JP2002323468A - Sensor with gas-kind classifying function, gas sensor with polar-gas classifying function and gas sensor with smoke- containing polar-gas classifying function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor which can be miniaturized and made at low cost by a method, where the structure of a catalytic combustion-type gas sensor and the acquisition timing of a sensor output are optimized and a plurality of gas kinds and smoke can be classified only by one catalytic combustion-type gas sensor, and to provide a sensor which detects gas at a high speed and which achieves low power consumption. SOLUTION: The gas kinds are classified, by using the fact that the sensor output in a rise period from the point of time of an charging start up to the point of time of a steady operation displays a peak waveform specific to a specific kind of gas. The gas kinds and the smoke are classified by using the ratio of a maximum value in the rise period of the sensor output of the catalytic combustion-type gas sensor 40 to a steady value in the point of time of the steady operation. Thereby, the gas kinds can be classified, by using only one sensor 40 used to detect gas leakage. Since the sensor output in the rise period is used to classify the gas kinds the gas kinds can be classified at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas sensor having a function of separating gas species, and more particularly to a gas sensor using a contact combustion type gas sensor and a smoke gas separation sensor having a function of separating smoke.

[0002]

2. Description of the Related Art Conventionally, there have been proposed a large number of gas detectors for detecting gas leakage and the like using a highly versatile catalytic combustion type gas sensor. This example will be described with reference to FIG.
FIG. 13 is a schematic view of a contact combustion type gas sensor used in a conventional gas detection device. In particular, FIGS. 13A and 13B are schematic views of a sensitive element portion and a compensating element portion of a conventional catalytic combustion type gas sensor, respectively.

[0003] In this type of contact combustion type gas sensor, combustion heat obtained by combusting combustible gas and oxygen in the air on a catalyst is detected as a change in resistance of a platinum coil. As shown in FIG. 13A, the sensitive element section
Approximately 1 mm in diameter on a 20 umφ (platinum) Pt coil 42A
The Pd / Al ₂ O ₃ catalyst layer 43A is applied so as to have a spherical shape. Further, as shown in FIG. 13B, the Al ₂ O ₃ catalyst layer 45A is applied to the same Pt coil 44A in a spherical shape having a diameter of about 1 mm in the compensating element portion. In practice, since the resistance change of the Pt coil 42A with respect to the flammable gas is very small, the sensitive element section and the compensation element section are incorporated in a bridge circuit, and a direct current or a pulse is applied to both ends of the bridge circuit. The change in the midpoint voltage of the bridge circuit for the flammable gas is measured as a sensor output.

FIG. 14 is a graph showing a relationship between a gas concentration and a sensor output by the above-mentioned conventional catalytic combustion type gas sensor. In the figure, Gc1 indicates the output characteristic of isobutane, and similarly, Gc2 is hydrogen, Gc3 is ethanol, and Gc3 is
4 shows the output characteristics of methane. As shown in this figure, the sensor outputs corresponding to the above four gases monotonically increase with increasing gas concentration, and all have similar characteristics.
Here, ethanol is an example of a harmless thing that frequently occurs in daily life due to alcoholic beverages. On the other hand, isobutane, hydrogen, methane, and the like are examples of those that should be detected as harmful gases that occur extraordinarily due to gas leakage or the like.

[0005]

However, the above-mentioned conventional catalytic combustion type gas sensor has a large heat capacity and poor responsiveness and measurement accuracy. Therefore, as shown in FIG.
All of the gases exhibited similar output characteristics, and it was difficult to separate and identify them. Therefore, the gas sensor device using the conventional contact combustion type gas sensor has to set a gas detection reference value common to all gas types, and must perform gas detection based on this reference value. As a result, there is a possibility that the gas sensor reacts to a harmless gas such as an ethanol-based gas or an acetic-acid-based gas due to alcoholic beverages, seasonings, and the like existing in a normal household, thereby causing a false alarm. Therefore, as another conventional example in which this point is improved, a gas sensor device in which a filter of activated carbon or the like is attached to a sensor cap in order to provide selectivity to a gas type has been proposed. Further, as another conventional example, there has been proposed a gas sensor device or the like in which a plurality of gas sensors having different characteristics corresponding to gas types are provided and these are simultaneously driven. However, even in these conventional examples, separate means for imparting selectivity such as a filter is required, or a plurality of gas sensors having different characteristics are required, which makes the apparatus complicated, large-sized, and consumes power. There is a problem that the cost is increased due to the increase.

In view of the above-mentioned situation, the present invention optimizes the structure of a contact combustion type gas sensor and the timing of obtaining sensor output, and enables a single contact combustion type gas sensor to separate a plurality of gas types, thereby reducing the size. It is an object of the present invention to provide a gas sensor which has achieved cost reduction and cost reduction. It is another object of the present invention to provide a gas sensor that achieves higher detection speed and lower power consumption.

[0007]

According to a first aspect of the present invention, there is provided a gas sensor having a function of separating gas species according to the first aspect of the present invention, as shown in FIGS.
By utilizing the fact that the sensor output during the rising period from the start of energization of 0 to the steady time T300 at which the sensor output of the catalytic combustion type gas sensor 40 becomes stable exhibits a unique peak waveform for a specific type of gas. The method is characterized by separating seeds.

According to the first aspect of the present invention, the gas type is separated by utilizing the fact that the sensor output in the rising period from the start of energization to the steady state exhibits a unique peak waveform for a specific type of gas. I'm trying to
Only by using one contact combustion type gas sensor 40, a plurality of gas types can be separated. In addition, since the sensor output during the rising period is used, gas types can be separated at high speed.

In order to solve the above-mentioned problem, a gas sensor with a gas type separation function according to claim 2 is provided as shown in FIGS. 1 to 7. In a first rising period from a start time to a specific rising initial time T10 between the energization starting time and the steady time, and in a second rising period from the rising initial time to the steady time, the sensor A first gas having a peak waveform of the output, a second gas having a peak waveform of the sensor output only in the second rising period, and a third gas in which the sensor output monotonically increases in the rising period. A gas sensor with a gas type classification function that outputs a classification result, the method including detecting a presence or absence of a peak waveform of the sensor output during the first rising period. Peak presence / absence detection means 12, second peak presence / absence detection means 13/14 for detecting the presence / absence of a peak waveform of the sensor output during the second rising period, first peak presence / absence detection means 12, and second peak presence / absence detection Based on the peak waveform presence / absence detection results by the means 13 and 14, the gas type separation means 15 for separating the first gas, the second gas, and the third gas, and the separation result by the gas type separation means 15 And a gas detection output means 30 for outputting.

According to the second aspect of the present invention, the first gas having a peak waveform in each of the first rising period and the second rising period, the second gas having a peak waveform only in the second rising period, and the rising period And the third gas in which the sensor output monotonically increases corresponds to the first peak existence detecting means 12.
And the second peak presence / absence detection means 13 and 14 based on the respective peak waveform presence / absence detection results. In other words, by focusing on the sensor output waveform during the rising period of the catalytic combustion type gas sensor 40, the three types of gases can be separated. As described above, the first peak presence / absence detection means 12 and the second peak presence / absence detection means 13 and 14 detect the presence / absence of a peak waveform by focusing on the sensor output during the rising period of the contact combustion type gas sensor 40. The three types of gases can be separated by using only one catalytic combustion type gas sensor 40.

According to a third aspect of the present invention, there is provided a gas sensor with a gas type separation function according to the second aspect of the present invention, as shown in FIGS. One gas is a gas generated due to acetic acid, and the second gas is a gas generated due to ethanol.

According to the third aspect of the invention, a gas generated due to acetic acid, a gas generated due to ethanol, and other gases can be separated. Gases generated due to acetic acid and ethanol are likely to be routinely generated from liquor and seasonings. By separating these, false alarms can be prevented.

According to a fourth aspect of the present invention, there is provided a gas sensor with a gas type separation function according to the first, second, or third aspect, as shown in FIG. The contact combustion type gas sensor 40 includes:
A heater element and a catalyst layer are formed on an insulating film supported on a silicon wafer, and the thin film diaphragm is formed by etching from a back surface of the silicon wafer.

According to the fourth aspect of the present invention, in the contact combustion type gas sensor 40, a heater element and a catalyst layer are formed on an insulating film supported on a silicon wafer, and further, the thin film diaphragm is etched from the back surface of the silicon wafer. Ds
Is formed, the heat capacity can be reduced.

In order to solve the above-mentioned problem, the gas sensor with a polar gas separating function according to claim 5 detects a gas leak and is driven by being intermittently energized, as shown in FIGS. A gas sensor with a polar gas separation function that separates a polar gas using the sensor output during a rising period from the start of energization of the catalytic combustion type gas sensor 40 to a steady state at which the sensor output of the catalytic combustion type gas sensor 40 is stabilized. Then, based on the variation of the ratio between the maximum value of the sensor output during the rising period and the steady-state value that is the value of the sensor output at the steady-state time, due to the variation of the energization interval for the contact combustion type gas sensor 40. The polar gas is separated.

According to the fifth aspect of the present invention, the polar gas is separated using the ratio between the maximum value of the sensor output of the catalytic combustion type gas sensor 40 during the rising period and the steady value at the steady time. That is, the contact combustion type gas sensor 40
When the maximum value and the steady-state value are obtained by using, the polarity ratio can be separated by focusing on the fact that the ratio varies depending on the variation of the energization interval depending on the gas type. As described above, by utilizing the ratio between the maximum value of the sensor output of the contact combustion type gas sensor 40 during the rising period and the steady value at the steady state, the polar gas is detected using the contact combustion type gas sensor 40 that detects gas leakage. Be able to separate.

According to a sixth aspect of the present invention, there is provided a gas sensor having a function of separating a polar gas, wherein the gas sensor has a function of separating a polar gas, as shown in FIGS. A first sensor output acquisition unit for acquiring the maximum value and the steady-state value of the sensor output based on a first energization interval set based on the saturation adsorption time of the polar gas, and a first energization interval longer than the first energization interval A second sensor output acquisition unit 101b for acquiring the maximum value and the steady value of the sensor output based on a second power supply interval;
The first output ratio calculating unit 102 that calculates the ratio based on the maximum value and the steady value obtained by the first sensor output obtaining unit 101a as a first output ratio, and the second sensor output obtaining unit 101b obtains the ratio. The second output ratio calculating means 103 for calculating the ratio based on the obtained maximum value and the steady value as a second output ratio, and based on the comparison between the first output ratio and the second output ratio, A first separation means 104 for separating a polar gas, and a gas detection output means 30 for outputting a result of the separation by the first separation means 104
0 is included.

According to the sixth aspect of the present invention, the first output ratio calculated from the sensor output based on the first energizing interval set based on the saturated adsorption time of the polar gas, and the first energizing interval are smaller than the first energizing interval. The polar gas is separated based on comparison with the second output ratio calculated from the sensor output at the long second energization interval. In other words, the polar gas is separated from the others by utilizing the fact that the output ratio of the polar gas becomes stable when the energization interval is set in consideration of the saturation adsorption time of the polar gas. As described above, by making use of the fact that the output ratio of the polar gas becomes stable when the energization interval is set in consideration of the saturation adsorption time of the polar gas, the contact combustion type gas sensor 4 for detecting gas leakage is used.
By using 0, it is possible to separate the polar gas.

According to a seventh aspect of the present invention, there is provided a gas sensor having a function of separating a polar gas, as shown in FIGS. The polar gas has a first polar gas whose output ratio is about 5 times irrespective of the energization interval, and the output ratio of about 10 to 13 regardless of the energization interval.
A second polarizer gas that is about twice as large, and based on the first output ratio or the second output ratio, separates the first polar gas from the second polar gas. And the gas detection output means 300 also outputs the result of separation by the second separation means 105.

According to the seventh aspect of the present invention, in addition to the separation of the polar gas, the first polar gas having a power ratio of about 5 times regardless of the current supply interval among the polar gases; The second polar gas having an output ratio of about 10 to 13 times can be separated.

A gas sensor having a function of separating a polar gas according to claim 8 which has been made in order to solve the above-mentioned problem is provided in the gas sensor having a function of separating a polar gas according to claim 7 as shown in FIGS. The first energization interval and the second
The energization intervals are about 10 seconds and about 30 seconds, respectively, wherein the first polar gas is a gas generated from ethanol, and the second polar gas is a gas generated from acetic acid. Features.

According to the present invention, the first polar gas generated due to ethanol and the second polar gas generated due to acetic acid can be separated. Since the gas generated due to ethanol and acetic acid is likely to be generated from alcohol and seasonings on a daily basis, it is possible to prevent false alarms by separating these gases.

According to a ninth aspect of the present invention, there is provided a gas sensor with a function of separating a polar gas, as shown in FIG. 4, wherein the function of separating a polar gas according to the fifth, sixth, seventh or eighth aspect is provided. In the attached gas sensor, the contact combustion type gas sensor 40 has a structure in which a heater element and a catalyst layer are formed on an insulating film supported on a silicon wafer, and a thin film diaphragm is formed by etching from the back surface of the silicon wafer. Features.

According to the ninth aspect of the present invention, in the contact combustion type gas sensor 40, a heater element and a catalyst layer are formed on an insulating film supported on a silicon wafer, and the thin film diaphragm is etched from the back surface of the silicon wafer. Ds
Is formed, the heat capacity can be reduced.

According to a tenth aspect of the present invention, there is provided a gas sensor having a function of separating a gas having a polarity of smoke, which detects a gas leak, and at the time of starting energization of a contact combustion type gas sensor 40 driven by intermittent energization. A gas sensor with a function of separating a polar gas and a smoke generated at the time of fire by using the sensor output in a rising period until a steady time when the sensor output of the catalytic combustion type gas sensor 40 is stabilized. Along with the fluctuation of the energization interval to the contact combustion type gas sensor 40, based on the fluctuation state of the ratio between the maximum value of the sensor output during the rising period and the steady value which is the value of the sensor output at the steady time. It is characterized by separating polar gas and smoke.

According to the tenth aspect of the present invention, the ratio of the maximum value of the sensor output of the catalytic combustion type gas sensor 40 during the rising period to the steady state value at the steady state is utilized to detect the gas leakage of the contact combustion type gas sensor 40. Gas sensor 40
Can be used to separate polar gases and smoke generated during a fire. Further, a gas type separation filter or the like is not required. As a result, a small-sized, low-cost and high-performance gas sensor can be obtained.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment First, a first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, first, a basic configuration, a driving waveform, and a method of classifying gas will be described with reference to FIGS. FIG. 1 is a block diagram showing a basic configuration of a first embodiment of a gas sensor with a gas type separation function of the present invention. FIGS. 2A and 2B are time charts showing examples of driving waveforms according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram showing a criterion for gas type separation and a gas determination pattern according to the first embodiment of the present invention.

As shown in FIG. 1, the controller 10 is connected to a drive power supply 20, a gas detection output unit 30, and a catalytic combustion type gas sensor 40 including a bridge circuit for detection. In the gas sensor with a gas type separation function, a drive pulse as shown in FIG. 2 is supplied to control the energization of the contact combustion type gas sensor 40, and the controller 10 classifies the gas type based on the sensor output of the sensor 40. Gas detection output is performed. As shown in FIG. 6, this separation principle is based on the fact that the sensor output during the rising period from the start of energization of the catalytic combustion type gas sensor 40 to the steady state at which the sensor output stabilizes is a specific type of gas (eg, acetic acid, ethanol, etc.). Which utilizes a unique peak waveform, which will be described later.

As shown in FIG. 2 (A), the controller 10 performs the driving pulse energizing period D10 of which one cycle is composed of the pulse OFF period of 10 seconds and the energizing period D10 of 400 ms. As shown in), sensor outputs are obtained at the time T5, the time T10, the time T20, and the time T300 from the pulse ON. These times T5, T10, T20, and T300 are set based on data collected in advance so that a peak waveform specific to a specific gas can be easily identified and detected.

The controller 10 includes a sensor output acquisition unit 11, first to third determination units 12 to 14, and a gas type separation unit 1.
5, judgment pattern storage means 16, sensor drive control means 1
7 and correction means 18. The controller 10 includes, as hardware, an operation unit, a storage unit, a timer unit, and the like. Each of the units 11 to 16 performs a processing operation in FIG. 7 described below performed by the operation unit according to a control program stored in the storage unit. It corresponds to.

The sensor output acquiring means 11 transmits, via the correcting means 18, the time points T5, T10, T20 shown in FIG.
Then, the sensor output is obtained at T300. Then, the sensor output acquiring means 11 determines the time T5, T10, T20
And T300, respectively, comprising a first time point output obtaining means 11a, a second time point output obtaining means 11b, a third time point output obtaining means 11c, and a fourth time point output obtaining means 11d. For example, the first time point output obtaining means 11a obtains the sensor output at the time T5 at 5 ms from the pulse ON, and similarly, the second time point output obtaining means 11b, the third time point output obtaining means 11c, and the fourth time point output obtaining means 11d. Are also T10 at 10 ms, T20 and 30 at 20 ms, respectively.
The sensor output at time T300 at 0 ms is obtained.

The first to third judging means 12 to 14 receive the sensor output at each time supplied from the sensor output acquiring means 11 and determine Y or N according to the judging criteria shown in FIG. Output the judgment result. The first determination unit 12, the second determination unit 13, and the third determination unit 14 in FIG. 1 correspond to the first determination YN1, the second determination YN2, and the third determination YN2 in FIG.
Y or N is determined by a method corresponding to the determination YN3. For example, the first determination unit 12 determines the 10 ms output S10 (sensor output at the time T10) and the 5 ms output S5 (sensor output at the time T5) according to the determination criterion indicated by the first determination YN1. By comparison, if the criterion is satisfied, Y is output, otherwise N is output. Similarly, the second judging means 13 and the third judging means 14 also have the judgment criteria shown in FIG. 3, the second judgment YN2 and the third judgment YN3, respectively.
Then, Y or N is output.

By the way, the first judging means 12
The Y or N is output by comparing the ms output S10 with the 5ms output S5. Although not shown in FIG. 3, when the output at 0 ms (sensor output at the time of pulse ON) is compared with the output S5 at 5 ms,
In any case, the output S5 at the time of 5 ms is larger. That is, Y or N of the first determination means 12
, The presence / absence of a peak waveform of the sensor output at 0 to 10 ms (corresponding to the first rising period of claim 2) is detected. Similarly, the presence / absence of the peak waveform of the sensor output at the time of 10 to 300 ms (corresponding to the second rising period of claim 2) is detected by the second determination unit 13 and the third determination unit 14. That is, the first determination unit 12 corresponds to a first peak presence / absence detection unit, and the second determination unit 13 and the third determination unit 14 correspond to a second peak presence / absence detection unit. Note that the 5 ms point T5 corresponds to a specific initial rising point in claim 2, and the 300ms point T300 corresponds to a steady point. The time points T5 and T300 are set in the first embodiment in consideration of the characteristics of acetic acid and ethanol and the sensor performance described later. If the fractionated gas is different or the sensor performance is different, the time may be changed as appropriate. May be.

The gas type discriminating means 15 receives the judgment results of each of Y or N outputted by the first to third judging means 12 to 14 and receives the gas judgment pattern stored in the judgment pattern storing means 16 (see FIG. 3). by referring to the illustrated), sensor output, acetate, ethanol or methane, to determine whether to match any of the three patterns, such as H _2, the judgment result, i.e., outputs the gas fractionation results. For example, the first
If the determination YN1 is N, the second determination YN2 is Y, and the third determination YN3 is N, it means that the gas type separation means 15 has separated and detected acetic acid from the sensor output at this time. Similarly, the first determination YN1 is Y, the second determination YN2 is Y,
If the determination YN3 is N, ethanol, the first determination YN1 is Y,
If the second determination YN2 is Y and the third determination YN3 is Y, methane is used.
This means that H _{2 and the} like are separately detected. This separation will be described more specifically using data in FIGS.

The sensor drive control means 17 controls the energization of the drive power supply 20 to the contact combustion type gas sensor 40 and
(A) As shown in (B), a drive pulse composed of one cycle of a pulse OFF period of 10 seconds and a conduction period D10 of 400 ms is continuously generated until the power is turned on and a predetermined trigger is present. Let it. 2A and 2B.
In the drive pulse indicated by, the level of the drive pulse corresponding to OFF is not always zero. That is, a DC bias may be applied to this drive pulse so that the sensor output acquisition unit 11 easily acquires a desired sensor output.

The correction means 18 supplies the sensor output obtained by performing a predetermined correction to a detection output from a bridge circuit described later as a sensor output to the sensor output acquisition means 11. That is, the detection output from the bridge circuit in pure air by the drive pulse shown in FIG. 2 was measured in advance as an initial detection output, and this initial detection output was subtracted from the detection output actually obtained from the bridge circuit. This is supplied to the sensor output obtaining means 11 as the sensor output.

As the drive power supply 20, an existing battery or the like is used. The gas detection output means 30 receives a gas type determination result from the gas type classification means 15 of the controller 10 and outputs the determination result. The gas detection output means 30
For example, a known speaker or LED that emits a gas leak alarm by voice or light emission display or the like, and a driver circuit thereof are provided. If the determination result indicates acetic acid or ethanol, they are harmless to the human body, so that no alarm is issued from the gas detection output means 30. Alternatively, only a display is made and no sound alarm is issued. The above determination result is H
_{When 2} or the like is indicated, it is an abnormal situation, and an audio alarm or both an audio alarm and a display alarm are issued. In addition, in order to distinguish the detection of acetic acid or ethanol, you may make it display LED of a different color.

The contact combustion type gas sensor 40 is supplied with a drive pulse as shown in FIGS. 2A and 2B and is driven intermittently. This contact combustion type gas sensor 40
Is basically composed of a sensitive element section Rs and a compensating element section Rr. The sensitive element portion Rs includes a (platinum) Pt heater 42 and a Pd / Al ₂ O ₃ catalyst layer 43, and the compensation element portion Rr includes a Pt heater 44 and a (alumina) Al ₂ O ₃ catalyst layer 45. The Pt heaters 42 and 44 have a fixed resistance R
1, R2 and the variable resistor Rv constitute a bridge circuit. A drive pulse is intermittently supplied at predetermined intervals to the connection point between the Pt heater 44 and the fixed resistor R1 and the connection point between the Pt heater 42 and the fixed resistor R2 in the bridge circuit via the controller 10. . Further, a voltage value as a sensor output is supplied to the controller 10 from a connection point between the Pt heaters 42 and 44 and the variable resistor Rv.

When using the contact combustion type gas sensor 40, first, before the detection operation is started, the correction means 1 is used.
The variable resistor Rv is adjusted so that the sensor output supplied from 8 to the sensor output obtaining means 11 becomes zero. In this state, when the CO gas or the like touches the sensitive element portion Rs, it is oxidized by the catalytic action on the surface of the element to generate reaction heat. Due to the reaction heat, the resistance value of the Pt heater 42 increases, and the balance of the bridge circuit is broken due to the increase in the resistance value, and the sensor output is supplied to the controller 10. In this case, the Pt heater 44 compensates for the fluctuation of the resistance value of the Pt heater 42 due to the fluctuation of the ambient temperature and to take out only the fluctuation component of the resistance value of the Pt heater 42 caused by the reaction heat. The structure of the contact combustion type gas sensor 40 will be described later with reference to FIG.

Next, the structure of the catalytic combustion type gas sensor 40 used in the first embodiment will be described with reference to FIG. 4A, 4B, and 4C are a plan view, a rear view, and a cross-sectional view taken along line AA of the contact combustion type gas sensor 40, respectively.

As shown in FIGS. 4A and 4B, this contact-combustion gas sensor uses a (silicon) Si wafer 41.
An insulating thin film composed of an (oxidized) SiO ₂ film 48c, a (nitrided) SiN film 48b, and a (hafnium oxide) HfO ₂ film 48a is formed thereon, and (platinum) Pt is formed thereon as a sensitive element portion Rs. A heater 42, a Pd / Al ₂ O ₃ catalyst layer 43, and a (platinum) Pt heater 44 and an (alumina) Al ₂ O ₃ catalyst layer 45 are formed as a compensating element portion Rr.
Further, as shown in FIG. 3C, the concave portions 46 and 47 are formed by anisotropic etching, and the thin films diaphragms Ds and Dr are formed to reduce the heat capacity. With such a configuration, a contact combustion type gas sensor capable of high-speed reaction and having improved measurement accuracy can be obtained. Further, since the heat capacity is reduced, the power consumption is reduced.

Next, the output characteristics of each gas by the catalytic combustion type gas sensor 40 used in the above embodiment will be described with reference to FIGS. FIG. 5 and FIG.
5 is a graph showing sensor output characteristics of a non-polar gas and a polar gas by a contact combustion type gas sensor 40. FIG.
In FIG. 6 and FIG. 6, the horizontal axis represents the elapsed time from the pulse ON point (zero point in the figure) when the driving pulse as shown in FIG. 2 is supplied to the contact combustion type gas sensor 40.

In FIG. 5, Sv1 is (carbon monoxide) C
The graph shows the sensor output characteristics of O gas, and similarly, Sv2, Sv
3 and Sv4 indicate the sensor output characteristics of (methane) CH ₄ gas, (hydrogen) H ₂ gas, and (isobutane) i · C ₄ H ₁₀ gas, respectively. These gases are mainly generated at the time of gas leakage, and here, the concentration of each gas is 100
Data was collected at 0 ppm. As shown in FIG. 5, the sensor output for the four types of gases rises in a specific waveform from the time 0 (pulse ON time) until 100 ms elapses, but after 100 ms, the sensor output becomes steady. It turns out that it becomes a state. However, it can be seen that these nonpolar gases monotonically increase from the pulse ON point to the 100 ms point, and then have a common fluctuation pattern that stabilizes at a constant value unique to each gas. By utilizing such characteristics, the present contact combustion type gas sensor 40 can detect an abnormal situation such as gas leakage.

In FIG. 6, Sv5 is (acetic acid) C
Shows the sensor output characteristics of the H ₃ COOH gas, SV6 shows the sensor output characteristics of (ethanol) C ₂ H ₅ OH gas. These gases are mainly generated in the kitchen and the like in daily life due to seasonings and alcoholic beverages. Here, the concentration of each gas was 1000 ppm, and data was collected.
As shown by Sv5 in FIG. 6, the sensor output for acetic acid sharply increases until 5 ms elapses from the pulse ON time, reaches the first peak at this time, and then sharply decreases. Then, after reaching a minimum at the time of 10 ms, it rises rapidly again and reaches the second peak at the time of 30 ms. After that, it decreases monotonically and becomes a steady state of the intrinsic output value at the time of elapse of 200 ms. That is, this Sv5
It can be seen that the sensor output for acetic acid shown in (1) has a peak waveform having two peaks until it reaches a steady state. This acetic acid corresponds to the first gas of claim 2.

Further, as shown by Sv6 in FIG. 6, the sensor output for ethanol is 30 m from the pulse ON time.
After abrupt increase until s elapses and a peak at this time, it monotonously decreases and becomes a steady state of the intrinsic output value at the elapse of 200 ms. That is, it can be seen that the sensor output for ethanol shown in Sv6 has a peak waveform having one peak until it reaches a steady state. Utilizing such a unique peak waveform characteristic, the present catalytic combustion type gas sensor 40 can separate and detect acetic acid and ethanol. This ethanol corresponds to the second gas of claim 2.

It is considered that the specific pulse waveform as described above is generated because the attraction force is a major factor. That is, the polarity of acetic acid, ethanol, etc. is large,
In a gas having a large adsorption force, gas molecules are adsorbed on the sensor surface during the pulse OFF period, and when the pulse is turned ON and the sensor is energized, the adsorbed gas burns instantaneously, and accordingly, the sensor output increases. At this time, a catalytic combustion reaction also occurs at the same time. On the other hand, non-polar or low-polarity gases such as methane, hydrogen, and carbon monoxide have low adsorption power, so the above phenomenon does not occur, and the sensor output gradually increases until it is stabilized at a steady value. .

As described above, the gas type is separated by utilizing the fact that a specific type of gas exhibits a unique peak waveform. Therefore, a plurality of gas types can be separated only by using one contact combustion type gas sensor. become able to. This allows
Gas generated due to acetic acid and ethanol generated daily from alcohol and seasonings can be separated, and a highly reliable gas sensor with few false alarms can be obtained.

The processing operation performed by the controller 10 to separate the gas species using the sensor output characteristics of each gas as shown in FIGS. 5 and 6 will be described with reference to FIG.

FIG. 7 is a flowchart showing a processing operation according to the first embodiment of the present invention. In this embodiment, a driving pulse as shown in FIG. 2 is used, and a 5 ms point T5, a 10 ms point T10,
At the time T20 at 20 ms and the time T300 at 300 ms, the sensor output is obtained. Then, after the sensor outputs acquired at the respective times T5, T10, T20 and T300 are Y / N-determined according to the criterion shown in FIG. 3, the gas type is determined with reference to the gas determination pattern shown in FIG. Is done. Thereby, a plurality of types of gases are separated by using one contact combustion type gas sensor.

In step P1 of FIG. 7, the time T at 5 ms in the energizing period D10 of the drive pulse shown in FIG.
In 5, the sensor output of the catalytic combustion type gas sensor 40 is
It is obtained as a 5 ms point-in-time output S5. Similarly, in step P2, step P3, and step P4, respectively, 10 ms time T10, 20 ms time T20, and 3 in the drive pulse energizing period D10 shown in FIG.
At the time T300 at 00 ms, the sensor outputs are obtained as the output S10 at the time 10 ms, the output S20 at the time 20 ms, and the output S300 at the time 300 ms, respectively. These outputs S5, S10, S20, and S300 are temporarily stored in a storage unit of the controller 10.

Next, in step P5, the temporarily stored 5ms output S5 and 10ms output S10 are read out, and these are stored in the determination pattern storage means 16 according to the determination criteria shown in FIG. Based on Y / N
Is determined. Similarly, in step P6, 10 ms
The point-in-time output S10 and the 20-ms point-in-time output S20 are read, and in step P7, the 20-ms point-in-time output S20 and the 300-ms point-in-time output S300 are read, and these are stored in the determination pattern storage means 16 according to the determination criteria shown in FIG. Y / N determination is made based on this. These Y / N determination results are also temporarily stored in the storage unit of the controller 10. Step P5 corresponds to the first peak presence / absence detecting means in claim 2. Steps P6 and P7 correspond to the second peak presence / absence detecting means.

Then, in step P8, the temporarily stored determination results of the first determination YN1, the second determination YN2, and the third determination YN3 are read out, and these are stored in the determination pattern storage means 16. The gas type is discriminated by comparison with the gas determination pattern indicated by. The determination in step P8 is the first determination YN1, the second determination YN
2. If N, Y, N in the order of the third determination YN3, the process proceeds to the acetic acid detection output process of step P9, and if Y, Y, N, the process proceeds to the ethanol detection output process of step P10. If Y, Y, methane in step P11, H
Move on to _second- class detection output processing. Note that the above step P8
Corresponds to the gas type separation means of claim 2.

In the acetic acid detection output processing and the ethanol detection output processing in steps P9 and P10, since they are harmless to the human body, no alarm is issued from the gas detection output means 30. Alternatively, only a display is made and no sound alarm is issued. Or, in order to distinguish the detection of acetic acid or ethanol, Step P9 and Step P10
In the above, LED display of different colors may be performed.

On the other hand, methane and H in step P11
_{In the second-} class detection output process, since there is a possibility of an abnormal situation, the gas detection output unit 300 issues an audio alarm or both an audio alarm and a display alarm. However, this step P11 is also performed in a normal state that does not include any gas. Therefore, in order to distinguish this normal state from the above-mentioned abnormal state, the sensor output of the output S300 at the time of 300 ms is monitored, and an alarm is issued in the normal state. Not to be. Steps P9, P10 and P11 correspond to the gas detection output means in claim 2.

In this flowchart, only the process corresponding to one cycle of the drive pulse shown in FIG. 2 is shown. However, in reality, this drive pulse is continuously generated and the above process is continuously performed. To do. Thereby, gas separation can be performed more reliably.

As described above, according to the first embodiment, the presence or absence of a peak waveform is detected in steps P5, P6, and P7 by focusing on the sensor output during the rising period of the catalytic combustion type gas sensor 40. Therefore, three types of gases having different peak waveforms can be separated by using only one catalytic combustion type gas sensor. Further, a gas type separation filter or the like is not required. As a result,
A low-cost and high-performance gas sensor with a gas classification function can be obtained. In particular, it is possible to separate gas generated from acetic acid and ethanol, which are generated from alcohol and seasonings on a daily basis, from other gases, so that a highly reliable gas sensor with few false alarms can be obtained. Become. Further, FIG.
Since a contact combustion type gas sensor having a small heat capacity is used and a sensor output during the rising period is used to utilize an instantaneous combustion reaction, gas species can be separated at high speed.

Second Embodiment A second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, first, a basic configuration and driving waveforms will be described with reference to FIGS. FIG. 8 is a block diagram showing a basic configuration of a second embodiment of the gas sensor with a gas type separation function of the present invention. FIG.
9 is a time chart illustrating an example of a driving waveform according to the second embodiment of the present invention.

As shown in FIG. 8, the controller 100 is connected to a drive power supply 20, a contact combustion type gas sensor 40 including a bridge circuit for detection, and gas detection output means 300. In this gas sensor with gas type separation function,
The drive pulse as shown in FIG. 9 is supplied to control the energization of the contact combustion type gas sensor 40. Based on the sensor output of the sensor 40, the controller 100 classifies the gas type and outputs the detected gas. As shown in FIG. 11, the separation principle calculates the ratio between the maximum value of the sensor output during the rising period of the catalytic combustion type gas sensor 40 and the steady value of the sensor output at the steady time, that is, the output ratio, and calculates the fluctuation of the power supply interval. The gas type is separated based on the degree of fluctuation of the output ratio accompanying this, which will be described later again.

The controller 100 operates for 400 ms immediately after the pulse OFF period of 10 seconds as shown in FIG.
The sensor output is acquired in the energization period D10 of 400 ms and the energization period D30 of 400 ms immediately after the pulse OFF period of 30 seconds. The controller 100 includes a sensor output acquisition unit 101, first and second output ratio calculation units 102 and 103, first and second classification units 104 and 105, a sensor drive control unit 170, and a correction unit 180. The controller 100 includes an arithmetic unit, a storage unit, a timer unit, and the like as hardware.
Reference numeral 105 corresponds to a processing operation of FIG. 12 described later performed by the arithmetic unit in accordance with the control program stored in the storage unit.

The sensor output obtaining means 101 obtains the sensor output via the correction means 180 during the above-described energization periods D10 and D30 shown in FIG. These energization periods D1
Although 0 and D30 are both 400 ms, during this period, the sensor output is acquired, for example, every 5 ms. That is, sampling is performed 80 times in each of the energization periods D10 and D30. The sensor output obtaining means 101 is provided with a first sensor output obtaining means 101a and a second sensor output
It comprises a sensor output obtaining means 101b. This first
The sensor output acquisition unit 101a is configured to set the above-described 1 based on the saturated adsorption time of a polar gas such as acetic acid or ethanol.
400 ms energization period D1 immediately after 0 second pulse OFF
The maximum value and the steady value are obtained from the 80 sensor outputs at 0. The maximum value and the steady value will be described later. Further, the second sensor output acquisition unit 101b controls the 400-ms conduction period D immediately after the 30-second pulse OFF.
The maximum value and the steady value are obtained from the 80 sensor outputs at 30.

The first output ratio calculating means 102 outputs the first output ratio
The ratio between the maximum value and the steady value acquired by the sensor output acquisition means 101a, that is, (maximum value−steady value) / steady value in the energization period D10 is calculated as the first output ratio. Further, the second output ratio calculating means 103 outputs the ratio between the maximum value and the steady value acquired by the second sensor output acquiring means 101b, that is, (maximum value−steady value) / steady value in the energization period D30 as the second output. Calculate as ratio. This maximum value-steady value corresponds to the maximum adsorption combustion output described later, and the steady value corresponds to the contact combustion output.

The first separating means 104 separates the polar gas from other gases based on the comparison between the first output ratio and the second output ratio. The second sorting means 105 further includes a first polar gas having an output ratio of about 5 times, regardless of the current supply interval, based on the first output ratio or the second output ratio. And the output ratio is about 10-1
The second polar gas, which is about three times as large, for example, acetic acid is separated.

The sensor drive control means 170 controls the energization of the drive power supply 20 to the contact combustion type gas sensor 40 to generate a drive pulse having an energization interval of 10 seconds and 30 seconds as shown in FIG. It is generated continuously until there is a predetermined trigger. In the driving pulse shown in FIG. 9, the level of the driving pulse corresponding to OFF is not always zero. That is, a DC bias may be applied to the drive pulse so that the sensor output acquisition unit 101 easily acquires a desired sensor output.

The correction means 180 supplies the sensor output obtained by performing a predetermined correction to the detection output from the bridge circuit described later as a sensor output to the sensor output obtaining means 101. That is, the detection output from the bridge circuit in pure air by the driving pulse shown in FIG. 9 was measured in advance as an initial detection output, and the initial detection output was subtracted from the detection output actually obtained from the bridge circuit. Things,
The sensor output is supplied to the sensor output obtaining means 101 as the sensor output.

The drive power supply 20 is the same as that described in the first embodiment of FIG. 1, and the description is omitted here. The gas detection output means 300 is provided by the controller 100
Receiving the gas type separation results from the first and second separation means 104 and 105, and outputs the separation results. The gas detection output unit 300 includes, for example, a known speaker or LED that emits a gas leak alarm by voice or light emission display, and a driver circuit thereof. If the above determination result indicates acetic acid or ethanol, they are harmless to the human body, so that no alarm is issued from the gas detection output means 300. Alternatively, only a display is made and no sound alarm is issued. The determination result is indicative of H _2, etc., so abnormal situation, to issue a both voice alarm or voice alarm and display alarm. In addition, in order to distinguish the detection of acetic acid or ethanol, you may make it display LED of a different color.

The contact combustion type gas sensor 40 has the same configuration as that shown in the first embodiment of FIG. 1 and FIG. 4, and only the supplied drive pulse is different, so that the description is omitted here. . This contact combustion type gas sensor 40
Before using the detection operation, the variable resistor Rv is adjusted so that the sensor output supplied from the correction unit 180 to the sensor output acquisition unit 101 becomes zero before the detection operation starts.

Further, referring to FIGS. 10 and 11, the output ratio as a criterion for gas type separation of the gas sensor with gas type separation function will be described. FIG. 10 shows that the driving interval of the present catalytic combustion type gas sensor was set to 1 using ethanol as a test substance.
It is a graph which shows each sensor output at the time of 10 seconds, 10 seconds, and 30 seconds. FIG. 11 is a graph showing the output ratio of a plurality of gases when the gas concentration and the drive interval are changed. In FIG. 10, the horizontal axis represents the elapsed time from the pulse ON time (time 0 in the figure) when the drive pulse as shown in FIG. 9 described above is supplied to the contact combustion type gas sensor 40. In FIG. 11, the numerical value below the horizontal axis indicates the driving interval-gas concentration.

In FIG. 10, H1 indicates the sensor output characteristic of ethanol during the 400 ms energization period D1 immediately after the drive interval is set to 1 second. Similarly, H10 is an energizing period D of 400 ms immediately after the drive interval is set to 10 seconds.
10, the sensor output characteristic of ethanol, H30 is a 400 ms energization period D3 immediately after the drive interval is set to 30 seconds.
7 shows a sensor output characteristic of ethanol at 0. As shown in FIG. 10, when the pulse drive interval is changed from 1 second to 10 seconds, the sensor output, particularly the peak value, greatly changes. However, even when the pulse drive interval is changed from 10 seconds to 30 seconds, the sensor output is not changed. It can be seen that there is a saturation characteristic that hardly fluctuates. This is because the saturated adsorption time of ethanol is 10-3.
0 seconds. It has been found that the saturation adsorption time of a polar gas other than ethanol is almost 10 to 30 seconds. On the other hand, since non-polar gases such as methane, hydrogen, and carbon monoxide have a smaller adsorbing power than polar gases, it is known that there is no such characteristic of the saturated adsorption time of 10 to 30 seconds. Thus, the polar gas is 1
By utilizing the fact that it has a saturated adsorption time of about 0 to 30 seconds, it becomes possible to separate polar gases.

FIG. 11 shows the output ratio of a plurality of types of gases when the gas concentration and the drive interval are changed. This output ratio is generally expressed as maximum adsorption combustion output / contact combustion output. The contact combustion output (corresponding to the steady value of claim 5) is an output value when the sensor output is in a steady state, and the maximum adsorption combustion output is a value obtained by subtracting the contact combustion output from the peak output. In the example of FIG.
0 ms, and the contact combustion output is 300
The sensor output is at the time of the elapse of ms, and the peak output is the maximum value of the sensor output during the power supply period. Then, by setting the driving intervals of the driving pulse to 10 seconds and 30 seconds, data on the output ratio of ethanol, acetic acid, cotton wick, and wood to smoke is collected and calculated. In each drive interval,
The data collected and calculated by setting three types of gas concentrations are also described.

As shown in FIG. 11, the output ratio of ethanol depends on the set driving interval and gas concentration, and the output ratio is almost 5 times and is constant. Acetic acid depends on the set drive interval and gas concentration. The output ratio is approximately 10 to 13
It is about twice. That is, these polar gases are 10 to
Since the saturated adsorption time is about 30 seconds, it is understood that the output ratio is stable regardless of the drive interval. On the other hand, it can be seen that there is a correlation between the drive interval and the gas concentration of the other cotton wick and wood smoke at the set drive interval and the gas concentration. By utilizing such characteristics, a polar gas such as ethanol or acetic acid can be separated from other types of gas or smoke. Further, the output ratio characteristics of ethanol and acetic acid can be used to separate ethanol and acetic acid. As described above, by using the output ratio, the gas type can be separated only by using the contact combustion type gas sensor used for detecting one gas leak.

The processing operation performed by the controller 100 for performing the gas type separation utilizing the output ratio characteristics of each gas as shown in FIG. 11 will be described with reference to FIG. FIG. 12 is a flowchart showing a processing operation according to the second embodiment of the present invention. In this embodiment, FIG.
The contact combustion output is acquired at a time point of 300 ms after the pulse is turned on using a drive pulse as shown in FIG.
The maximum value of the sensor output during the current application period is obtained as the peak output. Then, the output ratios of the driving intervals of 10 seconds and 30 seconds are compared to separate ethanol, acetic acid and others.
The drive intervals of 10 seconds and 30 seconds are set based on the saturation adsorption time of a polar gas such as acetic acid or ethanol.

In step P101 in FIG. 11, in the energizing period D10 immediately after the drive interval shown in FIG. 9 is 10 seconds, for example, a total of 80 sensor outputs W10 every 5 ms are output.
Is obtained. Similarly, in step P102, a total of 80 sensor outputs W
30 are obtained. These acquired sensor outputs are temporarily stored in the storage unit of the controller 100.

Next, in step P103, the sensor output W for 80 times in D10 that has been temporarily stored is stored.
From 10, the maximum value and the steady value (contact combustion output) are obtained. Then, in step P104, using the maximum value and the steady value acquired in step P103,
(Maximum value−steady value) / steady value is calculated as the first output ratio. Note that the above steps P103 and P10
Reference numerals 4 correspond to a first sensor output acquisition unit and a first output ratio calculation unit, respectively.

Similarly, in step P105, the maximum value and the steady value (contact combustion output) are obtained from the temporarily stored sensor output W30 of D30 at 80 times.
Is obtained, and in Step P106, Step P1
By using the maximum value and the steady value acquired in 05, (maximum value-steady value) / steady value is calculated as the second output ratio. The first output ratio and the second output ratio are determined by the controller 1
00 is temporarily stored in the storage unit. Step P105 above
And step P106 correspond to a second sensor output obtaining means and a second output ratio calculating means in claim 6, respectively.

Then, in step P107, the temporarily stored first output ratio and second output ratio are read out, and based on the comparison between the first output ratio and the second output ratio, the polar gas is replaced with another one. Separated from gas. This classification is
For example, using the output ratio characteristics shown in FIG. 11, if the first output ratio and the second output ratio are within the fluctuation range of about 20%, there is no change, that is, the detected gas is acetic acid. The process proceeds to step P108 after determining that the gas is a polar gas such as ethanol or ethanol, and otherwise, there is a change.
It moves to 11. Incidentally, the step P107 corresponds to a first classification means of the present invention.

In step P108, the output ratio characteristic shown in FIG. 11 is used to separate ethanol and acetic acid based on either the first output ratio or the second output ratio. That is, if the first output ratio (or the second output ratio) is about 5, the detected gas is determined to be ethanol, and the flow shifts to Step P109 where the detected gas is determined to be 10 to 1
If it is about 3, the detected gas is determined to be acetic acid, and the program shifts to Step P110. As an additional explanation, ethanol and acetic acid both have a specific output ratio irrespective of the energization interval. Therefore, the judgment in step P108 can be made using either the first output ratio or the second output ratio. Good. Incidentally, the step P108 corresponds to a second classification means of the present invention.

In this way, when ethanol, acetic acid, and others are separated, step P109,
In Step P110 and Step P111, an ethanol detection output process, an acetic acid detection output process, and other detection processes are performed. Step P109 and Step P1
In the ethanol detection output processing and the acetic acid detection output processing in 10, since they are harmless to the human body, no alarm is issued from the gas detection output means 300. Alternatively, only a display is made and no sound alarm is issued. Alternatively, to distinguish between ethanol detection and acetic acid detection, step P10
In step 9 and step P110, LEDs of different colors may be displayed. Step P109 above,
Steps P110 and P111 correspond to the gas detection output means of claim 6.

On the other hand, in the other detection output processing in step P111, the detected gas is a cotton wick shown in FIG. 11, smoke caused by wood burning, a non-polar gas such as methane gas or hydrogen gas, or It may correspond to a gas of very low polarity. Realistically, the cotton wick, or smoke resulting from the burning of wood, occurs during a fire,
It is considered that a nonpolar gas such as the methane gas or the hydrogen gas or a gas having a very small polarity is generated at the time of gas leakage. In other words, the fact that the process has reached step P111 means that there is a possibility of an abnormal situation. Therefore, the gas detection output means 300 issues an audio alarm or both an audio alarm and a display alarm. When issuing this alarm, for example, methane gas or hydrogen gas is detected using the method of the first embodiment, and as shown in the graph corresponding to the cotton wick and wood in FIG. It is also possible to detect a tendency to increase as the concentration increases, to detect smoke from a fire, and to change the way of alarming according to the result. However,
Since there is a possibility that this step P111 will be performed in a normal state that does not belong to such abnormality detection, the normal state is distinguished from the above-mentioned abnormal state by, for example, setting the period P3 during the power-on period
The sensor output at the time of 00 ms is monitored so that no alarm is issued in a normal state.

In this flowchart, only the process corresponding to one cycle of the drive pulse shown in FIG. 2 is shown. However, in reality, this drive pulse is continuously generated and the above process is continuously performed. To do. Thereby, gas separation can be performed more reliably.

As described above, according to the second embodiment, when the energization interval is set in consideration of the saturation adsorption time of a polar gas such as acetic acid or ethanol, the output ratio of the polar gas becomes stable. By using such a gas, it is possible to separate polar gases from others by using only one contact combustion type gas sensor for detecting gas leakage. Further, among polar gases,
A gas generated due to ethanol having an output ratio of about 5 and a gas generated due to acetic acid having an output ratio of about 10 to 13 can be distinguished regardless of the current supply interval. That is, the gas generated due to ethanol and acetic acid which is generated from alcohol and seasonings on a daily basis can be separated from the other gases, so that a highly reliable gas sensor with few false alarms can be obtained. Of course, the gas can be separated only by using one contact combustion type gas sensor, so that it is needless to say that a small, low-cost and high-performance gas sensor with a gas type separation function can be obtained as in the first embodiment. Further, since a contact combustion type gas sensor having a small heat capacity as shown in FIG. 4 is used to acquire the sensor output during the rising period and utilize an instantaneous combustion reaction, it is possible to perform high-speed gas type separation. become.

The present invention does not limit the acquisition time of each sensor output, energization interval, energization time, and the like to the values exemplified in the first and second embodiments. Their values are
It can be changed as appropriate without changing the gist of the present invention. In addition, the present invention is applicable to gases having a specific output ratio other than ethanol and acetic acid exemplified as polar gases in the second embodiment.

[0083]

As described above, according to the first aspect of the present invention, the sensor output during the rise from the start of energization to the steady state exhibits a unique peak waveform for a specific type of gas. Is used to separate gas types, so that only one contact combustion type gas sensor 40 can be used to separate a plurality of gas types. Further, a gas type separation filter or the like is not required. As a result,
A small, low-cost, high-performance gas sensor with a gas type separation function can be obtained. Further, since the sensor output during the rising period is used, the gas type can be separated at a high speed.

According to the second aspect of the present invention, focusing on the sensor output during the rising period of the catalytic combustion type gas sensor 40, the first peak presence / absence detection means 12 and the second peak presence / absence detection means 13 and 14 provide peak waveforms. Since the presence / absence is detected, three types of gases having different peak waveforms can be separated by using only one catalytic combustion type gas sensor 40. As a result, a small-sized, low-cost and high-performance gas sensor with a gas classification function can be obtained.

According to the third aspect of the present invention, a gas generated due to acetic acid, a gas generated due to ethanol, and other gases can be separated. Since the gas generated due to acetic acid and ethanol is likely to be generated from alcohol and seasonings on a daily basis, it is possible to separate them, which means that a highly reliable gas sensor with few false alarms can be obtained. It turns out that.

According to the fourth aspect of the present invention, in the contact combustion type gas sensor 40, the heater element and the catalyst layer are formed on the insulating film supported on the silicon wafer, and the thin film diaphragm is etched from the back surface of the silicon wafer. Ds
Is formed, the heat capacity can be reduced. As a result, the power consumption is reduced, the response to the gas concentration change is performed at high speed, and the measurement accuracy is further improved.

According to the fifth aspect of the present invention, by utilizing the ratio between the maximum value of the sensor output of the catalytic combustion type gas sensor 40 during the rising period and the steady state value at the steady state, the contact combustion type gas sensor detects gas leakage. The polar gas can be separated using the gas sensor 40. Further, a gas type separation filter or the like is not required. As a result, a compact, low-cost and high-performance gas sensor can be obtained.

According to the sixth aspect of the present invention, by utilizing the fact that the output ratio of the polar gas becomes stable when the energization interval is set in consideration of the saturation adsorption time of the polar gas, the gas leak detection is performed. It is possible to separate the polar gas using the contact combustion type gas sensor 40 which performs the following. As a result,
A low-cost and high-performance gas sensor can be obtained.

According to the seventh aspect of the present invention, in addition to the separation of the polar gas, the first polar gas having an output ratio of about 5 times regardless of the current supply interval among the polar gases; The second polar gas having an output ratio of about 10 to 13 times can be separated. Therefore, a gas sensor with higher performance and higher reliability can be obtained.

According to the present invention, the first polar gas generated due to ethanol and the second polar gas generated due to acetic acid can be separated. Since the gas generated due to acetic acid and ethanol is likely to be generated from alcohol and seasonings on a daily basis, it is possible to separate them, which means that a highly reliable gas sensor with few false alarms can be obtained. It turns out that.

According to the ninth aspect of the present invention, in the contact combustion type gas sensor 40, a heater element and a catalyst layer are formed on an insulating film supported on a silicon wafer, and further, the thin film diaphragm is etched from the back surface of the silicon wafer. Ds
Is formed, the heat capacity can be reduced. As a result, the power consumption is reduced, the response to the gas concentration change is performed at high speed, and the measurement accuracy is further improved.

According to the tenth aspect of the present invention, the ratio of the maximum value of the sensor output of the catalytic combustion type gas sensor 40 during the rising period to the steady state value at the steady state is utilized to detect the gas leakage. Gas sensor 40
Can be used to separate polar gases and smoke generated during a fire. Further, a gas type separation filter or the like is not required. As a result, a small-sized, low-cost and high-performance gas sensor can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a first embodiment of a gas sensor with a gas type separation function of the present invention.

FIGS. 2A and 2B are time charts showing examples of driving waveforms according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a determination criterion for separating gas types and a gas determination pattern according to the first embodiment of the present invention.

FIGS. 4A, 4B, and 4C are a plan view, a rear view, and a cross-sectional view taken along line AA of the contact combustion gas sensor, respectively.

FIG. 5 is a graph showing sensor output characteristics of a nonpolar gas by the present contact combustion type gas sensor.

FIG. 6 is a graph showing sensor output characteristics of a polar gas by the present catalytic combustion type gas sensor.

FIG. 7 is a flowchart illustrating a processing operation according to the first embodiment of the present invention.

FIG. 8 is a block diagram showing a basic configuration of a second embodiment of the gas sensor with a gas type separation function of the present invention.

FIG. 9 is a time chart illustrating an example of a driving waveform according to the second embodiment of the present invention.

FIG. 10 is a graph showing sensor outputs when the drive interval of the present catalytic combustion type gas sensor is changed.

FIG. 11 is a graph showing the output ratio of a plurality of gases when the gas concentration and the drive interval are changed.

FIG. 12 is a flowchart illustrating a processing operation according to the second embodiment of the present invention.

FIGS. 13A and 13B are respectively
It is an outline view of a sensitive element part and a compensating element part of a conventional catalytic combustion type gas sensor.

FIG. 14 is a graph showing a relationship between a gas concentration and a sensor output by a conventional catalytic combustion type gas sensor.

[Explanation of symbols]

10, 100 Controller 20 Drive power supply 30, 300 Gas detection output means 40 Contact combustion type gas sensor 42, 44 Pt heater 43 Pd / Al ₂ O ₃ catalyst layer 45 Al ₂ O ₃ catalyst layer Rs Sensitive element part Rr Compensation element part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G060 AA01 AB03 AB17 AB21 AB22 AE19 AF07 BA03 BD02 BD10 HC07 HC09 HC10 HD01 HD02 5C086 AA01 AA02 BA02 BA11 CA04 CB13 DA01 DA08 DA16 EA13 EA28 GA02 GA04

Claims (10)

[Claims] 1. The sensor output in a rising period from the start of energization of the catalytic combustion type gas sensor to a steady state at which the sensor output of the catalytic combustion type gas sensor becomes stable exhibits a peak waveform unique to a specific type of gas. A gas sensor with a gas type separation function, wherein the gas type is separated by utilizing the above. 2. The gas sensor according to claim 1, wherein a first rise period from the start of energization to a specific initial start time between the start of energization and the steady-state time,
A first gas having a peak waveform of the sensor output in a second rising period between the initial rising time and the steady time, and a second gas having a peak waveform of the sensor output only in the second rising period. A gas sensor with a gas type classification function for classifying a gas and a third gas whose sensor output monotonically increases in the rising period and outputting a classification result, wherein a peak waveform of the sensor output in the first rising period is First peak presence / absence detection means for detecting presence / absence; second peak presence / absence detection means for detecting presence / absence of a peak waveform of the sensor output during the second rising period; first peak presence / absence detection means; and second peak presence / absence The first gas, the second gas, and the third gas, based on each peak waveform detection result by the detection unit. A gas species separation means for separating the gas species separation function with a gas sensor which comprises a gas detection output means for outputting the fractional result of the gas species classification unit. 3. The gas sensor according to claim 2, wherein the first gas is a gas generated due to acetic acid.
The second gas is a gas generated due to ethanol, and the gas sensor with a gas type separation function. 4. The gas sensor according to claim 1, 2 or 3, wherein the contact combustion type gas sensor has a heater element and a catalyst layer formed on an insulating film supported on a silicon wafer. A gas sensor with a gas type separation function, wherein a thin film diaphragm is formed by etching from the back surface of the silicon wafer. 5. A method for detecting a gas leak and detecting a sensor output during a rising period from a start of energization of a contact combustion type gas sensor driven by intermittent energization to a steady state at which a sensor output of the contact combustion type gas sensor is stabilized. A gas sensor with a polar gas separation function for separating a polar gas using the sensor, wherein the sensor at the steady-state time and the maximum value of the sensor output during the rising period due to a change in an energization interval to the contact combustion type gas sensor A gas sensor with a function of separating a polar gas, wherein the polar gas is separated based on the degree of change in the ratio to a steady value that is an output value. 6. The gas sensor with a polar gas separation function according to claim 5, wherein the maximum value and the steady-state value of the sensor output at a first energization interval set based on the saturated adsorption time of the polar gas are determined. First sensor output obtaining means for obtaining the first sensor output;
Second sensor output acquisition means for acquiring the maximum value and the steady value of the sensor output by a second electricity supply interval longer than the electricity supply interval; and the maximum value and the steady value acquired by the first sensor output acquisition means A first output ratio calculating means for calculating the ratio according to the first output ratio, and a ratio based on the maximum value and the steady value acquired by the second sensor output acquiring means as a second output ratio. A second output ratio calculating means, based on a comparison between the first output ratio and the second output ratio,
A gas sensor with a polar gas separation function, comprising: a first separation unit that separates the polar gas; and a gas detection output unit that outputs a result of the separation by the first separation unit. 7. The gas sensor with a polar gas separation function according to claim 6, wherein the polar gas has a first polar gas whose output ratio is about 5 times regardless of the current supply interval, and A second polar gas having an output ratio of about 10 to 13 times regardless of an interval, wherein the first polar gas and the second polar gas are based on the first output ratio or the second output ratio. A gas sensor with a polar gas separation function, further comprising a second separation unit that separates from a polar gas, wherein the gas detection output unit also outputs a result of the separation by the second separation unit. 8. The gas sensor with a polar gas separation function according to claim 7, wherein the first energizing interval and the second energizing interval are about 10 seconds and about 30 seconds, respectively. A gas sensor having a function of separating a polar gas, wherein the gas is a gas generated from ethanol, and the second polar gas is a gas generated from acetic acid. 9. The gas sensor with a polar gas separation function according to claim 5, 6, 7, or 8, wherein the contact combustion type gas sensor has a heater element and a catalyst layer formed on an insulating film supported on a silicon wafer. And a thin film diaphragm formed by etching from the back surface of the silicon wafer. 10. A sensor for detecting a gas leak and detecting a sensor output during a rising period from a start of energization of a contact combustion type gas sensor driven intermittently to a steady state at which a sensor output of the contact combustion type gas sensor is stabilized. What is claimed is: 1. A gas sensor with a function of separating a polar gas and a smoke generated at the time of a fire by using a polar gas separating function, wherein a maximum value of the sensor output during the rising period is caused by a change in an energization interval to the contact combustion type gas sensor. And separating the polar gas and the smoke based on the degree of change in the ratio between the stationary gas and the stationary value that is the value of the sensor output at the steady time.