JPH1123461A - Smoke sensor and smoke sensing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a smoldering fire at an early stage and to improve reliability by determining a fire and issuing an alarm in the case the integrated value of smoke density for a predetermined period of time exceeds a predetermined value while smoke density is gradually increases. SOLUTION: When smoke is produced, for example, by a smoldering fire and a photodetector 3 detects a minute current, the detected minute current is amplified at a computation processing unit 4 and converted into a digital signal. The determining part 5a of a determining part 5 determines whether the signal exceeds the first threshold value A or not, and issues an alarm in the case it exceeds the threshold A. If it does not exceeds the threshold A, a determining part 5b determines whether smoke density has been gradually increased or not. If it is increased, a determining part 5c starts the computation of the integrated value of smoke density and issues an alarm when the integrated value exceeds a threshold X.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a smoke detector and a smoke detection system.

[0002]

2. Description of the Related Art As shown in FIG. 5, a photoelectric smoke detector, which is a kind of conventional smoke detector, includes a smoke detector 1 including a light emitting element 2 such as a light emitting diode provided in a dark box, and a light receiving element. A light receiving element 3, such as a photodiode, whose axis is displaced from the optical axis of the light emitting element. Light emitted from the light emitting element 2 is irregularly reflected by smoke flowing into the dark box. When the light is received by the light receiving element 3, the light receiving element 3 outputs a small current to sense smoke.

The light receiving current sensed by the light receiving element 3 is converted into smoke density data, and an alarm is issued when the smoke density data exceeds a fire determination level (alarm level).

[0004]

However, in a fire in which the smoke density rises very slowly over a long period of time (for example, a smoldering fire), it takes a very long time to exceed the alarm level.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a fire in which the smoke density rises very slowly over a long period of time (for example, a smoldering fire). ) At an early stage to provide a reliable smoke detector and smoke detection system.

[0006]

In order to solve the above-mentioned problem, according to the first aspect of the present invention, a smoke detector which issues an alarm when the smoke density sensed by the sensing unit becomes higher than a first threshold value. In the case where the smoke density gradually increases even if the smoke density is equal to or lower than the first threshold value, and the smoke density integrated value for a predetermined time exceeds the second threshold value, Even if the concentration does not exceed the first threshold, it is determined that a fire has occurred and an alarm is issued.

According to the second aspect of the present invention, the output of the analog smoke detector is received, and a smoke alarm is issued at the receiver when the received smoke density exceeds the first threshold value. In the system, when the smoke density gradually increases and the integrated value of the smoke density for a predetermined time exceeds the second threshold, the current smoke density exceeds the first threshold. If not, judge it as a fire and alert.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. 1 is a diagram showing the configuration of a photoelectric smoke detector, FIG. 2 is a diagram showing the relationship between smoke density and time when making a fire decision, and FIG. 3 is a diagram showing the relationship between smoke density and time when making a non-fire decision. .

As shown in FIG. 1, a smoke detector 1 of a photoelectric smoke detector includes a light emitting element 2 such as a light emitting diode provided in a dark box of an optical room, and a light receiving axis corresponding to an optical axis of the light emitting element 2. A light receiving element 3 such as a photodiode, which is provided shifted, is provided.
Detects smoke due to fire by receiving light.

The arithmetic processing section 4 sends the minute current obtained by the light receiving element 3 to the determination section 5 as smoke density data obtained by amplifying and digitizing the minute current. The determination unit 5 includes a first determination unit 5a, and has a threshold A of, for example, a smoke density of 10 [% / m] as a first threshold of a normal alert level. If the smoke density detection value exceeds the threshold value A, an alarm is issued.

Further, the apparatus has a determination unit 5b for determining whether or not the smoke density is gradually increasing. The determination as to whether or not the value is gradually increasing is based on whether the difference between the detected value obtained as the detected value of the smoke density and the immediately preceding detected value is equal to or greater than a certain value, or the differential value of the detected values of the plurality of smoke densities. Is greater than or equal to a certain value, it is determined that the smoke density is gradually increasing.

Further, the judging section 5 has a judging section 5c. After judging that the smoke density is gradually increasing, the integrated value S of the smoke density until a predetermined time T is set to a second threshold. It is determined whether or not the value X is exceeded. If the value exceeds the second threshold value X, an alarm is issued. At this time, even if the smoke density detection value does not exceed the first threshold value A, if the smoke density exceeds the second threshold value X, an alarm is issued.

[Embodiment] The first threshold value A of the discriminating section 5 is set to, for example, a smoke density of 10 [% / m]. In the case of a very slow-burning smoldering fire in which the smoke density increases by about 0.5 [% / m] per minute, after the smoke density starts to increase, it takes 10% [m / m] to reach the smoke density. About 2
It may take about 0 minutes, but if the predetermined time T of the determination unit 5c is 15 minutes and the second threshold value X is 25 min *% / m, the smoke density 5 starts 10 minutes after the smoke density starts to increase.
% / M.

Next, the operation of the first embodiment will be described using the above embodiment. When smoke is generated by the smoldering fire and a small current is detected by the light receiving element 3 in FIG. 1, it is amplified by the arithmetic processing unit 4 and converted into a digital signal. The determination unit 5a of the determination unit 5 determines that the smoke density 1
It is determined whether or not it exceeds 0 [% / m], and if it exceeds (YES), an alarm is issued.

If not (NO), the judgment section 5b
In, it is determined whether the smoke density is gradually increasing. If it has not risen (NO), the process returns to the determination unit 5a again. If it is gradually increasing (YES), the judgment unit 5
At step c, the calculation of the integrated value of the smoke density is started, and when the integrated value exceeds the threshold value X (25 min *% / m), an alarm is issued as shown in FIG. The integral value is indicated by an integral value S (corresponding to the area of the oblique line) in the relationship diagram between the smoke density and the time indicating the fire judgment in FIG.
0 minutes.

As shown in FIG. 3, in the case of a non-fire report (tobacco smoke, cooking steam, etc.), the smoke density suddenly reaches a certain level, and the state is changed for a while for about 1 to 3 minutes. Maintain and eventually disappear. For such non-fire reports,
The integral value S does not reach the threshold value X and does not generate an alert.

A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing a configuration of the smoke detection system. In the second embodiment, the determination unit 5 in the first embodiment is provided in the receiver 6, and the determination unit 7, the determination unit 7a, the determination unit 7b, and the determination unit 7c are used. On the sensor 8 side, a light projecting element 2 and a light receiving element 3 are provided in the smoke detecting section 1 to detect smoke due to a fire.

The arithmetic processing unit 4 provided in the sensor 8 comprises:
The small current obtained by the light receiving element 3 is amplified and converted into a digital signal, which is sent to the determination unit 7 of the receiver 6 through a time division multiplex transmission line or the like. The fire judgment in the judging section 7 is the same as that in the first embodiment, and the explanation is omitted.

[0019]

According to the first aspect of the present invention, a fire in which the smoke density rises very slowly over a long period of time, such as a smoked fire, can be detected at an early stage.

According to the second aspect of the invention, in addition to the effect of the first aspect, since the receiver is provided with the judgment unit, it is possible to use a conventional analog type smoke detector. It works.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a smoke detector according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between smoke density and time indicating a fire judgment according to the first embodiment.

FIG. 3 is a diagram showing the relationship between smoke density and time when making a non-fire determination according to the first embodiment.

FIG. 4 is a diagram showing a configuration of a smoke detection system according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a conventional smoke detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Smoke sensing part 2 Light emitting element 3 Light receiving element 4 Arithmetic processing part 5 Judgment part 5a Judgment part 5b Judgment part 5c Judgment part 6 Receiver 7 Judgment part 7a Judgment part 7b Judgment part 7c Judgment part 8 Sensor

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[Procedure amendment]

[Submission date] January 13, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 2

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

According to the second aspect of the present invention, a smoke detection system which receives an output of an analog type smoke detector and issues an alarm when the received smoke concentration exceeds a first threshold value at a receiver side. In the case where the smoke density gradually increases and the integrated value of the smoke density for a predetermined time exceeds the second threshold, the smoke density at that time does not exceed the first threshold. Even if it is judged as a fire, a warning is issued.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

[Embodiment] The first threshold value A of the discriminating section 5 is set to, for example, a smoke density of 10 [% / m]. In the case of a very slow-burning smoldering fire in which the smoke density increases by about 0.5 [% / m] per minute, after the smoke density starts to increase, it takes 10% [m / m] to reach the smoke density. About 2
Although it may take about 0 minutes, if the predetermined time T of the determination unit 5c is 15 minutes and the second threshold value X is 25 min *% / m, the smoke density is increased about 10 minutes after the smoke density starts to increase. It is possible to make an alarm at 5% / m.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a smoke detector according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between smoke density and time indicating a fire judgment according to the first embodiment.

FIG. 3 is a diagram showing the relationship between smoke density and time when making a non-fire determination according to the first embodiment.

FIG. 4 is a diagram showing a configuration of a smoke detection system according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a conventional smoke detector.

[Description of Signs] 1 Smoke sensing unit 2 Light emitting element 3 Light receiving element 4 Arithmetic processing unit 5 Judgment unit 5a Judgment unit 5b Judgment unit 5c Judgment unit 6 Receiver 7 Judgment unit 7a Judgment unit 7b Judgment unit 7c Judgment unit 8 Sensor

[Procedure amendment 5]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

Claims (2)

[Claims] 1. A smoke detector which issues an alarm when the smoke density sensed by a sensing unit is equal to or higher than a first threshold value. In this case, if the integrated value of the smoke density for a predetermined time exceeds the second threshold value, it is determined that a fire has occurred even if the smoke density at that time does not exceed the first threshold value, and an alarm is issued. A smoke detector, characterized in that: 2. A smoke detection system which receives an output of an analog smoke detector and issues an alarm if the received smoke concentration exceeds a first threshold value at a receiver side.
Even if the smoke density gradually increases and the integrated value of the smoke density for a predetermined time exceeds the second threshold, even if the smoke density at that time does not exceed the first threshold Smoke detection system that detects and reports a fire.