JP4893397B2 - Fire detector - Google Patents

Description

  The present invention relates to a fire detector.

Conventionally, as a fire detector for detecting smoke generated at the time of a fire or the like, a scattered light type smoke detector (for example, see Patent Document 1) and a dimming type smoke detector (for example, see Patent Document 2) are known. It has been. Here, the scattered light type smoke detector is configured to receive light scattered by smoke particles of light irradiated to the monitoring space from a light projecting element made of a light emitting diode element by a light receiving element made of a photodiode. In addition, if smoke particles are present in the monitoring space, the amount of light received by the light receiving element is increased due to the generation of scattered light, so the presence or absence of smoke particles can be detected based on the amount of increase in the amount of light received by the light receiving element. On the other hand, the dimming smoke detector is configured so that light emitted from the light projecting element is directly received by the light receiving element, and smoke particles are present in the monitoring space between the light projecting element and the light receiving element. If it is present, the amount of light received by the light receiving element is reduced, and therefore the presence or absence of smoke particles can be detected based on the amount of light received by the light receiving element.
JP 2001-34862 A JP 61-33595 A

  By the way, the scattered light type smoke detector needs to be equipped with a labyrinth body as a countermeasure against stray light, so when there is little air flow, the time until smoke particles enter the monitoring space in the event of a fire increases, and the response There was a problem with sex. In addition, there is a problem that the dimming smoke detector may generate a report due to the influence of background light (a non-fire report will be generated) even though no fire has occurred. . In addition, the separate-type dimming smoke detector needs to align the optical axes of the light projecting element and the light receiving element with high accuracy, and there is a problem that it takes a lot of work.

  In addition, non-fire reports may occur when scattered light type smoke detectors or dimming type smoke detectors enter the surveillance space, and steam may enter the monitor space. It was not suitable.

  This invention is made | formed in view of the said reason, The objective is to provide the fire detector which is excellent in responsiveness and can reduce a non-fire report.

The invention of claim 1 includes a sound source unit capable of transmitting ultrasonic waves, a control unit for controlling the sound source unit, a wave receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and a wave receiving element A signal processing unit for determining the presence or absence of a fire based on the output of the signal, the signal processing unit is a monitoring space between the sound source unit and the receiving element based on the attenuation from the reference value of the output of the receiving element a smoke density estimation unit that estimates a smoke density, by comparing the estimated smoke density with a predetermined threshold value at a smoke density estimation unit have a smoke type determination means for determining presence or absence of fire, the sound source unit Is capable of transmitting a plurality of types of ultrasonic waves having different frequencies, and the signal processing unit is configured to output the output frequency of the sound source unit and the receiving element according to the type of suspended particles present in the monitoring space and the smoke concentration. Storage means for storing relational data with the attenuation amount from the reference value of the output of the Particle type estimation means for estimating the type of particles floating in the monitoring space using the output of the receiving element for each ultrasonic wave of each frequency and the relational data stored in the storage means. The smoke concentration estimating means is configured to monitor the monitoring space based on an attenuation amount from a reference value of an output of the receiving element with respect to an ultrasonic wave having a specific frequency when the particle estimated by the particle type estimating means is a smoke particle. It is characterized by estimating the smoke density .

  According to this invention, the signal processing unit that determines the presence or absence of a fire based on the output of the wave receiving element that detects the sound pressure of the ultrasonic wave transmitted from the sound source unit is provided. The smoke density in the monitoring space between the sound source unit and the wave receiving element is estimated based on the attenuation amount from the reference value of the output of the wave receiving element, and is estimated by the smoke density estimating means in the smoke type judging means. The background smoke, which is a problem with photoelectric smoke detectors such as scattered light smoke detectors and dimming smoke detectors, is judged by comparing the smoke concentration with a predetermined threshold. This makes it possible to eliminate the labyrinth required for the scattered light type smoke detector and makes it easier for smoke particles to diffuse into the surveillance space in the event of a fire. And can reduce non-fire alarms compared to a light-reducing smoke detector Possible to become.

Further, according to the present invention, in the signal processing unit, in the particle category estimation unit, the output storage means to the stored relationship data of wave receiving devices of each ultrasound of each frequency that is transmitting from the tone generator Is used to estimate the type of particles floating in the monitoring space, and when the particle estimated by the particle type estimation unit is a smoke particle, the smoke concentration estimation unit receives the ultrasonic wave having a specific frequency. Since the smoke concentration in the monitoring space is estimated based on the attenuation amount from the reference value of the output of the wave element, the particle type identifying means estimates the type of particles floating in the monitoring space, for example, smoke particles and steam. Therefore, it is possible to reduce non-fire information as compared with the scattered light smoke detector and the dimming smoke detector.

According to a second aspect of the present invention, in the first aspect of the present invention, the storage means is an attenuation obtained by dividing an attenuation amount from the reference value of the output frequency of the sound source unit and the output of the receiving element by the reference value as the relation data. It stores the relationship data with the rate.

  According to the present invention, even when the reference value of the output of the receiving element varies according to the output frequency of the sound source unit, the attenuation rate from which the influence of the variation of the output frequency of the sound source unit and the reference value is removed, and By using the relationship data, it is possible to estimate the type of particles floating in the monitoring space without being affected by the fluctuation of the reference value.

According to a third aspect of the present invention, in the first or second aspect of the invention, the sound source unit includes a single sound wave generating element capable of transmitting the plurality of types of ultrasonic waves, and the control unit includes a sound wave generating element. The sound source unit is controlled so that a plurality of types of ultrasonic waves are sequentially transmitted.

  According to the present invention, it is possible to reduce the size and cost of the sound source unit as compared with a case where a plurality of sound wave generating elements capable of transmitting various kinds of ultrasonic waves are provided.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the sound source section includes a plurality of sound wave generating elements capable of transmitting ultrasonic waves having different frequencies.

  According to the present invention, an element that generates ultrasonic waves by mechanical vibration, such as a piezoelectric element, is used as each sound wave generating element, and each sound wave generating element is driven at the respective resonance frequency to transmit a wave from the sound source unit. The sound pressure of the ultrasonic waves that are generated can be increased.

According to a fifth aspect of the invention, in the first to fourth aspects of the invention, the control unit transmits two types of ultrasonic waves having different frequencies from the sound source unit.

  According to the present invention, it is possible to reduce the burden on the control unit and the signal processing unit and to simplify the control unit and the signal processing unit as compared with the case of transmitting three or more types of ultrasonic waves.

According to a sixth aspect of the present invention, in the first to fourth aspects of the invention, the control unit changes the frequency of the ultrasonic wave transmitted from the sound source unit from a lower limit frequency to an upper limit frequency within a predetermined frequency range. Features.

  According to the present invention, it is possible to improve the estimation accuracy of the particle type in the particle type estimation means.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the signal processing unit periodically generates the sound source unit by the control unit based on an output of the receiving element with respect to an ultrasonic wave having a predetermined frequency. At least one of the control condition and the signal processing condition of the output of the receiving element is changed.

According to this invention, it becomes possible to periodically cancel the output fluctuation of the sound source section and the sensitivity fluctuation of the receiving element, and the long-term reliability is improved.
The invention of claim 8 is characterized in that, in the inventions of claims 1 to 7, the control unit transmits ultrasonic waves having a frequency having an insect-proof effect from the sound source unit.
According to the present invention, insects can be prevented from entering the monitoring space, and non-fire reports resulting from insects can be reduced.
According to a ninth aspect of the present invention, in the first to eighth aspects of the present invention, a sound insulation wall is provided around the receiving element to prevent ultrasonic waves from entering the receiving element from other than the sound source section. It is characterized by that.
According to this invention, it is possible to prevent the ultrasonic waves generated from other than the sound source unit from entering the wave receiving element by the sound insulation wall, and to reduce non-fire information.
The invention of claim 10 is the invention of claims 1 to 9, further comprising a base member on which the sound source section and the receiving element are mounted on one surface side, and the one surface of the base member includes the base member A sound absorbing layer is provided to prevent reflection of ultrasonic waves transmitted from the sound source unit.
According to the present invention, it is possible to prevent the ultrasonic wave transmitted from the sound source unit from being reflected by the base member and entering the receiving element, and to prevent interference of the reflected wave.

The invention of claim 11 is a sound source unit capable of transmitting an ultrasonic wave, a control unit for controlling the sound source unit, a wave receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and a wave receiving element A signal processing unit for determining the presence or absence of a fire based on the output of the signal, the signal processing unit is a monitoring space between the sound source unit and the receiving element based on the attenuation from the reference value of the output of the receiving element A smoke density estimation means for estimating the smoke density of the smoke, and a smoke type judgment means for judging the presence or absence of a fire by comparing the smoke density estimated by the smoke density estimation means with a predetermined threshold, Is characterized in that an ultrasonic wave is generated by applying a thermal shock to the air due to a temperature change of the heat generating element accompanying energization of the heat generating element.

According to this invention, the signal processing unit that determines the presence or absence of a fire based on the output of the wave receiving element that detects the sound pressure of the ultrasonic wave transmitted from the sound source unit is provided. The smoke density in the monitoring space between the sound source unit and the wave receiving element is estimated based on the attenuation amount from the reference value of the output of the wave receiving element, and is estimated by the smoke density estimating means in the smoke type judging means. The background smoke, which is a problem with photoelectric smoke detectors such as scattered light smoke detectors and dimming smoke detectors, is judged by comparing the smoke concentration with a predetermined threshold. This makes it possible to eliminate the labyrinth required for the scattered light type smoke detector and makes it easier for smoke particles to diffuse into the surveillance space in the event of a fire. And can reduce non-fire alarms compared to a light-reducing smoke detector Possible to become. Furthermore, the sound source section has a flat frequency characteristic, and the frequency of the generated ultrasonic wave can be changed over a wide range. It is also possible to transmit single-pulse ultrasonic waves with little reverberation from the sound source unit.

According to a twelfth aspect of the present invention, in the invention of the eleventh aspect , the sound source section includes the heat generating section formed on the one surface side of the base substrate, and the heat generating section and the base on the one surface side of the base substrate. It is characterized by having a thermal insulation layer comprising a porous layer provided between the substrate and thermally insulating the heating element and the base substrate.

  According to this invention, since the heat insulation layer is composed of a porous layer, compared with the case where the heat insulation layer is composed of a non-porous layer, the heat insulation property of the heat insulation layer is improved and the ultrasonic wave generation efficiency is increased, Low power consumption can be achieved.

A thirteenth aspect of the invention is characterized in that, in the invention of the eleventh or twelfth aspect , the control unit transmits a single-pulse ultrasonic wave as an ultrasonic wave from the sound source unit.

  According to the present invention, the wave receiving element is less susceptible to interference due to reflected waves, and the accuracy of the smoke density estimated by the smoke density estimating means can be increased.

The invention according to claim 14 is a sound source unit capable of transmitting an ultrasonic wave, a control unit for controlling the sound source unit, a wave receiving element for detecting a sound pressure of the ultrasonic wave transmitted from the sound source unit, and a wave receiving element A signal processing unit for determining the presence or absence of a fire based on the output of the signal, the signal processing unit is a monitoring space between the sound source unit and the receiving element based on the attenuation from the reference value of the output of the receiving element A smoke density estimation means for estimating the smoke density of the smoke, and a smoke type judgment means for judging the presence or absence of a fire by comparing the smoke density estimated by the smoke density estimation means with a predetermined threshold, the control unit Is characterized by transmitting ultrasonic waves having an insect-proofing frequency from the sound source section.

According to this invention, the signal processing unit that determines the presence or absence of a fire based on the output of the wave receiving element that detects the sound pressure of the ultrasonic wave transmitted from the sound source unit is provided. The smoke density in the monitoring space between the sound source unit and the wave receiving element is estimated based on the attenuation amount from the reference value of the output of the wave receiving element, and is estimated by the smoke density estimating means in the smoke type judging means. The background smoke, which is a problem with photoelectric smoke detectors such as scattered light smoke detectors and dimming smoke detectors, is judged by comparing the smoke concentration with a predetermined threshold. This makes it possible to eliminate the labyrinth required for the scattered light type smoke detector and makes it easier for smoke particles to diffuse into the surveillance space in the event of a fire. And can reduce non-fire alarms compared to a light-reducing smoke detector Possible to become. In addition, insects can be prevented from entering the monitoring space, and non-fire reports caused by insects can be reduced.

The invention of claim 15 includes a sound source unit capable of transmitting ultrasonic waves, a control unit for controlling the sound source unit, a wave receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and a wave receiving element A signal processing unit for determining the presence or absence of a fire based on the output of the signal, the signal processing unit is a monitoring space between the sound source unit and the receiving element based on the attenuation from the reference value of the output of the receiving element Smoke density estimation means for estimating the smoke density of the smoke, and smoke type judgment means for judging the presence or absence of a fire by comparing the smoke density estimated by the smoke density estimation means with a predetermined threshold, A sound insulation wall is provided around the element to prevent ultrasonic waves from entering the wave receiving element from other than the sound source section.

According to this invention, the signal processing unit that determines the presence or absence of a fire based on the output of the wave receiving element that detects the sound pressure of the ultrasonic wave transmitted from the sound source unit is provided. The smoke density in the monitoring space between the sound source unit and the wave receiving element is estimated based on the attenuation amount from the reference value of the output of the wave receiving element, and is estimated by the smoke density estimating means in the smoke type judging means. The background smoke, which is a problem with photoelectric smoke detectors such as scattered light smoke detectors and dimming smoke detectors, is judged by comparing the smoke concentration with a predetermined threshold. This makes it possible to eliminate the labyrinth required for the scattered light type smoke detector and makes it easier for smoke particles to diffuse into the surveillance space in the event of a fire. And can reduce non-fire alarms compared to a light-reducing smoke detector Possible to become. Furthermore, the sound insulation wall can prevent the ultrasonic waves generated from other than the sound source unit from entering the wave receiving element, thereby reducing non-fire reports.
According to a sixteenth aspect of the present invention, there is provided a sound source unit capable of transmitting an ultrasonic wave, a control unit for controlling the sound source unit, a wave receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and the wave receiving element A signal processing unit for determining the presence or absence of a fire based on the output of the signal, the signal processing unit is a monitoring space between the sound source unit and the receiving element based on the attenuation from the reference value of the output of the receiving element A smoke density estimation means for estimating the smoke density of the smoke, and a smoke type judgment means for judging the presence or absence of a fire by comparing the smoke density estimated by the smoke density estimation means with a predetermined threshold, And the wave receiving element are mounted on one surface side, and a sound absorbing layer is provided on the one surface of the base member to prevent reflection of ultrasonic waves transmitted from the sound source unit. It is characterized by that.
According to this invention, the signal processing unit that determines the presence or absence of a fire based on the output of the wave receiving element that detects the sound pressure of the ultrasonic wave transmitted from the sound source unit is provided. The smoke density in the monitoring space between the sound source unit and the wave receiving element is estimated based on the attenuation amount from the reference value of the output of the wave receiving element, and is estimated by the smoke density estimating means in the smoke type judging means. The background smoke, which is a problem with photoelectric smoke detectors such as scattered light smoke detectors and dimming smoke detectors, is judged by comparing the smoke concentration with a predetermined threshold. This makes it possible to eliminate the labyrinth required for the scattered light type smoke detector and makes it easier for smoke particles to diffuse into the surveillance space in the event of a fire. And can reduce non-fire alarms compared to a light-reducing smoke detector Possible to become. Furthermore, it is possible to prevent the ultrasonic wave transmitted from the sound source unit from being reflected by the base member and entering the wave receiving element, and interference of the reflected wave can be prevented.
According to a seventeenth aspect of the present invention, in the first to sixteenth aspects of the invention, when the control unit determines that there is a fire in the signal processing unit, the control unit generates an alarm sound including an audible sound wave from the sound source unit. It is characterized by generating.
According to the present invention, since an alarm sound can be generated from the sound source unit, it is not necessary to separately provide a speaker or the like for outputting the alarm sound, and it is possible to reduce the size and cost.

According to an eighteenth aspect of the present invention, in the first to seventeenth aspects of the invention, the signal processing unit is configured to receive the ultrasonic wave from the sound source unit until the ultrasonic wave is received by the wave receiving element. The sound speed detecting means for obtaining the sound speed based on the time difference between the temperature, the temperature estimating means for estimating the temperature of the monitoring space based on the sound speed obtained by the sound speed detecting means, and the temperature estimated by the temperature estimating means and the specified temperature are compared. And a thermal type judgment means for judging the presence or absence of a fire.

  According to this invention, in the signal processing unit, in the sound speed detection means, the sound speed is detected based on a time difference from when the sound source unit transmits an ultrasonic wave until the ultrasonic wave is received by the receiving element. In the temperature estimation means, the temperature of the monitoring space is estimated based on the sound speed obtained by the sound speed detection means, and in the thermal judgment means, the temperature estimated by the temperature estimation means is compared with the specified temperature. Since the presence / absence is determined, it is possible to detect the fire even when the temperature rises at the time of the fire without using a separate temperature detecting element, and it becomes possible to detect the fire more reliably.

In the above invention, the response can be improved as compared with the scattered light type smoke detector, and the non-fire report can be reduced as compared with the reduced light type smoke detector.

In addition, the non-fire report can be reduced as compared with the scattered light smoke detector and the dimming smoke detector.

(Embodiment 1)
As shown in FIG. 1, the fire detector according to the present embodiment includes a sound source unit 1 that can transmit ultrasonic waves, a control unit 2 that controls the sound source unit 1, and an ultrasonic wave transmitted from the sound source unit 1. A wave receiving element 3 that detects sound pressure and a signal processing unit 4 that determines the presence or absence of a fire based on the output of the wave receiving element 3 are provided. Here, as shown in FIG. 2, the sound source unit 1 and the wave receiving element 3 are disposed so as to face each other on the one surface side of the circuit board 5 made of a disk-shaped printed board. A control unit 2 and a signal processing unit 4 are provided. Here, in the vicinity of the wave receiving element 3, a sound insulating wall 6 made of a sound insulating plate for preventing the ultrasonic waves generated outside the sound source unit 1 from entering the wave receiving element 3 is provided. In addition, a sound absorbing layer (not shown) for preventing the reflection of the ultrasonic wave transmitted from the sound source unit 1 is provided on the one surface of the circuit board 5, so that the super wave transmitted from the sound source unit 1 is provided. A sound wave can be prevented from being reflected by the circuit board 5 and incident on the wave receiving element 3, and interference of the reflected wave can be prevented. In particular, a continuous wave is transmitted as an ultrasonic wave transmitted from the sound source unit 1. It is effective when using. In the present embodiment, the circuit board 5 constitutes a base member on which the sound source unit 1 and the wave receiving element 3 are mounted on one surface side.

  In the present embodiment, a sound wave generating element that generates an ultrasonic wave by applying a thermal shock to air as described later is used as the sound source unit 1 to transmit an ultrasonic wave having a reverberation time shorter than that of a piezoelectric element. In addition, a capacitive microphone is used as the wave receiving element 3 in which the Q value of the resonance characteristics is sufficiently smaller than that of the piezoelectric element and the generation period of the reverberation component included in the received wave signal is short.

  Here, as shown in FIG. 3, the sound source unit 1 includes a heat insulating layer (heat insulation) made of a porous silicon layer on one surface (upper surface in FIG. 3) side of a base substrate 11 made of a single crystal p-type silicon substrate. Layer) 12 is formed, and a heating element layer 13 made of a metal thin film is formed on the surface side of the heat insulating layer 12 as a heating element portion, and is electrically connected to the heating element layer 13 on the one surface side of the base substrate 11. A pair of pads 14 and 14 are formed. The planar shape of the base substrate 11 is a rectangular shape, and the planar shapes of the heat insulating layer 12 and the heating element layer 13 are also formed in a rectangular shape. An insulating film (not shown) made of a silicon oxide film is formed on the surface of the base substrate 11 where the thermal insulating layer 12 is not formed on the one surface side.

  In the above-described sound source unit 1, when current is passed between the pads 14 and 14 at both ends of the heating element layer 13 to cause a sudden temperature change in the heating element layer 13, the air (medium) that is in contact with the heating element layer 13. A sudden temperature change (thermal shock) occurs (that is, a thermal shock is applied to the air in contact with the heating element layer 13). Accordingly, the air in contact with the heating element layer 13 expands when the temperature of the heating element layer 13 rises and contracts when the temperature of the heating element layer 13 decreases. Therefore, by appropriately controlling energization to the heating element layer 13 Ultrasonic waves that propagate in the air can be generated. In short, the sound wave generating element constituting the sound source unit 1 generates an ultrasonic wave propagating through the medium by converting a rapid temperature change of the heat generating body layer 13 accompanying energization to the heat generating body layer 13 into expansion and contraction of the medium. Therefore, it is possible to transmit single-pulse ultrasonic waves with less reverberation compared to the case where ultrasonic waves are generated by mechanical vibration like a piezoelectric element.

In the sound source unit 1 described above, a p-type silicon substrate is used as the base substrate 11, and the heat insulating layer 12 is formed of a porous layer made of a porous silicon layer having a porosity of about 60 to about 70%. Therefore, a porous silicon layer serving as the thermal insulating layer 12 can be formed by anodizing a part of the silicon substrate used as the base substrate 11 in an electrolytic solution composed of a mixed solution of hydrogen fluoride and ethanol. (Here, the porous silicon layer formed by the anodic oxidation treatment contains a large number of nanocrystalline silicon composed of microcrystalline silicon having a crystal grain size on the order of nanometers). Since the porous silicon layer has a lower thermal conductivity and heat capacity as the porosity becomes higher, the thermal conductivity and heat capacity of the heat insulating layer 12 are made smaller than the heat conductivity and heat capacity of the base substrate 11, and heat insulation is performed. By making the product of the thermal conductivity and the thermal capacity of the layer 12 sufficiently smaller than the product of the thermal conductivity and the thermal capacity of the base substrate 11, the temperature change of the heating element layer 13 can be efficiently transmitted to the air. The heat generating body layer 13 and the air can efficiently exchange heat, and the base substrate 11 can efficiently receive the heat from the heat insulating layer 12 and release the heat of the heat insulating layer 12 to generate heat. It is possible to prevent heat from the body layer 13 from being accumulated in the heat insulating layer 12. Note that the porosity formed by anodizing a single crystal silicon substrate having a thermal conductivity of 148 W / (m · K) and a heat capacity of 1.63 × 10 ⁶ J / (m ³ · K) is 60%. The porous silicon layer is known to have a thermal conductivity of 1 W / (m · K) and a heat capacity of 0.7 × 10 ⁶ J / (m ³ · K). In this embodiment, the heat insulating layer 12 is composed of a porous silicon layer having a porosity of approximately 70%, the heat conductivity of the heat insulating layer 12 is 0.12 W / (m · K), and the heat capacity is 0.00. It is 5 × 10 ⁶ J / (m ³ · K).

  The heating element layer 13 is formed of tungsten, which is a kind of refractory metal, but the material of the heating element layer 13 is not limited to tungsten, and for example, tantalum, molybdenum, iridium, aluminum, or the like may be employed. In the sound source unit 1 described above, the thickness of the base substrate 11 is 300 to 700 μm, the thickness of the heat insulating layer 12 is 1 to 10 μm, the thickness of the heating element layer 13 is 20 to 100 nm, and the thickness of each pad 14. However, these thicknesses are only examples and are not particularly limited. Further, Si is adopted as the material of the base substrate 11, but the material of the base substrate 11 is not limited to Si, and, for example, it can be made porous by anodizing treatment such as Ge, SiC, GaP, GaAs, InP or the like. Other semiconductor materials may be used, and in any case, a porous layer formed by making a part of the base substrate 11 porous can be used as the heat insulating layer 12.

As described above, the sound source unit 1 generates ultrasonic waves in accordance with the temperature change of the heating element layer 13 due to energization of the heating element layer 13 via the pair of pads 14 and 14. When the drive input waveform consisting of the drive voltage waveform or the drive current waveform applied to is a sine wave waveform having a frequency f1, for example, the frequency of the temperature oscillation generated in the heating element layer 13 is ideally the frequency f1 of the drive input waveform. The frequency f2 is doubled, and an ultrasonic wave having a frequency approximately twice that of the drive input waveform f1 can be generated. That is, the above-described sound source unit 1 has a flat frequency characteristic and can change the frequency of the generated ultrasonic wave over a wide range. In the sound source unit 1 described above, for example, a half-cycle isolated wave having a sine wave waveform is applied between the pair of pads 14 and 14 as a drive input waveform, so that a single-pulse ultrasonic wave with almost one cycle with little reverberation is generated. Can be generated. By using such single-pulse ultrasonic waves, interference due to reflection is less likely to occur, so that the sound absorbing layer can be made unnecessary. Further, in the sound source unit 1, since the heat insulating layer 12 is formed of a porous layer, the heat insulating layer 12 is compared with a case where the heat insulating layer 12 is formed of a non-porous layer (for example, a SiO ₂ film). As a result, the heat generation efficiency is improved, the efficiency of ultrasonic generation is increased, and the power consumption can be reduced.

  Although not shown, the control unit 2 that controls the sound source unit 1 gives a drive input waveform to the sound source unit 1 to drive the sound source unit 1, and a control circuit that includes a microcomputer that controls the drive circuit; It consists of

  Further, as shown in FIG. 4, the capacitance type microphone constituting the wave receiving element 3 has a rectangular frame-shaped frame 31 formed by providing a window hole 31a penetrating in the thickness direction in the silicon substrate. And a cantilever-type pressure receiving portion 32 disposed on one surface side of the frame 31 so as to straddle two opposing sides of the frame 31. Here, a thermal oxide film 35, a silicon oxide film 36 covering the thermal oxide film 35, and a silicon nitride film 37 covering the silicon oxide film 36 are formed on one surface side of the frame 31, and one end of the pressure receiving portion 32. Is supported by the frame 31 via the silicon nitride film 37, and the other end faces the silicon nitride film 37 in the thickness direction of the silicon substrate. Further, a fixed electrode 33 a made of a metal thin film (for example, a chromium film) is formed on a surface of the silicon nitride film 37 facing the other end of the pressure receiving portion 32, and the silicon nitride film 37 at the other end of the pressure receiving portion 32 is formed. A movable electrode 33b made of a metal thin film (for example, a chromium film) is formed on the opposite side of the opposite surface. A silicon nitride film 38 is formed on the other surface of the frame 31. The pressure receiving portion 32 is constituted by a silicon nitride film formed in a separate process from the silicon nitride films 37 and 38 described above.

  In the wave receiving element 3 composed of a capacitive microphone having the configuration shown in FIG. 4, a capacitor having the fixed electrode 33a and the movable electrode 33b as electrodes is formed, so that the pressure receiving portion 32 receives the pressure of the dense wave. As a result, the distance between the fixed electrode 33a and the movable electrode 33b changes, and the capacitance between the fixed electrode 33a and the movable electrode 33b changes. Therefore, if a DC bias voltage is applied between pads (not shown) provided on the fixed electrode 33a and the movable electrode 33b, a minute voltage change occurs between the pads according to the sound pressure of the ultrasonic waves. The sound pressure of ultrasonic waves can be converted into an electric signal.

  By the way, the signal processing unit 4 includes a smoke density estimation unit 41 that estimates the smoke density in the monitoring space between the sound source unit 1 and the wave receiving element 3 based on the attenuation amount from the reference value of the output of the wave receiving element 3. The smoke type estimation means 42 for comparing the smoke density estimated by the smoke density estimation means 41 with a predetermined threshold value to determine the presence or absence of a fire, and the sound source unit 1 transmits the ultrasonic wave, and then the ultrasonic wave A sound speed detecting means 43 for obtaining the sound speed based on the time difference until the wave receiving element 3 receives the wave, a temperature estimating means 44 for estimating the temperature of the monitoring space based on the sound speed obtained by the sound speed detecting means 43, Thermal type determination means 45 that compares the temperature estimated by the temperature estimation means 44 with a specified temperature to determine the presence or absence of a fire is provided. The signal processing unit 4 is configured by a microcomputer, and each of the means 41 to 45 is realized by mounting an appropriate program on the microcomputer. The signal processing unit 4 is provided with an A / D converter for analog-digital conversion of the output signal of the wave receiving element 3.

  The smoke density estimation means 41 estimates the smoke density based on the attenuation amount from the reference value of the output of the wave receiving element 3 that detects the sound pressure of the ultrasonic wave from the sound source unit 1. If the frequency of the transmitted ultrasonic wave is constant, the amount of attenuation increases approximately in proportion to the smoke concentration in the monitoring space, so the smoke concentration is based on the relationship data between the smoke concentration and attenuation measured in advance. If the relational expression between and the amount of attenuation is obtained and stored, the smoke density can be estimated from the amount of attenuation using the relational expression. The smoke type determination means 42 determines “no fire” when the smoke concentration estimated by the smoke concentration estimation means 41 is less than the above threshold value, while “no fire” when it exceeds the threshold value. And the fire detection signal is output to the control unit 2. Here, when the control unit 2 receives the fire detection signal from the smoke type determination means 42, the control unit 2 controls the drive input waveform to the sound source unit 1 so that an alarm sound including an audible sound wave is generated from the sound source unit 1. . Therefore, since the alarm sound can be generated from the sound source unit 1, it is not necessary to separately provide a speaker for outputting the alarm sound, and the entire fire detector can be reduced in size and cost.

  The sound speed detection means 43 obtains the sound speed using the distance between the sound source unit 1 and the wave receiving element 3 and the time difference. Moreover, the temperature estimation means 44 estimates the temperature of the said monitoring space from a sound speed using the well-known relational expression of the sound speed in air and absolute temperature. The thermal determination means 45 determines “no fire” if the temperature estimated by the temperature estimation means 44 is lower than the specified temperature, while “fire” if the temperature is higher than the specified temperature. And the fire detection signal is output to the control unit 2. Here, even when the control unit 2 receives the fire detection signal from the thermal determination unit 45, the drive input waveform to the sound source unit 1 is generated so that an alarm sound including an audible sound wave is generated from the sound source unit 1. To control.

  In the present embodiment, the fire detection signal output from the smoke determination unit 42 or the thermal determination unit 45 is output to the control unit 2, but is not limited to the control unit 2. You may make it output to an apparatus.

  In the fire detector according to the present embodiment described above, the smoke density estimation means 41 determines the monitoring space between the sound source unit 1 and the wave receiving element 3 based on the attenuation amount from the reference value of the output of the wave receiving element 3. The smoke density is estimated, and the smoke type judging means 42 compares the smoke density estimated by the smoke density estimating means 41 with a predetermined threshold value to judge the presence or absence of a fire. In the event of a fire, it is possible to eliminate the influence of background light, which is a problem with photoelectric smoke detectors such as light smoke detectors, and to eliminate the need for labyrinth bodies required for scattered light smoke detectors. Since smoke particles easily diffuse into the monitoring space, the response can be improved as compared with the scattered light type smoke detector, and the non-fire report can be reduced as compared with the reduced light type smoke detector. Furthermore, in the fire detector according to the present embodiment, the sound speed detection means 43 determines the sound speed based on the time difference from when the sound source unit 1 transmits an ultrasonic wave until the ultrasonic wave is received by the wave receiving element 3. The temperature estimation means 44 estimates the temperature of the monitoring space based on the sound speed obtained by the sound speed detection means 43, and the thermal type judgment means 45 compares the temperature estimated by the temperature estimation means 44 with the specified temperature. Therefore, it is possible to detect the fire even when the temperature rises at the time of the fire without using a separate temperature detecting element, and to detect the fire more reliably.

(Embodiment 2)
The basic configuration of the fire detector of the present embodiment shown in FIG. 5 is substantially the same as that of the first embodiment, and the configurations of the control unit 2 and the signal processing unit 4 are different. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably.

By the way, the inventors of the present application, as shown in FIG. 6, according to the type of suspended particles in the monitoring space between the sound source unit 1 and the wave receiving element 3, I got the knowledge that the relationship is different. Here, the sound pressure (hereinafter referred to as a reference sound pressure) received by the wave receiving element 3 in the absence of suspended particles in the monitoring space is defined as I ₀ , a dimming smoke densitometer (a dimming smoke detector). (I ₀ −I _x ), where I _x is the sound pressure received by the wave receiving element 3 in a state where suspended particles having a concentration of x% / m exist in the monitoring space. The value represented by / I ₀ is defined as the sound pressure attenuation rate, and in particular, the attenuation rate when x = 1 is defined as the unit attenuation rate. Here, it is assumed that the reference sound pressure I ₀ and the sound pressure I _x are detected under the same conditions except for the presence or absence of suspended particles in the monitoring space. “I” in FIG. 6 is an approximate curve showing the relationship between the output frequency and the unit attenuation rate of sound pressure when the suspended particles are black smoke particles (black circles are measured data), and “B” is the suspended particles. Approximate curve showing the relationship between the output frequency of white smoke particles and the unit attenuation rate of sound pressure (black square is measured data), “C” is the output frequency when the floating particles are steam particles It is an approximate curve (black triangle is measurement data) showing the relationship with the unit attenuation rate of sound pressure, and the unit attenuation rate shown here is when the distance between the sound source unit 1 and the receiving element 3 is set to 30 cm. The data for each output frequency. Each data at the right end in FIG. 6 is data when the output frequency is 82 kHz, and FIG. 7 shows the result of normalizing the unit attenuation rate of each output frequency with the data when the output frequency is 82 kHz as 1. . In short, in FIG. 7, the horizontal axis represents the output frequency, and the vertical axis represents the relative unit attenuation rate. The size of white smoke particles is about 800 nm, the size of black smoke particles is about 200 nm, and the size of steam particles is about several μm to 20 μm.

  Based on the above knowledge, in the present embodiment, the control unit 2 controls the sound source unit 1 so that plural types of ultrasonic waves having different frequencies are sequentially transmitted from the sound source unit 1, and the signal processing unit 4. Is at least the reference output of the wave receiving element 3 (the output of the wave receiving element 3 with respect to the reference sound pressure), the output frequency of the sound source unit 1 and the wave receiving element corresponding to the type of floating particles present in the monitoring space and the concentration of floating particles 3 relative data of the relative unit attenuation rate of output (data extracted from FIG. 7 described above), unit attenuation rate at a specific frequency (for example, 82 kHz) with respect to smoke particles (data extracted from FIG. 6 described above) Is stored in the monitoring space using the storage means 48 storing the signal, the output of the wave receiving element 3 for each ultrasonic wave transmitted from the sound source unit 1 and the relational data stored in the storage means 48. The type of particles The particle type estimation means 46 for performing the measurement, and when the particles estimated by the particle type estimation means 46 are smoke particles, the attenuation from the reference value of the output of the wave receiving element 3 with respect to the ultrasonic wave of a specific frequency (for example, 82 kHz) Based on the smoke density estimation means 47 for estimating the smoke density of the monitoring space based on the above, the smoke type judgment means 42 for judging the presence or absence of a fire by comparing the smoke density estimated by the smoke density estimation means 47 with a predetermined threshold value. And so on.

  Below, the operation example of the fire detector of this embodiment is demonstrated with reference to the flowchart of FIG. First, a plurality of types of ultrasonic waves are sequentially transmitted from the sound source unit 1, and the output of the wave receiving element 3 for each ultrasonic wave is measured by the signal processing unit 4 (step S11). The particle type estimation means 46 obtains the sound pressure attenuation rate from the output of the wave receiving element 3 and the reference output stored in the storage means 48 for each output frequency (step S12), and the sound at the output frequency of 82 kHz. The ratio of the sound pressure attenuation rate at 20 kHz to the pressure attenuation rate is calculated (step S13). In the storage means 48, as the above relational data between the output frequency of the sound source unit 1 and the relative unit attenuation rate of the output of the wave receiving element 3, the relative unit at 20 kHz with respect to the relative unit attenuation rate at the output frequency of 82 kHz is stored. A ratio of attenuation rates (in the case of FIG. 7, white smoke is 0, black smoke is 0.2, steam is 0.5) is stored, and the particle type estimation means 46 calculates the calculated attenuation rate ratio. Compared with the relational data stored in the storage means 48, the type of particle having the closest ratio of the attenuation rate in the relational data is estimated as the particle floating in the monitoring space (step S14). Here, if the estimated particles are smoke particles, the process proceeds to the processing in the smoke concentration estimating means 47 (step S15). Here, in the case of white smoke, as shown in FIG. 9, the relationship between the smoke density measured by the dimming smoke densitometer and the sound pressure attenuation rate is data that can be represented by a straight line, and other particles Therefore, the smoke density estimation means 47 is a unit stored in the storage means 48 of the attenuation factor of the output of the wave receiving element 3 with respect to ultrasonic waves of a specific frequency (for example, 82 kHz) for the estimated particle type. A ratio with respect to the attenuation rate is calculated, and when the value of the ratio is y, it is estimated that the smoke density in the monitoring space corresponds to the smoke density y% / m in the evaluation with the dimming smoke densitometer (step S16). The smoke type determination means 42 compares the smoke density estimated in step S16 with a predetermined threshold (for example, a smoke density that is 10% / m as evaluated by a dimming smoke densitometer) to estimate the smoke. When the concentration is less than the above threshold, it is determined that “no fire”, while when it is equal to or greater than the above threshold, it is determined that “fire exists” and a fire detection signal is output to the control unit 2.

  In the above example, the particle type estimation means 46 uses the attenuation rate when the output frequency is 82 kHz and the attenuation rate when the output frequency is 20 kHz. However, the present invention is not limited to the combination of these output frequencies, and different combinations are possible. An output frequency may be used. Furthermore, attenuation rates for more output frequencies may be used, and in that case, the accuracy of estimation of the particle type can be improved. In this embodiment, the smoke density estimation means 47 targets one frequency as the specific frequency, but targets a plurality of frequencies as the specific frequency, and obtains an average value of the smoke density estimated for each specific frequency. In this case, the accuracy of smoke density estimation is improved. The signal processing unit 4 is constituted by a microcomputer, and the particle type estimation means 46, the smoke concentration estimation means 47, and the smoke type determination means 42 are realized by mounting an appropriate program on the microcomputer. Yes. The signal processing unit 4 is provided with an A / D converter for analog-digital conversion of the output signal of the wave receiving element 3.

  In the present embodiment, one sound wave generating element described in the first embodiment is used as the sound source unit 1, and the above-described control unit 2 sequentially changes the frequency of the drive input waveform applied to the sound source unit 1. A plurality of types of ultrasonic waves having different frequencies are sequentially transmitted from the sound source unit 1. Here, the control unit 2 changes the frequency of the ultrasonic wave transmitted from the sound source unit 1 from the lower limit frequency (for example, 20 kHz) to the upper limit frequency (for example, 82 kHz) in a predetermined frequency range (for example, 20 kHz to 82 kHz). . In the present embodiment, the control unit 2 is configured to control the sound source unit 1 so that four types of ultrasonic waves having different frequencies are sequentially transmitted from the sound source unit 1. The frequency of the ultrasonic wave to be waved is not limited to four types and may be a plurality of types. For example, if two types are used, the control unit 2 and the signal processing unit are compared with the case where three or more types of ultrasonic waves are sequentially transmitted. 4 can be reduced, and the control unit 2 and the signal processing unit 4 can be simplified. Further, in the present embodiment, as described above, the sound wave generating element described in the first embodiment is used as the sound source unit 1 and can transmit a single-pulse ultrasonic wave. If the sound wave is a single-pulse ultrasonic wave having a different frequency, a plurality of piezoelectric elements having different resonance frequencies are used as the sound source unit 1 and the ultrasonic wave of the continuous wave is transmitted from each piezoelectric element. Cost and power consumption can be reduced. In addition, since a plurality of types of ultrasonic waves can be transmitted by a single sound wave generating element, the sound source unit 1 can be reduced in size and cost compared to the case where a plurality of sound wave generating elements capable of transmitting various types of ultrasonic waves are provided. It becomes.

In the present embodiment, the example in which the relationship data between the output frequency of the sound source unit 1 and the relative unit attenuation rate of the output of the receiving element 3 is stored in the storage unit 48 has been shown. Since the amount of attenuation (I ₀ −I _x ) from the reference value of the output of the wave receiving element 3 changes for each output frequency of the sound source unit 1 according to the type of particle, the above relationship stored in the storage means 48 The data may be data indicating the relationship between the output frequency of the sound source unit 1 and the attenuation amount from the reference value of the output of the wave receiving element 3. Instead of the above relative unit attenuation rate, for example, the wave receiving element Attenuation amount from the reference value of the output of 3 or the attenuation value obtained by dividing the attenuation amount from the reference value of the output of the receiving element 3 by the reference value (I ₀ ), or related data adopting the unit attenuation rate You may make it memorize | store in the memory | storage means 48. FIG.

  In the fire detector of the present embodiment described above, in the particle type estimation unit 46, the relationship between the output of the receiving element 3 for each ultrasonic wave transmitted from the sound source unit 1 and the storage unit 48 is stored. The type of particles floating in the monitoring space is estimated using the data, and when the particle estimated by the particle type estimation unit 46 is a smoke particle, the smoke density estimation unit 47 uses the ultrasonic wave of a specific frequency. The smoke density in the monitoring space is estimated based on the attenuation amount from the reference value of the output of the wave receiving element 3 with respect to the smoke density, and the smoke type estimating means 42 uses the smoke density estimated by the smoke density estimating means 47 and a predetermined threshold value. To determine the presence or absence of a fire, so it is possible to eliminate the influence of background light, which is a problem with photoelectric smoke detectors such as scattered light smoke detectors and dimming smoke detectors. Labyrin required for optical smoke detectors Body and can improve the response in comparison with the light scattering type smoke sensor and can be eliminated, also the reduction of non-fire report is made possible as compared with the dimming smoke sensor. Moreover, since the particle type estimation means 46 can identify the smoke particles and steam by estimating the type of particles floating in the monitoring space, the scattered light type smoke detector and the dimming type smoke detector can be used. In comparison, non-fire reports due to steam can be reduced, making it suitable for use in kitchens and bathrooms. Further, since the white smoke particles and the black smoke particles can be discriminated by the particle type estimation means 46, it is also possible to use it for identifying the nature of the fire. In addition, it is possible to distinguish between dust and smoke particles floating when cleaning the room where the fire detector is installed or for electrical work behind the ceiling, so reduce non-fire reports caused by dust. Is also possible.

  By the way, in this embodiment, the sound source unit 1 is constituted by a single sound wave generating element, and the control unit 2 sequentially changes the frequency of the drive input waveform applied to the sound source unit 1, so that a plurality of types having different frequencies from the sound source unit 1 can be obtained. However, the sound source unit 1 may be composed of a plurality of sound wave generating elements 1a having different output frequencies as shown in FIG. In this case, an element that generates ultrasonic waves by mechanical vibration, such as a piezoelectric element, is used as each sound wave generating element 1a, and each sound wave generating element 1a is driven at the respective resonance frequency to be transmitted from the sound source unit 1. The sound pressure of the ultrasonic wave that is waved can be increased. When the sound pressure of the ultrasonic wave from the sound source unit 1 is increased, the fluctuation range of the sound pressure of the ultrasonic wave received by the wave receiving element 3 is widened. There is an advantage that the amount of change in output increases and the SN ratio improves. Further, in the example of FIG. 10, a plurality of wave receiving elements 3 respectively associated with each sound wave generating element 1a are provided, and each wave receiving element 3 receives an ultrasonic wave from each sound wave generating element 1a corresponding thereto. It is configured. Therefore, the sensitivity of the wave receiving element 3 is obtained by using a piezoelectric element or the like having a relatively large Q value of the resonance characteristics as each wave receiving element 3 and using each wave receiving element 3 for receiving an ultrasonic wave of each resonance frequency. And can contribute to the improvement of the SN ratio. In this case, not only the respective sound wave generating elements 1a are sequentially driven to sequentially transmit plural kinds of ultrasonic waves, but also the plural sound wave generating elements 1a are simultaneously driven to simultaneously transmit plural kinds of ultrasonic waves. Is also possible. If multiple types of ultrasonic waves are transmitted simultaneously, the amount of attenuation of the sound pressure of multiple types of ultrasonic waves is detected at the same time, thereby being affected by changes over time in the monitoring space (for example, changes in the concentration of suspended particles). Since the attenuation of sound pressure can be detected for a plurality of types of ultrasonic waves under the same conditions, the type of suspended particles and the smoke concentration can be accurately estimated.

  Further, as shown in FIG. 11, a single wave receiving element 3 is provided for the sound source unit 1 including a plurality of sound wave generating elements 1a, and each sound wave generating element 1a is sequentially driven to sequentially transmit a plurality of types of ultrasonic waves. The plurality of types of ultrasonic waves may be sequentially received by the single receiving element 3. In this case, it is desirable to use, as the wave receiving element 3, an element having a small Q value of the resonance characteristics, such as the capacitive microphone described in the first embodiment. In the example of FIG. 11, the cost of the wave receiving element 3 and the size of the fire detector can be reduced as compared with the case where a plurality of wave receiving elements 3 are provided.

  Furthermore, for example, a sound wave generating element 1a that can be used for both transmission and reception of ultrasonic waves, such as a piezoelectric ultrasonic sensor, is used, and as shown in FIG. It is also conceivable that the sound wave generating element 1 a is also used as the wave receiving element 3 by connecting to the signal processing unit 4. In the example of FIG. 12, the sound source unit 1 is composed of a plurality of sound wave generating elements 1a, and the reflection wall 7 that reflects the ultrasonic wave transmitted from each sound wave generating element 1a toward the sound wave generating element 1a is used as the sound source unit. 1 so that each of the sound wave generating elements 1a can receive the reflected wave of the ultrasonic wave transmitted by itself. Here, the ultrasonic wave transmitted from the sound wave generating element 1 a reciprocates between the reflection wall 7 and the sound wave generating element 1 a and is received by the sound wave generating element 1 a functioning as the wave receiving element 3. The space between the sound wave generating element 1a and the reflecting wall 7 becomes a monitoring space. In this case, although the reflection wall 7 for reflecting the ultrasonic wave transmitted from the sound wave generating element 1a toward the sound wave generating element 1a is required, the cost can be reduced by reducing the number of elements.

  Further, as shown in FIG. 13, by using the single sound wave generating element 1a described in the first embodiment as the sound source unit 1, and sequentially changing the frequency of the drive input waveform given to the sound source unit 1 by the control unit 2, While a plurality of types of ultrasonic waves having different frequencies are sequentially transmitted from the sound source unit 1, a plurality of wave receiving elements 3 may be provided. In this case, each receiving element 3 is used for receiving ultrasonic waves having different frequencies. Therefore, the sensitivity of the wave receiving element 3 is obtained by using a piezoelectric element or the like having a relatively large Q value of the resonance characteristics as each wave receiving element 3 and using each wave receiving element 3 for receiving an ultrasonic wave of each resonance frequency. And can contribute to the improvement of the SN ratio. In the configuration in which a plurality of types of ultrasonic waves are received by one receiving element 3, if the sensitivity of the receiving element 3 differs for each frequency, the SN ratio varies for each type of ultrasonic wave. In the configuration in which the reception of various ultrasonic waves is performed by the individual wave receiving elements 3 as described above, by varying the sensitivity of the wave receiving elements 3, it is possible to suppress variation in the SN ratio for each type of ultrasonic wave. it can.

  By the way, the signal processing unit 4 periodically changes the output of the sound source unit 1 and the wave receiving element 3 based on the output of the wave receiving element 3 with respect to an ultrasonic wave having a predetermined frequency (for example, 82 kHz which is the same as the specific frequency described above). If at least one of the control condition of the sound source unit 1 by the control unit 2 and the signal processing condition of the output of the wave receiving element 3 is changed so that the sensitivity fluctuation of the sound source unit 1 is canceled, Sensitivity fluctuations of the wave element 3 can be periodically canceled, and long-term reliability is improved.

  In the fire detector of the present embodiment, the sound speed detection means 43, the temperature estimation means 44, and the thermal determination means 45 may be provided in the signal processing unit 4 as in the first embodiment shown in FIG.

  By the way, in each of the above embodiments, the sound source unit 1, the control unit 2, the wave receiving element 3, and the signal processing unit 4 are provided on one circuit board 5 and housed in a container (not shown). And a sound source unit provided with the control unit 2 and a receiving unit provided with the receiving element 3 and the signal processing unit 4 as separate bodies to constitute a separate type fire detector. It may be. Further, the sound source unit 1 is not limited to the sound wave generating element having the configuration shown in FIG. 3 described above. For example, a rapid temperature change of the heat generating unit accompanying energization of the heat generating unit with a thin aluminum plate as the heat generating unit. A sound wave may be generated by a thermal shock due to.

  Moreover, in each said embodiment, if the control part 2 is made to transmit the ultrasonic wave of the frequency which has an insect-proof effect from the sound source part 1, it can prevent that an insect penetrate | invades in the said monitoring space, Non-fire reports caused by insects can be reduced. Here, the control unit 2 may periodically transmit ultrasonic waves having a frequency having an insect-proofing effect separately from the ultrasonic waves having a frequency transmitted from the sound source unit 1 in order to estimate the smoke density. In order to estimate the smoke concentration, the frequency of the ultrasonic wave transmitted from the sound source unit 1 may be set to a frequency having an insect-proof effect.

It is a block diagram of the fire detector of Embodiment 1. The principal part of the fire detector in the same as above is shown, (a) is a schematic bottom view, (b) is a schematic side view. It is a schematic sectional drawing of the sound wave generation element which comprises the sound source part in the same as the above. The wave receiving element in the same as above is shown, (a) is a schematic perspective view partly broken, and (b) is a schematic cross-sectional view. It is a block diagram of the fire detector of Embodiment 2. It is a related figure of the output frequency of a sound source part in the same as above, and the unit attenuation rate of sound pressure. It is a related figure of the output frequency of a sound source part in the same as above, and a relative unit attenuation factor. It is a flowchart which shows the operation example same as the above. It is a related figure between the smoke density | concentration in the same as the above, and the attenuation factor of the ultrasonic wave of a specific frequency. It is a block diagram which shows the other example same as the above. It is a block diagram which shows another example same as the above. It is a block diagram which shows another example same as the above. It is a block diagram which shows another example same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sound source part 1a Sound wave generation element 2 Control part 3 Receiving element 4 Signal processing part 5 Circuit board (base member)
6 Sound insulation wall 11 Base substrate 12 Thermal insulation layer 13 Heating element layer (heating element part)
DESCRIPTION OF SYMBOLS 14 Pad 41 Smoke density estimation means 42 Smoke type judgment means 43 Sonic speed detection means 44 Temperature estimation means 45 Thermal type judgment means 46 Particle type estimation means 47 Smoke density estimation means 48 Storage means

Claims (18)

A sound source unit capable of transmitting ultrasonic waves, a control unit for controlling the sound source unit, a receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and a fire based on the output of the receiving element A signal processing unit for determining the presence or absence of smoke, and the signal processing unit is configured to estimate smoke concentration in a monitoring space between the sound source unit and the wave receiving element based on an attenuation amount from a reference value of the output of the wave receiving element. a concentration estimating unit, and a smoke type determination means for comparing the estimated smoke density with a predetermined threshold value at a smoke density estimation unit determines the presence or absence of fire possess,
The sound source unit can transmit a plurality of types of ultrasonic waves having different frequencies, and the signal processing unit is configured to output the output frequency of the sound source unit according to the type of suspended particles present in the monitoring space and the smoke concentration, and the Stored in the storage means for storing the relationship data with the attenuation amount from the reference value of the output of the receiving element, and the output of the receiving element for each ultrasonic wave transmitted from the sound source unit and stored in the storing means Particle type estimation means for estimating the type of particles floating in the monitoring space using the relationship data, and the smoke concentration estimation means is configured such that the particles estimated by the particle type estimation means are smoked. A fire detector for estimating a smoke concentration in the monitoring space based on an attenuation amount from a reference value of an output of the receiving element with respect to an ultrasonic wave of a specific frequency in the case of particles . The storage means stores, as the relationship data, relationship data between an output frequency of the sound source unit and an attenuation rate obtained by dividing an attenuation amount from a reference value of the output of the receiving element by a reference value. The fire detector according to claim 1. The sound source unit includes a single sound wave generating element capable of transmitting the plurality of types of ultrasonic waves, and the control unit controls the sound source unit so that the plurality of types of ultrasonic waves are sequentially transmitted from the sound wave generating elements. claim 1 or fire detector according to claim 2, characterized in that. The sound source unit fire detector according to claim 1 or claim 2, wherein the consisting of mutually different frequencies of the plurality of sound-wave generating element capable transmit ultrasonic waves. The control unit may fire detector according to any one of claims 1 to 4, characterized in that to transmit two different ultrasonic frequencies from the sound source unit. The said control part changes the frequency of the ultrasonic wave transmitted from the said sound source part from the lower limit frequency of a predetermined frequency range to an upper limit frequency, The one of Claim 1 thru | or 4 characterized by the above-mentioned. Fire detector. The signal processing unit periodically has at least one of a control condition of the sound source unit by the control unit and a signal processing condition of the output of the receiving element based on an output of the receiving element with respect to an ultrasonic wave of a predetermined frequency fire detector according to any one of claims 1 to 6, characterized in that to change the. The control unit may fire detector according to any one of claims 1 to 7 and this with features for transmitting ultrasonic waves of frequencies of insect repellent from the sound source unit. 9. The sound insulation wall according to claim 1 , wherein a sound insulation wall is provided around the wave receiving element to prevent ultrasonic waves from entering the wave receiving element from other than the sound source unit . 10. The fire detector described. The sound source unit and the wave receiving element are provided with a base member mounted on one surface side, and a sound absorbing layer for preventing reflection of ultrasonic waves transmitted from the sound source unit is provided on the one surface of the base member. It is claims 1, characterized by comprising to a fire detector according to any one of claims 9. A sound source unit capable of transmitting ultrasonic waves, a control unit for controlling the sound source unit, a receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and a fire based on the output of the receiving element A signal processing unit for determining the presence or absence of smoke, and the signal processing unit is configured to estimate smoke concentration in a monitoring space between the sound source unit and the wave receiving element based on an attenuation amount from a reference value of the output of the wave receiving element. A smoke estimator that compares the smoke concentration estimated by the smoke estimator with a predetermined threshold to determine the presence or absence of a fire;
The sound source unit, fire detectors you characterized in that to generate ultrasonic waves by applying thermal shock to the air by the temperature change of the heating element due to the energization of the heating element. The sound source unit is formed between the heat generating unit and the base substrate on the one surface side of the base substrate, and the heat generating unit and the base are formed on the one surface side of the base substrate. 12. The fire detector according to claim 11 , further comprising a thermal insulation layer comprising a porous layer that thermally insulates the substrate . The fire detector according to claim 11 or 12 , wherein the control unit transmits single-pulse ultrasonic waves as ultrasonic waves from the sound source unit. A sound source unit capable of transmitting ultrasonic waves, a control unit for controlling the sound source unit, a receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and a fire based on the output of the receiving element A signal processing unit for determining the presence or absence of smoke, and the signal processing unit is configured to estimate smoke concentration in a monitoring space between the sound source unit and the wave receiving element based on an attenuation amount from a reference value of the output of the wave receiving element. A smoke estimator that compares the smoke concentration estimated by the smoke estimator with a predetermined threshold to determine the presence or absence of a fire;
Wherein, fire detectors shall be the this and features for transmitting ultrasonic waves of frequencies of insect repellent from the sound source unit. A sound source unit capable of transmitting ultrasonic waves, a control unit for controlling the sound source unit, a receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and a fire based on the output of the receiving element A signal processing unit for determining the presence or absence of smoke, and the signal processing unit is configured to estimate smoke concentration in a monitoring space between the sound source unit and the wave receiving element based on an attenuation amount from a reference value of the output of the wave receiving element. A smoke estimator that compares the smoke concentration estimated by the smoke estimator with a predetermined threshold to determine the presence or absence of a fire;
Fire detector you wherein sound insulating wall that is provided with ultrasound to the wave-receiving element from outside the sound source portion to the peripheral is prevented from entering the wave receiving devices. A sound source unit capable of transmitting ultrasonic waves, a control unit for controlling the sound source unit, a receiving element for detecting the sound pressure of the ultrasonic wave transmitted from the sound source unit, and a fire based on the output of the receiving element A signal processing unit for determining the presence or absence of smoke, and the signal processing unit is configured to estimate smoke concentration in a monitoring space between the sound source unit and the wave receiving element based on an attenuation amount from a reference value of the output of the wave receiving element. A smoke estimator that compares the smoke concentration estimated by the smoke estimator with a predetermined threshold to determine the presence or absence of a fire;
The sound source unit and the wave receiving element are provided with a base member mounted on one surface side, and a sound absorbing layer for preventing reflection of ultrasonic waves transmitted from the sound source unit is provided on the one surface of the base member. are fire sensors you characterized by comprising. 17. The control unit according to claim 1, wherein the control unit generates an alarm sound including an audible sound wave from the sound source unit when the signal processing unit determines that there is a fire. Fire detector according to item. The signal processing unit is obtained by a sound speed detecting unit that obtains a sound speed based on a time difference from when the sound source unit transmits an ultrasonic wave until the ultrasonic wave is received by the receiving element, and a sound speed detecting unit. Temperature estimation means for estimating the temperature of the monitoring space based on the sound speed, and thermal type determination means for comparing the temperature estimated by the temperature estimation means and the specified temperature to determine the presence or absence of a fire. The fire detector according to any one of claims 1 to 17.

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