JPH0772075A - Scattered light smoke detector - Google Patents

Abstract

(57) [Abstract] [Purpose] With a simple structure, the 0-point level is lowered in the case of thinning to improve reliability. [Structure] The light emitting element 12 is arranged at a position A on the circumference of a substantially cylindrical smoke detection chamber. The light emitting element 12 and the labyrinth member 91 facing the light emitting surface of the light emitting element 12 are arranged such that the emission range (θ1) of the light emitting element 12 is within the height H of the labyrinth member 91 (the height in the smoke detection chamber). It is located in. The height H of the labyrinth member 91 is formed to be approximately 20 mm or less.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In this type of scattered light type smoke sensor, a labyrinth member forms a smoke detecting chamber for efficiently inflowing smoke from the outside and blocking light from the outside, and a light emitting section is provided in the smoke detecting chamber. Is arranged so that the respective optical axes of the light receiving part and the light receiving part intersect with each other so that scattered light due to smoke is detected.

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

[0004]

However, in the above-mentioned conventional scattered light type smoke sensor, since the light emitting element has a relatively wide directional angle, if the structure is made thin, the direct light from the light emitting element is directly emitted from the smoke detecting chamber. The surface and the bottom surface of the ceiling of the above are reflected in the vertical direction, and the reflected light and the light reflected again by these surfaces and the labyrinth member are incident on the light receiving element to increase the 0-point level, and therefore, be thin. There is a problem that you cannot do it. Further, if the ceiling-side surface or the bottom surface in the smoke detection room becomes dirty, the 0-point level becomes even higher.

Therefore, a means of providing a diaphragm (opening) or an eaves on the front surface of the light emitting element is used, but with this, it is not possible to effectively use all the irradiation light of the light emitting element, and the device cost also increases. There is a point.
In view of the above-mentioned conventional problems, an object of the present invention is to provide a scattered light type smoke sensor which has a simple structure and can reduce the 0-point level when it is made thin to improve reliability.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a plurality of labyrinths for facilitating inflow of smoke from the outside and blocking light from the outside to form a smoke detecting chamber in the central portion. Member, and a scattered light smoke detector having a light emitting part and a light receiving part respectively provided with a smoke detecting light emitting element and a light receiving element arranged so that respective optical axes intersect in a smoke detecting chamber formed by the labyrinth member. In the above, the radiation range of the light emitting portion is arranged so as to be within the height of the surface of the labyrinth member facing the light emitting surface of the light emitting portion.

Further, specifically, the height of the surface of the labyrinth member facing the light emitting surface of the light emitting portion is formed to be about 20 mm or less.

[0008]

In the present invention, since the emission range of the light emitting portion is arranged within the height of the surface of the labyrinth member facing the light emitting surface of the light emitting portion, the direct light of the light emitting element emits light in the vertical direction. Since it is reflected only by the labyrinth member facing the light emitting surface of the section and not by the ceiling-side surface and the bottom surface in the smoke detection chamber, the zero point level can be lowered.

[0009]

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 the scattered light smoke detector according to the present invention, and the positions shown in the drawing are schematic. For ease of explanation, the smoke detection chamber is formed in a substantially cylindrical shape, that is, in a substantially circular shape in the horizontal direction, and the light emitting element 12 is apparently arranged at a point A on this circumference. And
The light emitting element 12 arranged at this position A and the light emitting element 1
The labyrinth member 91 facing the light emitting surface of No. 2 is arranged such that the radiation range (θ1 in the drawing) of the light emitting element 12 is within the height H of the surface of the labyrinth member 91 (that is, the height inside the smoke detection chamber). The height H of the member 91 is specifically about 2
It is formed to be 0 mm or less.

In the horizontal direction, the light emitting element 12
The labyrinth member 91 prevents the light receiving element 13 from receiving the primary reflected light from the labyrinth member 91 facing the light emitting surface of the light receiving surface of the light receiving element 13 and the optical axis of the light emitting element 12 of the light receiving element 13. It is formed with a reflection angle of about 45 ° with respect to AD, and the light receiving element 13 is arranged so that its field of view does not include the reflection surface of the labyrinth member 91 and passes through substantially the center O of the smoke detection chamber. ing. The light receiving element 13 is also 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 other labyrinth members.

In such a structure, if the distance from the apparent position A of the light emitting element 12 to the furthest position of the reflecting surface of the labyrinth member 91 is L, and the aperture d of the light emitting element 12 (described later) is d. The so-called half-value angle θ1 at which the output power of the light receiving element 13 becomes half-value is configured so that θ1 <tan ⁻¹ (HD) / 2L. Also, the height H in the smoke detection chamber is 2
In the thin smoke sensor of 0 mm or less, the light emitting element 12 with θ1 <10 ° is selected in consideration of the variation at the time of assembly.

According to this structure, the direct light of the light emitting element 12 is reflected only by the labyrinth member 91, and is not reflected by the ceiling side surface and the bottom surface (the surface opposite to the ceiling side) of the smoke detection chamber. The 0 point level can be lowered. FIG. 2 shows a cross section and an external view of a plane and a holder of a light emitting element 12 of a scattered light type smoke sensor according to an embodiment of the present invention as viewed from the side, and FIG. 3 shows a plane and a holder of the light receiving element 13 as a side surface. The cross section and the external appearance seen from are shown. 2 and 3, the light emitting element 12, the light receiving element 13 and the insect screen 5 are not shown.

2 and 3, the smoke detector 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 upright on the upper wall 8, and a smoke detection chamber is formed in a region surrounded by the labyrinth members 9. Each labyrinth member 9 is formed so as to facilitate the inflow of smoke from the outside and block the light from the outside. The smoke inlet 5a formed between the labyrinth members 9 is surrounded by an insect screen 5 for preventing insects from entering the smoke detection chamber and generating scattered light. The bottom opening (on the side opposite to the upper wall 8) is covered with a cover (not shown).

On the upper wall 8, the smoke detecting light emitting element 12 and the light receiving element 12 are arranged so that the optical axes of the light emitting element 12 and the light receiving element 13 intersect at the center of the smoke detecting chamber formed by the labyrinth member 9. Holders 10 and 11 which are concave portions for housing 13 respectively, and a light shielding plate 14 for preventing the emitted light of the light emitting element 12 from directly reaching the light receiving element 13.
Are formed so as to stand. In addition, the holder 10,
Reference numerals 11 and 11 denote openings 22 and 21 for narrowing the fields of view so that the light receiving element 13 does not directly receive the light from the light emitting element 12.
Are formed. Here, a holder 1 having an opening 22
0 and the light emitting element 12 constitute a smoke detecting light emitting section, and the holder 11 having the opening 21 and the light receiving element 13 constitute a smoke detecting light receiving section.

As the light emitting element 12 housed in the holder 10, one having a so-called half value angle θ1 at which the output power P has a half value as shown in FIGS. 4 and 5 is about 10 ° or less is used. Has a tip formed of an epoxy lens 12a or the like so that the emitted light from the chip 12b is focused so that the half-value angle θ1 is about 10 ° or less.

Further, the labyrinth member 91 facing the light emitting surface of the light emitting element 12 is formed to be 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 its front side. Tip and light shield 14
A gap 20 is formed by. The width of the gap 20 orthogonal to the optical axis direction is formed to be, for example, about 3 to 5 mm. All the labyrinth members 9 are arranged such that the tip end surface 91a does not face the light emitting surface of the light emitting element 12, and the flat surface portion 91b
Is formed at such an angle that the emitted light of the light emitting element 12 is not reflected in the direction of the light receiving surface of the light receiving element 13 and is reflected in the outside direction to escape.

In FIG. 6, 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 (degree), 9 degree, 13 degree, 15 degree, and 20 degree.
As is clear from the figure, the S / N ratio increased as the half-value angle θ1 increased to 9 °, and decreased as it increased from 9 °. Therefore, the light emitting element 12 has a half-value angle θ.
S / N as 1 is less than about 10 ° is used.
The ratio can be improved.

Further, even if the accuracy of assembling the light emitting element 12 into the holder 10 is poor or the optical axis is deviated due to the variation of the light emitting element 12 itself, the output power of the light emitting element 12 is kept within the visual field of the light receiving element 13. In addition, the output value due to smoke becomes larger than that when a light emitting element having a wide directional angle is used. Furthermore, since no lens or the like is incorporated, the structure can be inexpensive, 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 smoke detecting light emitting element 12 is repeatedly reflected by the flat surface portion 91b of the labyrinth member 9 and the edge of the tip thereof and diffuses into the smoke detecting chamber, the diffused light is emitted to the labyrinth member 91. Since the light-shielding plate 14 blocks the light-receiving element 13 and the field of view of the light-receiving element 13 is relatively small due to the gap 20 and the opening 21, the 0-point level of the detection output of the light-receiving element 13 can be lowered. it can.

[0020]

As described above, the present invention makes it easier for smoke from the outside to flow in and blocks the light from the outside.
Light emission including a plurality of labyrinth members forming a smoke detection chamber in the central portion, and a smoke detection light emitting element and a light receiving element arranged so that respective optical axes intersect in the smoke detection chamber formed by the labyrinth member. In the scattered light type smoke sensor having a light emitting part and a light receiving part, since the emission range of the light emitting part is arranged to be within the height of the surface of the labyrinth member facing the light emitting surface of the light emitting part, In the vertical direction, the light is reflected only by the labyrinth member facing the light emitting surface of the light emitting section, and not by the ceiling side surface and the bottom surface in the smoke detection chamber, so that the zero point level can be lowered.

[Brief description of drawings]

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

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

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

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

[Explanation of symbols]

 2: Main body of smoke detector 5: Insect screen 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 Detection light-receiving element 14: Light-shielding members 21, 22: Opening 91a: Tip surface 91b: Flat surface portion

Claims (2)

[Claims] 1. A plurality of labyrinth members for facilitating inflow of smoke from the outside and blocking light from the outside to form a smoke detecting chamber in a central portion, and a smoke detecting chamber formed by the labyrinth members. In a scattered light smoke sensor having a light emitting part and a light receiving part each having a smoke detecting light emitting element and a light receiving element arranged so that the optical axes intersect, the emission range of the light emitting section is a light emitting surface of the light emitting section. The scattered light type smoke detector characterized in that it is arranged within the height of the surface of the labyrinth member facing to. 2. The scattered light type smoke sensor according to claim 1, wherein the surface of the labyrinth member facing the light emitting surface of the light emitting portion has a height of about 20 mm or less. vessel.