WO2019065127A1 - Capteur de gaz - Google Patents

Capteur de gaz Download PDF

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Publication number
WO2019065127A1
WO2019065127A1 PCT/JP2018/032832 JP2018032832W WO2019065127A1 WO 2019065127 A1 WO2019065127 A1 WO 2019065127A1 JP 2018032832 W JP2018032832 W JP 2018032832W WO 2019065127 A1 WO2019065127 A1 WO 2019065127A1
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WO
WIPO (PCT)
Prior art keywords
thermistor
gas
sensitivity
concentration
heater
Prior art date
Application number
PCT/JP2018/032832
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English (en)
Japanese (ja)
Inventor
海田　佳生
裕 松尾
Original Assignee
Tdk株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2018129769A external-priority patent/JP7070175B2/ja
Application filed by Tdk株式会社 filed Critical Tdk株式会社
Priority to US16/649,558 priority Critical patent/US11499932B2/en
Priority to EP18863664.1A priority patent/EP3690432A4/fr
Priority to CN201880062693.3A priority patent/CN111164419B/zh
Publication of WO2019065127A1 publication Critical patent/WO2019065127A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/14—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature
    • G01N27/18—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature caused by changes in the thermal conductivity of a surrounding material to be tested

Definitions

  • the present invention relates to a gas sensor for detecting a gas contained in an atmosphere, and more particularly to a gas sensor capable of canceling the influence of a gas different from a gas to be detected.
  • Patent Document 1 an oxygen concentration measurement unit and a humidity measurement unit are provided separately from the hydrogen sensor unit that detects hydrogen gas to be detected, and a signal obtained from the hydrogen sensor unit is corrected based on the oxygen concentration and humidity. A method is disclosed.
  • an object of the present invention is to provide a gas sensor capable of highly accurately eliminating the influence of a gas different from the gas to be detected without performing arithmetic processing.
  • the resistance value changes at a first sensitivity according to the concentration of the first gas, and the resistance value changes at a second sensitivity according to the concentration of the second gas.
  • the resistance value changes at a third sensitivity which is connected in series to the first thermistor and which is lower than the first sensitivity in accordance with the concentration of the first gas;
  • a second thermistor whose resistance value changes with a fourth sensitivity different from the sensitivity of 2, and a first thermistor connected in parallel to the first or second thermistor according to the concentration of the second gas
  • a correction resistor that cancels the potential change of the connection point of the second thermistor.
  • the first and second thermistors are connected in series, and the potential change at the connection point of the first thermistor and the second thermistor according to the concentration of the second gas is canceled by the correction resistor.
  • the influence of the second gas can be easily and accurately removed, and the concentration of the first gas can be accurately calculated, without performing arithmetic processing.
  • the first thermistor is heated to a first temperature by the first heater, and the second thermistor is heated to a second temperature different from the first temperature by the second heater. It does not matter. According to this, for example, the first thermistor and the second thermistor can have the same configuration.
  • the fourth sensitivity may be higher than the second sensitivity, and the correction resistor may be connected in parallel to the second thermistor. According to this, since the fourth sensitivity is effectively reduced, it is possible to match the second sensitivity.
  • the resistance of the second thermistor heated to the second temperature is Rd2
  • the gas sensor according to the present invention may further comprise a third thermistor disposed between the first thermistor and the second thermistor. According to this, it is possible to reduce the thermal interference because the distance between the first thermistor and the second thermistor increases.
  • the gas sensor according to the present invention changes the first control voltage supplied to the first heater and the second control voltage supplied to the second heater according to the temperature signal supplied from the third thermistor. May be further provided. According to this, the heating temperature by the first and second heaters can be set as the designed temperature regardless of the current environmental temperature.
  • a gas sensor receives a common control voltage by receiving a common control voltage, a first heater for heating a first thermistor to a first temperature, a second heater for heating a second thermistor to a second temperature, and the like. And a second amplifier for receiving the common control voltage and applying a second control voltage to the second heater. Absent. According to this, it is possible to reduce the measurement error due to the fluctuation of the power supply potential.
  • the third sensitivity may be 1/10 or less of the first sensitivity. According to this, it is possible to calculate the concentration of the first gas more accurately.
  • the first thermistor and the second thermistor may be housed in the same package. According to this, since the measurement conditions of the first thermistor and the second thermistor coincide with each other, the influence of the second gas can be more accurately removed.
  • the first and second thermistors may constitute a heat conduction sensor.
  • the detection error caused by a gas different from the gas to be detected it is possible to reduce the detection error caused by a gas different from the gas to be detected. Become.
  • the first gas may be CO 2 gas
  • the second gas may be water vapor. According to this, it becomes possible to eliminate the influence of humidity in the concentration detection of CO 2 gas.
  • the influence of a gas different from the gas to be detected can be eliminated with high accuracy without performing arithmetic processing. This makes it possible to measure the concentration of the gas to be detected with high accuracy.
  • FIG. 1 is a circuit diagram showing a configuration of a gas sensor 10A according to a first embodiment of the present invention.
  • FIG. 2 is a top view for explaining the configuration of the sensor unit S.
  • FIG. 3 is a cross-sectional view taken along the line AA shown in FIG.
  • FIG. 4 is a graph showing the relationship between the heating temperature of the thermistors Rd1 and Rd2 and the sensitivity.
  • FIG. 5 is a timing chart showing an example of waveforms of control voltages Vmh1 and Vmh2.
  • FIG. 6 is a graph showing measured values, where (a) shows changes in CO 2 gas and humidity, and (b) shows changes in detection signal Vout1.
  • FIG. 1 is a circuit diagram showing a configuration of a gas sensor 10A according to a first embodiment of the present invention.
  • FIG. 2 is a top view for explaining the configuration of the sensor unit S.
  • FIG. 3 is a cross-sectional view taken along the line AA shown in FIG.
  • FIG. 7 is a circuit diagram showing a configuration of a gas sensor 10B according to a second embodiment of the present invention.
  • FIG. 8 is a circuit diagram showing a configuration of a gas sensor 10C according to a third embodiment of the present invention.
  • FIG. 9 is a circuit diagram showing a configuration of a gas sensor 10D according to a fourth embodiment of the present invention.
  • FIG. 10 is a top view for explaining the configuration of the sensor unit S in the fourth embodiment.
  • FIG. 11 is a cross-sectional view taken along a line BB shown in FIG.
  • FIG. 12 is a timing chart for explaining the timing at which the temperature signal Vout2 is sampled.
  • FIG. 13 is a graph showing the relationship between the environmental temperature and the control voltages Vmh1 and Vmh2.
  • FIG. 1 is a circuit diagram showing a configuration of a gas sensor 10A according to a first embodiment of the present invention.
  • the gas sensor 10A includes a sensor unit S and a signal processing circuit 20.
  • the gas sensor 10A according to the present embodiment detects the concentration of CO 2 gas in the atmosphere, and as described later, the hardware cancels the measurement error caused by the humidity. It is possible.
  • the gas to be detected may be referred to as “first gas”, and the gas that becomes noise may be referred to as “second gas”.
  • the first gas is CO 2 gas and the second gas is water vapor.
  • the sensor unit S is a heat conduction type gas sensor for detecting the concentration of CO 2 gas which is a detection target gas, and has a first sensor unit S1 and a second sensor unit S2.
  • the first sensor unit S1 includes a first thermistor Rd1 and a first heater resistor MH1 for heating the same.
  • the second sensor unit S2 includes a second thermistor Rd2 and a second heater resistor MH2 for heating the same.
  • the first and second thermistors Rd1 and Rd2 are connected in series between a line to which the power supply potential Vcc is supplied and a line to which the ground potential GND is supplied.
  • the first and second thermistors Rd1 and Rd2 are made of, for example, a material having a negative temperature coefficient of resistance, such as a composite metal oxide, amorphous silicon, polysilicon, or germanium.
  • the thermistors Rd1 and Rd2 both detect the concentration of the CO 2 gas, but their operating temperatures are different from each other as described later.
  • the first thermistor Rd1 is heated by the first heater resistor MH1.
  • the heating temperature of the first thermistor Rd1 by the first heater resistance MH1 is 150 ° C., for example. If CO 2 gas is present in the measurement atmosphere with the first thermistor Rd 1 heated, the heat dissipation characteristics of the first thermistor Rd 1 change according to the concentration. Such a change appears as a change in the resistance value of the first thermistor Rd1.
  • the resistance value of the first thermistor Rd1 changes at a first sensitivity according to the concentration of the CO 2 gas.
  • the first sensitivity is a sensitivity that can sufficiently change the potential of the detection signal Vout1 that appears at the connection point of the first thermistor Rd1 and the second thermistor Rd2.
  • the heat radiation characteristics of the first thermistor Rd1 change according to the concentration.
  • the heating temperature of the first thermistor Rd1 is 150 ° C.
  • the resistance value of the first thermistor Rd1 changes at a second sensitivity depending on the humidity.
  • the second thermistor Rd2 is heated by the second heater resistor MH2.
  • the heating temperature of the second thermistor Rd2 by the second heater resistance MH2 is 300 ° C., for example. Even if the CO 2 gas is present in the measurement atmosphere with the second thermistor Rd 2 heated, the resistance value of the second thermistor Rd 2 hardly changes. This is because, when the heating temperature of the second thermistor Rd2 is 300 ° C., the resistance value of the second thermistor Rd2 changes at a third sensitivity according to the concentration of the CO 2 gas, but the third sensitivity is This is because it is significantly lower than the first sensitivity, preferably 1/10 or less of the first sensitivity, and more preferably substantially zero. For this reason, even if the concentration of CO 2 gas changes, the resistance value of the second thermistor Rd 2 hardly changes.
  • the heat dissipation characteristics of the second thermistor Rd2 change according to the concentration.
  • the heating temperature of the second thermistor Rd2 is 300 ° C.
  • the resistance value of the second thermistor Rd2 changes at the fourth sensitivity according to the humidity.
  • the fourth sensitivity is greater than the second sensitivity described above.
  • the gas sensor 10A includes the correction resistor R1 connected in parallel to the second thermistor Rd2. As described later, the correction resistor R1 is provided to cancel the difference between the sensitivity (the second sensitivity) of the first thermistor Rd1 to the humidity and the sensitivity (the fourth sensitivity) of the second thermistor Rd2 to the humidity. .
  • the first thermistor Rd1 and the second thermistor Rd2 are connected in series, and the detection signal Vout1 is output from the connection point.
  • the detection signal Vout1 is input to the signal processing circuit 20.
  • the signal processing circuit 20 includes differential amplifiers 21 to 23, an AD converter (ADC) 24, a DA converter (DAC) 25, a control unit 26, and resistors R2 to R4.
  • the differential amplifier 21 is a circuit that compares the detection signal Vout1 with the reference voltage Vref and amplifies the difference.
  • the gain of the differential amplifier 21 is arbitrarily adjusted by the resistors R2 to R4.
  • the amplified signal Vamp output from the differential amplifier 21 is input to the AD converter 24.
  • the AD converter 24 converts the amplified signal Vamp into a digital signal and supplies the value to the control unit 26.
  • the DA converter 25 converts the reference signal supplied from the control unit 26 into an analog signal to generate the reference voltage Vref, and controls the control voltages Vmh1 and Vmh2 supplied to the first and second heater resistors MH1 and MH2. Play a role in generating.
  • the control voltage Vmh1 is applied to the first heater resistor MH1 via the differential amplifier 22 which is a voltage follower.
  • the control voltage Vmh2 is applied to the second heater resistor MH2 via the differential amplifier 23, which is a voltage follower.
  • FIG. 2 is a top view for explaining the configuration of the sensor unit S.
  • FIG. 3 is a cross-sectional view taken along the line AA shown in FIG.
  • the drawings are schematic, and for convenience of explanation, the relationship between thickness and planar dimensions, the ratio of thickness between devices, etc. are different from the actual structure within the range where the effects of the present embodiment can be obtained. It does not matter.
  • the sensor unit S is a heat conduction type gas sensor that detects the gas concentration based on the change of the heat release characteristic according to the concentration of the CO 2 gas, and as shown in FIGS. 2 and 3, the two sensor units S1 and S2 And a ceramic package 51 for housing the sensor units S1 and S2.
  • the ceramic package 51 is a box-shaped case having an open top, and a lid 52 is provided on the top.
  • the lid 52 has a plurality of air vents 53 so that the CO 2 gas in the atmosphere can flow into the ceramic package 51.
  • the lid 52 is omitted in FIG. 2 in consideration of the legibility of the drawing.
  • the first sensor unit S1 includes a substrate 31, insulating films 32 and 33 respectively formed on the lower and upper surfaces of the substrate 31, a first heater resistor MH1 provided on the insulating film 33, and a first heater A heater protection film 34 covering the resistance MH1, a first thermistor Rd1 and a thermistor electrode 35 provided on the heater protection film 34, and a thermistor protection film 36 covering the first thermistor Rd1 and the thermistor electrode 35 are provided.
  • the substrate 31 is not particularly limited as long as it has appropriate mechanical strength and is a material suitable for micro processing such as etching, and a silicon single crystal substrate, a sapphire single crystal substrate, a ceramic substrate, a quartz substrate And glass substrates can be used.
  • the substrate 31 is provided with a cavity 31a at a position overlapping with the first heater resistor MH1 in plan view in order to suppress heat conducted to the substrate 31 by the first heater resistor MH1.
  • the portion from which the substrate 31 is removed by the cavity 31a is called a membrane. If the membrane is configured, the heat capacity is reduced by the amount of thinning of the substrate 31, so heating can be performed with less power consumption.
  • the insulating films 32 and 33 are made of an insulating material such as silicon oxide or silicon nitride.
  • a film formation method such as a thermal oxidation method or a CVD (Chemical Vapor Deposition) method may be used.
  • the film thickness of the insulating films 32 and 33 is not particularly limited as long as the insulating property is secured, and may be, for example, about 0.1 to 1.0 ⁇ m.
  • the insulating film 33 is also used as an etching stop layer when forming the cavity 31 a in the substrate 31, the film thickness may be suitable for achieving the function.
  • the first heater resistance MH1 is made of a conductive material whose resistivity changes with temperature, and made of a material having a relatively high melting point, for example, molybdenum (Mo), platinum (Pt), gold (Au), tungsten (W), tantalum (Ta), palladium (Pd), iridium (Ir), an alloy containing any two or more of these, and the like are preferable.
  • Mo molybdenum
  • platinum (Pt) gold
  • Au gold
  • W tungsten
  • Ta tantalum
  • Ir iridium
  • an alloy containing any two or more of these, and the like are preferable.
  • it is preferable that it is a conductive material capable of highly accurate dry etching such as ion milling, and in particular, platinum (Pt) having high corrosion resistance is more preferable as a main component.
  • an adhesion layer such as titanium (Ti) on a base of Pt.
  • a heater protection film 34 is formed on the first heater resistance MH1.
  • the heater protective film 34 it is desirable to use the same material as the insulating film 33. Since the first heater resistance MH1 repeatedly produces a severe thermal change, rising from normal temperature to 150 ° C. and decreasing again to normal temperature, the insulating film 33 and the heater protective film 34 are also strongly thermally stressed. If it receives continuously, it will lead to destruction such as delamination and a crack. However, if the insulating film 33 and the heater protective film 34 are made of the same material, the material properties of the two are the same, and the adhesion is strong, so that delamination occurs as compared with the case where different materials are used. It becomes difficult to produce destruction such as cracks.
  • the film may be formed by a method such as a thermal oxidation method or a CVD method.
  • the film thickness of the heater protective film 34 is not particularly limited as long as the insulation with the first thermistor Rd1 and the thermistor electrode 35 is ensured, and may be, for example, about 0.1 to 3.0 ⁇ m.
  • the first thermistor Rd1 is made of a material having a negative temperature coefficient of resistance, such as a composite metal oxide, amorphous silicon, polysilicon, or germanium, and can be formed using a thin film process such as sputtering or CVD.
  • the film thickness of the first thermistor Rd1 may be adjusted according to the target resistance value. For example, if the resistance value (R25) at room temperature is set to about 2 M ⁇ using a MnNiCo-based oxide, a pair Although depending on the distance between the thermistor electrodes 35, the film thickness may be set to about 0.2 to 1 ⁇ m.
  • the reason why a thermistor is used as the temperature sensitive resistance element is that a large detection sensitivity can be obtained because the temperature coefficient of resistance is larger than that of a platinum temperature sensor or the like.
  • the thin film structure makes it possible to efficiently detect the heat generation of the first heater resistor MH1.
  • the thermistor electrode 35 is a pair of electrodes having a predetermined distance, and a first thermistor Rd1 is provided between the pair of thermistor electrodes 35. Thus, the resistance value between the pair of thermistor electrodes 35 is determined by the resistance value of the first thermistor Rd1.
  • the material of the thermistor electrode 35 is a conductive substance that can withstand processes such as the film forming process and the heat treatment process of the first thermistor Rd1, and is a material having a relatively high melting point, such as molybdenum (Mo) or platinum (Pt). And the like, gold (Au), tungsten (W), tantalum (Ta), palladium (Pd), iridium (Ir), and an alloy containing any two or more of them are preferable.
  • the first thermistor Rd1 and the thermistor electrode 35 are covered with a thermistor protective film 36.
  • a thermistor protective film 36 When the first thermistor Rd1 is brought into contact with a material having reducibility to bring it into a high temperature state, oxygen is taken from the thermistor to cause reduction, which affects the thermistor characteristics.
  • the material of the thermistor protective film 36 be an insulating oxide film having no reducibility, such as a silicon oxide film.
  • both ends of the first heater resistor MH1 are connected to electrode pads 37a and 37b provided on the surface of the thermistor protective film 36, respectively. Further, both ends of the thermistor electrode 35 are respectively connected to electrode pads 37 c and 37 d provided on the surface of the thermistor protective film 36.
  • the electrode pads 37 a to 37 d are connected to the package electrode 54 provided on the ceramic package 51 via the bonding wire 55.
  • the package electrode 54 is connected to the signal processing circuit 20 shown in FIG. 1 through an external terminal 56 provided on the back surface of the ceramic package 51.
  • the first sensor unit S1 has a configuration in which the first heater resistor MH1 and the first thermistor Rd1 are stacked on the substrate 31, the heat generated by the first heater resistor MH1 is generated. Efficiently transmit to the first thermistor Rd1.
  • the second sensor unit S2 includes a substrate 41, insulating films 42 and 43 respectively formed on the lower and upper surfaces of the substrate 41, a second heater resistor MH2 provided on the insulating film 43, and a second sensor unit S2.
  • the substrate 41 is made of the same material as the substrate 31 used for the first sensor unit S1, and has the same configuration. That is, the cavity 41a is provided at a position overlapping with the second heater resistance MH2 in plan view, thereby suppressing the conduction of heat by the second heater resistance MH2 to the substrate 41.
  • the materials of the insulating films 42 and 43 are the same as those of the insulating films 32 and 33, and an insulating material such as silicon oxide or silicon nitride is used.
  • the thickness of the insulating films 42 and 43 is the same as that of the insulating films 32 and 33.
  • the first heater resistance MH1 used for the first sensor unit S1, the heater protective film 34, the first thermistor Rd1, the thermistor electrode 35, and the thermistor protection film 36 have the same configuration.
  • Both ends of the second heater resistance MH2 are connected to electrode pads 47a and 47b provided on the surface of the thermistor protective film 46, respectively.
  • both ends of the thermistor electrode 45 are respectively connected to electrode pads 47 c and 47 d provided on the surface of the thermistor protective film 46.
  • the electrode pads 47 a to 47 d are connected to the package electrode 54 provided on the ceramic package 51 via the bonding wire 55.
  • a large number of sensor units S1 and S2 each having the above configuration are simultaneously manufactured in a wafer state, separated into pieces by dicing, and fixed to the ceramic package 51 using a die paste (not shown). Thereafter, the electrode pads 37a to 37d and 47a to 47d and the corresponding package electrodes 54 are connected by bonding wires 55 using a wire bonding apparatus.
  • a metal having a low resistance such as Au, Al or Cu, is preferable.
  • the lid 52 having the vent 53 with the outside air is fixed to the ceramic package 51 using an adhesive resin (not shown) or the like.
  • an adhesive resin (not shown) or the like.
  • the sensor unit S completed in this manner is connected to the signal processing circuit 20 and the power supply via the external terminal 56.
  • the correction resistor R1 is built in the signal processing circuit 20, housed in the ceramic package 51, or provided on a circuit board on which the signal processing circuit 20 is mounted.
  • the gas sensor 10A according to this embodiment, the CO 2 gas thermal conductivity of utilizing the point that differs significantly from the thermal conductivity of the air, the thermistor according to the concentration of CO 2 gas Rd1, Rd2 detection signal a change in the heat dissipation characteristics of Vout1 It is taken out as.
  • the thermal conductivity of the measurement atmosphere changes not only with the concentration of CO 2 gas but also with humidity, that is, the concentration of water vapor, so the influence of humidity causes a measurement error. Therefore, the gas sensor 10A according to the present embodiment adjusts the resistance value of the correction resistor R1 to the humidity so that the error component due to the humidity of the first thermistor Rd1 and the error component due to the humidity of the second thermistor Rd2 coincide. Cancel the change of the detection signal Vout1 based on the
  • FIG. 4 is a graph showing the relationship between the heating temperature of the thermistors Rd1 and Rd2 and the sensitivity.
  • the gas sensor 10A sufficiently secures the sensitivity (first sensitivity) to the concentration of the CO 2 gas by heating the first thermistor Rd1 to 150 ° C.
  • the sensitivity (third sensitivity) to the concentration of CO 2 gas is made almost zero by heating the thermistor Rd 2 to 300 ° C. Since the first thermistor Rd1 and the second thermistor Rd2 are connected in series, the level of the detection signal Vout1 indicates the concentration of CO 2 gas if there is no influence of humidity.
  • the sensitivity to humidity when the heating temperature of the first thermistor Rd1 is 150 ° C. (second sensitivity) and the sensitivity to humidity when the heating temperature of the second thermistor Rd2 is 300 ° C. (fourth The sensitivities are different from one another. Specifically, the fourth sensitivity is about 200 ⁇ V /% RH, while the second sensitivity is about 120 ⁇ V /% RH. Therefore, the influence of humidity is reflected on the detection signal Vout1 simply by connecting the first thermistor Rd1 and the second thermistor Rd2 in series.
  • the correction resistor R1 is connected in parallel to the second thermistor Rd2 so that the change of the detection signal Vout1 according to the humidity is cancelled.
  • the second sensitivity is a
  • the fourth sensitivity is b
  • the resistance of the second thermistor Rd2 heated to 300 ° C. is Rd2
  • the level of the detection signal Vout1 is determined by the concentration of the CO 2 gas.
  • FIG. 5 is a timing chart showing an example of waveforms of control voltages Vmh1 and Vmh2.
  • the control voltage Vmh1 and the control voltage Vmh2 are simultaneously brought to active levels to simultaneously heat the first heater resistance MH1 and the second heater resistance MH2. Then, if the detection signal Vout1 is sampled at the timing when the control voltages Vmh1 and Vmh2 are activated, the concentration of the CO 2 gas can be measured without performing arithmetic processing for canceling the influence of humidity.
  • FIG. 6 is a graph showing measured values, where (a) shows changes in CO 2 gas and humidity, and (b) shows changes in detection signal Vout1.
  • the level of the detection signal Vout1 largely changes due to the humidity
  • the influence of the humidity from the detection signal Vout1 is almost the same. It can be seen that it has been completely canceled.
  • the two thermistors Rd1 and Rd2 having different heating temperatures are connected in series, and the correction resistor R1 is connected in parallel to the second thermistor Rd2.
  • the level of the detection signal Vout1 appearing at the connection point of the first and second thermistors Rd1 and Rd2 accurately represents the concentration of CO 2 gas without being affected by humidity. Therefore, it is possible to immediately measure the concentration of CO 2 gas without performing arithmetic processing for canceling the influence of humidity.
  • FIG. 7 is a circuit diagram showing a configuration of a gas sensor 10B according to a second embodiment of the present invention.
  • the common control voltage Vmh is commonly supplied to the differential amplifiers 22 and 23, and the differential amplifier 23 is not connected in voltage follower, and the resistors R5 to R5 are connected. It differs from the gas sensor 10A according to the first embodiment shown in FIG. 1 in that the gain is adjusted using R7.
  • the other configuration is the same as that of the gas sensor 10A according to the first embodiment, and therefore the same components are denoted by the same reference numerals, and the redundant description will be omitted.
  • the resistors R5 to R7 are elements for adjusting the gain of the differential amplifier 23.
  • Vmh2 2 ⁇ Vmh1 It can be done. That is, it becomes possible to generate two different control voltages Vmh1 and Vmh2 using the common control voltage Vmh.
  • FIG. 8 is a circuit diagram showing a configuration of a gas sensor 10C according to a third embodiment of the present invention.
  • the gas sensor 10C according to the present embodiment is different from the gas sensor 10B according to the second embodiment shown in FIG. 7 in that the correction resistor R1 is connected in parallel to the first thermistor Rd1. It is different. Since the other configuration is the same as that of the gas sensor 10B according to the second embodiment, the same elements will be denoted by the same reference signs, and redundant description will be omitted.
  • the correction resistor R1 may be connected in parallel to the first thermistor Rd1.
  • FIG. 9 is a circuit diagram showing a configuration of a gas sensor 10D according to a fourth embodiment of the present invention.
  • the gas sensor 10D according to the present embodiment is the first embodiment shown in FIG. 1 in that a third sensor unit S3 and a resistor R8, which are temperature sensors, are added to the sensor unit S.
  • the third sensor unit S3 includes a third thermistor Rd3.
  • the third thermistor Rd3 and a resistor R8 are connected in series between the line to which the power supply potential Vcc is supplied and the line to which the ground potential GND is supplied. ing.
  • a temperature signal Vout2 is output from the connection point of the third thermistor Rd3 and the resistor R8.
  • the temperature signal Vout2 is supplied to the AD converter 24.
  • the other circuit configuration is the same as that of the gas sensor 10A according to the first embodiment, and therefore the same components are denoted by the same reference numerals and redundant description will be omitted.
  • FIG. 10 is a top view for explaining the configuration of the sensor unit S in the present embodiment.
  • 11 is a cross-sectional view taken along the line BB shown in FIG.
  • the drawings are schematic, and for convenience of explanation, the relationship between thickness and planar dimensions, the ratio of thickness between devices, etc. are different from the actual structure within the range where the effects of the present embodiment can be obtained. It does not matter.
  • a third sensor unit S3 is disposed between the first sensor unit S1 and the second sensor unit S2.
  • three sensor units S1 to S3 are integrated on a single substrate 61.
  • the substrate 61 is formed with three cavities 61a to 61c corresponding to the three sensor units S1 to S3.
  • the substrate 61 includes insulating films 62 and 63, a heater protection film 64, and a third thermistor Rd3 and a thermistor electrode 65 provided on the heater protection film 64 at a position overlapping the cavity 61c, and first thermistors Rd1 to Rd3. And a thermistor protective film 66 covering the thermistor electrodes 35, 45 and 65.
  • both ends of the thermistor electrode 65 constituting the third sensor unit S3 are connected to electrode pads 67a and 67b provided on the surface of the thermistor protective film 66, respectively.
  • the electrode pads 67 a and 67 b are connected to the package electrode 54 provided on the ceramic package 51 via the bonding wire 55.
  • the other basic configuration is the same as the configuration shown in FIG. 2 and FIG. 3, so the same components are denoted by the same reference numerals and redundant description will be omitted.
  • the third sensor unit S3 which is a temperature sensor, can be used without increasing the number of parts. It can be added.
  • the third sensor unit S3 by arranging the third sensor unit S3 at the center, the distance between the first sensor unit S1 and the second sensor unit S2 can be separated, so that mutual thermal interference can be reduced. That is, since the first sensor unit S1 and the second sensor unit S2 have different heating temperatures and are simultaneously heated, thermal interference may occur if the distance between the two is short.
  • the third sensor unit S3 is disposed between the first sensor unit S1 and the second sensor unit S2, the first sensor unit S1 and the second sensor unit S1 are disposed. The thermal interference during S2 is reduced and more accurate measurement is possible.
  • FIG. 12 is a timing chart for explaining the timing at which the temperature signal Vout2 is sampled.
  • the control voltage Vmh1 and the control voltage Vmh2 are simultaneously set to the active level, so that the first heater resistance MH1 and the second heater resistance MH2 are simultaneously heated.
  • the detection signal Vout1 is sampled at the timing when the control voltages Vmh1 and Vmh2 are activated, and the temperature signal Vout2 is sampled at the timing before the control voltages Vmh1 and Vmh2 are activated.
  • the third sensor unit S3 without being affected by the heating by the first and second heater resistances MH1 and MH2.
  • the temperature signal Vout2 is supplied to the AD converter 24 shown in FIG.
  • the temperature signal Vout2 supplied to the AD converter 24 is converted into a digital signal and supplied to the control unit 26.
  • FIG. 13 is a graph showing the relationship between the environmental temperature and the control voltages Vmh1 and Vmh2.
  • the control unit 26 corrects the control voltages Vmh1 and Vmh2 so that the levels of the control voltages Vmh1 and Vmh2 decrease as the environmental temperature rises.
  • first and second heater resistances MH1 and MH2 are obtained regardless of the current environmental temperature.
  • the heating temperature by can be made the designed temperature.
  • the control voltages Vmh1 and Vmh2 are corrected based on the temperature signal Vout2, but also between the first sensor unit S1 and the second sensor unit S2. Since three sensor units S3 are disposed, the thermal interference between the first sensor unit S1 and the second sensor unit S2 is reduced. This makes it possible to measure the concentration of CO 2 gas more accurately.
  • the third sensor unit S3 is disposed on the same chip as the first sensor unit S1 and the second sensor unit S2, the first sensor unit S1 and the second sensor unit S2 receive the third sensor unit S3.
  • the third sensor unit S3 can measure an environmental temperature substantially equal to the ambient temperature. Since this enables very accurate temperature measurement, the heating temperature by the first and second heater resistances MH1 and MH2 can be made almost as designed.
  • the present invention is not limited to this.
  • the sensor unit used in the present invention is not necessarily a heat conduction sensor, and may be a contact combustion sensor or another sensor.

Abstract

La présente invention vise à permettre de mesurer la concentration d'un gaz à détecter tout en éliminant l'influence d'un gaz différent du gaz à détecter. La présente invention concerne par conséquent une première thermistance Rd1 qui a une résistance qui change avec une première sensibilité en fonction de la concentration d'un premier gaz et qui change avec une seconde sensibilité en fonction de la concentration d'un second gaz, une seconde thermistance Rd2 qui est connectée en série à la première thermistance et a une résistance qui change avec une troisième sensibilité en fonction de la concentration du premier gaz et change avec une quatrième sensibilité en fonction de la concentration du second gaz, et une résistance de correction R1 qui est raccordée en parallèle avec la première ou la seconde thermistance. Dans la présente invention, les première et seconde thermistances sont raccordées en série et le changement de potentiel en fonction de la concentration du second gaz au point de raccordement entre la première thermistance et la seconde thermistance est annulé par la résistance de correction, de sorte qu'il est possible, sans impliquer de traitement de calcul, d'éliminer simplement et très précisément l'influence du second gaz et de calculer avec précision la concentration du premier gaz.
PCT/JP2018/032832 2017-09-26 2018-09-05 Capteur de gaz WO2019065127A1 (fr)

Priority Applications (3)

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US16/649,558 US11499932B2 (en) 2017-09-26 2018-09-05 Gas sensor
EP18863664.1A EP3690432A4 (fr) 2017-09-26 2018-09-05 Capteur de gaz
CN201880062693.3A CN111164419B (zh) 2017-09-26 2018-09-05 气体传感器

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JP2017184266 2017-09-26
JP2017-184266 2017-09-26
JP2018-129769 2018-07-09
JP2018129769A JP7070175B2 (ja) 2017-09-26 2018-07-09 ガスセンサ

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US20210096095A1 (en) * 2019-09-26 2021-04-01 Tdk Corporation Gas sensor with improved sensitivity and gas sensor component
CN113008969A (zh) * 2021-03-01 2021-06-22 上海雷密传感技术有限公司 用于气体传感器的气体浓度测量方法、装置及气体检测仪
CN113008943A (zh) * 2019-12-20 2021-06-22 财团法人工业技术研究院 气体感测装置及气体浓度感测方法
US20220252567A1 (en) * 2021-02-05 2022-08-11 Invensense, Inc. Adaptive sensor filtering
WO2022170054A1 (fr) * 2021-02-05 2022-08-11 Invensense, Inc. Filtrage adaptatif de capteur

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US20210096095A1 (en) * 2019-09-26 2021-04-01 Tdk Corporation Gas sensor with improved sensitivity and gas sensor component
US11898979B2 (en) * 2019-09-26 2024-02-13 Tdk Corporation Gas sensor with improved sensitivity and gas sensor component
CN113008943A (zh) * 2019-12-20 2021-06-22 财团法人工业技术研究院 气体感测装置及气体浓度感测方法
US20220252567A1 (en) * 2021-02-05 2022-08-11 Invensense, Inc. Adaptive sensor filtering
WO2022170054A1 (fr) * 2021-02-05 2022-08-11 Invensense, Inc. Filtrage adaptatif de capteur
CN113008969A (zh) * 2021-03-01 2021-06-22 上海雷密传感技术有限公司 用于气体传感器的气体浓度测量方法、装置及气体检测仪

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