JP3113937B2 - Method of setting reference concentration of smoke detector and method of detecting contamination of smoke detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical smoke detector, and more particularly, to measuring smoke density using light scattering by smoke particles and comparing the measured smoke density with a reference density. And improvement of a smoke detector for detecting the occurrence of a fire.

[0002]

2. Description of the Related Art An optical smoke detector detects the occurrence of smoke by utilizing the scattering of light by smoke particles and notifies the occurrence of a fire. Such a smoke detector is provided with a light projecting element and a light receiving element in an optical chamber, and this optical chamber is formed by a labyrinth structure that blocks external light and allows only smoke to enter. Further, the light emitting element and the light receiving element are arranged such that the light receiving element does not directly receive the light beam emitted from the light emitting element.

[0003] Therefore, when smoke flows into the optical chamber, the light emitted from the light emitting element is scattered by the smoke particles, and the scattered light is received by the light receiving element.
The smoke density can be measured based on the detection result of the light receiving element. The smoke density is monitored, and if it reaches a predetermined level (fire occurrence level), it can be determined that a fire has occurred.

However, in such a smoke detector, scattered light increases due to an increase in dirt such as dust accumulated in the optical chamber. For this reason, it is determined that the increase in the measured value due to the contamination of the optical chamber is also due to the detection of smoke, and a smoke density higher than the actual smoke density is measured. That is,
Due to the contamination of the optical chamber, it is impossible to accurately measure the smoke density, and the sensitivity of the smoke detector is sharpened, so that there is a high possibility that a fire is erroneously notified.

In order to solve such a problem, a conventional smoke detector employs a method of detecting dirt in an optical chamber, correcting the sensitivity of the smoke detector, and accurately measuring the smoke density. ing. That is, a reference density for compensating for contamination of the optical room is set, and when a value obtained by subtracting this reference density from the measured smoke density reaches a certain level, it is determined that a fire has occurred. The operation of such a conventional smoke detector will be described with reference to FIG. FIG. 4 is a diagram showing data relating to the smoke density held in the smoke detector. Dx (1) in the figure is the average value of the smoke density measured from the present to the time T,
Dx (2) is the average value of measured concentrations from time T to time T × 2, and similarly, Dx (n) is
It is the average value of measured concentrations from time T × (n−1) to time T × n. D0 is a reference density.

First, an average value of the smoke density D measured during a period from immediately after the power is turned on until a time T elapses is obtained.
x (1). At this point, from Dx (2) to D
Since the density average value to be stored in x (n) has not been measured, it is assumed that the state of the measured density average value Dx (1) has continued from before power-on, and Dx (2) to Dx (2).
(N) also stores the same value as Dx (1). And
Assuming that there is no smoke when the power is turned on, this Dx
It is conceivable that (1) is a measured value in a state where there is no smoke, that is, a smoke density due to contamination of the optical room. For this reason, the average value Dx (1) of the measured densities can be used as the reference density D0.

Next, after a certain time T has elapsed,
The average value of the smoke density measured during the period from the time to the time T before is stored in Dx (1), the value held in Dx (1) is stored in Dx (2), and Dx (2) is stored. ) Is stored in Dx (3), the storage location is shifted in the same manner, and the value stored in Dx (n) is discarded. Since the average value of the smoke density measured in a state where smoke is generated is larger than the value measured in a smokeless state, the updated minimum value of Dx (1) to Dx (n) is changed to a state without smoke. And the reference density D0. Thereafter, every time the time T elapses, Dx (1) to Dx (n) are similarly updated, and the minimum value is set to D0.

[0008] In this way, the density measured by the contamination of the optical room is set as a reference density, and when a value obtained by subtracting the reference density from the measured smoke density reaches a certain level (fire judgment level), a fire has occurred. Thus, even if dust accumulates in the optical chamber, it is possible to accurately measure the smoke density and prevent occurrence of false alarms.

[0009]

However, in the above-described method for setting the reference concentration of the smoke detector, it is assumed that the smoke detector is in a smokeless state when the power is turned on. When the smoke detector is turned on in the presence state, the average value Dx (1) of the smoke density measured by detecting this smoke is regarded as the smoke density in the smokeless state, and is set to the reference density D0. There was a problem of setting.

This situation is shown in FIGS. 5A and 5B.
These figures are diagrams showing a change in measured smoke density when smoke is generated, (a) showing a state in a smokeless state when the power is turned on, and (b) showing a state of the power supply. The situation when smoke is present at the time of injection is shown. In addition,
In both cases, the dirt in the optical chamber of the smoke detector is the same.

In the case of (a), the reference density D0 is the measured density average value Dx (1) at the time T immediately after the power is turned on, and the difference between the measured smoke density D and the reference density D0 is a fire judgment. When the level reaches the ｊDjudge, a fire is notified. That is, when the reference density D0 compensates for the measured density due to dirt, and the true smoke density reaches a value corresponding to the fire determination level △ Djudge, a fire alarm is issued.

However, in the case of (b), since the smoke is present in the optical chamber when the power is turned on, the measured density average value Dx (1) immediately after the power is turned on is a density △ D0 smaller than the measured density due to dirt. This becomes a high value, and this smoke density is directly used as the reference density D0. For this reason, in order for the difference between the measured smoke density D and the reference density D0 to reach the fire determination level △ Djudge, the measured density D is reduced to the illustrated level Djudge2.
It is necessary to make the above, and even if it reaches the level Djudge 1 at which the fire alarm is performed in (a), no alarm is generated. Therefore, as shown in (b), when the measured density D does not reach the level Djudge2, a fire alarm is unreported.

Furthermore, if the optical chamber of the smoke detector becomes significantly contaminated, the influence of the contaminant on the measured density D becomes too large, and the smoke density must be accurately measured by the above method. May be difficult, and in such a case, it is necessary to clean the optical chamber. For this reason,
Some conventional smoke detectors output a failure signal when the reference density D0 exceeds a certain value (compensation limit level) Dlimit to notify that it is time to clean the optical chamber.

However, according to such a method, it is impossible to know the state of contamination of the optical chamber of the smoke detector until a failure signal is output. For this reason, when a plurality of smoke detectors are installed in the same building,
If one smoke detector outputs a failure signal, the smoke detector is cleaned, and if the other smoke detector outputs a failure signal, the other smoke detector is cleaned, the cleaning work should be performed frequently. Need to be done. On the other hand, if one of the smoke detectors outputs a failure signal, if all the smoke detectors are to be cleaned, the number of cleaning operations will be reduced. Cleaning is inefficient, resulting in poor cleaning efficiency.

FIG. 6 shows this state. FIG. 6 is a diagram illustrating an example of a state of detection of dirt for a plurality of smoke detectors. In this figure, the horizontal axis indicates a plurality of smoke sensors S1 to Sn, and the vertical axis indicates smoke density, and indicates the reference density D0 of each of the smoke sensors S1 to Sn. Since the reference density of the smoke detector S5 has reached the compensation limit level Dlimit,
A failure signal is output from the smoke detector S5, and the smoke detector S5
Cleaning is performed. However, the reference voltages D0 of the smoke detectors S3 and S4 do not reach the compensation limit level Dlimit, but are approaching this level. For this reason, the smoke detector S
Within a short period of time after the cleaning of No. 5, the smoke detector S3 or S4 outputs a failure signal, and it becomes necessary to perform the cleaning operation again.

Further, since it is troublesome to perform frequent cleaning work, it is conceivable to clean all of the smoke detectors S1 to Sn at one time. Will also be cleaned every time. The present invention has been made in view of the above circumstances, and compensates for errors in measured density due to dirt, thereby preventing the occurrence of false reports, and even when smoke is present in the optical chamber at power-on. Another object of the present invention is to provide a smoke detector for preventing a fire alarm from being missed.

It is another object of the present invention to provide a smoke detector which improves the cleaning work efficiency by detecting not only the presence or absence of contamination in the optical chamber of the smoke detector but also the degree of the contamination.

[0018]

According to the first aspect of the present invention, there is provided a method for setting a reference density of a smoke detector according to the present invention, wherein light scattered by smoke particles is detected from light emitted from a light emitting element. A method for setting a reference density used in a smoke detector for detecting the occurrence of fire by comparing the measured smoke density with a reference density by detecting the smoke density by detecting with the element. Then, the density measured at the time of turning on the power is corrected by the density at the time of no smoke which is measured and held in advance, and the density obtained is set.

According to a second aspect of the present invention, there is provided a method for setting a reference density of a smoke detector, comprising the steps of: If the change in smoke density does not exceed the predetermined range, the density measured at power-on is set as the reference density, while if the change in smoke density exceeds the predetermined range, The measured and held smokeless concentration is set as the reference concentration.

According to a third aspect of the present invention, there is provided a method of setting a reference density of a smoke detector according to the present invention, wherein the reference density is a density measured at power-on. And the density determined by calculation of the smokeless density measured and held in advance. According to a fourth aspect of the present invention, there is provided a method of detecting dirt on a smoke detector, comprising: comparing a reference density set by the setting method according to any one of claims 1 to 3 with a predetermined dirt level. A method wherein the stain level is predetermined as a plurality of different density levels, and the reference density is compared with each of the plurality of stain levels to determine which stain level the reference density has reached. To detect the degree of contamination of the smoke detector.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a method for setting a reference density of a smoke detector according to the present invention will be described below. FIGS. 1A and 1B show an example of a fire alarm according to the method for setting the reference concentration of the smoke detector.
FIG. 7 is a diagram shown in comparison with a case according to a conventional method.

FIG. 5A shows the case of the conventional method of setting the reference density, which is the same as FIG. 5B. That is, since smoke is present in the optical room when the power is turned on, the smoke density D is set to the level Djud because the average value Dx (1) of the smoke density obtained by measuring the smoke is set to the reference density D0.
Unless ge2 (a fire determination level 判断 Djudge higher than the measured density average value Dx (1)), a fire alarm cannot be issued, and a false report has occurred.

(B) shows a case of the method for setting the reference density according to the present invention. The smoke detector measures the smokeless density initial value Da in the smokeless state in advance and sets the EEPROM.
And the like. For example, the measured concentration Da at the time of shipment from the factory is written in the storage unit. Then, when the power is turned on, the average value Dx (1) of the smoke density D measured within the period of time T from the power on is obtained, and
The change of the measured density D is monitored, and based on the monitoring result, the measured density average value Dx (1) or the smokeless density initial value Da
Is selected and set as the reference density D0.

That is, the smoke density D measured for a certain period of time after the power is turned on, for example, one minute, is monitored. If there is no change in the measured density D, it is determined that there is no smoke.
The average value Dx (1) of the measured densities is defined as the reference density D0. On the other hand, if the measured density D greatly changes for one minute after the power is turned on, it is determined that smoke has been detected, and the smokeless density initial value Da is set as the reference density D0.

Here, since the contamination of the optical chamber is caused by accumulation of dust and the like, in general, the change of the scattered light incident on the light receiving element due to the contamination of the optical chamber is gentle, If it is not monitored during a period of about one day or more, it cannot be detected. However, the change in the scattered light due to smoke is extremely short in comparison with this, and changes greatly even within a short time of about one minute.

In the case of (b) in the figure, since the measured density D greatly changes within one minute after the power is turned on, the reference density D0 is set to the smokeless density initial value Da. Therefore, when the measured density D reaches the level Djudge1 (a level higher than the smokeless density initial value Da by the fire determination level △ Djudge), a fire alarm is issued. In this way, by monitoring the change in the smoke density D measured within a certain time immediately after the power is turned on, it is determined whether or not smoke exists,
As a result, in the case of a smokeless state, the measured density average value Dx (1) is set to the reference density D0 as in the conventional method, while in the state of smoke, the smokeless density initial value held in the storage means is stored. By setting Da to the reference density D0, it is possible to prevent a fire alarm from being missed when smoke is present when the power is turned on.

In FIG. 1B, a change in the measured density D is monitored by a change amount ΔD for one minute, and the change amount ΔD is compared with a predetermined value to turn on the power. We judge whether there is smoke at the time. Next, a method of setting the reference density of the smoke detector according to the present invention will be described below. FIGS. 2A and 2B are views showing an example of a fire alarm according to the method of setting the reference concentration of the smoke detector in comparison with the case of the conventional method. FIG. 5A shows a case according to a conventional method of setting a reference density, which is the same as FIG. 5B.

(B) shows the case of the method for setting the reference density according to the present invention. The smoke detector measures the smokeless density initial value Da in the smokeless state in advance in the same manner as in the above-described embodiment, and uses the EEPROM. And the like.
When the power is turned on, an average value Dx (1) of the smoke densities D measured within a period of time T from the power on is calculated, and the measured density average value Dx (1) and the smokeless density initial value Da are calculated. , The reference density D0 is obtained. This calculation can be, for example, a calculation for calculating an average value of the measured density average value Dx (1) and the smokeless density initial value Da.

The reference density D0 obtained in this way is:
The error in the measured density due to the contamination of the optical chamber can be compensated to some extent, and even if smoke is present at the time of turning on the power, the possibility of a false alarm can be reduced as compared with the conventional method. That is, the measured density average value Dx (1) includes the smoke density measured by the contamination of the optical room, and furthermore, if the smoke is present when the power is turned on, the smoke density due to the measurement of the smoke is measured. Therefore, if smoke is present when the power is turned on, a fire alarm is issued by performing an average calculation or the like of the measured density average value Dx (1) and the smokeless density initial value Da. The level Djudge3 of the measured density D required for this is the level Djudgeg in the above embodiment.
Although the value is higher than e2, it can be lower than the level Djudge1 of the conventional example shown in FIG. Therefore, the possibility of unreporting can be reduced as compared with the conventional method.

Further, a method for detecting contamination of a smoke detector according to the present invention will be described below. FIG.
FIG. 4 is a diagram showing an example of a state of detection of dirt on a plurality of smoke detectors. This figure shows a plurality of smoke detectors S on the horizontal axis.
1 to Sn, and the vertical axis represents smoke density, and each smoke detector S
It shows the reference density D0 of 1 to Sn. This dirt detection method detects dirt in the optical chamber of the smoke detector by comparing the reference density D0 with a predetermined level. As a level to be compared, the compensation limit level Dlimi is used.
t and dirt levels L3-L1 are used.

The reference density D0 is the smoke density obtained by the above-described method, and this reference density is used as a value indicating the contamination of the optical room. The compensation limit level Dlimit is
Similar to the conventional detection method, this is a contamination level for outputting a failure signal, and the reference density D0 is a compensation limit level Dlimi.
When t is reached, the smoke detector outputs a fault signal. The dirt levels L3 to L1 are lower than the compensation limit level Dlimit, and are given as different levels.

Specifically, in FIG. 3, the compensation limit level Dlimit is 10 (% / m), the stain level L3 is 9 (% / m), the stain level L2 is 6 (% / m), and the stain level L1. Is 3 (% / m). According to the method for detecting contamination of a smoke detector according to the present invention, a failure signal is output when the reference density D0 is equal to or higher than a compensation limit level Dlimit.
Even if the reference density D0 is lower than the compensation limit level Dlimit, the cleaning operation of the optical chamber is made more efficient by detecting the state of the dirt in the optical chamber based on the dirt levels L3 to L1.

That is, the reference density D0 and the dirt levels L3 to L
1 is detected, the degree of contamination is detected, and the reference density D0 becomes equal to the compensation limit level Dlimi.
If no failure signal is output below t, it is possible to know the margin of the reference density D0 of the smoke detector with respect to the compensation limit level Dlimit. Therefore, when a plurality of smoke detectors S1 to Sn are installed in the same building, if the reference density D0 of one of the smoke detectors S5 exceeds the compensation limit level Dlimit and outputs a failure signal, Cleaning work of the smoke detector is performed. At this time, the target of the cleaning work is not only the smoke detector S5 that has output the failure signal, but also the reference density D0 exceeds the contamination level L3 and the compensation limit level D
Smoke detectors S3 and S4 that cannot afford the limit are also included.

The smoke detector exceeding the contamination level L3 is
In a short time, it reaches the compensation limit level Dlimit,
Since it is considered that a failure signal is output, it is efficient to perform the cleaning at the same time as the smoke detector S5. These smoke detectors can be excluded from cleaning because it can take a considerable amount of time to reach Dlimit.

In this way, by comparing the reference density with a plurality of different contamination levels and detecting the degree of contamination of the smoke detector, the work of cleaning the optical chamber can be made more efficient.

[0036]

According to the method for setting the reference density of the smoke detector according to the present invention, the reference density in the optical smoke detection is measured and stored in advance at the time when the power is turned on. It is obtained by correcting according to the density at the time. That is, the measured density at power-on, which is affected by the presence of smoke in the optical room and the presence of smoke at power-on, is corrected by the smoke-free density initial value from which these effects have been eliminated, and used as the reference density. As a criterion, the presence or absence of a fire is determined based on the measured concentration thereafter.

For this reason, the sensitivity is corrected by detecting the dirt in the optical chamber, so that the smoke density can be measured accurately and the fire alarm immediately after the power is turned on can be prevented from being lost. According to a second aspect of the present invention, there is provided a method for setting a reference density of a smoke detector, wherein a change in a measured density during a certain period after the power is turned on is monitored. If this change is large, the smokeless density measured and held in advance is used as the reference density.

That is, the presence or absence of smoke when the power is turned on is detected based on the change in the measured density, and only when it is determined that smoke is present, the initial value of the smokeless density is used as the reference density. Because we used the measured concentration at the time,
Prevents a fire alarm from being lost immediately after the power is turned on. According to the method for setting the reference density of the smoke detector according to the present invention, the reference density is obtained by calculating the density measured when the power is turned on and the previously measured and held density in the smokeless state. .

For this reason, the obtained reference density can compensate the error of the measured density due to contamination to some extent, but can reduce the possibility of unreporting immediately after turning on the power as compared with the conventional method. . According to a fourth aspect of the present invention, there is provided a method for setting a reference density of a smoke detector, wherein the reference density is compared with a plurality of predetermined dirt levels, and which of the dirt levels the reference density has reached. To detect the degree of contamination of the smoke detector.

Therefore, when a plurality of smoke detectors are installed, when one of the smoke detectors needs to be cleaned, even if the contamination level that requires cleaning is not reached,
By performing the cleaning operation on the smoke detectors close to the level at the same time, the failure signal is not frequently output from each smoke detector, and the number of cleaning operations can be reduced. In addition, cleaning work can be omitted for smoke detectors where the optical room is almost clean,
The efficiency of the cleaning operation can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a fire alarm according to a method for setting a reference concentration of a smoke detector according to the present invention described in claims 1 and 2, in comparison with a case of a conventional method.

FIG. 2 is a diagram showing an example of a fire alarm according to a method for setting a reference concentration of a smoke detector according to the present invention, as compared with a conventional method.

FIG. 3 is a diagram illustrating an example of a state of detection of dirt on a plurality of smoke detectors.

FIG. 4 is a diagram showing data relating to the smoke density held in the smoke detector.

FIG. 5 is a diagram showing a state of a fire alarm in comparison with a case where there is smoke when the power is turned on and a case where there is no smoke.

FIG. 6 is a diagram showing a state of detecting dirt for a plurality of smoke detectors.

[Explanation of symbols]

 D: Smoke density to be measured Dx (1): Density measured at power-on Da: Smoke-free density previously stored D0: Reference density L3 to L1: Dirt level

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-217595 (JP, A) JP-A-62-254296 (JP, A) JP-A-7-6274 (JP, A) JP-A 8- 255291 (JP, A) Fully open sho 59-118089 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G08B 17/00-17/12

Claims (4)

(57) [Claims] 1. A method according to claim 1, wherein, among the light beams emitted from the light projecting element, light scattered by the smoke particles is detected by a light detecting element to measure smoke density, and the measured smoke density is compared with a reference density.
In the smoke detector for detecting the occurrence of a fire, the reference concentration is a concentration obtained by correcting the concentration measured at the time of turning on the power by the previously measured and held concentration at the time of no smoke. How to set the reference concentration of the sensor. 2. The method of setting a reference concentration according to claim 1, wherein the smoke concentration measured during a certain period after the power is turned on is monitored, and if the change in the smoke concentration does not exceed a predetermined range, While the density measured at the time of turning on the power is used as the reference density, if the change in the smoke density exceeds a predetermined range, the smoke density, which is measured and held beforehand and used as smokeless, is used as the reference density. How to set the reference concentration of the sensor. 3. The method according to claim 1, wherein the reference density is obtained by calculating a density measured at power-on and a smokeless density measured and held in advance. A method for setting a reference concentration of a smoke detector, characterized in that: 4. A dirt detection method for comparing a reference density set by the setting method according to claim 1 with a predetermined dirt level, wherein the dirt levels are different from each other. The reference density is predetermined as a density level, and the reference density is compared with each of the plurality of dirt levels to detect which dirt level the reference density has reached, and the degree of dirt on the smoke detector is determined. A method for detecting dirt on a smoke detector, comprising detecting.