JPH0772073A - Scattered light type smoke sensor - Google Patents

Abstract

PURPOSE:To improve reliability by reducing a zero-point level to be as small as possible. CONSTITUTION:Such a light emitting element 12 is used that has approximately 10 deg. or smaller of a half-angle theta1 where an output power becomes half. The light emitting element 12 and a photodetector 13 are disposed so that a scattering angle theta2 when optical axes of the element 12 and the photodetector 13 intersect, is approximately not smaller than 60 deg. in order for the photodetector 13 not to detect a light directly from the light emitting element 12. At the same time, the element 12 and the photodetector 13 are arranged so that the scattering angle theta2 is approximately not larger than 80 deg. in order for the photodetector 13 not to detect a primary reflecting light reflected by a labyrinth member 91. The labyrinth member 91 facing a light emitting surface of the light emitting element 12 is formed, for example, to assume approximately 45 deg. of an angle theta3 to the optical axis of the light emitting element 12 to reflect the light from the light emitting element 12 in a direction opposite to the photodetector 13.

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 detector which senses smoke by detecting scattered light from the smoke.

[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 detector, since the light emitting element has a relatively wide directional angle, if the structure is made thin, a part of the direct light from the light emitting element or The light reflected by the labyrinth member is incident on the light receiving element, and the 0-point level becomes high.
There is a problem that it cannot be thinned.

Further, if a light emitting element is constructed 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 element to make the light emitting element thin, the beam becomes expensive and the beam is caused by an error in the mounting position of the light emitting element and the lens. Therefore, the productivity is deteriorated because a high degree of assembly accuracy is required. In view of the above conventional problems, it is an object of the present invention to provide a highly reliable scattered light smoke detector by reducing the zero point level as much as possible.

[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 light emitting element has a half-value angle of about 10 ° or less, and the light emitting section and the light receiving section are arranged such that the scattering angle at which the optical axes intersect is in the range of about 60 ° to 80 °. It is characterized in that the reflecting surface of the labyrinth member facing the light emitting surface and the light receiving surface of the light receiving portion do not face each other.

Desirably, the light emitting portion and the light receiving portion have a scattering angle of about 70 °, and the labyrinth member facing the light emitting surface of the light emitting portion has a reflecting surface with respect to the optical axis of the light emitting portion.
It is formed at about 45 °.

[0008]

According to the present invention, the light emitting element has a half-value angle of about 10 ° or less, and the light emitting portion and the light receiving portion are arranged so that the scattering angle is in the range of about 60 ° to 80 °, and the light emitting element emits light. Since the reflecting surface of the labyrinth member and the light-receiving surface of the light-receiving element do not face each other, the mounting accuracy of the light-emitting element and the light-receiving element is poor, or the optical axis is displaced due to variations in the light-emitting element itself. When the structure is made thin, a part of the direct light from the light emitting portion and the reflected light from the labyrinth member do not enter the light receiving portion, so that the zero point level can be lowered with a simple structure.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of a scattered light type smoke sensor according to the present invention. The light emitting element 12 is configured such that the so-called half value angle θ1 at which the output power P becomes a half value is about 10 ° or less, and the light emitting element 12 and the light receiving element 13 have a scattering angle θ2 at which the optical axes intersect from about 60 ° to 80 °. Of the labyrinth member 91 facing the light emitting surface of the light emitting element 12 is approximately 45 with respect to the optical axis of the light emitting element 12 so that the reflecting surface does not face the light receiving surface of the light receiving element 13. It is formed with a reflection angle θ3 of °.

FIG. 2 shows a plane and a cross section of the holder of the light emitting element 12 as seen from the side of an embodiment of the scattered light type smoke sensor according to the present invention, and FIG. 3 shows the plane and the light receiving element 13.
The cross section and the external appearance of the holder of FIG.
Note that in the side views shown in FIGS. 2 and 3, the light emitting element 12 is
Also, the light receiving element 13 and the insect screen 5 are not shown. Figure 2
And in FIG. 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).

The upper wall 8 also has a smoke detecting light emitting element 12 and a light receiving element 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.

The light emitting element 12 and the light receiving element 13 are arranged such that the angle at which the respective optical axes intersect, that is, the scattering angle θ2 is about 60 ° or more, so that the light receiving element 13 does not receive the direct light from the light emitting element 12. The light receiving element 13 is the labyrinth member 9
The scattering angle θ2 is arranged to be approximately 80 ° or less so that the primary reflected light reflected by 1 is not received.

The angle θ2 of the holders 10 and 11 in which the light emitting element 12 and the light receiving element 13 are housed is θ2 = 70.
It is desirable to form at. 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 chamber is only the front side thereof, and the tip and the light blocking portion are shielded. A gap 20 is formed by the plate 14. The width of the gap 20 orthogonal to the optical axis direction is, for example, 3 to 5 mm.
Formed in degrees.

The labyrinth member 9 has a flat surface 91a so that the end surface 91a does not face the light emitting surface of the light emitting element 12.
b 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 but is reflected in the outside direction to escape. In particular, the labyrinth member 91 facing the light emitting surface of the light emitting element 12 is configured to reflect light from the light emitting element 12 in a direction opposite to that of the light receiving element 13, for example, the light emitting element 12
Is formed so that the angle θ3 with the optical axis of is about 45 °.

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 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, since the light emitting element 12 having the half-value angle θ1 of about 10 ° or less is used, the S / N ratio can be improved.

Further, even if the mounting accuracy of the light emitting element 12 in 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.

In FIG. 7, the light emitting element 12 having a half value angle θ1 of 9 ° is used, and the scattering angle θ2, that is, the light emitting element 12 and the light receiving element 13 is used.
The crossing angle of each optical axis of 10 ° in the range of 30 ° to 90 °
Each 0-point output is shown every time and at 120 °. As is clear from the figure, the zero-point output decreased as the scattering angle θ2 increased from 30 ° to 70 °, and increased as the scattering angle θ2 increased from 70 °.

Therefore, the scattering angle θ2 is from 60 ° to 8
The labyrinth member 91, which is configured in the range of 0 ° and faces the light emitting surface of the light emitting element 12, is formed so as to reflect the light from the light emitting element 12 in a direction opposite to that of the light receiving element 13. Since the primary reflected light from the labyrinth member 91 is not received, the 0 point level can be lowered.

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 and diffused 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.

As a result, the S / N ratio can be improved, so that the reliability can be improved and a sufficient margin can be obtained against various noises such as dust and dew condensation. Furthermore, since the area that receives the reflected light in the smoke detection room is limited, it is only necessary to design the labyrinth structure in that light receiving area, so when designing the labyrinth structure for smoke inflow and ambient light. The degree of freedom of can be improved.

[0022]

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 a scattered light type smoke detector having a light receiving part and a light receiving part, the light emitting element has a half-value angle of about 10 °.
The light emitting portion and the light receiving portion are arranged so that the scattering angles at which the respective optical axes intersect are in the range of approximately 60 ° to 80 °, and further, the reflecting surface of the labyrinth member facing the light emitting surface of the light emitting portion. Since the light-receiving surfaces of the light-receiving unit are not facing each other, even if the light-emitting element and the light-receiving element are not assembled with each other in accuracy, or the optical axis is misaligned due to variations in the light-emitting element itself, Part of the direct light and the light reflected by the labyrinth member do not enter the light receiving portion, so that the zero point level can be lowered with a simple structure.

[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.

FIG. 7 is an explanatory diagram showing a relationship between a scattering angle and zero-point output.

[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. A scattered light type 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 their optical axes intersect with each other, wherein the light emitting element has a half-value angle of about 10 ° or less. The light emitting unit and the light receiving unit are arranged such that the scattering angles at which the respective optical axes intersect are in the range of about 60 ° to 80 °, and the reflecting surface of the labyrinth member facing the light emitting surface of the light emitting unit and the A scattered light type smoke detector characterized in that the light receiving surfaces of the light receiving portions are not opposed to each other. 2. The scattered light smoke detector according to claim 1, wherein the labyrinth member facing the light emitting surface of the light emitting portion has a reflection surface formed at an angle of about 45 ° with respect to the optical axis of the light emitting portion. A scattered light type smoke detector characterized by being provided.