CN85106166A

CN85106166A - Scattered-light type smoke detector

Info

Publication number: CN85106166A
Application number: CN 85106166
Authority: CN
Inventors: 长岛哲也
Original assignee: Hochiki Corp
Current assignee: Hochiki Corp
Priority date: 1985-08-15
Filing date: 1985-08-15
Publication date: 1987-03-04

Abstract

A scattered-light type smoke detector is incorporated into smog an inlet in the black chamber having some on its periphery.In black chamber, be placed with a light radiating portion that launches light into this black chamber and a reception optical transmitting set emission and by the light receiving part of the light of smog scattering, and the optical axis that makes them is with 145 ° angle of intersection substantially.Under such arrangement, can obtain one and have 4%/the grey cigarette of foot or littler extinctivity under and the light output of under the black smoke of 10%/foot extinctivity, satisfying the detection sensitivity of UL standard-required.

Description

Scattered-light type smoke detector

The present invention is relevant with a kind of scattered-light type smoke detector, this detecting device by a light radiating portion with optical radiation to a Smoke Detection zone and allow ray cast to a light receiving part of the smog institute scattering that enters the Smoke Detection zone have the ability that detects smog.

Require such smoke-detectors to provide a light output with predetermined detection sensitivity to smog with certain extinctivity.For example, according to the strictest UL standard, for the grey smog that produces by the burning cotton lamp wicks, under 4%/foot or littler extinctivity and, be issued to predetermined fire alarm detection sensitivity at 10%/foot or littler extinctivity for the black smog that produces by the oil of burning as kerosene.

An object of the present invention is to provide the smoke-detectors of a scattered-light type, it has the Smoke Detection characteristic that satisfies strict UL standard, can make the light amount maximum of smog institute scattering, and can make stray light minimum when not having smog.

In order to achieve this end, an optimum embodiment of the present invention includes a black chamber, on its periphery, there are some that smog is introduced the inlet of black chamber, thereby so just make that the light that sends from a light radiating portion can project the light receiving part that is used to detect smog by the smog scattering that enters by these inlets.Light radiating portion and light receiving part all in this black chamber, settle their mode to make that their optical axis is the angle of intersection with 145 ° substantially.

According to the present invention, for having 4%/the grey cigarette of foot or littler extinctivity or, can both reach a light output of satisfying the detection sensitivity of UL standard-required, and make and disturb light to reduce to minimum having the black smoke of 10%/foot or littler extinctivity.

Other purpose of the present invention and effect are clearly according to following description.

Fig. 1 is the explanatory of one embodiment of the invention.

Fig. 2 is the curve map that concerns between the light output of an expression scattered-light type smoke detector according to the invention and grey cigarette and the black smoke smoke density.

The light output of scattered-light type smoke detector according to the invention and the graph of relation between grey cigarette and the black smoke smoke density when Fig. 3 is the little optical axis intersection of an expression angle.

Fig. 4 is 145 ° of expressions.Light output during the angle of intersection is assumed to the curve map of 1 o'clock relative output.

To be described an optimum embodiment of the present invention now.

With reference to Fig. 1, the detecting device housing 1 that testing circuit wherein is housed is installed on the detecting device base, and this base is fixed on ceiling etc.An outer cover 3 that a plurality of smog inlets 2 are arranged on its periphery is arranged in the bottom of detecting device housing 1,3 li of outer covers, an inner cover 4 is arranged, it has one and stops extraneous light 2 to enter but constitutes the maze-type structure of the passage of introducing smog by entering the mouth.Outer cover 3 and inner cover 4 are installed in the bottom of detecting device housing 1, form a black chamber.

Bearing 5 is installed on the upper inside wall of deceiving the chamber, is at the end of detecting device housing, and a photocell 6 is installed on the right side of bearing 5, in its left side, through lens 8 photodetector 7 has been installed.Photocell 6 and photodetector 7 are placed to such an extent that their optical axis 9 and 10 is pointed to obliquely down, and intersect at 11 places, Smoke Detection zone that are positioned at black chamber center section.In the present invention, the optical axis 10 of the optical axis 9 of photocell 6 and photodetector 7 is substantially with 145 ° angle of intersection.When photocell 6 and photodetector 7 are installed, adjust their position as required, still, because the structural restriction of fixed light radiated element 6 and photodetector 7, the tolerance limit of angle of intersection θ can be in 145 ± 2.5 ° scope.

Be adjusted into 145 ° by the angle of intersection of optical axis in the Smoke Detection zone with photocell 6 and photodetector 7, just can reach as the UL prescribed by standard, to having 4%/the grey cigarette of foot or littler extinctivity and to the light output of the predetermined detection sensitivity of black smoke with 10%/foot or littler extinctivity.

Why the angle of intersection θ that will explain now at Smoke Detection zone 11 place's photocells and photodetector optical axis will be transferred to 145 ° reason.

Experiment confirms that when the angle of intersection θ of the optical axis of photocell 6 and photodetector 7 changed, angle of intersection θ was littler, and the difference between the light output down of light output grey cigarette under and black smoke heals greatly.

When Fig. 2 had drawn and has been adjusted to 145 ° by angle of intersection θ of the present invention, light output was to the relation of different smoke densitys under grey cigarette and the black smoke situation.If stipulate that the light output of required detection sensitivity is 1.8 volts, so, for reaching the output of 1.8 volts of light, be 4%/foot to the grey cigarette that produces by the burning cotton lamp wicks, the extinctivity that its smoke density has, and be 10%/foot the black smoke that produces by burning kerosene, the extinctivity that its smoke density should have.

Fig. 3 has represented to be reduced to the variation relation of 90 ° of time outputs with respect to grey cigarette and black smoke smoke density as angle of intersection θ.Though be 4% for having extinctivity/the grey cigarette of the smoke density of foot obtained 0.6 volt light output of needs, to black smoke have only when its density increase to 16%/foot extinctivity the time just reach 0.6 volt.

Relative output when Fig. 4 has represented that the light output when the angle of intersection is 145 ° is assumed to 1 and the relation of the angle of intersection.When angle of intersection θ diminished, output reduced relatively, will understand according to Fig. 4, obtained the maximum amount of smog scattering when the angle of intersection is 145 °.

By Fig. 2,3 and 4 shown experimental datas, obviously, angle of intersection θ is littler, and the relative difference under grey cigarette and the black smoke between the light output is just bigger.As by can finding out on the family curve of Fig. 2, to grey cigarette with 4%/foot or littler extinctivity and the black smoke with 10%/foot or littler extinctivity, the angle of intersection that can both reach the sensitivity that requires is 145 °.

When angle of intersection θ becomes bigger, as by finding out on Fig. 1, can cause the direct more each other relative position of photocell 6 and photodetector 7, this will increase stray light.Owing to this reason, as previously mentioned, angle of intersection θ is preferably in 145 ° ± 2.5 ° scope.

Arrangement with Fig. 1, therein, Smoke Detection zone 11 is positioned under the Smoke Detection part that comprises bearing 5, photocell 6 and photodetector 7, be installed at smoke-detectors on the position of ceiling etc., a printed circuit board (PCB) that is used for detector circuit 1 li of detecting device housing can partly constitute one with Smoke Detection, and smog can be smoothly, promptly 2 enter into the Smoke Detection zone by entering the mouth.

Though as mentioned above, in this embodiment, photocell 6 and photodetector 7 are placed to such an extent that make their optical axis intersect sensing down,, they also can point to as horizontal direction with other direction.

Claims

1, scattered-light type smoke detector, it includes a black chamber, some is arranged with smog introducing inlet wherein on the periphery of this chamber;

A light radiating portion that launches light into this black chamber;

A light receiving part, be used to receive by said optical transmitting set emission and by the light of smog scattering;

Said smooth radiating portion and said light receiving part be placed make their optical axis can be substantially with 145 ° angle of intersection.

2, scattered-light type smoke detector by claim 1 regulation, therein, said smooth radiating portion and said light receiving part are black indoor at this.

3, scattered-light type smoke detector by claim 2 regulation, wherein said smooth radiating portion and said light receiving part are installed on the support in the said black chamber.

4, scattered-light type smoke detector by claim 2 regulation, wherein the angle of intersection of optical axis is in 145 ° ± 2.5 ° scope.

5, scattered-light type smoke detector by claim 1 regulation, wherein said smooth radiating portion and said light receiving part are on the top of this black chamber and settle to such an extent that to make its optical axis be downward-sloping sensing.