WO2017122659A1 - Gas detecting device and gas detecting method - Google Patents

Gas detecting device and gas detecting method Download PDF

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Publication number
WO2017122659A1
WO2017122659A1 PCT/JP2017/000579 JP2017000579W WO2017122659A1 WO 2017122659 A1 WO2017122659 A1 WO 2017122659A1 JP 2017000579 W JP2017000579 W JP 2017000579W WO 2017122659 A1 WO2017122659 A1 WO 2017122659A1
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Prior art keywords
gas
phase difference
light
unit
detected
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PCT/JP2017/000579
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French (fr)
Japanese (ja)
Inventor
将史 影山
義憲 井手
亮太 石川
久一郎 今出
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コニカミノルタ株式会社
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Priority to JP2017561124A priority Critical patent/JPWO2017122659A1/en
Publication of WO2017122659A1 publication Critical patent/WO2017122659A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers

Definitions

  • the present invention relates to a gas detection device and a gas detection method that can be used to calculate the concentration of a gas to be detected.
  • each detected gas has its own light absorption spectrum.
  • the amount of light attenuation is proportional to the concentration of the detection gas.
  • a gas detection device using this phenomenon is described in Patent Document 1 and the like.
  • the gas detection device of Patent Document 1 generates FM modulated light having a center frequency fc and frequency-modulated by a frequency fm by a light source unit, and irradiates the gas to be detected.
  • the gas detector receives light transmitted through the gas to be detected by the light receiving unit.
  • the light absorption spectrum of the gas is approximated by a quadratic function that is substantially line symmetric with respect to the frequency fc.
  • the output signal of the light receiving unit includes not only the component of the modulation frequency fm but also, for example, a second-order (2 ⁇ fm) harmonic component.
  • the gas detection device obtains the gas concentration using a signal processing circuit based on the fundamental wave component and the second harmonic component.
  • optical path noise (a harmonic component of a predetermined order) due to etalon fringe may be superimposed on the FM modulated light on the optical path between the light source unit and the light receiving unit.
  • the optical path noise may be misidentified as a harmonic component of a predetermined order due to absorption in the gas to be detected, and the concentration may be detected.
  • an object of the present invention is to provide a gas detection device and a gas detection method capable of accurately discriminating harmonic components and optical path noise caused by absorption in a gas to be detected.
  • One aspect of the present invention is FM modulated light having a frequency of an absorption line of a gas to be detected as a center frequency, a light source unit that emits FM modulated light that is frequency-modulated at a predetermined frequency, and the FM modulated light is
  • the first light receiving unit that outputs a signal based on the first return light absorbed by the detection gas, and the phase difference between the fundamental wave component and the harmonic component contained in the output signal of the first light receiving unit is a first phase difference.
  • a first phase difference detection unit for detecting as a gas detection device.
  • FM modulated light having a center frequency at the frequency of the absorption line of the gas to be detected, the first step of emitting FM modulated light frequency-modulated at a predetermined frequency, and the FM modulated light
  • the first light receiving step for outputting a signal based on the first return light absorbed by the detected gas, and the phase difference between the fundamental wave component and the harmonic component included in the output signal of the first light receiving step are ranked first.
  • a first phase difference detecting step for detecting the phase difference.
  • FIG. 1 It is a figure which shows the structure of the gas detection apparatus which concerns on 1st embodiment. It is a figure used for description of the optical path noise resulting from an etalon fringe etc. It is a functional block diagram of the control part of FIG. It is a flowchart which shows operation
  • the gas detection device 1 has an appearance such as a portable video camera, a notebook PC, a smartphone, or a tablet terminal.
  • the concentration of a gas (hereinafter referred to as a gas to be detected) G to be detected in A) is obtained.
  • the gas detection device 1 includes a first light source unit 11, a first drive unit 12, a first light receiving unit 13, a first phase difference detection unit 14, a first derivation unit 15, The control part 16, the display apparatus 17, and the alerting
  • the first light source unit 11 includes a semiconductor laser such as a DFB (Distributed Feedback) laser.
  • the first drive unit 12 injects current into the semiconductor laser to emit light under the control of the control unit 16.
  • the semiconductor laser generates and emits FM modulated light Lfm.
  • the FM modulated light Lfm has a predetermined center frequency fc and is frequency-modulated with a predetermined modulation frequency fm.
  • the FM modulated light Lfm may be continuous light or pulsed light.
  • the modulation frequency fm is appropriately set to an appropriate value (for example, 10 kHz, 50 kHz, 100 kHz).
  • the center frequency fc is the frequency of the absorption line in the light absorption spectrum of the gas to be detected, and is determined by the type of the gas to be detected (see Table 1 below). In Table 1, the wavelength corresponding to the center frequency fc is shown for convenience. For example, if the gas to be detected is methane, the center frequency fc is set to a frequency corresponding to the wavelength of 1.654 ⁇ m of the R (3) line, for example.
  • the FM modulated light Lfm generated by the first light source unit 11 is emitted toward the monitoring area A.
  • the FM modulated light Lfm is absorbed by the detection gas G and attenuates according to the concentration of the detection gas G. Further, since the detected gas G has a unique light absorption spectrum, a harmonic component of a predetermined order is generated in the FM modulated light Lfm (for example, when the detected gas G is methane, a second-order harmonic component).
  • Such FM modulated light Lfm is incident on the first light receiving unit 13 after being scattered (reflected) by an object other than the gas G to be detected. In the present embodiment, the light incident on the first light receiving unit 13 is referred to as first return light Lr1.
  • an object O other than the gas to be detected G may exist on the optical path between the first light source unit 11 and the first light receiving unit 13 as shown in FIG.
  • the object O is glass, an optical component, or the like that can exist on the optical path.
  • optical path noise Ln (a harmonic component of a predetermined order) is generated due to interference (etalon fringe, etc.) at the interface with the outside.
  • the FM modulated light Lfm is indicated by a broken line
  • the optical path noise Ln is indicated by an alternate long and short dash line.
  • the conventional gas detection device In the conventional gas detection device, a harmonic component of a predetermined order generated by absorption in the detection gas G is superimposed on the first return light Lr1, or the optical path noise Ln is superimposed on the first return light Lr1. I did not judge whether or not. Therefore, the conventional gas detection device sometimes miscalculates the optical path noise Ln as a harmonic component of a predetermined order generated in the detected gas G and calculates the concentration of the detected gas G.
  • the first light receiving unit 13 is, for example, an InGaAs photodiode.
  • the first light receiving unit 13 performs photoelectric conversion when the first return light Lr1 is incident, and generates and outputs a first electric signal Se1 correlated with the light amount.
  • the output signal Se1 of the first light receiving unit 13 is branched into two, one being input to the first phase difference detecting unit 14 and the other being input to the first deriving unit 15.
  • the first phase difference detection unit 14 performs Fourier transform (specifically, FFT (Fast Fourier Transform)) on the input signal Se1, and converts the signal Se1 to the phase of the fundamental wave component included in the input signal Se1.
  • a phase difference ⁇ 1 of a harmonic component (for example, second harmonic) of a predetermined order included is obtained.
  • the first phase difference detection unit 14 outputs the obtained phase difference ⁇ 1 to the control unit 16.
  • the first deriving unit 15 obtains a value Vd that correlates with the concentration of the detected gas G based on the input signal Se1 by a so-called 2f detection method. Since the 2f detection method is well known, detailed description thereof will be omitted, but for details, see, for example, Patent Document 1.
  • control unit 16 includes an input / output interface unit (hereinafter referred to as an input / output IF unit) 161, a CPU 162 as a typical example of a computer device, a nonvolatile memory 163, a main memory 164, It has.
  • an input / output interface unit hereinafter referred to as an input / output IF unit
  • CPU 162 as a typical example of a computer device
  • nonvolatile memory 163
  • main memory 164 main memory
  • the input / output IF unit 161 transmits various signals and various data to the peripheral components 12, 17, and 18, and receives various data from the peripheral components 14 and 15.
  • the CPU 162 executes the program P stored in advance in the non-volatile memory 163 by using the main memory 164 as a work area, so that the determination unit 165, the concentration calculation unit 166, the display control unit 167, and the notification control unit 168 are performed. Function. These functional blocks 165 to 168 will be described in detail later.
  • the display device 17 is a liquid crystal display, for example, and displays an image indicating the concentration of the gas to be detected G, the gas to be detected G not being detected, and the like.
  • the notification device 18 is a speaker, for example, and outputs a sound indicating that the detected gas G has not been detected or that the return light has not been absorbed by the detected gas G.
  • the CPU 162 instructs the first drive unit 12 to supply an injection current to the semiconductor laser of the first light source unit 11.
  • FM modulated light Lfm is emitted from the first light source unit 11 toward the monitoring region A.
  • step S02 Part of the FM modulated light Lfm is incident on the first light receiving unit 13 as the first return light Lr1 by being absorbed by the detection gas G or being scattered by the other object O.
  • the first light receiving unit 13 generates the first electric signal Se1 based on the first return light Lr1, and outputs the first electric signal Se1 to the first phase difference detection unit 14 and the first derivation unit 15.
  • step S03 the first phase difference detection unit 14 obtains the phase difference ⁇ 1 based on the output signal Se1 of the first light receiving unit 13 and outputs it to the control unit 16 as described above.
  • the fundamental wave The phase difference ⁇ 1 of the harmonic component with respect to the component can be obtained in advance by experiments or the like.
  • the phase difference ⁇ 1 obtained in advance by experiments is described in advance in the program P as the reference value Vref.
  • the CPU 162 functions as the determination unit 165, and determines whether the reference value Vref described in advance and the phase difference ⁇ 1 input from the first phase difference detection unit 14 are the same or within an allowable range.
  • the CPU 162 as the determination unit 165 considers that a harmonic component of a predetermined order due to absorption in the detected gas G is superimposed on the first return light Lr1 in step S05, and the first The derivation unit 15 is instructed to obtain and return the correlation value Vd.
  • step S06 the first deriving unit 15 obtains the correlation value Vd with the concentration of the detected gas G as described above in response to the instruction of the determining unit 165, and returns it to the CPU 162 as the concentration calculating unit 166.
  • step S07 the concentration calculation unit 166 multiplies the received correlation value Vd by a predetermined proportional multiplier ⁇ to obtain the concentration of the detected gas G, and passes it to the CPU 162 as the display control unit 167.
  • step S08 the display control unit 167 generates image data Id indicating the concentration of the gas G to be detected, and then transfers the image data Id to the display device 17.
  • the display device 17 displays the concentration of the detected gas G according to the received image data Id.
  • step S04 If a negative determination is made in step S04, the CPU 162 as the determination unit 165 regards that the optical path noise Ln is superimposed on the first return light Lr1 in step S09, and correlates with the first deriving unit 15. Instructs not to obtain the value Vd. In addition, the determination unit 165 instructs the notification control unit 168 to generate the audio data Is.
  • step S010 the notification control unit 168 generates audio data Is indicating that the gas to be detected G has not been detected or that the optical path noise Ln is superimposed on the first return light Lr1, and the notification device 18 Forward to.
  • the notification device 18 notifies the user that the detected gas G has not been detected or that the optical path noise Ln is superimposed on the first return light Lr1 by voice output according to the received voice data Is.
  • the determination unit 165 receives the first light received by the first light receiving unit 13 based on the phase difference ⁇ 1 generated by the first phase difference detection unit 14. It is determined whether or not a harmonic component of a predetermined order due to the detected gas G is superimposed on the return light Lr1. If the determination unit 165 makes an affirmative determination, the concentration calculation unit 166 calculates the concentration of the detected gas G based on the correlation value Vd obtained by the first derivation unit 15. On the other hand, if the determination unit 165 makes a negative determination, the concentration calculation unit 166 does not calculate the concentration of the detected gas G.
  • the first phase difference detection unit 14 and the determination unit 165 are provided in the gas detection device 1, so that what is superimposed on the first return light Lr 1 is caused by the detected gas G. It is possible to accurately identify the harmonic component of the predetermined order or the optical path noise Ln. In addition to the above, the possibility of erroneous detection of the concentration of the gas G to be detected can be reduced.
  • the first light source unit 11 has been described as generating the FM modulated light Lfm by the direct modulation method. However, the first light source unit 11 may generate the FM modulated light Lfm by the external modulation method. I do not care. In this case, the first light source unit 11 includes, for example, a semiconductor laser and an external modulator.
  • the user is notified by voice that the gas to be detected G has not been detected or that the optical path noise Ln is superimposed on the first return light Lr1.
  • the present invention is not limited to this, and the user may be notified by displaying them on the display device 17. In this case, the display device 17 becomes the notification device 18.
  • the gas detection device 1 ⁇ / b> A includes a deflection / transmission unit 21, a storage unit 22, a second light receiving unit 23, and a second phase difference detection unit 24 compared to the gas detection device 1 of FIG. Furthermore, it differs in the point provided. Other than that, there is no structural difference between the gas detectors 1 and 1A. Therefore, in FIG. 5, the same reference numerals are assigned to the components corresponding to the configuration of FIG.
  • the deflection / transmission unit 21 is a half mirror, for example, and is disposed on the optical path of the FM modulated light Lfm from the first light source unit 11 and in the immediate vicinity of the first light source unit 11. More specifically, the first light source unit 11 and the deflecting / transmitting unit 21 are disposed close to each other so that the gas G to be detected and the other object O do not exist.
  • the deflecting / transmitting unit 21 arranged as described above deflects a part of the FM modulated light Lfm emitted from the first light source unit 11 toward the accommodating unit 22 and also monitors the remainder of the FM modulated light Lfm as a monitoring region. It penetrates toward A.
  • the accommodating part 22 is a so-called sample gas cell, and is a container that accommodates the same type of gas as the gas G to be detected as the reference gas Gref.
  • the accommodating part 22 has an infrared transmitting incident side window part and an emitting side window part so that the FM modulated light Lfm from the deflecting / transmitting part 21 transmits the reference gas Gref.
  • the FM modulated light Lfm from the deflecting / transmitting unit 21 is incident from the incident side window portion and is absorbed by the internal reference gas Gref, and then is emitted from the emission side window portion to the second light receiving unit 23 at the subsequent stage. It is emitted toward.
  • the light incident on the second light receiving unit 23 is referred to as second return light Lr2.
  • the second light receiving unit 23 is, for example, a Si photodiode.
  • the second light receiving unit 23 performs photoelectric conversion when the second return light Lr2 is incident, and generates and outputs a second electric signal Se2 correlated with the light amount.
  • the output signal Se ⁇ b> 2 from the second light receiving unit 23 is input to the second phase difference detection unit 24.
  • the second phase difference detection unit 24 performs Fourier transform (specifically, FFT) on the input signal Se2, and has a predetermined order included in the signal Se2 with respect to the phase of the fundamental wave component included in the input signal Se2.
  • a phase difference hereinafter referred to as a second phase difference
  • ⁇ 2 of a harmonic component for example, a second harmonic
  • the second phase difference detection unit 24 outputs the obtained second phase difference ⁇ 2 to the control unit 16.
  • the CPU 162 emits the FM modulated light Lfm from the first light source unit 11 in the same manner as in step S01 of FIG. 4.
  • the FM modulated light Lfm is bifurcated by the deflection / transmission unit 21, one is deflected toward the accommodation unit 22, and the other is transmitted toward the monitoring region A.
  • the other of the FM modulated light Lfm is incident on the first light receiving unit 13 as the first return light Lr1 by being absorbed by the gas G to be detected or scattered by the other object O.
  • the first light receiving unit 13 generates the first electric signal Se1 based on the first return light Lr1, and outputs the first electric signal Se1 to the first phase difference detecting unit 14 and the first deriving unit 15.
  • step S ⁇ b> 13 the second light receiving unit 23 generates the second electric signal Se ⁇ b> 2 based on the second return light Lr ⁇ b> 2 and outputs it to the second phase difference detection unit 24.
  • the phase difference detection units 14 and 24 obtain the phase differences ⁇ 1 and ⁇ 2 based on the output signals Se1 and Se2 of the light receiving units 13 and 23 and output them to the control unit 16 as described above.
  • step S16 the CPU 162 functions as the determination unit 165 and determines whether or not both phase differences ⁇ 1 and ⁇ 2 are the same or within an allowable range.
  • the CPU 162 displays the concentration of the detected gas G on the display device 17 in steps S17 to S110 in the same procedure as in S05 to S08 of FIG.
  • step S16 the CPU 162 notifies the user that the detected gas G has not been detected in the notification device 18 in the same manner as in steps S09 and S010 in S111 and S112. To do.
  • the determination unit 165 is based on the phase differences ⁇ 1 and ⁇ 2 generated by the phase difference detection units 14 and 24, as in the first embodiment. It is determined whether or not a harmonic component of a predetermined order due to the detected gas G is superimposed on the first return light Lr1 received by the first light receiving unit 13. Therefore, the effect described in the first to third columns can also be achieved by the gas detection device 1A according to the present embodiment.
  • the gas detection device and the gas detection method according to the present invention can reduce erroneous detection of the detected gas concentration and are useful for a gas monitor device and the like.

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Abstract

This gas detecting device is provided with: a light source unit that emits FM modulated light which is frequency modulated using a prescribed frequency and in which the absorption line frequency of a gas being detected is set as a central frequency; a first light receiving unit which outputs a signal on the basis of first returned light obtained as a result of absorption of the FM modulated light by the gas being detected; and a first phase difference detecting unit which detects as a first phase difference a phase difference between a fundamental wave component and a harmonic component contained in the output signal from the first light receiving unit.

Description

ガス検知装置およびガス検知方法Gas detection device and gas detection method
　本発明は、被検出ガスの濃度算出に使用可能なガス検知装置およびガス検知方法に関する。 The present invention relates to a gas detection device and a gas detection method that can be used to calculate the concentration of a gas to be detected.
　周知の通り、被検出ガスにはそれぞれ固有の光吸収スペクトルが存在する。その吸収線の周波数を中心周波数ｆｃとして有する光が被検出ガスを通過すると、光減衰量は被検出ガスの濃度に比例する。この現象を利用したガス検知装置が特許文献１等に記載されている。特許文献１のガス検知装置は、光源部により、中心周波数ｆｃを有し周波数ｆｍで周波数変調されたＦＭ変調光を生成し被検出ガスに照射する。また、ガス検知装置は、受光部により、被検出ガスを透過した光を受光する。ガスの光吸収スペクトルは、周波数ｆｃを基準として略線対称な二次関数で近似される。従って、受光部の出力信号には、変調周波数ｆｍの成分だけでなく、例えば二次（２×ｆｍ）の高調波成分も含まれる。ガス検知装置は、基本波成分および二次の高調波成分に基づきガス濃度を信号処理回路にて求める。 As is well known, each detected gas has its own light absorption spectrum. When light having the frequency of the absorption line as the center frequency fc passes through the detection gas, the amount of light attenuation is proportional to the concentration of the detection gas. A gas detection device using this phenomenon is described in Patent Document 1 and the like. The gas detection device of Patent Document 1 generates FM modulated light having a center frequency fc and frequency-modulated by a frequency fm by a light source unit, and irradiates the gas to be detected. The gas detector receives light transmitted through the gas to be detected by the light receiving unit. The light absorption spectrum of the gas is approximated by a quadratic function that is substantially line symmetric with respect to the frequency fc. Accordingly, the output signal of the light receiving unit includes not only the component of the modulation frequency fm but also, for example, a second-order (2 × fm) harmonic component. The gas detection device obtains the gas concentration using a signal processing circuit based on the fundamental wave component and the second harmonic component.
特開平７－１５１６８１号公報Japanese Patent Laid-Open No. 7-151681
　しかしながら、従来のガス検知装置では、光源部および受光部の間の光路上で、エタロンフリンジ等による光路雑音（所定次数の高調波成分）がＦＭ変調光に重畳されることがある。従来のガス検知装置では、この光路雑音を、被検出ガスでの吸収に起因する所定次数の高調波成分と誤認して濃度検知することがあった。 However, in the conventional gas detection device, optical path noise (a harmonic component of a predetermined order) due to etalon fringe may be superimposed on the FM modulated light on the optical path between the light source unit and the light receiving unit. In the conventional gas detection device, the optical path noise may be misidentified as a harmonic component of a predetermined order due to absorption in the gas to be detected, and the concentration may be detected.
　それゆえに、本発明の目的は、被検出ガスでの吸収に起因する高調波成分と光路雑音とを正確に識別可能なガス検知装置およびガス検知方法を提供することである。 Therefore, an object of the present invention is to provide a gas detection device and a gas detection method capable of accurately discriminating harmonic components and optical path noise caused by absorption in a gas to be detected.
　本発明の一形態は、被検出ガスの吸収線の周波数を中心周波数とするＦＭ変調光であって、所定周波数で周波数変調されたＦＭ変調光を出射する光源部と、前記ＦＭ変調光が前記被検出ガスで吸収された第一戻り光に基づき信号を出力する第一受光部と、前記第一受光部の出力信号に含まれる基本波成分と高調波成分との位相差を第一位相差として検出する第一位相差検出部と、を備えたガス検知装置に向けられる。 One aspect of the present invention is FM modulated light having a frequency of an absorption line of a gas to be detected as a center frequency, a light source unit that emits FM modulated light that is frequency-modulated at a predetermined frequency, and the FM modulated light is The first light receiving unit that outputs a signal based on the first return light absorbed by the detection gas, and the phase difference between the fundamental wave component and the harmonic component contained in the output signal of the first light receiving unit is a first phase difference. And a first phase difference detection unit for detecting as a gas detection device.
　また、他の形態は、被検出ガスの吸収線の周波数を中心周波数とするＦＭ変調光であって、所定周波数で周波数変調されたＦＭ変調光を出射する第一ステップと、前記ＦＭ変調光が前記被検出ガスで吸収された第一戻り光に基づき信号を出力する第一受光ステップと、前記第一受光ステップの出力信号に含まれる基本波成分と高調波成分との位相差を第一位相差として検出する第一位相差検出ステップと、を備えたガス検知方法に向けられる。 In another form, FM modulated light having a center frequency at the frequency of the absorption line of the gas to be detected, the first step of emitting FM modulated light frequency-modulated at a predetermined frequency, and the FM modulated light The first light receiving step for outputting a signal based on the first return light absorbed by the detected gas, and the phase difference between the fundamental wave component and the harmonic component included in the output signal of the first light receiving step are ranked first. And a first phase difference detecting step for detecting the phase difference.
　上記各形態によれば、被検出ガスと雑音とを正確に識別可能なガス検知装置およびガス検知方法を提供することが出来る。 According to each of the above embodiments, it is possible to provide a gas detection device and a gas detection method capable of accurately identifying a gas to be detected and noise.
第一実施形態に係るガス検知装置の構成を示す図である。It is a figure which shows the structure of the gas detection apparatus which concerns on 1st embodiment. エタロンフリンジ等に起因する光路雑音の説明に使用される図である。It is a figure used for description of the optical path noise resulting from an etalon fringe etc. 図１の制御部の機能ブロック図である。It is a functional block diagram of the control part of FIG. 図１のガス検知装置の動作を示すフロー図であって、第一施形態に係るガス検知方法を示すフロー図である。It is a flowchart which shows operation | movement of the gas detection apparatus of FIG. 1, Comprising: It is a flowchart which shows the gas detection method which concerns on 1st embodiment. 第二実施形態に係るガス検知装置の構成を示す図である。It is a figure which shows the structure of the gas detection apparatus which concerns on 2nd embodiment. 図５のガス検知装置の動作を示すフロー図であって、第二実施形態に係るガス検知方法を示すフロー図である。It is a flowchart which shows operation | movement of the gas detection apparatus of FIG. 5, Comprising: It is a flowchart which shows the gas detection method which concerns on 2nd embodiment.
≪１．第一実施形態≫
　以下、上記図面を参照して、本発明の第一実施形態に係るガス検知装置１およびガス検知方法を詳説する。 << 1. First embodiment >>
Hereinafter, the gas detection device 1 and the gas detection method according to the first embodiment of the present invention will be described in detail with reference to the drawings.
≪１－１．ガス検知装置１の構成≫
　図１において、ガス検知装置１は、例えばポータブルビデオカメラ、ノート型ＰＣ、スマートフォンまたはタブレット端末のような外観をしており、所謂２ｆ検波法により、例えばガス漏れを監視すべき領域（以下、監視領域という）Ａにて検出されるべきガス（以下、被検出ガスという）Ｇの濃度を求める。 << 1-1. Configuration of Gas Detector 1 >>
In FIG. 1, the gas detection device 1 has an appearance such as a portable video camera, a notebook PC, a smartphone, or a tablet terminal. The concentration of a gas (hereinafter referred to as a gas to be detected) G to be detected in A) is obtained.
　ガス検知装置１は、図１に示すように、第一光源部１１と、第一駆動部１２と、第一受光部１３と、第一位相差検出部１４と、第一導出部１５と、制御部１６と、表示装置１７と、報知装置１８と、を備えている。 As shown in FIG. 1, the gas detection device 1 includes a first light source unit 11, a first drive unit 12, a first light receiving unit 13, a first phase difference detection unit 14, a first derivation unit 15, The control part 16, the display apparatus 17, and the alerting | reporting apparatus 18 are provided.
　第一光源部１１は、ＤＦＢ（Ｄｉｓｔｒｉｂｕｔｅｄ　Ｆｅｅｄｂａｃｋ）レーザ等の半導体レーザを含む。第一駆動部１２は、制御部１６の制御下で、半導体レーザに電流を注入して発光させる。これにより、第一光源部１１において、半導体レーザは、ＦＭ変調光Ｌｆｍを生成し出射する。ＦＭ変調光Ｌｆｍは、所定の中心周波数ｆｃを有し、所定の変調周波数ｆｍで周波数変調されている。なお、ＦＭ変調光Ｌｆｍは連続光でもパルス光でも構わない。変調周波数ｆｍは適宜適切な値（例えば、１０ｋＨｚ，５０ｋＨｚ，１００ｋＨｚ）に設定される。中心周波数ｆｃは、被検出ガスの光吸収スペクトルにおける吸収線の周波数であり、被検出ガスの種類により定まる（下表１を参照）。なお、下表１では、便宜上、中心周波数ｆｃに相当する波長が示されている。例えば、被検出ガスがメタンであれば、中心周波数ｆｃは、例えばＲ（３）線の波長１．６５４μｍに相当する周波数に設定される。 The first light source unit 11 includes a semiconductor laser such as a DFB (Distributed Feedback) laser. The first drive unit 12 injects current into the semiconductor laser to emit light under the control of the control unit 16. Thus, in the first light source unit 11, the semiconductor laser generates and emits FM modulated light Lfm. The FM modulated light Lfm has a predetermined center frequency fc and is frequency-modulated with a predetermined modulation frequency fm. The FM modulated light Lfm may be continuous light or pulsed light. The modulation frequency fm is appropriately set to an appropriate value (for example, 10 kHz, 50 kHz, 100 kHz). The center frequency fc is the frequency of the absorption line in the light absorption spectrum of the gas to be detected, and is determined by the type of the gas to be detected (see Table 1 below). In Table 1, the wavelength corresponding to the center frequency fc is shown for convenience. For example, if the gas to be detected is methane, the center frequency fc is set to a frequency corresponding to the wavelength of 1.654 μm of the R (3) line, for example.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　第一光源部１１で生成されたＦＭ変調光Ｌｆｍは、監視領域Ａに向けて出射される。監視領域Ａに被検出ガスＧが存在する場合、ＦＭ変調光Ｌｆｍは、被検出ガスＧで吸収されて被検出ガスＧの濃度に応じて減衰する。また、被検出ガスＧは固有の光吸収スペクトルを持つため、ＦＭ変調光Ｌｆｍには所定次数の高調波成分（被検出ガスＧがメタンの場合、例えば二次の高調波成分）が生じる。このようなＦＭ変調光Ｌｆｍは、被検出ガスＧ以外の他の物体での散乱（反射）等を経て、第一受光部１３に入射される。本実施形態では、第一受光部１３への入射光を第一戻り光Ｌｒ１という。 The FM modulated light Lfm generated by the first light source unit 11 is emitted toward the monitoring area A. When the detection gas G exists in the monitoring region A, the FM modulated light Lfm is absorbed by the detection gas G and attenuates according to the concentration of the detection gas G. Further, since the detected gas G has a unique light absorption spectrum, a harmonic component of a predetermined order is generated in the FM modulated light Lfm (for example, when the detected gas G is methane, a second-order harmonic component). Such FM modulated light Lfm is incident on the first light receiving unit 13 after being scattered (reflected) by an object other than the gas G to be detected. In the present embodiment, the light incident on the first light receiving unit 13 is referred to as first return light Lr1.
　ところで、第一光源部１１と第一受光部１３との間の光路上には、図２に示すように、被検出ガスＧ以外の物体Ｏが存在することがある。物体Ｏは、光路上に存在しうるガラスや光学部品等である。このような物体Ｏに第一光源部１１からのＦＭ変調光Ｌｆｍが入射されると、外部との界面での干渉（エタロンフリンジ等）により光路雑音Ｌｎ（所定次数の高調波成分）が生じることがある。なお、図２の楕円内には、破線によりＦＭ変調光Ｌｆｍを示し、一点鎖線により光路雑音Ｌｎを示している。 Incidentally, an object O other than the gas to be detected G may exist on the optical path between the first light source unit 11 and the first light receiving unit 13 as shown in FIG. The object O is glass, an optical component, or the like that can exist on the optical path. When FM modulated light Lfm from the first light source unit 11 is incident on such an object O, optical path noise Ln (a harmonic component of a predetermined order) is generated due to interference (etalon fringe, etc.) at the interface with the outside. There is. In the ellipse in FIG. 2, the FM modulated light Lfm is indicated by a broken line, and the optical path noise Ln is indicated by an alternate long and short dash line.
　従来のガス検知装置は、被検出ガスＧでの吸収により生じた所定次数の高調波成分が第一戻り光Ｌｒ１に重畳されているのか、それとも、光路雑音Ｌｎが第一戻り光Ｌｒ１に重畳されているのかを判断していなかった。それゆえ、従来のガス検知装置は、この光路雑音Ｌｎを被検出ガスＧで生じた所定次数の高調波成分と誤認して、被検出ガスＧの濃度算出をすることがあった。 In the conventional gas detection device, a harmonic component of a predetermined order generated by absorption in the detection gas G is superimposed on the first return light Lr1, or the optical path noise Ln is superimposed on the first return light Lr1. I did not judge whether or not. Therefore, the conventional gas detection device sometimes miscalculates the optical path noise Ln as a harmonic component of a predetermined order generated in the detected gas G and calculates the concentration of the detected gas G.
　ここで、再度図１を参照する。被検出ガスがメタンの場合には、第一受光部１３は、例えばＩｎＧａＡｓフォトダイオードである。このような第一受光部１３は、第一戻り光Ｌｒ１が入射されると光電変換を行って、その光量に相関する第一電気信号Ｓｅ１を生成し出力する。第一受光部１３の出力信号Ｓｅ１は二分岐され、一方は第一位相差検出部１４に、他方は第一導出部１５に入力される。 Here, refer to FIG. 1 again. When the gas to be detected is methane, the first light receiving unit 13 is, for example, an InGaAs photodiode. The first light receiving unit 13 performs photoelectric conversion when the first return light Lr1 is incident, and generates and outputs a first electric signal Se1 correlated with the light amount. The output signal Se1 of the first light receiving unit 13 is branched into two, one being input to the first phase difference detecting unit 14 and the other being input to the first deriving unit 15.
　第一位相差検出部１４は、入力信号Ｓｅ１に対してフーリエ変換（具体的にはＦＦＴ（Ｆａｓｔ　Ｆｏｕｒｉｅｒ　Ｔｒａｎｓｆｏｒｍ））を行って、入力信号Ｓｅ１に含まれる基本波成分の位相に対する、同信号Ｓｅ１に含まれる所定次数の高調波成分（例えば二次高調波）の位相の差Δφ１を求める。第一位相差検出部１４は、求めた位相差Δφ１を制御部１６に出力する。 The first phase difference detection unit 14 performs Fourier transform (specifically, FFT (Fast Fourier Transform)) on the input signal Se1, and converts the signal Se1 to the phase of the fundamental wave component included in the input signal Se1. A phase difference Δφ1 of a harmonic component (for example, second harmonic) of a predetermined order included is obtained. The first phase difference detection unit 14 outputs the obtained phase difference Δφ1 to the control unit 16.
　第一導出部１５は、所謂２ｆ検波法により、入力信号Ｓｅ１に基づき、被検出ガスＧの濃度に相関する値Ｖｄを求める。なお、２ｆ検波法は周知であるため、その詳細な説明を省略するが、詳細に関しては例えば特許文献１を参照されたい。 The first deriving unit 15 obtains a value Vd that correlates with the concentration of the detected gas G based on the input signal Se1 by a so-called 2f detection method. Since the 2f detection method is well known, detailed description thereof will be omitted, but for details, see, for example, Patent Document 1.
　制御部１６は、図３に示すように、入出力インタフェイス部（以下、入出力ＩＦ部という）１６１と、コンピュータ装置の典型例としてのＣＰＵ１６２と、不揮発性メモリ１６３と、メインメモリ１６４と、を備えている。 As shown in FIG. 3, the control unit 16 includes an input / output interface unit (hereinafter referred to as an input / output IF unit) 161, a CPU 162 as a typical example of a computer device, a nonvolatile memory 163, a main memory 164, It has.
　入出力ＩＦ部１６１は、周辺の各構成１２，１７，１８に対し各種信号や各種データを送信したり、周辺の各構成１４，１５から各種データを受け取ったりする。 The input / output IF unit 161 transmits various signals and various data to the peripheral components 12, 17, and 18, and receives various data from the peripheral components 14 and 15.
　ＣＰＵ１６２は、不揮発性メモリ１６３に予め格納されているプログラムＰを、メインメモリ１６４を作業領域として用いて実行することで、判断部１６５、濃度算出部１６６、表示制御部１６７および報知制御部１６８として機能する。これら機能ブロック１６５～１６８については後で詳説する。 The CPU 162 executes the program P stored in advance in the non-volatile memory 163 by using the main memory 164 as a work area, so that the determination unit 165, the concentration calculation unit 166, the display control unit 167, and the notification control unit 168 are performed. Function. These functional blocks 165 to 168 will be described in detail later.
　表示装置１７は、例えば液晶ディスプレイであって、被検出ガスＧの濃度や、被検出ガスＧを検出できなかったこと等を示す画像を表示する。 The display device 17 is a liquid crystal display, for example, and displays an image indicating the concentration of the gas to be detected G, the gas to be detected G not being detected, and the like.
　報知装置１８は、例えばスピーカであって、被検出ガスＧを検出しなかったこと、または、戻り光には被検出ガスＧでの吸収が生じていないこと、を示す音声を出力する。 The notification device 18 is a speaker, for example, and outputs a sound indicating that the detected gas G has not been detected or that the return light has not been absorbed by the detected gas G.
≪１－２．ガス検知装置１の動作≫
　次に、図４等を参照して、ガス検知装置１の動作について詳説する。 << 1-2. Operation of Gas Detector 1 >>
Next, with reference to FIG. 4 etc., operation | movement of the gas detection apparatus 1 is explained in full detail.
　図４のステップＳ０１において、ＣＰＵ１６２は、第一光源部１１の半導体レーザに注入電流を供給するように第一駆動部１２に対し指示を行う。その結果、第一光源部１１からはＦＭ変調光Ｌｆｍが監視領域Ａに向けて出射される。 4, the CPU 162 instructs the first drive unit 12 to supply an injection current to the semiconductor laser of the first light source unit 11. As a result, FM modulated light Lfm is emitted from the first light source unit 11 toward the monitoring region A.
　ＦＭ変調光Ｌｆｍの一部は、被検出ガスＧで吸収されたり、それ以外の物体Ｏで散乱したりする等して、第一戻り光Ｌｒ１として第一受光部１３に入射される。ステップＳ０２において、第一受光部１３は、前述したとおり、第一戻り光Ｌｒ１に基づき第一電気信号Ｓｅ１を生成して、第一位相差検出部１４および第一導出部１５に出力する。 Part of the FM modulated light Lfm is incident on the first light receiving unit 13 as the first return light Lr1 by being absorbed by the detection gas G or being scattered by the other object O. In step S02, as described above, the first light receiving unit 13 generates the first electric signal Se1 based on the first return light Lr1, and outputs the first electric signal Se1 to the first phase difference detection unit 14 and the first derivation unit 15.
　ステップＳ０３において、第一位相差検出部１４は、前述したとおり、第一受光部１３の出力信号Ｓｅ１に基づき位相差Δφ１を求めて制御部１６に出力する。 In step S03, the first phase difference detection unit 14 obtains the phase difference Δφ1 based on the output signal Se1 of the first light receiving unit 13 and outputs it to the control unit 16 as described above.
　ここで、被検出ガスＧの光吸収スペクトルは既知であることから、被検出ガスＧでの吸収によりＦＭ変調光Ｌｆｍに所定次数（例えば二次）の高調波成分が生じている場合、基本波成分に対するこの高調波成分の位相差Δφ１は実験等で予め求めることが出来る。実験により予め求めておいた位相差Δφ１が基準値ＶｒｅｆとしてプログラムＰに予め記述されている。ＣＰＵ１６２は、ステップＳ０４において、判断部１６５として機能し、予め記述された基準値Ｖｒｅｆと、第一位相差検出部１４から入力された位相差Δφ１が同じか許容範囲内か否かを判断する。 Here, since the light absorption spectrum of the gas to be detected G is known, when a harmonic component of a predetermined order (for example, second order) is generated in the FM modulated light Lfm due to absorption by the gas to be detected G, the fundamental wave The phase difference Δφ1 of the harmonic component with respect to the component can be obtained in advance by experiments or the like. The phase difference Δφ1 obtained in advance by experiments is described in advance in the program P as the reference value Vref. In step S04, the CPU 162 functions as the determination unit 165, and determines whether the reference value Vref described in advance and the phase difference Δφ1 input from the first phase difference detection unit 14 are the same or within an allowable range.
　肯定判断を行った場合、判断部１６５としてのＣＰＵ１６２は、ステップＳ０５において、第一戻り光Ｌｒ１に被検出ガスＧでの吸収による所定次数の高調波成分が重畳されているとみなして、第一導出部１５に相関値Ｖｄを求めて返すように指示する。 If an affirmative determination is made, the CPU 162 as the determination unit 165 considers that a harmonic component of a predetermined order due to absorption in the detected gas G is superimposed on the first return light Lr1 in step S05, and the first The derivation unit 15 is instructed to obtain and return the correlation value Vd.
　ステップＳ０６において、第一導出部１５は、判断部１６５の指示に応答して、前述したとおり、被検出ガスＧの濃度との相関値Ｖｄを求めて、濃度算出部１６６としてのＣＰＵ１６２に返す。 In step S06, the first deriving unit 15 obtains the correlation value Vd with the concentration of the detected gas G as described above in response to the instruction of the determining unit 165, and returns it to the CPU 162 as the concentration calculating unit 166.
　ステップＳ０７において、濃度算出部１６６は、受け取った相関値Ｖｄに対し、予め定められた比例乗数αを乗算して、被検出ガスＧの濃度を求めて、表示制御部１６７としてのＣＰＵ１６２に渡す。 In step S07, the concentration calculation unit 166 multiplies the received correlation value Vd by a predetermined proportional multiplier α to obtain the concentration of the detected gas G, and passes it to the CPU 162 as the display control unit 167.
　ステップＳ０８において、表示制御部１６７は、被検出ガスＧの濃度を示す画像データＩｄを生成した後、表示装置１７に転送する。表示装置１７は、受信した画像データＩｄに従って被検出ガスＧの濃度を表示する。 In step S08, the display control unit 167 generates image data Id indicating the concentration of the gas G to be detected, and then transfers the image data Id to the display device 17. The display device 17 displays the concentration of the detected gas G according to the received image data Id.
　また、もしステップＳ０４において否定判断を行った場合、判断部１６５としてのＣＰＵ１６２は、ステップＳ０９において、第一戻り光Ｌｒ１に光路雑音Ｌｎが重畳されているとみなして、第一導出部１５に相関値Ｖｄを求めないように指示する。これに加えて、判断部１６５は、音声データＩｓを生成するように報知制御部１６８に指示する。 If a negative determination is made in step S04, the CPU 162 as the determination unit 165 regards that the optical path noise Ln is superimposed on the first return light Lr1 in step S09, and correlates with the first deriving unit 15. Instructs not to obtain the value Vd. In addition, the determination unit 165 instructs the notification control unit 168 to generate the audio data Is.
　ステップＳ０１０において、報知制御部１６８は、被検出ガスＧを検出しなかったこと、または第一戻り光Ｌｒ１に光路雑音Ｌｎが重畳されていることを示す音声データＩｓを生成して、報知装置１８に転送する。報知装置１８は、受信した音声データＩｓに従って、被検出ガスＧを検出しなかったこと、または第一戻り光Ｌｒ１に光路雑音Ｌｎが重畳されていることを音声出力することでユーザに報知する。 In step S010, the notification control unit 168 generates audio data Is indicating that the gas to be detected G has not been detected or that the optical path noise Ln is superimposed on the first return light Lr1, and the notification device 18 Forward to. The notification device 18 notifies the user that the detected gas G has not been detected or that the optical path noise Ln is superimposed on the first return light Lr1 by voice output according to the received voice data Is.
≪１－３．効果≫
　以上説明した通り、本実施形態に係るガス検知装置１によれば、第一位相差検出部１４で生成された位相差Δφ１に基づき、判断部１６５は、第一受光部１３で受信した第一戻り光Ｌｒ１に被検出ガスＧに起因する所定次数の高調波成分が重畳されているか否かを判断する。判断部１６５が肯定判断を行うと、第一導出部１５で求めた相関値Ｖｄに基づき、濃度算出部１６６は被検出ガスＧの濃度を算出する。それに対し、判断部１６５が否定判断を行うと、濃度算出部１６６は被検出ガスＧの濃度を算出しない。このように、本実施形態によれば、第一位相差検出部１４および判断部１６５をガス検知装置１に設けたことにより、第一戻り光Ｌｒ１に重畳されたものが被検出ガスＧに起因する所定次数の高調波成分か光路雑音Ｌｎかを正確に識別可能となる。上記に加え、被検出ガスＧの濃度を誤検出する可能性も低減させることが可能となる。 << 1-3. Effect >>
As described above, according to the gas detection device 1 according to the present embodiment, the determination unit 165 receives the first light received by the first light receiving unit 13 based on the phase difference Δφ1 generated by the first phase difference detection unit 14. It is determined whether or not a harmonic component of a predetermined order due to the detected gas G is superimposed on the return light Lr1. If the determination unit 165 makes an affirmative determination, the concentration calculation unit 166 calculates the concentration of the detected gas G based on the correlation value Vd obtained by the first derivation unit 15. On the other hand, if the determination unit 165 makes a negative determination, the concentration calculation unit 166 does not calculate the concentration of the detected gas G. As described above, according to the present embodiment, the first phase difference detection unit 14 and the determination unit 165 are provided in the gas detection device 1, so that what is superimposed on the first return light Lr 1 is caused by the detected gas G. It is possible to accurately identify the harmonic component of the predetermined order or the optical path noise Ln. In addition to the above, the possibility of erroneous detection of the concentration of the gas G to be detected can be reduced.
≪１－４．付記≫
　なお、上記実施形態では、第一光源部１１は、直接変調方式でＦＭ変調光Ｌｆｍを生成するとして説明したが、第一光源部１１は、外部変調方式によりＦＭ変調光Ｌｆｍを生成しても構わない。この場合、第一光源部１１は、例えば半導体レーザと外部変調器とを含む。 << 1-4. Appendix >>
In the above embodiment, the first light source unit 11 has been described as generating the FM modulated light Lfm by the direct modulation method. However, the first light source unit 11 may generate the FM modulated light Lfm by the external modulation method. I do not care. In this case, the first light source unit 11 includes, for example, a semiconductor laser and an external modulator.
　また、上記実施形態では、被検出ガスＧを検出しなかったこと、または第一戻り光Ｌｒ１に光路雑音Ｌｎが重畳されていることは音声によりユーザに報知されていた。しかし、これに限らず、これらを表示装置１７に表示することでユーザに通知されても構わない。この場合、表示装置１７が報知装置１８となる。 In the above embodiment, the user is notified by voice that the gas to be detected G has not been detected or that the optical path noise Ln is superimposed on the first return light Lr1. However, the present invention is not limited to this, and the user may be notified by displaying them on the display device 17. In this case, the display device 17 becomes the notification device 18.
≪２．第二実施形態≫
　次に、図５以降を参照して、第二実施形態に係るガス検知装置１Ａおよびガス検知方法を詳説する。 ≪2. Second embodiment >>
Next, with reference to FIG. 5 and subsequent figures, the gas detector 1A and the gas detection method according to the second embodiment will be described in detail.
≪２－１．ガス検知装置１Ａの構成≫
　図５において、ガス検知装置１Ａは、図１のガス検知装置１と比較すると、偏向／透過部２１と、収容部２２と、第二受光部２３と、第二位相差検出部２４と、をさらに備える点で相違する。それ以外に、両ガス検知装置１，１Ａの間に構成面での相違点は無い。それ故、図５において、図１の構成に相当するものには同一参照符号を付け、それぞれの説明を省略する。 << 2-1. Configuration of Gas Detector 1A >>
In FIG. 5, the gas detection device 1 </ b> A includes a deflection / transmission unit 21, a storage unit 22, a second light receiving unit 23, and a second phase difference detection unit 24 compared to the gas detection device 1 of FIG. Furthermore, it differs in the point provided. Other than that, there is no structural difference between the gas detectors 1 and 1A. Therefore, in FIG. 5, the same reference numerals are assigned to the components corresponding to the configuration of FIG.
　偏向／透過部２１は、例えばハーフミラーであって、第一光源部１１からのＦＭ変調光Ｌｆｍの光路上であって第一光源部１１の直ぐ近くに配置される。より詳細には、第一光源部１１と偏向／透過部２１との間に、被検出ガスＧやそれ以外の物体Ｏが存在しないように、両者は近接配置される。 The deflection / transmission unit 21 is a half mirror, for example, and is disposed on the optical path of the FM modulated light Lfm from the first light source unit 11 and in the immediate vicinity of the first light source unit 11. More specifically, the first light source unit 11 and the deflecting / transmitting unit 21 are disposed close to each other so that the gas G to be detected and the other object O do not exist.
　以上のように配置された偏向／透過部２１は、第一光源部１１から出射されたＦＭ変調光Ｌｆｍの一部を収容部２２に向けて偏向するとともに、ＦＭ変調光Ｌｆｍの残りを監視領域Ａに向けて透過する。 The deflecting / transmitting unit 21 arranged as described above deflects a part of the FM modulated light Lfm emitted from the first light source unit 11 toward the accommodating unit 22 and also monitors the remainder of the FM modulated light Lfm as a monitoring region. It penetrates toward A.
　収容部２２は、所謂サンプルガスセルであって、被検出ガスＧと同種のガスを基準ガスＧｒｅｆとして収容する容器である。上記偏向／透過部２１からのＦＭ変調光Ｌｆｍが基準ガスＧｒｅｆを透過するように、収容部２２は、赤外透過性の入射側窓部と出射側窓部とを有する。 The accommodating part 22 is a so-called sample gas cell, and is a container that accommodates the same type of gas as the gas G to be detected as the reference gas Gref. The accommodating part 22 has an infrared transmitting incident side window part and an emitting side window part so that the FM modulated light Lfm from the deflecting / transmitting part 21 transmits the reference gas Gref.
　以上の収容部２２において、偏向／透過部２１からのＦＭ変調光Ｌｆｍは入射側窓部から入射され、内部の基準ガスＧｒｅｆで吸収されつつ出射側窓部から、後段の第二受光部２３に向けて出射される。本実施形態では、第二受光部２３への入射光を第二戻り光Ｌｒ２という。 In the storage unit 22 described above, the FM modulated light Lfm from the deflecting / transmitting unit 21 is incident from the incident side window portion and is absorbed by the internal reference gas Gref, and then is emitted from the emission side window portion to the second light receiving unit 23 at the subsequent stage. It is emitted toward. In the present embodiment, the light incident on the second light receiving unit 23 is referred to as second return light Lr2.
　第二受光部２３は、例えばＳｉフォトダイオードである。このような第二受光部２３は、第二戻り光Ｌｒ２が入射されると光電変換を行って、その光量に相関する第二電気信号Ｓｅ２を生成し出力する。第二受光部２３の出力信号Ｓｅ２は第二位相差検出部２４に入力される。 The second light receiving unit 23 is, for example, a Si photodiode. The second light receiving unit 23 performs photoelectric conversion when the second return light Lr2 is incident, and generates and outputs a second electric signal Se2 correlated with the light amount. The output signal Se <b> 2 from the second light receiving unit 23 is input to the second phase difference detection unit 24.
　第二位相差検出部２４は、入力信号Ｓｅ２に対してフーリエ変換（具体的にはＦＦＴ）を行って、入力信号Ｓｅ２に含まれる基本波成分の位相に対する、同信号Ｓｅ２に含まれる所定次数の高調波成分（例えば二次高調波）の位相の差（以下、第二位相差という）Δφ２を求める。第二位相差検出部２４は、求めた第二位相差Δφ２を制御部１６に出力する。 The second phase difference detection unit 24 performs Fourier transform (specifically, FFT) on the input signal Se2, and has a predetermined order included in the signal Se2 with respect to the phase of the fundamental wave component included in the input signal Se2. A phase difference (hereinafter referred to as a second phase difference) Δφ2 of a harmonic component (for example, a second harmonic) is obtained. The second phase difference detection unit 24 outputs the obtained second phase difference Δφ2 to the control unit 16.
≪２－２．ガス検知装置１Ａの動作≫
　次に、図６等を参照して、ガス検知装置１Ａの動作について説明する。 << 2-2. Operation of Gas Detector 1A >>
Next, with reference to FIG. 6 etc., operation | movement of 1 A of gas detection apparatuses is demonstrated.
　図６のステップＳ１１において、ＣＰＵ１６２は、図４のステップＳ０１と同様にして、第一光源部１１からＦＭ変調光Ｌｆｍを出射させる。このＦＭ変調光Ｌｆｍは、偏向／透過部２１にて二分岐され、一方は収容部２２に向けて偏向され、他方は監視領域Ａに向けて透過される。 6, the CPU 162 emits the FM modulated light Lfm from the first light source unit 11 in the same manner as in step S01 of FIG. 4. The FM modulated light Lfm is bifurcated by the deflection / transmission unit 21, one is deflected toward the accommodation unit 22, and the other is transmitted toward the monitoring region A.
　ＦＭ変調光Ｌｆｍの他方は、被検出ガスＧで吸収されたり、それ以外の物体Ｏで散乱したりする等して、第一戻り光Ｌｒ１として第一受光部１３に入射される。ステップＳ１２において、第一受光部１３は、前述したとおり、第一戻り光Ｌｒ１に基づき第一電気信号Ｓｅ１を生成して、第一位相差検出部１４および第一導出部１５に出力する。 The other of the FM modulated light Lfm is incident on the first light receiving unit 13 as the first return light Lr1 by being absorbed by the gas G to be detected or scattered by the other object O. In step S12, as described above, the first light receiving unit 13 generates the first electric signal Se1 based on the first return light Lr1, and outputs the first electric signal Se1 to the first phase difference detecting unit 14 and the first deriving unit 15.
　上記に対し、ＦＭ変調光Ｌｆｍの一方は、収容部２２に収容された基準ガスＧｒｅｆを透過して、第二戻り光Ｌｒ２として第二受光部２３に入射される。ステップＳ１３において、第二受光部２３は、前述したとおり、第二戻り光Ｌｒ２に基づき第二電気信号Ｓｅ２を生成して、第二位相差検出部２４に出力する。 In contrast, one of the FM modulated light Lfm passes through the reference gas Gref stored in the storage unit 22 and is incident on the second light receiving unit 23 as the second return light Lr2. In step S <b> 13, as described above, the second light receiving unit 23 generates the second electric signal Se <b> 2 based on the second return light Lr <b> 2 and outputs it to the second phase difference detection unit 24.
　ステップＳ１４，Ｓ１５において、位相差検出部１４，２４は、前述の通り、受光部１３，２３の出力信号Ｓｅ１，Ｓｅ２に基づき位相差Δφ１，Δφ２を求め、制御部１６にそれぞれ出力する。 In steps S14 and S15, the phase difference detection units 14 and 24 obtain the phase differences Δφ1 and Δφ2 based on the output signals Se1 and Se2 of the light receiving units 13 and 23 and output them to the control unit 16 as described above.
　ここで、監視領域ＡにおいてＦＭ変調光Ｌｆｍが被検出ガスＧで吸収されていれば、被検出ガスＧと基準ガスＧｒｅｆとは同種であることから、被検出ガスＧでも基準ガスＧｒｅｆでもＦＭ変調光Ｌｆｍには同様の高調波成分が生じる。従って、位相差Δφ１は、Δφ２は同じか許容範囲内にある。ＣＰＵ１６２は、ステップＳ１６において、判断部１６５として機能し、両位相差Δφ１，Δφ２が同じか許容範囲内か否かを判断する。 Here, if the FM modulated light Lfm is absorbed by the gas to be detected G in the monitoring region A, the gas to be detected G and the reference gas Gref are of the same type, and therefore FM modulation is performed for both the gas to be detected G and the reference gas Gref. A similar harmonic component is generated in the light Lfm. Therefore, the phase difference Δφ1 is the same as Δφ2 or within an allowable range. In step S16, the CPU 162 functions as the determination unit 165 and determines whether or not both phase differences Δφ1 and Δφ2 are the same or within an allowable range.
　肯定判断を行った場合、ＣＰＵ１６２は、ステップＳ１７～Ｓ１１０において、図４のＳ０５～Ｓ０８と同様の手順で、表示装置１７に被検出ガスＧの濃度を表示させる。 When an affirmative determination is made, the CPU 162 displays the concentration of the detected gas G on the display device 17 in steps S17 to S110 in the same procedure as in S05 to S08 of FIG.
　また、もしステップＳ１６で否定判断を行った場合、ＣＰＵ１６２は、Ｓ１１１，Ｓ１１２において、ステップＳ０９，Ｓ０１０と同様にして、報知装置１８に、被検出ガスＧを検出しなかったこと等をユーザに報知する。 Further, if a negative determination is made in step S16, the CPU 162 notifies the user that the detected gas G has not been detected in the notification device 18 in the same manner as in steps S09 and S010 in S111 and S112. To do.
≪２－３．効果≫
　以上説明した通り、本実施形態に係るガス検知装置１Ａによれば、両位相差検出部１４，２４で生成された位相差Δφ１，Δφ２に基づき、判断部１６５は、第一実施形態と同様、第一受光部１３で受信した第一戻り光Ｌｒ１に被検出ガスＧに起因する所定次数の高調波成分が重畳されているか否かを判断する。よって、第１－３欄で述べた効果を、本実施形態に係るガス検知装置１Ａも奏することが出来る。 << 2-3. Effect >>
As described above, according to the gas detection device 1A according to the present embodiment, the determination unit 165 is based on the phase differences Δφ1 and Δφ2 generated by the phase difference detection units 14 and 24, as in the first embodiment. It is determined whether or not a harmonic component of a predetermined order due to the detected gas G is superimposed on the first return light Lr1 received by the first light receiving unit 13. Therefore, the effect described in the first to third columns can also be achieved by the gas detection device 1A according to the present embodiment.
≪２－４．付記≫
　なお、第１－４欄で記載した事項は、本実施形態でも適用可能である。 << 2-4. Appendix >>
Note that the items described in columns 1-4 can be applied to this embodiment.
　２０１６年１月１５日出願の特願２０１６－００６０６４の日本出願に含まれる明細書、図面および要約書の開示内容は、すべて本願に援用される。 The disclosure of the specification, drawings and abstract contained in the Japanese application of Japanese Patent Application No. 2016-006064 filed on Jan. 15, 2016 is incorporated herein by reference.
　本発明に係るガス検知装置およびガス検知方法は、被検出ガス濃度の誤検出を低減可能であり、ガスモニタ装置等に有用である。 The gas detection device and the gas detection method according to the present invention can reduce erroneous detection of the detected gas concentration and are useful for a gas monitor device and the like.
　１，１Ａ　ガス検知装置
　１１　第一光源部
　１３　第一受光部
　１４　第一位相差検出部
　１５　第一導出部
　１６　制御部
　１６５　判断部
　１６６　濃度算出部
　１７　表示装置
　１８　報知装置
　２１　偏向／透過部
　２２　収容部
　２３　第二受光部
　２４　第二位相検出部 DESCRIPTION OF SYMBOLS 1,1A Gas detection apparatus 11 1st light source part 13 1st light-receiving part 14 1st phase difference detection part 15 1st derivation | leading-out part 16 Control part 165 Judgment part 166 Concentration calculation part 17 Display apparatus 18 Notification apparatus 21 Deflection / transmission part 22 Housing part 23 Second light receiving part 24 Second phase detecting part

Claims (8)

  1. 　被検出ガスの吸収線の周波数を中心周波数とするＦＭ変調光であって、所定周波数で周波数変調されたＦＭ変調光を出射する光源部と、
    　前記ＦＭ変調光が前記被検出ガスで吸収された第一戻り光に基づき信号を出力する第一受光部と、
    　前記第一受光部の出力信号に含まれる基本波成分と高調波成分との位相差を第一位相差として検出する第一位相差検出部と、
    　を備えたガス検知装置。     A light source section that emits FM modulated light having a frequency centered on the frequency of the absorption line of the gas to be detected and modulated at a predetermined frequency;
    A first light-receiving unit that outputs a signal based on the first return light in which the FM modulated light is absorbed by the detection gas;
    A first phase difference detection unit that detects a phase difference between a fundamental wave component and a harmonic component contained in the output signal of the first light receiving unit as a first phase difference;
    Gas detector equipped with.
  2. 　前記第一位相差を用いて、前記第一戻り光に前記被検出ガスでの吸収に起因する高調波成分が重畳されているか否かを判断する判断部をさらに備え、
    　前記判断部は前記第一位相差を所定の基準値と比較することにより、前記第一戻り光に前記被検出ガスでの吸収に起因する高調波成分が重畳されているか否かを判断する、請求項１に記載のガス検知装置。     Using the first phase difference, further comprising a determination unit that determines whether or not a harmonic component resulting from absorption in the detected gas is superimposed on the first return light;
    The determination unit determines whether or not a harmonic component resulting from absorption in the detected gas is superimposed on the first return light by comparing the first phase difference with a predetermined reference value. The gas detection device according to claim 1.
  3. 　前記被検出ガスと同種の基準ガスを収容する収容部と、
    　前記光源部から出射されたＦＭ変調光の一部を前記基準ガスに向けて偏向するとともに、残りのＦＭ変調光を前記基準ガス以外に向けて出射する偏向／透過部と、
    　前記基準ガスで吸収された第二戻り光に基づき信号を出力する第二受光部と、
    　前記第二受光部の出力信号に含まれる基本波成分と高調波成分との位相差を第二位相差として検出する第二位相差検出部と、
    　前記第一位相差を用いて、前記第一戻り光に前記被検出ガスでの吸収に起因する高調波成分が重畳されているか否かを判断する判断部と、をさらに備え、
    　前記判断部は、前記第一位相差に加え前記第二位相差をさらに用いて、前記第一戻り光に前記被検出ガスでの吸収に起因する高調波成分が重畳されているか否かを判断する、請求項１に記載のガス検知装置。     An accommodating portion for accommodating a reference gas of the same type as the detected gas;
    A deflection / transmission unit that deflects a part of the FM modulated light emitted from the light source unit toward the reference gas and emits the remaining FM modulated light toward other than the reference gas;
    A second light receiving unit that outputs a signal based on the second return light absorbed by the reference gas;
    A second phase difference detection unit that detects a phase difference between a fundamental wave component and a harmonic component contained in the output signal of the second light receiving unit as a second phase difference;
    A determination unit that determines whether or not a harmonic component resulting from absorption in the detected gas is superimposed on the first return light using the first phase difference; and
    The determination unit further uses the second phase difference in addition to the first phase difference to determine whether or not a harmonic component resulting from absorption in the detected gas is superimposed on the first return light. The gas detection device according to claim 1.
  4. 　前記第一受光部の出力信号に基づき、前記被検出ガスの濃度に相関する値を求める第一導出部と、
    　前記判断部が肯定判断をすると、前記第一導出部が求めた値に基づき、前記被検出ガスの濃度を求める濃度算出部と、をさらに備える請求項２または３に記載のガス検知装置。     A first deriving unit for obtaining a value correlated with the concentration of the detected gas based on the output signal of the first light receiving unit;
    The gas detection device according to claim 2, further comprising: a concentration calculation unit that calculates a concentration of the detection target gas based on a value obtained by the first deriving unit when the determination unit makes an affirmative determination.
  5. 　前記判断部が否定判断をすると、前記被検出ガスを検出しなかったこと、または、前記戻り光において前記被検出ガスで吸収が生じていないこと、を報知する報知手段をさらに備える、請求項２～４のいずれかに記載のガス検知装置。 3. The information processing apparatus according to claim 2, further comprising notification means for notifying that the gas to be detected has not been detected or that no absorption has occurred in the gas to be detected in the return light when the determination unit makes a negative determination. 5. The gas detection device according to any one of 4 to 4.
  6. 　前記第一位相差検出部は、前記第一受光部の出力信号をフーリエ変換することで前記位相差を検出する、請求項１または２に記載のガス検知装置。 The gas detection device according to claim 1 or 2, wherein the first phase difference detection unit detects the phase difference by performing a Fourier transform on an output signal of the first light receiving unit.
  7. 　前記第一位相差検出部および前記第二位相差検出部は、前記第一受光部および前記第二受光部の出力信号をフーリエ変換することで前記位相差を検出する、請求項３に記載のガス検知装置。 The said 1st phase difference detection part and said 2nd phase difference detection part detect the said phase difference by Fourier-transforming the output signal of a said 1st light-receiving part and a said 2nd light-receiving part. Gas detector.
  8. 　被検出ガスの吸収線の周波数を中心周波数とするＦＭ変調光であって、所定周波数で周波数変調されたＦＭ変調光を出射する第一ステップと、
    　前記ＦＭ変調光が前記被検出ガスで吸収された第一戻り光に基づき信号を出力する第一受光ステップと、
    　前記第一受光ステップの出力信号に含まれる基本波成分と高調波成分との位相差を第一位相差として検出する第一位相差検出ステップと、を備えたガス検知方法。     A first step of emitting FM modulated light having a frequency centered on the frequency of the absorption line of the gas to be detected and modulated at a predetermined frequency;
    A first light receiving step for outputting a signal based on the first return light absorbed by the gas to be detected, the FM modulated light;
    A gas detection method comprising: a first phase difference detection step of detecting a phase difference between a fundamental wave component and a harmonic component contained in an output signal of the first light receiving step as a first phase difference.
PCT/JP2017/000579 2016-01-15 2017-01-11 Gas detecting device and gas detecting method WO2017122659A1 (en)

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