JP7715498B2 - Fire detection device, disaster prevention equipment, and fire detection method - Google Patents

Description

The present invention relates to fire detection devices such as smoke detectors that detect fires based on the optical effects of smoke, as well as disaster prevention equipment and fire detection methods.

Conventionally, fire detection devices such as smoke detectors are known that identify the type of smoke by receiving scattered light at different scattering angles and different wavelengths.

For example, by varying the scattering angle of two light-emitting elements relative to the light-receiving element, differences in scattered light depending on the type of smoke are created. At the same time, by varying the wavelength of the light emitted from the two light-emitting elements, differences in scattering characteristics due to wavelength are created. The synergistic effect of these differences in scattering angle and wavelength creates a significant difference in the light intensity of the scattered light depending on the type of smoke, thereby increasing the accuracy of smoke identification and preventing false fire alarms caused by cooking steam, etc., and also making it possible to reliably identify the type of burning material, such as black smoke fires and white smoke fires, when it comes to smoke from fires.

Japanese Patent Application Laid-Open No. 2004-325211 Japanese Patent Application Laid-Open No. 2020-035029 Japanese Patent Application Laid-Open No. 2020-135263

However, while such conventional fire detection devices that distinguish between types of smoke can distinguish between black smoke fires and white smoke fires, there is room for improvement in terms of appropriate fire detection based on the type of smoke. For example, for black smoke fires, which are expected to spread more rapidly than white smoke fires, the devices do not have sufficient performance in terms of quickly detecting them as fires and outputting a fire signal.

The present invention aims to provide a fire detection device, disaster prevention equipment, and fire detection method that enable rapid and appropriate fire detection based on the type of smoke identified.

(Fire detection device)
The present invention provides a fire detection device,
a signal detection means for detecting a signal associated with an optical action of a detection target in a monitoring area by at least a first optical setting and a second optical setting, the signal detection means detecting a first signal obtained by the first optical setting and a second signal obtained by the second optical setting;
an identification means for identifying the type of the detection target or the type of the cause of the detection target based on the first signal and the second signal detected by the signal detection means;
a fire detection means for detecting a fire when a predetermined fire detection condition is satisfied based on at least one of the first signal and the second signal detected by the signal detection means;
Equipped with
The fire detection condition is changed depending on the identification result by the identification means.
It is characterized by:

Here, "identifying the type of detection target based on the first signal and the second signal" refers to, for example, identifying the type by comparing the first signal and the second signal; more specifically, identifying the type based on the magnitude relationship between the first signal and the second signal, or identifying the type based on the ratio between the first signal and the second signal.

(optical settings)
The signal detection means
Using a first optical setting, a detection target in a monitoring area is irradiated with light of a first wavelength, and a light reception signal of scattered light obtained at a first scattering angle is detected as a first signal;
Using the second optical setting, the detection object in the monitoring area is irradiated with light of a second wavelength different from the first wavelength, and a received light signal of scattered light obtained at a second scattering angle different from the first scattering angle is detected as a second signal.

(Identification of detection target)
the identification means identifies a type of detection target as a fire detection target and a non-fire detection target;
The fire detection conditions are:
When a fire detection target is identified by the identification means, the fire detection means is changed so that the fire detection condition is more likely to be detected as a fire than the fire detection condition initially set by the fire detection means,
When the discrimination means discriminates a non-fire detection target, the fire detection means changes the fire detection conditions so that the non-fire detection target is less likely to be detected as a fire than the initially set fire detection conditions .

Here, "fire detection targets" refer to particles and other substances that should be detected as fires in the monitored area, such as smoke generated by a fire. Types of smoke include white smoke and black smoke. White smoke is whitish smoke generated by, for example, the smoldering of wood or cloth, while black smoke is dark smoke generated by, for example, the ignition and burning of an object. Known combustion materials for fires primarily accompanied by white smoke (white smoke fires) include wood and cotton wicks, while known combustion materials for fires primarily accompanied by black smoke (black smoke fires) include kerosene. Furthermore, "non-fire detection targets" refer to particles and other substances that should not be detected as fires, such as oil smoke, steam, vapor, dust, and cigarette smoke, which are generated by factors other than fires (non-fire factors). Factors that generate oil smoke, steam, and steam, which are non-fire detection targets, include cooking, boiling water, and using the bathroom, while dust generation factors include cleaning and sand, and cigarette smoke is generated by smoking.

Here, "making it easier to detect a fire" means, for example, that a fire will be detected under looser (relaxed) conditions, which will result in a fire being detected sooner. Also, "making it harder to detect a fire" means, for example, that a fire will be detected under stricter (strengthened) conditions, which will result in a fire being detected later. In other words, "changing the fire detection conditions" means relaxing the conditions for detecting a fire in the former case, and strengthening the conditions for detecting a fire in the latter case.

(Distinguishing between white and black smoke)
The discrimination means discriminates between white smoke and black smoke as fire detection targets,
The fire detection conditions are:
When white smoke is identified by the identification means, the fire detection means is changed to be more likely to detect a fire than the initial fire detection conditions ,
When the discrimination means discriminates black smoke, the fire detection means changes the fire detection conditions so that the fire is more likely to be detected as a fire than the changed fire detection conditions associated with the discrimination of white smoke.

(Detection of growth rate)
further comprising an increase rate detection means for detecting an increase rate of at least one of the first signal and the second signal;
The fire detection condition is changed based on the identification result by the identification means and the increase rate by the increase rate detection means.

(Change of fire detection conditions according to the rate of increase)
The fire detection conditions are changed so that when the identification means identifies a fire detection target as a type of detection target and the increase rate detected by the increase rate detection means satisfies a predetermined increase rate threshold condition, the fire detection means is more likely to detect a fire than before the change.

(Changes in fire detection conditions)
The fire detection means is
A fire is detected when at least one of the first signal and the second signal satisfies a predetermined threshold condition, or when at least one of the first signal and the second signal satisfies a predetermined accumulation condition in a state where the predetermined threshold condition is satisfied,
The fire detection conditions are:
By making at least one of the threshold conditions and accumulation conditions more lenient than before the change, fires are more likely to be detected than before the change.
By making at least one of the threshold conditions and the accumulation conditions stricter than before the change, it becomes more difficult to detect a fire than before the change.

(First disaster prevention equipment)
The present invention is a disaster prevention system using the above-mentioned fire detection device,
a receiver and a detector that detects a fire and transmits a fire signal to the receiver;
The detector is characterized by comprising a signal detection means, a discrimination means and a fire detection means, or a signal detection means, a discrimination means, a fire detection means and an increase rate detection means .

(Second disaster prevention equipment)
The present invention is a disaster prevention system using the above-mentioned fire detection device,
a receiver and a detector that detects a fire and transmits a fire signal to the receiver;
The sensor comprises a signal detection means;
The receiver is characterized by comprising an identification means and a fire detection means, or an identification means, a fire detection means and an increase rate detection means.

(Fire detection method)
The present invention provides a fire detection method for detecting a fire in a monitored area, comprising:
The signal detection means detects a signal associated with an optical action of a detection target in a monitoring area using at least a first optical setting and a second optical setting, and detects a first signal obtained by the first optical setting and a second signal obtained by the second optical setting;
the discrimination means discriminates between a fire detection target and a non-fire detection target as the type of detection target based on the first signal and the second signal detected by the signal detection means, and discriminates between white smoke and black smoke as the type of fire detection target;
a fire is detected by the fire detection means when a predetermined fire detection condition is satisfied based on at least one of the first signal and the second signal detected by the signal detection means;
Fire detection conditions are:
When the discrimination means discriminates white smoke as a fire detection target, the fire detection means changes the fire detection conditions so that the fire detection conditions are more likely to be detected as a fire than the initially set fire detection conditions,
When the discrimination means discriminates black smoke as a fire detection target, the fire detection means changes the fire detection conditions so that the black smoke is more likely to be detected as a fire than the changed fire detection conditions associated with the discrimination of white smoke;
When the discrimination means discriminates a non-fire detection target, the fire detection means changes the fire detection conditions so that the fire detection condition becomes less likely to be detected as a fire than the initially set fire detection conditions .

(Detection of increase rate and change of fire detection conditions)
1. A fire detection method comprising :
an increase rate detection means for detecting an increase rate of at least one of the first signal and the second signal;
The fire detection conditions are changed based on the identification result by the identification means and the increase rate by the increase rate detection means.

(Effectiveness of fire detection devices)
According to the fire detection device of the present invention, by changing the fire detection conditions according to the type of detection target, such as white smoke, black smoke, or steam, or the type of cause of these detection targets, fires caused by smoke that are more dangerous and have the potential to spread quickly and become large in scale are detected as fires more quickly, while false fire alarms can be reliably prevented for steam and other non-fire-related causes.

(Effect of optical settings)
Furthermore, by irradiating the detection object in the monitoring area with light of a first wavelength and detecting the received light signal of the scattered light obtained at a first scattering angle as a first signal, and then irradiating light of a second wavelength different from the first wavelength and detecting the received light signal of the scattered light obtained at a second scattering angle different from the first scattering angle as a second signal, the synergistic effect of the differences in the scattering characteristics of light of different wavelengths and different scattering angles makes it possible to reliably identify the type of detection object, such as white smoke, black smoke, or steam.

(Effect of identifying the detection target)
Furthermore, when a fire detection target such as white smoke or black smoke is identified, the fire detection conditions are changed to make it easier to detect a fire, enabling prompt fire detection and response. Furthermore, when a non-fire detection target such as steam or dust is identified, the fire detection conditions are changed to make it harder to detect a fire, ensuring the prevention of false fire alarms.

(Effect of distinguishing between white and black smoke)
Furthermore, when white smoke is identified, the fire detection conditions are changed to make it easier to detect a fire than before the change, enabling prompt fire detection and response.On the other hand, when black smoke is identified, the fire detection conditions are changed to make it easier to detect a fire than the changed fire detection conditions associated with white smoke, enabling more rapid detection and response of highly dangerous black smoke fires than white smoke fires.

(Effect of detecting the rate of increase and changing the fire detection conditions according to the rate of increase)
In addition, by changing the fire detection conditions so that a fire is more likely to be detected than before the change, depending on the rate of increase in the signal (at least one of the first signal and the second signal) from the fire detection target in the monitored area due to the action of light, the fire can be detected more quickly, especially for fires that are more likely to become large in scale and in which smoke spreads (rises) quickly.

(Effect of changes in fire detection conditions)
Furthermore, if the fire detection conditions are changed so that fires are more easily detected than before, the specified threshold conditions and/or accumulation conditions can be made more lenient than before, i.e., the fire detection conditions can be changed to increase detection sensitivity, thereby enabling appropriate fire detection for low-risk white smoke fires and high-risk black smoke fires.On the other hand, if the fire detection conditions are changed so that fires are more difficult to detect than before, the fire threshold conditions and/or accumulation conditions can be made stricter than before, i.e., the fire detection conditions can be changed to lower detection sensitivity, thereby reliably preventing false fire alarms caused by steam from cooking or dust from cleaning.

(Effect of the first disaster prevention equipment)
The present invention is a disaster prevention facility that uses the above-mentioned fire detection device, and comprises a receiver and a detector that detects a fire and transmits a fire signal to the receiver. By providing the detector with a signal detection means, an identification means, and a fire detection means, or a signal detection means, an identification means, a fire detection means, and an increase rate detection means, the problem can be addressed by simply changing the detector. Even in the case of existing equipment, the problem can be easily addressed by removing the detector attached to the detector base and replacing it with a detector that is equipped with a signal detection means, an identification means, and a fire detection means, or a detector that is also equipped with an increase rate detection means.

(Effect of the second disaster prevention equipment)
The present invention is a disaster prevention facility that uses the above-mentioned fire detection device, and comprises a receiver and a detector that detects a fire and transmits a fire signal to the receiver, and the detector is provided with a signal detection means, and the receiver is provided with an identification means and a fire detection means, or an identification means, a fire detection means and an increase rate detection means, thereby eliminating the need to modify the detector and allowing the problem to be addressed by modifying only the receiver.

(Effectiveness of fire detection methods)
The present invention, as a fire detection method, can provide the same effects as the above-described fire detection device.

1 is an explanatory diagram showing the basic concept of a fire detection device, a disaster prevention facility, and a fire detection method according to the present invention. 2 is an explanatory diagram of a disaster prevention facility showing a specific embodiment of the present invention targeted at a P-type disaster prevention facility corresponding to FIG. 1. [0023] FIG. FIG. 2 is an explanatory diagram showing a smoke detector unit equipped with a signal detector. This is an explanatory diagram showing in list form the type of detection target based on the first detection value and the second detection value, the cause of occurrence, the identification conditions, changes to fire detection conditions according to the identification results, and changes to fire detection conditions based on the detection of the increase rate. 10 is a time chart showing the characteristics of the change over time in smoke concentration with different increase rates. 3 is a flowchart illustrating a control operation according to an embodiment of the sensor of FIG. 2; FIG. 10 is an explanatory diagram showing another basic concept of the fire detection device, disaster prevention equipment, and fire detection method of the present invention, which detects a fire on the receiver side. 8 is an explanatory diagram of a disaster prevention facility showing a specific embodiment of the present invention targeted at an R-type disaster prevention facility corresponding to FIG. 7. [0023] FIG. 9 is a flowchart showing, in the form of a time chart, a control operation according to the embodiment of the R-type disaster prevention equipment of FIG. 8 .

Embodiments of a fire detection device, disaster prevention equipment, and fire detection method according to the present invention are described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.

[Basic Concept of the Embodiment]
Fig. 1 is an explanatory diagram showing the basic concept of an embodiment of the present invention corresponding to the first disaster prevention equipment, and the basic concept of the embodiment will be described with reference to Fig. 1. This embodiment generally relates to a fire detection device, a first disaster prevention equipment, and a fire detection method. Note that an embodiment corresponding to the second disaster prevention equipment will be described separately.

"Fire detection device" refers to a device that detects fires in a monitored area, and is a concept that includes, for example, smoke detectors, fire detectors, fire alarms, etc.

Here, a "monitored area" refers to an area that is monitored by a fire detection device, and is an outdoor or indoor space with a certain extent, and is a concept that includes spaces such as rooms, corridors, and staircases in a building.

An example of a fire detection device is the detector 12 of a disaster prevention system that is composed of a receiver 10 and a detector 12. The device basically comprises a signal detection unit 16 that functions as a signal detection means, an identification unit 18 that functions as an identification means, and a fire detection unit 20 that functions as a fire detection means, and further comprises an increase rate detection unit 22 that functions as an increase rate detection means.

The "signal detection unit 16" detects signals associated with the optical action of a detection target in the monitoring area using at least a first optical setting and a second optical setting, and detects a first signal obtained using the first optical setting and a second signal obtained using the second optical setting.

Here, "detectable object in the monitoring area" refers to an object that generates a signal due to the action of light, such as an object that generates scattered light when irradiated with light, and is a concept that includes smoke from a fire, steam or vapor from cooking (which are non-fire factors), dust from cleaning, and cigarette smoke from smoking.

The term "first optical setting" encompasses a concept that includes irradiating a detection target in a monitoring area with light of a first wavelength, receiving the scattered light at a first scattering angle, and detecting, as a first signal, a light-receiving signal obtained by such irradiation. The term "second optical setting" encompasses a concept that includes irradiating a detection target in a monitoring area with light of a second wavelength different from the first wavelength, receiving the scattered light at a second scattering angle different from the first scattering angle, and detecting, as a second signal, a light-receiving signal obtained by such irradiation. Using these first and second optical settings, for example, by differentiating the scattering angles of two light-emitting elements relative to the light-receiving elements, differences in scattered light depending on the type of smoke are created. At the same time, by differentiating the wavelengths of light emitted from the two light-emitting elements, differences in scattering characteristics due to wavelength are created, and the synergistic effect of the differences in scattering angles and wavelengths allows the detection of first and second signals that exhibit significant differences in the light intensity of scattered light depending on the type of smoke.

The "identification unit 18" identifies the type of detection target or the type of cause of the detection target based on the first and second signals detected by the signal detection unit 16.

Here, "type of detection target" is a concept that includes white smoke and black smoke, which are fire detection targets, and steam (vapor) and dust, which are non-fire detection targets. Furthermore, "type of cause of detection target" is a concept that includes, for example, white smoke fires, black smoke fires, and non-fires (such as cooking, as mentioned above), which correspond to each detection target.

The "fire detection unit 20" is a unit that detects a fire when a predetermined fire detection condition is met based on at least one of the first and second signals detected by the signal detection unit 16. This concept includes, for example, a unit that detects a fire when at least one of the first and second signals meets a predetermined threshold condition, or when at least one of the first and second signals meets a predetermined threshold condition and then meets a predetermined accumulation condition.

Here, "based on at least one of the first signal and the second signal" refers to, for example, identifying by comparing the first signal and the second signal; more specifically, identifying based on the magnitude relationship between the first signal and the second signal, or identifying based on the ratio between the first signal and the second signal.

Here, "fire detection conditions" refer to conditions for detecting a fire based on at least one of the first and second signals detected by the signal detection unit 16, and are changed depending on the identification results by the identification unit 18.

Furthermore, "changed in accordance with the identification results by the identification unit 18" means that the fire detection conditions are changed in accordance with the type of detection target or the type of cause of the detection target obtained as the identification result.

The change of fire detection conditions in accordance with the identification results of the identification unit 18 is optional. As an example, the identification unit 18 may distinguish between fire detection targets and non-fire detection targets as types of detection targets, and if a fire detection target is identified, the fire detection conditions may be changed to make it easier to detect a fire than before, while if a non-fire detection target is identified, the fire detection conditions may be changed to make it harder to detect a fire than before.

As another example, the fire detection conditions are changed so that when white smoke is identified by the identification unit 18, the fire is more likely to be detected as a fire than before the change, and when black smoke is identified by the identification unit 18, the fire detection conditions are changed so that the fire is more likely to be detected as a fire than the changed fire detection conditions following the identification of white smoke. This concept includes enabling more rapid fire detection of more dangerous black smoke fires than white smoke fires.

Here, "changing to make fires easier to detect than before the change" means changing the fire detection conditions to conditions that are more lenient and increase detection sensitivity. As an example, if at least one of the first signal and the second signal has a specified threshold condition and/or accumulation condition, this includes changing the threshold condition and/or accumulation condition before the change to a more lenient condition (loose condition) so that fires are easier to detect and detection sensitivity is increased.

Furthermore, "changed so that a fire is less likely to be detected than before the change" means changing to conditions that tighten the fire detection conditions and lower the detection sensitivity. As an example, if at least one of the first signal and the second signal has a predetermined threshold condition and/or accumulation condition, this includes tightening the smoke value threshold condition and/or accumulation condition before the change (making them stricter conditions) and lowering the detection sensitivity so that a fire is less likely to be detected.

The "increase rate detection unit 22" detects the increase rate of at least one of the first and second signals detected by the signal detection unit 16. Here, "detecting the increase rate" is a concept that includes detecting the amount of change in the detected value (e.g., smoke concentration) of at least one of the first and second signals per specified unit time.

Furthermore, with the inclusion of the increase rate detection unit 22, the fire detection conditions are changed based on the identification results by the identification unit 18 and the increase rate detected by the increase rate detection unit 22. The change in fire detection conditions in this case is arbitrary, but one example includes a concept in which a fire detection target is identified as the type of detection target, and when the increase rate satisfies a predetermined increase rate threshold condition, the fire detection conditions are changed so that a fire is more likely to be detected than before the change. For example, when white smoke or black smoke, which are fire detection targets, are identified, the initially set fire detection conditions are changed so that a fire is more likely to be detected depending on whether it is white smoke or black smoke. However, when the predetermined increase rate threshold condition is satisfied, the changed fire detection conditions are changed so that a fire is even more likely to be detected. As a result, even for fires with the same white or black smoke, the higher the increase rate of at least one of the first and second signals, for example, the increase rate of the detection value (smoke concentration), the more rapid the fire detection becomes.

In the following description, the "monitoring area" is a "room in a building," the "signal detection unit 16" is a "scattered light type smoke detector that detects a first signal and a second signal using different wavelengths and different scattering angles," the "identification unit 18" is a "unit that identifies the type of detection target or the type of cause of the detection target based on the ratio between the first detection value A1 and the second detection value A2 corresponding to the smoke density of the first signal and the second signal," and the "fire detection unit 20" is a "unit that detects a fire when a predetermined threshold condition for the smoke density is met,"
We will explain the case where the ``increase rate detection unit 22'' ``detects the increase rate α1, α2 of at least one of the first detection value A1 and the second detection value A2'' and the ``change in fire detection conditions'' is ``performed by the fire detection unit 20.''

[Specific Contents of the Embodiment]
The specific contents of the embodiments of the fire detection device, the disaster prevention equipment, and the fire detection method will be described in more detail below.
a. P-type disaster prevention equipment a1. Receiver a2. Detector a3. Signal detection unit a4. Light emission drive and light reception detection a5. Detector control unit a6. Fire detection unit b. Identification of type of detection target and change of fire detection conditions b1. Identification unit b2. Identification of white smoke b3. Identification of black smoke b4. Identification of non-fire detection targets c. Detection of increase rate and change of fire detection conditions c1. Increase rate detection unit c2. Change of fire detection conditions based on increase rate d. Detector control operation e. Basic concept of other embodiments f. R-type disaster prevention equipment f1. Detector f2. Receiver f3. Transmission control f4. Control operation of R-type disaster prevention equipment g. Modified example of the present invention

[a. P-type disaster prevention equipment]
Figure 2 is an explanatory diagram showing a specific embodiment of the present invention targeted at a P-type (Proprietary-type) disaster prevention facility corresponding to Figure 1. Here, the "P-type disaster prevention facility" refers to a facility in which a receiver 10 monitors fires for each signal line (each signal line) to which a detector 12 is connected.

As shown in Figure 2, the P-type disaster prevention equipment of this embodiment comprises a receiver 10 and multiple sensors 12. Note that Figure 2 shows only one sensor 12 as a representative. The receiver 10 is installed in a manager's office, disaster prevention center, etc., and multiple sensors 12 are connected to a signal line 14 that extends from the receiver 10 to a monitored area such as a room in the building. The signal line 14 extended from the receiver 10 comprises a positive signal line 14a and a negative signal line (common signal line) 14b, and supplies power from the receiver 10 to the sensors 12 and transmits a fire alert signal from the sensors 12 to the receiver 10.

(a1. Receiver)
The receiver 10 includes a receiver control unit 40, a line receiving unit 42, a display unit 44, an operation unit 46, an alarm unit 48, and a report transfer unit 50. A line receiving unit 42 is provided for each signal line 14 drawn out in a monitored area, for example, for each floor of a building, and receives a fire alert signal from the detector 12 and outputs it to the receiver control unit 40.

The receiver control unit 40 is composed of a computer circuit equipped with a CPU, memory, and various input/output ports, and performs a fire alarm operation when it detects the reception of a fire alert signal by any of the line receiving units 42. The receiver control unit 40's fire alarm operation activates the fire representative light on the display unit 44 and the district indicator light indicating the district where the fire occurred, outputs a main audible alarm including an alarm voice message from the alarm unit 48, and issues a district audible alarm by activating district sounding devices installed in the monitored area where the fire occurred, and also instructs the reporting unit 50 to perform interlocking control of smoke control and exhaust equipment, etc.

(a2. Sensor)
The configuration of the detector 12 that functions as a fire detection device will be described in more detail below. The detector 12 includes a signal detection unit 16, a detector control unit 24, an alarm circuit unit 26, a power supply unit 28, a light-emitting driver unit 36, and a light-receiving amplifier unit 38.

(a3. Signal detection unit)
The signal detection unit 16 detects a first detection value A1 based on a first signal obtained by irradiating smoke, steam, dust, etc., which are detection targets in the monitored area, with light of a first wavelength λ1 and receiving scattered light obtained at a first scattering angle θ1 using a first optical setting, and a second detection value A2 based on a second signal obtained by irradiating light of a second wavelength λ2, which is different from the first wavelength λ1, with a second optical setting and receiving scattered light obtained at a second scattering angle θ2, which is different from the first scattering angle θ1.The configuration and structure of the signal detection unit 16 are arbitrary, but for example, the first light-emitting element 30, the second light-emitting element 32, and the light-receiving element 34 are arranged in a smoke detection unit, which is a space provided inside the sensor into which outside air flows but which is blocked from outside light.

Figure 3 is an explanatory diagram showing the smoke detection section of the signal detection unit 16, with Figure 3(A) showing the first embodiment and Figure 3(B) showing the second embodiment.

As shown in Figure 3(A), in this embodiment, a first light-emitting element 30, a second light-emitting element 32, and a light-receiving element 34 are arranged within a smoke detection section 31 into which smoke from the outside flows and which is shielded from external light. This embodiment has a planar arrangement structure in which the respective optical axes 30a, 32a, and 34a are arranged in the same plane.

The first light-emitting element 30 is a near-infrared LED, and emits light with a first wavelength λ1 of 600 nm or more, for example, λ1 = 900 nm. Furthermore, the first scattering angle θ1 of the first light-emitting element 30 relative to the intersection P of its optical axis 30a and the optical axis 34a of the light-receiving element 34 is set to a predetermined angle in the range of 20° to 70°, for example, θ1 = 30°.

The second light-emitting element 32 is a visible light LED, and emits light with a center wavelength of 500 nm or less, e.g., λ2 = 500 nm, as light with a second wavelength λ2. The second light-emitting element 32 has a second scattering angle θ2 relative to the intersection P between its optical axis 32a and the optical axis 34a of the light-receiving element 34, which is set to a predetermined angle in the range of 110° to 150°, greater than the first scattering angle θ1 of the first light-emitting element 30 and the light-receiving element 34, e.g., θ2 = 120°.

The light-receiving element 34 uses a photodiode sensitive to light from the infrared region to the visible light region. The first light-emitting element 30 and the second light-emitting element 32 are driven to emit light alternately. When the first light-emitting element 30 emits light of a first wavelength λ1, it irradiates the smoke that has flowed into point P. The scattered light (forward scattered light) from the smoke corresponding to the first scattering angle θ1 is incident on and received by the light-receiving element 34, which outputs a first signal as a light-receiving signal and detects a first detection value A1 corresponding to the smoke concentration.

Furthermore, when light of the second wavelength λ2 is emitted by the second light-emitting element 32 and irradiated onto the smoke that has flowed into point P, the scattered light (backscattered light) from the smoke corresponding to the second scattering angle θ2 is incident on and received by the light-receiving element 34, a second signal is output as a light-receiving signal, and a second detection value A2 corresponding to the smoke concentration is detected.

Here, based on the difference in scattering efficiency, there is a difference between a first detection value A1 of scattered light received at a first scattering angle θ1 = 30° when the same smoke is irradiated with light of a first wavelength λ1 = 900 nm and a first detection value A2 of scattered light received at a second scattering angle θ2 = 120° when the same smoke is irradiated with light of a second wavelength λ2 = 500 nm.
A1>A2
It is known that the relationship

Furthermore, the first detection value A1 and the second detection value A2 will be different depending on the type of smoke that has flowed into the smoke detector 31, for example, white smoke, black smoke, steam, etc., and the type of smoke can be identified by comparing the first detection value A1 and the second detection value A2. The type of smoke can be identified by comparing the first detection value A1 and the second detection value A2 in any manner, but for example, the ratio R of the two can be set as follows:
R = A1/A2
It can be identified by finding

For example, for white smoke (smoldering smoke), which is whitish smoke produced when a cotton wick is burned, the ratio R between the first detection value A1 and the second detection value A2 is, for example, R = 8.0. In contrast, for black smoke (combustion smoke), which is dark smoke produced when kerosene is burned, the ratio R between the first detection value A1 and the second detection value A2 is, for example, R = 2.3.

For this reason, there is a sufficient difference between the ratio R of the first detection value A1 and the second detection value A2 for white smoke (smoldering smoke) and black smoke (combustion smoke). For example, by setting the first discrimination threshold Rth1 for discriminating between the type of smoke for the ratio R to a value in the range of 5 to 6, for example Rth1 = 5, it is possible to discriminate between white smoke if the ratio R is Rth1 or greater, and black smoke if it is less than Rth1.

On the other hand, steam and vapor have particle diameters significantly larger than smoke particles, and therefore their scattering efficiency at small scattering angles is significantly higher than that of smoke during a fire. This means that the first detection value A1 of scattered light at a first scattering angle θ1 = 30° when irradiated with light of the first wavelength λ1 is sufficiently large, and the ratio R of this to the second detection value A2 of scattered light at a second scattering angle θ2 = 120° when irradiated with light of the second wavelength λ2 is large, being 10 or greater.

For this reason, the second discrimination threshold Rth2 for identifying steam and vapor is set to a value in the range of 10 to 12, for example Rth2 = 12, and values above this can be identified as non-fire detection targets such as steam and vapor.

The same is true for cigarette smoke and dust, where a large ratio R of 10 or more is obtained, so when the second discrimination threshold Rth2 is 12 or higher, it can be identified as a non-fire detection target.

Next, a second embodiment of the smoke detector shown in Figure 3(B) will be described. As shown in Figure 3(B), in this embodiment, a light-emitting element 35, a first light-receiving element 34 (34-1), and a second light-receiving element 34 (34-2) are arranged within the smoke detector 31, and this embodiment has a planar arrangement structure in which the respective optical axes 35a, 34-1a, and 34-2a are arranged in the same plane.

The light-emitting element 35 simultaneously emits light including a first wavelength λ1 and a second wavelength λ2. The light of the first wavelength λ1 emitted from the light-emitting element 35 has a central wavelength of 600 nm or more, and the light of the second wavelength λ2 has a central wavelength of 500 nm or less. In this embodiment, the first wavelength λ1 is set to, for example, 700 nm, and the second wavelength λ2 is set to, for example, 450 nm.

The light-emitting element 35 emits light ranging from the infrared region to the visible light region. Its structure and type are arbitrary, but a white LED (white light-emitting diode) is used, for example. A white LED combines, for example, a blue LED with a phosphor. The light from the blue LED passes through the phosphor to emit white light. This emitted light contains light with a first wavelength λ1 = 700 nm and light with a second wavelength λ2 = 450 nm, and light with the first wavelength λ1 and second wavelength λ2 can be simultaneously irradiated into the smoke detection unit 31.

In addition, a two-color LED (two-color light-emitting diode) can also be used as the light-emitting element 35 in this embodiment. The two-color LED has a first light-emitting chip that emits light with a first wavelength λ1 = 700 nm and a second light-emitting chip that emits light with a second wavelength λ2 = 450 nm. By driving both chips simultaneously, light with the first wavelength λ1 and the second wavelength λ2 can be simultaneously irradiated into the smoke detection unit 31.

The first light receiving element 34 (34-1) uses a photodiode (PD) sensitive to the first wavelength λ1, and the second light receiving element 34 (34-2) uses a photodiode (PD) sensitive to the second wavelength λ2.

The first light receiving element 34 (34-1) and the second light receiving element 34 (34-2) may be a wideband photodiode sensitive to the visible light wavelength band, with a filter layer provided on the PD molding (transparent cover member) that receives only the first wavelength λ1 and the second wavelength λ2, respectively, or a filter that transmits the first wavelength λ1 and the second wavelength λ2 may be placed in front of the wideband photodiode.

The first light-receiving element 34 (34-1) has a first scattering angle θ1 relative to the intersection P of its optical axis 34-1a and the optical axis 35a of the light-emitting element 35 set to a predetermined angle in the range of 20° to 70°, for example, θ1 = 30°. When light including a first wavelength λ1 is irradiated from the light-emitting element 35 onto smoke that has flowed into point P, scattered light (forward scattered light) from the smoke corresponding to the first scattering angle θ1 is incident on and received by the first light-receiving element 34 (34-1), which then outputs a first signal as a light-receiving signal and detects a first detection value A1 corresponding to the smoke concentration.

The second light-receiving element 34 (34-2) has a second scattering angle θ2 relative to the intersection P between its optical axis 34-2a and the optical axis 35a of the light-emitting element 35, set to a predetermined angle in the range of 110° to 160°, for example, θ2 = 120°, which is larger than the first scattering angle θ1 of the first light-receiving element 34 (34-1) and the light-emitting element 35. When light containing the second wavelength λ2 is irradiated from the light-emitting element 35 onto the smoke that has flowed into point P, scattered light (backscattered light) from the smoke corresponding to the second scattering angle θ2 is incident on and received by the second light-receiving element 34 (34-2), which then outputs a second signal as a light-receiving signal and detects a second detection value A2 corresponding to the smoke concentration.

In this embodiment, the first detection value A1 of scattered light received at a first scattering angle θ1 = 30° when the same smoke is irradiated with light of a first wavelength λ1 = 700 nm and the first detection value A2 of scattered light received at a second scattering angle θ2 = 120° when the same smoke is irradiated with light of a second wavelength λ2 = 450 nm is also different based on the difference in scattering efficiency.
A1>A2
The first discrimination threshold Rth1 is set to, for example, Rth1=5, and if the first discrimination threshold Rth1 is equal to or greater than Rth1, it can be discriminated as white smoke, and if the first discrimination threshold Rth1 is less than Rth1, it can be discriminated as black smoke.

In addition, for steam, vapor, dust, cigarette smoke, etc., a second discrimination threshold Rth2 is set, for example, at Rth2 = 12, and anything above this can be identified as a non-fire detection target such as steam, vapor, dust, cigarette smoke, etc.

(a4. Light emission drive and light reception detection)
2 is provided with the first embodiment of the smoke detector shown in Fig. 3(A), and is therefore provided with a first light-emitting element 30, a second light-emitting element 32, and a light-receiving element 34. The first light-emitting element 30 and the second light-emitting element 32 are driven to emit light alternately at predetermined intervals by a light-emitting drive unit 36, and the first and second signals as light-receiving signals output sequentially from the first light-emitting element 30 and the second light-emitting element 32 are amplified by a light-receiving amplifier unit 38 and read into the sensor control unit 24, where a first detection value A1 and a second detection value A2 corresponding to the smoke density are detected.

(a5. Sensor control section)
The detector control unit 24 is composed of a computer circuit equipped with a CPU, memory, and various input/output ports, and has the functions of an identification unit 18, a fire detection unit 20, and an increase rate detection unit 22, which are components of the fire detection device of this embodiment, as functions realized by executing a program.

The sensor control unit 24 acquires the first detection value A1 and the second detection value A2 corresponding to the smoke density by reading the signal from the light receiving amplifier unit 38 through A/D conversion synchronized with the timing of the light emission drive of the first light emitting element 30 and the second light emitting element 32. When the fire detection unit 20 detects a fire based on the acquired first detection value A1 and second detection value A2, it activates the alarm circuit unit 26, shorts the positive signal line 14a and the negative signal line 14b to a low impedance, passes a fire alarm current, and transmits a fire alarm signal to the receiver 10.

(a6. Fire detection unit)
The fire detection unit 20 provided as fire detection means in the sensor control unit 24 detects a fire when at least one of the acquired first detection value A1 and second detection value A2 satisfies a predetermined fire detection condition. Here, fire detection based on the first detection value A1 will be described as an example, but the same applies to the case where fire detection is based on both the first detection value A1 and the second detection value A2.

The fire detection conditions of the fire detection unit 20 are arbitrary, but as an example, a fire is detected when the first detection value A1 satisfies a predetermined smoke density threshold condition. Here, the smoke density threshold condition is a condition under which a fire is detected when the first detection value A1 is equal to or greater than a predetermined smoke density threshold Dth0. For example, if the detector 12 is a type 2 sensitivity detector, a fire is detected when the first detection value A1 is equal to or greater than the smoke density threshold Dth0 = 10 (%/m) corresponding to the type 2 sensitivity.

A "Type 2 sensitivity detector" refers to a detector with a legally mandated nominal activation concentration K of 10 (%/m). When tested for activation, the detector activates within 30 seconds when placed in an airflow of 20-40 cm/sec containing smoke at a concentration of (nominal activation concentration K) x 1.5 = 10 (%/m) x 1.5 = 15 (%/m) at a wind speed of 20-40 cm/sec. Furthermore, when tested for deactivation, the detector fails to activate within 5 minutes when placed in an airflow of 20-40 cm/sec containing smoke at a concentration of (nominal activation concentration K) x 0.5 = 10 (%/m) x 0.5 = 5 (%/m), for example, in the case of a non-accumulation detector. In addition to such Type 2 sensitivity detectors with K = 10 (%/m), "Type 1 sensitivity detectors" with a nominal activation concentration K = 5 (%/m) or "Type 3 sensitivity detectors" with a nominal activation sensitivity K = 15 (%/m) are also acceptable.

As another fire detection condition, a fire may be detected when a predetermined smoke density threshold condition is met and a predetermined accumulation condition is also met. For example, if detector 12 is a type 2 sensitivity detector, a fire is detected when the first detection value A1 is equal to or greater than the smoke density threshold Dth0 = 10 (%/m) corresponding to type 2 sensitivity for a predetermined accumulation time T0, for example, T0 = 20 seconds or more.

Such fire detection conditions, such as the smoke density threshold Dth0 and accumulation time T0, are initially set, and in this embodiment, the initially set fire detection conditions, such as the smoke density threshold Dth0 and accumulation time T0, are changed based on the type of smoke being detected.

[b. Identifying the type of detection target and changing the fire detection conditions]
(b1. Identification part)
The identification unit 18 provided as an identification means in the detector control unit 24 identifies the type of detection target or the type of cause of the detection target based on the first detection value A1 and the second detection value A2 obtained from the signal detection unit 16, and accordingly the fire detection unit 20 changes the fire detection conditions based on the identification result of the identification unit 18.

Figure 4 shows an example of the identification of the detection target and changes to the fire detection conditions according to the identification results, along with the increase rate of the detection value and changes to the fire detection conditions.

As shown in Figure 4, the types of detection targets identified by the identification unit 18 are broadly divided into, for example, fire detection targets and non-fire detection targets. Fire detection targets include white smoke and black smoke. Causes of white smoke include white smoke fires, smoldering fires, and the combustion of cotton wicks used in fire tests. Causes of black smoke include black smoke fires, combustion fires, and the combustion of kerosene used in fire tests.

(b2. Identification of white smoke)
The identification unit 18 identifies white smoke when the ratio R = A1/A2 of the first detection value A1 to the second detection value A2 obtained from the signal detection unit 16 is, for example, equal to or greater than a first identification threshold Rth1 = 5 and less than a second identification threshold Rth2 = 12 (Rth1 ≦ R < Rth2). When the identification unit 18 identifies white smoke, the fire detection unit 20 changes the initially set fire detection conditions so that the fire is more likely to be detected as a fire than before the change. Note that the identification unit 18 may also identify the type of fire that causes white smoke, such as a white smoke fire or a smoldering fire.

The initially set fire detection conditions are, for example, a smoke density threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds) corresponding to a Class 2 sensitivity detector. When white smoke is identified, the initially set threshold Dth0 = 10 (%/m) is changed to a first threshold Dth1 = 7.5 (%/m), which makes it easier to detect a fire, and the initially set accumulation time T0 = 20 (seconds) is changed to a first accumulation time T1 = 15 (seconds), which makes it easier to detect a fire.

For this reason, when white smoke is identified, a fire is detected when at least one of the first detection value A1 and second detection value A2 obtained from the signal detection unit 16 reaches the changed first threshold value Dth1 = 7.5 (%/m), for example, allowing for earlier fire detection compared to the pre-change threshold value Dth0 = 10 (%//m).

(b3. Identification of black smoke)
The identification unit 18 identifies the fire as black smoke when the ratio R=A1/A2 of the first detection value A1 to the second detection value A2 obtained from the signal detection unit 16 is smaller than a first identification threshold Rth1=5 (R<5), for example. The identification unit 18 may also identify the type of fire, such as a black smoke fire or a combustion fire, which is a cause of black smoke.

When the identification unit 18 identifies black smoke, the fire detection unit 20 changes the initially set threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds) to modified fire detection conditions associated with the identification of white smoke, such as the first threshold Dth1 = 7.5 (%/m) and first accumulation time T1 = 15 (seconds), which make it easier to detect a fire, such as the second threshold Dth2 = 5.0 (%/m) and second accumulation time T2 = 10 (seconds).

For this reason, when black smoke is identified, a fire is detected when at least one of the first detection value A1 and second detection value A2 obtained from the signal detection unit 16 reaches the changed second threshold value Dth2 = 5.0 (%/m), for example. This allows for earlier detection of a fire compared to the pre-change threshold value Dth0 = 10 (%/m), and further allows for earlier detection of a fire compared to the first threshold value Dth1 = 7.5 (%/m), which is changed when white smoke is identified.

(b4. Identification of non-fire detection targets)
When the ratio R = A1/A2 of the first detection value A1 to the second detection value A2 acquired from the signal detection unit 16 is equal to or greater than a second discrimination threshold Rth2 = 12 (R ≥ 12), the discrimination unit 18 discriminates the detected object as a non-fire detection target, including steam (vapor), dust, cigarette smoke, etc. When the discrimination unit 18 discriminates a non-fire detection target such as steam, the fire detection unit 20 changes the initially set threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds) to a third threshold Dth3 = 15 (%/m) and a third accumulation time T3 = 30 (seconds), which make it less likely to be detected as a fire.

As a result, when a non-fire detection target such as steam is identified, the first detection value A1 and second detection value A2 of the non-fire detection target such as steam obtained from the signal detection unit 16 will not reach the changed third threshold Dth3 = 15 (%/m), ensuring that false fire alarms are prevented.

The values of the threshold values Dth1 to Dth3 and the accumulation times T1 to T3 shown in FIG. 4 are examples.
Dth3>Dth0>Dth1>Dth2
T3>T0>T1>T2
can be any value that satisfies the following relationship:

[c. Detection of Increase Rate and Change of Fire Detection Conditions]
Next, the detection of the increase rate based on at least one of the first detection value A1 and the second detection value A2 acquired from the signal detection unit 16 and the change of the fire detection condition based on the increase rate will be described in detail.

(c1. Increase rate detection unit)
The increase rate detection unit 22 provided as an increase rate detection means in the detector control unit 24 of the detector 12 shown in FIG. 2 detects at least one of the amounts of change ΔD1 and ΔD2 per predetermined unit time, for example, per minute, of the first detection value A1 and the second detection value A2 acquired from the signal detection unit 16 as a first increase rate α1 [(%/m)/sec] and a second increase rate α2 [(%/m)/sec].

The first increase rate α1 of the first detection value A1 and the second increase rate α2 of the second detection value A2, which correspond to the smoke concentration associated with a fire, depend on the smoke diffusion rate (ascent rate) according to the scale of the fire. For example, in a fire involving polyurethane or other materials accompanied by black smoke, the fast combustion rate generates a large amount of smoke, and the first increase rate α1 of the first detection value A1 and the second increase rate α2 of the second detection value A2 detected by the signal detection unit 16 become large.

On the other hand, in a smoldering fire or the like accompanied by white smoke, the combustion rate is slow, resulting in little smoke being generated, and the first increase rate α1 of the first detection value A1 and the second increase rate α2 of the second detection value A2 obtained from the signal detection unit 16 are small. Furthermore, when non-fire detection targets such as smoke or steam associated with cooking or cigarette smoke occur, the first increase rate α1 of the first detection value A1 and the second increase rate α2 of the second detection value A2 obtained from the signal detection unit 16 will exhibit increase rates lower than those of a smoldering fire or the like.

Figure 5 is a time chart showing the temporal change characteristics of smoke density at different linear growth rates over time, using the smoke density corresponding to the first detection value A1 as an example. As shown in Figure 5, characteristic a has the highest growth rate, representing, for example, an explosive oil fire, while characteristic e represents, for example, a smoldering fire in which a futon or other item smolders, with characteristics b to d representing fires of an intermediate scale. Characteristic f represents the occurrence of non-fire detection targets, such as smoke or steam from cooking or cigarette smoke. Note that the growth rate of smoke density in an actual fire is not linear (constant growth rate); as is well known, the growth rate changes randomly over time.

(c2. Changing the fire detection conditions based on the rate of increase)
When the increase rate detection unit 22 detects that at least one of the first increase rate α1 of the first detection value A1 and the second increase rate α2 of the second detection value A2 satisfies a predetermined increase rate threshold condition, for example, when the increase rate is equal to or greater than a predetermined increase rate threshold αth, the fire detection unit 20 changes the fire detection conditions to make it easier to detect a fire than before the change and detects a fire.

Here, the increase rate threshold αth for the smoke concentration increase rate α for changing the fire detection conditions is arbitrary. For example, in Figure 5, the increase rate threshold αth is set to the increase rate of characteristic g, which is approximately halfway between characteristic e due to smoldering fire, which has the lowest increase rate among the fire detection targets, and characteristic f due to smoldering fire.

The fire detection unit 20 changes the fire detection conditions based on the discrimination result between white smoke and black smoke discriminated by the discrimination unit 18 and the increase rate detected by the increase rate detection unit 22. The degree to which the fire detection conditions are changed based on the increase rate differs depending on whether white smoke or black smoke is discriminated.

When the identification unit 18 identifies white smoke, the fire detection unit 20 changes the fire detection conditions based on the detected increase rate so that fires are more likely to be detected than the fire detection conditions changed when white smoke is identified. For example, as shown in FIG. 4, when white smoke is identified and the increase rate (at least one of α1 and α2) is equal to or greater than a predetermined increase rate threshold αth, the pre-change fire detection conditions, which were initially set to a threshold Dth0 = 10 (%/m) and an accumulation time T0 = 20 (seconds), are changed to a fourth threshold Dth4 = 5.0 (%/m) and a fourth accumulation time T4 = 10 (seconds), which are fire detection conditions that make it easier to detect a fire.

The fire detection conditions changed based on this increase rate are conditions that make it even easier to detect a fire than the fire detection conditions changed to identify white smoke, which have a first threshold Dth1 = 7.5 (%/m) and a first accumulation time T1 = 15 (seconds).

Furthermore, when the identification unit 18 identifies black smoke, the fire detection unit 20 changes the fire detection conditions based on the detected increase rate so that fires are more likely to be detected than the fire detection conditions changed when black smoke is identified. For example, as shown in FIG. 4, when black smoke is identified and the increase rate (at least one of α1 and α2) is equal to or greater than a predetermined increase rate threshold αth, the pre-change fire detection conditions, which were the initially set threshold Dth0 = 10 (%/m) and initial accumulation time T0 = 20 (seconds), are changed to the fire detection conditions of a fifth threshold Dth5 = 2.5 (%/m) and a fifth accumulation time T5 = 5 (seconds), so that fires are more likely to be detected.

The fire detection conditions changed based on this increase rate result in a fire that is more likely to be detected than the second threshold Dth2 = 5.0 (%/m) and second accumulation time T2 = 10 (seconds) of the fire detection conditions changed to identify black smoke.

The threshold values Dth1 to Dth5 and the accumulation times T1 to T5 shown in FIG. 4 are examples.
Dth3>Dth0>Dth1>Dth2
Dth1>Dth4
Dth2>Dth5
T3>T0>T1>T25
T1>T4
T2>T5
can be any value that satisfies the following relationship:

[d. Sensor Control Operation]
FIG. 6 is a flow chart showing the control operation according to the embodiment of the detector of FIG. 2, which is the control operation of the detector control unit 24.

As shown in Figure 6, in step S1, the sensor control unit 24 obtains a first detection value A1 and a second detection value A2 corresponding to the smoke density from the first signal and the second signal detected by the signal detection unit 16. Taking the smoke detection unit 31 in Figure 3(A) as an example, the light emission drive unit 36 sequentially drives the first light emitting element 30 and the second light emitting element 32 to emit light at predetermined intervals, and the light receiving element 34 receives scattered light of different wavelengths and scattering angles from smoke, steam, etc. The first and second signals amplified by the light receiving amplifier unit 38 are read in via A/D conversion in synchronization with each emission to obtain the first detection value A1 and the second detection value A2 corresponding to the smoke density.

Next, in step S2, the ratio R = A1/A2 of the first detection value A1 and the second detection value A2 obtained is calculated, and in step S3, at least one of the first increase rate α1 of the first detection value A1 and the second increase rate α2 of the second detection value A2 is detected. Next, in step S4, if the ratio R is equal to or greater than the first discrimination threshold Rth1 = 5 and less than the second discrimination threshold Rth2 = 12, the smoke is identified as white smoke, and the process proceeds to step S5. If in step S5 the increase rate detected in step S3 is less than the increase rate threshold αth, the process proceeds to step S6, where the initially set fire detection conditions of threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds) are changed to first threshold Dth1 = 7.5 (%/m) and first accumulation time T1 = 15 (seconds), which are fire detection conditions based on the white smoke identified in step S4, to make it easier to detect a fire, and the process proceeds to step S14.

In step S14, if at least one of the first detection value A1 and the second detection value A2 obtained in step S1 satisfies the changed fire detection conditions, a fire is detected and the process proceeds to step S15, instructing the alarm circuit unit 26 to send a fire alarm signal, activating the alarm circuit unit 26 and transmitting the fire alarm signal to the receiver 10. Next, in step S16, recovery is determined based on, for example, the interruption of the power supply to the signal line 14 associated with a recovery operation on the receiver 10, and the process returns to the initial detector control in step S1.

On the other hand, in step S5, if the increase rate detected in step S3 is equal to or greater than the predetermined increase rate threshold αth, the process proceeds to step S7, where the pre-change fire detection conditions, which were the initially set threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds), are changed to a fourth threshold Dth4 = 5.0 (%/m) and a fourth accumulation time T4 = 10 (seconds), making it easier to detect a fire, and the process proceeds to step S14, where fire detection processing is performed.

If white smoke is not identified in step S4, proceed to step S8. If the ratio R is less than the first identification threshold Rth1 = 5, black smoke is identified and proceed to step S9. If in step S9 the increase rate detected in step S3 is less than the increase rate threshold αth, proceed to step S10, where the pre-change fire detection conditions, the initially set threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds), are changed to the second threshold Dth2 = 5.0 (%/m) and second accumulation time T2 = 10 (seconds), which are fire detection conditions based on the black smoke identified in step S8, making it easier to detect a fire, and proceed to step S14 to perform fire detection processing.

On the other hand, if step S9 determines that the increase rate detected in step S3 is equal to or greater than the predetermined increase rate threshold αth, the process proceeds to step S11, where the pre-change fire detection conditions, which were the initially set threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds), are changed to a fifth threshold Dth5 = 2.5 (%/m) and a fifth accumulation time T5 = 5 (seconds), making it easier to detect a fire, and the process proceeds to step S14 to perform fire detection processing.

Furthermore, if black smoke is not identified in step S8, proceed to step S12. If the ratio R is equal to or greater than the second identification threshold Rth2 = 12, it is identified as a non-fire detection target such as steam, proceed to step S13, and change the pre-change fire detection conditions, which were the initial threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds), to a third threshold Dth3 = 15 (%/m) and third accumulation time T3 = 30 (seconds), making it less likely to be detected as a fire. Then proceed to step S14 to perform fire detection processing.

Furthermore, if a non-fire detection target such as steam is not identified in step S12, the process proceeds to step S14 to perform fire detection processing while maintaining the initially set fire detection conditions of threshold Dth0 = 10 (%/m) and accumulation time T0 = 20 (seconds).

[e. Other basic concepts of the embodiment]
Figure 7 is an explanatory diagram showing another basic concept of an embodiment corresponding to the second disaster prevention equipment, and is a fire alarm equipment as an example of the second disaster prevention equipment equipped with a receiver 10 and a sensor 12. The sensor 12 is provided with a signal detection unit 16 that functions as a signal detection means of the fire detection device, and the receiver 10 is provided with an identification unit 18 that functions as an identification means of the fire detection device and a fire detection unit 20 that functions as a fire detection means, and further the receiver 10 is provided with an increase rate detection unit 22 that functions as an increase rate detection means.

The signal detection unit 16 provided in the detector 12 and the identification unit 18, fire detection unit 20, and increase rate detection unit 22 provided in the receiver 10 are basically the same as the signal detection unit 16, identification unit 18, fire detection unit 20, and increase rate detection unit 22 provided in the detector 12 in Figure 1. The first detection value A1 and second detection value A2 obtained from the first and second signals detected by the signal detection unit 16 of the detector 12 are transmitted to the receiver 10 via the transmission line 114, and the receiver 10 performs the following functions: identify the type of detection target, detect a fire when the fire detection conditions are met, change the fire detection conditions based on the detection target identification results, and change the fire detection conditions based on the increase rate.

Next, we will explain in more detail the specific contents of the embodiment corresponding to Figure 7.

[f. R-type disaster prevention equipment]
Figure 8 is an explanatory diagram of an R-type (Record-type) disaster prevention system showing specific details of an embodiment corresponding to Figure 7. Here, the "R-type disaster prevention system" is a system that monitors fires for each detector 12 (for each detector) by transmitting data between a receiver 10 and a detector 12.

As shown in Figure 8, the R-type disaster prevention equipment of this embodiment includes a receiver 10 and sensors 12, with multiple sensors 12 connected to a transmission line 114 that extends from the receiver 10 to a monitored area such as a room in a building. The transmission line 114 that extends from the receiver 10 includes a positive transmission line 114a and a negative transmission line (common transmission line) 114b, and supplies power from the receiver 10 to the sensors 12 while transmitting and receiving signals between the receiver 10 and the sensors 12 using a specified transmission method. A dedicated power supply line may also be provided.

(f1.sensor)
2, the detector 12 comprises a signal detection section 16 having a smoke detection structure such as that shown in Fig. 3(A), a detector control section 24, a power supply section 28, a light emission drive section 36, and a light reception amplifier section 38, but differs in that a transmission section 60 is provided to transmit and receive signals to and from the receiver 10 using a predetermined transmission method. Furthermore, the detector control section 24 does not have the functions of the identification section 18, fire detection section 20, and increase rate detection section 22, which are components of the fire detection device of the present invention shown in Fig. 2, and these functions are provided on the receiver 10 side.

(f2. Receiver)
2, the receiver 10 comprises a receiver control unit 40, a display unit 44, an operation unit 46, an alarm unit 48, and a report transfer unit 50, but differs in that a transmission unit 62 is provided to transmit and receive signals to and from the detector 12 using a predetermined transmission method, and in that the receiver control unit 40 is provided with the functions of an identification unit 18, a fire detection unit 20, and an increase rate detection unit 22, which are components of the fire detection device of the present invention, as functions realized by executing a program. The identification unit 18, fire detection unit 20, and increase rate detection unit 22 provided in the receiver 10 are basically the same as those provided in the detector 12 in the embodiment of FIG. 2.

(f3. Transmission Control)
In the R-type disaster prevention equipment, a unique address is assigned to the detectors 12, and the receiver 10 transmits a batch A/D conversion command signal at a predetermined cycle, for example, every minute. All detectors 12 that receive the batch A/D conversion command signal A/D convert and store (store) the first detection value A1 and the second detection value A2 corresponding to the first signal and the second signal obtained by receiving scattered light of different wavelengths and different scattering angles in their signal detection units 16. The receiver 10 then transmits a call signal sequentially specifying the detector addresses, thereby performing polling to have each detector 12 return a response signal including the first detection value A1 and the second detection value A2.

When the first detection value A1 or the second detection value A2 corresponding to the smoke density reaches a predetermined fire warning level (preliminary fire detection level), for example 1 (%/m), the detector 12 detects a fire warning and sends a fire interrupt signal to the receiver 10.

When the receiver 10 receives a fire interrupt signal from a detector 12, it transmits a group search command signal specifying a group address, performs a group search to identify the group address to which the detector 12 that responded with the fire interrupt signal belongs, and then transmits an intra-group search command signal specifying the detector addresses within the searched group address in sequence, to identify the addresses of the detectors 12 that responded with the fire interrupt signal, i.e., the addresses of the detectors 12 that detected a fire precursor.

The receiver 10 then transmits an A/D conversion command signal and a call signal specifying the address of the detector 12 that detected a fire precursor at a predetermined cycle that is shorter than normal. The receiver 10 then intensively acquires the first detection value A1 and the second detection value A2 from the detector 12 that detected a fire precursor, and controls the detection of a fire using the identification unit 18, fire detection unit 20, and increase rate detection unit 22 provided in the receiver control unit 40. Note that the transmission control between the receiver 10 and the detector 12 is an example, and any known transmission control can be applied.

(f4. Control operation of R-type disaster prevention equipment)
FIG. 9 is a flowchart showing the control operation of the embodiment of the R-type disaster prevention equipment of FIG. 8 in the form of a time chart.

As shown in FIG. 9, in step S21, the receiver 10 performs a fire monitoring transmission process by transmitting a batch A/D conversion command signal at a predetermined interval, for example, one minute, followed by a call signal specifying the detector address and receiving a response signal from the detector 12. Meanwhile, in step S22, the detector 12 performs a fire monitoring response process by receiving the batch A/D conversion command signal from the receiver 10, storing and retaining the first detection value A1 and second detection value A2 obtained at that time, and then transmitting a response signal including the first detection value A1 and second detection value A2 when it receives a call signal specifying its own address.

Next, if the detector 12 determines in step S23 that the smoke density of the acquired first detection value A1 or second detection value A2 has reached a predetermined fire precursor level, for example, 1 (%/m), it proceeds to step S24 and transmits a fire interrupt signal to the receiver 10 as a fire precursor transmission process. In step S25, the receiver 10 performs a fire precursor reception process by searching for and identifying the address of the detector that transmitted the fire interrupt signal based on the fire interrupt signal received from the detector 12.

In step S26, the receiver 10 determines whether a fire interrupt signal has been received from the detector 12. If a fire interrupt signal has not been received, the process returns to step S21. If a fire interrupt signal has been received, the process proceeds to step S27 below. On the other hand, if a fire interrupt signal has been transmitted, the process proceeds to step S27.

In step S27, the receiver 10 receives the detection values A1 and A2 by repeatedly transmitting, at short intervals, a batch A/D conversion command signal and a call signal specifying the address of the detector 12 that transmitted the fire interrupt signal. In step S28, the receiver 10 causes the detector 12 to transmit the detection values A1 and A2, and intensively receives the first detection value A1 and the second detection value A2 from the detector 12 that detected a fire precursor.

The receiver 10 then proceeds to step S29, where it calculates the ratio R = A1/A2 based on the acquired first detection value A1 and second detection value A2, and detects the rate of increase of at least one of the first detection value A1 and second detection value A2 using the increase rate detection unit 22. Then, in step S30, the identification unit 18 identifies the type of detection target, such as white smoke, black smoke, or steam, based on the ratio R, and changes the fire detection conditions based on the identification results. These changes to the fire detection conditions are, for example, the same as those shown in the list in Figure 4.

The receiver 10 then proceeds to step S31 and changes the fire detection conditions based on the detected rate of increase. This change in fire detection conditions based on the rate of increase is, for example, the same as the list shown in Figure 4. The receiver 10 then proceeds to step S32, and if it determines that at least one of the first detection value A1 and the second detection value A2 satisfies the initially set fire detection conditions or the changed fire detection conditions, it detects a fire and proceeds to step S33, where it performs fire alarm processing, including sounding the main acoustic alarm and district acoustic alarm, displaying the location of the fire based on the address of the detector that detected the fire, and interlocking control of smoke control equipment.

Next, if the receiver 10 determines in step S34 that recovery has occurred due to a recovery operation following the extinguishing of the fire, it sends a recovery signal to the detector 12 in step S35 and returns to the fire monitoring transmission processing in step S21. Furthermore, if the detector 12 determines in step S36 that it has received a recovery signal, it returns to the fire monitoring response processing in step S22.

[g. Modifications of the present invention]
An alternative embodiment of the present invention will now be described in more detail.

(Fire detection device)
The fire detection device of the above embodiment is exemplified as being equipped with a signal detection unit 16, an identification unit 18, a fire detection unit 20, and an amplification factor detection unit 22, but is not limited to this and includes a fire detection device whose basic configuration is the signal detection unit 16, the identification unit 18, and the fire detection unit 20 excluding the amplification factor detection unit 22.

(fire alarm)
The above embodiment takes as an example the configuration of a fire detection device for disaster prevention equipment equipped with a receiver and a sensor, but the fire detection device may also be configured as, for example, a residential fire alarm equipped with a means for detecting a fire from smoke density and a means for issuing a fire alarm. In the case of a fire alarm, the fire alarm will be provided with the functions of the signal detection unit 16, the identification unit 18, the fire detection unit 20, and the increase rate detection unit 22 that constitute the fire detection device, similar to the sensor 12 of the disaster prevention equipment shown in Figures 1 and 2.

(Fire detection conditions)
In the fire detection device of the above embodiment, the fire detection unit 20 changes the fire detection conditions in accordance with the identification result by the identification unit 18, but this is not limited to this, and for example, the identification unit 18 may change the fire detection conditions in accordance with the identification result, and the fire detection unit 20 may detect a fire under the changed fire detection conditions. The same applies when the fire detection conditions are changed based on the increase rate detected by the increase rate detection unit 22.

(others)
Furthermore, the present invention includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to the numerical values shown in the above embodiments.

10: Receiver 12: Detector 14: Signal line 16: Signal detection unit 18: Identification unit 20: Fire detection unit 22: Increase rate detection unit 24: Detector control unit 26: Alarm circuit unit 28: Power supply unit 30: First light-emitting element 32: Second light-emitting element 34: Light-receiving element 34 (34-1): First light-receiving element 34 (34-2): Second light-receiving element 35: Light-emitting element 36: Light-emitting driver unit 38: Light-receiving amplifier unit 40: Receiver control unit 42: Line receiving unit 44: Display unit 46: Operation unit 48: Alarm unit 50: Reporting unit 60, 62: Transmission unit 114: Transmission line

Claims (11)

a signal detection means for detecting a signal associated with an optical action of a detection target in a monitoring area by at least a first optical setting and a second optical setting, the signal detection means detecting a first signal obtained by the first optical setting and a second signal obtained by the second optical setting;
a discrimination means for discriminating between a fire detection target and a non-fire detection target as the type of the detection target based on the first signal and the second signal detected by the signal detection means, and for discriminating between white smoke and black smoke as the type of the fire detection target;
a fire detection means for detecting a fire when a predetermined fire detection condition is satisfied based on at least one of the first signal and the second signal detected by the signal detection means;
Equipped with
The fire detection condition is:
When the discrimination means discriminates the white smoke as the fire detection target, the fire detection conditions are changed so that the fire detection conditions are more likely to be detected as a fire than the initially set fire detection conditions of the fire detection means,
When the discrimination means discriminates the black smoke as the fire detection target, the fire detection means changes the fire detection conditions so that the black smoke is more likely to be detected as a fire than the fire detection conditions after the change associated with the discrimination of the white smoke,
A fire detection device characterized in that, when the identification means identifies a non-fire detection target, the fire detection conditions initially set in the fire detection means are changed to make it less likely to be detected as a fire.
2. The fire detection device according to claim 1,
The signal detection means
Using the first optical setting, a detection target in the monitoring area is irradiated with light of a first wavelength, and a light receiving signal of scattered light obtained at a first scattering angle is detected as the first signal;
A fire detection device characterized in that, using the second optical setting, light of a second wavelength different from the first wavelength is irradiated onto the detection object in the monitoring area, and the received signal of scattered light obtained at a second scattering angle different from the first scattering angle is detected as the second signal.
3. The fire detection device according to claim 1 or 2,
an increase rate detection means for detecting an increase rate of at least one of the first signal and the second signal;
The fire detection device is characterized in that the fire detection conditions are changed based on the identification result by the identification means and the increase rate by the increase rate detection means.
4. The fire detection device according to claim 3,
A fire detection device characterized in that the fire detection conditions are changed so that the fire detection means is more likely to detect a fire than before the change when the identification means identifies a fire detection target as the type of detection target and the increase rate detected by the increase rate detection means satisfies a predetermined increase rate threshold condition.
5. The fire detection device according to claim 1,
The fire detection means
A fire is detected when at least one of the first signal and the second signal satisfies a predetermined threshold condition, or when at least one of the first signal and the second signal satisfies a predetermined accumulation condition in a state where the predetermined threshold condition is satisfied,
The fire detection condition is:
By making at least one of the threshold condition and the accumulation condition more lenient than before the change, it becomes easier to detect a fire than before the change,
A fire detection device characterized in that at least one of the threshold condition and the accumulation condition is made stricter than before the change, making it more difficult to detect a fire than before the change.
a signal detection means for detecting a signal associated with an optical action of a detection target in a monitoring area by at least a first optical setting and a second optical setting, the signal detection means detecting a first signal obtained by the first optical setting and a second signal obtained by the second optical setting;
a discrimination means for discriminating between a fire detection target and a non-fire detection target as the type of the detection target based on the first signal and the second signal detected by the signal detection means, and for discriminating between white smoke and black smoke as the type of the fire detection target;
a fire detection means for detecting a fire when a predetermined fire detection condition is satisfied based on at least one of the first signal and the second signal detected by the signal detection means;
Equipped with
The fire detection condition is:
When the discrimination means discriminates the white smoke as the fire detection target, the fire detection conditions are changed so that the fire detection conditions are more likely to be detected as a fire than the initially set fire detection conditions of the fire detection means,
When the discrimination means discriminates the black smoke as the fire detection target, the fire detection means changes the fire detection conditions so that the black smoke is more likely to be detected as a fire than the fire detection conditions after the change associated with the discrimination of the white smoke,
This disaster prevention equipment is characterized in that, when the identification means identifies a non-fire detection target, the fire detection conditions are changed so that the non-fire detection target is less likely to be detected as a fire than the fire detection conditions initially set in the fire detection means.
The disaster prevention equipment according to claim 6,
an increase rate detection means for detecting an increase rate of at least one of the first signal and the second signal;
The fire detection condition is changed based on the identification result by the identification means and the increase rate detected by the increase rate detection means.
The disaster prevention equipment according to claim 7 ,
a receiver and a detector that detects a fire and transmits a fire signal to the receiver;
The detector is characterized in that it is equipped with the signal detection means, the identification means, and the fire detection means, or the signal detection means, the identification means, the fire detection means, and the increase rate detection means.
The disaster prevention equipment according to claim 7 ,
a receiver and a detector that detects a fire and transmits a fire signal to the receiver;
The sensor comprises the signal detection means,
The disaster prevention equipment is characterized in that the receiver is equipped with the identification means and the fire detection means, or the identification means, the fire detection means and the increase rate detection means.
1. A fire detection method for detecting a fire in a monitored area, comprising:
a signal detection means for detecting a signal associated with an optical action of a detection target in the monitoring area by at least a first optical setting and a second optical setting, and detecting a first signal obtained by the first optical setting and a second signal obtained by the second optical setting;
an identification means for identifying the type of detection target as a fire detection target or a non-fire detection target based on the first signal and the second signal detected by the signal detection means, and for identifying the type of fire detection target as white smoke or black smoke;
a fire detection means for detecting a fire when a predetermined fire detection condition is satisfied based on at least one of the first signal and the second signal detected by the signal detection means;
The fire detection condition is
When the discrimination means discriminates the white smoke as the fire detection target, the fire detection means changes the fire detection conditions so that the fire detection conditions are more likely to be detected as a fire than the initially set fire detection conditions,
When the discrimination means discriminates the black smoke as the fire detection target, the fire detection means changes the fire detection conditions so that the black smoke is more likely to be detected as a fire than the fire detection conditions after the change associated with the discrimination of the white smoke,
A fire detection method characterized in that, when the identification means identifies a non-fire detection target, the fire detection conditions initially set in the fire detection means are changed so that the non-fire detection target is less likely to be detected as a fire.
11. The fire detection method according to claim 10 ,
an increase rate detection means for detecting an increase rate of at least one of the first signal and the second signal;
A fire detection method, characterized in that the fire detection conditions are changed based on the identification result by the identification means and the increase rate by the increase rate detection means.