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WO2010118749A1 - Détecteur de gaz avec regard de filtration - Google Patents

Détecteur de gaz avec regard de filtration Download PDF

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Publication number
WO2010118749A1
WO2010118749A1 PCT/DK2010/000046 DK2010000046W WO2010118749A1 WO 2010118749 A1 WO2010118749 A1 WO 2010118749A1 DK 2010000046 W DK2010000046 W DK 2010000046W WO 2010118749 A1 WO2010118749 A1 WO 2010118749A1
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WO
WIPO (PCT)
Prior art keywords
sensor
filter
band
suspect
radiation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DK2010/000046
Other languages
English (en)
Inventor
Jens Møller JENSEN
Arun Krishna
Lars Munch
Rainer Buchner
Thomine Stolberg-Rohr
Henrik Gedde Moos
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Danfoss Ixa AS
Original Assignee
Danfoss Ixa AS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Danfoss Ixa AS filed Critical Danfoss Ixa AS
Publication of WO2010118749A1 publication Critical patent/WO2010118749A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0006—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation
    • 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
    • G01N21/15—Preventing contamination of the components of the optical system or obstruction of the light path
    • 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
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/007—Pressure-resistant sight glasses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/12—Generating the spectrum; Monochromators
    • G01J2003/1213—Filters in general, e.g. dichroic, band
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
    • 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
    • G01N2021/0389—Windows
    • 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
    • G01N2021/3531—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 without instrumental source, i.e. radiometric

Definitions

  • the invention relates to a sensor having a filter arrangement, downstream of which there is arranged a detector arrangement, and an evaluating device which is connected to the detector arrangement.
  • a sensor having a filter arrangement, downstream of which there is arranged a detector arrangement, and an evaluating device which is connected to the detector arrangement.
  • particles or substances in general present in the environment where the sensor operates as these over time gets into contact with more delicate parts of the sensor, decreasing the time of operation of the sensor, before maintenances or even exchange is needed. It is therefore often desired to keep the more delicate parts of the sensor physically separated from the media or environment containing the substances or species being measured by the sensor.
  • the present invention solves this problem by introducing sight glasses positioned at least in front of the delicate parts of the sensor, the sight glasses in general being formed with coating(s) chosen according to the environment wherein the sight glasses are to be used.
  • Such a sensor which is configured as a gas sensor, is known, for example, from US 5,081 ,998 A.
  • An IR radiation source is provided therein, which acts upon a total of four detectors by way of a filter arrangement.
  • the filter arrangement has two filters having different pass characteristics.
  • a first filter has a pass band for IR radiation that is absorbed by CO2. That filter is therefore also referred to as a "CO 2 filter".
  • the detectors arranged downstream are designated CO 2 detectors.
  • the other filter has a pass band different therefrom which serves for determining a reference quantity.
  • the detectors arranged downstream of that reference filter are referred to as reference detectors.
  • a third filter which is referred to as a natural density filter and overlaps half of the first filter and half of the second filter. Accordingly, one of the two CO 2 detectors and one of the reference detectors receives only IR radiation that has passed both through the natural density filter and through either the CO 2 filter or the reference filter.
  • the difference of the output signals of the two CO 2 detectors and the difference of the two reference detectors is formed. The two differences are then divided by one another.
  • a CO 2 sensor is required, for example, for determining CO 2 in a patient's breath so as to be better able to monitor the patient during anaesthesia.
  • the problem underlying the invention is to simplify the use of an IR sensor, which is introduced in the sensor described in US 2008/0283753, wherein the pass band of a first filter is arranged within the pass band of a second filter and the evaluating device forms the difference of the signals of the detectors and normalises it to the signal of a detector.
  • the IR radiation is therefore not divided into two separate ranges, with each detector detecting only one range. Instead, one detector detects IR radiation having a pre-set spectral range, which also includes, for example, the absorption spectrum of the gas being determined, here CO 2 . The other detector detects an IR spectrum from a sub-range thereof, which does not include the absorption spectrum of the gas being determined.
  • the normalisation of the difference to the output signal of a detector enables fluctuations in the intensity of the IR radiation to be compensated. It is also possible to use more than two sensors with a correspondingly greater number of filters, the individual pass ranges then overlapping accordingly.
  • the senor can transmit its signals wirelessly.
  • the pass band of the first filter is preferably larger than the pass band of the second filter. Accordingly, the first filter, in addition to including the spectral range allowed to pass by the second filter, also includes the spectral range in which IR radiation is absorbed.
  • the two filters preferably have a common cut-off wavelength. That simplifies evaluation. The difference between the output signals of the detectors can then readily be formed without additional calculation steps being necessary.
  • the cutoff wavelengths are the wavelengths that define, that is to say limit, the pass bands. They are referred to as "lower wavelength” and "upper wavelength”.
  • a selective gas detection system is arranged in the measurement gas space for a defined volatile component.
  • the gas detection system has an IR light source, an IR filter and an IR-sensitive light sensor. Light falls through the IR filter on the light sensor.
  • the IR filter comprises a transmission window in the range of an alcohol-specific absorption band.
  • Another example is the optoacoustic gas sensor disclosed in US 6,006,585 that has a sensor body, a light source, a measurement cell with a gas-permeable membrane, a measurement microphone, and an optical measurement filter between the light source and the measurement cell, a reference cell is included that is separate from the measurement cell.
  • the reference cell has a reference microphone that is shielded against optoacoustic signals from the gas to be detected via the reference cell being substantially free from intensity-modulated optical radiation having an absorption wavelength of the gas to be detected.
  • the measurement signal which indicates gas concentration, is obtained by subtraction of the signals from the two microphones.
  • the present invention solves these problems by introducing a sensor equipped with sight glass penetrable to the light at least in the wavelengths of relevance.
  • the substances or particles in the media or environment may also settle at the sight glass to make it less transparent, or even totally block it for light. Therefore, in order to enhance the operational time of the sensor before maintenance or even an exchange is needed, one or more layers of coating is formed on the surface(s) of the sight glass to be in contact with the environment.
  • the coating(s) may be for example, PTFE (Polytetrafluorethylene), also known as Teflon ⁇ , being chemically resistant, hydrophobic and with non-stick properties.
  • PTFE Polytetrafluorethylene
  • Teflon ⁇ Teflon ⁇
  • Sol-gel derived materials where the materials derived by this technique cover a wide range of materials, from spin-on glasses to ceramics, metal-chlorides, polymers etc.
  • a further example is DLC (Diamond-Like-Carbon), since DLC has good IR-transmission and can be used as antireflective coating on e.g. silicon or germanium. Furthermore it is mechanically highly robust and shows also good chemical stability.
  • the surface(s) of the sight glass may be structured on the micro- and the nanoscale (e.g Lotus-effect), for example to make it superhydrophobic or superhydrophilic in order to achieve a self-cleaning effect.
  • the nanoscale e.g Lotus-effect
  • the base material of the sight glass may be any known within the field of glass making and general making of transparent materials. Among many suitable materials are such as Silicon, Germanium, CaF2, Sapphire etc.
  • the sight glass may further be formed as a pass band filter letting through only selected wavelengths, either preventing the passing of wavelengths above or below some wavelength, or within some band of wavelengths.
  • Such a bandpass filter generally is formed as a transparent base material with some coating letting through wavelengths above or below the desired wavelength, or with both kinds of coatings forming a band of wavelengths allowed to pass.
  • Such secondary coatings preferably would be formed between the base material and the above described primary protective coating, or alternatively, on a surface of the sight glass not to be in contact with the environments.
  • the invention also relates to a sensor device, especially a gas sensor, equipped with such a sight glass.
  • a fixing structure is introduced having two ends, such that the sensor device is fixed at the first end, and the light source/emitter is fixed at the second end.
  • the fixing structure preferably is hollow and equipped with a sight glass at each end in order to ensure optic communication from the light source to the detector device.
  • This construction is able to compensate for changes in the intensity of radiation of the (IR) source, however, is not robust to for example temperature changes of IR source.
  • the "lower wavelength” is the lowest wavelength from which the filters allow passage of radiation
  • the "upper wavelength” is the highest wavelength higher that the lower wavelength, from which the filters shuts off passage of radiation.
  • the ranges of allowed wavelengths of the suspect filter are in the following being referred to as the "suspect band", and the allowed wavelengths of the reference filter(s) are in the following being referred to as the "reference band(s)".
  • the suspect lower wavelength in the present invention is different to the reference lower length(s), and the suspect upper wavelength is different to the reference upper wavelength(s).
  • the mean value, or average, of the radiation intensity density (or energy) over the suspect band roughly equals the mean value, or average, of the radiation intensity density (or energy) over each of the reference bands.
  • the radiation intensity density (or energy) over the suspect band roughly equals the mean value, or average, of the radiation intensity density (or energy) over the whole of the combined reference bands, (the 'reference filter system band' is the combined reference bands of all the reference filters).
  • the radiation intensity density (or energy) over the suspect band roughly equals the mean value, or average, of the radiation intensity density (or energy) of one of or each of the reference bands.
  • the filters of the present invention may be formed by filter elements in series, or by one single filter element. When two or more filters are arranged as filter elements in series, they are arranged one after the other in the radiation direction, that is to say between the radiation source(s) and the detectors.
  • the sensor with advantage may operate within any radiation wavelength, and the source may be any radiation source.
  • At least one reference filter (to be called the first reference filter) has a reference band, called the first reference band, with a wider span of wavelengths than the suspect band, where the first reference lower wavelength of this first reference filter is at a lower wavelength than the suspect lower wavelength, and the first reference upper wavelength of this first reference filter has a higher wavelength than the suspect upper wavelength.
  • the suspect band overlaps the first reference band.
  • the centre wavelength of the first reference band (the first centre reference wavelength) and the centre wavelength of the suspect band may be the same, or may be different.
  • the relative change in intensity in the suspect and reference band must be equal in order for the temperature dependency to cancel out.
  • the unmatching centre wavelength can be introduced to improve stability to temperature drift.
  • the reference filter(s) advantageously has a pass band that is from 0.2 to 1 ⁇ m greater than the pass band of the suspect filter. It is desirable for the suspect filter to cover basically only a relatively narrow wavelength range or spectral range of the radiation spectrum, for example the range in which IR radiation is absorbed by CO 2 . The range indicated is sufficient for this. The risk that absorption by other gases will have an adverse effect on the measurement result and falsify that result is kept small.
  • the first reference filter prefferably has a pass band in the range from 4 to 4.5 ⁇ m and the suspect filter to have a pass band in the range from 4.1 to 4.4 ⁇ m. In dependence upon the gases or other quantities being detected, those spectral ranges can of course also be shifted.
  • the system comprises a first and a second reference filter with a first and second reference band respectively (together constituting the combined reference bands), where the first and second reference bands are non-overlapping, meaning they span no common wavelengths.
  • At least one of the first or second reference bands overlaps the suspect band, meaning that the first reference upper wavelength is at a higher wavelength than the suspect lower wavelength, and/or the second reference lower wavelength is at a lower wavelength than the suspect upper wavelength, but at a higher than the first reference upper wavelength, thus leading to the first and second reference bands extending at each side of the suspect band, but without overlapping.
  • the first reference upper wavelength is at a lower wavelength than the suspect lower wavelength
  • the second reference lower wavelength is at a higher wavelength than the suspect upper wavelength
  • the first and second reference bands are overlapping having at least one common wavelength.
  • the senor uses the natural radiation, such as IR radiation, from the environment.
  • IR radiation is generally present everywhere, even when there is no incident sunlight. In principle every body emits a certain amount of thermal radiation.
  • the "measurement range" is also broadened, that is to say it is possible to monitor relatively large areas of a room for the content of the gas in question. This facilitates the monitoring and establishment of a "personal room climate" or the indoor air quality. It is unnecessary first to conduct the air in the room to a sensor where it is passed between the source of IR radiation and the detectors with upstream filters.
  • the senor it is sufficient for the sensor to be arranged at a point in the room where it can, as it were, "survey" the volume of air to be monitored. In that case, the gas sensor can, as it were, detect the averaged gas concentration in a simple way. The sensor therefore determines an average value, which, particularly for the personal room climate, constitutes a substantially better measurement result.
  • the sensor it is also possible to use the sensor to improve the technology of sensors that operate with lamps or other means of lighting. When natural or ambient IR radiation is used, the energy of the light means can be reduced. That results in longer maintenance intervals and a longer service life.
  • the filters preferably contain CaF 2 , germanium or silicon.
  • the filter and any other parts of the sensor device where it would make sense, preferably has an anti-reflective coating in order to improve transmission.
  • Fig. 1 is a diagrammatic view for explaining the operating principle of the present invention
  • Fig. 2 is a schematically illustrates a sight glass with surface modifications such as coatings, being a first aspect of the present invention.
  • Fig. 3 is a schematically illustration of an aligning structure with fixing a detecting part and light source together, this being a further optional aspect of the present invention.
  • Fig. 4A-E shows, in diagrammatic form, pass bands of two or three filters
  • Fig. 5 illustrates a Planck curve and a pass band.
  • Fig. 6 shows, in diagrammatic form, the amount of energy that can be detected by detectors
  • Fig. 7A-D are block circuit diagrams for explaining different embodiments of the structure of the gas sensor
  • Fig. 1 shows a diagrammatic view of a gas sensor (1) for determining for example the CO 2 content (carbon dioxide content) in a measurement region (3), where the sensor (1) comprises a detection part (2).
  • the measurement region may be, for example, a room or the portion of a room in which the personal room climate is to be regulated.
  • a sun symbol (4) represents a radiation source, such as for example a natural IR source, passive sources, or any imaginable active source (sunlight, laser, light diodes, controlled hated sources etc.)
  • the sun symbol (4) serves here merely for explanation purposes.
  • the gas sensor (1) also operates in the absence of sunlight, because in principle virtually any body radiates heat and thus generates IR rays.
  • the CO 2 molecules are present in the measurement region (2), the CO 2 molecules being represented herein by small circles.
  • the gas molecules (5) absorb IR rays in a specific spectral range, as represented by the arrows. The greater the concentration of CO 2 the lower the energy in a specific spectral range that can be detected in the gas sensor (1).
  • the figure shows a first aspect of the present invention, where a sight glass (100) is positioned in front of the detecting part (2) of the sensor (1).
  • Fig. 2 shows a further aspect of the present invention, being a side view of such a sight glass having a base substrate (102) and having a coating (101) and/or some kind of structures and/or some kind of processing / treatment of at least a part of one of the surface of the sight glass (100).
  • the coating(s) (101) may be for example, PTFE (Polytetrafluorethylene), also known as Teflon ⁇ , being chemically resistant, hydrophobic and with non-stick properties and being.
  • PTFE Polytetrafluorethylene
  • Teflon ⁇ Teflon ⁇
  • Sol-gel derived materials where the materials derived by this technique cover a wide range of materials, from spin- on glasses to ceramics, metal-chlorides, polymers etc.
  • a further example is DLC (Diamond-Like-Carbon), since DLC has good IR-transmission and can be used as antireflective coating on e.g. silicon or germanium. Furthermore it is mechanically highly robust and shows also good chemical stability.
  • the surface(s) of the sight glass may be structured on the micro- and the nanoscale (e.g Lotus-effect), for example to make it superhydrophobic or superhydrophilic in order to achieve a self-cleaning effect.
  • the nanoscale e.g Lotus-effect
  • the base material (102) of the sight glass may be any known within the field of glass making and general making of transparent materials. Among many suitable materials are such as Silicon, Germanium, CaF2, Sapphire etc.
  • the sight glass(es) (100) may further be formed as a pass band filter letting through only selected wavelengths, either preventing the passing of wavelengths above or below some wavelength, or within some band of wavelengths.
  • a bandpass filter generally is formed as a transparent base material with some coating letting through wavelengths above or below the desired wavelength, or with both kinds of coatings forming a band of wavelengths allowed to pass.
  • Such secondary coatings preferably would be formed between the base material and the above described primary protective coating, or alternatively, on a surface of the sight glass not to be in contact with the environments.
  • Fig. 3 illustrates a further embodiment of the present invention, showing the detecting part (2) fixed in a first structure (103) and a constructed light source (4) fixed in a second structure (104).
  • Light illustrated by the arrow (107) is emitted by the light source (4) and as it passes the measuring region (3) some wavelengths are absorbed by the suspect species (5).
  • a sight glass (100a) is positioned in front of the detecting part (2) protecting it from any dirt, particles etc. present in the measuring region (3).
  • an aligning structure (105) is illustrated fixing the first (103) and second (104) structures, and thereby the detecting part (2) and light source (4), together in a manner that ensures a correct alignment despite any ambient influences.
  • the aligning structure (105) is preferably hollow and solid enough to fix the parts (103) and (104) solid to each other, but comprises pores, openings, holes etc. (106) that allows the suspect species (5) to easily flow into and out of the internal hollow, being the measuring region (3), of the of aligning structure (105).
  • the illustration further shows a second sight glass (100b) covering the light source (4) protecting it's delicate parts.
  • Fig. 7A shows, in diagrammatic form, a block circuit diagram for explaining the structure of the simple detecting part (2) of a gas sensor (1).
  • the detecting part (2) has a filter arrangement (6), a detector arrangement (7) and an evaluating device (8). Further details, such as the housing, fixing means or the like, are not shown herein.
  • the shown filter arrangement has a first reference filter (10) and a suspect filter (9), where the two filters (9) and (10) have different pass characteristics, where one embodiment is shown in Fig. 4A.
  • the first reference filter (10) allows passing of wavelengths within the firsts reference band RB1
  • the suspect filter (10) allows the passing of wavelengths within the suspect band SB.
  • the embodiment in Fig. 4B shows the first reference band RB1 spanning wider than the suspect band SB, but where the suspect band SB overlaps the first reference band RB1 in such a manner, that the first reference band RB1 comprises the same wavelengths as the suspect band SB.
  • the first reference lower wavelength RLW1 therefore is at a lower wavelength than the suspect lower wavelength SLW, and the first reference upper wavelength RUW1 has a higher wavelength than the suspect upper wavelength SUW.
  • the first reference band RB1 has a first centre wavelength RCW1, and the suspect band has a suspect centre wavelength SCW.
  • the figure shows the two bands having a common centre wavelength RCW1 and SCW.
  • Fig. 4B shows a related embodiment to that shown in Fig. 4A, only where they dissimilar centre wavelengths RCW and RCW1.
  • the relative change in intensity in the suspect and reference band must be equal in order for the temperature dependency to cancel out.
  • the relative change in intensity depends unlinearly on the wavelengths spanned by the bands. Therefore the unmatching centre wavelength can be introduced to improve stability to temperature drift.
  • Fig. 5 illustrates the situation of a source emitting with a spectral distribution represented by a general Planck curve having a maximum radiation at the wavelength ⁇ max, and having a continuously decreasing radiation for increasing wavelengths above ⁇ max, so using a band ⁇ between two such wavelengths ⁇ 1 and ⁇ 2.
  • the radiation R1 at the lower wavelength ⁇ 1 being larger than the radiation R2 at the upper wavelength ⁇ 2.
  • unmatching centre wavelengths are introduced giving different spans of wavelengths of the reference band(s) below and above the suspect band respectively, where these different spans then compensates the changing radiation intensity.
  • Fig. 4C shows another embodiment where a second reference filter (20) has been introduced into the system spanning over a second reference band RB2 extending from a second reference lower wavelength RLW2 to a second reference upper wavelength RUW2.
  • the shown embodiment further has the suspect band SB only partly overlapping both the first and second reference bands RB1 and RB2 in such a manner, that the suspect lower wavelength SLW is between the first reference lower wavelength RLW1 and the first reference upper wavelength RUW1.
  • the suspect upper wavelength SUW is between the second reference lower wavelength RLW2 and the second reference upper wavelength RUW2.
  • the shown embodiment has the first reference upper wavelength RUW1 being higher than the second reference lower wavelength RLW2, but in other embodiments the first and second reference bands RB1 and RB2 might not overlap, meaning that the first reference upper wavelength RUW1 would be lower or equal to the second reference lower wavelength RLW2.
  • Fig. 4D shows an alternative embodiment with two reference filters (10) and (20), where none of the reference bands RB1 and RB2 at least substantially overlaps the suspect band SB, at least, but extends at each side of it, here meaning, that the first reference upper wavelength RUW1 is not higher than the suspect lower wavelength SLW 1 but could optionally be the same, and the second reference lower wavelength RLW2 is not lower than the suspect upper wavelength SUW, but could optionally be the same.
  • the figure shows the two reference bands RB1 and RB2 having substantially the same pass range of wavelengths, but as seen in Fig. 2E this may not be the case, the two reference bands RB1 and RB2 might have very different pass ranges of wavelengths.
  • the relative positions and sizes of the bands depends on a number of factors, such as the tolerances of the edges of the filters, the width of the suspect bandpass, the distribution of the absorption lines of the suspect band, and of any other gasses that might cause cross sensitivities.
  • the suspect band SB could with advantage have a suspect lower wavelength SLW at about 4.0 ⁇ m and a suspect upper wavelength SUW at about 4.5 ⁇ m, or with an even more narrow range of the suspect band from 4.1 ⁇ m - 4.4 ⁇ m, or any other band covering the spectral range of CO 2
  • the reference start and upper wavelengths then with advantage could extend about 0.5 ⁇ m above and below the suspect lower wavelength SLW and suspect upper wavelength SUW respectively.
  • Fig. 6 illustrates a first reference band RB1 and the suspect band SB of the first embodiment of the invention as seen in Fig. 5, where the suspect band has a unreduced energy indicated by reference letter A. That energy is reduced by an amount C which is absorbed by for example CO 2 .
  • the two sections of the first reference band RB1 extending at each side of the suspect band each has an energy indicated by reference letters B. That energy is virtually constant, because it is not affected by for example CO 2 .
  • Fig. 7A shows one simple embodiment of a construction of a filter arrangement (6), where the suspect filter (9) comprises two filter elements (11) and (12), the first suspect filter element (11) defining the suspect upper wavelength SUW and having a lower wavelength lower than the suspect lower wavelength SLW.
  • the second suspect filter element (12) defines the suspect lower wavelength SLW and has an upper wavelength substantially higher than the suspect upper wavelength SUW.
  • the first reference filter (10) comprises two filter elements (13) and (14) defining the first reference upper wavelength RUW1 and the first reference lower wavelength RLW1 respectively.
  • any number of such constructions of filter elements (11), (12), (13) and (14) may be introduced into the filter arrangement (6).
  • Some filter elements in this and any other embodiment may be common to two or more of the filters when the filters have the same end and/or lower wavelength, this being illustrated in Fig. 7B, where the two 'upper' filter elements (11) and (13) is one common filter element.
  • Fig. 7C shows a similar sensor having a extra reference filter, the second reference filter (20), and where each filter only has a single filter element (21 , 22, 23) comprising the desired band pass characteristic both for the upper and lower wavelengths, the suspect filter (21) thus both defining both the suspect lower wavelength SLW and upper suspect wavelength SUW.
  • the first reference filter (22) defining both the first reference upper and lower wavelengths RUW1 and RLW1
  • the second reference filter (23) defining both the second reference upper and lower wavelengths RUW2 and RLW2.
  • the two filter elopements (22, 23) are in this illustrated embodiment connected to the same detector (16) though in reality what would be none, is to add their signals mathematically after they have been acquired by for example two separated Thermopiles.
  • Fig. 7D shows an embodiment related to that of Fig. 7C, only where a third detector (24) is connected to the second reference filter (20).
  • the senor could also be used to measure more than one gas, then just including the needed number of sensors, detectors etc., as it will be known to a craftsman.
  • thermopile sensor usually a temperature measurement is carried out (because the output signal varies with temperature), measurement of the temperature around the sensor has already been incorporated.
  • the radiation temperature of the room is also obtainable by means of the sensor, it is possible on the basis of those two measurements simultaneously to obtain directly an operating temperature which can then be used for controlling the room temperature or something quite different.
  • IR In connection with IR it is also conceivable that measurement of a movement in the room is directly possible with the sensor, which can then be used, for example, for controlling a ventilating system, which, for example, is activated only in the event of a movement indicating that there is someone in the room.
  • a ventilating system which, for example, is activated only in the event of a movement indicating that there is someone in the room.
  • IcO 2 ' s * ne electrical quantity for example the current or the voltage, containing the information relating to the IR absorption
  • l ref is the reference quantity that is not affected by the IR absorption.
  • That difference S1 - S2 is normalised to the output signal S1 of the first detector (15), so that a signal S3 is obtained.
  • the sensor of this invention may be used to measure any kinds of gas such like for example nitrogen, nitric oxides, oxygen or CO, and is not even limited to measure gasses, but may also be used to measure the suspect in other forms like liquids and solids.
  • gasses such as nitrogen, nitric oxides, oxygen or CO
  • the pass bands would have to be shifted accordingly, for example the absorption band of H2O is around 2.7 ⁇ m
  • the sensor of the present invention may further comprise any possible other optical components, for example a sapphire window, that acts as additional band pass filter, reflectors, a collecting device, being a device that gathers or focuses for example IR radiation, for example a collimator, positioned upstream of the sensor, etc. It is also possible to use such a sensor directly for waste gas monitoring. For that purpose, it is installed in the chimney or exhaust. Particularly in the case of heating systems, combustion can then be controlled with the aid of the output signals of the sensor (or of a plurality of sensors).
  • a sapphire window that acts as additional band pass filter, reflectors, a collecting device, being a device that gathers or focuses for example IR radiation, for example a collimator, positioned upstream of the sensor, etc.
  • a collecting device being a device that gathers or focuses for example IR radiation, for example a collimator, positioned upstream of the sensor, etc. It is also possible to use such a sensor directly for waste gas monitoring. For
  • the senor may as well be implemented in measuring substances in general being a part of a media, where the media is not excluded to be a gas it self, but could for example be a liquid.

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Abstract

Cette invention concerne un détecteur équipé d'un ensemble filtre en aval duquel est disposé un ensemble de détection, et un dispositif d'évaluation connecté à l'ensemble de détection. Comme des particules ou des substances en général sont présentes dans le milieu de fonctionnement du capteur et entrent, au fil du temps, en contact avec les parties plus délicates de ce capteur, il importe de réduire le temps d'utilisation dudit capteur avant entretien, voire remplacement. Il est donc nécessaire dès la conception de séparer physiquement les pièces les plus délicates du capteur du milieu ou de l'environnement contenant les substances ou les espèces mesurées par le capteur. La présente invention permet de résoudre ce problème grâce au montage de regards au moins en face des parties les plus délicates du capteur, ces regards comportant généralement une ou des couches choisies en fonction de leur futur environnement de travail.
PCT/DK2010/000046 2009-04-17 2010-04-16 Détecteur de gaz avec regard de filtration Ceased WO2010118749A1 (fr)

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Cited By (8)

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WO2012126469A1 (fr) 2011-03-23 2012-09-27 Danfoss Ixa A/S Capteur de gaz doté d'un vortex
WO2012126470A1 (fr) 2011-03-23 2012-09-27 Danfoss Ixa A/S Capteur de gaz haute-température
WO2012126471A2 (fr) 2011-03-23 2012-09-27 Danfoss Ixa A/S Capteur de gaz modulaire
WO2012167805A1 (fr) * 2011-06-09 2012-12-13 Qfood Gmbh Procédé et dispositif pour la détermination de la concentration d'un analyte contenu dans un échantillon liquide
CN106461544A (zh) * 2014-04-14 2017-02-22 皇家飞利浦有限公司 气体传感器的温度补偿
DE102016108545A1 (de) * 2016-05-09 2017-11-09 Technische Universität Dresden NDIR-Gassensor und Verfahren zu dessen Kalibrierung
US10768101B2 (en) 2016-05-09 2020-09-08 Infrasolid Gmbh Measuring device and method for sensing different gases and gas concentrations
CN111957156A (zh) * 2020-08-19 2020-11-20 邢台职业技术学院 一种基于光纤传感器的空气多参数检测系统

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012126469A1 (fr) 2011-03-23 2012-09-27 Danfoss Ixa A/S Capteur de gaz doté d'un vortex
WO2012126470A1 (fr) 2011-03-23 2012-09-27 Danfoss Ixa A/S Capteur de gaz haute-température
WO2012126471A2 (fr) 2011-03-23 2012-09-27 Danfoss Ixa A/S Capteur de gaz modulaire
WO2012167805A1 (fr) * 2011-06-09 2012-12-13 Qfood Gmbh Procédé et dispositif pour la détermination de la concentration d'un analyte contenu dans un échantillon liquide
CN106461544A (zh) * 2014-04-14 2017-02-22 皇家飞利浦有限公司 气体传感器的温度补偿
DE102016108545A1 (de) * 2016-05-09 2017-11-09 Technische Universität Dresden NDIR-Gassensor und Verfahren zu dessen Kalibrierung
US10768101B2 (en) 2016-05-09 2020-09-08 Infrasolid Gmbh Measuring device and method for sensing different gases and gas concentrations
DE102016108545B4 (de) * 2016-05-09 2021-02-04 Lnfrasolid Gmbh NDIR-Gassensor und Verfahren zu dessen Kalibrierung
CN111957156A (zh) * 2020-08-19 2020-11-20 邢台职业技术学院 一种基于光纤传感器的空气多参数检测系统

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