Method for determining the lifespan of gas detectors and gas sensors

Abstract

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

Description

Technical Field

[0001] This invention relates to a gas detector and a method for determining the lifespan of a gas sensor.

Background Art

[0002] Conventionally, gas detectors have been known (see, for example, Patent Document 1).

[0003] The above Patent Document 1 discloses a gas detection device (gas detector) including a gas detection unit including a gas sensor unit having one gas sensor, and a control unit. In this gas detector, the control unit is configured to predict the service life (time of use limit) of the gas sensor based on the calibration history data of the gas sensor. Specifically, the control unit acquires a sensitivity decay characteristic curve over time specific to the gas sensor based on the calibration history data of the gas sensor. Then, the control unit acquires a specific decay time point at which the sensitivity value becomes a specific ratio (threshold value) with respect to the initial sensitivity value of the gas sensor based on the acquired sensitivity decay characteristic curve over time. Then, when it is detected that the sensitivity value of the gas sensor is below the threshold value during the calibration process of the gas sensor, the control unit determines that the service life of the gas sensor has arrived.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, gas detection devices (gas detectors) are safety equipment, and information regarding the lifespan of the sensor unit, which forms the core of such safety equipment, is important. 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 the calibration history data of the gas sensor acquired during calibration. Therefore, since the timing at which lifespan determination can be performed is limited to the time of calibration, there is a disadvantage in that it is difficult to accurately determine the lifespan of the sensor unit. Thus, there is a need 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] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a gas detector and a method for determining the lifespan of a gas sensor that can accurately determine the lifespan of the sensor part. [Means for solving the problem]

[0007] To achieve the above objective, the gas detector according to the first aspect of this invention is a gas detector for detecting a target gas, comprising a sensor unit including a plurality of gas sensors of the same type provided on the same chip, and a control unit that acquires the output values ​​of the plurality of gas sensors, wherein the control unit is configured to make a determination regarding the lifespan of the sensor unit based on the output values ​​of the plurality of gas sensors.

[0008] In the gas detector according to the first aspect of this invention, the control unit is configured to make a determination regarding the lifespan of the sensor unit based on the output values ​​of multiple gas sensors. This differs from configurations that make a determination regarding the lifespan of the sensor unit based on calibration history data of the gas sensors. By providing multiple gas sensors, it is possible to make a determination regarding the lifespan of the sensor unit based on information within the gas detector, such as the output values ​​of multiple gas sensors, without obtaining calibration history data through processes such as calibration. As a result, the lifespan of the sensor unit can be determined with high accuracy. The lifespan of the sensor unit has the same meaning as the remaining lifespan, indicating how much longer the sensor unit can be used. Furthermore, the determination regarding the lifespan of the sensor unit means determining how close the sensor unit is to its lifespan limit. In other words, the determination regarding the lifespan of the sensor unit means determining how much longer the sensor unit can be used.

[0009] In the gas detector according to the first aspect described above, preferably, the control unit is configured to make a determination regarding the lifespan of the sensor unit based on the output values ​​of the multiple gas sensors and the degradation status of the multiple gas sensors. With this configuration, unlike a configuration that makes a determination regarding the lifespan of the sensor unit based only on the output values ​​of the multiple gas sensors, the degradation status of the multiple gas sensors is also taken into consideration when making the determination regarding the lifespan of the sensor unit. As a result, the determination regarding the lifespan of the sensor unit can be made with greater accuracy.

[0010] In this case, preferably, the control unit is configured to determine whether or not each of the gas sensors has deteriorated based on the output values ​​of the gas sensors, and to make a determination regarding the lifespan of the sensor unit based on the number of gas sensors that have deteriorated. With this configuration, since the presence or absence of deterioration in each of the gas sensors is determined based on the output values ​​of the gas sensors, the lifespan of the sensor unit can be easily and accurately determined by obtaining the number of gas sensors that have deteriorated.

[0011] In a configuration where the control unit determines the lifespan of the sensor unit based on the output values ​​of multiple gas sensors and the degradation status of the multiple gas sensors, it is preferable that the control unit determines whether or not each of the multiple gas sensors has degraded based on the output values ​​of the multiple gas sensors, corrects the degraded gas sensors based on the output values ​​of the multiple gas sensors, and makes a determination regarding the lifespan of the sensor unit based on the state of correction. With this configuration, the lifespan of the gas sensors can be extended because the degraded gas sensors are corrected. Furthermore, since the determination regarding the lifespan of the sensor unit is made based on the state of correction, the determination regarding the lifespan of the sensor unit can be made with high accuracy even in a configuration where the lifespan of the gas sensors is extended by correcting the gas sensors.

[0012] In this case, preferably, the control unit is configured to make a determination regarding the lifespan of the sensor unit based on at least one of the number of corrections or the magnitude of the correction value when performing the correction. 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] In the gas detector according to the first aspect described above, preferably, the control unit is configured to make a determination regarding the lifespan of the sensor unit based on the output values ​​of multiple gas sensors and the history information of multiple gas sensors. With this configuration, a comprehensive determination regarding the lifespan of the sensor unit can be made based on the output values ​​of multiple gas sensors and the history information of multiple gas sensors. As a result, in a configuration that can extend the lifespan of the gas sensor, the determination regarding the lifespan of the sensor unit can be made with even greater accuracy.

[0014] In the gas detector according to the first aspect described above, preferably, a notification unit is further provided that can notify the result of the sensor unit's lifespan determination, and the notification unit is configured to change the notification content according to the result of the determination regarding the sensor unit's lifespan. With this configuration, the user can easily understand the lifespan of the sensor unit because the result of the sensor unit's lifespan determination is notified. As a result, user convenience (usability) can be improved.

[0015] A second aspect of this invention provides a method for determining the lifespan of a gas sensor, comprising the steps of: acquiring the output values ​​of multiple gas sensors in a sensor unit, which includes multiple gas sensors of the same type provided on the same chip; and making a determination regarding the lifespan of the sensor unit based on the output values ​​of the multiple gas sensors.

[0016] The second aspect of this invention provides a method for determining the lifespan of a gas sensor, which includes a step of determining the lifespan of the sensor unit based on the output values ​​of multiple gas sensors. 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 unit, similar to the gas detector described in the first aspect. [Effects of the Invention]

[0017] According to the present invention, as described above, it is possible to provide a gas detector and a method for determining the lifespan of a gas sensor that can accurately determine the lifespan of the sensor unit. [Brief explanation of the drawing]

[0018] [Figure 1] This is a block diagram showing the controllable configuration of a gas detector according to the first embodiment. [Figure 2] This is a circuit diagram showing an example of the configuration of the gas sensor of a gas detector according to the first embodiment. [Figure 3] This is a schematic plan view showing an example of the configuration of the gas sensor of a gas detector according to the first embodiment. [Figure 4] This is a schematic cross-sectional view showing an example of the configuration of the gas sensor of a gas detector according to the first embodiment. [Figure 5] A graph for explaining a configuration in which a control unit of a gas detector according to the first embodiment determines whether deterioration has occurred in a gas sensor. [Figure 6] A flowchart for explaining a method for determining the lifespan of a gas sensor by a gas detector according to the first embodiment. [Figure 7] A block diagram showing a control configuration of a gas detector according to the second embodiment. [Figure 8] A graph for explaining a configuration in which a control unit of a gas detector according to the second embodiment corrects a deteriorated gas sensor. [Figure 9] A flowchart for explaining a method for determining the lifespan of a gas sensor by a gas detector according to the second embodiment.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0020] [First Embodiment] Referring to FIGS. 1 to 6, the configuration of a gas detector 100 according to the first embodiment of the present invention will be described.

[0021] (Configuration of Gas Detector) The gas detector 100 of the first embodiment is a gas detector that detects a gas to be detected. Further, when the gas detector 100 detects the gas to be detected, it outputs an alarm to notify the user of gas leakage or the like. The gas to be detected is the gas that the gas detector 100 should detect. For example, the gas to be detected is a fuel gas (city gas) containing methane gas as a main component.

[0022] As shown in Figure 1, the gas detector 100 comprises a sensor unit 1, a control unit 2, a notification unit 3, a storage unit 4, multiple amplifiers 5, and a communication unit 6. The multiple gas sensors 10, the control unit 2, the notification unit 3, and the communication unit 6 are housed within the casing of the gas detector 100. The gas detector 100 operates on power supplied from a commercial power source or from a battery (not shown).

[0023] The sensor unit 1 includes multiple gas sensors 10 of the same type. The sensor unit 1 detects a single type of target gas. In the example shown in Figure 1, the sensor unit 1 includes gas sensors 10a to 10c. The sensor unit 1 outputs the output values ​​30 from the multiple gas sensors 10 to the amplifier 5. Although Figure 1 shows, for convenience, the output value 30 being output from only one of the multiple gas sensors 10, the output value 30 is similarly output from the other gas sensors 10 as well.

[0024] Each gas sensor 10 includes a sensing element 11 and a heating element 12 that heats the sensing element 11 to a predetermined temperature. The output values ​​30 of each gas sensor 10 are input to the corresponding amplifier 5. The gas sensors 10 are MEMS (Micro Electro Mechanical Systems) type gas sensors. In other words, each gas sensor 10 is formed using MEMS technology, which involves forming a mechanical structure in a semiconductor substrate using a semiconductor manufacturing process. For example, each gas sensor 10 has a size of approximately 0.1 mm on each side. Note that in Figure 1, for convenience, only gas sensor 10a is shown with the sensing element 11 and heating element 12, but gas sensors 10b and 10c also include the sensing element 11 and heating element 12 in the same way.

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

[0026] Voltage is applied from power supply E to the sensor element 13a, the opposite side resistors R1 and R2, and the load resistor R3. Additionally, an output value of 30 (see Figure 1) is output from terminal A1 connected between the sensor element 13a and the load resistor R3, and from terminal A2 connected between the opposite side resistors R1 and R2.

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

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

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

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

[0031] Specifically, the sensing element 11 of the gas sensor 10 is heated to a predetermined temperature by the heating element 12, thereby adsorbing oxygen from the air. Furthermore, if the target gas (for example, methane gas) is present, the oxygen adsorbed on the sensing element 11 reacts, causing a change in the electrical resistance of the sensing element 11. Multiple gas sensors 10 detect methane gas by measuring this change in electrical resistance.

[0032] Each of the multiple gas sensors 10, as shown in Figures 3 and 4, includes a substrate 14, an electrode pattern 15 provided on the substrate 14 via an insulating film 14a, a pair of electrode parts 16 connected to a power supply E (see Figure 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 a sensitive part 11 and a heating part 12. In other words, the electrode pattern 15 is heated to a predetermined temperature when current is passed through it. Furthermore, when the gas to be detected is present, the resistance value of the electrode pattern 15 changes, thereby changing the output value 30. Note that the structures of gas sensors 10a to 10c are the same, so in Figure 4, gas sensor 10a is shown as a representative of the multiple gas sensors 10. The substrate 14 is an example of a "chip" as defined in the claims.

[0033] Furthermore, as shown in Figure 3, multiple gas sensors 10 are provided on the same substrate 14. In the example shown in Figure 3, three gas sensors 10a to 10c are provided on the same substrate 14. Note that the number of gas sensors 10 is not limited to three. For example, there may be several tens to 100 gas sensors 10. Preferably, there are 10 to 20 gas sensors 10. Also, the multiple 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 (multiple gas sensors 10, notification unit 3, multiple amplifiers 5, and communication unit 6). The control unit 2 also acquires the output values ​​30 from the multiple gas sensors 10. Based on the output values ​​30 from the multiple gas sensors 10, the control unit 2 detects the target gas. For example, the control unit 2 acquires the concentration of the target gas based on all the output values ​​30 from the multiple gas sensors 10. The control unit 2 includes a processor such as a CPU (Central Processing Unit) and memory such as RAM (Random Access Memory). The control unit 2 also performs control processing by executing a predetermined program.

[0035] The control unit 2 heats the sensing unit 11 to a predetermined temperature by pulse driving of the heating unit 12 at predetermined time intervals, and performs detection at predetermined temperatures of the multiple gas sensors 10 at predetermined time intervals. In other words, the control unit 2 pulsely heats the sensing unit 11 to a temperature at which methane gas can be detected at predetermined time intervals, and performs detection of methane gas at predetermined time intervals. For example, the control unit 2 performs detection of the multiple gas sensors 10 at predetermined temperatures with a period of approximately 60 seconds. The control unit 2 may also perform detection for the entire duration of the pulse in which the sensing unit 11 is pulsed, or it may perform detection for a part of the duration of the pulse in which the sensing unit 11 is pulsed (for example, the duration of one point).

[0036] Furthermore, the control unit 2 is configured to determine whether or not deterioration has occurred in the multiple gas sensors 10. The control unit 2 is also configured to make a determination regarding the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10. In the first embodiment, the control unit 2 is configured to make a determination regarding the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10 and the deterioration status of the multiple 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 for making a determination regarding the lifespan of the sensor unit 1, will be described later.

[0037] The notification unit 3 provides notification via sound, light, or other means when the target gas is detected. Furthermore, the notification unit 3 is configured to notify the results of the lifespan determination of the sensor unit 1.

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

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

[0040] The communication unit 6 can communicate with an 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 by directly connecting to the external device 7 via wired or wireless connection.

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

[0042] (Gas sensor degradation detection) In the first embodiment, the control unit 2 determines whether or not each of the multiple gas sensors 10 has deteriorated based on the output values ​​30 of the multiple 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 multiple gas sensors 10. The control unit 2 then determines that a gas sensor 10 that outputs an output value 30 outside a predetermined range from the output value information 20 among the multiple gas sensors 10 is a deteriorated gas sensor 10. The output value information 20 includes, for example, the average value 20a (see Figure 5) of the output values ​​30 of the multiple gas sensors 10, the median, and the average value of the remaining output values ​​30 after excluding the maximum and minimum values.

[0043] In the first embodiment, the control unit 2 stores the number of gas sensors 10 that have deteriorated as deterioration information 21 in the storage unit 4.

[0044] Referring to Figure 5, the configuration in which the control unit 2 determines whether or not deterioration has occurred in the gas sensor 10 using the average value 20a of the output values ​​30 of multiple gas sensors 10 as output value information 20 will be described. In the graph G1 shown in Figure 5, the vertical axis is the output value 30 of the gas sensor 10, and the horizontal axis is the number (No.) of the gas sensor 10.

[0045] In the example shown in Figure 5, gas sensors 1 to 3 (10) correspond to 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 is a range with an upper limit of the average value 20a plus a threshold Th, and a lower limit of the average value 20a minus the threshold Th. In other words, the predetermined range 40 is a range of +ΔTh and -ΔTh centered on the average value 20a. If the output value 30 of a 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 a deteriorated gas sensor 10 is excluded from the calculation of the average value 20a.

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

[0048] Furthermore, in the first embodiment, if there is a deteriorated gas sensor 10, the control unit 2 excludes the output value 30 of the deteriorated gas sensor 10 and obtains the concentration of the gas to be detected. In other words, if there is a deteriorated gas sensor 10, the control unit 2 obtains the concentration of the gas to be detected using only the output value 30 of the gas sensors 10 that have not deteriorated.

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

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

[0051] In the first embodiment, the control unit 2 is configured to make a determination regarding 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. Specifically, the control unit 2 makes a determination regarding the lifespan of the sensor unit 1 based on the number of gas sensors 10 that have deteriorated and the usage history or driving 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 gas detector 100 has been started and stopped, the usage time, etc. The driving history includes the number of times the sensing unit 11 has been heated by the pulse drive of the heating unit 12, the heating time, etc.

[0052] (Notification of the result of the determination regarding the lifespan of the sensor unit) The control unit 2 is configured to notify the notification unit 3 of 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 notification content according to the result of the determination regarding the lifespan of the sensor unit 1. For example, the notification unit 3 can make notifications with different types of sounds, loudness, and length. The notification unit 3 can also make notifications with different colors of lights, whether they flash or not, and where they are emitted. For example, when the notification unit 3 makes notifications by emitting light such as an LED, the control unit 2 notifies the result of the determination regarding the lifespan of the sensor unit 1 by lighting up the LED in blue if the sensor unit 1 has not yet reached the end of its lifespan. The control unit 2 also notifies the result of the determination regarding the lifespan of the sensor unit 1 by lighting up the LED in yellow if the sensor unit 1 is approaching the end of its lifespan. The control unit 2 also notifies the result of the determination regarding the lifespan of the sensor unit 1 by lighting up the LED in red if the sensor unit 1 has reached the end of its lifespan. Furthermore, for example, if the notification unit 3 provides notification by voice, the control unit 2 will notify the result of the determination regarding the lifespan of the sensor unit 1 by having the notification unit 3 emit a short beep, beep, beep if the sensor unit 1 has not yet reached the end of its lifespan. Also, if the sensor unit 1 has reached the end of its lifespan, the control unit 2 will notify the result of the determination regarding the lifespan of the sensor unit 1 by having the notification unit 3 emit a long beep, beep, beep.

[0053] (Determination process regarding the lifespan of the sensor unit) Next, with reference to Figure 6, the determination process regarding the lifespan of the sensor unit 1 by the control unit 2 will be explained.

[0054] In step S1 of Figure 6, the control unit 2 acquires the output values ​​30 of the multiple gas sensors 10 of the sensor unit 1, which includes multiple 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 are no deteriorated gas sensors 10, the process ends. If there are deteriorated gas sensors 10, the process proceeds to step S3.

[0056] If the process proceeds from step S2 to step S3, in step S3, the control unit 2 makes a determination regarding the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10. Specifically, the control unit 2 makes a determination regarding the lifespan of the sensor unit 1 based on the number of gas sensors 10 that have deteriorated out of the multiple gas sensors 10.

[0057] Next, in step S4, the control unit 2 notifies the result of the determination regarding the lifespan of the sensor unit 1. After that, 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 make a determination regarding the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10. This differs from 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 multiple gas sensors 10, it is possible to make a determination regarding the lifespan of the sensor unit 1 based on information within the gas detector 100, such as the output values ​​30 of the multiple gas sensors 10, without obtaining calibration history data through processes 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 make a determination regarding the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10 and the deterioration status of the multiple gas sensors 10. This differs from the 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 it allows for a determination regarding the lifespan of the sensor unit 1 to be made while also taking into account the deterioration status of the multiple gas sensors 10. As a result, the determination regarding the lifespan of the sensor unit 1 can be made with greater accuracy.

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

[0062] Furthermore, in the first embodiment, as described above, the control unit 2 is configured to make a determination regarding 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. This allows for a comprehensive determination regarding 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. As a result, the determination regarding the lifespan of the sensor unit 1 can be made with even greater accuracy.

[0063] Furthermore, in the first embodiment, as described above, the notification unit 3 is configured to change the notification content according to 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 the user can easily understand the lifespan of the sensor unit 1. As a result, user convenience (usability) can be improved.

[0064] Furthermore, in the first embodiment, as described above, the life determination method includes the step of determining the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10. This makes it possible to provide a life 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, the gas detector 200 according to the second embodiment will be described with reference to Figures 7 to 9. Components similar to those in the gas detector 100 according to the first embodiment are denoted by the same reference numerals, and detailed explanations are omitted.

[0066] The gas detector 200 according to the second embodiment comprises 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 gas sensors 10 has deteriorated based on the output values ​​30 of the gas sensors 10.

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

[0069] (Correction of gas sensor output value) In the second embodiment, the control unit 201 is configured to correct a deteriorated gas sensor 10 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, treating it as a deteriorated gas sensor 10. More specifically, the control unit 2 corrects the output value 30 of a deteriorated gas sensor 10 based on the output value 30 of a gas sensor 10 that has not deteriorated.

[0070] In the second embodiment, the control unit 201 corrects the deteriorated gas sensor 10 by correcting 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 has not deteriorated. Specifically, as shown in graph G2 of Figure 8, the control unit 201 obtains an average value 20a from the output values ​​30 of a plurality of gas sensors 10 that have not deteriorated. Then, the control unit 201 obtains a predetermined range 40 based on the average value 20a and a threshold 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 becomes the output value information 20 (average value 20a). Note that in graph G2, the vertical axis is the output value 30 of the gas sensor 10, and the horizontal axis is the number (No.) of the gas sensor 10.

[0071] In the example shown in Figure 8, the gain correction of the amplifier 5 is performed so that the output value 30c outside the predetermined range 40 becomes the output value 30d, which is equal to the average value 20a. After the correction of the output value 30, the gas sensor 10 continues to be used to detect the target gas.

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

[0073] (Determination regarding the lifespan of the sensor unit) In the second embodiment, the control unit 201 is configured to make a determination regarding the lifespan of the sensor unit 1 based on the correction status. Specifically, the control unit 201 is configured to make a determination regarding the lifespan of the sensor unit 1 based on at least one of the number of corrections or the magnitude of the correction value 50 used when performing the correction. In the second embodiment, when the determination regarding the lifespan of the sensor unit 1 is made 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. The control unit 201 then outputs that deterioration is progressing as a result of the determination regarding the lifespan of the sensor unit 1. Also, when the determination regarding the lifespan of the sensor unit 1 is made 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. The control unit 201 then outputs that the sensor unit 1 has reached the end of its lifespan as a result of the determination regarding the lifespan of the sensor unit 1. Furthermore, the control unit 201 determines that deterioration is progressing if the correction value 50 exceeds a predetermined first threshold. The control unit 201 then outputs that deterioration is progressing as a result of its determination regarding the lifespan of the sensor unit 1. The control unit 201 also determines that the sensor unit 1 cannot be used if the correction value 50 exceeds a predetermined second threshold. The control unit 201 then outputs that the sensor unit 1 has reached the end of its lifespan as a result of its determination regarding the lifespan of the sensor unit 1.

[0074] (Determination process regarding the lifespan of the sensor unit) Next, with reference to Figure 9, the determination process regarding the lifespan of the sensor unit 1 by the control unit 201 will be explained.

[0075] In step S1 of Figure 9, the control unit 2 acquires the output values ​​30 from multiple gas sensors 10. In step S2, the control unit 2 determines whether or not there are any deteriorated gas sensors 10. If there are no deteriorated gas sensors 10, the process ends. If there are deteriorated gas sensors 10, the process proceeds to step S10.

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

[0077] Next, in step S11, the control unit 201 makes a determination regarding the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10. Specifically, the control unit 2 makes a determination regarding the lifespan of the sensor unit 1 based on at least one of the number of corrections or the magnitude of the correction value 50 when corrections are made.

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

[0079] Furthermore, the other configurations in the second embodiment are the same as those in the first embodiment described above.

[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 deteriorated gas sensors 10 based on the output values ​​30 of the multiple gas sensors 10, and to make a determination regarding the lifespan of the sensor unit 1 based on the correction status. As a result, the lifespan of the gas sensors 10 can be extended by correcting the deteriorated gas sensors 10. Furthermore, since the determination regarding the lifespan of the sensor unit 1 is made based on the correction status, even in a configuration where the lifespan of the gas sensors 10 is extended by correcting the gas sensors 10, the determination regarding the lifespan of the sensor unit 1 can be made with high accuracy.

[0082] Furthermore, in the second embodiment, as described above, the control unit 201 is configured to make a determination regarding the lifespan of the sensor unit 1 based on at least one of the number of corrections or the magnitude of the correction value 50 used when performing the correction. This makes it possible to easily make a determination regarding the lifespan of the sensor unit 1 in a configuration in which the lifespan of the gas sensor 10 can be extended by obtaining at least one of the number of corrections or the magnitude of the correction value 50.

[0083] Furthermore, the other effects of the second embodiment are the same as those of the first embodiment described above.

[0084] (modified version) It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than by the description of the embodiments above, and further includes all modifications (exceptions) within the meaning and scope equivalent to the claims.

[0085] For example, in the first and second embodiments described above, an example was shown in which the control unit 2 (control unit 201) makes a determination regarding the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10 and the deterioration status of the multiple gas sensors 10. However, the present invention is not limited thereto. For example, the control unit may be configured to make a determination regarding the lifespan of the sensor unit without using the deterioration status of the multiple gas sensors, as long as the output values ​​of the multiple gas sensors are used.

[0086] Furthermore, in the first embodiment described above, an example was shown in which the control unit 2 makes a determination regarding the lifespan of the sensor unit 1 based on the number of gas sensors 10 that have deteriorated among the plurality of gas sensors 10, but the present invention is not limited to this. For example, the control unit may be configured to make a determination regarding the lifespan of the sensor unit based on the degree of deterioration of the plurality of gas sensors.

[0087] Furthermore, while the second embodiment described above shows an example in which the control unit 201 makes a determination regarding the lifespan of the sensor unit 1 based on at least one of the number of corrections performed on the multiple gas sensors 10 or the magnitude of the correction value 50, the present invention is not limited thereto. For example, the control unit may be configured to make a determination regarding the lifespan of the sensor unit based on both the number of corrections performed on the multiple gas sensors and the magnitude of the correction value 50. In this case, the control unit may be configured to store both the number of corrections performed and the correction value 50 as correction information in the storage unit.

[0088] Furthermore, while the first and second embodiments described above show an example of a configuration in which the control unit 2 (control unit 201) makes a determination regarding the lifespan of the sensor unit 1 based on the number of deteriorated gas sensors 10, the number of corrections, and the correction value 50, the present invention is not limited thereto. For example, the control unit may be configured to make a determination regarding the lifespan of the sensor unit based on how much the base value of the output values ​​of the multiple gas sensors 10 has risen relative to a threshold. 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 value of the output value exceeds the threshold, or when the base value rises to a value higher than half of the threshold when compared with the initial base value.

[0089] Furthermore, while the first and second embodiments described above show an example configuration in which the control unit 2 (control unit 201) makes a determination regarding 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, the present invention is not limited thereto. For example, the control unit may be configured to make a determination regarding 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] Furthermore, while the first and second embodiments described above show an example configuration in which the control unit 2 (control unit 201) makes a determination regarding the lifespan of the sensor unit 1 based on the output values ​​30 of the multiple gas sensors 10, the present invention is not limited thereto. For example, the control unit may be configured to make a determination regarding the lifespan of the gas detector based on the output values ​​of the multiple gas sensors.

[0091] Furthermore, while the first and second embodiments described above show examples where the threshold value Th is set to 10% of the 10% LEL of the gas to be detected, the present invention is not limited thereto. For example, the threshold may be set by obtaining the variance of the output values ​​of multiple gas sensors and setting it as 1σ of the variance, or by setting the threshold value as 20% of the mean value.

[0092] Furthermore, while the first and second embodiments described above show examples of configurations in which all of the gas sensors 10 are used to detect the target gas, the present invention is not limited thereto. It is not necessary to use all of the gas sensors when detecting the target gas. However, even if not all of the gas sensors are used when detecting the target gas, it is still necessary to drive all of the gas sensors.

[0093] Furthermore, while the first and second embodiments described above show an example in which the control unit 2 (control unit 201) acquires the concentration of the gas to be detected based on the output values ​​30 of a plurality of gas sensors 10, the present invention is not limited thereto. 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 a plurality of gas sensors.

[0094] Furthermore, while the first and second embodiments described above show examples of configurations in which gas is detected at a predetermined temperature at predetermined time intervals of approximately 60 seconds, the present invention is not limited thereto. In the present invention, gas may be detected at predetermined time intervals other than 60 seconds.

[0095] Furthermore, although the first and second embodiments described above show examples in which the multiple gas sensors 10 are semiconductor-type gas sensors, the present invention is not limited thereto. For example, the multiple gas sensors may be electrochemical sensors (potential-constant electrolytic type, diaphragm galvanic cell type), catalytic combustion type gas sensors, or gas thermal conduction type gas sensors. When the multiple gas sensors are configured as gas sensors other than semiconductor-type sensors, it is necessary to arrange each gas sensor within a predetermined range (for example, a few centimeters) in order for the multiple gas sensors to detect the same target gas.

[0096] Furthermore, although the first and second embodiments described above used methane as an example of the gas to be detected, 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, while the first and second embodiments described above show examples of configurations in which the gas detector 100 detects a single type of target gas, the present invention is not limited thereto. In the present invention, the target gas may include a predetermined type of first target gas and a second target gas of a different type 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 and 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, while the first and second embodiments described above show examples of gas detectors 100 comprising a notification unit 3 and a communication unit 6, the present invention is not limited thereto. In the present invention, the gas detector may be provided with only one of the notification unit and the communication unit. For example, the gas detector may not be provided with a communication unit. Also, the gas detector may not be provided with a notification unit. In this case, the notification unit may be provided separately from the gas detector. Furthermore, even if the gas detector is provided with a notification unit, notification may be performed by an external device to the gas detector.

[0099] Furthermore, while the first and second embodiments described above show examples of configurations in which the notification unit 3 changes the notification content by changing the way it lights up or the sound it makes depending on the result of the determination regarding the lifespan of the sensor unit 1, the present invention is not limited thereto. The notification unit may be configured to notify only when the sensor unit reaches the end of its lifespan, and not to notify otherwise.

[0100] Furthermore, in the first and second embodiments described above, for the sake of explanation, an example was shown in which the control processing by the control unit 2 (control unit 201) was explained using a flow-driven flowchart that processes sequentially according to the processing flow, but the present invention is not limited thereto. In the present invention, the control processing may be performed by event-driven processing, which executes processing on an event-by-event basis. In this case, it may be performed as a completely event-driven system, or a combination of event-driven and flow-driven systems may be used. [Explanation of Symbols]

[0101] 1. Sensor section 2, 201 Control Unit 3. News Department 10, 10a~10c Multiple gas sensors 14. Circuit board (chip) 22 History Information 30 Output Value 50 Correction value 100, 200 gas detectors

Claims

1. A gas detector that detects the target gas, A sensor unit including multiple gas sensors of the same type, mounted on the same chip, The system includes a control unit that acquires the output values ​​of the plurality of gas sensors, A gas detector in which the control unit is configured to make a determination regarding the lifespan of the sensor unit based on the output values ​​of the plurality of gas sensors.

2. The gas detector according to claim 1, wherein the control unit is configured to make a determination regarding the lifespan of the sensor unit based on the output values ​​of the plurality of gas sensors and the deterioration status of the plurality of gas sensors.

3. The gas detector according to claim 2, wherein 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, and to make a determination regarding the lifespan of the sensor unit based on the number of gas sensors that have deteriorated.

4. 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 the deteriorated gas sensor based on the output values ​​of the plurality of gas sensors, and to make a determination regarding the lifespan of the sensor unit based on the state of the correction, as described in claim 2.

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

6. The gas detector according to any one of claims 1 to 5, wherein the control unit is configured to make a determination regarding the lifespan of the sensor unit based on the output values ​​of the plurality of gas sensors and the history information of the plurality of gas sensors.

7. The system further includes a notification unit capable of notifying the result of the life determination of the sensor unit, The gas detector according to claim 1, wherein the notification unit is configured to change the notification content according to the result of the determination regarding the lifespan of the sensor unit.

8. A step of acquiring the output values ​​of the multiple gas sensors in a sensor unit that includes multiple gas sensors of the same type provided on the same chip, A method for determining the lifespan of a gas sensor, comprising the step of determining the lifespan of the sensor unit based on the output values ​​of the plurality of gas sensors.

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