F in this modification includes a light projecting element 10, a light receiving element 20, a reflector 40F, and a heating device (not shown), as in the above embodiment. By detecting the scattered light of the light projecting element 10 by the particles in the detection area DA by the light receiving element 20, the particles contained in the gas are detected. Also in this modification, the flow channel direction of the particle flow channel (not shown) in which the detection area DA exists is the direction perpendicular to the paper surface.

  The reflector 40F in the present modification reflects light scattered by particles in the knowledge area DA and guides it to the light receiving element 20, and is an aggregate of a plurality of micromirrors each having a curved surface or a flat surface. The inner surface of the reflector 40F has a shape that forms a part of the rotation surface of a substantially parabolic paraboloid as a whole. That is, instead of a reflector having a continuous smooth curved surface as in the above-described embodiments and modifications, a reflector 40F in which each inner surface is configured by a plurality of microscopic mirrors having a curved surface shape or a planar shape may be used. .

  In this modification as well, the flow direction of the particle flow path 33 in which the detection area DA is present is the direction perpendicular to the paper surface, and a heating device such as a heater resistor is installed in the particle flow path 33.

  As described above, the particle detection sensor 1F according to the present modification includes the reflector 40F that reflects the scattered light of the particles in the detection area DA and guides the scattered light to the light receiving element 20 as in the above embodiment. .

  As a result, similarly to the above embodiment, even a heating type particle detection sensor using a heating device (not shown) can detect particles with a small particle size contained in gas with high accuracy. .

  Also in this modified example, the inner surface of the reflector 40F forms a part of the rotation surface of the substantially spheroid, and the reflector 40F is arranged so that one focus of the ellipse exists in the detection area DA. The light receiving element 20 is disposed in the vicinity of the other focal point of the ellipse.

  Thereby, since the scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20 with a small number of reflections, a highly sensitive particle detection sensor can be realized. In addition, since the light receiving efficiency can be increased by arranging the light receiving element 20 in the vicinity of the focal point of the ellipse, a small photodetector or the like can be used as the light receiving element 20.

(Modification 7)
Each particle detection sensor in the embodiment and the modification can be mounted on a dust sensor. For example, when the dust sensor detects dust particles in the atmosphere by a built-in particle detection sensor, the dust sensor notifies the detection of dust by sound or light or displays it on a display unit. Thus, each particle detection sensor in the above-mentioned embodiment and modification can be applied to a dust sensor.

(Modification 8)
Moreover, each particle | grain detection sensor in the said embodiment and modification can be mounted in a smoke sensor. For example, when the smoke detector detects smoke particles in the atmosphere by a built-in particle detection sensor, the smoke detector notifies the display of the smoke by sound or light or displays it on the display unit. Thus, each particle detection sensor in the above embodiment and modification can be applied to a smoke detector.

(Modification 9)
Moreover, each particle | grain detection sensor or the said dust sensor in the said embodiment and modification can be mounted in an air cleaner, a ventilation fan, or an air conditioner. For example, when the air cleaner, the ventilation fan, or the air conditioner detects dust particles in the atmosphere by the built-in particle detection sensor, it may simply display that the dust has been detected or activate the fan. The fan may be controlled such as changing the rotation speed of the fan. Thus, each particle detection sensor or dust sensor in the above-described embodiments and modifications can be applied to a device having a fan such as an air purifier, a ventilation fan, or an air conditioner.

(Other variations)
As described above, the particle detection sensor and the device including the particle detection sensor according to the present invention have been described based on the embodiments. However, the present invention is not limited to the above-described embodiments.

  For example, in the above-described embodiment and modification, the inner surface of the reflector is a part of the surface of the spheroid or the rotation parabola. However, the present invention is not limited to this. It can be. In this case, the conic curve may be selected from an ellipse, a parabola and a hyperbola instead of a circle. That is, the inner surface of the reflector is preferably a part of a spheroid, rotating parabola, or rotating hyperbolic curved surface (rotating surface) rather than a spherical curved surface (spherical surface). When the inner surface of the reflector is spherical, if diffuse reflection is used like an integrating sphere, scattered light is reflected (multiple reflection) and attenuated many times, so that light does not enter the light receiving element 20 so much. For example, in the case of a sphere, only about 1/100 is received compared to the case of a spheroid.

  Moreover, in the said embodiment and modification, although the reflector was arrange | positioned in the light reception area | region 32, you may arrange | position a lens in the light reception area | region 32 instead of a reflector. For example, a condensing lens that collects the scattered light of particles in the detection area DA on the light receiving element 20 may be disposed in the light receiving area 32.

  Moreover, in the said embodiment and modification, although the flow path direction (direction where the gas of measurement object flows) of the particle flow path 33 is made into the up-down direction (vertical direction) of a paper surface, it is good also as a paper surface perpendicular | vertical direction. That is, in the above embodiment, the flow channel axis of the particle flow channel 33 is set to exist on a plane through which each optical axis of the light projecting element 10 and the light receiving element 20 passes, but so as to be orthogonal to the plane. It may be set.

  In the second embodiment, the first light shield 61 shields both the heater light and the external light. However, the first light shield 61 may be configured to shield only one of them. In this case, when the first light shield 61 is a heater light shield that shields only the heater light, an entrance external light shield that shields the external light from the air introduction hole 35 may be additionally provided. Alternatively, when the first light shield 61 is an entrance external light shield that shields only the external light from the air introduction hole 35, a heater light shield that shields the heater light may be additionally provided.

  In the above embodiment and salute, the medium containing particles is the atmosphere (air), but may be a medium other than the atmosphere (liquid such as water).

  In addition, the embodiment can be realized by arbitrarily combining the components and functions in each embodiment without departing from the scope of the present invention, or a form obtained by subjecting each embodiment to various modifications conceived by those skilled in the art. Forms are also included in the present invention.

DESCRIPTION OF SYMBOLS 1, 2 Particle detection sensor 10 Light projecting element 20 Light receiving element 30 Case 31 Light projecting area 32 Light receiving area 33 Particle flow path 34 Trap part 34a Light projecting trap part 34b Light receiving trap part 35 Atmospheric introduction hole 36 Atmospheric discharge hole 40 Reflector 50 Heating device 61 First light shield (light shield)
61a First light shielding wall 61b Second light shielding wall 62 Second light shielding body (light shielding body)
71 Light-projecting diaphragm 72 Light-projecting opposite diaphragm 73 Light-receiving opposite diaphragm

Claims (31)

A particle detection sensor comprising a light projecting element and a light receiving element, and detecting particles contained in a gas by receiving scattered light of the light of the light projecting element due to particles in a detection region by the light receiving element,
A heating device for heating the gas;
A particle detection sensor comprising: a reflector that reflects the scattered light and guides the scattered light to the light receiving element. The particle detection sensor according to claim 1, wherein the reflector focuses the scattered light on the light receiving element. The particle detection sensor according to claim 1, wherein the reflector reflects the scattered light toward the light receiving element. The particle detection sensor according to claim 1, wherein an inner surface of the reflector is a curved surface. The particle detection sensor according to any one of claims 1 to 3, wherein an inner surface of the reflector is a part of a rotating surface of a conical curved rotating body. The particle detection sensor according to claim 5, wherein the conical curve is an ellipse, a parabola, or a hyperbola. The conic curve is an ellipse;
The reflector is arranged so that one focal point of the ellipse exists in the detection area;
The particle detection sensor according to claim 5, wherein the light receiving element is disposed in the vicinity of the other focal point of the ellipse. And a light projecting lens disposed in front of the light projecting element,
The particle detection sensor according to claim 7, wherein a condensing point of light emitted from the light projecting lens coincides with the one focus of the ellipse. The conic curve is a parabola,
The reflector is arranged such that the focus of the parabola is in the detection area;
The particle detection sensor according to claim 5, wherein the light receiving element is arranged at a position opposite to the apex of the parabola with the focal point of the parabola interposed therebetween. The particle detection sensor according to claim 1, wherein the reflector is disposed in a light receiving region that is a spatial region for guiding the scattered light to the light receiving element. A particle region that is a space region including the detection region and a space region through which a gas including particles flows,
The light receiving region has an opening that opens toward the particle flow path,
The reflector has an opening that opens toward the particle channel,
The particle detection sensor according to claim 10, wherein the opening of the light receiving region and the opening of the reflector substantially coincide with each other. Furthermore, the particle | grain detection sensor of any one of Claims 1-11 which has a light projection stop provided in the light projection area | region which is the space area | region where the light of the said light projection element is light-projected. The projection diaphragm is an optical diaphragm having an opening,
The end of the aperture of the optical diaphragm forms an acute angle by two straight lines in a cross section including the optical axis of the optical diaphragm,
The particle detection sensor according to claim 12, wherein the surface including one of the two straight lines is a reflection surface that reflects incident light in a direction other than the detection region. The projection diaphragm unit is composed of a plurality of optical diaphragms each having an opening,
14. The particle detection according to claim 12, wherein an imaginary line connecting tips of openings of the plurality of optical diaphragms and a contour line of light emitted from the light projecting element and directed to the detection region are substantially parallel. Sensor. Furthermore, the particle | grain detection sensor of any one of Claims 1-14 which has a light projection opposite stop part provided in the other side of the said light projection element on both sides of the said detection area | region. The light projection opposite stop portion is an optical stop having an opening,
The end of the aperture of the optical diaphragm forms an acute angle by two straight lines in a cross section including the optical axis of the optical diaphragm,
The particle detection sensor according to claim 15, wherein the surface including one of the two straight lines is a reflection surface that reflects incident light in a direction other than the detection region. The light projection opposite stop portion comprises a plurality of optical stops each having an opening,
17. The particle according to claim 15, wherein an imaginary line connecting tips of openings of the plurality of optical diaphragms and a contour line of light emitted from the light projecting element and passing through the detection region are substantially parallel. Detection sensor. Furthermore, it has a light projecting trap part that absorbs light of the light projecting element that has passed through the detection region,
The particle detection sensor according to any one of claims 15 to 17, wherein the light projection opposite diaphragm portion is provided in the light projection trap portion. The particle detection sensor according to claim 18, wherein a curved surface that guides light to a side opposite to the detection region side is formed on a back side of the light projection opposite diaphragm portion in the light projection trap unit. Furthermore, the particle | grain detection sensor of any one of Claims 1-19 which has a diaphragm part opposite to the light reception provided in the other side of the said light receiving element on both sides of the said detection area | region. The light receiving counter diaphragm is an optical diaphragm having an aperture;
The end of the aperture of the optical diaphragm forms an acute angle by two straight lines in a cross section including the optical axis of the optical diaphragm,
The particle detection sensor according to claim 20, wherein the surface including one of the two straight lines is a reflection surface that reflects incident light in a direction other than the detection region. Furthermore, it has a light receiving trap part that absorbs light traveling on the opposite side of the light receiving element,
The particle detection sensor according to claim 20, wherein the light receiving counter diaphragm is provided in the light receiving trap part. The particle detection sensor according to claim 22, wherein a curved surface that guides light to a side opposite to the detection region side is formed on a back side of the light reception opposite diaphragm portion in the light reception trap unit. The particle detection sensor according to any one of claims 1 to 23, wherein a contour line of light emitted from the light projecting element and traveling toward the detection region is substantially parallel to a virtual line connecting the end faces of the reflector. Furthermore, the particle | grain detection sensor of any one of Claims 1-24 which has an auxiliary reflector which reflects the scattered light which does not go to the said reflector toward the said reflector. The particle detection sensor according to claim 1, wherein the reflector is an assembly of a plurality of micromirrors each having a curved surface or a flat surface. A dust sensor equipped with the particle detection sensor according to claim 1. A smoke detector equipped with the particle detection sensor according to any one of claims 1 to 26. An air cleaner equipped with the particle detection sensor according to any one of claims 1 to 26 or the dust sensor according to claim 27. A ventilation fan equipped with the particle detection sensor according to any one of claims 1 to 26 or the dust sensor according to claim 27. An air conditioner equipped with the particle detection sensor according to any one of claims 1 to 26 or the dust sensor according to claim 27.

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