JP2010238109A - Photoelectric smoke sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an S/N ratio by preventing reflecting light from entering a smoke-detecting section. <P>SOLUTION: A photoelectric smoke sensor includes: a light-emitting element 22 for emitting light to an inside of a smoke detecting section 1; a light-receiving element 23 for receiving light emitted from the light-emitting element 22 and scattered by smoke section of the smoke detecting section; and a plurality of shading walls 24, 40a for preventing light emitted from the light-emitting element 22 from advancing toward a section other than the smoke detecting section. The plurality of shading walls 24, 40a have a shape and arrangement corresponding to a relative light-emitting intensity distribution to the smoke detecting section of the light-emitting section of the light-emitting element 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photoelectric smoke detector, and more particularly to a photoelectric smoke detector that can reduce the amount of reflected light (stray light) that enters a smoke detection unit and improve the S / N ratio.

  2. Description of the Related Art Conventionally, in a scattered light smoke detector, a light shielding wall that prevents light emitted from a light emitting element from traveling to a portion other than a smoke detector is known (see, for example, Patent Document 1).

Japanese Patent No. 2747472 (FIGS. 1 to 3)

  However, in the conventional scattered light type smoke detector, the light shielding wall is arranged without considering the pattern (radiation pattern) of the relative light emission intensity distribution of the light emitting portion of the light emitting element with respect to the smoke detecting portion. For this reason, the light shielding wall, particularly the light shielding wall that prevents direct light from entering the light receiving element, is installed in a state where the light shielding wall enters more than necessary. The amount of reflected stray light was large and the S / N ratio was bad.

  The technical problem of the present invention is to make it possible to prevent reflected light from entering the smoke detector and to improve the S / N ratio.

  The photoelectric smoke detector according to the present invention has the following configuration. That is, in a photoelectric smoke detector that has a smoke detector and a fire discriminator that judges a fire based on the output signal of the smoke detector and outputs a fire signal when the fire discriminator judges a fire. A light emitting element for irradiating light inside the smoke part, a light receiving element for receiving scattered light emitted from the smoke particles of the smoke detecting part, and light emitted from the light emitting element other than the smoke detecting part A plurality of light shielding walls that prevent the light from traveling forward, and a plurality of walls that prevent external light from entering the smoke inflow portion, and a smoke inlet formed between the walls. The plurality of light shielding walls are shaped and arranged in accordance with the relative light emission intensity distribution with respect to the smoke detecting part of the light emitting part of the light emitting element.

  The photoelectric smoke detector according to the present invention has the following configuration. That is, in a photoelectric smoke detector that has a smoke detector and a fire discriminator that judges a fire based on the output signal of the smoke detector and outputs a fire signal when the fire discriminator judges a fire. The smoke part includes a mounting part and a smoke inflow part, and the mounting part is a light emitting element that irradiates light inside the mounting part, and scattering that is emitted from the light emitting element and caused by smoke particles in the smoke detecting part. A light receiving element that receives light, and a plurality of light shielding walls that prevent light emitted from the light emitting element from traveling to other than the smoke detecting section. And a plurality of wall bodies formed between the wall bodies, and the mounting section and the smoke inflow section are stacked so that the smoke inflow section is on the lower side. The plurality of light shielding walls are connected to the light emitting portion of the light emitting element relative to the smoke detecting portion. Shape corresponding to the intensity distribution is obtained by the arrangement.

  A part of the plurality of light shielding walls is arranged in the vicinity of the wall facing the light emitting element, and is configured as an optical trap that repeatedly attenuates reflection of light emitted from the light emitting element.

  In the present invention, there are provided a plurality of light shielding walls for preventing the light emitted from the light emitting element from traveling to other than the smoke detecting section, and the plurality of light shielding walls are used for relative light emission with respect to the smoke detecting section of the light emitting section of the light emitting element. Since the shape and arrangement according to the intensity distribution (for example, the light shielding wall in front of the light emitting element is arranged farthest from the light emitting part), the area of the relative light emission intensity distribution pattern (radiation pattern) with respect to the smoke detecting part of the light emitting part of the light emitting element Since the light shielding wall does not enter more than necessary, the amount of light (stray light) reflected by the light shielding wall can be reduced, the amount of stray light entering the smoke detector is reduced, and the S / N ratio is reduced. Can be improved.

  In addition, a part of the plurality of light-shielding walls is arranged in the vicinity of the wall facing the light-emitting element, and is configured as an optical trap that repeatedly attenuates the reflection of light emitted from the light-emitting element. The amount of stray light to be generated can be further reduced, and the amount of reflected light (stray light) entering the smoke detecting section can be reduced, so that the S / N ratio can be further improved.

It is a disassembled perspective view which shows the smoke detection part of the fire alarm which concerns on one embodiment of this invention upside down. It is a bottom view of the smoke detection part of the fire alarm which concerns on one embodiment of this invention. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 3 is a side view of FIG. 2. FIG. 5 is a cross-sectional view taken along line B-B in FIG. 4. It is a bottom view of the smoke inflow part of the fire alarm which concerns on one embodiment of this invention. It is a bottom view of the mounting part of the fire alarm which concerns on one embodiment of this invention. It is a cross-sectional view of the mounting portion showing an example of the directivity angle of the relative light emission intensity with respect to the smoke detecting portion of the light emitting portion of the light emitting element of the fire alarm according to one embodiment of the present invention.

  In the following embodiments, a case will be described in which the present invention is applied to a fire alarm device in which an alarm device such as a push button switch or a buzzer is provided in the configuration of the photoelectric smoke detector.

  FIG. 1 is an exploded perspective view showing the smoke detector of the fire alarm according to an embodiment of the present invention upside down, FIG. 2 is a bottom view of the smoke detector of the fire alarm, and FIG. 4 is a side view of FIG. 2, FIG. 5 is a cross-sectional view of FIG. 4 along the line BB, FIG. 6 is a bottom view of the smoke inflow portion of this fire alarm, FIG. Fig. 8 is a bottom view of the mounting portion of the fire alarm, and Fig. 8 is a cross-sectional view of the mounting portion showing an example of a directivity angle of relative light emission intensity with respect to the smoke detecting portion of the light emitting element of the light emitting element of the fire alarm. For convenience of explanation, all the drawings are reverse to the layout at the time of ceiling installation, and in the following explanation, the upper and lower notations are based on the layout at the time of ceiling installation.

  In the fire alarm device according to the present embodiment, the smoke detector 1 includes a smoke inflow portion 10 and a mounting portion 20. The smoke inflow portion 10 has a substantially cylindrical shape, and includes a plate member 11 and a wall body 12. The plate member 11 has a substantially disk shape, and an opening 13 is formed at a substantially central portion. Further, on the outer peripheral portion of the plate member 11, convex portions 11 a and convex portions 11 b are formed at corresponding positions of a light emitting element holder 26 and a light receiving element holder 27 described later. A plurality of, for example, substantially J-shaped wall bodies 12 are erected in a substantially annular shape with a predetermined interval at a peripheral portion on the lower surface side of the plate member 11. Thereby, the smoke inflow part 10 is formed in a substantially cylindrical shape so that the upper surface part is covered with the plate member 11. The wall body 12 prevents external light from entering the smoke inflow portion 10 and the mounting portion 20. A space (predetermined interval) formed between the wall bodies 12 serves as a smoke inlet 14 for smoke to flow into the smoke inflow portion 10. The opening on the lower surface side of the smoke inflow portion 10 is closed by the lid body 16, and the inside of the smoke inflow portion 10 is a dark box. In addition, an insect net (not shown) is provided on the side surface of the smoke inflow portion 10 in order to prevent insects from entering from the smoke inlet 14.

  A mounting portion 20 is provided above the smoke inflow portion 10. The mounting unit 20 includes an optical bench 21, a light emitting element 22, a light receiving element 23, a light shielding wall 24, an optical trap 40, and the like. The optical bench 21 has a substantially cylindrical shape with an opening at the bottom, and is provided with a light emitting element holder 26 for accommodating the light emitting element 22 and a light receiving element holder 27 for accommodating the light receiving element 23. The outer end portions of the light emitting element holder 26 and the light receiving element holder 27 are provided so as to protrude from the outer peripheral portion of the optical bench 21. Further, the light irradiated from the light emitting element 22 in the vicinity of the peripheral wall facing the light emitting element 22 of the optical bench 21 is converted into the primary reflected light 50a, the secondary reflected light 50b, the tertiary reflected light 50c... Shown in FIG. Thus, an optical trap 40 composed of a plurality of light shielding walls 40a that are attenuated by repeating reflection is provided. The optical trap 40 has a larger radius than the other peripheral walls so that the light emitted from the light emitting element 22 can be sufficiently attenuated. Further, the plurality of light shielding walls 40a extend substantially linearly with the plane portion facing the light emitting element 22 so that the irradiation light repeats a predetermined number of reflections for each of the narrow paths formed on the peripheral walls between them. Further, the edge shape of the inner end portions of the plurality of light shielding walls 40a is an acute angle. As a result, the irradiation light of the light emitting element 22 can be reliably attenuated by the light trap 40, so that a large amount of stray light is prevented from being generated in the smoke detector. The number and shape of the plurality of light shielding walls 40a of the optical trap 40 are appropriately determined according to the irradiation pattern (not shown) of the light emitting element 22. In a state where the smoke inflow portion 10 is provided below the mounting portion 20, the smoke inflow portion 10 that is a dark box closes the opening of the optical bench 21. Thereby, the inside of the optical bench 21 is also a dark box. In addition, in a state where the smoke inflow portion 10 is provided below the mounting portion 20, the smoke inflow portion 10 and the mounting portion 20 communicate with each other through the opening 13. In addition, the height of the mounting part 20 is larger than the height of the smoke inflow part 10.

  The light emitting element holder 26 is provided with a pair of holding members 26a made of hooks, for example. The light emitting element 22 is accommodated in the light emitting element holder 26 while being held between the holding members 26 a. At this time, the lead portion of the light emitting element 22 is bent at a substantially right angle, is inserted through a through hole 26 b formed in the light emitting element holder 26, and protrudes from the upper surface portion of the optical bench 21. In addition, an aperture 30 having a longitudinal slit 30a narrower than the outer diameter of the light emitting part of the light emitting element 22 is provided in the vicinity of the light emitting part of the light emitting element 22, that is, in front of the light emitting element holder 26. The amount of irradiation can be limited.

  Here, for example, an LED having a narrow radiation pattern with a half-value angle of 10 ° is used as the light receiving element 23, provided in the shield case 28, and housed in the light receiving element holder 27 together with the shield case 28. The shield case 28 has a substantially rectangular tube shape with an opening in a range facing the light receiving part of the upper part and the light receiving element 23. The shield case 28 is provided with a holding member 28 a made of, for example, a pressing piece. The light receiving element 23 is sandwiched between the side surface portion of the shield case 28 and the holding member 28 a and is provided in the shield case 28. A convex portion 28b is formed on the upper portion of the shield case 28, and the convex portion 28b is inserted into an opening formed in a circuit board (not shown) and soldered to thereby form the shield case 28 and the light receiving element. 23 is fixed.

  In a state in which the light emitting element 22 and the light receiving element 23 are housed in the optical bench 21, the light emitting element 22 is provided so that the irradiation range thereof faces the substantially central portion of the optical bench 21, and the light receiving element 23 has the light receiving range. Is provided so as to face substantially the center of the optical bench 21. Further, the optical axis of the light emitting element 22 and the optical axis of the light receiving element 23 are provided so as to be substantially parallel in a side view and to form a predetermined angle in a plan view. That is, smoke is detected by the smoke detection unit that is a superposition of the irradiation range of the light emitting element 22 and the light receiving range of the light receiving element 23. More specifically, the light receiving element 23 receives light scattered by the smoke irradiated from the light emitting element 22 by the smoke entering the smoke detecting unit.

  Further, the optical bench 21 on the side where the angle formed by the optical axis of the light emitting element 22 and the optical axis of the light receiving element 23 is an obtuse angle, the relative light emission intensity of the light emitting part of the light emitting element 22 to the smoke detecting part as shown in FIG. A light shielding wall 24 having a shape and arrangement corresponding to the distribution pattern (radiation pattern) 50 is erected. In other words, the light shielding wall 24 has a cross-sectional shape in a plan view, and has a shape in which the center side of the optical bench 21 is cut into a substantially V shape. Thus, the light shielding wall 24 is formed with an edge portion 24a and an edge portion 24b. Further, these edge portions 24a and 24b are arranged along the radiation pattern 50, and are considered so as not to enter the area of the radiation pattern 50 more than necessary. The edge portion 24 a prevents the light receiving element 23 from directly receiving the light emitted from the light emitting element 22. The edge part 24b prevents the light receiving element 23 from receiving the stray light irregularly reflected by the edge part 24a.

  The mounting part 20 is mounted on the lower surface part of a circuit board (not shown). A plurality of electrical components (not shown) are mounted on the circuit board, and these electrical components constitute a fire discrimination unit and the like. And a fire discrimination | determination part (not shown) discriminate | determines whether the fire broke out based on the light reception amount which the light receiving element 23 detects. The amount of received light detected by the light receiving element 23 is output to the fire discriminating unit by, for example, voltage.

  The smoke detector 1 and the circuit board are provided in a casing (not shown) in which smoke inflow is ensured, and constitute a fire alarm. The fire alarm is installed in a monitoring space such as a house. In a state where the fire alarm is attached to the ceiling surface of the monitoring space, the fire alarm is installed with the smoke inflow portion 10 on the lower side.

  The fire alarm uses a battery such as a lithium battery as a drive source. That is, the battery supplies power to the light emitting element 22 of the smoke detector 1 and the fire determination unit of a circuit board (not shown).

Next, the operation of the fire alarm of this embodiment will be described.
First, smoke generated by the fire flows along the ceiling surface of the monitoring space and flows into the smoke inflow section 10 of the smoke detector section 1. At this time, the light shielding wall 24 is provided only in the mounting portion 20. That is, the light shielding wall 24 is not provided in the smoke inflow portion 10. On the other hand, the light emitting element 22 and the light receiving element 23 are not provided in the smoke inflow portion 10. Therefore, the light shielding wall 24 and the like do not block the flow of smoke flowing into the smoke inflow portion 10, and the smoke inflow characteristics of the smoke inflow portion 10 are improved. The light shielding wall 24 is not necessarily provided only in the mounting portion 20, and the tip of the light shielding wall 24 is inserted into the smoke inflow portion 10 as long as the smoke inflow characteristics of the smoke inflow portion 10 do not deteriorate. May be. By providing the light shielding wall 24 with such a length that the tip portion is inserted into the smoke inflow portion 10, it is possible to more reliably prevent the light receiving element 23 from directly receiving the light emitted by the light emitting element 22. .

  Smoke has low inertia because of its small particle mass. Therefore, since the flow state is easily changed, the smoke that has flowed into the smoke inflow portion 10 flows into the mounting portion 20 through the opening portion 13. When smoke flows into the mounting portion 20, the light emitted from the light emitting element 22 is scattered by the smoke. This scattered light is received by the light receiving element 23. That is, the amount of light received by the light receiving element 23 changes. The light receiving element 23 outputs a detection value (voltage or the like) corresponding to the amount of received light to a fire determination unit (not shown). Based on this detection value, the fire discriminating unit discriminates whether or not a fire has occurred. When it is determined that a fire has occurred, the fire determination unit warns the surroundings that a fire has occurred by a light emitting element such as an LED or an alarm device (not shown) such as a buzzer. In the present embodiment, since the height dimension of the mounting portion 20 is larger than the height dimension of the smoke inflow portion 10, the smoke that has flowed into the smoke inflow portion 10 easily flows into the mounting portion 20. Yes. For this reason, the fire discriminating unit (fire alarm device) can accurately determine a fire.

Further, a plurality of light shielding walls 24 and 40a for preventing the light emitted from the light emitting element 22 from traveling to other than the smoke detecting section are provided, and the plurality of light shielding walls 24 and 40a are provided for detecting the light emitting section of the light emitting element 22. Since the shape and arrangement according to the relative light emission intensity distribution with respect to the smoke part (the light shielding wall 40a at the front is located farthest and the light shielding wall 24 at the side is located closest), the smoke detecting part of the light emitting part of the light emitting element 22 The relative light emission intensity distribution pattern with respect to the light emission pattern 50, in particular, the light shielding walls 24 and 40a are prevented from entering more than necessary in an area where the light emission intensity is large, and the amount of stray light reflected by these light shielding walls 24 and 40a is reduced. It is possible to reduce the amount of stray light that enters the smoke detector, and the S / N ratio can be improved. In particular, in any of the plurality of light shielding walls 40a (for example, four) forming the optical trap 40, the effect of reducing the amount of stray light due to the edge of the inner end not entering the area of the radiation pattern 50 more than necessary is significant. A large amount of stray light is not generated from the edge in the smoke detector, and the S / N ratio can be easily improved.
FIG. 8 shows an example in which the light-emitting element 22 has a maximum relative light emission intensity distribution at the front (radiation angle 0 °) and decreases as the radiation angle increases. The light shielding walls 24 and 40a are appropriately arranged.

  Further, since the light trap 40 including the light shielding wall 40a that repeatedly attenuates the reflection of the light emitted from the light emitting element 22 is provided in the vicinity of the peripheral wall facing the light emitting element 22 of the mounting unit 20, the smoke detecting unit 1 It is possible to reduce the amount of stray light that is reflected on the light shielding wall or the like, and to further improve the S / N ratio.

  In addition, an aperture 30 having a vertically long slit 30a that is narrower than the outer diameter of the light emitting portion of the light emitting element 22 is provided in the vicinity of the light emitting portion of the light emitting element 22 to limit the amount of light applied to the left and right sides. Therefore, the light emitted from the light emitting element 22 in the left-right direction can be eliminated, the amount of stray light reflected from the light shielding wall or the like can be reduced, and the S / N ratio can be improved.

  In addition, since the smoke detection unit 1 is configured in a two-stage manner in which the mounting unit 20 is provided above the smoke inflow unit 10, only the optical trap needs to be formed in the mounting unit 20, and the capacity of the mounting unit 20 is increased. it can.

  In the present embodiment, the present invention is applied to a scattered light type fire alarm in which the smoke detector 1 has a smoke inflow portion 10 and a mounting portion 20 configured in two stages. The present invention may be implemented in a fire alarm configured in a single stage. In this case, the plurality of wall bodies 12 also serve as the optical trap 40. Further, if the present invention is applied to a fire alarm device in which the smoke detector 1 is downsized, a better effect can be expected.

  DESCRIPTION OF SYMBOLS 1 Smoke detection part, 10 Smoke inflow part, 11 Plate member, 11a Convex part, 11b Convex part, 12 Wall body, 13 Opening part, 14 Smoke inlet, 16 Cover body, 20 Mounting part, 21 Optical stand, 22 Light emitting element , 23 Light receiving element, 24, 40a Light shielding wall, 24a Edge part, 24b Edge part, 25 Smoke detecting part, 26 Light emitting element holder, 26a Holding member, 26b Through hole, 27 Light receiving element holder, 28 Shield case, 28a Holding member, 28b Convex part, 30 aperture, 30a Long slit, 40 Light trap, 50 Radiation pattern, 50a, 50b, 50c Reflected light.

Claims (3)

In a photoelectric smoke detector that has a smoke detector and a fire discriminator that judges a fire based on an output signal of the smoke detector, and outputs a fire signal when the fire discriminator judges a fire,
A light emitting element for irradiating light inside the smoke detector, a light receiving element for receiving scattered light emitted from the light emitting element and generated by smoke particles in the smoke detector, and a light irradiated from the light emitting element are detected. A plurality of light-shielding walls that prevent advancing to other than the smoke part,
A plurality of walls that prevent external light from entering the smoke inflow section, and a smoke inlet formed between the walls,
The photoelectric smoke detector, wherein the plurality of light shielding walls have a shape and an arrangement that match a relative light emission intensity distribution of the light emitting portion of the light emitting element with respect to the smoke detecting portion. In a photoelectric smoke detector that has a smoke detector and a fire discriminator that judges a fire based on an output signal of the smoke detector, and outputs a fire signal when the fire discriminator judges a fire,
The smoke detector includes a mounting part and a smoke inflow part,
The mounting part is
A light emitting element for irradiating light inside the mounting part; a light receiving element for receiving scattered light emitted from the light emitting element and caused by smoke particles in the smoke detecting part; and light emitted from the light emitting element for detecting smoke A plurality of light-shielding walls that prevent the advancing to other than the part,
The smoke inlet is
A plurality of walls that prevent external light from entering the smoke inlet, and a smoke inlet formed between the walls;
The mounting portion and the smoke inflow portion are
The smoke inflow portion is arranged so as to be on the lower side, communicated with the opening,
The photoelectric smoke detector, wherein the plurality of light shielding walls have a shape and an arrangement that match a relative light emission intensity distribution of the light emitting portion of the light emitting element with respect to the smoke detecting portion.   A part of the plurality of light shielding walls is arranged in the vicinity of the wall facing the light emitting element, and is configured as an optical trap that repeatedly attenuates reflection of light emitted from the light emitting element. The photoelectric smoke detector according to claim 1 or 2.

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