Gas detection device, humidity correction method and control device

Abstract

To flexibly cope with change over time of a sensor and furthermore to improve the accuracy of correction of a measured value.SOLUTION: The gas detection device pertaining to one embodiment of the present invention comprises a detection element, a humidity sensor and a control device. The output of the detection element changes due to the absorption, by the detection element, of an odorous content included in a detection object gas. The humidity sensor detects the humidity of the detection object gas. The control device includes an acquisition unit, a storage unit, a measurement unit and an update unit. The acquisition unit acquires the measured value of the detection element and the measured value of the humidity sensor. The storage unit stores a correction coefficient. The measurement unit measures the odorous content on the basis of the output of the detection element having been corrected for humidity using the correction coefficient. The update unit updates a current correction coefficient to a coefficient for update calculated on the basis of first history data that is the history of measured value of each of the detection element and the humidity sensor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas detection device, a humidity correction method, and a control device. [Background technology]

[0002] In order to distinguish between odors, which are aggregates of multiple odor components, there has been active development in recent years of odor sensors that pattern odors by arraying adsorption films with multiple different chemical properties to form multi-array sensors.The use of such odor sensors makes it possible to distinguish between pleasant and unpleasant odors, and applications of odor sensors have begun to be considered in fields where human sensory evaluation has traditionally been relied upon. These applications include indoor and automotive environmental management, factory process management, and environmental monitoring to detect early-stage fires and malodors that affect the human body.

[0003] For example, odor sensors use a detection element with an adsorption film on a quartz crystal oscillator. The resonant frequency of the quartz crystal oscillator decreases in proportion to the weight of odor components adsorbed on the adsorption film, so the amount of odor components can be detected based on the change in resonant frequency. Therefore, a decrease in sensitivity level due to deterioration over time of the adsorption film that adsorbs odor components affects the reliability of the odor sensor. The main cause of deterioration of the adsorption film over time is that the adsorbed odor components cannot be released from the adsorption film during sensor use, and remain on the adsorption film, causing the odor components to accumulate.

[0004] For example, Patent Document 1 discloses a method for improving the accuracy of correcting sensor values due to deterioration over time by using a correction means with two-stage parameters according to the degree of deterioration. Also, Patent Document 2 discloses a method for performing correction by adding a new sensor that serves as a reference for correcting the sensor response amount. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6730110 [Patent Document 2] Patent No. 6428779 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method of Patent Document 1 has only two-stage parameters, making it difficult to flexibly respond to the degree of deterioration, and differences are likely to occur in long-term environments, parameter changes, etc. Furthermore, if an individual sensor shows changes over time that are specific to that sensor, the correction will not function properly.

[0007] On the other hand, the method of Patent Document 2 requires the preparation of a reference for correcting the gas sensor, which incurs additional costs. In addition, the reference used must have the same characteristics as the sensor used for measurement, including the time-dependent change characteristics.

[0008] In view of the above circumstances, an object of the present invention is to provide a gas detection device, a humidity correction method, and a control device that can flexibly respond to changes in the sensor over time and improve the accuracy of correction of measurement values. [Means for solving the problem]

[0009] A gas detection device according to one aspect of the present invention includes a detection element, a humidity sensor, and a control device. The detection element generates a change in output upon adsorption of odor components contained in the detection target gas. The humidity sensor detects the humidity of the detection target gas. The control device includes an acquisition unit, a storage unit, a measurement unit, and an update unit. The acquisition unit acquires a measurement value of the detection element and a measurement value of the humidity sensor. The storage unit stores a correction coefficient. The measurement unit measures the odor component based on the output of the detection element that has been humidity-corrected using the correction coefficient. The update unit updates the correction coefficient to an update correction coefficient calculated based on first history data, which is a history of measurement values of the detection element and the humidity sensor.

[0010] The measurement value of the sensing element may be the minimum or maximum value of the resonant frequency obtained within a measurement period, or the resonant frequency at the end of the measurement period.

[0011] The measurement values of the detection element and the humidity sensor may be time-linked measurement values.

[0012] The control device may further include a determination unit that determines whether or not the correction coefficient should be updated to the update correction coefficient based on a determination criterion set based on second history data, which is a history of the correction coefficient.

[0013] The determination unit may be configured to set the determination criterion based on an average value of the correction coefficients in the second history data, and to update the correction coefficients to the update correction coefficients only if the update correction coefficients satisfy the determination criterion.

[0014] The detection element may include a plurality of detection elements.

[0015] The detection element may be a vibration device having an adsorption film that adsorbs the odor component, and in which the adsorption of the odor component causes a change in resonant frequency.

[0016] A humidity correction method according to one aspect of the present invention is a humidity correction method for a gas detection device, comprising: In a first period, a measurement value of a detection element that produces an output change due to adsorption of odor components contained in the detection target gas and a measurement value of a humidity sensor that detects the humidity of the detection target gas are obtained; measuring the odor component based on the output of the detection element that has been humidity-corrected using a correction coefficient; An update correction coefficient is calculated based on history data that is a history of measurement values of the detection element and the humidity sensor.

[0017] A control device according to one aspect of the present invention is a control device for a gas detection device, an acquisition unit that acquires, in a first period, a measurement value of a detection element that produces an output change due to adsorption of odor components contained in the detection target gas and a measurement value of a humidity sensor that detects the humidity of the detection target gas; a storage unit that stores the correction coefficient; a measurement unit that measures the odor components based on the output of the detection element that has been humidity-corrected using the correction coefficient; and an updating unit that updates the correction coefficient to a correction coefficient calculated based on first history data that is a history of measurement values of the detection element and the humidity sensor; It is equipped with: [Effects of the Invention]

[0018] According to the present invention, it is possible to improve the accuracy of correction of measurement values while flexibly dealing with changes over time in the sensor. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram of a gas detection device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing an example of the configuration of a detection element. [Figure 3] FIG. 10 is an explanatory diagram of a method for calculating a correction coefficient for humidity correction. [Figure 4] FIG. 10 is an explanatory diagram of a method for calculating a correction coefficient for humidity correction. [Figure 5] FIG. 4 is a schematic diagram showing frequency changes of a detection element. [Figure 6] 4 is a flowchart showing an example of a processing procedure of a control device in the gas detection device. [Figure 7] FIG. 10 is a diagram illustrating an example of history data of correction coefficients. [Figure 8] 10A and 10B are diagrams illustrating a method for determining whether or not an update correction coefficient is adopted. [Figure 9] 10A and 10B are diagrams illustrating a method for determining whether or not an update correction coefficient is adopted. [Figure 10]10A and 10B are diagrams illustrating a method for determining whether or not an update correction coefficient is adopted. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] [Gas detection equipment] FIG. 1 is a schematic diagram of a gas detection device 100 according to this embodiment. The gas detection device 1 is configured as an alarm device that is installed, for example, inside a distribution board and detects a specific odor component in gas that is generated when an abnormality such as a cable fire occurs, and issues an alarm or the like.

[0022] As shown in FIG. 1, gas detection device 100 includes gas sensor 2, control device 4, and alarm device 5.

[0023] The gas sensor 2 has a housing 20 , a first intake port 21 , a second intake port 22 , and a sensor chamber 60 .

[0024] The first intake port 21 communicates with the sensor chamber 60 via a first flow path 31. The second intake port 22 communicates with the sensor chamber 60 via a second flow path 32. First air intake 21 and second air intake 22 are inlets for taking in outside air G into sensor chamber 60. Outside air G is a gas to be detected by gas detection device 100, and in this embodiment, is the air inside the switchboard. In the description of this embodiment, the gas includes moisture and odor components.

[0025] In the first flow path 31, a first pump 31P is arranged to take in outside air G from the first intake port 21 into the sensor chamber 60. A second pump 32P is disposed in the second flow path 32, which takes in outside air G from the second air intake port 22 into the sensor chamber 60. A filter 32F is disposed in the second flow path 32, which adsorbs odor components and moisture contained in the outside air G taken in from the second air intake port 22 to generate clean air.

[0026] In the embodiments of the present invention, clean air refers to gas from which odorous components and moisture contained in the outside air G have been removed using a filter, but it is also possible to provide a separate device that generates clean gas that does not contain odorous components or moisture, and to send the clean gas from that device to the sensor chamber 60 as clean air.

[0027] The first pump 31P and the second pump 32P are typically configured as diaphragm pumps, but other gas senders capable of sending or sucking gas at a constant flow rate, such as fans or blowers, can also be used. The first pump 31P and the second pump 32P are driven individually by the control device 4, and by driving either one of them, either the first flow path 31 or the second flow path 32 is selected as the intake flow path for outside air.

[0028] The filter 32F can be made of materials with high humidity removal properties such as silica gel or molecular sieves to remove humidity and hydrophilic odor components, materials with high odor adsorption properties such as activated carbon or zeolite to remove odor components, or a combination of these.

[0029] The sensor chamber 60 accommodates a plurality of QCM (Quartz Crystal Microbalance) sensors 10 as detection elements and a humidity sensor 70 .

[0030] Sensor chamber 60 forms a chamber into which measurement is performed by taking in outside air G. Sensor chamber 60 is connected to first flow path 31 and second flow path 32, and outside air G is introduced into sensor chamber 60 via first air intake port 21 or second air intake port 22. Although not shown, sensor chamber 60 is connected to an exhaust passage that exhausts the introduced gas.

[0031] The QCM sensor 10 is a detection element whose resonant frequency changes when it adsorbs odor components contained in the outside air G. Each QCM sensor 10 constitutes a detection channel (ch). The number of QCM sensors 10 corresponds to the number of channels, and is not particularly limited. In this embodiment, an example is given in which a 16-channel QCM sensor 10 is provided, but at least one channel is sufficient.

[0032] An oscillation circuit 50 is connected to each QCM sensor 10. Each oscillation circuit 50 is driven by the control device 4. Each oscillation circuit 50 vibrates each QCM sensor 10 at a predetermined resonance frequency. The oscillation circuit 50 is connected to a counter circuit (not shown) that counts the oscillation frequency of the QCM sensor 10. The counter circuit counts changes in the resonance frequency of each QCM sensor 10 and outputs the count value to the control device 4. In this embodiment, the measurement value of each QCM sensor 10 is the count value output by the counter circuit.

[0033] The humidity sensor 70 measures the relative humidity of the outside air G. The measurement value output from the humidity sensor 70 is output to the control device 4. The control device 4 corrects the measurement value of each QCM sensor 10 based on the humidity measured by the humidity sensor 70, as will be described later. The humidity sensor 70 can be a conventional type such as a capacitance type that detects humidity based on the output value of capacitance or a semiconductor type that detects humidity based on the output value of resistance, but is not limited to these. A hydrophilic adsorption film may be formed on the QCM sensor, and the humidity of each QCM sensor 10 may be corrected based on the change in resonant frequency when odor components are adsorbed.

[0034] The sensor chamber 60 may further include a temperature sensor that detects the temperature of the outside air G. In this case, based on the temperature detected by the temperature sensor, the temperature-induced change in the resonant frequency detected by each QCM sensor 10 can be canceled out, and the resonant frequency change of each QCM sensor 10 that is not affected by temperature can be detected.

[0035] Each QCM sensor 10, each oscillation circuit 50, and humidity sensor 70 may be mounted on a common wiring board, or may be mounted on separate wiring boards.

[0036] Each QCM sensor 10 has a configuration comprising a quartz crystal oscillator as an oscillator and an adsorption film disposed on the quartz crystal oscillator that adsorbs odor components contained in the outside air G. The basic structure is the same except for the type of adsorption film.

[0037] 2, the QCM sensor 10 includes a quartz crystal oscillator 13, an electrode 11, an adsorption film 12, lead lands 16A and 16B, leads 14A and 14B, pin terminals 19A and 19B, and a holder 18. The quartz crystal oscillator 13 is, for example, an AT-cut quartz crystal plate. The resonant frequency of the quartz crystal oscillator 13 is not particularly limited and is, for example, 32 MHz.

[0038] The resonant frequency of the quartz crystal oscillator 13 of the QCM sensor 10 decreases in proportion to the increase in the weight of the gas adsorbed on the adsorption film 12, so the change in resonant frequency is calculated for each QCM sensor 10 to detect the presence or absence of odor components in the outside air G or to measure the amount or concentration of one or more odor components. Furthermore, based on the calculation results, the type or intensity of the odor contained in the outside air G can be determined.

[0039] In this embodiment, a quartz crystal oscillator is used as the oscillator of the detection element, but this is not limiting. For example, other oscillatory devices such as a ceramic oscillator, a surface acoustic wave element, a piezoelectric thin film resonator, a cantilever, or a diaphragm can also be used.

[0040] Electrodes 11 are formed on both sides of the quartz crystal unit 13, and an adsorption film 12 is formed on the electrodes 11 formed on one side of the quartz crystal unit 13. Lead lands 16A are formed integrally with the electrodes 11 formed on one side, and lead lands 16B are formed integrally with the electrodes 11 formed on the other side.

[0041] The adsorption films 12 of the QCM sensors 10 are made of different materials. The materials constituting the adsorption films 12 are selected arbitrarily depending on the type of odor component to be detected. The adsorption films 12 are configured to be able to adsorb one or more types of odor components.

[0042] Leads 14A and 14B are made of a metal spring material. One end of lead 14A is electrically connected to electrode 11 formed on one surface via lead land 16A, and the other end is connected to pin terminal 19A. One end of lead 14B is electrically connected to electrode 11 formed on the other surface via lead land 16B, and the other end is connected to pin terminal 19B. Pin terminals 19A and 19B are supported by a holder 18 provided on the wiring board, and holder 18 supports crystal unit 13 so that it can vibrate freely.

[0043] Based on the measurement values of each QCM sensor 10, the control device 4 detects the presence or absence of odor components in the outside air G, which is the gas to be detected, or measures the amount or concentration of one or more odor components. At this time, the adsorption film 12 of each QCM sensor 10 adsorbs not only odor components but also moisture contained in the detection target gas. Therefore, the measurement value of each QCM sensor 10 also contains information about frequency changes due to moisture adsorption. Therefore, the control device 4 performs a correction (hereinafter also referred to as humidity correction) to remove the humidity component from the measurement value of each QCM sensor 10 in order to accurately measure only the frequency change due to the adsorption of odor components. Furthermore, the measurement device 4 is configured to be able to periodically update the correction coefficient for humidity correction in order to suppress a decrease in measurement accuracy due to deterioration over time of the adsorption film 12 of each QCM sensor 10.

[0044] [Control device] The control device 4 will be described in detail below. The control device 4 is configured as an information processing device having a CPU and memory. The control device 4 controls the driving of the first pump 31P, the second pump 32P, the oscillation circuit 50, the humidity sensor 70, etc., and acquires information on the amount of change in the resonant frequency of each QCM sensor 10 and the humidity of the outside air G from the oscillation circuit 50 and the humidity sensor 70.

[0045] 1, the control device 4 has, as functional blocks of a CPU, an acquisition unit 41, a measurement unit 42, a calculation unit 43, an update unit 44, and a determination unit 45. The control device 4 further includes a storage unit 46 configured from a semiconductor memory or the like.

[0046] (Storage part) The storage unit 46 stores a program for causing the acquisition unit 41, the measurement unit 42, the calculation unit 43, the determination unit 45, and the update unit 44 to operate as functional blocks of a CPU.

[0047] The memory unit 46 stores the resonant frequency of each QCM sensor 10 acquired by the acquisition unit 41 when the adsorption film 12 and the sensor chamber 60 are cleaned with clean air. Cleaning the adsorption film 12 refers to desorbing odor components from the adsorption film 12 with clean air. The clean air can be obtained by taking in outside air G through the second air intake 22 and introducing it into the sensor chamber 60 through the filter 32F of the second flow path 32. The resonant frequency of each QCM sensor 10 when the adsorption film 12 and the sensor chamber 60 are cleaned with clean air is also referred to as the zero point of the frequency of each QCM sensor 10 hereinafter. The zero point is acquired in advance for each QCM sensor 10 and stored in the memory unit 46.

[0048] The memory unit 46 stores the measurement values of each QCM sensor 10 acquired by the acquisition unit 41. The measurement values of each QCM sensor 10 correspond to the amount of change in the resonant frequency of each QCM sensor 10 when outside air G is introduced into the sensor chamber 60 from the first intake port 21 through the first flow path 31.

[0049] The storage unit 46 stores the measurement value of the humidity sensor 70 acquired by the acquisition unit 41. The memory unit 46 temporally links the measurement values of each QCM sensor 10 with the measurement values of the humidity sensor 70, and stores historical data (hereinafter also referred to as first historical data) which is the history of the measurement values of each QCM sensor 10 and humidity sensor 70.

[0050] The storage unit 46 associates the correction coefficients calculated by the calculation unit 43 with information on the date and time of the calculation, and stores history data (hereinafter also referred to as second history data) which is a history of these. The storage unit 46 also stores in advance reference detection patterns obtained when various odors are detected in the sensor chamber 60 for each different type of odor.

[0051] The storage unit 46 stores an initial value of a correction coefficient specific to each QCM sensor 10. The initial value of the correction coefficient is a correction coefficient that is referenced when an unused gas detection device 100 is used for the first time. This correction coefficient is calculated based on the humidity-dependent characteristics of each QCM sensor 10 that have been measured in advance in an odor-free environment.

[0052] (Method for determining the initial value of the correction coefficient) Here, a method for calculating the initial values of the correction coefficients will be described. When calculating the initial values of the correction coefficients, reference is made to the time change in the output of each QCM sensor 10 and humidity sensor 70 measured using air as the gas. An example of the measurement results is shown in FIG. In FIG. 3, the horizontal axis represents measurement time, the vertical axis on the left represents the resonance frequency of the QCM sensor 10, and the vertical axis on the right represents the relative humidity of the air, which is the gas to be detected by the humidity sensor 70. By measuring the output pattern of each QCM sensor 10 using a gas that does not contain odor components, the relationship between the output of each QCM sensor 10 and the environmental factor (humidity in this example) can be found.

[0053] The resonant frequency of each QCM sensor 10 gradually decreases from zero depending on the amount of adsorbed moisture in the gas, and vibrates at a constant resonant frequency after a predetermined time has elapsed since the start of measurement. In the example shown, the QCM sensor 10 for detection channel number 8, "ch8," exhibits the largest frequency change. This indicates that the adsorption film 12 of the QCM sensor 10 for "ch8" is more likely to adsorb moisture than the adsorption films 12 of the other channels, and has a higher affinity for moisture.

[0054] On the other hand, with respect to the humidity sensor 70, as the humidity of the measurement environment increases with the start of the introduction of air, the detected humidity gradually fluctuates in the direction of increasing from the start of measurement.

[0055] 3, "dch" is the amount of frequency variation from the zero point of each QCM sensor 10, and "dch min" is the minimum value of the resonant frequency of each QCM sensor 10. "ch8 min" means the minimum value of the resonant frequency of the QCM sensor 10 of "ch8." Furthermore, "dhumidity" (hereinafter abbreviated as dhmd) is the measurement value of the humidity sensor 70, and "dhmd min" is the measurement value of the humidity sensor 70 when the resonant frequency of the QCM sensor 10 of "ch8", which has the largest frequency fluctuation among all QCM sensors 10, shows the minimum value.

[0056] The data shown in Figure 3 shows how, when air is exposed to the QCM sensor 10, odor components contained in the air are adsorbed by the QCM sensor 10, causing its resonant frequency to decrease. As described above, the measurement value of the humidity sensor 70 is the measurement value of the humidity sensor when the resonant frequency of the QCM sensor 10 for the detection channel with the largest frequency fluctuation is at its minimum. In the case shown in Figure 3, the measurement value of the humidity sensor when the resonant frequency of the QCM sensor 10 for "ch8" with the largest frequency fluctuation is at its minimum is used. On the other hand, the moisture adsorbed by the QCM sensor 10 may be desorbed by the atmosphere. In this case, the resonant frequency of the QCM sensor 10 increases, and therefore the measurement value of the humidity sensor 70 is adopted as the measurement value of the humidity sensor when the resonant frequency of the QCM sensor 10 in the detection channel with the largest frequency fluctuation reaches its maximum value. Thus, when air is applied to the QCM sensor 10, the resonant frequency of the QCM sensor 10 may either decrease or increase, so the measurement value of the QCM sensor 10 used as the reference when determining the measurement value of the humidity sensor 70 may be determined by comparing the absolute values of the minimum and maximum resonant frequencies of the QCM sensor 10 in the detection channel with the greatest frequency fluctuation, and using the measurement value that shows the largest of these. As a further alternative, the measurement value of the QCM sensor 10 in the detection channel with the greatest frequency fluctuation at the end of the measurement period may be used.

[0057] Next, the difference between the humidity at the start of measurement and the measurement value of the humidity sensor 70 at any measurement time was taken as the humidity difference, and the frequency fluctuation of each QCM sensor 10 was plotted against the humidity difference, as shown in Figure 4. As shown in Figure 4, there is a very clear linear relationship between the frequency fluctuation of each QCM sensor 10 and the humidity difference, as shown in the following equation. (dch)=a1×(dhmd)+b1 …(1)

[0058] In the above equation, the constants a1 and b1 are unique values for each QCM sensor 10, and typically, the constant a1 corresponds to the initial value of the correction coefficient. Note that in addition to the constant a1, the constant b1 and coefficients of equations other than the linear equation may also be used for humidity correction. The above correction formula is obtained by regression analysis from the frequency fluctuation (dch) of the QCM sensor 10 obtained by multiple measurements and the measurement value (dhmd) of the humidity sensor 70.

[0059] (Acquisition Department) The acquisition unit 41 acquires the measurement values of each QCM sensor 10 and the measurement value of the humidity sensor 70 . More specifically, the acquisition unit 41 acquires the zero point of the resonant frequency of each QCM sensor 10 when the adsorption film 12 and the sensor chamber 60 are cleaned by introducing clean air. Hereinafter, this process is also referred to as a refresh process. The refresh process is performed before or after each QCM sensor 10 measures the ambient air G. The refresh process lasts, for example, one minute.

[0060] The acquisition unit 41 acquires the measurement values of each QCM sensor 10 when outside air G is introduced into the sensor chamber 60 in a first period. Hereinafter, this process is also referred to as a gas measurement process. The first period is not particularly limited and is, for example, one hour. In this embodiment, the maximum change in the resonant frequency of each QCM sensor 10 during each gas measurement process is acquired as the measurement value of each QCM sensor 10.

[0061] The acquisition unit 41 acquires, in a first cycle, the measurement value of the humidity sensor 70. In this embodiment, as described with reference to Fig. 3, during each gas measurement process, the output of the humidity sensor 70 when the resonant frequency of the QCM sensor 10 with the largest frequency change among the QCM sensors 10 is at its minimum value is acquired as the measurement value of the humidity sensor 70. In this case, as described above, the larger of the absolute value of the minimum or maximum value of the resonant frequency of the QCM sensor 10 of the detection channel with the largest frequency change may be used, or the measurement value at the end of the measurement period may be used.

[0062] FIG. 5 is a schematic diagram showing an example of the change in output of the QCM sensor 10 during the refresh process and the gas measurement process. As shown in the figure, the control device 4 executes a process of alternately performing a refresh process and a gas measurement process.

[0063] During the refresh process period before the gas measurement process, the adsorption film 12 of each QCM sensor 10 and the sensor chamber 60 are thoroughly cleaned with clean air, and environmental factors such as the vibration frequency of each QCM sensor 10 and the humidity of the sensor chamber 60 are set to zero. The refresh process period at this time is, for example, 20 minutes. The gas measurement process is performed after the refresh process. In the illustrated example, the changes in the resonant frequencies of three QCM sensors 10, ch1, ch2, and ch3, out of the 16-channel QCM sensor 10, are shown. The minimum frequency value that indicates the maximum change from the zero point in the resonant frequency of each channel is included in the measurement value of each QCM sensor 10. The gas measurement process is performed for a predetermined time (e.g., one minute) in a first cycle, for example, every hour.

[0064] To give a specific example, the first cycle may be a cycle in which the refresh process before the gas measurement process is performed for 20 minutes, followed by the gas measurement process for 1 minute, followed by a 1-minute refresh process, followed by a 38-minute wait time. The 38-minute wait time is a period in which the pump is not driven and the refresh process and gas measurement process are not performed. After that, the next cycle begins, and the refresh process before the gas measurement process begins. The first cycle is not limited to 1 hour. The gas measurement process, refresh process, and wait time can also be set arbitrarily. The first cycle may also be a cycle in which the gas measurement process and the refresh process are performed in order without a wait time.

[0065] After the gas measurement process is completed, the refresh process is performed again. This causes the odor components and moisture adsorbed on the adsorption film 12 of each QCM sensor 10 to desorb, and the resonance frequency of each QCM sensor 10 returns to the zero point. The refresh process period is not particularly limited, and may be continued after the gas measurement process is completed until just before the next gas measurement process.

[0066] In a QCM sensor 10 that has not deteriorated over time, the zero point of the frequency of each QCM sensor 10 is 32 MHz, which is the natural frequency of the quartz oscillator 13. On the other hand, if desorption of odor components and moisture is insufficient due to deterioration of the adsorption film 12 over time, the zero point of the QCM sensor 10 will be a frequency lower than the natural frequency of the quartz oscillator 13.

[0067] (Measurement part) During the gas measurement process, the measurement unit 42 uses a correction coefficient to humidity-correct the measurement values of each QCM sensor 10 and measure the type and amount or concentration of odor components in the target gas, outside air G. The odor components are those that are adsorbed by at least one adsorption film 12 of each QCM sensor 10 and can be identified by the reference detection pattern stored in the memory unit 46.

[0068] As described above, there is a linear relationship between humidity and the frequency fluctuation of QCM sensor 10. If the frequency fluctuation due to excess humidity included in the measurement value of QCM sensor 10 is defined as "Δchhumidity," and the difference between the measurement value of humidity sensor 70 at the start of measurement and the measurement value of humidity sensor 70 at the time the measurement value of QCM sensor 10 is acquired is defined as "ΔHumidity," the relationship between the two can be expressed as follows: Δchhumidity=a2×ΔHumidity+b2 …(2) The constants a2 and b2 have unique values for each QCM sensor 10, and typically, the constant a2 is used as the correction coefficient. In addition to the constant a2, the constant b2 and coefficients of equations other than the linear equation may also be used for humidity correction.

[0069] In the humidity correction of the measurement values of each QCM sensor 10 performed by the measurement unit 42, it is assumed that the measurement values of each QCM sensor 10 include an extra fluctuation due to humidity. Therefore, if the measurement value of the QCM sensor 10 before humidity correction is Δchraw and the measurement value of the QCM sensor 10 after humidity correction is Δchsample, the measurement unit 42 performs humidity correction of the measurement values of the QCM sensor 10 by executing the calculation process shown in the following equation. Δchsample=Δchraw-Δchhumidity …(3)

[0070] The measurement unit 42 compares the combination pattern of the humidity-corrected measurement values of each QCM sensor 10 with the reference detection pattern pre-stored in the memory unit 46, and evaluates the type and intensity of odor using pattern recognition based on machine learning, etc. When the measuring unit 42 detects an odor component that indicates an abnormality, or when it evaluates that the concentration of the odor component is equal to or higher than a predetermined concentration, it generates and outputs an abnormality signal to the alarm device 5.

[0071] The alarm device 5 has alarm devices such as a buzzer and a lamp. The alarm device 5 receives an abnormality signal generated when an odor component is detected from the control device 4, and sounds the buzzer or lights or blinks the lamp. This makes it possible to notify the outside world of an abnormality in the distribution board.

[0072] (Calculation section) The correction coefficient used for humidity correction of the QCM sensor 10 changes over time. That is, because the gas measurement process is repeated at a fixed cycle (every hour in this embodiment), the cleanliness level of the adsorption film 12 in the subsequent refresh process gradually decreases. As a result, as the number of days passes from the start of measurement, the fixed correction coefficient becomes unable to perform appropriate humidity correction, which may result in an erroneous evaluation of odor components. Specifically, there is a possibility that an abnormality may be determined when no abnormality has occurred, or that no abnormality has occurred when an abnormality has occurred.

[0073] To prevent such a problem, the control device 4 of this embodiment is configured to be able to update the correction coefficient. The calculation unit 43 is configured to execute a process of periodically calculating an updated correction coefficient.

[0074] Calculation unit 43 calculates a correction coefficient based on first history data, which is a history of measurement values of each QCM sensor 10 and humidity sensor 70 stored in storage unit 46. The calculation method of the correction coefficient is similar to the calculation method of the initial value of the correction coefficient described with reference to Figures 3 and 4, but when calculating the updated correction coefficient, the measurement values of each QCM sensor 10 acquired during the gas measurement process are used as the measurement values of each QCM sensor 10. This eliminates the need to prepare a new atmospherically adjusted measurement environment, and allows new correction coefficients to be calculated while gas detection device 100 continues its regular abnormality monitoring operation.

[0075] The calculation unit 43 executes a process of calculating an update correction coefficient (hereinafter also referred to as an update correction coefficient) in a second period that is longer than the first period (one hour in this example), which is the operating period of the gas measurement process. The second period is not particularly limited, and is, for example, one day (24 hours).

[0076] When calculating the correction coefficient, the calculation unit 43 calculates the correction formula as shown in the above formula (1) using the most recent historical data from the historical data (first historical data) of the measurement values of each QCM sensor 10 for the past 24 hours and the measurement values of the humidity sensor 70 linked to them. The number of recent historical data is not particularly limited, and in this embodiment, historical data for the past 24 hours, i.e., the measurement values of each QCM sensor 10 and humidity sensor 70 acquired during the most recent 24 gas measurement processes, are used.

[0077] (Update section) The update unit 44 is configured to be able to execute a process of updating, at a second cycle (every 24 hours), the correction coefficients used in the humidity correction process in the measurement unit 42 to the update correction coefficients calculated by the calculation unit 43. This makes it possible to suppress a decrease in the accuracy of the measurement values of each QCM sensor due to deterioration over time of the adsorption film 12, and ensure proper anomaly detection operation over a long period of time.

[0078] In this embodiment, as will be described later, the current correction coefficients are updated to the update correction coefficients only when the determination unit 46 permits the update.

[0079] (Judgment Department) Ideally, the data referenced when calculating the updated correction coefficients would be measurements of the QCM sensors 10 in which there is no odor and frequency fluctuations are caused purely by humidity fluctuations. In this embodiment, the updated correction coefficients are calculated based on measurements of each QCM sensor 10 acquired during the gas measurement process. However, these measurements are not necessarily data measured in an odor-free environment. For example, there are times when odor components are detected but not enough to warrant evaluation of an abnormal state. Using correction coefficients calculated based on data measured under such conditions could have a significant impact on subsequent anomaly detection processing.

[0080] Therefore, in this embodiment, a newly calculated update correction coefficient is not adopted as is, but a determination unit 45 is provided to determine whether the calculated update correction coefficient is appropriate based on the history of past correction coefficients.

[0081] The determination unit 45 is configured to determine whether or not the current correction coefficient should be updated to the update correction coefficient calculated by the calculation unit 42, based on a determination criterion set based on second history data, which is the past history of the correction coefficients stored in the memory unit 46. The judgment criteria are to calculate a predicted value of the next correction coefficient from past correction coefficients and its allowable range. The predicted value may be, for example, the average value of past correction coefficients, and the allowable range may be, for example, the standard deviation of the correction coefficient history multiplied by a certain coefficient.

[0082] [Gas detection device operation] Details of control device 4 will be described below along with a typical operation of gas detection device 100. Fig. 6 is a flowchart showing an example of a processing procedure of control device 4.

[0083] (Gas measurement processing) Control device 4 periodically executes gas measurement processing in a first cycle after starting operation of gas detection device 100. In this embodiment, the gas measurement processing is executed in the first cycle, that is, every hour (steps 101 to 104).

[0084] In the gas measurement process, as described above, the first pump 31P is driven to drive the outside air G (air inside the switchboard) taken in through the first intake port 21 and introduced into the sensor chamber 60 through the first flow path 31. The control device 4 acquires the measurement values of each QCM sensor 10 and humidity sensor 70 and stores them in the memory unit 46 (step 102).

[0085] Next, the control device 4 performs humidity correction on the measurement values of each QCM sensor 10 using the relative humidity of the outside air G acquired by the humidity sensor 70 and the correction coefficient stored in the memory unit 46 (step 103). If the correction coefficient has not yet been updated, the initial value of the correction coefficient measured in advance as described with reference to FIGS. 3 and 4 is used.

[0086] The control device 4 compares the detection pattern, which is a combination of the humidity-corrected measurement values of each QCM sensor 10, with a reference detection pattern pre-stored in the memory unit 46, and evaluates the type or intensity of the odor component using pattern recognition based on machine learning or the like (step 104). If there is no odor component indicating an abnormality or the concentration is less than a predetermined value, it is determined that there is no odor and that the condition is normal ("Y" in step 105). On the other hand, if the concentration of the odor component indicating an abnormality is evaluated to be equal to or greater than the predetermined value, it is determined to be abnormal ("N" in step 105), and an abnormality signal is generated and output to alarm device 5 (step 106).

[0087] After the gas measurement process described above is completed, the control device 4 executes a refresh process. In the refresh process, the first pump 31P is stopped, and the second pump 32P is driven to introduce outside air G taken in through the second intake port 22 into the sensor chamber 60 through the second flow path 32 and the filter 32F. This cleans the adsorption film 12 of each QCM sensor 10 and the inside of the sensor chamber 60, and returns the resonance frequency of each QCM sensor 10 to the zero point (see FIG. 5).

[0088] After the refresh process is completed, the control device 4 performs an operation (hereinafter also referred to as steady-state operation) in which the above-mentioned gas measurement process and refresh process are repeated at a first cycle, and stores historical data including the measurement values of each QCM sensor 10 and humidity sensor 70 for each gas measurement process, the measurement values of each QCM sensor 10 after humidity correction, odor evaluation results, etc. in the memory unit 46 as first historical data.

[0089] (Correction coefficient calculation process) The control device 4 first executes the gas measurement process, and then periodically executes the calculation process of the update correction coefficients in a second cycle. In this embodiment, the calculation process of the update correction coefficients is executed in the second cycle, that is, every 24 hours (steps 107 to 111). The calculation process of the update correction coefficients is executed for each QCM sensor 10.

[0090] The calculation process of the update correction coefficients uses the correction formula shown in the above formula (1) to calculate the update correction coefficients (step 108) based on the measurement values of the QCM sensor 10 and the humidity sensor 70 for the past 24 hours stored in the memory unit 46. As will be described later, the control device 4 determines whether the calculated update correction coefficients are within an allowable range (step 109), and if they are within the allowable range, updates the current correction coefficients with the calculated update correction coefficients, and performs humidity correction processing of the measurement values of each QCM sensor 10 using the updated correction coefficients from the next gas measurement process.

[0091] On the other hand, if the calculated update correction coefficient is outside the allowable range, the calculated update correction coefficient is discarded, and the current correction coefficient continues to be used to perform humidity correction processing on the measurement values of each QCM sensor 10.

[0092] The calculation process and update process of the update correction coefficients described above are repeatedly executed in a second cycle, and history data including the calculation results of the update correction coefficients each time and the updated values of the correction coefficients are stored in the memory unit 46 as second history data.

[0093] (Decision on whether or not to adopt the update correction coefficient) The determination of whether or not the update correction coefficient is adopted, which is performed in the process of step 109, will be described below.

[0094] 7 is a diagram showing an example of the history of correction coefficients. Memory unit 46 stores historical data on correction coefficients from the start of operation of gas detection apparatus 100 to the present for each QCM sensor 10. As shown in the figure, the values and trends of the correction coefficients differ for each QCM sensor, and it can be seen that the correction coefficient for "ch4" in particular fluctuates significantly each time it is updated.

[0095] Fig. 8 is an explanatory diagram of the criteria for determining whether or not to adopt an updated correction coefficient. In the figure, the horizontal axis is the number of days, the vertical axis is the correction coefficient, and the history of correction coefficients updated on a daily basis is shown in a line graph, with the circled points being the newly calculated correction coefficients (the same applies to Figs. 9 and 10).

[0096] In the illustrated example, the criteria for judgment are set to a range of ±3σ, which is three times the standard deviation of the average value of past correction coefficients, and this range is set as the allowable range for the correction coefficient to be updated. Therefore, in the illustrated example, since the newly calculated update correction coefficient is within the allowable range, the current correction coefficient is updated to the update correction coefficient (steps 109 and 110 in FIG. 6). Such judgment is performed individually for each QCM sensor 10.

[0097] Since the allowable range reflects the previous correction coefficient, the average value of the correction coefficient can be regarded as a predicted value of the correction coefficient to be updated next time. In other words, since the average value of the correction coefficient varies depending on the number of days, and therefore the allowable range also constantly fluctuates, it is possible to update the correction coefficient to an appropriate value that reflects the actual situation. The past correction coefficients referenced when calculating the update correction coefficients may be those from a predetermined period in the past (for example, within the past two weeks). In this case, the update correction coefficients are calculated using relatively recent past correction coefficients, making it easier to obtain correction coefficients that are in line with the actual situation.

[0098] On the other hand, as shown in FIG. 9, if the newly calculated update correction coefficient falls outside the allowable range, the control device 4 determines that the update correction coefficient is inappropriate and discards it (steps 109 and 111 in FIG. 6).

[0099] If some abnormality has occurred in the QCM sensor 10 within the past 24 hours, such as deterioration of the adsorption film 12, detection of a low concentration of a specific odor component, or detection of an unknown odor component, the updated correction coefficient calculated based on this data is likely to vary significantly from the previous correction coefficient. Therefore, since adopting such a correction coefficient outside the allowable range as the new correction coefficient could lead to an erroneous evaluation of the odor measurement, we decided not to adopt the updated correction coefficient calculated this time. Furthermore, even if the previously calculated update correction coefficient is outside the allowable range, the next calculated update correction coefficient may fall within the allowable range, as shown in FIG. Therefore, if it is determined that the calculated update correction coefficient is outside the allowable range, the current correction coefficient is typically continued to be used. However, this is not limited to this, and for example, the average value of the correction coefficients for the most recent few days within the allowable range may be updated as the update correction coefficient.

[0100] If an update correction coefficient outside the allowable range is calculated multiple times in succession, the average value of the past correction coefficients may be used as described above.

[0101] As described above, in this embodiment, the measurement values of QCM sensor 10 and humidity sensor 70 obtained during steady-state operation of gas detection apparatus 100 are numerically processed, the correction coefficients are periodically updated, and the predicted value and range of the next correction coefficient are calculated from the history of the obtained correction coefficients, and only if the value obtained by the next measurement falls within that range, the new correction coefficient is adopted as the latest correction coefficient. This makes it possible to flexibly respond to changes in the sensors over time and improve the correction accuracy of the measurement values.

[0102] Furthermore, according to this embodiment, the correction coefficients are automatically calculated and updated, so that highly accurate anomaly detection can be performed stably over a long period of time. In particular, it becomes easier to check for anomalies in places where people do not normally enter, such as distribution boards, thereby reducing the burden on workers.

[0103] Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and that various modifications can be made.

[0104] For example, in the above embodiment, a QCM sensor has been described as an example of an odor component detection element, but this is not limiting and other detection elements, such as semiconductor sensors whose resistance changes upon adsorption of odor components, may also be used. Furthermore, the detection elements may be ones that can detect physical changes, such as an increase in weight or expansion stress due to gas adsorption of the adsorption film, and convert them into electrical signals.

[0105] The gas detection device according to the present invention is not limited to applications for detecting abnormalities such as fires. For example, it may be used as a sensor for detecting unpleasant odor components in a room and performing ventilation operations. The present invention is also applicable to analyzing odor components contained in unknown gases.

[0106] Furthermore, in the above embodiment, the measurement value of the humidity sensor 70 is determined based on the change in the resonant frequency of the QCM sensor 10 with the largest frequency fluctuation, and the measurement value of that humidity sensor 70 is commonly used to perform humidity correction on the measurement values of the QCM sensor 10 of each detection channel, but this is not limited to this. For example, the measurement value of the humidity sensor 70 may be determined individually for each detection channel based on the minimum or maximum value of the resonant frequency of each QCM sensor 10, and the humidity correction on the measurement value of the QCM sensor 10 of each detection channel may be performed individually using the determined measurement value of the humidity sensor of each detection channel. [Explanation of symbols]

[0107] 4...Control device 10...QCM sensor (detection element) 12...Adsorption film 41…Acquisition part 42…Measuring part 43...Calculation section 44…Update section 45...Judgment section 46...Storage section 70...Humidity sensor 100...Gas detection device

Claims

1. a detection element that produces an output change upon adsorption of odor components contained in the detection target gas; a humidity sensor for detecting the humidity of the detection target gas; Control device and Equipped with The control device an acquisition unit that acquires a measurement value of the detection element and a measurement value of the humidity sensor; a calculation unit that calculates a correction coefficient based on first history data that is a history of measurement values of the detection element and the humidity sensor, and calculates an update correction coefficient using history data most recent from the first history data; a measurement unit that measures the odor component based on the output of the detection element that has been humidity-corrected using the correction coefficient; and a determination unit that calculates a predicted value of the update correction coefficient and a range of the predicted value based on second history data that is a history of the correction coefficient, and determines whether the update correction coefficient is within the range of the predicted value; an updating unit that updates the correction coefficient to the update correction coefficient when the update correction coefficient is within the range of the predicted value; Gas detection equipment.

2. 2. The gas detection device according to claim 1, The measurement value of the detection element used as a reference when determining the measurement value of the humidity sensor is the minimum or maximum value of the resonance frequency acquired within the measurement period, or the resonance frequency at the end of the measurement period. Gas detection equipment.

3. 3. The gas detection device according to claim 1 or 2, The measurement values of the detection element and the humidity sensor are time-linked to each other. Gas detection equipment.

4. 2. The gas detection device according to claim 1, The predicted value of the update correction coefficient is the average value of the correction coefficient in the second history data, and the range of the predicted value is obtained by multiplying the standard deviation of the history of the correction coefficient by a certain coefficient. Gas detection equipment.

5. The gas detection device according to any one of claims 1 to 4, The detection element has a plurality of detection elements. Gas detection equipment.

6. The gas detection device according to any one of claims 1 to 5, The detection element is a vibration device having an adsorption film that adsorbs the odor components, and the adsorption of the odor components causes a change in resonance frequency. Gas detection equipment.

7. 1. A humidity correction method for a gas detection device, comprising: A measurement value of a detection element that changes its output due to adsorption of odor components contained in the detection target gas and a measurement value of a humidity sensor that detects the humidity of the detection target gas are obtained; calculating a correction coefficient based on first history data which is a history of measurement values of the detection element and the humidity sensor, and calculating an updated correction coefficient using the most recent history data of the first history data; measuring the odor component based on the output of the detection element that has been humidity-corrected using the correction coefficient; calculating a predicted value of the update correction coefficient and a range of the predicted value based on second history data which is a history of the correction coefficient, and determining whether the update correction coefficient is within the range of the predicted value; When the update correction coefficient is within the range of the predicted value, the correction coefficient is updated to the update correction coefficient. Humidity correction method.

8. 1. A control device for a gas detection device, comprising: an acquisition unit that acquires a measurement value of a detection element that produces an output change due to adsorption of odor components contained in the detection target gas and a measurement value of a humidity sensor that detects the humidity of the detection target gas; a calculation unit that calculates a correction coefficient based on first history data that is a history of measurement values of the detection element and the humidity sensor, and calculates an update correction coefficient using history data most recent from the first history data; a measurement unit that measures the odor component based on the output of the detection element that has been humidity-corrected using the correction coefficient; and a determination unit that calculates a predicted value of the update correction coefficient and a range of the predicted value based on second history data that is a history of the correction coefficient, and determines whether the update correction coefficient is within the range of the predicted value; an updating unit that updates the correction coefficient to the update correction coefficient when the update correction coefficient is within the range of the predicted value; A control device comprising:

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