Exhaust sensor and exhaust measuring method

Abstract

The invention relates to an expiration sensor and an expiration measurement method. In a first measurement period, a potential difference between a first terminal and a second terminal of a light-emitting element is maintained at a first value or more, and in a third measurement period, a potential difference between the first terminal and the second terminal is maintained at 0 V or more and less than the first value. The concentration of the gas to be measured is measured on the basis of a second intensity of the light received by the light-receiving element during a second measurement period and a fourth intensity of the light received by the light-receiving element during a fourth measurement period. The second measurement period starts at a second timing after a first timing at which the first measurement period starts and before a third timing at which the third measurement period starts, and the fourth measurement period starts at a fourth timing after the third timing and before the next first timing.

Description

TECHNICAL FIELD

[0001] The present application relates to an exhalation sensor and a method for measuring exhalation. BACKGROUND

[0002] Patent Document 1 describes "The present application described herein relates to a sensor and a method for measuring the concentration of alcohol in an alcohol hydrocarbon mixture." (TECHNICAL FIELD).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENT

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. H4-501769 SUMMARY

[0006] In a first aspect of the present application, an exhalation sensor is provided. The exhalation sensor can include a light source portion having a light emitting element of a heat radiation type including a filament, which irradiates light toward a measurement target gas associated with exhalation. The exhalation sensor can include a concentration measurement portion having a light receiving element that receives at least a portion of the light, and measures a concentration of the measurement target gas. In the exhalation sensor, the light source portion can have a first terminal and a second terminal. In the exhalation sensor, the light emitting element can be supplied with direct current power of a polarity switched based on a set condition from the first terminal and the second terminal. In the exhalation sensor, an absolute value of a potential difference between the first terminal and the second terminal can be maintained at a first value or more during a first measurement period in which the light emitting element is supplied with the direct current power and the first measurement period is repeated two or more times. In the exhalation sensor, a third value of the absolute value of the potential difference between the first terminal and the second terminal can be maintained at 0 V or more and less than the first value during a third measurement period different from the first measurement period. In the exhalation sensor, the concentration measurement portion can measure the concentration of the measurement target gas based on a second intensity of the light received by the light receiving element during a second measurement period, and a fourth intensity of the light received by the light receiving element during a fourth measurement period, the second measurement period starting at a second timing after a first timing at which the first measurement period starts and before a third timing at which the third measurement period starts, the fourth measurement period starting at a fourth timing after the second measurement period ends and after the third timing.

[0007] In the exhalation sensor, the first measurement period can be repeated two or more times at a frequency of 0.1 Hz or more.

[0008] In any of the above breath sensors, a first polarity as one of the polarities and a second polarity as the other of the polarities can be switched based on a number of times of activation of the breath sensor.

[0009] In any of the above breath sensors, a first polarity as one of the polarities and a second polarity as the other of the polarities can be switched based on a number of times of activation of the light emitting element.

[0010] In any of the above breath sensors, a first polarity as one of the polarities and a second polarity as the other of the polarities can be switched based on a time of supply of the direct current power.

[0011] In any of the above breath sensors, a first polarity as one of the polarities and a second polarity as the other of the polarities can be switched based on a time of activation of the breath sensor.

[0012] Any of the above breath sensors can include a resistance acquisition unit that acquires a resistance value of the light emitting element. In any of the above breath sensors, a first polarity as one of the polarities and a second polarity as the other of the polarities can be switched based on the resistance value.

[0013] In any of the above breath sensors, a first polarity as one of the polarities and a second polarity as the other of the polarities can be switched based on a temperature or humidity of a measurement target that includes the measurement target gas.

[0014] In any of the above breath sensors, the direct current power can be supplied by a constant voltage power supply. In any of the above breath sensors, the constant voltage power supply can have the first terminal and the second terminal. In any of the above breath sensors, the constant voltage power supply can maintain the first terminal at a first potential, maintain a potential of the second terminal at a second potential that is higher than the first potential, and supply the direct current power using a potential difference between the first potential and the second potential. In any of the above breath sensors, the constant voltage power supply can increase the potential difference in steps.

[0015] In any of the above breath sensors, the direct current power can be supplied by a constant current power supply.

[0016] In any of the above breath sensors, the concentration of the measurement target gas measured during a first polarity, which is one of the polarities, can be set as a first gas concentration, and the concentration of the measurement target gas measured during a second polarity, which is the other of the polarities, can be set as a second gas concentration. In any of the above breath sensors, the concentration measuring section can calculate the concentration of the measurement target gas by correcting at least one of the first gas concentration measured during the first polarity and the second gas concentration measured during the second polarity.

[0017] In any of the above breath sensors, the concentration measuring section can store a correction curve representing a relationship between the intensity of the light and the concentration for each polarity of the direct current power to the light emitting element, and calculate the concentration of the measurement target gas based on the correction curve corresponding to the polarity.

[0018] Any of the above breath sensors can have two or more of the light receiving elements. In the concentration measuring section of any of the above breath sensors, at least one of the length of the second measurement period and the length of the fourth measurement period can be different for each of the light receiving elements.

[0019] Any of the above breath sensors can have two or more of the light receiving elements. In the concentration measuring section of any of the above breath sensors, at least one of the second timing, which is the start time point of the second measurement period, and the fourth timing, which is the start time point of the fourth measurement period, can be different for each of the light receiving elements.

[0020] In the second aspect of the present application, a method of measuring exhaled breath is provided. The method can include a power supply stage in which direct current power is supplied to a light source section including a light emitting element of a thermal radiation type having a filament and having a first terminal and a second terminal, and the light emitting element emits light that irradiates a measurement target gas associated with exhaled breath. The method can include a concentration measurement stage in which a light receiving element that receives at least a portion of the light measures a concentration of the measurement target gas irradiated with the light. In either of the methods, the light emitting element can be supplied with direct current power having a polarity that is switched based on a set condition from the first terminal and the second terminal. In either of the methods, the absolute value of the potential difference between the first terminal and the second terminal can be maintained at a first value or more during a first measurement period in which the light emitting element is supplied with the direct current power and the first measurement period is repeated two or more times. In either of the methods, the absolute value of the potential difference between the first terminal and the second terminal can be maintained at a third value of 0 V or more and less than the first value during a third measurement period that is different from the first measurement period. In either of the methods, the concentration of the measurement target gas can be measured based on a second intensity of the light received by the light receiving element during a second measurement period that starts at a second timing that is after a first timing at which the first measurement period starts and before a third timing at which the third measurement period starts, and a fourth intensity of the light received by the light receiving element during a fourth measurement period that starts at a fourth timing that is after the end of the second measurement period and after the third timing, and before a next first timing at which the first measurement period starts again.

[0021] In a third aspect of the present invention, there is provided an exhalation sensor that measures a concentration of a measurement target gas. The exhalation sensor can include a light source section having a heat radiation type light emitting element including a filament that irradiates light toward a measurement target gas associated with exhalation. The exhalation sensor can include a concentration measurement section having a light receiving element that receives at least a portion of the light, and measures the concentration of the measurement target gas. In the exhalation sensor, the light source section can have a first terminal and a second terminal. In the exhalation sensor, the light emitting element can be supplied with direct current power having a polarity that is switched based on a set condition from the first terminal and the second terminal. In the exhalation sensor, an absolute value of a potential difference between the first terminal and the second terminal is maintained to be a first value or more during a first measurement period in which the light emitting element is supplied with the direct current power, the first measurement period being repeated two or more times. In the exhalation sensor, an absolute value of a potential difference between the first terminal and the second terminal during a third measurement period different from the first measurement period can be maintained to be a third value of 0 V or more and less than the first value. In the exhalation sensor, the concentration measurement section can measure the concentration of the measurement target gas based on a first intensity of the light received by the light receiving element during the first measurement period and a third intensity of the light received by the light receiving element during the third measurement period.

[0022] Note that the above summary of the invention does not exhaustively list all features of the invention. In addition, sub-combinations of these groups of features can also constitute inventions. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1A FIG. 1 is a diagram showing an example of a gas sensor 100 according to an embodiment of the present invention.

[0024] Figure 1B FIG. 2 is a diagram showing another example of the gas sensor 100 according to the embodiment of the present invention.

[0025] Figure 2 FIG. 3 is a circuit diagram showing an example of a connection relationship between the light emitting element 10 and the power supply section 20 in the gas sensor 100 of Figure 1A or Figure 1B

[0026] Figure 3 FIG. 4 is a circuit diagram showing another example of a connection relationship between the light emitting element 10 and the power supply section 20 in the gas sensor 100 of Figure 1A or Figure 1B

[0027] Figure 4 FIG. 5 is a diagram showing an example of a relationship between a polarity of direct current power and a time t. ​​

[0028] Figure 5 FIG. 6 is a graph showing another example of the relationship between the polarity of the direct current and the time t.

[0029] Figure 6 FIG. 6 is a graph showing another example of the relationship between the polarity of the direct current and the time t.

[0030] Figure 7 FIG. 7 is a graph showing an example of the measurement target 200.

[0031] Figure 8 FIG. 8 is a graph showing an example of the relationship between the potential V of the second terminal Ev2 and the time t.

[0032] Figure 9 FIG. 9 is a graph showing an example of the relationship between the current I flowing through the filament 14 and the time t.

[0033] Figure 10 FIG. 10 is a graph showing a comparative example of the relationship between the potential V of the second terminal Ev2 and the time t.

[0034] Figure 11 FIG. 11 is a graph showing a comparative example of the relationship between the current I flowing through the filament 14 and the time t.

[0035] Figure 12 FIG. 12 is a graph showing another example of the relationship between the potential V of the second terminal Ev2 and the time t.

[0036] Figure 13 FIG. 13 is a graph showing an example of the relationship between the current I flowing through the filament 14 and the time t.

[0037] Figure 14 FIG. 14 is a graph showing another example of the relationship between the polarity of the direct current and the time t.

[0038] Figure 15 FIG. 15 is a graph showing another example of the relationship between the polarity of the direct current and the time t.

[0039] Figure 16 FIG. 16 is a graph showing another example of the relationship between the polarity of the direct current and the time t.

[0040] Figure 17 FIG. 17 is a graph showing an example of the relationship between the intensity Ir of the light 12 and the concentration of the measurement target gas 90.

[0041] Figure 18 FIG. 18 is a graph showing another example of the relationship between the polarity of the direct current and the time t.

[0042] Figure 19 FIG. 19 is a graph showing an example of the relationship between the intensity of the light 12 received by the first light-receiving element 52 and the time t.

[0043] Figure 20FIG. 1 is a diagram showing an example of a power supply system 300 according to an embodiment of the present application.

[0044] Figure 21 FIG. 4 is a flowchart showing an example of a gas concentration measurement method according to an embodiment of the present application.

[0045] Explanation of Reference Numerals

[0046] 10 light emitting element, 12 light, 14 filament, 20 power supply unit, 30 chamber, 32 internal space, 34 gas inlet and outlet, 40 switching unit, 50 concentration measurement unit, 51 first optical filter, 52 first light receiving element, 53 second optical filter, 54 storage unit, 55 second light receiving element, 60 resistance acquisition unit, 70 hygrometer, 90 measurement target gas, 100 gas sensor, 200 measurement target, 300 power supply system. DETAILED DESCRIPTION

[0047] Hereinafter, the present application will be described through embodiments of the application, but the following embodiments do not limit the scope of the application involved in the claims. In addition, the combination of features described in the embodiments is not necessarily all necessary for the solution means of the application.

[0048] In this specification, regarding each element of a circuit, the configuration of each element is sometimes described in a manner that a third element is disposed between a first element and a second element. The description of the configuration refers to the position of each element in an electric path, and does not limit the position of each element in space.

[0049] Figure 1A FIG. 1 is a diagram showing an example of a gas sensor 100 according to an embodiment of the present application. The gas sensor 100 measures the concentration of a measurement target gas 90. As an example, the measurement target gas 90 is a gas associated with exhalation, but the measurement target gas 90 is not limited thereto. The gas associated with exhalation is a gas including a gas contained in exhalation. The gas associated with exhalation can be a part of the gas contained in exhalation, or can be all of the gas, or can be a gas in which these gases are mixed with other gases. For example, the gas sensor 100 can be an exhalation sensor that measures the concentration of carbon dioxide, the concentration of alcohol in exhalation, or the like, but the measurement target gas 90 is not limited thereto. The measurement target gas 90 is, for example, carbon dioxide, water vapor, methane, ethane, propane, butane, formaldehyde, carbon monoxide, nitrogen monoxide, ammonia, sulfur dioxide, alcohol (methanol, ethanol, or the like), chlorofluorocarbon, hydrochlorofluorocarbon, hydrofluorocarbon, refrigerant gas (R32, R290, or the like), or the like, or a mixed gas thereof.

[0050] The concentration of the gas is, for example, a volume concentration (vol%). The gas sensor 100 is provided with the light emitting element 10, the power supply portion 20, the chamber 30, and the concentration measuring portion 50. The gas sensor 100 can be provided with the first optical filter 51. The measurement target gas 90 is housed in the internal space 32 of the chamber 30. The chamber 30 can have a gas inlet and outlet 34. The measurement target gas 90 enters the internal space 32 from the gas inlet and outlet 34, and exits from the internal space 32 to the outside of the chamber 30. As shown in FIG. 1, the entrance of the measurement target gas 90 into the internal space 32 and the exit of the measurement target gas 90 from the internal space 32 can be a common opening, or can be separate openings. The gas sensor 100 can measure the concentration of the measurement target gas 90 passing through the chamber 30, or can measure the concentration of the measurement target gas 90 in a state of being enclosed in the chamber 30. Figure 1A

[0051] The light emitting element 10 emits light 12 that is irradiated toward the measurement target gas 90. The light emitting element 10 irradiates the light 12 toward the measurement target gas 90 housed in the internal space 32. The light emitting element 10 has a filament 14. The filament 14 can be formed mainly of W (tungsten). The filament 14 can also be W (tungsten) to which ThO2 (thorium oxide) or an oxide of a rare earth element is added. The power supply portion 20 supplies direct current power to the light emitting element 10. The light emitting element 10 is a heat radiation type. By supplying direct current power to the light emitting element 10, the filament 14 is heated. By heating the filament 14, the light emitting element 10 emits light 12 of a predetermined wavelength. The light 12 can be infrared light (wavelength of 780 nm or more and 15,000 nm or less), can be visible light (wavelength of 380 nm or more and 780 nm or less), or can be ultraviolet light (wavelength of 100 nm or more and 380 nm or less). The light 12 that is irradiated toward the measurement target gas 90 and that passes through the measurement target gas 90 is incident on the concentration measuring portion 50.

[0052] The concentration measuring portion 50 measures the concentration of the measurement target gas 90. The concentration measuring portion 50 can have a first light receiving element 52 that receives the light 12 irradiated toward the measurement target gas 90. The first optical filter 51 can be provided between the light emitting element 10 and the first light receiving element 52 in the optical path of the light 12. The first optical filter 51 is a filter that transmits the light 12 of a wavelength band that is to be absorbed by the measurement target gas 90. The first light receiving element 52 can receive the light 12 that has transmitted the first optical filter 51.

[0053] The concentration measuring portion 50 can measure the concentration of the measurement target gas 90 on the basis of the intensity of the light 12 received by the first light receiving element 52. The first light receiving element 52 can be a photodiode, or can be a thermopile. The concentration measuring portion 50 can have a storage portion 54.

[0054] ​The gas sensor 100 can be a so-called NDIR (Non-Dispersive Infrared) type gas sensor. The measurement target gas 90 absorbs infrared light of a specific wavelength. The higher the concentration of the measurement target gas 90, the greater the amount of light absorbed. In the case where the gas sensor 100 is of the NDIR type, the concentration measuring section 50 measures the concentration of the measurement target gas 90 based on the intensity of the light 12 received by the first light receiving element 52.

[0055] The gas sensor 100 can also be a photoacoustic type gas sensor. In the case where the gas sensor 100 is of the photoacoustic type, the concentration measuring section 50 can have a photoacoustic element that detects a photoacoustic wave. If the light 12 is irradiated to the measurement target gas 90, the light energy absorbed by the molecules of the measurement target gas 90 is converted into heat energy. As a result, the measurement target gas 90 expands. A pressure wave (photoacoustic wave) is generated in accordance with the change in volume of the measurement target gas 90. The higher the concentration of the measurement target gas 90, the greater the amplitude of the pressure wave. The photoacoustic element detects the change in pressure of the measurement target gas 90 by measuring the pressure wave. The concentration measuring section 50 measures the concentration of the measurement target gas 90 based on the change in pressure detected by the photoacoustic element. The concentration measuring section 50 can convert the change in pressure detected by the photoacoustic element into the concentration of the measurement target gas 90.

[0056] Figure 1B is a view that shows another example of the gas sensor 100 of one embodiment of the present application. The gas sensor 100 of the present example differs from the gas sensor 100 of Figure 1A in that it further includes a second light receiving element 55 and a second optical filter 53. In the present example, the concentration measuring section 50 has the second light receiving element 55 that receives the light 12 irradiated to the measurement target gas 90. The second optical filter 53 can be provided between the light emitting element 10 and the second light receiving element 55 in the optical path of the light 12. The second optical filter 53 is a filter that transmits the light 12 of a wavelength band that is not absorbed by the measurement target gas 90. The second light receiving element 55 can receive the light 12 that has transmitted the second optical filter 53.

[0057] Figure 2 is a circuit diagram that shows an example of the connection relationship between the light emitting element 10 and the power supply section 20 in the gas sensor 100 of Figure 1A or Figure 1B The power supply section 20 can be a constant-voltage power supply or a constant-current power supply. In the example of Figure 2 , the power supply section 20 is a constant-voltage power supply.

[0058] The light emitting element 10 can have a first terminal E1 and a second terminal E2. The first terminal E1 and the second terminal E2 are electrical terminals. The light emitting element 10 emits light by a current flowing between the first terminal E1 and the second terminal E2. The light emitting element 10 of this example has a filament 14 connected between the first terminal E1 and the second terminal E2.

[0059] The power supply section 20 can have a first terminal Ev1 and a second terminal Ev2. The power supply section 20 can maintain the first terminal Ev1 at a first potential V1, and can maintain the second terminal Ev2 at a second potential V2. The first potential V1 can be a ground potential. The second potential V2 is a high potential compared to the first potential V1. The power supply section 20 supplies direct-current power to the light emitting element 10 by a potential difference between the first potential V1 and the second potential V2.

[0060] The gas sensor 100 is provided with a switching section 40. In Figure 2 this example, the range of the switching section 40 is indicated by a single-dot chain line. The switching section 40 switches the polarity of the direct-current power supplied to the first terminal E1 and the second terminal E2 of the light emitting element 10 based on a set condition. The switching section 40 can switch the polarity of the voltage applied to the first terminal E1 and the second terminal E2. For example, the switching section 40 switches the polarity by switching the potential of the second terminal E2 to be relatively higher or lower with respect to the potential of the first terminal E1. The switching section 40 of this example switches the polarity of the power supplied to the light emitting element 10 by the power supply section 20 based on a set condition. The set condition is, for example, a period during which the first polarity of the power is supplied or a period during which the second polarity of the power is supplied. The switching section 40 switches the direction of the current flowing through the filament 14 by switching the polarity of the power. In this specification, the polarity of the power can refer to the direction of the current flowing through the filament 14.

[0061] In this example, the first polarity is the polarity in which the current flows through the filament 14 in the direction from the second terminal E2 to the first terminal E1. That is, the first polarity is a state in which the potential of the second terminal E2 is higher than the potential of the first terminal E1. In Figure 2 the example, the first polarity is a state in which the first terminal E1 of the light emitting element 10 is connected to the first terminal Ev1 of the power supply section 20 and the second terminal E2 is connected to the second terminal Ev2. In this example, the second polarity is the polarity in which the current flows through the filament 14 in the direction from the first terminal E1 to the second terminal E2. That is, the second polarity is a state in which the potential of the second terminal E2 is lower than the potential of the first terminal E1. In Figure 2 the example, the second polarity is a state in which the first terminal E1 is connected to the second terminal Ev2 and the second terminal E2 is connected to the first terminal Ev1. Figure 2 is an example of the state of each switch in the case of the second polarity.

[0062] InFigure 2 In this example, the switching unit 40 has a first switch Sw1 and a second switch Sw2. The first switch Sw1 selects one of the first terminal Ev1 and the second terminal Ev2 and connects it to the first terminal E1 of the light-emitting element 10. The second switch Sw2 selects a terminal of the first terminal Ev1 and the second terminal Ev2 that is different from the first switch Sw1 and connects it to the second terminal E2 of the light-emitting element 10. Figure 2 In the diagram, the ranges of the first switch Sw1 and the second switch Sw2 are represented by dashed lines.

[0063] exist Figure 2 In this example, the switching unit 40 has a third switch Sw3 and a relay element Re. In this example, the switching unit 40 drives the first switch Sw1 and the second switch Sw2 via the relay element Re by turning the third switch Sw3 on or off. The switching unit 40 sets the polarity of the power supplied by the power supply unit 20 to the first polarity by turning the third switch Sw3 on, and sets the polarity of the power to the second polarity by turning the third switch Sw3 off.

[0064] The relay element Re can have a coil. The third switch Sw3 toggles whether current flows through the coil. In this example, the first switch Sw1 and the second switch Sw2 switch on and off by the magnetic field generated by the current flowing through the coil.

[0065] The gas sensor 100 may also include a resistance acquisition unit 60. The resistance acquisition unit 60 acquires the resistance value R of the light-emitting element 10. The resistance acquisition unit 60 can also acquire the resistance value R of the filament 14. Figure 2 In the diagram, the range of the resistance acquisition section 60 is indicated by a thick dashed line. Figure 2 In this example, the resistance acquisition unit 60 measures the voltage generated across the filament 14 by allowing a certain current to flow between the first terminal E1 and the second terminal E2. Using this voltage and the constant current flowing between the first terminal E1 and the second terminal E2, the resistance acquisition unit 60 obtains the resistance value R.

[0066] The gas sensor 100 may also include a thermo-hygrometer 70. The thermo-hygrometer 70 will be described later.

[0067] Figure 3 It means Figure 1A or Figure 1B A circuit diagram illustrating another example of the connection between the light-emitting element 10 and the power supply unit 20 in the gas sensor 100. In this example, the power supply unit 20 is a constant voltage power supply. Figure 3 In the diagram, the range of the switching unit 40 is indicated by a single-dotted line. In this example, the gas sensor 100 and... Figure 2 The example also has a resistor acquisition section 60.

[0068] existFigure 3 In the example of FIG. 2, the first polarity is a state in which the first terminal El of the light emitting element 10 is connected to the first terminal Evl of the power supply 20 and the second terminal E2 is connected to the second terminal Ev2. The second polarity is a state in which the first terminal El is connected to the second terminal Ev2 and the second terminal E2 is connected to the first terminal Evl. Figure 2 In the example of FIG. 2, the first polarity is a state in which the first terminal El of the light emitting element 10 is connected to the first terminal Evl of the power supply 20 and the second terminal E2 is connected to the second terminal Ev2. The second polarity is a state in which the first terminal El is connected to the second terminal Ev2 and the second terminal E2 is connected to the first terminal Evl. Figure 3 FIG. 4 is an example of a state of each transistor in a case where the second polarity is indicated.

[0069] In the present example, the switching section 40 has a first transistor Trl, a second transistor Tr2, a third transistor Tr3, and a fourth transistor Tr4. The first transistor Trl and the second transistor Tr2 of the present example switch which one of the first terminal Evl and the second terminal Ev2 is connected to the first terminal El of the light emitting element 10. In addition, the third transistor Tr3 and the fourth transistor Tr4 switch which one of the first terminal Evl and the second terminal Ev2 is connected to the second terminal E2 of the light emitting element 10.

[0070] The first transistor Trl of the present example is disposed between the second terminal Ev2 and the first terminal Evl. The second transistor Tr2 is disposed between the first transistor Trl and the first terminal Evl. A connection node of the first transistor Trl and the second transistor Tr2 is connected to the first terminal El of the light emitting element 10. In addition, the third transistor Tr3 is disposed between the second terminal Ev2 and the first terminal Evl. The fourth transistor Tr2 is disposed between the third transistor Tr3 and the first terminal Evl. A connection node of the third transistor Tr3 and the fourth transistor Tr4 is connected to the second terminal E2 of the light emitting element 10.

[0071] In the present example, the switching section 40 makes the first transistor Trl and the fourth transistor Tr4 off and makes the second transistor Tr2 and the third transistor Tr3 on, thereby making the polarity of the power the first polarity. The switching section 40 makes the first transistor Trl and the fourth transistor Tr4 on and makes the second transistor Tr2 and the third transistor Tr3 off, thereby making the polarity of the power the second polarity.

[0072] Figure 4 FIG. 5 is an example of a graph indicating the relationship between the polarity of the direct current power and the time t. In the present example, the potential V of the first terminal El of the light emitting element 10 changes with the passage of time. Note that a potential having a phase that differs by 180 degrees from the first terminal El is applied to the second terminal E2 of the light emitting element 10.

[0073] The first terminal El of the present example is connected to the first terminal Evl of the power supply 20 and the second terminal E2 is connected to the second terminal Ev2 in the first polarity. Figure 2 In the example of FIG. 2, the first polarity is a state in which the first terminal El of the light emitting element 10 is connected to the first terminal Evl of the power supply 20 and the second terminal E2 is connected to the second terminal Ev2. The second polarity is a state in which the first terminal El is connected to the second terminal Ev2 and the second terminal E2 is connected to the first terminal Evl. Figure 3The first terminal Evl and the second terminal Ev2 are alternately connected as described above. The potential of the first terminal Evl is the first potential VI, and the potential of the second terminal Ev2 is the second potential V2. Thus, the first potential VI and the second potential V2 are alternately applied to the first terminal El. The second potential V2 is applied to the second terminal E2 during the period when the first potential VI is applied to the first terminal El. The first potential VI is applied to the second terminal E2 during the period when the second potential V2 is applied to the first terminal El. Thus, the polarity of the direct current applied to the light emitting element 10 is alternately switched. The direct current supplied from the power supply section 20 can be in a pulse shape. In this example, the potentials applied to the first terminal El and the second terminal E2 are changed in a pulse shape. For example, in the case where the power supply section 20 (constant voltage power supply) supplies a direct current, the power supply section 20 can supply a pulse-shaped direct current by alternately supplying a constant voltage V Figure 2 const and 0 V. In the case where the power supply section 20 (constant voltage power supply) supplies a direct current, the power supply section 20 can supply a pulse-shaped direct current by alternately supplying a constant voltage V Figure 2 const1 and a constant voltage V const1 different from the V const2 .

[0074] The switching section 40 (see FIG. 2 and FIG. 3) can switch the polarity of the direct current in accordance with the period Tl and the period T2 set. In the example of FIG. 4, the first potential VI is applied to the first terminal El, and the second potential V2 is applied to the second terminal E2 in the period Tl. In addition, the second potential V2 is applied to the first terminal El, and the first potential VI is applied to the second terminal E2 in the period T2. The period Tl and the period T2 can be the same length as each other, or can be different lengths. The length of the period Tl can change with time, or can be constant. The length of the period T2 can change with time, or can be constant. The period Tl and the period T2 set can be 0.1 seconds, can be 0.2 seconds, can be 1 second, can be 2 seconds, or can be 5 seconds. Figure 2 Figure 3 The switching section 40 can also switch the polarity of the direct current in accordance with the time t set. In the example of FIG. 5, the polarity of the direct current is switched at each of the times tl to t6. The times tl to t6 at which the polarity of the direct current is switched can be determined in advance. The times tl to t6 can also be different dates from each other. Figure 4

[0075] The switching section 40 can also switch the polarity of the direct current in accordance with the time t set. In the example of FIG. 5, the polarity of the direct current is switched at each of the times tl to t6. The times tl to t6 at which the polarity of the direct current is switched can be determined in advance. The times tl to t6 can also be different dates from each other. Figure 4

[0076] ​​​​​A portion of the filament 14 of the light emitting element 10 evaporates during startup of the light emitting element 10. When a portion of the filament 14 evaporates, the filament 14 becomes thin. Thus, the filament 14 is likely to break. If the same polarity of direct current power is continuously supplied to the light emitting element 10, the same portion of the filament 14 is likely to continuously evaporate. Thus, the filament 14 is likely to become thin locally. In the gas sensor 100, the switching section 40 switches the polarity of the direct current power based on a set condition. For example, the switching section 40 periodically switches the polarity of the direct current power. Thus, the evaporation portion in the filament 14 is likely to be dispersed. Thus, the life of the filament 14 is likely to be long.

[0077] Figure 5 is another example of a graph indicating the relationship between the polarity of the direct current power and the time t. In this example, the power supply section 20 supplies the first polarity of direct current power to the light emitting element 10 during the period from time tl to time t2 and the period from time t3 to time t4, and supplies the second polarity of direct current power to the light emitting element 10 during the period from time t5 to time t6. In this example, the power supply section 20 does not supply direct current power to the light emitting element 10 during the period from time t2 to time t3 and the period from time t4 to time t5.

[0078] The period from time tl to time t2, the period from time t3 to time t4, and the period from time t5 to time t6 are set as a period Ta. The period from time t2 to time t3 and the period from time t4 to time t5 are set as a period Tr. The period Tr can be equal to the period Ta, can be 10 times or more of the period Ta, can be 20 times or more, or can be 100 times or more.

[0079] The switching section 40 can switch the polarity of the direct current power based on the number of startups of the power supply section 20. For example, the switching section 40 switches the polarity of the direct current power when the number of startups of the power supply section 20 exceeds a predetermined number of times. The predetermined number of times can be 2, can be 5, or can be 10. The startup of the power supply section 20 refers to a change from a state in which the power supply section 20 is not started to a state in which the power supply section 20 is started. In the example of Figure 5 , the state in which the power supply section 20 is started is the state of the power supply section 20 in the period Ta. The state in which the power supply section 20 is not started is the state of the power supply section 20 in the period Tr in the example of Figure 5 , the state in which the power supply section 20 is started is the state of the power supply section 20 in the period Ta. The state in which the power supply section 20 is not started is the state of the power supply section 20 in the period Tr in the example of Figure 5 , the state in which the power supply section 20 is started is the state of the power supply section 20 in the period Ta. The state in which the power supply section 20 is not started is the state of the power supply section 20 in the period Tr in the example of

[0080] The switching section 40 can switch the polarity of the direct current based on the number of times of activation of the light emitting element 10. For example, the switching section 40 switches the polarity of the direct current in a case where the number of times of activation of the light emitting element 10 exceeds a predetermined number of times. The predetermined number of times can be two times, can be five times, or can be ten times. The activation of the light emitting element 10 refers to a change from a state where the direct current is not supplied to the light emitting element 10 to a state where the direct current is supplied. The state where the direct current is not supplied to the light emitting element 10 refers to a state where no current flows through the light emitting element 10. The activation of the light emitting element 10 refers to a change from a state where no current flows through the light emitting element 10 to a state where a current flows through the light emitting element 10 by supplying the direct current. In Figure 5 the example, the state where the direct current is not supplied to the light emitting element 10 is the state of the direct current in the period Tr. In Figure 5 the example, the switching section 40 switches the polarity of the direct current to the second polarity in a case where the number of times of activation of the light emitting element 10 under the first polarity exceeds two times.

[0081] As described above, the period Tr can be equal to the period Ta, can be more than ten times the period Ta, can be more than twenty times, or can be more than one hundred times. For example, in a case where the period Ta is one second and the period Tr is less than ten seconds, the direct current can be continuously supplied to the light emitting element 10. That is, the supply of the direct current at the time t3 and the time t5 can not be included in the number of times of activation of the light emitting element 10. For example, in a case where the period Ta is one second and the period Tr is more than ten seconds, the supply of the direct current at the time t3 and the time t5 can be included in the number of times of activation of the light emitting element 10.

[0082] In the period Tr where the direct current is not supplied, the filament 14 becomes a low temperature. In a case where the temperature of the filament 14 is low, the filament has a low resistance value R. In a case where the power supply section 20 is a constant voltage power source, a large direct current flows in the filament 14 at the instant when the direct current is supplied (that is, at the instant when the period Ta is entered). In a case where there is a portion where the filament 14 is thin, the portion rapidly heats up due to the large direct current. In a case where the power supply section 20 is a constant current power source, a certain direct current flows in the filament 14 at the instant when the direct current is supplied (that is, at the instant when the period Ta is entered) regardless of the temperature of the filament 14. In a case where there is a portion where the filament 14 is thin, the portion rapidly heats up due to the certain direct current. Thus, in a case where the power supply section 20 is either of a constant voltage power source and a constant current power source, the more the number of times of activation of the light emitting element 10 increases, the more the amount of evaporation of the same portion as the portion of the filament 14 is likely to increase. The switching section 40 switches the polarity of the direct current based on the number of times of activation of the light emitting element 10, and thus a portion of the evaporation in the filament 14 is likely to be dispersed.

[0083] Figure 6 is another example of a graph indicating the relationship between the polarity of direct current power and the time t. In this example, the power supply section 20 starts to supply direct current power of the first polarity at time tl, time t4, time t6, and time tlO, and starts to supply direct current power of the second polarity at time t2, time t5, and time t8. In this example, the power supply section 20 continues to supply direct current power of the first polarity in the period Tei, the period Te4, the period Te6, and the period Te10, and continues to supply direct current power of the second polarity in the period Te2, the period Te5, and the period Te8. In this example, the power supply section 20 does not supply direct current power in the period Te3, the period Te7, and the period Te9. The lengths of the period Tei to the period Te10 can be equal to each other, or can be different from each other.

[0084] The power supply section 20 can acquire the supply time of the direct current power of the first polarity. For example, in the case where the current time t is an arbitrary time in the period Te7, the power supply section 20 acquires the total time of the period Tei, the period Te4, and the period Te6 as the supply time. The supply time of the direct current power of the first polarity can also be set in advance. The supply time can be set in advance according to the date or the time.

[0085] The switching section 40 can switch the polarity of the direct current power to the second polarity based on the supply time. For example, the switching section 40 switches the polarity of the direct current power to the second polarity in the case where the supply time exceeds a predetermined time. As described above, if the direct current power of the same polarity is continuously supplied to the light emitting element 10, the W (tungsten) of the same part in the filament 14 is likely to continuously evaporate. Thus, the filament 14 is likely to be locally thinned. The switching section 40 switches the polarity of the direct current power based on the supply time, whereby the part in which the W (tungsten) evaporates in the filament 14 is likely to be dispersed. Thus, the life of the filament 14 is likely to be lengthened.

[0086] The switching section 40 can switch the polarity of the direct current power based on the resistance value R of the light emitting element 10. For example, the switching section 40 can switch the polarity in the case where the resistance value R increases by a predetermined percentage. The resistance value R of the light emitting element 10 at a first time is set to R0, and the resistance value R of the light emitting element 10 at a second time after the first time is set to Rl. The percentage of the increase in the resistance value R can be defined by (Rl / R0). The predetermined percentage of the increase can be 0.05%, can be 0.1%, can be 0.2%, can be 0.5%, or can be 1%.

[0087] In the case where the start of the light emitting element 10 is started at the first time, the resistance value R0 is the resistance value R before the current flows through the filament 14. In the case where the start of the light emitting element 10 is started at the second time, the resistance value Rl is the resistance value R after the current flows through the filament 14. Figure 6In a case where the first time is time t1, the second time is, for example, time t2. The resistance value R at time t1 is R0, and the resistance value R at time t2 is R1. In Figure 6 In a case where the resistance value R at time t2 (R1 / R0) exceeds a predetermined ratio, the switching section 40 switches the polarity from the first polarity to the second polarity. In this way, the switching section 40 can switch the polarity each time the resistance value R increases by a predetermined ratio. Figure 6 In a case where the first time is time t2, the second time is, for example, time t3. The resistance value R at time t2 is R0, and the resistance value R at time t3 is R1. In Figure 6 In a case where the resistance value R at time t3 (R1 / R0) exceeds a predetermined ratio, the switching section 40 switches the polarity from the second polarity to the first polarity. In this way, the switching section 40 can switch the polarity each time the resistance value R increases by a predetermined ratio.

[0088] When W (tungsten) is heated in the filament 14, the resistance value R increases. If the resistance value R increases, the filament 14 is more likely to heat. Thus, the evaporation amount of W (tungsten) is likely to increase. Thus, the filament 14 is likely to break. By switching the polarity by the switching section 40 based on the resistance value R, the position where W (tungsten) evaporates in the filament 14 is likely to be uniform. Thus, the life of the filament 14 is likely to be long.

[0089] Figure 7 is a diagram that shows an example of a measurement target 200. The measurement target 200 of this example is an indoor space of a vehicle. The measurement target 200 includes a measurement target gas 90. In this example, the indoor space of the vehicle includes the measurement target gas 90. The hygrometer 70 measures the temperature or humidity of the measurement target 200. In this example, the hygrometer 70 measures the temperature or humidity of the indoor space.

[0090] In this example, the gas sensor 100 is provided to the measurement target 200. The gas sensor 100 can have or can not have the hygrometer 70. In a case where the vehicle has the hygrometer 70, the gas sensor 100 can not have the hygrometer 70. The hygrometer 70 provided to the vehicle can transmit the measured temperature or humidity to the gas sensor 100.

[0091] The switching section 40 can switch the polarity of the direct current power based on the temperature or humidity of the measurement target 200. For example, the higher the temperature or humidity of the measurement target 200, the less frequently the switching section 40 switches the polarity. In the case where the measurement target 200 is an indoor space of a vehicle, the temperature of the measurement target 200 is likely to be significantly higher than the temperature of the outside of the measurement target 200. In the case of an indoor space of a vehicle, the temperature of the measurement target 200 can be about 60 to 70°C. In such a case, the temperature of the filament 14 in the startup of the light emitting element 10 is likely to become higher. As a result, the resistance value R of the filament 14 is more likely to increase. As a result, the filament 14 is more likely to be heated.

[0092] The higher the humidity of the measurement target 200, the higher the temperature of the filament 14 in the startup of the light emitting element 10 is likely to become. As a result, the resistance value R of the filament 14 is more likely to increase. As a result, the filament 14 is more likely to be heated.

[0093] The switching section 40 makes the period of switching the polarity shorter as the temperature or humidity of the measurement target 200 is higher, thereby dispersing the portion of the W (tungsten) evaporated in the filament 14 before a part of the filament 14 is locally thinned. As a result, the life of the filament 14 is likely to be longer.

[0094] In the case where the measurement target 200 is an indoor space of a vehicle, the switching section 40 can switch the polarity based on at least one of the number of start-ups of an engine of the vehicle, the distance of travel, the position information, and the amount of fuel remaining. With the key switch turned on, the power supply section 20 (see Figure 1A ) in the vehicle is started. As a result, the engine of the vehicle is started. Therefore, the number of start-ups of the engine is basically equal to the number of times of turning on the key switch. In the case where the vehicle is a key start type based on a smart key, the engine of the vehicle is started in conjunction with the key start. Therefore, the number of start-ups of the engine is equal to the number of times of the key start. In the case where the number of times of turning on the key switch or the number of times of the key start is set to m (m is a natural number), in the case where the power supply section 20 supplies the direct current power of the first polarity the 2m-1th time, the switching section 40 can switch the polarity of the direct current power supplied the 2mth time to the second polarity. In addition, in the case where the key switch is rotated by half a turn (ACC state) to start the power supply section 20 but not to start the engine of the vehicle, it can also be included in the number of times of turning on the key switch or the number of times of the key start. In the case of an electric vehicle, a fuel cell vehicle, or the like driven by a motor, instead of the number of start-ups of the engine, the number of drives of the motor can be set, and even in the case where the power supply section 20 is started but the motor of the vehicle is not started, it can be included in the number of times of turning on the key switch or the number of times of the key start.

[0095] The electric power supply section 20 can be a storage battery mounted on the vehicle, for example, a lead storage battery, a lithium ion battery, or the like. In a case where the gas sensor 100 is mounted with a storage battery, the electric power supply section 20 can be a storage battery built in the gas sensor 100, a primary battery such as an alkaline battery, a manganese battery, or the like, a secondary battery such as a lithium ion battery, a nickel-hydrogen battery, or the like.

[0096] The switching section 40 can also switch the polarity of the direct current electric power based on the engine start time. The engine start time refers to a period from a time when the user of the vehicle starts the engine to the current time. In a case where the gas sensor 100 is started in the engine start, the longer the engine start time, the longer the start time of the gas sensor 100. Therefore, in a case where the polarity of the direct current electric power is not switched in the start time of the gas sensor 100, a part of the filament 14 is likely to be locally thinned. Therefore, in a case where the engine start time exceeds a predetermined time, the switching section 40 can switch the polarity of the direct current electric power.

[0097] The travel distance of the vehicle can be a travel distance from a time when the user of the vehicle starts the engine to the current time after the user makes the vehicle start traveling. The travel distance can be obtained based on position information of the vehicle at the time when the user starts the engine and position information of the vehicle at the current time. The travel distance can be a distance between the position of the vehicle at the time when the user starts the engine and the position of the vehicle at the current time. The longer the travel distance, the longer the engine start time. Therefore, in a case where the travel distance of the vehicle exceeds a predetermined distance, the switching section 40 can switch the polarity of the direct current electric power.

[0098] The remaining amount of the fuel is an amount obtained by subtracting a consumption amount of the fuel caused by the travel of the vehicle from a predetermined amount of the fuel (for example, an amount of the fuel in a full-fuel state). The remaining amount of the fuel can use a value obtained by detecting the remaining amount of the fuel at the current time by a sensor or the like. The longer the travel distance of the vehicle, the larger the consumption amount of the fuel. Therefore, the switching section 40 can switch the polarity of the direct current electric power based on the remaining amount of the fuel. The switching section 40 can switch the polarity of the direct current electric power in a case where the remaining amount of the fuel is smaller than a predetermined amount.

[0099] Figure 8 FIG. 2 is a graph showing an example of a relationship between the potential V of the second terminal Ev2 and the time t. In a case where the electric power supply section 20 is a constant voltage power source, the constant voltage power source can increase the potential difference between the first potential VI and the second potential V2 in a stepwise manner. The constant voltage power source can increase the potential V of the second terminal Ev2 from the first potential VI to the second potential V2 in a stepwise manner in a state where the first terminal Evl is maintained at the first potential VI.

[0100] The constant voltage power supply can maintain the first terminal Ev1 at a first potential V1, and then increase the potential V of the second terminal Ev2 from the first potential V1 to an intermediate potential Vs1. After a predetermined time has elapsed since the potential V of the second terminal Ev2 was increased to the intermediate potential Vs1, the constant voltage power supply can then increase the potential V of the second terminal Ev2 from the intermediate potential Vs1 to the intermediate potential Vs2. When the potential V of the second terminal Ev2 increases from the first potential V1 to the intermediate potential Vs1, the current I flowing through the filament 14 changes. The current I changes transiently; therefore, immediately after increasing to the intermediate potential Vs1, the current I may not have fully changed to the current I corresponding to the intermediate potential Vs1. The predetermined time from the increase of the potential V of the second terminal Ev2 to the intermediate potential Vs1 refers to the time from when the change of the current I flowing through the filament 14 is complete until the change towards the current I corresponding to the intermediate potential Vs1 ends. Similarly, the constant voltage power supply can increase the potential V of the second terminal Ev2 to the second potential V2.

[0101] There can be at least one intermediate potential Vs. In this example, there are three intermediate potentials Vs. There can also be two or more intermediate potentials Vs. Let the potential difference between adjacent potentials be the potential difference Vd. When there are n (n is an integer greater than 2) intermediate electrons Vs, there exists a potential difference Vd1 from the first potential V1 and the intermediate potential Vs1 to the potential difference Vd between the intermediate potential Vsn and the second potential V2. n+1 There are n+1 potential differences Vd. The n+1 potential differences Vd can be the same or different from each other.

[0102] Among the n+1 potential differences Vd, potential difference Vd1 can be minimized, and potential difference Vd n+1 This allows for maximum current flow. Consequently, the initial current flowing through filament 14 decreases. Therefore, filament 14 is less prone to breakage. Consequently, the lifespan of filament 14 is extended. Figure 8 In the example, the potential difference Vd1 is made smaller than the potential difference Vd2, the potential difference Vd2 is made smaller than the potential difference Vd3, and the potential difference Vd3 is made smaller than the potential difference Vd4.

[0103] Among the n+1 potential differences Vd, potential difference Vd1 can be the largest, and potential difference Vd n+1 It can be minimized. Therefore, the initial current flowing through filament 14 increases. Consequently, the second terminal Ev2 easily and quickly reaches the second potential V2. Figure 8 In the example, for instance, the potential difference Vd1 is greater than the potential difference Vd2, the potential difference Vd2 is greater than the potential difference Vd3, and the potential difference Vd3 is greater than the potential difference Vd4.

[0104] In this example, time t1 is a time at which the constant voltage power supply increases the potential V of the second terminal Ev2 from the first potential VI to the intermediate potential Vs, and time t2 is a time at which the constant voltage power supply increases the potential V of the second terminal Ev2 from the intermediate potential Vs to the second potential V2. The period T is a period between time t1 and time t2. The constant voltage power supply can change the potential V of the second terminal Ev2 from the first potential VI to the second potential V2 in a stepwise manner over the entire period T.

[0105] Figure 9 is a graph showing an example of the relationship between the current I flowing through the filament 14 and the time t. Figure 9 is an example of the relationship between the current I and the time t in a case where the potential V of the second terminal Ev2 changes as Figure 8 The power supply portion 20 is a constant voltage power supply in this example. Therefore, during a period in which the potential V of the second terminal Ev2 increases from the first potential VI to the intermediate potential Vs1 by a predetermined time, the current I decreases in response to the increase in the resistance value R of the filament 14. Thus, the speed at which the filament 14 is thinned decreases.

[0106] Figure 10 is a graph showing a comparative example of the relationship between the potential V of the second terminal Ev2 and the time t. In this comparative example, the constant voltage power supply does not change the potential difference between the first potential VI and the second potential V2 in a stepwise manner. The period T in this comparative example is smaller than the period T in the example of Figure 8

[0107] Figure 11 is a graph showing a comparative example of the relationship between the current I flowing through the filament 14 and the time t. Figure 11 is an example of the relationship between the current I and the time t in a case where the potential V of the second terminal Ev2 changes as Figure 10 In this comparative example, the constant voltage power supply does not change the potential difference between the first potential VI and the second potential V2 in a stepwise manner, and thus the current I easily increases sharply at time t1. After the current I increases sharply at time t1, the current I decreases to a constant current I1’ in accordance with the increase in the resistance value R of the filament 14. In the comparative example, the current I easily increases sharply, and thus the filament 14 easily locally increases in temperature. Therefore, the site at which the filament 14 starts to be thinned easily breaks. Thus, the life of the filament 14 easily shortens.

[0108] Figure 12 is a graph showing another example of the relationship between the potential V of the second terminal Ev2 and the time t. Figure 13 is a graph showing an example of the relationship between the current I flowing through the filament 14 and the time t. Figure 12 Figure 13 ​​is an example of a case where the power supply section 20 is a constant current power source. In the case where the power supply section 20 is a constant current power source, the current I flowing through the filament 14 is constant. Therefore, as in the case of the constant voltage power source, the current flowing through the filament 14 is not likely to sharply increase with the start of the supply of the direct current. Therefore, the filament 14 is not likely to sharply heat up due to the current sharply flowing through the filament 14. Therefore, evaporation of the filament 14 due to the heat is likely to be suppressed. Therefore, the filament 14 is not likely to break. Therefore, the life of the filament 14 is likely to be long.

[0109] Figure 14 is a graph showing another example of the relationship between the polarity of the direct current and the time t. In this example, the power supply section 20 starts to supply the direct current of the first polarity at time tc1 and starts to supply the direct current of the second polarity at time tc2. In this example, the power supply section 20 supplies the direct current of the first polarity for a first period Tc1 and supplies the direct current of the second polarity for a second period Tc2. In this example, the concentration measuring section 50 (see Figure 1A ) measures the first concentration of the measurement target gas 90 for the first period Tc1 and measures the second concentration of the measurement target gas 90 for the second period Tc2.

[0110] Figure 15 is a graph showing another example of the relationship between the polarity of the direct current and the time t. The concentration measuring section 50 (see Figure 1A ) can correct at least one of the first period Tc1 and the second period Tc2 based on the first concentration and the second concentration. For example, the concentration measuring section 50 corrects the first period Tc1 to be short and the second period Tc to be long based on the first concentration and the second concentration. In Figure 15 , the first period Tc1' is the corrected first period Tc1 and the second period Tc2' is the corrected second period Tc2. In Figure 15 , the first period Tc1' is the period from time tc3 to time tc4 and the second period Tc2' is the period from time tc4 to time tc5. In Figure 15 , the first period Tc1 and the second period Tc2 in Figure 14 are indicated by thick broken lines.

[0111] The concentration measurement section 50 ideally has the same concentration measurement result for the measurement target gas 90 regardless of the polarity of the direct current. However, depending on the usage time of the gas sensor 100 in each polarity, there are cases in which the resistance value R of the filament 14 in each polarity differs from each other. In such a case, the current I flowing through the filament 14 in each polarity differs from each other. Due to this, there are cases in which the light emission amount of the light emitting element 10, the light emission intensity distribution of the filament emission site in each polarity differs from each other. Due to this, there are cases in which the concentration measurement result in each polarity differs from each other.

[0112] In Figure 15 the example, in a case in which the first concentration measured in the first period Tc1 is smaller than the second concentration measured in the second period Tc2, the light emission amount of the light emitting element 10 in the first polarity is likely to be smaller than the light emission amount of the light emitting element 10 in the second polarity. Therefore, the resistance value R of the filament 14 in the first polarity is likely to be higher than the resistance value R of the filament 14 in the second polarity. Therefore, in terms of the life of the filament 14, the first polarity is likely to be shorter than the second polarity. In such a case, the concentration measurement section 50 can make the first period Tc1' shorter than the first period Tc1 by correcting the first period Tc1. The concentration measurement section 50 can make the second period Tc2' longer than the first period Tc2 by correcting the second period Tc2. Also, in a case in which the first concentration measured in the first period Tc1 is larger than the second concentration measured in the second period Tc2, the concentration measurement section 50 can make the first period Tc1' longer than the first period Tc1 by correcting the first period Tc1, and can make the second period Tc2' shorter than the first period Tc2 by correcting the second period Tc2.

[0113] Figure 16 is another example of a graph indicating the relationship between the polarity of the direct current and the time t. In the present example, the period from the time tg1 to the time tg2 is the first period Tg1, the period from the time tg2 to the time tg3 is the third period Tg3, and the period from the time tg3 to the time tg4 is the second period Tg2. In the present example, in the first period Tg1 and the second period Tg2, the first terminal Ev1 (refer to Figure 2 and Figure 3 ) is maintained at the first potential V1, and the second terminal Ev2 (refer to Figure 2 and Figure 3 ) is maintained at the second potential V2. That is, in the present example, in the first period Tg1 and the second period Tg2, the power supply section 20 supplies the direct current of either one of the first polarity and the second polarity. In Figure 16 the example, the power supply section 20 supplies the direct current of the first polarity in the first period Tg1, and supplies the direct current of the second polarity in the second period Tg2.

[0114] In the third period Tg3, the first terminal Evl (refer to Figure 2 and Figure 3 ) can be maintained at the first potential VI, and the second terminal Ev2 (refer to Figure 2 and Figure 3 ) can be maintained at the first potential VI or more and less than the second potential V2. In the third period Tg3, the power supply portion 20 can supply direct current power when the second terminal Ev2 is maintained at the first potential VI or more and less than the second potential V2. In Figure 16 , the first terminal Evl and the second terminal Ev2 are maintained at the first potential VI, and the first potential VI is 0 V. Therefore, in the example of Figure 16 , the power supply portion 20 does not supply direct current power in the third period Tg3.

[0115] The concentration measuring portion 50 can measure the concentration of the measurement target gas 90 based on the first intensity of the light 12 received by the first light receiving element 52 in the first period Tgl and the third intensity of the light 12 received by the first light receiving element 52 in the third period Tg3. For example, the concentration measuring portion 50 calculates the concentration of the measurement target gas 90 based on the difference (first intensity - third intensity) between the first intensity of the light 12 measured in the first period Tgl and the third intensity of the light 12 measured in the third period Tg3. The concentration measuring portion 50 can calculate the concentration of the measurement target gas 90 based on the ratio (first intensity / third intensity) between the first intensity of the light 12 measured in the first period Tgl and the third intensity of the light 12 measured in the third period Tg3.

[0116] In the example of Figure 16 , the power supply portion 20 does not supply direct current power in the third period Tg3. Therefore, the concentration of the measurement target gas 90 in the third period Tg3 can be zero. However, sometimes the first light receiving element 52 receives light other than the light 12 emitted by the light emitting element 10 (refer to Figure 1A ), and thereby measures the third intensity as a value other than zero. In this case, even if direct current power is not supplied in the third period Tg3, the concentration measuring portion 50 sometimes measures the concentration of the measurement target gas 90 as a value other than zero. Therefore, the concentration measuring portion 50 measures the concentration of the measurement target gas 90 based on the first intensity of the light 12 received by the first light receiving element 52 in the first period Tgl and the third intensity of the light 12 received by the first light receiving element 52 in the third period Tg3, and thereby can measure the accurate concentration of the measurement target gas 90.

[0117] The power supply section 20 can also supply direct current electric power at which the second terminal Ev2 is maintained at greater than the first potential VI and less than the second potential V2 during the third period Tg3. In this case, the power supply section 20 supplies direct current electric power that is less than the direct current electric power at which the first terminal Evl is maintained at the first potential VI and the second terminal Ev2 is maintained at the second potential V2. The third intensity can also be the intensity of the light 12 received by the first light-receiving element 52 when the power supply section 20 supplies such direct current electric power.

[0118] The concentration measuring section 50 can measure the concentration of the measurement target gas 90 based on the second intensity of the light 12 received by the first light-receiving element 52 during the second period Tg2 and the third intensity of the light 12 received by the first light-receiving element 52 during the third period Tg3. For example, the concentration measuring section 50 calculates the concentration of the measurement target gas 90 based on the difference (second intensity - third intensity) between the second intensity of the light 12 measured during the second period Tg2 and the third intensity of the light 12 measured during the third period Tg3. The concentration measuring section 50 can calculate the concentration of the measurement target gas 90 based on the ratio (second intensity / third intensity) between the second intensity of the light 12 measured during the second period Tg2 and the third intensity of the light 12 measured during the third period Tg3.

[0119] Figure 17 is a graph indicating an example of the relationship between the intensity Ir of the light 12 and the concentration of the measurement target gas 90. The intensity Ir of the light 12 and the concentration of the measurement target gas 90, for example, indicate the relationship shown in Figure 17 . The higher the concentration of the measurement target gas 90, the greater the amount of gas molecules absorbed by the gas molecules. Therefore, the intensity of the light 12 received by the first light-receiving element 52 (see Figure 1A ) easily becomes small. The lower the concentration of the measurement target gas 90, the smaller the amount of gas molecules absorbed by the gas molecules. Therefore, the intensity of the light 12 received by the first light-receiving element 52 easily becomes large. The relationship between the intensity Ir of the light 12 and the concentration of the measurement target gas 90 can be measured in advance. The relationship between the intensity Ir of the light 12 and the concentration of the measurement target gas 90 measured in advance can be stored in the storage section 54 (see Figure 1A ).

[0120] The intensity Ir of the light 12 can be the difference between the first intensity and the third intensity of the light 12, or can be the ratio between the first intensity and the third intensity of the light 12. The intensity Ir of the light 12 can depend on the temperature of the internal space 32 (see Figure 1A ). Therefore, the difference or the ratio between the first intensity and the third intensity can also be a difference or a ratio corrected according to the temperature of the internal space 32. The intensity Ir of the light 12 can be the difference between the second intensity and the third intensity of the light 12, or can be the ratio between the second intensity and the third intensity of the light 12. The difference or the ratio between the second intensity and the third intensity can also be a difference or a ratio corrected according to the temperature of the internal space 32.

[0121] The concentration measuring section 50 can measure the concentration of the measurement target gas 90 based on the difference or ratio of the first intensity of the first period Tg1 and the third intensity of the third period Tg3, and the relationship between the intensity Ir of the light 12 stored in the storage section 54 and the concentration of the measurement target gas 90. The concentration measuring section 50 can measure the concentration of the measurement target gas 90 based on the difference or ratio of the second intensity of the second period Tg2 and the third intensity of the third period Tg3, and the relationship between the intensity Ir of the light 12 stored in the storage section 54 and the concentration of the measurement target gas 90.

[0122] The second light receiving element 55 (refer to Figure 1B ) can be a reference element. The second light receiving element 55 receives the light 12 that has passed through the second optical filter 53. The second optical filter 53 is a filter that transmits the light 12 of a wavelength band that is not absorbed by the measurement target gas 90. The first light receiving element 52 receives the light 12 that has passed through the first optical filter 51. The first optical filter 51 is a filter that transmits the light 12 of a wavelength band that is absorbed by the measurement target gas 90. The concentration measuring section 50 can measure the concentration of the measurement target gas 90 based on the difference between the light receiving amount of the first light receiving element 52 and the light receiving amount of the second light receiving element 55. Thus, the concentration measuring section 50 can accurately measure the concentration of the measurement target gas 90.

[0123] The second light receiving element 55 (refer to Figure 1B ) can also be an element whose light receiving characteristics have been corrected. The light receiving characteristics of the first light receiving element 52 can change over time. The change over time refers to, for example, degradation over time. The concentration measuring section 50 can correct the light receiving characteristics of the first light receiving element 52 using the light receiving characteristics of the second light receiving element 55, and measure the concentration of the measurement target gas 90 based on the corrected light receiving characteristics. Thus, even if the light receiving characteristics of the first light receiving element 52 change over time, the concentration measuring section 50 can measure an accurate concentration.

[0124] The second light-receiving element 55 can also detect a gas different from the first light-receiving element 52. The first light-receiving element 52 can detect the measurement target gas 90, and the second light-receiving element 55 can detect a reference gas. The reference gas can be used to estimate the dilution rate of the measurement target gas 90. For example, the first light-receiving element 52 can detect light of a wavelength band corresponding to alcohol, and the second light-receiving element 55 can detect light of a wavelength band corresponding to carbon dioxide. The concentration of carbon dioxide contained in the breath of a person is substantially constant. Therefore, by detecting the concentration of carbon dioxide with the gas sensor 100, it is possible to estimate to what extent the breath has been diluted by the measurement target gas 90. Since it is assumed that the dilution rate of alcohol contained in the breath is equal to the dilution rate of carbon dioxide contained in the breath, it is possible to estimate the concentration of alcohol contained in the breath on the basis of the concentration of alcohol detected by the gas sensor 100 and the estimated dilution rate. In addition, the first light-receiving element 52 can detect light corresponding to carbon dioxide, and the second light-receiving element 55 can detect light corresponding to carbon monoxide, or the like, and the types of gas detected by each light-receiving element can be considered in various combinations.

[0125] The light-emitting characteristics of the light-emitting element 10 can change over time. The change over time is, for example, degradation over time. In a case where the light-emitting characteristics of the light-emitting element 10 change over time, the light-receiving amount of light received by the first light-receiving element 52 changes. In a case where the light-emitting characteristics of the light-emitting element 10 degrade, the light-receiving amount of light received by the first light-receiving element 52 decreases. Therefore, the concentration measuring unit 50 can measure the concentration of the measurement target gas 90 to be higher than the actual concentration. In a case where the light-emitting characteristics of the light-emitting element 10 increase due to aging or the like, the light-receiving amount of light received by the first light-receiving element 52 increases. Therefore, the concentration measuring unit 50 can measure the concentration of the measurement target gas 90 to be lower than the actual concentration. The concentration measuring unit 50 corrects the light-receiving characteristics of the first light-receiving element 52 using the light-receiving characteristics of the second light-receiving element 55, and measures the concentration of the measurement target gas 90 on the basis of the corrected light-receiving characteristics, whereby the concentration measuring unit 50 can accurately measure the concentration of the measurement target gas 90 even in a case where the light-emitting characteristics of the light-emitting element 10 change over time.

[0126] The intensity Ir of the light 12 can be the ratio of the first difference between the first intensity and the third intensity of the light 12 received by the first light-receiving element 52 and the second difference between the first intensity and the third intensity of the light 12 received by the second light-receiving element 55. The intensity Ir of the light 12 can also be the difference between the first difference and the second difference. The intensity Ir of the light 12 can also be the ratio of the third difference between the second intensity and the third intensity of the light 12 received by the first light-receiving element 52 and the fourth difference between the second intensity and the third intensity of the light 12 received by the second light-receiving element 55. The intensity Ir of the light 12 can also be the difference between the third difference and the fourth difference.

[0127] The concentration measuring section 50 can measure the concentration D1 of the measurement target gas 90 based on the first intensity and the third intensity of the light 12, and measure the concentration D2 of the measurement target gas 90 based on the second intensity and the third intensity of the light 12. The concentration measuring section 50 can measure the concentration of the measurement target gas 90 based on the concentration D1 and the concentration D2. For example, the concentration measuring section 50 can measure the average of the concentration D1 and the concentration D2 as the concentration of the measurement target gas 90. The concentration D1 and the concentration D2 are concentrations measured when direct current power of different polarities is supplied, respectively. Therefore, the concentration based on the concentration D1 and the concentration D2 can be a more accurate concentration than a concentration obtained by subtracting the third concentration from the first concentration or a concentration obtained by subtracting the third concentration from the second concentration.

[0128] The storage section 54 of the concentration measuring section 50 can store a correction curve indicating the relationship between the intensity of the light and the concentration as shown in Figure 17 for each polarity of the direct current power of the light emitting element 10. The concentration measuring section 50 can select the correction curve corresponding to the polarity of the direct current power of the light emitting element 10 when the first light receiving element 52 receives the light 12. The concentration measuring section 50 can calculate the concentration of the measurement target gas from the intensity of the light 12 based on the selected correction curve.

[0129] Figure 18 is another example of a graph indicating the relationship between the polarity of the direct current power and the time t. The time tg10, the time tg20, the time tg30, and the time tg40 in the present example are the same as the time tg1, the time tg2, the time tg3, and the time tg4, respectively, of Figure 16 . In the present example, the period S11 between the time tg10 and the time tg11, the period S13 between the time tg12 and the time tg13, the period S15 between the time tg14 and the time tg15, and the period S17 between the time tg16 and the time tg20 in the first period Tg1, the first terminal Ev1 (refer to Figure 2 and Figure 3 ) is maintained at the first potential V1, and the second terminal Ev2 (refer to Figure 2 and Figure 3 ) is maintained at the second potential V2. The period S11, the period S13, the period S15, and the period S17 are each an example of the first measurement period. In the first measurement period, the absolute value of the potential difference between the first terminal Ev1 and the second terminal Ev2 is maintained to be a first value or more. In the above example, the absolute value of the potential difference is maintained to be a constant |V1-V2|, but the absolute value of the potential difference can not be maintained to be a constant value. The first value can be, for example, 2 V, can be 3 V, or can be a value of 4 V or more. As Figure 18As shown, the first measurement period is repeated two or more times in one first period Tg1. In this example, in the period S12 between the time tg11 and the time tg12, the period S14 between the time tg13 and the time tg14, and the period S16 between the time tg15 and the time tg16 in the first period Tg1, the direct-current electric power is not supplied. The period S12, the period S14, and the period S16 are examples of the third measurement period. As shown, the third measurement period is a period different from the first measurement period. In this example, in the first period Tg1, the first measurement period and the third measurement period are alternately repeated. The lengths of the periods S11 to S17 can be equal to or different from each other. In the third measurement period, the absolute value of the potential difference between the first terminal Ev1 and the second terminal Ev2, that is, the third value, is maintained at 0 V or more and less than the first value. The third value can be maintained at 0 V or other values. The third value can be half or less of the first value. The third value can be a value of 1 V or less or a value of 0.5 V or less. Figure 18

[0130] In this example, in the period S21 between the time tg30 and the time tg31, the period S23 between the time tg32 and the time tg33, the period S25 between the time tg34 and the time tg35, and the period S27 between the time tg36 and the time tg40 in the second period Tg2, the first terminal Ev1 (see Figure 2 and Figure 3 ) is maintained at the first potential V1, and the second terminal Ev2 (see Figure 2 and Figure 3 ) is maintained at the second potential V2. The periods S21, S23, S25, and S27 are examples of the first measurement period, respectively. In this example, in the period S22 between the time tg31 and the time tg32, the period S24 between the time tg33 and the time tg34, and the period S26 between the time tg35 and the time tg36 in the second period Tg2, the direct-current electric power is not supplied. The periods S22, S24, and S26 are examples of the third measurement period. In this example, in the second period Tg2, the first measurement period and the third measurement period are alternately repeated. The lengths of the periods S21 to S27 can be equal to or different from each other.

[0131] The timing at which each first measurement period starts is referred to as a first timing. The start times tg10, tg12, tg14, and tg16 of the periods S11, S13, S15, and S17 are examples of the first timing. The start times tg30, tg32, tg34, and tg36 of the periods S21, S23, S25, and S27 are also examples of the first timing.

[0132] ​The timing at which each of the third measurement periods starts is set to the third timing. The start times tg11, tg13, tg15 of the period S12, the period S14, and the period S16 are examples of the third timing. The start times tg31, tg33, tg35 of the period S22, the period S24, and the period S26 are also examples of the third timing.

[0133] In the first period Tg1 or the second period Tg2, the first timing and the third timing are alternately arranged. Each of the first measurement periods can start at the first timing and end at the third timing. In addition, each of the third measurement periods can start at the third timing and end at the first timing. That is, the alternately arranged first measurement periods and the third measurement periods can be continuous to each other.

[0134] In this example, the power supply unit 20 supplies the direct-current electric power of the first polarity in the first period Tg1 and supplies the direct-current electric power of the second polarity in the second period Tg2. In the third period Tg3, the first terminal Ev1 (refer to Figure 16 , the first terminal Ev1 (refer to Figure 2 , and the second terminal Ev2 (refer to Figure 3 ) can be maintained at the first potential V1, and the second terminal Ev2 (refer to Figure 2 , and the second terminal Ev2 (refer to Figure 3 ) can be maintained at the first potential V1 or more and less than the second potential V2.

[0135] The concentration measurement unit 50 can measure the concentration of the measurement target gas 90 based on the first intensity of the light 12 received by the first light-receiving element 52 in any one of the period S11, the period S13, the period S15, and the period S17 and the third intensity of the light 12 received by the first light-receiving element 52 in any one of the period S12, the period S14, and the period S16. The concentration measurement unit 50 can measure the concentration of the measurement target gas 90 based on the first intensity of the light 12 received by the first light-receiving element 52 in any one of the period S21, the period S23, the period S25, and the period S27 and the third intensity of the light 12 received by the first light-receiving element 52 in any one of the period S22, the period S24, and the period S26. As in the example of Figure 16 , the concentration measurement unit 50 can calculate the concentration of the measurement target gas 90 based on the difference between the first intensity and the third intensity of the light 12 or can calculate the concentration of the measurement target gas 90 based on the ratio between the first intensity and the third intensity of the light 12.

[0136] The time tg10 in this example is, for example, the timing at which the key switch is turned on or the timing at which the button is activated for the (2m - 1)th time described above. The time tg30 in this example is, for example, the timing at which the key switch is turned on or the timing at which the button is activated for the 2mth time described above. The third period Tg3 in this example is, for example, a period in which the key switch is turned off or the button is not activated.

[0137] Figure 19 is an example of a graph showing the relationship between the intensity of light 12 received by the first light-receiving element 52 and the time t. The periods S11 to S17 and the periods S21 to S27 are the same as the example of Figure 18 The periods S11 to S17 and the periods S21 to S27 are each set for a predetermined period T delay The periods S11' to S17' and the periods S21' to S27' are set for the periods T delay The period T

[0138] In the first period Tg1, the periods S11', S13', S15', and S17' are each an example of a second measurement period. Each of the second measurement periods starts at a second timing after a first timing (e.g., time tg10) at which the first measurement period starts and before a third timing (e.g., time tg11) at which the next third measurement period starts. In the example of Figure 19 In the example of

[0139] In the first period Tg1, the periods S12', S14', and S16' are each an example of a fourth measurement period. Each of the fourth measurement periods starts after the end of the second measurement period and before a fourth timing (e.g., tg11) after the third timing (e.g., tg11) and before the next first timing (e.g., tg12) at which the first measurement period starts again. In the example of Figure 19 In the example of

[0140] In the second period Tg2, the periods S21', S23', S25', and S27' are each an example of a second measurement period. In addition, the times tg30', tg32', tg34', and tg36' correspond to the second timing. The periods S22', S24', and S26' are each an example of a fourth measurement period. In addition, the times tg31', tg33', and tg35 correspond to the fourth timing.

[0141] In the first period Tg1 or the second period Tg2, the second timing and the fourth timing are alternately arranged. In the example of Figure 19In the example of FIG. 10, the first timing, the second timing, the third timing, and the fourth timing are sequentially repeated two or more times in the first period Tg1 or the second period Tg2. Each of the second measurement periods can start at the second timing and end at the fourth timing. Alternatively, each of the fourth measurement periods can start at the fourth timing and end at the second timing. That is, the second measurement periods and the fourth measurement periods, which are alternately arranged, can be continuous to each other.

[0142] The concentration measuring section 50 can measure the concentration of the measurement target gas 90 based on the second intensity of the light received by the first light-receiving element 52 during the second measurement period (e.g., S11') starting at the second timing (e.g., tg10') and the fourth intensity of the light received by the first light-receiving element 52 during the fourth measurement period (e.g., S12') starting at the fourth timing (e.g., tg11'). For example, the concentration measuring section 50 calculates the concentration of the measurement target gas 90 based on the difference between the second intensity and the fourth intensity (second intensity - fourth intensity). The concentration measuring section 50 can calculate the concentration of the measurement target gas 90 based on the ratio between the second intensity and the fourth intensity (second intensity / fourth intensity).

[0143] The concentration measuring section 50 of the present example measures the concentration of the measurement target gas 90 based on the second intensity of the light received by the first light-receiving element 52 during any one of the periods S11', S13', S15', and S17' and the fourth intensity of the light received by the first light-receiving element 52 during any one of the periods S12', S14', and S16'. The concentration measuring section 50 can measure the concentration of the measurement target gas 90 based on the second intensity of the light received by the first light-receiving element 52 during any one of the periods S21', S23', S25', and S27' and the fourth intensity of the light received by the first light-receiving element 52 during any one of the periods S22', S24', and S26'.

[0144] Even if the direct-current electric power of the first polarity is supplied at the time tg10, there is sometimes a delay time until the light amount of the filament 14 increases to a desired light amount or temperature. This delay time is set as a first delay time. The first desired light amount or temperature is, for example, a light amount or temperature corresponding to the value of the direct-current electric power. The period T delay The first delay time can be equal to the second delay time. The same applies to the times tg12, tg14, tg16, tg30, tg32, tg34, and tg36.

[0145] Even if the supply of direct-current electric power of the first polarity is started to be stopped at the time tg11, there is sometimes a delay time until the light amount of the filament 14 decreases to a desired light amount or temperature. This delay time is set to a second delay time. The desired light amount or temperature is, for example, a light amount or temperature corresponding to a value of zero of the direct-current electric power, respectively. The period T delay may be equal to the second delay time. The same applies to the times tg13, tg15, tg17, tg31, tg33, tg35, and tg37. The period T delay may be different from the period T delay , and can be equal.

[0146] In a case where there is the first delay time until the light amount of the filament 14 increases to the desired light amount, or the second delay time until the light amount decreases to the desired light amount, the concentration measuring section 50 can measure the concentration of the measurement target gas 90 based on the first intensity of the light 12 accepted by the first light receiving element 52 in any one of the periods S11', S13', S15', and S17', and the third intensity of the light 12 accepted by the first light receiving element 52 in any one of the periods S12', S14', and S16'. Thus, the concentration measuring section 50 can more accurately measure the concentration of the measurement target gas 90.

[0147] In the first period Tg1 or the second period Tg2, the first measurement period can be repeated two or more times at a frequency of 0.1 Hz or more. In Figure 19 , in the first period Tg1, the four first measurement periods (periods S11, S13, S15, S17) are repeated at a frequency of 0.1 Hz or more. In the second period Tg2, the four first measurement periods (periods S21, S23, S25, S27) are also repeated at a frequency of 0.1 Hz or more. The repetition frequency of the first measurement period can be 0.5 Hz or more, can be 1 Hz or more, or can be 10 Hz or more. The repetition frequency can be 100 Hz or less.

[0148] In the detection of the measurement target gas, the faster the driving cycle of the gas sensor 100, the more accurately the variation in the gas concentration can be measured. As an example, in the gas sensor 100 that detects alcohol, it is preferable that the driving cycle be fast. On the other hand, if the driving cycle of the gas sensor 100 is made faster, the light emission of the filament of the light emitting element 10 becomes difficult to stabilize. As described above, in Figure 18 and Figure 19 , the measurement timing (second timing) of the first light receiving element 52 is delayed from the light emission start timing (first timing) of the light emitting element 10. Thus, the concentration measuring section 50 can more accurately measure the concentration of the measurement target gas 90.

[0149] The gas sensor 100 can also put the measurement of the first light-receiving element 52 into standby mode until the light emission of the light-emitting element 10 stabilizes. The gas sensor 100 can also set the aforementioned delay times to stabilize the light emission of the light-emitting element 10.

[0150] Gas sensor 100 can also Figure 19 Each delay time described herein is set to 0. That is, the third timing can be made consistent with the first timing, and the fourth timing can be made consistent with the second timing. In this case, the concentration measuring unit 50 can measure the concentration of the target gas 90 based on the first intensity of light received by the first light receiving element 52 during the first measurement period (e.g., S11) and the third intensity of light received by the first light receiving element 52 during the third measurement period (e.g., S12).

[0151] In the examples described in this specification, the first period Tg1, the second period Tg2, and the third period Tg3 of the first light-receiving element 52 and the second light-receiving element 55 may be the same. On the other hand, the periods, moments, and delay times included in the first period Tg1, the second period Tg2, and the third period Tg3 may also differ between the first light-receiving element 52 and the second light-receiving element 55. For example, Figure 19 In the example, the length of at least one of the second measurement period (e.g., period S11', period S13', period S15', period S17') and the fourth measurement period (e.g., period S12', period S14', period S16') may differ in the first light-receiving element 52 and the second light-receiving element 55. At least one of the second timing at the start of the second measurement period and the fourth timing at the start of the fourth measurement period may differ in the first light-receiving element 52 and the second light-receiving element 55. The frequency bands traversed by the first optical filter 51 of the first light-receiving element 52 and the second optical filter 53 of the second light-receiving element 55 may be different.

[0152] The emission spectrum varies depending on the temperature of the filament of the light-emitting element 10. Since the first light-receiving element 52 and the second light-receiving element 55 detect different wavelengths, the delay time or output current until emission from the light-emitting element 10 differs. Therefore, the optimal settings for the parameters of each period, time, and delay time included in the first period Tg1, the second period Tg2, and the third period Tg3 may sometimes differ between the first light-receiving element 52 and the second light-receiving element 55. By adjusting these parameters in each light-receiving element, the concentration of the target gas 90 can be measured more accurately.

[0153] For example, the infrared absorption wavelength of alcohol is around 3.3 μm, and the absorption wavelength of carbon dioxide is around 4.3 μm. Each light-receiving element is designed in correspondence with them. The light emission spectrum characteristics of the filament of the light-emitting element 10 depend on the temperature of the filament. Carbon dioxide can be detected on the basis of light emission at a lower temperature of the filament, compared with alcohol.

[0154] In a case where the measurement target gas 90 is carbon dioxide, the first light-receiving element 52 can detect carbon dioxide, and the second light-receiving element 55 can detect a reference gas. The reference gas can be a gas whose concentration is known or hardly changes. By adjusting the above-described parameters for the first light-receiving element 52 and the second light-receiving element 55, the concentration of carbon dioxide can be accurately measured.

[0155] The measurement target gas 90 can also be alcohol and carbon dioxide. For example, the gas sensor 100 can be used to detect the drinking state of a subject. The first light-receiving element 52 can detect alcohol, and the second light-receiving element 55 can detect carbon dioxide. By adjusting the above-described parameters for the first light-receiving element 52 and the second light-receiving element 55, the concentrations of alcohol and carbon dioxide can be accurately measured, respectively. Thus, the detection accuracy of the drinking state can be improved.

[0156] Figure 20 is a diagram illustrating an example of a power supply system 300 according to an embodiment of the present application. In this example, the light-emitting element 10 is a light bulb provided in a room.

[0157] The power supply system 300 includes a power supply unit 20 and a switching unit 40. The power supply system 300 can include the light-emitting element 10. The power supply unit 20 supplies direct-current power to the light-emitting element 10. The light-emitting element 10 is of a heat radiation type having a filament 14. The switching unit 40 switches the polarity of the direct-current power on the basis of a set condition. The light-emitting element 10, the power supply unit 20, and the switching unit 40 can be connected as illustrated in a circuit diagram as illustrated in Figure 2 or Figure 3 The same operation as that described in the gas sensor 100 in Figures 4-19 can be realized in the power supply system 300.

[0158] The light-emitting element 10 can also be a light bulb for a warning light in a road or a building. The power supply unit 20 in the power supply system 300 can supply direct-current power to such a light-emitting element 10. The switching unit 40 in the power supply system 300 can switch the polarity of the direct-current power on the basis of a set condition.

[0159] Figure 21 is a flowchart illustrating an example of a gas concentration measurement method according to an embodiment of the present application. The gas concentration measurement method is performed by the gas sensor 100. Figures 1A-19The gas sensor shown is an example of a gas concentration measurement method. The gas concentration measurement method includes a power supply stage S100, a switching stage S110, and a concentration measurement stage S120.

[0160] The power supply stage S100 is a stage in which the power supply unit 20 supplies direct current to the heat radiation type light emitting element 10 having the filament 14. The light emitting element 10 emits light 12 that irradiates the measurement target gas 90. The switching stage S110 is a stage in which the switching unit 40 switches the polarity of the direct current based on a set condition. The concentration measurement stage S120 is a stage in which the concentration of the measurement target gas 90 irradiated with the light 12 is measured.

[0161] The above describes the present application using embodiments, but the technical scope of the present application is not limited to the scope described in the above embodiments. It is apparent for those skilled in the art that various changes or modifications can be made to the above embodiments. The embodiments to which such changes or modifications are applied are also included in the technical scope of the present application according to the recitations of the claims.

[0162] Note that the order of execution of each process such as actions, processes, steps, and stages in the apparatus, system, program, and method shown in the claims, specification, and drawings can be implemented in any order as long as it is not specifically indicated as "before," "after," and the like, and as long as the output of the previous process is not used in the subsequent process. Regarding the flow of actions in the claims, specification, and drawings, even if it is described using "first," "next," and the like for convenience, it does not mean that it must be implemented in that order.

Claims

1. A breath sensor, comprising: The light source section includes a heat-radiating light-emitting element containing a filament, which illuminates light directed towards the gas being measured in relation to exhalation; and The concentration measuring unit has a light-receiving element that receives at least a portion of the light, and measures the concentration of the gas to be measured. The light source unit has a first terminal and a second terminal. The light-emitting element is supplied with DC power from the first terminal and the second terminal, the polarity of which is switched based on set conditions. During the first measurement, which is performed twice or more while supplying DC power to the light-emitting element, the absolute value of the potential difference between the first terminal and the second terminal remains above a first value. During a third measurement period different from the first measurement period, a third value, which is the absolute value of the potential difference between the first terminal and the second terminal, is maintained above 0V and below the first value. The concentration measuring unit measures the concentration of the target gas based on the second intensity of the light received by the light-receiving element during the second measurement period and the fourth intensity of the light received by the light-receiving element during the fourth measurement period. The second measurement period begins at a second timing interval, which is after the first timing interval at which the first measurement period begins and before the third timing interval at which the third measurement period begins. The fourth measurement period begins at the fourth timing, which ends after the second measurement period and precedes the next first timing after the third timing and before the first measurement period begins again.

2. The exhalation sensor according to claim 1, wherein, The first measurement was repeated at least twice at a frequency of 0.1 Hz or higher.

3. The exhalation sensor according to claim 1, wherein, Based on the number of times the exhalation sensor is activated, the first polarity, which is one polarity, and the second polarity, which is the other polarity, are switched.

4. The exhalation sensor according to claim 1, wherein, Based on the number of times the light-emitting element is activated, the first polarity, which is one polarity, and the second polarity, which is the other polarity, are switched.

5. The exhalation sensor according to claim 1, wherein, Based on the supply time of the DC power, the first polarity, which is one side of the polarity, and the second polarity, which is the other side, are switched.

6. The exhalation sensor according to claim 1, wherein, Based on the activation time of the exhalation sensor, the first polarity, which is one polarity, and the second polarity, which is the other polarity, are switched.

7. The exhalation sensor according to claim 1, wherein, The breath sensor also includes a resistance acquisition unit that acquires the resistance value of the light-emitting element. The breath sensor switches between a first polarity (as one polarity) and a second polarity (as the other polarity) based on the resistance value.

8. The exhalation sensor according to claim 1, wherein, Based on the temperature or humidity of the object being measured, which contains the gas being measured, the first polarity, which is one polarity, and the second polarity, which is the other polarity, are switched.

9. The exhalation sensor according to any one of claims 1 to 8, wherein, The DC power is supplied by a constant voltage power source. The constant voltage power supply has the first terminal and the second terminal. The constant voltage power supply maintains the first terminal at a first potential and the second terminal at a second potential that is higher than the first potential, and uses the potential difference between the first and second potentials to supply the DC power. The constant voltage power supply causes the potential difference to increase in a stepwise manner.

10. The exhalation sensor according to any one of claims 1 to 8, wherein, The DC power is supplied by a constant current power source.

11. The breath sensor according to any one of claims 1 to 8, wherein, The concentration of the target gas measured during the first polarity period, which is one of the polarities, is designated as the first gas concentration; the concentration of the target gas measured during the second polarity period, which is the other polarity, is designated as the second gas concentration. The concentration measuring unit calculates the concentration of the target gas by correcting at least one of the first gas concentration and the second gas concentration based on the first gas concentration measured during the first polarity period and the second gas concentration measured during the second polarity period.

12. The exhalation sensor according to any one of claims 1 to 8, wherein, The concentration measuring unit stores a calibration curve representing the relationship between the light intensity and the concentration for each polarity of the DC power of the light-emitting element, and calculates the concentration of the gas to be measured based on the calibration curve corresponding to the polarity.

13. The exhalation sensor according to any one of claims 1 to 8, wherein, The breath sensor has two or more of the aforementioned light-receiving elements. In the concentration measuring unit, at least one of the lengths of the second measuring period and the fourth measuring period is different in each of the light-receiving elements.

14. The exhalation sensor according to any one of claims 1 to 8, wherein, The breath sensor has two or more of the aforementioned light-receiving elements. In the concentration measuring unit, at least one of the second timing, which is the start time of the second measurement period, and the fourth timing, which is the start time of the fourth measurement period, is different in each of the light-receiving elements.

15. A method for measuring exhalation, comprising: During the power supply phase, DC power is supplied to a light source unit including a thermal radiation type light-emitting element with a filament and having a first terminal and a second terminal, and the light-emitting element emits light that irradiates the gas of the test subject associated with exhalation. and In the concentration measurement stage, a light-receiving element that receives at least a portion of the light is used to measure the concentration of the gas to be measured after being irradiated by the light. DC power with switching polarity is supplied to the light-emitting element from the first terminal and the second terminal based on set conditions. During the first measurement, which is performed twice or more while supplying DC power to the light-emitting element, the absolute value of the potential difference between the first terminal and the second terminal is maintained at or above a first value. During a third measurement period different from the first measurement period, a third value, which is the absolute value of the potential difference between the first terminal and the second terminal, is maintained at 0V or higher and less than the first value. The concentration of the target gas is determined based on the second intensity of the light received by the light-receiving element during the second measurement period and the fourth intensity of the light received by the light-receiving element during the fourth measurement period. The second measurement period begins at a second timing interval, which is after the first timing interval at which the first measurement period begins and before the third timing interval at which the third measurement period begins. The fourth measurement period begins at the fourth timing, which ends after the second measurement period and precedes the next first timing after the third timing and before the first measurement period begins again.

16. A breath sensor, comprising: The light source section includes a heat-radiating light-emitting element containing a filament, which illuminates light directed towards the gas being measured in relation to exhalation; and The concentration measuring unit has a light-receiving element that receives at least a portion of the light, and measures the concentration of the gas to be measured. The light source unit has a first terminal and a second terminal. The light-emitting element is supplied with DC power from the first terminal and the second terminal, the polarity of which is switched based on set conditions. During the first measurement, which is performed twice or more while supplying DC power to the light-emitting element, the absolute value of the potential difference between the first terminal and the second terminal remains above a first value. During a third measurement period different from the first measurement period, a third value, which is the absolute value of the potential difference between the first terminal and the second terminal, is maintained above 0V and below the first value. The concentration measuring unit measures the concentration of the target gas based on a first intensity of light received by the light-receiving element during the first measurement and a third intensity of light received by the light-receiving element during the third measurement.

Images