JP7728089B2 - 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 caused by leaks of flammable gases used in semiconductor manufacturing, as well as disaster prevention equipment and fire detection methods.

Conventionally, certain gases used in semiconductor manufacturing and compounds used as raw materials in the chemical industry are toxic and highly flammable, and many of the combustion products are toxic. For example, gases such as silane gas used as a doping gas in semiconductor manufacturing and phosphine gas used as an epitaxial gas can spontaneously ignite and burn explosively if they leak outside and come into contact with air, producing silicon oxide (SiO2 ₎ in the case of silane gas.

Smoke detectors are widely used to detect fires caused by gases and chemical materials. Smoke detectors detect the presence of combustion products by irradiating light from a light-emitting element onto the fine particles of combustion products that have flowed into the smoke-detecting section of the detector, and then capturing the light scattered by the fine particles with a light-receiving element.

Furthermore, fire detection devices such as smoke detectors that identify types of smoke by receiving scattered light with different scattering angles and different wavelengths are known. 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 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 scattered light depending on the type of smoke, increasing the accuracy of smoke identification and preventing false fire alarms caused by cooking steam, etc. It also makes it possible to distinguish between types of smoke caused by fire, such as black smoke and white smoke, which correspond to the burning material.

Furthermore, a known fire detection device for detecting flames uses a sensor such as a pyroelectric element to convert infrared rays in the 4.5 μm band emitted in conjunction with _CO2 resonance of a combustion flame into an electrical signal, and then extracts the flickering frequency component specific to flames from this electrical signal to determine whether or not a flame is present.

Japanese Patent Application Laid-Open No. 2004-325211 Japanese Patent Application Laid-Open No. 2020-035029 Japanese Patent Application Laid-Open No. 2020-135263 Patent No. 4014188 Patent No. 4404329

However, conventional smoke detectors cannot distinguish between the products of combustion caused by leaking and burning gases used in semiconductor manufacturing and the products of combustion caused by ordinary fires, known as general fires, oil fires, or electrical fires, which occur when ordinary machinery or structures burn due to accidental fires.

Furthermore, even with conventional fire detection devices that detect flames, even if a fire occurs due to a leak of gas used in semiconductor manufacturing, unlike fires caused by normal carbon-containing substances, _CO2 , which emits infrared rays in the 4.5 μm band associated with _CO2 resonance, is not produced during combustion, and there is a high possibility that the gas leak fire will not be detected.

On the other hand, if semiconductor manufacturing gases such as silane gas or phosphine gas burn, extinguishing the fire with water should never be done to prevent the release of toxic gases. Similarly, extinguishing with halon fire extinguishing gas is also considered inappropriate, and the use of carbon dioxide or dry chemical fire extinguishing agents is required. However, if the fire is in a machine or structure, it can be extinguished with water as a normal fire, and there is no problem with extinguishing with halon fire extinguishing agents.

In other words, in semiconductor manufacturing, it is necessary to correctly identify the combustible material in a fire and use the appropriate extinguishing agent, and for this reason, there is a demand for fire detection devices that can identify combustible materials such as silane gas and phosphine gas.

The present invention aims to provide a fire detection device, disaster prevention equipment, and fire detection method that can identify gas fires used in semiconductor manufacturing, such as silane gas, and prevent the fire from spreading, suppress it, or extinguish it.

(Fire detection device 1)
The present invention is characterized by a fire detection device that detects smoke-generating fires that produce smoke and predetermined gas fires that produce monodisperse particles, and distinguishes between the types of fire.

Here, "monodisperse particles" refers to particles with a uniform size distribution, and is a concept that includes monodisperse combustion products. For example, it refers to particles where the standard deviation of the size distribution divided by the average size is small, for example, 0.1 or less.

(Fire alarm including identification results)
If it is determined that the fire is a smoke fire or a specified gas fire, the determination result is output along with the fire.

(Control according to the identification result)
A disaster prevention facility using the fire detection device described above,
Control for preventing the spread of the fire, suppressing it, or extinguishing it is varied depending on the identification result of the fire detection device.

(Gas fire in semiconductor manufacturing)
In addition, if the fire detection device identifies a semiconductor manufacturing gas fire, the disaster prevention equipment will control the supply of semiconductor gas to be stopped and/or release inert gas into the area where the fire has occurred.

(Fire detection device 2)
The present invention provides a fire detection device for detecting a fire in a monitored area, comprising:
a signal detection unit that irradiates light onto a detection target in a monitoring area that involves optical action and detects a plurality of detection signals received at different scattering angles;
an identification unit that identifies whether the fire is a smoke-generating fire that generates smoke or a semiconductor manufacturing gas fire that generates monodisperse particles based on the plurality of detection signals detected by the signal detection unit;
a detection output unit that outputs the fire and the identification result to the outside when any of the plurality of detection signals satisfies a predetermined fire detection condition in a state where the identification unit has identified the fire as a smoke fire or a semiconductor manufacturing gas fire;
The present invention is characterized by the following features.

(Gas for semiconductor manufacturing)
The semiconductor manufacturing gas is silane gas or phosphine gas.

In the following explanation, a method of irradiating a detection object with light of a predetermined wavelength and detecting three detection signals received at three different scattering angles will be referred to as the "one wavelength, three scattering angle method," a method of irradiating a detection object with light of a predetermined wavelength and detecting two detection signals received at two different scattering angles will be referred to as the "one wavelength, two scattering angle method," and a method of irradiating a detection object with light of two different wavelengths and detecting two detection signals received at two different scattering angles will be referred to as the "two wavelength, two scattering angle method."

(One wavelength, three scattering angles method: Identification and detection of gas fires in semiconductor manufacturing)
the signal detection unit detects a signal associated with an optical action of the detection object by at least a first optical setting, a second optical setting, and a third optical setting;
As a first optical setting, a detection target is irradiated with light of a predetermined wavelength, and a light reception signal of scattered light obtained at a predetermined forward scattering angle smaller than 90° is detected as a forward scattering detection signal;
As a second optical setting, a detection target is irradiated with light of a predetermined wavelength, and a light reception signal of scattered light obtained at a predetermined backscattering angle greater than 90° is detected as a backscattering detection signal;
As a third optical setting, a detection target is irradiated with light of a predetermined wavelength, and a light receiving signal of scattered light obtained at a scattering angle of 90° is detected as a 90° scattering detection signal;
the identification unit identifies a semiconductor manufacturing gas fire when a predetermined identification condition corresponding to Rayleigh scattering in which the 90° scattering detection signal has a minimum value is satisfied based on the forward scattering detection signal, the backward scattering detection signal, and the 90° scattering detection signal detected by the signal detection unit;
When the identification unit has identified a semiconductor manufacturing gas fire, and predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs the identification result that the fire is a semiconductor manufacturing gas fire to the outside along with the fire.

(One wavelength, three scattering angles method: discrimination and detection of smoke-emitting fires)
the identification unit identifies a smoke-generating fire when a predetermined identification condition corresponding to Rayleigh scattering, in which the 90° scattering detection signal has a minimum value, is not satisfied based on the forward scattering detection signal, the backward scattering detection signal, and the 90° scattering detection signal detected by the signal detection unit;
When the identification unit has identified a smoke-generating fire, and other specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs the identification result that the fire is a smoke-generating fire to the outside along with the fire.

As is well known, "Rayleigh scattering" is the scattering of light by particles smaller than the wavelength of light, where the scattering intensity (amount of scattered light) is distributed approximately the same in the forward and backward directions and is at its minimum at a scattering angle of 90°. On the other hand, "Mie scattering" is known as the scattering of light by particles larger than the wavelength of light, where the scattering intensity of light is greater in the forward direction than in the backward direction.

Smoke particles, primarily composed of carbon oxides and water, are generated by smoke-generating fires, including general fires, oil fires, and electrical fires. They vary widely in size, ranging from 0.001 μm to several μm (1 nm to several thousand nm). Particles larger than the wavelength of the light irradiating the target undergo Mie scattering, while particles smaller than the wavelength of light undergo Rayleigh scattering, resulting in a combined scattering of both.

In contrast, gases that ignite when leaked into the atmosphere, such as particles of combustion products (silicon oxide) of silane gas, a gas used in semiconductor manufacturing, are monodisperse particles, with extremely small particle sizes (particle diameters) of approximately 0.05 μm to 0.06 μm (50 nm to 60 nm), which are smaller than the wavelength of the light irradiated onto the detection target, resulting in Rayleigh scattering. Therefore, when specific identification conditions corresponding to Rayleigh scattering are met, it is possible to identify a fire caused by a semiconductor manufacturing gas such as silane gas.

(1 wavelength, 3 scattering angles method, 1 LED + 3 PD)
The signal detection unit
a light emitting unit that irradiates a detection target with light of a predetermined wavelength;
a first light receiving unit that receives scattered light obtained at a forward scattering angle when light of a predetermined wavelength is irradiated onto a detection target and outputs a forward scattering detection signal;
a second light receiving unit that receives scattered light obtained at a backscattering angle when light of a predetermined wavelength is irradiated onto the detection target and outputs a backscattering detection signal;
a third light receiving unit that receives scattered light obtained at a scattering angle of 90° when light of a predetermined wavelength is irradiated onto the detection object and outputs a 90° scattering detection signal;
Equipped with.

(Second smoke detector structure: 3 LEDs + 1 PD, 1 wavelength, 3 scattering angles)
The signal detection unit
a light receiving unit that receives scattered light of a predetermined wavelength irradiated onto a detection target and outputs a scattered light detection signal, a backscattered light detection signal, or a 90° scattered light detection signal;
a first light emitting unit that irradiates a detection target with light of a predetermined wavelength so that scattered light at a forward scattering angle is incident on a light receiving unit and a forward scattering detection signal is output;
a second light emitting unit that irradiates the detection target with light of a predetermined wavelength so that scattered light at a backscattering angle is incident on the light receiving unit and a backscattering detection signal is output;
a third light emitting unit that irradiates the detection target with light of a predetermined wavelength so that scattered light having a scattering angle of 90° is incident on the light receiving unit and a 90° scattering detection signal is output;
Equipped with.

(One wavelength, two scattering angles method: gas leak fire identification and detection)
The signal detection unit detects a signal associated with an optical action of the detection target using at least a first optical setting and a second optical setting,
As a first optical setting, a detection target is irradiated with light of a predetermined wavelength, and a light reception signal of scattered light obtained at a predetermined forward scattering angle smaller than 90° is detected as forward scattered light, or a light reception signal of scattered light obtained at a predetermined backward scattering angle larger than 90° is detected as a backward scattering detection signal;
As a second optical setting, a detection object is irradiated with light of a predetermined wavelength, and a light receiving signal of scattered light obtained at a scattering angle of 90° is detected as a 90° scattering detection signal;
the identification unit identifies a semiconductor manufacturing gas fire when the ratio of the forward scattering detection signal to the 90° scattering detection signal or the ratio of the backscattered light to the 90° scattering detection signal satisfies a predetermined identification condition corresponding to Rayleigh scattering;
When the identification unit has identified a semiconductor manufacturing gas fire and predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs the identification result that the fire is a semiconductor manufacturing gas fire to the outside along with the fire.

(One wavelength, two scattering angles method: discrimination and detection of smoke-emitting fires)
the identification unit identifies a smoke-generating fire when the ratio of the forward scattering detection signal to the 90° scattering detection signal or the ratio of the backscattered light to the 90° scattering detection signal satisfies a predetermined identification condition corresponding to smoke;
When the identification unit has identified a smoke-generating fire and other specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs the identification result that the fire is a smoke-generating fire to the outside along with the fire.

(One wavelength, three scattering angles method and one wavelength, two scattering angles method: distinguishing between white smoke fires and black smoke fires)
the identification unit identifies a white smoke fire when the ratio of the forward scattered light detection signal to the 90° scattered light detection signal or the ratio of the back scattered light to the 90° scattered light detection signal satisfies a predetermined identification condition corresponding to white smoke, and identifies a black smoke fire when the ratio satisfies a predetermined identification condition corresponding to black smoke;
When the identification unit has identified a white smoke fire and other predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs to the outside the identification result that the fire is a white smoke fire along with the fire, and when the identification unit has identified a black smoke fire and other predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs to the outside the identification result that the fire is a black smoke fire along with the fire.

(1 wavelength 2 scattering method first smoke detector structure: 1 LED + 2 PD)
The signal detection unit
a light emitting unit that irradiates a detection target with light of a predetermined wavelength;
a first light receiving unit that receives scattered light obtained at a forward scattering angle when a detection target is irradiated with light of a predetermined wavelength and outputs a forward scattering detection signal, or a second light receiving unit that receives scattered light obtained at a backward scattering angle when a detection target is irradiated with light of a predetermined wavelength and outputs a backward scattering detection signal;
a third light receiving unit that receives scattered light obtained at a scattering angle of 90° when light of a predetermined wavelength is irradiated onto the detection object and outputs a 90° scattering detection signal;
A place equipped with.

(Second smoke detector structure with one wavelength and two scattering methods: 2 LEDs + 1 PD)
The signal detection unit
a light receiving unit that receives scattered light of a predetermined wavelength irradiated onto a detection target and outputs a forward scattering detection signal and a 90° scattering detection signal, or a backward scattering detection signal and a 90° scattering detection signal;
a first light-emitting unit that irradiates a detection target with light of a predetermined wavelength so that scattered light at a forward scattering angle is incident on the light-receiving unit and a forward scattering detection signal is output, or a second light-emitting unit that irradiates a detection target with light of the predetermined wavelength so that scattered light at a backward scattering angle is incident on the light-receiving unit and a backward scattering detection signal is output;
a third light emitting unit that irradiates the detection target with light of a predetermined wavelength so that scattered light having a scattering angle of 90° is incident on the light receiving unit and a 90° scattering detection signal is output;
A place equipped with.

(Two wavelengths, two scattering method: identification and detection of gas combustion products)
The signal detection unit detects a signal associated with an optical action of the detection target using at least a first optical setting and a second optical setting,
As a first optical setting, a detection target is irradiated with light of a predetermined first wavelength, and a light reception signal of scattered light obtained at a predetermined forward scattering angle is detected as a forward scattering detection signal;
As a second optical setting, the detection object is irradiated with light of a predetermined second wavelength different from the first wavelength, and a light reception signal of scattered light obtained at a predetermined backscattering angle is detected as a backscattering detection signal;
the identification unit identifies a semiconductor manufacturing gas fire when a ratio between a multiplication value of the first wavelength and the forward scattering detection signal and a multiplication value of the second wavelength and the back scattering detection signal satisfies a predetermined identification condition corresponding to Rayleigh scattering;
When the identification unit has identified a semiconductor manufacturing gas fire and predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs the identification result that the fire is a semiconductor manufacturing gas fire to the outside along with the fire.

(2 wavelengths, 2 scattering angles method: normal fire identification and detection)
the identification unit identifies a smoke-generating fire when a ratio between a multiplication value of the first wavelength and the forward scattering detection signal and a multiplication value of the second wavelength and the back scattering detection signal satisfies a predetermined identification condition corresponding to smoke;
When the identification unit has identified a smoke-generating fire and other specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs the identification result that the fire is a smoke-generating fire to the outside along with the fire.

(2 wavelengths, 2 scattering angles method: distinguishing between white and black smoke)
the identification unit identifies a white smoke fire when a ratio between a multiplied value of the first wavelength and the forward scattering detection signal and a multiplied value of the second wavelength and the backward scattering detection signal satisfies a predetermined smoke identification condition corresponding to white smoke, and identifies a black smoke fire when a predetermined smoke identification condition corresponding to black smoke is satisfied;
When the identification unit has identified a smoke-emitting fire and other predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs to the outside the identification result that the fire is a white smoke fire along with the fire, and when the identification unit has identified a black smoke fire and other predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs to the outside the identification result that the fire is a black smoke fire along with the fire.

(2 wavelength 2 scattering type smoke detector structure: 2 LED + 1 PD)
The signal detection unit
a light receiving unit that outputs a forward scattering detection signal when it receives scattered light of the light of the first wavelength that has been irradiated onto the detection target, and outputs a backward scattering detection signal when it receives scattered light of the light of the second wavelength that has been irradiated onto the detection target;
a first light emitting unit that irradiates the detection target with light of a first wavelength so that scattered light at a forward scattering angle is incident on the light receiving unit and a forward scattering detection signal is output;
a second light emitting unit that irradiates the detection target with light of a second wavelength so that scattered light at a backscattering angle is incident on the light receiving unit and a backscattering detection signal is output;
Equipped with.

(Disaster prevention equipment 1)
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 is characterized by being provided with a signal detection section, a discrimination section, and a detection output section.

(Disaster prevention equipment 2)
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 provided with a signal detection unit,
The receiver is characterized by being provided with an identification unit and the detection output unit.

(Control according to fire identification results)
The receiver of the disaster prevention equipment varies the control to prevent the spread of the fire, suppress the fire, or extinguish the fire depending on the identification result output from the detection output unit.

(Control according to fire identification results)
If the receiver of the disaster prevention equipment identifies a semiconductor manufacturing gas fire, the control will be to stop the supply of semiconductor manufacturing gas and/or release inert gas into the area where the fire has occurred.

(Fire detection method 1)
The present invention is a fire detection method characterized by detecting a smoke fire that produces smoke and a predetermined gas fire that produces monodisperse particles, and distinguishing between the two types of fire.

(Fire alarm including identification results)
If it is determined that the fire is a smoke fire or a specified gas fire, the determination result is output along with the fire.

(Control according to the identification result)
Depending on the identification result, different controls are taken to prevent the fire from spreading, suppress it, or extinguish it.

(Gas fire in semiconductor manufacturing)
If the identification result is a semiconductor manufacturing gas fire, the control will be to stop the supply of semiconductor gas and/or release inert gas to the area where the fire has occurred.

(Fire detection method 2)
The present invention provides a fire detection method for detecting a fire in a monitored area, comprising:
A signal detection unit irradiates a detection target in a monitoring area with light action with light, and detects a plurality of detection signals received at different scattering angles;
The identification unit identifies whether the fire is a smoke-generating fire that generates smoke or a semiconductor manufacturing gas fire that generates monodisperse particles based on the plurality of detection signals detected by the signal detection unit;
When the identification unit has identified a smoke fire or a semiconductor manufacturing gas fire and any of the plurality of detection signals satisfies a predetermined fire detection condition, the detection output unit outputs the identification result together with the fire to the outside.
It is characterized by:

(Gas for semiconductor manufacturing)
The semiconductor manufacturing gas is silane gas or phosphine gas.

(Effectiveness of fire detection devices)
According to the fire detection device of the present invention, when a fire breaks out in a monitored area, multiple signals are detected at multiple different scattering angles as signals from the combustion products that are the detection target in the monitored area and involve optical action.Based on these signals, if the particle size of the combustion object is smaller than the wavelength of the irradiated light, the scattering intensity of the light is distributed approximately uniformly in the front and rear, and predetermined identification conditions corresponding to Rayleigh scattering, which is minimum at a scattering angle of 90°, are met, the device identifies that the fire is a semiconductor manufacturing gas fire, in which gases such as silane gas and phosphine gas used in semiconductor manufacturing are burned to produce monodispersed particles.The device outputs the identification result that a semiconductor manufacturing gas fire has been identified together with the fire to the outside, allowing control such as stopping the supply of semiconductor manufacturing gas and/or releasing inert gas into the fire area, thereby enabling safe and reliable fire extinguishing.

(Effect of identifying and detecting gas leak fires using the one-wavelength, three-scattering-angle method)
Furthermore, in the one wavelength, three scattering angle method, when light is irradiated onto the combustion products to be detected, the light intensity distribution due to Rayleigh scattering, which is scattering of particles smaller than the wavelength of light, is approximately uniform in the front and back and is minimum at a scattering angle of 90°.Therefore, by detecting the forward scattering detection signal, the backward scattering detection signal and the 90° scattering detection signal, if the specified identification condition corresponding to Rayleigh scattering, at which the 90° scattering detection signal reaches its minimum value, it is identified as a semiconductor manufacturing gas fire involving silane gas or phosphine gas, making it possible to reliably detect and deal with semiconductor manufacturing gas fires at an early stage.

(Effect of identifying and detecting smoke-emitting fires using the one-wavelength, three-scattering-angle method)
Furthermore, in the one wavelength, three scattering angle method, the light intensity distribution in Mie scattering, which is the scattering of particles larger than the wavelength of light, is such that forward scattering is greater than backward scattering, and the sizes of smoke particles from smoke fires vary widely from smaller to larger than the wavelength of the light irradiated on the detection target, resulting in a composite scattering of Rayleigh scattering and Mie scattering.Since composite scattering does not satisfy the identification condition corresponding to Rayleigh scattering, which is that the 90° scattering detection signal is at a minimum value corresponding to Rayleigh scattering, in this case it is identified as a smoke fire, and it is possible to extinguish the smoke fire using, for example, water or halon fire extinguishing gas, even in monitored areas where semiconductor equipment using silane gas, phosphine gas, etc. is installed.

(Effect of the first smoke detector structure using the one-wavelength, three-scattering-angle method)
In the one wavelength, three scattering angles method, the signal detection unit has three light receiving units for one light emitting unit that are arranged to receive scattered light at a forward scattering angle, a backward scattering angle, and a scattering angle of 90°, thereby enabling reliable detection of three types of signals with different scattering angles with a simple configuration. Furthermore, by emitting light from one light emitting unit, signals from each light receiving unit can be obtained simultaneously.

(Effect of the second smoke detector structure using the one-wavelength, three-scattering-angle method)
In addition, in the one wavelength, three scattering angles method, the signal detection unit can reliably detect three types of signals with different scattering angles with a simple configuration by arranging three light emitting units for one light receiving unit so that scattered light at forward scattering angles, backward scattering angles, and 90° scattering angles is received. In this case, each light emitting unit emits light in sequence, and each signal is obtained in turn.

(Effect of identifying and detecting gas leak fires using the one-wavelength, two-scattering angle method)
In addition, in the one-wavelength, two-scattering angle method, the signal detection unit irradiates light onto the combustion products to be detected and detects either a forward scattering detection signal or a backward scattering detection signal, and a 90° scattering detection signal, and the identification unit identifies the fire as being a semiconductor manufacturing gas fire, such as silane gas or phosphine gas, if the ratio of the forward scattering detection signal to the 90° scattering detection signal, or the ratio of the forward scattering detection signal to the 90° scattering detection signal, satisfies a predetermined identification condition corresponding to Rayleigh scattering, thereby enabling semiconductor manufacturing gas fires to be reliably detected and dealt with at an early stage.

(Effect of identifying and detecting normal fires using the one-wavelength, two-scattering angle method)
Furthermore, if the ratio between the forward scattering detection signal and the 90° scattering detection signal, or the ratio between the forward scattering detection signal and the 90° scattering detection signal, does not satisfy a predetermined identification condition corresponding to Rayleigh scattering, the identification unit identifies the fire as a smoke-generating fire, and makes it possible to extinguish the smoke-generating fire, for example, by using water or halon fire extinguishing gas, even in a monitored area where semiconductor equipment using silane gas, phosphine gas, or the like is installed.

(Effect of the first smoke detector structure using the one-wavelength, two-scattering angle method)
In the one wavelength, two scattering angles method, the signal detection unit has two light emitting units for one light emitting unit, and is arranged to receive scattered light at a forward scattering angle and a 90° scattering angle, or at a backward scattering angle and a 90° scattering angle, thereby making it possible to detect two types of signals with different scattering angles with a simple configuration. Furthermore, by emitting light from one light emitting unit, signals can be obtained simultaneously from each light receiving unit.

(Effect of the second smoke detector structure using the one-wavelength, two-scattering angle method)
In the one wavelength, two scattering angles method, the signal detection unit can detect two types of signals with different scattering angles with a simple configuration by arranging two light emitting units for one light receiving unit so that forward scattered light and a 90° scattering angle, or backward scattered light and a 90° scattering angle, are received. In this case, each light emitting unit emits light in sequence, and the light receiving unit outputs each signal in sequence.

(Effect of distinguishing white smoke from black smoke using the one wavelength, three scattering angle method and the one wavelength, two scattering angle method)
Furthermore, in the one wavelength three scattering angle method and the one wavelength two scattering angle method, when smoke is identified as that of a normal fire, if the ratio of the forward scattered light to the 90° scattered detection signal or the ratio of the back scattered light to the 90° scattered detection signal satisfies predetermined identification conditions corresponding to white smoke, it is identified as a white smoke fire, and if it satisfies predetermined identification conditions corresponding to black smoke, it is identified as a black smoke fire, and by outputting the identification result that it is a white smoke fire or a black smoke fire together with the fire to the outside, it becomes possible to take measures such as swift evacuation guidance and extinguishing the fire, for example, in the case of a black smoke fire, which poses a high fire risk.

(Effect of identifying and detecting gas combustion products using a two-wavelength, two-scattering method)
Furthermore, in the two-wavelength, two-scattering angle method, the signal detection unit creates differences in scattering characteristics due to the scattering angle by varying the scattering angle with respect to the detection object between a forward scattering angle and a backward scattering angle, and at the same time creates differences in scattering characteristics due to the wavelength by varying the wavelength of the light irradiated onto the detection object between a first wavelength and a second wavelength. The synergistic effect of this difference in scattering angle and difference in wavelength creates a significant difference in the scattering intensity of the light scattered by monodisperse particles generated in semiconductor manufacturing gas fires, such as silane gas or phosphine gas, and smoke generated in smoke-generating fires. If the ratio of the multiplied value of the first wavelength and the forward scattering detection signal to the multiplied value of the second wavelength and the backward scattering detection signal satisfies a predetermined identification condition corresponding to Rayleigh scattering, the identification unit identifies the fire as being a semiconductor manufacturing gas fire, such as silane gas or phosphine gas, making it possible to reliably detect and deal with semiconductor manufacturing gas fires at an early stage.

(Discrimination and detection of smoke-emitting fires using a two-wavelength, two-scattering angle method)
Furthermore, in the two-wavelength, two-scattering angle method, if the ratio between the multiplication value of the first wavelength and the forward scattering detection signal and the multiplication value of the second wavelength and the backward scattering detection signal does not satisfy a predetermined identification condition corresponding to the monodisperse particles that occur in a gas fire used in semiconductor manufacturing, the identification unit will identify that it is a smoke fire, and make it possible to extinguish the smoke fire with, for example, water or halon fire extinguishing gas, even in a monitored area where semiconductor equipment using silane gas, phosphine gas, etc. is installed.

(Distinguishing between white and black smoke using a two-wavelength, two-scattering angle method)
Furthermore, in the two-wavelength two-scattering angle method, if the ratio of the multiplication value of the first wavelength and the forward scattering detection signal to the multiplication value of the second wavelength and the backward scattering detection signal satisfies a predetermined identification condition corresponding to white smoke, the fire is identified as a white smoke fire, and if the ratio satisfies a predetermined identification condition corresponding to black smoke, the fire is identified as a black smoke fire. By outputting the identification result that the fire is a white smoke fire or a black smoke fire to the outside along with the fire, it becomes possible to take measures such as swift evacuation guidance and extinguishing the fire, for example, in the case of a black smoke fire, which poses a high fire risk.

(Effect of the smoke detector structure using two wavelengths and two scattering angles)
In the two-wavelength, two-scattering angle system, the signal detection unit has two light-emitting units that irradiate one light-receiving unit with light of different wavelengths, and these units are arranged so that scattered light of forward and backward scattering angles is received, thereby enabling reliable detection of forward and backward scattering detection signals of different wavelengths and scattering angles with a simple configuration. In this case, each light-emitting unit emits light in sequence, and the light-receiving unit outputs each signal in sequence.

(Effect of the first disaster prevention equipment)
The present invention is a disaster prevention facility that uses the fire detection device described above, and by providing the detector with a signal detection unit, an identification unit, and a detection output unit, it is possible to deal with the problem by simply making changes to the detector.Even in the case of existing equipment, it is possible to easily deal with the problem by removing the detector attached to the base and replacing it with a detector that is provided with a signal detection unit, an identification unit, and a detection output unit.

(Effect of the second disaster prevention equipment)
The present invention is a disaster prevention facility that uses the fire detection device described above, and by providing a signal output unit in the detector and an identification unit and a detection output unit in the receiver, there is no need to make changes to the detector, and the problem can be addressed by making changes only to 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. 3A and 3B are explanatory diagrams showing a smoke detector equipped with a signal detection unit, in which FIG. 3A shows the structure of a first smoke detector using a one-wavelength, three-scattering-angle method, and FIG. 3B shows the structure of a second smoke detector using a one-wavelength, three-scattering-angle method. FIG. 1 is an explanatory diagram showing scattering intensity versus scattering angle for Rayleigh scattering and Lie scattering. FIG. 1 is a characteristic graph showing the scattering intensity versus scattering angle for white smoke, black smoke, and silicon oxide. This is an explanatory diagram showing, in a list format, forward scattering detection values, backward scattering detection values, and 90° scattering detection values A1 to A3 corresponding to the types of smoke detected by the first smoke detection unit structure in Figure 3 (A), relative values when the 90° scattering detection value A3 is set to 1, the ratio between the backward scattering detection value and the 90° scattering detection value for distinguishing between white smoke and black smoke, and the conditions for distinguishing between white smoke and black smoke. 3 is a flowchart illustrating a control operation according to an embodiment of the sensor of FIG. 2; FIG. 1 is an explanatory diagram of a disaster prevention equipment showing a specific embodiment of the present invention, which is targeted at a P-type disaster prevention equipment using a smoke detector with a one-wavelength, two-scattering angle system. 9 is an explanatory diagram showing the structure of a smoke detector corresponding to the signal detector of FIG. 8 . FIG. FIG. 10 is an explanatory diagram showing, in a list format, the ratio and the conditions for distinguishing between white smoke and black smoke based on the backscattered smoke detection value A2 and the 90° scattered smoke detection value A3 detected by the first smoke detection unit structure of FIG. 9(A). FIG. 10 is an explanatory diagram showing a specific embodiment of the present invention that targets a P-type disaster prevention facility equipped with a signal detection unit using a two-wavelength, two-scattering angle method. FIG. 2 is an explanatory diagram showing the structure of a smoke detector using a two-wavelength, two-scattering angle method. FIG. 12 is an explanatory diagram showing, in a list format, the forward scattering detection value A1 and the backward scattering detection value A2 of the first wavelength, the forward scattering detection value A1 and the backward scattering detection value A2 of the second wavelength, the ratio of the multiplication value of the first wavelength and the forward scattering detection value to the multiplication value of the second wavelength and the backward scattering detection value, and the discrimination conditions for white smoke or black smoke, which correspond to the types of smoke detected by the smoke detection unit structure of 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 determines whether a fire has occurred on the receiver side. FIG. 14 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. 13. 15 is a flowchart showing, in the form of a time chart, the control operation of the embodiment of the R-type disaster prevention equipment of FIG. 14.

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 a disaster prevention equipment detector 12 that is composed of a receiver 10 and a detector 12, and is equipped with a signal detection unit 16, an identification unit 18, and a detection output unit 20.

The "signal detection unit 16" detects signals from a detection target in the monitoring area that involve optical action by using optical settings with multiple different scattering angles, and detects multiple signals obtained by these optical settings.

Here, "detection target in a monitoring area involving optical action" refers to smoke, a combustion product generated in the event of a fire, which, for example, generates scattered light when irradiated with light. This concept includes not only smoke generated by smoke-generating fires, including general fires, oil fires, and electrical fires, but also, in this embodiment, monodisperse particles generated by specific gas fires, such as monodisperse particles generated by gas fires used in semiconductor manufacturing, such as silane gas used as a doping gas in semiconductor manufacturing and phosphine gas used as an epitaxial gas.

For example, silane gas ( _SiH4 ) is toxic, and it is stipulated that in the event of a fire, the fire should not be extinguished unless the leak is stopped. Powder fire extinguishing agents, foam fire extinguishing agents, and _CO2 are used as extinguishing agents. There is a risk of it reacting violently with water to produce toxic gas, and water should not be used in the initial stage of fire extinguishing, so firefighting activities must be carried out separately from smoke fires. When silane gas leaks into the air, it reacts with oxygen at room temperature and burns easily. The lower flammability limit of silane gas is around 1%, and it is extremely unstable against oxygen, so when it comes into contact with air it spontaneously ignites and burns explosively, producing silicon oxide ( _SiO2 ) as monodisperse particles. The chemical formula for silane gas combustion is:
SiH ₄ +2O ₂ →SiO ₂ +2H ₂ O
Silicon oxide (SiO ₂ ) produced in a silane gas fire has a particle size of, for example, about 50 nm to 60 nm.

Furthermore, "multiple different optical settings" refers to detecting multiple signals obtained by irradiating a detection target in a monitoring area with light of a predetermined wavelength and receiving scattered light obtained at different scattering angles.

As an example of "multiple different optical settings," a first optical setting is one in which the detection target is irradiated with light of a predetermined wavelength and the received signal of scattered light obtained at a predetermined forward scattering angle θ1 less than 90° is detected as a forward scattering detection signal; a second optical setting is one in which the detection target is irradiated with light of a predetermined wavelength and the received signal of scattered light obtained at a predetermined backward scattering angle θ2 greater than 90° is detected as a backward scattering detection signal; and a third optical setting is one in which the detection target is irradiated with light of a predetermined wavelength and the received signal of scattered light obtained at a scattering angle of 90° is detected as a 90° scattering detection signal.

The signal detection unit 16 may have any configuration or structure, but for example, it may be a one-wavelength, three-scattering-angle system in which light of a predetermined wavelength is irradiated onto the detection target and three detection signals received at three different scattering angles are detected. Examples of smoke detection unit structures for the one-wavelength, three-scattering-angle system include a first smoke detection unit structure consisting of one light-emitting element and three light-receiving elements, and a second smoke detection unit structure consisting of one light-receiving element and three light-emitting elements that irradiate light of the same wavelength.

The "identification unit 18" distinguishes between a smoke-generating fire that produces smoke and a specific gas fire that produces monodispersed particles, such as a semiconductor manufacturing gas fire, such as silane gas or phosphine gas, based on multiple detection signals detected by the signal detection unit. For example, if the multiple detection signals satisfy specific identification conditions corresponding to Rayleigh scattering, the unit will identify the fire as a semiconductor manufacturing gas fire.

As mentioned above, "Rayleigh scattering" refers to the scattering of light by particles smaller than the wavelength of light. The scattering intensity (amount of scattered light) is distributed approximately uniformly in the front and rear and is minimized at a scattering angle of 90°. The silicon oxide particles that occur in semiconductor manufacturing gas fires, such as silane gas fires, are very small, ranging in size from 50 nm to 60 nm, and are smaller than the wavelength of the irradiated light, resulting in Rayleigh scattering. For this reason, the identification unit 18 identifies a silane gas fire when a predetermined identification condition corresponding to Rayleigh scattering, in which the 90° scattering detection signal reaches a minimum value, is met.

The "identification unit 18" also identifies a smoke fire when the 90° scattering detection signal does not meet the predetermined identification condition corresponding to Rayleigh scattering, which is the minimum value. The smoke produced by smoke fires, including general fires, oil fires, and electrical fires, is primarily composed of carbon oxides and water caused by the burning of organic matter, with particle sizes ranging from roughly 0.0001 μm to several μm. Therefore, particles smaller than the wavelength of the irradiated light undergo Rayleigh scattering, while particles larger than the wavelength of the light undergo Mie scattering, resulting in a composite scattering effect that combines both.

As mentioned above, "Mie scattering" is the scattering of light by particles larger than the wavelength of light, and the intensity of light scattering forward is greater than that of light scattering backward. Because smoke from a smoke-generating fire is a combination of Rayleigh scattering and Mie scattering, the intensity of light scattering does not reach a minimum at a scattering angle of 90°. For this reason, the identification unit identifies a smoke-generating fire when the identification condition corresponding to Rayleigh scattering, at which the 90° scattering detection signal reaches a minimum, is not met.

Furthermore, when the identification unit 18 identifies a smoke-generating fire, it further identifies whether it is a white smoke fire that produces white smoke or a black smoke fire that produces black smoke. As an example, the identification unit identifies a white smoke fire when the ratio of the forward scattered light detection signal to the 90° scattered light detection signal, or the ratio of the backscattered light to the 90° scattered light detection signal, satisfies a predetermined identification condition corresponding to white smoke, and identifies a black smoke fire when the ratio satisfies a predetermined identification condition corresponding to black smoke.

White smoke is whitish smoke composed primarily of moisture, which is produced when wood, cloth, etc., smokes (smolders), and is also called smoldering smoke. Black smoke is dark smoke produced when an object, for example, ignites and burns, and is also called combustion smoke. Wood and cotton wicks are known as burning materials in white smoke fire models that primarily produce white smoke, while kerosene is known as burning materials in black smoke fire models that primarily produce black smoke.

When the identification unit 18 has identified a specified gas fire and any of the multiple detection signals meets the specified fire detection conditions, the "detection output unit 20" outputs to the outside a notification that the fire is a specified gas fire along with the fire itself. For example, when the identification unit 18 has identified a semiconductor manufacturing gas fire, such as silane gas or phosphine gas, and the specified fire detection conditions are met based on the forward scattering detection signal or the back scattering detection signal, the "detection output unit 20" outputs to the outside a notification that the fire has been identified as a semiconductor manufacturing gas fire along with the fire itself.

Here, "when a specified fire detection condition is met" means that any of the multiple signals meets a specified threshold condition or accumulation condition, and is a concept that includes, for example, when a specified threshold is exceeded, or when a state in which the specified threshold is exceeded continues for a specified accumulation time.

In addition, this embodiment is a one-wavelength, two-scattering angle signal detection unit 16 that is a simplified version of the one-wavelength, three-scattering angle system, and detects forward scattering detection signals and 90° scattering detection signals, or backward scattering detection signals and 90° scattering detection signals, using first and second optical settings. While the configuration and structure are arbitrary, examples include a first smoke detection unit structure consisting of one light-emitting element and two light-receiving elements, and a second smoke detection unit structure consisting of one light-receiving element and two light-emitting elements that irradiate light of the same wavelength.

In conjunction with the signal detection unit 16 using the one-wavelength, two-scattering angle method, the identification unit 18 identifies a fire as a gas fire used in semiconductor manufacturing, such as silane gas or phosphine gas, when the ratio of the forward scattering detection signal to the 90° scattering detection signal, or the ratio of the back scattering detection signal to the 90° scattering detection signal, satisfies predetermined identification conditions corresponding to Rayleigh scattering. Conversely, when the predetermined identification conditions corresponding to Rayleigh scattering are not met, the identification unit 18 identifies a fire as a smoke-generating fire.

Furthermore, when the identification unit 18 identifies a smoke-generating fire, it will identify it as a white smoke fire if the ratio of the forward scattering detection signal to the 90° scattering detection signal, or the ratio of the backscattered light to the 90° scattering detection signal, satisfies predetermined identification conditions corresponding to white smoke, as with the one wavelength, three scattering angle method, and will identify it as a black smoke fire if the ratio satisfies predetermined identification conditions corresponding to black smoke, and will output the identification result indicating a white smoke fire or a black smoke fire together with the fire via the detection output unit 20 to the outside.

In addition, this embodiment employs a two-wavelength, two-scattering angle signal detection unit 16 that accentuates differences in scattering intensity depending on the detection target due to differences in wavelength as well as differences in scattering angle. For example, the signal detection unit 16 may, in a first optical setting, irradiate the detection target with light of a predetermined first wavelength and detect a received signal of scattered light obtained at a predetermined forward scattering angle as a forward scattering detection signal, and in a second optical setting, irradiate the detection target with light of a predetermined second wavelength different from the first wavelength and detect a received signal of scattered light obtained at a predetermined backscattering angle as a backscattering detection signal. While any configuration or structure may be used, for example, the smoke detector may have a structure consisting of one light receiving element and two light emitting elements that irradiate light of different wavelengths.

In conjunction with the signal detection unit 16 using the two-wavelength, two-scattering angle method, the identification unit 18 identifies a fire as a gas fire used in semiconductor manufacturing, such as silane gas or phosphine gas, when the ratio of the multiplication value of the first wavelength and the forward scattering detection signal to the multiplication value of the second wavelength and the backscattering detection signal satisfies predetermined identification conditions corresponding to Rayleigh scattering, and identifies a fire as a smoke-generating fire when predetermined identification conditions corresponding to smoke from a smoke-generating fire are satisfied.

In addition, when the identification unit 18 identifies a smoke-emitting fire, it identifies it as a white smoke fire if the ratio of the multiplication value of the first wavelength and the forward scattering detection signal to the multiplication value of the second wavelength and the back scattering detection signal satisfies a predetermined identification condition corresponding to white smoke, or identifies it as a black smoke fire if the ratio satisfies a predetermined identification condition corresponding to black smoke, and causes the detection output unit 20 to output the identification result indicating that it is a white smoke fire or a black smoke fire together with the fire to the outside.

In the following explanation, the "monitoring area" is a "room in a building," the "signal detection unit 16" is the "one wavelength, three scattering angle method," the "one wavelength, two scattering angle method," or the "two wavelength, two scattering angle method," the "forward scattering detection signal," the "backward scattering detection signal," and the "90° scattering detection signal" detected by each method are the "forward scattering detection value A1," the "backward scattering detection value A2," and the "90° scattering detection value A3," and the "semiconductor manufacturing gas fire producing monodisperse particles exhibiting Rayleigh scattering" is a "silane gas fire producing silicon oxide exhibiting Rayleigh scattering." Note that each scattering detection value A1 to A3 is a concept that includes scattering intensity, scattered light amount, and signal amount.

[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 b. Signal detection unit b1. One-wavelength, three-scattering angle signal detection unit b2. One-wavelength, three-scattering angle first smoke detection unit structure b3. One-wavelength, three-scattering angle second smoke detection unit structure c. Detector control unit d. Identification unit d1. Identification function d2. Rayleigh scattering d3. Mie scattering d4. Compound scattering d5. Scattering characteristics of detection target d6. Identification of silane gas fires d7. Identification of smoke-emitting fires d8. Identification of white smoke fires and black smoke fires e. Detection output unit e1. Detection conditions for silane gas fires e2. Detection conditions for smoke-emitting fires e3. Transmission of fire alarm signal based on fire detection f. Detector control operation g. Embodiment equipped with one-wavelength, two-scattering angle signal detection unit g1. One-wavelength, two-scattering angle first smoke detection unit structure g2. Structure of second smoke detector using one wavelength and two scattering angles g3. Identification unit using one wavelength and two scattering angles h. Embodiments equipped with a signal detector using two wavelengths and two scattering angles h1. Signal detector using two wavelengths and two scattering angles h2. Structure of smoke detector using two wavelengths and two scattering angles h3. Identification unit using two wavelengths and two scattering angles h4. Identification between silane gas fires and smoke-generating fires h5. Rayleigh scattering and wavelength i. Basic concept of other embodiments j. R-type disaster prevention equipment j1. Detector j2. Receiver j3. Transmission control j4. Identification unit of receiver j5. Detection output unit of receiver j6. Control operation of R-type disaster prevention equipment k. 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" is 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 the sensors 12 are connected to a signal line 14 that is drawn from the receiver 10 to the monitored area, such as a room in the building.

Here, the room that serves as the monitored area contains semiconductor manufacturing equipment that uses silane gas, and the detector 12 of this embodiment transmits a fire alert signal to the receiver 10 that includes the fire's identification result, indicating that it is a silane gas fire or a smoke fire. Furthermore, for smoke fires, the detector 12 of this embodiment transmits a fire alert signal that includes the fire's identification result, indicating that it is a white smoke fire or a black smoke fire. In addition to the detector 12 of this embodiment, a publicly known, highly sensitive scattered light smoke detector that detects smoke produced by smoke fires may also be connected to the receiver 10.

The signal line 14 drawn from the receiver 10 has a positive signal line 14a and a negative signal line (common signal line) 14b, which supplies power from the receiver 10 to the detector 12 and also transmits a fire alarm signal including the aforementioned identification result from the detector 12 to the receiver 10.

(a1. Receiver)
The receiver 10 of the P-type disaster prevention system will now be described in more detail. The receiver 10 includes a receiver control unit 46, a line receiving unit 48, a display unit 50, an operation unit 52, an alarm unit 54, and a signal transmission unit 56. The line receiving unit 48 is provided for each signal line 14 drawn out from the monitoring area, e.g., each floor of a building. The line receiving unit 48 receives a fire alarm signal from the detector 12 of this embodiment, including identification information indicating that a silane gas fire or a smoke-emitting fire has been identified. The line receiving unit 48 outputs this received detection signal to the receiver control unit 46. Furthermore, the smoke-emitting fire detection signal is output separately as a white smoke fire detection signal and a black smoke fire detection signal. Furthermore, when the line receiving unit 48 receives a fire alarm signal from a known scattered light detector, it outputs a smoke-emitting fire detection signal to the receiver control unit 46.

The receiver control unit 46 is composed of a computer circuit equipped with a CPU, memory, and various input/output ports, and performs a fire alarm operation when it receives a silane gas fire detection signal or a smoke fire detection signal output from the line receiving unit 48. The fire alarm operation of the receiver control unit 46 activates the fire representative light on the display unit 44 and the district indicator light indicating the district where the fire has occurred, and also displays an indication of a silane gas fire or a smoke fire on a display or the like, and for smoke fires, displays whether the fire is a white smoke fire or a black smoke fire. In addition, the alarm unit 48 outputs a main acoustic alarm including an alarm voice message, and also issues a district acoustic alarm by activating district sounding devices installed in the monitored area where the fire has occurred.

The silane gas fire warning display and audio warning message by the alarm unit 48 are arbitrary, but may be, for example, "Silane gas has been detected. A silane gas fire has occurred." In addition to the warning display and audio warning message, the alarm unit 48 may provide guidance on fire extinguishing agents that can be used to extinguish a silane gas fire, prohibiting the use of water and instructing the use of carbon dioxide or a dry chemical fire extinguisher. The alarm unit 48 may also instruct the reporting unit 56 to perform interlocking control of smoke control and exhaust devices and to report the fire to external fire departments, etc.

Furthermore, the reception control unit 46 causes the notification unit 56 to output a control signal to the notification destination to change the control for preventing the spread of the fire, suppressing it, or extinguishing it, depending on the identification result of whether it is a silane gas fire or a smoke-generating fire. For example, if the identification result is a silane gas fire, the reception control unit 46 instructs the notification unit 56 to transmit and output a control signal to stop the supply of silane gas to the semiconductor manufacturing equipment, and also to transmit and output a control signal to inert gas fire extinguishing equipment such as carbon dioxide fire extinguishing equipment to release inert gas such as carbon dioxide gas into the fire area.

(a2. Sensor)
The detector 12 of this embodiment, which functions as a fire detection device, includes a signal detection section 16, a detector control section 24, an alarm circuit section 26, a power supply section 28, a light emission driving section 38, and light reception amplifier sections 40, 42, 44.

[b. Signal detection unit]
(b1. Signal detection unit using one wavelength, three scattering angles method)
The signal detection unit 16 of the one-wavelength, three-scattering angle system provided in the detector 12 will now be described in more detail. The signal detection unit 16 irradiates a detection target, such as silicon oxide produced in a silane gas fire or smoke produced in a smoke-emitting fire, with light of a predetermined wavelength λ, and detects a forward scattering detection value A1 based on a forward scattering detection signal obtained by receiving scattered light obtained at a predetermined forward scattering angle θ1 using a first optical setting, a backscattering detection value A2 based on a backscattering detection signal obtained by receiving scattered light obtained at a predetermined backscattering angle θ2 using a second optical setting, and a 90° scattering detection value A3 based on a 90° scattering detection signal obtained by receiving scattered light obtained at a scattering angle of 90° using a third optical setting. The configuration and structure of the signal detection unit 16 are arbitrary, but it may include, for example, a light-emitting element 30, a first light-receiving element 32, a second light-receiving element 34, and a third light-receiving element 36 disposed in a smoke detection unit provided inside the detector, which is a space into which outside air flows but which is blocked from outside light.

Figure 3 is an explanatory diagram showing the smoke detection section structure of the signal detection unit 16. Figure 3(A) shows an embodiment of the first smoke detection section structure corresponding to the signal detection unit 16 in Figure 2, and Figure 3(B) shows a second smoke detection section structure as another embodiment.

(b2. First smoke detector structure using one wavelength, three scattering angles method)
The structure of the first smoke detector using the one-wavelength, three-scattering angle system will now be described in more detail. As shown in Fig. 3(A), the first smoke detector using the one-wavelength, three-scattering angle system has a light-emitting element 30, a first light-receiving element 32, a second light-receiving element 34, and a third light-receiving element 36 arranged in a planar configuration within a smoke detector 58 where smoke enters from outside and light from outside is blocked, with the optical axes of each element being arranged in the same plane. The light-emitting element 30 is driven to emit light at predetermined intervals by the light-emitting element driver 38 shown in Fig. 2, and the light-receiving signals from the first to third light-receiving elements 32, 34, and 36 are amplified by light-receiving amplifiers 40, 42, and 44 and then sequentially read by A/D conversion in the sensor control unit 24.

The light-emitting element 30 can be of any type, but for example, a near-infrared LED (light-emitting diode) is used, and emits light with a wavelength λ of, for example, light with a central wavelength in the range of 400 nm to 1000 nm, such as light with a near-infrared wavelength of λ = 900 nm. The first to third light-receiving elements 32, 34, and 36 are photodiodes PD that are sensitive from the infrared region to the visible light region.

In the first optical setting of the signal detection unit 16, the first light-receiving element 32 is positioned at a scattering angle θ1 relative to point P (smoke detection point) where its optical axis intersects with the optical axis of the light-emitting element 30. The scattering angle θ1 is set to a predetermined angle less than 90°, for example, a forward scattering angle of θ1 = 40°. When the light-emitting element 30 is driven by the light-emitting driver 38 to emit light, light with a wavelength λ = 900 nm is irradiated onto the smoke that has flowed into point P. The scattered light (forward scattered light) from the smoke corresponding to the scattering angle θ1 = 40° is incident on and received by the first light-receiving element 32, and a forward scattering detection signal is output as a received light signal. This signal is amplified by the light-receiving amplifier 40, A/D converted, and read by the sensor control unit 24, thereby detecting a forward scattering detection value A1 corresponding to the smoke concentration.

As a second optical setting of the signal detection unit 16, the second light-receiving element 34 is disposed at a scattering angle θ2 relative to point P (smoke detection point) where its optical axis intersects with the optical axis of the light-emitting element 30, and the second scattering angle θ2 is set to a predetermined angle exceeding 90°, for example, a backscattering angle of θ2 = 110°. When the light-emitting element 30 is driven by the light-emitting drive unit 38 to emit light, light of wavelength λ = 900 nm is irradiated onto the smoke that has flowed into point P, and the scattered light (backscattered light) from the smoke corresponding to the scattering angle θ2 = 110° is incident on and received by the second light-receiving element 34, and a backscattering detection signal is output as a received light signal. The backscattering detection signal is amplified by the received light amplifier 42 and A/D converted and read by the sensor control unit 24, whereby a backscattering detection value A2 corresponding to the smoke concentration is detected.

Furthermore, as a third optical setting of the signal detection unit 16, the third light receiving element 36 is positioned at a scattering angle θ3 = 90° with respect to point P (smoke detection point) where its optical axis intersects with the optical axis of the light emitting element 30. When the light emitting element 30 is driven by the light emitting driver 38 to emit light with wavelength λ = 900 nm, the smoke that has flowed into point P is irradiated with light scattered from the smoke corresponding to a scattering angle θ3 = 90°, which is incident on and received by the third light receiving element 36. A 90° scattering detection signal is output as a received light signal, which is amplified by the received light amplifier 44, A/D converted, and read by the sensor control unit 24, thereby detecting a 90° scattering detection value A3 corresponding to the smoke concentration.

(b3. Secondary smoke detector structure using one wavelength, three scattering angles method)
The second smoke detector structure of the one-wavelength, three-scattering angle system will now be described in more detail. Instead of the first smoke detector structure shown in FIG. 3A, the second smoke detector structure shown in FIG. 3B can also be used. As shown in FIG. 3B, the second smoke detector structure of the one-wavelength, three-scattering angle system has a planar arrangement in which a light-receiving element 60, a first light-emitting element 62, a second light-emitting element 64, and a third light-emitting element 66 are arranged within a smoke detector 58, with their optical axes aligned in the same plane. The first to third light-emitting elements 62, 64, and 66 are sequentially driven to emit light at predetermined intervals, and the light-receiving signal from the light-receiving element 60 is amplified and then sequentially read by the sensor control unit 24 through A/D conversion synchronized with the light emitted by the first to third light-emitting elements 62, 64, and 66.

The first to third light-emitting elements 62, 64, and 66 are near-infrared LEDs that emit light with a near-infrared wavelength of, for example, λ = 900 nm. The light-receiving element 60 is a photodiode PD that is sensitive from the infrared region to the visible light region.

In the first optical setting of the signal detection unit 16, the first light-emitting element 62 is positioned so that when it irradiates light at point P where its optical axis intersects with the optical axis of the light-receiving element 60, the light-receiving element 60 receives the scattered light obtained at a scattering angle θ1, which is set to a predetermined angle less than 90°, for example, a forward scattering angle of θ1 = 40°. When light with a wavelength λ = 900 nm emitted by the first light-emitting element 62 is irradiated onto the smoke that has flowed into point P, the scattered light from the smoke (forward scattered light) corresponding to the scattering angle θ1 = 40° is incident on and received by the light-receiving element 60, which then outputs a forward scattering detection signal as a received light signal and detects a forward scattering detection value A1 corresponding to the smoke concentration.

In addition, as a second optical setting of the signal detection unit 16, the second light-emitting element 64 is positioned so that when it irradiates light at point P where its optical axis intersects with the optical axis of the light-receiving element 60, the light-receiving element 60 receives the scattered light obtained at a scattering angle θ2, which is set to a predetermined angle greater than 90°, for example, a backscattering angle of θ2 = 110°. When light with a wavelength λ = 900 nm is emitted by the second light-emitting element 64 and irradiates the smoke that has flowed into point P, the scattered light (backscattered light) from the smoke corresponding to the scattering angle θ2 = 110° is incident on and received by the light-receiving element 60, a backscatter detection signal is output as a light-receiving signal, and a backscatter detection value A2 corresponding to the smoke concentration is detected.

Furthermore, as a third optical setting of the signal detection unit 16, the third light-emitting element 66 is positioned so that when it irradiates light at point P where its optical axis intersects with the optical axis of the light-receiving element 60, the light-receiving element 60 receives the scattered light obtained at a scattering angle θ3 = 90°. When the third light-emitting element 66 emits light with a wavelength λ = 900 nm and irradiates the smoke that has flowed into point P, the scattered light from the smoke corresponding to the scattering angle θ3 = 90° is incident on and received by the third light-receiving element 36, a 90° scattering detection signal is output as a light-receiving signal, and a 90° scattering detection value A3 corresponding to the smoke concentration is detected.

[c. Sensor control section]
A more detailed description will now be given of the detector control unit 24 of the detector 12. 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 the identification unit 18 and detection output unit 20, which are components of the fire detection device according to this embodiment, as functions realized by executing a program.

The detector control unit 24 acquires the forward scattering detection value A1, the backward scattering detection value A2, and the 90° scattering detection value A3 corresponding to the smoke concentration by sequentially reading the signals from the light receiving amplifier units 40, 42, and 44 through A/D conversion in synchronization with the timing of the light emitting element 30 being driven at a predetermined cycle. The identification unit 18 identifies whether the fire is a silane gas fire or a smoke fire based on the acquired forward scattering detection value A1, the backward scattering detection value A2, and the 90° scattering detection value A3. Furthermore, when the detection output unit 20 determines that a predetermined fire detection condition is met based on the acquired forward scattering detection value A1 or the backward scattering detection value A2, it activates the alarm circuit unit 26, shorting the positive signal line 14a and the negative signal line 14b to a low impedance to allow a fire alarm current to flow, and transmits a fire alarm signal to the receiver 10 along with the fire, including identification information indicating that it is a silane gas fire or a smoke fire.

[d. Identification unit]
(d1. Identification function)
The discrimination unit 18 of the detector 12 will be described in more detail below. The discrimination unit 18 discriminates a fire that produces silicon oxide as a silane gas fire if discrimination conditions corresponding to Rayleigh scattering are met based on the forward scattering detection value A1, the back scattering detection value A2, and the 90° scattering detection value A3 detected from the light reception signal of the signal detection unit 16, and discriminates a fire that produces smoke if discrimination conditions corresponding to Rayleigh scattering are not met, and further discriminates a fire that produces smoke as a white smoke fire or a black smoke fire if the fire produces black smoke.

When light of a specified wavelength is irradiated onto a detection target that has flowed from the monitoring area into the smoke detection unit 58 of the detector 12, the scattering characteristics will be Rayleigh scattering, Mie scattering, or a combination of both, depending on the size of the particle being detected.

(d2. Rayleigh scattering)
Rayleigh scattering will be explained in more detail. Figure 4(A) is an explanatory diagram showing the scattering intensity distribution (scattered light amount distribution) of Rayleigh scattering caused by particles smaller than the wavelength of light. When light indicated by arrow 70 is irradiated onto a particle 68 smaller than the wavelength of light, the intensity distribution of the scattered light is approximately uniform in the front and rear, and is minimum at a scattering angle of 90°. Silicon oxide, which is generated as monodisperse particles in silane gas fires, has particle sizes distributed in the range of approximately 50 nm to 60 nm. Since this particle size is small compared to the wavelength λ = 900 nm of the light irradiated onto the detection target, Rayleigh scattering occurs.

(d3. Mie scattering)
Mie scattering will be explained in more detail. Figure 4(B) is an explanatory diagram showing the scattering intensity distribution (scattered light amount distribution) of light due to Mie scattering by particles larger than the wavelength of light. When light indicated by arrow 70 is irradiated onto particles 78 larger than the wavelength of light, the intensity distribution of the scattered light shows that scattering in the forward direction is greater than scattering in the backward direction. Silicon oxide produced in silane gas fires does not exhibit Mie scattering because its particle size is small compared to the wavelength λ = 900 nm of the irradiated light.

(d4. Complex scattering)
Complex scattering will be explained in more detail. Smoke generated by smoke fires, including general fires, oil fires, and electrical fires, is primarily composed of carbonaceous combustion products and moisture, with particle sizes distributed over a wide range, for example, from 1 nm to several thousand nm (0.001 μm to several μm). Therefore, particles with a wavelength of less than 900 nm of light irradiated onto the detection target undergo Rayleigh scattering, while particles with a wavelength of more than 900 nm undergo Mie scattering. As a result, the smoke as a whole undergoes complex scattering, a combination of Rayleigh scattering and Mie scattering. Therefore, when the detection target is smoke from a smoke fire, which exhibits complex scattering, the forward scattering detection value A1, the backscattering detection value A2, and the 90° scattering detection value A3 do not exhibit a minimum value corresponding to Rayleigh scattering.

(d5. Scattering characteristics of detection target)
The scattering characteristics of the combustion products to be detected will now be described in more detail. Figure 5 is a characteristic graph showing the relationship between the scattering angle and scattering intensity (amount of scattered light) of combustion products, and shows white smoke characteristics 80 from the combustion of a cotton lantern, black smoke characteristics 82 from the combustion of kerosene, and silicon oxide characteristics 84 from a silane gas fire. Note that the white smoke characteristics 80 and black smoke characteristics 82 are smoke characteristics of smoke-emitting fires. Furthermore, since the particle sizes of white smoke and black smoke are relatively large and relatively small, the scattering intensity of the white smoke characteristics 80 is large and the black smoke characteristics 82 is small, and furthermore, the silicon oxide characteristics 84 is lower than the black smoke characteristics 82.

In the signal detection unit 16 of Fig. 3(A), as shown by the dotted lines in Fig. 5, a forward scattering detection value A1 is detected at a scattering angle θ1 = 40°, a backscattering detection value A2 is detected at a scattering angle θ2 = 110°, and a 90° scattering detection value A3 is detected at a scattering angle θ3 = 90°. Furthermore, a backscattering detection value A4 at a scattering angle of 140° is shown for reference. The values at the intersections of the dotted lines for scattering angles of 40°, 90°, 110°, and 140° in Fig. 5 with each characteristic indicate the scattering intensities corresponding to the detection values A1 to A4.

Figure 6 (A) shows in a table format the forward scattering detection value A1 at a scattering angle θ1 = 40°, the backscattering detection value A2 at a scattering angle θ2 = 110°, and the 90° scattering detection value A3 at a scattering angle θ3 = 90° for the white smoke characteristic 80, black smoke characteristic 82, and silicon oxide characteristic 84 in Figure 5, and also shows the backscattering detection value A4 at a scattering angle of 140° for reference. Figure 6 (B) also shows in a table format the relative values of the forward scattering detection value A1, backscattering detection value A2, and backscattering detection value A4 when the 90° scattering detection value A3 is set to 1.

(d6. Identifying Silane Gas Fires)
As shown in FIGS. 5 and 6A and 6B, the silicon oxide characteristic 84 generated by a silane gas fire is expressed as follows:
(A3<A1) and (A3<A2)
The relationship between the forward scattering detection value A1, the back scattering detection value A2, and the 90° scattering detection value A3 is the minimum, and therefore Rayleigh scattering can be identified. Therefore, based on the forward scattering detection value A1, the back scattering detection value A2, and the 90° scattering detection value A3, when the identification condition corresponding to Rayleigh scattering in which the 90° scattering detection value A3 is the minimum is satisfied, the identification unit 18 identifies that the detection target is silicon oxide and that it is a silane gas fire.

(d7. Identification of smoke-generating fires)
On the other hand, as shown in FIGS. 5 and 6A and 6B, the white smoke characteristic 80, which is one aspect of a smoke-generating fire, is a characteristic that is expressed as follows:
(A1>A3>A2)
The above relationship holds, and since the 90° scattering detection value A3 is not the minimum value, the identification unit 18 identifies that the detection target is smoke from a smoke-emitting fire that corresponds to compound scattering that combines Rayleigh scattering and Mie scattering, and that it is a smoke-emitting fire.

Furthermore, the black smoke characteristic 82 , which is another aspect of a smoke-generating fire, is similarly expressed as follows between the forward scattering detection value A1, the backward scattering detection value A2, and the 90° scattering detection value A3:
(A1>A3>A2)
The above relationship holds, and since the 90° scattering detection value A32 is not the minimum value, the discrimination unit 18 discriminates that the detected object is smoke from a smoke-emitting fire that corresponds to compound scattering that combines Rayleigh scattering and Mie scattering, and that it is a smoke-emitting fire. Note that the discrimination unit 18 of this embodiment does not discriminate that it is a smoke-emitting fire, but rather discriminates whether it is a white smoke fire or a black smoke fire, which will be described next.

(d8. Distinguishing between white smoke fires and black smoke fires)
The discrimination between white smoke fires and black smoke fires will be described in more detail below. The discrimination unit 18 discriminates between white smoke fires and black smoke fires based on, for example, the ratio R=A2/A3 of the backscattered fire detection value A2 to the 90° scattered fire detection value A3, corresponding to whether the detected smoke is white smoke or black smoke.

Figure 6 (C) shows in table format the ratio R of the backscatter detection value A2 and the 90° scattering detection value A3 in Figure 6 (A), with R = 0.71 for white smoke and R = 1.01 for black smoke. Based on these, the discrimination unit 18 sets a discrimination threshold Rth, for example Rth = 0.8, as the condition for discriminating between white smoke and black smoke, as shown in Figure 6 (D). If the ratio R is equal to or less than the threshold Rth = 0.8, it discriminates as white smoke and a white smoke fire, and if the ratio R exceeds the threshold Rth = 0.8, it discriminates as black smoke and a black smoke fire.

The discrimination unit 18 can arbitrarily discriminate between white smoke fires and black smoke fires. In addition to the ratio R=A2/A3 of the backscatter detection value A2 to the 90° scattering detection value A3, it can also calculate the ratio R=A1/A3 of the forward scattering detection value A1 to the 90° scattering detection value A3, or the ratio R=A1/A2 of the forward scattering detection value A1 to the backscatter detection value A2. If the specified discrimination conditions corresponding to white smoke are met, the discrimination unit 18 will discriminate between white smoke fires, and if the specified discrimination conditions corresponding to black smoke are met, the discrimination unit 18 will discriminate between black smoke fires.

[e. Detection output section]
The detection output unit 20 of the detector 12 will now be described in more detail. The detection output unit 20 provided in the detector control unit 24 outputs the identification result of the identification unit 18 together with a fire to the outside when at least one of the acquired forward scattering detection value A1 and back scattering detection value A2 satisfies a predetermined fire detection condition while an identification result has been obtained from the identification unit 18. Here, fire detection based on the forward scattering detection value A1 will be described as an example, but the same applies to the back scattering detection value A2.

(e1. Silane gas fire detection conditions)
The fire detection conditions of the detection output unit 20 when the identification unit 18 identifies a silane gas fire will be described in more detail. The scattering intensity due to Rayleigh scattering of silicon oxide generated in a silane gas fire is, for example, about 1/100 of the intensity of the white smoke characteristic 80, as shown by the silicon oxide characteristic 84 in Figure 5. For this reason, if the fire detection conditions are set so that a white smoke fire is detected when the smoke density of white smoke is equal to or exceeds a predetermined threshold value Dth0 = 10 (%/m), for example, the threshold smoke density for silicon oxide in a silane gas fire is set to Dth1 = 0.1 (%/m), and if the forward scattering detection value A1 is equal to or exceeds the threshold value Dth1 = 0.1 (%/m), a fire is detected, and the identification result that it is a silane gas fire is output to the outside along with the fire.

As another fire detection condition for silane gas fires, a fire may be detected when a predetermined accumulation condition is met while a fire detection condition based on a smoke density threshold is met. For example, if the smoke density threshold Dth1 = 0.1 (%/m) or greater continues for a predetermined accumulation time T1, e.g., T1 = 10 seconds or more, a fire is detected and the fire identification result that it is a silane gas fire is output to the outside. In the case of a silane gas fire, leaked silane gas is likely to burn explosively and spread to surrounding structures and equipment. In this case, smoke from a smoke-generating fire may be generated, making it difficult to identify as silicon oxide. Therefore, it is desirable to set the accumulation condition so that a silane gas fire can be detected within a short time, e.g., 10 seconds or less.

(e2. Conditions for detecting smoke-emitting fires)
The fire detection conditions of the detection output unit 20 when the discrimination unit 18 has obtained a discrimination result of a smoke-emitting fire, i.e., when the discrimination result of whether the fire is a white smoke fire or a black smoke fire, will be described in more detail. The fire detection conditions of the detection output unit 20 when the discrimination unit 18 has obtained a discrimination result of whether the fire is a white smoke fire or a black smoke fire are arbitrary. However, when the forward scattering detection value A1 satisfies a predetermined smoke density threshold condition, the detection output unit 20 detects a fire and outputs a discrimination result of whether the fire is a white smoke fire or a black smoke fire to the outside together with the fire. Here, the "smoke density threshold condition" refers to a condition under which a fire is detected when the forward scattering 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 white smoke fire or a black smoke fire is detected when the forward scattering detection value A1 is equal to or greater than the smoke density threshold Dth0 corresponding to the type 2 sensitivity, Dth0 = 10 (%/m).

A "type 2 sensitivity detector" is a detector with a legally mandated nominal activation concentration K of 10 (%/m), which 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) as an activation test, and which does not activate within 5 minutes (for example, in the case of a non-accumulation type) 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) as a deactivation test. In addition to this type 2 sensitivity detector with K = 10 (%/m), it is also possible to use a "type 1 sensitivity detector" with a nominal operating concentration K = 5 (%/m), or a "type 3 sensitivity detector" with a nominal operating sensitivity K = 15 (%/m).

As another fire detection condition, a fire caused by white or black smoke 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, and the forward scattering detection value A1 remains at or above the smoke density threshold Dth0 = 10 (%/m) corresponding to type 2 sensitivity for a predetermined accumulation time T0, for example, T0 = 20 seconds, a fire is detected, and the fire identification result indicating that it is a white smoke fire or a black smoke fire is output to the outside.

(e3. Transmission of fire alarm signal based on fire detection)
When the detection output unit 20 detects a silane gas fire, a white smoke fire, or a black smoke fire, the detector control unit 24 instructs the alarm circuit unit 26 to transmit a fire alarm signal including identification information of the type of fire to the receiver 10 as an output to the outside.

While the alarm circuit 26 can send any fire alarm signal, for example, it may send the fire alarm signal by shorting the positive signal line 14a and the negative signal line 14b to a predetermined low impedance and passing a predetermined alarm current for a predetermined period of time. It then disconnects the positive signal line 14a and the negative signal line 14b to a low impedance and passes a pulse current corresponding to a predetermined code indicating a silane gas fire, white smoke fire, or black smoke fire, thereby sending a fire identification signal, and this process is repeated periodically. It is also possible to set a different alarm current for each silane gas fire, white smoke fire, or black smoke fire and send a fire alarm signal.

[f. Sensor control operation]
FIG. 7 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 7, in step S1, the sensor control unit 24 acquires the forward scattering detection value A1, the backscattering detection value A2, and the 90° scattering detection value A3 corresponding to the smoke density detected by the signal detection unit 16.

Next, the 90° scattering detection value A3 acquired in step S2 is determined to be the minimum value that satisfies the identification condition corresponding to Rayleigh scattering. If it is determined to be the minimum value, the process proceeds to step S3, where it is identified as a silane gas fire. Next, the process proceeds to step S9, and if it is determined that the fire detection condition set for the identified silane gas fire is satisfied, for example, the threshold condition based on the forward scattering detection value A1 threshold of 0.1 (%/m), the process proceeds to step S10, where a fire alert signal including the fire and the identification result that it is a silane gas fire is sent to receiver 10, and a fire alert indicating a silane gas fire is output.

On the other hand, if it is determined in step S2 that the 90° scattering detection value A3 is not the minimum value, the process proceeds to step S4, where the ratio R = A2/A3 of the 90° scattering detection value A3 to the backscatter detection value A2 is calculated. If it is determined in step S5 that the white smoke identification condition based on the threshold value Rth1 is met, the process proceeds to step S6, where it is identified as a white smoke fire. If it is determined in step S5 that the white smoke identification condition is not met, the process proceeds to step S7, where it is identified as a black smoke fire.

If step S6 identifies a white smoke fire, or step S7 identifies a black smoke fire, the process proceeds to step S8. If it is determined that a specified fire detection condition is met, for example based on the forward scattering detection value A1, the process proceeds to step S9, where a fire producing white or black smoke is detected. A fire alert signal including the fire and the identification result of either a white or black smoke fire is sent to receiver 10, and a fire alarm is output indicating that a black or white smoke fire has been detected. For example, by reporting a highly dangerous black smoke fire, it is possible to take action such as prompt evacuation guidance or fire notification.

After transmitting a fire alert signal containing fire identification information in step S9, if recovery is determined in step S10 based on a recovery operation on the receiver 10, such as by cutting off the power supply to the signal line 14, the process returns to step S1.

[g. One wavelength, two scattering angle method]
An embodiment of the one-wavelength, two-scattering angle system will now be described in more detail. Figure 8 is an explanatory diagram showing a specific embodiment of the present invention targeted at P-type disaster prevention equipment in which a sensor 12 is provided with a signal detection unit 16 that uses the one-wavelength, two-scattering angle system.

As shown in Figure 8, the P-type disaster prevention system of this embodiment includes a receiver 10 and a plurality of sensors 12. The configurations of the receiver 10 and sensors 12 are basically the same as those of the disaster prevention system of Figure 2, but differ in that the signal detection unit 16 of the sensors 12 is configured to support the one-wavelength, two-scattering angle method. The signal detection unit 16 of the sensor 12 includes a light-emitting element 30, a second light-receiving element 34 , and a third light-receiving element 36.

(g1 . First smoke detector structure using one wavelength and two scattering angles)
The structure of the first smoke detector of the one wavelength, two scattering angles system will now be described in more detail. Figure 9(A) shows the structure of the first smoke detector of the one wavelength, two scattering angles system, which corresponds to the signal detector 16 of Figure 8, and which comprises a light-emitting element 30, a second light-receiving element 34 , and a third light-receiving element 36, and which is a simplified structure obtained by removing the first light-emitting element 32 from the first smoke detector of the one wavelength, three scattering angles system shown in Figure 3(A).

In the signal detection unit 16, which has a first smoke detection unit structure using the one-wavelength, two-scattering angle method, the light-emitting element 30 is driven to emit light at a predetermined cycle by the light-emitting element driver 38 shown in Figure 8, and the light-receiving signals from the second and third light-receiving elements 34, 36 are amplified by the light-receiving amplifiers 42, 44 and then sequentially read by the sensor control unit 24 via A/D conversion.

The light-emitting element 30 emits light with a wavelength λ of 900 nm, which is a near-infrared wavelength, for example. The second and third light-receiving elements 34, 36 use photodiodes PD that are sensitive from the infrared region to the visible light region.

As the first optical setting of the signal detection unit 16, the second light receiving element 34 is set to a backscattering angle of, for example, θ2 = 110°. When light from the light emitting element 30 is irradiated onto smoke that has flowed into point P, a backscattering detection signal is output by receiving scattered light from the smoke corresponding to a scattering angle θ2 = 110°. This signal is amplified by the light receiving amplifier 42, A/D converted, and read by the sensor control unit 24, thereby detecting a backscattering detection value A2 corresponding to the smoke concentration.

Furthermore, as the second optical setting of the signal detection unit 16, the third light receiving element 36 is positioned at a scattering angle θ3 = 90°. When light from the light emitting element 30 is irradiated onto smoke that has flowed into point P, a 90° scattering detection signal is output by receiving scattered light from the smoke corresponding to a scattering angle θ3 = 90°. This signal is amplified by the light receiving amplifier 44, A/D converted, and read by the sensor control unit 24, thereby detecting a 90° scattering detection value A3 corresponding to the smoke concentration.

(g2. Secondary smoke detector structure using one wavelength, two scattering angles method)
The second smoke detector structure of the one wavelength, two scattering angles system will be described in more detail below. Figure 9(B) shows a second smoke detector structure of the one wavelength, two scattering angles system that can be replaced with Figure 9(A), and includes a light receiving element 60, a second light emitting element 64, and a third light emitting element 66. This structure is a simplified version of the second smoke detector structure of the one wavelength, three scattering angles system shown in Figure 3(B) by removing the first light emitting element 32.

The second and third light-emitting elements 64, 66 are driven to emit light sequentially at a predetermined cycle, and the light-receiving signal from the light-receiving element 60 is amplified and then sequentially read by the sensor control unit 24 through A/D conversion synchronized with the light emitted by the second and third light-emitting elements 64, 66.

The second and third light-emitting elements 64, 66 are near-infrared LEDs that emit light with a near-infrared wavelength of, for example, λ = 900 nm. The light-receiving element 60 is a photodiode PD that is sensitive from the infrared region to the visible light region.

In the first optical setting of the signal detection unit 16, the second light-emitting element 64 is positioned so that when it irradiates point P with light, the light-receiving element 60 receives scattered light obtained at a scattering angle θ2 = 110°, for example. A backscatter detection signal is output from the light-receiving element 60, and a backscatter detection value A2 corresponding to the smoke concentration is detected.

Furthermore, as a second optical setting of the signal detection unit 16, the third light-emitting element 66 is positioned so that when light is irradiated onto point P, the light-receiving element 60 receives the scattered light obtained at a scattering angle θ3 = 90°, a 90° scattering detection signal is output from the light-receiving element 60, and a 90° scattering detection value A3 corresponding to the smoke concentration is detected.

(g3. Identification unit for one wavelength and two scattering angles)
The one-wavelength, two-scattering-angle type discrimination unit 18 will be described in more detail below. The discrimination unit 18 discriminates a fire as a silane gas fire when discrimination conditions corresponding to Rayleigh scattering are met based on the backscatter detection value A2 and the 90° scattering detection value A3 detected by the signal detection unit 16, and also discriminates whether a smoke-emitting fire is a white smoke fire or a black smoke fire.

Figure 10(A) shows in table format the ratio R = A2/A3 of the backscattering detection value A2 and the 90° scattering detection value A3 in Figure 6(A), with R = 0.71 for white smoke, R = 1.01 for black smoke, and R = 1.11 for silicon oxide. Based on these, the discrimination unit 18 sets the discrimination conditions for white smoke, black smoke, and silicon oxide as shown in Figure 10(B), with Rth1 = 0.8 as the first threshold value Rth1 for discriminating between white smoke and black smoke, and Rth2 = 1.1 as the second threshold value Rth2 for discriminating between white smoke or black smoke generated in smoke fires and silicon oxide generated in silane gas fires. As a result, the identification unit 18 identifies a white smoke fire when the ratio R is Rth1 = 0.8 or less, as the smoke is white; when the ratio R is in the range of Rth1 = 0.8 to Rth2 = 1.1, as the smoke is black, as the fire is black; and further, when the ratio R is Rth2 = 1.1 or more, as the smoke is silicon oxide, as the fire is silane gas.

The discrimination unit 18 can arbitrarily discriminate between white smoke fires, black smoke fires, and silane gas fires. In addition to the ratio R=R2/R3 between the backscatter detection value A2 and the 90° scattering detection value A3, it can also calculate the ratio R=A1/A3 between the forward scattering detection value A1 and the 90° scattering detection value A3, or the ratio R=A1/A2 between the forward scattering detection value A1 and the backscatter detection value A2. If the specified discrimination conditions corresponding to white smoke are met, the discrimination unit 18 discriminates as a white smoke fire. If the specified discrimination conditions corresponding to black smoke are met, the discrimination unit 18 discriminates as a black smoke fire. Furthermore, if the silicon oxide discrimination conditions corresponding to Rayleigh scattering are met, the discrimination unit 18 discriminates as a silane gas fire. The detection output unit 20 for the one-wavelength, two-scattering angle method is the same as that for the one-wavelength, three-scattering angle method described above, and therefore its description is omitted.

[h. Two-wavelength, two-scattering angle embodiment]
Figure 11 is an explanatory diagram showing a specific embodiment of the present invention directed to a P-type disaster prevention system in which a detector is provided with a signal detection unit that uses a dual-wavelength, dual-scattering angle system. As shown in Figure 11, the P-type disaster prevention system of this embodiment includes a receiver 10 and multiple detectors 12. The configurations of the receiver 10 and detectors 12 are basically the same as those of the disaster prevention system of Figure 2, except that the signal detection unit 16 of the detector 12 is configured to support the dual-wavelength, dual-scattering angle system. The signal detection unit 16 of the detector 12 is provided with a light-receiving element 90, a first light-emitting element 92, and a second light-emitting element 94.

(h1. Signal detection unit using the two-wavelength, two-scattering angle method)
The dual wavelength, dual scattering angle signal detection unit 16 will now be described in more detail. In order to prominently display the characteristics of Rayleigh scattering caused by silicon oxide that occurs in a silane gas fire, the dual wavelength, dual scattering angle signal detection unit 16 provided in the detector 12 uses a shorter wavelength for detecting backscattering detection value A2 than for detecting forward scattering detection value A1, thereby improving the ability to distinguish between silicon oxide based on forward scattering detection value A1 and backscattering detection value A2.

(h2. Two-wavelength, two-scattering angle smoke detector structure)
The structure of the smoke detector employing the dual wavelength and dual scattering angle system will now be described in more detail. Figure 12 shows the structure of the smoke detector employing the dual wavelength and dual scattering angle system, corresponding to the signal detector 16 shown in Figure 11. A light-receiving element 90, a first light-emitting element 92, and a second light-emitting element 94 are arranged within the smoke detector 58, with their optical axes aligned in the same plane. The first and second light-emitting elements 92, 94 are sequentially driven to emit light at predetermined intervals by light-emitting element drivers 38a, 38b. The light-receiving signal from the light-receiving element 90 is amplified by the light-receiving amplifier 40 and then sequentially read by the sensor controller 24 through A/D conversion synchronized with the light emitted by the first and second light-emitting elements 92, 94.

The first and second light-emitting elements 92, 94 are near-infrared LEDs. The first light-emitting element 92 emits light of a predetermined first wavelength λ1, for example, λ1 = 900 nm. In contrast, the second light-emitting element 94 emits light of a predetermined second wavelength λ2, for example, λ2 = 500 nm, which is shorter than the wavelength λ1 of the first light-emitting element 92. The light-receiving element 90 is a photodiode PD that is sensitive to wavelengths from 400 nm to 1000 nm in the infrared to visible light range.

In the first optical setting of the signal detection unit 16, the first light-emitting element 92 is positioned so that when light of a first wavelength λ1 = 900 nm is irradiated onto point P where the optical axis of the first light-emitting element 92 intersects with the optical axis of the light-receiving element 90, the light-receiving element 90 receives the scattered light obtained at a scattering angle θ1, where the scattering angle θ1 is set to a predetermined angle other than 90°, for example, a forward scattering angle of θ1 = 40°. When the light of the first wavelength λ1 = 900 nm emitted by the first light-emitting element 92 is irradiated onto smoke that has flowed into point P, the scattered light (forward scattered light) from the smoke corresponding to the scattering angle θ1 = 40° is incident on and received by the light-receiving element 90, which then outputs a forward scattering detection signal as a received light signal and detects a forward scattering detection value A1 corresponding to the smoke concentration.

In addition, as a second optical setting of the signal detection unit 16, the second light-emitting element 94 is positioned so that when light of a second wavelength λ2 = 500 nm is irradiated onto point P where its optical axis intersects with the optical axis of the light-receiving element 60, the light-receiving element 90 receives the scattered light obtained at a scattering angle θ2, where the scattering angle θ2 is set to a predetermined angle other than 90°, for example, a backscattering angle of θ2 = 120°. When light of a second wavelength λ2 = 500 nm is irradiated onto smoke that has flowed into point P by the emission of the second light-emitting element 64, the scattered light (backscattered light) from the smoke corresponding to the scattering angle θ2 = 120° is incident on and received by the light-receiving element 60, a backscatter detection signal is output as a light-receiving signal, and a backscatter detection value A2 corresponding to the smoke concentration is detected.

(h3. Two-wavelength, two-scattering angle type identification unit)
The dual-wavelength, dual-scattering angle discrimination unit 18 will now be described in more detail. Based on the forward scattering detection value A1 at a first wavelength λ1 = 900 nm and a scattering angle θ1 = 30° and the backscattering detection value A2 at a second wavelength λ2 = 500 nm and a scattering angle θ2 = 120° detected by the signal detection unit 16, the discrimination unit 18 discriminates that the detected object is silicon oxide and therefore a silane gas fire if the discrimination conditions corresponding to Rayleigh scattering are met, and discriminates that the detected object is a white smoke fire due to white smoke from a smoke fire or a black smoke fire due to black smoke if the discrimination conditions corresponding to Rayleigh scattering are not met.

Figure 13 (A) shows in table format the scattering intensity of the forward scattering detection value A1 for white smoke, black smoke, and silicon oxide at a first wavelength λ1 = 900 nm and a scattering angle θ1 = 30° in Figure 12, and Figure 13 (B) shows in table format the scattering intensity of the back scattering detection value A2 for white smoke, black smoke, and silicon oxide at a second wavelength λ2 = 500 nm and a scattering angle θ2 = 120° in Figure 12.

The discrimination unit 18 calculates the ratio R between the multiplication value (λ1·A1) of the first wavelength λ1 and the forward scattering detection value A1 and the multiplication value (λ2·A2) of the second wavelength λ2 and the backscattering detection value A2 as follows: R=(λ1·A1)/(λ2·A2)
When the ratio R satisfies the discrimination condition corresponding to Rayleigh scattering, the discrimination unit 18 discriminates that the fire is a silane gas fire because it is silicon oxide. Furthermore, when the ratio R satisfies the discrimination condition of white smoke or black smoke of a smoke-emitting fire corresponding to a composite scattering that combines Rayleigh scattering and Mie scattering, the discrimination unit 18 discriminates that the fire is a white smoke fire or a black smoke fire.

(h4. Identification of combustion products)
13(C) shows in table form the ratio R of the multiplication value of the first wavelength λ1 and the forward scattering detection value A1 in FIG. 13(A) and the multiplication value of the second wavelength λ2 and the backscattering detection value A2 in FIG. 13(B), where R = 8.0 for white smoke, R = 2.3 for black smoke, and R = 0.1 for silicon oxide. Based on these, as the discrimination conditions for white smoke, black smoke, and silicon oxide, the discrimination unit 18 sets Rth1 = 5 as the first threshold value Rth1 for discriminating between white smoke and black smoke, and also sets Rth2 = 1 as the second threshold value Rth2 for discriminating between smoke generated in smoke fires including white smoke and black smoke and silicon oxide generated in silane gas fires, as shown in FIG. 13(D). Therefore, when the ratio R is Rth1=5 or more, the identification unit 18 identifies that the detected object is white smoke and therefore a white smoke fire; when the ratio R is in the range of Rth2=1 to Rth1=5, the identification unit 18 identifies that the detected object is black smoke and therefore a black smoke fire; and further, when the ratio R is Rth2=1 or less, the identification unit 18 identifies that the detected object is silicon oxide and therefore a silane gas fire.

In this way, in the two-wavelength, two-scattering angle identification unit 18, the scattering angle relative to the detection target is varied between a forward scattering angle θ1 = 30° and a backward scattering angle θ2 = 120°, thereby creating differences in scattering characteristics due to the scattering angle. At the same time, the wavelength of the light irradiated onto the detection target is varied between a first wavelength λ1 = 900 nm and a second wavelength λ2 = 500 nm, thereby creating differences in scattering characteristics due to the wavelength. The synergistic effect of these differences in scattering angle and wavelength results in the scattering intensity of the light scattered by silicon oxide that occurs in silane gas fires. This creates a significant difference in the intensity of scattered light from the white and black smoke produced by smoke-emitting fires, and furthermore, the discrimination unit 18 calculates the ratio R of the multiplication value (λ1·A1) of the first wavelength λ1 and the forward scattering detection value A1 to the multiplication value (λ2·A2) of the second wavelength λ2 and the backward scattering detection value A2, rather than the ratio of the forward scattering detection value A1 and the backward scattering detection value A2. This reflects the differences due to the wavelength ratio (λ1/λ2), further improving the ability to discriminate between silane gas fires caused by silicon oxide, white smoke fires caused by white smoke, and black smoke fires caused by black smoke.

(h5. Rayleigh scattering and wavelength)
Silicon oxide particles generated as monodisperse particles in silane gas fires have particle sizes ranging from approximately 50 nm to 60 nm, which are smaller than the wavelength of the irradiated light, 900 nm or 500 nm, and therefore cause Rayleigh scattering. Here, the relationship between the scattering intensity I and the wavelength λ in Rayleigh scattering is such that the scattering intensity I is inversely proportional to the fourth power of the wavelength λ.
I∝1/ ^λ4
Therefore, the detected value A2 of backscattering at wavelength λ2=500 nm is given by the following equation for the detected value A1 of forward scattering at wavelength λ1=900 nm:
1/(λ1/λ2) ⁴ =1/(900/500) ⁴
The significant difference in scattering intensity due to differences in wavelength and scattering angle makes it possible to improve the ability to identify silicon oxide, which is the detection target.

The discrimination between white smoke, black smoke, and silicon oxide by the dual-wavelength, dual-scattering angle discrimination unit 18 can be arbitrarily determined. In addition to the ratio R = (λ1·A1/λ2·A2), it is also possible to calculate the ratio R = (λ1·A1/λ2·A3) of the multiplication value of the first wavelength λ1 and the forward scattering detection value A1 to the multiplication value of the second wavelength λ2 and the 90° scattering detection value A3, or the ratio R = (λ1·A2/λ2·A3) of the multiplication value of the first wavelength λ1 and the backward scattering detection value A2 to the multiplication value of the second wavelength λ2 and the 90° scattering detection value A3, and to identify a white smoke fire if the specified discrimination conditions corresponding to white smoke are met, identify a black smoke fire if the specified discrimination conditions corresponding to black smoke are met, and further identify a silane gas fire if the silicon oxide discrimination conditions corresponding to Rayleigh scattering are met. Furthermore, the detection output unit 18 for the two-wavelength, two-scattering angle method is the same as that for the one-wavelength, three-scattering angle method described above, so its description is omitted.

[i. Other basic concepts of the embodiment]
Figure 14 is an explanatory diagram showing another basic concept of an embodiment corresponding to the second disaster prevention equipment, in which a fire alarm system is an example of the second disaster prevention equipment equipped with a receiver 10 and a sensor 12, in which the sensor 12 is provided with a signal detection unit 16 of the fire detection device, and the receiver 10 is provided with an identification unit 18 and a detection output unit 20 of the fire detection device.

The signal detection unit 16 of the detector 12 and the discrimination unit 18 and detection output unit 20 of the receiver 10 are basically the same as the signal detection unit 16, discrimination unit 18, and detection output unit 20 provided in the detector 12 in Figure 1, except that the forward scattering detection value A1, back scattering detection value A2, and 90° scattering detection value A3 detected by the signal detection unit 16 of the detector 12 are transmitted to the receiver 10 via the transmission line 114, and the discrimination unit 18 and detection output unit 20 of the receiver 10 detect a fire if a discrimination result of a silane gas fire, white smoke fire, or black smoke fire is obtained and the specified fire detection conditions are met, and the discrimination result is output along with the fire.

[j. R-type disaster prevention equipment]
An embodiment corresponding to the second disaster prevention equipment will be described in more detail. Figure 15 is an explanatory diagram of an R-type (Record-type) disaster prevention equipment showing the specific contents of the embodiment corresponding to Figure 14. Here, the "R-type disaster prevention equipment" is equipment that monitors fires for each detector 12 (for each detector) by transmitting between the receiver 10 and the detector 12.

As shown in Figure 15, the R-type disaster prevention equipment of this embodiment includes a receiver 10 and a sensor 12, with the sensor 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 sensor 12 and transmits and receives signals between the receiver 10 and the sensor 12 using a specified transmission method. A dedicated power supply line may also be provided.

(j1. Sensor)
The detector 12 of the R-type disaster prevention system will now be described in more detail. Like the detector 12 of the P-type disaster prevention system shown in Fig. 2, the detector 12 of the R-type disaster prevention system includes a signal detection unit 16 having a first smoke detection unit structure using the one-wavelength, three-scattering-angle method shown in Fig. 3(A), a detector control unit 24, a power supply unit 28, a light-emitting driver unit 38, and light-receiving amplifier units 40, 42, and 44. However, the detector 12 differs in that it includes a transmitter unit 86 for transmitting and receiving signals to and from the receiver 10 using a predetermined transmission method. Furthermore, the detector control unit 24 does not include the functions of the identification unit 18 and detection output unit 20, which are components of the fire detection device of the present invention shown in Fig. 2; these functions are provided on the receiver 10 side.

(j2. Receiver)
The receiver 10 of the R-type disaster prevention system will now be described in more detail. Like the receiver 10 of the P-type disaster prevention system shown in Figure 2, the receiver 10 of the R-type disaster prevention system includes a receiver control unit 46, a display unit 50, an operation unit 52, an alarm unit 54, and a reporting unit 56. However, it differs in that it includes a transmission unit 88 for transmitting and receiving signals to and from the detector 12 using a predetermined transmission method. It also differs in that the receiver control unit 46 includes an identification unit 18 and a detection output unit 20, which are components of the fire detection device of the present invention, as functions realized by executing a program. The identification unit 18 and detection output unit 20 provided in the receiver 10 are essentially the same as the identification unit 18 and detection output unit 20 provided in the detector 12 of the P-type disaster prevention system shown in Figure 2.

(j3. Transmission Control)
The transmission control of the R-type disaster prevention system will be described in more detail. In the R-type disaster prevention system, a unique address is assigned to each of the sensors 12, and the receiver 10 transmits a batch A/D conversion command signal at a predetermined interval, for example, every minute. All of the sensors 12 that receive the batch A/D conversion command signal receive scattered light at different scattering angles in their signal detection units 16, and then A/D convert and store the forward scattering detection value A1, back scattering detection value A2, and 90° scattering detection value A3. The receiver 10 then transmits a call signal sequentially specifying the sensor addresses, thereby polling the sensors 12 and causing them to return response signals including the forward scattering detection value A1, back scattering detection value A2, and 90° scattering detection value A3.

(j4. Receiver Identification Unit)
The identification unit 18 of the receiver 10 will be described in more detail. The identification unit 18 of the receiver 10 is similar to the identification unit 18 of the detector 12 installed in the P-type disaster prevention equipment described above. Each time the forward scattering detection value A1, the backscattering detection value A2, and the 90° scattering detection value A3 are received from each detector 12 by polling, if the identification condition corresponding to Rayleigh scattering at which the 90° scattering detection value A3 is a minimum is met, the detection target is silicon oxide, and therefore a silane gas fire is identified. Furthermore, if the identification condition corresponding to Rayleigh scattering at which the 90° scattering detection value A3 is a minimum is not met, the detection target is white smoke or black smoke generated by a smoke-emitting fire, and therefore a white smoke fire or a black smoke fire is identified.

(J5. Receiver detection output section)
The detection output unit 20 of the receiver 10 will be described in more detail below. When the identification unit 18 identifies a silane gas fire, the detection output unit 20 of the receiver 10 specifies the detector address corresponding to the identification result of the silane gas fire, centrally acquires the forward scattering detection value A1, the back scattering detection value A2, and the 90° scattering detection value A3, and when the fire detection condition is met, for example, when the forward scattering detection value A1 is equal to or exceeds a predetermined threshold value of 0.1 (%/m), outputs an identification result indicating that a silane gas fire has been identified along with the fire, and performs fire alarm processing including sounding a main acoustic alarm and a district acoustic alarm, displaying the location of the fire and the silane gas fire based on the detector address that determined the fire, and interlocking control of smoke control and exhaust equipment.

Furthermore, when the identification unit 18 identifies a white smoke fire or a black smoke fire, the detection output unit 20 of the receiver 10 specifies the detector address corresponding to the identification result of a white smoke fire or a black smoke fire, and intensively acquires the forward scattering detection value A1, the back scattering detection value A2, and the 90° scattering detection value A3.For example, if the forward scattering detection value A1 satisfies the fire detection condition of being equal to or exceeding a predetermined threshold value of 10 (%/m), the detection output unit 20 outputs the identification result of a white smoke fire or a black smoke fire along with the fire, and performs fire alarm processing including sounding the main acoustic alarm and the district acoustic alarm, displaying the location of the fire and whether it is a white smoke fire or a black smoke fire based on the detector address that determined it to be a fire, and interlocking control of smoke control and exhaust equipment.

(j6. Control operation of R-type disaster prevention equipment)
The control operation of the R-type disaster prevention equipment will be described in more detail below. Fig. 16 is a flowchart showing the control operation of the embodiment of the R-type disaster prevention equipment in Fig. 15 in the form of a time chart.

As shown in FIG. 16, in step S11, 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 S12, the detector 12 performs a fire monitoring response process by receiving a batch A/D conversion command signal from the receiver 10, storing and retaining the forward scattering detection value A1, back scattering detection value A2, and 90° scattering detection value A3 obtained at that time, and then, upon receiving a call signal specifying its own address, transmits a response signal including the forward scattering detection value A1, back scattering detection value A2, and 90° scattering detection value A3 in step S13.

Next, in step S14, the receiver 10 receives the forward scattering detection value A1, backscattering detection value A2, and 90° scattering detection value A3 from the detector 12. If the receiver 10 determines, based on the received forward scattering detection value A1, backscattering detection value A2, and 90° scattering detection value A3, that the silicon oxide identification condition corresponding to Rayleigh scattering, where the 90° scattering detection value A3 is at its minimum, is met, the receiver 10 proceeds to step S26 and identifies the fire as a silane gas fire. If the receiver 10 determines in step S25 that the 90° scattering detection value A3 is not at its minimum, the receiver 10 proceeds to step S27 and identifies the fire as a white smoke fire or a black smoke fire, for example, based on the ratio R of the backscattering detection value A2 and the 90° scattering detection value A3.

If a silane gas fire is identified in step S16, or if a white smoke fire or black smoke fire is identified in step S17, the process proceeds to step S18, where an A/D conversion command signal specifying the address of the detector 12 corresponding to the identification result and a call signal are transmitted. In response, the detector 12 transmits the forward scattering detection value A1, the back scattering detection value A2, and the 90° scattering detection value A3 in step S19, and the receiver 10 performs a process of intensively receiving the forward scattering detection value A1, the back scattering detection value A2, and the 90° scattering detection value A3.

Next, if the receiver 10 determines in step S20 that the forward scattering detection value A1 satisfies the predetermined fire detection conditions corresponding to the identified silane gas fire, white smoke fire, or black smoke fire, it proceeds to step S21 and performs fire alarm processing, including sounding the main acoustic alarm and local acoustic alarm, displaying the location of the fire based on the address of the detector that determined it to be a fire, outputting an indication that a silane gas fire, white smoke fire, or black smoke fire has been detected, and controlling the linkage of smoke prevention and exhaust equipment.

Next, if the receiver 10 determines in step S22 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 S23 and returns to the fire monitoring transmission processing in step S11. Furthermore, if the detector 12 determines in step S24 that it has received a recovery signal, it returns to the fire monitoring response processing in step S12.

Note that the R-type disaster prevention equipment shown in Figure 15 uses a fire detection device with a one-wavelength, three-scattering angle system as an example, but the one-wavelength, two-scattering angle or two-wavelength, two-scattering angle fire detection devices described for the P-type disaster prevention equipment may also be applied.

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

(phosphine gas)
The above embodiment uses silane gas as an example of a semiconductor manufacturing gas that reacts with oxygen in the atmosphere and burns. However, phosphine gas _PH3 can also be detected. Phosphine gas _PH3 is toxic, and it is stipulated that in the event of a fire, fire extinguishing should not be attempted unless the leak is stopped. Powder fire extinguishing agents, foam fire extinguishing agents, and _CO2 are used. Since there is a risk of toxic gas being generated by violently reacting with water, water should not be used in the initial stage of fire extinguishing. Therefore, like silane gas, fire extinguishing activities must be carried out separately from smoke fires.

Phosphine gas _PH3 reacts with oxygen in the air and burns violently, with the _chemical reaction formula being _8PH3 + _8O2 → _P4O10 + _6H2O
The P ₄ O ₁₀ produced as monodisperse particles in the combustion of phosphine gas has a particle size in the range of, for example, approximately 50 nm to 60 nm, and exhibits Rayleigh scattering because it is a particle size smaller than the wavelength of the irradiated light, and similarly to silicon oxide SiO ₂ produced in a silane gas fire, the above embodiment identifies a phosphine gas fire from the P ₄ O ₁₀ produced in the combustion of phosphine gas, and outputs to the outside an identification result indicating that a phosphine gas fire has been identified along with the fire.

Furthermore, the above-described embodiments are not limited to silane gas fires or phosphine gas fires, but can be applied to identifying fires involving the combustion products of any gas or chemical that reacts with oxygen in the atmosphere and burns.

(Identification of non-fire factors)
The identification unit 18 in the above embodiment identifies silicon oxide in silane gas fires and white and black smoke in smoke fires, but may also be configured to identify non-fire factors. "Non-fire factors" are particles that should not be detected as fires, and include, for example, oily smoke, steam, vapor, dust, cigarette smoke, and the like that are generated by factors other than fires.

Steam and vapor, which are non-fire factors, have larger particle sizes than white smoke, and therefore have a higher scattering intensity at forward scattering angles than white smoke during a fire. For example, when irradiated with light of a wavelength of 900 nm, the forward scattering detection value A1 of scattered light at a scattering angle of 40° is sufficiently large, and the ratio R of the forward scattering detection value A2 of scattered light at a scattering angle of 110° is even larger than the ratio for white smoke. For this reason, the identification unit 18 will identify the detected object as a non-fire factor, such as steam or vapor, if, for example, the ratio R of the forward scattering detection value A1 to the backward scattering detection value A2 satisfies a specified non-fire identification condition. If the identification unit 18 identifies the detected object as a non-fire factor, the detection output unit 20 will not output a signal indicating that a fire has been detected, even if the forward scattering detection value A1 satisfies the specified fire detection condition, thereby preventing the generation of a non-fire alarm.

(fire alarm)
Although the above embodiment has been described as an example of a fire detection device for disaster prevention equipment equipped with a receiver and a sensor, a residential fire alarm equipped with a means for detecting a fire from smoke density and a means for issuing a fire alarm may also be configured as a fire detection device. 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, and the detection output unit 20 that constitute the fire detection device, similar to the sensor 12 of the disaster prevention equipment shown in Figures 1 and 2.

(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: Sensor 14: Signal line 16: Signal detection unit 18: Identification unit 20: Detection output unit 24: Sensor control unit 26: Alarm circuit unit 28: Power supply unit 30: Light emitting element 32: First light receiving element 34: Second light receiving element 36: Third light receiving element 38, 38a, 38b: Light emitting driver unit 40, 42, 44: Light receiving amplifier unit 46: Receiver control unit 48: Line receiving unit 50: Display unit 52: Operation unit 54: Alarm unit 56: Alarm transfer unit
58: Smoke Detection Department
60: Light receiving element 62 , 92 : First light emitting element 64 , 94 : Second light emitting element 66: Third light emitting element 80: White smoke characteristics 82: Black smoke characteristics 84: Silicon oxide characteristics 86, 88: Transmission section 114: Transmission line

Claims (29)

A fire detection device that detects smoke-generating fires and semiconductor manufacturing gas fires that produce monodispersed particles based on the characteristics of scattered light from combustion products in a monitored area where semiconductor manufacturing gases are used, and distinguishes between the two types of fire.
2. The fire detection device according to claim 1,
A fire detection device characterized in that, when it identifies a smoke-generating fire or a semiconductor manufacturing gas fire, it outputs the identification result along with the fire.
A disaster prevention facility using the fire detection device according to claim 2 ,
A disaster prevention system characterized in that control for preventing, suppressing, or extinguishing a fire is changed depending on the identification result of the fire detection device.
The disaster prevention equipment according to claim 3,
This fire prevention equipment is characterized in that, when the identification result of the fire detection device is a semiconductor manufacturing gas fire, the control is to stop the supply of the semiconductor manufacturing gas and/or release an inert gas into the fire area.
A fire detection device for detecting a fire in a monitored area where semiconductor manufacturing gases are used ,
a signal detection unit that irradiates light onto a detection target in the monitoring area that involves optical action, and detects a plurality of detection signals based on scattered light received at different scattering angles;
an identification unit that identifies whether the fire is a smoke-generating fire that generates smoke or a semiconductor manufacturing gas fire that generates monodisperse particles based on the intensity distribution of the multiple detection signals detected by the signal detection unit;
a detection output unit that outputs the identification result together with the fire to the outside when any of the plurality of detection signals satisfies a predetermined fire detection condition in a state where the identification unit has identified the fire as the smoke fire or the semiconductor manufacturing gas fire;
A fire detection device comprising:
The fire detection device according to claim 1, 2 or 5 and the disaster prevention equipment according to claim 3 or 4,
A disaster prevention facility or fire detection device for monitoring an area where silane gas or phosphine gas is used as the semiconductor manufacturing gas.
6. The fire detection device according to claim 5,
The signal detection unit detects a signal associated with an optical action of the detection object by at least a first optical setting, a second optical setting, and a third optical setting,
As the first optical setting, the detection object is irradiated with light of a predetermined wavelength, and a light reception signal of scattered light obtained at a predetermined forward scattering angle smaller than 90° is detected as a forward scattering detection signal;
In the second optical setting, the detection target is irradiated with light of the predetermined wavelength, and a light reception signal of scattered light obtained at a predetermined backscattering angle greater than 90° is detected as a backscattering detection signal;
As the third optical setting, the detection object is irradiated with light of the predetermined wavelength, and a light receiving signal of scattered light obtained at a scattering angle of 90° is detected as a 90° scattering detection signal;
the identification unit identifies the occurrence of a semiconductor manufacturing gas fire when a predetermined identification condition corresponding to Rayleigh scattering in which the 90° scattering detection signal has a minimum value is satisfied based on the forward scattering detection signal, the back scattering detection signal, and the 90° scattering detection signal detected by the signal detection unit;
A fire detection device characterized in that, when the identification unit has identified a semiconductor manufacturing gas fire and the specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs the identification result that it is a semiconductor manufacturing gas fire to the outside along with the fire.
8. The fire detection device according to claim 7,
the identification unit identifies the fire as being smoke-generating when a predetermined identification condition corresponding to Rayleigh scattering in which the 90° scattering detection signal has a minimum value is not satisfied based on the forward scattering detection signal, the backward scattering detection signal, and the 90° scattering detection signal detected by the signal detection unit;
The fire detection device is characterized in that, when the identification unit has identified a smoke-generating fire and other specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal, the detection output unit outputs the identification result of the smoke-generating fire along with the fire to the outside.
6. The fire detection device according to claim 5,
The signal detection unit
a light emitting unit that irradiates the detection target with light of a predetermined wavelength;
a first light receiving unit that receives scattered light obtained at a forward scattering angle when the detection target is irradiated with light of the predetermined wavelength and outputs a forward scattering detection signal;
a second light receiving unit that receives scattered light obtained at a backscattering angle when the detection target is irradiated with light of the predetermined wavelength and outputs a backscattering detection signal;
a third light receiving unit that receives scattered light obtained at a scattering angle of 90° when the detection target is irradiated with light of the predetermined wavelength and outputs a 90° scattering detection signal;
A fire detection device comprising:
6. The fire detection device according to claim 5,
The signal detection unit
a light receiving unit that receives scattered light of a predetermined wavelength irradiated onto the detection target and outputs a forward scattering detection signal, a backward scattering detection signal, or a 90° scattering detection signal;
a first light emitting unit that irradiates the detection target with light of the predetermined wavelength so that scattered light at a forward scattering angle is incident on the light receiving unit and the forward scattering detection signal is output;
a second light emitting unit that irradiates the detection target with light of the predetermined wavelength so that scattered light at a backscattering angle is incident on the light receiving unit and the backscattering detection signal is output;
a third light emitting unit that irradiates the detection target with light of the predetermined wavelength so that scattered light at a scattering angle of 90° is incident on the light receiving unit and the 90° scattering detection signal is output;
A fire detection device comprising:
6. The fire detection device according to claim 5,
The signal detection unit detects a signal associated with an optical action of the detection target by at least a first optical setting and a second optical setting,
As the first optical setting, the detection target is irradiated with light of a predetermined wavelength, and a light reception signal of scattered light obtained at a predetermined forward scattering angle smaller than 90° is detected as a forward scattering detection signal, or a light reception signal of scattered light obtained at a predetermined backward scattering angle larger than 90° is detected as a backward scattering detection signal,
As the second optical setting, the detection object is irradiated with light of the predetermined wavelength, and a light receiving signal of scattered light obtained at a scattering angle of 90° is detected as a 90° scattering detection signal;
the identification unit identifies the semiconductor manufacturing gas fire when a ratio between the forward scattering detection signal and the 90° scattering detection signal or a ratio between the back scattering detection signal and the 90° scattering detection signal satisfies a predetermined identification condition corresponding to Rayleigh scattering,
A fire detection device characterized in that, when the identification unit has identified a semiconductor manufacturing gas fire and the specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal , the detection output unit outputs the identification result that it is a semiconductor manufacturing gas fire along with the fire to the outside.
12. The fire detection device according to claim 11,
the identification unit identifies the fire as a smoke-generating fire when a ratio between the forward scattering detection signal and the 90° scattering detection signal or a ratio between the back scattering detection signal and the 90° scattering detection signal satisfies a predetermined identification condition corresponding to the smoke,
The fire detection device is characterized in that, when the identification unit has identified a smoke-generating fire and other specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal , the detection output unit outputs the identification result of the smoke-generating fire along with the fire to the outside.
The fire detection device according to claim 8 or 12,
the identification unit identifies a white smoke fire when a ratio between the forward scattering detection signal and the 90° scattering detection signal or a ratio between the back scattering detection signal and the 90° scattering detection signal satisfies a predetermined identification condition corresponding to white smoke, and identifies a black smoke fire when a predetermined identification condition corresponding to black smoke is satisfied;
The fire detection device is characterized in that, when the identification unit has identified a white smoke fire and other predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal , the detection output unit outputs to the outside the identification result that the fire is the white smoke fire along with the fire, and when the identification unit has identified a black smoke fire and other predetermined fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal , the detection output unit outputs to the outside the identification result that the fire is the black smoke fire along with the fire.
12. The fire detection device according to claim 11,
The signal detection unit
a light emitting unit that irradiates the detection target with light of the predetermined wavelength;
a first light receiving unit that receives scattered light obtained at the forward scattering angle when the detection target is irradiated with light of the predetermined wavelength and outputs the forward scattering detection signal, or a second light receiving unit that receives scattered light obtained at the backward scattering angle when the detection target is irradiated with light of the predetermined wavelength and outputs the backward scattering detection signal;
a third light receiving unit that receives scattered light obtained at the scattering angle of 90° when the detection target is irradiated with light of the predetermined wavelength and outputs the 90° scattering detection signal;
A fire detection device comprising:
12. The fire detection device according to claim 11,
The signal detection unit
a light receiving unit that receives scattered light of the predetermined wavelength irradiated onto the detection target and outputs the forward scattering detection signal and the 90° scattering detection signal, or the back scattering detection signal and the 90° scattering detection signal;
a first light-emitting unit that irradiates the detection target with light of the predetermined wavelength so that scattered light at the forward scattering angle is incident on the light-receiving unit and the forward scattering detection signal is output, or a second light-emitting unit that irradiates the detection target with light of the predetermined wavelength so that scattered light at the backward scattering angle is incident on the light-receiving unit and the backward scattering detection signal is output;
a third light emitting unit that irradiates the detection target with light of the predetermined wavelength so that scattered light at the scattering angle of 90° is incident on the light receiving unit and the 90° scattering detection signal is output;
A fire detection device comprising:
6. The fire detection device according to claim 5,
The signal detection unit detects a signal associated with an optical action of the detection object by at least a first optical setting and a second optical setting,
As the first optical setting, the detection target is irradiated with light of a predetermined first wavelength, and a light reception signal of scattered light obtained at a predetermined forward scattering angle is detected as a forward scattering detection signal;
As the second optical setting, the detection target is irradiated with light of a predetermined second wavelength different from the first wavelength, and a light reception signal of scattered light obtained at a predetermined backscattering angle is detected as a backscattering detection signal;
the identification unit identifies the semiconductor manufacturing gas fire when a ratio between a multiplication value of the first wavelength and the forward scattering detection signal and a multiplication value of the second wavelength and the back scattering detection signal satisfies a predetermined identification condition corresponding to Rayleigh scattering,
A fire detection device characterized in that, when the identification unit has identified a semiconductor manufacturing gas fire and the specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal , the detection output unit outputs the identification result that it is a semiconductor manufacturing gas fire along with the fire to the outside.
17. The fire detection device of claim 16,
the identification unit identifies the fire as a smoke-generating fire when a ratio between a multiplication value of the first wavelength and the forward scattering detection signal and a multiplication value of the second wavelength and the back scattering detection signal satisfies a predetermined identification condition corresponding to the smoke,
The fire detection device is characterized in that, when the identification unit has identified a smoke-generating fire and other specified fire detection conditions are met based on the forward scattering detection signal or the backward scattering detection signal , the detection output unit outputs the identification result of the smoke-generating fire along with the fire to the outside.
18. The fire detection device of claim 17,
the identification unit identifies a white smoke fire when a ratio of a multiplied value of the first wavelength and the forward scattering detection signal to a multiplied value of the second wavelength and the backscattering detection signal satisfies a predetermined smoke identification condition corresponding to white smoke, and identifies a black smoke fire when a ratio of a multiplied value of the second wavelength and the backscattering detection signal satisfies a predetermined smoke identification condition corresponding to black smoke,
The fire detection device is characterized in that, when the identification unit has identified the fire as a white smoke fire and other predetermined fire detection conditions are met based on the forward scattering detection signal or the backscatter detection signal, the detection output unit outputs the identification result that the fire is the white smoke fire to the outside along with the fire, and when the identification unit has identified the fire as a black smoke fire and other predetermined fire detection conditions are met based on the forward scattering detection signal or the backscatter detection signal, the detection output unit outputs the identification result that the fire is the black smoke fire to the outside along with the fire.
17. The fire detection device of claim 16,
The signal detection unit
a light receiving unit that outputs the forward scattering detection signal when it receives scattered light of the light of the first wavelength that has been irradiated onto the detection target, and outputs the backward scattering detection signal when it receives scattered light of the light of the second wavelength that has been irradiated onto the detection target ;
a first light emitting unit that irradiates the detection target with light of the first wavelength so that scattered light at the forward scattering angle is incident on the light receiving unit and the forward scattering detection signal is output;
a second light emitting unit that irradiates the detection target with light of the second wavelength so that scattered light at the backscattering angle is incident on the light receiving unit and the backscattering detection signal is output;
A fire detection device comprising:
A disaster prevention facility using the fire detection device according to claim 5 ,
a receiver and a detector that detects a fire and transmits a fire signal to the receiver;
The detector is characterized by comprising the signal detection unit, the identification unit, and the detection output unit.
A disaster prevention facility using the fire detection device according to claim 5 ,
a receiver and a detector that detects a fire and transmits a fire signal to the receiver;
The sensor includes the signal detection unit,
The disaster prevention equipment is characterized in that the receiver is equipped with the identification unit and the detection output unit.
The disaster prevention equipment according to claim 20 or 21,
The disaster prevention equipment is characterized in that the receiver changes the control for preventing the spread of a fire, suppressing it, or extinguishing it depending on the identification result output from the detection output unit.
The disaster prevention equipment according to claim 22,
The disaster prevention equipment is characterized in that, when the identification result is a semiconductor manufacturing gas fire, the receiver controls the supply of semiconductor manufacturing gas to be stopped and/or an inert gas is released into the area where the fire occurred.
A fire detection method that detects smoke-generating fires and semiconductor manufacturing gas fires that produce monodispersed particles in a monitored area where semiconductor manufacturing gases are used, based on the characteristics of scattered light from combustion products , and identifies which type of fire it is.
25. The fire detection method of claim 24, further comprising :
A fire detection method characterized in that, when it is identified as a smoke-emitting fire or a semiconductor manufacturing gas fire, the identification result is reported along with the fire.
26. The fire detection method of claim 25 , further comprising :
A fire detection method characterized in that control for preventing the spread of fire, suppressing it, or extinguishing it is changed depending on the identification result.
27. The fire detection method of claim 26, further comprising :
A fire detection method characterized in that, when the identification result is a semiconductor manufacturing gas fire, the control is to stop the supply of the semiconductor manufacturing gas and/or release an inert gas into the fire area.
1. A fire detection method for detecting a fire in a monitored area where semiconductor manufacturing gas is used , comprising:
a signal detection unit irradiating a detection target in the monitoring area with light and detecting a plurality of detection signals based on scattered light received at different scattering angles;
an identification unit that identifies whether the fire is a smoke-generating fire that generates smoke or a semiconductor manufacturing gas fire that generates monodisperse particles based on the intensity distribution of the plurality of detection signals detected by the signal detection unit;
A fire detection method characterized in that, when the identification unit has identified the fire as a smoke-generating fire or a semiconductor manufacturing gas fire and any of the plurality of detection signals satisfies specified fire detection conditions, the detection output unit outputs the identification result together with the fire to the outside.
29. A fire detection method according to any one of claims 24 to 28, comprising:
A fire detection method characterized in that the fire detection method targets a monitoring area where silane gas or phosphine gas is used as the semiconductor manufacturing gas.