JP2001141559A - Flame detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame detector prevented from an erroneous operation state even if noise above a fire level is produced so as to prevent a delay in fire detection. SOLUTION: When a detection element detects flame, a narrow-band filter extracts necessary frequency constituents and a smoothing means smoothens these constituents so as to output a detection signal. If the detection signal exceeds a predetermined fire determination level, generation of flame is determined and the detection signal is discharged, and the determination of the generation of flame is counted. When the count value reaches a predetermined value, the occurrence of a fire is determined, and the count value is canceled if the detection signal is below the fire level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame detector for detecting a fire by detecting ultraviolet rays, infrared rays or the like generated by a flame.

[0002]

2. Description of the Related Art Heretofore, when a fire related to a flame is detected, a method has been adopted in which a time delay is performed to confirm whether or not the fire has occurred in order to prevent a malfunction when the fire is detected.

[0003] That is, the detection element detects ultraviolet rays, infrared rays, and the like that generate a flame, and the detection signal reaches a predetermined fire determination level even if a predetermined delay time elapses. If the signal is maintained at or above the fire determination level, it is determined that a fire has occurred.

[0004]

FIG. 6 is a diagram showing the operation of the conventional example.

As shown in FIG. 6, when noise occurs even once, the state continues to exceed the fire determination level due to periodic sampling and malfunctions. In other words, according to the conventional method, when noise (external light noise or thermal noise) that is higher than the fire determination level occurs, the detection signal becomes higher than the fire determination level, and the flame detector may malfunction. There's a problem.

In this case, if the delay time is set longer than a predetermined time, it is possible to prevent a malfunction state. However, if the delay time is increased in this way, the timing of fire detection is delayed. Another problem arises.

Further, in the conventional method, an internal light source and an external light source are provided inside and outside of a light receiving glass accommodating a detecting element. During a function test, after irradiating the internal light source, an output signal (detection signal) of a smoothing circuit is provided. Since the external light source is irradiated after the stabilization, the required time for the function test is long.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flame detector which does not cause a malfunction in a flame detector even if noise higher than a fire determination level is generated, and which does not delay fire detection. .

The present invention also provides an internal light source and an external light source provided inside and outside a light-receiving glass for accommodating a detecting element, respectively. It is an object of the present invention to provide a flame detector capable of shortening the required time.

[0010]

According to the present invention, a detecting element detects a flame, a narrow band filter extracts a required frequency component, the smoothing means smoothes the frequency component, and outputs a detection signal.
When this detection signal exceeds a preset fire determination level, it is determined that a flame is occurring, and when it is determined that a flame is occurring, the detection signal is discharged, and the flame is generated. When the count value reaches a predetermined value, it is determined that a fire has occurred. When the detection signal does not exceed the fire determination level, the count value is set to 0. It is a vessel.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a flame detector FD1 according to one embodiment of the present invention.

The flame detector FD1 includes a long-wavelength-side detection element 10
, A narrow band filter 20, an amplifier circuit 30, a smoothing circuit 40, a short wavelength side detection element 10a, a narrow band filter 20a, an amplifier circuit 30a, a smoothing circuit 40a, a discharge circuit 50, a CPU 60 , A transmission unit 70, and a constant voltage unit 80.

The long-wavelength-side detection element 10 and the short-wavelength-side detection element 10a are detection elements for detecting ultraviolet rays, infrared rays, and the like that generate flame.

The narrow-band filters 20 and 20a are filters that pass signals of 1 to 20 Hz, which are flame fluctuation components, among the signals detected by the detection elements 10 and 10a.

The smoothing circuits 40 and 40a are examples of smoothing means for smoothing output signals of the narrow band filters 20 and 20a and outputting detection signals.

The CPU 60 is an example of flame occurrence judging means for judging that a flame is occurring when the detection signal exceeds a preset fire judgment level.

The discharging circuit 50 is an example of discharging means for discharging the detection signal when the flame generation detecting means determines that a flame is generated.

The CPU 60 is an example of counting means for counting the number of discharges, and is an example of fire determining means for determining that a fire has occurred when the count value reaches a predetermined value. This is an example of a count value reset unit that sets the count value to 0 when the detection signal does not exceed the fire determination level.

The CPU 60 includes a ROM storing a program and a fire discrimination level, and the detecting elements 10 and 10a.
RAM for temporarily storing a detection signal output from the A. A for converting the detection signal from an analog signal to a digital signal
/ D conversion unit.

FIG. 2 is a circuit diagram showing a specific example of the flame detector FD1, and is a circuit diagram centering on the long wavelength side detection element 10.

The detecting element 10 includes a detecting element 11 such as a pyroelectric element and a load resistor 12 thereof.

In the narrow band filter 20, infrared light received by the detection element 10 is input to a narrow band filter amplifier 25. The filter 20 includes an amplifier 25 and capacitors 21 and 2
3 and resistors 22 and 24, 1 to 20H
Pass through the fluctuation of the flame of z. A Zener diode 82 as a constant voltage circuit 15 is used as a reference voltage of the amplifier 25.
And the capacitor 83 supplies a stable voltage. The resistor 81 is a current limiting resistor.

The amplifier circuit 30 receives a signal of 1 to 20 Hz into the amplifier 31, and the amplifier 31 and resistors 32, 33, 3
The signal is amplified by the amplifier circuit composed of

In the smoothing circuit 40, the signal passed through the coupling capacitor 41 is fed to the FET 42 and the resistor 43.
, And the capacitor 45 is charged via the resistor 44 and smoothed. Resistance 4
Reference numeral 6 denotes a discharge resistor for discharging a signal, which is discharged slowly so that the signal maintains a stable state.

In the CPU 60, this signal is input to the A / D converter of the CPU 60 via the protection resistor 54,
Execute fire judgment.

The discharge circuit 50 includes a base resistor 52, a transistor 51, and a discharge resistor 53. The transistor 51 is connected to the CPU 60 via the base resistor 52.
Is turned on / off according to the presence or absence of an output from the
By discharging the signal of 0, the detection signal does not reach the level at which a fire is caused unless there is a light source in front of the detection element 11.

A circuit centering on the short-wavelength side detection element 10a has the same configuration as the circuit shown in FIG.

FIG. 4 is a diagram showing detection wavelength characteristics of the detection elements 10 and 10a and wavelength characteristics of light generated from various light sources.

In FIG. 4, the detection area of the long wavelength side detection element 10 has a wavelength of 1.6 to 1.8 μm, and is formed by the characteristics of the pyroelectric element as an element and the optical filter on the front surface thereof. ing. The detection area of the short wavelength side detection element 10a has a wavelength of 0.9 to 1.1 μm, which is the characteristic itself of the photodiode as the element. The spectral characteristics of gasoline-centered flame and the characteristics of misinformation of various electric lights and sunlight are shown for both elements 10, 10a. It is based on not only the predetermined level of the detection element 10 but also a predetermined output ratio with the output of the short wavelength side element 10a at that time. It is to be noted that the detection areas of the two elements as the two-wavelength type are not limited, and may have a width around each wavelength.

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

FIG. 3 is a flowchart showing the operation of the above embodiment.

Here, steps S1 to S5 are fire monitoring operations, steps S11 to S13 are operations for discriminating between fire and noise, and steps S21 to S27 are:
This is a functional test.

When determining a fire (S1), first, the CPU
The value of the fire counter, which is a function of 60, is reset to "0" (S2). The output signal of the detection element 10 on the long wavelength side is smoothed and sampled (S3), and the output signal of the detection element 10a on the short wavelength side is smoothed and sampled (S4).

Then, the sampled value (detection signal)
Is determined whether or not exceeds the fire determination level (S
5). For example, the value of the output signal of the long wavelength side detection element 10 is equal to or higher than the first predetermined level, and the value of the output signal of the long wavelength side detection element 10 and the value of the output signal of the short wavelength side detection element 10a are different from each other. Is greater than or equal to a second predetermined level,
It is determined that the value exceeds the fire determination level, and step S11 is performed.
Proceed to.

If the detection signal exceeds the fire determination level (S5), the discharge circuit 50 is turned on (S11), the output signals of the smoothing circuits 40 and 40a are set to 0, and the fire counter is incremented by "1" (S11). S12).

Here, the value of the fire counter is used to count the number of times that it is determined that a flame has occurred. If the value of the fire counter has not reached 3 (S13), the flow returns to step S3. If the value of the fire counter has reached 3 (S13), a fire signal is transmitted to a fire receiver (not shown) (S14). The value of the fire counter as a condition for transmitting the fire signal to the fire reception may be set to a value other than 3.

In FIG. 3, "noise 1" is a noise having a value equal to or higher than the fire determination level, and "noise 2"
Is noise below the fire determination level. As the "noise 1", for example, headlight noise of a truck passing through a tunnel, thermal noise due to a muffler, and the like are considered, and the level is often much higher than the fire determination level.

In the above embodiment, in step S11, the detection signal (the output signal of the smoothing circuits 40 and 40a)
Is discharged, so that even if the detection signal at that time is noise and the level is considerably high, it is discharged. As a result, the flame detector FD1 does not malfunction and the fire detection is not delayed.

On the other hand, if the output signals of the detection elements 10 and 10a do not include a signal exceeding the fire determination level (S5) and if a function test needs to be performed (S21), the light receiving glass Are irradiated on the detection elements 10 and 10a (S22), the detection signals are sampled (S23), and discharged by the discharge circuit 50 (S24). After being stabilized by the discharge, an external light source (not shown in detail) provided outside the light receiving glass is detected by the detecting elements 10 and 1.
It irradiates 0a (S25), samples a detection signal (S26), and transmits the test result to a receiver (not shown) (S27).

As described above, the detection element 1
The level of light emission applied to 0, 10a is high, and noise 1
If the detection signal continues to be high as in the case of (1), it is necessary to wait for the detection signal to stabilize. However, after the detection signal has stabilized by the discharge, the detection element 1
Since irradiation is performed to 0 and 10a, the time required for the function test can be shortened. In an actual system, since a large number of flame detectors FD1 are connected to a receiver (not shown), the reduction of each test time is extremely large in terms of the test time of the entire system.

FIG. 5 shows the CPUs in the above embodiment when a fire is detected without noise and when a fire is detected in the presence of noise.
FIG. 6 is a diagram illustrating an input signal of the first embodiment;

That is, the detection signals output by the smoothing circuits 40 and 40a when no noise occurs and when noise occurs are shown in FIG.

When the signal output is amplified by noise, the level exceeds the fire determination level due to periodic sampling. However, the transistor 51 of the discharge circuit 50 is temporarily turned on, and the charge of the capacitor 45 is forcibly forced by the discharge resistor 53. Since the battery is discharged temporarily and returned to the monitoring state, malfunction can be prevented, and a fire can be immediately detected.

On the other hand, in the event of a fire, a detection signal higher than the fire discrimination level is continuously generated even after the discharge, so that the fire is determined.

According to the above embodiment, in the flame detector,
When the detection signal reaches the fire determination level due to single noise, discharge the detection signal so that it does not malfunction.
By distinguishing between fire and noise, fire can be detected early. That is, in the above embodiment, the fire is immediately monitored by the discharge, and the fire can be detected early.

It is not necessary to limit the timing at which the discharge circuit 50 discharges the detection signal only to the case where the fire detection level is exceeded, and the discharge circuit 50 is driven after sampling (S3 and S4 in FIG. 3). You may make it discharge. Usually, a false alarm similar to a flame often occurs in a pulsed manner. However, when low-level stationary noise is accumulated, it is preferable to drive the discharge circuit 50 for each sampling. In addition, the discharge circuit 50
Is also advantageous in that the 0 level of the detection signal is stabilized.

In the above embodiment, the case where the detection elements 10 and 10a are used has been described as the two-wavelength type.
As for the infrared region, one infrared detecting device for a wide or narrow wavelength may be used, or an ultraviolet detecting device for the ultraviolet region may be used.

[0048]

According to the present invention, even if noise higher than the fire determination level occurs, the flame detector does not malfunction.
Also, there is an effect that the fire detection is not delayed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a flame detector FD1 according to one embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific example of a flame detector FD1,
FIG. 3 is a circuit diagram mainly showing a long-wavelength-side detection element 10.

FIG. 3 is a flowchart showing the operation of the embodiment.

FIG. 4 is a diagram illustrating wavelength characteristics of light generated from various light sources.

FIG. 5 is a diagram showing input signals of a CPU 60 in the above embodiment when a fire is detected without noise and when a fire is detected in a situation where noise is present.

FIG. 6 is a diagram showing an operation of a conventional example.

[Explanation of symbols]

 FD1: flame detector, 10: long wavelength side detection element, 10a: short wavelength side detection element, 20, 20a: narrow band filter, 30, 30a: amplification circuit, 40, 40a: smoothing circuit, 50: discharge circuit, 60 CPU.

Claims (5)

[Claims] 1. A detecting element for detecting ultraviolet rays, infrared rays, etc. generated by a flame; and among signals output by the detecting element,
A narrow-band filter for extracting a necessary frequency component; a smoothing means for smoothing an output signal of the narrow-band filter and outputting a detection signal; and a flame when the detection signal exceeds a preset fire determination level. Flame generation determining means for determining that a flame has occurred; discharge means for discharging the detection signal when the flame generation detection means has determined that a flame has occurred; Counting means for counting the number of times judged by the occurrence detecting means; fire judging means for judging that a fire has occurred when the count value reaches a predetermined value; and if the detection signal does not exceed the fire judgment level, And a count value resetting means for setting the count value to zero. 2. The function testing device according to claim 1, wherein the function of the detecting element or the contamination of the light receiving glass is measured; and after the function of the detecting element or the contamination of the light receiving glass is measured, the detection signal is transmitted to the discharging means. Control means for controlling discharge to the flame. 3. The internal light source according to claim 2, wherein the function test means includes an internal light source provided inside the light receiving glass, and an external light source provided outside the light receiving glass. And a means for irradiating the detection element from the external light source after the detection signal is stabilized by the discharge. 4. The method according to claim 2, wherein a plurality of the flame detectors are provided, and the function test is performed on one of the plurality of flame detectors according to a command from a fire receiver. A flame detector, wherein the function test is performed on another flame detector. 5. A detecting element for detecting an ultraviolet ray, an infrared ray, or the like that generates a flame; a smoothing means for smoothing an output signal of the detecting element and outputting a detection signal; and wherein the detection signal is set in advance. Flame detection characterized by having flame generation determining means for determining that a flame is generated when the fire determination level is exceeded; and discharging means for discharging the detection signal after processing by the flame generation determining means. vessel.