JP2011102710A - Light scattering particle detector and fire alarm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain stable detection accuracy by suppressing an influence of scattered light (stray light). <P>SOLUTION: In a lower case 33 formed by two-dividing a chamber case including labyrinth structure into upper and lower portions, a light-emitting element 35 and a light receiving element 36 are disposed at an outer peripheral section of a baseplate 34 at an angle of 120 degrees mutually while directing the center of the baseplate 34. Then, the height of the light axis of the light-emitting element 35 is made equal to that of the light axis of the light receiving element 36. A height "h" of a junction surface of a vertical rib 37A of an upper case 32 and a vertical rib 37 of a lower case 33 from the baseplate 34 is made different from a height "H" of the light axis of the light-emitting element 35 and the light receiving element 36, thus preventing emission light from the light-emitting element 35 from impinging on the junction surface of the vertical rib 37A of the upper case 32 and the vertical rib 37 of the lower case 33 of which the shape is not stable due to a variation of manufacturing, suppressing the generation of scattered light (stray light) or the like, and obtaining the stable detection accuracy of fine particles. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a light scattering particle detection device including a light emitting element and a light receiving element, and a fire alarm using the light scattering particle detection device.

  As a light scattering type particle detection device suitable for use in an air cleaner, smoke detector, or the like, a “light scattering type” disclosed in Japanese Patent Laid-Open No. 11-248629 (Patent Document 1) as shown in FIG. There is a “particle detection sensor”. 8 (a) is an exploded perspective view, and FIG. 8 (b) is a longitudinal sectional view showing light traveling inside.

  In the light scattering type particle detection sensor, as shown in FIG. 8, an optical chamber 2 is formed by a hollow rectangular case 1. The case 1 is composed of a base 1a having a rectangular box shape with one side opened, and a cover 1b for closing the opening of the base 1a. Then, the light projecting element 3 and the light projecting lens 4 are provided in the upper left corner of the case 1 in FIG. 8B, and the optical axis of the light projecting beam is disposed toward the lower right corner that is the diagonal position. Further, the light receiving element 5 and the light receiving lens 6 are provided at the upper right corner of the case 1 in FIG. 8B, and the optical axis of the light receiving element 5 is disposed toward the lower left corner at the diagonal position. That is, the light projecting element 3 and the light receiving element 5 are disposed so that their optical axes intersect each other.

  In the case 1, a light projecting element composed of an aperture 7 for limiting the light projecting area, an aperture 8 for limiting the light receiving area, and a plurality of ribs for suppressing stray light projected from the light projecting element 3. The light trap A on the 3 side and the light trap B on the light receiving element 5 side and the inlet 9 which is a hole for introducing floating fine particles such as smoke and dust into the optical chamber 2 are integrally formed.

  A portion where the optical axes of the light projecting element 3 and the light receiving element 5 intersect with each other is a detection region A, and the inflow port 9 is provided in accordance with the position of the detection region A. Then, the light receiving element 5 receives the light scattered by the light emitted from the light projecting element 3 hitting the suspended particles introduced from the inlet 9 and existing in the detection region a. Thus, the presence or absence of suspended particles is detected based on the amount of light incident on the light receiving element 5.

  In the optical chamber 2, when the emitted light is repeatedly reflected on the inner wall surface and returns to the detection region a as stray light, the amount of light received by the light receiving element 5 when there is no floating particle in the detection region a is the amount of the stray light. Increase by minutes. Therefore, it becomes difficult to detect a minute change in the amount of received light when there is a suspended particle in the detection region a and when there is no suspended particle. In other words, the sensitivity of the light-scattering particle detection sensor decreases so that the suspended particles cannot be detected unless the amount of scattered light scattered by the suspended particles increases as the number of suspended particles introduced into the detection area a increases. It will be done.

  In addition, when a foreign substance adheres to the wall surface of the optical chamber 2, the amount of stray light also varies because the light reflection direction at that location varies. Therefore, there is a possibility that the operation of the light scattering type particle detection sensor becomes unstable such as a decrease in sensitivity.

  In order to suppress the influence of the stray light as described above, in the present light scattering type particle detection sensor, the stray light entering the detection region A is detected by the optical traps A and B and the apertures 7 and 8 formed of a plurality of ribs. It has a complex structure that suppresses it.

  In the base 1a of the case 1 configured as described above, the other side surface (that is, the bottom surface of the base 1a having a rectangular box shape) facing the one side provided with the opening closed by the cover 1b is provided. On the outer surface, the light projecting element 3 and the light receiving element 5, a drive circuit for the light projecting element 3, a processing circuit for processing an output signal from the light receiving element 5, and a control circuit for controlling the operation of the light scattering particle detection system Etc. are mounted.

  Further, as a light scattering type particle detection apparatus as described above, there is a “floating particle detection apparatus” as shown in FIG. 9 disclosed in Japanese Patent Laid-Open No. 2003-98083 (Patent Document 2). 9A is a plan view in the detection space, and FIG. 9B is a cross-sectional view taken along the line AA ′ in FIG. 9A.

  As shown in FIG. 9, the floating particle detection apparatus includes a light emitting element 11 that irradiates light to a detection space, a light receiving element 12 that receives scattered light due to floating particles out of the light emitted from the light emitting element 11, and at least The circuit board 13 which mounts the circuit part which drives the light emitting element 11 with the light emitting element 11 and the case 14 which forms the detection space which introduce | transduces floating particulates inside are comprised. In the detection space, the optical axes A1 and A2 of the light emitting element 11 and the light receiving element 12 are arranged as parallel optical axes having a predetermined angle and parallel to the circuit board 13.

  The light emitting element 11 is mounted on the circuit board 13 so that the optical axis thereof is substantially vertical, and an aperture (not shown) that blocks light at the periphery of the irradiation region is interposed on the upper part of the light emitting element 11 to vertically A prism body 15 is provided that bends so that the optical axis becomes the parallel optical axis A1. The light receiving element 12 is mounted on the circuit board 13 so that the optical axis thereof is substantially vertical, and a convex lens 16 is integrally formed on the side surface of the resin outer shell also serving as a sealing body. Above the convex lens 16 is provided a condensing prism body 17 that bends so that its vertical optical axis becomes the parallel optical axis A2.

  The case 14 has a substantially cylindrical shape. A labyrinth portion 19 having a plurality of substantially vertical ribs protruding from the outer peripheral portion of the upper plate 18 so as to prevent smoke from flowing in and prevent external light from entering the upper plate 18 is provided. On the opposite lower surface side, a lower plate 20 that also serves as a decorative cap is provided (however, in FIG. 9B, the vertical position in the attached state is inverted). That is, the case 14 is formed so that smoke can pass in the lateral direction and flow into the detection space in FIG. 9B.

  In addition, an optical trap 21 provided with a plurality of box-shaped vertical ribs is provided at a location intersecting the parallel optical axis A1 of the light emitting element 11 in the case 14. Then, the light emitted from the light emitting element 11 and bent by the prism body 15 provided at the upper portion and parallel to the circuit board 13 is converged and absorbed by the inclined surface between the vertical ribs of the optical trap 21, and the case 14. The stray light inside is reduced.

  Also in this suspended particulate detector, the light emitting element 11 and the light receiving element 12 have a plane view angle formed by the parallel optical axes A1 and A2 of about 100 degrees, and the parallel optical axes A1 and A2 are in the detection space. Are arranged so that the smoke sensing area that senses smoke is near the approximate center of the detection space.

  However, the conventional light scattering type particle detection device such as the light scattering type particle detection sensor disclosed in Patent Document 1 and the suspended particle detection device disclosed in Patent Document 2 have the following problems. .

  That is, as shown in FIGS. 8 and 9, the conventional light scattering type particle detection apparatus includes a case having a complicated optical structure including an aperture, a light trap, a rib and the like as a light projecting element, a light receiving element, and a circuit. It is arranged so as to cover the printed circuit board on which the component is mounted, and is further sealed by a case cover serving as an upper lid.

  In such a configuration, in order to accommodate the light projecting element and the light receiving element mounted on the printed board in the case having the optical structure, the light projecting element and the light receiving element are accommodated in the case. An opening for inserting the element from the lower side needs to be provided in the case. This opening is provided with a suitable margin in consideration of variations in manufacturing part size and arrangement positioning accuracy. Therefore, dust or the like generated in the manufacturing process may enter the optical chamber (the optical chamber 2 and the detection space) from a margin (gap) of the opening during manufacturing. However, since the light scattering type particle detector is a device that detects smoke and dust entering the detection space, if dust adheres to the optical chamber, the detection sensitivity of fine particles is affected by the scattered light from the dust. There is a problem such as lowering or making detection impossible.

  Moreover, the case provided with the optical structure has a certain height in order to ensure the variation likelihood of the optical system. When mounting an optical component such as a lens or an aperture in such a case, it is necessary to insert and mount the optical component to a deep position in the height direction in the case, and the optical axis is aligned in the mounting as well. Therefore, there is a problem that a high manufacturing technique is necessary.

JP-A-11-248629 JP 2003-98083 A

  Accordingly, an object of the present invention is to provide a light-scattering particle detection device capable of simplifying manufacturing, suppressing the influence of dispersed light (stray light) and obtaining stable detection accuracy, and the light-scattering particle detection It is providing the fire alarm using an apparatus.

In order to solve the above problems, the light scattering particle detector of the present invention is:
A chamber case that has a labyrinth structure composed of a plurality of vertical ribs that allows the introduction of suspended particulates from the outside while preventing the entry of ambient light, and that can be divided into an upper case and a lower case ,
A light emitting device installed in the lower case;
A light receiving element that is installed in the lower case and receives light emitted from the light emitting element and reflected by suspended fine particles in the chamber case;
The chamber case is mounted, and includes at least a circuit board on which a circuit that performs processing of a signal from the light receiving element and operation control of the light emitting element and the light receiving element is mounted,
The height from the installation surface of the light emitting element and the light receiving element in the optical axis of the light emitting element and the optical axis of the light receiving element are the same,
The plurality of vertical ribs are separable into a first vertical rib provided in the upper case and a second vertical rib provided in the lower case,
The height from the installation surface at the joining position of the first vertical rib and the second vertical rib is different from the height from the installation surface on the optical axis of the light emitting element and the light receiving element. It is characterized by having.

  According to the above configuration, the chamber case having a labyrinth structure composed of a plurality of vertical ribs can be divided into an upper case and a lower case, and a light emitting element and a light receiving element are arranged in the divided lower case. Is installed. Therefore, the height of the case having the labyrinth structure in which the light emitting element and the light receiving element are installed can be less than half of the height of the chamber case, and the mounting of the optical component including the light emitting element and the light receiving element is possible. Becomes easier.

  Further, the opening provided in the lower case for installing the light emitting element and the light receiving element may be a hole for inserting the lead terminal of the light emitting element and the lead terminal of the light receiving element. Therefore, the diameter of the opening is not limited as long as the lead terminal can be inserted, and the opening diameter can be greatly reduced as compared with the opening in which the light emitting element and the light receiving element itself are inserted. Therefore, it can suppress that dust etc. mix from the said opening at the time of manufacture.

  Further, the height of the joining position of the first vertical rib on the upper case side and the second vertical rib on the lower case side is different from the height of the optical axis of the light emitting element and the light receiving element. Therefore, the light emitted from the light emitting element does not hit the joining position of the first vertical rib and the second vertical rib, which has a manufacturing variation and the shape is not stable, and is irregularly reflected by the joint. The generated stray light can be prevented. Therefore, it is possible to stably detect suspended particulates.

In the light scattering type particle detector of one embodiment,
One vertical rib of the plurality of vertical ribs provided in the chamber case, the one end of the vertical rib being on the optical axis of the light emitting element, and the light emitting element Placed so as to face
The light emitted from the light emitting element and dispersed on both sides at the one end portion of the vertical rib is converged by other vertical ribs provided on both sides of the vertical rib.

  According to this embodiment, the light emitted from the light emitting element and passing through a detection space that is an area where the optical axis of the light emitting element and the optical axis of the light receiving element intersect with each other is a single vertical rib. The other vertical ribs distributed on both sides at one side end portion and provided on both sides of the vertical ribs are converged. Therefore, it is possible to suppress the light after passing through the detection space from being reflected in the chamber case to become stray light and returning to the detection space. Therefore, stray light passing through the detection space can be suppressed, and the detection sensitivity of the suspended fine particles can be stabilized.

  In that case, the vertical rib which comprises the said labyrinth structure is utilized as the vertical rib which disperse | distributes the light after passing the said detection space to both sides, and the vertical rib which converges this disperse | distributed light. Therefore, the vertical ribs for converging the light after passing through the detection space and the other vertical ribs can have substantially the same shape, simplifying the device, and introducing suspended particulates. Directivity can be suppressed.

In the light scattering type particle detector of one embodiment,
A first aperture that is installed at a front portion of the light emitting element in the lower case and blocks a peripheral edge of a light beam emitted from the light emitting element;
And a second aperture that is installed at a front portion of the light receiving element in the lower case and blocks a peripheral edge of a light beam incident on the light receiving element.

  According to this embodiment, the peripheral portion of the light beam emitted from the light emitting element is blocked by the first aperture, and the peripheral portion of the incident light beam incident on the light receiving element is blocked by the second aperture. The irradiation area and the light receiving area can be narrowed down, and the detection sensitivity of suspended particulates can be stabilized. Furthermore, since the irradiation area and the light receiving area relating to the detection space can be reduced, the external dimensions of the chamber case can be reduced, and the apparatus can be downsized.

  At this time, if the first aperture is composed of a plurality of apertures and the aperture distance away from the light emitting element is set to be small, the irradiation area can be narrowed down more accurately. Furthermore, if the second aperture is composed of a plurality of apertures and the aperture distance away from the light receiving element is set larger, the light receiving region can be narrowed down more accurately.

In the light scattering type particle detector of one embodiment,
A cylindrical first lens element that is installed at a front portion of the light emitting element in the lower case and focuses light emitted from the light emitting element toward the optical axis;
And a cylindrical second lens element that is disposed in front of the light receiving element in the lower case and focuses incident light incident on the light receiving element toward the optical axis.

  According to this embodiment, the emitted light from the light emitting element is focused toward the optical axis by the first lens element. Further, incident light incident on the light receiving element is focused toward the optical axis by the second lens element. Therefore, the irradiation area and the light receiving area related to the detection space can be narrowed down, and the detection sensitivity of the suspended fine particles can be stabilized. Further, since the emitted light and the incident light are converged in a direction parallel to the lower case, irradiation accuracy and light receiving accuracy in the vertical (height) direction can be improved, and the chamber case can be thinned. .

In the light scattering type particle detector of one embodiment,
A grounding terminal, and a metal case that is placed on the lower case and is placed on the light receiving element that is placed on the lower case,
The ground terminal of the metal case is connected to a GND power source.

  According to this embodiment, the light receiving element is covered with a metal case, and the ground terminal of the metal case is connected to the GND power source. Therefore, it is possible to improve the resistance to external electromagnetic noise in the light receiving element, and it is possible to provide a light scattering type particle detector that is stable against noise.

In the light scattering type particle detector of one embodiment,
An inspection opening provided in the immediate vicinity of a detection space formed by a region where the optical axis of the light emitting element and the optical axis of the light receiving element intersect in the lower case;
A cap for sealing the opening is provided.

  According to this embodiment, the inspection opening is provided in the lower case in the immediate vicinity of the detection space. Accordingly, by inserting a test member that substitutes for the suspended fine particles into the opening at the time of assembly, the operation and adjustment of the light scattering particle detector can be simulated. Furthermore, since the opening is sealed with a cap, in actual use, the suspended fine particles are introduced from the side surface of the chamber case having the labyrinth structure.

Moreover, the fire alarm of this invention is
Equipped with the light scattering type particle detector of the present invention,
The light scattering type particle detector detects smoke generated at the time of a fire and notifies the occurrence of the fire.

  According to the above configuration, it is easy to mount an optical component including a light emitting element and a light receiving element, the generation of stray light can be prevented, and the light scattering particle detection device capable of stably detecting suspended particulates can be used for fire. It detects smoke that sometimes occurs. Therefore, it is possible to provide a smoke detection type fire alarm that simplifies the manufacturing method, is stable in detection accuracy, and is small and thin.

  As is clear from the above, the light scattering particle detector of the present invention can divide the chamber case having a labyrinth structure composed of a plurality of vertical ribs into an upper case and a lower case, and Since the light emitting element and the light receiving element are installed in the lower case, the labyrinth structure is provided, and the height of the lower case in which the light emitting element and the light receiving element are installed is set to the height of the chamber case. It can be less than half that. Therefore, it is possible to easily mount an optical component including the light emitting element and the light receiving element.

  Further, the opening provided in the lower case for installing the light emitting element and the light receiving element may be a hole for inserting the lead terminal of the light emitting element and the lead terminal of the light receiving element. Therefore, the diameter of the opening is not limited as long as the lead terminal can be inserted, and the opening diameter can be greatly reduced as compared with the opening in which the light emitting element and the light receiving element itself are inserted. Therefore, it can suppress that dust etc. mix from the said opening at the time of manufacture.

  Further, the height of the joining position of the first vertical rib on the upper case side and the second vertical rib on the lower case side is different from the height of the optical axis of the light emitting element and the light receiving element. Therefore, the light emitted from the light emitting element does not hit the joint position between the first vertical rib and the second vertical rib, which has a manufacturing variation and the shape is not stable, and is irregularly reflected at the joint. The stray light generated by the can be prevented. Therefore, it is possible to stably detect suspended particulates.

  In addition, the fire alarm according to the present invention can easily mount optical components including a light emitting element and a light receiving element, can prevent generation of stray light, and can stably detect suspended particles. Since the device detects smoke generated in the event of a fire, the manufacturing method is simplified, the detection accuracy is stable, and a smoke detection-type fire alarm that is compact and thin is provided. can do.

It is a disassembled external view of the chamber case in the light-scattering type particle | grain detection apparatus of this invention. It is a top view of the lower case which comprises the chamber case shown in FIG. FIG. 3 is a detailed view of a lower case shown in FIG. 2. It is function explanatory drawing of the aperture installed in the front part of the light emitting element and light receiving element which are shown in FIG. FIG. 5 is a functional explanatory diagram when a cylindrical lens is used instead of the aperture shown in FIG. 4. It is a figure which shows the attachment method with respect to the lower case of a light emitting element and a light receiving element. It is a figure which shows the mounting method to the circuit board of a chamber case. It is the disassembled perspective view and longitudinal cross-sectional view in the conventional light-scattering type particle | grain detection sensor. It is the top view and longitudinal cross-sectional view in the conventional floating particle detection apparatus.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is an exploded external view of a chamber case 31 in the light scattering type particle detector of the present embodiment. 2 is a plan view of the lower case 33 constituting the chamber case 31 in FIG.

  As shown in FIGS. 1 and 2, the chamber case 31 forms an optical chamber having a labyrinth structure and can be divided into an upper case 32 and a lower case 33.

  A light emitting element 35 and a light receiving element 36 are disposed on the outer periphery of the bottom plate 34 forming a circular shape in the lower case 33 so as to face the center of the bottom plate 34 at an angle of 120 degrees. Therefore, the light emitted from the light emitting element 35 is not received by the light receiving element 36 as it is. The bottom plate 34 is formed with a plurality of vertical ribs 37 to form a labyrinth structure. Further, an aperture 38 is provided in front of the light emitting element 35 and the light receiving element 36 in the bottom plate 34 to block the peripheral edge of the emitted light beam from the light emitting element 35 and the incident light beam to the light receiving element 36. However, the aperture 38 on the light emitting element 35 side is used as the aperture 38a, while the aperture 38 on the light receiving element 36 side is used as the aperture 38b. Further, an inspection opening 39 is provided at the center of the bottom plate 34. As shown in FIG. 2, each of the light emitting element 35 and the light receiving element 36 is an element provided with a lens, and the irradiation light and the incident light are converged by the lens to further suppress the dispersed light.

  Hereinafter, a specific structure and operation will be described with reference to FIG. 3A is a plan view of the lower case 33. FIG. FIG. 3B is a cross-sectional view taken along line BB ′ in FIG. In FIG. 3A, the one-dot chain line arrow is the optical axis of the light emitting element 35, and the broken line arrow is the optical axis of the light receiving element 36. A region where the optical axes of the light emitting element 35 and the light receiving element 36 intersect becomes a detection space 40.

  Then, when floating particulates enter the detection space 40, the irradiation light from the light emitting element 35 is reflected by the floating particulates and enters the light receiving element 36. That is, when fine particles enter the detection space 40, the amount of light received by the light receiving element 36 increases. Therefore, in the present light scattering type particle detection device, the presence or absence of airborne particles is detected by detecting the increase in the amount of light received by the light receiving element 36 using an electrical signal.

  The suspended fine particles to be observed pass through the vertical ribs 37 constituting the labyrinth structure and enter the detection space 40 from the periphery of the chamber case 31 as indicated by white arrows. At that time, the vertical ribs 37 constituting the labyrinth structure have such a shape that disturbance light cannot enter while taking in surrounding floating fine particles. Specifically, as shown in FIG. 3 (a), it has a substantially flat U-shaped horizontal (horizontal) cross section, and protrudes from the substantially middle portion of the U-shape toward the outside of the U-shape. Has a protruding portion. The plurality of vertical ribs 37 having such a shape are arranged radially on the outer peripheral portion of the bottom plate 34 with the protruding portions directed in the same direction.

  Furthermore, in light scattering type particle detectors used for fire alarms, it is required to introduce suspended fine particles from all directions. Therefore, the labyrinth structure needs to be designed so as not to have directivity. This will be specifically described below.

  In the present light scattering type particle detector, it is important that the amount of light irradiating the detection space 40 is stably constant. The change in the amount of light that irradiates the detection space 40 means that the level of light received by the light receiving element 36 changes even if the same number of particles are present in the detection space 40. Therefore, a detection error occurs, and when the amount of irradiation light is not stable, the measurement variation becomes large, resulting in an unstable light scattering particle detector. Accordingly, light that has passed through the detection space 40 out of the light emitted from the light emitting element 35 is unnecessary, and this unnecessary light is reflected by the wall surface or the like in the optical chamber and becomes stray light in the detection space 40. If it returns, it will cause a detection error.

  In order to suppress such stray light, a structure for dispersing and converging unnecessary irradiation light on the side opposite to the light emitting element 35 on the optical axis of the light emitting element 35 is required. In the embodiment, in one vertical rib 37a constituting the labyrinth structure, a tip portion 37a ′ facing the center side of the bottom plate 34 is positioned on the optical axis of the light emitting element 35. By doing so, the light hitting the tip 37a ′ of the vertical rib 37a is dispersed on both sides of the vertical rib 37a and can be converged by the vertical ribs 37b and 37c located on both sides of the vertical rib 37a. .

  By adopting such a structure, the vertical ribs 37a, 37b, and 37c for converging unnecessary irradiation light and the other vertical ribs 37 can be formed in substantially the same shape, thereby simplifying the apparatus. In addition, the directivity when introducing suspended particulates can be suppressed.

  In the conventional optical trap structure disclosed in Patent Document 2, the box-shaped optical trap 21 is formed in a shape different from the other substantially labyrinth portion 19. Therefore, floating particulates cannot be introduced at the location of the optical trap 21, and directivity occurs when the suspended particulates are introduced.

  3B, when the lower case 33 is viewed from the side, the light emitting element 35 and the light receiving element 36 have an optical axis of the light emitting element 35 and an optical axis of the light receiving element 36. Are arranged at the same height and parallel to the surface of the lower case 33. At that time, the upper case 32 that constitutes the chamber case 31 together with the lower case 33 is also provided with the vertical rib 37A having the same horizontal cross-sectional shape at the same position as the vertical rib 37 of the lower case 33. Yes. Then, the height “h” from the bottom plate 34 of the lower case 33 at the joint surface between the vertical rib 37 </ b> A of the upper case 32 and the vertical rib 37 of the lower case 33 is used as the light of the light emitting element 35 and the light receiving element 36. By arranging it different from the shaft height “H”, the generation of stray light can be suppressed.

  That is, the portion of the joint surface between the vertical rib 37 </ b> A of the upper case 32 and the vertical rib 37 of the lower case 33 becomes the edge portion of each of the upper case 32 and the lower case 33. Therefore, the joint surface part is a part whose shape is not stable due to manufacturing variations, and the joint finished shape is also an unstable part, and when the joint surface part is exposed to light, dispersed light (stray light), etc. is generated. However, as described above, the detection sensitivity varies. Therefore, as in the present embodiment, the optical axes of the light emitting element 35 and the light receiving element 36 are positioned not on the joint surface between the upper case 32 and the lower case 33 but on the portion where the manufacturing shape is stable. Optical variation can be reduced. The direction in which the positions of the optical axes of the light emitting element 35 and the light receiving element 36 are shifted with respect to the joining position of the upper case 32 and the lower case 33 may be either the upward direction or the downward direction.

  FIG. 4 schematically shows the function of the aperture 38 that is installed in front of the light emitting element 35 and the light receiving element 36 and blocks the peripheral edge of the emitted light beam from the light emitting element 35 and the incident light beam to the light receiving element 36. Yes. 4A shows the aperture 38a on the light emitting element 35 side, and FIG. 4B shows the aperture 38b on the light receiving element 36 side.

  In FIG. 4 (a), the luminous flux of the light emitted from the light emitting element 35 is blocked at the periphery by the aperture 38a, the irradiation area is narrowed, and the dispersed light is suppressed. In that case, preferably, a plurality of apertures 38a are provided, and the hole diameter of the apertures 38a is set smaller as the distance from the light emitting element 35 increases. For example, as shown in FIG. 4A, two apertures 38a of an aperture 38a1 and an aperture 38a2 are arranged in series along the optical axis of the light emitting element 35. Then, the hole diameter φa1 of the aperture 38a1 closer to the light emitting element 35 is set larger than the hole diameter φa2 of the farther aperture 38a2. By doing so, the irradiation area of the light emitting element 35 can be narrowed down step by step, and the irradiation area can be narrowed down more accurately.

  In FIG. 4B, the light beam incident on the light receiving element 36 is blocked at the periphery by the aperture 38b, the light receiving area is narrowed, and the dispersed light is suppressed. In that case, the hole diameter of the aperture 38b is set to be larger as the distance from the light receiving element 36 increases, contrary to the light emitting side. For example, as shown in FIG. 4B, two apertures 38b, which are an aperture 38b1 and an aperture 38b2, are arranged in series along the optical axis of the light receiving element 36. Then, the hole diameter φb1 of the aperture 38b1 closer to the light receiving element 36 is set smaller than the hole diameter φb2 of the farther aperture 38b2. By doing so, the light receiving area of the light receiving element 36 can be narrowed in steps, and the light receiving area can be narrowed down with higher accuracy.

  That is, according to the aperture 38a on the light emitting element 35 side and the aperture 38b on the light receiving element 36 side in the present embodiment, the irradiation area and the light receiving area with respect to the detection space 40 can be narrowed down. The influence of (stray light) can be suppressed. Further, since the irradiation area and the light receiving area with respect to the detection space 40 can be reduced, the size of the optical chamber, that is, the outer dimension of the chamber case 31 can be reduced, and a small light scattering particle detector is provided. Can do it.

  FIG. 5 shows a modification in which a cylindrical lens 41 is arranged on the optical axis in the front part of the light emitting element 35 and a cylindrical lens 42 is arranged on the optical axis in the front part of the light receiving element 36 instead of the apertures 38a and 38b. An example is shown. Since the cylindrical lenses 41 and 42 converge the light toward the optical axis of the light emitting element 35 or the optical axis of the light receiving element 36, the light emitting and receiving efficiency is reduced while the apertures 38a and 38b block the light as described above. Can be raised. Furthermore, since the light is converged in a direction parallel to the bottom plate 34 of the lower case 33, the irradiation accuracy and light receiving accuracy in the vertical (height) direction can be improved, and the thickness of the optical chamber, that is, the thickness of the chamber case 31 can be reduced. It becomes possible, and thickness reduction of this light scattering type particle | grain detection apparatus can be achieved. The arrangement (optical design) of the cylindrical lens 41 on the light emitting element 35 side is such that the convergence position of the light from the light emitting element 35 is substantially at the position of the detection space 40 in order to suppress the dispersed light (stray light) with respect to the detection space 40. It is preferable to set so that

  FIG. 6 shows a method of attaching the light emitting element 35 and the light receiving element 36 to the lower case 33. FIG. 7 shows a method of mounting the chamber case 31 having the above configuration on the circuit board 50.

  In FIG. 6, the lower case 33 has small holes (not shown) through which the two lead terminals 43 a and 43 b of the light emitting element 35 and the two lead terminals 44 a and 44 b of the light receiving element 36 are inserted. The lead terminals 43a, 43b, 44a, 44b are inserted into these holes, and the light emitting element 35 and the light receiving element 36 are attached to the lower case 33. Further, the light receiving element 36 thus attached to the lower case 33 is covered with a metal case 45 integrally formed with one grounding terminal 46, and the grounding terminal of the metal case 45 provided on the lower case 33 is covered. The ground terminal 46 is inserted into a small hole (not shown) for inserting the metal 46, and the metal case 45 is attached to the lower case 33 together with the light receiving element 36.

  Further, the upper case 32 is joined to the lower case 33 to which the light emitting element 35, the light receiving element 36 and the metal case 45 are attached in this manner, so that the chamber case 31 is formed. At that time, three locking members 47 a, 47 b, 47 c (see FIG. 1) that extend downward on the outer peripheral portion of the upper case 32 are provided on the bottom plate 34 of the lower case 33. Further, it passes through the three engaging member through holes 48a, 48b, 48c (see FIG. 3) and protrudes outward. Further, a boss 49 (see FIG. 6) is formed around the opening 39 for inspection on the outer surface of the bottom plate 34.

  The chamber case 31 formed as described above is mounted on the circuit board 50 as shown in FIG.

  That is, the locking members 47a, 47b, 47c protruding outward from the outer surface of the bottom plate 34 in the lower case 33 are inserted into the locking holes 51a, 51b, 51c provided in the circuit board 50. A boss 49 formed on the outer surface of the bottom plate 34 is fitted into a fitting hole 52 provided in the circuit board 50. Further, the lead terminals 43 a and 43 b of the light emitting element 35 protruding from the bottom plate 34 are inserted into the light emitting side terminal holes 53 provided in the circuit board 50. Further, the lead terminals 44 a and 44 b of the light receiving element 36 protruding from the bottom plate 34 are inserted into the light receiving side terminal holes 54 provided in the circuit board 50. Further, the ground terminal 46 of the metal case 45 protruding from the bottom plate 34 is inserted into the ground terminal hole 55 provided in the circuit board 50.

  Thus, the chamber case 31 is locked to the circuit board 50 by the locking members 47a, 47b, 47c. Furthermore, the lead terminals 43 a and 43 b of the light emitting element 35 and the lead terminals 44 a and 44 b of the light receiving element 36 are connected to wiring formed on the back surface of the circuit board 50. Further, the ground terminal 46 of the metal case 45 is connected to the GND wiring formed on the back surface of the circuit board 50.

  As described above, when the ground terminal 46 of the metal case 45 is connected to the GND wiring, the light receiving element 36 can be shielded, and the resistance to external electromagnetic noise can be improved.

  In general, in the light scattering type particle detector, the amplifier circuit that amplifies the detection current from the light receiving element 36 has a high gain in order to detect weakly reflected light due to suspended fine particles in the detection space 40. Such a high-sensitivity amplifier is easily affected by electromagnetic noise from various electric devices such as a mobile phone and an inverter fluorescent lamp from the outside. Therefore, it is very effective to shield the light receiving element 36 which is a sensor portion that first obtains a detection signal.

  In the present embodiment, as shown in FIG. 1, an optical chamber is formed and a chamber case 31 having a labyrinth structure is divided into an upper case 32 and a lower case 33 vertically. Therefore, it is possible to easily install the light emitting element 35 and the light receiving element 36, the apertures 38a and 38b, or the cylindrical lenses 41 and 42 with respect to the chamber case 31.

  Further, the lower case 33 serving as the bottom surface of the optical chamber is provided for grounding the two lead terminals 43a and 43b of the light emitting element 35, the two lead terminals 44a and 44b of the light receiving element 36, and the metal case 45. It is only necessary to provide five small holes through which the terminal 46 is inserted. Therefore, as in the case where the light emitting element and the light receiving element are mounted on the printed board as in the conventional light scattering particle detector disclosed in the above cited reference 1 and the above cited reference 2, the light emitting element 35 and the lower case 33 It is not necessary to provide an opening for inserting the light receiving element 36 itself from below.

  Therefore, when providing holes for lead terminals in the lower case 33, the holes themselves are small because the holes themselves are small even if they are provided with an appropriate margin in consideration of variations in component size and arrangement positioning accuracy. The portion (gap) is also very small, and the small margin (gap) is blocked by the installed light emitting element 35, light receiving element 36, and metal case 45. Therefore, in a manufacturing process, it can suppress that foreign materials, such as dust, penetrate | invade in the chamber case 31 as said optical chamber.

  Further, in the present embodiment, as shown in FIG. 3, the inspection is performed at the position of the detection space 40 where the optical axis of the light emitting element 35 and the optical axis of the light receiving element 36 intersect on the bottom plate 34 of the lower case 33. An opening 39 is provided. The present light scattering type particle detection device is configured to introduce surrounding suspended fine particles from the lateral direction of the chamber case 31. Therefore, in the state in which the upper case 32 and the lower case 33 are joined and the chamber case 31 is assembled, when adjusting and confirming the operation, particles such as smoke are actually blown into the chamber case 31. It is necessary to do this, and the adjustment and confirmation of the operation becomes a large scale.

  Therefore, by providing the opening 39 for inspection in the lower case 33, it is easy to insert inspection parts such as scattering material into the opening 39 in place of the fine particles in the assembled state of the chamber case 31. It is possible to inspect and adjust the operation. As shown in FIG. 7, the inspection opening 39 is opened after the sealing cap 56 is finally inserted into the boss 49 of the lower case 33 after the inspection and adjustment of the operation are performed. The part 39 is sealed. Therefore, in actual operation, only floating particulates are introduced into the detection space 40 of the chamber case 31 from the laterally outer peripheral direction of the chamber case 31, and neither particulates nor light can enter from the inspection opening 39. .

  As described above, according to the present embodiment, it is possible to provide a light-scattering particle detector capable of simplifying manufacturing and suppressing the influence of dispersed light (stray light) and obtaining stable detection accuracy. it can. Therefore, if the light scattering type particle detector is used to detect smoke generated during a fire, the manufacturing method is simplified, the detection accuracy is stable, and the size and thickness are reduced. It is possible to provide a smoke detector detection type fire alarm.

  In the above embodiment, the joining of the lower case 33 and the upper case 32 and the mounting of the chamber case 31 to the circuit board 50 are performed by the locking members 47a, 47b, 47c is engaged with the circuit board 50. However, the present invention is not limited to this. For example, the lower case 33 and the upper case 32 may be joined by the first locking member, and the chamber case 31 may be mounted on the circuit board 50 by the second locking member.

31 ... Chamber case,
32 ... upper case,
33 ... lower case,
34 ... bottom plate,
35. Light emitting element,
36 ... light receiving element,
37, 37a, 37b, 37c, 37A ... vertical ribs,
37a '... the tip of the vertical rib,
38,38a, 38b, 38a1,38a2,38b1,38b2 ... Aperture,
39 ... opening,
40. Detection space,
41, 42 ... Cylindrical lens,
45 ... Metal case,
47a, 47b, 47c ... locking members,
48a, 48b, 48c ... locking member through hole,
49 ... Boss,
50 ... Circuit board,
56: Cap for sealing.

Claims (7)

A chamber case that has a labyrinth structure composed of a plurality of vertical ribs that allows the introduction of suspended particulates from the outside while preventing the entry of ambient light, and that can be divided into an upper case and a lower case ,
A light emitting device installed in the lower case;
A light receiving element that is installed in the lower case and receives light emitted from the light emitting element and reflected by suspended fine particles in the chamber case;
The chamber case is mounted, and includes at least a circuit board on which a circuit that performs processing of a signal from the light receiving element and operation control of the light emitting element and the light receiving element is mounted,
The height from the installation surface of the light emitting element and the light receiving element in the optical axis of the light emitting element and the optical axis of the light receiving element are the same,
The plurality of vertical ribs are separable into a first vertical rib provided in the upper case and a second vertical rib provided in the lower case,
The height from the installation surface at the joining position of the first vertical rib and the second vertical rib is different from the height from the installation surface on the optical axis of the light emitting element and the light receiving element. A light scattering type particle detector. In the light scattering type particle detector according to claim 1,
One vertical rib of the plurality of vertical ribs provided in the chamber case, the one end of the vertical rib being on the optical axis of the light emitting element, and the light emitting element Placed so as to face
The light emitted from the light emitting element and dispersed on both sides at the one end of the vertical rib is converged by other vertical ribs provided on both sides of the vertical rib. A light scattering type particle detector. In the light scattering type particle | grain detection apparatus of Claim 1 or Claim 2,
A first aperture that is installed at a front portion of the light emitting element in the lower case and blocks a peripheral edge of a light beam emitted from the light emitting element;
A light scattering type particle detection apparatus, comprising: a second aperture that is installed at a front portion of the light receiving element in the lower case and blocks a peripheral edge of a light beam incident on the light receiving element. In the light scattering type particle | grain detection apparatus of Claim 1 or Claim 2,
A cylindrical first lens element that is installed at a front portion of the light emitting element in the lower case and focuses light emitted from the light emitting element toward the optical axis;
And a cylindrical second lens element that is disposed in front of the light receiving element in the lower case and focuses incident light incident on the light receiving element toward the optical axis. A light scattering particle detector. In the light scattering type particle | grain detection apparatus as described in any one of Claim 1- Claim 4,
A grounding terminal, and a metal case that is placed on the lower case and is placed on the light receiving element that is placed on the lower case,
A light scattering type particle detecting apparatus, wherein the grounding terminal of the metal case is connected to a GND power source. In the light scattering type particle | grain detection apparatus as described in any one of Claim 1- Claim 5,
An inspection opening provided in the immediate vicinity of a detection space formed by a region where the optical axis of the light emitting element and the optical axis of the light receiving element intersect in the lower case;
A light scattering type particle detection apparatus comprising a cap for sealing the opening. The light scattering type particle detector according to any one of claims 1 to 6 is mounted,
A fire alarm characterized by detecting smoke generated at the time of a fire by the light scattering type particle detecting device and notifying the occurrence of a fire.

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