JP4950842B2 - Airborne particle measurement system - Google Patents

Airborne particle measurement system Download PDF

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JP4950842B2
JP4950842B2 JP2007279707A JP2007279707A JP4950842B2 JP 4950842 B2 JP4950842 B2 JP 4950842B2 JP 2007279707 A JP2007279707 A JP 2007279707A JP 2007279707 A JP2007279707 A JP 2007279707A JP 4950842 B2 JP4950842 B2 JP 4950842B2
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sound source
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祥文 渡部
由明 本多
雅則 林
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Panasonic Corp
Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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本発明は、監視空間に存在する浮遊粒子の種別および濃度を測定する浮遊粒子測定システムに関するものである。   The present invention relates to a suspended particle measurement system that measures the type and concentration of suspended particles present in a monitoring space.

従来から、たとえば煙濃度を測定することによる火災の発生の有無の判断や、半導体の製造プロセスで使用されるクリーンルームの状態の管理などを目的として、監視空間に存在する浮遊粒子（煙粒子、粉塵、湯気など）の種別および濃度を測定する浮遊粒子測定システムが提案されている。   Conventionally, suspended particles (smoke particles, dust, etc.) that exist in the monitoring space are used for the purpose of determining the presence or absence of a fire by measuring the smoke concentration, for example, and managing the state of the clean room used in the semiconductor manufacturing process. Suspended particle measuring systems that measure the type and concentration of steam, steam, etc.) have been proposed.

この種の浮遊粒子測定システムとしては、レーザ光の浮遊粒子による散乱光を用いて浮遊粒子の種別（大きさ）や濃度（個数）を測定するものが知られている（たとえば特許文献１、特許文献２参照）。ここにおいて、特許文献１に記載の浮遊粒子測定システムは、レーザ光を分波器により２分した一方のレーザ光を浮遊粒子に照射して散乱光を生じさせ、他方のレーザ光を周波数偏移させた後に前記散乱光と合成し、当該合成光を光検出器で受光してビート信号を検出、処理する光ヘテロダイン法を用いて浮遊粒子の大きさおよび個数を計測する。一方、特許文献２に記載の浮遊粒子測定システムは、レーザ発振器から発せられたレーザ光を複数の鏡面を備えたポリゴンミラーにより走査させ、走査光の浮遊粒子による散乱光を矩形の開口部を有するマスクを介してＣＣＤカメラにより検出し、検出された散乱光に基づき浮遊粒子の量を測定する。   As this kind of suspended particle measurement system, a system that measures the type (size) and concentration (number) of suspended particles using scattered light of suspended particles of laser light is known (for example, Patent Document 1, Patent). Reference 2). Here, the suspended particle measuring system described in Patent Document 1 irradiates the suspended particles with one of the laser beams divided into two by a demultiplexer to generate scattered light, and frequency shifts the other laser beam. Then, the size and number of suspended particles are measured using an optical heterodyne method in which the synthesized light is combined with the scattered light, and the combined light is received by a photodetector to detect and process a beat signal. On the other hand, the suspended particle measuring system described in Patent Document 2 scans laser light emitted from a laser oscillator with a polygon mirror having a plurality of mirror surfaces, and has a rectangular opening for scattered light from the suspended particles of the scanned light. It is detected by a CCD camera through a mask, and the amount of suspended particles is measured based on the detected scattered light.

ところで、上述したようにレーザ光の浮遊粒子による散乱光を用いる浮遊粒子測定システムは、レーザ光源と光検出器（あるいはＣＣＤカメラ）の他にレーザ光を分波する分波器やレーザ光を走査させるポリゴンミラーなどの光学部材が必要となり、システムが大掛かりで大型且つ高価なものになるという問題がある。
特開昭６３−６３９４４号公報 特開平７−２２９８２６号公報 By the way, as described above, the suspended particle measurement system using the scattered light by the suspended particles of the laser beam scans the demultiplexer for dividing the laser beam and the laser beam in addition to the laser light source and the photodetector (or CCD camera). There is a problem that an optical member such as a polygon mirror is required, and the system is large, large, and expensive.
JP-A 63-63944 Japanese Patent Laid-Open No. 7-229826

上述した散乱光を用いる浮遊粒子測定システムの問題点を解決するために、本願出願人は、音波（たとえば超音波）を用いて浮遊粒子の濃度を測定する浮遊粒子測定システムを提案している。   In order to solve the problems of the suspended particle measurement system using scattered light, the applicant of the present application has proposed a suspended particle measurement system that measures the concentration of suspended particles using sound waves (for example, ultrasonic waves).

この浮遊粒子測定システムは、図１５に示すように、超音波を送波可能な音源部１と、音源部１を制御する制御部２と、音源部１から送波された超音波の音圧を検出する受波素子３と、受波素子３の出力に基づいて音源部１と受波素子３との間の監視空間に存在する浮遊粒子の濃度を測定する信号処理部４とを備える。信号処理部４は、受波素子３の出力の基準値からの減衰量に基づいて監視空間の浮遊粒子の濃度を推定する濃度推定手段４２を有する。すなわち、監視空間に粒子が入り込むと音源部１からの超音波は受波素子３に到達するまでに音圧が低下し、受波素子３の出力の減衰量は監視空間の浮遊粒子の濃度に略比例して増加するので、この減衰量に基づき浮遊粒子の濃度を推定することができる。   As shown in FIG. 15, the suspended particle measurement system includes a sound source unit 1 capable of transmitting ultrasonic waves, a control unit 2 that controls the sound source unit 1, and a sound pressure of ultrasonic waves transmitted from the sound source unit 1. And a signal processing unit 4 that measures the concentration of suspended particles existing in the monitoring space between the sound source unit 1 and the wave receiving element 3 based on the output of the wave receiving element 3. The signal processing unit 4 includes concentration estimation means 42 that estimates the concentration of suspended particles in the monitoring space based on the attenuation amount from the reference value of the output of the wave receiving element 3. That is, when particles enter the monitoring space, the sound pressure of the ultrasonic waves from the sound source unit 1 decreases before reaching the wave receiving element 3, and the attenuation of the output of the wave receiving element 3 becomes the concentration of suspended particles in the monitoring space. Since it increases approximately proportionally, the concentration of suspended particles can be estimated based on this attenuation.

ところで、本願出願人は、音源部１と受波素子３との間の監視空間の浮遊粒子の種別に応じて図１６に示すように音源部１の出力周波数と音圧の単位減衰率との関係が異なるという知見を得た。ここで、監視空間に浮遊粒子が存在しない状態で受波素子３にて受波される音圧（以下、基準音圧という）をＩ０、減光式煙濃度計（減光式煙感知器）での評価でｘ〔％／ｍ〕となる濃度の浮遊粒子が監視空間に存在する状態で受波素子３にて受波される音圧をＩｘとしたときに、（Ｉ０−Ｉｘ）／Ｉ０で表される値を音圧の減衰率と定義し、特にｘ＝１のときの減衰率を単位減衰率と定義する。ここにおいて、基準音圧Ｉ０と音圧Ｉｘとは、監視空間における浮遊粒子の有無を除いては同一の条件で検出されるものとする。図１６中の「イ」は浮遊粒子が黒煙の煙粒子である場合の出力周波数と音圧の単位減衰率との関係を示す近似曲線（黒丸が測定データ）、「ロ」は浮遊粒子が白煙の煙粒子である場合の出力周波数と音圧の単位減衰率との関係を示す近似曲線（黒四角が測定データ）、「ハ」は浮遊粒子が湯気の粒子である場合の出力周波数と音圧の単位減衰率との関係を示す近似曲線（黒三角が測定データ）であり、ここに示す単位減衰率は、音源部１と受波素子３との間の距離を３０ｃｍに設定したときの各出力周波数ごとのデータである。また、図１６における右端の各データは、出力周波数が８２ｋＨｚのときのデータであり、出力周波数が８２ｋＨｚのときのデータを１として各出力周波数の単位減衰率を規格化した結果を図１７に示す。要するに、図１７は、横軸が出力周波数、縦軸が相対的単位減衰率となっている。また、白煙の煙粒子のサイズは８００ｎｍ程度、黒煙の煙粒子のサイズは２００ｎｍ程度、湯気の粒子のサイズは数μｍ〜２０μｍ程度である。 By the way, the applicant of the present application determines the output frequency of the sound source unit 1 and the unit attenuation rate of the sound pressure as shown in FIG. 16 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 (darkening smoke detector) the sound pressure of airborne particles of the concentration to be x [% / m] is reception at wave receiving element 3 in the state they exist in the monitoring space when the I x evaluation at), (I 0 -I The value represented by x 1 ) / 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. “A” in FIG. 16 is an approximate curve showing the relationship between the output frequency and 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. Further, each data at the right end in FIG. 16 is data when the output frequency is 82 kHz, and FIG. 17 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. 17, 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.

上述の知見に基づいて、本願出願人は、音源部１から周波数の異なる複数種の超音波が送波されるようにし、信号処理部４に、少なくとも受波素子３の出力の基準値（基準音圧に対する受波素子３の出力）、上記監視空間に存在する浮遊粒子の種別および浮遊粒子濃度に応じた音源部１の出力周波数と受波素子３の出力の相対的単位減衰率との関係データ（上述の図１７より抽出されるデータ）、各浮遊粒子に関して特定周波数（たとえば、８２ｋＨｚ）における単位減衰率（上述の図１６より抽出されるデータ）を記憶した記憶手段４４と、音源部１から送波された各周波数の超音波ごとの受波素子３の出力と記憶手段４４に記憶されている関係データとを用いて上記監視空間に浮遊している粒子の種別を推定する粒子種別推定手段４１とを付加し、特定周波数（たとえば、８２ｋＨｚ）の超音波に対する受波素子３の出力の基準値からの減衰量に基づいて上記監視空間の浮遊粒子の濃度を濃度推定手段４２に推定させることを提案している。   Based on the above-described knowledge, the applicant of the present application causes a plurality of types of ultrasonic waves having different frequencies to be transmitted from the sound source unit 1, and sends at least a reference value (reference value) of the output of the receiving element 3 to the signal processing unit 4. The output of the wave receiving element 3 with respect to the sound pressure), the relationship 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 according to the type of suspended particles present in the monitoring space and the suspended particle concentration Storage means 44 storing data (data extracted from the above-described FIG. 17), unit attenuation rate (data extracted from the above-described FIG. 16) at a specific frequency (for example, 82 kHz) for each suspended particle, and the sound source unit 1 Particle type estimation that estimates the type of particles floating in the monitoring space using the output of the receiving element 3 for each ultrasonic wave transmitted from the frequency and the relational data stored in the storage means 44 Means 41 and In addition, it is proposed to cause the concentration estimating means 42 to estimate the concentration of suspended particles in the monitoring space based on the attenuation amount 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). ing.

この超音波式の浮遊粒子測定システムでは、散乱光を用いる浮遊粒子測定システムに必要な光学部材が不要であるから、システムを簡略化でき小型且つ安価なものとすることが可能になる。   In this ultrasonic suspended particle measuring system, the optical member necessary for the suspended particle measuring system using scattered light is unnecessary, so that the system can be simplified and can be made small and inexpensive.

しかしながら、上述のように浮遊粒子の種別を推定可能とするためには、音源部１から周波数の異なる複数種の超音波を送波させることが必要であり、これにより以下の問題を生じる。すなわち、音源部１から複数種の超音波を送波させるためには、各種の超音波を送波する音源部１を複数個用いるか、あるいは制御部によって１個の音源部１から複数種の超音波を順次送波させる必要がある。前者の場合、音源部１を１個とする構成に比べて音源部１に掛かるコストが高くなり、また浮遊粒子測定システムの大型化にもつながるという問題がある。一方、後者の場合、音源部１から超音波を送波する度に音源部１を異なる駆動周波数で駆動する必要があるため、音源部１から１種類の超音波を送波させる場合に比べて制御部の構成が複雑化して、コスト高につながるという問題がある。また、いずれの場合においても、複数種の超音波が個別に送波されるため、個々の超音波の送波時に送波音圧のばらつきが生じることで浮遊粒子の種別や濃度の推定確度が低くなる可能性があり、さらに、超音波を複数回送波する必要があるため、超音波の送波に伴う消費電力が大きくなる。   However, in order to be able to estimate the type of suspended particles as described above, it is necessary to transmit a plurality of types of ultrasonic waves having different frequencies from the sound source unit 1, which causes the following problems. That is, in order to transmit a plurality of types of ultrasonic waves from the sound source unit 1, a plurality of sound source units 1 that transmit various types of ultrasonic waves are used, or a plurality of types of sound sources 1 can be transmitted from a single sound source unit 1 by a control unit. It is necessary to transmit ultrasonic waves sequentially. In the former case, there is a problem that the cost required for the sound source unit 1 is higher than that in the configuration in which one sound source unit 1 is provided, and the suspended particle measurement system is increased in size. On the other hand, in the latter case, it is necessary to drive the sound source unit 1 at a different driving frequency each time an ultrasonic wave is transmitted from the sound source unit 1, so that compared with a case where one type of ultrasonic wave is transmitted from the sound source unit 1. There is a problem in that the configuration of the control unit is complicated, leading to high costs. In any case, since multiple types of ultrasonic waves are individually transmitted, the estimation accuracy of the type and concentration of suspended particles is low due to variations in the transmitted sound pressure during the transmission of individual ultrasonic waves. Furthermore, since it is necessary to transmit the ultrasonic wave a plurality of times, the power consumption accompanying the transmission of the ultrasonic wave increases.

本発明は上記事由に鑑みて為されたものであって、監視空間における超音波の減衰量に基づいて浮遊粒子の種別および濃度を測定する構成において、音源部から複数種の音波を送波させる必要のない浮遊粒子測定システムを提供することを目的とする。   The present invention has been made in view of the above reasons, and in a configuration for measuring the type and concentration of suspended particles based on the attenuation amount of ultrasonic waves in a monitoring space, a plurality of types of sound waves are transmitted from a sound source unit. An object of the present invention is to provide a suspended particle measurement system that is not necessary.

請求項１の発明では、複数の周波数成分を含む音波を送波する音源部と、音源部を制御する制御部と、音源部から送波された音波の音圧を検出する受波素子と、受波素子の出力に基づいて音源部と受波素子との間の監視空間に存在する浮遊粒子の種別および濃度を測定する信号処理部とを備え、信号処理部は、受波素子で検出された音波から各周波数成分の強度を抽出する周波数成分抽出手段と、音源部と受波素子との間の監視空間に存在する浮遊粒子の種別および濃度に応じた各周波数成分の周波数と強度の基準値からの減衰量との関係データを記憶した記憶手段と、周波数成分抽出手段で抽出された各周波数成分の強度と記憶手段に記憶されている関係データとを用いて監視空間に浮遊している粒子の種別を推定する粒子種別推定手段と、特定の周波数成分の強度の基準値からの減衰量に基づいて監視空間の浮遊粒子の濃度を推定する濃度推定手段とを有することを特徴とする。   In the invention of claim 1, a sound source unit that transmits a sound wave including a plurality of frequency components, a control unit that controls the sound source unit, a wave receiving element that detects the sound pressure of the sound wave transmitted from the sound source unit, A signal processing unit for measuring the type and concentration of suspended particles existing in the monitoring space between the sound source unit and the receiving element based on the output of the receiving element, and the signal processing unit is detected by the receiving element Frequency component extraction means for extracting the intensity of each frequency component from the collected sound wave, and a reference for the frequency and intensity of each frequency component according to the type and concentration of suspended particles existing in the monitoring space between the sound source unit and the receiving element Floating in the monitoring space using the storage means storing the relationship data with the attenuation amount from the value, the intensity of each frequency component extracted by the frequency component extraction means, and the relationship data stored in the storage means A particle type estimating means for estimating a particle type; And having a concentration estimation means for estimating the concentration of suspended particles in the monitoring space on the basis of the attenuation amount from the reference value of the intensity of a specific frequency component.

この構成によれば、信号処理部が、受波素子で検出された音波から各周波数成分の強度を抽出する周波数成分抽出手段を有し、粒子種別推定手段において、周波数成分抽出手段で抽出された各周波数成分の強度と記憶手段に記憶されている関係データとを用いて監視空間に浮遊している粒子の種別を推定するので、監視空間に浮遊している粒子の種別を推定可能としながらも、音源部から複数種の音波を送波させる必要はない。すなわち、音源部からは複数の周波数成分を含む１種類の音波が送波されればよく、音源部から複数種の音波を送波させる場合に比べて、音源部や制御部に掛かるコストを低く抑えることができ、また、音源部から１回に送波された音波から複数の周波数成分の強度を抽出するようにすれば、個々の音波の送波時に送波音圧のばらつきが生じることで浮遊粒子の種別や濃度の推定確度が低くなったり、音波の送波に伴う消費電力が大きくなったりすることを回避できる。   According to this configuration, the signal processing unit has the frequency component extraction unit that extracts the intensity of each frequency component from the sound wave detected by the receiving element, and is extracted by the frequency component extraction unit in the particle type estimation unit. Since the type of particles floating in the monitoring space is estimated using the intensity of each frequency component and the relational data stored in the storage means, the type of particles floating in the monitoring space can be estimated There is no need to transmit a plurality of types of sound waves from the sound source unit. That is, it is only necessary that one type of sound wave including a plurality of frequency components is transmitted from the sound source unit, and the cost required for the sound source unit and the control unit is lower than when a plurality of types of sound waves are transmitted from the sound source unit. If the intensity of a plurality of frequency components is extracted from the sound wave transmitted at once from the sound source unit, the transmission sound pressure varies when each sound wave is transmitted. It is possible to avoid the estimation accuracy of the type and concentration of particles from being lowered and the power consumption accompanying the transmission of sound waves from being increased.

請求項２の発明は、請求項１の発明において、前記記憶手段が、前記関係データとして各周波数成分の周波数と強度の基準値からの減衰量を基準値で除した減衰率との関係データを記憶していることを特徴とする。   According to a second aspect of the present invention, in the first aspect of the present invention, the storage means includes, as the relational data, relation data between the frequency of each frequency component and an attenuation rate obtained by dividing the attenuation from the reference value of the intensity by the reference value. It is memorized.

この発明によれば、各周波数成分の周波数に応じて当該周波数成分の強度の基準値が変動する場合でも、各周波数成分の周波数と基準値の変動の影響が除去された減衰率との関係データを用いることにより、基準値の変動の影響を受けずに監視空間に浮遊している粒子の種別を推定することができる。   According to the present invention, even when the reference value of the intensity of the frequency component varies according to the frequency of each frequency component, the relationship data between the frequency of each frequency component and the attenuation rate from which the influence of the variation of the reference value is removed By using, it is possible to estimate the type of particles floating in the monitoring space without being affected by the fluctuation of the reference value.

請求項３の発明は、請求項１または請求項２の発明において、前記音源部が、発熱体部への通電に伴う発熱体部の温度変化により空気に熱衝撃を与えることで音波を発生するものであることを特徴とする。   According to a third aspect of the present invention, in the first or second aspect of the present invention, the sound source unit generates a sound wave by applying a thermal shock to the air due to a temperature change of the heat generating unit accompanying energization of the heat generating unit. It is characterized by being.

この構成によれば、音源部は平坦な周波数特性を有しており、発生させる音波の周波数を広範囲にわたって変化させることができる。また、音源部から残響の少ない単パルス状の音波を送波させることも可能となる。   According to this configuration, the sound source unit has a flat frequency characteristic, and the frequency of the sound wave to be generated can be changed over a wide range. It is also possible to transmit a single-pulse sound wave with little reverberation from the sound source unit.

請求項４の発明は、請求項３の発明において、前記音源部が、ベース基板の一表面側に前記発熱体部が形成されるとともに、ベース基板の前記一表面側で前記発熱体部とベース基板との間に設けられて前記発熱体部とベース基板とを熱絶縁する多孔質層からなる熱絶縁層を有してなることを特徴とする。   According to a fourth aspect of the present invention, in the third aspect of the present invention, the sound source section includes the heating element portion formed on the one surface side of the base substrate, and the heating element portion 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.

この構成によれば、熱絶縁層が多孔質層からなるので、熱絶縁層が非多孔質層からなる場合に比べて、熱絶縁層の断熱性が向上して発熱体部への入力電圧に対する音波の音圧の比が高くなり、低消費電力化を図ることができる。   According to this configuration, since the heat insulating layer is made of a porous layer, the heat insulating property of the heat insulating layer is improved compared to the case where the heat insulating layer is made of a non-porous layer. The ratio of the sound pressure of the sound wave becomes high, and the power consumption can be reduced.

請求項５の発明は、請求項１ないし請求項４のいずれかの発明において、前記音源部が送波する前記複数の周波数成分を含む音波が、単パルス状の音波であることを特徴とする。   According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the sound wave including the plurality of frequency components transmitted by the sound source unit is a single-pulse sound wave. .

この構成によれば、周波数成分間の強度差が少なく、且つ比較的広範囲の周波数に亘ってパワーが分布した形のパワースペクトルを持つ単パルス状の音波を音源部から送波するので、周波数成分抽出手段においては、強度差が少なく、且つ比較的広範囲の周波数成分の強度を抽出することできる。   According to this configuration, since the intensity difference between frequency components is small and a single-pulse sound wave having a power spectrum in which power is distributed over a relatively wide range of frequencies is transmitted from the sound source unit, the frequency component In the extracting means, the intensity difference is small and the intensity of a relatively wide range of frequency components can be extracted.

請求項６の発明は、請求項１ないし請求項５のいずれかの発明において、前記周波数成分抽出手段が、各周波数成分の信号をそれぞれ通過させるフィルタ手段を有し、前記受波素子の出力を前記フィルタ手段に通すことで各周波数成分の強度を抽出することを特徴とする。   According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the frequency component extraction means includes filter means for passing signals of the respective frequency components, and outputs the output of the receiving element. The intensity of each frequency component is extracted by passing through the filter means.

この構成によれば、たとえば受波素子の出力の時系列データについて高速フーリエ変換を行い、その結果から各周波数成分の強度を抽出する構成に比べて、信号処理の負荷を低減することができる。   According to this configuration, for example, it is possible to reduce the load of signal processing as compared with a configuration in which fast Fourier transform is performed on time-series data output from the receiving element and the intensity of each frequency component is extracted from the result.

請求項７の発明は、請求項６の発明において、前記フィルタ手段が各周波数成分ごとに個別に設けられており、前記周波数成分抽出手段が、前記受波素子の出力を各フィルタ手段に分配する分配手段を有することを特徴とする。   According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the filter means is individually provided for each frequency component, and the frequency component extracting means distributes the output of the receiving element to the filter means. It has a distribution means.

この構成によれば、音源部から１回に送波された音波について複数の周波数成分の強度を抽出することができるので、個々の音波の送波時に送波音圧のばらつきが生じることで浮遊粒子の種別や濃度の推定確度が低くなったり、音波の送波に伴う消費電力が大きくなったりすることを回避できる。   According to this configuration, the intensity of a plurality of frequency components can be extracted from the sound wave transmitted at one time from the sound source unit. It is possible to avoid the estimation accuracy of the type and concentration of the sound source from being lowered and the power consumption accompanying the transmission of the sound wave from being increased.

請求項８の発明は、請求項１ないし請求項５のいずれかの発明において、前記周波数成分抽出手段が、高速フーリエ変換により各周波数成分の強度を抽出することを特徴とする。   The invention of claim 8 is characterized in that, in the invention of any one of claims 1 to 5, the frequency component extraction means extracts the intensity of each frequency component by fast Fourier transform.

この構成によれば、多数の周波数成分の強度を抽出可能となり、したがって、多数の周波数成分の強度に基づいて浮遊粒子の種別の推定を行うことにより、粒子種別推定の確度の向上を図ることができる。また、音源部から１回に送波された音波について複数の周波数成分の強度を抽出することができるので、個々の音波の送波時に送波音圧のばらつきが生じることで浮遊粒子の種別や濃度の推定確度が低くなったり、音波の送波に伴う消費電力が大きくなったりすることを回避できる。   According to this configuration, it is possible to extract the intensities of a large number of frequency components. Therefore, the accuracy of particle type estimation can be improved by estimating the type of suspended particles based on the intensities of the numerous frequency components. it can. In addition, since the intensity of a plurality of frequency components can be extracted from the sound wave transmitted at one time from the sound source unit, the type and concentration of suspended particles can be caused by variations in the transmitted sound pressure when each sound wave is transmitted. Thus, it is possible to avoid the estimation accuracy of the signal from being lowered and the power consumption accompanying the transmission of the sound wave from increasing.

請求項９の発明は、請求項１ないし請求項６のいずれかの発明において、前記周波数成分抽出手段が、前記音源部から同時に送波され前記監視空間のうち経路長の異なる伝播経路を通して前記受波素子にそれぞれ伝播された複数の音波の各々から、各周波数成分の強度をそれぞれ抽出することを特徴とする。   According to a ninth aspect of the present invention, in the invention according to any one of the first to sixth aspects, the frequency component extracting means transmits the reception through a propagation path having a different path length in the monitoring space that is simultaneously transmitted from the sound source unit. It is characterized in that the intensity of each frequency component is extracted from each of a plurality of sound waves respectively propagated to the wave element.

この構成によれば、音源部から１回に送波された音波について複数の周波数成分の強度を抽出することができるので、個々の音波の送波時に送波音圧のばらつきが生じることで浮遊粒子の種別や濃度の推定確度が低くなったり、音波の送波に伴う消費電力が大きくなったりすることを回避できる。   According to this configuration, the intensity of a plurality of frequency components can be extracted from the sound wave transmitted at one time from the sound source unit. It is possible to avoid the estimation accuracy of the type and concentration of the sound source from being lowered and the power consumption accompanying the transmission of the sound wave from being increased.

本発明は、周波数成分抽出手段で抽出された各周波数成分の強度と記憶手段に記憶されている関係データとを用いて監視空間に浮遊している粒子の種別を推定するので、監視空間に浮遊している粒子の種別を推定可能としながらも、音源部から複数種の音波を送波させる必要はないという効果がある。   Since the present invention estimates the type of particles floating in the monitoring space using the intensity of each frequency component extracted by the frequency component extracting means and the relational data stored in the storage means, While it is possible to estimate the type of particles being performed, there is an effect that it is not necessary to transmit a plurality of types of sound waves from the sound source unit.

以下の各実施形態では、本発明の浮遊粒子測定システムの一例として、火災の発生の有無を判断する目的で監視空間の煙粒子の濃度を測定するものを例示するが、この例に限らず、本発明の浮遊粒子測定システムは、監視空間の種々の浮遊粒子（煙粒子、粉塵、湯気など）の種別および濃度の測定に用いることができる。   In the following embodiments, as an example of the suspended particle measurement system of the present invention, an example of measuring the concentration of smoke particles in the monitoring space for the purpose of determining whether or not a fire has occurred, is not limited to this example. The suspended particle measurement system of the present invention can be used to measure the type and concentration of various suspended particles (smoke particles, dust, steam, etc.) in a monitoring space.

（実施形態１）
本実施形態の浮遊粒子測定システムは、図２に示すように、超音波を送波可能な音源部１と、音源部１を制御する制御部２と、音源部１から送波された超音波の音圧を検出する受波素子３と、受波素子３の出力に基づいて音源部１と受波素子３との間の監視空間に存在する浮遊粒子の種別および濃度を測定する信号処理部４とを備えている。なお、ここでは超音波を送受波する音源部１および受波素子３を採用しているが、音源部１および受波素子３は、超音波に限らず音波を送受波するものであればよい。 (Embodiment 1)
As shown in FIG. 2, the suspended particle measurement system of the present embodiment includes a sound source unit 1 capable of transmitting ultrasonic waves, a control unit 2 that controls the sound source unit 1, and ultrasonic waves transmitted from the sound source unit 1. Receiving element 3 that detects the sound pressure of the signal, and a signal processing unit that measures the type and concentration of suspended particles present in the monitoring space between the sound source unit 1 and the receiving element 3 based on the output of the receiving element 3 4 is provided. Here, the sound source unit 1 and the wave receiving element 3 that transmit and receive ultrasonic waves are employed. However, the sound source unit 1 and the wave receiving element 3 are not limited to ultrasonic waves, but may be anything that transmits and receives sound waves. .

ここにおいて、音源部１と受波素子３とは、図２に示すように、円盤状のプリント基板からなる回路基板５の一表面側において互いに離間して対向配置されており、回路基板５に制御部２および信号処理部４が設けられている。また、回路基板５の上記一表面には、音源部１から送波された超音波の反射を防止する吸音層（図示せず）が設けられているので、音源部１から送波された超音波が回路基板５で反射して受波素子３に入射するのを防止することができて、反射波の干渉を防止することができる。   Here, as shown in FIG. 2, the sound source unit 1 and the wave receiving element 3 are arranged 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. 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. The sound wave can be prevented from being reflected by the circuit board 5 and entering the wave receiving element 3, and interference of the reflected wave can be prevented.

本実施形態では、音源部１として、後述のように空気に熱衝撃を与えることで超音波を発生させる音波発生素子を用いることで、圧電素子に比べて残響時間が短い超音波を送波するようにし、且つ、受波素子３として、共振特性のＱ値が圧電素子に比べて十分に小さく受波信号に含まれる残響成分の発生期間が短い静電容量型のマイクロホンを用いている。   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, as the wave receiving element 3, a capacitance type microphone is used 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.

ここにおいて、音源部１は、図３に示すように、単結晶のｐ形のシリコン基板からなるベース基板１１の一表面（図３における上面）側に多孔質シリコン層からなる熱絶縁層（断熱層）１２が形成され、熱絶縁層１２の表面側に発熱体部として金属薄膜からなる発熱体層１３が形成され、ベース基板１１の上記一表面側に発熱体層１３と電気的に接続された一対のパッド１４，１４が形成されている。なお、ベース基板１１の平面形状は矩形状であって、熱絶縁層１２、発熱体層１３それぞれの平面形状も矩形状に形成してある。また、ベース基板１１の上記一表面側において熱絶縁層１２が形成されていない部分の表面にはシリコン酸化膜からなる絶縁膜（図示せず）が形成されている。   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 thermal insulating layer 12 and the heating element layer 13 are also rectangular. 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.

上述の音源部１では、発熱体層１３の両端のパッド１４，１４間に通電して発熱体層１３に急激な温度変化を生じさせると、発熱体層１３に接触している空気（媒質）に急激な温度変化（熱衝撃）が生じる（つまり、発熱体層１３に接触している空気に熱衝撃が与えられる）。したがって、発熱体層１３に接触している空気は、発熱体層１３の温度上昇時には膨張し発熱体層１３の温度下降時には収縮するから、発熱体層１３への通電を適宜に制御することによって空気中を伝播する超音波を発生させることができる。要するに、音源部１を構成する音波発生素子は、発熱体層１３への通電に伴う発熱体層１３の急激な温度変化を媒質の膨張収縮に変換することにより媒質を伝播する超音波を発生するので、圧電素子のように機械的振動により超音波を発生する場合に比べて、残響の少ない単パルス状の超音波を送波させることができる。   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 propagating 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.

上述の音源部１は、ベース基板１１としてｐ形のシリコン基板を用いており、熱絶縁層１２を多孔度が略６０〜略７０％の多孔質シリコン層からなる多孔質層により構成しているので、ベース基板１１として用いるシリコン基板の一部をフッ化水素水溶液とエタノールとの混合液からなる電解液中で陽極酸化処理することにより熱絶縁層１２となる多孔質シリコン層を形成することができる（ここで、陽極酸化処理により形成された多孔質シリコン層は、結晶粒径がナノメータオーダの微結晶シリコンからなるナノ結晶シリコンを多数含んでいる）。多孔質シリコン層は、多孔度が高くなるにつれて熱伝導率および熱容量が小さくなるので、熱絶縁層１２の熱伝導率および熱容量をベース基板１１の熱伝導率および熱容量に比べて小さくし、熱絶縁層１２の熱伝導率と熱容量との積をベース基板１１の熱伝導率と熱容量との積に比べて十分に小さくすることにより、発熱体層１３の温度変化を空気に効率よく伝達することができ発熱体層１３と空気との間で効率的な熱交換が起こり、且つ、ベース基板１１が熱絶縁層１２からの熱を効率よく受け取って熱絶縁層１２の熱を逃がすことができて発熱体層１３からの熱が熱絶縁層１２に蓄積されるのを防止することができる。なお、熱伝導率が１４８Ｗ／（ｍ・Ｋ）、熱容量が１．６３×１０６Ｊ／（ｍ３・Ｋ）の単結晶のシリコン基板を陽極酸化して形成される多孔度が６０％の多孔質シリコン層は、熱伝導率が１Ｗ／（ｍ・Ｋ）、熱容量が０．７×１０６Ｊ／（ｍ３・Ｋ）であることが知られている。本実施形態では、熱絶縁層１２を多孔度が略７０％の多孔質シリコン層により構成してあり、熱絶縁層１２の熱伝導率が０．１２Ｗ／（ｍ・Ｋ）、熱容量が０．５×１０６Ｊ／（ｍ３・Ｋ）となっている。 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 heat capacity of the layer 12 sufficiently smaller than the product of the thermal conductivity and heat capacity of the base substrate 11, the temperature change of the heating element layer 13 can be efficiently transmitted to the air. In addition, efficient heat exchange occurs between the heating element layer 13 and the air, 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).

発熱体層１３は、高融点金属の一種であるタングステンにより形成してあるが、発熱体層１３の材料はタングステンに限らず、たとえば、タンタル、モリブデン、イリジウム、アルミニウムなどを採用してもよい。また、上述の音源部１では、ベース基板１１の厚さを３００〜７００μｍ、熱絶縁層１２の厚さを１〜１０μｍ、発熱体層１３の厚さを２０〜１００ｎｍ、各パッド１４の厚さを０．５μｍとしてあるが、これらの厚さは一例であって特に限定するものではない。また、ベース基板１１の材料としてＳｉを採用しているが、ベース基板１１の材料はＳｉに限らず、たとえば、Ｇｅ、ＳｉＣ、ＧａＰ、ＧａＡｓ、ＩｎＰなどの陽極酸化処理による多孔質化が可能な他の半導体材料でもよく、いずれの場合にも、ベース基板１１の一部を多孔質化することで形成した多孔質層を熱絶縁層１２とすることができる。   The heating element layer 13 is made 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 adopted. 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 anodic oxidation treatment of 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.

上述のように音源部１は、一対のパッド１４，１４を介した発熱体層１３への通電に伴う発熱体層１３の温度変化に伴って超音波を発生するものであり、発熱体層１３へ与える駆動電圧波形あるいは駆動電流波形からなる駆動入力波形をたとえば周波数がｆ１の正弦波波形とした場合、理想的には、発熱体層１３で生じる温度振動の周波数が駆動入力波形の周波数ｆ１の２倍の周波数ｆ２となり、駆動入力波形ｆ１の略２倍の周波数の超音波を発生させることができる。すなわち、上述の音源部１は、平坦な周波数特性を有しており、発生させる超音波の周波数を広範囲にわたって変化させることができる。また、上述の音源部１では、たとえば正弦波波形の半周期の孤立波を駆動入力波形として一対のパッド１４，１４間へ与えることによって、残響の少ない略１周期の単パルス状の超音波を発生させることができる。このような単パルス状の超音波を用いることにより、反射による干渉が起こりにくくなるので、上記吸音層を不要にすることもできる。また、音源部１は、熱絶縁層１２が多孔質層により構成されているので、熱絶縁層１２が非多孔質層（たとえば、ＳｉＯ２膜など）からなる場合に比べて、熱絶縁層１２の断熱性が向上して超音波発生効率が高くなり、低消費電力化を図れる。 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 composed of the drive voltage waveform or the drive current waveform applied to is a sine wave waveform having a frequency of f1, for example, the frequency of the temperature oscillation generated in the heating element layer 13 is ideally the frequency of the drive input waveform f1. 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. Further, in the sound source unit 1 described above, for example, a half-cycle solitary wave of 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 of approximately 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.

音源部１を制御する制御部２は、図示していないが、音源部１に駆動入力波形を与えて音源部１を駆動する駆動回路と、当該駆動回路を制御するマイクロコンピュータからなる制御回路とで構成されている。   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

また、上述の受波素子３を構成する静電容量型のマイクロホンは、図４に示すように、シリコン基板に厚み方向に貫通する窓孔３１ａを設けることで形成された矩形枠状のフレーム３１と、フレーム３１の一表面側においてフレーム３１の対向する２つの辺に跨る形で配置されるカンチレバー型の受圧部３２とを備えている。ここにおいて、フレーム３１の一表面側には熱酸化膜３５と熱酸化膜３５を覆うシリコン酸化膜３６とシリコン酸化膜３６を覆うシリコン窒化膜３７とが形成されており、受圧部３２の一端部がシリコン窒化膜３７を介してフレーム３１に支持され、他端部が上記シリコン基板の厚み方向においてシリコン窒化膜３７に対向している。また、シリコン窒化膜３７における受圧部３２の他端部との対向面に金属薄膜（たとえば、クロム膜など）からなる固定電極３３ａが形成され、受圧部３２の他端部におけるシリコン窒化膜３７との対向面とは反対側に金属薄膜（たとえば、クロム膜など）からなる可動電極３３ｂが形成されている。なお、フレーム３１の他表面にはシリコン窒化膜３８が形成されている。また、受圧部３２は、上記各シリコン窒化膜３７，３８とは別工程で形成されるシリコン窒化膜により構成されている。   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 33a made of a metal thin film (for example, a chromium film) is formed on the 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.

図４に示した構成の静電容量型のマイクロホンからなる受波素子３では、固定電極３３ａと可動電極３３ｂとを電極とするコンデンサが形成されるから、受圧部３２が疎密波の圧力を受けることにより固定電極３３ａと可動電極３３ｂとの間の距離が変化し、固定電極３３ａと可動電極３３ｂとの間の静電容量が変化する。したがって、固定電極３３ａおよび可動電極３３ｂに設けたパッド（図示せず）間に直流バイアス電圧を印加しておけば、パッドの間には超音波の音圧に応じて微小な電圧変化が生じるから、超音波の音圧を電気信号に変換することができる。   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.

ここにおいて、本実施形態の浮遊粒子測定システムは、「発明が解決しようとする課題」の欄で図１５を用いて説明した浮遊粒子測定システムと基本構成が共通であって、図１に示すように、信号処理部４には、音源部１と受波素子３との間の監視空間に存在する浮遊粒子の種別を推定する粒子種別推定手段４１と、監視空間の浮遊粒子の濃度を推定する濃度推定手段４２と、粒子種別推定手段４１および濃度推定手段４２で使用するデータを記憶した記憶手段４４とを具備している。   Here, the suspended particle measuring system of the present embodiment has the same basic configuration as the suspended particle measuring system described with reference to FIG. 15 in the column “Problems to be Solved by the Invention”, as shown in FIG. In addition, the signal processing unit 4 estimates particle type estimation means 41 for estimating the type of suspended particles existing in the monitoring space between the sound source unit 1 and the receiving element 3, and estimates the concentration of suspended particles in the monitoring space. Concentration estimation means 42, particle type estimation means 41, and storage means 44 that stores data used by concentration estimation means 42 are provided.

すなわち、本実施形態では、音源部１が複数の周波数成分を含む超音波を送波する構成を採用するとともに、受波素子３で検出された超音波から各周波数成分の強度を検出する周波数成分抽出手段４０を信号処理部４に付加してある。音源部１から送波される超音波の具体的例および周波数成分抽出手段４０の構成例については後述する。さらに、粒子種別推定手段４１は、周波数成分抽出手段４０で抽出された各周波数成分の強度と記憶手段４４に記憶されている関係データとを用いて監視空間に浮遊している粒子の種別を推定するものとし、且つ、信号処理部４で測定される浮遊粒子の濃度を火災の有無の判断に用いるため、濃度推定手段４２は、粒子種別推定手段４１にて推定された粒子が煙粒子のときに、特定の周波数成分（たとえば、８２ｋＨｚ）の強度の基準値からの減衰量に基づいて監視空間の浮遊粒子の濃度を推定するものとする。   That is, in this embodiment, the sound source unit 1 employs a configuration in which an ultrasonic wave including a plurality of frequency components is transmitted, and a frequency component that detects the intensity of each frequency component from the ultrasonic wave detected by the wave receiving element 3. An extraction means 40 is added to the signal processing unit 4. A specific example of the ultrasonic wave transmitted from the sound source unit 1 and a configuration example of the frequency component extraction unit 40 will be described later. Further, the particle type estimation unit 41 estimates the type of particles floating in the monitoring space using the intensity of each frequency component extracted by the frequency component extraction unit 40 and the relational data stored in the storage unit 44. In addition, since the concentration of suspended particles measured by the signal processing unit 4 is used to determine whether or not there is a fire, the concentration estimation unit 42 is configured so that the particles estimated by the particle type estimation unit 41 are smoke particles. In addition, it is assumed that the concentration of suspended particles in the monitoring space is estimated based on the attenuation amount from the reference value of the intensity of a specific frequency component (for example, 82 kHz).

また、記憶手段４４には、少なくとも受波素子３の出力から周波数成分抽出手段４０によって抽出される各周波数成分の強度の基準値（監視空間に浮遊粒子が存在しない状態で受波素子３にて受波される基準音圧に対する受波素子３の出力から抽出される各周波数成分の強度）、上記監視空間に存在する浮遊粒子の種別および浮遊粒子濃度に応じた各周波数成分の周波数と同周波数成分の強度の相対的単位減衰率との関係データ（図１７より抽出されるデータ）、煙粒子に関して特定周波数（たとえば、８２ｋＨｚ）における単位減衰率（図１６より抽出されるデータ）を記憶している。   Further, the storage means 44 stores at least the reference value of the intensity of each frequency component extracted from the output of the wave receiving element 3 by the frequency component extracting means 40 (in the wave receiving element 3 in a state where no suspended particles exist in the monitoring space). The intensity of each frequency component extracted from the output of the receiving element 3 with respect to the received reference sound pressure), the type of suspended particles present in the monitoring space, and the frequency of each frequency component corresponding to the suspended particle concentration Data relating to the relative unit attenuation rate of the component intensity (data extracted from FIG. 17) and unit attenuation rate (data extracted from FIG. 16) at a specific frequency (for example, 82 kHz) with respect to smoke particles are stored. Yes.

なお、信号処理部４は、マイクロコンピュータにより構成されており、上記各手段４０〜４４は、上記マイクロコンピュータに適宜のプログラムを搭載することにより実現されている。また、信号処理部４には、受波素子３の出力信号をアナログ−ディジタル変換するＡ／Ｄ変換器なども設けられている。   The signal processing unit 4 is configured by a microcomputer, and each of the means 40 to 44 is realized by mounting an appropriate program on the microcomputer. The signal processing unit 4 is also provided with an A / D converter for analog-digital conversion of the output signal of the wave receiving element 3.

以下に、本実施形態の浮遊粒子測定システムの動作例を図５のフローチャートを参照して説明する。まず、音源部１から複数の周波数成分を含んだ超音波を送波させ、当該超音波に対する受波素子３の出力を信号処理部４で計測する（ステップＳ１１）。周波数成分抽出手段４０は受波素子３の出力から各周波数成分の強度を抽出し、粒子種別推定手段４１は、周波数成分抽出手段４０で抽出された各周波数成分の強度と記憶手段４４に記憶されている基準値とから、各周波数成分について強度の減衰率を求め（ステップＳ１２）、中心周波数が８２ｋＨｚの周波数成分の減衰率に対する中心周波数が２０ｋＨｚの周波数成分の減衰率の比を算出する（ステップＳ１３）。記憶手段４４には、各周波数成分の周波数と同周波数成分の強度の相対的単位減衰率との上記関係データとして、出力周波数が８２ｋＨｚでの相対的単位減衰率に対する２０ｋＨｚでの相対的単位減衰率の比（図１７の場合、白煙が０、黒煙が０．２、湯気が０．５となる）が記憶されており、粒子種別推定手段４１は、算出した減衰率の比を記憶手段４４に記憶されている関係データと比較し、関係データの中で減衰率の比が最も近い種別の粒子を監視空間に浮遊している粒子と推定する（ステップＳ１４）。ここで、推定された粒子が煙粒子であれば濃度推定手段４２での処理に移行する（ステップＳ１５）。ここにおいて、白煙の場合には図６に示すように減光式煙濃度計で計測される浮遊粒子の濃度と音圧の減衰率との関係は直線で示すことのできるデータであり、他の粒子においても同様であるから、濃度推定手段４２は、推定された粒子種別について特定の周波数成分（たとえば、８２ｋＨｚ）の減衰率の記憶手段４４に記憶されている単位減衰率に対する比を算出し、その比の値がｙの場合に監視空間の煙濃度が減光式煙濃度計での評価における浮遊粒子の濃度ｙ〔％／ｍ〕に相当すると推定する（ステップＳ１６）。ステップＳ１６で推定された浮遊粒子の濃度と所定の閾値（たとえば、減光式煙濃度計での評価で１０％／ｍとなる浮遊粒子の濃度）とを比較し、推定された浮遊粒子の濃度が上記閾値未満の場合には「火災無し」と判断する一方で、上記閾値以上の場合には「火災有り」と判断する。   Hereinafter, an operation example of the suspended particle measurement system of the present embodiment will be described with reference to the flowchart of FIG. First, an ultrasonic wave including a plurality of frequency components is transmitted from the sound source unit 1, and the output of the wave receiving element 3 for the ultrasonic wave is measured by the signal processing unit 4 (step S11). The frequency component extraction means 40 extracts the intensity of each frequency component from the output of the receiving element 3, and the particle type estimation means 41 is stored in the storage means 44 with the intensity of each frequency component extracted by the frequency component extraction means 40. The attenuation rate of the intensity for each frequency component is obtained from the reference value (step S12), and the ratio of the attenuation rate of the frequency component having the center frequency of 20 kHz to the attenuation rate of the frequency component having the center frequency of 82 kHz is calculated (step S12). S13). The storage means 44 stores the relative unit attenuation rate at 20 kHz with respect to the relative unit attenuation rate at the output frequency of 82 kHz as the relational data of the frequency of each frequency component and the relative unit attenuation rate of the intensity of the frequency component. (In the case of FIG. 17, white smoke is 0, black smoke is 0.2, and steam is 0.5), and the particle type estimation means 41 stores the calculated ratio of the attenuation rate as storage means. Compared with the relational data stored in 44, 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 by the concentration estimating means 42 (step S15). In this case, in the case of white smoke, as shown in FIG. 6, the relationship between the concentration of suspended particles measured by a dimming smoke densitometer and the attenuation rate of sound pressure is data that can be shown by a straight line. Therefore, the concentration estimation means 42 calculates the ratio of the attenuation rate of a specific frequency component (for example, 82 kHz) to the unit attenuation rate stored in the storage means 44 for the estimated particle type. When the value of the ratio is y, it is estimated that the smoke density in the monitoring space corresponds to the suspended particle density y [% / m] in the evaluation with the dimming smoke densitometer (step S16). The concentration of airborne particles estimated in step S16 is compared with a predetermined threshold (for example, the concentration of airborne particles that is 10% / m in the evaluation with a dimming smoke densitometer), and the airborne particle concentration estimated. Is less than the threshold value, it is determined that there is no fire. On the other hand, if it is greater than the threshold value, it is determined that there is a fire.

上述の例では、粒子種別推定手段４１は中心周波数が８２ｋＨｚの周波数成分の減衰率と中心周波数が２０ｋＨｚの周波数成分の減衰率とを用いているが、これらの周波数成分の組み合わせに限定するものではなく、異なる組み合わせの周波数成分を用いてもよい。さらに、より多くの周波数成分の減衰率を用いてもよく、その場合は粒子種別の推定の確度を向上させることができる。また、本実施形態では、濃度推定手段４２が特定の周波数成分として１周波数成分を対象としているが、特定の周波数成分として複数の周波数成分を対象とし、各周波数成分ごとに推定した浮遊粒子の濃度の平均値を求めるようにしてもよく、この場合、浮遊粒子の濃度の推定の確度が向上する。   In the above example, the particle type estimation means 41 uses the attenuation rate of the frequency component with the center frequency of 82 kHz and the attenuation rate of the frequency component with the center frequency of 20 kHz, but the combination is not limited to these frequency components. Alternatively, different combinations of frequency components may be used. Furthermore, the attenuation rate of more frequency components may be used, and in that case, the accuracy of estimation of the particle type can be improved. In the present embodiment, the concentration estimation unit 42 targets one frequency component as a specific frequency component. However, the concentration of suspended particles estimated for each frequency component with a plurality of frequency components as a specific frequency component is targeted. In this case, the accuracy of estimation of the concentration of suspended particles is improved.

ところで、本実施形態では、音源部１から複数の周波数成分を含んだ超音波を送波させるために、制御部２は音源部１に対して正弦波波形の半周期の孤立波を駆動入力波形として与えている。これにより、音源部１からは図７（ａ）に示すような略１周期の単パルス（インパルス）状の超音波が送波されることとなる。この種の単パルス状の超音波のパワースペクトルは、図７（ｂ）に示すようにパルス幅に応じた周波数ｆ０を中心周波数として広範囲の周波数に亘って強度（エネルギ）が分布した形となる。要するに、本実施形態のように単パルス状の超音波を音源部１から送波させることによって、音源部１からは複数の周波数成分を含んだ超音波が送波されることとなる。したがって、周波数成分抽出手段４０は、たとえば図７（ｂ）にＢ１〜Ｂ３で示す各周波数帯域について周波数成分の強度を抽出することができる。   By the way, in this embodiment, in order to transmit an ultrasonic wave including a plurality of frequency components from the sound source unit 1, the control unit 2 drives the sound source unit 1 with a half-cycle isolated wave of a sine wave waveform as a drive input waveform. As given. As a result, a single-pulse (impulse) ultrasonic wave having approximately one cycle as shown in FIG. 7A is transmitted from the sound source unit 1. The power spectrum of this kind of single-pulse ultrasonic wave has a shape in which intensity (energy) is distributed over a wide range of frequencies with a frequency f0 corresponding to the pulse width as a center frequency as shown in FIG. 7B. . In short, by transmitting single-pulse ultrasonic waves from the sound source unit 1 as in the present embodiment, the sound source unit 1 transmits ultrasonic waves including a plurality of frequency components. Therefore, the frequency component extraction means 40 can extract the intensity of the frequency component for each frequency band indicated by B1 to B3 in FIG. 7B, for example.

これに対して、ある程度の波数（たとえば３周期程度）を持つバースト波のパワースペクトルは、周期に応じた周波数ｆ０にピークを持ち、その他の周波数帯域においては強度が低くなる。そのため、本実施形態のように単パルス状の超音波を用いる場合に比べて、周波数成分抽出手段４０において抽出可能な周波数成分は、強度差が大きく、且つ周波数範囲が狭くなる。なお、音源部１からの超音波が図８（ａ）のようにある周波数ｆ０の連続波になると、超音波のパワースペクトルは、図８（ｂ）に示すように前記周波数ｆ０に鋭いピークを持ち、その他の周波数帯域においては強度が大幅に低下する形になるので、周波数成分抽出手段４０において各周波数成分の強度を抽出できなくなる。   On the other hand, the power spectrum of a burst wave having a certain number of waves (for example, about 3 cycles) has a peak at a frequency f0 corresponding to the cycle, and the intensity is low in other frequency bands. Therefore, compared with the case where single pulse ultrasonic waves are used as in the present embodiment, the frequency components that can be extracted by the frequency component extraction means 40 have a large intensity difference and a narrow frequency range. When the ultrasonic wave from the sound source unit 1 becomes a continuous wave of a certain frequency f0 as shown in FIG. 8A, the ultrasonic power spectrum has a sharp peak at the frequency f0 as shown in FIG. 8B. In other frequency bands, the intensity is greatly reduced, and the frequency component extracting means 40 cannot extract the intensity of each frequency component.

一方、受波素子３においては、共振特性のＱ値が圧電素子に比べて十分に小さい静電容量型のマイクロホンを用いているため、音源部１からの超音波に含まれる複数の周波数成分について感度に大きなばらつきはない。ただし、図９（ｂ）に示すように受波素子３の共振周波数ｆｃよりも高い周波数帯域では感度が低下するので、図９（ａ）に示すように周波数成分抽出手段４０で周波数成分の強度が抽出される周波数帯域Ｂ１〜Ｂ３よりも高い周波数を共振周波数とする受波素子３を用いることが望ましい。なお、パワースペクトルを示す図７（ｂ）、図８（ｂ）、図９並びに以下の説明で用いる図１０、図１１では、横軸を周波数、縦軸を強度（パワー）とする。   On the other hand, since the receiving element 3 uses a capacitance type microphone whose resonance characteristic Q value is sufficiently smaller than that of the piezoelectric element, a plurality of frequency components included in the ultrasonic wave from the sound source unit 1 are used. There is no great variation in sensitivity. However, since sensitivity decreases in a frequency band higher than the resonance frequency fc of the receiving element 3 as shown in FIG. 9B, the intensity of the frequency component is obtained by the frequency component extracting means 40 as shown in FIG. 9A. It is desirable to use the wave receiving element 3 having a resonance frequency that is higher than the frequency band B1 to B3 from which the noise is extracted. In FIGS. 7B, 8B, and 9 showing the power spectrum, and FIGS. 10 and 11 used in the following description, the horizontal axis represents frequency and the vertical axis represents intensity (power).

次に、周波数成分抽出手段４０の構成について説明する。   Next, the configuration of the frequency component extraction unit 40 will be described.

一例として、音源部１からは図１０（ａ）に示すように周期が３．３３μｓ（つまり、３００ｋＨｚ相当）の単パルス状の超音波が送波され、これにより、受波素子３で受波される超音波のパワースペクトルが図１０（ｂ）に示すように３００ｋＨｚにピークを持つ形になったものと仮定する。この場合において、図１１における周波数帯域Ｂ１〜Ｂ３の各周波数成分の強度を抽出するため、図１２に示すように、１５０〜２５０ｋＨｚ（周波数帯域Ｂ１）の信号を通過させる第１のフィルタ手段（たとえば、バンドパスフィルタ）４５ａと、２５０〜３５０ｋＨｚ（周波数帯域Ｂ２）の信号を通過させる第２のフィルタ手段４５ｂと、３５０〜４５０ｋＨｚ（周波数帯域Ｂ３）の信号を通過させる第３のフィルタ手段４５ｃとを周波数成分抽出手段４０に設け、第１〜第３の各フィルタ手段４５ａ〜４５ｃの出力を各周波数成分の強度として取り出すようにする。   As an example, the sound source unit 1 transmits a single-pulse ultrasonic wave having a period of 3.33 μs (that is, equivalent to 300 kHz) as shown in FIG. It is assumed that the power spectrum of the ultrasonic wave to be formed has a peak at 300 kHz as shown in FIG. In this case, in order to extract the intensity of each frequency component in the frequency bands B1 to B3 in FIG. 11, as shown in FIG. 12, a first filter means (for example, a filter of 150 to 250 kHz (frequency band B1)) is passed. , A band pass filter) 45a, a second filter means 45b for passing a signal of 250 to 350 kHz (frequency band B2), and a third filter means 45c for passing a signal of 350 to 450 kHz (frequency band B3). Provided in the frequency component extraction means 40, the outputs of the first to third filter means 45a to 45c are extracted as the intensity of each frequency component.

ここで、周波数成分抽出手段４０は、受波素子３の出力を増幅するアンプＡｍｐと、アンプＡｍｐで増幅された受波素子３の出力を各フィルタ手段４５ａ〜４５ｃに略均等に分配する分配手段４６とを有しており、受波素子３の出力が各フィルタ手段４５ａ〜４５ｃを通して後段の粒子種別推定手段４１に出力されるようにしてある。これにより、周波数成分抽出手段４０においては、音源部１から１回に送波された超音波から複数の周波数成分の強度を抽出することができる。ここで、フィルタ手段４５ａ〜４５ｃはプログラムによって実現してもよいが、ハードウェアで実現すれば信号処理の負荷を低減することができ、信号処理の高速化を図ることができる。   Here, the frequency component extraction means 40 is an amplifier Amp that amplifies the output of the wave receiving element 3, and a distribution means that distributes the output of the wave receiving element 3 amplified by the amplifier Amp substantially equally to each of the filter means 45a to 45c. 46, and the output of the wave receiving element 3 is output to the subsequent particle type estimation means 41 through the filter means 45a to 45c. Thereby, in the frequency component extraction means 40, the intensity | strength of a several frequency component can be extracted from the ultrasonic wave transmitted at once from the sound source part 1. FIG. Here, the filter means 45a to 45c may be realized by a program, but if realized by hardware, the load of signal processing can be reduced, and the speed of signal processing can be increased.

なお、本実施形態では、各周波数成分の周波数と強度の相対的単位減衰率との関係データを記憶手段４４に記憶した例を示したが、そもそも監視空間に存在する浮遊粒子の種別に応じて周波数成分の周波数ごとに変化するのは周波数成分の強度の基準値からの減衰量（Ｉ０−Ｉｘ）であるから、記憶手段４４に記憶する上記関係データは、各周波数成分の周波数と同周波数成分の強度の基準値からの減衰量との関係を示すデータであればよく、上述の相対的単位減衰率に代えて、たとえば、周波数成分の強度の基準値からの減衰量や、周波数成分の強度の基準値からの減衰量を基準値（Ｉ０）で除しただけの減衰率、あるいは単位減衰率を採用した関係データを記憶手段４４に記憶するようにしてもよい。 In the present embodiment, the example in which the relationship data between the frequency of each frequency component and the relative unit attenuation rate of the intensity is stored in the storage unit 44 is shown. However, depending on the type of suspended particles existing in the monitoring space in the first place. Since the attenuation amount (I 0 -I x ) from the reference value of the intensity of the frequency component changes for each frequency of the frequency component, the relational data stored in the storage unit 44 is the same as the frequency of each frequency component. Any data showing the relationship with the attenuation amount from the reference value of the intensity of the frequency component may be used. Instead of the above relative unit attenuation rate, for example, the attenuation amount from the reference value of the intensity of the frequency component or the frequency component It is also possible to store in the storage means 44 the attenuation rate obtained by dividing the attenuation amount from the reference value of the intensity by the reference value (I 0 ) or the relation data adopting the unit attenuation rate.

以上説明した本実施形態の浮遊粒子測定システムによれば、周波数成分抽出手段４０が、受波素子３で検出された超音波から各周波数成分の強度を抽出し、粒子種別推定手段４１においては、周波数成分抽出手段４０で抽出された各周波数成分の強度と記憶手段４４に記憶されている関係データとを用いて監視空間に存在する浮遊粒子の種別を推定するので、浮遊粒子の種別を推定可能としながらも、音源部１から複数種の超音波を送波させる必要はない。   According to the suspended particle measurement system of the present embodiment described above, the frequency component extraction unit 40 extracts the intensity of each frequency component from the ultrasonic wave detected by the wave receiving element 3, and the particle type estimation unit 41 Since the type of suspended particles existing in the monitoring space is estimated using the intensity of each frequency component extracted by the frequency component extracting unit 40 and the relational data stored in the storage unit 44, the type of suspended particles can be estimated. However, it is not necessary to transmit a plurality of types of ultrasonic waves from the sound source unit 1.

すなわち、煙濃度を測定することにより火災の発生の有無の判断を行う場合に、粒子種別推定手段４１において上記監視空間に浮遊している粒子の種別を推定することで煙粒子と湯気とを識別可能となるから、湯気に起因した非火災報を低減することが可能となり、台所や浴室での使用にも適する。また、浮遊粒子測定システムを設置している室内の掃除や天井裏の電気工事などの際に浮遊する粉塵と煙粒子との識別も可能になるから、粉塵などに起因した非火災報を低減することも可能となる。なお、粒子種別推定手段４１において白煙の煙粒子と黒煙の煙粒子とを識別可能となるから、火災の性状の識別に役立てることも可能となる。   That is, when determining whether or not a fire has occurred by measuring the smoke concentration, the particle type estimation means 41 discriminates between smoke particles and steam by estimating the type of particles floating in the monitoring space. This makes it possible to reduce non-fire reports due to steam and is suitable for use in kitchens and bathrooms. In addition, it is possible to distinguish between dust and smoke particles floating when cleaning the room where the suspended particle measurement system is installed or when electrical work is performed on the back of the ceiling, thus reducing non-fire reports caused by dust. It is also possible. Since the particle type estimation means 41 can distinguish between white smoke particles and black smoke particles, it can also be used for identifying fire properties.

しかも、音源部１からは複数の周波数成分を含む１種類の超音波（ここでは、単パルス状の超音波）が送波されればよく、音源部１から複数種の超音波を送波させる場合に比べて、音源部１や制御部２に掛かるコストを低く抑えることができる。また、周波数成分抽出手段４０は音源部１から１回に送波された超音波から複数の周波数成分の強度を抽出するので、個々の超音波の送波時に送波音圧のばらつきが生じることで浮遊粒子の種別や濃度の推定確度が低くなったり、超音波の送波に伴う消費電力が大きくなったりすることを回避できるという利点もある。   In addition, it is only necessary to transmit one type of ultrasonic wave (in this case, a single pulsed ultrasonic wave) including a plurality of frequency components from the sound source unit 1, and a plurality of types of ultrasonic waves are transmitted from the sound source unit 1. Compared to the case, the cost of the sound source unit 1 and the control unit 2 can be kept low. Further, since the frequency component extraction means 40 extracts the intensity of a plurality of frequency components from the ultrasonic wave transmitted from the sound source unit 1 at a time, the transmission sound pressure varies when each ultrasonic wave is transmitted. There is also an advantage that it is possible to avoid the estimation accuracy of the type and concentration of suspended particles from being lowered and the power consumption accompanying the transmission of ultrasonic waves from being increased.

ところで、周波数成分抽出手段４０は、上述したようにフィルタ手段４５ａ〜４５ｃによって各周波数成分の強度を抽出するものに限らず、たとえば受波素子３の出力の時系列データについて高速フーリエ変換（ＦＦＴ）を行い、その結果から各周波数成分の強度を抽出するものであってもよい。この場合、多数の周波数成分の強度を抽出することが容易となり、多数の周波数成分の強度に基づいて浮遊粒子の種別の推定を行うことにより、粒子種別の推定の確度の向上を図ることができる。また、分配手段４６を用いることなく、音源部１から１回に送波された超音波について複数の周波数成分の強度を抽出することができるという利点もある。ただし、この場合、フィルタ手段４５ａ〜４５ｃによって各周波数成分の強度を抽出する構成に比べて、信号処理の負荷が大きくなる。   Incidentally, the frequency component extracting means 40 is not limited to extracting the intensity of each frequency component by the filter means 45a to 45c as described above. For example, fast Fourier transform (FFT) is performed on the time series data of the output of the receiving element 3. And the intensity of each frequency component may be extracted from the result. In this case, it becomes easy to extract the intensities of a large number of frequency components, and by estimating the type of suspended particles based on the intensities of the large number of frequency components, it is possible to improve the accuracy of estimation of the particle type. . Further, there is also an advantage that the intensity of a plurality of frequency components can be extracted from the ultrasonic wave transmitted at one time from the sound source unit 1 without using the distributing means 46. However, in this case, the load of signal processing becomes larger than the configuration in which the intensity of each frequency component is extracted by the filter means 45a to 45c.

また、音源部１からは複数の周波数成分を含んだ超音波が送波されればよく、上述したような単パルス状の超音波に限らず、波数の少ないバースト波状の超音波、あるいは周波数の異なる複数の超音波を重畳させて成る超音波を音源部１から送波させるようにしてもよい。   The sound source unit 1 only needs to transmit an ultrasonic wave including a plurality of frequency components, and is not limited to the single-pulse ultrasonic wave as described above. An ultrasonic wave formed by superposing a plurality of different ultrasonic waves may be transmitted from the sound source unit 1.

（実施形態２）
本実施形態の浮遊粒子測定システムは、基本構成が実施形態１と略同じであり、周波数成分抽出手段４０の構成が実施形態１の浮遊粒子測定システムと相違する。なお、実施形態１と同様の構成要素には同一の符号を付して説明を適宜省略する。 (Embodiment 2)
The suspended particle measurement system of the present embodiment has substantially the same basic configuration as that of the first embodiment, and the configuration of the frequency component extraction means 40 is different from that of the suspended particle measurement system of the first embodiment. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably.

本実施形態では、音源部１と受波素子３との間に経路長の異なる複数の伝播経路を形成し、音源部１から送波された超音波を複数の伝播経路に分岐し、各伝播経路を通して受波素子３で受波されるように構成する。ここで、周波数成分抽出手段４０は、音源部１から同時に送波され経路長の異なる伝播経路を通して受波素子３にそれぞれ伝播された複数の超音波の各々から、各周波数成分の強度をそれぞれ抽出する。   In the present embodiment, a plurality of propagation paths having different path lengths are formed between the sound source unit 1 and the wave receiving element 3, and the ultrasonic waves transmitted from the sound source unit 1 are branched into a plurality of propagation paths. The signal is received by the wave receiving element 3 through the path. Here, the frequency component extracting means 40 extracts the intensity of each frequency component from each of a plurality of ultrasonic waves transmitted simultaneously from the sound source unit 1 and propagated to the receiving element 3 through propagation paths having different path lengths. To do.

本実施形態の一例として、図１３（ａ）に示すように内部空間に形成された超音波の伝播経路の経路長が異なる複数種類の筒体６ａ，６ｂを、音源部１と受波素子３との間に並列に介在させる構成が考えられる。すなわち、図１３（ａ）のように音源部１と受波素子３との間に、直管状であって管長さＬ１の筒体６ａと、湾曲した形であって管長さＬ２（＞Ｌ１）の筒体６ｂとを、音源部１および受波素子３の対向する方向に直交する面内で並ぶように配設し、音源部１からの超音波が両筒体６ａ，６ｂに分岐されて各筒体６ａ，６ｂの内部空間を通るようにする。しかして、音源部１から送波される超音波は、両筒体６ａ，６ｂの入り口（図１３（ａ）では左端面）で第１および第２の超音波Ｓｗ１，Ｓｗ２に分岐され、第１の超音波Ｓｗ１が管長さＬ１の筒体６ａの内部空間（経路長Ｌ１の伝播経路）を通って受波素子３に伝播されるとともに、第２の超音波Ｓｗ２が管長さＬ２の筒体６ｂの内部空間（経路長Ｌ２の伝播経路）を通って受波素子３に伝播されることになる。その後、周波数成分抽出手段４０で超音波Ｓｗ１，Ｓｗ２の各々から、各周波数成分の強度がそれぞれ抽出される。 As an example of the present embodiment, as shown in FIG. 13A, a plurality of types of cylinders 6 a and 6 b having different propagation lengths of ultrasonic waves formed in an internal space are used as a sound source unit 1 and a wave receiving element 3. It is conceivable to intervene in parallel with each other. That is, between the sound source unit 1 and wave receiving element 3 as shown in FIG. 13 (a), the a cylindrical body 6a of a straight tubular pipe length L 1, a curved shape tube length L 2 (> L 1 ) cylinders 6b are arranged in a plane orthogonal to the direction in which the sound source unit 1 and the receiving element 3 face each other, and the ultrasonic waves from the sound source unit 1 are applied to both the cylinders 6a and 6b. It branches so that it may pass through the internal space of each cylinder 6a, 6b. Accordingly, the ultrasonic wave transmitted from the sound source unit 1 is branched into the first and second ultrasonic waves Sw1 and Sw2 at the entrances (the left end face in FIG. 13A) of both the cylinders 6a and 6b. while being propagated in the wave receiving element 3 1 ultrasonic Sw1 is through the interior space of the cylindrical body 6a of tube length L 1 (propagation path of the path length L 1), second ultrasonic Sw2 is tube length L 2 It will be propagated to the wave receiving element 3 through the interior space of the cylindrical body 6b (the propagation path of the path length L 2). Thereafter, the frequency component extraction means 40 extracts the intensity of each frequency component from each of the ultrasonic waves Sw1 and Sw2.

ここにおいて、各超音波Ｓｗ１，Ｓｗ２が受波素子３に到達するタイミングには、図１３（ｂ）に示すように伝播経路の経路長Ｌ１，Ｌ２の差に応じた時間差Ｔｄが生じる。この時間差Ｔｄは、経路長Ｌ１，Ｌ２の差を音速で除することにより求められる。受波素子３において各超音波Ｓｗ１，Ｓｗ２を区別するためには、受波素子３で各超音波Ｓｗ１，Ｓｗ２をそれぞれ受波する期間を前記時間差Ｔｄ内に収める必要がある。 Here, at the timing when each of the ultrasonic waves Sw1 and Sw2 arrives at the wave receiving element 3, a time difference Td corresponding to the difference between the path lengths L 1 and L 2 of the propagation path is generated as shown in FIG. 13B. This time difference Td is obtained by dividing the difference between the path lengths L 1 and L 2 by the speed of sound. In order to distinguish the ultrasonic waves Sw1 and Sw2 in the wave receiving element 3, it is necessary to keep the period during which the ultrasonic waves Sw1 and Sw2 are received by the wave receiving element 3 within the time difference Td.

つまり、たとえば音速が３４０ｍ／ｓで、音源部１から送波される超音波の周波数が１００ｋＨｚである場合、超音波は周期１０μｓ、波長３．４ｍｍとなるので、経路長Ｌ１，Ｌ２の差を６８ｍｍにすると、超音波の波数が２０波を超えれば超音波同士の重なりが生じ、受波素子３で各超音波Ｓｗ１，Ｓｗ２を区別できなくなる。そこで、経路長Ｌ１，Ｌ２の差と音源部１から１回に送波する超音波の波数とを調整することにより、超音波同士の重なりが生じないようにする。浮遊粒子測定システムを小型化するために経路長Ｌ１，Ｌ２の差を小さくする場合などには、実施形態１で説明したように、発熱体層１３への通電に伴う発熱体層１３の温度変化により空気に熱衝撃を与えることで超音波を発生する構成であって、残響の少ない単パルス状の超音波を送波可能な音源部１を採用することが有用である。 That is, for example, the sound velocity at 340m / s, when the frequency of the ultrasonic wave transmitted from the sound source unit 1 is 100kHz, ultrasound period 10 [mu] s, since the wavelength 3.4 mm, the path length L 1, L 2 When the difference is set to 68 mm, if the wave number of the ultrasonic wave exceeds 20, the ultrasonic waves overlap each other, and the wave receiving element 3 cannot distinguish the ultrasonic waves Sw1 and Sw2. Therefore, by adjusting the difference between the path lengths L 1 and L 2 and the wave number of the ultrasonic wave transmitted from the sound source unit 1 at one time, the ultrasonic waves do not overlap each other. When reducing the difference between the path lengths L 1 and L 2 in order to reduce the size of the suspended particle measurement system, as described in the first embodiment, It is useful to employ a sound source unit 1 that is configured to generate an ultrasonic wave by applying a thermal shock to air due to a temperature change and that can transmit a single-pulse ultrasonic wave with little reverberation.

さらに、図１３（ａ）の構成によれば、音源部１と受波素子３との間に筒体６ａ，６ｂを設けたことにより、音源部１から送波される超音波は、筒体６ａ，６ｂの内部空間を通ることで拡散が抑制され、音源部１と受波素子３との間における超音波の拡散による音圧の低下を抑制することができるので、監視空間中に浮遊粒子がない状態において受波素子３で受波される超音波の音圧を高く維持でき、浮遊粒子の濃度の変化量に対する受波素子３の出力の変化量が比較的大きくなり、その結果、ＳＮ比が向上するという効果がある。   Furthermore, according to the configuration of FIG. 13A, since the cylinders 6 a and 6 b are provided between the sound source unit 1 and the wave receiving element 3, the ultrasonic waves transmitted from the sound source unit 1 are cylindrical. Diffusion is suppressed by passing through the internal spaces 6a and 6b, and a decrease in sound pressure due to diffusion of ultrasonic waves between the sound source unit 1 and the receiving element 3 can be suppressed. The sound pressure of the ultrasonic wave received by the wave receiving element 3 can be maintained high in the absence of noise, and the amount of change in the output of the wave receiving element 3 relative to the amount of change in the concentration of suspended particles becomes relatively large. The ratio is improved.

なお、図１３の例では、筒体６ａ，６ｂの各開口端面に音源部１および受波素子３がそれぞれ突き合わされるように配置されており、各筒体６ａ，６ｂの内部が監視空間となるので、たとえば筒体６ａ，６ｂの長手方向に沿う側面には内部に煙粒子等の浮遊粒子を案内する孔（図示せず）が形成される。   In the example of FIG. 13, the sound source unit 1 and the receiving element 3 are arranged so as to face each opening end face of the cylinders 6 a and 6 b, and the inside of each cylinder 6 a and 6 b is a monitoring space. Therefore, for example, holes (not shown) for guiding suspended particles such as smoke particles are formed in the side surfaces along the longitudinal direction of the cylinders 6a and 6b.

また、本実施形態の他の例として、一方の筒体６ａを省略して、音源部１から受波素子３に直接伝わる超音波を第１の超音波Ｓｗ１とする構成や、音源部１と受波素子３とが並ぶ方向に沿った反射面を音源部１および受波素子３の側方に形成し、音源部１から受波素子３に直接伝わる超音波を第１の超音波Ｓｗ１とするとともに、音源部１から送波された後に反射面で反射されて受波素子３に伝わる超音波を第２の超音波Ｓｗ２とする構成も考えられる。   As another example of the present embodiment, one cylindrical body 6a is omitted, and the ultrasonic wave directly transmitted from the sound source unit 1 to the wave receiving element 3 is used as the first ultrasonic wave Sw1, A reflection surface along the direction in which the wave receiving elements 3 are arranged is formed on the side of the sound source unit 1 and the wave receiving element 3, and the ultrasonic wave directly transmitted from the sound source unit 1 to the wave receiving element 3 is referred to as the first ultrasonic wave Sw1. In addition, a configuration in which the ultrasonic wave reflected from the reflection surface and transmitted to the wave receiving element 3 after being transmitted from the sound source unit 1 is the second ultrasonic wave Sw2 is also conceivable.

あるいは、音源部１と受波素子３との間に経路長の異なる複数の伝播経路を形成するために、図１４に示すように第１および第２の反射面７ａ，７ｂを、音源部１から送波された超音波の進行方向（図１４の左右方向）において互いに対向するように配置してもよい。各反射面７ａ，７ｂはそれぞれ超音波を反射するものであって、受波素子３は第１の反射面７ａ上に、音源部１は第２の反射面７ｂ上にそれぞれ配設される。ここで、周波数成分抽出手段４０は、音源部１から受波素子３に伝播されるまでに反射面７ａ，７ｂで反射された回数の異なる複数の超音波の各々から、各周波数成分の強度をそれぞれ抽出する。   Alternatively, in order to form a plurality of propagation paths having different path lengths between the sound source unit 1 and the wave receiving element 3, the first and second reflecting surfaces 7a and 7b are replaced with the sound source unit 1 as shown in FIG. They may be arranged so as to face each other in the traveling direction of the ultrasonic waves transmitted from (the left-right direction in FIG. 14). Each of the reflection surfaces 7a and 7b reflects ultrasonic waves. The wave receiving element 3 is disposed on the first reflection surface 7a, and the sound source unit 1 is disposed on the second reflection surface 7b. Here, the frequency component extraction means 40 obtains the intensity of each frequency component from each of a plurality of ultrasonic waves having different numbers of times reflected by the reflection surfaces 7a and 7b before being propagated from the sound source unit 1 to the wave receiving element 3. Extract each one.

すなわち、図１４のように音源部１から受波素子３に直接伝わる超音波を第１の超音波Ｓｗ１とするとともに、音源部１から送波された後に第１の反射面７ａで反射され、さらに第２の反射面７ｂで反射されることによって受波素子３に伝わる超音波を第２の超音波Ｓｗ２とする。しかして、反射面７ａ，７ｂでの反射回数が０回の第１の超音波Ｓｗ１と、反射面７ａ，７ｂでの反射回数が２回の第２の超音波Ｓｗ２とでは、伝播経路の経路長が異なることとなり、周波数成分抽出手段４０ではこれらの超音波Ｓｗ１，Ｓｗ２の各々から各周波数成分の強度が算出される。ここにおいて、受波素子３で各超音波Ｓｗ１，Ｓｗ２を区別可能とするため、各超音波Ｓｗ１，Ｓｗ２の経路長の差と音源部１から１回に送波する超音波の波数とを調整することにより超音波同士の重なりが生じないようにする点は、図１３の例と同様である。   That is, the ultrasonic wave directly transmitted from the sound source unit 1 to the wave receiving element 3 as shown in FIG. 14 is set as the first ultrasonic wave Sw1, and after being transmitted from the sound source unit 1, is reflected by the first reflecting surface 7a. Furthermore, an ultrasonic wave transmitted to the wave receiving element 3 by being reflected by the second reflecting surface 7b is referred to as a second ultrasonic wave Sw2. Thus, the path of the propagation path between the first ultrasonic wave Sw1 with 0 reflections on the reflection surfaces 7a and 7b and the second ultrasonic wave Sw2 with 2 reflections on the reflection surfaces 7a and 7b. The lengths are different, and the frequency component extraction means 40 calculates the intensity of each frequency component from each of the ultrasonic waves Sw1 and Sw2. Here, in order to enable the wave receiving element 3 to distinguish the ultrasonic waves Sw1 and Sw2, the difference in path length between the ultrasonic waves Sw1 and Sw2 and the wave number of the ultrasonic waves transmitted from the sound source unit 1 at once are adjusted. This is the same as the example of FIG. 13 in that the ultrasonic waves do not overlap each other.

ところで、図１４の例では、各反射面７ａ，７ｂが反射波を他方の反射面７ａ，７ｂ上に集音する形に湾曲した凹型の曲面からなる。さらに、音源部１と受波素子３とは各反射面７ａ，７ｂ上において、他方の反射面７ａ，７ｂに平面波として入射し反射された超音波が焦点を結ぶ位置に配置されている。   By the way, in the example of FIG. 14, each reflective surface 7a, 7b consists of a concave curved surface curved in the shape which collects a reflected wave on the other reflective surface 7a, 7b. Furthermore, the sound source unit 1 and the wave receiving element 3 are disposed on the reflecting surfaces 7a and 7b at positions where the reflected ultrasonic waves incident on the other reflecting surfaces 7a and 7b and reflected are focused.

要するに、第２の反射面７ｂ上に配置された音源部１から放射状に広がりながら受波素子３側の第１の反射面７ａに到達した超音波は、第１の反射面７ａで反射されることによって音源部１側の第２の反射面７ｂに対する平行波となり、その後、第２の反射面７ｂで反射されることによって第１の反射面７ａ上の受波素子３の位置で焦点を結ぶこととなる。そのため、反射面７ａ，７ｂでの反射を繰り返しても超音波は拡散しにくく、したがって、音源部１と受波素子３との間における超音波の拡散による音圧の低下を抑制することができる。その結果、浮遊粒子の濃度の変化量に対する受波素子３の出力の変化量が比較的大きくなり、ＳＮ比が向上する。   In short, the ultrasonic waves that reach the first reflecting surface 7a on the wave receiving element 3 side while spreading radially from the sound source unit 1 disposed on the second reflecting surface 7b are reflected by the first reflecting surface 7a. As a result, a parallel wave is generated with respect to the second reflecting surface 7b on the sound source unit 1 side, and then the light is reflected by the second reflecting surface 7b, thereby focusing at the position of the wave receiving element 3 on the first reflecting surface 7a. It will be. Therefore, even if the reflection on the reflecting surfaces 7a and 7b is repeated, the ultrasonic wave is not easily diffused. Therefore, a decrease in sound pressure due to the diffusion of the ultrasonic wave between the sound source unit 1 and the wave receiving element 3 can be suppressed. . As a result, the amount of change in the output of the wave receiving element 3 with respect to the amount of change in the concentration of suspended particles becomes relatively large, and the SN ratio is improved.

以上説明した本実施形態の浮遊粒子測定システムでは、周波数成分抽出手段４０は音源部１から同時に送波された超音波から複数の周波数成分の強度を抽出するので、個々の超音波の送波時に送波音圧のばらつきが生じることで浮遊粒子の種別や濃度の推定確度が低くなったり、超音波の送波に伴う消費電力が大きくなったりすることを回避できる。また、周波数成分抽出手段４０は、異なるタイミングで受波素子３に到達した超音波Ｓｗ１，Ｓｗ２の各々から各周波数成分の強度を順次抽出するので、受波素子３の出力を複数のフィルタ手段４５ａ〜４５ｃに同時に通す必要はなく、分配手段４６を省略することができる。   In the suspended particle measurement system according to the present embodiment described above, the frequency component extraction unit 40 extracts the intensity of a plurality of frequency components from the ultrasonic waves transmitted simultaneously from the sound source unit 1. It can be avoided that the estimation accuracy of the type and concentration of suspended particles is lowered due to the variation in the transmitted sound pressure, and that the power consumption associated with the transmission of ultrasonic waves is increased. Further, since the frequency component extraction means 40 sequentially extracts the intensity of each frequency component from each of the ultrasonic waves Sw1 and Sw2 that have reached the wave receiving element 3 at different timings, the output of the wave receiving element 3 is output to a plurality of filter means 45a. ˜45c need not be passed simultaneously, and the distribution means 46 can be omitted.

なお、その他の構成および機能は実施形態１と同様である。   Other configurations and functions are the same as those in the first embodiment.

ところで、上記各実施形態の浮遊粒子測定システムは、音源部１からの超音波の拡散範囲を狭める拡散防止部材を備えるものであってもよい。すなわち、図１３の例では音源部１と受波素子３との間に設けられた筒体６ａ，６ｂが拡散防止部材として機能しているが、筒体６ａ，６ｂ以外の拡散防止部材を適用してもよい。たとえば、音源部１からの超音波の拡散範囲を狭める拡散防止部材として一対の拡散防止板を用いることができる。   By the way, the suspended particle measuring system of each of the above embodiments may include a diffusion preventing member that narrows the diffusion range of the ultrasonic wave from the sound source unit 1. That is, in the example of FIG. 13, the cylinders 6 a and 6 b provided between the sound source unit 1 and the wave receiving element 3 function as diffusion preventing members, but diffusion preventing members other than the cylinders 6 a and 6 b are applied. May be. For example, a pair of diffusion prevention plates can be used as a diffusion prevention member that narrows the diffusion range of ultrasonic waves from the sound source unit 1.

各拡散防止板はそれぞれ平面視矩形状の平板からなり、一対の拡散防止板は一表面同士を対向させるように略平行に配設される。ここで、一対の拡散防止板は、音源部１からの超音波を互いに対向する前記一表面間の空間に通すことで当該超音波の拡散範囲を狭めるものであって、対向する前記一表面間の空間を通して音源部１からの超音波を伝搬させるように、前記一表面の間に音源部１と受波素子３とを挟みこむ形で配設される。このように拡散防止板を設けたことにより、音源部１から送波される超音波は、拡散防止板の前記一表面で囲まれた監視空間を通ることで拡散が抑制され、したがって音源部１と受波素子３との間における超音波の拡散による音圧の低下を抑制することができる。   Each diffusion prevention plate is a flat plate having a rectangular shape in plan view, and the pair of diffusion prevention plates are arranged substantially in parallel so that one surface faces each other. Here, the pair of diffusion prevention plates narrows the diffusion range of the ultrasonic wave by passing the ultrasonic wave from the sound source unit 1 through the space between the one surface facing each other. The sound source unit 1 and the wave receiving element 3 are sandwiched between the surfaces so that the ultrasonic waves from the sound source unit 1 are propagated through the space. By providing the diffusion preventing plate in this manner, the ultrasonic wave transmitted from the sound source unit 1 is prevented from diffusing by passing through the monitoring space surrounded by the one surface of the diffusion preventing plate. And a decrease in sound pressure due to diffusion of ultrasonic waves between the receiving element 3 and the wave receiving element 3 can be suppressed.

また、上記各実施形態では、音源部１と制御部２と受波素子３と信号処理部４とを１枚の回路基板５に設けて図示しない器体内に収納してあるが、音源部１と制御部２とを備えた音源側ユニットと、受波素子３と信号処理部４とを備えた受波側ユニットとを別体として互いに対向配置する分離型の浮遊粒子測定システムを構成するようにしてもよい。また、音源部１は上述の図３に示した構成の音波発生素子に限らず、たとえば、アルミニウム製の薄板を発熱体部として当該発熱体部への通電に伴う発熱体部の急激な温度変化による熱衝撃によって音波を発生させるものでもよい。   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 a single circuit board 5 and housed in a container (not shown). And a sound source side unit including the control unit 2 and a reception side unit including the wave receiving element 3 and the signal processing unit 4 are configured as separate bodies to constitute a separate suspended particle measurement system. 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.

さらにまた、上記各実施形態において、制御部２が、音源部１から防虫効果のある周波数の超音波を送波させるようにすれば、上記監視空間に虫が侵入するのを防止することができ、虫に起因した浮遊粒子の誤測定を低減できる。ここで、制御部２は、浮遊粒子の種別および濃度を推定するために音源部１から送波させる超音波とは別に、防虫効果のある周波数の超音波を定期的に送波させるようにしてもよいし、浮遊粒子の種別および濃度を推定するために音源部１から送波する超音波に防虫効果のある周波数成分を含むようにしてもよい。   Furthermore, in each of the above embodiments, if the control unit 2 transmits ultrasonic waves having a frequency having an insect-proofing effect from the sound source unit 1, it is possible to prevent insects from entering the monitoring space. , False measurement of suspended particles caused by insects can be reduced. Here, the control unit 2 periodically transmits ultrasonic waves having an insecticidal effect separately from the ultrasonic waves transmitted from the sound source unit 1 in order to estimate the type and concentration of suspended particles. Alternatively, in order to estimate the type and concentration of suspended particles, the ultrasonic wave transmitted from the sound source unit 1 may include a frequency component having an insecticidal effect.

本発明の実施形態１の構成を示すブロック図である。It is a block diagram which shows the structure of Embodiment 1 of this invention. 同上の要部を示し、（ａ）は概略下面図、（ｂ）は概略側面図である。The principal part same as the above is shown, (a) is a schematic bottom view, (b) is a schematic side view. 同上に用いる音波発生素子を示す概略断面図である。It is a schematic sectional drawing which shows the sound wave generation element used for the same as the above. 同上に用いる受波素子を示し、（ａ）は一部破断した概略斜面図、（ｂ）は概略断面図である。The wave receiving element used for the above is shown, (a) is a partially broken schematic perspective view, and (b) is a schematic sectional view. 同上の動作例を示すフローチャートである。It is a flowchart which shows the operation example same as the above. 同上に用いる浮遊粒子の濃度と特定の周波数成分の減衰率との関係を示す説明図である。It is explanatory drawing which shows the relationship between the density | concentration of the suspended particle used for the same as the above, and the attenuation factor of a specific frequency component. （ａ）は音源部からの超音波の波形図、（ｂ）は（ａ）のパワースペクトル図である。(A) is a waveform diagram of ultrasonic waves from the sound source section, and (b) is a power spectrum diagram of (a). （ａ）は超音波の波形図、（ｂ）は（ａ）のパワースペクトル図である。(A) is a waveform diagram of ultrasonic waves, (b) is a power spectrum diagram of (a). （ａ）は受波素子の出力のパワースペクトル図、（ｂ）は他のパワースペクトル図である。(A) is the power spectrum figure of the output of a receiving element, (b) is another power spectrum figure. （ａ）は音源部からの超音波の波形図、（ｂ）は（ａ）のパワースペクトル図である。(A) is a waveform diagram of ultrasonic waves from the sound source section, and (b) is a power spectrum diagram of (a). 同上の周波数成分の強度の抽出方法の説明図である。It is explanatory drawing of the extraction method of the intensity | strength of a frequency component same as the above. 同上の要部の概略構成図である。It is a schematic block diagram of the principal part same as the above. 本発明の実施形態２の動作を示す概略図である。It is the schematic which shows the operation | movement of Embodiment 2 of this invention. 同上の他の構成例を示す概略図である。It is the schematic which shows the other structural example same as the above. 従来例の構成を示すブロック図である。It is a block diagram which shows the structure of a prior art example. 同上の音源部の出力周波数と音圧の単位減衰率との関係を示す説明図である。It is explanatory drawing which shows the relationship between the output frequency of a sound source part same as the above, and the unit attenuation rate of a sound pressure. 同上の音源部の出力周波数と相対的単位減衰率との関係を示す説明図である。It is explanatory drawing which shows the relationship between the output frequency of a sound source part same as the above, and a relative unit attenuation factor.

符号の説明Explanation of symbols

１ 音源部
２ 制御部
３ 受波素子
４ 信号処理部
１１ ベース基板
１２ 熱絶縁層
１３ 発熱体層（発熱体部）
４０ 周波数成分抽出手段
４１ 粒子種別推定手段
４２ 濃度推定手段
４４ 記憶手段
４５ａ〜４５ｃ フィルタ手段
４６ 分配手段 DESCRIPTION OF SYMBOLS 1 Sound source part 2 Control part 3 Receiver element 4 Signal processing part 11 Base board 12 Thermal insulation layer 13 Heat generating body layer (heat generating body part)
40 Frequency component extraction means 41 Particle type estimation means 42 Concentration estimation means 44 Storage means 45a to 45c Filter means 46 Distribution means

Claims (9)

複数の周波数成分を含む音波を送波する音源部と、音源部を制御する制御部と、音源部から送波された音波の音圧を検出する受波素子と、受波素子の出力に基づいて音源部と受波素子との間の監視空間に存在する浮遊粒子の種別および濃度を測定する信号処理部とを備え、信号処理部は、受波素子で検出された音波から各周波数成分の強度を抽出する周波数成分抽出手段と、音源部と受波素子との間の監視空間に存在する浮遊粒子の種別および濃度に応じた各周波数成分の周波数と強度の基準値からの減衰量との関係データを記憶した記憶手段と、周波数成分抽出手段で抽出された各周波数成分の強度と記憶手段に記憶されている関係データとを用いて監視空間に浮遊している粒子の種別を推定する粒子種別推定手段と、特定の周波数成分の強度の基準値からの減衰量に基づいて監視空間の浮遊粒子の濃度を推定する濃度推定手段とを有することを特徴とする浮遊粒子測定システム。   Based on a sound source unit that transmits a sound wave including a plurality of frequency components, a control unit that controls the sound source unit, a receiving element that detects sound pressure of the sound wave transmitted from the sound source unit, and an output of the receiving element A signal processing unit for measuring the type and concentration of suspended particles existing in the monitoring space between the sound source unit and the receiving element, and the signal processing unit is configured to detect each frequency component from the sound wave detected by the receiving element. The frequency component extraction means for extracting the intensity, and the attenuation amount from the frequency and intensity reference value of each frequency component according to the type and concentration of the suspended particles existing in the monitoring space between the sound source unit and the receiving element Particles that estimate the type of particles floating in the monitoring space using the storage means that stores the relation data, the intensity of each frequency component extracted by the frequency component extraction means, and the relation data that is stored in the storage means Type estimation means and specific frequency components Suspended particle measuring system characterized by having a concentration estimation means for estimating the concentration of suspended particles in the monitoring space on the basis of the attenuation amount from the reference value of the degree. 前記記憶手段は、前記関係データとして各周波数成分の周波数と強度の基準値からの減衰量を基準値で除した減衰率との関係データを記憶していることを特徴とする請求項１記載の浮遊粒子測定システム。   2. The storage device according to claim 1, wherein the storage means stores relationship data between the frequency of each frequency component and an attenuation rate obtained by dividing an attenuation amount from a reference value of intensity by a reference value as the relationship data. Airborne particle measurement system. 前記音源部は、発熱体部への通電に伴う発熱体部の温度変化により空気に熱衝撃を与えることで音波を発生するものであることを特徴とする請求項１または請求項２に記載の浮遊粒子測定システム。   3. The sound source unit according to claim 1, wherein the sound source unit generates a sound wave by applying a thermal shock to air due to a temperature change of the heat generating unit accompanying energization of the heat generating unit. Airborne particle measurement system. 前記音源部は、ベース基板の一表面側に前記発熱体部が形成されるとともに、ベース基板の前記一表面側で前記発熱体部とベース基板との間に設けられて前記発熱体部とベース基板とを熱絶縁する多孔質層からなる熱絶縁層を有してなることを特徴とする請求項３記載の浮遊粒子測定システム。   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. 4. The suspended particle measuring system according to claim 3, further comprising a thermal insulating layer comprising a porous layer that thermally insulates the substrate. 前記音源部が送波する前記複数の周波数成分を含む音波は、単パルス状の音波であることを特徴とする請求項１ないし請求項４のいずれか１項に記載の浮遊粒子測定システム。   5. The suspended particle measurement system according to claim 1, wherein the sound wave including the plurality of frequency components transmitted by the sound source unit is a single-pulse sound wave. 6. 前記周波数成分抽出手段は、各周波数成分の信号をそれぞれ通過させるフィルタ手段を有し、前記受波素子の出力を前記フィルタ手段に通すことで各周波数成分の強度を抽出することを特徴とする請求項１ないし請求項５のいずれか１項に記載の浮遊粒子測定システム。   The frequency component extraction unit includes a filter unit that allows a signal of each frequency component to pass therethrough, and extracts the intensity of each frequency component by passing the output of the receiving element through the filter unit. The suspended particle measuring system according to any one of claims 1 to 5. 前記フィルタ手段は各周波数成分ごとに個別に設けられており、前記周波数成分抽出手段は、前記受波素子の出力を各フィルタ手段に分配する分配手段を有することを特徴とする請求項６記載の浮遊粒子測定システム。   7. The filter means according to claim 6, wherein the filter means is provided separately for each frequency component, and the frequency component extraction means has distribution means for distributing the output of the receiving element to each filter means. Airborne particle measurement system. 前記周波数成分抽出手段は、高速フーリエ変換により各周波数成分の強度を抽出することを特徴とする請求項１ないし請求項５のいずれか１項に記載の浮遊粒子測定システム。   6. The suspended particle measurement system according to claim 1, wherein the frequency component extraction unit extracts the intensity of each frequency component by fast Fourier transform. 前記周波数成分抽出手段は、前記音源部から同時に送波され前記監視空間のうち経路長の異なる伝播経路を通して前記受波素子にそれぞれ伝播された複数の音波の各々から、各周波数成分の強度をそれぞれ抽出することを特徴とする請求項１ないし請求項６のいずれか１項に記載の浮遊粒子測定システム。
The frequency component extracting means transmits the intensity of each frequency component from each of a plurality of sound waves transmitted simultaneously from the sound source unit and propagated to the receiving element through propagation paths having different path lengths in the monitoring space. The suspended particle measuring system according to any one of claims 1 to 6, wherein the suspended particle measuring system is extracted.
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