JP2721788B2 - Scattered light smoke detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scattered light smoke sensor for detecting smoke by detecting scattered light caused by smoke.
In particular, the present invention relates to a thin scattered light type smoke detector whose height in a smoke detection chamber is about 20 mm or less.

[0002]

2. Description of the Related Art In a scattered light type smoke detector of this type, a labyrinth member is provided to form a smoke detection chamber for efficiently flowing in smoke from the outside and blocking light from the outside. The light receiving unit is arranged so that the optical axes thereof intersect with each other to detect light scattered by smoke.

In such a conventional scattered light type smoke detector,
Infrared LED (light emitting diode) having a relatively wide directional angle of 30 to 60 ° as a light emitting element constituting a light emitting unit
Is used, so that the light receiving section does not receive the direct light of the relatively wide directivity angle of this infrared LED, the scattering angle at which the light axis of the light emitting section and the light axis of the light receiving section intersect, and the shape and reflection angle of the labyrinth member. Must be devised.

[0004]

However, in the above-mentioned conventional scattered light type smoke detector, since the light emitting element has a relatively wide directional angle, direct light from the light emitting element emits light in the smoke detection chamber when the structure is reduced in thickness. The light reflected in the vertical direction by the surface or bottom surface on the ceiling side and the reflected light and the light reflected again by these surfaces and the labyrinth member enter the light receiving element to increase the zero point level, and therefore, to reduce the thickness. There is a problem that can not be. Further, if the ceiling surface or the bottom surface in the smoke detection room becomes dirty, the zero point level is further increased.

[0005] Further, by providing a stop (opening) for narrowing the irradiation range of the light emitting element, it is possible to prevent an increase in the zero point level, but in this case, all the irradiation light of the light emitting element is used effectively. The signal amount due to the scattered light of smoke is reduced. Furthermore, if the light emitting section is configured by incorporating a lens or the like in front of the light emitting element in order to narrow the directional angle of the light emitting section to make it thinner, it becomes expensive and the direction of the beam is increased due to an error in the mounting position of the light emitting element and the lens. As a result, a high degree of assembly accuracy is required, and the productivity is reduced.

The present invention has been made in view of the above-described conventional problems, and has as its object to provide a scattered light type smoke detector which can improve the reliability by lowering the zero point level when the thickness is reduced.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a plurality of labyrinths which facilitate the flow of smoke from the outside, block light from the outside, and form a smoke detection chamber at the center. A smoke detection chamber formed by the labyrinth member, the smoke detection chamber includes a light emitting unit and a light receiving unit respectively provided with a light emitting element and a light receiving element for smoke detection arranged so that respective optical axes intersect. In a scattered light smoke detector having a height of about 20 mm or less, the half-value angle of the light emitting element is about 5 ° or more.
It is characterized by 10 °.

[0008]

According to the present invention, in the scattered light type smoke detector in which the height of the smoke detection chamber is about 20 mm or less, a light emitting element having a half value angle of about 5 ° to 10 ° is used. It is easy to prevent the direct light of the light emitting element from being reflected only by the labyrinth member facing the light emitting surface of the light emitting unit, and not to be reflected by the ceiling side surface and the bottom surface in the smoke detection room. be able to.

In addition, since it is not necessary to narrow the irradiation range of the light emitting element by the stop, the signal amount due to the scattered light of smoke can be increased, and furthermore, the irradiation range of the light emitting element does not need to be narrowed by a lens, so that it is inexpensive. The direction of the beam does not shift due to the assembling accuracy of the light emitting element and the lens.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a side surface and a plane of an embodiment of a scattered light type smoke detector according to the present invention, and positions shown in the figure are schematic. For ease of explanation, the smoke detection chamber is formed in a substantially cylindrical shape, that is, in a substantially circular horizontal direction, and the light emitting element 12 is apparently arranged at one point A on this circumference. And
The light emitting element 12 arranged at the position A has a so-called half-value angle θ1 at which the output power P becomes a half value of about 5 ° to 10 °, and its emission range faces the light emitting surface of the light emitting element 12. The height of the labyrinth member 91 is set to be within the height H (that is, the height in the smoke detection chamber). The height H of the labyrinth member 91 is specifically formed to be approximately 20 mm or less.

In the horizontal direction, the light emitting element 12
The labyrinth member 91 is arranged so that the reflective surface does not face the light receiving surface of the light receiving element 13 and the optical axis of the light emitting element 12 so that the light receiving element 13 does not receive the primary reflected light by the labyrinth member 91 facing the light emitting surface of the light emitting element 12. The light receiving element 13 is formed so that its field of view does not look at the reflection surface of the labyrinth member 91 and its optical axis is located ahead of the tip of the labyrinth member 91. It is arranged so as to pass through substantially the center O of the chamber. Light receiving element 1
Numeral 3 is arranged so as not to receive the direct light from the light emitting element 12 and the secondary reflected light reflected by the labyrinth member 91 and reflected by another labyrinth member.

FIG. 2 is a plan view of a scattered light type smoke detector according to an embodiment of the present invention and a cross-sectional view of a holder of the light emitting element 12 as viewed from the side, and FIG.
2 shows a cross section and appearance of the holder of FIG.
Note that, in the side views shown in FIG. 2 and FIG.
Also, the light receiving element 13 and the insect net 5 are not shown. FIG.
3 and FIG. 3, the smoke detection unit main body 2 is formed in a substantially cylindrical shape, and the upper wall 8 is attached to the ceiling. A plurality of labyrinth members 9 are formed on the upper wall 8 so as to be erected, and a smoke detection chamber is formed in a region surrounded by the labyrinth members 9. Each labyrinth member 9 is formed so that smoke from the outside easily flows in and light from the outside is blocked. The smoke inlet 5a formed between the labyrinth members 9 is surrounded by an insect net 5 for preventing insects from entering the smoke detection chamber and generating scattered light. The bottom opening (the side opposite to the upper wall 8) is covered with a cover (not shown).

The upper wall 8 also includes a light emitting element 12 for smoke detection and a light receiving element so that the respective optical axes of the light emitting element 12 and the light receiving element 13 intersect at the center of the smoke detection chamber formed by the labyrinth member 9. Holders 10 and 11, which are recesses for accommodating the light-receiving elements 13, respectively, and a light-shielding plate 14 for preventing light emitted from the light-emitting element 12 from directly reaching the light-receiving element 13.
Is formed to stand upright. Also, the holder 10,
11 are openings 22 and 21 for narrowing the respective fields of view so that the light from the light emitting element 12 is not directly received by the light receiving element 13.
Are formed. Here, the holder 1 having the opening 22
0 and the light emitting element 12 constitute a light emitting section for smoke detection, and the holder 11 provided with the opening 21 and the light receiving element 13 constitute a light receiving section for smoke detection.

As shown in FIGS. 4 and 5, the light emitting element 12 housed in the holder 10 has a so-called half-value angle θ1 at which the output power P becomes a half value, which is approximately 5 ° to 10 °. The element 12 has an epoxy lens 12a at the tip.
And the like, and by converging the radiated light of the chip 12b, the half value angle θ1 is configured to be approximately 5 ° to 10 °.

The labyrinth member 91 facing the light emitting surface of the light emitting element 12 is formed relatively longer than the other labyrinth members 9 so that the field of view of the light receiving element 13 with respect to the smoke detection room is only in front of the light detecting element 13. Tip and light shield 14
Thus, a gap 20 is formed. The width of the gap 20 orthogonal to the optical axis direction is, for example, about 3 to 5 mm. All the labyrinth members 9 are arranged such that the front end surface 91a does not face the light emitting surface of the light emitting element 12 and the flat portion 91b
Are formed so as not to reflect the radiated light of the light-emitting element 12 in the direction of the light-receiving surface of the light-receiving element 13 and to reflect and escape in the external direction.

FIG. 6 shows that the half-value angle θ1 is 4 °, 7 °, 7.5.
It is the experimental data which measured each S / N ratio using the light emitting element 12 of °, 9 °, 13 °, 15 °, and 20 °.
As is clear from the figure, the S / N ratio increased as the half-value angle θ1 increased to 9 °, and decreased as the half-value angle θ1 increased from 9 °. Therefore, the light emitting element 12 has a half-value angle θ
1 is approximately 5 ° to 10 °, so that S /
The N ratio can be improved. Here, when the angle is 10 ° or more, the amount of light emission is dispersed, so that scattered light due to smoke cannot be obtained effectively. On the other hand, when the angle is 5 ° or less,
The relative emission of light is too narrow
Intensity increases, but on the other hand, the amount of scattered light decreases
Will be.

Further, even if the accuracy of assembling the light emitting element 12 into the holder 10 is poor or the optical axis is shifted due to the variation of the light emitting element 12 itself, the output power of the light emitting element 12 is kept within the field of view of the light receiving element 13. In addition, the output value due to smoke becomes larger than when a light emitting element having a wide directivity angle is used. Further, since a lens or the like is not incorporated, the configuration can be made inexpensively, and the beam direction does not shift due to the assembling accuracy of the light emitting element and the lens.

Further, even if the light of the light emitting element 12 for smoke detection is reflected many times by the flat portion 91b of the labyrinth member 9 and the edge of the tip and diffuses into the smoke detection chamber, the diffused light is transmitted to the labyrinth member 91. Since the light receiving element 13 is shielded from the light receiving element 13 by the light shielding plate 14 and the field of view of the light receiving element 13 is formed by the gap 20 and the opening 21 and is relatively small, it is necessary to lower the zero point level of the detection output of the light receiving element 13. it can.

As a result, the S / N ratio can be improved, so that the reliability can be improved and a sufficient margin can be obtained for various noises such as dust and dew. Furthermore, since the area for receiving the reflected light in the smoke detection room is limited, the labyrinth structure of the light receiving area can be designed primarily, so when designing the labyrinth structure for smoke inflow and disturbance light Degree of freedom can be improved.

[0020]

As described above, the present invention makes it easy for external smoke to flow in and blocks external light,
A plurality of labyrinth members forming a smoke detection room in the center, and a light emission including a smoke detection light emitting element and a light receiving element each arranged so that each optical axis intersects in the smoke detection room formed by the labyrinth member. In a scattered light type smoke detector having a smoke detection chamber having a height of about 20 mm or less, the half-value angle of the light-emitting element is approximately 5 ° to 10 °, so that the light-emitting element Is reflected only by the labyrinth member facing the light-emitting surface of the light-emitting section, and is easily prevented from being reflected by the ceiling-side surface and the bottom surface in the smoke detection room. Therefore, it is possible to lower the zero point level. it can.

Further, since it is not necessary to narrow the irradiation range of the light emitting element by the aperture, it is possible to increase the signal amount due to the scattered light of smoke, and it is not necessary to narrow the irradiation range of the light emitting element by the lens, so that the configuration is inexpensive. The direction of the beam does not shift due to the assembling accuracy of the light emitting element and the lens.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a scattered light type smoke detector according to the present invention.

FIG. 2 is an explanatory view showing a plane and a side cross section of one embodiment of the scattered light type smoke detector according to the present invention.

FIG. 3 is an explanatory view showing a plane and a side cross section of one embodiment of the scattered light type smoke detector according to the present invention.

FIG. 4 is an explanatory view showing a light emitting device according to the present invention.

FIG. 5 is an explanatory diagram showing a half-value angle of a light-emitting element according to the present invention.

FIG. 6 is an explanatory diagram showing a relationship between a half-value angle of a light-emitting element and an S / N ratio.

[Explanation of symbols]

 2: Smoke detection unit main body 5: Insect repellent net 5a: Smoke inlet 8: Upper wall 9, 91: Labyrinth member 10, 11: Recess (holder) 12: Light emitting element for smoke detection 12a: Epoxy lens 12b: Chip 13: Smoke Light receiving element for detection 14: Light shielding member 21, 22: Opening 91a: Tip surface 91b: Flat portion

Claims (1)

(57) [Claims] A plurality of labyrinth members forming a smoke detection chamber at a central portion, and a smoke detection chamber formed by the labyrinth member. In a scattered light type smoke detector having a light emitting unit and a light receiving unit respectively provided with a light emitting element for smoke detection and a light receiving element arranged so that optical axes intersect, and the height of the smoke detection chamber is about 20 mm or less. A scattered light type smoke detector, wherein a half-value angle of the light emitting element is approximately 5 ° to 10 °.