JP3181734B2 - Fire detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-sensitivity smoke type fire detector for calibrating sensitivity characteristics by taking a plurality of sample gases into a smoke chamber.

[0002]

2. Description of the Related Art When calibrating sensitivity characteristics of a smoke detector by taking a plurality of sample gases into a smoke chamber, conventionally, oxygen gas,
Two kinds of pure gases having significantly different molecular weights, such as Freon 12 (CCl ₂ F ₂ ) gas, are alternately passed through a smoke chamber, and light generated by a light-emitting lamp is scattered by molecules of the sample gas. The sensitivity characteristic of the smoke detector is calibrated using the fact that the light receiving element captures the light.

[0003] That is, pure gas is stable in concentration, and when attention is paid to a certain pure gas, the pure gas is taken into a smoke chamber, and when the pure gas is detected as smoke, a value of a certain smoke concentration is output. And the output smoke density value is very small. In other words, since a certain pure gas and smoke density correspond, and the smoke density is very low,
By utilizing this, it is possible to calibrate the sensitivity characteristic of a highly sensitive smoke detector.

FIG. 5 is a circuit diagram showing a main part of a conventional smoke detector.

In this conventional example, light is emitted from a xenon lamp (not shown), and after the light generated by the xenon lamp is scattered, the scattered light is received by a light receiving element 81, and the peak value of the output signal of the light receiving element 81 is peaked. The data held by the hold circuit 84 and obtained by subtracting a predetermined value from the peak value by the subtraction circuit 85 is sent to the receiver via the signal output circuit 87. The variable resistor 83 for adjusting the gain adjusts the gain of the amplifier 82,
The middle offset variable resistor 86 is a resistor for adjusting the predetermined value to be subtracted from the peak value.

FIG. 6 is a diagram showing the relationship between the smoke density and the value of the current output from the signal output circuit 87 in the conventional example.

FIG. 6 shows the value of the output current of the signal output circuit 87 with respect to the concentration when pure oxygen gas and Freon 12 gas are alternately taken into the smoke chamber at 1 atmosphere and normal temperature. In FIG. 6, a characteristic C1 is a characteristic when the sensitivity of the smoke detector is not adjusted.
3 is a characteristic when the sensitivity adjustment is completed. That is,
The variable resistor 83 for gain adjustment and the offset amount adjustment so that the output current of the signal output circuit 87 when using oxygen gas becomes I1 and the output current of the signal output circuit 87 when using Freon 12 becomes I2. The characteristic C3 is determined by adjusting the output current of the signal output circuit 87 when oxygen gas is used.
And the output current of the signal output circuit 87 when the Freon 12 is used becomes I2.

To adjust the sensitivity of the smoke detector, the characteristic C1
Adjustment of the tilt and translation. In practice, the output of the smoke detector is adjusted while looking at the ammeter or the like. First, by operating the gain adjusting variable resistor 83 by taking in Freon 12 gas, the characteristic C1 is adjusted so that the output matches I2.
Is adjusted to obtain the characteristic C21. Next, by taking in oxygen gas and operating the offset amount adjusting variable resistor 86, the characteristic C21 is adjusted so that the output matches I1.
Is moved in parallel to obtain a characteristic C22. And again CFC 1
By taking in two gases and operating the variable resistor 83 for gain adjustment, the characteristic C22 is set so that the output matches I2.
Is adjusted to obtain the characteristic C23. Hereinafter, the characteristic is C3
Repeat this operation until it matches.

As described above, when changing the characteristic from C1 to C3, if the variable resistor 86 for adjusting the offset is adjusted so that one of the output data coincides with I1, the other output data becomes I2. Therefore, the characteristic C3 cannot be obtained. Next, when the variable resistor 83 for gain adjustment is adjusted to adjust this slope so that the other output data matches I2, Since the output data cannot keep the coincidence with I1, the characteristic C3 cannot be obtained accurately. Therefore, even if the adjustment operation for obtaining the characteristics twice (the operation of using the oxygen gas and the Freon 12 gas once each) is performed, the sensitivity adjustment does not end.

Of course, in the process of repeating these operations, the characteristic gradually approaches the characteristic C3. For that purpose, it is necessary to obtain the characteristic many times.
% Replacement is required, and the gas replacement operation is not easy and complicated. For this reason, in the above-mentioned conventional device, there is a problem that the sensitivity adjustment work of the smoke detector is complicated and the sensitivity adjustment work takes a long time.

[0011]

In order to solve this problem, it is necessary to set A when the smoke chamber is filled with oxygen gas.
The memory stores the output data of the / D conversion circuit as the first calibration data _x1h , and outputs the output data of the A / D conversion circuit when the smoke chamber is filled with Freon 12 gas as the second calibration data _x2h. As the first calibration data stored in the memory as
Based on _x1h , the second calibration data _x2h, and the output data of the A / D conversion circuit, it is necessary to display an appropriate smoke density value corresponding to the output data of the A / D conversion circuit on the smoke density display device. It is conceivable to calculate various output data.

However, in this case, the smoke concentration corresponding to oxygen gas and Freon 12 gas is extremely low, and the sensitivity of the smoke detector is calibrated only in a very small area of the measurement scale. For this reason, there is a problem that the accuracy of the measured smoke density may be low. That is, there is a problem that the accuracy of the smoke density is low in a region where the smoke concentration is higher than the concentration of the gas used when obtaining the calibration data.

According to the present invention, the work of adjusting the sensitivity of the smoke detector is easy, and the work of adjusting the sensitivity can be completed in a short time.
Moreover, it is another object of the present invention to provide a smoke-type fire sensing device having high smoke density accuracy in a smoke density region higher than the gas concentration used when taking calibration data.

[0014]

SUMMARY OF THE INVENTION The present invention relates to an output data of an A / D conversion circuit when a smoke chamber is filled with a first gas, the light being received at a gain higher than a gain at a set sensitivity. The data when the output signal of the element is amplified is stored as the first calibration data _x1h , and the output data of the A / D conversion circuit when the smoke chamber is filled with the second gas. The data when the output signal of the light receiving element is amplified with a gain higher than the gain in sensitivity is stored as second calibration data x _2h , and the first calibration data is stored.
The appropriate smoke density value corresponding to the current output data of the A / D conversion circuit is displayed on the smoke density display device based on _x1h , the second calibration data _x2h, and the current output data of the A / D conversion circuit. This is to calculate the output data necessary for the operation.

[0015]

According to the present invention, the output data of the A / D conversion circuit when the smoke chamber is filled with the first gas is amplified at a gain higher than the gain at the set sensitivity. The first calibration data x _1h at the time of the correction and the output data of the A / D conversion circuit when the smoke chamber is filled with the second gas. Based on the second calibration data x _2h when the output signal of the element is amplified and the output data of the A / D conversion circuit, an appropriate smoke density value corresponding to the current output data of the A / D conversion circuit is calculated. After the calculation, the first calibration data x _1h and the second calibration data x _2h are converted into a gain at the set sensitivity, so that the sensitivity adjustment work of the smoke sensing device is easy, and the sensitivity adjustment work can be performed in a short time. Can be finished and calibration data High accuracy of smoke density in the regions of high smoke concentration than the concentration of the gas used when taking.

[0016]

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the smoke detector 1 of this embodiment, the smoke room 3
The xenon lamp 10 and the light receiving element 20 are provided in the inside of the light shielding plate 34.
Are separated by And a xenon lamp 10
Emits light, and the light is scattered by the smoke in the smoke chamber 30 and reaches the light receiving element 20.

The xenon lamp 10 is supplied with a high voltage necessary for light emission from a high voltage generation circuit 12 and a trigger circuit 11
The light emission timing is controlled by a trigger signal supplied from. The trigger circuit 11 generates a trigger signal based on a control signal supplied from the control circuit 50.

The smoke chamber 30 is connected to a sampling pipe 31 for guiding the atmosphere of the fire monitoring area to the smoke chamber 30 and a pipe 32 for guiding the air in the smoke chamber 30 to the outside of the smoke detector 1. A suction fan 33 is provided.

The amplifier 40 amplifies the output signal of the light receiving element 20, the gain of which is controlled by a gain switching circuit 41, and the peak hold circuit 42 is a circuit that holds the peak of the output signal of the amplifier 40. , A / D
The conversion circuit 43 is a circuit that converts an analog signal output from the peak hold circuit 42 into a digital signal.

The control circuit 50 is composed of a microcomputer or the like, controls the smoke detector 1 as a whole,
The current smoke density in the smoke chamber 30 is determined based on the digital signal from the / D conversion circuit 43.

The ROM 60 stores the program of the flowchart shown in FIG. EEPROM 61
, For example 1 atmosphere, at room temperature, an output data of the A / D converter circuit 43 which definitive when sucking oxygen pure gas Kemurishitsu 30, the light receiving element with high gain G _h than the gain G _n in the set sensitivity the data when the output signal of the 20 was amplified stored as first calibration data x _1h, definitive when sucking the pure gas freon 12 to Kemurishitsu 30 a
An output data / D conversion circuit 43, the data of the second calibration data x _2h when the output signal of the light receiving element 20 with high gain G _h than the gain G _n in the set sensitivity is amplified
ROM. The RAM 64 is a working memory.

The D / A conversion circuit 71 includes a signal output circuit 7
2. To send a signal to the receiver 2 via the connector C,
This is a circuit that converts a digital signal output by the control circuit 50 into an analog signal. The receiver 2 includes a smoke density display device 2d (shown in FIG. 4) for displaying smoke density.

When the sensitivity of the smoke detector 1 is being adjusted, the calibration confirmation light circuit 74 indicates that the adjustment is being performed.

The switches SW1 and SW2 are lock-type switches operated in accordance with the type of gas used when calibrating the sensitivity of the smoke detector 1, and the switch SW3 is used when calibrating the sensitivity of the smoke detector 1. This is a non-lock type switch that is turned on for 5 seconds or more.

It should be noted that E for the detected value of the memory calibration reference gas is used.
EPROM61 is an output data of the definitive A / D converter when the first gas in the smoke chamber is filled, the output signal of the light receiving element with high gain G _h than the gain G _n is amplified in the setting sensitivity The first calibration data
stored as x _1h, an output data of the definitive A / D converter when the second gas in the smoke chamber is filled, the output signal of the light receiving element with high gain G _h than the gain G _n in the set sensitivity Is used as the second calibration data
It is an example of a memory stored as _x2h . Also, EEPR
The OM 61 is an electrically rewritable nonvolatile memory.

The control circuit 50 and the ROM 60 are examples of arithmetic means for performing a predetermined arithmetic operation based on the output data of the A / D conversion circuit. This arithmetic means includes first calibration data x _1h
Is converted to a gain _Gn at the set sensitivity,
The appropriate smoke density value corresponding to the current output data of the A / D conversion circuit is determined based on the data obtained by converting the calibration data _x2h of the A / D conversion into the gain _Gn at the set sensitivity and the output data of the A / D conversion circuit. This is a means for calculating output data necessary for displaying on the density display device.

More specifically, the calculation means calculates the first calibration data x _1h , the second calibration data x _2h , the current output data x of the A / D conversion circuit, and the first gas. corresponds to the output data y ₁ required for displaying a smoke density in the smoke density display device, the output data y ₂ required for displaying a smoke density corresponding to the second gas to the smoke density display device, a / output data y needed to display D proper sensitivity value corresponding to the output data of the conversion circuit to the smoke density display device, and the gain G _n in the set sensitivity, high gain G _h than the gain G _n in the set sensitivity And y = [(y ₂ −y ₁ ) / {(x _2h -x _1h )
By calculating the _{(G n / G h)}} ] · x + (y 1 · x 2h -y 2 · x 1h) / (x 2h -x 1h), is intended for calculating the output data y.

Next, the operation of the above embodiment will be described.

FIG. 2 is a flowchart showing the operation of the above embodiment. In this flowchart, S11 to S11
S23 is a preparation operation for adjusting the sensitivity of the smoke detector 1,
S1 to S4 are smoke detection operations including sensitivity adjustment.

First, the preparatory operation for sensitivity adjustment will be described.

Before the sensitivity adjustment of the smoke detector 1, for example, at 1 atmosphere and normal temperature, the sampling pipe 31
The switch SW1 is turned on, the switch SW2 is turned off, and the switch SW3 for the sensitivity adjustment command is turned on for 5 seconds or more while the smoke chamber 30 is filled with pure oxygen through the switch. In this way, when the sensitivity adjustment command switch SW3 is turned on for 5 seconds or more (S11), the confirmation light of the calibration confirmation light circuit 74 is lit for one second to inform that the sensitivity adjustment operation will be performed from now on (S11). S12). At this time, switch SW
1 is on and the switch SW2 is off (S1
3, 14), the gain switching circuit 41 is driven to switch the gain of the amplifier 40 to the maximum value (S15), and the output signal of the light receiving element 20 is amplified in a state where the smoke chamber 30 is filled with pure oxygen, and this amplification is performed. The peak value of the converted signal is held in the peak hold circuit 42, and this peak value is converted into digital data by the A / D conversion circuit 43, and the converted output data is used as the first calibration data x _1h as EEP.
The gain is stored in the ROM 61 (S16), the gain of the amplifier 40 is returned to the gain Gn of the set sensitivity (S17), and the smoke detection operation (S1 to S4) described later is executed.

Then, the pure oxygen gas is discharged from the pipe 32 and the pure chlorofluorocarbon 12 (F1
2) is filled in the smoke chamber 30, the switch SW1 is turned off,
The switch SW2 is turned on, and the switch SW3 for the sensitivity adjustment command is turned on for 5 seconds or more. In this way, when the sensitivity adjustment command switch SW3 is turned on for more than 5 seconds (S11), the confirmation light of the calibration confirmation light circuit 74 is turned on for 1 second.
Lights up to notify that a sensitivity adjustment operation is to be performed (S12). At this time, since the switch SW1 is off and the switch SW2 is on (S13, S21), the gain switching circuit 41 is driven to switch the gain of the amplifier 40 to the highest value (S22), and the pure Freon 12 is set in the smoke chamber. 30
, The output signal of the light receiving element 20 is amplified by the amplifier circuit 40, the peak value of the amplified signal is held in the peak hold circuit 42, and the peak value is stored in the A / D
The converted output data is converted into digital data by the conversion circuit 43, and the converted output data is used as the second calibration data _x2h.
The gain is stored in the EPROM 61 (S23), the gain of the amplifier 40 is returned to the gain of the set sensitivity (S17), and the smoke detection operation (S1 to S4) described later is executed. Note that the switch SW
If both SW1 and SW2 are on, data other than the calibration data among the data stored in the EEPROM 61 is cleared (S24).

Next, the smoke density detecting operation including the sensitivity adjustment, that is, the smoke detecting operation will be described.

When the preparation operation for the sensitivity adjustment is completed as described above, the first calibration data x from the EEPROM 61 is read.
_1h , the second calibration data x _2h is read (S1), and the current detection data (current output data of the A / D conversion circuit 43) x is fetched (S2). And the first calibration data
x _1h , second calibration data x _2h , current detection data x, D
A D / A conversion circuit 71 necessary for displaying an appropriate smoke density value corresponding to the current output data x on the smoke density display device 2d based on the output data y ₁ and the output data y ₂ of the / A conversion circuit 71. The output data y to the controller 50 and the ROM 60
Are calculated, that is, sensitivity is adjusted (S3).

The output data y ₁ is necessary for displaying the smoke density (about 0.005% / m) corresponding to the oxygen gas (first gas) on the smoke density display 2 d of the receiver 2. Na D
The output data to the / A conversion circuit 71 is calculated in advance and stored in the ROM 60. Output data y ₂ is the smoke density (about 0 corresponding to freon 12 gas (second gas).
035% / m) is output data to the D / A conversion circuit 71 necessary for displaying the smoke density display device 2d, and is calculated in advance and stored in the ROM 60. That is, since the concentration of the oxygen gas is equivalent to the smoke concentration of about 0.005% / m, when the oxygen gas is injected into the smoke chamber 30, as shown in FIG. In the display device 2d, only the "OK" portion is turned on, and the concentration of Freon 12 gas is equivalent to a smoke concentration of about 0.035% / m. Therefore, when Freon 12 gas is injected into the smoke chamber 30, Are “OK”, “0.01”, “0.02”, “0.0” in the smoke density display device 2d as shown in FIG.
"3" is lit.

That is, the output data y to the D / A conversion circuit 71 necessary for displaying the appropriate sensitivity value corresponding to the current output data x on the smoke density display device 2d is transmitted to the control device 5
In the case where 0 and the ROM 60 calculate, the characteristic to be obtained from the calculation is generally expressed by the equation y = a · x as shown in FIG.
+ b, and the general expression “y = a · x + b” is obtained by adding the expression “y = [(y ₂ −
y ₁ ) / {(x _2h -x _1h ) · (G _n / G _h )}] · x + (y ₁ · x _2h -y ₂ · x _1h ) / (x _2h -x
_1h ) ”will be described below.

[0038] In FIG. 3, x ₁ is the sensitivity setting G _n, an output value of the A / D converter circuit 43 which definitive when the first gas (O2) is filled into the smoke chamber, x ₂ is This is the output value of the A / D conversion circuit 43 when the smoke chamber is filled with the second gas (F12) at the set sensitivity _Gn .

At this time, y ₁ = a · x ₁ + b and y ₂ = a · x ₂ + b. Solving the simultaneous equations based on these two equations gives a = {(y ₂ −y ₁ ) / (x ₂ -x ₁ )}, and b = (y ₁ x ₂ -y ₂ x ₁ ) / (x ₂ -x ₁ ). Therefore, when a and b are substituted into the general formula, y = a × x + b = {(y ₂ −y ₁ ) / (x ₂ −x ₁ )} × x (y ₁ × ₂ −y ₂ × ₁ ) / (x _2-
x ₁ ).

[0040] Incidentally, the first calibration data x _1h, the second calibration data x _2h is because the data when it is amplified by the high gain G _h than the gain G _n of the amplifier 40 in the setting sensitivity, x ₁ = x _1h · (G _n / G _h ) and x ₂ = x _2h · (G _n / G _h ). Therefore, y = [(y ₂ −y ₁ ) / {(x _2h -x _1h ) · (G _n / G _h )}] · x + (y ₁ · x _2h -y ₂ · x
_1h ) / (x _2h -x _1h ).

When the output data y thus obtained is supplied to the D / A conversion circuit 71, the D / A conversion circuit 71
Converts the output data y into an analog value, the signal output circuit 72 sends it to the receiver 2, and the appropriate smoke density value corresponding to the current output data x of the A / D conversion circuit 43 is displayed on the smoke density display device 2d. Is done. For example, if the current smoke density is 0.06
% / M, as shown in FIG.
K, and the parts from "0.01" to "0.06" are turned on.

In the above embodiment, the concentration of oxygen gas is set to 0.1.
005% / m or 0.035% /
In the vicinity of m, there is no advantage of increasing the gain when taking the first calibration data x _1h and the second calibration data x _2h , but the smoke concentration is higher than the gas concentration used when taking the calibration data. Concentration range (eg, 0.05% / m
And near 0.10% / m), the concentration measurement error is reduced.

In the above embodiment, pure gas is
Although the oxygen gas and the chlorofluorocarbon 12 gas are used, pure gases other than these may be used, or three or more kinds of pure gases may be used. Further, in the above-described embodiment, the case where the xenon lamp is used has been described. However, a light-emitting lamp other than the xenon lamp may be used.

In the above embodiment, the analog signal is transmitted to the receiver 2. However, the analog signal may be transmitted to the receiver 2 in the state of a digital signal.

Further, in the above embodiment, when the sensitivity characteristic is calibrated, the gain switching circuit 41 is driven to switch the gain of the amplifier 40 to the maximum value. G _{n at}
It may be amplified by the high gain G _h than.

In the above embodiment, the current output data
The output data y to the D / A conversion circuit 71 corresponding to x is
Data x _1h , x _2h , y ₁ , y ₂ , calculated using Gn / Gh, but without using data Gn / Gh, data x _1h , x _2h , y _1h ,
The output data y can be calculated using _y2h .
_{That, y = {(y 2h -y} 1h) / (x 2h -x 1h)} · x + (y 1h ·
x _2h -y _2h · x _1h) is / (x _2h -x _1h). Note that the data x _1h is output data of the A / D conversion circuit 43 when the smoke chamber 30 is filled with the first gas, and the output signal of the light receiving element 20 has a gain higher than the gain at the set sensitivity. Is the first calibration data when A is amplified, and the data x _2h is the output data of the A / D conversion circuit 43 when the smoke chamber 30 is filled with the second gas. This is the first calibration data when the output signal of the light receiving element 20 is amplified with a gain higher than the gain. Data y _1h is output data of the signal output circuit 72 corresponding to the first calibration data x _1h , and data y _2h is output data of the signal output circuit 72 corresponding to the second calibration data x _2h. is there. Also, the data
y _1h and y _2h are calculated in advance as follows.

That is, the output data x ₁ of the A / D conversion circuit 43 for the first gas when the amplifier 40 is set to the set sensitivity, and the A / D for the second gas when the amplifier 40 is set to the set sensitivity. the output data x ₂ D conversion circuit 43, the output data y ₁ of the signal output circuit 72 required for displaying a smoke density corresponding to the first gas to the smoke density display device, corresponding to the second gas Output data of the signal output circuit 27 necessary for displaying the smoke density on the smoke density display device
Using y ₂ , y _1h = {(y ₂ −y ₁ ) / (x ₂ −x ₁ )} · (G _h / G _n ) · x ₁ +
_{(Y 1 · x 2 - y} 2 · x 1) / (x 2 -x 1) y 2h = {(y 2 -y 1) / (x 2 -x 1)} · (G h / G n) · x ₂ +
Calculate (y ₁ x ₂ -y ₂ x ₁ ) / (x _2- x ₁ ).

In the above embodiment, the memory such as the EEPROM 61 for the detected value of the reference gas for calibration and the arithmetic means are provided on the smoke detector 1 side. It may be provided on the repeater side that is not used.

In the above embodiment, the smoke density display device 2
Although d is provided on the receiver 2 side, it may be provided on the smoke detector 1 side.

[0050]

According to the present invention, an output data of the definitive A / D converter when the first gas in the smoke chamber is filled, high gain G _h than the gain G _n in the set sensitivity
The first calibration data x _1h when the output signal of the light receiving element is amplified, and the output data of the A / D conversion circuit when the smoke chamber is filled with the second gas, wherein the sensitivity is set. and second calibration data x _2h when the gain G _n higher gain than G _h, the output signal of the light receiving element is amplified in, a
An appropriate smoke density value corresponding to the current output data of the A / D conversion circuit was calculated based on the output data of the / D conversion circuit, and this was converted by the gain _Gn at the set sensitivity.
The sensitivity adjustment work of the smoke sensing device is easy, the sensitivity adjustment work can be completed in a short time, and the accuracy of the smoke concentration in the smoke concentration region higher than the gas concentration used when taking the calibration data Is high.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment.

FIG. 3 is a diagram showing a relationship between output data of an A / D conversion circuit 43 and output data of a D / A conversion circuit 71 in the embodiment.

FIG. 4 is a diagram showing a smoke density display device 2d provided in a receiver connected to the embodiment.

FIG. 5 is a circuit diagram showing a main part of a conventional smoke detector.

FIG. 6 shows the smoke density and the signal output circuit 8 in the conventional example.
FIG. 7 is a diagram illustrating a relationship with a value of a current output by a reference numeral 7.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Smoke detector, 2 ... Receiver, 2d ... Smoke density display device, 1
0 ... xenon lamp, 11 ... trigger circuit, 20 ... light-receiving element, 30 ... smoke chamber, 40 ... amplification unit, 41 ... gain switching circuit, 50 ... control circuit, 60 ... ROM, 61 ... detection value of the calibration reference gas EEPROM, 74: Calibration confirmation light circuit.

Continuation of front page (72) Inventor Tadao Morita 4-7-3 Kudanminami, Chiyoda-ku, Tokyo Nomi Disaster Prevention Co., Ltd. (58) Field surveyed (Int.Cl. ⁷ , DB name) G08B 17/00-17 / 12

Claims (4)

(57) [Claims] 1. A smoke chamber including a light emitting lamp and a light receiving element for receiving light from the light emitting lamp; an amplifier for amplifying an output signal of the light receiving element; and converting an output signal of the amplifier into a digital signal. An A / D conversion circuit;
Calculating means for performing a predetermined calculation based on output data of the conversion circuit; a signal output circuit for sending an output signal of the calculating means to a smoke density display device for displaying smoke density; Is the first calibration data x _1h , which is the output data of the A / D converter circuit when the output signal of the light receiving element is amplified with a gain higher than the gain at the set sensitivity. When the second chamber is filled with the second gas.
A memory for storing, as the second calibration data _x2h , data obtained when the output signal of the light receiving element is amplified at a gain higher than the gain at the set sensitivity, the data being output data of the / D conversion circuit. The calculating means converts the first calibration data x _1h into a gain at a set sensitivity, the first conversion data
and x _1, and the second conversion data x ₂ is a data in terms of the gain in sensitivity setting said second calibration data x _2h, displaying a smoke density corresponding to said first gas to said smoke density display device Necessary for the output data y of the above signal output circuit
_1, a smoke density corresponding to the second gas on the basis of the output data y ₂ of the signal output circuit necessary for displaying on the smoke density display device, the current output of the A / D converter circuit A fire detecting device, which is means for calculating output data y required to display an appropriate smoke density value corresponding to data on the smoke density display device. 2. The method according to claim 1, wherein the calculating means includes a first calibration data x _1h stored in the memory and a second calibration data x _1h stored in the memory.
_x2h , the output data x of the A / D conversion circuit when the amplifier is set to the set sensitivity, and the signal necessary for displaying the smoke density corresponding to the first gas on the smoke density display device. the output data y ₁ of the output circuit, a smoke density corresponding to the second gas and the output data y ₂ of the signal output circuit necessary for displaying on the smoke density display device, and to set the sensitivity of the above amplifier The output data y necessary to display the appropriate smoke density value corresponding to the output data of the A / D conversion circuit at the time on the smoke density display device, the gain _{Gn at the} set sensitivity, and the gain _Gn Y = [(y ₂ −y ₁ ) / {(x _2h −x _1h ) · (G _n / G _h )}] based on the high gain G _h
• By calculating x + (y ₁ x _2h- y ₂ x _1h ) / (x _2h- x _1h ). A fire detecting device for calculating the output data y. 3. A smoke chamber including a light emitting lamp and a light receiving element for receiving light from the light emitting lamp; an amplifier for amplifying an output signal of the light receiving element; and converting an output signal of the amplifier into a digital signal. An A / D conversion circuit;
Calculating means for performing a predetermined calculation based on output data of the conversion circuit; a signal output circuit for sending an output signal of the calculating means to a smoke density display device for displaying smoke density; Is the first calibration data x _1h , which is the output data of the A / D converter circuit when the output signal of the light receiving element is amplified with a gain higher than the gain at the set sensitivity. When the second chamber is filled with the second gas.
The output data of the / D conversion circuit, the data when the output signal of the light receiving element is amplified with a gain higher than the gain at the set sensitivity is stored as second calibration data _x2h , and calculated in advance. first predetermined output data y _1h of the signal output circuit corresponding to said first calibration data x _1h
And a memory for storing the second predetermined output data y _2h of the signal output circuit corresponding to the second calibration data x _2h . The arithmetic means includes the first calibration data x _1h And the second calibration data x _2h , the output data y _1h, and the output data
characterized in that on the basis of the y _2h, a means for calculating the output data y necessary for the proper smoke density value corresponding to the current output data of the A / D converter circuit be displayed on the smoke density display device And fire detection device. 4. The method according to claim 3, wherein the calculating means includes the first calibration data x _1h stored in the memory, the second calibration data x _2h stored in the memory, and the amplifier. The output data x 1 of the A / D conversion circuit when the sensitivity is set, and the output data y _{1 of the} signal output circuit necessary for displaying the smoke density corresponding to the first gas on the smoke density display device. And output data y of the signal output circuit necessary for displaying the smoke density corresponding to the second gas on the smoke density display device.
₂ and A when the amplifier is set to the set sensitivity.
Output data y required to display an appropriate smoke density value corresponding to the output data of the / D conversion circuit on the smoke density display device.
When the gain G _n in the set sensitivity, the high gain G _h than the gain in the sensitivity setting, and the first predetermined output data y _1h, based on the said second predetermined output data y _2h , Y _1h = {(y ₂ −y ₁ ) / (x ₂ −x ₁ )} · (G _h / G _n ) · x ₁ +
_{(Y 1 · x 2 - y} 2 · x 1) / (x 2 -x 1) y 2h = {(y 2 -y 1) / (x 2 -x 1)} · (G h / G n) · x ₂ +
_{(Y 1 · x 2 - y} 2 · x 1) / with (x ₂ -x ₁₎ for calculating _{a, y = {(y 2h -y} 1h) / (x 2h -x 1h)} · x + (y 1h・
x _2h −y _2h · x _1h ) / (x _2h −x _1h ), whereby the output data y is calculated.