JP3312711B2 - Infrared 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 an infrared fire detector for detecting a fire by receiving infrared energy radiated from a flame. The present invention relates to an infrared fire detection device that recognizes a spectral characteristic peculiar to a flame from a light receiving signal in a wavelength band out of a wavelength band indicating a wavelength band and a peak value to determine a fire.

[0002]

2. Description of the Related Art Conventionally, in an infrared fire detection apparatus for detecting a fire by detecting infrared energy radiated from a flame, the determination is made based on the spectral characteristic characteristic of the flame shown in FIG. The spectral characteristic of the flame is 4.3 μm in the infrared region.
It has a radiation peak near it. With respect to such spectral characteristics unique to the flame, for example, sunlight as a disturbance has a peak from a visible light region to a near-infrared region, and is sufficiently attenuated in a band showing a peak unique to the flame. The 400 ° C. high-temperature object has a peak near 4.3 μm, which is the same as that of the flame, but is gradually attenuated on both sides. Therefore, the spectral characteristics of the flame having a sharp peak near 4.3 μm can be clearly distinguished from disturbances such as sunlight and high-temperature objects.

[0003] Further, the flame has a unique flicker,
It is known that the flicker frequency is between 1 and 10 Hz. Therefore, in order to judge a fire from the infrared energy emitted from the flame, it is only necessary to detect a steep peak characteristic around 4.3 μm, a flicker frequency specific to the flame, or both.

[0004] Conventionally, as a flame detecting device for judging a fire from the spectral characteristics peculiar to a flame having a peak around 4.3 μm,
For example, there is Japanese Unexamined Patent Publication No. 50-2497 shown in FIG. FIG. 11A shows the structure of the detection device,
5, the rotating plate 101 is rotated.
As shown in (B), the band-pass filters 102, 103,
104 are provided.

For this reason, the filters 102, 103, 104
Is the rotation of the rotating plate 101 by the motor 105, which is positioned in front of the photoelectric conversion device 106 using the pyroelectric element and Cds in order, and the infrared light in the filter wavelength band emitted from the flame 100 enters the photoelectric conversion device 106. Convert to electrical signals. For example, λ1 = 3.5 μm, λ2 = 4.3 μm, and λ3 = 5.1 μm are selected as the passing wavelength bands of the bandpass filters 102, 103, and 104.

[0006] Such three filters 102, 10
The point A in FIG.
Light receiving levels of three wavelengths of points B and C are obtained. If there is a flame, there is a sufficient level difference between point B and points A and C on both sides as shown in the figure. Can be judged as a fire.

[0007]

However, in an infrared fire detection device that determines the spectral characteristic unique to a flame from a received light signal obtained by switching a filter, a motor is always used for switching a filter in a normal monitoring state. , And the current consumption per detecting device is not so large, several tens of mA. However, since a plurality of such detecting devices are connected to a power / signal line from a receiver, The current consumption per line increases with the number of detectors installed. Considering that the current consumption of ordinary fire detectors is several tens of microamperes per unit, the number of detectors installed per line is large. In order to install the required number, the power capacity of the receiver must be increased.

Further, since the filter switching motor is driven continuously, the life of the detection device is determined by the endurance time of the motor, and there is a problem that it is difficult to perform stable fire monitoring over a long period of time. The present invention has been made in view of such a conventional problem, and has an infrared fire detection system that detects spectral characteristics peculiar to a flame by switching a filter that consumes a small amount of current and ensures a stable monitoring operation for a long period of time. It is intended to provide a device.

[0009]

In order to achieve this object, the present invention is configured as follows. First, the present invention provides a light receiving unit that detects infrared rays emitted from a flame and converts it into an electric signal, and a wavelength band (4.3) in which the amount of radiation from the flame shows a peak value.
μ), a filter plate including one or more second filters that pass infrared light in a wavelength band outside the peak wavelength band, a filter plate having one or more second filters, Targeted is an infrared fire detector that has a filter drive unit such as a motor for selectively positioning and a fire judgment unit that judges a fire from a change in the light reception signal obtained by the light reception unit by switching the filter by the filter drive unit. And

In the infrared fire detecting apparatus according to the present invention, the light receiving signal of the light receiving section is predetermined when the filter driving section in which the first filter of the filter plate is positioned on the incident optical path of the light receiving element is stopped. If the threshold is exceeded,
A drive control unit is provided which activates the filter driving unit, switches the filter with respect to the optical path of the light receiving unit, and makes the fire judgment unit make a fire judgment.

Further, the infrared fire detection apparatus of the present invention is provided with a test section for performing an operation test by turning on a check light source such as a halogen lamp and causing light from the check light source to enter the light receiving section during a test. It is characterized by the following. Further, as the drive control unit of the present invention, when the filter drive unit in which the first filter of the filter plate is positioned on the incident light path of the light receiving element is stopped, the light receiving signal of the light receiving unit exceeds a predetermined threshold, and When the flicker frequency peculiar to the flame is detected from the received light signal, the filter driving unit is activated to switch the filter with respect to the optical path of the light receiving unit, and the fire determining unit makes a fire determination based on the received light signal of the light receiving element obtained. You may do so.

In the infrared fire detecting apparatus of the present invention, a check light source such as a halogen lamp is turned on during a test, and light from the check light source is allowed to enter a light receiving portion through the first filter. A test section was set to set the rotation cycle located on the incident path of the light receiving section to be within the range of the flicker frequency peculiar to the flame, and to control the filter drive section to rotate the filter plate to perform an operation test. It is characterized by the following.

Further, after transmitting the fire detection signal to the outside from the fire determination unit, the drive control unit stops the filter drive unit with the first filter positioned at the light receiving unit, and reduces the drive time of the motor and the like. Minimize necessary.

[0014]

According to the infrared fire detecting device of the present invention, in the steady monitoring state, the first filter near 4.3 μm in the spectral characteristic characteristic of the flame is located in front of the light receiving section. For example, the light receiving level is monitored when the motor as the driving unit is stopped, and since the motor is not required to be driven, the current consumption of the detection device can be suppressed to a sufficiently low value as in a normal fire detector. Therefore, a plurality of infrared fire detectors can be connected to the power / signal line from the receiver in the same manner as a normal fire detector, and there is no need to increase the power capacity of the receiver.

[0013] In addition, the monitoring while the motor is stopped 4.3.
When the light receiving level in the vicinity of μm exceeds the threshold level due to the energy from the flame due to the fire, the filter switching by the motor start is started, the peak value of the radiation amount is in the vicinity of 4.3 μm, and the flame which falls sharply on both sides. Judgment as to whether or not the spectral characteristics are peculiar is performed, false alarms due to heat sources other than flames are prevented, and highly reliable fire detection can be performed.

Further, although the current consumption of the detecting device is increased by driving the motor, after the fire detection signal is transmitted after judging the flame, the motor is stopped so that the detecting device connected to the same line can simultaneously drive the motor. Is very unlikely to occur, and there is no problem that current consumption increases. Further, the motor is driven only for the time required for determining the spectral characteristics of the flame, for example, for only a few seconds, so that there are few failures and the life is greatly extended. Furthermore, an operation test can be performed by turning on a check light source such as a halogen lamp at the time of the test, so that the reliability is high.

[0017]

FIG. 1 is a block diagram showing an embodiment of an infrared fire detector according to the present invention. In FIG. 1, a filter plate 1 rotated by a motor 2 is provided,
The light receiving section 8 is arranged behind the filter plate 1. As shown in FIG. 2, the filter plate 1 is a disk-shaped plate member, and filters 3, 4, and 5 are provided at three positions shifted by 120 ° from the center of rotation.

The filters 3, 4, and 5 are set to pass wavelength bands indicated by the spectral characteristics unique to the flame shown in FIG. First, the filter (first filter) 3 has a pass wavelength band centered on a wavelength λ2 = 4.3 μm having a steep peak of the spectral characteristic of the flame in FIG. On the other hand, the filter (second filter) 4 has a wavelength λ1 = a steeply falling valley portion on the left side of the peak portion in FIG.
It has a pass wavelength band centered at 4.0 μm.

Further, a filter (second filter) 5 is provided as shown in FIG.
Has a pass wavelength band centered on the wavelength λ3 = 4.7 μm at the steeply falling valley portion on the right side of the peak of, that is, on the long wavelength side. Further, the filter 3 of the filter plate 10
A slit 7 is formed at a target position via the center. A photo interrupter 6 is provided for the slit 7 as shown in FIG. The photo interrupter 6 has a light emitting element on one side and a light receiving element on the other side with the slit 7 interposed therebetween, and receives light from the light emitting element at the position of the slit 7 and outputs a position detection signal.

As the light receiving section 8, an appropriate infrared detecting element such as a pyroelectric element is used to receive infrared energy transmitted through one of the filters 3, 4 and 5 provided on the filter plate 1. To convert it into an electric signal. The output of the light receiving unit 8 is supplied to an amplified signal processing unit 9, where signal processing such as amplification of a weak light receiving signal and noise removal is performed, and the signal is output to a fire determining unit 10. The fire determination unit 10 makes a fire determination according to the spectral characteristics unique to the flame in FIG.

The motor 2 for rotating the filter plate 1 is controlled by a drive control unit 11. In the steady monitoring state, the drive control unit 11 stops while driving and positioning the motor 2 so that the slit 7 of the filter plate 1 is located at a position detected by the photo interrupter 6. At the detection position of the slit 7 by the photointerrupter 6, the filter 3 provided on the filter plate 1 and having a pass characteristic of a wavelength band of a peak wavelength of 4.3 μm is located in front of the light receiving element 8.

Therefore, in the steady monitoring state, the infrared energy of the peak portion of the spectral characteristic centered on λ2 = 4.3 μm in FIG. In a steady monitoring state in which the motor 2 is stopped by the drive control unit 11, the fire determination unit 10 determines a predetermined threshold value TH as shown in FIG. 8 are compared.

When the fire judging unit 10 judges that the light receiving signal has exceeded the threshold value TH, a start signal is output to the drive control unit 11, and the drive control unit 11 drives the motor 2 to
The rotation of the filter plate 1 is started. Therefore, as shown in the filter plate 1 of FIG.
The three filters 3, 4, and 5 are arranged in order, and the light receiving signals in the respective wavelength bands of the wavelengths λ1, λ2, and λ3 in the spectral characteristics of FIG.

The fire judging unit 10 judges from the level of the received light signal obtained in synchronization with the switching of the filters 3, 4 and 5 whether or not the characteristic has a steep peak characteristic peculiar to the flame shown in FIG. When it is determined that the characteristic is the peak characteristic, a fire detection signal is transmitted to a receiver or the like via a signal line. At the same time, a drive stop signal is output to the drive control unit 11 to stop driving the motor 2.

FIG. 4 is a flowchart showing a first embodiment of the control processing by the drive control section 11 of FIG. First, in step S1, a filter 3 having a center wavelength of 4.3 μm as shown is set so as to be in front of the light receiving unit 8, and in step S2, the light received from the light receiving unit 8 that has passed through the filter 3 and entered. The light receiving signal from the amplified signal processing unit 9 based on the signal is read into the fire judging unit 10, and it is monitored in step S3 whether the signal is equal to or more than the threshold value TH.

When the light receiving signal of the light receiving section 8 increases and exceeds the threshold value in step S3, the drive control section 11 starts the motor 2 in response to the start signal from the fire judging section 10. By the rotation of the filter plate 1 due to the start of the motor 2, the filters are positioned in front of the light receiving element 8 in the order of, for example, the filters 4, 5, and 3 in FIG. In each of S6 and S7, the received light signal of each of the filters 3, 4, and 5 is read into the fire determination unit 10.

In step S8, filters 3,
Reading of the received light signal by the set of 4 and 5 is a predetermined N
It is checked whether the process has been performed or not, and the processes of steps S5 to S7 are repeated until the process has been performed N times. When reading of the light receiving signal by the set of the filters 3, 4, 5 is performed N times, the process proceeds to step S9, where the center wavelength λ as shown in FIG.
For example, an average value of light receiving signals for each of 1, λ2 and λ3 is obtained,
It has a peak level in the center wavelength band λ2, and determines whether or not it has a sharply falling low level in the wavelength bands λ1 and λ3 on both sides.

More specifically, when the levels of the wavelength bands of the wavelengths λ1 and λ3 on both sides are subtracted from the peak level of the band of the wavelength λ2, and when the difference exceeds both predetermined values,
It is determined that the steep peak characteristic peculiar to the flame has been obtained.
If it is determined that a fire has occurred as a result of the three-wavelength determination process in step S9, the process proceeds from step S10 to step S10.
Proceed to 11 to output a fire signal to an external receiver or the like.

When the output of the fire signal is completed, the motor 2 is stopped in step S12, and the routine returns to the regular monitoring state in step S2. Of course, when the motor is stopped in step S12, as shown in FIG. 1, the motor 3 is stopped at the position where the slit 7 is located in the photo interrupter 6, and the filter 3 is located in front of the light receiving unit 8. In step S10, 3
If it is determined that the fire is not a fire as a result of the wavelength determination processing, the motor is stopped in step S12, and the process returns to the steady monitoring state in step S2 again.

FIG. 5 is a flowchart showing a second embodiment of the processing operation by the drive control section 11 of FIG. The second embodiment is characterized in that the flicker frequency peculiar to the flame is determined in addition to the detection of the peak level. In FIG. 5, steps S1 to S3 are the same as those in the first embodiment of FIG. 4, and steps S6 to S14 are steps S4 to S12 of FIG.
It corresponds to. In addition to this, in the second embodiment,
In step S3, the peak wavelength band λ2 by the filter 3 =
If the level of the light receiving signal of 4.3 μm is equal to or greater than the threshold value TH, the flickering frequency in the specified range is determined in step S4, that is, the flickering frequency is obtained from the temporal level change of the light receiving signal obtained from the light receiving unit 8 with the filter 3 set. And find 1
If it is within the range of 10 Hz to 10 Hz, it is determined that the flame is present, and step S
Then, at this stage, a pre-alarm output is performed to an external receiver or the like.

When the pre-alarm output is completed, step S6
Then, the motor 2 is started, and the determination process is performed by the filter switching based on the rotation of the filter plate 1. The determination process is the same as in the first embodiment of FIG. As a result, the fire signal output in step S13 is obtained based on two determination results that there is a flicker frequency peculiar to a flame and a peak characteristic peculiar to a steep flame centered on a wavelength of 4.3 μm. Highly accurate fire judgment results are obtained.

In the second embodiment shown in FIG. 5, the pre-alarm output is performed at the stage where the flicker frequency is determined. However, in the first embodiment shown in FIG.
The pre-alarm output may be similarly performed when the light receiving signal becomes equal to or more than the threshold value TH with the filter 3 set. FIG. 6 shows another embodiment of the filter switching mechanism used in the infrared fire detection device of the present invention. This embodiment is characterized in that the filter is switched by linear driving.

In FIG. 6, filters 3, 4 and 5 are arranged laterally on the filter plate 12, and the filter plate 12 can be moved laterally by a slide actuator 13. Slide actuator 13
For example, an appropriate actuator such as an electromagnetic cylinder, an electromagnetic solenoid, and a power generation actuator can be used. The filter plate 12 movable by the slide actuator 13 shows an initial position. In this state, the slit 7 provided in the filter plate 12 is at an initial position where the slit 7 is fixed to the photointerrupter 6 fixedly arranged. At this time, the filter 3 is located in front of the light receiving unit 8 disposed on the back side.

For this reason, in the steady monitoring state, the slide actuator 13 is stopped so that the filter 3 is located in front of the light receiving section 8, and in this state, if the light receiving signal obtained from the light receiving section 8 exceeds the threshold value TH. Then, the slide actuator 13 is driven, and the slide is driven so that the filters 3, 4, and 5 are sequentially positioned in front of the light receiving unit 8. FIG. 7 shows another embodiment of the drive mechanism of the slide drive type filter plate 12, which is characterized by using a rack and pinion mechanism. That is, the filter plate 12 has three filters 3, 4 and 5 arranged side by side similarly to the embodiment of FIG. 6, and the filter is located at the initial position where the photo interrupter 6 is located in the slit 7 and in front of the light receiving section 8. 3 are located.

A rack gear 14 is formed below the filter plate 12, and a pinion gear 15 driven by a motor is engaged with the rack gear 14.
In the steady monitoring state, the filter plate 12 is positioned so that the filter 3 is located in front of the light receiving section 8 when the motor is stopped, as shown in the figure. If the light receiving signal from the light receiving section 8 exceeds the threshold value TH in this state, the filter plate 12 on which the rack gear 14 is formed reciprocates due to the rotation of the pinion gear 15 driven by the motor, and the filters 3 and 4 are provided in front of the light receiving section 8. , 5 are sequentially slid.

FIG. 8 shows another embodiment of the optical mechanism used in the infrared fire detecting apparatus according to the present invention, which is characterized by using a scanning optical mechanism. 8, a filter plate 1 driven by a motor 2 is the same as in FIGS. 1 and 2, and an optical system from a monitoring area for the filter plate 1 is a scanning optical system.

First, a rotating mirror 16 that is rotated at a constant speed by a scanning motor 17 is provided. The rotation of the rotating mirror 16 by the scanning motor 17 causes the field of view to be scanned with respect to the monitoring area. The image resulting from this scanning enters the lens 18 as shown by the optical axis of the arrow, is reflected by the mirror 19, and is further reflected by the mirror 19. The light is condensed by the lens 20 and enters the light receiving unit 8 through the filter 3 of the filter plate 1 stopped in the steady monitoring state.

The drive control in such a scanning optical mechanism is such that in a steady monitoring state in which the rotation of the filter plate 1 by the motor 2 is stopped, the light receiving signal from the light receiving unit 8 due to the light transmitted through the filter 3 and entered is a threshold. When the threshold value TH is exceeded, the rotation of the rotating mirror 16 by the scanning motor 17 is stopped, and the energy from the monitoring position where the light receiving level exceeding the threshold value TH is obtained is fixedly incident on the light receiving unit 8. In this state, the motor 2 is rotated to switch the filter, and light receiving signals for three wavelengths are taken in to determine whether a steep peak characteristic peculiar to the disaster is obtained.

As another drive control, when the light receiving signal in the steady monitoring state exceeds the threshold value TH, the scanning motor 17 is not stopped, and the switching of the three filters 3, 4, and 5 by the motor 2 is performed by the rotating mirror 16. The light reception signals for three wavelengths may be obtained by synchronizing with one scan. Further, the rotation speed of the rotating mirror 16 by the scanning motor 17 is sufficiently high, whereas the rotation speed of the filter plate 1 by the motor 2 is increased.
Is rotating very slowly, while the filters 3, 4, and 5 of the filter plate 1 are located in front of the light receiving section 8, the rotation mirror 16 is moved from the flame position by scanning a plurality of times. Energy can be received and the filter plate 1
It is not necessary to synchronize the rotation timing of the rotation mirror 16 with the rotation timing of the rotation mirror 16.

FIG. 9 shows another embodiment of a scanning optical mechanism, which is characterized in that a reflection type filter is provided on a filter plate. The scanning optical system is the same as that of the embodiment shown in FIG. 8, and when the motor 2 is stopped, the reflection type filter 3a provided on the filter plate 1 for reflecting light in the wavelength band λ2 = 4.3 μm is provided by the rotating mirror 16. The light reflected from the lens 18 in the scanning is reflected by a wavelength corresponding to a band around the wavelength λ 1, is condensed by the lens 20, and is incident on the light receiving unit 8.

As for the reflection type filter 3a, the same applies to the other two reflection filters 4a and 5a corresponding to the filters 4 and 5 having the center wavelengths λ1 = 4.0 μm and λ3 = 4.7 μm, though not shown. As described above, in the infrared fire detecting device of the present invention, the motor 2 is stopped in the steady monitoring state, and the filter 3 having the center wavelength λ2 = 4.3 μm is arranged in front of the light receiving section 8 to receive light. Signal is threshold TH
Is monitored, and since there is no motor drive, the current consumption is suppressed to a sufficiently low value as in a normal fire detector.

Incidentally, the center wavelength λ2 =
Unless the infrared light receiving signal of 4.3 μm exceeds the threshold value TH, the motor 2 is not driven, and if the motor 2 is not driven for a long period of time, the motor 2 is started even if the motor is started in some cases. There is a risk that it will not move or will not move smoothly. Therefore, in the fire detection device of the present invention, a periodic inspection function is provided in the amplified signal processing unit 9 or the drive control unit 11 to perform a test operation of rotating the motor 2 for about one minute, for example, once a day. It is desirable.

In the infrared fire detecting device of the present invention, a check light source such as a halogen lamp can be used for the test operation of the detecting device. On the other hand, in the conventional apparatus shown in FIG. 11, since three filters are constantly switched by the motor and the determination is made from all the received light outputs, the wavelength has a peak at 4.3 μm, but a sharp fall occurs on both sides thereof. The test operation cannot be performed with light from a light source such as a halogen lamp having no function.

However, in the fire detection device of the present invention, the filter 3 is located in front of the light receiving section 8 in the steady monitoring state, and only compares the level of the light receiving signal having the center wavelength of 4.3 μm with the threshold value TH. Since there is no spectral characteristic in which both sides fall sharply, a test can be performed up to the switching operation of the filter plate 1 by the drive control unit 11 by irradiating light from a check light source such as a halogen lamp.

Further, in the control processing in the drive control unit 11 of FIG. 5, the flicker frequency of the flame is determined.
When the filter plate 1 is rotated by starting the motor 2 with the light from the check light source being incident, the filter 3
The rotation speed is set to 0.2 rpm (200 msec per rotation) so that the period of one rotation with respect to the incident optical path of the light receiving unit 8 flickers in the range of 1 to 10 Hz, for example, 5 Hz. For this reason, when the filter 3 passes in front of the light receiving unit 8, the change on the time axis of the light receiving signal of the wavelength band λ2 = 4.3 μm falls within the range of the flicker frequency. The function of judging the frequency can also be tested.

In the above-described embodiment, it is determined whether or not a flame is present from the light receiving outputs at three wavelengths of the wavelength band of 4.3 μm where the amount of radiation from the flame has a peak value and two wavelength bands on both sides thereof. However, the wavelength at which the amount of radiation from the flame reaches a peak value is 4.3μ.
If m and the received light output from one or more wavelength bands deviating from this peak wavelength band, the flame judgment processing can be performed. Therefore, the number of the second filters is determined by the number of the wavelength bands.

In the above embodiment, when a light receiving output of a predetermined level or more is obtained with the first filter positioned in the incident path of the light receiving element, a fire judgment is made by sequentially switching the first and second filters. However, when the light receiving output through the first filter is obtained once, the fire determination may be made only by switching to the second filter.

[0048]

As described above, according to the present invention, since the filter drive unit such as the motor is stopped in the steady monitoring state, the current consumption of the detection device is small, and the power supply signal from the receiver or the like is small. An infrared fire detection device can be connected to the line without increasing the power supply capacity on the receiver side, similar to a normal fire detector.

If the light receiving level near 4.3 μm exceeds the threshold value in the steady monitoring state in which the motor stops, the fire is determined based on the light receiving level of each wavelength band by switching the filter by starting the motor. Then, since the motor is stopped, it is extremely unlikely that the motors are simultaneously driven by the detection devices connected to the same line, and a stable operation can be guaranteed with a small current consumption.

Further, the motor for switching the filter is driven only for a certain period of time required for the judgment based on the spectral characteristic peculiar to the flame when the flame is detected, so that the number of failures is small and the life can be greatly extended. Furthermore, a peak wavelength of 4.3 μm
When the level exceeds the threshold value, the flicker frequency is further observed to determine the spectral characteristics unique to the flame by switching the filter, so that infrared energy from sunlight, lighting equipment, and even hot objects such as heating is erroneously detected. A highly reliable fire detection with few false alarms can be performed without being judged as a fire.

Further, the operation test can be performed by turning on a check light source such as a halogen lamp at the time of the test, so that the reliability is high.

[Brief description of the drawings]

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

FIG. 2 is an explanatory view of the filter plate of FIG. 1;

FIG. 3 is an explanatory diagram of a filter band characteristic of the present invention with respect to a spectral characteristic of a flame.

FIG. 4 is a flowchart showing a first embodiment of a control process by a drive control unit in FIG. 1;

FIG. 5 is a flowchart showing a second embodiment of the control processing by the drive control unit in FIG. 1;

FIG. 6 is an explanatory view showing an embodiment of a slider-type filter switching mechanism used in the present invention.

FIG. 7 is an explanatory view showing another embodiment of the slider-type filter switching mechanism used in the present invention.

FIG. 8 is an explanatory view showing an embodiment of a scanning optical mechanism used in the present invention.

FIG. 9 is an explanatory view showing another embodiment of the scanning optical mechanism used in the present invention.

FIG. 10 is an explanatory diagram showing spectral characteristics of a flame in comparison with sunlight and a high-temperature object.

FIG. 11 is an explanatory view of a conventional detection device.

[Explanation of symbols]

 1, 12: filter plate 2: motor 3: filter (first filter: 4.3 μm) 3a: reflective filter 4: filter (second filter: 4.0 μm) 5: filter (second filter: 4.7 μm) 6: Photo interrupter 7: Slit 8: Light receiving section 9: Amplified signal processing section 10: Fire determination section 11: Drive control section 13: Slide actuator 14: Rack gear 15: Pinion gear 16: Rotating mirror 17: Scan motor 18, 20: Lens 19: Mirror

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G08B 17/02-17/12

Claims (5)

(57) [Claims] 1. A light-receiving unit for detecting infrared rays emitted from a flame and converting it into an electric signal, a first filter passing infrared rays in a wavelength band in which the amount of radiation from the flame indicates a peak value, A filter plate including one or more second filters that pass infrared light in a deviated wavelength band, a filter driving unit that selectively positions a filter of the filter plate in an incident optical path of the light receiving unit, and the filter driving unit A fire judging unit for judging a fire from a change in a light receiving signal obtained by the light receiving unit by switching of the filter according to the first aspect of the present invention. If the light receiving signal of the light receiving unit exceeds a predetermined threshold value while the filter driving unit positioned on the incident optical path is stopped, the filter driving unit is activated. An infrared fire detection device, further comprising a drive control unit which operates to switch the filter with respect to an optical path of the light receiving unit and to cause the fire judgment unit to make a fire judgment. 2. The operation test according to claim 1, wherein a check light source such as a halogen lamp is turned on during the test, and light from the check light source is incident on the light receiving section. An infrared fire detection device characterized by having a test section for performing the test. 3. A light-receiving unit for detecting infrared rays emitted from a flame and converting it into an electric signal, a first filter passing infrared rays in a wavelength band in which the amount of radiation from the flame shows a peak value, and A filter plate including one or more second filters that pass infrared light in a deviated wavelength band, a filter driving unit that selectively positions a filter of the filter plate in an incident optical path of the light receiving unit, and the filter driving unit A fire judging unit for judging a fire from a change in a light receiving signal obtained by the light receiving unit by switching of the filter according to the first aspect of the present invention. When the filter driving unit positioned in the incident optical path is stopped, the light receiving signal of the light receiving unit exceeds a predetermined threshold value, and the light receiving signal of the light receiving unit emits a flame. When a unique flicker frequency is detected, a fire judgment is made by the fire judging unit based on a light receiving signal of the light receiving element obtained by activating the filter driving unit and switching the filter with respect to an optical path of the light receiving unit. An infrared fire detection device, comprising a drive control unit for causing the fire detection device to emit light. 4. The infrared fire detector according to claim 3, wherein a check light source such as a halogen lamp is turned on during a test, and light from the check light source is made to enter the light receiving portion through the first filter. In this state, the first filter is set so that the rotation cycle in which the first filter is positioned on the incident path of the light receiving unit is within a range of a flicker frequency peculiar to the flame, and the filter driving unit is controlled so as to rotate the filter plate. An infrared fire detection device characterized by having a test section for performing an operation test. 5. The infrared fire detection device according to claim 1, wherein the drive control unit sends the first filter to the light receiving unit after transmitting a fire detection signal to the outside from the fire determination unit. An infrared fire detection device, wherein the filter driving unit is stopped in a state where the filter driving unit is located in the unit.