JP2015045546A - Gas detector and gas detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas detector and a gas detection method for eliminating effects due to temperature and humidity and realizing detection with even higher accuracy.SOLUTION: Provided is a gas detector or a gas detection method including the steps of: driving a heater layer drive unit 22 so that a heater layer heats a gas sensing layer to place it in a detectable state and detecting a gas concentration on the basis of output from a gas detection unit 23; reading in a heater layer resistance value from a heater layer resistance detection unit 24 and detecting the temperature in the periphery of the gas sensing layer; reading in the heater layer resistance value from the heater layer resistance detection unit 24 and calculating the humidity in the periphery of the gas sensing layer on the basis of a change in the temperature rise characteristic of a heater layer resistance value after heater power-on; calculating a correction value on the basis of the calculated temperature and humidity; correcting the gas concentration using the correction value; and determining the presence of a gas from the corrected gas concentration.

Description

  The present invention relates to a low power consumption gas detection device and a gas detection method.

The gas detection device is generally used for applications such as a gas leak alarm. The gas sensor used in this gas detection device is a device that is selectively sensitive to a specific gas, for example, a reducing gas such as CO, CH ₄ , C ₃ H ₈ , C ₂ H ₅ OH, etc. High sensitivity, high selectivity, high response, high reliability, and low power consumption are indispensable.

  By the way, gas leak alarms that are widely used for household use are intended for detection of flammable gas for city gas and propane gas, for detection of incomplete combustion gas in combustion equipment, Alternatively, there are those having both of these functions, but the spread rate is not so high due to cost and installation problems. Therefore, from the viewpoint of improving the diffusion rate of the gas leak alarm device, it is desired to improve the installation property, specifically, to make the gas leak alarm device cordless by driving the battery.

Low power consumption is the most important for realizing battery drive. However, when CH ₄ or C ₃ H ₈ is detected by a catalytic combustion type or semiconductor type gas sensor, it is necessary to detect it by heating to a high temperature of 400 ° C. to 500 ° C. In order to heat to a high temperature with low power consumption, it is necessary to intermittently operate a gas sensor having an ultra-low heat capacity structure with a diaphragm structure or the like using a microfabrication process in accordance with a detection cycle.

  As a prior art of such a gas detection device, for example, there is a gas sensor having a diaphragm structure described in Patent Document 1 (Japanese Patent Laid-Open No. 2009-210342). The gas detection device 100 of FIG. 1 of Patent Document 1 includes a thin-film sensor element 20, an energization driving unit 12 that intermittently energizes the heater layer 6 to change the temperature of the gas detection layer 100, and a gas Gas detection means 13 for detecting the detection target gas based on the electrical resistance value of the detection layer 100, humidity detection means 14 for detecting the humidity of the detection target gas containing the detection target gas, and the humidity detection means 14 Humidity display means 15 for displaying humidity, a lithium battery (not shown) for supplying power to these, and correction means 17 for correcting electrical characteristics based on the humidity detected by the humidity detection means 14 are provided. Composed.

  The sensor element 20 is manufactured by sequentially stacking a support layer 5, a heater layer 6 and an insulating layer 7, a pair of electrodes 9, a gas detection layer 10, and a selective catalyst layer 11 on a Si substrate 1 by a semiconductor process. It is a thin film type device. As shown in the graph of FIG. 2 of Patent Document 1, gas is detected by the sensor resistance value of the gas detection layer 10 when driven by a pulsed voltage signal, and low power consumption is realized. . The prior art is like this.

JP 2009-210342 A (paragraphs [0033] to [0036], FIGS. 1 and 2)

The selective catalyst layer generally uses γ-Al ₂ O ₃ which is a porous body as a carrier in order to permeate and diffuse a detection gas such as CH ₄ , C ₃ H ₈ , and CO. Furthermore, in order to efficiently burn and remove the non-detection target gas, a noble metal catalyst (for example, Pt or Pd) is often carried.
In addition, the gas detection layer made of SnO ₂ also adopts a porous structure or a columnar structure to increase the specific area. By adopting such a configuration, the contact area with the detection target gas is increased, and the detection sensitivity is increased.

  In such a porous body or a columnar structure, there are many pores having an opening diameter of several nm to several μm. It is known that the pores tend to adsorb water by capillary condensation expressed by the following formula, and the amount of adsorption depends on humidity.

  Therefore, in a high humidity environment, moisture is adsorbed into the fine pores of the selective catalyst layer and the gas detection layer. This moisture has been a factor of latent heat of vaporization that causes an endothermic phenomenon during evaporation to change the temperature. In particular, the gas detector has a very small heat capacity, that is, it is easy to heat and cool, and such latent heat of vaporization cannot be ignored. In general, since the resistance value changes with temperature, the sensor resistance value of the gas detection layer 10 may also change. In addition, the gas detection characteristics vary depending on the ambient temperature of the external environment, which may cause a problem in detection reliability.

  The gas detection device of Patent Document 1 grasps the humidity from the sensor resistance value when the heater is turned off. However, in a high humidity environment, the sensor resistance value changes due to moisture adsorbed by fine pores and the ambient temperature. In some cases, the sensor resistance value includes an error.

  Accordingly, the present invention is to solve the above-described problems, and an object of the present invention is to provide a gas detection device and a gas detection method that eliminates the influence of temperature and humidity and realizes highly accurate detection. There is.

In order to solve the above problem, the invention described in claim 1
A gas sensor having a gas sensing layer whose electrical resistance is changed by contact with a gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A temperature detection unit that outputs a detection signal according to the temperature around the gas sensor;
A humidity detector that outputs a detection signal according to the humidity around the gas sensor;
A central processing unit to which a heater layer driving unit, a gas detection unit, a temperature detection unit and a humidity detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for detecting the temperature around the gas sensing layer based on the output from the temperature detection unit;
Humidity detection means for detecting the humidity around the gas sensing layer based on the output from the humidity detector,
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
Determination means for determining the presence or absence of gas from the corrected sensor output;
It is provided with this.

The invention described in claim 2
A gas sensor having a gas sensing layer whose electrical resistance is changed by contact with a gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A heater layer resistance detector for detecting a change in the heater layer resistance of the heater layer;
A central processing unit to which a heater layer driving unit, a gas detection unit and a heater layer resistance detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for reading the heater layer resistance value for the heater layer resistance from the heater layer resistance detector and detecting the temperature around the gas sensing layer;
A humidity detecting means for reading the heater layer resistance value for the heater layer resistance from the heater layer resistance detecting unit and detecting the humidity around the gas sensing layer based on a change in the temperature rise characteristic of the heater layer resistance value after the heater is turned on;
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
Determination means for determining the presence or absence of gas from the corrected sensor output;
It is provided with this.

The invention described in claim 3
The gas detection device according to claim 2,
The temperature detecting means is a means for reading the heater layer resistance value and calculating the ambient temperature from the heater layer resistance value, the temperature coefficient of the heater layer resistance, and the heater layer resistance value at the reference temperature. It is a detection device.

The invention described in claim 4
A gas sensor having a gas sensing layer whose electrical resistance is changed by contact with a gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A heater layer resistance detector for detecting a change in the heater layer resistance of the heater layer;
A temperature detection unit that outputs a detection signal according to the temperature around the gas sensor;
A central processing unit to which a heater layer driving unit, a gas detection unit, a heater layer resistance detection unit and a temperature detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for detecting the temperature around the gas sensing layer based on the output from the temperature detection unit;
A humidity detecting means for reading the heater layer resistance value for the heater layer resistance from the heater layer resistance detecting unit and detecting the humidity around the gas sensing layer based on a change in the temperature rise characteristic of the heater layer resistance value after the heater is turned on;
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
A determination means for determining the presence or absence of a gas based on the corrected gas concentration;
It is provided with this.

Moreover, the invention described in claim 5 is
In the gas detection device according to any one of claims 2 to 4,
The humidity detection means evaporates the moisture adsorbed on the gas sensing layer, which is heated for a predetermined period from the start of the heater on, as a change in the temperature rise characteristic of the heater layer resistance from the start of the heater on for the heater layer resistance. The first heater layer resistance value when the threshold was not reached and the second heater layer resistance value when the moisture adsorbed on the gas sensing layer that was sufficiently heated from the start of the heater on and evaporated were used. The gas detection device is a means for calculating a ratio and calculating a humidity corresponding to the ratio.

The invention described in claim 6
In the gas detection device according to any one of claims 2 to 4,
The humidity detection means is a heater in which moisture adsorbed on the gas sensing layer, which is a porous body, is sufficiently heated from the start of the heater on as a change in the temperature rise characteristic of the heater layer resistance value from the start of the heater on for the heater layer resistance. The gas detection device is a means for calculating a time to reach the layer resistance value and calculating a humidity corresponding to the time.

The invention described in claim 7
In the gas detection device according to any one of claims 1 to 6,
A filter cover for partitioning a space including at least the gas sensing layer from the outside;
A filter that is provided in the filter cover and that adsorbs a predetermined gas of the detection target gas and introduces the gas into the filter cover;
It is provided with this.

The invention described in claim 8
A gas sensor having a gas sensing layer whose electrical resistance characteristics change by contact with the gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A porous layer for detection;
A detection heater layer for heating the detection porous layer;
A detection heater layer driving section for driving the detection heater layer;
A detection heater layer resistance detector for detecting a change in the heater layer resistance of the detection heater layer;
A central processing unit to which a heater layer drive unit, a gas detection unit, a detection heater layer drive unit and a detection heater layer resistance detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
A detection heater layer driving means for driving the detection heater layer driving section so that the detection heater layer heats the detection porous layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for reading the heater layer resistance value for the detection heater layer resistance from the detection heater layer resistance detection unit and detecting the temperature around the gas detection layer;
The heater layer resistance value for the detection heater layer resistance is read from the detection heater layer resistance detection unit, and based on the change in the temperature rise characteristic of the heater layer resistance value for the detection heater layer resistance after the heater is turned on, Humidity detection means for detecting humidity;
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
A determination means for determining the presence or absence of a gas based on the corrected gas concentration;
It is provided with this.

The invention described in claim 9 is
The gas detection device according to claim 8,
The temperature detecting means is a means for reading the heater layer resistance value and calculating the ambient temperature from the heater layer resistance value, the temperature coefficient of the heater layer resistance, and the heater layer resistance value at the reference temperature. It is a detection device.

Moreover, the invention described in claim 10 is
A gas sensor having a gas sensing layer whose electrical resistance characteristics change by contact with the gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A porous layer for detection;
A detection heater layer for heating the detection porous layer;
A detection heater layer driving section for driving the detection heater layer;
A detection heater layer resistance detector for detecting a change in the heater layer resistance of the detection heater layer;
A temperature detection unit that outputs a detection signal according to the temperature around the gas sensor;
A central processing unit to which a heater layer drive unit, a gas detection unit, a detection heater layer drive unit, a detection heater layer resistance detection unit, and a temperature detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
A detection heater layer driving means for driving the detection heater layer driving section so that the detection heater layer heats the detection porous layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for detecting the temperature around the gas sensing layer based on the output from the temperature detection unit;
Humidity detection means for reading the heater layer resistance value for the detection heater layer resistance from the detection heater layer resistance detection unit and detecting the humidity around the gas detection layer based on a change in the temperature rise characteristic of the heater layer resistance value after the heater is turned on When,
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
A determination means for determining the presence or absence of a gas based on the corrected gas concentration;
It is provided with this.

Further, the invention described in claim 11 is
In the gas detector according to any one of claims 8 to 10,
The humidity detecting means adsorbs to the detection porous layer, which is heated for a predetermined period from the start of the heater on, as a change in the temperature rise characteristic of the heater layer resistance value from the start of the heater on for the detection heater layer resistance. First heater layer resistance value when the evaporated water does not completely evaporate, and second heater layer resistance when the moisture adsorbed on the porous porous body for detection, which is sufficiently heated from the start of heater ON, is evaporated The gas detection device is a means for calculating a ratio using the value and calculating a humidity corresponding to the ratio.

Further, the invention described in claim 12 is
In the gas detector according to any one of claims 8 to 10,
The humidity detection means evaporates the moisture adsorbed on the porous layer for detection, which is sufficiently heated from the start of the heater on, as a change in the temperature rise characteristic of the heater layer resistance value from the start of the heater on for the heater layer resistance. The gas detector is a means for calculating a time to reach the heater layer resistance value and calculating a humidity corresponding to the time.

The invention described in claim 13 is
In the gas detection device according to any one of claims 8 to 12,
A filter cover for partitioning a space including at least the gas sensing layer and the detection porous layer from the outside;
A filter that is provided in the filter cover and that adsorbs a predetermined gas of the detection target gas and introduces the gas into the filter cover;
It is provided with this.

Moreover, the invention described in claim 14 is
In the gas detection device according to any one of claims 1 to 13,
The gas sensor
A Si substrate having a through hole;
A diaphragm-like heat insulating support layer stretched over the opening of the through hole;
The heater layer provided on the thermal insulating support layer;
An electrical insulation layer provided to cover the thermal insulation support layer and the heater layer;
A pair of sensing electrode layers provided on the electrically insulating layer;
The gas sensing layer made of an oxide semiconductor, which is provided on the electrical insulating layer and the pair of sensing electrode layers and in the vicinity of the heater layer, and whose sensor resistance value is changed by the gas in contact with the gas sensing layer;
It is a sensor provided with this.

The invention described in claim 15 is
The gas detection device according to claim 14, wherein
The gas sensor is further provided so as to cover the surface of the gas sensing layer, and is made of an Al ₂ O ₃ sintered material that supports Pd (palladium), Pt (platinum), or an alloy containing Pd and Pt as a catalyst. A gas detection device comprising a gas selective combustion layer.

In addition, the invention described in claim 16
In the gas detection device according to any one of claims 1 to 15,
The gas detector is driven by power supplied from a power supply unit of a built-in battery.

Moreover, the invention described in claim 17 is
A gas sensing layer whose electrical resistance characteristics change by contact with the detection target gas, a gas sensor having a heater layer for heating the gas sensing layer, a heater layer driving unit for driving the heater layer, and an electrical resistance of the gas sensing layer A gas detection method used in a gas detection device provided with a gas detection unit that detects a change, a heater layer resistance detection unit that detects a change in the heater layer resistance of the heater layer, and
The heater layer driving unit is driven so that the gas sensing layer can be detected by heating the heater layer, the sensor output is detected based on the output from the gas sensing unit, and the heater layer resistance sensing unit detects the heater layer resistance. Reads the resistance value, detects the temperature around the gas sensing layer, reads the heater layer resistance value for the heater layer resistance from the heater layer resistance detector, and changes the temperature of the heater layer resistance value after the heater is turned on. Detecting the humidity around the sensing layer, calculating a correction value based on the calculated temperature and humidity, correcting the sensor output using the correction value, and determining the presence or absence of gas based on the corrected sensor output This is a characteristic gas detection method.

Further, the invention described in claim 18 is
A gas sensing layer whose electrical resistance characteristics change by contact with the detection target gas, a gas sensor having a heater layer for heating the gas sensing layer, a heater layer driving unit for driving the heater layer, and an electrical resistance of the gas sensing layer A gas detection device comprising: a gas detection unit that detects a change; a heater layer resistance detection unit that detects a change in the heater layer resistance of the heater layer; and a temperature detection unit that outputs a detection signal corresponding to the temperature around the gas sensor. A gas detection method used,
The heater layer drive unit is driven to make the gas sensing layer detectable by heating the heater layer, the sensor output is detected based on the output from the gas detection unit, and the surroundings of the gas sensing layer based on the output from the temperature detection unit The heater layer resistance detection unit reads the heater layer resistance value for the heater layer resistance, detects the humidity around the gas sensing layer based on the change in the temperature rise characteristic of the heater layer resistance value after the heater is turned on, A gas detection method characterized by calculating a correction value based on the calculated temperature and humidity, correcting the sensor output using the correction value, and determining the presence or absence of gas based on the corrected sensor output.

  ADVANTAGE OF THE INVENTION According to this invention, the influence by temperature and humidity can be excluded, and the gas detection apparatus and gas detection method which implement | achieve more highly accurate detection can be provided.

It is a block block diagram of the gas detection apparatus of the 1st form for implementing this invention. It is sectional drawing of a gas sensor. It is a characteristic view which shows the heater resistance change of the thin film gas sensor by the external heating in a high temperature furnace. It is a characteristic view which shows the humidity dependence of the time change of heater layer resistance at the time of heater ON at 20 degreeC. It is a characteristic view which shows the humidity dependence of the time change of heater layer resistance at the time of heater ON at 50 degreeC. It is a characteristic view which shows the humidity dependence of the heater layer resistance at 20 ms at 50 ° C./heater layer resistance at 200 ms. It is a characteristic view of the sensor output before ambient temperature and ambient humidity correction. It is a characteristic view of the sensor output after ambient temperature and ambient humidity correction. It is a characteristic view which shows the humidity dependence of the time when the heater resistance value in 20 degreeC reaches a threshold value. It is a characteristic view which shows the humidity dependence (160 degreeC) of the time change of the heater resistance at the time of heater On at 20 degreeC. It is a characteristic view which shows the humidity dependence (160 degreeC) of the time when the heater resistance value in 20 degreeC reaches a threshold value. It is sectional drawing of the gas sensor of the gas detection apparatus of the 2nd form for implementing this invention. It is a block block diagram of the gas detection apparatus of the 3rd form for implementing this invention. It is sectional drawing of a gas sensor. It is sectional drawing of the gas sensor of the gas detection apparatus of the 4th form for implementing this invention. It is a block block diagram of the gas detection apparatus of the 5th form for implementing this invention. It is sectional drawing of a gas sensor. It is sectional drawing of the gas sensor of the gas detection apparatus of the 6th form for implementing this invention. It is a block block diagram of the gas detection apparatus of the 7th form for implementing this invention. It is sectional drawing of a gas sensor. It is sectional drawing of the gas sensor of the gas detection apparatus of the 8th form for implementing this invention. It is a block block diagram of the gas detection apparatus of the 9th form for implementing this invention. It is sectional drawing of a gas sensor. It is sectional drawing of the gas sensor of the gas detection apparatus of the 10th form for implementing this invention.

  Hereinafter, the gas detector 1 of the 1st form of this invention is demonstrated, referring a figure. As shown in FIG. 1, the gas detection device 1 includes a gas sensor 10 and a drive control / signal processing unit 20. The drive control / signal processing unit 20 controls the drive of the gas sensor 10 and receives a detection signal from the gas sensor 10 to detect the presence or absence of gas.

First, details of the gas sensor 10 will be described.
As shown in the cross-sectional view of FIG. 2, the gas sensor 10 has a thermal insulating support of a diaphragm structure on the upper side of the Si substrate 11 by a thermally oxidized SiO ₂ layer 121, a CVD-Si ₃ N ₄ layer 122, and a CVD-SiO ₂ layer 123. Layer 12 is formed.

The heater layer 13 is made of Ni—Cr and is provided on the upper side of the heat insulating support layer 12. The heat insulating support layer 12 and the heater layer 13 are covered with an electric insulating layer 14 made of a sputtered SiO ₂ layer. On the lower side of the pair of sensing electrode layers 152 made of Pt, a bonding layer 151 made of Ta is also formed as an intermediate layer with respect to the electrical insulating layer 14 that is a base oxide film. The pair of sensing electrode layers 152 is provided with a gas sensing layer 153 made of Sb-doped SnO ₂ layer passed.

A part of the electrically insulating layer 14, the pair of sensing electrode layers 152, and the gas sensing layer 153 are covered with a gas selective combustion layer 154 that is a Pd-supported Al ₂ O ₃ sintered material. Instead of the Pd-supported Al ₂ O ₃ sintered material, a Pt-supported Al ₂ O ₃ sintered material or a Pd / Pt alloy-supported Al ₂ O ₃ sintered material may be used.

Then, the manufacturing method of the gas sensor 10 which showed the cross-section in FIG. 2 is demonstrated below. Si ₃ N ₄ and SiO ₂ films are sequentially formed on a silicon wafer 11 having a thermal oxide film on both sides by the plasma DVD method. Next, the heater layer 13 and the SiO ₂ insulating layer 14 are sequentially formed by sputtering. A bonding layer 151, a sensing layer electrode 152, and a gas sensing layer 153 are formed thereon. Film formation is performed by an ordinary sputtering method using an RF magnetron sputtering apparatus. The film formation conditions are the same for the bonding layer (Ta or Ti) 151 and the sensing layer electrode (Pt or Au) 152, Ar gas pressure 1 Pa, substrate temperature 300 ° C., RF power 2 W / cm ² , and film thickness are bonding layer 151 / Sensing layer electrode 152 = 500cm / 2000cm.

Next, a gas sensing layer 153 of SnO ₂ doped with Sb and a gas selective combustion layer 154 made of a sintered material carrying Pd as a catalyst on Al ₂ O ₃ are formed. After the gas selective combustion layer 154 is applied by screen printing, it is baked at 500 ° C. for 1 hour or longer. The size of the gas selective combustion layer 154 is sufficient to cover the gas sensing layer 153. Finally, the silicon was removed from the back surface of the silicon wafer by etching to form a diaphragm structure.

  Next, the drive control / signal processing unit 20 will be described. As shown in FIG. 1, the drive control / signal processing unit 20 includes a central processing unit 21, a heater layer driving unit 22, a gas detection unit 23, a heater layer resistance detection unit 24, a storage unit 25, an alarm display unit 26, and an alarm sound. An output unit 27, an external output unit 28, and a power supply unit 29 are provided.

  The central processing unit 21 is connected to the heater layer driving unit 22, gas detection unit 23, heater layer resistance detection unit 24, storage unit 25, alarm display unit 26, alarm sound output unit 27, and external output unit 28. The central processing unit 21 includes a CPU such as a microcomputer and its peripheral part, and includes a heater layer driving unit 211, a city gas detection unit 212, a CO gas detection unit 213, a temperature detection unit 214, a humidity detection unit 215, and a correction. The functions of the means 216, the determination means 217, the display control means 218, and the output control means 219 are realized by hardware and software, and various controls and signal processing are performed.

  The heater layer driving unit 22 is a circuit unit that converts the voltage supplied from the power supply unit 29 into a heater voltage for accurately detecting gas and drives the heater layer 13 by energization. The heater layer driving unit 22 is controlled variously by the heater layer driving unit 211 in the central processing unit 21. For example, energization is performed in a pulse shape such as a heater-on time of 200 ms and a driving cycle of 60 s. Details of these driving will be described later in the detection process.

  The gas detection unit 23 is connected to the gas detection layer 153 via the detection electrode layer 152 and detects the resistance value of the gas detection layer 153. Based on this resistance value, the city gas detection means 212 and the CO gas detection means 213 in the central processing unit 21 detect the city gas and the CO gas, and send them to the correction means 216 as sensor outputs. The city gas detection means 212 and the CO gas detection means 213 are specific examples of the gas detection means of the present invention, and other means for detecting various gases can be adopted.

  The heater layer resistance detection unit 24 includes means for detecting the heater layer resistance, and transmits a detection signal to the central processing unit 21. The temperature detection means 214 of the central processing unit 21 measures the ambient temperature by a method described later based on the heater layer resistance value. Further, the humidity detecting means 215 of the central processing unit 21 measures the ambient humidity by a method described later based on the heater layer resistance value. When calculating the ambient temperature / humidity, the storage unit 25 is accessed to acquire various data.

  Since the outputs from the gas detection unit 23 and the heater layer resistance detection unit 24 are analog signals, the central processing unit 21 includes an A / D conversion unit that converts these analog signals into digital signals.

  The storage unit 25 is connected to the central processing unit 21 to read and write various data. The storage unit 25 stores history data such as setting values such as threshold values for generating various alarms, correction values based on ambient temperature and humidity, state data when the gas detection device issues an alarm, and the like. .

  In the central processing unit 21, the correction unit 216 calculates a correction value based on the ambient temperature / humidity from the temperature detection unit 214 and the humidity detection unit 215, and the city gas detection unit 212 and the CO gas detection unit 213 sensors. The output is corrected using this correction value, and the corrected sensor output is sent to the determination means 217. The determination means 217 determines the presence or absence of gas based on the corrected sensor output. With such correction, highly accurate gas detection that eliminates the influence of ambient temperature and humidity as much as possible is performed.

  The determination unit 217 of the central processing unit 21 performs control to display an alarm on the alarm display unit 26 via the display control unit 218 when it is determined that gas is detected, and outputs an alarm sound via the output control unit 219. Control is performed to output to the unit 27 and the external output unit 28.

  The alarm display unit 26 includes a display unit such as an LED, a lamp, and an LCD display and its driver, and can display an alarm when an abnormality is detected. In the central processing unit 21, the display control unit 218 that has received the output of the determination unit 217 performs control to display a warning on the detected content that the city gas or CO gas has been detected abnormally.

  The alarm sound output unit 27 includes, for example, a speaker and a driver thereof, and can output an alarm sound or a sound through a speaker or the like. In the central processing unit 21, the output control means 219 that receives the output of the determination means 217 performs control to output a warning sound of the detected content that the city gas or CO gas is detected as abnormal.

  The external output unit 28 is, for example, a contact unit or a communication unit, and can output an alarm to the outside. In the central processing unit 21, the output control means 219, which has received the output of the determination means 217, outputs to the outside the detected contents indicating that the city gas or CO gas has been detected as an abnormal voltage or an output signal of a communication signal. I do.

The power supply unit 29 is not shown in the central processing unit 21, heater layer driving unit 22, gas detection unit 23, heater layer resistance detection unit 24, storage unit 25, alarm display unit 26, alarm sound output unit 27, and external output unit 28. They are connected by power lines and supply power to them. The power supply unit 29 is assumed to be a consumable battery such as a built-in dry battery or a rechargeable battery, but may be composed of a commercial power supply such as AC 100 V and a constant voltage unit.
The overall configuration of the gas detector 1 is as described above.

  Next, the detection operation by the gas detection device 1 will be described. The central processing unit 21 controls the entire gas detection device 1. As shown in FIG. 2, the gas sensor 10 drives the heater by inputting a driving signal from the heater layer driving unit 22 to the heater layer 13 through a conducting wire indicated by a thin line. The gas sensing layer 153 comes into contact with the gas while being heated to a high temperature of 400 ° C. to 500 ° C. by the heater layer 13, and the sensor resistance value that changes in the gas sensing layer 153 is passed through the conductive wire indicated by the thin line. The gas is detected by 23 as a detection signal.

Such a gas detection device 1 particularly detects city gas (combustible gas such as CH ₄ and C ₃ H ₈ ). For example, the heater layer 13 is energized for a certain time of 50 to 500 ms, and the temperature of the heater layer 13, that is, the gas sensing layer 153 is maintained at a high temperature (High 400 to 500 ° C.) for a certain time of 50 to 500 ms. In such a high temperature state, the sensor resistance value of the gas sensing layer 153 is measured by the sensing electrode layer 152 by the gas sensing unit 23, and the presence or absence of CH ₄ , C ₃ H _8, etc. and the combustible gas concentration are detected from the change. . Such detection is performed periodically (for example, every 30 seconds). (High-Off method).

Here, the gas selective combustion layer 154 at a high temperature burns reducing gases such as CO and H _{2 and} other miscellaneous gases, but inactive combustible gases such as CH ₄ and C ₃ H ₈ are gas selective combustion layers. 154 is transparent. Combustible gas reaches the gas sensing layer 153 by diffusing the gas selective combustion layer 154 reacts with the SnO ₂ gas sensitive layer 153, changing the sensor resistance of the SnO _2. By detecting this change in the sensor resistance value, the presence or concentration of a combustible gas such as CH ₄ or C ₃ H ₈ generated when a gas leak occurs in a gas device or the like is detected.

  Further, when detecting incomplete combustion (CO), the temperature of the heater layer 13 is once increased to a high temperature (High 400 to 500 ° C.) for a certain period of 50 to 500 ms, and the gas sensing layer 153 is cleaned. Then, the temperature is lowered to a low temperature (Low about 100 ° C.) and incomplete combustion (CO) is detected. This is known to increase CO sensitivity and gas selectivity (High-Low-Off method).

Also, in the High state, not only cleaning but also detection of flammable gases such as CH ₄ and C ₃ H ₈ is performed, and in combination with detection of incomplete combustion gases such as CO in the Low state, flammable gases and incompleteness with one sensor. It is good also as a gas sensor which can detect both combustion gas.

  As described above, the heater driving method for these gas sensors is (1) driving the heater temperature of the thin film gas sensor to High-Off repeatedly at a predetermined cycle (for example, a cycle of 60 seconds), or (2) setting the heater temperature of the thin film gas sensor to High. Driving that is repeated at a predetermined cycle (for example, 150-second cycle) in -Low-Off is intermittent driving that is repeated at a predetermined cycle (for example, 150-second cycle), thereby reducing power consumption. These methods can be adopted for gas detection.

  Next, correction of the sensor detection value will be described. First, the point that the ambient temperature affects the sensor resistance value and the heater resistance value will be described. The gas sensor 10 having the structure shown in FIG. 2 was placed in a high temperature furnace, the temperature around the gas sensor 10 was raised, and the change in the heater layer resistance value of the heater layer 13 was measured. As shown by the change in the heater layer resistance value in FIG. 3, the heater layer resistance value changes almost linearly with respect to the temperature in the temperature range of 0 to about 500 ° C. Therefore, the heater layer resistance value increases as the ambient temperature increases, and the heater layer resistance value decreases as the ambient temperature decreases. From this tendency, it can be inferred that not only the heater layer resistance value but also the sensor resistance value of the gas sensing layer 153 affects the ambient temperature, in other words, can be used to detect the ambient temperature.

  Next, the point that the ambient humidity affects the sensor resistance value will be described. As described above, the gas sensing layer 153 and the gas selective combustion layer 154 are porous bodies that adsorb moisture, and adsorb moisture that is proportional to the ambient humidity of the installation environment when the heater is off. When the heater is turned on, heat is absorbed when the water adsorbed on the porous body evaporates, and a temperature change caused by humidity occurs due to the latent heat of evaporation. This tendency is presumed that the higher the humidity, the higher the moisture content and the greater the latent heat of vaporization.

  The influence of temperature change due to humidity will be described. The gas sensor 10 having the structure shown in FIG. 2 is energized while changing the humidity. FIG. 4 shows the time variation of the heater resistance when the heater is turned on when energization is performed at an ambient temperature of 20 ° C. with a driving period of 60 s and a heater on time of 200 ms. In the rising period of about 5 ms to 80 ms, the heater layer resistance decreases as the humidity increases from 50% to 90% at the same time (for example, at 40 ms).

  FIG. 5 shows the time variation of the heater resistance when the heater is turned on when energized at an ambient temperature of 50 ° C. with a driving period of 60 s and a heater on time of 200 ms. Again, the heater layer resistance decreases as the humidity increases from 50% to 90% at the same time (for example, at 40 ms) in the rising period of about 5 ms to 80 ms.

As shown in FIGS. 4 and 5, the change in the heater resistance with time when the heater is on changes in the temperature rise characteristic of about 5 ms to 80 ms as the ambient humidity increases.
As described above, the temperature is lowered by latent heat of vaporization for evaporating the moisture adsorbed in the pores of the selective catalyst layer and the gas sensing layer which are porous or columnar structures. And it is presumed that the more moisture, that is, the higher the humidity, the greater the latent heat of vaporization and the lower the temperature and the lower the heater layer resistance. The same applies to the sensor resistance value of the gas sensing layer 153.
Thus, the heater layer resistance value of the heater layer 13 and the sensor resistance value of the gas sensing layer 153 are affected by the ambient temperature and ambient humidity.

  The influence of the ambient temperature and ambient humidity affects the sensor output as shown in FIG. Therefore, a correction value for a certain ambient temperature and a certain ambient humidity is calculated in advance, and the correction value is registered by associating the ambient temperature, the ambient humidity and the correction value. A large number of such registrations are performed by combining an assumed ambient temperature and an assumed ambient humidity. Then, an optimum correction value is read from the detected current ambient temperature and ambient humidity, and the sensor output is corrected. In this way, accurate detection that is not affected by the ambient temperature and ambient humidity is possible.

  Next, detection of the ambient temperature using the heater layer resistance value by the heater layer resistance detector 24 and the temperature detector 214 will be described. The temperature detection is the ambient temperature when the heater is off. When the heater is on, ambient humidity is detected as will be described later.

  As shown in FIG. 2, the heater layer resistance detection unit 24 measures the heater layer resistance value from the heater layer 13 through a conductive wire indicated by a thin line, and includes a shunt resistance. The shunt resistance has a known resistance value and is connected in series with the heater layer 13. Furthermore, the circuit configuration is such that the voltage across the heater layer 13 and the voltage across the shunt resistor can be measured.

  When measuring the heater layer resistance when the heater is turned off, a predetermined voltage is applied to the heater layer 13 and the shunt resistor, the voltage across the heater layer 13 is measured, and the voltage value across the shunt resistor arranged in series is also measured. These voltage values at both ends are sent to the temperature detecting means 214. Then, the temperature detection means 214 calculates the current from the voltage value across the shunt resistor arranged in series and the known shunt resistance value arranged in series. Then, the heater layer resistance value is calculated from this current and the read voltage across the heater layer 13. Then, using the measured heater layer resistance value of the heater layer 13, the temperature detection unit 214 calculates the temperature T of the heater layer 13 when the heater is off from the following equation.

In this way, the ambient temperature T approximately equal to the heater layer temperature T is calculated.
Here, the value of R ₀ is obtained in advance by measurement. Further, the value of α is a value determined for each sensor. However, since there is little variation for each wafer on which a thin film sensor is formed, the same value may be given to a thin film sensor that can be taken from one wafer. Alternatively, when flowing a plurality of wafers in one lot, the same value may be given to the thin film sensors in the same lot.

  Subsequently, detection of ambient humidity using the heater layer resistance value will be described. 4 and 5, the change in the temperature rise characteristic observed during the rise period of about 5 ms to 80 ms, which is recognized as the ambient temperature increases, is that the power consumed in the heater layer is consumed for latent heat of vaporization. Appears as a change in properties. Humidity can be estimated according to how the temperature rise characteristic behaves, that is, the heater layer resistance value. Therefore, humidity detection is a feature of the present invention, but ambient humidity is measured with reference to a resistance change that is affected by latent heat of vaporization when the heater is on, not when the heater is off.

  Next, humidity detection by the heater layer resistance detection unit 24 and the humidity detection means 215 will be described. The heater layer resistance detector 24 measures the heater layer resistance value when the heater is turned on by the method described above. This heater layer resistance value is sent to the humidity detecting means 215. The humidity detecting means 215 estimates the ambient humidity from the behavior of the resistance value of the heater layer (change in the heater temperature rise characteristic) from when the heater is on to when it is stable.

  An example is shown below. It is assumed that the ambient temperature is 50 ° C. and follows the characteristics shown in FIG. In the sample used this time, the heater layer resistance value at 20 ms selected from about 5 ms to 80 ms at which the water adsorbed on the porous body does not evaporate is set as the first heater layer resistance value, and the heater is heated sufficiently. The heater layer resistance value at 200 ms selected from about 80 ms to 200 ms when the water adsorbed on the porous body is evaporated is defined as the second heater layer resistance value. The ratio with the heater layer resistance value is calculated in advance for each humidity, and is registered in the storage unit 25 as ambient humidity dependency. FIG. 6 shows the ambient humidity dependency. Since the ambient humidity dependency differs depending on the temperature, it is registered for each temperature. For example, if the ambient temperature is 20 ° C., the ambient humidity dependency generated in advance based on the characteristics shown in FIG. 4 is adopted, and if the temperature is 50 ° C., the characteristics shown in FIG. The ambient humidity dependency generated in advance based on the above is adopted. This is determined by the previously determined ambient temperature. In this embodiment, the ambient temperature is 50 ° C., and description will be made with reference to the ambient humidity dependence for 50 ° C.

  The ratio of the vertical axis of the ambient humidity dependence adopted, that is, when the moisture is not evaporated completely (heated for 20 ms in this embodiment) when heated for a predetermined period from the start of heater on but adsorbed to the porous gas sensing layer. The first heater layer resistance value is detected, and then the second heater layer resistance value when the water is sufficiently heated from the start of the heater on and the moisture adsorbed on the porous gas sensing layer evaporates (at 200 ms in this embodiment). Is detected. And the humidity detection means 215 calculates | requires ratio of these 1st heater layer resistance values and 2nd heater layer resistance values, and the ambient humidity dependence (ambient humidity corresponding to ratio) registered into the memory | storage part 25 is obtained. Access the database and read the ambient humidity corresponding to the calculated ratio. This is to estimate the ambient humidity by calculating the humidity corresponding to the characteristics shown in FIG. In this way, the ambient humidity is calculated.

  The correction means 216 of the central processing unit 21 corrects the detected gas value according to the ambient temperature and ambient humidity of the gas sensing unit 15 based on the ambient humidity and ambient temperature. In this case, correction values corresponding to a certain ambient temperature and a certain ambient humidity are calculated in advance, and correction values corresponding to all the assumed ambient temperatures and all the ambient humidity (for example, an ambient temperature of 20 ° C. and an ambient humidity of 65). % Correction value a, ambient temperature 35 ° C. and ambient humidity 90% correction value b, ambient temperature 50 ° C. and ambient humidity 65% correction value c, and ambient temperature 50 ° C. and ambient humidity 90% correction value d) in advance. Registered in the storage unit 25. Then, a correction value corresponding to the measured ambient temperature / humidity is read from the storage unit 25, and the sensor output is corrected based on the correction value. For example, the correction value may be multiplied as a coefficient, or may be added. The correction principle is as follows.

  An example improved by correction will be described with reference to FIGS. Before the correction, as shown in FIG. 7, the sensor output changed due to the ambient temperature / humidity, but after the correction, as shown in FIG. 8, the sensor output absorbs the change due to the ambient temperature / ambient humidity. Yes.

The determination unit 217 of the central processing unit 21 determines whether the corrected sensor output from the correction unit 216 exceeds the alarm threshold value. When the corrected sensor output exceeds the alarm threshold value, the determination unit 217 notifies the display control unit 218 and the output control unit 219 that gas has been detected exceeding the threshold value. When the display control means 218 controls the alarm display unit 26 to display an alarm, the alarm display unit 26 displays the alarm. When the output control means 219 controls the alarm sound output unit 27 to output an alarm sound, the alarm sound output unit 27 outputs an alarm sound, and the external output unit 28 outputs that the alarm has been notified to the outside. When controlled in this manner, the external output unit 28 outputs an alarm to the outside. In this way, gas detection is performed.
The gas detector 1 of this embodiment is such a thing.

  According to the present invention described above, the ambient humidity can be detected from the temperature rise characteristic of the heater. Specifically, it has been found that the influence of latent heat of vaporization when moisture adsorbed on the gas sensing layer 153 and the gas selective combustion layer 154 evaporates when the heater is turned on is reflected in the temperature rise characteristics of the heater and can be used for humidity detection. Based on the ambient temperature and humidity thus obtained, the detected gas value is corrected according to the ambient temperature and humidity of the gas sensing layer. Therefore, highly accurate gas detection that eliminates the influence of humidity becomes possible.

  Next, another embodiment will be described. In this embodiment, the structure is the same as that of the previous embodiment, but only the humidity detection method is different. Hereinafter, the humidity detection will be described, and other configurations, temperature detection methods, and the like will be the same, and redundant description will be omitted.

  In this embodiment, as a change in the heater temperature rise characteristic when the heater is turned on, the time until the measured heater resistance value exceeds a specific heater resistance value that is a threshold is measured, and the ambient humidity is estimated based on this time To do. This detection principle will be described with reference to the drawings. FIG. 9 plots the time when the heater temperature is raised by turning on the heater at a certain humidity and the heater resistance exceeds 95Ω as a threshold value. The ambient temperature at this time is 20 ° C. According to this characteristic, it can be seen that as the ambient humidity increases, the time exceeding 95Ω increases approximately proportionally. In other words, if the time exceeding 95Ω is known, the ambient humidity can be estimated.

  For example, if the time over 95Ω is 15 ms, the ambient humidity is estimated to be around 55%. As described above, a plurality of times exceeding the sensor resistance value of 95Ω with respect to a certain ambient humidity are registered in the storage unit 25. Since the ambient humidity dependency differs depending on the temperature, it is registered for each temperature. For example, if the ambient temperature is 20 ° C., the ambient humidity dependency generated in advance based on the characteristics shown in FIG. 9 is adopted. If the temperature is different, other ambient humidity dependence registered for each temperature such as 25 ° C. and 30 ° C. is used.

  First, temperature detection by the heater layer resistance detector 24 and the temperature detector 214 will be described. The heater layer resistance detection unit 24 measures the heater layer resistance value when the heater is turned off by the method described above. The temperature detector 214 calculates the ambient temperature using the heater layer resistance value when the heater is off. The optimum ambient humidity-time characteristic is adopted depending on the ambient temperature. In this embodiment, it is assumed that the ambient temperature is 20 ° C. and the ambient humidity-time characteristic for 20 ° C. as shown in FIG. 9 is selected.

  Next, humidity detection by the heater layer resistance detection unit 24 and the humidity detection means 215 will be described. The heater layer resistance detector 24 measures the heater layer resistance value when the heater is turned on by the method described above. The heater layer resistance value when the heater is on is sequentially sent to the humidity detecting means 215. Then, the humidity detecting means 215 detects that the heater layer resistance value that rises as it is heated for a predetermined period from the start of heater on has reached a predetermined threshold value (95Ω). The humidity detecting means 215 stores the arrival time, accesses the ambient humidity-time characteristic database registered in the storage unit 25, and selects the ambient humidity corresponding to the measured time, thereby estimating the ambient humidity. .

  The heater temperature rise characteristic may be a heater temperature significantly lower than the sensor driving temperature at the time of gas detection. For example, while the heater temperature is 500 ° C. in the above description, the heater temperature is 160 ° C. here. FIG. 10 shows the time change of the heater temperature rising resistance when the heater is turned on. In FIG. 10, the ambient temperature is 20 ° C., and the same conditions as described above are used. As is apparent from FIG. 10, the time required to reach the heater resistance threshold value of 95Ω is lengthened.

  In such a heater temperature rise characteristic, in particular, since the heater temperature is low, the time for evaporating the adsorbed moisture is lengthened, and in the heater temperature rise characteristic, the time until the heater resistance threshold is exceeded is lengthened. Therefore, it is possible to estimate the humidity more accurately by reducing the time resolution. FIG. 11 also shows that the time when the heater resistance exceeds 95Ω as the threshold value is plotted, the time exceeding 95Ω becomes longer as the ambient humidity increases. Thus, the humidity can be estimated more accurately by calculating the humidity by lowering the heater temperature significantly below the sensor temperature.

Next, another embodiment will be described.
In this embodiment, the gas sensor of FIG. 1 is particularly improved, and a gas sensor 30 as shown in FIG. 12 is employed instead of the gas sensor 10 of FIG. Therefore, the description other than the gas sensor 30 is the same as each configuration of the previous gas detection device 1, and a duplicate description is omitted, and only the gas sensor 30 is described. FIG. 12 is a cross-sectional view of a gas sensor of a gas detector according to a second embodiment for carrying out the present invention.

  In general, in an environment where the gas detection device 1 is used, other miscellaneous gases that adversely affect the gas sensor coexist in addition to the detection target gas. The miscellaneous gas is a gas type such as combustible gas, oxygen, nitrogen, carbon dioxide gas, and water vapor that is not detected. Some of these gases become interference gas for the gas sensor (gas that induces false detection that causes the gas sensor to change its resistance and behave as if the gas to be detected exists), and may cause false detection.

  In order to eliminate the influence of the interference gas and accurately detect the presence and concentration of the detection target gas, the interference gas is removed by the gas selective combustion layer 154, and the detection target gas is detected at a sufficiently high temperature. It is necessary to energize for a long time. However, there is a problem that such heating hinders low power consumption.

  Therefore, in order to prevent the influence of the interference gas, the gas sensor 30 covers the gas sensing layer 153 and the gas selective combustion layer 154 with a filter case 31 and a filter 32 at the gas inlet of the filter case 31 as shown in FIG. Provided. The filter 32 includes, for example, an activated carbon adsorption layer, and adsorbs and removes interference gas.

  Since this activated carbon adsorption layer also adsorbs and desorbs moisture in the air, the humidity response of the detection space 311 in the filter case is delayed with respect to the humidity change outside the filter case 31 (in the environment), but the heater that detects humidity The layer 13 is provided in the filter case 31, and there is no problem. As a result, the correction described above is performed after greatly eliminating the influence of humidity, so that a more accurate correction is possible. Such a gas detection device 1 may be used.

  Next, another embodiment will be described with reference to FIG. As shown in FIG. 13, the gas detection device 2 includes a gas sensor 10 and a drive control / signal processing unit 40. The drive control / signal processing unit 40 controls the drive of the gas sensor 10 and receives a detection signal from the gas sensor 10 to detect the presence or absence of gas. The gas detector 1 of FIG. 1 described above performs temperature detection and humidity detection using the heater layer resistance value for the heater layer 13. In this embodiment, as shown in FIG. 14, a temperature detection unit 41 that performs temperature detection is employed, and a heater layer resistance detection unit 24 is employed for humidity detection.

  The gas sensor 10 shown in FIG. 14 has the same configuration as that described above with reference to FIG. 2, and is given the same reference numerals and redundant description is omitted. As shown in FIG. 13, the drive control / signal processing unit 40 includes a central processing unit 21, a heater layer driving unit 22, a gas detection unit 23, a heater layer resistance detection unit 24, a storage unit 25, an alarm display unit 26, and an alarm sound. An output unit 27, an external output unit 28, a power supply unit 29, and a temperature detection unit 41 are provided. Compared with the drive control / signal processing unit 20 described above with reference to FIG. 1, only the temperature detection unit 41 is added. The drive control / signal processing unit 40 is different only in the ambient temperature detection method by the temperature detection unit 41, and this point will be described mainly. Other configurations and ambient humidity detection are shown in FIG. The same numbers as those of the components of the gas detection device 1 are assigned and redundant description is omitted.

  The temperature detector 41 is, for example, a thermistor, and changes the resistance value according to the temperature. The temperature detection unit 41 has the shunt resistance described above so that the resistance value of the thermistor of the temperature detection unit 41 can be detected. The temperature detection means 214 of the central processing unit 21 measures the ambient temperature by the method using Equation 2 based on the resistance value of the thermistor of the temperature detection unit 41.

  Further, the humidity detection means 215 of the central processing unit 21 measures the ambient humidity by the above method based on the heater layer resistance value obtained via the heater layer resistance detection unit 24. The heater layer driving unit 211 of the central processing unit 21 controls the heater layer driving unit 22 to perform driving when detecting ambient humidity as described above. Then, the humidity detection is performed based on a change in the heater layer resistance value of the heater layer 13 when the heater is turned on, which is obtained via the heater layer resistance detection unit 24, when the temperature rises (ratio in FIG. 6 and time in FIGS. 9 and 11). Means 215 detects ambient humidity. Hereinafter, the correction / determination as described above is performed using the ambient temperature and the ambient humidity.

  According to the present invention as described above, the detection of the ambient temperature and the detection of the ambient humidity can be performed independently, and thus there is an advantage that the installation location and the detection time can be freely set.

Next, another embodiment will be described. This embodiment employs a gas sensor 30 as shown in FIG. 15 instead of the gas sensor 10 of FIG. 14 in the gas detection device 2 of FIG. The gas sensor 30 shown in FIG. 15 is obtained by adding a filter case 31 and a filter 32 to the configuration of the gas sensor 10 of FIG. These configurations are the same as those of the gas sensor 30 described above with reference to FIG. 12, but it is particularly preferable that the temperature detection unit 41 is disposed in the filter case 31 to detect the ambient temperature in the filter case 31. Note that temperature detection is possible even if the temperature detector 41 is disposed outside the filter case 31. The ambient temperature / ambient humidity detection method, gas detection method, correction method, and the like are the same as those described above, and redundant descriptions are omitted.
In such a gas detection device 2, the correction described above is performed after greatly eliminating the influence of humidity, so that more accurate correction is possible. Such a gas detection device 2 may be used.

  Next, another embodiment will be described with reference to FIG. The gas detection device 3 includes a gas sensor 50 and a drive control / signal processing unit 60. The drive control / signal processing unit 60 controls the driving of the gas sensor 50 as shown in FIG. 17 and receives a detection signal from the gas sensor 50 to detect the presence or absence of gas. The gas detector 1 of FIG. 1 described above performs temperature detection and humidity detection using the heater layer resistance value for the heater layer 13. In this embodiment, a detection unit 51 specialized for detection is mounted on the gas sensor 50, and the detection unit 51 performs temperature detection and humidity detection.

  As shown in FIG. 17, the gas sensor 50 includes a Si substrate 11, a thermal insulation support layer 12, a heater layer 13, an electrical insulation layer 14, a gas sensing unit 15, and a detection unit 51. Among these, the Si substrate 11, the heat insulating support layer 12, the heater layer 13, the electric insulating layer 14, and the gas sensing unit 15 are the same as those described above, and are given the same reference numerals and redundant description is omitted.

The detection unit 51 includes a detection heater layer 511 and a detection porous layer 512.
The detection heater layer 511 is made of Ni—Cr and is provided on the upper side of the heat insulating support layer 12. The detection heater layer 511 is covered with an electrical insulating layer 14 made of a sputtered SiO ₂ layer. The detection porous layer 512 is made of the same material as the gas selective combustion layer 154, such as a Pd-supported Al ₂ O ₃ sintered material, a Pt-supported Al ₂ O ₃ sintered material, or a Pd / Pt alloy-supported Al ₂ O ₃ sintered material. Can be adopted. The detection heater layer 511 and the detection porous layer 512 can be simultaneously formed using the same material when the heater layer 13 and the gas selective combustion layer 154 are formed.

  The position of the detection unit 51 (detection heater layer 511, detection porous layer 512) is in the vicinity of the gas sensing unit 15 and within a range on the diaphragm. This is because if it is disposed outside the range on the diaphragm, heat escapes to the Si substrate 11, the temperature rise becomes gradual, and the temperature cannot be raised. As described above, by disposing on the diaphragm, it becomes difficult for heat to escape, and low power consumption can be realized.

  Next, the drive control / signal processing unit 60 will be described. As shown in FIG. 16, the drive control / signal processing unit 60 includes a heater layer driving unit 22, a gas detection unit 23, a storage unit 25, an alarm display unit 26, an alarm sound output unit 27, an external output unit 28, and a power supply unit 29. A central processing unit 61, a detection heater layer driving unit 62, and a detection heater layer resistance detection unit 63. The central processing unit 61, the detection heater layer driving unit 62, and the detection heater layer resistance detection unit 63 will be described mainly, and the other components will be assigned the same reference numerals and redundant description of the gas detection method and the like will be omitted. To do.

  The central processing unit 61 includes heater layer driving means 211, city gas detection means 212, CO gas detection means 213, temperature detection means 214, humidity detection means 215, correction means 216, determination means 217, display control means 218, output control means. In addition to 219, a heater layer driving means 611 for detection is provided.

The detection heater layer driving unit 62 converts the voltage supplied from the power supply unit 29 into a heater voltage for accurately detecting the ambient temperature and ambient humidity, and drives the detection heater layer 511 by energization. Part.
The detection heater layer resistance detection unit 63 includes means for detecting the heater layer resistance of the detection heater layer 511, and transmits a detection signal to the central processing unit 61. The temperature detection means 214 of the central processing unit 61 measures the ambient temperature by the method using the above equation 2 based on the heater layer resistance value of the detection heater layer 511. Further, the humidity detecting means 215 of the central processing unit 61 measures the ambient humidity by the above method based on the heater layer resistance value of the detection heater layer 511.

  The detection heater layer driving unit 611 of the central processing unit 61 controls the detection heater layer driving unit 62 and performs the driving at the time of detecting the ambient temperature and ambient humidity as described above. Then, based on the heater layer resistance value of the detection heater layer 511 obtained when the heater is turned off, obtained via the detection heater layer resistance detection unit 63, the temperature detection unit 214 of the central processing unit 61 detects the ambient temperature. Then, the heater layer resistance value obtained through the detection heater layer resistance detection unit 63 and including the influence of moisture adsorbed on the detection porous layer 512 when the heater is turned on, the heater layer resistance of the detection heater layer 511 Based on the change of the value when the temperature rises (ratio in FIG. 6 and time in FIGS. 9 and 11), the humidity detecting means 215 detects the ambient humidity. Hereinafter, the correction / determination as described above is performed using the ambient temperature and the ambient humidity.

  According to the present invention, since the ambient temperature and ambient humidity can be detected independently, there is an advantage that the installation location and the detection time can be freely set.

  Next, another embodiment will be described. In this embodiment, a gas sensor 70 as shown in FIG. 18 is adopted in the gas detection device 3 of FIG. 16 instead of the gas sensor 50 as shown in FIG. A gas sensor 70 shown in FIG. 18 is obtained by adding a filter case 31 and a filter 32 to the configuration of the gas sensor 50 of FIG. The detection unit 51 is also located in the detection space 311 of the filter case 31. The configurations of the filter case 31 and the filter 32 are the same as those described above, and the detection method of the ambient temperature / humidity, the detection method of gas, the correction method, and the like are the same as those of the previous description, and overlapping descriptions are given. Is omitted.

  In such a gas detection device 3, since the correction described above is performed after greatly eliminating the influence of humidity, more accurate correction can be performed. Further, since the ambient temperature and ambient humidity can be detected independently, there is an advantage that the installation location and the detection time can be set freely. Such a gas detection device 3 may be used.

  Next, another embodiment will be described with reference to FIG. The gas detection device 4 includes a gas sensor 50 and a drive control / signal processing unit 80. The drive control / signal processing unit 80 controls the driving of the gas sensor 50 as shown in FIG. 20 and receives a detection signal from the gas sensor 50 to detect the presence or absence of gas. In this embodiment, the temperature detection unit 41 is used for temperature detection, and the temperature detection unit 41 performs temperature detection. The humidity detection uses the detection heater layer resistance detector 63 described above.

  The gas sensor 50 has the same configuration as that described with reference to FIG. As shown in FIG. 19, the drive control / signal processing unit 80 includes a central processing unit 61, a heater layer driving unit 22, a gas detection unit 23, a storage unit 25, an alarm display unit 26, an alarm sound output unit 27, and an external output unit. 28, a power supply unit 29, a detection heater layer driving unit 62, a detection heater layer resistance detection unit 63, and a temperature detection unit 41. Compared with the drive control / signal processing unit 60 described above with reference to FIG. 16, only the temperature detection unit 41 is added. The drive control / signal processing unit 80 differs only in the ambient temperature detection method by the temperature detection unit 41, and this point will be described mainly. Other configurations and ambient humidity detection are shown in FIG. The same reference numerals as those of the gas detection device 3 are assigned, and redundant description is omitted.

  The temperature detector 41 is, for example, a thermistor, and changes the resistance value according to the temperature. The temperature detector 41 has the shunt resistor described above, and can detect the resistance value of the thermistor. The temperature detecting means 214 of the central processing unit 61 measures the ambient temperature by the above method based on the resistance value of the thermistor. Further, the humidity detection means 215 of the central processing unit 61 measures the ambient humidity by the above method based on the detection heater layer resistance value obtained via the detection heater layer resistance detection unit 63.

  The detection heater layer driving unit 611 of the central processing unit 61 controls the detection heater layer driving unit 62 to perform driving when detecting ambient humidity as described above. Then, the change in the heater layer resistance value of the detection heater layer 511 when the heater is turned on, which is obtained via the detection heater layer resistance detection unit 63, at the time of temperature rise (ratio in FIG. 6 and time in FIGS. 9 and 11). Based on this, the humidity detecting means 215 detects the ambient humidity. Hereinafter, the correction / determination as described above is performed using the ambient temperature and the ambient humidity.

  According to the present invention, since the detection of the ambient temperature and the detection of the ambient humidity can be performed independently while being separated from the heater layer driving, the installation location and the detection time can be freely set. There is an advantage.

  Next, another embodiment will be described. This embodiment employs a gas sensor 70 as shown in FIG. 21 in place of the gas sensor 50 in the gas detection device 4 of FIG. The gas sensor 70 shown in FIG. 21 is obtained by adding a filter case 31 and a filter 32 to the configuration of the gas sensor 50 of FIG. These configurations are the same as those described above, and the ambient temperature / humidity detection method, gas detection method, correction method, and the like are the same as those described above, and redundant descriptions are omitted.

  In such a gas detection device 4, since the correction described above is performed after greatly eliminating the influence of humidity, more accurate correction can be performed. In particular, the detection of the ambient temperature and the detection of the ambient humidity can be performed independently while being separated from the heater layer drive, so that there is an advantage that the installation location and the detection time can be freely set. Such a gas detection device 4 may be used.

  Next, another embodiment will be described with reference to FIG. As shown in FIG. 22, the gas detection device 5 includes a gas sensor 90 and a drive control / signal processing unit 100. The drive control / signal processing unit 100 controls the drive of the gas sensor 90 and receives a detection signal from the gas sensor 90 to detect the presence or absence of gas. In this embodiment, a temperature detection unit 41 that performs temperature detection and a humidity detection unit 102 that performs humidity detection are employed.

  A gas sensor 90 shown in FIG. 23 includes a Si substrate 11, a heat insulating support layer 12, a heater layer 13, an electric insulating layer 14, and a gas sensing unit 15. The Si substrate 11, the heat insulating support layer 12, the heater layer 13, and the electrical insulating layer 14 are the same as those described above, and are given the same reference numerals and redundant description is omitted.

  As shown in FIG. 22, the drive control / signal processing unit 100 includes a central processing unit 100, a heater layer driving unit 22, a gas detection unit 23, a storage unit 25, an alarm display unit 26, an alarm sound output unit 27, and an external output unit. 28, a power supply unit 29, a temperature detection unit 41, and a humidity detection unit 102. Regarding the drive control / signal processing unit 100, the ambient temperature detection method by the temperature detection unit 41 and the ambient temperature detection method by the humidity detection unit 102 are different. Are given the same numbers as the components of the gas detection device 1 of FIG.

  The temperature detector 41 is, for example, a thermistor, and changes the resistance value according to the temperature. The temperature detector 41 has the shunt resistor described above, and can detect the resistance value of the thermistor. The temperature detection unit 214 of the central processing unit 101 measures the ambient temperature by the method using the above equation 2 based on the resistance value of the thermistor of the temperature detection unit 41.

  The humidity detection unit 102 changes the resistance value in proportion to the amount of moisture absorbed by the moisture sensitive body according to the humidity, for example. The humidity detection means 215 of the central processing unit 101 measures the ambient humidity by the above-described method based on the resistance value of the humidity sensing body of the humidity detection unit 102. Hereinafter, the correction / determination as described above is performed using the ambient temperature and the ambient humidity.

  According to the present invention as described above, the detection of the ambient temperature and the detection of the ambient humidity can be performed independently, and thus there is an advantage that the installation location and the detection time can be freely set.

  Next, another embodiment will be described. This embodiment employs a gas sensor 110 as shown in FIG. 24 in place of the gas sensor 90 of FIG. 23 in the gas detection device 5 of FIG. The gas sensor 110 shown in FIG. 24 is obtained by adding a filter case 31 and a filter 32 to the configuration of the gas sensor 90 of FIG. These configurations are the same as those of the gas sensor 90 described above with reference to FIG. 23. In particular, the temperature detection unit 41 and the humidity detection unit 102 are arranged in the filter case 31, and the ambient temperature and ambient humidity in the filter case 31 are as follows. Is preferably detected. Note that temperature detection / humidity detection is possible even if the temperature detection unit 41 and the humidity detection unit 102 are arranged outside the filter case 31, and such a configuration may be adopted. Further, the gas detection method, the correction method using the ambient temperature / humidity, and the like are the same as those described above, and redundant descriptions are omitted.

  In such a gas detection device 5, since the correction described above is performed after greatly eliminating the influence of humidity, more accurate correction is possible. Such a gas detection device may be used.

  The gas detection device of the present invention has been described above with reference to the drawings. In the above-described embodiments, the gas selective combustion layer 154 is described as being configured to include the gas selective combustion layer 154. However, the gas sensing layer 15 without the gas selective combustion layer 154 may be used. Also in this case, gas detection is possible if the porous gas sensing layer 153 is provided. A configuration without such a gas selective combustion layer 154 may be adopted.

  As described above, according to the gas detection device described above, the influence of the ambient temperature and the ambient humidity can be eliminated, and accurate gas detection is realized.

  The gas detection device of the present invention is particularly applicable to uses such as a gas leak alarm.

1, 2, 3, 4, 5: Gas detectors 10, 30, 50, 70, 90, 110: Gas sensor 11: Si substrate 12: Thermal insulating support layer 121: Thermal oxide SiO ₂ layer 122: CVD-Si ₃ N ₄ layer 123: CVD-SiO ₂ layer 13: heater layer 14: electrical insulation layer 15: gas detection unit 151: bonding layer 152: sensing electrode layer 153: gas sensing layer 154: gas selective combustion layer 20, 40, 60, 80 , 100: Drive control / signal processing unit 21, 61, 101: Central processing unit 211: Heater layer driving unit 212: City gas detection unit 213: CO gas detection unit 214: Temperature detection unit 215: Humidity detection unit 216: Correction unit 217: Determination unit 218: Display control unit 219: Output control unit 611: Detection heater layer driving unit 22: Heater layer driving unit 23: Gas detection unit 24: Heater layer resistance detection 25: storage unit 26: alarm display unit 27: alarm sound output unit 28: external output unit 29: power supply unit 31: filter case 311: detection space 32: filter 41: temperature detection unit 51: detection unit 511: heater layer for detection 512: Detection porous layer 52: Detection heater layer driving unit 53: Detection heater layer resistance detection unit 102: Humidity detection unit

Claims (18)

A gas sensor having a gas sensing layer whose electrical resistance is changed by contact with a gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A temperature detection unit that outputs a detection signal according to the temperature around the gas sensor;
A humidity detector that outputs a detection signal according to the humidity around the gas sensor;
A central processing unit to which a heater layer driving unit, a gas detection unit, a temperature detection unit and a humidity detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for detecting the temperature around the gas sensing layer based on the output from the temperature detection unit;
Humidity detection means for detecting the humidity around the gas sensing layer based on the output from the humidity detector,
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
Determination means for determining the presence or absence of gas from the corrected sensor output;
A gas detection device comprising: A gas sensor having a gas sensing layer whose electrical resistance is changed by contact with a gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A heater layer resistance detector for detecting a change in the heater layer resistance of the heater layer;
A central processing unit to which a heater layer driving unit, a gas detection unit and a heater layer resistance detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for reading the heater layer resistance value for the heater layer resistance from the heater layer resistance detector and detecting the temperature around the gas sensing layer;
A humidity detecting means for reading the heater layer resistance value for the heater layer resistance from the heater layer resistance detecting unit and detecting the humidity around the gas sensing layer based on a change in the temperature rise characteristic of the heater layer resistance value after the heater is turned on;
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
Determination means for determining the presence or absence of gas from the corrected sensor output;
A gas detection device comprising: The gas detection device according to claim 2,
The temperature detecting means is a means for reading the heater layer resistance value and calculating the ambient temperature from the heater layer resistance value, the temperature coefficient of the heater layer resistance, and the heater layer resistance value at the reference temperature. Detection device. A gas sensor having a gas sensing layer whose electrical resistance is changed by contact with a gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A heater layer resistance detector for detecting a change in the heater layer resistance of the heater layer;
A temperature detection unit that outputs a detection signal according to the temperature around the gas sensor;
A central processing unit to which a heater layer driving unit, a gas detection unit, a heater layer resistance detection unit and a temperature detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for detecting the temperature around the gas sensing layer based on the output from the temperature detection unit;
A humidity detecting means for reading the heater layer resistance value for the heater layer resistance from the heater layer resistance detecting unit and detecting the humidity around the gas sensing layer based on a change in the temperature rise characteristic of the heater layer resistance value after the heater is turned on;
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
A determination means for determining the presence or absence of a gas based on the corrected gas concentration;
A gas detection device comprising: In the gas detection device according to any one of claims 2 to 4,
The humidity detection means evaporates the moisture adsorbed on the gas sensing layer, which is heated for a predetermined period from the start of the heater on, as a change in the temperature rise characteristic of the heater layer resistance from the start of the heater on for the heater layer resistance. The first heater layer resistance value when the threshold was not reached and the second heater layer resistance value when the moisture adsorbed on the gas sensing layer that was sufficiently heated from the start of the heater on and evaporated were used. A gas detection device that is a means for calculating a ratio and calculating a humidity corresponding to the ratio. In the gas detection device according to any one of claims 2 to 4,
The humidity detection means is a heater in which moisture adsorbed on the gas sensing layer, which is a porous body, is sufficiently heated from the start of the heater on as a change in the temperature rise characteristic of the heater layer resistance value from the start of the heater on for the heater layer resistance. A gas detection device characterized in that it is means for calculating a time to reach a layer resistance value and calculating a humidity corresponding to the time. In the gas detection device according to any one of claims 1 to 6,
A filter cover for partitioning a space including at least the gas sensing layer from the outside;
A filter that is provided in the filter cover and that adsorbs a predetermined gas of the detection target gas and introduces the gas into the filter cover;
A gas detection device comprising: A gas sensor having a gas sensing layer whose electrical resistance characteristics change by contact with the gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A porous layer for detection;
A detection heater layer for heating the detection porous layer;
A detection heater layer driving section for driving the detection heater layer;
A detection heater layer resistance detector for detecting a change in the heater layer resistance of the detection heater layer;
A central processing unit to which a heater layer drive unit, a gas detection unit, a detection heater layer drive unit and a detection heater layer resistance detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
A detection heater layer driving means for driving the detection heater layer driving section so that the detection heater layer heats the detection porous layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for reading the heater layer resistance value for the detection heater layer resistance from the detection heater layer resistance detection unit and detecting the temperature around the gas detection layer;
The heater layer resistance value for the detection heater layer resistance is read from the detection heater layer resistance detection unit, and based on the change in the temperature rise characteristic of the heater layer resistance value for the detection heater layer resistance after the heater is turned on, Humidity detection means for detecting humidity;
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
A determination means for determining the presence or absence of a gas based on the corrected gas concentration;
A gas detection device comprising: The gas detection device according to claim 8,
The temperature detecting means is a means for reading the heater layer resistance value and calculating the ambient temperature from the heater layer resistance value, the temperature coefficient of the heater layer resistance, and the heater layer resistance value at the reference temperature. Detection device. A gas sensor having a gas sensing layer whose electrical resistance characteristics change by contact with the gas to be detected, and a heater layer for heating the gas sensing layer;
A heater layer driving unit for driving the heater layer;
A gas detector that detects changes in the electrical resistance of the gas sensing layer;
A porous layer for detection;
A detection heater layer for heating the detection porous layer;
A detection heater layer driving section for driving the detection heater layer;
A detection heater layer resistance detector for detecting a change in the heater layer resistance of the detection heater layer;
A temperature detection unit that outputs a detection signal according to the temperature around the gas sensor;
A central processing unit to which a heater layer drive unit, a gas detection unit, a detection heater layer drive unit, a detection heater layer resistance detection unit, and a temperature detection unit are connected;
The central processing unit
A heater layer driving means for driving the heater layer driving unit so as to detect the gas sensing layer by heating the heater layer;
A detection heater layer driving means for driving the detection heater layer driving section so that the detection heater layer heats the detection porous layer;
Gas detection means for detecting the sensor output based on the output from the gas detection unit;
Temperature detection means for detecting the temperature around the gas sensing layer based on the output from the temperature detection unit;
Humidity detection means for reading the heater layer resistance value for the detection heater layer resistance from the detection heater layer resistance detection unit and detecting the humidity around the gas detection layer based on a change in the temperature rise characteristic of the heater layer resistance value after the heater is turned on When,
Correction means for calculating a correction value based on the calculated temperature and humidity, and correcting the sensor output using the correction value;
A determination means for determining the presence or absence of a gas based on the corrected gas concentration;
A gas detection device comprising: In the gas detector according to any one of claims 8 to 10,
The humidity detecting means adsorbs to the detection porous layer, which is heated for a predetermined period from the start of the heater on, as a change in the temperature rise characteristic of the heater layer resistance value from the start of the heater on for the detection heater layer resistance. First heater layer resistance value when the evaporated water does not completely evaporate, and second heater layer resistance when the moisture adsorbed on the porous porous body for detection, which is sufficiently heated from the start of heater ON, is evaporated A gas detection device, characterized in that it is means for calculating a ratio using a value and calculating a humidity corresponding to the ratio. In the gas detector according to any one of claims 8 to 10,
The humidity detection means evaporates the moisture adsorbed on the porous layer for detection, which is sufficiently heated from the start of the heater on, as a change in the temperature rise characteristic of the heater layer resistance value from the start of the heater on for the heater layer resistance. A gas detection device, characterized in that it is means for calculating a time to reach the heater layer resistance value and calculating a humidity corresponding to this time. In the gas detection device according to any one of claims 8 to 12,
A filter cover for partitioning a space including at least the gas sensing layer and the detection porous layer from the outside;
A filter that is provided in the filter cover and that adsorbs a predetermined gas of the detection target gas and introduces the gas into the filter cover;
A gas detection device comprising: In the gas detection device according to any one of claims 1 to 13,
The gas sensor
A Si substrate having a through hole;
A diaphragm-like heat insulating support layer stretched over the opening of the through hole;
The heater layer provided on the thermal insulating support layer;
An electrical insulation layer provided to cover the thermal insulation support layer and the heater layer;
A pair of sensing electrode layers provided on the electrically insulating layer;
The gas sensing layer made of an oxide semiconductor, which is provided on the electrical insulating layer and the pair of sensing electrode layers and in the vicinity of the heater layer, and whose sensor resistance value is changed by the gas in contact with the gas sensing layer;
It is a sensor provided with, The gas detection apparatus characterized by the above-mentioned. The gas detection device according to claim 14, wherein
The gas sensor is further provided so as to cover the surface of the gas sensing layer, and is made of an Al ₂ O ₃ sintered material that supports Pd (palladium), Pt (platinum), or an alloy containing Pd and Pt as a catalyst. A gas detection device comprising a gas selective combustion layer. In the gas detection device according to any one of claims 1 to 15,
A gas detection device that is driven by power supplied from a power source of a built-in battery. A gas sensing layer whose electrical resistance characteristics change by contact with the detection target gas, a gas sensor having a heater layer for heating the gas sensing layer, a heater layer driving unit for driving the heater layer, and an electrical resistance of the gas sensing layer A gas detection method used in a gas detection device provided with a gas detection unit that detects a change, a heater layer resistance detection unit that detects a change in the heater layer resistance of the heater layer, and
The heater layer driving unit is driven so that the gas sensing layer can be detected by heating the heater layer, the sensor output is detected based on the output from the gas sensing unit, and the heater layer resistance sensing unit detects the heater layer resistance. Reads the resistance value, detects the temperature around the gas sensing layer, reads the heater layer resistance value for the heater layer resistance from the heater layer resistance detector, and changes the temperature of the heater layer resistance value after the heater is turned on. Detecting the humidity around the sensing layer, calculating a correction value based on the calculated temperature and humidity, correcting the sensor output using the correction value, and determining the presence or absence of gas based on the corrected sensor output A characteristic gas detection method. A gas sensing layer whose electrical resistance characteristics change by contact with the detection target gas, a gas sensor having a heater layer for heating the gas sensing layer, a heater layer driving unit for driving the heater layer, and an electrical resistance of the gas sensing layer A gas detection device comprising: a gas detection unit that detects a change; a heater layer resistance detection unit that detects a change in the heater layer resistance of the heater layer; and a temperature detection unit that outputs a detection signal corresponding to the temperature around the gas sensor. A gas detection method used,
The heater layer drive unit is driven to make the gas sensing layer detectable by heating the heater layer, the sensor output is detected based on the output from the gas detection unit, and the surroundings of the gas sensing layer based on the output from the temperature detection unit The heater layer resistance detection unit reads the heater layer resistance value for the heater layer resistance, detects the humidity around the gas sensing layer based on the change in the temperature rise characteristic of the heater layer resistance value after the heater is turned on, A gas detection method, comprising: calculating a correction value based on the calculated temperature and humidity, correcting the sensor output using the correction value, and determining the presence or absence of gas based on the corrected sensor output.

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