Fire detection device

Abstract

To provide a fire detection device, a disaster prevention facility and a fire detection method that are able to detect a fire more quickly according to dispersion of smoke, without requiring correction of a light receiving signal of smoke by high gain amplification in a smoke sensor.SOLUTION: In a disaster prevention facility, a smoke detection unit 16 as detection means detects a smoke concentration as a predetermined physical quantity caused by smoke in a monitoring area, and a fire determination unit 20 as fire determination means determines that a fire has occurred when the smoke concentration detected by the smoke detection unit 16 satisfies a predetermined fire determination condition. An increase rate detection unit 18 detects an increase rate of the smoke concentration detected by the smoke detection unit 16. When the increase rate of the smoke concentration is equal to or higher than a predetermined threshold, the fire determination condition is changed so as to make it easier to determine a fire. A fire having a high possibility that smoke may be rapidly dispersed and a scale may become significant, it is quickly determined that a fire has occurred.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fire detection device such as a smoke detector that detects smoke caused by a fire and determines whether or not there is a fire, a disaster prevention facility, and a fire detection method. [Background technology]

[0002] 2. Description of the Related Art Conventionally, fire detection devices such as sensors determine that a fire has occurred when, for example, the smoke density caused by a fire satisfies a predetermined fire determination condition, and cause, for example, a receiver to perform a fire alarm operation.

[0003] Meanwhile, in recent years, a smoke detector has been proposed that corrects the output of a smoke sensor according to the rate of increase in the output of the smoke sensor that detects the smoke concentration caused by a fire, thereby enabling faster detection of fast-growing fires, i.e., fires in which the smoke spreads (rises) quickly and is likely to become large in scale (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-220113 A [Patent Document 2] JP 2001-67557 A [Patent Document 3] Japanese Patent Application Publication No. 5-166076 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in such conventional smoke detectors, the amplification factor of the photo-receiving amplifier is changed in accordance with the rate of increase of the smoke sensor output to correct the sensor output. However, the light receiving output of a light receiving element such as a photodiode is very weak, on the order of microamperes, and since a photo-receiving amplifier with a large amplification gain is used, the device is susceptible to the effects of noise. Changing the amplification gain of the photo-receiving amplifier to correct the sensor output results in unstable operation, and the circuit configuration becomes complex, resulting in increased costs.

[0006] The present invention aims to provide a fire detection device and a fire detection method that enable faster fire detection in response to smoke diffusion without the need for correction of smoke reception signals through high gain amplification. [Means for solving the problem]

[0007] (Fire detection equipment) The present invention provides a fire detection device for detecting a fire in a monitored area, comprising: a smoke detection means for detecting a predetermined physical quantity caused by smoke and outputting a smoke detection value; a fire determination means for determining that a fire has occurred when the smoke detection value satisfies a predetermined fire determination condition; an increase rate detection means for detecting an increase rate of a smoke detection value; Equipped with changing a fire determination condition based on the increase rate of the smoke detection value detected by the increase rate detection means; It is characterized by:

[0008] (Fire Judgment Condition Change 1: Change to judge the increase rate by a single threshold) When the rate of increase in the smoke detection value is equal to or greater than a predetermined threshold, the fire determination conditions are changed so that a fire is more easily determined than before the change.

[0009] (Fire threshold and / or accumulation time change for fire judgment conditions 1) The means of determining a fire are If the smoke detection value is equal to or exceeds a predetermined fire threshold, or When the smoke detection value remains above the specified fire threshold for a specified cumulative time or longer, It was determined to be a fire, When the increase rate of the smoke detection value is equal to or greater than the threshold, compared to when the increase rate of the smoke detection value is below the threshold, Lower the fire threshold and / or shorten the build-up time.

[0010] (Fire Judgment Condition Change 2: Change to judge the increase rate based on the first and second thresholds) When the increase rate of the smoke detection value is equal to or greater than a predetermined first threshold, the fire judgment condition is changed to make it easier to judge a fire than before the change, When the rate of increase in the smoke detection value is equal to or less than a predetermined second threshold value which is smaller than the first threshold value, the fire determination conditions are changed so that it becomes more difficult to determine that a fire has occurred than before the change.

[0011] (Fire threshold and / or accumulation time change for fire judgment conditions 2) The means of determining a fire are If the smoke detection value is equal to or exceeds a predetermined fire threshold, or When the smoke detection value remains above the specified fire threshold for a specified cumulative time or longer, It was determined to be a fire, When the increase rate of the smoke detection value is equal to or greater than the first threshold, compared to when the increase rate of the smoke detection value is less than the first threshold and exceeds the second threshold, Lowering the fire threshold and / or shortening the build-up time, When the increase rate of the smoke detection value is equal to or less than the second threshold, compared with when the increase rate of the smoke detection value is less than the first threshold and exceeds the second threshold, Increase the fire threshold and / or increase the build-up time.

[0012] (Disaster prevention equipment 1) In the disaster prevention equipment using the above-mentioned fire detection device, A fire alarm system includes a receiver and a detector that detects a fire and transmits a fire signal to the receiver, The detector is provided with smoke detection means, fire determination means and increase rate detection means.

[0013] (Disaster prevention equipment 2) In the disaster prevention equipment using the above-mentioned fire detection device, A fire alarm system includes a receiver and a detector that detects a fire and transmits a fire signal to the receiver, The detector is provided with smoke detection means; The receiver is provided with a fire determination means and an increase rate detection means.

[0014] (Fire detection method) The present invention provides a fire detection method for detecting a fire in a monitored area, comprising: A smoke detection means detects a predetermined physical quantity caused by smoke and outputs a smoke detection value; A fire determination means determines that a fire has occurred when the smoke detection value satisfies a predetermined fire determination condition; The increase rate detection means detects an increase rate of the smoke detection value; changing a fire determination condition based on the increase rate of the smoke detection value detected by the increase rate detection means; It is characterized by: Effect of the Invention

[0015] (Effectiveness of fire detection devices) According to the fire detection device of the present invention, when a fire is judged by detecting a smoke detection value (e.g., smoke concentration) in a monitored area, the fire judgment conditions based on the smoke detection value are changed according to the rate of increase in the smoke detection value, so that a fire that is likely to become large in scale and in which smoke spreads (rises) quickly can be judged as a fire more quickly.

[0016] (Effects of Fire Judgment Condition Change 1) In addition, if the rate of increase in the smoke detection value is equal to or greater than a predetermined threshold, the fire judgment conditions are changed to make it easier to judge a fire than before the change, i.e., to increase the sensitivity, making it possible to quickly judge a large fire where smoke spreads quickly.

[0017] (Effect of changing the fire threshold and / or accumulation time) In addition, when the rate of increase in the smoke detection value is equal to or greater than the threshold, the fire judgment conditions are changed to lower the fire threshold and / or shorten the accumulation time compared to when the rate of increase in the smoke detection value is below the threshold, thereby enabling rapid fire judgment for fires that have a high potential for large-scale fires with fast smoke diffusion rates.

[0018] (Effects of Fire Judgment Condition Change 2) In addition, when the rate of increase in the smoke detection value is equal to or greater than a predetermined first threshold, the fire judgment conditions are changed to make it easier to judge a fire than before the change, making it possible to quickly and reliably judge a fire for fires that have the potential to become large in scale and where smoke spreads quickly.When the rate of increase in the smoke detection value is equal to or less than a predetermined second threshold which is lower than the first threshold, the fire judgment conditions are changed to make it more difficult to judge a fire than before the change, i.e., to lower the sensitivity, making it possible to reliably prevent non-fire alarms in conditions that correspond to non-fires, such as smoke or steam from cooking, cigarette smoke, etc.

[0019] (Effect of changing the fire threshold and / or accumulation time) In addition, when the rate of increase in the smoke detection value is equal to or greater than the first threshold, the fire threshold is lowered and / or the accumulation time is shortened compared to when the rate of increase in the smoke detection value is less than the first threshold and exceeds the second threshold, thereby enabling quick fire judgment for fires that have a high possibility of becoming large in scale due to the fast smoke diffusion rate. On the other hand, when the rate of increase in the smoke detection value is equal to or less than the second threshold which is smaller than the first threshold, the fire threshold is raised and / or the accumulation time is lengthened compared to when the rate of increase in the smoke detection value is less than the first threshold and exceeds the second threshold, thereby making it possible to reliably prevent non-fire alarms in conditions that correspond to non-fires, such as smoke or steam associated with cooking, cigarette smoke, etc.

[0020] (Effect of Disaster Prevention Equipment 1) The present invention is a disaster prevention equipment that uses the above-mentioned fire detection device, and by providing the detector with all of the smoke detection means, fire judgment means, and increase rate detection means, it can be dealt with simply by modifying the detector. Even in the case of existing equipment, it can be easily dealt with by removing the detector mounted on the base and replacing it with a detector equipped with all of the smoke detection means, fire judgment means, and increase rate detection means.

[0021] (Effects of Disaster Prevention Equipment 2) The present invention is a disaster prevention facility that uses the above-mentioned fire detection device, and by providing a smoke detection means in the detector and a fire judgment means and an increase rate detection means in the receiver, it is no longer necessary to make changes to the detector and can be dealt with by making changes only to the receiver.

[0022] (Effectiveness of fire detection methods) The present invention, as a fire detection method, provides the same effects as those of the above-mentioned fire detection device. [Brief description of the drawings]

[0023] [Figure 1] 1 is an explanatory diagram showing the basic concept of a fire detection device, a disaster prevention equipment, and a fire detection method according to the present invention. [Diagram 2] FIG. 2 is an explanatory diagram of a disaster prevention system showing a specific embodiment of the present invention targeted at a P-type disaster prevention system corresponding to FIG. 1. [Diagram 3] 1 is a time chart showing characteristics of time change in smoke concentration with different increase rates. [Figure 4] 3 is a flow chart illustrating a control operation according to an embodiment of the sensor of FIG. 2. [Diagram 5] 3 is a flowchart showing a control operation according to another embodiment of the sensor of FIG. 2. [Figure 6] 1 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 judges a fire on the receiver side. [Figure 7] FIG. 7 is an explanatory diagram of a disaster prevention system showing a specific embodiment of the present invention targeted at an R-type disaster prevention system corresponding to FIG. 6. [Figure 8] 8 is a flowchart showing, in the form of a time chart, a control operation according to the embodiment of the R-type disaster prevention equipment of FIG. 7. [Figure 9] 8 is a flowchart showing, in the form of a time chart, a control operation according to another embodiment of the R-type disaster prevention equipment of FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a fire detection device, a fire prevention system, and a fire detection method according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these preferred embodiments.

[0025] [Basic Concept of the Embodiment] Fig. 1 is an explanatory diagram showing the basic concept of an embodiment of the present invention corresponding to a disaster prevention facility 1, 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 disaster prevention facility, and a fire detection method. Note that an embodiment corresponding to a disaster prevention facility 2 will be described separately.

[0026] The term "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, and the like.

[0027] Here, the "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 of a building.

[0028] The fire detection device is, for example, a detector 12 of a disaster prevention facility that is composed of a receiver 10 and a detector 12, and includes smoke detection means, fire determination means, and increase rate detection means.

[0029] "Smoke detection means" is a means for detecting a predetermined physical quantity caused by smoke and outputting a smoke detection value, such as the smoke detection unit 16 provided in the detector 12, and specifically, a means for detecting the smoke density of smoke generated by, for example, a fire. Here, "detecting a predetermined physical quantity caused by smoke" means that when detection light from a light-emitting element is applied to smoke that has flowed into the smoke detection unit 16, the scattered light or attenuated light is received by a light-receiving element and converted into an electrical signal, and the received light signal is amplified with high gain by a light-receiving amplifier and output as a detection value of the smoke density, and includes the concept of detecting smoke density by a scattering type smoke detector or a light-attenuating type smoke detector.

[0030] The "fire judgment means" is a means for judging that a fire has occurred when the smoke detection value of the smoke detection means satisfies predetermined fire judgment conditions, such as the fire judgment unit 20 provided in the detector 12, which judges that a fire has occurred when the smoke concentration detected by the smoke detection unit 16 satisfies predetermined fire judgment conditions.

[0031] The fire judgment means sets a first fire judgment condition or a second fire judgment condition as the fire judgment condition. Here, the "first fire judgment condition" is a condition for judging a fire when the smoke detection value is equal to or greater than a fire threshold. The "second fire judgment condition" is a condition for judging a fire when the smoke detection value remains equal to or greater than a predetermined fire threshold for a predetermined accumulated time or more.

[0032] The "increase rate detection means" is a means for detecting the rate of increase in the smoke detection value detected by the smoke detection means, i.e., the amount of change in the smoke concentration per specified unit time, and is, for example, an increase rate detection unit 18 provided in the detector 12, which detects the increase rate of the smoke concentration detected by the smoke detection unit 16.

[0033] Furthermore, the fire detection device changes the fire judgment conditions according to the increase rate of the smoke detection value detected by the increase rate detection means. For example, the fire judgment means is a means for changing the fire judgment conditions so that it is easier to judge a fire than before the change when the increase rate of the smoke detection value is equal to or greater than a predetermined threshold. Here, "changing the fire judgment conditions so that it is easier to judge a fire" means changing the conditions for judging a fire to conditions with looser conditions and higher sensitivity. As an example, if a first fire judgment condition for judging a fire when the smoke density is equal to or greater than a predetermined fire threshold is set, it means changing the fire threshold to a lower condition (loose condition) to make it easier to judge a fire and increase the sensitivity compared to when the increase rate of the smoke detection value is less than the threshold. Also, if a second fire judgment condition for judging a fire when the smoke density is equal to or greater than the predetermined fire threshold continues for a predetermined accumulation time or more, it means changing the accumulation time to a shorter condition (loose condition) to make it easier to judge a fire and increase the sensitivity compared to when the increase rate of the smoke detection value is less than the threshold.

[0034] In addition, the fire judgment means sets a predetermined first threshold value and a second threshold value smaller than the first threshold value for the increase rate of the smoke detection value, and changes the fire judgment conditions by dividing the increase rate of the smoke detection value as follows. First, when the rate of increase in the smoke detection value is equal to or greater than a first threshold value, the fire detection conditions are changed to make it easier to detect a fire. Second, when the rate of increase in the smoke detection value is less than the first threshold value and exceeds the second threshold value, the fire determination conditions are not changed, and the initially set fire determination conditions are maintained. Third, when the rate of increase in the smoke detection value is equal to or less than the second threshold, the fire detection conditions are changed so as to make it more difficult to detect a fire.

[0035] Here, in the third case, "making it difficult to detect a fire" means, for example, when a first fire detection condition is set to detect a fire when the smoke density is equal to or greater than a predetermined fire threshold, changing the fire threshold to a higher value (stricter condition) to make it difficult to detect a fire and lowering the sensitivity. Also, when a second fire detection condition is set to detect a fire when the smoke density remains equal to or greater than a predetermined accumulated time, changing the accumulated time to a longer time (stricter condition) to make it difficult to detect a fire and lowering the sensitivity.

[0036] In the following explanation, we will explain the case where the "monitoring area" is a "room in a building," the "smoke detection means" is a "scattered light type smoke detection unit," the "smoke detection value" is "smoke concentration," and the "increase rate of the smoke detection value" is the "increase rate of smoke concentration."

[0037] [Specific details 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. The contents will be described separately as follows. a. P-type fire prevention equipment a1. Receiver a2. Sensor a3. Fire judgment department a4. Increase rate detection section a5. An embodiment in which the rate of increase in smoke density is determined by a single threshold a6. Threshold for determining the growth rate a7. Changes in fire judgment criteria a8. Sensor control operation a9. An embodiment in which the increase rate of smoke density is determined based on the first and second threshold values b. Basic Concept of Other Embodiments c. R-type fire prevention equipment c1. Sensor c2. Receiver c3. Transmission control c4. An embodiment in which the rate of increase in smoke density is determined by a single threshold c5. An embodiment in which the increase rate of smoke density is determined based on first and second threshold values d. Modifications of the present invention

[0038] [aP-type disaster prevention equipment] Fig. 2 is an explanatory diagram showing a specific embodiment of the present invention targeted at a proprietary-type (P-type) disaster prevention facility corresponding to Fig. 1. Here, the "P-type disaster prevention facility" refers to a facility in which a receiver 10 monitors fires for each signal line (each signal line) to which a detector 12 is connected.

[0039] As shown in Fig. 2, the P-type disaster prevention equipment of this embodiment includes a receiver 10 and multiple sensors 12. Note that Fig. 2 shows one sensor 12 as a representative. The receiver 10 is installed in a manager's office, a disaster prevention center, or the like, and multiple sensors 12 are connected to a signal line 14 that is drawn from the receiver 10 to a monitoring area such as a room in a building. The signal line 14 drawn from the receiver 10 includes a positive signal line 14a and a negative signal line (common signal line) 14b, and supplies power from the receiver 10 to the sensors 12 and transmits a fire alert signal from the sensor 12 to the receiver 10.

[0040] (a1. Receiver) The receiver 10 comprises a receiver control unit 40, a line receiving unit 42, a display unit 44, an operation unit 46, an alarm unit 48, and a report transmission unit 50. The line receiving units 42 are provided for each signal line 14 drawn out in a monitored area, for example, for each floor of a building, and receive fire alert signals from the detectors 12 and output them to the receiver control unit 40.

[0041] The receiver control unit 40 is composed of a computer circuit equipped with a CPU, memory, and various input / output ports, and performs a fire alarm operation when it detects the reception of a fire alert signal by any of the line receiving units 42. The fire alarm operation of the receiver control unit 40 activates the fire representative light on the display unit 44 and also activates the district indicator light indicating the district where the fire has occurred, outputs a main sound alarm including an alarm voice message by the alarm unit 48, and also performs a district sound alarm by activating the district sounding device installed in the monitoring area where the fire has occurred, and also instructs the reporting unit 50 to perform interlocking control of smoke control and exhaust equipment, etc.

[0042] (a2.sensor) The configuration of the detector 12 that functions as a fire detection device will be described in more detail below. The detector 12 includes a smoke detection section 16, a detector control section 24, an alarm circuit section 26, a power supply section 28, a light emission driving section 34, and a light reception amplification section 36.

[0043] The smoke detection unit 16, which serves as smoke detection means, comprises a light-emitting element 30 and a light-receiving element 32, and is disposed in a smoke detection space provided inside the detector. The light-emitting element 30 irradiates smoke flowing into the smoke detection space from the outside, and the light-receiving element 32 receives the light scattered by the smoke, forming a scattering type smoke detection unit that outputs a light-receiving signal corresponding to the smoke concentration. The light-emitting element 30 is, for example, a light-emitting diode, but may be any light-emitting element, and the light-receiving element 32 is, for example, a photodiode, but may be any light-receiving element. When a silicon photodiode is used as the light-receiving element 32, for example, a short-circuit current (light-receiving current) in the range of about 1 to 10 μA (10-6 to 10-5 A) flows depending on the intensity of the scattered light.

[0044] The smoke detection space is a light-shielded space into which smoke flows, and the light-emitting element 30 and the light-receiving element 32 arranged in the smoke detection space are arranged so that their optical axes intersect at a scattering angle that is a predetermined acute angle, the area including the intersection of the optical axes is the smoke detection area, and light scattered by smoke that has flowed into the smoke detection area, so-called forward scattered light, is received by the light-receiving element 32. The scattering angle is arbitrary, and it is also possible to detect backward scattered light by setting the scattering angle to a predetermined obtuse angle exceeding a right angle.

[0045] The light-emitting element 30 is driven to emit light intermittently by a light-emitting driver 34, and the light-receiving signal output from the light-receiving element 32 is amplified by a light-receiving amplifier 36 and output to the sensor control unit 24 as a smoke concentration detection signal.

[0046] The light emission driver 34 outputs a light emission pulse signal to the light emitting element 30 at a predetermined cycle to drive the light emitting element 30 to emit light intermittently, and the light emission pulse width of the light emitting element 30 is a constant pulse width determined by the response characteristics of the light receiving element 32 and the light receiving amplifier 36, and the light emission cycle is set to, for example, a cycle of 1 second to reduce the current consumption of the light emission drive, but is arbitrary and can be changed as necessary. The light receiving amplifier 36 uses an operational amplifier circuit with an amplification gain fixed to a predetermined gain, which inputs a short circuit current of, for example, 1 to 10 μA that flows in pulses according to the amount of scattered light received by the light receiving element 32, and outputs a light receiving pulse voltage of, for example, 1 to 5 mV.

[0047] The detector control unit 24 is composed of a computer circuit equipped with a CPU, memory, and various input / output ports, and has the functions of an increase rate detection unit 18 and a fire judgment unit 20, which are components of the fire detection device of the present invention, as functions realized by executing a program.

[0048] The detector control unit 24 acquires the smoke density by reading the smoke density detection signal from the photoreceiver amplifier unit 36 ​​through A / D conversion synchronized with the timing of the light emission drive of the light emitting element 30. When the fire detection unit 20 judges a fire to have occurred based on the acquired smoke density, it activates the alarm circuit unit 26, short-circuits the positive signal line 14a and the negative signal line 14b to a low impedance, passes a fire alarm current and transmits a fire alarm signal to the receiver 10.

[0049] (a3. Fire Judgment Department) The fire judgment section 20, which serves as a fire judgment means provided in the sensor control section 24, judges that a fire has occurred when the smoke density obtained by reading the smoke density detection signal output from the light receiving amplifier section 36 through A / D conversion satisfies a predetermined fire judgment condition. A first fire judgment condition or a second fire judgment condition is set in the fire judgment section 20 as the fire judgment condition.

[0050] The first fire judgment condition is to judge a fire to have occurred when the detected smoke density D is equal to or greater than a predetermined fire threshold Dth. For example, if the detector 12 is a type 2 sensitivity detector, the first fire judgment condition is to judge a fire to have occurred when the detected smoke density D is equal to or greater than the fire threshold Dth=10 (% / m) corresponding to the type 2 sensitivity.

[0051] A "class 2 sensitivity detector" is a detector with a legally stipulated nominal activation concentration K of 10 (% / m), which activates within 30 seconds when placed in an airflow with a wind speed of 20cm to 40cm / sec containing smoke with a concentration of (nominal activation concentration K) x 1.5 = 10 (% / m) x 1.5 = 15 (% / m) as an activation test, and does not activate within 5 minutes, for example in the case of a non-accumulation type, when placed in an airflow with a wind speed of 20cm to 40cm / sec containing smoke with a concentration of (nominal activation concentration K) x 0.5 = 10 (% / m) x 0.5 = 5 (% / m) as a non-activation test. In addition to such class 2 sensitivity detectors with K = 10 (% / m), "class 1 sensitivity detectors" with a nominal activation concentration K = 5 (% / m) or "class 3 sensitivity detectors" with a nominal activation sensitivity K = 15 (% / m) may also be used.

[0052] The second fire judgment condition is to judge a fire to have occurred when the state in which the detected smoke density D is equal to or greater than a predetermined fire threshold Dth continues for a predetermined accumulation time T or more. For example, assuming that the detector 12 is a type 2 sensitivity detector, the second fire judgment condition is to judge a fire to have occurred when the state in which the detected smoke density D is equal to or greater than a fire threshold Dth=10 (% / m) corresponding to the type 2 sensitivity continues for a predetermined accumulation time T, for example, T=15 seconds or more.

[0053] (a4. Increase rate detection section) The increase rate detection unit 18, which serves as an increase rate detection means provided in the detector 12, detects the amount of change ΔD in the smoke concentration detected by the smoke detection unit 16 per specified unit time, for example, per minute, as an increase rate α [(% / m) / min].

[0054] The rate of increase α of smoke density associated with a fire depends on the diffusion speed (ascent speed) of smoke according to the scale of the fire that has occurred. For example, in a fire involving polyurethane or the like that involves black smoke, a large amount of smoke is generated due to the fast burning speed, and the rate of increase α of smoke density detected by the smoke detection unit 16 is large. On the other hand, in a smoldering fire that involves white smoke, the burning speed is slow so the amount of smoke generated is small, and the rate of increase α of smoke density detected by the smoke detection unit 16 is small. Furthermore, in the event of the occurrence of non-fire factors such as smoke or steam from cooking or cigarette smoke, the rate of increase α of smoke density detected by the smoke detection unit 16 is lower than that of a smoldering fire.

[0055] Fig. 3 is a time chart showing the characteristics of time change in smoke concentration with different linear increase rates over time, with characteristic a showing the highest increase rate, for example an explosive oil fire, while characteristic e shows a smoldering fire in which a futon or the like smolders, and characteristics b to d show fires of a scale between these two. Characteristic g shows cases where non-fire factors such as smoke or steam from cooking or cigarette smoke have occurred. Note that the increase rate of smoke concentration in an actual fire is not a straight line (constant increase rate), and as is well known, the increase rate changes randomly over time.

[0056] (a5. An embodiment in which the rate of increase in smoke density is determined by a single threshold value) The fire judgment unit 20 judges a fire by setting a predetermined fire judgment condition, for example a first fire judgment condition or a second fire judgment condition, and further, when the increase rate α of the smoke concentration detected by the increase rate detection unit 18 is equal to or greater than a predetermined threshold value αth, changes the fire judgment condition to make it easier to judge a fire, and increases the sensitivity to judge a fire.

[0057] (a6. Threshold of growth rate) Here, the threshold value αth of the smoke concentration increase rate α for changing the fire judgment conditions is arbitrary, but for example, in Figure 3, the increase rate of characteristic f between characteristic e due to a smoldering fire, which has the lowest increase rate among fire causes, and characteristic g due to non-fire causes is set as the threshold value αth.

[0058] As another method, the threshold value αth is set, for example, within the range of 0.5 to 1.5 [(% / m) / min], for example 1.0 [(% / m) / min], based on inactivation tests of detectors with class 1, class 2, and class 3 sensitivity. For example, in a deactivation test for detectors of type 1, 2, and 3 sensitivity, when the detector is placed in an air current with a wind speed of 20cm to 40cm / sec containing smoke with a nominal activation concentration of 2.5 (% / m), 5 (% / m), or 7.5 (% / m), the detector is one that does not activate within 5 minutes, for example in the case of a non-accumulation type. When the smoke concentration reaches 2.5 (% / m), 5 (% / m), or 7.5 (% / m) respectively after 5 minutes, the increase rate α is 0.5 [(% / m) / min], 1.0 [(% / m) / min], or 1.5 [(% / m) / min], so the threshold value αth of the increase rate α of the smoke concentration is set to a predetermined value within the range of 0.5 to 1.5 [(% / m) / min].

[0059] (a7. Changes in fire judgment criteria) In the case where the fire judgment unit 20 has set a first fire judgment condition for judging a fire to exist when the detected smoke density D is equal to or greater than a predetermined fire threshold Dth, when the increase rate α of the smoke density detected by the increase rate detection unit 18 is determined to be equal to or greater than the threshold αth, the fire judgment unit 20 changes the fire threshold Dth of the first fire judgment condition to another lower predetermined fire threshold Dth1, making it easier to judge a fire and increasing the sensitivity.

[0060] For example, if the detector 12 is a detector with a type 2 sensitivity, the fire judgment unit 20 sets a first fire judgment condition for judging a fire when the detected smoke density D becomes equal to or exceeds the fire threshold Dth=10(% / m) corresponding to the type 2 sensitivity, but when the increase rate α of the smoke density detected by the increase rate detection unit 18 is determined to be equal to or exceeds the threshold αth, the fire judgment unit 20 changes the fire threshold Dth=10(% / m) of the first fire judgment condition to a higher fire threshold Dth1=5(% / m) corresponding to the type 1 sensitivity, for example, to make it easier to judge a fire and increase the sensitivity. In Fig. 3, by changing the fire threshold Dth to the smaller fire threshold Dth1, a fire that was judged to be a fire at the a1-e1 point for the characteristic α-e is judged to be a fire at the a2-e2 point, and the time until a fire is judged to be a fire is shortened, enabling a quicker fire judgment.

[0061] In addition, in the case where the fire judgment unit 20 has set a second fire judgment condition in which a fire is judged to have occurred when the state in which the detected smoke density D is equal to or greater than a predetermined fire threshold Dth continues for a predetermined accumulation time T, for example, T = 15 seconds, or more, when the increase rate α of the smoke density detected by the increase rate detection unit 18 is determined to be equal to or greater than the threshold αth, the fire judgment unit 20 changes the accumulation time T, for example, T = 15 seconds, to a shorter predetermined accumulation time T1, for example, T1 = 10 seconds, thereby shortening the time until a fire is judged to have occurred, making it easier to judge a fire.

[0062] As a result, when the rate of increase in the smoke density is large, the accumulation time T is changed to a shorter accumulation time T1, and a fire is judged to have occurred if the state in which the smoke density D is equal to or greater than the fire threshold Dth continues for the changed short accumulation time T1 or more, enabling a quicker fire judgment. Note that, in the change of the second fire judgment condition, the accumulation time is changed when an increase rate α that is equal to or greater than the threshold αth is detected, but both the fire threshold and the accumulation time may be changed.

[0063] (a8. Sensor control operation) FIG. 4 is a flowchart showing the control operation according to the embodiment of the detector in FIG. 2, which determines the rate of increase in smoke density using a single threshold value to change the fire judgment conditions, and is the control operation of the detector control unit 24.

[0064] 4, in step S1, the sensor control unit 24 acquires the smoke density detected by the smoke detection unit 16. That is, the light-emitting element 30 is intermittently driven by the light-emitting drive unit 34 to emit light, and scattered light such as smoke or steam is received by the light-receiving element 32. The smoke density detection signal amplified by the light-receiving amplifier unit 36 ​​is read in by A / D conversion to acquire the smoke density.

[0065] Next, the detector control unit 24 compares the smoke density acquired in step S2 with a predetermined fire warning level, and since a fire warning level exceeding the fire warning level indicates a high possibility of a fire, the process proceeds to step S3, where the increase rate detection unit 18 detects the increase rate of the smoke density. Here, the "fire warning level" is a level (threshold) for preliminarily judging a fire prior to an actual fire judgment, and for example, if the detector 12 is a type 2 sensitivity detector that alerts a fire at a smoke density of 10 (% / m), the fire warning level may be a lower smoke density, for example 5 (% / m) corresponding to type 1 sensitivity, or even lower, for example 3 (% / m), but this is arbitrary.

[0066] Next, in step S3, the detector control unit 24 detects the rate of increase in smoke density using the increase rate detection unit 18, and if in step S4 the rate of increase in smoke density is equal to or greater than a predetermined threshold, the process proceeds to step S5, at which point the fire judgment unit 20 increases the sensitivity by lowering the fire threshold and / or shortening the accumulation time in order to change the first fire judgment condition and / or the second fire judgment condition set above to relaxed conditions that make it easier to judge a fire.

[0067] Next, proceeding to step S6, the detector control unit 24 judges whether the smoke density detected by the fire judgment unit 20 satisfies the fire judgment conditions changed by the fire judgment unit 20, and if it is satisfied, proceeds to step S7 to judge it to be a fire, and in step S8 instructs the alarm circuit unit 26 to transmit a fire alarm signal, activates the alarm circuit unit 26 and transmits the fire alarm signal to the receiver 10.

[0068] Next, in step S9, the sensor control unit 24 determines recovery from the interruption of the power supply to the signal line 14 accompanying the recovery operation in the receiver 10, and returns to the initial sensor control in step S1.

[0069] On the other hand, when the detector control unit 24 determines in step S4 that the rate of increase in smoke concentration is less than a predetermined threshold, it proceeds to step S10, and if the fire judgment conditions have been changed in the previous processing, it restores the fire judgment conditions to the initially set fire judgment conditions in step S11 and proceeds to the fire judgment processing of step S6, or if the fire judgment conditions have not been changed in step S10, it proceeds to step S6 and performs fire judgment processing based on the initially set fire judgment conditions.

[0070] (a9. An embodiment in which the increase rate of smoke density is determined by first and second thresholds) In this embodiment, a first threshold value αth1 and a smaller second threshold value αth2 are set as thresholds for determining whether the smoke density increase rate α is large or small, and as described above, when the smoke density increase rate α is equal to or greater than the first threshold value αth1, the fire judgment conditions are changed to make it easier to judge a fire, when the smoke density increase rate α is less than the first threshold value αth1 and greater than the second threshold value αth2, the initially set fire judgment conditions are maintained, and when the smoke detection value increase rate α is equal to or less than the second threshold value αth2, the fire judgment conditions are changed to make it more difficult to judge a fire.

[0071] Here, the first threshold value αth1 and the second threshold value αth2 used to determine the magnitude of the rate of increase α of smoke concentration are arbitrary, but if the setting range of the threshold value αth based on the aforementioned detector deactivation test is 0.5 to 1.5 [(% / m) / min], for example, the first threshold value αth1 is set to 1.5 [(% / m) / min] and the second threshold value αth2 is set to 0.5 [(% / m) / min].

[0072] When the first fire judgment condition is set to judge a fire to be present when the detected smoke density D is equal to or greater than a predetermined fire threshold Dth, the fire judgment unit 20 changes the fire threshold Dth of the first fire judgment condition to a lower predetermined fire threshold Dth1 when the smoke density increase rate α is equal to or greater than the first threshold αth1, making it easier to judge a fire and increasing the sensitivity. This enables quick judgment of fires that have a high possibility of expanding in scale due to the fast smoke diffusion speed.

[0073] On the other hand, when the increase rate α of the smoke density is equal to or lower than the second threshold αth2, the fire judgment unit 20 changes the fire threshold Dth of the first fire judgment condition to a higher predetermined fire threshold Dth2 to make it difficult to judge a fire and to lower the sensitivity. For example, if the detector 12 is a detector with a type 2 sensitivity, the fire judgment unit 20 sets the first fire judgment condition to judge a fire when the smoke density D is equal to or higher than the fire threshold Dth=10(% / m) corresponding to the type 2 sensitivity, but when the increase rate of the smoke density is equal to or lower than the second threshold αth2, the fire threshold Dth=10(% / m) of the first fire judgment condition is changed to a higher fire threshold Dth2=15(% / m) corresponding to the type 3 sensitivity to make it difficult to judge a fire and to lower the sensitivity.

[0074] As a result, in the case of a gradual increase in smoke concentration due to non-fire reasons such as smoke or steam from cooking or cigarette smoke, the fire threshold is changed to a higher value, and the smoke concentration takes a long time to reach the new high fire threshold or may not reach it at all, which makes it possible to prevent a non-fire alarm from being issued because the smoke concentration due to non-fire reasons such as steam or cigarette smoke is judged to be a fire.

[0075] Furthermore, when the fire judgment unit 20 is set with a second fire judgment condition that judges a fire to have occurred when the state in which the detected smoke density D is equal to or greater than a predetermined fire threshold Dth continues for a predetermined accumulation time T, for example, T=15 seconds, or more, when the smoke density increase rate α is equal to or greater than the first threshold αth1, the accumulation time T, for example, T=15 seconds, is changed to a shorter predetermined accumulation time T1, for example, T1=10 seconds, to shorten the time until a fire is judged to have occurred, making it easier to judge a fire and increasing the sensitivity. This enables quick fire judgment for fires that have a high possibility of becoming large in scale due to the fast diffusion speed of smoke.

[0076] On the other hand, when the rate of increase in smoke concentration is equal to or less than the second threshold value αth2, the fire detection unit 20 changes the accumulation time T, for example T = 15 seconds, to a longer predetermined accumulation time T2, for example T2 = 20 seconds, thereby lengthening the time until a fire is determined, making it more difficult to determine that a fire has occurred and lowering the sensitivity.

[0077] As a result, if the smoke density is due to a non-fire such as smoke or steam from cooking or cigarette smoke, the accumulation time T is changed to the longer accumulation time T2, and the possibility that the state in which the smoke density is equal to or greater than the fire threshold Dth will continue for longer than the changed long accumulation time T2 is almost eliminated, making it possible to prevent a non-fire alarm from being issued due to a judgement that a fire exists based on the smoke density of a non-fire such as steam or cigarette smoke. Note that, although the accumulation time is changed in changing the second fire judgment condition, both the fire threshold and the accumulation time may be changed.

[0078] Furthermore, when the increase rate α of the smoke density is less than the first threshold value αth1 and exceeds the second threshold value αth2, the initially set fire determination conditions are maintained.

[0079] FIG. 5 is a flowchart showing a control operation according to another embodiment of the detector of FIG. 2, in which the rate of increase in smoke density is determined based on first and second threshold values ​​to change the fire judgment conditions, and this is the control operation performed by the detector control unit 24 of the detector 14.

[0080] Steps S21 to S23 in FIG. 5 are the same as steps S1 to S3 in FIG. 4, steps S26 to S29, S32, and S33 in FIG. 5 are the same as steps S6 to S9, S11, and S12 in FIG. 4, and steps S24, S25, S30, and S31 are controls unique to this embodiment.

[0081] That is, if the rate of increase in smoke concentration is equal to or greater than a predetermined first threshold in step S24, the detector control unit 24 proceeds to step S25, and at this time, the fire judgment unit 20 increases the sensitivity by lowering the threshold and / or shortening the accumulation time in order to change the first fire judgment condition and / or the second fire judgment condition set above to conditions that make it easier to judge a fire.

[0082] On the other hand, if the increase rate of the smoke density is less than the first threshold in step S24, the process proceeds to step S30, and if it is equal to or less than the second threshold, the process proceeds to step S31, where the fire threshold is increased and / or the accumulation time is lengthened to lower the sensitivity in order to change the first or second fire judgment condition set at that time to a condition that makes it difficult to judge a fire. Furthermore, if it is determined in step S24 that the increase rate α of the smoke density is less than the first threshold αth1 and then in step S30 that the increase rate α exceeds the second threshold αth2, the initially set fire judgment condition is maintained, including the processes in steps S32 and S33.

[0083] [b. Other basic concepts of the embodiment] FIG. 6 is an explanatory diagram showing another basic concept of an embodiment of a fire detection device, disaster prevention equipment, and fire detection method corresponding to disaster prevention equipment 2, and is characterized in that in a fire alarm system as an example of disaster prevention equipment equipped with a receiver 10 and a sensor 12, the sensor 12 is provided with a smoke detection unit 16 which serves as the smoke detection means of the fire detection device, and the receiver 10 is provided with a fire judgment unit 20 which serves as the fire judgment means of the fire detection device and an increase rate detection unit 18 which serves as the increase rate detection means.

[0084] The smoke detection unit 16 provided in the detector 12 and the fire judgment unit 20 and increase rate detection unit 18 provided in the receiver 10 are basically the same as the smoke detection unit 16, fire judgment unit 20 and increase rate detection unit 18 provided in the detector 12 in Figure 1, but differ in that the smoke density in the monitored area detected by the smoke detection unit 16 of the detector 12 is transmitted to the receiver 10 via signal line 14, and the receiver 10 detects the increase rate of the smoke density, changes the fire judgment conditions depending on the increase rate of the smoke density, and makes a fire judgment, etc.

[0085] Next, the specific content of the embodiment corresponding to FIG. 6 will be described in more detail.

[0086] [cR-type disaster prevention equipment] Fig. 7 is an explanatory diagram of an R-type (Record-type) disaster prevention system showing specific details of an embodiment corresponding to Fig. 6. Here, the "R-type disaster prevention system" refers to a system that monitors fires for each detector 12 (for each detector) by transmitting between a receiver 10 and a detector 12.

[0087] As shown in Fig. 7, the R-type disaster prevention equipment of this embodiment includes a receiver 10 and a sensor 12, and multiple sensors 12 are connected to a transmission line 114 drawn from the receiver 10 to a monitoring area such as a room in a building. The transmission line 114 drawn 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 by a predetermined transmission method. A dedicated power supply line may be provided.

[0088] (c1.sensor) 2, the sensor 12 comprises a smoke detection section 16, a sensor control section 24, a power supply section 28, a light emission drive section 34, and a light reception amplifier section 36, but differs in that a transmission section 60 is provided for transmitting and receiving signals with the receiver 10 by a predetermined transmission method. Also, the sensor control section 24 does not have the functions of the fire judgment section 20 and the increase rate detection section 18, which are components of the fire detection device of the present invention shown in FIG. 2, and these functions are provided on the receiver 10 side.

[0089] (c2. Receiver) 2, the receiver 10 includes a receiver control unit 40, a display unit 44, an operation unit 46, an alarm unit 48, and a reporting unit 50, but differs in that a transmission unit 62 is provided to transmit and receive signals to and from the detector 12 using a predetermined transmission method, and in that the receiver control unit 40 is provided with the functions of a fire judgment unit 20 and an increase rate detection unit 18, which are components of the fire detection device of the present invention, as functions realized by executing a program. The fire judgment unit 20 and increase rate detection unit 18 provided in the receiver 10 are basically the same as those provided in the detector 12 in the embodiment of FIG. 2.

[0090] (c3. Transmission control) In the R-type disaster prevention equipment, a unique address is set for the detectors 12, the receiver 10 transmits a batch A / D conversion command signal at a predetermined cycle, for example, at one-minute cycles, and all the detectors 12 that receive the batch A / D conversion command signal A / D convert and hold (store) the smoke density detected by their smoke detection units 16. Next, the receiver 10 transmits a call signal sequentially specifying the detector addresses, and performs polling to have each detector 12 return a response signal including the detected smoke density.

[0091] When the smoke density detected by the detector 12 reaches a predetermined fire warning level (preliminary fire judgment level), for example 3 (% / m), the detector 12 judges it to be a fire warning level and sends a fire interrupt signal to the receiver 10.

[0092] When the receiver 10 receives a fire interrupt signal from a detector 12, it transmits a group search command signal specifying a group address, performs a group search to identify the group address to which the detector 12 that responded with the fire interrupt signal belongs, and then transmits an intra-group search command signal specifying the detector addresses within the searched group address in sequence, to identify the address of the detector 12 that responded with the fire interrupt signal, i.e., the detector 12 that has been determined to be a sign of a fire.

[0093] Next, the receiver 10 transmits an A / D conversion command signal and a call signal specifying the address of the detector 12 that has been determined to be a fire precursor at a predetermined cycle that is shorter than normal, intensively acquires smoke density from the detectors 12 that have been determined to be a fire precursor, and performs control to determine whether a fire has occurred based on the smoke density using a fire determination unit 20 and an increase rate detection unit 18 provided in the receiver control unit 40. Note that the transmission control between the receiver 10 and the detector 12 is one example, and any known transmission control can be applied.

[0094] (c4. An embodiment in which the rate of increase in smoke density is determined by a single threshold value) FIG. 8 is a flow chart showing, in the form of a time chart, the control operation according to the embodiment of the R-type fire prevention equipment of FIG. 7, in which the rate of increase in smoke density is determined by a single threshold value.

[0095] 8, in step S41, the receiver 10 performs a fire monitoring transmission process by transmitting a batch A / D conversion command signal at a predetermined cycle, for example, at one-minute cycles, then transmitting a call signal specifying the detector address, and receiving a response signal from the detector 12. Meanwhile, in step S42, the detector 12 performs a fire monitoring response process by receiving the batch A / D conversion command signal from the receiver 10, storing and holding the smoke density detected at that time, then receiving a call signal specifying its own address to be received, and transmitting a response signal including the smoke density.

[0096] Next, in step S43, if the detector 12 determines that the detected smoke density has reached a predetermined fire warning level, for example 3 (% / m), the process proceeds to step S44, where it transmits a fire interrupt signal to the receiver 10 as a fire warning transmission process. In step S45, the receiver 10 searches for and identifies the address of the detector that transmitted the fire interrupt signal based on the reception of the fire interrupt signal from the detector 12 as a fire warning reception process.

[0097] In step S46, the receiver 10 determines whether or not a fire interruption signal has been received from the detector 12, and if no fire interruption signal has been received, the process returns to step S41, whereas if a fire interruption signal has been received, the process proceeds to the following step S47.

[0098] Next, in step S47, the receiver 10 performs observation data reception processing by repeatedly transmitting a call signal specifying the address of the detector 12 that transmitted the batch A / D conversion command signal and the fire interrupt signal at short intervals, and causes the detector 12 to perform a smoke density transmission process in which it detects and transmits the smoke density in step S48, and intensively receives smoke density from the detectors 12 that have been determined to be a sign of a fire.

[0099] Next, the receiver 10 proceeds to step S49, where the acquired rate of increase in smoke density is detected by the increase rate detection unit 18, and then, if the rate of increase in smoke density is equal to or greater than a predetermined threshold in step S50, the receiver 10 proceeds to step S51, where the receiver 10 changes the first fire judgment condition and / or the second fire judgment condition set in the fire judgment unit 20 at that time to conditions that make it easier to judge a fire, by lowering the fire threshold and / or shortening the accumulation time, thereby increasing the sensitivity.

[0100] Next, proceeding to step S52, the detector control unit 24 performs fire judgment processing to determine whether the smoke density detected by the fire judgment unit 20 satisfies the changed fire judgment condition.If the fire judgment condition is satisfied, proceed to step S53 and judge it to be a fire.In step S54, fire alarm processing is performed including sounding a main acoustic alarm and a district acoustic alarm, displaying the location of the fire based on the address of the detector that has been judged to be a fire, and linking and controlling smoke control equipment.

[0101] Next, when the receiver 10 determines in step S55 that the restoration is due to a restoration operation following the extinguishing of the fire, it transmits a restoration signal to the detector 12 in step S56 and returns to the fire monitoring transmission processing in step S41. Also, when the detector 12 determines in step S57 that it has received a restoration signal, it returns to the fire monitoring response processing in step S42.

[0102] On the other hand, when the receiver 10 determines in step S50 that the rate of increase in smoke concentration is less than the threshold, it proceeds to step S58, and if the fire judgment conditions were changed in the previous processing, it reverts to the initially set fire judgment conditions in step S59 and proceeds to the fire judgment processing of step S52, but if it determines in step S58 that the fire judgment conditions were not changed, it proceeds to step S52 and performs fire judgment processing based on the initially set fire judgment conditions.

[0103] (c5. An embodiment in which the increase rate of smoke density is determined using first and second thresholds) In the increase rate detection unit 18 and fire judgment unit 20 provided in the receiver 10 of the R-type fire alarm system shown in Figures 6 and 7, as in the increase rate detection unit 18 and fire judgment unit 20 provided in the sensor 12 shown in Figures 1 and 2, a first threshold value αth1 and a smaller second threshold value αth2 are set for the smoke concentration increase rate α, and the fire judgment conditions are changed.

[0104] When the smoke density increase rate α is equal to or greater than the first threshold αth1, the fire judgment unit 20 increases the sensitivity by lowering the fire threshold and / or shortening the accumulation time so as to make it easier to judge the fire judgment condition as a fire. Here, the fire judgment condition is the above-mentioned first fire judgment condition or second fire judgment condition, and the first fire judgment condition lowers the fire threshold and the second fire judgment condition shortens the accumulation time to make it easier to judge the fire.

[0105] Furthermore, when the increase rate α of the smoke density is less than the first threshold value αth1 and exceeds the second threshold value αth2, the fire judgment unit 20 maintains the initially set fire judgment conditions.

[0106] Furthermore, when the increase rate α of the smoke density is equal to or less than the second threshold αth2, the fire judgment unit 20 lowers the sensitivity by increasing the fire threshold and / or lengthening the accumulation time so as to make it difficult to judge the fire judgment condition as a fire. Here, the fire judgment condition is the above-mentioned first fire judgment condition or second fire judgment condition, and the first fire judgment condition increases the fire threshold and the second fire judgment condition lengthens the accumulation time to make it difficult to judge the fire.

[0107] FIG. 9 is a flow chart showing, in the form of a time chart, a control operation according to another embodiment of the R-type fire prevention equipment of FIG. 7, in which the rate of increase in smoke density is determined based on first and second threshold values.

[0108] Steps S61 to S69 in FIG. 9 are the same as steps S41 to S49 in FIG. 8, and steps S72 to S77, S80, and S81 in FIG. 9 are the same as steps S52 to S57, S58, and S59 in FIG. 8, and steps S70, S71, S78, and S79 are controls unique to this embodiment.

[0109] That is, if the rate of increase in smoke concentration is equal to or greater than a predetermined first threshold in step S70, the receiver 10 proceeds to step S71, and the fire judgment unit 20 changes the initially set fire judgment conditions to conditions that make it easier to judge a fire by lowering the fire threshold and / or shortening the accumulation time, thereby increasing the sensitivity, and judges a fire in step S72 based on the changed fire judgment conditions.

[0110] On the other hand, if the increase rate of the smoke density is less than the predetermined first threshold in step S70, the process proceeds to step S78, and if it is equal to or less than the predetermined second threshold, the process proceeds to step S79, where the fire judgment unit 20 changes the initially set fire judgment conditions to conditions that make it more difficult to judge a fire by increasing the fire threshold and / or lengthening the accumulation time, thereby lowering the sensitivity, and judges a fire according to the changed fire judgment conditions in step S72. Furthermore, if it is determined in step S70 that the increase rate α of the smoke density is less than the first threshold αth1, and then it is determined in step S78 that the increase rate α exceeds the second threshold αth2, the initially set fire judgment conditions are maintained, including the processes of steps S80 and S81.

[0111] [d. Modifications of the present invention] An alternative embodiment of the invention will now be described in more detail.

[0112] (Dimmable smoke detector) The above embodiment is an example of a light scattering type smoke detector, but is not limited thereto. For example, a light-dimming type smoke detector may be used. The light-dimming type smoke detector is provided with a known light-dimming type smoke detector structure in which light from a light-emitting unit is reflected by a plurality of mirrors arranged in a circular ring shape in a smoke detection space, and the optical path length to the light-receiving unit is made long enough to obtain sufficient light dimming due to smoke. In addition, the smoke detector may be provided with a known composite smoke detector structure that is provided with a light scattering type smoke detector structure and a light-dimming type smoke detector structure in one body.

[0113] (fire alarm) 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, but a fire alarm for a house, for example, equipped with a means for detecting smoke concentration to judge a fire and a means for issuing a fire alarm, may be configured as a fire detection device. In the case of a fire alarm, the functions of the smoke detection unit 16, fire judgment unit 20, and increase rate detection unit 18 constituting the fire detection device are provided in the fire alarm, similar to the sensor 12 of the disaster prevention equipment shown in Figs. 1 and 2.

[0114] (others) Furthermore, the present invention includes appropriate modifications that do not impair the objects and advantages of the present invention, and is not limited to the numerical values ​​shown in the above embodiment. [Explanation of symbols]

[0115] 10: Receiver 12: Sensor 14: Signal line 16: Smoke detector 18: Increase rate detection section 20: Fire judgment department 24: Sensor control unit 26: Alarm circuit section 28: Power supply section 30: Light emitting element 32: Light receiving element 34: Light emitting driver 36: Photoreceiving amplifier section 40: Receiver control unit 42: Line receiving section 44: Display section 46:Operation section 48:Alarm section 50:Transfer Department 60, 62: Transmission section 114: Transmission line

Claims

[Claim 1] A fire detection device for detecting a fire in a monitored area, comprising: a smoke detection means for detecting a predetermined physical quantity caused by smoke and outputting a smoke detection value; a fire determination means for determining that a fire has occurred when the smoke detection value satisfies a predetermined fire determination condition; an increase rate detection means for detecting an increase rate of the smoke detection value; Equipped with When the increase rate of the smoke detection value detected by the increase rate detection means is equal to or greater than a predetermined threshold, the fire judgment condition is changed so as to make it easier to judge a fire than before the change, A fire detection device characterized in that the threshold value is set between the increase rate when a smoldering fire, which is the lowest fire cause, occurs and the increase rate when a non-fire cause occurs.

Images