Optical gas sensor device and gas detection method

Abstract

The invention relates to an optical gas sensor device and a gas detection method. The present invention suppresses a variation in a gas concentration value based on a change in substrate temperature. An optical gas sensor device (100) is provided with: a light source (2) that emits infrared rays toward a gas (G) to be detected; an optical filter (3) that transmits infrared rays having a wavelength corresponding to the absorption wavelength of the gas (G) to be detected; a light receiving unit (4) that detects the infrared rays incident through the optical filter (3) and generates a detection signal; a substrate (6) on which the light source (2) and the light receiving unit (4) are mounted; and a signal processing unit (5). The signal processing unit (5) performs intermittent drive control on / off of the light source (2), and calculates the gas concentration value of the gas (G) to be detected on the basis of a difference value obtained by subtracting the detection value of the detection signal when the light source (2) is turned off from the detection value of the detection signal when the light source (2) is turned on.

Description

Technical Field

[0001] The present invention relates to an optical gas sensor device and a gas detection method. Background Art

[0002] In the past, gas sensors based on the non-dispersive infrared absorption method (NDIR) are known. NDIR gas sensors are sensors that utilize the property that multiple gases absorb their own infrared wavelengths, and when radiating infrared rays to the gas to be detected, detect how much of which wavelength is absorbed, thereby measuring the concentration in the gas to be detected. For example, a gas sensor that has an infrared light-emitting unit and a light-receiving unit detects the concentration of the gas to be detected located on the optical path of the light-emitting unit and the light-receiving unit.

[0003] For example, a non-dispersive infrared gas sensor is known, which has a light source arranged in a lens barrel into which a gas to be measured is introduced, an infrared wavelength selection filter and an infrared detection unit arranged on a block different from the lens barrel to face the light source (see Patent Document 1). The non-dispersive infrared gas sensor alternately and periodically switches the light source to a first set light intensity and a second set light intensity smaller than the first set light intensity. The non-dispersive infrared gas sensor obtains the average value of two consecutive detection signals of the first set light intensity and the difference between the detection signals of the second set light intensity therebetween, and converts them into gas concentration, thereby suppressing the reduction in the measurement accuracy of the gas concentration accompanying the change of the measurement environment.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-135258 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In gas sensors, it is required to install the light source and the light receiving unit on the same substrate in order to achieve miniaturization and simplify the device structure. In this structure, the heat from the light source is transferred to the light receiving unit via the substrate, which has a great influence on the gas detection signal in the light receiving unit. It is required to suppress the change of the gas concentration value calculated based on the gas detection signal based on the change of the substrate temperature.

[0008] An object of the present invention is to suppress the variation in gas concentration value due to the change in substrate temperature.

[0009] Means for solving problems

[0010] In order to solve the above problems, the optical gas sensor device of the present invention has:

[0011] A light source that emits infrared rays toward the gas to be detected;

[0012] an optical filter that transmits infrared light having a wavelength corresponding to an absorption wavelength of the gas to be detected;

[0013] a light receiving unit that detects the infrared rays incident through the optical filter and generates a detection signal;

[0014] a substrate on which the light source and the light receiving unit are mounted; and

[0015] A signal processing unit performs intermittent drive control on / off of the light source, and calculates the gas concentration value of the gas of the detection object based on a difference value obtained by subtracting the detection value of the detection signal when the light source is turned on from the detection value of the detection signal when the light source is turned off.

[0016] In addition, the present invention is a gas detection method of an optical gas sensor device.

[0017] The optical gas sensor device comprises:

[0018] A light source that emits infrared rays toward the gas to be detected;

[0019] an optical filter that transmits infrared light having a wavelength corresponding to an absorption wavelength of the gas to be detected;

[0020] a light receiving unit that detects infrared light incident through the optical filter and generates a detection signal; and

[0021] a substrate on which the light source and the light receiving unit are mounted,

[0022] The gas detection method includes a signal processing step, in which the on / off of the light source is intermittently driven and controlled, and the gas concentration value of the gas of the detection object is calculated based on the difference value obtained by subtracting the detection value of the detection signal when the light source is turned on from the detection value of the detection signal when the light source is turned off.

[0023] In addition, the gas detection program product of the present invention enables the computer of the optical gas sensor device to function as a signal processing unit.

[0024] The optical gas sensor device comprises:

[0025] A light source that emits infrared rays toward the gas to be detected;

[0026] an optical filter that transmits infrared light having a wavelength corresponding to an absorption wavelength of the gas to be detected;

[0027] a light receiving unit that detects infrared light incident through the optical filter and generates a detection signal; and

[0028] a substrate on which the light source and the light receiving unit are mounted,

[0029] The signal processing unit performs intermittent drive control on / off of the light source, and calculates the gas concentration value of the gas of the detection object based on the difference value obtained by subtracting the detection value of the detection signal when the light source is turned on from the detection value of the detection signal when the light source is turned off.

[0030] Effects of the Invention

[0031] According to the present invention, it is possible to suppress the variation in gas concentration value due to the change in substrate temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of an optical gas sensor device according to an embodiment of the present invention.

[0033] Figure 2 It is a perspective view of an optical gas sensor device.

[0034] Figure 3 It is a stereogram of the light source.

[0035] Figure 4 It is a diagram showing the circuit structure of an optical gas sensor device and an apparatus.

[0036] Figure 5 : is a flowchart showing the status signal generation process.

[0037] Figure 6 : is a flowchart showing the light source intermittent drive control process.

[0038] Figure 7 Yes means Figure 5 Flowchart of the measurement loop processing of the status signal generation processing.

[0039] Figure 8 is a diagram showing the waveform of the status signal.

[0040] Fig. 9 It is a diagram showing various timings of waveforms of turning on and off of a light source.

[0041] Fig.10 (a) is a graph showing the time characteristics of the detection value when the light source is turned on, and (b) is a graph showing the time characteristics of the detection value when the light source is turned off.

[0042] Fig.11 It is a diagram showing the time characteristics of the difference value of the detection value. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the scope of the present invention is not limited to the examples shown in the drawings.

[0044] First, refer to Figure 1 , a schematic structure of the optical gas sensor device 100 according to the present embodiment will be described. Figure 1 1 is a schematic diagram of an optical gas sensor device 100 according to the present embodiment.

[0045] like Figure 1 As shown, the optical gas sensor device 100 of the present embodiment is a NDIR gas sensor, and includes an optical cover 1, a light source 2, an optical filter 3, a light receiving unit 4, a signal processing unit 5, and a switch 81. The optical gas sensor device 100 radiates (emit, emit) infrared rays from the light source 2, and emits the infrared rays to the gas G of the detection target (measurement target) in the optical cover 1 via the optical path (path) in the optical cover 1. The molecules of the gas G of the detection target existing in the optical path absorb the infrared rays, thereby reducing the amount of light reaching the light receiving unit 4. The optical gas sensor device 100 detects that the gas G of the detection target absorbs a part of the infrared rays through the light receiving unit 4 via the optical filter 3, and processes the detection signal through the signal processing unit 5, and detects (measures) the concentration of the gas G of the detection target and outputs it. The switch 81 is a switch that turns on / off the light emission of the light source 2, and is included in the circuit element unit 8 described later. When performing gas detection, the signal processing unit 5 turns on / off the light source 2 via the switch 81 to perform intermittent operation. The optical cover 1 has a gas inlet port 11 as a gas inlet portion for introducing the gas G to be detected. To prevent foreign matter from entering from the outside, a contamination filter 12 is attached to the gas inlet port 11. The contamination filter 12 is, for example, a metal mesh filter or a porous resin film.

[0046] In particular, the optical gas sensor device 100 filters the infrared rays emitted from the light source 2 to the gas G to be detected by the optical filter 3 and receives the infrared rays by the light receiving unit 4. The optical filter 3 is arranged at a position near the light receiving unit 4 on the optical path upstream of the light receiving unit 4. Compared with the structure in which the infrared rays emitted from the light source 2 are filtered by the optical filter and then emitted to the gas G to be detected, this structure only needs to filter by the light receiving surface of the light receiving unit 4, so the area of ​​the optical filter 3 can be reduced, and the cost can be reduced. In addition, the infrared rays before filtering emitted from other than the light source 2 are not received, and the SN ratio (Signal to Noise ratio) of the sensor is improved. However, the optical gas sensor device 100 can also be configured to filter the infrared rays emitted from the light source 2 by the optical filter 3 and emit them to the gas G to be detected. In this embodiment, in addition to the optical path where the infrared rays received by the light receiving unit 4 via the optical filter 3 directly arrive from the light source 2, the optical path is designed in a manner that the infrared rays are reflected on the inner surface of the optical cover 1 and arrive. The higher the reflectivity of the inner surface of the optical cover 1 is, the higher the light (infrared ray) utilization efficiency is, and this is preferred.

[0047] The optical gas sensor device 100 detects the refrigerant of the air conditioner, i.e., the alternative Freon refrigerant, using the gas G as the detection object. Alternative Freon is a refrigerant of a synthetic compound (gas) used industrially as a substitute for a specific Freon (chlorofluorocarbon, abbreviated as: CFC). CFC refrigerants have a high ozone depletion coefficient and become the cause of the depletion of the earth's ozone layer. Therefore, they are beginning to be replaced by hydrochlorofluorocarbon (HCFC) refrigerants with a low ozone depletion coefficient. In addition, in developed countries, the conversion from HCFC refrigerants to HFC refrigerants (R410A) with an ozone depletion coefficient of 0 is underway.

[0048] It is known that CFC refrigerants, HCFC refrigerants, and HFC refrigerants have high global warming potentials and are greenhouse gases that cause global warming. Therefore, research is underway to replace HFC refrigerants (R410A) with HFC refrigerants (R32) that have lower global warming potentials. In this embodiment, for example, as the gas G to be detected, detection of R32, a freon-based refrigerant, is performed.

[0049] The optical gas sensor device 100 outputs various status signals based on the gas concentration value of the detected gas G to an information processing unit of a device that performs processing based on the status of the optical gas sensor device 100. For example, the information processing unit is described later. Figure 4MCU (Micro Controller Unit) 200 in. The status signal is, for example, a fault signal, an alarm signal, and a monitoring signal (normal signal). The fault signal indicates the state of a fault in the optical gas sensor device 100. The alarm signal indicates that the concentration of the detected gas G is in an abnormal state (alarm state) that requires an alarm. The monitoring signal indicates that the concentration of the detected gas G is in a normal state. In the case where the device is an alarm, various alarms are reported based on various signals received from the optical gas sensor device 100 (for example, an alarm of a fault in the optical gas sensor device 100 based on a fault signal, an alarm of an abnormal concentration of the detected gas G based on an alarm signal). The device may be a device 230 ( Figure 4 ), or a device different from the optical gas sensor device 100 (including an external device of the MCU 200 (for example Figure 4 The above-mentioned equipment includes indoor air conditioners, air conditioners for shops and offices, multi-air conditioners for buildings, etc.

[0050] However, the gas G to be detected is not limited to R32, but may be other Freon-based refrigerants. Furthermore, the gas G to be detected is not limited to Freon-based refrigerants, but may be carbon dioxide, carbon monoxide, propane, methane, butane, ammonia, oxygen disulfide, nitrogen dioxide, nitrogen monoxide, ozone, sulfur hexafluoride, ethylene, etc.

[0051] Next, refer to Figure 2 , Figure 3 , the specific device structure of the optical gas sensor device 100 is described. Figure 2 It is a perspective view of the optical gas sensor device 100 . Figure 3 is a stereogram of the light source 2.

[0052] like Figure 2 As shown, specifically, the optical gas sensor device 100 includes: an optical cover 1, a light source 2, an optical filter 3, a light receiving unit 4, a signal processing unit 5, a substrate 6, a connector 7, and a circuit element unit 8. Figure 2 In the figure, the x-axis, y-axis, and z-axis are shown. These three axes are Figure 3 The same is true in Chinese.

[0053] The optical cover 1 is a cover as follows: it is installed on the surface on the +z side of the substrate 6, covers (includes) the light source 2, the optical filter 3 and the light receiving part 4, and forms a space inside that can accommodate the gas G of the detection object, and the gas G of the detection object is introduced and discharged into the space via the gas inlet port 11. The base of the optical cover 1 is made of resin, for example, and has a plurality of planar or curved inner surfaces. The inner surface of the base of the optical cover 1 is covered with an infrared reflective film. In the present embodiment, gold is used as the infrared reflective film, but it is not limited to this. As the infrared reflective film, silver, aluminum or a dielectric multilayer film can be used. And, as needed, in order to prevent corrosion of the metal film of the infrared reflective film, a protective film such as silicon oxide or silicon nitride can be formed on the infrared reflective film. The film forming method of the infrared reflective film and the protective film can use a plating method, a sputtering method, a vacuum evaporation method, etc.

[0054] The optical cover 1 reflects infrared light emitted from the light source 2 by using an infrared reflective film, so that at least a portion of the reflected light reaches the light receiving unit 4 via the optical filter 3, thereby playing a role of efficiently guiding the infrared light from the light source 2 to the light receiving unit 4 as an optical path. Figure 2 The shape, size, and position of the gas introduction port 11 for the gas G of the optical cover 1 are merely examples and are not limited thereto.

[0055] like Figure 3 As shown, the light source 2 is a MEMS (Micro Electro Mechanical Systems) type light source mounted on the upper surface (surface on the +z side) of the substrate 6, for example, a membrane M having a membrane structure is formed. The light source 2 has an electrode 231 and a pad P1 provided on the +x direction side, and an electrode 232 and a pad P2 provided on the -x direction side.

[0056] The light source 2 is a diaphragm M disposed on a Si substrate, and has a structure in which, for example, a light source layer support layer, a light source layer 21, an electrode support layer, and a protective layer (all omitted in the figure) are stacked from the -z direction side to the +z direction side. The light source layer support layer has, for example, a silicon oxide film, a silicon nitride film, and an HLD (High temperature Low pressure Dielectric layer) layer from the -z direction side to the +z direction side. The light source layer 21 is a thin film heater as a light source (metal) layer (light-emitting layer) that radiates infrared rays, and is composed of, for example, MoSi2. The light source layer heats the diaphragm M by energizing it, and radiates infrared rays having an intensity and wavelength dependence that depends on the surface temperature and the surface emissivity. The electrode support layer has, for example, two insulating layers from the -z direction side to the +z direction side, and supports the electrode. The protective layer is a protective layer of the upper surface composed of an insulator.

[0057] The light source layer 21 is electrically connected to the electrodes 231 and 232. The pad P1 is a pad for wire bonding and is electrically connected to the electrode 231. The pad P2 is a pad for wire bonding and is electrically connected to the electrode 232. The pads P1 and P2 are wire-bonded to the terminals of the wiring pattern on the substrate 6, and by applying a voltage, the light source layer 21 is energized and emits infrared rays.

[0058] The light source 2 as a MEMS type light source is small / thin, and can realize miniaturization as a sensor module. In addition, the light source 2 as a MEMS type light source has the characteristics of long life, low power consumption, and short response time, and can realize low power consumption as a whole sensor module. The characteristic of the short response time of the MEMS type light source is that in the case of intermittent driving, the standby time after power-on can be shortened, and the average power consumption can be reduced.

[0059] In addition, the light source 2 as a MEMS type light source can directly utilize the radiated light from the surface of the high temperature part, so it can also be applied to the detection of gases with absorption bands at high wavelengths. In addition, the area of ​​the light source 2 that radiates infrared rays is patterned with high precision on the plane of the Si substrate of the diaphragm M, and the individual deviation of the radiation direction is very small. Therefore, the deviation of the amount of light received when the sensor module is composed of the light source 2 is reduced, which helps to improve the product yield. In addition, the light source 2 is produced together with the MEMS technology based on the silicon wafer, so it is excellent in mass production.

[0060] The light source 2 is a surface mount component by direct mounting (COB: Chip On Board) on the substrate 6. However, the light source 2 is not limited thereto, and may be a DIP (Dual Inline Package) component (CAN package, etc.).

[0061] like Figure 1As shown, the optical filter 3 is a filter that is provided in a manner that covers the light receiving surface of the light receiving unit 4 and transmits light (infrared light) in a band corresponding to the absorption wavelength inherent in the gas G to be detected. In this way, the transmission wavelength of the optical filter 3 is designed to coincide with the absorption wavelength inherent in the gas G to be detected, thereby suppressing the change in light quantity caused by gases other than the gas G to be detected, and improving the SN ratio of the detection signal of the light receiving unit 4. More specifically, the optical filter 3 filters the infrared light of the wide band that is incident from the light source 2 and passes through the gas G, and transmits the infrared light in the band corresponding to the absorption wavelength of the gas G. In addition, in addition to a bandpass filter that transmits only wavelengths of a specific band, the optical filter 3 can also be set as a longpass filter that transmits an infrared band in a wavelength region corresponding to the absorption wavelength of the gas G as a transmission wavelength greater than a cut-on wavelength. The longpass filter is a filter that cuts off light on the wavelength side shorter than a specific cut-on wavelength and transmits light on the long wavelength side.

[0062] The optical filter 3, for example, has a silicon substrate and a dielectric multilayer film as a substrate, or a multilayer film formed by infrared transmission materials such as Si, Ge, sulfide and fluoride. The silicon substrate is a planar silicon substrate. The material of the substrate is not limited to silicon, and Ge (germanium), quartz, aluminum oxide, BaF2 (barium fluoride), CaF2 (calcium fluoride) etc. can be used. The multilayer film is a plurality of layered films arranged on both sides of the silicon substrate. In addition, the planar shape of the optical filter 3 is circular, but is not limited to this, and can also be other shapes such as rectangle.

[0063] The light receiving unit 4 is mounted on the surface of the +z side of the substrate 6, and is a thermopile type optical sensor (infrared sensor) having a plurality of thermocouples, and detects the amount of incident infrared light and outputs a detection signal as an analog electrical signal. However, the light receiving unit 4 is not limited to a thermopile type infrared sensor, and may be an infrared sensor of various types shown in Table 1 below.

[0064] Table I

[0065]

[0066] In addition, the light receiving unit 4 is, for example, an infrared sensor of a CAN package, but is not limited to this structure.

[0067] The signal processing unit 5 is mounted on a plane area other than the optical cover 1 on the surface on the +z side of the substrate 6, and is an AFE (Analog Front End)-IC (Integrated Circuit) that is an electronic component (processor) that performs signal processing related to the detection signal of the light receiving unit 4. The signal processing unit 5 amplifies the analog detection signal of the light receiving unit 4 and performs AD conversion, and generates a differential value of the detection value when the light source 2 is turned off based on the detection value when the light source 2 is turned on. The signal processing unit 5 performs corrections on the differential value of the detection value for temperature, individual deviations of the optical gas sensor device 100, etc., and generates various status signals based on the differential value of the digital detection value. The signal processing unit 5 outputs the differential value of the digital detection value and the status signal.

[0068] The substrate 6 is a PCB (Printed Circuit Board) with conductor wiring printed on a board of glass epoxy resin or the like. The optical cover 1, the light source 2, the light receiving unit 4, the signal processing unit 5, the connector 7, and the circuit element unit 8 are mounted on the surface on the +z side of the substrate 6. The +z side surface of the substrate 6 is approximately parallel to the light receiving surfaces of the optical filter 3 and the light receiving unit 4.

[0069] The connector 7 is mounted on the plane area other than the optical cover 1 and the signal processing unit 5 on the surface on the +z side of the substrate 6, and is a connector for outputting various digital signals output from the signal processing unit 5 to the information processing unit (MCU200) of the subsequent device 230 (set as an alarm). The connector 7 is connected to the MCU200 of the device 230 via a cable with a plug.

[0070] The circuit element section 8 includes switches such as the switch 81 , chip resistors, and chip capacitors.

[0071] Next, the optical path of infrared light of the optical gas sensor device 100 is described. In the optical gas sensor device 100, infrared light radiated from the light source 2 in the +z direction is absorbed by the gas G of the detection object in the optical cover 1. Together with the absorption, the infrared light is reflected in the ±x direction, ±y direction, and ±z direction on the inner surface of the optical cover 1, filtered by the optical filter 3, and reaches the light receiving part 4 and enters. The optical path becomes a straight optical path on a plane, or a light path that is reflected and bent by the inner surface of the optical cover 1. The inner surface of the optical cover can also be a plane, a curved surface, or a combination thereof, or a three-dimensionally wound tube with a polygonal, circular, or elliptical cross-section.

[0072] Next, refer to Figure 4 , the circuit structure of the optical gas sensor device 100 is described. Figure 4 It is a diagram showing the circuit configuration of the optical gas sensor apparatus 100 and the device 230 .

[0073] like Figure 4 As shown, the optical gas sensor device 100 has a circuit structure including a light source 2, a light receiving unit 4, a signal processing unit 5, and a circuit element unit 8. The signal processing unit 5 includes an amplifier 50, a temperature sensor 511, a clock generating unit 512, a multiplexer 52, an AD (Analog to Digital) converter 53, an NVM (Non-Volatile Memory) 54, a data processor 55, a communication unit 56, and a state output terminal 57. The circuit element unit 8 includes a switch 81 and resistors 82 and 83. In addition, the optical gas sensor device 100 is connected to the MCU 200 of the device 230. The device 230 includes an MCU 200, resistors 211 and 212, a capacitor 213, and a notification unit 214.

[0074] MCU200 is a control unit for controlling each part of the device 230, and has a communication unit 201. The communication units 56 and 201 are serial communication units of the I2C communication method. The communication unit 56 and the communication unit 201 of the optical gas sensor device 100 are connected via the clock line SCL and the data line SDA through the connector 7. The communication unit 201 generates a clock signal and outputs it to the communication unit 56, and sends and receives data signals to the communication unit 56. In addition, the communication method of the communication units 56 and 201 is not limited to IC2, and other serial communication methods such as UART (Universal Asynchronous Receiver / Transmitter) and CSI (Clocked Serial Interface) can also be used. In addition, MCU200 is connected to the status output terminal 57 via the signal line 220, and receives the status signal of the optical gas sensor device 100 described later from the optical gas sensor device 100. MCU200 controls the notification unit 214 according to the status signal of the optical gas sensor device 100. The notification unit 214 notifies the state of the optical gas sensor device 100 based on the state signal through display, sound output, etc. as described later, according to the control of the MCU 200 .

[0075] The power supply unit of the power supply voltage VDD is connected to the clock line SCL (serial clock) via the resistor 211, connected to the data line SDA (serial data) via the resistor 212, and connected to the ground via the capacitor 213. The resistors 211 and 212 are pull-up resistors. The power supply voltage VDD is removed from noise by the capacitor 213.

[0076] The light source 2 and the switch 81 are connected in series between the power supply unit of the power supply voltage VDD and the ground. The switch 81 is a switch for switching the light source 2 on / off. The switch 81 is composed of NMOSFET (N-channel Metal-Oxide-SemiconductorField Effect Transistor), CMOS (Complementary Metal-Oxide-Semiconductor), etc., and the gate as a control terminal is connected to the signal processing unit 5. In addition, the resistors 82 and 83 are connected in series between the power supply unit of the power supply voltage VDD and the ground. The node between the resistors 82 and 83 is connected to the input end of the light receiving unit 4. The power supply voltage divided by the resistors 82 and 83 is input to the input end of the light receiving unit 4. The light receiving unit 4 detects the infrared IR emitted from the light source 2 and input through the gas G and the optical filter 3, and outputs an analog detection signal from the output end.

[0077] In addition, the power supply voltage divided by the resistors 82 and 83 is input to the first input terminal of the amplifier 50. The output terminal of the light receiving unit 4 is connected to the second input terminal of the amplifier 50. The amplifier 50 amplifies the analog detection signal output from the light receiving unit 4 using the input divided power supply voltage and the detection signal input from the light receiving unit 4.

[0078] The output terminal of the amplifier 50 is connected to one of the multiple input terminals of the multiplexer 52. The temperature sensor 511 is connected to one of the multiple input terminals of the multiplexer 52, detects the temperature inside the optical cover 1 and generates an analog temperature signal, and outputs the generated analog temperature signal to the input terminal of the multiplexer 52.

[0079] The clock generation unit 512 is a clock generation circuit that generates a digital clock signal and outputs it to the data processor 55. The data processor 55 obtains the current time based on the clock signal input from the clock generation unit 512. The clock generation unit 512 may also be configured to be connected to the AD converter 53, generate an analog clock signal, and output it to the AD converter 53.

[0080] The multiplexer 52 multiplexes the amplified analog detection signal input from the light receiving unit 4, the analog temperature signal input from the temperature sensor 511, and the divided power supply voltage into one analog multiplexed signal, for example, according to the selection control of the signal from the data processor 55, and outputs it to the input end of the AD converter 53. The AD converter 53 converts the input multiplexed signal into a multiplexed signal of a digital detection signal of the light receiving unit 4, a digital temperature signal, and a digital divided power supply voltage, and outputs it to the data processor 55.

[0081] NVM54 is a memory for storing information in a non-volatile manner, for example, a threshold value M1 of a difference value of a detection value when the light source is turned on and when the light source is turned off, a threshold value A of a gas concentration value of gas G, a threshold value N of a light source voltage value, an initial failure determination period, a non-determination period, and a correction coefficient, which will be described later. Threshold value M1 is a threshold value for distinguishing a failure state and a normal state (a state not in a failure state) of the optical gas sensor device 100, and is a threshold value of a lower limit of a difference value of a detection value when the light source is turned on and when the gas G in a normal state is placed. Threshold value A is a threshold value for distinguishing an alarm state and a normal state (a state not in an alarm state) of the optical gas sensor device 100, and is a threshold value of an upper limit of a gas concentration value of gas G in a normal state.

[0082] The threshold value N is a threshold value for distinguishing between an abnormal state and a normal state (a state not being an abnormal state) of the voltage value (light source voltage value) applied to the light source 2, and is a threshold value of the upper limit of the light source voltage value in the normal state. The threshold value N is, for example, 3.3 [V].

[0083] The initial fault judgment period is a waiting time until the fault judgment of the initial state after the power supply of the optical gas sensor device 100 is turned on is completed, and is, for example, 2 [sec] preset based on experience or experiment. The non-judgment period is a waiting time for stabilizing the difference value of the detection value of the detection signal of the light receiving unit 4 after the initial fault judgment of the optical gas sensor device 100, and is, for example, 38 [sec] preset based on experience or experiment. The correction coefficient is a correction coefficient for performing correction processing such as temperature correction and correction of individual deviation of the optical gas sensor device 100 for the detection value of the light receiving unit 4.

[0084] The data processor 55 is a control unit main body (processor) that performs signal processing related to the detection signal of the light receiving unit 4, and has, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), and a storage unit. The CPU controls the optical gas sensor device 100. The RAM is a volatile memory that temporarily stores information. The storage unit is composed of a non-volatile memory (NVM: Non-Volatile Memory) such as a ROM (Read Only Memory), and stores various data and programs. It can also be configured so that the non-volatile memory, that is, NVM54, which is set separately from the data processor 55, also serves as the storage unit. In addition, as NVM54, a mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), a flash memory, etc. can be used. In the data processor 55, the CPU reads out the program stored in the storage unit and expands it in the RAM, and performs various processes by cooperating with the expanded program. The state signal generation program for executing the gas concentration measurement process described later is stored in the storage unit.

[0085] The data processor 55 calculates the gas concentration value of the gas G using the digital detection signal and digital temperature signal of the light receiving unit 4 input from the multiplexer 52 and the correction coefficient stored in the NVM54. The data processor 55 generates various status signals (fault signals, alarm signals, and monitoring signals described later) of the optical gas sensor device 100 based on the comparison and correction of the calculated gas concentration value and the light source voltage value with the threshold value stored in the NVM54. The data processor 55 sends the gas concentration value to the MCU200 of the device 230 via the communication unit 56. In addition, the data processor 55 sends the status signal of the optical gas sensor device 100 to the MCU200 via the status output terminal 57 according to the prescribed format. In addition, the data processor 55 can also be composed of circuits such as FPGA (Field Programmable Gate Array) and ASIC (Application Specific Integrated Circuit).

[0086] The communication unit 56 transmits and receives data signals (gas concentration values, etc.) to and from the communication unit 201 via the data line SDA.

[0087] Next, refer to Figures 5 to 9 , as an operation of the optical gas sensor device 100 , the operation of the data processor 55 of the signal processing unit 5 will be described. Figure 5 : is a flowchart showing the status signal generation process. Figure 6 : is a flowchart showing the light source intermittent drive control process. Figure 7 Yes means Figure 5 Flowchart of the measurement loop processing of the status signal generation processing. Figure 8 is a diagram showing the waveform of the status signal. Fig. 9 It is a diagram showing various timings of the waveform of the on and off of the light source 2.

[0088] The optical gas sensor device 100 is connected to the MCU 200 of the device 230 in advance, and the gas G to be detected is introduced into the interior of the optical cover 1 from the gas introduction port 11. The optical gas sensor device 100 is powered off. Figure 8 As shown in the waveform of the "power off" state signal, the output (state signal) from the state output terminal 57 of the signal processing unit 5 is always at a high level. However, the "power off" state signal is always at a high level when the pull-up resistor (not shown) of the signal line 220 of the device 230 of the connection destination of the optical gas sensor device 100 is turned on.

[0089] Then, the data processor 55 of the signal processing unit 5 uses the power input of the optical gas sensor device 100 by the user (step S10 ) as a trigger to execute the state signal generation process according to the state signal generation program stored in the internal storage unit.

[0090] First, the data processor 55 performs the initialization of the signal processing unit 5 and prepares the signal processing unit 5 for driving (step S11). Then, the data processor 55 fixes the PWM (Pulse Width Modulation) of the output state signal to a low level and controls the switch 81 to fix the light source 2 to be off (step S12). In step S12, Figure 8 As shown in the waveform of the "initial action" state signal, it is set to always be at a low level.

[0091] Then, the data processor 55 reads the initial fault determination period stored in the NVM 81, controls the switch 81 according to the clock signal generated by the clock generating unit 512, and starts the initial light source intermittent drive control of turning on / off the light source 2 (step S13). After step S13, the initial fault determination period is executed in parallel with the state signal generation process. Figure 6 In addition, the initial light source intermittent drive control is Fig. 9 The intermittent drive control of the light source 2 shown has a waveform of the light source off (extinguishing) time and the light source on (emitting) time, in which the light source off time is set to, for example, 200 [ms] and the light source on time is set to, for example, 200 [ms] in a repeated mode of intermittent drive control.

[0092] Here, refer to Figure 6 The intermittent drive control process of the light source is described. First, the data processor 55 controls the switch 81 to turn off the light source 2, and based on the clock signal generated by the clock generating unit 512, the detection value of the light receiving unit 4, the substrate temperature, and the voltage value of the light source 2 when the light source is turned off are measured and waited (step S31). Fig. 9 As shown, in the intermittent drive control of the light source 2, at the time t11 (t21 ...) which is the last (before the rise) timing of the light source on time, the detection value of the detection signal of the light receiving unit 4 when the light source is turned off, the substrate temperature of the substrate 6 based on the temperature sensor 511, and the light source voltage value of the light source 2 are measured. That is, in step S31, the data processor 55 waits from the beginning of the light source off time to the time of measuring the timing of its last measured value. The waiting time of step S31 corresponding to the initial intermittent drive control of step S13 is, for example, 200 [ms].

[0093] Then, the data processor 55 obtains the detection value from the detection signal of the light receiving unit 4, obtains the substrate temperature from the temperature sensor 511, and obtains the divided power supply voltage between the resistors 82 and 83. Furthermore, the data processor 55 calculates the voltage value applied to the light source 2 as the light source voltage value based on the divided power supply voltage, and measures the detection value, substrate temperature, and light source voltage value when the light source is turned off (step S32).

[0094] Then, the data processor 55 controls the switch 81 to turn on the light source 2, and based on the clock signal generated by the clock generating unit 512, the detection value of the light receiving unit 4, the substrate temperature, and the voltage value of the light source 2 when the light source is turned on are measured and waited (step S33). Fig. 9 As shown, in the intermittent drive control of the light source 2, at the time t12 (t22 ...) which is the last timing (before the fall) of the light source off time, the detection value of the light receiving unit 4 when the light source is off and the substrate temperature of the substrate 6 by the temperature sensor 511 are measured. That is, in step S33, the data processor 55 waits from the beginning of the light source on time to the timing of measuring the last measured value. The waiting time of step S33 corresponding to the initial failure judgment period of step S13 is, for example, 200 [ms].

[0095] Then, the data processor 55 obtains the detection value from the detection signal of the light receiving unit 4, obtains the substrate temperature from the temperature sensor 511, and measures the detection value when the light source is turned on and the substrate temperature (step S34). In addition, in step S34, the data processor 55 can also be configured to measure the voltage value (light source voltage value) applied to the light source 2, as in step S32.

[0096] Then, the data processor 55 reads the correction coefficient from the NVM 54, and uses the detection values ​​and substrate temperature when the light source is turned off and on measured in steps S32 and S34, and the read correction coefficient to calculate the difference value of the detection value, the average substrate temperature, and the gas concentration value (step S35). The process transfers to step S31. Fig. 9 As shown, step S35 is executed at time t13 (, t23 . . . ) after time t12 (, t22 . . . ) of step S34.

[0097] Here, the processing of step S35 is described in more detail. First, the data processor 55 subtracts the detection value when the light source is turned off obtained in step S32 from the detection value when the light source is turned on obtained in step S34, and calculates the difference value of the detection value of the light receiving part 4. Then, the data processor 55 calculates the average value of the substrate temperature when the light source is turned off measured in step S32 and the substrate temperature when the light source is turned on measured in step S34, that is, the substrate average temperature. Then, the data processor 55 uses the calculated difference value of the detection value and the substrate average temperature and the correction coefficient to calculate the gas concentration value. In addition, the data processor 55 sends the calculated gas concentration value to the MCU200 of the device 230 via the communication unit 56.

[0098] Back to Figure 5 The data processor 55 determines whether the initial failure determination period read in step S13 has passed since the light source was turned off (step S14) based on the clock signal generated by the clock generating unit 512. If the initial failure determination period has not passed (step S14; No), the process transfers to step S14.

[0099] When the initial fault determination period has passed (step S14; yes), the data processor 55 reads the specified fault condition from the NVM 54. The data processor 55 determines whether to detect the initial fault of the optical gas sensor device 100 based on whether the light source voltage value obtained in step S32 of the initial intermittent drive control and the difference value between the detection value when the light source is turned on and the detection value when the light source is turned off calculated in step S35 meet the read-out specified fault condition (step S15). The specified fault condition includes, for example, a threshold value M1 of the difference value between the detection value when the light source is turned on and the detection value when the light source is turned off and a threshold value N of the light source voltage value as a threshold value for the occurrence of a fault.

[0100] In step S15 , it is determined whether an initial failure of the optical gas sensor device 100 has occurred based on whether the difference value of the detection value when the light source is on and when the light source is off calculated in step S35 is less than M1 and the light source voltage value obtained in step S32 is greater than or equal to N.

[0101] When an initial fault is detected (step S15; yes), the data processor 55 sets the output state signal to the PWM of the fault mode and sets it as a fault signal (step S16). Figure 8 The PWM state signal of "fault" shown is output as a fault signal to the device 230. The fault signal is, for example, an intermittent signal with a low level period of 75 [msec], a high level period of 300 [msec], and a duty cycle of 80%. When the MCU 200 of the device 230 receives the fault signal from the signal processing unit 5 via the signal line 220, the notification unit 214 outputs the meaning of the fault of the optical gas sensor device 100.

[0102] Then, the data processor 55 reads the non-determination period stored in the NVM 81, controls the switch 81 according to the clock signal generated by the clock generating unit 512, and starts the normal intermittent drive control of turning on / off the light source 2 (step S17). After step S17, in the intermittent drive control of the light source executed in parallel with the state signal generation process, the on / off interval of the normal intermittent drive control process is applied to steps S31 and S33. The intermittent drive control of the light source is performed in parallel with the state signal generation process. Fig. 9 In the waveforms of the light source off time and the light source on time of the intermittent drive control of the light source 2 shown, the intermittent drive control is performed in a repetitive mode in which the light source off time is set to, for example, 750 [msec] and the light source on time is set to, for example, 250 [msec].

[0103] Then, the data processor 55 starts counting the non-determination period according to the clock signal generated from the clock generating unit 512, and stops outputting the status signal (step S18). The non-determination period is a standby period until the gas concentration value stabilizes. Since the gas concentration value is unstable, the output of the gas concentration value and the status signal is stopped. Then, the data processor 55 determines whether the non-determination period has passed since the counting started in step S18 according to the clock signal generated from the clock generating unit 512 (step S19). If the non-determination period has not passed (step S19; No), the process transfers to step S19.

[0104] When the non-determination period has passed (step S19; Yes), the data processor 55 sets the output state signal to the PWM of the monitoring mode and sets it as the monitoring signal (step S20). Figure 8 The PWM state signal of "monitoring" is output as a monitoring signal to the device 230. The monitoring signal is, for example, an intermittent signal having a low-level period of 300 [msec], a high-level period of 75 [msec], and a duty ratio of 20%.

[0105] Then, the data processor 55 executes the measurement cycle process (step S21). Figure 7 The measurement cycle processing of step S21 is described below. Figure 7 As shown, first, the data processor 55 obtains the difference value of the detection value of the light receiving unit 4, the average substrate temperature, and the gas concentration value (step S41). Step S41 is a step of obtaining the difference value of the detection value of the light receiving unit 4, the average substrate temperature, and the gas concentration value calculated in the previous step S35 in the light source intermittent drive control process.

[0106] Then, the data processor 55 reads the threshold value A for alarm determination from the NVM 54, and determines whether the gas concentration value that requires an alarm, i.e., the alarm concentration value, is detected based on whether the gas concentration value obtained in step S41 is greater than A (step S42). If the alarm concentration value is detected (step S42; yes), the data processor 55 sets the output status signal to the PWM of the alarm mode and sets it as an alarm signal (step S43). By step S43, a signal is generated. Figure 8 The PWM state signal of "alarm" shown is output as an alarm signal to the device 230. The alarm signal is, for example, an intermittent signal with a low level period of 150 [msec], a high level period of 225 [msec], and a duty cycle of 60%. When the MCU 200 of the device 230 receives the alarm signal from the signal processing unit 5 via the signal line 220, the notification unit 214 outputs an alarm indicating that the gas concentration value is high. The process is transferred to step S41.

[0107] When the alarm concentration value is not detected (step S42; No), the data processor 55 reads the prescribed fault condition from the NVM 54. And the data processor 55 determines whether to detect a normal fault (normal fault) of the optical gas sensor device 100 (step S44) based on whether the light source voltage value obtained in step S41 in the normal intermittent drive control and the difference value of the detection value when the light source is turned on and when the light source is turned off obtained in step S41 meet the read prescribed fault condition. The prescribed fault condition includes, for example, a threshold value M1 of the difference value of the detection value when the light source is turned on and when the light source is turned off and a threshold value N of the light source voltage value as a threshold value for the occurrence of a fault.

[0108] In step S44, similarly to step S15 of the initial fault determination, the occurrence of a normal fault in the optical gas sensor device 100 is determined based on whether the difference between the detection values ​​when the light source is turned on and when the light source is turned off obtained in step S41 is less than M1 and the light source voltage value obtained in step S41 is greater than or equal to N. However, the present invention is not limited thereto, and the fault determination method (fault conditions, etc.) of the initial fault determination may be different from the fault determination method (fault conditions, etc.) of the normal fault determination.

[0109] When a normal failure is not detected (step S44; No), the data processor 55 sets the output state signal to the PWM of the monitoring mode and sets it as a monitoring signal (step S45). Step S45 is the same as step S20. The process proceeds to step S41.

[0110] When a normal failure is detected (step S44; Yes), the data processor 55 sets the output state signal to PWM of the failure mode and sets it as a failure signal (step S46). Step S46 is the same as step S16. The process proceeds to step S41.

[0111] Next, refer to Fig.10 (a)~ Fig.11 , a specific example of gas concentration value detection is described. Fig.10 (a) is a graph showing the time characteristics of the detection value when the light source is turned on. Fig.10 (b) is a graph showing the time characteristics of the detection value when the light source is turned off. Fig.11 It is a diagram showing the time characteristics of the difference value of the detection value.

[0112] like Fig.10 As shown in (a), from 0 (when light source control starts) to 8 [min], R32 gas is not introduced into the space where the optical gas sensor device 100 is installed, so that the gas concentration value of R32 in the optical cover 1 is 0 [ppm]. Similarly, from 8 to 11 [min], R32 gas is introduced into the above space, so that the gas concentration value of R32 in the optical cover 1 is 5000 [ppm]. Similarly, from 11 to 14 [min], R32 gas is further introduced into the above space, so that the gas concentration value of R32 in the optical cover 1 is 10000 [ppm]. Similarly, from 14 to 17 [min], R32 gas is further introduced into the above space, so that the gas concentration value of R32 in the optical cover 1 is 15000 [ppm].

[0113] exist Fig.10 In (a), in the above-mentioned R32 gas state, the solid line represents the detection value of the light receiving unit 4 when the light source is turned on (emitting light) relative to time, and the dotted line represents the substrate temperature [°C] relative to the same time. The characteristic curve of substrate temperature [°C] relative to time is Fig.10 (a)~ Fig.11 Chinese Communist Party.

[0114] exist Fig.10 In (b), the solid line indicates the detection value of the light receiving unit 4 when the light source is turned off (extinguished) with respect to time. Fig.11In the above-mentioned R32 gas state, the difference value of the detection value of the light receiving unit 4 with respect to time (detection value when the light source is turned on - detection value when the light source is turned off) is represented by a solid line.

[0115] The light receiving unit 4 as an infrared sensor may not be able to fully read infrared rays due to the rapid change of the substrate temperature and the change of the detection value. Fig.10 As shown in (a), in order to calculate the gas concentration value based on the detection value when the light source is turned on, it is necessary to wait for more than 8 minutes from the start of the optical gas sensor device 100 to the rise of the substrate temperature to stabilize as a standby time. In particular, since the optical gas sensor device 100 has the light source 2 and the light receiving unit 4 mounted on the same substrate 6, the heat generated by the light source 2 is easily transferred to the light receiving unit 4 via the substrate 6, and the detection value of the light receiving unit 4 is easily unstable.

[0116] In contrast, Fig.11 As shown, by obtaining the difference between the detection values ​​when the light source is turned on and when the light source is turned off, the difference between the detection values ​​is stabilized in a short time, and the standby time can be shortened to about 30 [seconds].

[0117] As described above, according to the present embodiment, the optical gas sensor device 100 includes: a light source 2 that emits infrared light toward the gas G to be detected; an optical filter 3 that transmits infrared light of a wavelength corresponding to the absorption wavelength of the gas G to be detected; a light receiving unit 4 that detects the infrared light incident through the optical filter 3 and generates a detection signal; a substrate 6 on which the light source 2 and the light receiving unit 4 are mounted; and a signal processing unit 5. The signal processing unit 5 performs intermittent drive control of the on / off of the light source 2, and calculates the gas concentration value of the gas G to be detected based on the difference value obtained by subtracting the detection value of the detection signal when the light source 2 is turned on from the detection value of the detection signal when the light source 2 is turned off.

[0118] Therefore, in a structure in which the light source 2 and the light receiving unit 4 are mounted on the same substrate 6 and the light receiving unit 4 is easily affected by the heat of the light source 2, the change of the detection signal of the gas G based on the change of the substrate temperature can be suppressed, and the gas concentration value can be stabilized. In addition, the time from startup to the measurement of the normal gas concentration value can be shortened.

[0119] In addition, the optical gas sensor device 100 has a temperature sensor 511 for detecting the substrate temperature of the substrate 6. The signal processing unit 5 calculates the gas concentration value based on the difference between the substrate temperature and the detection value of the light receiving unit 4. More specifically, the temperature sensor 511 detects the substrate temperature when the light source is turned on and the substrate temperature when the light source is turned off. The signal processing unit 5 calculates the average substrate temperature, which is the average of the substrate temperature when the light source 2 is turned on and the substrate temperature when the light source 2 is turned off, and calculates the gas concentration value based on the difference between the substrate average temperature and the detection value of the light receiving unit 4. Therefore, it is possible to suppress the influence of the substrate temperature difference when the light source 2 is turned on and when the light source 2 is turned off and calculate a stable gas concentration value.

[0120] In addition, the light source 2 is a MEMS type light source. Therefore, the response time can be shortened, and the power consumption of the optical gas sensor device 100 can be reduced.

[0121] In addition, the optical gas sensor device 100 includes: an optical cover 1, which is provided on the substrate 6 in a manner covering the light source 2 and the light receiving unit 4, and is provided so that the infrared light passing through the optical filter 3 is reflected on its inner surface, and at least a part of the reflected light reaches the light receiving unit 4; and a gas introduction port 11, which introduces the gas G to be detected into the interior of the optical cover 1. Therefore, the gas concentration value of the gas G in the optical cover 1 can be accurately detected.

[0122] In addition, the signal processing unit 5 determines that the optical gas sensor device 100 has a fault when the difference value between the detection value when the light source is turned on and when the light source is turned off is lower than the threshold value M1 as the predetermined first threshold value, and the light source voltage value applied to the light source 2 is greater than the threshold value N as the predetermined second threshold value. Therefore, the optical gas sensor device 100 can be accurately determined to have a fault.

[0123] Signal processing unit 5 determines the state of optical gas sensor device 100 based on the gas concentration value, and outputs a state signal of the determined state to external device 230. Therefore, a state signal of optical gas sensor device 100 based on a stable and accurate gas concentration value can be output to device 230.

[0124] In addition, the description in the above-mentioned embodiment is an example of the optical gas sensor device, gas detection method, and program of the present invention, and is not limited thereto.

[0125] For example, in the above-mentioned embodiment, the data processor 55 is configured to calculate the difference between the detection values ​​of the light source 2 when the light source is turned on and when the light source is turned off in step S35 of the intermittent driving process of the light source. However, it is not limited to this structure. For example, it can also be configured so that the data processor 55 calculates "a second difference value obtained by further subtracting the change in two consecutive detection values ​​when the light source is turned off from the first difference value of the detection value when the light source 2 is turned on and when the light source is turned off" instead of "a difference between the detection values ​​of the light source 2 when the light source is turned on and when the light source is turned off". According to this structure, compared with the first difference value, the stabilization of the second difference value can be accelerated, and the time can be further shortened. Fig.11 Alternatively, the data processor 55 may calculate the gas concentration value using the calculated second difference value, the substrate average temperature, and the correction coefficient.

[0126] In addition, in the above-mentioned embodiment, the data processor 55 calculates the gas concentration value and generates the status signal by comparing it with various threshold values, but the present invention is not limited thereto. Alternatively, the data processor 55 may calculate a value corresponding to the gas concentration value and generate the status signal by comparing the value corresponding to the gas concentration value with various threshold values ​​corresponding thereto.

[0127] In the above embodiment, the optical gas sensor device 100 includes one set of light source 2, optical filter 3, and light receiving unit 4, but the present invention is not limited thereto. The optical gas sensor device may include a plurality of sets of light source 2, optical filter 3, and light receiving unit 4.

[0128] Furthermore, the detailed structure and detailed operation of the optical gas sensor device 100 in the above-described embodiment can be appropriately modified without departing from the gist of the present invention.

[0129] Explanation of symbols

[0130] 100 Optical gas sensor device

[0131] G Gas

[0132] 1 Optical cover

[0133] 11 Gas inlet port

[0134] 12 Contamination filter

[0135] 2 Light Source

[0136] 21 Light source layer

[0137] 231, 232 electrodes

[0138] P1, P2 pads

[0139] M Diaphragm

[0140] 3 Optical filters

[0141] 4 Light receiving part

[0142] 5 Signal processing unit

[0143] 50 Amplifier

[0144] 511 Temperature Sensor

[0145] 512 Clock Generation Unit

[0146] 52 Multiplexer

[0147] 53 AD converter

[0148] 54NVM

[0149] 55 Data Processor

[0150] 56 Ministry of Communications

[0151] SCL clock line

[0152] SDA data cable

[0153] 6 substrate

[0154] 7 Connectors

[0155] 8 Circuit Components

[0156] 81 Switch

[0157] 82, 83 Resistors

[0158] 230 devices

[0159] 200MCU

[0160] 201 Ministry of Communications

[0161] 211, 212 resistor

[0162] 213 Capacitor

[0163] 214 Reporting Department

[0164] 220 signal line.

Claims

1. An optical gas sensor device, It is characterized in that have: A light source that emits infrared rays toward the gas to be detected; an optical filter that transmits infrared light having a wavelength corresponding to an absorption wavelength of the gas to be detected; a light receiving unit that detects the infrared rays incident through the optical filter and generates a detection signal; a substrate on which the light source and the light receiving portion are mounted; as well as A signal processing unit performs intermittent drive control on / off of the light source, and calculates the gas concentration value of the gas of the detection object based on a difference value obtained by subtracting the detection value of the detection signal when the light source is turned on from the detection value of the detection signal when the light source is turned off.

2. The optical gas sensor device according to claim 1, It is characterized in that The optical gas sensor device includes: a temperature sensor for detecting a substrate temperature of the substrate; The signal processing unit calculates the gas concentration value based on the substrate temperature and the difference value.

3. The optical gas sensor device according to claim 2, It is characterized in that The temperature sensor detects the substrate temperature when the light source is turned on and the substrate temperature when the light source is turned off. The signal processing unit calculates a substrate average temperature which is an average of a substrate temperature when the light source is turned on and a substrate temperature when the light source is turned off, and calculates the gas concentration value based on the substrate average temperature and the difference value.

4. The optical gas sensor device according to claim 1, It is characterized in that The light source is a MEMS type light source.

5. The optical gas sensor device according to claim 1, It is characterized in that The optical gas sensor device comprises: an optical cover provided on the substrate so as to cover the light source and the light receiving portion, and provided so that the infrared light having passed through the optical filter is reflected on its inner surface and at least a part of the reflected light reaches the light receiving portion; as well as A gas introduction portion introduces the gas to be detected into the optical cover.

6. The optical gas sensor device according to claim 1, It is characterized in that The signal processing unit determines that the optical gas sensor device has failed when a difference value obtained by subtracting a detection value of the detection signal when the light source is turned on from a detection value of the detection signal when the light source is turned off is lower than a prescribed first threshold and a voltage value applied to the light source is greater than a prescribed second threshold.

7. The optical gas sensor device according to any one of claims 1 to 6, It is characterized in that The signal processing unit determines a state of the optical gas sensor device based on the gas concentration value, and outputs a state signal of the determined state to an external device.

8. A gas detection method of an optical gas sensor device, The optical gas sensor device comprises: A light source that emits infrared rays toward the gas to be detected; an optical filter that transmits infrared light having a wavelength corresponding to an absorption wavelength of the gas to be detected; a light receiving unit that detects infrared light incident through the optical filter and generates a detection signal; and a substrate on which the light source and the light receiving unit are mounted, It is characterized in that The gas detection method includes a signal processing step, which performs intermittent drive control on the on / off of the light source, and calculates the gas concentration value of the gas of the detection object based on the difference value obtained by subtracting the detection value of the detection signal when the light source is turned on from the detection value of the detection signal when the light source is turned off.

Images