JP6353227B2 - Gas sensor control device and infrared analysis type gas concentration detection device - Google Patents

Description

  The present invention relates to a gas sensor control device connected to a non-distributed gas sensor that can be used for detecting the concentration of a specific gas in exhaled air, managing air conditioning, managing the atmosphere of an industrial process, detecting various gas leaks, and the like. The present invention relates to an infrared analytical gas concentration detection device having

The non-dispersive infrared gas sensor (NDIR) passes the measurement target gas between a light source that emits infrared light and an infrared detection unit that detects the amount of infrared light. The gas concentration is measured by taking advantage of absorption by molecules inside. In addition, an optical filter for wavelength selection is arranged in front of the infrared detection unit, and only the infrared ray having a specific wavelength determined by the molecular structure of gas molecules (CO, CO _2, etc.) is transmitted to discriminate the gas type. ing. Note that the "closed path arrangement format" that allows the gas to be measured to flow through the cylinder (cell) and the "open path" in which the gas flows between the light source and the infrared detector without using the cell. Arrangement format ".
However, since every object emits infrared rays according to its own temperature, when the ambient temperature of the measurement environment changes, the various members that make up the non-dispersive infrared gas sensor (for example, in the case of a closed-path arrangement type, the cylinder surface) ) Also changes, and the detection output of the infrared detector changes even though the gas concentration does not change, resulting in a drift phenomenon in which the detection accuracy decreases.

  Therefore, a technique for correcting the sensitivity of the gas concentration by taking the difference between the detection output when the light source is on and the detection output when the light source is temporarily turned off is disclosed (see Patent Document 1). Then, by using this difference as a gas concentration detection value, it is possible to cancel the influence of the temperature change around the measurement environment and correct the drift. That is, as shown in FIG. 17, since the detection output V0 when the light source is temporarily turned off represents infrared radiation as a background reflecting the ambient temperature, the detection output VH when the light source is on. By subtracting V0 from the true detection output ΔV (= VH−V0) excluding the influence of the temperature change around the measurement environment.

JP-A-8-233810 (FIGS. 2 and 5)

By the way, as shown in FIG. 17, the detection timing is different from the detection time T1 of the detection output VH1 and the detection time T2 of the detection output V0 (1). In this case, if the ambient temperature of the measurement environment does not change with time, V0 also does not change with time, and V0 (1) = V0 (2) = V0 (3). Drift correction can be performed without considering the influence of the detection timing shift.
However, when the ambient temperature of the measurement environment changes with time, as shown in FIG. 18, the detection outputs VH and V0 themselves change with time, so that ΔV cannot be obtained accurately due to a shift in detection timing. There is a problem. That is, as shown in FIG. 18, the original value of V0 at the detection time T1 of the detection output VH1 is V0 (0), but changes to V0 (1) at the detection time T2. Therefore, when true ΔV = VH1−V0 (0), an incorrect value ΔV ′ = VH1−V0 (1) is calculated.
In particular, when measuring a gas containing a large amount of moisture, it is necessary to prevent condensation by heating the non-dispersive infrared gas sensor itself with a heater, and the ambient temperature may rise with time due to the heater heating. The ambient temperature also changes when the gas flow rate changes with time during the measurement.
SUMMARY OF THE INVENTION An object of the present invention is to provide a gas sensor control device and an infrared analytical gas concentration detection device that suppresses a decrease in gas concentration detection accuracy due to a temporal change in the measurement environment of a non-dispersive infrared gas sensor. To do.

In order to solve the above-described problems, a gas sensor control device of the present invention is connected to a gas sensor including a light source that emits infrared light to a measurement target gas and an infrared detection unit that detects the infrared light, and is emitted from the light source. A first light amount that is different from the first set light amount over a second cycle time and that has a predetermined value without turning off the light source so that the infrared light amount becomes a first set light amount over a first cycle time. A light source control unit that performs control to switch alternately so as to obtain two set light quantities; and a gas concentration calculation unit that calculates the concentration of the measurement target gas from the detection signal of the infrared detection unit, and the first period time The detection signal detected by the infrared detection unit in the first detection signal, the detection signal detected by the infrared detection unit in the second period time as the second detection signal, the gas concentration calculation unit A first average signal obtained by averaging the values of the first detection signals detected in two first cycle times that are continuous in time, and a second cycle time between the two first cycle times. A second average signal obtained by averaging the values of the second detection signals detected based on the first information group consisting of the second detection signals or in two time periods that are consecutive in time, and Based on the second information group consisting of the first detection signals detected in the first cycle time between the two second cycle times, the concentration of the measurement target gas is calculated.

During measurement with a non-dispersive infrared gas sensor, the temperature of various members constituting the non-dispersive infrared gas sensor changes with changes in the ambient temperature of the measurement environment, gas flow rate, etc., and infrared rays emitted from these members Since the amount also changes, a drift phenomenon occurs in which the detection signal of the infrared detection unit changes even though the gas concentration does not change. Therefore, the drift due to the change in the measurement environment is canceled by switching the infrared light quantity between two set light quantities and calculating the gas concentration based on the detection signal at each light quantity. However, when the temperature, etc. change with time, that is, when the fluctuation amount of temperature, etc. is not constant with respect to time, the detection timing for each light quantity shifts as the light quantity changes, and the gas concentration detection accuracy decreases. To do.
For this reason, in the gas sensor control device of the present invention, the first average signal or the second average signal is used to virtually match the detection timing with the corresponding second detection signal or first detection signal. Therefore, it is possible to suppress a decrease in gas concentration detection accuracy accompanying a temporal change in the surrounding measurement environment.

Furthermore, in the gas sensor control device of the present invention, the first average signal is a weighted average of the values of the first detection signals respectively detected in the two time periods that are continuous in time. The second average signal may be a weighted average of the values of the second detection signals respectively detected in the two time periods that are continuous in time.
When the temporal change of the surrounding measurement environment itself changes with time, that is, when the temporal change of the measurement environment is not monotonically increasing or decreasing, the measurement environment is not a simple average when calculating the first average signal. By taking a weighted average obtained by weighting the values of the two first detection signals in accordance with the temporal change state, it is possible to further suppress a decrease in the detection accuracy of the gas concentration.

  Similarly, when calculating the second average signal, it is not a simple average, but by taking a weighted average obtained by weighting the values of the two second detection signals in accordance with the temporal change state of the measurement environment, A decrease in detection accuracy can be further suppressed.

Furthermore, in the gas sensor control device of the present invention, the gas concentration calculation unit may determine a weighting factor used for the weighted average based on an external temperature measured by an external temperature measurement unit provided outside the gas sensor. Good.
According to this gas sensor control device, the weight coefficient used for the weighted average is set to a value reflecting the external temperature, so that a decrease in gas concentration detection accuracy can be further suppressed.

Furthermore, in the gas sensor control device of the present invention, the gas concentration calculation unit is configured to calculate the weighted average based on a temperature of the infrared detection unit measured by an infrared detection unit temperature measurement unit provided in the vicinity of the infrared detection unit. The weighting factor to be used may be determined.
According to this gas sensor control device, the weight coefficient used for the weighted average is set to a value that reflects the temperature of the infrared detection unit, thereby further suppressing a decrease in gas concentration detection accuracy.

Furthermore, in the infrared gas sensor control device of the present invention, the first cycle time and the second cycle time may be 2 seconds or less.
The detection signal drift due to the temporal change of the measurement environment such as the temperature described above usually has a time constant of 4 seconds or more. During this time, the first information group and the second information group are added one by one. If two or more sets can be obtained, the gas concentration can be calculated with high accuracy. Therefore, in this gas sensor control device, each cycle time is defined as 2 seconds or less.

  An infrared analytical gas concentration detection device of the present invention includes the gas sensor control device, a light source that is connected to the gas sensor control device and emits infrared light to a measurement target gas, and an infrared detection unit that detects the infrared light. A gas sensor.

  The infrared analytical gas concentration detection device of the present invention may further include an external temperature measurement unit that is provided outside the gas sensor and measures an external temperature of the gas sensor.

  The infrared analytical gas concentration detection device of the present invention may further include an infrared detection unit temperature measurement unit that is provided in the vicinity of the infrared detection unit and measures the temperature of the infrared detection unit.

  According to the present invention, it is possible to obtain a gas sensor control device and an infrared analytical gas concentration detection device that suppresses a decrease in gas concentration detection accuracy accompanying a temporal change in the measurement environment of the gas sensor.

1 is an overall configuration diagram of an infrared analytical gas concentration detection apparatus according to a first embodiment of the present invention. It is a figure which shows the outline of the method of calculating | requiring detection signal (DELTA) V by gas concentration calculation processing. In 1st Embodiment, it is a figure showing the time chart which shows the acquisition timing of VH and VL, and the 1st setting light quantity (CH) of a light source, and the 2nd setting light quantity (CL). It is a figure which shows the flowchart of the acquisition process of VH and VL in 1st Embodiment. FIG. 5 is a diagram illustrating a flowchart of a gas concentration calculation process using a first average signal VH ′ and a second average signal VL ′ in the first embodiment. In 2nd Embodiment, it is a figure showing the time chart which shows the acquisition timing of VH and VL, and the time chart which shows the 1st setting light quantity (CH) and 2nd setting light quantity (CL) of a light source. In 2nd Embodiment, it is a figure which shows the flowchart of the acquisition process of VH and VL. In 2nd Embodiment, it is a figure which shows the flowchart of the gas concentration calculating process using 1st average signal VH 'and 2nd average signal VL'. In 3rd Embodiment, it is a figure which shows the outline of the method of calculating | requiring detection signal (DELTA) V by gas concentration calculation processing. FIG. 10 is a partially enlarged view in the vicinity of VH (1) and VH (2) in FIG. 9. In 3rd Embodiment, the time chart which shows the acquisition timing of VH and VL, the time chart which shows the 1st setting light quantity (CH) of a light source, and 2nd setting light quantity (CL), and the temperature of external temperature and an infrared detection element It is a figure showing the time chart shown. In 3rd Embodiment, it is a figure which shows the flowchart of the gas concentration calculating process using 1st average signal VH 'and 2nd average signal VL'. It is a figure which shows an example of the method of estimating the time change of VH and VL. It is a figure which shows an example of the table of the weighting factors A and B corresponding to the time change of VH and VL. It is a figure which shows the time change of actual detection signal (DELTA) V when changing ambient temperature and producing the change of VH and VL. It is a figure which shows the time change of actual detection signal (DELTA) V when changing the flow volume of measurement object gas and producing the change of VH and VL. It is a figure showing the conventional time chart which calculates (DELTA) V which is the difference of detection output VH1 and the detection output V0 by light source off. It is a figure showing the conventional time chart which calculates (DELTA) V which is the difference of the detection output VH1 and the detection output V0 by light source OFF, when the ambient temperature of a measurement environment changes with time.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is an overall configuration diagram of an infrared analytical gas concentration detector 1 according to an embodiment of the present invention. The infrared analytical gas concentration detection device 1 includes a non-dispersive infrared gas sensor (gas sensor) 100 and an infrared gas sensor control device (gas sensor control device) 60 connected to the non-dispersive infrared gas sensor 100. In addition, in FIG. 1, the cross-sectional structure along the length direction of the non-dispersion type | mold infrared gas sensor 100 is shown.

The non-dispersive infrared gas sensor 100 includes a cylindrical barrel 102, a light source 121 that emits infrared rays, and an infrared detection unit (infrared detection element) 122 that are arranged opposite to each other at both ends of the barrel 102. An infrared wavelength selection filter (band pass filter) 110 is disposed on the light receiving surface side of the infrared detection element 122. Then, the measurement target gas G is introduced from the inlet 103 provided on the side surface of the lens barrel 102, and the measurement target gas G is discharged to the outside from the outlet 104 provided on the side surface of the lens barrel 102. Then, when infrared rays irradiated from the light source 121 toward the infrared detection element 122 in the lens barrel 102 pass through the measurement target gas G, the infrared rays of the infrared detection element 122 are absorbed. Based on the output, the concentration of the specific gas contained in the measurement target gas G is measured.
The non-dispersive infrared gas sensor 100 is configured in a “closed path arrangement format” in which the measurement target gas is introduced into the measurement space 102s in the lens barrel 102, which is a closed space, and the inner surface of the lens barrel 102 on the light source 121 side. Is a spherical reflecting mirror 102 a that directs infrared rays emitted from the light source 121 toward the infrared detection element 122. The other inner surface 102 b of the lens barrel 102 is also mirror-finished so as to reflect infrared rays so that the infrared rays reach the infrared detection element 122.

Furthermore, when condensation occurs on the inner surfaces 102a and 102b of the lens barrel 102 when measuring a gas containing a large amount of moisture such as exhaled breath, the detection output of the infrared detection element 122 is lowered and the measurement becomes inaccurate. A heat insulating jacket 131 containing a heater 130 for preventing condensation is placed on the outside of the lens barrel 102.
An external temperature measuring unit (temperature sensor) 141 that measures the temperature outside the non-dispersive infrared gas sensor 100 is provided outside the heat insulating jacket 131. Similarly, an infrared detection unit temperature measurement unit (temperature sensor) 142 that measures the temperature of the infrared detection element 122 is provided in the vicinity of the infrared detection element 122. Here, “outside” of the non-dispersive infrared gas sensor 100 refers to the outside of the space (in the above example, the measurement space 102 s) where the infrared rays emitted from the light source 121 reach the infrared detection element 122.

Examples of the light source 121 include a light source such as a tungsten lamp and a white light source formed of a heating resistor such as a heater.
The lens barrel 102 can be made of, for example, plastic or metal. When the lens barrel 102 is made of plastic, the inner surface may be coated with a film of metal (aluminum, chromium, etc.) having high infrared reflectance.
Examples of the infrared detection element 122 include a thermopile element (TP), a pyroelectric element, and a photodiode (PD). The detection signal (detection output) of the infrared detection element 122 is usually a voltage, but is not limited to this.
Examples of the infrared wavelength selection filter 110 include a wavelength selection filter, a diffraction grating, and a Fabry-Perot filter. The wavelength selection filter is formed by laminating a plurality of transparent films on the surface of a substrate made of an infrared transmitting material such as sapphire, quartz glass, silicon, germanium, or zinc selenide.

The non-dispersive infrared gas sensor 100 is connected to the infrared gas sensor control device 60. The infrared gas sensor control device 60 is a control circuit in which a microcomputer 50 and a power supply circuit 61 are mounted on a substrate.
The microcomputer 50 stores various programs and data for executing light amount control of the light source 121, gas concentration calculation processing, and the like, and a program stored in the storage device 55. The CPU 51 is a known device including an IO port for inputting and outputting various signals, a timer for timekeeping, and the like.
The microcomputer 50 corresponds to an example of a gas concentration calculation unit, and the microcomputer 50 and the power supply circuit 61 correspond to an example of a light source control unit. The gas concentration calculation unit calculates the concentration of the measurement target gas from the detection signal of the infrared detection element 122, and performs a process for obtaining a weighting coefficient described later from the temperature information of the temperature sensors 141 and 142.

The light source control unit performs control for switching the amount of infrared light emitted from the light source 121 between two set light amounts set in advance for each predetermined cycle time via the power supply circuit 61 controlled by the microcomputer 50. More specifically, the control is performed so that the first set light amount becomes the first set light amount over the first cycle time and the second set light amount is different from the first set light amount over the second cycle time. Here, in the present embodiment, the larger set light amount is set to be the first set light amount, and the smaller side is set to the second set light amount. The second set light amount is a value obtained when the light source control unit turns off the light source 121 in addition to a predetermined amount of light controlled by the light source control unit (ideally 0, but from various members around the measurement environment. (A minute amount of light reflecting inevitable infrared rays). That is, the power supply circuit 61 may be a circuit that adjusts the amount of light according to a necessary measurement cycle, and may be intermittently driven (flashed) so that the light source 121 can be turned on and off. Further, when the light source 121 is turned on / off, a chopper may be provided between the light source 121 and the infrared detector 122 instead of the power supply circuit 61.
The microcomputer 50 is activated when power supply from the DC power supply is started by turning on a predetermined activation switch, and after various parts of the microcomputer 50 are initialized, various processes are started.

Here, the signal level of the detection signal detected by the infrared detection element 122 at the first set light amount CH is the first detection signal VH, and the signal level of the detection signal detected at the second set light amount CL is the second detection signal VL. Let's say.
The storage device 55 includes concentration conversion data representing a correlation between ΔV (= VH−VL), which is the difference between the first detection signal VH and the second detection signal VL, and the gas concentration of the measurement target, and a temperature sensor. Weight coefficient conversion data representing a correlation between temperature information 141 and 142 and a weight coefficient described later is stored at least. Each conversion data is specifically composed of conversion map data (table), a calculation formula for conversion, and the like, and is created in advance based on data obtained by experiments or the like.

[Gas concentration calculation process in the first embodiment]
Next, the gas concentration calculation process of the infrared gas sensor control device according to the first embodiment of the present invention will be described with reference to FIGS. In the following description, the detection signal indicates a voltage.
FIG. 2 shows an outline of a method for obtaining the detection signal ΔV by the gas concentration calculation process of the infrared gas sensor control device 60. In the present invention, ΔV = VH−VL, which is the difference between VH and VL, is used for the calculation of the gas concentration, thereby canceling the temperature change around the measurement environment and correcting the drift. In the example of FIG. 2, the ambient temperature of the measurement environment increases at a substantially constant rate with time, and the first detection signal VH and the second detection signal VL are approximately with time even though the gas concentration does not change. It is increasing at a certain rate.

Here, the first cycle time TW1 that is the detection time of VH1 is different from the second cycle time TW2 that is the detection time of VL1, and VH1 ′ in the second cycle time TW2 is VH1 in the first cycle time TW1. Has changed since. Therefore, by estimating the predicted value of VH (first average signal VH1 ′) at the same detection timing (TW2) as VL1, VH and VL can be accurately obtained at the same detection timing, and the temporal change in ambient temperature. It is possible to suppress a decrease in the gas concentration detection accuracy associated with.
Specifically, the first average signal VH1 ′ is obtained by averaging two VH1 and VH2 values that are temporally continuous in the first cycle times TW1 and TW3. VH1 is detected at a predetermined elapsed time when the light quantity is stable within the first cycle time TW1, and is represented by “first cycle time TW1”. The same applies to the detection times of the other VH and VL.
Similarly, a predicted value of VL (second average signal VL1 ′) at the same detection timing (TW3) as VH2 is estimated, and ΔV is obtained at the same detection timing.
Details of the gas concentration calculation process will be described below with reference to FIGS.

  FIG. 3 is a time chart showing the acquisition timing of VH and VL, respectively (FIGS. 3A and 3B), and a time chart showing the first set light amount (CH) and the second set light amount (CL) of the light source 121. (FIG. 3C) is represented. 4 is a flowchart of the VH and VL acquisition processing, and FIG. 5 is a flowchart of the gas concentration calculation processing using the first average signal VH ′ and the second average signal VL ′.

When the ambient temperature rises during detection, VH and VL increase with time (FIGS. 3A and 3B), so after detecting VH1 at the first first cycle time TW1, When VL1 is detected at the cycle time TW2, the value of the second detection signal becomes larger than when it is detected at the same timing (first cycle time TW1) as VH1. Therefore, in the first embodiment, the first average signal VH1 ′ obtained by averaging the values of two VH1 and VH2 temporally continuous in the first cycle times TW1 and TW3, and the second cycle between VH1 and VH2. The gas concentration is calculated based on the relationship with VL1 at time TW2 (this is referred to as “first information group”). Here, VH and VL used for the first information group are illustrated by an inverted triangular region R1 in FIG.
Thus, the predicted value (first average signal VH1 ′) of the first detection signal at the same detection timing (second cycle time TW2) as the second detection signal (VL1) is used as the other first cycle times TW1, TW3. Therefore, VH, VL, and thus ΔV are obtained at the same detection timing to suppress a decrease in detection accuracy of the gas concentration accompanying a temporal change in the ambient temperature. Can do. That is, in the gas concentration calculation process according to the first embodiment, the first average signal VH1 ′ obtained by averaging the values of the two first detection signals VH1 and VH2 that are temporally continuous and the two first detection signals VH1. , VH2, the gas concentration is calculated based on the first information group including the second detection signal VL1 in the second cycle time TW2.
In FIG. 3, the first detection signal is detected in time sequence in the order of the subscripts 1, 2, and 3 of the first detection signal (VH), and similarly the subscripts 1 and 2 of the second detection signal (VL). , 3, the second detection signal is detected in time series.

Furthermore, in the first embodiment, after calculating the first information group at the first cycle time TW3 as described above, the second detection signal VL1 used for calculating the first information group and the next The second average signal VL1 ′ is calculated by averaging the second detection signal VL2 detected at the two cycle time TW4. Then, the gas concentration is calculated based on the relationship between VL1 ′ and VH2 in the cycle time TW3 between VL1 and VL2 (this is referred to as “second information group”). Here, VH and VL used for the second information group are illustrated by a triangular region R2 in FIG.
Also in the second information group, the predicted value (second average signal VL1 ′) of the second detection signal at the same detection timing (first cycle time TW3) as the first detection signal (VH2) is used for the other second cycle. Since it is estimated from the second detection signals (VL1, VL2) at times TW2 and TW4, the voltage difference and voltage ratio of VH and VL are obtained at the same detection timing, and the gas concentration is detected as the ambient temperature changes with time. A decrease in accuracy can be suppressed. That is, in the gas concentration calculation process according to the first embodiment, the second average signal VL1 ′ obtained by averaging the values of the two second detection signals VL1 and VL2 that are temporally continuous and the two second detection signals VL1. , VL2 based on the second information group consisting of the first detection signal VH2 at the first cycle time TW3, the gas concentration is calculated.
As described above, after the second information group is calculated at the second cycle time TW4, it is detected at the first detection signal VH2 used for calculating the second information group and the next first cycle time TW5. Using the first detection signal VH3, the first information group is calculated in the same manner as described above. As described above, by alternately calculating the first information group and the second information group, the same detection is performed every second cycle time TW4, first cycle time TW5... After the first cycle time TW3. Since VH, VL, and thus ΔV are obtained at the timing, the gas concentration detection accuracy is further improved. On the other hand, when only one of the first information group and the second information group is calculated as in the second embodiment described later, the calculation timing is twice the period time (FIG. 6). reference).

  Next, VH and VL acquisition processing and gas concentration calculation processing executed by the CPU of the microcomputer 50 will be described with reference to FIGS. In the calculation for obtaining the gas concentration X, the gas concentration X is obtained from the above-described ΔV, which is the difference between the first detection signal VH and the second detection signal VL, using the concentration conversion data.

As shown in FIG. 4, in the VH and VL acquisition processing, first, in step S102, the CPU switches the light source 121 to the high light amount side (first set light amount (CH) side) to emit infrared rays. Specifically, the power supply circuit 61 performs control to hold the light amount of the light source 121 at the first set light amount CH for a predetermined cycle time TW.
Next, in S <b> 104, the CPU obtains the external temperature of the non-dispersive infrared gas sensor 100 and the temperature of at least one of the infrared detection elements 122 from the temperature sensors 141 and 142. The temperature data acquired in S104 and S118 described later is not used in the first embodiment, but is used in a third embodiment described later. FIG. 3C is a time chart showing the light amount of the light source 121. A subscript m and a subscript n, which will be described later, are natural numbers and indicate that they are acquired in time series in the order of 1, 2, 3, and so on.
Next, in S106, the CPU determines whether or not the first detection signal (VHm) is acquired for the first time, that is, whether it is VH1, and if No, 1 is assigned to the concentration calculation flag (S108). 1 is assigned to the determination flag (S110). Further, the process proceeds from S110 to S112. On the other hand, if Yes in S106, the process proceeds to S112 as it is.
Note that the density calculation flag = 1 means that VHm has been acquired a plurality of times, and the first average signal VHm-1 is obtained by averaging the values of two consecutive VHm-1 and VHm as described in FIG. Indicates that 'can be calculated. The calculation determination flag is a flag for determining which of the first average signal VHm-1 ′ and the second average signal VLn-1 ′ is calculated in the flow of FIG. 5 described later. In this case, the first average signal VHm-1 ′ is calculated.

Next, in S112, the CPU acquires the first detection signal (VHm) of the light source 121, and determines whether or not the cycle time TW has elapsed (S114). If Yes in S114, the process proceeds to S116, and if No, the process returns to S114 and waits for the cycle time TW to elapse. In the example of FIGS. 4 and 5, TW = 200 msec.
Next, in S116, the CPU switches the light source 121 to the low light amount side (second set light amount (CL) side), and emits infrared rays. Next, in S <b> 118, the CPU acquires from the temperature sensors 141 and 142 the external temperature of the non-dispersive infrared gas sensor 100 and the temperature of at least one of the infrared detection elements 122.
Next, in S120, the CPU determines whether or not the second detection signal (VLn) is acquired for the first time, that is, whether it is VL1. If Yes, the process proceeds to S124, and if No, the calculation determination flag is set. 0 is assigned (S122). When the calculation determination flag = 0, the second average signal VLn-1 ′ can be calculated by averaging the values of two consecutive VLn−1 and VLn as described with reference to FIG. A process of calculating VLn-1 ′ is performed. Further, after the process of S122, the process proceeds to S124.
Next, in S124, the CPU acquires the second detection signal (VLn) of the light source 121, and determines whether or not the cycle time TW has elapsed (S126). If Yes in S126, the process proceeds to S128, and if No, the process returns to S126 and waits for the elapse of the cycle time TW.
In S128, the CPU switches the light source 121 to the high light amount side (first set light amount (CH) side), emits infrared rays, and returns to S104.
The VHm and VLn acquired as described above are stored in the storage device 55 (RAM) in association with the concentration calculation flag and the calculation determination flag, and read out by the following gas concentration calculation processing.

Next, the gas concentration calculation process will be described with reference to FIG. The gas concentration calculation process is performed every cycle time TW described above. That is, since the section from S104 to S114 in FIG. 4 is processed with the cycle time TW, the gas concentration calculation process is performed by reading the calculation determination flag in S110 when S114 has elapsed. Further, the section from S116 to S126 is processed at the next cycle time TW, and the next gas concentration calculation process that reads the calculation determination flag at S122 is performed even when S126 has elapsed.
In FIG. 5, first, in step S202, the CPU determines whether or not the density calculation flag is 1. If Yes in S202, the process proceeds to S204, and if No, the gas concentration calculation process is terminated and prepared for the next time. Next, in S204, the CPU determines whether or not the calculation determination flag is 1. If YES in S204 (that is, when acquisition processing of two first detection signals VHm-1 and VHm that are temporally continuous in S104 to S114 in FIG. 4), the process proceeds to S206, and VHm-1, VHm and VLn are acquired. Here, the case of m = 2 and n = 1 corresponds to R1 in FIG. 3, and the gas concentration based on the first information group consisting of the first average signal VHm-1 ′ and the second detection signal VLn. It becomes arithmetic processing. On the other hand, if No in S204, the process proceeds to the gas concentration calculation process based on the second information group including the second average signal VLn-1 ′ and the first detection signal VHm.

Next, in S208, the CPU calculates a first average signal VHm-1 ′. Specifically, VHm−1 ′ is calculated using VHm−1 and VHm acquired in S206 as input values of the following equation (1). That is, VHm-1 ′ is calculated by a simple average of VHm-1 and VHm.
VHm−1 ′ = (VHm−1 + VHm) / 2 (1)
In S210, the CPU calculates ΔV using VLn acquired in S206 and VHm−1 ′ calculated in S208 as input values of the following equation (2).
ΔV = VHm−1′−VLn (2)
Next, in S212, the gas concentration X is calculated based on ΔV calculated in S210 and the concentration conversion data, and the process returns to the beginning of the gas concentration calculation process.

  On the other hand, in the case of No in S204 (that is, in the case where two second detection signals VLn-1 and VLn that are temporally continuous in S116 to S126 in FIG. 4 are acquired), the process proceeds to S230 and VLn -1, VLn, VHm are acquired. Here, the case of m = 2 and n = 2 corresponds to R2 in FIG.

Next, in S232, the CPU calculates a second average signal VLn-1 ′. Specifically, VLn + 1 ′ is calculated using VLn−1 and VLn acquired in S230 as input values of the following equation (3). That is, VLn-1 ′ is calculated by a simple average of VLn-1 and VLn.
VLn−1 ′ = (VLn−1 + VLn) / 2 (3)
In S234, the CPU calculates ΔV using VHm acquired in S230 and VLn−1 ′ calculated in S232 as input values of the following equation (4).
ΔV = VHm−VLn−1 ′ (4)
In S236, the gas concentration X is calculated based on ΔV calculated in S234 and the concentration conversion data, and the process returns to the beginning of the gas concentration calculation process.

As described above, in the processes of FIGS. 4 and 5, the light amount of the light source 121 is switched every cycle time TW, thereby acquiring the first detection signals VHm−1 and VHm and the second detection signals VLn−1 and VLn.
Furthermore, the predicted value (first average signal VHm−1 ′) of the first detection signal at the same detection timing (cycle time) as the second detection signal VLn is used as the first detection signal (VHm−) at another cycle time. 1 and VHm), and the gas concentration X is calculated from ΔV which is the difference between the first detection signal VHm−1 ′ and the second detection signal VLn.
Therefore, ΔV at the same detection timing is obtained, and it is possible to suppress a decrease in gas concentration detection accuracy due to a temporal change in ambient temperature.

  The first cycle time and the second cycle time are each preferably 2 seconds or less. The change (drift) of VH and VL with time in the measurement environment such as temperature described above usually has a time constant of 4 seconds or more. During this time, the first information group and the second information group are 1 If two sets in total (corresponding to the regions R1 and R2 in FIG. 3) can be obtained, ΔV can be calculated with high accuracy and the gas concentration X can be calculated. Therefore, the cycle time is defined as 2 seconds or less.

[Gas concentration calculation processing in the second embodiment]
Next, the gas concentration calculation process of the infrared gas sensor control device according to the second embodiment of the present invention will be described with reference to FIGS.
FIG. 6 is a time chart showing acquisition timings of VH and VL (FIGS. 6A and 6B, respectively), and a time chart showing the first set light amount (CH) and the second set light amount (CL) of the light source 121. (FIG. 6C) is shown. FIG. 7 is a flowchart of the VH and VL acquisition processing, and FIG. 8 is a flowchart of the gas concentration calculation processing using the first average signal VH ′.

When the ambient temperature rises during detection, VH and VL increase with time as shown in FIG. 6 (FIGS. 6A and 6B), so VH1 was detected at the first first cycle time TW1. After that, when VL1 is detected at the next second cycle time TW2, the value of the second detection signal becomes larger than when it is detected at the same timing (first cycle time TW1) as VH1. Therefore, in the second embodiment, as in the first embodiment, a first average signal VH1 ′ obtained by averaging the values of two VH1 and VH2 temporally continuous in the first cycle times TW1 and TW3, and VH1 The gas concentration is calculated based on the first information group with VL1 in the second cycle time TW2 between VH2 and VH2. Here, VH and VL used for the first information group are illustrated by an inverted triangular region R1 in FIG.
Thus, the predicted value (first average signal VH1 ′) of the first detection signal at the same detection timing (second cycle time TW2) as the second detection signal (VL1) is used as the other first cycle times TW1, TW3. Therefore, VH and VL are obtained at the same detection timing, and it is possible to suppress a decrease in detection accuracy of the gas concentration accompanying a temporal change in the ambient temperature. That is, in the gas concentration calculation processing according to the second embodiment, the first average signal VH1 ′ obtained by averaging the values of the two first detection signals VH1 and VH2 that are temporally continuous, and the two first detection signals VH1 and VH2 are averaged. The gas concentration is calculated based on the first information group including the second detection signal VL1 at the second cycle time TW2.

  However, in the second embodiment, after the first information group is calculated at the first cycle time TW3, the next timing for calculating the first information group is the first cycle time TW5 delayed by two cycles. Here, VH and VL used for the first relationship calculated for the second time are shown as an inverted triangular region R3 in FIG. In this way, when only one of the first information group and the second information group is calculated, the first information group, that is, VH and VL at the same detection timing are calculated by twice the cycle time TW. Therefore, although the gas concentration detection accuracy is inferior to that of the first embodiment, there is an advantage that the processing load of the microcomputer is reduced.

  Next, VH and VL acquisition processing and gas concentration calculation processing executed by the CPU of the microcomputer 50 will be described with reference to FIGS.

As shown in FIG. 7, in the VH and VL acquisition processing, first, in step S302, the CPU switches the light source 121 to the high light amount side (first set light amount (CH) side) and emits infrared rays. Specifically, the power supply circuit 61 performs control to hold the light amount of the light source 121 at the first set light amount CH for a predetermined cycle time TW.
Next, in S306, the CPU determines whether or not the first detection signal (VHm) is acquired for the first time, that is, whether it is VH1, and if it is No, 1 is assigned to the density calculation flag (S308), and S312 is performed. Transition. If Yes in S306, the process proceeds to S312. In the second embodiment, since the second average signal VLn-1 ′ is not calculated, the operation determination flag is not used.

Next, in S312, the CPU acquires the first detection signal (VHm) and determines whether or not the cycle time TW has elapsed (S314). If Yes in S314, the process proceeds to S316, and if No, the process returns to S314 and waits for TW to elapse. In the examples of FIGS. 6 and 7, TW = 200 msec.
Next, in S316, the CPU switches the light source 121 to the low light amount side (second set light amount (CL) side) and emits infrared rays.
Next, in S324, the CPU acquires the second detection signal (VLn) and determines whether or not the cycle time TW has elapsed (S326). If Yes in S326, the process proceeds to S328, and if No, the process returns to S326 and waits for TW to elapse.
In S328, the CPU switches the light source 121 to the high light amount side (first set light amount (CH) side), emits infrared rays, and returns to S306.
The VHm and VLn acquired as described above are stored in the storage device 55 (RAM) in association with the concentration calculation flag, and read out by the following gas concentration calculation processing.

Next, the gas concentration calculation process will be described with reference to FIG. The gas concentration calculation process is performed every cycle time TW described above. That is, since the section from S306 to S314 in FIG. 7 is processed with the cycle time TW, the gas concentration calculation process (mainly the calculation of the first average signal VHm-1 ′) is performed when S314 has elapsed, The gas concentration calculation process (mainly acquisition of VLn) is also performed in the section of S316 to S326 processed in the period time TW.
However, since the process of FIG. 8 is the same as S206 to S226 of the process described in FIG. 5 except that there is no step S204 and the process immediately shifts from S202 to S206, the description is given with the same step number. Omitted.

[Gas concentration calculation process in the third embodiment]
Next, the gas concentration calculation process of the infrared gas sensor control device according to the third embodiment of the present invention will be described with reference to FIGS.
FIG. 9 shows an outline of a method for obtaining the detection signal ΔV by the gas concentration calculation process of the infrared gas sensor control device 60. In the example of FIG. 9, unlike the case of FIG. 2, the ambient temperature of the measurement environment rises while the amount of increase decreases with time, and VH and VL become convex curves with respect to time. Yes.

FIG. 10 is a partially enlarged view in the vicinity of VH1 and VH2 in FIG. In the first embodiment, since VH simply increases along the straight line L1 with respect to time, AV1 that is the value of the first average signal VH1 ′ is obtained by simply averaging the values of VH1 and VH2. . Specifically, AV1 that is the value of VH on the straight line L1 at the detection time T2 that is the midpoint between the detection times T1 and T3 at the first cycle times TW1 and TW3 is calculated as VH1 ′.
On the other hand, in the example of FIG. 9, VH increases with a curved line L2 that is convex upward with respect to time. Therefore, at detection time T2, which is the midpoint between detection times T1 and T3, AV2 that is the value of VH on the curve L2 Is larger than AV1.
Therefore, in the third embodiment, when the value of VH1 and VH2 is averaged to obtain AV2, the amount of increase in VH decreases with time, so VH1 that contributes to the value of AV2 is weighted more. AV2 is obtained by a weighted average.
Specifically, VH1 ′ is calculated by the following equation 5, and the weighting factor A> B is set here, so that VH1 can be heavily weighted.
VHm-1 ′ = {A × (VH1) + B × (VH2)} / (A + B) (5)

FIG. 11 is a time chart showing the acquisition timing of VH and VL (FIGS. 11A and 11B), and a time chart showing the first set light quantity (CH) and the second set light quantity (CL) of the light source 121. FIG. 11 (c)) and a time chart (FIG. 11 (d)) showing the external temperature and the temperature of the infrared detecting element are shown.
Note that the time chart of FIG. 11D is based on the temperatures obtained alternately in steps S104 and S118 of FIG. 4, and the temperatures obtained at the respective cycle times TW1, TW2,... Are TH1, TH2,.・ Let's say. Each temperature TH1, TH2,... Is precisely the temperature at the detection time of VH, VL, but is represented by “period time TW”.
FIG. 11 is the same as FIG. 3 of the first embodiment except that the time change curves of VH and VL are different from each other, so that the description thereof is omitted.
FIG. 12 is a flowchart of the gas concentration calculation process using the first average signal VH ′ and the second average signal VL ′. Note that the flowchart of the VH and VL acquisition processing is the same as that in FIG. 4 of the first embodiment, and thus the description and illustration are omitted.

Next, the gas concentration calculation process will be described with reference to FIG. However, the processing of FIG. 12 is the same as that of FIG. 5 except that the processing of S407 and S408 is performed instead of S208 after step S206, and the processing of S431 and S432 is performed after step S230 instead of S232. Since the process is the same as described, the same process as in FIG.
In FIG. 12, after obtaining VHm-1, VHm, and VLn in S206, weighting factors A and B are obtained (step S407). An example of specific processing in step S407 will be described later.
Next, in S408, the CPU calculates a first average signal VHm-1 ′. Specifically, VHm−1 ′ is calculated using VHm−1, VHm acquired in S206, and A and B acquired in S407 as input values of the following equation (6). That is, VHm-1 ′ is calculated by a weighted average of VHm-1 and VHm.
VHm-1 ′ = {A × (VHm−1) + B × (VHm)} / (A + B) (6)
Then, ΔV is calculated in S210, and in S212, the gas concentration X is calculated based on ΔV calculated in S210 and the concentration conversion data, and this gas concentration calculation process is terminated.

Similarly, after acquiring VLn-1, VLn, and VHm in S230, the weighting factors A and B are acquired (step S431). The processing content of S431 is the same as that of S407.
Next, in S432, the CPU calculates a second average signal VLn-1 ′. Specifically, VLn + 1 ′ is calculated using VLn−1, VLn acquired in S230 and A and B acquired in S431 as input values of the following equation (7). That is, VLn-1 ′ is calculated by a weighted average of VLn-1 and VLn.
VLn-1 ′ = {A × (VLn−1) + B × (VLn)} / (A + B) (7)
Then, ΔV is calculated in S234, and in S236, the gas concentration X is calculated based on ΔV calculated in S234 and the concentration conversion data, and the process returns to the beginning of the gas concentration calculation processing.

Next, an example of specific processing for obtaining the weighting factors A and B in steps S407 and S431 will be described with reference to FIGS. FIG. 13 shows an example of a method for estimating temporal changes in VH and VL, and FIG. 14 shows an example of a table of weighting factors A and B corresponding to temporal changes in VH and VL.
In FIG. 13, the CPU calculates a straight line L1 passing through the temperatures TH1 and TH2 at two first cycle times TW1 and TW2 (more precisely, the above-described times T1 and T2) that are temporally continuous. Then, the CPU calculates a magnitude relationship between the temperature TH3 at the next first cycle time TW3 and the virtual temperature TH3 ′ on the straight line L1 at the first cycle time TW3, that is, a value of ΔT = TH3′−TH3.
If ΔT = 0, VH and VL are considered to change along the straight line L with respect to time. On the other hand, if ΔT <0, VH and VL are considered to change along a convex curve L2 with respect to time. Similarly, if ΔT> 0, it is considered that VH and VL change along a downward convex curve L3 with respect to time.

  When the external temperature of the non-dispersive infrared gas sensor 100 is acquired from the temperature sensor 141 in step S118 and the like described above, and the weighting factor described later is changed, the weighting factor that reflects the usage environment (external temperature) of the gas sensor 100 is used. Thus, it is possible to further suppress a decrease in gas concentration detection accuracy. Here, when changing the weighting factor based on the temperature sensor 141, for example, different weighting factors are used when the external temperature is −40 ° C. and 25 ° C., but depending on the external temperature, the heat retention by the heater 130 may be increased. Since the weight coefficient is stable, the weight coefficient often does not change continuously even if the external temperature changes continuously.

Further, when the weighting factor is changed from the temperature of the infrared detecting element 122 by the temperature sensor 142 in the above-described step S118, the weighting factor reflecting the temperature of the infrared detecting element 122 can be obtained, and the detection accuracy of the gas concentration can be improved. The decrease can be further suppressed. Here, when the weighting coefficient is changed based on the infrared detection element 122, the weighting coefficient changes continuously as in the third embodiment.
As described above, the weighting factor may be changed using the temperature of at least one of the temperature sensors 141 and 142. However, in the above-described example, the weighting coefficient is changed using the temperature of either one of the temperature sensors 141 and 142. When both the temperatures of the temperature sensors 141 and 142 are used, both the temperature and the weight are used. The weighting coefficient is changed based on a mathematical formula or a table based on the relationship with the coefficient.

Next, the CPU refers to the table 55t shown in FIG. 14, acquires a set of weighting factors A and B corresponding to the value of ΔT, and performs the processes of steps S407 and S431. In the table 55t, sets of weighting factors A and B are recorded in association with various values of ΔT.
In the example of FIG. 13, when the first cycle time TW3 has elapsed, the temporal change of VH and VL is determined, the table 55t shown in FIG. 14 is referenced, and a set of weighting factors A and B corresponding to step S407 is obtained. To get. When the next second cycle time TW4 has elapsed, ΔT is calculated based on the straight line L1 passing through the temperatures TH2 and TH3 and the temperature TH4 at the second cycle time TW4, and a weighting factor A corresponding to step S431, Get a set of B. In this way, the CPU obtains a set of weighting factors A and B by sequentially using the latest three cycle times TW.
For example, in a section where the absolute value of ΔT is equal to or smaller than a certain value (for example, section S1 where the absolute value of ΔT is 1 or less in the table 55t in FIG. 14), VH and VL are substantially along a straight line L with respect to time. The first average signal VH ′ and the second average signal VL ′ may be calculated by A = B, that is, by a simple average similar to that of the first embodiment. In this way, the processing burden on the CPU is reduced as compared with the case where the set of weighting factors A and B is acquired from the table 55t one by one in accordance with the value of each ΔT.

  It goes without saying that the present invention is not limited to the above-described embodiment, but extends to various modifications and equivalents included in the spirit and scope of the present invention. For example, a device for storing various programs and data for executing each process in the microcomputer 50 is not limited to the storage device 55 provided in the microcomputer 50, and information is transmitted to and from the microcomputer 50. However, any form of external storage device or recording medium that can be used. In this case, the microcomputer 50 executes each process using various programs and data read from the external storage device or the recording medium. Examples of the recording medium include a portable semiconductor memory (for example, a USB memory, a memory card (registered trademark)), an optical disk such as a CD-ROM or a DVD, a magnetic disk, and the like.

Examples of the non-dispersive infrared gas sensor 100 include sensors that detect a physical quantity using an infrared light amount, such as an alcohol sensor, a CO ₂ sensor, a CO sensor, an HC gas sensor, a NOx gas sensor, an NH ₃ gas sensor, and an acetone gas sensor.
Further, in the above embodiment, the “closed path arrangement type” non-dispersion type infrared gas sensor is exemplified, but the present invention is not limited to this, and a reflection part and a base on which the infrared detection part (and wavelength selection means) are arranged are provided. You may comprise in the "open-path arrangement | positioning form" which is spaced apart to a major axis direction and makes measurement object gas open space which distribute | circulates gas between a light source and an infrared detection part, without using a cylinder (cell).
Further, the method of acquiring the set of weighting factors A and B is not limited to the above, and may be obtained by a predetermined calculation formula, for example.
In addition, when temperature, VH, and VL fall with time, the above-mentioned straight line L1 and the curves L2 and L3 become the up-down direction reverse to FIG.
Further, as the infrared detection element 122, infrared light having a specific wavelength is detected via the infrared wavelength selection filter 110 that absorbs a specific wavelength, but a second infrared wavelength selection that absorbs another second wavelength separately. A second infrared detection element provided with a filter may be disposed. If infrared light having a wavelength that is not absorbed by gas molecules is selected as the second wavelength (for example, 3.9 μm), for example, the light source 121 is deteriorated, or the reflectance of the reflecting mirror 102a is decreased, so that the detection output of the infrared detection element 122 is obtained. This effect can be corrected even if the value decreases.

Using the infrared analysis type gas concentration detection apparatus 1 shown in FIG. 1, the time change of the detection signal ΔV when the ambient temperature and the gas flow rate were changed to cause the change (drift) of VH and VL was measured.
A light bulb 121 is used as the light source 121 of the non-dispersive infrared gas sensor 100, a thermopile is used as the infrared detection element 122, a bandpass filter having a selection wavelength of 4.3 μm is used as the infrared wavelength selection filter 110, the lens barrel 102 is made of aluminum, and a heater 130 The control temperature was about 50 ° C.

FIG. 15 shows the time change of the detection signal ΔV when the ambient temperature is changed to cause changes in VH and VL (thermal drift). The example is based on the ΔV calculation method using the weighted average according to the third embodiment, and the comparative example is based on the ΔV calculation method according to the conventional technique shown in FIG. 17 (shifted to the detection timing of VH and VL). There was a thing). However, V0 in FIG. 17 was replaced with VL. The ambient temperature was measured with the temperature sensor 142.
As is apparent from FIG. 15, in the case of the embodiment in which the first average signal VH ′ and the second average signal VL ′ are predicted and ΔV that is the difference between VH and VL is calculated at the same detection timing, VH and VL Compared to the comparative example with a difference in detection timing, the correct ΔV can be obtained in a relatively short time even if the ambient temperature changes, and the influence of the VH and VL drifts due to the temporal change in the ambient temperature can be corrected quickly. It has been found that it is possible to suppress a decrease in the detection accuracy of the gas concentration accompanying the temporal change in temperature.

FIG. 16 shows the time change of the detection signal ΔV when the flow rate of the measurement target gas G introduced into the introduction port 103 is changed to cause changes (drifts) in VH and VL. When the gas flow rate decreases with time, the ambient temperature increases, and when the gas flow rate increases with time, the ambient temperature tends to decrease.
As can be seen from FIG. 16, in the case of the embodiment in which ΔV, which is the difference between VH and VL, is calculated at the same detection timing, the flow rate of the measurement target gas G compared to the comparative example in which the detection timing of VH and VL is different. The correct ΔV can be obtained in a relatively short time with respect to the change in ambient temperature due to the change, and the effect of drift in VH and VL due to the temporal change in the surrounding gas flow rate is corrected quickly, and the gas flow rate (ambient temperature) It has been found that it is possible to suppress a decrease in the detection accuracy of the gas concentration accompanying the temporal change of.

DESCRIPTION OF SYMBOLS 1 Infrared analysis type gas concentration detection apparatus 50 Gas concentration calculating part 50,61 Light source control part 60 Infrared gas sensor control apparatus 100 Non-dispersion type infrared gas sensor 121 Light source 122 Infrared detection part (infrared detection element)
141 External temperature measurement unit 142 Infrared detection unit temperature measurement unit CH First set light amount CL Second set light amount VH First detection signal VH ′ First average signal VL Second detection signal VL ′ Second average signal TW1, TW3 First cycle Time TW2, TW4 Second cycle time A, B Weighting factor

Claims (8)

A gas sensor control device connected to a gas sensor comprising: a light source that emits infrared rays to a measurement target gas; and an infrared detection unit that detects the infrared rays,
The amount of the infrared light emitted from the light source becomes a first set light amount over a first cycle time, and is different from the first set light amount over a second cycle time, and the predetermined amount without turning off the light source. A light source control unit that performs control to alternately switch to a second set light amount that forms a light amount of value ;
A gas concentration calculation unit that calculates the concentration of the measurement target gas from the detection signal of the infrared detection unit,
The detection signal detected by the infrared detection unit in the first cycle time is a first detection signal, the detection signal detected by the infrared detection unit in the second cycle time is a second detection signal,
The gas concentration calculation unit includes a first average signal obtained by averaging the values of the first detection signals detected at two first cycle times that are temporally continuous, and a first average signal between the two first cycle times. Based on the first information group consisting of the second detection signals detected in two cycle times,
Alternatively, a second average signal obtained by averaging the values of the second detection signals detected at two time periods that are consecutive in time and a first period time between the two second period times are detected. The concentration of the measurement target gas is calculated based on the second information group consisting of the first detection signals that are generated.
Gas sensor control device. The first average signal is a weighted average of the values of the first detection signals respectively detected at the two time periods that are continuous in time.
2. The gas sensor control device according to claim 1, wherein the second average signal is a weighted average of values of second detection signals respectively detected in the two time periods that are continuous in time. The gas sensor control device according to claim 2,
The gas concentration control unit is a gas sensor control device that determines a weighting coefficient used for the weighted average based on an external temperature measured by an external temperature measurement unit provided outside the gas sensor. The gas sensor control device according to claim 2 or 3,
The gas concentration calculation unit is a gas sensor control device that determines a weighting coefficient used for the weighted average based on a temperature of the infrared detection unit measured by an infrared detection unit temperature measurement unit provided in the vicinity of the infrared detection unit. The gas sensor control device according to any one of claims 1 to 4,
The gas sensor control device, wherein the first cycle time and the second cycle time are 2 seconds or less. A gas sensor control device according to any one of claims 1 to 5,
A gas sensor that is connected to the gas sensor control device and includes a light source that emits infrared rays to the measurement target gas, and an infrared detection unit that detects the infrared rays;
Infrared analytical gas concentration detector. The infrared analytical gas concentration detection device according to claim 6,
Furthermore, an infrared analysis type gas concentration detection apparatus provided with an external temperature measurement unit that is provided outside the gas sensor and measures an external temperature of the gas sensor. An infrared analytical gas concentration detection device according to claim 6 or 7,
Furthermore, an infrared analytical gas concentration detection device provided with an infrared detection unit temperature measurement unit that is provided in the vicinity of the infrared detection unit and measures the temperature of the infrared detection unit.