Gas detector and gas sensor life determination method

Abstract

A gas detector capable of accurately determining the life of a sensor unit is provided. [Solution] This gas detector 100 is a gas detector that detects a target gas, and comprises a sensor section 1 including multiple gas sensors 10 of the same type mounted on the same substrate 14, and a control section 2 that acquires output values ​​30 of the multiple gas sensors 10, and the control section 2 is configured to make a judgment regarding the lifespan of the sensor section 1 based on the output values ​​30 of the multiple gas sensors 10.

Description

[Technical Field]

[0001] The present invention relates to a gas detector and a method for determining the lifespan of a gas sensor. [Background technology]

[0002] BACKGROUND ART Gas detectors have been known in the past (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses a gas detection device (gas detector) including a gas detection section including a gas sensor unit having one gas sensor, and a control section. In this gas detector, the control section is configured to predict the useful life (use limit) of the gas sensor based on calibration history data of the gas sensor. Specifically, the control section acquires a time-dependent sensitivity decay characteristic curve specific to the gas sensor based on the calibration history data of the gas sensor. Then, based on the acquired time-dependent sensitivity decay characteristic curve, the control section acquires a specific decay time point at which the sensitivity value (threshold value) of the gas sensor becomes a specific ratio of the initial sensitivity value of the gas sensor. Then, when the control section detects during a calibration process of the gas sensor that the sensitivity value of the gas sensor is equal to or less than the threshold value, it determines that the useful life of the gas sensor has arrived. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-094616 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, a gas detection device (gas detector) is a safety device, and information regarding the lifespan of the sensor unit, which is the core of this safety device, is important information. However, in the gas detection device (gas detector) described in Patent Document 1, the service life (lifespan) of the gas sensor is determined based on calibration history data of the gas sensor acquired during calibration. Therefore, the timing at which lifespan can be determined is limited to calibration, which makes it difficult to accurately determine the lifespan of the sensor unit, which is an inconvenience. Therefore, there is a demand for a gas detector and a method for determining the lifespan of a gas sensor that can accurately determine the lifespan of the sensor unit.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a gas detector and a method for determining the lifespan of a gas sensor that can accurately determine the lifespan of a sensor unit. [Means for solving the problem]

[0007] In order to achieve the above object, a gas detector according to a first aspect of the present invention is a gas detector for detecting a gas to be detected, comprising: a sensor unit including a plurality of gas sensors of the same type provided on the same chip; and a control unit for acquiring output values ​​of the plurality of gas sensors, 、 Output values ​​of multiple gas sensors Based on the above, the deterioration of each of the plurality of gas sensors is determined, and the deterioration of the plurality of gas sensors is calculated. Condition status The life of the sensor unit is determined based on the above.

[0008] In the gas detector according to the first aspect of the present invention, the control unit calculates output values ​​of the plurality of gas sensors. Based on the above, the deterioration of each of the plurality of gas sensors is determined, and the deterioration of the plurality of gas sensors is calculated. Condition statusThe life of the sensor unit is determined based on the output values ​​of the multiple gas sensors. This differs from a configuration in which the life of the sensor unit is determined based on the calibration history data of the gas sensor. By providing multiple gas sensors, the life of the sensor unit can be determined based on information within the gas detector, such as output values ​​of the multiple gas sensors, without having to acquire calibration history data through a calibration process or other process. As a result, the life of the sensor unit can be determined with high accuracy. The life of the sensor unit has the same meaning as the remaining life, which indicates how much the sensor unit can be used in the future. Furthermore, determining the life of the sensor unit means determining how close the sensor unit is to reaching the limit of its life. In other words, determining the life of the sensor unit means determining how much longer the sensor unit can be used.

[0010] this A gas detector according to a second aspect of the invention comprises: , A gas detector for detecting a gas to be detected, comprising: a sensor unit including a plurality of gas sensors of the same type provided on the same chip; and a control unit for acquiring output values ​​of the plurality of gas sensors; The control unit is configured to determine whether or not each of the multiple gas sensors has deteriorated based on the output values ​​of the multiple gas sensors, and to make a determination regarding the lifespan of the sensor unit based on the number of gas sensors in which deterioration has occurred. This Since the presence or absence of deterioration in each of the multiple gas sensors is determined based on the output values ​​of the multiple gas sensors, by obtaining the number of gas sensors in which deterioration has occurred, it is possible to easily and accurately determine the lifespan of the sensor unit.

[0011] A gas detector according to a third aspect of the present invention comprises: , A gas detector for detecting a gas to be detected, comprising: a sensor unit including a plurality of gas sensors of the same type provided on the same chip; and a control unit for acquiring output values ​​of the plurality of gas sensors; The control unit is configured to determine whether or not each of the multiple gas sensors has deteriorated based on the output values ​​of the multiple gas sensors, to correct the gas sensor that has deteriorated based on the output values ​​of the multiple gas sensors, and to determine the lifespan of the sensor unit based on the state of the correction. This Since the deteriorated gas sensor is corrected, the life of the gas sensor can be extended. Furthermore, since the life of the sensor unit is determined based on the state of correction, the life of the sensor unit can be determined with high accuracy even in a configuration in which the life of the gas sensor is extended by correcting the gas sensor.

[0012] In this case, the control unit is preferably configured to determine the lifespan of the sensor unit based on at least one of the number of corrections or the magnitude of the correction value when the correction is performed. With this configuration, the lifespan of the sensor unit can be easily determined by obtaining at least one of the number of corrections or the magnitude of the correction value.

[0013] A gas detector according to a fourth aspect of the present invention comprises: , A gas detector for detecting a gas to be detected, comprising: a sensor unit including a plurality of gas sensors of the same type provided on the same chip; and a control unit for acquiring output values ​​of the plurality of gas sensors; The control unit 、 Output values ​​of a plurality of gas sensors and Includes usage and driving history for each The life of the sensor unit is determined based on the history information. This The lifespan of the sensor unit can be comprehensively determined based on the output values ​​of the plurality of gas sensors as well as the history information of the plurality of gas sensors. As a result, in a configuration that can extend the lifespan of the gas sensor, the lifespan of the sensor unit can be determined with even greater accuracy.

[0014] This invention No. 5 Gas detection by aspect The vessel , A gas detector for detecting a gas to be detected, comprising: a sensor unit including a plurality of gas sensors of the same type provided on a single chip; and a control unit for acquiring output values ​​of the plurality of gas sensors. An alarm unit that can notify the result of the sensor unit's lifespan determination and picture, the control unit is configured to determine the life of the sensor unit based on output values ​​of the plurality of gas sensors; The notification unit is configured to change the content of notification depending on the result of the determination regarding the life of the sensor unit. This Since the result of the lifespan determination of the sensor unit is notified, the user can easily grasp the lifespan of the sensor unit, thereby improving usability for the user.

[0015] The first aspect of this invention 6 The method for determining a lifetime of a gas sensor according to this aspect includes the steps of: acquiring output values ​​of a plurality of gas sensors of a sensor unit including a plurality of gas sensors of the same type provided on a single chip; determining deterioration of each of the plurality of gas sensors based on output values ​​of the plurality of gas sensors; Multiple gas sensors State of deterioration and determining the lifespan of the sensor unit based on the result.

[0016] The first aspect of this invention 6 In the method for determining the lifespan of a gas sensor according to the above aspect, determining deterioration of each of the plurality of gas sensors based on output values ​​of the plurality of gas sensors; Multiple gas sensors State of deterioration A step of determining the lifespan of the sensor unit based on the and This makes it possible to provide a method for determining the lifespan of a gas sensor that can accurately determine the lifespan of the sensor portion, similar to the gas detector according to the first aspect. [Effects of the Invention]

[0017] As described above, the present invention can provide a gas detector and a method for determining the lifespan of a gas sensor that can accurately determine the lifespan of a sensor portion. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a block diagram showing the control configuration of the gas detector according to the first embodiment. [Figure 2] 1 is a circuit diagram showing an example of the configuration of a gas sensor of a gas detector according to a first embodiment. FIG. [Figure 3] FIG. 1 is a schematic plan view showing an example of the configuration of a gas sensor of a gas detector according to a first embodiment. [Figure 4] 1 is a schematic cross-sectional view showing an example of the configuration of a gas sensor of a gas detector according to a first embodiment. FIG. [Figure 5] 5 is a graph illustrating a configuration in which a control unit of the gas detector according to the first embodiment determines whether or not deterioration has occurred in the gas sensor. [Figure 6] 5 is a flowchart for explaining a method for determining the life span of a gas sensor in the gas detector according to the first embodiment. [Figure 7] FIG. 10 is a block diagram showing the control configuration of a gas detector according to a second embodiment. [Figure 8] 10 is a graph illustrating a configuration in which a control unit of a gas detector according to a second embodiment corrects a deteriorated gas sensor. [Figure 9]10 is a flowchart for explaining a method for determining the life span of a gas sensor in the gas detector according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] [First embodiment] The configuration of a gas detector 100 according to a first embodiment of the present invention will be described with reference to FIGS.

[0021] (Gas detector configuration) The gas detector 100 of the first embodiment is a gas detector that detects a detection target gas. When the gas detector 100 detects the detection target gas, it outputs an alarm to notify the user of a gas leak or the like. The detection target gas is a gas that the gas detector 100 is to detect. For example, the detection target gas is a fuel gas (city gas) containing methane gas as a main component.

[0022] 1, the gas detector 100 includes a sensor unit 1, a control unit 2, an alarm unit 3, a memory unit 4, multiple amplifiers 5, and a communication unit 6. The multiple gas sensors 10, the control unit 2, the alarm unit 3, and the communication unit 6 are housed within a housing of the gas detector 100. The gas detector 100 operates on power supplied from a commercial power source or on power from a battery (not shown).

[0023] The sensor unit 1 includes a plurality of gas sensors 10 of the same type. The sensor unit 1 detects a single type of target gas. In the example shown in FIG. 1, the sensor unit 1 includes gas sensors 10a to 10c. The sensor unit 1 outputs output values ​​30 of the plurality of gas sensors 10 to an amplifier 5. For convenience, FIG. 1 shows only one of the plurality of gas sensors 10 as outputting an output value 30, but the other gas sensors 10 also output output values ​​30 in the same manner.

[0024] Each of the gas sensors 10 includes a sensitive portion 11 and a heating portion 12 that heats the sensitive portion 11 to a predetermined temperature. The output values ​​30 of the gas sensors 10 are input to corresponding amplifiers 5. Each of the gas sensors 10 is a microelectromechanical systems (MEMS) gas sensor. The gas sensors 10 are fabricated using MEMS technology, which forms a mechanical structure in a semiconductor substrate using a semiconductor manufacturing process. For example, each of the gas sensors 10 has a side length of approximately 0.1 mm. While FIG. 1 illustrates the sensitive portion 11 and heating portion 12 only for the gas sensor 10a for convenience, the gas sensors 10b and 10c also include the sensitive portion 11 and heating portion 12.

[0025] Each of the gas sensors 10 includes a measurement circuit as shown in Fig. 2. The measurement circuit includes sensor elements 13a to 13c, opposite-side resistors R1, R2, R4, R5, R7, and R8, and load resistors R3, R6, and R9.

[0026] A voltage is applied to the sensor element 13a, the resistors R1 and R2, and the load resistor R3 from a power source E. An output value 30 (see FIG. 1) is output from a terminal A1 connected between the sensor element 13a and the load resistor R3, and a terminal A2 connected between the resistors R1 and R2.

[0027] A voltage is applied to sensor element 13b, resistors R4 and R5, and load resistor R6 from power supply E. An output value 30 is output from terminal A3 connected between sensor element 13b and load resistor R6, and from terminal A4 connected between resistors R4 and R5.

[0028] A voltage is applied to the sensor element 13c, the resistors R7 and R8, and the load resistor R9 from a power supply E. An output value 30 is output from a terminal A5 connected between the sensor element 13c and the load resistor R9, and from a terminal A2 connected between the resistors R7 and R8.

[0029] In the first embodiment, a voltage is simultaneously applied to each of the plurality of gas sensors 10 from the power source E. That is, in the first embodiment, the plurality of gas sensors 10 are simultaneously driven.

[0030] The resistance value of the gas sensor 10 changes when the gas to be detected is adsorbed. Therefore, the change in the electrical resistance of the gas sensor 10 is extracted as a deviation voltage, and this is used as an output value 30, making it possible to measure the concentration of the gas to be detected.

[0031] Specifically, the sensitive part 11 of the gas sensor 10 adsorbs oxygen in the air when heated to a predetermined temperature by the heating part 12. Furthermore, when a gas to be detected (e.g., methane gas) is present, the oxygen adsorbed to the sensitive part 11 reacts with the gas, causing a change in the electrical resistance of the sensitive part 11. The gas sensors 10 measure this change in electrical resistance to detect methane gas.

[0032] As shown in FIGS. 3 and 4, each of the gas sensors 10 includes a substrate 14, an electrode pattern 15 provided on the substrate 14 via an insulating film 14a, a pair of electrodes 16 connected to a power source E (see FIG. 2), and a SnO2 sensitive layer 17 covering the electrode pattern 15. The substrate 14 is made of Si. A cavity C is formed in the substrate 14. The electrode pattern 15 is made of Pt. The electrode pattern 15 also serves as both the sensitive portion 11 and the heating portion 12. That is, the electrode pattern 15 is heated to a predetermined temperature when current is applied. When a gas to be detected is present, the electrode pattern 15 changes its resistance, thereby changing the output value 30. Note that the gas sensors 10a to 10c have the same structure, and therefore FIG. 4 illustrates only the gas sensor 10a as a representative of the gas sensors 10. The substrate 14 is an example of a "chip" as defined in the claims.

[0033] As shown in FIG. 3, the plurality of gas sensors 10 are provided on the same substrate 14. In the example shown in FIG. 3, three gas sensors 10a to 10c are provided on the same substrate 14. The number of the plurality of gas sensors 10 is not limited to three. For example, several tens to 100 gas sensors 10 may be provided. Preferably, 10 to 20 gas sensors 10 are provided. The plurality of gas sensors 10 may be arranged in an array on the same substrate 14.

[0034] The control unit 2 controls each part of the gas detector 100 (the multiple gas sensors 10, the alarm unit 3, the multiple amplifiers 5, and the communication unit 6). The control unit 2 also acquires output values ​​30 of the multiple gas sensors 10. The control unit 2 also detects the gas to be detected based on the output values ​​30 of the multiple gas sensors 10. For example, the control unit 2 acquires the concentration of the gas to be detected based on all of the output values ​​30 of the multiple gas sensors 10. The control unit 2 includes a processor such as a CPU (Central Processing Unit) and a memory such as a RAM (Random Access Memory). The control unit 2 also executes a predetermined program to perform control processing.

[0035] The control unit 2 heats the sensitive unit 11 to a predetermined temperature by pulse-driving the heating unit 12 at predetermined time intervals, and performs detection of the multiple gas sensors 10 at the predetermined temperature at the predetermined time intervals. That is, the control unit 2 pulse-heats the sensitive unit 11 to a temperature at which methane gas can be detected at the predetermined time intervals, and performs detection of methane gas at the predetermined time intervals. For example, the control unit 2 performs detection of the multiple gas sensors 10 at the predetermined temperature at approximately 60-second intervals. The control unit 2 may perform detection during the entire period of the pulse during which the sensitive unit 11 is heated in a pulsed manner, or may perform detection during a part of the period (for example, a single point in time) of the pulse during which the sensitive unit 11 is heated in a pulsed manner.

[0036] The control unit 2 is also configured to determine whether or not deterioration has occurred in the plurality of gas sensors 10. The control unit 2 is also configured to make a determination regarding the life of the sensor unit 1 based on the output values ​​30 of the plurality of gas sensors 10. In the first embodiment, the control unit 2 is configured to make a determination regarding the life of the sensor unit 1 based on the output values ​​30 of the plurality of gas sensors 10 and the deterioration states of the plurality of gas sensors 10. Details of the configuration by which the control unit 2 determines whether or not deterioration has occurred in the gas sensors 10 and the configuration by which the control unit 2 makes a determination regarding the life of the sensor unit 1 will be described later.

[0037] When the gas to be detected is detected, the notification unit 3 issues a notification by sound, light, etc. The notification unit 3 is also configured to be able to notify the result of the lifespan determination of the sensor unit 1.

[0038] The storage unit 4 stores a determination threshold value (not shown) for the concentration of the gas to be detected, various programs (not shown) executed by the control unit 2, output value information 20 (described later), deterioration information 21 indicating the deterioration state of the gas sensor 10 (described later), history information 22, and a threshold value Th. The storage unit 4 includes, for example, a semiconductor storage element. The history information 22 includes the usage history and driving history of the gas sensor 10. The threshold value Th is a value used to determine the deterioration of the gas sensor 10 (described later).

[0039] The amplifier 5 is configured to amplify the output value 30 output by the gas sensor 10. The amplifier 5 outputs the amplified output value 30 to the control unit 2. The amplifier 5 includes amplifiers 5a to 5c corresponding to the gas sensors 10a to 10c. The amplifier 5 is, for example, an operational amplifier.

[0040] The communication unit 6 is capable of communicating with the external device 7. For example, the communication unit 6 communicates with the external device 7 via a network. Alternatively, the communication unit 6 may communicate with the external device 7 by being directly connected to the external device 7 via wired or wireless communication.

[0041] The control unit 2, the notification unit 3, the storage unit 4, and the communication unit 6 may be provided on the same substrate 14 as the sensor unit 1, or may be provided on different substrates.

[0042] (Gas sensor deterioration determination) In the first embodiment, the control unit 2 determines whether or not each of the plurality of gas sensors 10 has deteriorated, based on the output values ​​30 of the plurality of gas sensors 10. Specifically, the control unit 2 acquires output value information 20 corresponding to the gas concentration based on the output values ​​30 of the plurality of gas sensors 10. The control unit 2 then determines that a gas sensor 10 among the plurality of gas sensors 10 that outputs an output value 30 outside a predetermined range of the output value information 20 is a deteriorated gas sensor 10. The output value information 20 includes, for example, an average value 20a (see FIG. 5 ) of the output values ​​30 of the plurality of gas sensors 10, a median value, an average value of the remaining output values ​​30 excluding the maximum and minimum values, and the like.

[0043] In the first embodiment, the control unit 2 stores the number of gas sensors 10 in which degradation has occurred as degradation information 21 in the storage unit 4.

[0044] 5, a configuration will be described in which the control unit 2 determines whether or not the gas sensor 10 has deteriorated by using an average value 20a of the output values ​​30 of a plurality of gas sensors 10 as the output value information 20. In the graph G1 shown in FIG. 5, the vertical axis represents the output value 30 of the gas sensor 10, and the horizontal axis represents the number (No.) of the gas sensor 10.

[0045] In the example shown in FIG. 5, the first to third gas sensors 10 correspond to the gas sensors 10a to 10c.

[0046] The control unit 2 obtains an average value 20a based on the output values ​​30a to 30c of the gas sensors 10a to 10c. The control unit 2 then determines whether the output values ​​30a to 30c of each gas sensor 10 are within a predetermined range 40. The predetermined range 40 has an upper limit equal to the average value 20a plus a threshold value Th and a lower limit equal to the average value 20a minus the threshold value Th. That is, the predetermined range 40 is a range of plus ΔTh and minus ΔTh around the average value 20a. If the output value 30 of the gas sensor 10 is outside the predetermined range 40, the control unit 2 determines that the gas sensor 10 has deteriorated. The output value 30 of the deteriorated gas sensor 10 is excluded from the calculation of the average value 20a.

[0047] The threshold value Th is, for example, 1 / 10 (10%) of the 10% LEL (Lower Explosion Limit) value used to determine when reporting a gas leak. For example, if the gas to be detected is a methane-based gas, the 10% LEL is 5000 ppm. Therefore, if the gas to be detected is a methane-based gas, the threshold value Th is 500 ppm.

[0048] Furthermore, in the first embodiment, when a deteriorated gas sensor 10 is present, the control unit 2 acquires the concentration of the gas to be detected, excluding the output value 30 of the deteriorated gas sensor 10. That is, when a deteriorated gas sensor 10 is present, the control unit 2 acquires the concentration of the gas to be detected, using only the output value 30 of the gas sensor 10 that is not deteriorated.

[0049] In addition, the control unit 2 can determine that the sensor unit 1 as a whole is close to deterioration or has deteriorated even if the average value 20a approaches or exceeds a predetermined value (for example, half or full value of 10% LEL).

[0050] (Determination of the lifespan of the sensor unit) The control unit 2 is configured to determine the lifespan of the sensor unit 1 based on the number of gas sensors 10 that have deteriorated. For example, if 30% of the gas sensors 10 have deteriorated, the control unit 2 determines that deterioration is progressing. Then, the control unit 2 outputs the result of the determination regarding the lifespan of the sensor unit 1 that deterioration is progressing. Furthermore, if 40% of the gas sensors 10 have deteriorated, the control unit 2 determines that the sensor unit 1 cannot be used. Then, the control unit 2 outputs the result of the determination regarding the lifespan of the sensor unit 1 that the sensor unit 1 has reached the end of its lifespan.

[0051] In the first embodiment, the control unit 2 is configured to determine the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10 and the history information 22 of the multiple gas sensors 10. That is, the control unit 2 determines the lifespan of the sensor unit 1 based on the number of gas sensors 10 that have deteriorated and the usage history or drive history included in the history information 22 of the multiple gas sensors 10. The usage history includes the number of times the gas sensor 10 or the gas detector 100 has been started and stopped, the duration of use, etc. The drive history includes the number of times the sensitive unit 11 has been heated by pulse driving of the heating unit 12, the duration of heating, etc.

[0052] (Notification of the result of the determination regarding the life of the sensor unit) The control unit 2 is configured to cause the notification unit 3 to notify the result of the determination regarding the lifespan of the sensor unit 1. In the first embodiment, the notification unit 3 is configured to change the content of the notification depending on the result of the determination regarding the lifespan of the sensor unit 1. For example, the notification unit 3 can notify by varying the type, volume, length, etc. of the sound to be notified. The notification unit 3 can also notify by varying the color, flashing, and location of the light to be notified. For example, when the notification unit 3 notifies by emitting light from an LED or the like, the control unit 2 notifies the result of the determination regarding the lifespan of the sensor unit 1 by lighting the LED blue if the sensor unit 1 has not yet reached the end of its lifespan. The control unit 2 notifies the result of the determination regarding the lifespan of the sensor unit 1 by lighting the LED yellow if the sensor unit 1 is approaching the end of its lifespan. The control unit 2 notifies the result of the determination regarding the lifespan of the sensor unit 1 by lighting the LED red if the sensor unit 1 has reached the end of its lifespan. Furthermore, for example, when the notification unit 3 notifies by voice, if the sensor unit 1 has not yet reached the end of its life, the control unit 2 notifies the result of the determination regarding the life of the sensor unit 1 by making the notification unit 3 emit a short sound, "beep, beep, beep." Furthermore, if the sensor unit 1 has reached the end of its life, the control unit 2 notifies the result of the determination regarding the life of the sensor unit 1 by making the notification unit 3 emit a long sound, "beep, beep, beep."

[0053] (Determination process regarding the life of the sensor unit) Next, the process of determining the life span of the sensor unit 1 by the control unit 2 will be described with reference to FIG.

[0054] In step S1 of FIG. 6, the control unit 2 acquires output values ​​30 of the plurality of gas sensors 10 of the sensor unit 1, which includes a plurality of gas sensors 10 of the same type provided on the same substrate 14.

[0055] Next, in step S2, the control unit 2 determines which of the multiple gas sensors 10 has deteriorated based on the output values ​​30 of the multiple gas sensors 10. If there is no deteriorated gas sensor 10, the process ends. If there is a deteriorated gas sensor 10, the process proceeds to step S3.

[0056] When the process proceeds from step S2 to step S3, in step S3 the control unit 2 determines the life of the sensor unit 1 based on the output values ​​30 of the plurality of gas sensors 10. Specifically, the control unit 2 determines the life of the sensor unit 1 based on the number of gas sensors 10 that have deteriorated among the plurality of gas sensors 10.

[0057] Next, in step S4, the control unit 2 notifies the result of the determination regarding the life of the sensor unit 1. Thereafter, the process ends.

[0058] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0059] In the first embodiment, as described above, the control unit 2 is configured to determine the lifespan of the sensor unit 1 based on the output values ​​30 of the plurality of gas sensors 10. Thus, unlike a configuration in which the lifespan of the sensor unit 1 is determined based on the calibration history data of the gas sensors 10, by providing the plurality of gas sensors 10, it is possible to determine the lifespan of the sensor unit 1 based on information in the gas detector 100, such as the output values ​​30 of the plurality of gas sensors 10, without acquiring calibration history data through a process such as calibration. As a result, the lifespan of the sensor unit 1 can be determined with high accuracy.

[0060] Furthermore, in the first embodiment, as described above, the control unit 2 is configured to determine the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10 and the deterioration states of the multiple gas sensors 10. This makes it possible to determine the lifespan of the sensor unit 1 by taking into account the deterioration states of the multiple gas sensors 10, unlike a configuration in which the lifespan of the sensor unit 1 is determined based only on the output values ​​30 of the multiple gas sensors 10. As a result, the lifespan of the sensor unit 1 can be determined more accurately.

[0061] Furthermore, in the first embodiment, as described above, the control unit 2 is configured to determine the lifespan of the sensor unit 1 based on the number of deteriorated gas sensors 10. As a result, the presence or absence of deterioration in each of the plurality of gas sensors 10 is determined based on the output values ​​30 of the plurality of gas sensors 10, and thus the lifespan of the sensor unit 1 can be determined easily and accurately by acquiring the number of deteriorated gas sensors 10.

[0062] Furthermore, in the first embodiment, as described above, the control unit 2 is configured to determine the lifespan of the sensor unit 1 based on the output values ​​30 of the plurality of gas sensors 10 and the history information 22 of the plurality of gas sensors 10. This allows the control unit 2 to comprehensively determine the lifespan of the sensor unit 1 based on the output values ​​30 of the plurality of gas sensors 10 as well as the history information 22 of the plurality of gas sensors 10. As a result, the lifespan of the sensor unit 1 can be determined with even greater accuracy.

[0063] Furthermore, in the first embodiment, as described above, the notification unit 3 is configured to change the notification content depending on the result of the determination regarding the lifespan of the sensor unit 1. As a result, the result of the lifespan determination of the sensor unit 1 is notified, so that the user can easily understand the lifespan of the sensor unit 1. As a result, it is possible to improve convenience (usability) for the user.

[0064] Furthermore, in the first embodiment, as described above, the lifespan determination method includes a step of determining the lifespan of the sensor unit 1 based on the output values ​​30 of the plurality of gas sensors 10. This makes it possible to provide a lifespan determination method for the gas sensor 10 that can accurately determine the lifespan of the sensor unit 1, similar to the gas detector 100.

[0065] [Second embodiment] Next, a gas detector 200 according to a second embodiment will be described with reference to Figures 7 to 9. Note that the same components as those in the gas detector 100 according to the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0066] The gas detector 200 according to the second embodiment includes a sensor unit 1, a control unit 201, a notification unit 3, a storage unit 4, an amplifier 5, and a communication unit 6.

[0067] The control unit 201 is configured to determine whether or not each of the plurality of gas sensors 10 has deteriorated based on the output values ​​30 of the plurality of gas sensors 10 .

[0068] The storage unit 4 stores correction information 23 used to determine the lifespan of the sensor unit 1. The correction information 23 will be described in detail later.

[0069] (Gas sensor output value correction) In the second embodiment, the control unit 201 is configured to correct the output value 30 of a gas sensor 10 that has deteriorated, based on the output values ​​30 of a plurality of gas sensors 10. Specifically, the control unit 201 is configured to correct a gas sensor 10 that outputs an output value 30 outside a predetermined range from the output value information 20 of the plurality of gas sensors 10, as a gas sensor 10 that has deteriorated. More specifically, the control unit 201 corrects the output value 30 of a gas sensor 10 that has deteriorated, based on the output values ​​30 of gas sensors 10 that have not deteriorated.

[0070] In the second embodiment, the control unit 201 corrects the gain of the amplifier 5 corresponding to the deteriorated gas sensor 10 based on the output value 30 of the gas sensor 10 that is not deteriorated, thereby correcting the gain of the deteriorated gas sensor 10. Specifically, as shown in graph G2 of FIG. 8, the control unit 201 obtains an average value 20a from the output values ​​30 of a plurality of gas sensors 10 that are not deteriorated. The control unit 201 then obtains a predetermined range 40 based on the average value 20a and a threshold value Th, and corrects the gain of the amplifier 5 so that the output value 30 of the deteriorated gas sensor 10 falls within the obtained predetermined range 40. Preferably, the control unit 201 corrects the gain of the amplifier 5 so that the output value 30 of the deteriorated gas sensor 10 conforms to the output value information 20 (average value 20a). Note that in graph G2, the vertical axis represents the output value 30 of the gas sensor 10, and the horizontal axis represents the number (No.) of the gas sensor 10.

[0071] 8, the gain of the amplifier 5 is corrected so that the output value 30c outside the predetermined range 40 becomes the output value 30d equal to the average value 20a. After the correction of the output value 30, the gas sensor 10 continues to be used for detecting the target gas.

[0072] Furthermore, the control unit 201 stores, as correction information 23, in the memory unit 4 for each of the plurality of gas sensors 10, at least one of the number of times correction has been performed and the correction value 50 obtained when the output value 30c is corrected to the output value 30d.

[0073] (Determination of the lifespan of the sensor unit) In the second embodiment, the control unit 201 is configured to determine the lifespan of the sensor unit 1 based on the state of correction. Specifically, the control unit 201 is configured to determine the lifespan of the sensor unit 1 based on at least one of the number of corrections and the magnitude of the correction value 50 used when performing the correction. In the second embodiment, when determining the lifespan of the sensor unit 1 based on the number of corrections, the control unit 201 determines that deterioration is progressing if the number of corrections exceeds a predetermined first number. Then, the control unit 201 outputs a result of the determination on the lifespan of the sensor unit 1 that the deterioration is progressing. Furthermore, when determining the lifespan of the sensor unit 1 based on the correction value 50, the control unit 201 determines that the sensor unit 1 cannot be used if the number of corrections exceeds a predetermined second number. Then, the control unit 201 outputs a result of the determination on the lifespan of the sensor unit 1 that the sensor unit 1 has reached the end of its life. Furthermore, the control unit 201 determines that deterioration is progressing if the correction value 50 exceeds a predetermined first threshold. Then, the control unit 201 outputs the result of the determination regarding the lifespan of the sensor unit 1 that deterioration is progressing. Furthermore, the control unit 201 determines that the sensor unit 1 cannot be used when the correction value 50 exceeds a predetermined second threshold value. Then, the control unit 201 outputs the result of the determination regarding the lifespan of the sensor unit 1 that the sensor unit 1 has reached the end of its lifespan.

[0074] (Determination process regarding the life of the sensor unit) Next, the process of determining the life span of the sensor unit 1 by the control unit 201 will be described with reference to FIG.

[0075] 9, the control unit 2 acquires output values ​​30 of a plurality of gas sensors 10. In step S2, the control unit 2 determines whether or not there is any gas sensor 10 that has deteriorated. If there is no gas sensor 10 that has deteriorated, the process ends. If there is any gas sensor 10 that has deteriorated, the process proceeds to step S10.

[0076] When the process proceeds from step S2 to step S10, the control unit 201 corrects the gas sensor 10 that has deteriorated based on the output values ​​30 of the plurality of gas sensors 10 in step S10.

[0077] Next, in step S11, the control unit 201 determines the life of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10. Specifically, the control unit 201 determines the life of the sensor unit 1 based on at least one of the number of corrections and the magnitude of the correction value 50 when performing the correction.

[0078] Next, in step S4, the control unit 201 notifies the result of the determination regarding the life of the sensor unit 1. Thereafter, the process ends.

[0079] The other configurations of the second embodiment are the same as those of the first embodiment.

[0080] (Effects of the second embodiment) In the second embodiment, the following effects can be obtained.

[0081] In the second embodiment, as described above, the control unit 201 is configured to correct any gas sensor 10 that has deteriorated based on the output values ​​30 of the multiple gas sensors 10, and to determine the life of the sensor unit 1 based on the state of the correction. This allows the correction of any gas sensor 10 that has deteriorated, thereby extending the life of the gas sensor 10. Furthermore, because the determination of the life of the sensor unit 1 is made based on the state of the correction, the life of the sensor unit 1 can be accurately determined even in a configuration in which the life of the gas sensor 10 is extended by correcting the gas sensor 10.

[0082] Furthermore, in the second embodiment, as described above, the control unit 201 is configured to make a determination regarding the life of the sensor unit 1 based on at least one of the number of corrections and the magnitude of the correction value 50 used when making the correction. This makes it possible to easily make a determination regarding the life of the sensor unit 1 in a configuration that can extend the life of the gas sensor 10 by acquiring at least one of the number of corrections and the magnitude of the correction value 50.

[0083] The other effects of the second embodiment are the same as those of the first embodiment.

[0084] (Variation) The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the above description of the embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0085] For example, in the first and second embodiments described above, an example of a configuration has been shown in which the control unit 2 (control unit 201) determines the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10 and the deterioration states of the multiple gas sensors 10, but the present invention is not limited to this. For example, the control unit may be configured to determine the lifespan of the sensor unit without using the deterioration states of the multiple gas sensors, as long as it uses the output values ​​of the multiple gas sensors.

[0086] In the first embodiment, the control unit 2 determines the life of the sensor unit 1 based on the number of deteriorated gas sensors 10 among the plurality of gas sensors 10. However, the present invention is not limited to this. For example, the control unit may be configured to determine the life of the sensor unit based on the degree of deterioration of the plurality of gas sensors.

[0087] In the second embodiment, the control unit 201 determines the lifespan of the sensor unit 1 based on at least one of the number of corrections made to the gas sensors 10 and the magnitude of the correction value 50. However, the present invention is not limited to this. For example, the control unit may be configured to determine the lifespan of the sensor unit based on both the number of corrections made to the gas sensors 10 and the magnitude of the correction value 50. In this case, the control unit may be configured to store both the number of corrections made and the correction value 50 in the storage unit as correction information.

[0088] Furthermore, in the first and second embodiments described above, an example of a configuration has been shown in which the control unit 2 (control unit 201) determines the lifespan of the sensor unit 1 based on any one of the number of gas sensors 10 that have deteriorated, the number of corrections, and the correction value 50. However, the present invention is not limited to this. For example, the control unit may be configured to determine the lifespan of the sensor unit based on how much the base values ​​of the output values ​​of the multiple gas sensors 10 have increased relative to a threshold value. In this case, the control unit may be configured to determine that the sensor unit has reached the end of its lifespan when the base values ​​of the output values ​​exceed the threshold value or when the base value increases to a value higher than half the threshold value when compared with the initial base value.

[0089] Furthermore, in the first and second embodiments described above, an example of a configuration has been shown in which the control unit 2 (control unit 201) determines the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10 and the history information 22 of the multiple gas sensors 10, but the present invention is not limited to this. For example, the control unit may be configured to determine the lifespan of the sensor unit without using the history information of the multiple gas sensors, as long as it uses the output values ​​of the multiple gas sensors.

[0090] In the first and second embodiments, the control unit 2 (control unit 201) determines the lifespan of the sensor unit 1 based on the output values ​​30 of the plurality of gas sensors 10, but the present invention is not limited to this. For example, the control unit may be configured to determine the lifespan of the gas detector based on the output values ​​of the plurality of gas sensors.

[0091] In the first and second embodiments, the threshold value Th is set to 10% of the 10% LEL of the gas to be detected, but the present invention is not limited to this. For example, the threshold value may be set to 1σ of the variance of the output values ​​of multiple gas sensors, or may be set to 20% of the average value.

[0092] Furthermore, in the first and second embodiments, examples of configurations in which all of the plurality of gas sensors 10 are used to detect the target gas are shown, but the present invention is not limited to this. Not all of the plurality of gas sensors may be used to detect the target gas. Even if not all of the plurality of gas sensors are used to detect the target gas, all of the plurality of gas sensors must be driven.

[0093] In the first and second embodiments, the control unit 2 (control unit 201) acquires the concentration of the gas to be detected based on the output values ​​30 of the plurality of gas sensors 10. However, the present invention is not limited to this. For example, the control unit may be configured to determine the presence or absence of the gas to be detected based on the output values ​​of the plurality of gas sensors.

[0094] In the first and second embodiments, gas detection at a predetermined temperature is performed at predetermined time intervals of approximately 60 seconds, but the present invention is not limited to this. In the present invention, gas detection at a predetermined temperature may be performed at predetermined time intervals other than 60 seconds.

[0095] In the first and second embodiments, the gas sensors 10 are semiconductor-type gas sensors, but the present invention is not limited to this. For example, the gas sensors may be electrochemical sensors (potential electrolysis type, diaphragm galvanic cell type), catalytic combustion type gas sensors, or gas thermal conduction type gas sensors. When the gas sensors are configured as gas sensors other than semiconductor-type gas sensors, the gas sensors must be arranged within a predetermined range (for example, several centimeters) so that they can detect the same target gas.

[0096] In the first and second embodiments, the gas to be detected is methane, but the present invention is not limited to this. For example, the gas to be detected may be hydrogen gas, ethane gas, propane gas, or carbon monoxide gas.

[0097] Furthermore, in the first and second embodiments, examples have been shown in which the gas detector 100 detects a single type of target gas, but the present invention is not limited to this. In the present invention, the target gas may include a predetermined type of first target gas and a second target gas different from the first target gas. The first target gas is, for example, methane gas. The second target gas is, for example, hydrogen sulfide gas generated from sewage. In this case, the sensor unit may be configured to include a gas sensor capable of detecting methane gas as well as a gas sensor capable of detecting hydrogen sulfide gas. The gas sensor capable of detecting hydrogen sulfide gas includes a substrate, an electrode pattern provided on the substrate, and a ZnO sensitive layer covering the electrode pattern. The ZnO sensitive layer contains gallium.

[0098] Furthermore, in the above first and second embodiments, examples have been shown in which the gas detector 100 is configured to include the alarm unit 3 and the communication unit 6, but the present invention is not limited to this. In the present invention, the gas detector may be provided with only one of the alarm unit and the communication unit. For example, the gas detector may not be provided with a communication unit. Furthermore, the gas detector may not be provided with an alarm unit. In this case, the alarm unit may be provided separately from the gas detector. Furthermore, even if the gas detector is provided with an alarm unit, the alarm may be performed by a device external to the gas detector.

[0099] In the first and second embodiments, the notification unit 3 changes the notification content by changing the way it emits light or the sound it emits depending on the result of the determination regarding the lifespan of the sensor unit 1, but the present invention is not limited to this. The notification unit may be configured to issue a notification only when the sensor unit has reached the end of its lifespan, and not to issue a notification in other cases.

[0100] In the first and second embodiments, for convenience of explanation, the control processing by the control unit 2 (control unit 201) is explained using a flow-driven flowchart in which processing is performed sequentially according to a processing flow, but the present invention is not limited to this. In the present invention, the control processing may be performed by an event-driven processing in which processing is performed on an event-by-event basis. In this case, the control processing may be performed completely event-driven, or may be performed in a combination of event-driven and flow-driven. [Explanation of symbols]

[0101] 1 Sensor unit 2, 201 Control unit 3. Information Department 10, 10a to 10c Multiple gas sensors 14 Substrate (chip) 22 Historical Information 30 Output Values 50 correction value 100, 200 Gas Detector

Claims

1. A gas detector for detecting a gas to be detected, a sensor unit including a plurality of gas sensors of the same type provided on the same chip; a control unit that acquires output values ​​of the plurality of gas sensors, the control unit is configured to determine deterioration of each of the plurality of gas sensors based on output values ​​of the plurality of gas sensors, and to make a determination regarding the life of the sensor unit based on the deterioration state of the plurality of gas sensors.

2. A gas detector for detecting a gas to be detected, a sensor unit including a plurality of gas sensors of the same type provided on the same chip; a control unit that acquires output values ​​of the plurality of gas sensors, The control unit is configured to determine whether or not each of the plurality of gas sensors has deteriorated based on output values ​​of the plurality of gas sensors, and to make a determination regarding the life of the sensor unit based on the number of gas sensors in which deterioration has occurred.

3. A gas detector for detecting a gas to be detected, a sensor unit including a plurality of gas sensors of the same type provided on the same chip; a control unit that acquires output values ​​of the plurality of gas sensors, The control unit is configured to determine whether or not each of the plurality of gas sensors has deteriorated based on the output values ​​of the plurality of gas sensors, to correct any gas sensor that has deteriorated based on the output values ​​of the plurality of gas sensors, and to determine the life of the sensor unit based on the state of the correction.

4. 4. The gas detector according to claim 3, wherein the control unit is configured to make a determination regarding the life of the sensor unit based on at least one of the number of times the correction is performed or the magnitude of the correction value when the correction is performed.

5. A gas detector for detecting a gas to be detected, a sensor unit including a plurality of gas sensors of the same type provided on the same chip; a control unit that acquires output values ​​of the plurality of gas sensors, The control unit is configured to make a determination regarding the life of the sensor unit based on output values ​​of the plurality of gas sensors and history information including the usage history and operation history of each of the plurality of gas sensors.

6. A gas detector for detecting a gas to be detected, a sensor unit including a plurality of gas sensors of the same type provided on the same chip; a control unit that acquires output values ​​of the plurality of gas sensors; a notification unit capable of notifying a result of the lifespan determination of the sensor unit, the control unit is configured to determine a lifespan of the sensor unit based on output values ​​of the plurality of gas sensors, The gas detector, wherein the notification unit is configured to change the content of notification depending on the result of the determination regarding the lifespan of the sensor unit.

7. acquiring output values ​​of a plurality of gas sensors of the same type provided on the same chip in a sensor unit; determining deterioration of each of the plurality of gas sensors based on output values ​​of the plurality of gas sensors; and determining the lifespan of the sensor units based on the deterioration states of the plurality of gas sensors.

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