JPH09198584A - Scattered light type smoke sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability by lowering the 0 point level of the detection output of scattered light by smoke. SOLUTION: Plural labyrinth members 9 are formed so as to be erected on an upper wall, a smoke detection chamber is formed in an area surrounded by the labyrinth members 9 and the respective optical axes of a light emitting element 12 and a light receiving element 13 are arranged so as to cross at the center of the smoke detection chamber. A parallel passage part 95 opened to the smoke detection chamber inside is formed between the adjacent labyrinth members 9-2 and 9-3 for instance and a labyrinth passage 76 provided with plural bends are formed on an outer side continuing to the parallel passage part 95. The labyrinth passage part continuing to the parallel passage part 95 is formed in a labyrinth structure provided with the bends at least on two parts.

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 sensor for detecting smoke by detecting scattered light from the smoke, and more particularly to a labyrinth structure of the scattered light type smoke sensor.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional smoke detector.
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 to have a substantially rectangular shape or a substantially L-shaped horizontal cross section in order to facilitate the flow of smoke from the outside and to block light from the outside. The labyrinth member 9
The smoke inlet formed by the space is surrounded by an insect screen 5 for preventing insects from entering the smoke detection chamber and generating scattered light.

The light emitting element 12 and the light receiving element 13 are respectively housed in the upper wall 8 such that the light axes of the light emitting element 12 and the light receiving element 13 intersect at the center of the smoke detection room formed by the labyrinth member 9. Recesses 10 and 11 for
A light-shielding plate 14 is formed so as to protrude from the light-emitting element 12 to prevent the light emitted from the light-emitting element 12 from directly reaching the light-receiving element 13. An opening is formed so as not to directly receive light. Here, the viewing area of the light receiving element 13 is a hatched portion b.

[0004] When smoke flows into the smoke detection chamber with respect to the zero point level of the detection output of the light receiving element 13 in the absence of smoke, light scattered by the smoke is detected by the light receiving element 13.

[0005]

However, in the above-mentioned conventional sensor, each labyrinth member 9 simply makes it easy for smoke from the outside to flow in, and blocks light from the outside. Since the light receiving element 13 is only configured not to directly receive the light, the light of the light emitting element 12 is reflected many times by the plane portion and the end face and edge of the labyrinth member 9 and diffuses into the smoke detection chamber. I do. Further, since the field of view of the light receiving element 13 is relatively wide, the diffused light reaches the light receiving surface of the light receiving element 13 and the level of the zero point of the detection output of the light receiving element 13 is increased, so that the S / N ratio is reduced. And the reliability is lowered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a scattered light type smoke detector capable of improving the reliability by lowering the zero point level of detection output of scattered light due to smoke. I do.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention makes it easier for smoke from the outside to flow in, blocks light from the outside, and forms a smoke detecting chamber in the central portion. In a scattered light smoke detector having a labyrinth member and a light emitting element and a light receiving element arranged so that the respective optical axes intersect in a smoke detection chamber formed by the labyrinth member, between the adjacent labyrinth member, A parallel passage portion having an opening is formed in the smoke detection chamber, and a labyrinth passage having a plurality of bends is formed outside the parallel passage portion. In this case, the labyrinth passage portion following the parallel passage portion is formed in a maze structure having at least two bends.

According to the present invention, the labyrinth structure is such that the parallel passage portion and the labyrinth passage portion continue from the inside to the outside between the adjacent labyrinth members, so that the parallelism between the internal smoke detection chamber and the labyrinth member is increased. The light incident on the passage part travels outward while repeating reflection on the opposite parallel surfaces, is trapped by the trap of the labyrinth passage part formed at the exit part, and the return of the reflected light to the internal smoke detection chamber is blocked. The reliability can be improved by lowering the 0-point level of the detection output of scattered light due to smoke.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an embodiment of a scattered light smoke detector according to the present invention. In FIG. 1, the smoke detector main body 2 is formed in a substantially cylindrical shape as in the conventional example.
The upper wall 8 (not shown in FIG. 1) as shown in FIG. The upper wall 8 has a plurality of labyrinth members 9-1 to 9-9.
-8 is formed to stand upright, and this labyrinth member 9
A smoke detection chamber is formed in a region surrounded by -1 to 9-8. Each of the labyrinth members 9-1 to 9-8 is formed to facilitate the inflow of smoke from the outside and to block the light from the outside.

The smoke inlet formed by the labyrinth members 9-1 to 9-8 is surrounded by an insect screen 5 for preventing insects from entering the smoke detection chamber and generating scattered light. Has been done. The upper wall 8 also has a labyrinth member 9-1.
Holders formed as recesses for accommodating the light emitting element 12 and the light receiving element 13 so that the optical axes of the light emitting element 12 and the light receiving element 13 intersect in the center of the smoke detection chamber formed by 9-8. Parts 10, 11 and light emitting element 12
A light shielding plate 14 for preventing the emitted light from directly reaching the light receiving element 13 is formed so as to stand upright. Also,
The light from the light emitting element 12 is received in the holder sections 10 and 11 by the light receiving element 1.
Apertures 22 and 21 for narrowing each field of view are formed so that 3 does not receive light directly.

This embodiment is characterized in that a labyrinth structure having a parallel passage portion and a labyrinth passage portion is provided by the adjacent labyrinth members. Labyrinth members 9-1 to 9-7 among labyrinth members 9-1 to 9-8
Are about the same length. Labyrinth members 9-1 to 9-7
The passage structure according to, for example, labyrinth members 9-2, 9-
As shown in FIG. 3, the parallel passage portion 94 and the labyrinth passage portion 96 are sequentially formed from the inside.

The parallel passage portion 95 is formed by providing the flat portion 91 of the labyrinth member 9-2 with a tip bent portion 92 having a flat portion 93 parallel to the tip of the adjacent labyrinth member 9-3. The labyrinth passage 96
Is formed by providing a rear end bent portion 93 at the rear end of the labyrinth member 9-2 on the smoke inlet side. According to the passage structure having the parallel passage portion 95 and the labyrinth passage portion 96, the light incident from the light emitting element 12 to the parallel passage portion 95 is flat portion 93 parallel to the flat portion 91 forming the parallel passage portion 95. It advances to the outside while reflecting between and. This state is similar to a state in which light travels while reflecting on a parallel path such as an optical fiber.

The light that has passed through the parallel passage portion 95 then enters the labyrinth passage portion 96 and is repeatedly attenuated and absorbed in the labyrinth structure having a plurality of bends due to the formation of the rear end bent portion 94, or smoke is absorbed. It is not reflected to the outside through the inflow port and never returns to the smoke detection room. Therefore, the zero-point level of the detection output of scattered light due to smoke can be further lowered.

Further, since the rear end bending member 94 is provided on the smoke inlet side of the labyrinth passage 96, the rear end bending member 94 can prevent external light from entering the inside. Further, since the number of bends of the labyrinth passage 96 is increased (the number of traps is increased) by the rear end bending member 94, the internal light can be reflected many times, and if the internal light is reflected and returns to the inside again. Can also be sufficiently damped.

FIG. 2 shows another embodiment of the present invention, which is characterized in that the rear end bent portion 94 located outside the rough billyrinth passage portion 96 provided in the embodiment of FIG. 1 is removed. To do. By excluding the rear end bent portion 94 of the labyrinth passage 96 in this manner, the internal light incident on the labyrinth passage 96 can be emitted to the outside, and the smoke inflow property can be improved.

[0016]

As described above, according to the present invention, a plurality of labyrinth members for facilitating inflow of smoke from the outside and blocking light from the outside and forming a smoke detection chamber in the central portion are provided by the labyrinth member. In a scattered light smoke detector having a light emitting element and a light receiving element arranged so that the respective optical axes intersect in a formed smoke detection chamber, a parallel passage from the inside to the outside between the adjacent labyrinth member. Since the labyrinth structure has a maze part and a labyrinth passage part, light entering the parallel passage part between the labyrinth member from the internal smoke detection chamber travels outward while repeating reflection on the opposite parallel surfaces, and exits. Since the labyrinth passage formed in the section has multiple bends, the return of reflected light to the internal smoke detection chamber is blocked, and the zero point level of the detection output of scattered light due to smoke is lowered to improve reliability. It is possible.

[Brief description of drawings]

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

FIG. 2 is a plan view showing another embodiment of the scattered light type smoke sensor according to the present invention.

FIG. 3 is a plan view showing a conventional scattered light type smoke detector.

[Explanation of symbols]

 2: Main body of smoke detection section 5: Insect screen 9-1 to 9-6: Labyrinth member 10, 11: Holder section 12: Light emitting element 13: Light receiving element 14: Light shielding member 21, 22: Opening 91: Flat section 92: Tip Bent portion 93: Plane portion 94: Rear end bent portion 95: Parallel passage portion 96: Labyrinth passage 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 type smoke sensor having a light emitting element and a light receiving element arranged so that optical axes intersect, each of the labyrinth members is a parallel opening that opens to an internal smoke detection chamber between adjacent labyrinth members. A scattered light smoke detector characterized in that a labyrinth passage portion having a plurality of bends is formed outside the parallel passage portion while forming the passage portion. 2. The scattered light type smoke sensor according to claim 1, wherein the labyrinth passage portion has a bend at least at two positions.