JP2620311B2 - Dirt correction method and device for fire alarm device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dirt correction method for a fire alarm device and its device.

[Prior Art] In a fire alarm device, in order to accurately judge the occurrence of a fire and / or a change state of a fire, the detection output of the fire phenomenon detection unit must always know the correct detection amount of the fire phenomenon. It is necessary to calibrate the detection output.

As a conventional method for calibrating the detection output of the fire phenomenon detection unit, for example, Japanese Patent Application Laid-Open No. 61-247918 and Japanese Patent Application Laid-Open No. 61-247919
There are two types of light-emitting elements (light-emitting diodes) including a light-emitting element for smoke detection and a light-emitting element for dirt correction or test. That is, LED) is incorporated, and the light emitting element for smoke detection is arranged at an angle so that light does not directly enter the light receiving element (light receiving diode), and in a steady state, only this light emitting element emits light at a fixed cycle of every few seconds, When the smoke enters the smoke detection area, the light scattered by the smoke particles increases the amount of light received by the light receiving element to detect the smoke.

On the other hand, the dirt correction light emitting element is arranged at an angle such that light is directly incident on the light receiving element. Then, as shown in FIG. 5, the light emission amount is a constant smoke density, for example, 10%.
/ m The amount of light received by the light-emitting equal to the received light amount V _T of the light receiving elements is obtained the smoke detecting light-emitting element when there is, and the light receiving element is adjusted during production in the factory to receive, at the time of contamination correction the only dirt correcting light-emitting element emits light, and detects the dirt by changing than the amount V _T where the light receiving amount had been set by the light receiving element.

Then, in a state where there is no smoke, K = 10% from a detection amount V ₀ obtained by causing only the light emitting element for smoke detection to emit light and a detection amount V _T obtained by causing only the light emitting element for contamination correction to emit light. / m
The slope K of the output characteristic of the fire phenomenon detection unit, that is, the photoelectric smoke detection unit, is obtained from ÷ (V _T −V ₀ ). And this slope K
Until the next time V ₀ and V _T are calibrated and updated, the correction for obtaining the smoke density D from the arbitrary detection output level V ₁ by the equation D = K × (V ₁ −V ₀ ) is performed. Is going.

[Problems to be Solved by the Invention] However, in such a conventional dirt correction method, the test light emitting element, that is, the dirt correction light emitting element has a structure in which only light directly enters the light receiving element. Therefore, when the test light emitting element is turned on during dirt correction, the indirect light of the labyrinth wall reflection does not enter the light receiving element, and therefore, the change in the wall reflection is not taken into account depending on the dirt content, and accurate correction can be performed. There was a disadvantage that there was no.

In other words, when black stains stain the inner surface of the labyrinth of the photoelectric smoke sensor, the smoke detecting light emitting element, the test light emitting element, the light receiving element, and the inner wall are similarly stained. The reflection does not change from the initial time or decreases even if it does. In addition, the amount of reduction in light from the test light emitting element is substantially the same as the amount of reduction in light from the smoke detection light emitting element. Since the amount of change is the same as that of the element, the correction for the black stain is effective.

However, in white stains, the indirect light due to the labyrinth wall reflection increases, and as described above, the test light emitting element is arranged so that only the direct light is incident on the light receiving element. Can not, and therefore
No effective correction can be made.

[Means for Solving the Problems] The present invention has been made in view of such a conventional problem, and the sensor output level SLV from the smoke detection unit is scattered light due to smoke existing in the environment. Paying attention to the sum of the component D and the reflected light component I on the inner wall surface such as a labyrinth (dark box), and the scattered light component D due to smoke is 0% / m. And the reflected light component I can be measured from the sensor output level at the time of lighting of the light emitting element for smoke detection at 0% / m. The purpose is to correct the sensor output level for true smoke density.

Specifically, according to the present invention, a sensor output is generated by receiving a scattered light emitted from the smoke detection light emitting element and a smoke detection light emitting element that is energized to detect the smoke density. And a test light emitting element for correcting a change in the relationship between the sensor output level and the actual smoke density caused by the activation of the smoke detecting light emitting element. In the method for correcting the contamination of a fire alarm device, which determines a fire abnormality based on the above, the sensor output level SLV ₁ when the light emitting element for smoke detection is activated at a predetermined smoke density A is held as an initial setting stage. a first step, a second step of holding the sensor output level I ₁ when was energized smoke detecting light-emitting element in the absence of smoke, the test light emitting element in the absence of smoke biasing to holding the sensor output level T ₁ of the time obtained by Includes a third step, the, as the stage of dirt correction in a fire alarm system, and a fourth step of holding the sensor output level I ₂ when is biased smoke detecting light-emitting element in the absence of smoke includes a fifth step of holding the sensor output level T ₂ of the time that has energized the test light emitting element in the absence of smoke, a, as a normal step for monitoring, the fire discrimination reference SLV _F, SLV _{F = T 2 / T 1 (} SLV 1 -I 1) + dirt correction method of the fire alarm device, characterized in that it comprises a sixth step of obtaining the I ₂ is provided.

Instead of the sixth step, as a normal monitoring step, a predetermined smoke density A, sensor output levels SLV ₁ , I ₁ ,
Using T ₁ , I ₂ and T ₂ , the smoke density X corresponding to the monitored sensor output level SLV _X output from the smoke detector is calculated as follows: X = ｛(SLV _X −I ₂ ) / (SLV ₁ − I ₁ )｝ × (T ₁ / T ₂ ) × A.

According to another aspect of the present invention, a light emitting element for smoke detection activated to detect smoke density, and a sensor output is generated by receiving scattered light emitted from the light emitting element for smoke detection. And a test light emitting element for correcting a change in the relationship between the sensor output level and the actual smoke density caused by the activation of the smoke detecting light emitting element. storing the dirt compensation device fire alarm apparatus adapted to determine the fire abnormality, as a means for the initial setting, the sensor output level SLV ₁ when was energized smoke detecting light-emitting element at a predetermined smoke density a by first means, second means for storing the sensor output level I ₁ when was energized smoke detecting light-emitting element in the absence of smoke, the test light emitting element in the absence of smoke biasing to storing sensor output level T ₁ of the time obtained by A third means that, the, as a means of dirt correction in a fire alarm system, a fourth storing the sensor output level I ₂ when the smoke detecting light-emitting element is energized in the absence of smoke means includes a fifth means for storing the sensor output level T ₂ of the when the test light emitting element in the absence of smoke is energized, and as a general means for monitoring, fire discrimination reference SLV A dirt correction device for a fire alarm device is provided, comprising a sixth means for determining _F by SLV _F = T ₂ / T ₁ (SLV ₁ −I ₁ ) + I ₂ .

Instead of the above-mentioned sixth means, as a means for normal monitoring, a predetermined smoke density A, a sensor output level SLV ₁ , I ₁ ,
Using T ₁ , I ₂ and T ₂ , the smoke density X corresponding to the monitored sensor output level SLV _X output from the smoke detector is calculated as follows: X = ｛(SLV _X −I ₂ ) / (SLV ₁ − I ₁ )｝ (T ₁ / T ₂ ) × A There is provided a dirt correction device for a fire alarm device, characterized by having means for obtaining the following formula.

[Action] By the above method, the sensor output level or smoke in consideration of the stain on the inner wall surface is calculated by using SLV ₁ , I ₁ , T ₁ determined at the initial stage and I ₂ , T ₂ at the time of test or correction. The density can be corrected. According to the above method,
It is not necessary to perform the adjustment so that the test light emitting element or the dirt correction light emitting element outputs the predetermined sensor output level at the initial stage.

Example An example of the present invention will be described below.

FIG. 2 is a cross-sectional view of an optical part of a photoelectric smoke detector FS described later with reference to FIG. 1, and a labyrinth structure for allowing smoke to flow in and preventing outside light from entering is omitted. I have. Light emitting element LED for smoke detection emitted during fire monitoring
₁ is arranged such that light from the light emitting element is not directly directed to the solar cell by being shielded by the translucent DOUS. When smoke is generated, the light from the light emitting element for smoke detection LED ₁ is scattered by the smoke and is incident on the solar cell SB to output a light receiving signal, and the generation of smoke is known from the light receiving signal from the solar cell SB. Can be. In addition, the test light emitting element LE
D _2, the reference light from the light emitting element LED ₂ are arranged so as to be directly incident to the light receiving element SB. In this case, the reflected light from the wall surface of the reference light is prevented from entering the light receiving element SB.

The operation of the present invention will be described. Since the amount of light attenuation in smoke with a specified smoke concentration of A% / m (for example, 10% / m) is reduced only about 0.5% at a distance of 5 cm when using an infrared light emitting diode, the initial contamination When there is no smoke, the light output of the light receiving element SB when only the smoke detecting light emitting element LED ₁ emits light when the smoke of the above concentration is present, that is, the sensor output level SLV
_1, corresponds to the scattered light component due to the smoke and D _1, the sensor output level obtained by lighting only the smoke detection light emitting element when there is no reflected light component I ₁ (smoke in the inner wall surface of the labyrinth like )
Then, it is expressed by the following equation.

Initial time SLV ₁ = D ₁ + I ₁ (1) After that, the sensor output level SLV ₂ at the light receiving element SB at the same density when the contamination is generated is represented by D _{2 as the} scattered light component due to smoke, and When the reflected light component of the inner wall surface of the labyrinth like and I _2, is expressed by the following equation.

After contamination SLV ₁ = D ₂ + I ₂ (2) On the other hand, the smoke scattered light components D ₁ and D ₂ at the sensor output level output from the light receiving element SB are smoke emitting light emitting elements, respectively.
The intensity of light output from the LED ₁ to the smoke detecting region and S ₁ and S _2, a predetermined smoke density and A% / m, the light transmission quantity of the incident light i.e. light receiving element SB is input to the light receiving element SB Assuming that (coefficients) are R ₁ and R ₂ and that a conversion coefficient determined by the light receiving element SB and the optical system is K, D ₁ = K (S ₁ × A × R ₁ ) (3) D ₂ = K ( S ₂ × A × R ₂ ) (4) Thus, the scattered light components D ₁ and D ₂ of the smoke are
It is proportional to S ₁ and S ₂ , and R ₁ and R ₂ respectively. Equation (3) above
And (4) the ratio D ₂ / D ₁ for D ₁ of the D ₂ from, Here, S ₁ R ₁ is proportional to the sensor output level T ₁ at the light receiving element SB when only the test light emitting element LED ₂ is lit when there is no smoke in the initial unstained state (T ₁ = K '
× S ₁ R ₁ ), and S ₂ R ₂ is the sensor output level when only test light emitting element LED ₂ is lit when there is no smoke after contamination
Proportional to _{T 2 (T 2 = K '} × S 2 R 2). This is because the test light emitting element LED ₂ is assumed to be contaminated in the same situation as the smoke detecting light emitting element LED ₁ . Therefore, D ₂ / D ₁ is Then, SLV ₂ = D ₂ + I ₂ = D ₁ × T ₂ / T ₁ + I ₂ = T ₂ / T ₁ (SLV ₁ −I ₁ ) + I ₂ (9) is obtained. As a result, if SLV ₁ , I ₁ , and T ₁ are measured at the initial stage, the smoke density is 0% at the time of dirt correction or test.
/ m, that is, I ₂ and T ₂ are measured in the state where it is determined that there is no smoke, and the sensor output from the light emitting element LED ₁ for smoke detection corresponding to A% / m, taking into account the contamination of the inner wall surface. The level can be known from the above formula. If the sensor output level SLV ₂ at this predetermined smoke density is used as the fire determination reference SLV _F , the sensor output level DATA detected by the smoke detection light emitting element LED ₁ at any time can be used as the sensor output level for the fire determination reference. By comparing with SLV _F , it is possible to judge fire.

Further, the smoke density X is obtained from an arbitrary sensor output level SLV _X (that is, the sensor output level DATA). First, because in general the scattered light component of the smoke is proportional to the smoke density, the scattered light component D _X smoke sensor output level in SLV _X = D _X + I _X at any smoke density X% / m, a predetermined smoke The sensor output level SLV ₂ = D ₂ + I ₂ at the concentration A% / m can be expressed by the smoke scattered light component D ₂ in the following manner.

D _X = (X / A) · D ₂ (10) From equation (9), D ₂ = T ₂ / T ₁ (SLV−I ₁ ), and the reflected light component _{IX on the} inner wall surface is Since I _X = I ₂ irrespective of the smoke density, the sensor output level SL at an arbitrary smoke density X is eventually obtained.
V _X is given by: SLV _X = D _X + I ₂ = (X / A) · (T ₂ / T ₁ ) · (SLV ₁ −I ₁ ) + I ₂ (11) Therefore, the arbitrary smoke density X is .

As described above, the present invention has been operatively described. Hereinafter, a specific embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a block circuit diagram showing a fire alarm device suitable for applying the method for correcting contamination of a photoelectric smoke sensor according to the present invention. In the figure, RE is a fire receiver, and DE _{11 to} DE ₁ n. DE
n _{1 to} DEnn are respectively connected to the fire receivers RE via a pair of power / signal lines L _{1 to} Ln provided for each fire alarm area.
And a fire detector that sends a fire signal and / or an address signal to the fire receiver RE when detecting a fire phenomenon that has reached a fire determination criterion. Fire detector DE ₁₁
Only the internal circuit is shown in detail for, but the same applies to other fire detectors.

In the fire detection DE ₁₁ , FS is a photoelectric (scattered light) smoke detection unit as a fire phenomenon detection unit whose cross section is shown in FIG. 2, and MPU is a microprocessor, ROM1, ROM2 , RAM1, RAM2, and RAM3 symbolically indicate an operation storage area related to the present application in the main memory associated with the microprocessor MPU. ROM1 is a storage area for programs and the like shown in the flowchart of FIG. , ROM2 is the SL stored at the time of adjustment at the time of manufacture of the fire detector.
Storage area of the V _1, RAM 1 is working area, RAM 2, the storage area of the I ₁ and T _1, RAM 3, the storage area of _{I 2, T 2, SLV F} , TX is a fire signal and / or address signals The signal transmission unit (the signal transmission / reception unit when the fire detector is an analog sensor), IF1 and IF2 are interfaces.

In the photoelectric smoke detection unit FS, LED ₁ is a light emitting element for smoke detection, LED ₂ is a light emitting element for testing, i.e., dirt correction, SB is a light receiving element such as a solar cell, and LC is a light emitting element for smoke detection. LED ₁ at predetermined time intervals,
Alternatively the light emission drive circuit for the light emitting by the microprocessor instruction, TC is a command from the microprocessor MPU based on the test (corrected) instruction from the unshown timer or the fire receiver RE or repeaters, the test light emitting element LED ₂ A light-emitting circuit for test that emits light, RC is an amplifier circuit, and a sample-and-hold circuit that holds the output of the amplifier circuit in synchronization with the light emission of the light-emitting element LED ₁ for smoke detection or the light-emitting element LED ₂ for test. AD is an analog-to-digital converter that converts an analog signal into a digital signal.

The operation of FIG. 1 will be described with reference to the flowchart of FIG. 3, which shows an example of a program stored in the storage area ROM1 of the fire detector.

The storage area ROM2 has a smoke concentration of A% / m (for example, 10% /
when m), the sensor output level detected by the solar cell SB by emission of smoke detection light emitting element LED ₁ is stored as SLV _1.

When installed in place of use is the no smoke state, only the smoke detection light emitting element LED ₁ lights first (step 301), the sensor output level of the light receiving element SB at that time in the storage area RAM2 as I ₁ storing (step 302), then only the lit test light emitting element LED ₂ stores sensor output level (step 303) the light receiving element SB as T ₁ in the storage area RAM 2 (step 304). The sensor output level SLV ₁ stored in the storage area ROM2 is stored in the storage area RAM3 as fire discrimination standards SLV _F (step 305).

Note that the sensor output level I ₁ and T _1, the test stage of manufacture, together with the sensor output level SLV _1, may also be stored in a nonvolatile memory such as ROM.

In the monitoring state, first, the light emitting element LED ₁ for smoke detection is turned on (step 306), and the sensor output level DATA is read (step 307). Then, the read sensor output level DATA is compared with the fire discrimination criterion SLV _F, and as a result of the comparison, if it is equal to or greater than the fire discrimination criterion SLV _F (Y in step 308), the fire signal is sent from the fire signal transmission unit TX. It is output (step 309).

If the sensor output level DATA is smaller than the fire determination reference SLV _F (N in step 308), the process returns to step 306 until it is determined in step 311 that it is time to perform dirt correction, and the smoke detecting light emitting element LED ₁ Lights up, and the normal monitoring posture is continued.

If it is determined that dirt correction should be performed by a command from a timer or the like that detects that a considerable amount of time has elapsed, or by a test command from the receiver RE or the repeater (Y in step 311). First, it is determined whether or not the smoke density is 0% / m, that is, whether or not the environment is a stable state where it is determined that there is no smoke suitable for performing the correction (step 312). ). This determination method is, for example,
It may be the one described in the specification of Japanese Patent Application No. 63-42187 entitled "Fire Alarm System" filed on Feb. 26, 1988 by the present applicant. The patent application specification, when calibrating or correcting the relationship between the detected amount of the environment and the detection output of the detection unit that detects the detected amount,
Prior to performing the calibration, a plurality of detection outputs are collected, and when the difference between the maximum value and the minimum value among the plurality of detection outputs collected is equal to or smaller than a certain value, the calibration of the relationship is permitted. Doing so is described as an example.

If it is not determined that the smoke density is 0% / m (N in step 312), the process returns to step 306 and waits for the environment to stabilize. Thereafter, it is determined that the smoke density is 0% / m. (Y in step 312), then, the smoke detection light emitting element L
And light emission drives the ED ₁ (step 313), reads the sensor output levels during normal or normal from the light receiving element SB, in the storage area RAM3 it as I ₂ (Step 31
Four). Next, turn off the smoke detecting light-emitting element LED _1, a test light emitting element LED ₂ emitting driven (step 315), similarly reads the analog level from the light receiving element SB, work area it as T ₂ It is stored in the RAM 3 (step 316).

The sensor output level I ₂ and T ₂ may be the average of the plurality of sensor output level.

This way, the I ₂ and T ₂ are determined, then, SLV ₁ and the storage area ROM2 and RAM2 are stored respectively
Using I ₁ and T ₁ , a new fire criterion SLV _F is calculated by the formula SLV _F = T ₂ / T ₁ (SLV ₁ −I ₁ ) + I ₂ (step
317) Thereafter, in step 308, fire discrimination is performed based on the new fire discrimination standard.

FIG. 4 is a flowchart showing another example of a program that can be stored in the storage area ROM1, and includes a smoke detection unit FS.
Each time the sensor output level SLV _X or DATA is read from the CPU, the smoke density X corresponding to the sensor output level DATA is calculated, and the obtained smoke density X is converted to a predetermined smoke density A% /
7 is a flow chart in which fire discrimination is performed by comparing with m, for example, 10% / m. In this program, for example, from the sensor side, the analog fire detector (fire sensor) sends only the analog amount signal to the receiver, and it is determined from the fire sensor side whether the fire is abnormal or whether the fire has changed. It is suitable for use in a so-called analog-type fire sensor that is performed by a receiver or a repeater based on a transmitted analog signal of a fire phenomenon.

In FIG. 4, steps 400 to 404 correspond to steps 300 to 304 in FIG. 3, respectively, and perform the same operation.

In step 405, when it is determined that there is a correction command, after confirming the smoke density of 0% / m, that is, a state of no smoke (Y in step 406), I ₂ (step 408) is performed in the same manner as in FIG. ) And T ₂ (step 410) are read into the storage area RAM3, and the normal monitoring state is entered via N in step 405.

In the normal monitoring state, if there is a data return command from the receiver RE or the repeater (Y in step 411), the smoke detecting light emitting element LE is used to detect the smoke density at that time.
Lit the D ₁ (step 412), the sensor output level DATA
Is read (step 413), and SLV ₁ and ROM 2 in ROM 2 are read.
Using I ₁ and T ₁ in I and I ₂ and T ₂ in RAM 3, an equation is obtained from the sensor output level DATA. , Calculate the smoke density X at that time (step
414). The calculated smoke density X is written in the transmission interface and transmitted to the receiver RE or the repeater (step 415). In this case, the fire determination is performed on the receiver RE side.

In the above embodiment, the correction of the discrimination level or the sensor output level is performed on the sensor side. However, the correction may be performed on the receiver RE side. In this _{case, SLV 1, I 1, T} 1, I 2 of the sensor, and provided with a ROM and a RAM for storing the T ₂ to the receiver RE, receives the processing described in Figure 3 or Figure 4 It may be done on the machine RE side.

[Effect of the Invention] As described above, according to the present invention, for the initial setting, the sensor output level SLV ₁ when was energized smoke detecting light-emitting element at a predetermined smoke density A, the smoke detection in the absence of smoke a sensor output level I ₁ when is biased to use light-emitting element, a light-emitting element for testing in the absence of smoke and holds the sensor output level T ₁ of the time that has energized, as dirt correction, smoke a sensor output level I ₂ when the smoke detecting light-emitting element was energized in the absence, and holds the sensor output level T ₂ of the time that has energized the test light emitting element in the absence of smoke, normal Fire monitoring standard SL for monitoring
The V _F, or obtained by _{SLV F = T 2 / T 1} (SLV 1 -I 1) + I 2,
Alternatively, for normal monitoring, using a predetermined smoke density A and sensor output levels SLV ₁ , I ₁ , T ₁ , I ₂ and T ₂ , the monitored sensor output level SLV _X output from the smoke detection unit. X = {(SLV _X −I ₂ ) / (SLV ₁ −I ₁ )} ×
Since it is determined by (T ₁ / T ₂ ) × A, there is an effect that accurate level correction can be performed in consideration of a reflected light component such as a labyrinth.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a fire alarm device to which an embodiment of the present invention can be applied, FIG. 2 is a cross-sectional view showing an optical part of the photoelectric smoke detector FS of FIG. 1, and FIG. FIG. 4 is a flowchart for explaining the operation of FIG. 1, and FIG. 5 is a diagram for explaining the operation according to the prior art. In FIG, RE is the fire _{receiver, DE 11 ~DE 1 n ·· DEn} 1
~ DEnn is a fire detector, that is, a scattered light smoke detector, FS is a photoelectric smoke detector, MPU is a microprocessor, ROM1 is a storage area for programs, etc., ROM2 is a storage area for SLV ₁ , RAM1
Working area, RAM 2 is the I ₁ and T ₁ storage area, RAM 3 is I _2, T ₂
And a storage area for SLV _F , LED ₁ is a light emitting element for smoke detection, LED ₂ is a light emitting element for testing, that is, dirt correction, and SB is a light receiving element such as a solar cell.

Claims (4)

(57) [Claims] 1. A light emitting element for detecting smoke which is activated to detect smoke density, a light receiving element for receiving a scattered light emitted from the light emitting element for smoke detection and generating a sensor output, A test light-emitting element for correcting a change in the relationship between the sensor output level and the actual smoke density caused by the activation of the smoke detection light-emitting element. in dirt correction method of fire alarm apparatus adapted to determine, as a step for initial setting, first holding the sensor output level SLV ₁ when was energized the smoke detecting light-emitting element at a predetermined smoke density a a first stage, a second stage of holding the sensor output level I ₁ when in the absence of smoke is energized the smoke detection light emitting element, biasing the test light emitting element in the absence of smoke the sensor output level T ₁ of the time obtained by And a third stage of lifting, the, as the stage of dirt correction in the fire alarm device, to hold the sensor output level I ₂ when is biased to the smoke detecting light-emitting element in the absence of smoke a fourth step includes a fifth step of holding the sensor output level T ₂ of the when in the absence of smoke is energized the test light emitting element, as a normal step for monitoring, fire discrimination A method for correcting contamination of a fire alarm device, comprising a sixth step of obtaining a standard SLV _F by SLV _F = T ₂ / T ₁ (SLV ₁ −I ₁ ) + I ₂ . 2. A light emitting element for detecting smoke density which is energized for detecting smoke density, a light receiving element for receiving a scattered light emitted from the light emitting element for smoke detection and generating a sensor output, A test light-emitting element for correcting a change in the relationship between the sensor output level and the actual smoke density caused by the activation of the smoke detection light-emitting element. in dirt correction method of fire alarm apparatus adapted to determine, as a step for initial setting, first holding the sensor output level SLV ₁ when was energized the smoke detecting light-emitting element at a predetermined smoke density a a first stage, a second stage of holding the sensor output level I ₁ when in the absence of smoke is energized the smoke detection light emitting element, biasing the test light emitting element in the absence of smoke the sensor output level T ₁ of the time obtained by And a third stage of lifting, the, as the stage of dirt correction in the fire alarm device, to hold the sensor output level I ₂ when is biased to the smoke detecting light-emitting element in the absence of smoke a fourth step includes a fifth step of holding the sensor output level T ₂ of the time that has energized the light-emitting element for the testing in the absence of smoke, as a normal step for monitoring, the predetermined Smoke density A, the sensor output level SLV ₁ , I ₁ ,
Using T ₁ , I _2, and T ₂ , the smoke density X corresponding to the monitored sensor output level SLV _X output from the smoke detector is calculated as follows: X = ｛(SLV _X −I ₂ ) / (SLV ₁ -I ₁ ) A method for correcting contamination of a fire alarm device, which includes a sixth step of obtaining the following equation: Δ × (T ₁ / T ₂ ) × A. 3. A light emitting element for detecting smoke density, which is energized to detect a smoke density; a light receiving element for receiving a scattered light emitted from the light emitting element for detecting smoke and generating a sensor output; A test light-emitting element for correcting a change in the relationship between the sensor output level and the actual smoke density caused by the activation of the smoke detection light-emitting element. in dirt corrector fire alarm system which is adapted to determine, as a means for the initial setting, first stores the sensor output level SLV ₁ when it was energized the smoke detecting light-emitting element at a predetermined smoke density a and 1 means, and second means for storing the sensor output level I ₁ when in the absence of smoke is energized the smoke detection light emitting element, biasing the test light emitting element in the absence of smoke the sensor output level T ₁ of the time obtained by A third means for憶, the said as a means of dirt correction in a fire alarm system, storing the sensor output level I ₂ when the in the absence of smoke the smoke detecting light-emitting element is energized as a fourth means includes a fifth means for storing the sensor output level T ₂ of the when the test light emitting element in the absence of smoke has been energized, the conventional means for monitoring the, A dirt correction device for a fire alarm device, comprising a sixth means for obtaining a fire discrimination criterion SLV _F by SLV _F = T ₂ / T ₁ (SLV ₁ −I ₁ ) + I ₂ . 4. A smoke detecting light emitting element activated to detect smoke density, a light receiving element for receiving a scattered light emitted from the smoke detecting light emitting element and generating a sensor output, A test light-emitting element for correcting a change in the relationship between the sensor output level and the actual smoke density caused by the activation of the smoke detection light-emitting element. In the dirt correction device for a fire alarm device, the sensor output level SLV1 when the smoke detection light emitting element is activated at a predetermined smoke density A is stored as a _first setting means. means, is energized and second means for storing the sensor output level I ₁ when in the absence of smoke is energized the smoke detection light emitting element, a light-emitting element for the testing in the absence of smoke the sensor output level T ₁ of the time has come And third means, has, as a means of dirt correction in the fire alarm device, stores the sensor output level I ₂ when the in the absence of smoke the smoke detecting light-emitting element is energized to and fourth means includes a fifth means for storing the sensor output level T ₂ of the when the test light emitting element in the absence of smoke is energized, and as a conventional means for monitoring the A predetermined smoke density A, the sensor output level SLV ₁ , I ₁ ,
Using T ₁ , I _2, and T ₂ , the smoke density X corresponding to the monitored sensor output level SLV _X output from the smoke detector is calculated as follows: X = ｛(SLV _X −I ₂ ) / (SLV ₁ -I ₁ ) A dirt correction device for a fire alarm device, characterized in that the device has a sixth means for obtaining by｝ × (T ₁ / T ₂ ) × A.