WO2015119127A1 - Gas concentration detection device - Google Patents

Gas concentration detection device Download PDF

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Publication number
WO2015119127A1
WO2015119127A1 PCT/JP2015/053034 JP2015053034W WO2015119127A1 WO 2015119127 A1 WO2015119127 A1 WO 2015119127A1 JP 2015053034 W JP2015053034 W JP 2015053034W WO 2015119127 A1 WO2015119127 A1 WO 2015119127A1
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Prior art keywords
concentration
gas
temperature
output value
calibration curve
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PCT/JP2015/053034
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French (fr)
Japanese (ja)
Inventor
直輝 大串
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株式会社村田製作所
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Publication of WO2015119127A1 publication Critical patent/WO2015119127A1/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

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  • the present invention relates to a gas concentration detection device that detects the concentration of a gas in consideration of the temperature characteristics of the amount of infrared absorption by the gas.
  • a technique for detecting the concentration of a gas from the amount of infrared absorption of a detection target gas using a NDIR (Non-dispersive Infrared Analyzer) type (non-dispersion type) gas concentration detection device is known.
  • NDIR Non-dispersive Infrared Analyzer
  • Japanese Patent No. 4154274 Patent Document 1 uses a correction amount determined by the magnitude of the average output change rate in the temperature region between the detected temperature and the reference temperature.
  • a technique for detecting the gas concentration by correcting the detection output value is disclosed.
  • Patent Document 1 a plurality of calibration curve data for a plurality of temperatures are prepared in order to improve the detection accuracy of the gas concentration in consideration of such temperature characteristics. Therefore, there has been a problem that it takes a long time to acquire calibration curve data, or a long processing time due to a large amount of calibration curve data.
  • the present invention has been made in order to solve the above-described problems, and its purpose is to suppress the increase in the amount of data required in advance and to control the gas concentration in consideration of the temperature characteristics of the infrared absorption amount.
  • the object is to provide a gas concentration detection device that detects with high accuracy.
  • a gas concentration detection apparatus includes a concentration detection unit that outputs a signal indicating a concentration output value corresponding to a gas concentration, and a temperature detection that outputs a signal indicating a temperature output value corresponding to the temperature of the gas.
  • a calculation unit that calculates a gas concentration based on the first calibration curve shown.
  • the first calibration curve includes a correction coefficient proportional to the temperature output value.
  • the gas concentration can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared absorption by the gas. .
  • the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress an increase in the calibration curve data creation time and the amount of calibration curve data.
  • the calculation unit calculates a correction coefficient corresponding to the light absorption rate by the gas that varies inversely with the temperature change of the gas.
  • the gas concentration can be calculated with high accuracy.
  • the calculation unit calculates the reference output value based on the temperature output value and a second calibration curve indicating the relationship of the reference output value to the temperature output value.
  • the gas concentration can be calculated with higher accuracy using the calculated reference output value.
  • the second calibration curve is set by deriving an approximate expression of a predetermined order based on a plurality of concentration output values acquired in advance corresponding to each of a plurality of gas temperatures at the reference concentration.
  • the gas concentration can be calculated with higher accuracy based on the second calibration curve.
  • the first calibration curve derives an approximate expression of a predetermined order multiplied by a correction coefficient based on a plurality of concentration output values acquired in advance corresponding to each of the plurality of concentrations of the gas at the reference temperature. Is set.
  • the gas concentration can be calculated with higher accuracy based on the first calibration curve.
  • the concentration detection unit is provided between the light receiving sensor and the light source, an optical path portion into which the gas to be detected is introduced, a light source that emits infrared light, a light receiving sensor that detects infrared light emitted from the light source, and the light receiving sensor.
  • Bandpass filter is provided between the light receiving sensor and the light source, an optical path portion into which the gas to be detected is introduced, a light source that emits infrared light, a light receiving sensor that detects infrared light emitted from the light source, and the light receiving sensor.
  • the gas concentration can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared absorption by the gas. .
  • the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress an increase in the calibration curve data creation time and the amount of calibration curve data. Therefore, it is possible to provide a gas concentration detection device that can suppress an increase in a necessary data amount in advance and detect a gas concentration with high accuracy in consideration of a temperature characteristic of an infrared absorption amount.
  • FIG. 1 shows the structure of the gas concentration detection apparatus which concerns on this Embodiment. It is a circuit block diagram of the gas concentration detection apparatus which concerns on this Embodiment. It is a figure for demonstrating the 1st calibration curve in reference
  • FIG. 6A is a diagram illustrating an error of a detection value with respect to the concentration under a plurality of temperature environments according to the comparative example.
  • FIG. 6B is a diagram illustrating an error of a detection value with respect to the concentration under a plurality of temperature environments in the present embodiment.
  • FIG. 1 is a diagram showing a configuration of a gas concentration detection apparatus 10 according to the present embodiment.
  • the configuration of the gas concentration detection device 10 shown in FIG. 1 is an example, and is not particularly limited to the configuration shown in FIG.
  • the gas concentration detection device 10 is an infrared absorption (NDIR) gas sensor.
  • NDIR infrared absorption
  • the gas that is a concentration detection target by the gas concentration detection apparatus 10 in the present embodiment will be described as being carbon dioxide, the gas that is the detection target is not particularly limited to carbon dioxide.
  • the gas concentration detection device 10 is, for example, a ventilation control based on the carbon dioxide concentration in a BEMS (Building Energy Management System), a control for keeping the indoor carbon dioxide concentration within a predetermined range in a plant cultivation facility, or the like. Used for.
  • BEMS Building Energy Management System
  • the gas concentration detection device 10 includes a concentration detection unit 30 that performs a gas concentration detection operation, a thermistor 28 that is a temperature detection unit that detects the temperature of the gas, lighting control and concentration of the light source 20. And a drive circuit 40 for performing predetermined processing on the gas concentration detection signal output from the detection unit 30 and the temperature detection signal output from the thermistor 28.
  • a concentration detection unit 30 that performs a gas concentration detection operation
  • a thermistor 28 that is a temperature detection unit that detects the temperature of the gas, lighting control and concentration of the light source 20.
  • a drive circuit 40 for performing predetermined processing on the gas concentration detection signal output from the detection unit 30 and the temperature detection signal output from the thermistor 28.
  • Each of the component parts of the concentration detection unit 30 and the thermistor 28 is provided at a predetermined position on one surface of the circuit board 12.
  • the components of the drive circuit 40 are provided at predetermined positions on the circuit board 12.
  • the concentration detector 30 includes a light source 20, a holding base 22, a pyroelectric sensor 24, and an optical filter 26 as components.
  • the light source 20 is provided at a position separated from the pyroelectric sensor 24 by a predetermined distance.
  • An optical path 18 is provided between the light source 20 and the pyroelectric sensor 24.
  • the light source 20 emits infrared rays toward the pyroelectric sensor 24.
  • the light source 20 is described as being a filament lamp, for example, but may be a light source that emits infrared rays, such as an LED (Light Emitting Diode).
  • the light source 20 is held by a holding table 22 fixed to the circuit board 12.
  • the light source 20 is controlled to blink at a predetermined cycle.
  • the cross-sectional shape of the holding table 22 has a semi-elliptical shape opened to the pyroelectric sensor 24 side.
  • a mirror surface is formed inside the semi-elliptical shape. That is, the holding table 22 is an elliptical mirror.
  • the light source 20 is provided at a semi-elliptical focal position of the holding table 22. Therefore, the infrared rays radiated from the light source 20 pass through the optical path 18 and enter the pyroelectric sensor 24 directly, or reflect the mirror surface formed on the holding base 22 and then pass through the optical path 18. Or incident on the pyroelectric sensor 24.
  • the pyroelectric sensor 24 is a pyroelectric infrared sensor using bulk ceramics.
  • the pyroelectric sensor 24 is provided with an incident window, which is a part that receives infrared rays emitted from the light source 20, facing the light source 20.
  • An optical filter 26 is provided in the incident window.
  • the optical filter 26 is, for example, a bandpass filter that passes infrared rays in a predetermined wavelength band.
  • the predetermined wavelength band is, for example, a wavelength band including the vicinity of 4.26 ⁇ m, which is an infrared wavelength having a high absorption rate by carbon dioxide molecules.
  • the predetermined wavelength band has a wavelength corresponding to the type of gas that is the concentration detection target (that is, the absorption rate of the gas that is the concentration detection target is high).
  • a wavelength band based on (wavelength) is selected. That is, the pyroelectric sensor 24 receives infrared rays in a predetermined wavelength band among infrared rays emitted from the light source 20.
  • the thermistor 28 is provided around the pyroelectric sensor 24 and is fixed to the circuit board 12. In the thermistor 28, a constant current flows when a voltage is applied from the drive circuit 40, and a voltage generated when the constant current flows is detected in the drive circuit 40 as an output voltage.
  • the cover 14 is provided so as to cover the components of the concentration detection unit 30 and the thermistor 28, and is fixed to the circuit board 12.
  • the cover 14 is provided with an intake port 16 for taking in gas from the outside of the cover 14 and discharging gas inside the cover 14.
  • the intake port 16 is provided with an air filter.
  • the detection of the concentration of carbon dioxide by the gas concentration detection device 10 is performed in a state where gas is taken into the cover 14 from the intake port 16.
  • the pyroelectric sensor 24 When infrared rays are emitted from the light source 20 toward the pyroelectric sensor 24, the emitted infrared rays are received by the pyroelectric sensor 24.
  • the pyroelectric sensor 24 outputs a voltage in response to infrared light reception. At this time, the output voltage varies depending on the concentration and temperature of carbon dioxide in the optical path section 18.
  • the optical filter 26 since the optical filter 26 transmits infrared rays having a wavelength with high carbon dioxide absorption, it is possible to convert the output value of the pyroelectric sensor 24 into the concentration of carbon dioxide.
  • FIG. 2 is a circuit configuration diagram of the gas concentration detection apparatus 10 according to the present embodiment.
  • the drive circuit 40 includes an amplifier circuit 42, an AD conversion circuit 44, and a density conversion processing circuit 46.
  • the density conversion processing circuit 46 corresponds to a calculation unit in the claims of the present application.
  • the circuit configuration of the gas concentration detection apparatus 10 shown in FIG. 2 is an example, and is not limited to the circuit configuration shown in FIG.
  • the amplifying circuit 42 is configured by, for example, an amplifier, and amplifies the signal strength of the concentration detection signal (output voltage) of the concentration detector 30 and the signal strength of the temperature detection signal (output voltage) of the thermistor 28.
  • the AD conversion circuit 44 converts the analog signal whose signal intensity is amplified in the amplification circuit 42 into a digital signal.
  • a well-known technique may be used for amplification of signal intensity and conversion from an analog signal to a digital signal.
  • the concentration conversion processing circuit 46 performs a predetermined process on the digital signal converted by the AD conversion circuit 44 to detect the concentration C of carbon dioxide contained in the gas introduced into the cover 14.
  • the density conversion processing circuit 46 is realized by, for example, a CPU (Central Processing Unit).
  • the CPU executes predetermined arithmetic processing and control processing by executing a program stored in a storage unit (not shown). For example, the CPU executes a control process for lighting the light source 20 and a control process for applying a voltage to the thermistor 28 in addition to a calculation process for calculating the concentration of carbon dioxide.
  • the detection of the concentration of carbon dioxide in the gas concentration detection apparatus 10 is performed in the following procedure.
  • a temperature detection signal is acquired from the thermistor 28.
  • the light source 20 is turned on.
  • the output value V of the pyroelectric sensor 24 is acquired.
  • Predetermined signal processing is executed on the acquired output value V of the pyroelectric sensor 24.
  • the output value V of the pyroelectric sensor 24 corresponds to the concentration output value of the present invention. Further, the temperature detection signal of the thermistor 28 corresponds to the temperature output value of the present invention.
  • the predetermined signal processing includes, for example, processing for removing noise from the output waveform of the pyroelectric sensor 24 using a moving average method, processing for amplifying the signal intensity by the amplifier circuit 42, and digital data by the AD conversion circuit 44. And the process of converting to. These processes are also performed on the temperature detection signal. Further, the thermistor temperature Th [K] is calculated from the temperature detection signal. The calculation of the thermistor temperature Th may be performed in the above (1).
  • the concentration C of carbon dioxide is calculated from the thermistor temperature Th and the output value V of the pyroelectric sensor 24.
  • the light source 20 is turned off.
  • the gas concentration detection apparatus 10 performs the processes (1) to (6) at regular intervals, for example.
  • the concentration conversion processing circuit 46 calculates the concentration of carbon dioxide based on the output value V of the pyroelectric sensor 24, the first calibration curve obtained in advance, the thermistor temperature Th, and the second calibration curve.
  • the data relating to the first calibration curve and the data relating to the second calibration curve are acquired in advance at the time of manufacturing the gas concentration detection device 10 and stored in a storage medium such as a memory provided in the drive circuit 40.
  • the first calibration curve indicates the relationship between the carbon dioxide concentration C and the output value V of the pyroelectric sensor 24 at a predetermined reference temperature (for example, 25 ° C.). More specifically, the first calibration curve shows the relationship between the value (V / V0) obtained by normalizing the output value V of the pyroelectric sensor 24 with the reference output value V0 and the concentration C of carbon dioxide. An output value of the pyroelectric sensor 24 corresponding to each of the plurality of carbon dioxide concentrations at the reference temperature is acquired in advance, and the first calibration curve is based on the output values of the plurality of pyroelectric sensors 24 acquired in advance. Thus, an approximate expression of a predetermined order multiplied by the correction coefficient ⁇ is derived and set.
  • the reference output value V0 is an output value of the pyroelectric sensor 24 corresponding to the thermistor temperature Th when the concentration of carbon dioxide is a predetermined reference concentration (for example, 0 ppm).
  • the reference output value V0 is calculated using a second calibration curve described later based on the thermistor temperature Th.
  • the first calibration curve is represented by the following equation.
  • C (carbon dioxide concentration) ⁇ (correction coefficient) ⁇ f1 (V / V0) (Equation 1)
  • F1 in the above (Expression 1) is a function of a predetermined order, and may be, for example, a quadratic function or a cubic function.
  • f1 is a cubic function
  • the gas concentration C is expressed by the following equation.
  • a1 to a4 are calculated based on a combination of the concentrations of a plurality of types of carbon dioxide and the output value of the pyroelectric sensor 24 obtained in advance through experiments or the like at the reference temperature. For example, as shown in FIG.
  • output values of a plurality of pyroelectric sensors 24 respectively corresponding to a plurality of predetermined carbon dioxide concentrations (for example, concentrations of 0 ppm, 400 ppm, 1000 ppm, and 2000 ppm) at the reference temperature are obtained in advance.
  • A1 to a4 are calculated based on the acquired output values acquired by experiments or the like.
  • Equation 2 The above (Equation 2) and the calculated values of a1 to a4 are stored in a storage medium such as a memory provided in the drive circuit 40.
  • Th 25 indicates the thermistor temperature [K] at 25 ° C. That is, the correction coefficient ⁇ is proportional to the temperature output value.
  • B represents a constant
  • Vth represents the output voltage of the thermistor 28
  • Vcc represents the voltage applied from the drive circuit 40 to the thermistor 28.
  • the above (Equation 3) and the constant B are stored in a storage medium such as a memory provided in the drive circuit 40.
  • the correction coefficient ⁇ is a coefficient proportional to the thermistor temperature Th.
  • the correction coefficient ⁇ is stored in a storage medium such as a memory provided in the drive circuit 40.
  • the first calibration curve expressed by the above is indicated by a solid line in FIG.
  • the horizontal axis of FIG. 4 indicates the carbon dioxide concentration C
  • the vertical axis of FIG. 4 indicates the normalized value (V / V0).
  • the concentration C and the normalized value (V / V0) are normalized as the concentration C increases, the normalized value (V / V0) decreases, and the concentration C decreases.
  • the value (V / V0) has an increasing relationship.
  • the correction coefficient ⁇ is set in consideration of the temperature characteristics of the amount of absorption by which carbon dioxide absorbs infrared rays.
  • the molar concentration n (mol / l), which means the number of molecules of carbon dioxide, follows the gas equation of state (PV nRT). Therefore, in an environment where the pressure P and the volume V are constant, the temperature Proportional to inverse (inversely proportional to temperature). Therefore, even in an environment with the same carbon dioxide concentration, the amount of absorbed infrared light decreases between the temperature of the gas containing carbon dioxide and the amount of absorbed infrared light as the temperature of the gas containing carbon dioxide increases. There is a relationship in which the amount of infrared absorption increases as the temperature of the gas containing carbon dioxide decreases.
  • the output value V of the pyroelectric sensor 24 is changed to a value higher than the original output value when the infrared absorption amount is decreased. Therefore, the output value V of the pyroelectric sensor 24 is converted to a value lower than the original density.
  • the output value V of the pyroelectric sensor 24 changes to a value lower than the original output value. Therefore, the output value V of the pyroelectric sensor 24 is converted to a value higher than the original density.
  • the concentration of carbon dioxide to be calculated is the ratio of the volume of carbon dioxide gas to the volume inside the cover 14, the relationship between the temperature and the concentration to be calculated differs from the relationship between the temperature and the molar concentration n.
  • FIG. 5 shows the relationship between the wavelength of infrared rays emitted from the light source and the absorption rate of infrared rays by carbon dioxide molecules.
  • the vertical axis in FIG. 5 indicates the infrared absorption rate, and the horizontal axis in FIG. 5 indicates the infrared wavelength.
  • the infrared absorption rate indicates the amount of infrared absorption at a specific wavelength.
  • the thick solid line in FIG. 5 is an absorption spectrum when the gas concentration is ⁇ 50 ° C.
  • the thick broken line in FIG. 5 is an absorption spectrum when the gas concentration is 0 ° C.
  • the thin solid line in FIG. 5 is an absorption spectrum when the gas temperature is 25 ° C.
  • the thin broken line in FIG. 5 is an absorption spectrum when the gas temperature is 50 ° C.
  • the dashed-dotted line in FIG. 5 is an absorption spectrum when the gas temperature is 100 ° C.
  • the concentration of carbon dioxide can be calculated with higher accuracy by setting the correction coefficient ⁇ in consideration of the temperature characteristics of the amount of absorption by which carbon dioxide absorbs infrared rays.
  • the absorption ratio B / A (absorption amount B is the absorption amount A) between the infrared absorption amount A at a predetermined reference temperature Ta (for example, 25 ° C.) and the infrared absorption amount B at the temperature Tb.
  • the normalized value is similar to the reciprocal Ta / Tb of the temperature ratio. That is, the error in the density C occurs in proportion to Ta / Tb.
  • the correction coefficient ⁇ may be a coefficient proportional to the temperature, and is not particularly limited to the above formula, and may be adjusted by experiments or the like.
  • the first calibration curve is corrected by the correction coefficient ⁇ . For example, when the thermistor temperature Th is 50 ° C., the first calibration curve is located above the first calibration curve (solid line in FIG. 4) at the reference temperature (25 ° C.) as shown by the broken line in FIG. Since it is located, the density is corrected downward. Further, when the thermistor temperature Th is 0 ° C., the first calibration curve is located below the first calibration curve at the reference temperature as shown by the one-dot chain line in FIG. Is done.
  • the gas concentration can be calculated with high accuracy in consideration of the temperature characteristic of the infrared absorption amount.
  • the concentration conversion processing circuit 46 calculates the reference output value V0 using the second calibration curve.
  • the second calibration curve shows the relationship between the thermistor temperature Th and the reference output value V0 at a predetermined reference concentration (for example, 0 ppm).
  • the second calibration curve is set by deriving an approximate expression of a predetermined order based on the output values of the plurality of pyroelectric sensors 24 acquired in advance corresponding to each of the plurality of carbon dioxide temperatures at the reference concentration. .
  • the second calibration curve is represented by the following equation.
  • V0 f2 (Th) (Formula 4)
  • F2 in the above (Formula 4) is a function of a predetermined order, and may be, for example, a cubic function or a quartic function.
  • f2 is a quartic function
  • the reference output value V0 is expressed by the following equation.
  • V0 b1 ⁇ Th 4 + b2 ⁇ Th 3 + b3 ⁇ Th 2 + b4 ⁇ Th + b5 (Formula 5)
  • b1 to b5 are calculated based on a combination of a plurality of types of temperatures (thermistor temperature Th) obtained in advance by experiments or the like at the reference concentration and the output value of the pyroelectric sensor 24.
  • the gas concentration detection device 10 replaces a plurality of types of temperatures (thermistor temperature Th) previously acquired by experiments or the like at the reference concentration with the voltage values of a plurality of types of temperatures previously acquired by experiments or the like at the reference concentration (thermistor temperature Th).
  • the output voltage Vth of the thermistor may be used. That is, the reference output value V0 may be obtained from the output voltage Vth of the thermistor. Therefore, in the above (Formula 4) and (Formula 5), Th may be replaced with Vth.
  • the output values of a plurality of pyroelectric sensors 24 respectively corresponding to a plurality of temperatures (for example, 0 ° C., 10 ° C., 25 ° C., 40 ° C., and 50 ° C.) at the reference concentration are previously tested.
  • b1 to b4 are calculated based on the acquired output values.
  • the pyroelectric infrared sensor used in the experimental example is E472SW1 manufactured by Murata Manufacturing Co., Ltd., but generally the same effect can be obtained if the infrared sensor uses bulk piezoelectric ceramics or MEMS (Micro Electro Mechanical Systems). Is expected to be obtained.
  • FIG. 6 (A) shows errors in detection values corresponding to concentrations in a plurality of temperature environments when the correction coefficient ⁇ is not included in the first calibration curve.
  • the vertical axis in FIG. 6A indicates an error, and with 0 as a reference, the upward direction in FIG. 6A is a positive direction, and the downward direction in FIG. 6A is a negative direction.
  • the horizontal axis of FIG. 6A shows the concentration of carbon dioxide.
  • the broken line in FIG. 6 (A) shows the relationship between error and concentration when the temperature (thermistor temperature Th) is 0 ° C.
  • the solid line in FIG. 6A shows the relationship between error and concentration when the temperature is 25 ° C. (reference temperature).
  • the dashed line in FIG. 6A shows the relationship between error and concentration when the temperature is 50 ° C.
  • the error in concentration corresponding to each of the plurality of concentrations is almost zero. This is because the first calibration curve is set based on the output value (actually measured value) of the pyroelectric sensor 24 corresponding to each of a plurality of concentrations at the reference temperature.
  • the output value of the pyroelectric sensor 24 is the original value. It changes to a higher side than the output value (the output value of the pyroelectric sensor 24 for the same density when the temperature is 25 ° C.). For this reason, an error in density occurs on the lower side than an error in density when the temperature is 25 ° C.
  • the infrared absorption amount increases more than the infrared absorption amount when the temperature is 25 ° C. Therefore, the output value of the pyroelectric sensor 24 is higher than the original output value. Also changes to the lower side. For this reason, an error in density occurs on the higher side than an error in density when the temperature is 25 ° C.
  • FIG. 6 (B) shows errors in detected values corresponding to concentrations in a plurality of temperature environments when the correction coefficient ⁇ is included in the first calibration curve.
  • the vertical axis in FIG. 6B represents an error, and with 0 as a reference, the upward direction in FIG. 6B is the positive direction, and the downward direction in FIG. 6B is the negative direction.
  • the horizontal axis in FIG. 6B indicates the concentration of carbon dioxide. Note that the vertical scale in FIG. 6A and the vertical scale in FIG. 6B are the same.
  • the broken line in FIG. 6B shows the relationship between the error and the concentration when the temperature (thermistor temperature Th) is 0 ° C.
  • the solid line in FIG. 6B shows the relationship between error and concentration when the temperature is 25 ° C.
  • the alternate long and short dash line in FIG. 6B shows the relationship between the error and the concentration when the temperature is 50 ° C.
  • the correction coefficient ⁇ proportional to the thermistor temperature Th can be included in the first calibration curve, and therefore the infrared ray proportional to the inverse of the thermistor temperature Th. It is possible to correct the density error caused by the change in the amount of absorption. Therefore, the concentration C of carbon dioxide can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared rays absorbed by carbon dioxide.
  • the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress the time for creating the calibration curve data and the increase in the data amount of the calibration curve data. Therefore, it is possible to provide a gas concentration detection device that can suppress an increase in a necessary data amount in advance and detect a gas concentration with high accuracy in consideration of a temperature characteristic of an infrared absorption amount.
  • a value corresponding to the amount of infrared rays absorbed by the gas that changes in inverse proportion to the change in the thermistor temperature Th specifically, a value Th / standardized by the thermistor temperature Th 25 of the reference temperature (25 ° C.).
  • the reference output value V0 corresponding to the thermistor temperature Th can be calculated based on the second calibration curve, the carbon dioxide concentration C is calculated using the first calibration curve and the calculated reference output value V0. It is possible to calculate with high accuracy.
  • the carbon dioxide concentration C can be calculated using the first calibration curve represented by (Equation 1) and the second calibration curve represented by (Equation 4) including the correction coefficient ⁇ , data acquired in advance While suppressing an increase in the amount, the calculation load can be reduced. Moreover, the increase in the manufacturing cost and design cost of a product can be suppressed by suppressing the increase in the data acquired beforehand and reducing the calculation load.
  • the output values of the pyroelectric sensor 24 corresponding to each concentration are acquired in advance by using four concentrations of 0 ppm, 400 ppm, 1000 ppm, and 2000 ppm as measurement points.
  • the a1 to a4 of the first calibration curve are calculated using the output values, but for example, the output values of the pyroelectric sensor 24 corresponding to the concentrations of four or more points may be acquired in advance, The output value of the pyroelectric sensor 24 corresponding to the density of the measurement points other than the above four points may be acquired in advance, or a plurality of pyroelectrics corresponding to a plurality of densities having a density higher or lower than 2000 ppm as an upper limit value. The output value of the electric sensor 24 may be acquired in advance.
  • pyroelectric sensors corresponding to each temperature are measured at five temperatures of 0 ° C., 10 ° C., 25 ° C., 40 ° C., and 50 ° C.
  • the output values of 24 are acquired in advance, and b1 to b5 of the second calibration curve are calculated using the acquired output values.
  • the output of the pyroelectric sensor 24 corresponding to a temperature of 5 points or more is used.
  • the value may be acquired in advance, the output value of the pyroelectric sensor 24 corresponding to the temperature of the measurement point other than the above five points may be acquired in advance, or a temperature higher or lower than 50 ° C.
  • Output values of a plurality of pyroelectric sensors 24 corresponding to a plurality of temperatures may be acquired in advance, or a plurality of pyroelectrics corresponding to a plurality of temperatures having a lower value or a value lower than 0 ° C. Even if the output value of the sensor 24 is acquired in advance There.
  • each of the concentration measurement points is set to 0, R / 4, R / 2, and R when the measurement range is 0 to R.
  • the correction coefficient ⁇ is proportional to the temperature output value, but is not limited thereto.
  • the correction coefficient ⁇ may be proportional to the power of the temperature output signal.

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Abstract

　This gas concentration detection device (10) is provided with: a concentration detection unit (30) for outputting a signal indicating a concentration output value in accordance with the concentration of a gas; a thermistor (28) for outputting a signal indicating a temperature output value in accordance with the temperature of a gas; and a concentration conversion process circuit for computing standard output values that correspond to temperature output values at predetermined standard concentrations of a gas, and computing the concentration of the gas on the basis of a first calibration curve indicating a relationship between values obtained through normalization of concentration output values by standard output values, and the concentration of gas with respect to the normalized values. The first calibration curve includes a correction coefficient that is proportional to the output temperature value.

Description

ガス濃度検出装置Gas concentration detector
　本発明は、ガスによる赤外線の吸収量の温度特性を考慮してガスの濃度を検出するガス濃度検出装置に関する。 The present invention relates to a gas concentration detection device that detects the concentration of a gas in consideration of the temperature characteristics of the amount of infrared absorption by the gas.
　たとえば、ＮＤＩＲ（Non-dispersive　Infrared　Analyzer）型（非分散型）のガス濃度検出装置を用いて、検出対象のガスの赤外線の吸収量から当該ガスの濃度を検出する技術が公知である。このようなガス濃度検出装置として、たとえば、特許第４１５４２７４号公報（特許文献１）には、検出温度と基準温度との間の温度領域における平均出力変化率の大きさによって定められる補正量を用いて検出出力値を補正してガス濃度を検出する技術が開示される。 For example, a technique for detecting the concentration of a gas from the amount of infrared absorption of a detection target gas using a NDIR (Non-dispersive Infrared Analyzer) type (non-dispersion type) gas concentration detection device is known. As such a gas concentration detection device, for example, Japanese Patent No. 4154274 (Patent Document 1) uses a correction amount determined by the magnitude of the average output change rate in the temperature region between the detected temperature and the reference temperature. A technique for detecting the gas concentration by correcting the detection output value is disclosed.
特許第４１５４２７４号公報Japanese Patent No. 4154274
　ところで、ガスによる赤外線の吸収量は温度によって変化するため、ガス濃度を精度高く検出するためには、そのような温度特性を考慮する必要がある。特許文献１においては、そのような温度特性を考慮してガス濃度の検出精度を向上させるために、複数の温度に対する複数の検量線データを用意している。そのため、検量線データの取得に長時間を要したり、あるいは、検量線データのデータ量が多いため処理時間に長時間を要したりするという問題があった。 Incidentally, since the amount of infrared rays absorbed by the gas varies depending on the temperature, it is necessary to consider such temperature characteristics in order to detect the gas concentration with high accuracy. In Patent Document 1, a plurality of calibration curve data for a plurality of temperatures are prepared in order to improve the detection accuracy of the gas concentration in consideration of such temperature characteristics. Therefore, there has been a problem that it takes a long time to acquire calibration curve data, or a long processing time due to a large amount of calibration curve data.
　本発明は、上述した課題を解決するためになされたものであって、その目的は、予め必要なデータ量の増加を抑制するとともに、赤外線の吸収量の温度特性を考慮してガスの濃度を精度高く検出するガス濃度検出装置を提供することである。 The present invention has been made in order to solve the above-described problems, and its purpose is to suppress the increase in the amount of data required in advance and to control the gas concentration in consideration of the temperature characteristics of the infrared absorption amount. The object is to provide a gas concentration detection device that detects with high accuracy.
　この発明のある局面に係るガス濃度検出装置は、ガスの濃度に応じた濃度出力値を示す信号を出力する濃度検出部と、ガスの温度に応じた温度出力値を示す信号を出力する温度検出部と、予め定められたガスの基準濃度において温度出力値に対応する基準出力値を算出し、濃度出力値を基準出力値で規格化した値、および規格化した値に対するガスの濃度の関係を示す第１検量線に基づいてガスの濃度を算出する算出部とを備える。第１検量線は、温度出力値に比例する補正係数を含む。 A gas concentration detection apparatus according to an aspect of the present invention includes a concentration detection unit that outputs a signal indicating a concentration output value corresponding to a gas concentration, and a temperature detection that outputs a signal indicating a temperature output value corresponding to the temperature of the gas. A reference output value corresponding to the temperature output value at a predetermined gas reference concentration, a value obtained by normalizing the concentration output value with the reference output value, and a relationship of the gas concentration with respect to the normalized value. A calculation unit that calculates a gas concentration based on the first calibration curve shown. The first calibration curve includes a correction coefficient proportional to the temperature output value.
　このようにすると、第１検量線にガスの温度に比例する補正係数を含めることができるので、ガスによる赤外線の吸収量の温度特性を考慮して、ガスの濃度を精度高く算出することができる。また、複数の温度に対する検量線データを減少させることができるため、検量線データの作成時間、および検量線データのデータ量の増大を抑制できる。 In this way, since the correction coefficient proportional to the gas temperature can be included in the first calibration curve, the gas concentration can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared absorption by the gas. . In addition, since the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress an increase in the calibration curve data creation time and the amount of calibration curve data.
　好ましくは、算出部は、ガスの温度変化に反比例して変化するガスによる光の吸収率に応じた補正係数を算出する。 Preferably, the calculation unit calculates a correction coefficient corresponding to the light absorption rate by the gas that varies inversely with the temperature change of the gas.
　このようにすると、補正係数によって、ガスの温度の逆数に比例する赤外線の吸収量の変化によって生じる濃度の誤差を補正することができる。そのため、ガスの濃度を精度高く算出することができる。 In this way, it is possible to correct the concentration error caused by the change in the amount of absorbed infrared light in proportion to the reciprocal of the gas temperature by the correction coefficient. Therefore, the gas concentration can be calculated with high accuracy.
　さらに好ましくは、算出部は、温度出力値、および温度出力値に対する基準出力値の関係を示す第２検量線に基づいて基準出力値を算出する。 More preferably, the calculation unit calculates the reference output value based on the temperature output value and a second calibration curve indicating the relationship of the reference output value to the temperature output value.
　このようにすると、第２検量線に基づいて基準出力値を算出することができるため、算出された基準出力値を用いてガスの濃度をより精度高く算出することができる。 In this manner, since the reference output value can be calculated based on the second calibration curve, the gas concentration can be calculated with higher accuracy using the calculated reference output value.
　さらに好ましくは、第２検量線は、基準濃度におけるガスの複数の温度の各々に対応した、予め取得された複数の濃度出力値に基づいて所定の次数の近似式を導出して設定される。 More preferably, the second calibration curve is set by deriving an approximate expression of a predetermined order based on a plurality of concentration output values acquired in advance corresponding to each of a plurality of gas temperatures at the reference concentration.
　このようにすると、第２検量線に基づいてガスの濃度をより精度高く算出することができる。 In this way, the gas concentration can be calculated with higher accuracy based on the second calibration curve.
　さらに好ましくは、第１検量線は、基準温度におけるガスの複数の濃度の各々に対応した、予め取得された複数の濃度出力値に基づいて補正係数が乗算された所定の次数の近似式を導出して設定される。 More preferably, the first calibration curve derives an approximate expression of a predetermined order multiplied by a correction coefficient based on a plurality of concentration output values acquired in advance corresponding to each of the plurality of concentrations of the gas at the reference temperature. Is set.
　このようにすると、第１検量線に基づいてガスの濃度をより精度高く算出することができる。 In this way, the gas concentration can be calculated with higher accuracy based on the first calibration curve.
　さらに好ましくは、濃度検出部は、検出対象のガスが導入される光路部と、赤外線を放射する光源と、光源から放射された赤外線を検出する受光センサと、受光センサと光源との間に設けられるバンドパスフィルタとを含む。 More preferably, the concentration detection unit is provided between the light receiving sensor and the light source, an optical path portion into which the gas to be detected is introduced, a light source that emits infrared light, a light receiving sensor that detects infrared light emitted from the light source, and the light receiving sensor. Bandpass filter.
　この発明によると、第１検量線にガスの温度に比例する補正係数を含めることができるので、ガスによる赤外線の吸収量の温度特性を考慮して、ガスの濃度を精度高く算出することができる。また、複数の温度に対する検量線データを減少させることができるため、検量線データの作成時間、および検量線データのデータ量の増大を抑制できる。したがって、予め必要なデータ量の増加を抑制するとともに、赤外線の吸収量の温度特性を考慮してガスの濃度を精度高く検出するガス濃度検出装置を提供することができる。 According to the present invention, since the correction coefficient proportional to the gas temperature can be included in the first calibration curve, the gas concentration can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared absorption by the gas. . In addition, since the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress an increase in the calibration curve data creation time and the amount of calibration curve data. Therefore, it is possible to provide a gas concentration detection device that can suppress an increase in a necessary data amount in advance and detect a gas concentration with high accuracy in consideration of a temperature characteristic of an infrared absorption amount.
本実施の形態に係るガス濃度検出装置の構成を示す図である。It is a figure which shows the structure of the gas concentration detection apparatus which concerns on this Embodiment. 本実施の形態に係るガス濃度検出装置の回路構成図である。It is a circuit block diagram of the gas concentration detection apparatus which concerns on this Embodiment. 基準温度における第１検量線と、基準濃度における第２検量線とを説明するための図である。It is a figure for demonstrating the 1st calibration curve in reference | standard temperature, and the 2nd calibration curve in reference | standard density | concentration. 複数の温度環境下での濃度に対する第１検量線に基づく出力値を示す図である。It is a figure which shows the output value based on the 1st calibration curve with respect to the density | concentration in a several temperature environment. 赤外線の波長と二酸化炭素分子による赤外線の吸収率との関係を示す図である。It is a figure which shows the relationship between the wavelength of infrared rays, and the absorption factor of the infrared rays by a carbon dioxide molecule. 図６（Ａ）は比較例に係る複数の温度環境下での濃度に対する検出値の誤差を示す図である。図６（Ｂ）は、本実施の形態における複数の温度環境下での濃度に対する検出値の誤差を示す図である。FIG. 6A is a diagram illustrating an error of a detection value with respect to the concentration under a plurality of temperature environments according to the comparative example. FIG. 6B is a diagram illustrating an error of a detection value with respect to the concentration under a plurality of temperature environments in the present embodiment.
　以下、図面を参照しつつ、本発明の実施の形態について説明する。以下の説明では、同一の部品には同一の符号が付されている。それらの名称および機能も同じである。したがってそれらについての詳細な説明は繰返されない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.
　図１は、本実施の形態に係るガス濃度検出装置１０の構成を示す図である。なお、図１に示すガス濃度検出装置１０の構成は、一例であり、図１に示される構成に特に限定されるものではない。 FIG. 1 is a diagram showing a configuration of a gas concentration detection apparatus 10 according to the present embodiment. The configuration of the gas concentration detection device 10 shown in FIG. 1 is an example, and is not particularly limited to the configuration shown in FIG.
　本実施の形態において、ガス濃度検出装置１０は、赤外線吸収方式（ＮＤＩＲ）のガスセンサである。本実施の形態におけるガス濃度検出装置１０による濃度の検出対象となる気体は、二酸化炭素であるものとして説明するが、検出対象となる気体は、二酸化炭素に特に限定されるものではない。 In the present embodiment, the gas concentration detection device 10 is an infrared absorption (NDIR) gas sensor. Although the gas that is a concentration detection target by the gas concentration detection apparatus 10 in the present embodiment will be described as being carbon dioxide, the gas that is the detection target is not particularly limited to carbon dioxide.
　ガス濃度検出装置１０は、たとえば、ＢＥＭＳ（Building　Energy　Management　System）において二酸化炭素の濃度に基づく換気量の制御や、植物の栽培施設等において屋内の二酸化炭素の濃度を所定の範囲内に収める制御等に用いられる。 The gas concentration detection device 10 is, for example, a ventilation control based on the carbon dioxide concentration in a BEMS (Building Energy Management System), a control for keeping the indoor carbon dioxide concentration within a predetermined range in a plant cultivation facility, or the like. Used for.
　図１に示すように、ガス濃度検出装置１０は、ガスの濃度の検出動作を行う濃度検出部３０と、ガスの温度を検出する温度検出部であるサーミスタ２８と、光源２０の点灯制御、濃度検出部３０から出力されるガス濃度検出信号、およびサーミスタ２８から出力される温度検出信号に対して所定の処理を行うための駆動回路４０とを含む。濃度検出部３０の構成部品およびサーミスタ２８の各々は、回路基板１２の一方の面上の所定の位置に設けられる。駆動回路４０の構成部品は、回路基板１２の所定の位置に設けられる。 As shown in FIG. 1, the gas concentration detection device 10 includes a concentration detection unit 30 that performs a gas concentration detection operation, a thermistor 28 that is a temperature detection unit that detects the temperature of the gas, lighting control and concentration of the light source 20. And a drive circuit 40 for performing predetermined processing on the gas concentration detection signal output from the detection unit 30 and the temperature detection signal output from the thermistor 28. Each of the component parts of the concentration detection unit 30 and the thermistor 28 is provided at a predetermined position on one surface of the circuit board 12. The components of the drive circuit 40 are provided at predetermined positions on the circuit board 12.
　濃度検出部３０は、光源２０と、保持台２２と、焦電センサ２４と、光学フィルタ２６とを構成部品として含む。 The concentration detector 30 includes a light source 20, a holding base 22, a pyroelectric sensor 24, and an optical filter 26 as components.
　光源２０は、焦電センサ２４と所定の距離だけ離隔した位置に設けられる。光源２０と焦電センサ２４との間には光路部１８が設けられる。光源２０は、焦電センサ２４に向けて赤外線を放射する。本実施の形態において、光源２０は、たとえば、フィラメントランプであるものとして説明するが、たとえば、ＬＥＤ（Light　Emitting　Diode）等の赤外線を放射する光源であってもよい。光源２０は、回路基板１２に固定された保持台２２によって保持される。光源２０は、所定の周期で点滅するように制御される。 The light source 20 is provided at a position separated from the pyroelectric sensor 24 by a predetermined distance. An optical path 18 is provided between the light source 20 and the pyroelectric sensor 24. The light source 20 emits infrared rays toward the pyroelectric sensor 24. In the present embodiment, the light source 20 is described as being a filament lamp, for example, but may be a light source that emits infrared rays, such as an LED (Light Emitting Diode). The light source 20 is held by a holding table 22 fixed to the circuit board 12. The light source 20 is controlled to blink at a predetermined cycle.
　保持台２２の断面形状は、焦電センサ２４側に開いた半楕円形状を有する。半楕円形状の内側は、鏡面が形成される。すなわち、保持台２２は、楕円ミラーである。光源２０は、保持台２２の半楕円形状の焦点位置に設けられる。そのため、光源２０から放射された赤外線は、光路部１８を通過して焦電センサ２４に直接的に入射したり、あるいは、保持台２２に形成される鏡面を反射した後、光路部１８を通過して焦電センサ２４に入射したりする。 The cross-sectional shape of the holding table 22 has a semi-elliptical shape opened to the pyroelectric sensor 24 side. A mirror surface is formed inside the semi-elliptical shape. That is, the holding table 22 is an elliptical mirror. The light source 20 is provided at a semi-elliptical focal position of the holding table 22. Therefore, the infrared rays radiated from the light source 20 pass through the optical path 18 and enter the pyroelectric sensor 24 directly, or reflect the mirror surface formed on the holding base 22 and then pass through the optical path 18. Or incident on the pyroelectric sensor 24.
　焦電センサ２４は、バルクセラミックスを用いた焦電型赤外線センサである。焦電センサ２４には、光源２０から放射される赤外線を受光する部分である入射窓が光源２０に向けて設けられる。この入射窓には、光学フィルタ２６が設けられる。光学フィルタ２６は、たとえば、所定の波長帯の赤外線を通過するバンドパスフィルタである。所定の波長帯は、たとえば、二酸化炭素分子による吸収率の高い赤外線の波長である、４．２６μｍの近傍を含む波長帯である。所定の波長帯は、濃度の検出対象が二酸化炭素以外の気体である場合には、濃度の検出対象となる気体の種類に応じた波長（すなわち、濃度の検出対象となる気体の吸収率が高い波長）を基準とした波長帯が選択される。すなわち、焦電センサ２４は、光源２０から放射された赤外線のうち所定の波長帯の赤外線を受光する。 The pyroelectric sensor 24 is a pyroelectric infrared sensor using bulk ceramics. The pyroelectric sensor 24 is provided with an incident window, which is a part that receives infrared rays emitted from the light source 20, facing the light source 20. An optical filter 26 is provided in the incident window. The optical filter 26 is, for example, a bandpass filter that passes infrared rays in a predetermined wavelength band. The predetermined wavelength band is, for example, a wavelength band including the vicinity of 4.26 μm, which is an infrared wavelength having a high absorption rate by carbon dioxide molecules. When the concentration detection target is a gas other than carbon dioxide, the predetermined wavelength band has a wavelength corresponding to the type of gas that is the concentration detection target (that is, the absorption rate of the gas that is the concentration detection target is high). A wavelength band based on (wavelength) is selected. That is, the pyroelectric sensor 24 receives infrared rays in a predetermined wavelength band among infrared rays emitted from the light source 20.
　サーミスタ２８は、焦電センサ２４の周辺に設けられ、回路基板１２に固定される。サーミスタ２８においては、駆動回路４０から電圧が印加されることにより定電流が流れ、定電流が流れたときに生じる電圧が出力電圧として駆動回路４０において検出される。 The thermistor 28 is provided around the pyroelectric sensor 24 and is fixed to the circuit board 12. In the thermistor 28, a constant current flows when a voltage is applied from the drive circuit 40, and a voltage generated when the constant current flows is detected in the drive circuit 40 as an output voltage.
　カバー１４は、濃度検出部３０の構成部品およびサーミスタ２８を覆うように設けられ、回路基板１２に固定される。カバー１４には、カバー１４の外部からガスを取り入れたり、カバー１４の内部のガスを排出したりするための取入口１６が設けられる。取入口１６には、エアフィルターが設けられる。 The cover 14 is provided so as to cover the components of the concentration detection unit 30 and the thermistor 28, and is fixed to the circuit board 12. The cover 14 is provided with an intake port 16 for taking in gas from the outside of the cover 14 and discharging gas inside the cover 14. The intake port 16 is provided with an air filter.
　ガス濃度検出装置１０による二酸化炭素の濃度の検出は、取入口１６からカバー１４の内部に気体が取り入れられた状態で行われる。光源２０から焦電センサ２４に向けて赤外線が放射されると、放射された赤外線は、焦電センサ２４において受光される。焦電センサ２４は、赤外線の受光に応じて電圧を出力する。このとき、出力される電圧は、光路部１８における二酸化炭素の濃度と温度によって異なる。これは、光源２０から放射される赤外線が光路部１８上の二酸化炭素により吸収されるため、二酸化炭素の濃度により、光源２０から焦電センサ２４に到達する赤外線の量も変化するためである（Lambert-Beerの法則）。 The detection of the concentration of carbon dioxide by the gas concentration detection device 10 is performed in a state where gas is taken into the cover 14 from the intake port 16. When infrared rays are emitted from the light source 20 toward the pyroelectric sensor 24, the emitted infrared rays are received by the pyroelectric sensor 24. The pyroelectric sensor 24 outputs a voltage in response to infrared light reception. At this time, the output voltage varies depending on the concentration and temperature of carbon dioxide in the optical path section 18. This is because the amount of infrared rays that reach the pyroelectric sensor 24 from the light source 20 changes depending on the concentration of carbon dioxide because the infrared rays emitted from the light source 20 are absorbed by the carbon dioxide on the optical path portion 18 ( Lambert-Beer's law).
　本実施の形態において、光学フィルタ２６は、二酸化炭素の吸収率が高い波長の赤外線を通過させるものであるため、焦電センサ２４の出力値から二酸化炭素の濃度に換算することが可能となる。 In the present embodiment, since the optical filter 26 transmits infrared rays having a wavelength with high carbon dioxide absorption, it is possible to convert the output value of the pyroelectric sensor 24 into the concentration of carbon dioxide.
　図２は、本実施の形態に係るガス濃度検出装置１０の回路構成図である。図２に示すように、駆動回路４０は、増幅回路４２と、ＡＤ変換回路４４と、濃度変換処理回路４６とを含む。なお、濃度変換処理回路４６が本願請求項の算出部に相当する。また、図２に示すガス濃度検出装置１０の回路構成は、一例であり、図２に示される回路構成に限定されるものではない。 FIG. 2 is a circuit configuration diagram of the gas concentration detection apparatus 10 according to the present embodiment. As shown in FIG. 2, the drive circuit 40 includes an amplifier circuit 42, an AD conversion circuit 44, and a density conversion processing circuit 46. The density conversion processing circuit 46 corresponds to a calculation unit in the claims of the present application. Moreover, the circuit configuration of the gas concentration detection apparatus 10 shown in FIG. 2 is an example, and is not limited to the circuit configuration shown in FIG.
　増幅回路４２は、たとえば、アンプ等によって構成され、濃度検出部３０の濃度検出信号（出力電圧）の信号強度と、サーミスタ２８の温度検出信号（出力電圧）の信号強度とを増幅する。 The amplifying circuit 42 is configured by, for example, an amplifier, and amplifies the signal strength of the concentration detection signal (output voltage) of the concentration detector 30 and the signal strength of the temperature detection signal (output voltage) of the thermistor 28.
　ＡＤ変換回路４４は、増幅回路４２において信号強度が増幅されたアナログ信号をデジタル信号に変換する。なお、信号強度の増幅やアナログ信号からデジタル信号への変換は、周知の技術を用いればよい。 The AD conversion circuit 44 converts the analog signal whose signal intensity is amplified in the amplification circuit 42 into a digital signal. A well-known technique may be used for amplification of signal intensity and conversion from an analog signal to a digital signal.
　濃度変換処理回路４６は、ＡＤ変換回路４４において変換されたデジタル信号に対して所定の処理を実施することによってカバー１４の内部に取り入れられた気体に含まれる二酸化炭素の濃度Ｃを検出する。なお、本実施の形態において、濃度変換処理回路４６は、たとえば、ＣＰＵ（Central　Processing　Unit）によって実現される。ＣＰＵは、図示しない記憶部に記憶されたプログラムを実行することによって、所定の演算処理や制御処理を実行する。ＣＰＵは、たとえば、二酸化炭素の濃度を算出する演算処理に加えて、光源２０を点灯させる制御処理やサーミスタ２８に電圧を印加する制御処理を実行する。 The concentration conversion processing circuit 46 performs a predetermined process on the digital signal converted by the AD conversion circuit 44 to detect the concentration C of carbon dioxide contained in the gas introduced into the cover 14. In the present embodiment, the density conversion processing circuit 46 is realized by, for example, a CPU (Central Processing Unit). The CPU executes predetermined arithmetic processing and control processing by executing a program stored in a storage unit (not shown). For example, the CPU executes a control process for lighting the light source 20 and a control process for applying a voltage to the thermistor 28 in addition to a calculation process for calculating the concentration of carbon dioxide.
　本実施の形態において、ガス濃度検出装置１０における二酸化炭素の濃度の検出は、以下のような手順で行われる。（１）サーミスタ２８から温度検出信号を取得する。（２）光源２０を点灯状態にする。（３）焦電センサ２４の出力値Ｖを取得する。（４）取得された焦電センサ２４の出力値Ｖに対して、所定の信号処理を実行する。 In the present embodiment, the detection of the concentration of carbon dioxide in the gas concentration detection apparatus 10 is performed in the following procedure. (1) A temperature detection signal is acquired from the thermistor 28. (2) The light source 20 is turned on. (3) The output value V of the pyroelectric sensor 24 is acquired. (4) Predetermined signal processing is executed on the acquired output value V of the pyroelectric sensor 24.
　なお、焦電センサ２４の出力値Ｖが本願発明の濃度出力値に相当する。また、サーミスタ２８の温度検出信号が本願発明の温度出力値に相当する。 The output value V of the pyroelectric sensor 24 corresponds to the concentration output value of the present invention. Further, the temperature detection signal of the thermistor 28 corresponds to the temperature output value of the present invention.
　なお、所定の信号処理は、たとえば、焦電センサ２４の出力波形から移動平均法を用いてノイズを除去する処理と、増幅回路４２によって信号強度を増幅する処理と、ＡＤ変換回路４４によってデジタルデータに変換する処理とを含む。これらの処理は、温度検出信号に対しても行なわれる。また、温度検出信号からサーミスタ温度Ｔｈ［Ｋ］が算出される。サーミスタ温度Ｔｈの算出は、上記（１）において行なわれてもよい。 The predetermined signal processing includes, for example, processing for removing noise from the output waveform of the pyroelectric sensor 24 using a moving average method, processing for amplifying the signal intensity by the amplifier circuit 42, and digital data by the AD conversion circuit 44. And the process of converting to. These processes are also performed on the temperature detection signal. Further, the thermistor temperature Th [K] is calculated from the temperature detection signal. The calculation of the thermistor temperature Th may be performed in the above (1).
　（５）サーミスタ温度Ｔｈと焦電センサ２４の出力値Ｖとから二酸化炭素の濃度Ｃを算出する。（６）光源２０を点灯停止状態にする。ガス濃度検出装置１０は、上記（１）～（６）の処理を、たとえば、一定間隔毎に行なう。 (5) The concentration C of carbon dioxide is calculated from the thermistor temperature Th and the output value V of the pyroelectric sensor 24. (6) The light source 20 is turned off. The gas concentration detection apparatus 10 performs the processes (1) to (6) at regular intervals, for example.
　以下に、本実施の形態に係るガス濃度検出装置１０がサーミスタ２８の温度Ｔｈと焦電センサ２４の出力値Ｖとから二酸化炭素の濃度Ｃを算出する方法について説明する。 Hereinafter, a method for calculating the carbon dioxide concentration C from the temperature Th of the thermistor 28 and the output value V of the pyroelectric sensor 24 by the gas concentration detection apparatus 10 according to the present embodiment will be described.
　濃度変換処理回路４６は、焦電センサ２４の出力値Ｖと予め取得された第１検量線とサーミスタ温度Ｔｈと第２検量線とに基づいて二酸化炭素の濃度を算出する。 The concentration conversion processing circuit 46 calculates the concentration of carbon dioxide based on the output value V of the pyroelectric sensor 24, the first calibration curve obtained in advance, the thermistor temperature Th, and the second calibration curve.
　第１検量線に関するデータおよび第２検量線に関するデータは、ガス濃度検出装置１０の製造時において予め取得されて、駆動回路４０に設けられるメモリ等の記憶媒体に記憶される。 The data relating to the first calibration curve and the data relating to the second calibration curve are acquired in advance at the time of manufacturing the gas concentration detection device 10 and stored in a storage medium such as a memory provided in the drive circuit 40.
　第１検量線は、予め定められた基準温度（たとえば、２５℃）における二酸化炭素の濃度Ｃと焦電センサ２４の出力値Ｖとの関係を示す。より具体的には、第１検量線は、焦電センサ２４の出力値Ｖを基準出力値Ｖ０で規格化した値（Ｖ／Ｖ０）と、二酸化炭素の濃度Ｃとの関係を示す。基準温度における二酸化炭素の複数の濃度の各々に対応した、焦電センサ２４の出力値が予め取得されており、第１検量線は、予め取得された複数の焦電センサ２４の出力値に基づいて、補正係数αが乗算された所定の次数の近似式を導出して設定される。 The first calibration curve indicates the relationship between the carbon dioxide concentration C and the output value V of the pyroelectric sensor 24 at a predetermined reference temperature (for example, 25 ° C.). More specifically, the first calibration curve shows the relationship between the value (V / V0) obtained by normalizing the output value V of the pyroelectric sensor 24 with the reference output value V0 and the concentration C of carbon dioxide. An output value of the pyroelectric sensor 24 corresponding to each of the plurality of carbon dioxide concentrations at the reference temperature is acquired in advance, and the first calibration curve is based on the output values of the plurality of pyroelectric sensors 24 acquired in advance. Thus, an approximate expression of a predetermined order multiplied by the correction coefficient α is derived and set.
　この基準出力値Ｖ０は、二酸化炭素の濃度が予め定められた基準濃度（たとえば、０ｐｐｍ）である場合における、サーミスタ温度Ｔｈに対応した焦電センサ２４の出力値である。基準出力値Ｖ０は、サーミスタ温度Ｔｈに基づいて後述する第２検量線を用いて算出される。 The reference output value V0 is an output value of the pyroelectric sensor 24 corresponding to the thermistor temperature Th when the concentration of carbon dioxide is a predetermined reference concentration (for example, 0 ppm). The reference output value V0 is calculated using a second calibration curve described later based on the thermistor temperature Th.
　本実施の形態において、第１検量線は、以下の式で示される。
　Ｃ（二酸化炭素の濃度）＝α（補正係数）×ｆ１（Ｖ／Ｖ０）…（式１）
　上記（式１）におけるｆ１は、所定の次数の関数であって、たとえば、２次関数であってもよいし、３次関数であってもよい。ｆ１が３次関数である場合には、ガスの濃度Ｃは、以下の式で示される。 In the present embodiment, the first calibration curve is represented by the following equation.
C (carbon dioxide concentration) = α (correction coefficient) × f1 (V / V0) (Equation 1)
F1 in the above (Expression 1) is a function of a predetermined order, and may be, for example, a quadratic function or a cubic function. When f1 is a cubic function, the gas concentration C is expressed by the following equation.
　Ｃ＝α×［ａ１×（Ｖ／Ｖ０）３＋ａ２×（Ｖ／Ｖ０）２＋ａ３×（Ｖ／Ｖ０）＋ａ４］…（式２）
　上記（式２）におけるａ１～ａ４は、基準温度において予め実験等により取得された複数種類の二酸化炭素の濃度と焦電センサ２４の出力値との組み合わせに基づいて算出される。たとえば、図３に示すように、基準温度における予め定められた複数の二酸化炭素の濃度（たとえば、０ｐｐｍ、４００ｐｐｍ、１０００ｐｐｍ、２０００ｐｐｍの濃度）にそれぞれ対応した複数の焦電センサ２４の出力値が予め実験等により取得され、取得された出力値に基づいてａ１～ａ４が算出される。 C = α × [a1 × (V / V0) 3 + a2 × (V / V0) 2 + a3 × (V / V0) + a4] (Formula 2)
In the above (Expression 2), a1 to a4 are calculated based on a combination of the concentrations of a plurality of types of carbon dioxide and the output value of the pyroelectric sensor 24 obtained in advance through experiments or the like at the reference temperature. For example, as shown in FIG. 3, output values of a plurality of pyroelectric sensors 24 respectively corresponding to a plurality of predetermined carbon dioxide concentrations (for example, concentrations of 0 ppm, 400 ppm, 1000 ppm, and 2000 ppm) at the reference temperature are obtained in advance. A1 to a4 are calculated based on the acquired output values acquired by experiments or the like.
　上記（式２）および算出されたａ１～ａ４の値は、駆動回路４０に設けられるメモリ等の記憶媒体に記憶される。 The above (Equation 2) and the calculated values of a1 to a4 are stored in a storage medium such as a memory provided in the drive circuit 40.
　補正係数αは、α＝Ｔｈ／Ｔｈ２５の式より算出される。なお、Ｔｈ２５は、２５℃時のサーミスタ温度［Ｋ］を示す。すなわち、補正係数αは、温度出力値に比例する。 The correction coefficient α is calculated from the equation: α = Th / Th 25 . Th 25 indicates the thermistor temperature [K] at 25 ° C. That is, the correction coefficient α is proportional to the temperature output value.
　サーミスタ温度Ｔｈ［Ｋ］は、以下の式を用いて算出される。
　Ｔｈ＝１／（１／Ｔｈ２５＋１／Ｂ×ｌｎ（Ｖｔｈ／（Ｖｃｃ－Ｖｔｈ）））…（式３）
　上記（式３）において、Ｂは、定数を示し、Ｖｔｈは、サーミスタ２８の出力電圧を示し、Ｖｃｃは、駆動回路４０からサーミスタ２８への印加電圧を示す。上記（式３）および定数Ｂは、駆動回路４０に設けられるメモリ等の記憶媒体に記憶される。 The thermistor temperature Th [K] is calculated using the following equation.
Th = 1 / (1 / Th 25 + 1 / B × ln (Vth / (Vcc−Vth))) (Formula 3)
In (Equation 3), B represents a constant, Vth represents the output voltage of the thermistor 28, and Vcc represents the voltage applied from the drive circuit 40 to the thermistor 28. The above (Equation 3) and the constant B are stored in a storage medium such as a memory provided in the drive circuit 40.
　補正係数αは、サーミスタ温度Ｔｈに比例する係数である。補正係数αは、駆動回路４０に設けられるメモリ等の記憶媒体に記憶される。 The correction coefficient α is a coefficient proportional to the thermistor temperature Th. The correction coefficient α is stored in a storage medium such as a memory provided in the drive circuit 40.
　上記（式１）で示される第１検量線は、たとえば、図４の実線で示される。図４の横軸は、二酸化炭素の濃度Ｃを示し、図４の縦軸は、規格化した値（Ｖ／Ｖ０）を示す。図４に示されるように、濃度Ｃと規格化した値（Ｖ／Ｖ０）とは、濃度Ｃが高くなるほど、規格化した値（Ｖ／Ｖ０）が減少し、濃度Ｃが低くなるほど規格化した値（Ｖ／Ｖ０）は増加する関係がある。 The first calibration curve expressed by the above (formula 1) is indicated by a solid line in FIG. The horizontal axis of FIG. 4 indicates the carbon dioxide concentration C, and the vertical axis of FIG. 4 indicates the normalized value (V / V0). As shown in FIG. 4, the concentration C and the normalized value (V / V0) are normalized as the concentration C increases, the normalized value (V / V0) decreases, and the concentration C decreases. The value (V / V0) has an increasing relationship.
　補正係数αは、二酸化炭素が赤外線を吸収する吸収量についての温度特性を考慮して設定される。 The correction coefficient α is set in consideration of the temperature characteristics of the amount of absorption by which carbon dioxide absorbs infrared rays.
　カバー１４の内部の二酸化炭素の分子数によって赤外線の吸収量は異なる。そのため、カバー１４の内部の体積が同じで、圧力が同じであっても、二酸化炭素の分子の数が異なると、赤外線の吸収量が異なることから焦電センサ２４の出力値も変化することとなる。 ¡Infrared absorption varies depending on the number of carbon dioxide molecules inside the cover 14. Therefore, even if the volume inside the cover 14 is the same and the pressure is the same, if the number of carbon dioxide molecules is different, the output value of the pyroelectric sensor 24 also changes because the amount of infrared absorption is different. Become.
　この二酸化炭素の分子数を意味するモル濃度ｎ（ｍｏｌ／ｌ）は、理想気体の場合、気体の状態方程式（ＰＶ＝ｎＲＴ）に従うため、圧力Ｐおよび体積Ｖが一定の環境下では、温度の逆数に比例（温度に反比例）する。したがって、同じ二酸化炭素濃度の環境下であっても、二酸化炭素を含むガスの温度と赤外線の吸収量との間には、二酸化炭素を含むガスの温度が上昇するほど赤外線の吸収量は低下し、二酸化炭素を含むガスの温度が低下するほど赤外線の吸収量が増加する関係がある。 In the case of an ideal gas, the molar concentration n (mol / l), which means the number of molecules of carbon dioxide, follows the gas equation of state (PV = nRT). Therefore, in an environment where the pressure P and the volume V are constant, the temperature Proportional to inverse (inversely proportional to temperature). Therefore, even in an environment with the same carbon dioxide concentration, the amount of absorbed infrared light decreases between the temperature of the gas containing carbon dioxide and the amount of absorbed infrared light as the temperature of the gas containing carbon dioxide increases. There is a relationship in which the amount of infrared absorption increases as the temperature of the gas containing carbon dioxide decreases.
　温度上昇によりモル濃度ｎが低下するため、赤外線の吸収量が低下する場合には、焦電センサ２４の出力値Ｖは本来の出力値よりも高い値に変化する。そのため、焦電センサ２４の出力値Ｖは、本来の濃度よりも低い値に換算されることとなる。 Since the molar concentration n is decreased by the temperature rise, the output value V of the pyroelectric sensor 24 is changed to a value higher than the original output value when the infrared absorption amount is decreased. Therefore, the output value V of the pyroelectric sensor 24 is converted to a value lower than the original density.
　同様に、温度低下によりモル濃度ｎが増加するため、赤外線の吸収量が増加する場合には、焦電センサ２４の出力値Ｖは本来の出力値よりも低い値に変化する。そのため、焦電センサ２４の出力値Ｖは、本来の濃度よりも高い値に換算されることとなる。 Similarly, since the molar concentration n increases due to the temperature decrease, when the infrared absorption increases, the output value V of the pyroelectric sensor 24 changes to a value lower than the original output value. Therefore, the output value V of the pyroelectric sensor 24 is converted to a value higher than the original density.
　しかしながら、算出したい二酸化炭素の濃度は、カバー１４の内部の容積に対する二酸化炭素ガスの体積の比率であるため、温度と算出したい濃度の関係と、温度とモル濃度ｎの関係とは乖離がでる。 However, since the concentration of carbon dioxide to be calculated is the ratio of the volume of carbon dioxide gas to the volume inside the cover 14, the relationship between the temperature and the concentration to be calculated differs from the relationship between the temperature and the molar concentration n.
　図５に、光源から放射される赤外線の波長と、二酸化炭素分子による赤外線の吸収率との関係を示す。図５の縦軸は、赤外線の吸収率を示し、図５の横軸は、赤外線の波長を示す。なお、本実施の形態において、赤外線の吸収率は、特定の波長における赤外線の吸収量を示す。 FIG. 5 shows the relationship between the wavelength of infrared rays emitted from the light source and the absorption rate of infrared rays by carbon dioxide molecules. The vertical axis in FIG. 5 indicates the infrared absorption rate, and the horizontal axis in FIG. 5 indicates the infrared wavelength. In the present embodiment, the infrared absorption rate indicates the amount of infrared absorption at a specific wavelength.
　図５の太実線は、ガスの濃度が－５０℃である場合の吸収スペクトルである。図５の太破線は、ガスの濃度が０℃である場合の吸収スペクトルである。図５の細実線は、ガス温度が２５℃である場合の吸収スペクトルである。図５の細破線は、ガス温度が５０℃である場合の吸収スペクトルである。図５の一点鎖線は、ガス温度が１００℃である場合の吸収スペクトルである。 The thick solid line in FIG. 5 is an absorption spectrum when the gas concentration is −50 ° C. The thick broken line in FIG. 5 is an absorption spectrum when the gas concentration is 0 ° C. The thin solid line in FIG. 5 is an absorption spectrum when the gas temperature is 25 ° C. The thin broken line in FIG. 5 is an absorption spectrum when the gas temperature is 50 ° C. The dashed-dotted line in FIG. 5 is an absorption spectrum when the gas temperature is 100 ° C.
　図５に示す吸収スペクトルからも明らかなように、二酸化炭素分子による赤外線の吸収率が高い波長領域（吸収波長領域）において、二酸化炭素を含むガスの各温度における赤外線の吸収率の積分値（図５における各吸収スペクトルの波形の面積、すなわち、赤外線の吸収量）は、温度の逆数に比例する傾向がある。 As is clear from the absorption spectrum shown in FIG. 5, in the wavelength region (absorption wavelength region) where the absorption rate of infrared rays by carbon dioxide molecules is high, the integrated value of the absorption rate of infrared rays at each temperature of the gas containing carbon dioxide (see FIG. 5). 5, the area of the waveform of each absorption spectrum, that is, the amount of infrared absorption) tends to be proportional to the inverse of temperature.
　したがって、二酸化炭素が赤外線を吸収する吸収量の温度特性を考慮して補正係数αを設定することにより、二酸化炭素の濃度をより精度高く算出することができる。 Therefore, the concentration of carbon dioxide can be calculated with higher accuracy by setting the correction coefficient α in consideration of the temperature characteristics of the amount of absorption by which carbon dioxide absorbs infrared rays.
　また、予め定められた基準温度Ｔａ（たとえば、２５℃）での赤外線の吸収量Ａと、温度Ｔｂでの赤外線の吸収量Ｂとの吸収量比Ｂ／Ａ（吸収量Ｂを吸収量Ａで規格化した値）は、温度の比の逆数Ｔａ／Ｔｂと類似する。すなわち、濃度Ｃの誤差は、Ｔａ／Ｔｂに比例して生じることとなる。そのため、本実施の形態においては、補正係数αを、α＝Ｔｈ／Ｔｈ２５の式により設定するものとする。なお、補正係数αは、温度に比例する係数であればよく、特に上記式に限定されるものではなく、実験等により調整してもよい。 Also, the absorption ratio B / A (absorption amount B is the absorption amount A) between the infrared absorption amount A at a predetermined reference temperature Ta (for example, 25 ° C.) and the infrared absorption amount B at the temperature Tb. The normalized value) is similar to the reciprocal Ta / Tb of the temperature ratio. That is, the error in the density C occurs in proportion to Ta / Tb. For this reason, in the present embodiment, the correction coefficient α is set by the equation α = Th / Th 25 . The correction coefficient α may be a coefficient proportional to the temperature, and is not particularly limited to the above formula, and may be adjusted by experiments or the like.
　第１検量線は、補正係数αにより補正される。たとえば、サーミスタ温度Ｔｈが５０℃である場合には、図４の破線に示すように、基準温度（２５℃）での第１検量線（図４の実線）よりも上方に第１検量線が位置するので、濃度は下方に補正される。また、サーミスタ温度Ｔｈが０℃である場合には、図４の一点鎖線に示すように、基準温度での第１検量線よりも下方に第１検量線が位置するので、濃度は上方に補正される。 The first calibration curve is corrected by the correction coefficient α. For example, when the thermistor temperature Th is 50 ° C., the first calibration curve is located above the first calibration curve (solid line in FIG. 4) at the reference temperature (25 ° C.) as shown by the broken line in FIG. Since it is located, the density is corrected downward. Further, when the thermistor temperature Th is 0 ° C., the first calibration curve is located below the first calibration curve at the reference temperature as shown by the one-dot chain line in FIG. Is done.
　このように第１検量線に温度に比例する補正係数αを含めることにより、赤外線の吸収量の温度特性を考慮してガス濃度を精度高く算出することができる。 In this way, by including the correction coefficient α proportional to the temperature in the first calibration curve, the gas concentration can be calculated with high accuracy in consideration of the temperature characteristic of the infrared absorption amount.
　また、濃度変換処理回路４６は、第２検量線を用いて基準出力値Ｖ０を算出する。第２検量線は、予め定められた基準濃度（たとえば、０ｐｐｍ）におけるサーミスタ温度Ｔｈと基準出力値Ｖ０との関係を示す。第２検量線は、基準濃度における二酸化炭素の複数の温度の各々に対応した、予め取得された複数の焦電センサ２４の出力値に基づいて所定の次数の近似式を導出して設定される。 Further, the concentration conversion processing circuit 46 calculates the reference output value V0 using the second calibration curve. The second calibration curve shows the relationship between the thermistor temperature Th and the reference output value V0 at a predetermined reference concentration (for example, 0 ppm). The second calibration curve is set by deriving an approximate expression of a predetermined order based on the output values of the plurality of pyroelectric sensors 24 acquired in advance corresponding to each of the plurality of carbon dioxide temperatures at the reference concentration. .
　本実施の形態において、第２検量線は、以下の式で示される。
　Ｖ０＝ｆ２（Ｔｈ）…（式４）
　上記（式４）におけるｆ２は、所定の次数の関数であって、たとえば、３次関数であってもよいし、４次関数であってもよい。ｆ２が４次関数である場合には、基準出力値Ｖ０は、以下の式で示される。 In the present embodiment, the second calibration curve is represented by the following equation.
V0 = f2 (Th) (Formula 4)
F2 in the above (Formula 4) is a function of a predetermined order, and may be, for example, a cubic function or a quartic function. When f2 is a quartic function, the reference output value V0 is expressed by the following equation.
　Ｖ０＝ｂ１×Ｔｈ４＋ｂ２×Ｔｈ３＋ｂ３×Ｔｈ２＋ｂ４×Ｔｈ＋ｂ５…（式５）
　上記（式５）におけるｂ１～ｂ５は、基準濃度において予め実験等により取得された複数種類の温度（サーミスタ温度Ｔｈ）と焦電センサ２４の出力値との組み合わせに基づいて算出される。 V0 = b1 × Th 4 + b2 × Th 3 + b3 × Th 2 + b4 × Th + b5 (Formula 5)
In the above (Expression 5), b1 to b5 are calculated based on a combination of a plurality of types of temperatures (thermistor temperature Th) obtained in advance by experiments or the like at the reference concentration and the output value of the pyroelectric sensor 24.
　なお、ガス濃度検出装置１０は、基準濃度において予め実験等により取得された複数種類の温度（サーミスタ温度Ｔｈ）に代えて、基準濃度において予め実験等により取得された複数種類の温度の電圧値（サーミスタの出力電圧Ｖｔｈ）を用いてもよい。すなわち、基準出力値Ｖ０は、サーミスタの出力電圧Ｖｔｈから求められてもよい。したがって、上記（式４）、（式５）において、ＴｈをＶｔｈに置き換えてもよい。 Note that the gas concentration detection device 10 replaces a plurality of types of temperatures (thermistor temperature Th) previously acquired by experiments or the like at the reference concentration with the voltage values of a plurality of types of temperatures previously acquired by experiments or the like at the reference concentration (thermistor temperature Th). The output voltage Vth of the thermistor may be used. That is, the reference output value V0 may be obtained from the output voltage Vth of the thermistor. Therefore, in the above (Formula 4) and (Formula 5), Th may be replaced with Vth.
　たとえば、図３に示すように、基準濃度における複数の温度（たとえば、０℃、１０℃、２５℃、４０℃および５０℃）にそれぞれ対応した複数の焦電センサ２４の出力値が予め実験等により取得され、取得された出力値に基づいてｂ１～ｂ４が算出される。 For example, as shown in FIG. 3, the output values of a plurality of pyroelectric sensors 24 respectively corresponding to a plurality of temperatures (for example, 0 ° C., 10 ° C., 25 ° C., 40 ° C., and 50 ° C.) at the reference concentration are previously tested. And b1 to b4 are calculated based on the acquired output values.
　上記（式５）および算出されたｂ１～ｂ５の値は、駆動回路４０に設けられるメモリ等の記憶媒体に記憶される。 The above (Formula 5) and the calculated values b1 to b5 are stored in a storage medium such as a memory provided in the drive circuit 40.
　以下に実験例を示し、本実施の形態に係るガス濃度検出装置１０の作用効果について説明する。なお、実験例で用いられた焦電型赤外線センサは、村田製作所製Ｅ４７２ＳＷ１であるが、一般的にバルクの圧電セラミックスや、ＭＥＭＳ（Micro　Electro　Mechanical　Systems）を用いた赤外線センサであれば同様の効果が得られると予想される。 Hereinafter, experimental examples will be shown, and the effects of the gas concentration detection device 10 according to the present embodiment will be described. The pyroelectric infrared sensor used in the experimental example is E472SW1 manufactured by Murata Manufacturing Co., Ltd., but generally the same effect can be obtained if the infrared sensor uses bulk piezoelectric ceramics or MEMS (Micro Electro Mechanical Systems). Is expected to be obtained.
　以下に、上記（式１）で示される第１検量線における補正係数αの有無による温度特性の改善効果について図６を用いて説明する。 Hereinafter, the effect of improving the temperature characteristics by the presence or absence of the correction coefficient α in the first calibration curve expressed by the above (formula 1) will be described with reference to FIG.
　比較例として、図６（Ａ）に、第１検量線において補正係数αが含まれない場合における複数の温度環境下での濃度の各々に対応する検出値の誤差を示す。図６（Ａ）の縦軸は、誤差を示し、０を基準として図６（Ａ）上方向をプラス方向、図６（Ａ）下方向をマイナス方向とする。図６（Ａ）の横軸は、二酸化炭素の濃度を示す。 As a comparative example, FIG. 6 (A) shows errors in detection values corresponding to concentrations in a plurality of temperature environments when the correction coefficient α is not included in the first calibration curve. The vertical axis in FIG. 6A indicates an error, and with 0 as a reference, the upward direction in FIG. 6A is a positive direction, and the downward direction in FIG. 6A is a negative direction. The horizontal axis of FIG. 6A shows the concentration of carbon dioxide.
　図６（Ａ）の破線は、温度（サーミスタ温度Ｔｈ）が０℃である場合の誤差と濃度との関係を示す。図６（Ａ）の実線は、温度が２５℃（基準温度）である場合の誤差と濃度との関係を示す。図６（Ａ）の一点鎖線は、温度が５０℃である場合の誤差と濃度との関係を示す。 The broken line in FIG. 6 (A) shows the relationship between error and concentration when the temperature (thermistor temperature Th) is 0 ° C. The solid line in FIG. 6A shows the relationship between error and concentration when the temperature is 25 ° C. (reference temperature). The dashed line in FIG. 6A shows the relationship between error and concentration when the temperature is 50 ° C.
　図６（Ａ）に示すように、温度が２５℃である場合には、複数の濃度の各々に対応する濃度の誤差は、ほぼゼロとなる。これは、第１検量線が基準温度における複数の濃度の各々に対応する焦電センサ２４の出力値（実測値）に基づいて設定されているためである。 As shown in FIG. 6 (A), when the temperature is 25 ° C., the error in concentration corresponding to each of the plurality of concentrations is almost zero. This is because the first calibration curve is set based on the output value (actually measured value) of the pyroelectric sensor 24 corresponding to each of a plurality of concentrations at the reference temperature.
　一方、温度が５０℃である場合には、二酸化炭素による赤外線の吸収量は、温度が２５℃である場合の赤外線の吸収量よりも低下するため、焦電センサ２４の出力値は、本来の出力値（温度が２５℃である場合の同一の濃度に対する焦電センサ２４の出力値）よりも高い側に変化する。このため、温度が２５℃である場合の濃度の誤差よりも低い側に濃度の誤差が生じることとなる。 On the other hand, when the temperature is 50 ° C., the amount of infrared rays absorbed by carbon dioxide is lower than the amount of infrared rays absorbed when the temperature is 25 ° C. Therefore, the output value of the pyroelectric sensor 24 is the original value. It changes to a higher side than the output value (the output value of the pyroelectric sensor 24 for the same density when the temperature is 25 ° C.). For this reason, an error in density occurs on the lower side than an error in density when the temperature is 25 ° C.
　また、温度が０℃である場合には、赤外線の吸収量は、温度が２５℃である場合の赤外線の吸収量よりも増加するため、焦電センサ２４の出力値は、本来の出力値よりも低い側に変化する。このため、温度が２５℃である場合の濃度の誤差よりも高い側に濃度の誤差が生じることとなる。 In addition, when the temperature is 0 ° C., the infrared absorption amount increases more than the infrared absorption amount when the temperature is 25 ° C. Therefore, the output value of the pyroelectric sensor 24 is higher than the original output value. Also changes to the lower side. For this reason, an error in density occurs on the higher side than an error in density when the temperature is 25 ° C.
　図６（Ｂ）に、第１検量線において補正係数αが含まれる場合における複数の温度環境下での濃度の各々に対応する検出値の誤差を示す。図６（Ｂ）の縦軸は、誤差を示し、０を基準として図６（Ｂ）上方向をプラス方向、図６（Ｂ）下方向をマイナス方向とする。図６（Ｂ）の横軸は、二酸化炭素の濃度を示す。なお、図６（Ａ）の縦軸のスケールと図６（Ｂ）の縦軸のスケールとは同一であるものとする。 FIG. 6 (B) shows errors in detected values corresponding to concentrations in a plurality of temperature environments when the correction coefficient α is included in the first calibration curve. The vertical axis in FIG. 6B represents an error, and with 0 as a reference, the upward direction in FIG. 6B is the positive direction, and the downward direction in FIG. 6B is the negative direction. The horizontal axis in FIG. 6B indicates the concentration of carbon dioxide. Note that the vertical scale in FIG. 6A and the vertical scale in FIG. 6B are the same.
　図６（Ｂ）の破線は、温度（サーミスタ温度Ｔｈ）が０℃である場合の誤差と濃度との関係を示す。図６（Ｂ）の実線は、温度が２５℃である場合の誤差と濃度との関係を示す。図６（Ｂ）の一点鎖線は、温度が５０℃である場合の誤差と濃度との関係を示す。 The broken line in FIG. 6B shows the relationship between the error and the concentration when the temperature (thermistor temperature Th) is 0 ° C. The solid line in FIG. 6B shows the relationship between error and concentration when the temperature is 25 ° C. The alternate long and short dash line in FIG. 6B shows the relationship between the error and the concentration when the temperature is 50 ° C.
　図６（Ｂ）に示すように、温度が２５℃である場合には、図６（Ａ）を用いて説明したとおり、複数の濃度の各々に対応する誤差は、ほぼゼロとなる。 As shown in FIG. 6B, when the temperature is 25 ° C., as described with reference to FIG. 6A, the error corresponding to each of the plurality of concentrations is almost zero.
　一方、温度が５０℃である場合には、二酸化炭素による赤外線の吸収量は、温度が２５℃である場合の赤外線の吸収量も低下する。しかしながら、補正係数αは、温度が２５℃である場合（α＝１）よりも大きい値になる。そのため、二酸化炭素の濃度Ｃの誤差は、図６（Ａ）に示される温度が５０℃である場合の誤差と比較して、濃度の誤差は、プラス方向に是正されることとなる。そのため、図６（Ａ）の温度が５０℃である場合と比較して、濃度の誤差の大きさが小さくなる。 On the other hand, when the temperature is 50 ° C., the amount of infrared rays absorbed by carbon dioxide also decreases when the temperature is 25 ° C. However, the correction coefficient α is larger than when the temperature is 25 ° C. (α = 1). Therefore, the error in the concentration C of carbon dioxide is corrected in the positive direction as compared with the error in the case where the temperature shown in FIG. Therefore, compared to the case where the temperature in FIG. 6A is 50 ° C., the density error is small.
　同様に、温度が０℃である場合には、二酸化炭素による赤外線の吸収量は、温度が２５℃である場合の赤外線の吸収量よりも増加する。しかしながら、補正係数αは、温度が２５である場合（α＝１）よりも小さい値になる。そのため、二酸化炭素の濃度Ｃの誤差は、図６（Ａ）に示される温度が０℃である場合の誤差と比較して、濃度の誤差は、マイナス方向に是正されることとなる。そのため、図６（Ａ）の温度が０℃である場合と比較して、濃度の誤差の大きさが小さくなる。 Similarly, when the temperature is 0 ° C., the amount of infrared rays absorbed by carbon dioxide increases more than the amount of infrared rays absorbed when the temperature is 25 ° C. However, the correction coefficient α is smaller than when the temperature is 25 (α = 1). Therefore, the error in the concentration C of carbon dioxide is corrected in the minus direction as compared with the error in the case where the temperature shown in FIG. Therefore, the magnitude of the density error is smaller than in the case where the temperature in FIG.
　以上のようにして、本実施の形態に係るガス濃度検出装置１０によると、第１検量線にサーミスタ温度Ｔｈに比例する補正係数αを含めることができるので、サーミスタ温度Ｔｈの逆数に比例する赤外線の吸収量の変化によって生じる濃度の誤差を補正することができる。そのため、二酸化炭素による赤外線の吸収量の温度特性を考慮して、二酸化炭素の濃度Ｃを精度高く算出することができる。また、複数の温度に対する検量線データを減少させることができるため、検量線データの作成時間、および検量線データのデータ量の増大を抑制することができる。したがって、予め必要なデータ量の増加を抑制するとともに、赤外線の吸収量の温度特性を考慮してガスの濃度を精度高く検出するガス濃度検出装置を提供することができる。 As described above, according to the gas concentration detection apparatus 10 according to the present embodiment, the correction coefficient α proportional to the thermistor temperature Th can be included in the first calibration curve, and therefore the infrared ray proportional to the inverse of the thermistor temperature Th. It is possible to correct the density error caused by the change in the amount of absorption. Therefore, the concentration C of carbon dioxide can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared rays absorbed by carbon dioxide. In addition, since the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress the time for creating the calibration curve data and the increase in the data amount of the calibration curve data. Therefore, it is possible to provide a gas concentration detection device that can suppress an increase in a necessary data amount in advance and detect a gas concentration with high accuracy in consideration of a temperature characteristic of an infrared absorption amount.
　さらに、サーミスタ温度Ｔｈの変化に反比例して変化するガスによる赤外線の吸収量に応じた値、具体的には、サーミスタ温度Ｔｈを基準温度（２５℃）のサーミスタ温度Ｔｈ２５で規格した値Ｔｈ／Ｔｈ２５を補正係数αとして算出することにより、二酸化炭素による赤外線の吸収量の温度特性を考慮して、二酸化炭素の濃度Ｃを精度高く算出することができる。 Furthermore, a value corresponding to the amount of infrared rays absorbed by the gas that changes in inverse proportion to the change in the thermistor temperature Th, specifically, a value Th / standardized by the thermistor temperature Th 25 of the reference temperature (25 ° C.). By calculating Th 25 as the correction coefficient α, it is possible to calculate the concentration C of carbon dioxide with high accuracy in consideration of the temperature characteristics of the amount of infrared rays absorbed by carbon dioxide.
　さらに、第２検量線に基づいてサーミスタ温度Ｔｈに応じた基準出力値Ｖ０を算出することができるため、第１検量線と、算出された基準出力値Ｖ０とを用いて二酸化炭素の濃度Ｃを精度高く算出することができる。 Furthermore, since the reference output value V0 corresponding to the thermistor temperature Th can be calculated based on the second calibration curve, the carbon dioxide concentration C is calculated using the first calibration curve and the calculated reference output value V0. It is possible to calculate with high accuracy.
　補正係数αを含む上記（式１）で示される第１検量線および上記（式４）で示される第２検量線を用いて二酸化炭素の濃度Ｃの算出が可能となるため、予め取得するデータ量の増加を抑制するとともに、演算の負荷を低減することができる。また、予め取得するデータの増加の抑制や演算の負荷の低減により、製品の製造コストや設計コストの増加を抑制することができる。 Since the carbon dioxide concentration C can be calculated using the first calibration curve represented by (Equation 1) and the second calibration curve represented by (Equation 4) including the correction coefficient α, data acquired in advance While suppressing an increase in the amount, the calculation load can be reduced. Moreover, the increase in the manufacturing cost and design cost of a product can be suppressed by suppressing the increase in the data acquired beforehand and reducing the calculation load.
　本実施の形態において、基準温度である場合に、０ｐｐｍ、４００ｐｐｍ、１０００ｐｐｍ、および、２０００ｐｐｍの４点の濃度を測定ポイントとして、各濃度に対応する焦電センサ２４の出力値を予め取得し、取得された出力値を用いて第１検量線のａ１～ａ４を算出するものとして説明したが、たとえば、４点以上の濃度に対応する焦電センサ２４の出力値を予め取得してもよいし、上記４点以外の測定ポイントの濃度に対応する焦電センサ２４の出力値を予め取得してもよいし、２０００ｐｐｍよりも大きい濃度あるいは小さい濃度を上限値とする複数の濃度に対応する複数の焦電センサ２４の出力値を予め取得してもよい。 In the present embodiment, when the temperature is the reference temperature, the output values of the pyroelectric sensor 24 corresponding to each concentration are acquired in advance by using four concentrations of 0 ppm, 400 ppm, 1000 ppm, and 2000 ppm as measurement points. In the above description, the a1 to a4 of the first calibration curve are calculated using the output values, but for example, the output values of the pyroelectric sensor 24 corresponding to the concentrations of four or more points may be acquired in advance, The output value of the pyroelectric sensor 24 corresponding to the density of the measurement points other than the above four points may be acquired in advance, or a plurality of pyroelectrics corresponding to a plurality of densities having a density higher or lower than 2000 ppm as an upper limit value. The output value of the electric sensor 24 may be acquired in advance.
　さらに、本実施の形態においては、基準濃度である場合に、０℃、１０℃、２５℃、４０℃、および、５０℃の５点の温度を測定ポイントとして、各温度に対応する焦電センサ２４の出力値を予め取得し、取得された出力値を用いて第２検量線のｂ１～ｂ５を算出するものとして説明したが、たとえば、５点以上の温度に対応する焦電センサ２４の出力値を予め取得してもよいし、上記５点以外の測定ポイントの温度に対応する焦電センサ２４の出力値を予め取得してもよいし、５０℃よりも大きい温度あるいは小さい温度を上限値とする複数の温度に対応する複数の焦電センサ２４の出力値を予め取得してもよいし、０℃よりも低い値あるいは高い値を下限値とする複数の温度に対応する複数の焦電センサ２４の出力値を予め取得してもよい。 Furthermore, in this embodiment, when the reference concentration is used, pyroelectric sensors corresponding to each temperature are measured at five temperatures of 0 ° C., 10 ° C., 25 ° C., 40 ° C., and 50 ° C. In the above description, the output values of 24 are acquired in advance, and b1 to b5 of the second calibration curve are calculated using the acquired output values. For example, the output of the pyroelectric sensor 24 corresponding to a temperature of 5 points or more is used. The value may be acquired in advance, the output value of the pyroelectric sensor 24 corresponding to the temperature of the measurement point other than the above five points may be acquired in advance, or a temperature higher or lower than 50 ° C. Output values of a plurality of pyroelectric sensors 24 corresponding to a plurality of temperatures may be acquired in advance, or a plurality of pyroelectrics corresponding to a plurality of temperatures having a lower value or a value lower than 0 ° C. Even if the output value of the sensor 24 is acquired in advance There.
　なお、好ましくは、濃度の測定ポイントの各々は、測定範囲が０～Ｒである場合、０、Ｒ／４、Ｒ／２、Ｒとすることが望ましい。 Preferably, each of the concentration measurement points is set to 0, R / 4, R / 2, and R when the measurement range is 0 to R.
　なお、上述の実施の形態では、補正係数αは、温度出力値に比例するとしたが、これに限るものではない。補正係数αは、温度出力信号のべき乗に比例してもよい。 In the above-described embodiment, the correction coefficient α is proportional to the temperature output value, but is not limited thereto. The correction coefficient α may be proportional to the power of the temperature output signal.
　今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
　１０　ガス濃度検出装置、１２　回路基板、１４　カバー、１６　取入口、１８　光路部、２０　光源、２２　保持台、２４　焦電センサ、２６　光学フィルタ、２８　サーミスタ、３０　濃度検出部、４０　駆動回路、４２　増幅回路、４４　ＡＤ変換回路、４６　濃度変換処理回路。 10 gas concentration detection device, 12 circuit board, 14 cover, 16 inlet, 18 light path, 20 light source, 22 holding base, 24 pyroelectric sensor, 26 optical filter, 28 thermistor, 30 concentration detector, 40 drive circuit, 42 Amplification circuit, 44 AD conversion circuit, 46 density conversion processing circuit.

Claims (6)

  1. 　ガスの濃度に応じた濃度出力値を示す信号を出力する濃度検出部と、
    　前記ガスの温度に応じた温度出力値を示す信号を出力する温度検出部と、
    　予め定められた前記ガスの基準濃度において前記温度出力値に対応する基準出力値を算出し、前記濃度出力値を前記基準出力値で規格化した値、および前記規格化した値に対する前記ガスの濃度の関係を示す第１検量線に基づいて前記ガスの濃度を算出する算出部とを備え、
    　前記第１検量線は、前記温度出力値に比例する補正係数を含む、ガス濃度検出装置。     A concentration detector that outputs a signal indicating a concentration output value corresponding to the concentration of the gas;
    A temperature detector that outputs a signal indicating a temperature output value corresponding to the temperature of the gas;
    A reference output value corresponding to the temperature output value is calculated at a predetermined reference concentration of the gas, a value obtained by normalizing the concentration output value with the reference output value, and a concentration of the gas with respect to the normalized value A calculation unit that calculates the concentration of the gas based on a first calibration curve indicating the relationship of
    The gas concentration detection device, wherein the first calibration curve includes a correction coefficient proportional to the temperature output value.
  2. 　前記算出部は、前記ガスの温度変化に反比例して変化する前記ガスによる光の吸収率に応じた前記補正係数を算出する、請求項１に記載のガス濃度検出装置。 The gas concentration detection device according to claim 1, wherein the calculation unit calculates the correction coefficient according to the light absorption rate by the gas that varies inversely with the temperature change of the gas.
  3. 　前記算出部は、前記温度出力値、および前記温度出力値に対する前記基準出力値の関係を示す第２検量線に基づいて前記基準出力値を算出する、請求項１または２に記載のガス濃度検出装置。 The gas concentration detection according to claim 1, wherein the calculation unit calculates the reference output value based on the temperature output value and a second calibration curve indicating a relationship of the reference output value with respect to the temperature output value. apparatus.
  4. 　前記第２検量線は、前記基準濃度における前記ガスの複数の温度の各々に対応した、予め取得された複数の濃度出力値に基づいて所定の次数の近似式を導出して設定される、請求項３に記載のガス濃度検出装置。 The second calibration curve is set by deriving an approximate expression of a predetermined order based on a plurality of concentration output values acquired in advance corresponding to each of a plurality of temperatures of the gas at the reference concentration. Item 4. The gas concentration detection device according to Item 3.
  5. 　前記第１検量線は、基準温度における前記ガスの複数の濃度の各々に対応した、予め取得された複数の濃度出力値に基づいて前記補正係数が乗算された所定の次数の近似式を導出して設定される、請求項１～３のいずれかに記載のガス濃度検出装置。 The first calibration curve derives an approximate expression of a predetermined order multiplied by the correction coefficient based on a plurality of concentration output values acquired in advance corresponding to each of a plurality of concentrations of the gas at a reference temperature. The gas concentration detection device according to any one of claims 1 to 3, wherein the gas concentration detection device is set as follows.
  6. 　前記濃度検出部は、
    　検出対象のガスが導入される光路部と、
    　赤外線を放射する光源と、
    　前記光源から放射された前記赤外線を検出する受光センサと、
    　前記受光センサと前記光源との間に設けられるバンドパスフィルタとを含む、請求項１～５のいずれかに記載のガス濃度検出装置。     The concentration detector
    An optical path part into which the gas to be detected is introduced;
    A light source that emits infrared light;
    A light receiving sensor for detecting the infrared ray emitted from the light source;
    The gas concentration detection device according to any one of claims 1 to 5, further comprising a band pass filter provided between the light receiving sensor and the light source.
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019045240A (en) * 2017-08-31 2019-03-22 株式会社堀場製作所 Spectroscopic analyzer and spectral analysis method
CN110161181A (en) * 2018-02-13 2019-08-23 中国石油化工股份有限公司 The concentration of component recognition methods of mixed gas and system
WO2020066769A1 (en) * 2018-09-28 2020-04-02 株式会社フジキン Concentration measurement method
CN112557991A (en) * 2020-11-12 2021-03-26 珠海一多监测科技有限公司 Current transformer fault diagnosis method based on mole number and temperature
CN115931759A (en) * 2023-03-15 2023-04-07 浙江新寰科环保科技股份有限公司 Flue gas emission analysis system and method
JP7445557B2 (en) 2020-07-31 2024-03-07 株式会社Lixil Analysis method, analysis device that uses the analysis method, and program

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05264452A (en) * 1992-01-30 1993-10-12 Vaisala Oy Calibration for measurement of gas concentration
JPH06249779A (en) * 1993-02-26 1994-09-09 Shimadzu Corp Gas analyzer
JP2004309391A (en) * 2003-04-09 2004-11-04 Riken Keiki Co Ltd Method and detector for detecting gas concentration
JP2007502407A (en) * 2003-08-11 2007-02-08 センセエアー アーベー Method for compensating measurement errors and electronic configuration therefor
US20110049342A1 (en) * 2009-08-28 2011-03-03 Simon Tsao Gas concentration measurement device and method thereof
US8148691B1 (en) * 2009-08-21 2012-04-03 Jacob Y Wong Calibration methodology for NDIR dew point sensors
JP2012073098A (en) * 2010-09-28 2012-04-12 Asahi Kasei Electronics Co Ltd Gas concentration detection method and gas concentration sensor

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05264452A (en) * 1992-01-30 1993-10-12 Vaisala Oy Calibration for measurement of gas concentration
JPH06249779A (en) * 1993-02-26 1994-09-09 Shimadzu Corp Gas analyzer
JP2004309391A (en) * 2003-04-09 2004-11-04 Riken Keiki Co Ltd Method and detector for detecting gas concentration
JP2007502407A (en) * 2003-08-11 2007-02-08 センセエアー アーベー Method for compensating measurement errors and electronic configuration therefor
US8148691B1 (en) * 2009-08-21 2012-04-03 Jacob Y Wong Calibration methodology for NDIR dew point sensors
US20110049342A1 (en) * 2009-08-28 2011-03-03 Simon Tsao Gas concentration measurement device and method thereof
JP2012073098A (en) * 2010-09-28 2012-04-12 Asahi Kasei Electronics Co Ltd Gas concentration detection method and gas concentration sensor

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019045240A (en) * 2017-08-31 2019-03-22 株式会社堀場製作所 Spectroscopic analyzer and spectral analysis method
CN110161181A (en) * 2018-02-13 2019-08-23 中国石油化工股份有限公司 The concentration of component recognition methods of mixed gas and system
WO2020066769A1 (en) * 2018-09-28 2020-04-02 株式会社フジキン Concentration measurement method
JP7445557B2 (en) 2020-07-31 2024-03-07 株式会社Lixil Analysis method, analysis device that uses the analysis method, and program
CN112557991A (en) * 2020-11-12 2021-03-26 珠海一多监测科技有限公司 Current transformer fault diagnosis method based on mole number and temperature
CN112557991B (en) * 2020-11-12 2024-05-28 珠海一多监测科技有限公司 Current transformer fault diagnosis method based on mole number and temperature
CN115931759A (en) * 2023-03-15 2023-04-07 浙江新寰科环保科技股份有限公司 Flue gas emission analysis system and method

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