Apparatus and Method

Abstract

The present invention provides an apparatus and a method. The apparatus comprises: a measuring unit having a light-emitting unit and a first sensor for measuring a first measured value of a first physical quantity, the first physical quantity changing in response to light emitted from the light-emitting unit passing through a measuring object; a second sensor for measuring a second measured value of a second physical quantity, the second physical quantity being a physical quantity related to the measuring unit that is independent of the concentration of a target gas included in the measuring object and correlated with a reference value of the first measured value; a third sensor for measuring a third measured value of a third physical quantity, the third physical quantity being independent of the concentration of a target gas included in the measuring object and correlated with a reference value; a detection unit for detecting the presence or concentration of a target gas included in the measuring object based on the first measured value; and a determination unit for determining, using the second and third measured values, whether the amount of degradation of the accuracy of the first measured value exceeds a threshold.

Description

Technical Field

[0001] This invention relates to an apparatus and a method. Background Technology

[0002] Patent document 1 describes "a gas sensor that provides high-precision correction for the effects of light source degradation".

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-015516

[0006] Patent Document 2: Japanese Patent Publication No. 2007-502407 Summary of the Invention

[0007] In a first aspect of the present invention, an apparatus is provided, comprising: a measuring unit having a light-emitting unit and a first sensor for measuring a first measured value of a first physical quantity, the first physical quantity being a physical quantity that changes in response to light emitted from the light-emitting unit passing through a measuring object; a second sensor for measuring a second measured value of a second physical quantity, the second physical quantity being a physical quantity related to the measuring unit that is independent of the concentration of a target gas included in the measuring object and correlated with a reference value of the first measured value; a third sensor for measuring a third measured value of a third physical quantity, the third physical quantity being independent of the concentration of a target gas included in the measuring object and correlated with the reference value; a detection unit for detecting the presence or concentration of a target gas included in the measuring object based on the first measured value; and a determination unit for determining, using the second measured value and the third measured value, whether the amount of degradation of the accuracy of the first measured value exceeds a threshold.

[0008] In a second aspect of the invention, a method is provided, comprising the following stages: measuring the first measurement value by a measuring unit having a light-emitting part and a first measurement value of a first sensor for measuring a first physical quantity, the first physical quantity being a physical quantity that changes in response to light emitted from the light-emitting part passing through a measurement object; measuring a second measurement value of a second physical quantity, the second physical quantity being a physical quantity related to the measuring unit that is independent of the concentration of a target gas included in the measurement object and correlated with a reference value of the first measurement value; measuring a third measurement value of a third physical quantity, the third physical quantity being independent of the concentration of a target gas included in the measurement object and correlated with the reference value; detecting the presence or concentration of the target gas included in the measurement object based on the first measurement value; and using the second measurement value and the third measurement value to determine whether the amount of degradation of the accuracy of the first measurement value exceeds a threshold.

[0009] Furthermore, the above summary of the invention does not enumerate all the essential features of the invention. Additionally, sub-combinations of these feature groups can also constitute inventions. Attached Figure Description

[0010] Figure 1 An example of the structure of the concentration measuring device 100 is shown.

[0011] Figure 2 An example of a method for calculating the concentration of the target gas using standard curve data is shown.

[0012] Figure 3 This demonstrates a method for correcting measurement errors using zero-point calibration.

[0013] Figure 4 This demonstrates a method for correcting measurement errors using span correction.

[0014] Figure 5 An example of an operational flowchart of the concentration measuring device 100 is shown.

[0015] Figure 6 The concentration measuring device 100A involved in the modified example is shown. Detailed Implementation

[0016] The present invention will now be described through embodiments thereof; however, these embodiments are not intended to limit the invention as defined in the claims. Furthermore, not all combinations of features described in the embodiments are necessarily necessary for the solution of the invention.

[0017] Figure 1An example of the structure of a concentration measuring device 100 is shown. The concentration measuring device 100 includes a ventilation control unit 60, a light-emitting unit 10, an infrared detection unit 20, a temperature measuring unit 30, a signal processing unit 40, a notification unit 70, and an indicator unit 80. In this example, the concentration measuring device 100 includes a light path unit 12 and a reflective unit 14. The concentration measuring device 100 uses infrared light to measure the concentration of the target gas included in the measurement object 110.

[0018] The analyte 110 is the substance whose concentration of the target gas is being measured. The analyte 110 can be a gas or a liquid. The target gas is carbon dioxide, but is not limited to this. If the analyte 110 is a liquid, the target gas can also be a gas dissolved in that liquid.

[0019] The ventilation control unit 60 causes a ventilation device (not shown) to ventilate the target gas of the measurement object 110. The ventilation device can ventilate the entire space where the concentration measuring device 100 is installed, or it can ventilate only the target gas 110 within the optical path unit 12. For example, the ventilation device can be an air conditioner or a ventilation fan. The ventilation device can also be any other device capable of flowing a gas containing the target gas at a reference concentration (for example, atmospheric concentration) to the space where the concentration measuring device 100 is installed and to the optical path unit 12.

[0020] The ventilation control unit 60 can perform ventilation in response to user operation. The ventilation control unit 60 or the ventilation device can supply ventilation information indicating that the gas of the measurement object 110 has been ventilated to the signal processing unit 40. For example, the ventilation control unit 60 or the ventilation device can output ventilation information in response to the end of ventilation.

[0021] The light-emitting unit 10 emits or transmits infrared rays for measuring the concentration of the target gas. To allow the infrared rays to pass through the target 110 and thus calculate the concentration of the target gas, the light-emitting unit 10 can emit infrared rays with a fixed amount of light. The light-emitting unit 10 can also be located outside the concentration measuring device 100.

[0022] The optical path section 12 is an optical path for allowing infrared light to pass through the measurement object 110. The optical path section 12 includes the measurement object 110, allowing infrared light to pass through the measurement object 110 with a predetermined optical path length. The optical path section 12 can be a container for holding the measurement object 110 in a closed space, or it can be a flow path for allowing the measurement object 110 to flow. The measurement object 110 within the optical path section 12 can be in communication with the outside air. Infrared light reflected by the reflector 14 can also pass through the optical path section 12. The optical path section 12 may have a light-transmitting region 120 that does not include the measurement object 110. The transmittance of the light-transmitting region 120 is a reference transmittance that does not change depending on the gas concentration within the measurement object 110. The light-transmitting region 120 may include a sealed space isolated from the measurement object 110, or it may include a light-transmitting component such as glass.

[0023] The infrared detection unit 20 detects the infrared radiation emitted by the light-emitting unit 10 and outputs a detection signal Sd. In this example, the infrared detection unit 20 has a first detection unit 21 and a second detection unit 22. The first detection unit 21 and the second detection unit 22 each have an infrared sensor for detecting the infrared radiation emitted by the light-emitting unit 10. The infrared detection unit 20 may have a quantum well type sensor for detecting infrared radiation. The first detection unit 21 and the second detection unit 22 may each be a quantum well type sensor.

[0024] The first detection unit 21 is an example of a first sensor, used to measure a first measured value of a first physical quantity (in this embodiment, the intensity of infrared radiation is an example), which is a physical quantity that changes in response to the infrared radiation from the light-emitting unit 10 passing through the measurement object 110. The first detection unit 21 detects the intensity of the infrared radiation passing through the measurement object 110 as the first measured value, and outputs a first output signal So1 representing the detected first measured value to the signal processing unit 40. Infrared radiation incident on the first detection unit 21, after being emitted from the light-emitting unit 10, may or may not pass through the light-transmitting region 120, which does not include the measurement object.

[0025] The amount of infrared light incident on the first detection unit 21 varies depending on the concentration of the target gas included in the measurement object 110. For example, the amount of infrared light incident on the first detection unit 21 varies according to the Lambert-Beer law. In this example, the first detection unit 21 detects infrared light reflected by the reflective part 14. That is, the first detection unit 21 detects infrared light that has passed through the measurement object 110, been reflected by the reflective part 14, and then passed through the measurement object 110 again. However, it is also possible for the first detection unit 21 to detect infrared light emitted by the light-emitting part 10 without the reflective part 14 reflecting it.

[0026] The accuracy of the first measured value may deteriorate due to changes in the operating environment of the concentration measuring device 100, changes in the condition of the concentration measuring device 100 (for example, the deterioration of the first detection unit 21 over the years, and changes in its performance). Therefore, the first measured value is appropriately corrected by the correction unit 43 described later in the signal processing unit 40.

[0027] The first detection unit 21 and the light-emitting unit 10 can constitute a measuring unit (also called a main measuring unit or main measuring device) 1000, which mainly measures the concentration of the target gas included in the target. In addition, the main measuring unit 1000 may also include other structures such as an optical path unit 12.

[0028] The second detection unit 22 is an example of a second sensor, measuring a second measured value of a second physical quantity. This second physical quantity is a physical quantity related to the main detection unit 1000 that is independent of the concentration of the target gas included in the target 110 and correlated with the reference value SV (Standard Value) of the first measured value. The physical quantity related to the main detection unit 1000 may be a measured physical quantity relating to the elements included in the main detection unit 1000 (for example, a light-emitting element, elements of the sensor section) (for example, resistance value, supply voltage), or it may be the same type of physical quantity measured to determine the reference value of the physical quantity measured by the main detection unit 1000, or it may be a measured physical quantity relating to the elements used to measure that same type of physical quantity. The reference value SV may be a value used to correct the first measured value in the correction unit 43 described later.

[0029] In this embodiment, as an example, the second detection unit 22 measures the intensity of infrared radiation emitted from the light-emitting unit 10 and passing through the light-transmitting region 120 with a reference transmittance. The second detection unit 22 detects the intensity of infrared radiation that does not pass through the measurement object 110 as a second measured value, and outputs a second output signal So2 representing the detected second measured value to the signal processing unit 40. The second detection unit 22 detects infrared radiation of a fixed amount of light without being affected by the concentration of the measurement object 110. The infrared radiation emitted by the light-emitting unit 10 can be detected by the second detection unit 22 without reflection from the reflective unit 14.

[0030] The detection signal Sd is based on the first output signal So1 and the second output signal So2. The detection signal Sd may include each of the first output signal So1 and the second output signal So2. The detection signal Sd may also include the signal ratio of the first output signal So1 to the second output signal So2. By comparing the first output signal So1 and the second output signal So2 output by the infrared detection unit 20, the concentration change of the target gas included in the measurement object 110 can be detected.

[0031] The infrared sensor in the infrared detection unit 20 can be either a thermoelectric sensor or a quantum well sensor. At least one of the first detection unit 21 and the second detection unit 22 can be a quantum well sensor. By using a quantum well sensor, the infrared detection unit 20 can achieve a faster response compared to a thermoelectric sensor. In addition, the quantum well sensor can measure the absolute value of the signal, thus enabling simpler signal processing.

[0032] Furthermore, the light-emitting unit 10 can branch the light path after emitting infrared light from a shared single light-emitting element, allowing the first detection unit 21 and the second detection unit 22 to detect infrared light from different light paths. Alternatively, the light-emitting unit 10 can emit multiple infrared rays from different light-emitting elements, allowing the first detection unit 21 and the second detection unit 22 to detect infrared light from different light paths.

[0033] The temperature measuring unit 30 is an example of a third sensor, used to measure a third measured value of a third physical quantity. This third physical quantity is independent of the concentration of the target gas included in the measurement object 110 and correlated with a reference value SV of the first measured value. The third measured value may be correlated with a second measured value. In this embodiment, as an example, the temperature measuring unit 30 measures the temperature of the measurement object 110 or the concentration measuring device 100. The temperature measuring unit 30 can supply the measured temperature T, representing the measured third measured value, to the signal processing unit 40.

[0034] The temperature measuring unit 30 can use any temperature sensor to measure the temperature at any location of the concentration measuring device 100. For example, the temperature measuring unit 30 can measure the temperature of the light emitting unit 10, the infrared detection unit 20, or the signal processing unit 40.

[0035] In one example, the temperature measuring unit 30 uses the second detection unit 22 to measure the temperature of the infrared detection unit 20. The temperature measuring unit 30 can measure the temperature of the second detection unit 22 based on the second output signal So2. Specifically, the temperature measuring unit 30 can measure the temperature of the second detection unit 22 based on the infrared signal value of the second detection unit 22. Specifically, the temperature measuring unit 30 can measure the temperature of the second detection unit 22 based on its resistance value. The second output signal So2 can be used as a thermometer by pre-measuring its temperature dependence. Furthermore, the temperature dependence of the second output signal So2 can be stored in the storage unit 45, described later.

[0036] Here, temperature characteristics that affect concentration calculations may sometimes occur in the light-emitting unit 10 or the infrared detection unit 20. Additionally, the light absorption characteristics of the object being measured 110 may also affect concentration calculations due to temperature variations. Therefore, by performing calibration based on these temperatures, the concentration measuring device 100 can easily calculate the concentration of the object being measured 110 with higher accuracy.

[0037] The signal processing unit 40 includes a signal acquisition unit 41, a temperature information acquisition unit 42, a correction unit 43, a calculation unit 44, a storage unit 45, a determination unit 46, and a ventilation information acquisition unit 47. The signal processing unit 40 may be configured as a microcomputer.

[0038] The signal acquisition unit 41 acquires the detection signal Sd from the infrared detection unit 20. The signal acquisition unit 41 inputs the detection signal Sd to the calibration unit 43 and the determination unit 46. The signal acquisition unit 41 may also acquire the detection signal Sd from the infrared detection unit 20, which is located outside the concentration measuring device 100. The signal acquisition unit 41 may acquire the first output signal So1 and the second output signal So2 as the detection signal Sd, or it may acquire the signal ratio of the first output signal So1 to the second output signal So2 as the detection signal Sd. The signal acquisition unit 41 may also acquire the first output signal So1 and the second output signal So2 to generate the signal ratio of the first output signal So1 to the second output signal So2.

[0039] The temperature information acquisition unit 42 acquires the measured temperature T measured by the temperature measuring unit 30. The measured temperature T can be the temperature of the object being measured 110. The measured temperature T can also be the temperature of the light-emitting unit 10, the infrared detection unit 20, or the signal processing unit 40. The temperature information acquisition unit 42 can also acquire the measured temperature T from the temperature measuring unit 30 located outside the concentration measuring device 100. The temperature information acquisition unit 42 inputs the acquired measured temperature T to the calibration unit 43 and the determination unit 46.

[0040] The calibration unit 43 outputs a calibration signal Sc obtained by correcting the detection signal Sd. In this embodiment, as an example, the calibration unit 43 generates the calibration signal Sc by correcting the detection signal Sd (e.g., zero-point correction, span correction) based on the detection signal Sd and the measurement temperature T. As an example, the calibration unit 43 can perform zero-point correction on the detection signal Sd by adding, subtracting, or multiplying / dividing a value based on the measurement temperature T (e.g., the correction coefficient Zero(T) described later).

[0041] The calibration unit 43 can use a reference value SV to calibrate the first output signal So1 (e.g., degradation correction). For example, the calibration unit 43 calibrates the first output signal So1 in a manner that makes it consistent with the reference value SV when the gas to be measured is not included in the measurement object 110 at a concentration higher than that in the atmosphere. As an example, the calibration unit 43 can perform degradation correction on the first output signal So1 by adding, subtracting, or multiplying / dividing the deviation amount Δ described later.

[0042] As an example, the reference value SV is a predetermined value, calculated using the function So1 / So2×Zero(T) when the target gas is not included in the measurement object 110 at a concentration greater than that in the atmosphere. This is done using the first output signal So1 output from the first detection unit 21, a correction coefficient Zero(T) determined based on the measurement temperature T measured by the temperature measurement unit 30, and the second output signal So2 output from the second detection unit 22. This reference value SV can be set at the time of factory shipment of the concentration measuring device 100. The correction coefficient Zero(T) can be a value that varies according to temperature.

[0043] Instead, the reference value SV can also be the value of the predetermined first output signal So1 output from the first detection unit 21 when the target gas 110 does not contain the target gas at a concentration greater than that in the atmosphere. This reference value SV can be set at the time of factory shipment of the concentration measuring device 100. The target gas 110 that does not contain the target gas at a concentration greater than that in the atmosphere can be a target gas 110 that does not contain the target gas, or it can be a target gas 110 immediately after a ventilation process. When the target gas is carbon dioxide, the atmospheric concentration can be 400 ppm.

[0044] The calibration unit 43 can be an example of a calibration unit, capable of calibrating the first measured value obtained by the first detection unit 21. As calibration of the first measured value, the calibration unit 43 can calibrate the first output signal So1 representing the first measured value. The calibration of the first output signal So1 can determine the deviation Δ between a predetermined reference value SV (Standard Value) of the first output signal So1 and a reference value SV' that should be used in the current situation. The calibration unit 43 can calibrate the first output signal So1 based on the reference value of the first output signal So1. In this embodiment, as an example, the deviation Δ between the reference value SV and the reference value SV' can be determined. The reference value SV' can vary depending on changes in the operating environment of the concentration measuring device 100, changes in the state of the concentration measuring device 100 (for example, the deterioration of the first detection unit 21 over the years, changes in its performance), etc.

[0045] The calibration unit 43 can perform calibration using the measurement results from the first detection unit 21, the second detection unit 22, and the temperature measurement unit 30. In this embodiment, as an example, the calibration unit 43 acquires the first output signal So1, the second output signal So2, and the measured temperature T, calculates the reference value SV' using SV' = So1 / So2 × Zero(T), and determines the deviation amount Δ.

[0046] Instead, the calibration unit 43 can also use the measurement results of the first detection unit 21 when the target gas is not included in the measurement object 110 at a concentration greater than that in the atmosphere. In this case, the calibration unit 43 uses the value of the first output signal So1 output from the first detection unit 21 when the target gas is not included in the measurement object 110 at a concentration greater than that in the atmosphere as the reference value SV' to determine the deviation amount Δ. As the measurement result of the first detection unit 21 when the target gas is not included in the measurement object 110 at a concentration greater than that in the atmosphere, i.e., the reference value SV', the calibration unit 43 can use the measurement result immediately after the ventilation, or the measurement result when the concentration of the target gas is at its lowest after the last calibration. When the calibration unit 43 uses the measurement result when the concentration of the target gas is at its lowest as the reference value SV', it can use multiple measurement results of the first detection unit 21 to determine the reference value SV'. For example, the measurement result when the concentration of the target gas is at its lowest among the multiple measurement results can be determined as the reference value SV'.

[0047] The calibration unit 43 can perform calibration in response to receiving a signal (also called a calibration indication signal) indicating calibration execution from the ventilation information acquisition unit 47, the determination unit 46 (described later), the indication unit 80, etc. If calibration has been performed, the calibration unit 43 can use the calibrated deviation amount Δ to correct for degradation of the first output signal So1.

[0048] The calibration unit 43 outputs a calibration signal Sc corresponding to the calibrated first output signal So1. The calibration unit 43 can supply the calibration signal Sc to the calculation unit 44. In addition, the calibration unit 43 can supply a signal indicating that the first measured value has been calibrated to the calculation unit 44.

[0049] The calculation unit 44 is an example of a detection unit, which detects the concentration of the target gas included in the measurement object 110 based on a first measured value (in this embodiment, for example, the first output signal So1). The calculation unit 44 can detect the concentration of the target gas based on a correction signal Sc. For example, the calculation unit 44 uses predetermined standard curve data for calculating the concentration of the target gas to calculate the concentration of the target gas corresponding to the correction signal Sc. For example, the calculation unit 44 calculates the concentration of the target gas using common standard curve data at a reference temperature (25°C) by correcting the detection signal Sd at an arbitrary measurement temperature Tm and applying it to the standard curve data. Therefore, it is not necessary to change the standard curve data according to the measurement temperature T. The standard curve data will be described later. The calculation unit 44 can be an example of an output unit, which can output the detection result of the concentration of the target gas to the outside of the concentration measuring device 100. In addition, the calculation unit 44 can count the elapsed time after calibration by the correction unit 43.

[0050] The storage unit 45 stores the information needed to calculate the concentration of the target gas 110. In this example, the storage unit 45 stores information such as correction parameters used in the correction unit 43 to correct the detection signal Sd. The storage unit 45 may also store standard curve data used in the calculation unit 44 to calculate the concentration of the target gas.

[0051] The determination unit 46 uses a second measured value (in this embodiment, for example, the second output signal So2) and a third measured value (in this embodiment, for example, the measured temperature T) to determine whether the degradation amount E of the accuracy of the first measured value (in this embodiment, for example, the first output signal So1) exceeds a threshold. For example, the determination unit 46 calculates the value of the degradation amount E of the accuracy of the first measured value as a function of the second and third measured values, which is a predetermined value when the accuracy of the first measured value has not deteriorated. The threshold can be set arbitrarily. The determination unit 46 can supply a calibration instruction signal to the calibration unit 43 in response to the degradation amount E exceeding the threshold. Thus, the calibration of the first measured value is performed in response to the degradation amount E exceeding the threshold. The determination unit 46 can also supply a signal indicating this to the notification unit 70 in response to the degradation amount E exceeding the threshold.

[0052] Furthermore, the threshold for judgment can be a fixed value or a variable value. For example, the threshold for judgment can be increased or decreased each time the first measurement is calibrated. As an example, in the case where calibration is performed in response to the degradation amount E exceeding the threshold V, the threshold V can be updated to a value of V+E or V×E.

[0053] Here, the degradation amount E will be explained. When the first measured value is calibrated in the calibration unit 43 as described above, the first output signal So1 immediately following the calibration... (劣化前) With the second output signal So2 (劣化前) Between these concentrations, at a concentration that serves as the calibration reference (e.g., a concentration below the atmospheric concentration), the following relationship (1) holds.

[0054] So1 (劣化前) =So2 (劣化前) / Zero(T)…(1)

[0055] On the other hand, when the measurement accuracy of the first measured value deteriorates, and the second measured value also exhibits approximately the same deterioration characteristics, the deteriorated first output signal So1 (劣化后) Second output signal So2 (劣化后) It is expressed as in equations (2) and (3) below. In addition, “A” in the equation is a coefficient corresponding to the deterioration progress, and “δ” represents a coefficient corresponding to the difference in the deterioration progress between the first and second measured values.

[0056] So1 (劣化后) =So1 (劣化前) ×A…(2)

[0057] So2 (劣化后) / Zero(T)=So2 (劣化前) / Zero(T)×(A+δA)…(3)

[0058] According to these equations (2) and (3), at the concentration used as the calibration reference, when the measurement accuracy of the first measured value deteriorates, based on So2... (劣化前) The value of / Zero(T)×δA represents the measurement error of the concentration of the target gas.

[0059] Furthermore, when obtaining the degradation amount E, a function G(So2, T) that varies according to the second output signal value So2 and the measurement temperature T, and which will become a predetermined value (in this embodiment, "1" as an example) if the accuracy of the first output signal So1 is not degraded, can be obtained in advance. The function G(So2, T) is expressed as an example as shown in equation (4) below. In addition, f(T) in the equation is a function that varies according to the measurement temperature T.

[0060] G(So2,T)=So2 (劣化后) / f(T)…(4)

[0061] The value of the function G(So2,T) can be expressed as (A+δA) in equation (3). Therefore, in this embodiment, as an example, the value of the function G(So2,T) is used as the degradation amount E.

[0062] The ventilation information acquisition unit 47 acquires ventilation information indicating that the gas in the measurement object 110 has been ventilated. For example, the ventilation information acquisition unit 47 acquires ventilation information from the ventilation device or the ventilation control unit 60. However, the ventilation information acquisition unit 47 may also acquire ventilation information based on user operation of the instruction unit 80 described later. In response to acquiring the ventilation information, the ventilation information acquisition unit 47 can supply a calibration instruction signal to the calibration unit 43. Thus, in response to acquiring the ventilation information, the calibration unit 43 calibrates the first output signal So1.

[0063] The notification unit 70 notifies the user of various information. For example, the notification unit 70 may be a first notification unit, or it may notify the user by receiving a signal indicating that the degradation amount E exceeds a threshold from the determination unit 46. Thus, the user is notified in response to the degradation amount E exceeding the threshold.

[0064] The notification unit 70 can issue notifications by displaying notification messages, outputting sound messages, or illuminating indicators. For example, the notification unit 70 can communicate wirelessly or via a wired connection with an external display device of the concentration measuring device 100 to display notification messages. The display device can be a remote control for the ventilation device, or a user terminal such as a smartphone or PC.

[0065] The indicator unit 80 receives various operation inputs from the user and supplies signals corresponding to the input operation to various parts of the concentration measuring device 100. For example, the indicator unit 80 may supply a signal indicating ventilation to the ventilation control unit 60 in response to an input ventilation instruction operation.

[0066] Additionally, the indicator unit 80 can supply a calibration instruction signal to the calibration unit 43 in response to a calibration instruction operation. Thus, calibration is performed by the calibration unit 43 in response to a calibration instruction operation received from the user. Furthermore, a calibration instruction operation can be input in response to notification by the notification unit 70 that the degradation amount E exceeds a threshold, or in response to ventilation of the measurement object 110.

[0067] The concentration measuring device 100 is housed within a housing 50. That is, the concentration measuring device 100 is integrated within the housing 50. In this example, the concentration measuring device 100 is integrated in a manner that includes, in addition to the signal processing unit 40, a light-emitting unit 10, an optical path unit 12, a reflective unit 14, an infrared detection unit 20, and a temperature measuring unit 30. However, any of these components can be disposed outside the housing 50. In other words, the concentration measuring device 100 can also acquire the detection signal Sd and the measurement temperature T measured outside the housing 50 to calculate the concentration of the target gas.

[0068] Here, the Lambert-Beer law is used to explain the absorption of infrared radiation by the object being measured 110. In this example, a gas is used as the object being measured 110, but this is not a limitation. The amount of infrared radiation absorbed by the gas, Abs, is expressed by the following formula.

[0069] Abs = I0 - I0 × e -k×l×c

[0070] I0 represents the ideal amount of light arriving without the influence of gas. k is the gas-dependent absorption coefficient, l is the optical path length, and c is the gas concentration. The absorbance AR is expressed by the following formula.

[0071] AR = 1 - e -k×l×c

[0072] When the correction parameters for zero-point and span corrections have temperature coefficients, each correction parameter is expressed by the following formula. Furthermore, zero-point and span corrections are described later.

[0073] Correction parameter Zero(T) = Zero × fz(T)

[0074] Correction parameter Span(T) = Span × fs(T)

[0075] In this case, the absorption signal Signal_Abs is represented by the following formula.

[0076] Signal_Abs=(1-(So1 / So2)×Zero(T))×Span(T)

[0077] For example, when the correction parameters are determined by setting 0 ppm as the reference concentration for zero-point correction and by making the absorbance signal Signal_Abs equal to 0 at a concentration of 0 ppm, the following relation (1') holds. The above relation (1) can be derived from relation (1').

[0078] So1=So2 / Zero(T)…(1')

[0079] The amount of light arriving is expressed by the following formula.

[0080] I0-Abs=I0-(I0-I0×e -k×l×c )

[0081] Furthermore, the arriving light signal (Signal) is represented by the following formula.

[0082] Signal=1-(1-(So1 / So2)×Zero(T))×Span(T)

[0083] In this way, the concentration measuring device 100 can calculate the concentration of the target gas in the target 110 by acquiring a signal corresponding to the concentration of the target gas in the target 110.

[0084] The concentration measuring device 100 described above emits infrared light from the light-emitting unit 10 and measures the intensity of the infrared light passing through the target gas 110 using the first detection unit 21. Therefore, the concentration of the target gas can be detected using the so-called NDIR method. Furthermore, the detection result is output from the calculation unit 44, so the concentration of the target gas can be notified to the user.

[0085] Furthermore, the presence or absence of accuracy degradation of the first output signal So1 is determined using a second measured value (in this embodiment, the second output signal So2) that is correlated with the reference value SV of the first measured value (in this embodiment, the first output signal So1 for example) and a third measured value (in this embodiment, the measurement temperature T for example) that is correlated with the reference value SV, which are related to the main measuring unit 1000. Therefore, changes in the operating environment of the concentration measuring device 100 that affect the measurement accuracy of the first measured value, and changes in the state of the concentration measuring device 100 (for example, the deterioration of the first detection unit 21 over the years, and changes in its performance) can be detected. In addition, the decrease in accuracy of the first output signal So1 caused by the deviation of the reference value SV can be detected regardless of the concentration of the target gas in the current measurement object 110, thereby detecting the decrease in the measurement accuracy of the target gas concentration. Therefore, by calibrating the first output signal So1 in response to the detection of a decrease in accuracy, the measurement accuracy of the target gas concentration can be maintained at a high level. Furthermore, by suspending the calibration process until a decrease in the accuracy of the first output signal So1 is detected, unnecessary calibrations can be prevented. Therefore, the computational processing required for calibration can be reduced, thereby decreasing power consumption and improving the operating efficiency of the concentration measuring device 100.

[0086] Furthermore, the value of G(So2, T), a function defined by the second output signal So2 and the measured temperature T, which would become 1 if the accuracy of the first output signal So1 were not degraded, is taken as the amount of accuracy degradation E. Therefore, the amount of degradation E can be evaluated based on how far the function value deviates from 1, thus making it easy to determine whether degradation exists.

[0087] Furthermore, the first output signal So1 is calibrated using the measurement results from the second detection unit 22 and the temperature measurement unit 30. Therefore, the calibration of the first output signal So1, that is, the determination of the deviation Δ between the reference value SV of the first output signal So1 and the reference value SV' that should be used under the current conditions, can also be performed using sensors for determining the accuracy degradation of the first output signal So1 and for zero-point calibration of the first output signal So1. Therefore, it is not necessary to separately install sensors for determining accuracy degradation, zero-point calibration of the first output signal So1, and calibration of the first output signal So1, thereby preventing the concentration measuring device 100 from becoming too large.

[0088] Furthermore, by using multiple first output signals So1 output by the first detection unit 21 to determine a reference value and calibrating the first output signals So1 based on this reference value, accurate calibration can be performed based on a more suitable reference value. Additionally, the second output signal So2 and the measurement temperature T are used in the calculation of the degradation amount E, while the first output signal So1 is used in the calculation of the reference value SV of the first output signal So1. Therefore, the calculation of the reference value SV of the first output signal So1 and the calculation of the degradation amount E can be performed independently. Furthermore, by determining the calibration reference value SV based on the first output signal So1 itself, which is the object of calibration, calibration can be performed more accurately based on a more suitable reference value SV compared to the case where calibration is performed using the degradation amount E.

[0089] In addition, the first output signal So1 is calibrated in response to the degradation amount E exceeding the threshold, so the accuracy of the first output signal So1 can be maintained at a high level, thereby maintaining the accuracy of the concentration measurement of the target gas at a high level.

[0090] Furthermore, since calibration is performed in response to a calibration instruction received from the user, calibration can be performed at the time desired by the user. Therefore, for example, calibration can be performed when ventilation has been performed, indicating that the degradation amount E has exceeded a threshold.

[0091] Furthermore, since calibration is performed in response to obtaining ventilation information indicating that the test object 110 has been ventilated, calibration can be performed using the measurement results of the first detection unit 21 when the test object 110 does not include the target gas at a concentration greater than that in the atmosphere. Therefore, unlike calibration performed using the measurement results of the first detection unit 21 when the test object 110 includes the target gas at a concentration greater than that in the atmosphere or when the concentration of the target gas is unknown, accurate calibration can be performed.

[0092] Furthermore, since ventilation information can be obtained from either the ventilation device for ventilating the gas being measured 110 or the ventilation control unit 60 that enables the ventilation device to perform ventilation, the timing of ventilation can be accurately detected for calibration. Therefore, accurate calibration can be reliably performed.

[0093] In addition, the system notifies the user in response to the degradation amount E exceeding the threshold. Therefore, even if calibration is not automatically performed in response to the degradation amount E exceeding the threshold, the user can still be instructed to perform ventilation and calibration operations.

[0094] Furthermore, it has been described that the determination unit 46 calibrates and notifies the correction unit 43 and the notification unit 70 in response to the degradation amount E exceeding a threshold. However, it is also possible that the determination unit 46 calibrates and notifies the correction unit 43 and the notification unit 70 after a reference period (also called the degradation determination period) has elapsed since the period during which the degradation amount E exceeds the threshold. In this case, it is possible to prevent unnecessary calibration and notification in response to reversible and temporary changes in the condition. The degradation determination period can be considered as the period during which the measurement accuracy of the first measured value has indeed deteriorated, and can be arbitrarily set from the viewpoint of preventing false detections of degradation.

[0095] Figure 2 An example of a method for calculating the concentration of the target gas using standard curve data is shown. In this example, the standard curve data is data at a predetermined reference temperature (e.g., 25°C). The sensor output signal Sa on the vertical axis can be either the absorbance signal Signal_Abs or the arrival light signal Signal. By generating the sensor output signal Sa(Tm) at the measurement temperature Tm, the concentration measuring device 100 can calculate the concentration of the target gas included in the measurement object 110 using the shared standard curve data.

[0096] Figure 3 This illustrates a method for correcting measurement errors using zero-point calibration. The solid line represents the reference signal line, indicating the concentration dependence of the measured signal. The dashed line represents the measured signal line, indicating the concentration dependence of the measured signal. For example, calibration is performed by moving the measured signal line in a manner that makes the measured signal intensity at a concentration of 0 ppm consistent with the reference signal intensity. In this example, the measured signal line with the signal intensity ratio S = So1 / So2 is calibrated, but the types of signals calibrated are not limited to this.

[0097] Furthermore, in this example, a signal intensity of 0 ppm for the detected gas is used to align the measured signal line with the reference signal line. However, calibration can also be performed using a concentration other than 0 ppm as the reference. For example, when the detected gas is carbon dioxide, a signal intensity of 400 ppm can be used for calibration. The reference signal line can be set at the time of factory shipment.

[0098] Figure 4 This describes a method for correcting measurement errors using span correction. In span correction, the gradient of the measured signal line, represented by the dashed line, is adjusted to ensure that the difference between the measured signal line and the reference signal line within the measured concentration range is within a predetermined range. In this example, the correction ensures that the intensity change of the measured signal line within the measured concentration range from a predetermined gas concentration (e.g., 0 ppm) is within a predetermined reference output range. The correction unit 43 can also use zero-point correction and span correction to correct temperature characteristics. The content of the reference signal line can be set at the time of factory shipment.

[0099] Figure 5 An example of the operation flowchart of the concentration measuring device 100 is shown. The concentration measuring device 100 measures the concentration of the target gas while calibrating the first output signal So1 through the processing of steps S11 to S35.

[0100] In step S11, the light-emitting unit 10 emits light, and the first detection unit 21, the second detection unit, and the temperature measuring unit 30 perform measurements. In this embodiment, as an example, the first detection unit 21 measures a first measured value to output a first output signal So1, the second detection unit 22 measures a second measured value to output a second output signal So2, and the temperature measuring unit 30 measures the measured temperature T.

[0101] In step S13, the calculation unit 44 determines whether a reference time (also called an automatic calibration period) has elapsed since the last calibration performed by the calibration unit 43. The automatic calibration period can be any period during which automatic calibration can be performed after the reference time has elapsed, and can be arbitrarily set. The automatic calibration period can also be a period during which at least one ventilation change should be performed after calibration. The automatic calibration period can be a period during which the accuracy of the first measured value after calibration is suspected to have deteriorated. The automatic calibration period can be a period shorter than the aforementioned deterioration determination period. Furthermore, the calibration performed by the calibration unit 43 can be performed in steps S17, S29, S35, etc., as described later.

[0102] If it is determined in step S13 that no automatic calibration period has been completed (step S13: "No"), the process can proceed to step S21. If it is determined in step S13 that an automatic calibration period has been completed (step S13: "Yes"), the process can proceed to step S15.

[0103] In step S15, the determination unit 46 calculates the degradation amount E and determines whether the degradation amount E exceeds a threshold (also referred to as threshold 1, distinct from the threshold used in step S21 described later). Threshold 1 may be an example of a first threshold. If it is determined that the degradation amount E does not exceed threshold 1 (step S15: "No"), the process may proceed to step S19. If it is determined that the degradation amount E exceeds threshold 1 (step S15: "Yes"), the determination unit 46 may output a calibration indication signal, and the process may proceed to step S17.

[0104] In step S17, the calibration unit 43 calibrates the first output signal So1. For example, the calibration unit 43 uses the measurement results from the first detection unit 21 when the concentration of the target gas is at its lowest after the last calibration to calculate the reference value SV', and determines the deviation Δ between the predetermined reference value SV and the calculated reference value SV'. Alternatively, the calibration unit 43 uses the measurement results from the first detection unit 21, the second detection unit 22, and the temperature measurement unit 30 when the concentration of the target gas is at its lowest after the last calibration to calculate the reference value SV', and determines the deviation Δ between the calculated reference value SV' and the predetermined reference value SV. Thus, the first output signal So1 is calibrated in response to the degradation amount E exceeding the threshold 1 after the automatic calibration period since the last calibration.

[0105] In step S19, the correction unit 43 corrects the first output signal So1 to generate a correction signal Sc, and the calculation unit 44 detects the concentration of the target gas based on the correction signal Sc.

[0106] The correction unit 43 can perform at least one of zero-point correction and span correction on the first output signal So1. Alternatively, the correction unit 43 can perform degradation correction on the first output signal So1, that is, add, subtract, or multiply / divide the deviation amount Δ of the reference value SV on the first output signal So1. This generates a correction signal Sc. In this embodiment, as an example, the correction unit 43 performs zero-point correction and / or span correction, and degradation correction sequentially, but degradation correction may be performed first.

[0107] The calculation unit 44 can use predetermined standard curve data for calculating the concentration of the target gas to calculate the concentration corresponding to the correction signal Sc. The calculation unit 44 can display the detected concentration on a display device (not shown). In addition, the calculation unit 44 can display the elapsed time since the last calibration, and can also display the remaining time during the degradation determination period. Furthermore, the calculation unit 44 can also display the lowest concentration of the target gas detected since the last calibration and the time when the lowest concentration was detected. These displayed contents can be used as judgment material for the user to decide on the operation content in step S25 described later. If the processing of step S19 is completed, the process can proceed to step S11 described above.

[0108] In step S21, the determination unit 46 calculates the degradation amount E and determines whether the degradation amount E exceeds a threshold (also referred to as threshold 2, distinct from threshold 1 used in step S15 above). The determination unit 46 may also determine whether the degradation amount E exceeds the threshold for a period of time or longer due to continuous degradation. Here, threshold 1 and threshold 2 may be the same or different. In this embodiment, as an example, threshold 1 used when the elapsed time after calibration exceeds the automatic calibration period may be smaller than threshold 2 used when the elapsed time after calibration does not exceed the automatic calibration period. This allows for a more relaxed calibration condition in step S17, thereby enabling more aggressive calibration. Furthermore, threshold 1 may be set to vary according to the elapsed time after calibration. For example, threshold 1 may be set to be smaller the closer the elapsed time after calibration is to the automatic calibration period. This allows for more aggressive calibration as the elapsed time after calibration increases. Additionally, threshold 1 and threshold 2 may be set to be smaller the higher the concentration of the target gas. For example, threshold 1 and threshold 2 can be divided by a value corresponding to an exponential function of the concentration of the target gas. Therefore, the magnitude of the detection accuracy degradation, which is equivalent to threshold 1 and threshold 2, can be made consistent regardless of the concentration of the gas being detected, enabling more accurate calibration.

[0109] If it is determined in step S21 that the degradation amount E does not exceed the threshold 2 (step S21: "No"), the process can proceed to step S19. If it is determined that the degradation amount E exceeds the threshold 2 (step S21: "Yes"), the process can proceed to step S23.

[0110] In step S23, the notification unit 70 notifies the user. In this embodiment, as an example, the notification unit 70 displays that the degradation level E exceeds a threshold of 2. The notification unit 70 may also display content suggesting ventilation.

[0111] In step S25, the indicator unit 80 outputs an indicator signal corresponding to the user operation. If a calibration instruction is input (step S25: Calibration), the indicator unit 80 supplies a calibration instruction signal to the calibration unit 43 to instruct calibration, and the process can proceed to step S29. If a ventilation instruction is input (step S25: Ventilation), the indicator unit 80 supplies a ventilation instruction signal to the ventilation control unit 60 to instruct ventilation, and the process can proceed to step S31. Preferably, ventilation is instructed before the automatic calibration period has elapsed since calibration. If no operation is performed (step S25: None), the process can proceed to step S19 as described above.

[0112] In step S29, the calibration unit 43 calibrates the first output signal So1. The calibration unit 43 can perform the calibration in the same manner as in step S17. In this embodiment, as an example, the calibration unit 43 uses the measurement results of the first detection unit 21 when the concentration of the target gas is at its lowest after the last calibration to calculate the reference value SV', and determines the deviation Δ between the predetermined reference value SV and the calculated reference value SV'. Alternatively, the calibration unit 43 uses the measurement results of the first detection unit 21, the second detection unit 22, and the temperature measuring unit 30 when the concentration of the target gas is at its lowest after the last calibration to calculate the reference value SV', and determines the deviation Δ between the calculated reference value SV' and the predetermined reference value SV. If the process of step S29 is completed, the process can proceed to step S19 as described above.

[0113] In step S31, the ventilation control unit 60 causes the ventilation device to perform ventilation of the gas of the measurement object 110. In step S33, the first detection unit 21, the second detection unit 22, and the temperature measuring unit 30 perform measurements. The first detection unit 21, the second detection unit 22, and the temperature measuring unit 30 can perform measurements in the same manner as in step S11. Then, in step S35, the calibration unit 43 calibrates the first output signal So1. The calibration unit 43 can perform calibration in response to the acquired ventilation information. The calibration unit 43 uses the first output signal So1 acquired in step S33 to calculate the reference value SV' and determines the deviation Δ between the predetermined reference value SV and the calculated reference value SV'. Alternatively, the calibration unit 43 uses the first output signal So1, the second output signal So2, and the measured temperature T acquired in step S33 to calculate the reference value SV' and determines the deviation Δ between the predetermined reference value SV and the calculated reference value SV'. If the processing of step S35 is completed, the processing can proceed to step S19 as described above.

[0114] Based on the above actions, in response to the determination that the degradation amount E exceeds the threshold, the first output signal So1 is calibrated. Therefore, automatic calibration can be prevented regardless of the small degradation of the accuracy of the calibrated first measured value. In addition, in response to the determination that the degradation amount E exceeds the threshold after an automatic calibration period has elapsed since the last calibration, the first output signal So1 is calibrated. Therefore, frequent calibration can be prevented.

[0115] Furthermore, if the degradation amount E is determined to exceed the threshold 2, the user can instruct the ventilation control unit 60 to perform ventilation of the gas measured in the target 110 or the calibration unit 43 to perform calibration. Thus, the user can select the execution content.

[0116] Furthermore, the above-described operation is described as performing ventilation or calibration based on the user operation performed in step S25 when the degradation amount E is determined to exceed the threshold 2. However, ventilation or calibration may also be performed automatically in response to the determination that the degradation amount E exceeds the threshold 2. In this case, the ventilation information acquisition unit 47 may acquire the ventilation information and supply a calibration instruction signal to the calibration unit 43.

[0117] Furthermore, the explanation assumes that calibration of the first output signal So1 is performed in response to the degradation amount E exceeding threshold 1 after an automatic calibration period has elapsed since the last calibration. However, in addition to this, calibration of the first output signal So1 can also be performed in response to the degradation amount E exceeding a threshold (also referred to as threshold 3, distinct from threshold 1 and threshold 2 used in steps S15 and S21 above) before a reference time (in an example, an automatic calibration period) has elapsed since the last calibration. Threshold 3 can be an example of a second threshold. Threshold 3 can be greater than threshold 1, and threshold 3 can be the same as or different from threshold 2. Thus, calibration can be performed even when the degradation amount E is large before the reference calibration period has elapsed.

[0118] Furthermore, in step S23, the explanation is provided that the degradation level E has exceeded the threshold 2 and ventilation is recommended. However, other information may also be displayed. For example, the notification unit 70 may also display the set time for the degradation determination period, the set time for the automatic calibration period, and the set value of the threshold for the degradation level E. In this case, in step S25, the user can also change the settings for the degradation determination period, the automatic calibration period, and the threshold to match the measurement environment.

[0119] Furthermore, in the above-described operation, the concentration measuring device 100 can also perform a degradation diagnosis of the light-emitting unit 10, and if degradation is detected, the amount of current flowing to the light-emitting unit 10 can be adjusted. These processes can be performed before or after step S11. As a method for degradation diagnosis and current adjustment, for example, the method disclosed in Japanese Patent Application Publication No. 2020-160064 can be used.

[0120] Furthermore, in the above embodiment, the second physical quantity (that is, among the physical quantities related to the main measuring unit 1000, the physical quantity that is independent of the concentration of the target gas and correlated with the reference value SV) was described as the intensity of infrared radiation passing through the light-transmitting region 120 of the reference transmittance. However, in addition to this, or instead, it may be set to at least one other physical quantity. For example, the second physical quantity may be at least one of the following: the intensity of infrared radiation passing through the light-transmitting region 120 of the reference transmittance, the resistance value of the sensor portion in the first measuring unit 21, the resistance value of the sensor portion in the second measuring unit 22, and the supply voltage supplied to the light-emitting unit 10. When any of these physical quantities is used as the second physical quantity, the second measuring unit 22 may output a second output signal So2 (also called the second output signal So2) representing the value of the physical quantity. (1) The determination unit 46 can use the second output signal So2. (1) The function f(T) that varies with the measured temperature T. (1) The obtained function G(So2) (1) T) (1) =So2 (劣化后) (1) / f(T) (1) Let the value be the degradation factor E. The function f(T) (1) It can be the same function as f(T) or a different function. On the other hand, when multiple physical quantities are used as second physical quantities, the second detection unit 22 can output a second output signal So2 (also called the second output signal So2) representing the value of each physical quantity. (1) ...So2 (N) Where N is a natural number greater than or equal to 2. The determination unit 46 can calculate the assumed degradation amount E' for each physical quantity that is a second physical quantity. (n) (where n is a natural number 1 ≤ n ≤ N)), and the assumed degradation amount E' (n) The maximum value in the value is set as the degradation amount E. The assumed degradation amount E' is... (n) It could be based on the second output signal So2. (n) The function f(T) that varies with the measured temperature T. (n) The obtained function G(So2) (n) T)(n) =So2 (劣化后) (n) / f(T) (n) The value of each function G(So2). (n) T) (n) The function f(T) in (n) This can be in the corresponding function G(So2) (n) T) (n) Compared with other functions G(So2) (n) T) (n) Functions that are different from each other can also be found in the corresponding function G(So2). (n) T) (n) With at least a part of the function G(So2) (n) T) (n) The same function between them.

[0121] Furthermore, the third physical quantity (that is, a physical quantity that is independent of the concentration of the gas being measured and correlated with the reference value SV) has been described as the temperature of the object being measured 110 or the concentration measuring device 100, but it can also be other physical quantities. For example, the third physical quantity could be a physical quantity that is different from the second physical quantity, such as the intensity of infrared light emitted from the light-emitting unit 10 and passing through the light-transmitting region 120 with reference transmittance, the resistance value of the sensor portion in the first detection unit 21, the resistance value of the sensor portion in the second detection unit 22, the supply voltage supplied to the light-emitting unit 10, and the humidity of the gas in the object being measured 110. In addition, the second and third physical quantities could also be the same physical quantity measured at different locations.

[0122] Furthermore, while the ventilation control unit 60 and the ventilation device have been described as supplying ventilation information to the ventilation information acquisition unit 47 in response to the completion of ventilation, the ventilation information can also be supplied to the determination unit 46 during ventilation. In this case, the determination unit 46 can determine the completion of ventilation during ventilation based on the change in gas concentration calculated by the calculation unit 44 and the change in the first output signal value So1, and supply a calibration indication signal to the calibration unit 43. As an example, the determination unit 46 can determine that ventilation is complete based on the calculated gas concentration and the change rate of the first output signal value So1 being lower than the reference change rate. The determination unit 46 can supply a signal indicating the completion of ventilation to at least one of the ventilation device, the ventilation control unit 60, the notification unit 70, and the indication unit 80 to terminate the ventilation operation. Thus, the completion of ventilation can be accurately determined, and the ventilation operation can be terminated.

[0123] Next, the concentration measuring device 100A involved in the modified example will be described. Figure 6The concentration measuring device 100A according to the modified example is shown. Furthermore, in the concentration measuring device 100A according to this embodiment, for... Figure 1 The structures of the concentration measuring apparatus 100 shown are substantially the same as those shown in the figures, and the descriptions are omitted.

[0124] The concentration measuring device 100A is a device that detects the concentration of a target gas using a photoacoustic method, and includes a light-emitting unit 10A, a pressure detection unit 21A, and a signal processing unit 40A. Furthermore, the light-emitting unit 10A and the pressure detection unit 21A can be disposed within a sealed chamber 50A containing the target gas 110. Alternatively, the target gas 110 within the chamber 50A can be ventilated via a dust filter 500.

[0125] The light-emitting unit 10A emits or transmits infrared light. The light-emitting unit 10A can be a MEMS device. An infrared filter 11A that allows only infrared light to pass through can be provided on the emission surface of the light-emitting unit 10A. The infrared light emitted from the light-emitting unit 10A passes through the measurement object 110 and is absorbed by the molecules of the target gas included in the measurement object 110 (in this embodiment, carbon dioxide molecules are an example), causing the molecules to vibrate. As a result, the pressure inside the chamber 50A increases.

[0126] The pressure detection unit 21A is a sensor used to measure the pressure inside the chamber 50A. For example, the pressure detection unit 21A could be a piezoelectric microphone.

[0127] The pressure detection unit 21A is an example of a first sensor. It measures the pressure of the object 110 as a first physical quantity, responding to the change in pressure of light emitted from the light-emitting unit 10A as it passes through the object 110. The pressure detection unit 21A can supply a first output signal So1, representing the measured value of the first physical quantity, to the signal processing unit 40A. The pressure detection unit 21A can detect the presence or concentration of the target gas included in the object 110 based on the amount of pressure increase caused by the vibration of the target gas (for example, carbon dioxide). Furthermore, the pressure detection unit 21A and the light-emitting unit 10A can constitute a measuring unit (also called a main measuring unit or main measuring device) 1000A that primarily measures the concentration of the gas included in the target. Other structures, such as an infrared filter 11A, may also be included in the main measuring unit 1000A.

[0128] The pressure detection unit 21A can also be an example of a second sensor. As a second physical quantity related to the main measuring unit 1000A, it is independent of the concentration of the target gas included in the target 110 and correlated with the reference value SV of the first measured value. It measures the pressure of the target 110 when no infrared light from the light-emitting unit 10A passes through. The pressure detection unit 21A can supply a second output signal So2, representing the measured value of the second physical quantity, to the signal processing unit 40A.

[0129] The signal processing unit 40A, except that it obtains the first output signal So1 and the second output signal So2 from the pressure detection unit 21A, can have the same structure as the signal processing unit 40 in the concentration measuring device 100 described above.

[0130] According to the above-described concentration measuring device 100A, even in the photoacoustic concentration measuring device 100A, the same effect as the concentration measuring device 100 of the above-described embodiment can be obtained.

[0131] Furthermore, in the above-described variation, the second physical quantity (that is, among the physical quantities related to the main measuring unit 1000A, the physical quantity that is independent of the concentration of the target gas and correlated with the reference value SV) was described as the pressure of the target 110 when no infrared light from the light-emitting unit 10A passes through. However, it may be set to at least one other physical quantity. For example, the second physical quantity may be at least one of the following: the pressure of the target 110 when no infrared light from the light-emitting unit 10A passes through; the pressure of the light-transmitting space when infrared light emitted from the light-emitting unit 10A passes through the light-transmitting space with the reference transmittance; the resistance value of the sensor portion in the pressure detection unit 21A; the resistance value of the sensor that measures the pressure of the light-transmitting space; and the supply voltage supplied to the light-emitting unit 10A. The light-transmitting space may include a sealed space isolated from the target 110, or it may include a light-transmitting component such as glass.

[0132] Furthermore, similar to the embodiment, the third physical quantity (that is, a physical quantity that is independent of the concentration of the gas being measured and correlated with the reference value SV) has been described as the temperature of the object being measured 110 or the concentration measuring device 100A, but it can also be other physical quantities. For example, the third physical quantity could be the pressure of the object being measured 110 when no infrared light from the light-emitting unit 10A passes through, the pressure of the light-transmitting space when infrared light emitted from the light-emitting unit 10A passes through the light-transmitting space with the reference transmittance, the resistance value of the sensor portion in the pressure detection unit 21A, the resistance value of the sensor that measures the pressure of the light-transmitting space, the supply voltage supplied to the light-emitting unit 10A, the temperature of the object being measured 110 or the concentration measuring device 100A, the humidity of the gas in the object being measured 110, and the atmospheric pressure of the surrounding environment of the concentration measuring device 100A, which are different from the second physical quantity.

[0133] Furthermore, in the above embodiments and variations, the concentration measuring devices 100 and 100A are described as having a ventilation control unit 60, a notification unit 70, and an indicator unit 80, but these may not be included.

[0134] Furthermore, the explanation assumes that the calibration of the first output signal So1 is performed using a sensor that determines the accuracy degradation of the first output signal So1 and the zero-point correction of the first output signal So1, which determines the deviation Δ of the reference value SV of the first output signal So1. However, the calibration of the first output signal So1 can also be performed using a sensor that measures a different physical quantity than the sensor used for accuracy degradation determination and zero-point correction.

[0135] Furthermore, it was explained that the light-emitting units 10 and 10A emit infrared light, but any light in the absorption band of the gas being detected can be emitted, or light of other wavelengths can be emitted.

[0136] Furthermore, while the calculation unit 44 is described as displaying the detection results of the concentration of the target gas, other information may also be displayed. For example, the calculation unit 44 may display a message recommending the replacement or maintenance of the concentration measuring devices 100 and 100A in response to the calibration interval performed in steps S17, S29, and S35 being shorter than the reference interval (for example, 2 days). Additionally, the calculation unit 44 may estimate the timing of the next calibration in steps S17, S29, and S35 based on the calibration intervals previously performed in steps S17, S29, and S35, and display this estimate. Furthermore, the calculation unit 44 may display a message recommending the replacement or maintenance of the concentration measuring devices 100 and 100A in response to the interval from the current calibration to the estimated timing of the next calibration being shorter than the reference interval.

[0137] Furthermore, while the description assumes that the concentration of the target gas is measured using a single concentration measuring device 100, it is also possible to measure the concentration of the target gas using multiple concentration measuring devices 100. In this case, the calculation unit 44 of at least one concentration measuring device 100 can determine the concentration of the target gas based on the degradation amount E of each concentration measuring device 100. As an example, the calculation unit 44 can set the concentration measured by the concentration measuring device 100 with the lowest degradation amount E among the multiple concentration measuring devices 100 as the correct concentration of the target gas, or it can set the concentration measured by any concentration measuring device 100 among the multiple concentration measuring devices 100, determined by the degradation amount E and the cumulative usage time of the concentration measuring devices 100, as the correct concentration of the target gas. In this case, in response to any one of the concentration measuring devices 100 exceeding a threshold value in terms of degradation E, the calibration unit 43 of that concentration measuring device 100 (also referred to as concentration measuring device 100(1)) calibrates against another concentration measuring device 100 (also referred to as concentration measuring device 100(2)) that has been set to the correct concentration. For example, the calibration unit 43 of concentration measuring device 100(1) can set a value corresponding to the deviation Δ of the reference value SV' of concentration measuring device 100(1) relative to the reference value SV' of concentration measuring device 100(2) as the calibration result in concentration measuring device 100(1). Similarly, the concentration of the target gas can be measured using multiple concentration measuring devices 100A.

[0138] Furthermore, while the calculation unit 44 has been described as detecting the concentration of the target gas, it can also detect the presence or absence of the target gas. For example, the calculation unit 44 can also detect the presence or absence of the target gas at a concentration higher than the atmospheric concentration, using the atmospheric concentration as a reference concentration.

[0139] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. Those skilled in the art will understand that various modifications or improvements can be made to the above embodiments. As can be understood from the claims, the manner obtained by applying such modifications or improvements can also be included within the technical scope of the present invention.

[0140] It should be noted that the execution order of actions, processes, steps, and stages in the apparatus, system, program, and method shown in the claims, specification, and drawings can be implemented in any order, unless specifically indicated as "before," "before," etc., and the output of a preceding process is not used in a subsequent process. The flow of actions in the claims, specification, and drawings is described using terms such as "firstly," "next," etc., for convenience, but this does not imply that they must be implemented in this order.

[0141] Explanation of reference numerals in the attached figures

[0142] 10: Light-emitting unit; 11: Infrared filter; 12: Optical path unit; 14: Reflecting unit; 20: Infrared detection unit; 21: First detection unit; 22: Second detection unit; 30: Temperature measuring unit; 40: Signal processing unit; 41: Signal acquisition unit; 42: Temperature information acquisition unit; 43: Calibration unit; 44: Calculation unit; 45: Storage unit; 46: Judgment unit; 47: Ventilation information acquisition unit; 50: Housing; 60: Ventilation control unit; 70: Notification unit; 80: Indicator unit; 100: Concentration measuring device; 110: Measured object; 120: Light-transmitting area; 1000: Measuring unit.

Claims

1. An apparatus, characterized in that, have: The measuring unit has a light-emitting part and a first sensor for measuring a first measured value of a first physical quantity, wherein the first physical quantity is a physical quantity that changes in response to light emitted from the light-emitting part passing through the measuring object; The second sensor measures a second value of a second physical quantity, which is a physical quantity related to the measuring unit that is independent of the concentration of the gas to be detected included in the measuring object and correlated with a reference value of the first value. The third sensor measures a third physical quantity, which is a physical quantity that is independent of the concentration of the gas included in the measurement object and correlated with the reference value. The detection unit detects the presence or concentration of the target gas included in the test object based on the first measured value; The determination unit uses the second measured value and the third measured value to determine whether the degradation of the accuracy of the first measured value exceeds a threshold. as well as The calibration unit calibrates the first measured value in response to the degradation exceeding a first threshold after a reference time has elapsed since the last calibration.

2. The apparatus according to claim 1, characterized in that, The determination unit calculates a value that is a function of the second and third measured values, which is a predetermined value when the accuracy of the first measured value has not deteriorated, as the amount of deterioration in the accuracy of the first measured value.

3. The apparatus according to claim 1, characterized in that, The calibration unit uses multiple of the first measured values ​​to determine the reference value, and performs calibration of the first measured values ​​based on the reference value.

4. The apparatus according to claim 1, characterized in that, The calibration unit calibrates the first measured value in response to the fact that the amount of degradation exceeds a second threshold greater than the first threshold before a reference time has elapsed since the last calibration.

5. The apparatus according to claim 1, characterized in that, The calibration unit performs calibration in response to a calibration instruction received from the user.

6. The apparatus according to claim 1, characterized in that, It also includes a ventilation information acquisition unit, which acquires ventilation information indicating that the measurement object has undergone ventilation. The calibration unit performs calibration in response to receiving ventilation information.

7. The apparatus according to claim 6, characterized in that, It also includes a ventilation control unit that enables the ventilation device of the measured object to perform ventilation. The ventilation information acquisition unit acquires ventilation information from the ventilation device or the ventilation control unit.

8. The apparatus according to any one of claims 1 to 7, characterized in that, The calibration of the first measurement value is to determine the deviation between the predetermined reference value of the first measurement value and the reference value that should be used in the current situation.

9. The apparatus according to claim 8, characterized in that, The calibration unit determines the first measured value, which is the lowest among the multiple first measured values ​​measured by the first sensor after the last calibration, as the reference value that should be used in the current situation.

10. The apparatus according to claim 8, characterized in that, The calibration unit determines the first measured value obtained by the first sensor immediately after the measured object has been ventilated as the reference value that should be used in the current situation.

11. The apparatus according to claim 8, characterized in that, The predetermined reference value for the first measurement is the predetermined first measurement value output from the first sensor when the object being measured does not include the gas of the object being measured at a concentration greater than that in the atmosphere.

12. The apparatus according to claim 1, characterized in that, The reference value of the first measurement is the first measurement value output from the first sensor when the object being measured does not include the gas of the object being measured at a concentration greater than that in the atmosphere.

13. The apparatus according to claim 1, characterized in that, The threshold is set to decrease as the elapsed time after calibration increases.

14. The apparatus according to claim 1, characterized in that, The threshold is set such that the higher the concentration of the gas being detected, the lower the threshold.

15. The apparatus according to claim 2, characterized in that, The second sensor measures the second values ​​of multiple second physical quantities. The determination unit calculates a value for each of the plurality of second physical quantities, which is a function of the second measured value and the third measured value, and which is a predetermined value when the accuracy of the first measured value has not deteriorated, as a hypothetical degradation amount, and sets the maximum value of the hypothetical degradation amount as the degradation amount of the accuracy of the first measured value.

16. The apparatus according to claim 1, characterized in that, The calibration unit uses the measurement results from the second sensor and the third sensor to perform calibration.

17. The apparatus according to claim 1, characterized in that, It also includes a first notification unit that notifies the user in response to the degradation exceeding a threshold.

18. The apparatus according to claim 17, characterized in that, It also has: A ventilation control unit that causes the ventilation device of the measured object to perform ventilation; and The instruction unit, upon notification by the first notification unit, instructs the ventilation control unit to perform ventilation of the measured object or the calibration unit to perform calibration based on user operation.

19. The apparatus according to any one of claims 1 to 7, characterized in that, The measuring unit emits infrared rays from the light-emitting unit and uses the first sensor to measure the intensity of the infrared rays that have passed through the measuring object.

20. The apparatus according to claim 19, characterized in that, The second physical quantity is at least one of the following: the intensity of infrared radiation emitted from the light-emitting part and passing through the light-transmitting area with reference transmittance, the resistance value of the first sensor, the resistance value of the sensor that measures the intensity of infrared radiation passing through the light-transmitting area, and the supply voltage supplied to the light-emitting part.

21. The apparatus according to claim 19, characterized in that, The third physical quantity is the intensity of infrared radiation emitted from the light-emitting part and passing through the light-transmitting area of ​​the reference transmittance, the resistance value of the first sensor, the resistance value of the sensor that measures the intensity of infrared radiation emitted from the light-emitting part and passing through the light-transmitting area of ​​the reference transmittance, the supply voltage supplied to the light-emitting part, the temperature of the object being measured or the device, and, in the case that the object being measured is a gas, the humidity of the object being measured, which is different from the second physical quantity.

22. The apparatus according to claim 19, characterized in that, The second sensor measures the intensity of infrared light emitted from the light-emitting part and passing through the light-transmitting region with a reference transmittance as the second measured value. The detection unit detects the presence or concentration of the target gas included in the test object based on the first measured value and the second measured value.

23. The apparatus according to claim 22, characterized in that, The third physical quantity is the temperature of the second sensor. The third sensor measures the temperature of the second sensor based on the second measured value or the resistance value of the second sensor.

24. The apparatus according to claim 19, characterized in that, The second sensor measures the intensity of infrared light emitted from the light-emitting part and passing through the light-transmitting region with a reference transmittance as the second measured value. The third sensor measures the temperature of the object being measured or the device. The first measured value measured by the first sensor is set as So1, the second measured value measured by the second sensor is set as So2, and the correction coefficient determined by the measured temperature T measured by the third sensor is set as Zero(T). The reference value is calculated using the function So1 / So2×Zero(T) when the measured object does not include the gas of the target object at a concentration greater than that in the atmosphere.

25. The apparatus according to any one of claims 1 to 7, characterized in that, The measuring unit emits infrared rays from the light-emitting unit and uses the first sensor to measure the pressure of the object being measured through which the infrared rays pass.

26. The apparatus according to claim 1, characterized in that, It also has an output section that outputs the detection results of the detection section.

27. An apparatus, characterized in that, have: The measuring unit has a light-emitting part and a first sensor for measuring a first measured value of a first physical quantity, wherein the first physical quantity is a physical quantity that changes in response to light emitted from the light-emitting part passing through the measuring object; The second sensor measures a second value of a second physical quantity, which is a physical quantity related to the measuring unit that is independent of the concentration of the gas to be detected included in the measuring object and correlated with a reference value of the first value. The third sensor measures a third physical quantity, which is a physical quantity that is independent of the concentration of the gas included in the measurement object and correlated with the reference value. The detection unit detects the presence or concentration of the target gas included in the test object based on the first measured value; The determination unit uses the second measured value and the third measured value to determine whether the degradation of the accuracy of the first measured value exceeds a threshold. as well as The calibration unit calibrates the first measured value in response to the degradation exceeding a threshold. The threshold is set such that the longer the time elapsed after calibration, the smaller it becomes.

28. An apparatus, characterized in that, have: The measuring unit has a light-emitting part and a first sensor for measuring a first measured value of a first physical quantity, wherein the first physical quantity is a physical quantity that changes in response to light emitted from the light-emitting part passing through the measuring object; The second sensor measures a second value of a second physical quantity, which is a physical quantity related to the measuring unit that is independent of the concentration of the gas to be detected included in the measuring object and correlated with a reference value of the first value. The third sensor measures a third physical quantity, which is a physical quantity that is independent of the concentration of the gas included in the measurement object and correlated with the reference value. The detection unit detects the presence or concentration of the target gas included in the test object based on the first measured value; The determination unit uses the second measured value and the third measured value to determine whether the degradation of the accuracy of the first measured value exceeds a threshold. as well as The calibration unit calibrates the first measured value in response to the degradation exceeding a threshold. The threshold is set such that the higher the concentration of the gas being detected, the lower the threshold.

29. An apparatus, characterized in that, have: The measuring unit has a light-emitting part and a first sensor for measuring a first measured value of a first physical quantity, wherein the first physical quantity is a physical quantity that changes in response to light emitted from the light-emitting part passing through the measuring object; The second sensor measures a second value of a second physical quantity, which is a physical quantity related to the measuring unit that is independent of the concentration of the gas to be detected included in the measuring object and correlated with a reference value of the first value. The third sensor measures a third physical quantity, which is a physical quantity that is independent of the concentration of the gas included in the measurement object and correlated with the reference value. The detection unit detects the presence or concentration of the target gas included in the test object based on the first measured value; The determination unit uses the second measured value and the third measured value to determine whether the degradation of the accuracy of the first measured value exceeds a threshold. as well as The calibration unit calibrates the first measured value in response to the degradation exceeding a threshold. The calibration unit uses multiple first measured values ​​to determine the reference value and calibrates the first measured value based on the reference value. The calibration unit determines the first measured value among the multiple first measured values ​​where the concentration of the target gas is the lowest as the reference value.

30. A method, characterized in that, Includes the following stages: The first measured value is measured by a measuring unit having a light-emitting part and a first measured value of a first sensor for measuring a first physical quantity, wherein the first physical quantity is a physical quantity that changes in response to light emitted from the light-emitting part passing through the measuring object. The second physical quantity is a physical quantity that is independent of the concentration of the gas to be detected included in the measurement object and correlated with the reference value of the first physical quantity. The third physical quantity is a physical quantity that is independent of the concentration of the gas included in the test object and is correlated with the reference value. The presence or concentration of the gas included in the test object is detected based on the first measured value; The second and third measurements are used to determine whether the degradation of the accuracy of the first measurement exceeds a threshold. as well as The first measurement is calibrated in response to the degradation exceeding a first threshold after a reference time has elapsed since the last calibration.

31. A method, characterized in that, Includes the following stages: The first measured value is measured by a measuring unit having a light-emitting part and a first measured value of a first sensor for measuring a first physical quantity, wherein the first physical quantity is a physical quantity that changes in response to light emitted from the light-emitting part passing through the measuring object. The second physical quantity is a physical quantity that is independent of the concentration of the gas to be detected included in the measurement object and correlated with the reference value of the first physical quantity. The third physical quantity is a physical quantity that is independent of the concentration of the gas included in the test object and is correlated with the reference value. The presence or concentration of the gas included in the test object is detected based on the first measured value; The second and third measurements are used to determine whether the degradation of the accuracy of the first measurement exceeds a threshold. as well as The first measured value is calibrated in response to the degradation exceeding a threshold. The threshold is set such that the longer the time elapsed after calibration, the smaller it becomes.

32. A method, characterized in that, Includes the following stages: The first measured value is measured by a measuring unit having a light-emitting part and a first measured value of a first sensor for measuring a first physical quantity, wherein the first physical quantity is a physical quantity that changes in response to light emitted from the light-emitting part passing through the measuring object. The second physical quantity is a physical quantity that is independent of the concentration of the gas to be detected included in the measurement object and correlated with the reference value of the first physical quantity. The third physical quantity is a physical quantity that is independent of the concentration of the gas included in the test object and is correlated with the reference value. The presence or concentration of the gas included in the test object is detected based on the first measured value; The second and third measurements are used to determine whether the degradation of the accuracy of the first measurement exceeds a threshold. The first measured value is calibrated in response to the degradation exceeding a threshold. The threshold is set such that the higher the concentration of the gas being detected, the lower the threshold.

33. A method, characterized in that, Includes the following stages: The first measured value is measured by a measuring unit having a light-emitting part and a first measured value of a first sensor for measuring a first physical quantity, wherein the first physical quantity is a physical quantity that changes in response to light emitted from the light-emitting part passing through the measuring object. The second physical quantity is a physical quantity that is independent of the concentration of the gas to be detected included in the measurement object and correlated with the reference value of the first physical quantity. The third physical quantity is a physical quantity that is independent of the concentration of the gas included in the test object and is correlated with the reference value. The presence or concentration of the gas included in the test object is detected based on the first measured value; The second and third measurements are used to determine whether the degradation of the accuracy of the first measurement exceeds a threshold. as well as The first measured value is calibrated in response to the degradation exceeding a threshold. The reference value is determined using a plurality of the first measured values, and the first measured values ​​are calibrated based on the reference value, wherein the first measured value in which the concentration of the target gas is lowest among the plurality of the first measured values ​​is determined as the reference value.

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