JPS5831039B2 - Smoke detectors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a smoke sensor having a scattered light type smoke detection section and an ionization type smoke detection section as an integrated structure.

Traditionally, smoke detectors that detect when the smoke concentration associated with a fire has reached a predetermined value include photoelectric smoke detectors that detect the attenuation of transmitted light or the amount of scattered light due to smoke, and smoke detectors that detect the amount of light that is ionized by a radiation source. Each type of ionization smoke sensor, which detects smoke from changes in ion current caused by smoke entering a space, has been put into practical use individually, and is used depending on the purpose.

By the way, when comparing the smoke sensitivity characteristics of ionization smoke detectors and photoelectric smoke detectors, we find that, assuming the smoke concentration is constant, ionization smoke detectors detect relatively small smoke of 1μ or less. The change in ionic current for particles is noticeable, but the change in ionic current for smoke particles larger than 1 μm is small.

This is because the ionic current changes depending on the number of smoke particles per unit volume.

On the other hand, in photoelectric smoke detectors, taking the scattered light type as an example, they are significantly sensitive to relatively large particles of 1μ or more because the amount of scattered light increases, and the color of smoke particles is It has the characteristic that it is well sensitive to white particles, but it is difficult to be sensitive to black particles because it scatters less.

However, the nature of smoke when a fire occurs cannot be determined unambiguously, and it is necessary to generate a detection output when a predetermined concentration is reached regardless of the size, color, etc. of smoke particles. Smoke detectors that combine the characteristics of both detectors and photoelectric smoke detectors have been proposed;
No. 04088), both of them are related to the combination of electric circuits, and in practical use, the structure of the ionization smoke detector and the photoelectric sensor, which have completely different functions, must be combined into one structure without impairing their respective functions. Unless a solution is found to this point, installing separately manufactured ion smoke detectors and photoelectric smoke detectors in the same location will be sufficient to fully utilize the characteristics of both. It can be supplemented.

The present invention has been made in view of the above, and provides a smoke detector in which the electrode structure of the ionization type smoke detection part is used in combination with the light shielding structure of the scattered light type smoke detection part in order to have a simple integrated structure. The purpose is to

The present invention will be described in detail below based on the drawings.

FIG. 1 is a cross-sectional view of one embodiment of the present invention. First, the ionization type smoke detection section is insulated around an internal electrode 3 in which a radiation source 2 is embedded and held through a printed board 1. A ring 4 is provided, and a disk-shaped intermediate electrode 5 is inserted through the insulating ring 4.
, and a housing portion for the internal electrode 3 partitioned by an insulating ring 4 between the printed board 1 and the intermediate electrode 5 is formed as an internal ion chamber 6.

The external electrode 7 attached to the printed circuit board 1 covering the outside of the intermediate electrode 5 has a plurality of smoke inflow holes 8, and an external ion chamber 9 is formed in the space partitioned by the external electrode I and the intermediate electrode 5. is forming.

In addition, in this embodiment, since there is only one radiation source 2, an electrode hole is placed in the center of the intermediate electrode 5 in order to ionize the external ion chamber 9 by the radiation source 2 in the same way as the internal ion chamber 6.
0 is set.

Incidentally, the outside of the external electrode I is covered with a housing 12 similarly provided with a smoke inflow hole 11.

On the other hand, the scattered light type smoke detector includes a light emitter 14 equipped with a light emitting element 13 on both sides of an insulating ring 40, and a light receiver 16 equipped with a light receiving element 15.
The light receiver 16 is installed so that the inside of the external ion chamber 9 is irradiated through the intermediate electrode 7, and the light receiver 16 is installed so that the scattered light from the smoke flowing into the external ion chamber 9 enters through the through hole 18 of the intermediate electrode 5. The configuration angle θ in the smoke detection section 19 where the optical axes of the light emitter 14 and the light receiver 16 intersect is determined to be around 60°, for example.

With respect to such an arrangement of the light emitter 14 and the light receiver 16, the intermediate electrode 5 and the insulating ring 4 have the function of a light shielding part that prevents the light from the light emitter 14 from directly entering the light receiver 16. There is.

Therefore, the mounting position of the light emitter 14 and the light receiver 16 is as shown in the plan view of FIG.
It can be provided at any position within the range between 0'.

Also, an external ion chamber 9 receives light from the light emitter 14.
The inside is painted black to prevent light reflected from the inner wall from entering the light receiver 16.

In this case, since both the inner surface of the external electrode 1 and the upper surface of the intermediate electrode 5 must function as electrodes,
It is coated with a conductive black coating such as carbon coating.

In addition, the hood 14a of the light emitter 14 and the light receiver 16.

15a may not be provided if the intermediate electrode 5, insulating ring 4, etc. are configured to prevent light from entering from other than the smoke detection section 19, and of course, the light emitting element 13 and light receiving element in this case may not be provided. The storage section 15 is painted black.

Further, each hood 14a, 16a may be formed integrally with the insulating ring 4.

FIG. 3 shows another embodiment of the present invention, in which the same parts as in FIG. 2 are designated by the same reference numerals.

The internal ion chamber 6 is partitioned by an insulating ring 4 and an intermediate electrode 5 and accommodates an internal electrode 3 equipped with a radiation source 2, and the external ion chamber 9 houses an external electrode 1 provided on a printed board 1, covering the intermediate electrode 5. The internal ion chamber 6 is ionized by the radiation source 2, and the external ion chamber 9 is
The intermediate electrode 5 is equipped with an ionization type smoke detecting section that is ionized by a radiation source 2' separately provided, and the light emitter 14 and the light receiver 16 are connected to the intermediate electrode forming the internal ion chamber 6. 5 and an insulating ring 4, the mounting range is the same as that shown in FIG. 2, and the height does not exceed the intermediate electrode 5.

Of course, the inner surface of the external electrode 7 and the external ion chamber surface of the intermediate electrode 5 are coated with a conductive black coating to prevent light from the outside from being diffusely reflected within the external ion chamber and entering the light receiver 16. The light from the light emitter 14 is prevented from entering the light receiver 16 due to diffuse reflection by sources other than smoke.

FIG. 4 shows an example of the smoke detection circuit mounted on the printed board 1 in the embodiment shown in FIG. When smoke flows into the external ion chamber 9, the potential of the intermediate electrode 5 decreases according to the smoke concentration due to a decrease in the ion current.
This is detected by the amplifier 22 and input to the comparator 23, and when it exceeds the reference level determined by the capacitor C1, the comparator 23 produces an output, which activates the switching circuit 25 via the driver 24 which operates as an OR gate, and sends out a fire signal. do.

On the other hand, in order to pulse-drive the light emitting element 13 intermittently at a predetermined period, the scattered light detection circuit section first uses the clock generator 2
6. A monostable multivibrator 27 that generates a rectangular pulse with a predetermined pulse width using a clock pulse, and a driver that intermittently discharges the capacitor C2 using the pulse output of the monostable multivibrator 27 to drive the light emitting element (light emitting diode) 13 in pulses. 28 is provided, and the light emitting element 13
The pulsed light is diffusely reflected by the smoke that has flowed into the external ion chamber and enters the light receiving element 15, and the intensity of the scattered light corresponding to the smoke concentration is photoelectrically converted by the light receiving element 15 and transmitted to the amplifiers 29 and 3.
After being integrally amplified at 0, the signal is input to the comparator 31, and when it reaches a reference level determined by the capacitor C1, the comparator 31 produces an output, which operates the switching circuit 25 via the driver 24.

In order to prevent malfunctions, the driver 24 is provided with an AND gate function, and the switching circuit 25 is activated when detection outputs from both the ionization type detection section and the scattered light detection section are obtained. Alternatively, the detection sensitivity may be set in two levels by setting the reference levels of the comparators 23 and 31 separately.

As explained above, the smoke detector of the present invention has a configuration in which the electrode structure of the ionization type smoke detection section is used together as a light shielding part of the scattered light type smoke detection section, so that the ionization type smoke detection section is combined with the scattered light type detection section. Even when a smoke section is incorporated, there is no need to add a special light shielding structure in addition to the emitter and receiver, and the smoke detection section can be used in combination with both the ionization type smoke detection section and the scattered light type smoke detection section. Because of this, detection outputs can be taken out in parallel with different smoke detection effects for the inflow of smoke, and therefore, the smoke detection output can be extracted in parallel with different smoke detection effects. It is possible to realize an extremely reliable and highly sensitive smoke detector, and because it is integrated with a simple structure, it is easy to mass produce and can reduce costs. .

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing one embodiment of the present invention, Fig. 2 is a plan view showing the intermediate electrode portion of Fig. 1, and Fig. 3 is a cross-sectional view showing another embodiment of the present invention. 4 are block diagrams showing one embodiment of the smoke detection circuit used in the present invention. 1... Printed board, 2, 2'... Radiation source, 3... Internal electrode, 4... Insulating ring, 5... Intermediate Electrode, 6...Inner ion chamber, 7...Outer electrode, 8, 11...
・Smoke inflow hole, 9... External ion chamber, 10...
... Electrode hole, 12 ... Housing, 13 ...
...Light emitting element, 14... Light emitter, 15...
... Light receiving element, 16... Light receiver, 14a
, 16a...Hood, 17,18...
・Through hole, 19...Smoke detection part, 20, 20'...
...Parallel tangent, 22,29,30...-Amplifier, 23,31...Comparator, 24,28...
--- Driver, 25... Switching circuit, 26... Clock generator, 27...
- Monostable multibiflator.

Claims (1)

[Claims] 1. In a smoke sensor in which an internal ion chamber that is ionized by a radiation source is formed by an internal electrode and an intermediate electrode, and an external ion chamber that is ionized by a radiation source and into which smoke flows is formed by the intermediate electrode and external electrode, A light emitter that irradiates the inside of the external ion chamber and a light receiver that receives scattered light from the external ion chamber due to the light irradiated from the light emitter are arranged at a position that interposes the internal ion chamber as a light shielding part. Features a smoke detector.