WO2020225977A1 - Non-dispersive infrared gas detection device - Google Patents

Non-dispersive infrared gas detection device Download PDF

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Publication number
WO2020225977A1
WO2020225977A1 PCT/JP2020/011048 JP2020011048W WO2020225977A1 WO 2020225977 A1 WO2020225977 A1 WO 2020225977A1 JP 2020011048 W JP2020011048 W JP 2020011048W WO 2020225977 A1 WO2020225977 A1 WO 2020225977A1
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Prior art keywords
light
light receiving
light source
receiving element
substrate
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PCT/JP2020/011048
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French (fr)
Japanese (ja)
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創一朗 酒井
圭太 吉元
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フィガロ技研株式会社
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Publication of WO2020225977A1 publication Critical patent/WO2020225977A1/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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • 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
    • G01N21/59—Transmissivity
    • G01N21/61—Non-dispersive gas analysers

Definitions

  • the present invention relates to a non-dispersive infrared gas detector (NDIR).
  • NDIR non-dispersive infrared gas detector
  • a light source and a light receiving element are arranged on a substrate, and these are covered with a multiple reflection type optical cell to guide infrared light from the light source to the light receiving element.
  • the gas sensitivity is increased by multiple reflection.
  • the light receiving element the light receiving surface is often arranged at right angles to the substrate. Therefore, the side surface of the light receiving element is positioned on the substrate, which makes it difficult to attach the light receiving element.
  • Patent Document 1 proposes to combine two parabolic mirrors to improve the efficiency of light utilization.
  • An object of the present invention is to increase the ratio of light from a light source reaching a light receiving element and to enable the light receiving surface of the light receiving element to be arranged parallel to the main surface of the substrate.
  • the non-dispersive infrared gas detector of the present invention comprises a substrate on which a light source and at least one light receiving element are mounted on a main surface so as to face each other. It includes an optical cell that houses a light source and a light receiving element, and is positioned with respect to a substrate.
  • the surface of the optical cell in contact with the main surface of the substrate is set as a virtual bottom surface, and the inner surface of the optical cell opposite to the main surface is used as a ceiling surface.
  • At least the light source side end of the inner surface of the optical cell constitutes a light source side mirror that focuses on the light source.
  • At least the light receiving side end of the inner surface of the optical cell constitutes a light receiving side mirror focusing on the light receiving element.
  • the light receiving element is lower in height from the main surface than the light source, and the light receiving element is mounted on the substrate so that the light receiving surface is parallel to the main surface.
  • the light source side mirror is configured to make as much light as possible incident on the light receiving side mirror. Since the light receiving element is located at the focal point of the light receiving side mirror, the light incident on the light receiving side mirror changes its direction and is incident on the light receiving element on the main surface of the substrate. In the present invention, since the light receiving surface of the light receiving element is parallel to the main surface of the substrate, the light receiving element can be easily attached to the substrate. On the other hand, when the side surface of the light receiving element is attached to the substrate and the light receiving surface faces the light source, the amount of light received varies due to the fluctuation of the attachment angle of the light receiving element.
  • both the light source side mirror and the light receiving side mirror have a parabolic shape and have a common optical axis. Then, the light of the light source is reflected by the mirror on the light source side and is incident on the mirror on the light receiving side in parallel with the optical axis of the mirror on the light receiving side, so that the proportion of light incident on the light receiving element increases.
  • a pair of light receiving side mirrors are provided in the optical cell so that the light receiving elements are attached to the pair of substrates and each light receiving element is focused.
  • neither the light source side mirror nor the light receiving side mirror is a pure paraboloid, and includes a bipolar surface (a figure in which the bipolar line is rotated about an axis passing through the focal point) or a rotating ellipsoid in addition to the paraboloid. Mirrors are preferred.
  • the curvature at each position of the light source side mirror and the light receiving side mirror is changed according to the optical path, and as much light as possible is incident on the light receiving element. Then, for example, one light receiving element is used for gas detection, and the other light receiving element is used for reference.
  • a light source side mirror and a light receiving side mirror are provided so as to extend to the ceiling surface, the amount of light reaching the light receiving element increases.
  • the height of the optical cell increases. Therefore, it is preferable to use a flat mirror whose ceiling surface is parallel to the main surface to limit the height of the optical cell. A part of the light from the light source is reflected by the ceiling surface on a flat surface, enters the mirror on the light receiving side, and reaches the light receiving element.
  • the optical cell is shown by a chain line in the plan view of the non-dispersive gas detector (NDIR) of the embodiment. 11-11 direction sectional view of FIG. 111-111 direction sectional view of FIG. Bottom view of the optical cell of the embodiment Circuit diagram of the non-dispersive gas detector of the embodiment
  • FIGS. 1 to 5 show the non-dispersive infrared gas detector (NDIR) 2 of the embodiment.
  • the circuit board 4 of NDIR2 the light source 8, and the photodiodes 11 and 12 are shown by solid lines, and the optical cell (cell) 6 is shown by a chain line.
  • a light source 8 and, for example, a pair of photodiodes 11 and 12 are arranged on the main surface 5 of the circuit board 4 so as to face each other along the longitudinal direction of the substrate 4.
  • Photodiodes 11 and 12 are diodes that are sensitive to infrared light such as In-Sb systems, and may be other light receiving elements such as pyroelectric elements.
  • the diodes 11 and 12 are the same as the diodes, and bandpass filters (filters) 13 and 14 having different transmission wavelengths are attached to the light receiving surfaces of the diode 11 for detection and the diode 12 for reference.
  • the light receiving surface is the surface of the diodes 11 and 12 and the bottom surface of the filters 13 and 14.
  • the light receiving surface is parallel to the main surface 5 of the substrate 4, and the bottom surfaces of the diodes 11 and 12 are fixed to the substrate 4 by soldering or the like.
  • the light source 8 is attached to the substrate 4 via the holder 10, and the types of the light source 8 are a coiled heater, a MEMS micro hot plate, an LED, and the like.
  • the gas to be detected is arbitrary, such as CO2 and methane.
  • Cell 6 is fixed to the circuit board 4 so that the bottom surface 20 is in contact with the main surface 5.
  • 22 is the ceiling surface of cell 6, which is a flat mirror, parallel to the main surface 5.
  • a light source side mirror 24 is provided on the inner surface of the cell 6 at the end or side of the light source 8 side.
  • a pair of light-receiving side mirrors 25, 25 are provided at the end or side of the photodiodes 11 and 12 on the inner surface of the cell 6, and the number of light-receiving side mirrors 25 and 25 is the number of light-receiving elements (photodiodes) 11,12. equal.
  • a space 28 for a light source for accommodating the holder 10 is provided, and the cell 6 is solid up to the intermediate surface 29 between the light source side mirrors 24 and the light source side mirrors 25 and 25 and the bottom surface 20.
  • the side surface in the cell 6 between the light source side mirror 24 and the light receiving side mirrors 25 and 25 is referred to as the side surface 26.
  • circuit components other than the light source 8 are housed in the space between the intermediate surface 29 and the main surface 5.
  • 30 and 30 are, for example, a pair of ventilation holes, and introduce surrounding gas into the cell 6. The arrangement, number, etc. of the ventilation holes 30 are arbitrary.
  • the direction facing the ceiling surface 22 at right angles to the main surface 5 is the height direction
  • the long side direction of the main surface 5 and the cell 6 is the length direction
  • the short side direction of the main surface 5 and the cell 6 is the width.
  • the light source 8 is located higher than the light receiving surfaces of the photodiodes 11 and 12, and there is a gap between the light source 8 and the main surface 5.
  • the side surface 26 is perpendicular to the main surface 5, and the bottom surface 20 and the intermediate surface 29 are parallel to the main surface 5.
  • the focal point F1 of the light source side mirror 24 is in the light source 8.
  • the focal points F2 and F3 of the light receiving side mirrors 25 and 25 are on the light receiving surfaces of the diodes 11 and 12.
  • the light source side mirror 24 and the light source side mirrors 25 and 25 are located at the end or side of the inner surface of the cell 6, and the ceiling surface 22 and the intermediate surface 29 are flat surfaces.
  • the light receiving side mirrors 25 and 25 condense the light directly emitted from the light source 8, the light reflected by the light source side mirror 24, and the light reflected by the ceiling surface 22 to the focal points F2 and F3 and become the diodes 11 and 12. Make it incident.
  • the light receiving side mirrors 25 and 25 are mirrors including a paraboloid surface, a bipolar surface, and a rotating ellipsoidal surface.
  • the light source side mirror 24 determines the curvature so that the light source side mirrors 25 and 25 can easily focus the incident light to the focal points F2 and F3. Therefore, the light source side mirror 24 is not a pure paraboloid.
  • the inner surface of the cell 6, particularly the light source side mirror 24, the light receiving side mirrors 25, 25, and the ceiling surface 22 is configured to mirror-reflect infrared light.
  • the inner surface of the cell 6 is coated with gold plating + protective layer, or It is coated with Al plating + protective layer.
  • FIG. 5 shows the circuit configuration of NDIR2, which includes a power supply such as a battery 44, an IC for driving and signal processing, and a driving circuit 42 of the light source 8, and turns on the light source 8 at a predetermined cycle.
  • the amount of light received by the diodes 11 and 12 at this time is determined by the IC 40, and the gas to be detected is detected from the ratio of the amount of light received.
  • the circuit configuration of NDIR2 is arbitrary.
  • FIGS. 2, 3 and 4 a part of the optical path from the light source 8 to the diodes 11 and 12 is indicated by an arrow.
  • the light receiving surface of the diodes 11 and 12 is parallel to the main surface 5 and includes the focal points F2 and F3 of the light receiving side mirrors 25 and 25. Therefore, the incident light on the light receiving side mirrors 25 and 25 is focused on the diodes 11 and 12. Therefore, the bottom surfaces of the diodes 11 and 12 can be fixed to the main surface 5, and the light receiving surface can be made parallel to the main surface 5.
  • the diodes 11 and 12 can be easily mounted, and it is not necessary to consider the inclination of the diodes 11 and 12 (inclination from the direction perpendicular to the main surface 5).
  • Part of the light from the light source 8 is directly incident on the light receiving side mirrors 25 and 25, and is incident on the diodes 11 and 12.
  • the other part is reflected once by the light source side mirror 24 and is incident on the light receiving side mirrors 25 and 25, and is incident on the diodes 11 and 12.
  • some light is reflected by the ceiling surface 22 and enters the diodes 11 and 12 through the light receiving side mirrors 25 and 25.
  • the light is reflected up to three times, and the light is emitted from the light source 8, reflected by the light source side mirror 24, the ceiling surface 22, and the light receiving side mirrors 25 and 25, and is incident on the diodes 11 and 12.
  • NDIR2 was prototyped using diodes 11 and 12 with a light receiving surface size of 800 ⁇ m ⁇ 800 ⁇ m, and a light source 8 consisting of a coiled heater and having no directivity. Assuming that the range where light is concentrated from the light receiving side mirror 25 is the focal point F2, F3, the focal size is about 200 ⁇ m square, the focal point F2, F3 is smaller than the light receiving surface, and the cell 6, the light source 8, and the diodes 11 and 12 are installed. There was a tolerance for position errors. Of the total amount of light from the light source 8 at the measurement wavelength, the ratio of reaching the light receiving surface was about 3.5% for each of the diodes 11 and 12, and a total of 7% of the amount of light could be used for detection. This is an extremely high percentage for NDIR.
  • the ceiling surface 22 is used as a mirror surface having a curvature, or if a part of the main surface 5 of the substrate 4 is used as a mirror, the light collection efficiency to the diodes 11 and 12 is further improved. However, in the embodiment, this is not done because the height of NDIR2 is limited and the circuit components are mounted on the main surface 5 for some reason.
  • Non-dispersive infrared gas detector NDIR
  • Circuit board 5
  • Main surface 6
  • Optical cell (cell) 8
  • light source 10
  • holder 11,12 Photo diode (diode) 13,14
  • Bandpass filter filter
  • bottom 22
  • Ceiling surface 24
  • mirror 25
  • mirror 26
  • Light source space 29
  • Intermediate surface 30 vents 40
  • IC drive circuit 44
  • battery F1-F3 focus

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Abstract

In the present invention, a light source, at least one light-receiving element, and an optical cell are attached to a substrate. A light-source-side end part of an optical cell inner surface constitutes a light-source-side mirror having the light source as a focus thereof, and the light-receiving-side end part constitutes a light-receiving-side mirror having the light-receiving element as a focus thereof. The height of the light-receiving element from the substrate is less than the height of the light source from the substrate, and the light-receiving element is provided with a light-receiving surface parallel to the substrate. Light from the light source is reflected by the two mirrors, and is incident on the light-receiving surface parallel to the substrate.

Description

非分散型赤外線ガス検出装置Non-dispersive infrared gas detector
　この発明は非分散型赤外線ガス検出装置（NDIR）に関する。 The present invention relates to a non-dispersive infrared gas detector (NDIR).
　NDIRでは基板に光源と受光素子とを配置し、これらを多重反射型の光学セルで覆い、光源から受光素子へ赤外光を導く。そして多重反射によりガス感度を高める。しかし実際には光源からの光の極く一部のみが受光素子に到達し、光源からの光の大部分は検出に役立っていない。また受光素子は、しばしば受光面が基板と直角に配置される。このため受光素子の側面を基板に位置決めすることになり、受光素子の取付が困難になる。 In NDIR, a light source and a light receiving element are arranged on a substrate, and these are covered with a multiple reflection type optical cell to guide infrared light from the light source to the light receiving element. And the gas sensitivity is increased by multiple reflection. However, in reality, only a small part of the light from the light source reaches the light receiving element, and most of the light from the light source is not useful for detection. Further, in the light receiving element, the light receiving surface is often arranged at right angles to the substrate. Therefore, the side surface of the light receiving element is positioned on the substrate, which makes it difficult to attach the light receiving element.
　関連する先行技術を示す。特許文献１（特許4547,427）は２枚の放物面状ミラーを組み合わせ、光の利用効率を高めることを提案している。 Show the related prior art. Patent Document 1 (Patent 4547,427) proposes to combine two parabolic mirrors to improve the efficiency of light utilization.
特許4547,427Patent 4547,427
　この発明の課題は、光源の光が受光素子に到達する割合を高めること、及び、受光素子の受光面を基板の主面に平行に配置できるようにすることにある。 An object of the present invention is to increase the ratio of light from a light source reaching a light receiving element and to enable the light receiving surface of the light receiving element to be arranged parallel to the main surface of the substrate.
　この発明の非分散型赤外線ガス検出装置は、光源と少なくとも一個の受光素子とが互いに向き合うように主面に取り付けられている基板と、
　光源と受光素子とを収容し、かつ基板に対して位置決めされている光学セルとを備えている。
　この発明の非分散型赤外線ガス検出装置では、基板の主面と接する光学セルの面を仮想的な底面、主面と反対側の光学セルの内面を天井面として、
　光学セル内面の少なくとも光源側端部が、光源を焦点とする光源側ミラーを構成し、
　光学セル内面の少なくとも受光側端部が、受光素子を焦点とする受光側ミラーを構成し、
　受光素子は光源よりも主面からの高さが低く、かつ受光素子は受光面が主面に平行になるように、基板に取り付けられていることを特徴とする。 The non-dispersive infrared gas detector of the present invention comprises a substrate on which a light source and at least one light receiving element are mounted on a main surface so as to face each other.
It includes an optical cell that houses a light source and a light receiving element, and is positioned with respect to a substrate.
In the non-dispersive infrared gas detector of the present invention, the surface of the optical cell in contact with the main surface of the substrate is set as a virtual bottom surface, and the inner surface of the optical cell opposite to the main surface is used as a ceiling surface.
At least the light source side end of the inner surface of the optical cell constitutes a light source side mirror that focuses on the light source.
At least the light receiving side end of the inner surface of the optical cell constitutes a light receiving side mirror focusing on the light receiving element.
The light receiving element is lower in height from the main surface than the light source, and the light receiving element is mounted on the substrate so that the light receiving surface is parallel to the main surface.
　光源側ミラーの焦点に光源が有り、光源側ミラーはなるべく多くの光を受光側ミラーへ入射させるように構成されている。受光側ミラーの焦点に受光素子が有るので、受光側ミラーに入射した光は向きを変えて基板主面上の受光素子に入射する。この発明では受光素子の受光面が基板主面に平行なので、受光素子を基板に容易に取り付けることができる。これに対して、受光素子の側面を基板に取り付け、受光面を光源と向かい合わせると、受光素子の取り付け角度の変動により、受光する光量が変動する。 There is a light source at the focal point of the light source side mirror, and the light source side mirror is configured to make as much light as possible incident on the light receiving side mirror. Since the light receiving element is located at the focal point of the light receiving side mirror, the light incident on the light receiving side mirror changes its direction and is incident on the light receiving element on the main surface of the substrate. In the present invention, since the light receiving surface of the light receiving element is parallel to the main surface of the substrate, the light receiving element can be easily attached to the substrate. On the other hand, when the side surface of the light receiving element is attached to the substrate and the light receiving surface faces the light source, the amount of light received varies due to the fluctuation of the attachment angle of the light receiving element.
　受光素子が１個の場合、光源側ミラーも受光側ミラーも放物面状とし、これらの光軸を共通にすることが好ましい。すると光源の光は光源側ミラーで反射し、受光側ミラーの光軸に平行に受光側ミラーに入射するので、受光素子に入射する光の割合が増す。 When there is one light receiving element, it is preferable that both the light source side mirror and the light receiving side mirror have a parabolic shape and have a common optical axis. Then, the light of the light source is reflected by the mirror on the light source side and is incident on the mirror on the light receiving side in parallel with the optical axis of the mirror on the light receiving side, so that the proportion of light incident on the light receiving element increases.
　好ましくは、受光素子が一対基板に取り付けられ、かつ各受光素子を焦点とするように、一対の受光側ミラーが光学セルに設けられている。この場合、光源側ミラーも受光側ミラーも純粋な放物面状ではなく、放物面に加えて、双極面（双極線を焦点を通る軸回りに回転させた図形）あるいは回転楕円面を含むミラーが好ましい。受光素子が一対ある場合、光源から受光側ミラーへ直射する光と、光源側ミラーで反射されて受光側ミラーに入射する光との、光路を平行にすることが難しい。そこで光路に応じて、光源側ミラー及び受光側ミラーの各位置での曲率を変え、なるべく多くの光を受光素子に入射させる。そして例えば一方の受光素子をガス検出用に、他方の受光素子を参照用に用いる。 Preferably, a pair of light receiving side mirrors are provided in the optical cell so that the light receiving elements are attached to the pair of substrates and each light receiving element is focused. In this case, neither the light source side mirror nor the light receiving side mirror is a pure paraboloid, and includes a bipolar surface (a figure in which the bipolar line is rotated about an axis passing through the focal point) or a rotating ellipsoid in addition to the paraboloid. Mirrors are preferred. When there are a pair of light receiving elements, it is difficult to make the optical paths parallel between the light directly emitted from the light source to the light receiving side mirror and the light reflected by the light source side mirror and incident on the light receiving side mirror. Therefore, the curvature at each position of the light source side mirror and the light receiving side mirror is changed according to the optical path, and as much light as possible is incident on the light receiving element. Then, for example, one light receiving element is used for gas detection, and the other light receiving element is used for reference.
　天井面まで拡がるように、光源側ミラーと受光側ミラーを設けると、受光素子へ到達する光量が増す。しかしこの発明の位置では、光学セルの背の高さが増す。そこで好ましくは、天井面を主面に平行な平面状のミラーとし、光学セルの背の高さを制限する。なお光源からの光の一部は平面上の天井面で反射され、受光側ミラーに入射し、受光素子へ到達する。 If a light source side mirror and a light receiving side mirror are provided so as to extend to the ceiling surface, the amount of light reaching the light receiving element increases. However, at the position of the present invention, the height of the optical cell increases. Therefore, it is preferable to use a flat mirror whose ceiling surface is parallel to the main surface to limit the height of the optical cell. A part of the light from the light source is reflected by the ceiling surface on a flat surface, enters the mirror on the light receiving side, and reaches the light receiving element.
実施例の非分散型ガス検出装置（NDIR）の平面図で、光学セルを鎖線で示すThe optical cell is shown by a chain line in the plan view of the non-dispersive gas detector (NDIR) of the embodiment. 図１の11-11方向断面図11-11 direction sectional view of FIG. 図１の111-111方向断面図111-111 direction sectional view of FIG. 実施例の光学セルの底面図Bottom view of the optical cell of the embodiment 実施例の非分散型ガス検出装置の回路図Circuit diagram of the non-dispersive gas detector of the embodiment
　以下に本発明を実施するための最適実施例を示す。 The optimum examples for carrying out the present invention are shown below.
　図１～図５に、実施例の非分散型赤外線ガス検出装置（NDIR）2を示す。図１では、NDIR2の回路基板4と光源8，ホトダイオード11，12を実線で、光学セル（セル）6を鎖線で示す。回路基板4の主面5に、光源8と例えば一対のホトダイオード（ダイオード）11，12が、基板4の長手方向に沿って向かい合うように配置されている。ホトダイオード11，12はIn-Sb系など赤外光に感度を持つダイオードで、焦電素子など他の受光素子でも良い。ダイオード11，12はダイオードとしては同じもので、検出用のホトダイオード11と参照用のホトダイオード12の受光面に、透過波長が異なるバンドパスフィルタ（フィルタ）13,14を取り付ける。なお受光面は、ダイオード11,12の表面で、フィルタ13,14の底面にある。受光面は基板4の主面5に平行で、ダイオード11,12は半田等により底面を基板4に固定する。光源8はホルダー10を介して基板4に取り付けられ、光源8の種類はコイル状のヒータ、MEMSマイクロホットプレート、LED等である。検出対象ガスは、CO2、メタン、等任意である。 FIGS. 1 to 5 show the non-dispersive infrared gas detector (NDIR) 2 of the embodiment. In FIG. 1, the circuit board 4 of NDIR2, the light source 8, and the photodiodes 11 and 12 are shown by solid lines, and the optical cell (cell) 6 is shown by a chain line. A light source 8 and, for example, a pair of photodiodes 11 and 12 are arranged on the main surface 5 of the circuit board 4 so as to face each other along the longitudinal direction of the substrate 4. Photodiodes 11 and 12 are diodes that are sensitive to infrared light such as In-Sb systems, and may be other light receiving elements such as pyroelectric elements. The diodes 11 and 12 are the same as the diodes, and bandpass filters (filters) 13 and 14 having different transmission wavelengths are attached to the light receiving surfaces of the diode 11 for detection and the diode 12 for reference. The light receiving surface is the surface of the diodes 11 and 12 and the bottom surface of the filters 13 and 14. The light receiving surface is parallel to the main surface 5 of the substrate 4, and the bottom surfaces of the diodes 11 and 12 are fixed to the substrate 4 by soldering or the like. The light source 8 is attached to the substrate 4 via the holder 10, and the types of the light source 8 are a coiled heater, a MEMS micro hot plate, an LED, and the like. The gas to be detected is arbitrary, such as CO2 and methane.
　セル6は底面20が主面5に接するように、回路基板4に固定されている。22はセル6の天井面で、平坦なミラーであり、主面5に平行である。セル6の内面の光源8側の端部ないし側部には、光源側ミラー24が設けられている。またセル6内面のホトダイオード11,12側の端部ないし側部には一対の受光側ミラー25，25が設けられ、受光側ミラー25，25の数は受光素子（ホトダイオード）11,12の数と等しい。ホルダー10を収容するための光源用スペース28が設けられ、光源側ミラー24及び受光側ミラー25,25と底面20の間で、セル6は中間面29まで中実である。光源側ミラー24と受光側ミラー25，25の間のセル6内の側面を側面26とする。また中間面29と主面5の間のスペースに、光源8以外の回路部品が収容されている。30,30は例えば一対の通気孔で、セル６の内部へ周囲のガスを導入する。通気孔30の配置、個数等は任意である。 Cell 6 is fixed to the circuit board 4 so that the bottom surface 20 is in contact with the main surface 5. 22 is the ceiling surface of cell 6, which is a flat mirror, parallel to the main surface 5. A light source side mirror 24 is provided on the inner surface of the cell 6 at the end or side of the light source 8 side. A pair of light-receiving side mirrors 25, 25 are provided at the end or side of the photodiodes 11 and 12 on the inner surface of the cell 6, and the number of light-receiving side mirrors 25 and 25 is the number of light-receiving elements (photodiodes) 11,12. equal. A space 28 for a light source for accommodating the holder 10 is provided, and the cell 6 is solid up to the intermediate surface 29 between the light source side mirrors 24 and the light source side mirrors 25 and 25 and the bottom surface 20. The side surface in the cell 6 between the light source side mirror 24 and the light receiving side mirrors 25 and 25 is referred to as the side surface 26. In addition, circuit components other than the light source 8 are housed in the space between the intermediate surface 29 and the main surface 5. 30 and 30 are, for example, a pair of ventilation holes, and introduce surrounding gas into the cell 6. The arrangement, number, etc. of the ventilation holes 30 are arbitrary.
　この明細書では、主面5に直角に天井面22を向く方向を高さ方向とし、主面5及びセル6の長辺方向を長さ方向、主面５とセル6の短辺方向を幅方向とする。光源8はホトダイオード11,12の受光面よりも高い位置にあり、光源8と主面5の間には隙間がある。側面26は主面５に対して直角、底面20と中間面29は主面5に平行である。 In this specification, the direction facing the ceiling surface 22 at right angles to the main surface 5 is the height direction, the long side direction of the main surface 5 and the cell 6 is the length direction, and the short side direction of the main surface 5 and the cell 6 is the width. The direction. The light source 8 is located higher than the light receiving surfaces of the photodiodes 11 and 12, and there is a gap between the light source 8 and the main surface 5. The side surface 26 is perpendicular to the main surface 5, and the bottom surface 20 and the intermediate surface 29 are parallel to the main surface 5.
　光源側ミラー24の焦点F1は光源8内にある。また受光側ミラー25,25の焦点F2,F3はダイオード11，12の受光面にある。光源側ミラー24及び受光側ミラー25,25は、セル6内面の端部ないし側部にあり、天井面22と中間面29は平坦面である。受光側ミラー25,25は、光源8から直射した光、光源側ミラー24で反射した光、及び天井面22で反射した光を、いずれも焦点F2,F3へ集光してダイオード11,12に入射させる。このため、受光側ミラー25,25は、放物面と、双極面及び回転楕円面を含むミラーである。光源側ミラー24は、受光側ミラー25,25が入射光を焦点F2,F3へ集光しやすいように、曲率を定める。このため光源側ミラー24も純粋な放物面状ではない。 The focal point F1 of the light source side mirror 24 is in the light source 8. The focal points F2 and F3 of the light receiving side mirrors 25 and 25 are on the light receiving surfaces of the diodes 11 and 12. The light source side mirror 24 and the light source side mirrors 25 and 25 are located at the end or side of the inner surface of the cell 6, and the ceiling surface 22 and the intermediate surface 29 are flat surfaces. The light receiving side mirrors 25 and 25 condense the light directly emitted from the light source 8, the light reflected by the light source side mirror 24, and the light reflected by the ceiling surface 22 to the focal points F2 and F3 and become the diodes 11 and 12. Make it incident. Therefore, the light receiving side mirrors 25 and 25 are mirrors including a paraboloid surface, a bipolar surface, and a rotating ellipsoidal surface. The light source side mirror 24 determines the curvature so that the light source side mirrors 25 and 25 can easily focus the incident light to the focal points F2 and F3. Therefore, the light source side mirror 24 is not a pure paraboloid.
　なおセル6の内面、特に光源側ミラー24及び受光側ミラー25,25と天井面22は、赤外光が鏡面反射するように構成され、例えばセル6の内面は金メッキ＋保護層による被覆、あるいはAlメッキ＋保護層による被覆が施されている。 The inner surface of the cell 6, particularly the light source side mirror 24, the light receiving side mirrors 25, 25, and the ceiling surface 22 is configured to mirror-reflect infrared light. For example, the inner surface of the cell 6 is coated with gold plating + protective layer, or It is coated with Al plating + protective layer.
　図５は、NDIR２の回路構成を示し、電池44等の電源と、駆動及び信号処理用のICと、光源8の駆動回路42を備え、光源8を所定の周期でONさせる。この時のダイオード11，12の受光光量をIC４０で求め、受光光量の比から検出対象ガスを検出する。なおNDIR２の回路構成は任意である。 FIG. 5 shows the circuit configuration of NDIR2, which includes a power supply such as a battery 44, an IC for driving and signal processing, and a driving circuit 42 of the light source 8, and turns on the light source 8 at a predetermined cycle. The amount of light received by the diodes 11 and 12 at this time is determined by the IC 40, and the gas to be detected is detected from the ratio of the amount of light received. The circuit configuration of NDIR2 is arbitrary.
　図２，図３，図４に、光源8からダイオード11,12への光路の一部を矢印で示す。ダイオード11,12の受光面は主面5と平行で、受光側ミラー25,25の焦点F2,F3を含んでいる。このため受光側ミラー25，25への入射光は、ダイオード11,12に集光される。そしてこのため、ダイオード11,12の底面を主面5に固定し、受光面を主面5と平行にすることが可能になる。ダイオード11,12の底面を主面5に固定すると、ダイオード11,12の実装が容易で、ダイオード11,12の傾き（主面5に直角な方向からの傾斜）を考慮する必要もなくなる。 In FIGS. 2, 3 and 4, a part of the optical path from the light source 8 to the diodes 11 and 12 is indicated by an arrow. The light receiving surface of the diodes 11 and 12 is parallel to the main surface 5 and includes the focal points F2 and F3 of the light receiving side mirrors 25 and 25. Therefore, the incident light on the light receiving side mirrors 25 and 25 is focused on the diodes 11 and 12. Therefore, the bottom surfaces of the diodes 11 and 12 can be fixed to the main surface 5, and the light receiving surface can be made parallel to the main surface 5. If the bottom surface of the diodes 11 and 12 is fixed to the main surface 5, the diodes 11 and 12 can be easily mounted, and it is not necessary to consider the inclination of the diodes 11 and 12 (inclination from the direction perpendicular to the main surface 5).
　光源8からの光の一部は受光側ミラー25,25に直接入射し、ダイオード11,12に入射する。他の一部は、光源側ミラー24により1回反射されて受光側ミラー25,25に入射し、ダイオード11,12に入射する。また一部の光は、天井面22で反射され、受光側ミラー25,25を介してダイオード11,12に入射する。反射は最大3回で、光は光源8から出射し、光源側ミラー24と天井面22及び受光側ミラー25，25で反射され、ダイオード11,12に入射する。 Part of the light from the light source 8 is directly incident on the light receiving side mirrors 25 and 25, and is incident on the diodes 11 and 12. The other part is reflected once by the light source side mirror 24 and is incident on the light receiving side mirrors 25 and 25, and is incident on the diodes 11 and 12. Further, some light is reflected by the ceiling surface 22 and enters the diodes 11 and 12 through the light receiving side mirrors 25 and 25. The light is reflected up to three times, and the light is emitted from the light source 8, reflected by the light source side mirror 24, the ceiling surface 22, and the light receiving side mirrors 25 and 25, and is incident on the diodes 11 and 12.
　受光面のサイズが800μm×800μmのダイオード11,12を用い、コイル状ヒータから成り指向性が無い光源8を用い、NDIR２を試作した。受光側ミラー25から光が集中する範囲を焦点F2,F3とすると、焦点のサイズは200μm角程度で、焦点F2,F3は受光面よりも小さく、セル6，光源8，ダイオード11,12の設置位置の誤差に対する許容範囲があった。測定波長での光源8からの全光量の内、受光面に達する割合はダイオード11,12がそれぞれ3.5％程度で、光量の合計7％を検出に用いることができた。これはNDIRとしては極めて高い割合である。 NDIR2 was prototyped using diodes 11 and 12 with a light receiving surface size of 800 μm × 800 μm, and a light source 8 consisting of a coiled heater and having no directivity. Assuming that the range where light is concentrated from the light receiving side mirror 25 is the focal point F2, F3, the focal size is about 200 μm square, the focal point F2, F3 is smaller than the light receiving surface, and the cell 6, the light source 8, and the diodes 11 and 12 are installed. There was a tolerance for position errors. Of the total amount of light from the light source 8 at the measurement wavelength, the ratio of reaching the light receiving surface was about 3.5% for each of the diodes 11 and 12, and a total of 7% of the amount of light could be used for detection. This is an extremely high percentage for NDIR.
　天井面22を曲率が有るミラー面として用いる、あるいは基板4の主面5の一部をミラーとすると、ダイオード11,12への集光効率は更に向上する。しかし実施例では、NDIR2の背の高さを制限し、かつ主面5に事由に回路部品を実装するため、このようなことは行わなかった。 If the ceiling surface 22 is used as a mirror surface having a curvature, or if a part of the main surface 5 of the substrate 4 is used as a mirror, the light collection efficiency to the diodes 11 and 12 is further improved. However, in the embodiment, this is not done because the height of NDIR2 is limited and the circuit components are mounted on the main surface 5 for some reason.
　2　　非分散型赤外線ガス検出装置（NDIR）
　4　　回路基板
　5　　主面
　6　　光学セル（セル）
　8　　光源
10　　 ホルダー
11,12　ホトダイオード（ダイオード）
13,14　バンドパスフィルタ（フィルタ）
20　　 底面
22　　 天井面
24　　 ミラー
25　　 ミラー
26　　 側面
28　　 光源用スペース
29　　 中間面
30　　 通気孔
40　　 IC
42　　 駆動回路
44　　 電池
　
F1-F3　焦点　　　　　　　　 2 Non-dispersive infrared gas detector (NDIR)
4 Circuit board 5 Main surface 6 Optical cell (cell)
8 light source
10 holder
11,12 Photo diode (diode)
13,14 Bandpass filter (filter)
20 bottom
22 Ceiling surface
24 mirror
25 mirror
26 sides
28 Light source space
29 Intermediate surface
30 vents
40 IC
42 drive circuit
44 battery
F1-F3 focus

Claims (3)

  1. 　光源と少なくとも一個の受光素子とが互いに向き合うように主面に取り付けられている基板と、
    　光源と受光素子とを収容し、かつ基板に対して位置決めされている光学セルとを備える、非分散型赤外線ガス検出装置において、
    　前記主面と反対側の光学セルの内面を天井面として、
    　前記光学セル内面の少なくとも光源側端部が、前記光源を焦点とする光源側ミラーを構成し、
    　前記光学セル内面の少なくとも受光側端部が、前記受光素子を焦点とする受光側ミラーを構成し、
    　前記受光素子は前記光源よりも前記主面からの高さが低く、かつ受光素子は受光面が主面に平行になるように、基板に取り付けられていることを特徴とする、非分散型赤外線ガス検出装置。     A substrate on which the light source and at least one light receiving element are mounted on the main surface so as to face each other,
    In a non-dispersive infrared gas detector comprising a light source and a light receiving element and an optical cell positioned with respect to a substrate.
    The inner surface of the optical cell opposite to the main surface is used as the ceiling surface.
    At least the light source side end of the inner surface of the optical cell constitutes a light source side mirror focusing on the light source.
    At least the light receiving side end of the inner surface of the optical cell constitutes a light receiving side mirror focusing on the light receiving element.
    The non-dispersive infrared ray is characterized in that the light receiving element has a lower height from the main surface than the light source, and the light receiving element is attached to a substrate so that the light receiving surface is parallel to the main surface. Gas detector.
  2. 　前記天井面は前記主面に平行な平面状のミラーであることを特徴とする、請求項１の非分散型赤外線ガス検出装置。 The non-dispersive infrared gas detection device according to claim 1, wherein the ceiling surface is a flat mirror parallel to the main surface.
  3. 　前記受光素子が一対基板に取り付けられ、かつ各受光素子を焦点とするように、一対の受光側ミラーが前記光学セルに設けられていることを特徴とする、請求項１または２の非分散型赤外線ガス検出装置。 The non-dispersive type according to claim 1 or 2, wherein the light receiving elements are attached to a pair of substrates and a pair of light receiving side mirrors are provided in the optical cell so as to focus each light receiving element. Infrared gas detector.
PCT/JP2020/011048 2019-05-07 2020-03-13 Non-dispersive infrared gas detection device WO2020225977A1 (en)

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Publication number Priority date Publication date Assignee Title
JPH09184803A (en) * 1995-12-29 1997-07-15 Horiba Ltd Infrared gas analyzer
JPH11271221A (en) * 1998-03-20 1999-10-05 Horiba Ltd Infrared gas analyzer
JP2000019108A (en) * 1998-07-06 2000-01-21 Horiba Ltd Infrared gas analyzer
JP2007514160A (en) * 2003-12-12 2007-05-31 イーエルティー インコーポレイテッド Gas sensor
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