Heat transfer gas sensor system and sensing method

Abstract

To provide a heat transfer gas sensor system and a sensing method having high accuracy and sensitivity.SOLUTION: A heat transfer gas sensor system includes a measurement unit, a control unit, and a calculation unit. The measurement unit includes a sensor unit capable of measuring a resistance value and a heater unit capable of heating the sensor unit. The control unit has a heater control circuit capable of controlling heating and non-heating of the heater unit, and a timing control circuit capable of controlling timing of a control signal of heating and non-heating of the heater unit and an output signal from the sensor unit. The calculation unit acquires a first output signal from the sensor unit when the heater unit is not heating, and corrects a second output signal from the sensor unit when the heater unit is heating, using the first output signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments relate to thermal conduction gas sensor systems and sensing methods. [Background technology]

[0002] A known gas sensor is a thermal conduction type gas sensor that detects gas concentration using two sensors: a detection sensor that detects changes in thermal conductivity while heating with a heater, and an environmental temperature sensor that references the environmental temperature and corrects the detection sensor.

[0003] In such conventional thermal conduction gas sensors, the temperature of the environmental temperature sensor does not match the temperature of the detection sensor, so residues other than those dependent on the gas concentration remain after temperature correction, leading to reduced accuracy and sensitivity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-170161 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a thermal conductivity gas sensor system and sensing method that is highly accurate and sensitive. [Means for solving the problem]

[0006] The embodiments provided by the present invention are as follows.

[0007] A thermal conduction type gas sensor system comprising: a measuring unit having a sensor unit capable of measuring resistance values ​​and a heater unit capable of heating the sensor unit; a control unit having a heater control circuit capable of controlling whether the heater unit is heated or not, and a timing control circuit capable of controlling the timing of a control signal for heating or not heating the heater unit and an output signal from the sensor unit; and a calculation unit that obtains a first output signal from the sensor unit when the heater unit is not heated, and uses the first output signal to correct a second output signal from the sensor unit when the heater unit is heated. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing the configuration of a thermal conduction gas sensor system according to a first embodiment. [Figure 2] 4 is a flowchart illustrating a sensing method according to the first embodiment. [Figure 3] 4 is a timing chart relating to the sensing method according to the first embodiment. [Figure 4] FIG. 10 is a block diagram showing the configuration of a thermal conduction gas sensor system according to a modified example of the first embodiment. [Figure 5] 10 is a flowchart illustrating a sensing method according to a modified example of the first embodiment. [Figure 6] 1A is a cross-sectional view showing the configuration of a thermal conduction gas sensor system according to Example 1. FIG. 1B is a circuit diagram showing the configuration of a thermal conduction gas sensor system according to Example 1. [Figure 7] 10 shows the results of sensing according to the first embodiment. [Figure 8] 10 shows the results of sensing according to the second embodiment. [Figure 9] 10 shows the results of sensing according to Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] A first embodiment will be described below with reference to the drawings. Note that the present invention is not limited to the first embodiment. Identical parts in the drawings are assigned the same numbers, and detailed descriptions thereof will be omitted as appropriate, and different parts will be described. Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be expressed differently depending on the drawing.

[0010] [First embodiment] <Thermal Conductivity Gas Sensor System> FIG. 1 is a schematic diagram of a thermal conduction gas sensor system 1 according to the first embodiment.

[0011] The thermal conduction gas sensor system 1 according to the first embodiment is composed of a measurement unit 10, a control unit 20, and a calculation unit 31.

[0012] The measurement unit 10 includes a sensor unit 11 and a heater unit 12 .

[0013] The sensor unit 11 includes a resistor. The sensor unit 11 is capable of measuring the value of this resistor (resistance value). The obtained resistance value is sent to the calculation unit 31.

[0014] The heater section 12 can heat the sensor section 11. The heater section 12 includes, for example, a micro-heater.

[0015] The control unit 20 includes a timing control circuit 21 and a heater control circuit 22 .

[0016] The timing control circuit 21 issues a control signal to the heater control circuit 22 to control heating and / or non-heating of the heater section 12. The timing control circuit 21 also issues a control signal to the sensor section 11 to control the timing for measuring the output signal obtained from the sensor section 11. In addition to controlling these timings, the timing control circuit 21 also performs controls necessary for measurement, such as synchronizing the time at which measurements are performed.

[0017] The heater control circuit 22 controls whether the heater section 12 is heated or not. The control method of the heater control circuit 22 is not limited to one. For example, the current and voltage of the heater section 12 may be controlled by being turned on and off, or the values ​​of the current and voltage flowing through the heater section 12 may be controlled by PID control.

[0018] The calculation unit 31 acquires a first output signal from the sensor unit 11 when the heater unit 12 is not heating, and acquires a second output signal from the sensor unit 11 when the heater unit 12 is heating. The calculation unit 31 uses the acquired first output signal and second output signal to perform calculations to correct the measurement results.

[0019] Here, it is preferable to obtain each output signal after the output signal obtained from the sensor unit 11 has become "stable." Here, "stable" means that the fluctuation range of the output of the sensor unit 11 is within a predetermined range within a predetermined time, for example, within ±1% of the average value of the output signal of the sensor unit 11.

[0020] Here, the timing for acquiring the first output signal is preferably immediately before the heater unit 12 heats the sensor unit 11. The closer the timing for acquiring the first output signal is to the start of heating, the less the influence of environmental changes on the thermal conduction gas sensor system 1. This reduces the need to consider the influence of environmental changes at the timings when the first and second output signals are measured, resulting in measurement results closer to the true value. Furthermore, acquiring the first output signal immediately before the start of heating allows for a longer time interval between the end of heating by the heater unit 12 and the acquisition timing, enabling measurements with smaller temperature changes and thus improving accuracy. Note that "immediately before" here refers to any point before the heater unit 12 heats up, depending on the measurement system and measurement conditions, when the fluctuation range of the output of the sensor unit 11 is within a predetermined range within a predetermined time, for example, within ±1% of the average value of the output signal of the sensor unit 11. Here, the "predetermined time" refers, for example, to the same time period as the length of time required for measurement during heating. Also, for example, any point in the range indicated as "just before" in FIG. 3 is exemplified.

[0021] The thermal conduction gas sensor system 1 may include a memory unit 32. For example, the memory unit 32 may temporarily store the first signal output and the second signal output, and output them to the calculation unit 31 as needed, or store the calculation results.

[0022] [Sensing method according to the first embodiment] Hereinafter, a measurement method using the thermal conduction gas sensor system according to this embodiment will be described with reference to FIGS.

[0023] (S1, S11) After the temperature of the sensor unit 11 has stabilized without heating, the timing control circuit 21 issues a control signal to the sensor unit 11 to instruct it to measure the resistance value of the sensor unit 11. The obtained value (first output signal) is output to the calculation unit 31.

[0024] (S2~S3) Next, the heater control circuit 22 issues a control signal to the heater section 12 to instruct it to heat up. As the heater section 12 heats up, the temperature of the sensor section 11 also rises. The process waits until the temperature of the sensor section 12 stabilizes.

[0025] (S4, S12) After the temperature of the sensor unit 11 has stabilized under heating conditions, the timing control circuit 21 issues a control signal to the sensor unit 11 to instruct it to measure the resistance value of the sensor unit 11. The obtained value (second output signal) is output to the calculation unit 31.

[0026] (S5, S6) The heater control circuit 22 issues a control signal to the heater section 12 to instruct it not to heat. As the temperature of the heater section 12 drops, the temperature of the sensor section 11 also drops. The system waits until the temperature of the sensor section 11 stabilizes.

[0027] (S13, S14) A calculation is performed to correct the temperature using the values ​​(first output signal, second output signal) obtained in S11 and S12. The calculation result is output to a storage unit 32 or an output unit 33 such as a monitor.

[0028] A series of steps S1 to S14 is regarded as one unit of cycle, and by repeating this cycle, sensing over time becomes possible.

[0029] [Modification of the first embodiment] 4 is a schematic diagram of a thermal conduction gas sensor system 1 according to a modification of the first embodiment. In addition to the components of the first embodiment, this modification includes an environmental temperature sensor unit 13. By further including the environmental temperature sensor unit 13, more accurate sensing is possible.

[0030] In this case, it is preferable that the temperature dependency of the sensor section 11 is lower than the temperature dependency of the environmental temperature sensor section 13. Here, the temperature dependency refers to the ratio of the sensor output voltage fluctuation to the temperature change of the sensor output voltage.

[0031] Because the temperature dependence of the sensor unit 11 is lower than that of the environmental temperature sensor unit 13, the response fluctuation of the sensor unit 13 to temperature changes is reduced, leading to stability of the sensor output, while the change (temperature dependence) of the environmental temperature sensor unit 13 in response to changes in environmental temperature is increased, making it possible to achieve both improved accuracy in environmental temperature monitoring.

[0032] Furthermore, it is preferable that the environmental temperature sensor unit 13 is contained in the same package as the sensor unit 11. By providing them in the same package, the measurement environments for both can be made the same or similar, making it possible to eliminate common mode noise and further reduce the influence of the external environment, thereby enabling more accurate sensing.

[0033] [Sensing method according to a modification of the first embodiment] Since S1 to S6 and S11 to S12 are the same as those in the first embodiment, the explanation will be omitted, and only the points that differ from the first embodiment will be explained with reference to FIG.

[0034] (S15) After the heater control circuit 22 issues a control signal to the heater unit 12 instructing it not to heat, the timing control circuit 21 issues a control signal to the environment temperature sensor unit 13 instructing it to measure the resistance value of the environment temperature sensor unit 13. The obtained value (third output signal) is output to the calculation unit 31.

[0035] (S16, S17) A calculation is performed to correct the temperature using the values ​​(first output signal, second output signal, third output signal) obtained in S11, S12, and S15. The calculation result is output to a storage unit 32 or an output unit 33 such as a monitor. [Example]

[0036] Examples of each embodiment will be described below.

[0037] Example 1 Example 1 according to the first embodiment will be described below. Here, measurements were carried out using the thermal conduction type gas sensor system shown in Fig. 6(A).

[0038] First, the power supply to the heater unit 12 was turned off, and after the temperature of the sensor unit 11 stabilized without heating, the timing control circuit 21 issued a control signal to the sensor unit 11 to instruct it to measure the resistance value of the sensor unit 11, and the resistance value at this time was measured. The obtained value (first output signal) was output to the calculation unit 31. The first output signal obtained at this time is shown as Ex1-1 in FIG. 7.

[0039] Next, the heater control circuit 22 issued a control signal to the heater section 12 instructing it to heat. As the heater section 12 heated, the temperature of the sensor section 11 also rose, and the process waited until the temperature of the sensor section 11 stabilized. After the temperature of the sensor section 11 stabilized, the timing control circuit 21 issued a control signal to the sensor section 11 instructing it to measure the resistance value of the sensor section 11, and the resistance value at this time was measured. The obtained value (second output signal) was output to the calculation section 31. The second signal output obtained at this time is shown as Ex1-2 in Figure 7.

[0040] The temperature correction calculation was performed using the values ​​obtained above (first output signal, second output signal). Specifically, Ex1-1 was subtracted from Ex1-2. The residue at this time is shown in Ex1-3.

[0041] The fluctuation range of the sensor output for residue Ex1-3 was within ±0.3%, which indicates that highly accurate measurements are possible in Example 1, even though only one sensor is provided for measuring temperature.

[0042] Example 2 Example 2, which corresponds to a modification of the first embodiment, is shown. Here, an environmental temperature sensor 13 (not shown in FIG. 6) was added to the thermal conduction gas sensor system of Example 1 (FIG. 6(A)), and measurements were performed. The sensor unit 11 and the environmental temperature sensor 13 constituted a bridge circuit shown in FIG. 6(B).

[0043] The steps up to obtaining the first output signal and the second output signal were carried out in the same manner as in Example 1. The first output signal Ex2-1 and the second output signal Ex2-2 obtained at this time are shown in FIG.

[0044] After obtaining the second output signal, the heater control circuit 22 issued a control signal to the heater unit 12 instructing it to stop heating. Thereafter, the timing control circuit 21 issued a control signal to the ambient temperature sensor unit 13 instructing it to measure the resistance value of the ambient temperature sensor unit 13, and the resistance value at this time was measured. The obtained value (third output signal) was output to the calculation unit 31. The third output signal obtained at this time is shown as Ex2-3 in Figure 8.

[0045] The temperature correction calculation is performed using the values ​​obtained in S11, S12, and S15 (first output signal, second output signal, third output signal). Specifically, the first and third output signals are subtracted from the second output signal. The residue at this time is shown in Ex2-4.

[0046] For residue Ex2-4, the fluctuation range relative to the sensor output was within ±0.01%, which indicates that Example 2 was able to perform measurements with even higher accuracy than Example 1.

[0047] (Comparative Example) A comparative example will be described below. In this comparative example, the same heat conduction type gas sensor system 1 as in Example 2 was used.

[0048] Without performing S1 and S11, the heater control circuit 22 issued a control signal to the heater section 12 instructing it to heat. As the heater section 12 heated, the temperature of the sensor section 11 also rose, and the process waited until the temperature of the sensor section 11 stabilized. After the temperature of the sensor section 11 stabilized, the timing control circuit 21 issued a control signal to the sensor section 11 instructing it to measure the resistance value of the sensor section 11, and the resistance value at this time was measured. The obtained value (second output signal) was output to the calculation section 31. The second signal output obtained at this time is shown as Ref3-2 in Figure 9.

[0049] Next, after obtaining the second output signal, the heater control circuit 22 issued a control signal to the heater unit 12 instructing it to stop heating. Thereafter, the timing control circuit 21 issued a control signal to the ambient temperature sensor unit 13 instructing it to measure the resistance value of the ambient temperature sensor unit 13, and the resistance value at this time was measured. The obtained value (third output signal) was output to the calculation unit 31. The third output signal obtained at this time is shown as Ref3-3 in Figure 9.

[0050] The temperature correction calculation was performed using the values ​​obtained above (second output signal, third output signal). Specifically, Ref3-3 was subtracted from Ref3-2. The residue at this time is shown as Ref3-4.

[0051] Residue Ref3-4 did not stabilize over time, and the fluctuation range of the sensor output did not fall within the range of ±1%. This indicates that the comparative example is a thermal conduction type gas sensor system with lower accuracy than examples 1 and 2.

[0052] The embodiment may include the following configuration.

[0053] [Configuration 1] a sensor unit capable of measuring a resistance value; a heater unit capable of heating the sensor unit; a measuring unit having a heater control circuit capable of controlling heating and non-heating of the heater unit; a timing control circuit capable of controlling the timing of a control signal for heating / non-heating of the heater unit and an output signal from the sensor unit; a control unit having a calculation unit that acquires a first output signal from the sensor unit when the heater unit is not heated, and corrects a second output signal from the sensor unit when the heater unit is heated, using the first output signal; A thermal conduction type gas sensor system having:

[0054] [Configuration 2] 2. The thermal conduction type gas sensor system according to configuration 1, wherein the timing at which the first signal is acquired is immediately before the heater unit heats the sensor unit.

[0055] [Configuration 3] the calculation unit acquiring a first output signal of the sensor unit immediately before heating the heater unit; After the acquisition is completed, the heater control circuit heats the heater unit, and the timing control circuit performs a first waiting process until the temperature of the sensor unit becomes stable; After the first waiting period is completed, the calculation unit acquires a second output signal of the sensor unit; after the acquisition of the second output signal is completed, the heater control circuit stops heating the heater, and the timing control circuit performs a second waiting step until the temperature is stabilized; A thermal conduction type gas sensor system that repeatedly executes a cycle in which each step of After the second waiting in the previous cycle is performed, the first signal output of the first sensor unit in the subsequent cycle is acquired. 3. The thermal conduction type gas sensor system according to configuration 1 or 2.

[0056] [Configuration 4] 4. The thermal conduction type gas sensor system according to any one of configurations 1 to 3, further comprising an environmental temperature sensor.

[0057] [Configuration 5] 5. The thermal conduction type gas sensor system according to configuration 4, wherein the environmental temperature sensor is included in the same package as the sensor unit.

[0058] [Configuration 6] a sensor unit capable of measuring a resistance value; a heater unit capable of heating the sensor unit; a measuring unit having a heater control circuit capable of controlling heating and non-heating of the heater unit; a timing control circuit capable of controlling the timing of a control signal for heating / non-heating of the heater unit and an output signal from the sensor unit; a control unit having a calculation unit that acquires a first output signal from the sensor unit when the heater unit is not heated, and corrects a second output signal from the sensor unit when the heater unit is heated, using the first output signal; A sensing method using a thermal conduction type gas sensor system having the following: the calculation unit acquiring a first output signal of the sensor unit immediately before heating the heater unit; After the acquisition is completed, the heater control circuit heats the heater unit, and the timing control circuit performs a first waiting process until the temperature of the sensor unit becomes stable; after the first waiting period has ended, the calculation unit acquires a second output signal of the sensor unit; after the acquisition of the second output signal is completed, the heater control circuit stops heating the heater unit, and the timing control circuit performs a second waiting process until the temperature is stabilized; A sensing method for a thermal conduction type gas sensor system that repeatedly executes a cycle in which each step of the above is one unit.

[0059] According to at least one of the embodiments of the acid gas absorbent, the acid gas removal method, and the acid gas removal system described above, it is possible to realize an acid gas absorption system that produces little waste and requires less energy for regeneration.

[0060] As described above, several embodiments have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various combinations, omissions, substitutions, modifications, etc. are possible without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0061] 1. Thermal conductivity gas sensor system 10...Measuring section 10 11...Sensor section 12...Heater section 13...Environmental temperature sensor 20...Control unit 21...Timing control circuit 22...Heater control circuit 31...Arithmetic section 32...Storage section 33...Output section

Claims

1. a sensor unit capable of measuring a resistance value; a heater unit capable of heating the sensor unit; a measuring unit having a heater control circuit capable of controlling heating and non-heating of the heater unit; a timing control circuit capable of controlling the timing of a control signal for heating / non-heating of the heater unit and an output signal from the sensor unit; a control unit having a calculation unit that acquires a first output signal from the sensor unit when the heater unit is not heated, and corrects a second output signal from the sensor unit when the heater unit is heated, using the first output signal; A thermal conduction type gas sensor system having:

2. 2. The thermal conduction type gas sensor system according to claim 1, wherein the timing at which the first signal is acquired is immediately before the heater unit heats the sensor unit.

3. the calculation unit acquiring a first output signal of the sensor unit immediately before heating the heater unit; After the acquisition is completed, the heater control circuit heats the heater unit, and the timing control circuit performs a first waiting process until the temperature of the sensor unit becomes stable; after the first waiting period is completed, the calculation unit acquires a second output signal of the sensor unit; after the acquisition of the second output signal is completed, the heater control circuit stops heating the heater, and the timing control circuit performs a second waiting step until the temperature is stabilized; A thermal conduction type gas sensor system that repeatedly executes a cycle in which each step of After the second waiting in the previous cycle is performed, the first signal output of the first sensor unit in the subsequent cycle is acquired.

3. The thermal conduction type gas sensor system according to claim 1.

4. 3. The thermal conduction type gas sensor system according to claim 1, further comprising an environmental temperature sensor.

5. 5. The thermal conduction type gas sensor system according to claim 4, wherein the environmental temperature sensor is included in the same package as the sensor unit.

6. a sensor unit capable of measuring a resistance value; a heater unit capable of heating the sensor unit; a measuring unit having a heater control circuit capable of controlling heating and non-heating of the heater unit; a timing control circuit capable of controlling the timing of a control signal for heating / non-heating of the heater unit and an output signal from the sensor unit; a control unit having a calculation unit that acquires a first output signal from the sensor unit when the heater unit is not heated, and corrects a second output signal from the sensor unit when the heater unit is heated, using the first output signal; A sensing method using a thermal conduction type gas sensor system having the following: the calculation unit acquiring a first output signal of the sensor unit immediately before heating the heater unit; after the acquisition is completed, the heater control circuit heats the heater unit, and the timing control circuit performs a first waiting process until the temperature of the sensor unit becomes stable; after the first waiting period has ended, the calculation unit acquires a second output signal of the sensor unit; after the acquisition of the second output signal is completed, the heater control circuit stops heating the heater unit, and the timing control circuit performs a second waiting process until the temperature is stabilized; A sensing method for a thermal conduction type gas sensor system that repeatedly executes a cycle in which each step of the above is one unit.

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