JP2002168819A - Gas detector and gas detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the identification of gas components generated in case of a fire and carbon monoxide generated on the occasion of incomplete combustion and a gas such as methane generated during the leakage of a city gas. SOLUTION: A heater drive circuit 5 generates and applies a pulse drive signal with the OFF operation time set longer enough than the ON operation time to a heater 2 to perform an ON drive or OFF drive of a gas sensor 1. As the OFF operation of the pulse drive signal is made longer enough, the sensor sensitivity grows rapidly to a lowered concentration of a gas generated in case of the fire. As a result, sensor output values from a sensor element 3 during the ON drive period of the gas sensor also increases as detected by a sensor output detection part 13. Thus, based on the sensor output values, a gas identification part 15 can easily identify gas components generated during the fire, carbon monoxide generated on the occasion of incomplete combustion and a gas such as methane generated during the leakage of the city gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the methane generated gas components in the low concentration generated during a fire, upon leakage other example incomplete carbon monoxide generated during combustion (CO) or city gas (CH ₄₎ Detects with higher sensitivity than gases such as
The present invention relates to a gas detection device and a gas detection method for distinguishing a gas generated during a fire from other gases.

[0002]

2. Description of the Related Art Conventionally, for example, a semiconductor gas sensor has been used as a gas sensor for distinguishing between carbon monoxide generated during incomplete combustion and methane generated when city gas leaks. Utilizing catalytic activity, it discriminates between carbon monoxide and methane. FIG. 12 shows gas sensitivity characteristics of a semiconductor gas sensor using a SnO ₂ catalyst.

In FIG. 12, the horizontal axis represents the element temperature of the sensor, and the vertical axis represents the sensor resistance. As can be seen from FIG. 12, the SnO ₂ catalyst has a property of high activity against carbon monoxide in a low temperature range and a high activity against methane in a high temperature range. In other words, since carbon monoxide has a low sensor resistance at low temperatures and methane has a low sensor resistance at high temperatures, semiconductor gas sensors have the characteristic of selecting carbon monoxide at low temperatures and selecting methane at high temperatures. .

For this reason, one gas sensor provided in the gas detecting device is driven by a pulse driving method as shown in FIG. 13 and a low temperature region (eg, 100 ° C.) and a high temperature region (eg, 400 ° C.).
C), the carbon monoxide gas concentration is detected at the CO detection point in the low temperature range (black circle in FIG. 13), and the methane detection point in the high temperature range (black circle in FIG. 13). (Mark), the methane gas concentration can be detected.

As a conventional gas detector of this type, there is known a gas leak detector described in, for example, Japanese Patent Application Laid-Open No. 59-143948.

As shown in FIG. 14, the gas leak detecting device disclosed in Japanese Patent Application Laid-Open No. Sho 59-143948 has a metal oxide sensitive body 102 whose resistance value decreases when it comes into contact with a flammable gas. A heater 103 for holding the sensitive body 102 at a predetermined temperature, a voltage discriminating circuit 106 for detecting a change in the resistance value of the sensitive body 101, and a heater voltage control circuit for varying a heater voltage of the heater 103 based on an output of the voltage discriminating circuit 106 105 and an arithmetic circuit 108 for detecting the temperature dependency based on a change in the resistance value of the sensitive body 101 and determining the type of combustible gas.

[0007] According to such a gas leak detection device, when the combustible gas comes into contact with the sensitive body 102 and the resistance value decreases, and the potential at the point A falls below the set reference potential, the voltage discrimination circuit 106 is activated. When activated, the timer circuit 107 is activated, and the voltage applied to the heater 103 is changed by the heater voltage control circuit 105.

The type of gas can be detected by calculating the potential before and after the voltage change of the heater 103 by the calculation circuit 108 and calculating the temperature dependency of the currently detected gas.

[0009]

However, in the conventional gas detecting device and the gas leak detecting device described in Japanese Patent Application Laid-Open No. Sho 59-143948, carbon monoxide and city gas generated during incomplete combustion are not known. Can be distinguished from methane generated at the time of leakage of gas, but could not be distinguished from gas generated at the time of fire and methane generated at the time of leakage of carbon monoxide and city gas generated at the time of incomplete combustion. In addition, at present, even gas components generated during a fire are not clearly understood.

Therefore, the present invention provides a gas which can easily distinguish gas components generated at the time of fire from other gases such as carbon monoxide generated at the time of incomplete combustion and methane generated at the time of leakage of city gas. It is an object to provide a detection device and a gas detection method.

[0011]

Means for Solving the Problems To solve the above problems, the present invention has the following arrangement. The gas detecting device according to the first aspect of the present invention includes a gas sensor provided with a heater and a sensor element for detecting gas, and a pulse driving signal in which an off time is set to be sufficiently longer than an on time to generate the pulse driving signal. Pulse driving means for turning on / off the gas sensor by applying pressure to the heater; sensor output detecting means for detecting a sensor output value from the sensor element during the on-driving period of the gas sensor; Gas identification means for identifying the type of the gas based on the sensor output value detected by the detection means.

According to the gas detecting device of the first aspect of the present invention,
The pulse drive means applies a pulse drive signal in which the off time is set to be sufficiently long with respect to the on time to the heater to drive the gas sensor on / off. However, if the off time of the pulse drive signal is sufficiently long, a fire may occur. The sensor sensitivity at a low concentration of the generated gas (acetic acid) sharply increases. For this reason, the sensor output value detected by the sensor output detection means also becomes large, and the gas discrimination means uses the gas output generated at the time of fire and other components such as carbon monoxide generated at the time of incomplete combustion based on the sensor output value. Gas such as methane generated at the time of leakage of city gas can be easily identified,
This makes it possible to detect a fire without being affected by gases such as carbon monoxide and methane.

According to a second aspect of the present invention, in the gas detecting device according to the first aspect, the gas identifying means includes: when the sensor output value is equal to or greater than a predetermined first threshold value.
The gas is determined to be a gas generated at the time of a fire.

According to the second aspect of the present invention, when the sensor output value is equal to or larger than the predetermined first threshold value, the gas identifying means can determine that the gas is a gas generated in a fire. .

According to a third aspect of the present invention, in the gas detection device according to the second aspect, the gas discriminating means is provided when the sensor output value is equal to or greater than a second threshold value smaller than the first threshold value. Is characterized in that the gas is determined to be a gas generated at the time of non-fire.

According to the third aspect of the present invention, when the sensor output value is equal to or more than the second threshold value smaller than the first threshold value, the gas identifying means converts the gas into a gas generated during a non-fire. Can be determined.

According to a fourth aspect of the present invention, there is provided the first to third aspects.
The gas detecting device according to any one of the above, further comprising a notifying unit for notifying the identification result of the type of gas identified by the gas identifying unit.

The notifying means according to the fourth aspect of the present invention notifies the identification result of the gas type identified by the gas identifying means.
The type of gas generated can be easily identified, thereby improving safety.

According to a fifth aspect of the present invention, in the gas detection method, a pulse drive signal in which an off time is set to be sufficiently longer than an on time is generated, and the pulse drive signal is applied to a heater provided in a gas sensor. A pulse driving step of driving the gas sensor on / off, a sensor output detecting step of detecting a sensor output value from a sensor element provided in the gas sensor during the on driving period of the gas sensor, And a gas identification step of identifying the type of the gas based on the above-mentioned gas. The same operation and effect as the operation and effect of the invention of claim 1 can be obtained.

According to a sixth aspect of the present invention, in the gas detecting method according to the fifth aspect, the gas identifying step includes detecting the gas when the sensor output value is equal to or greater than a predetermined first threshold value. The invention is characterized in that it is determined that the gas is generated at the time of a fire, and the same operation and effect as the operation and effect of the invention of claim 2 can be obtained.

According to a seventh aspect of the present invention, in the gas detection method according to the sixth aspect, the gas identifying step is performed when the sensor output value is equal to or greater than a second threshold value smaller than the first threshold value. Is characterized in that the gas is determined to be a gas generated at the time of non-fire, and the same operation and effect as the operation and effect of the invention of claim 3 can be obtained.

The invention according to claim 8 is the invention according to claims 5 to 7.
The gas detecting method according to any one of the preceding claims, further comprising a notifying step of notifying an identification result of the type of gas identified in the gas identifying step, which is the same as the operation and effect of the invention of claim 4. Functions and effects can be obtained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the gas detecting device and the gas detecting method according to the present invention will be described below in detail with reference to the drawings.

The gas detecting device and the gas detecting method according to the embodiment are capable of detecting low-concentration gas components generated during a fire,
For example, it detects gas with higher sensitivity than carbon monoxide generated during incomplete combustion or methane generated when city gas leaks, and distinguishes between gas generated during a fire and other gases such as carbon monoxide and methane. It is characterized by doing.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a circuit configuration diagram of the gas detection device according to the embodiment. FIG.
FIG. 3 is a detailed structural diagram of a gas sensor in the gas detection device according to the first embodiment. FIG. 3 is a timing chart of the temperature of the gas sensor in the gas detection device according to the first embodiment.

In the gas detection device shown in FIG. 1, the gas sensor 1 is, for example, a contact combustion type gas sensor. The contact combustion type gas sensor includes a gas detection element having a heater (hereinafter, referred to as a sensor element) and a heater. With the comparison element, the combustion heat generated when the gas is burned is detected, and the gas is identified based on the obtained sensor output.

This gas sensor 1 is, as shown in FIG.
An element is formed by applying an alumina-based catalyst 51 on a heater 2 having a platinum coil of 20 μm to 50 μm, and the element includes a sensor element 3 having the heater 2 and a comparison element 4 having the heater 2. .

The sensor element 3 uses γ-alumina carrying palladium (Pd) as a catalyst, and the comparison element 4
γ-alumina or α-alumina is used as a catalyst. The catalyst 51 generates heat according to the calorific value of the heater 2 and acts as a catalyst for gas combustion.

Further, the sensor element 3, the comparison element 4, and the resistor R
The bridge circuit 6 is constituted by 11 and the resistor R12.
Then, the voltage from the heater drive circuit 5 is applied to the bridge circuit 6.
, And output voltage V is taken out from terminal c and terminal d as a sensor output. That is, the bridge circuit 6 calculates a change in the resistance value of the sensor element 3 and a change in the resistance value of the comparison element 4 caused by combustion heat generated when the gas is combusted by the sensor element 3 and the comparison element 4. A central processing unit (CPU), which is detected from a connection point between the sensor element 3 and the comparison element 4 and output as a sensor output, will be described later.
11 is output.

The power supply circuit 7 supplies power to the timer drive circuit 8 and the heater drive circuit 5. Timer drive circuit 8
Receives a power supply from the power supply circuit 7 and drives a timer (not shown). The heater driving circuit 5 includes a timer driving circuit 8
A pulse drive signal is generated based on a timer signal from a timer driven by the timer, and the generated pulse drive signal is applied to the heater 2 to drive the gas sensor 1 on / off.

As shown in FIG. 3, the pulse drive signal is 1
It is a signal that repeats on / off in a 0 second cycle, with an on-time of 100 ms and an off-time of 9900 ms. Therefore, as shown in FIG. 3, the gas sensor 1 is turned off by a pulse drive signal to reduce the temperature (RT.degree.
(maintained only for 100 ms), and the gas sensor 1 is turned on to maintain a high temperature (400 ° C. is maintained for only 100 ms). The heater driving circuit 5 and the timer driving circuit 8
Constitute pulse driving means.

As shown in FIG. 1, the CPU 11 has a sensor output detecting section 1 as a sensor output detecting means.
3. It has a gas identification unit 15 as gas identification means.

The sensor output detector 13 detects that the sensor temperature is 4
Gas detection point DP (black circle in FIG. 3) during the period of 00 ° C. (period during which the pulse drive signal is on)
, A sensor output value is detected from the sensor element 3 of the gas sensor 1.

The gas discriminating unit 15 includes a sensor output detecting unit 13
If the sensor output value detected in step (1) is equal to or greater than a predetermined first threshold value SH1, it is determined that the identification target gas is a gas (acetic acid) generated at the time of fire.

The gas discriminating unit 15 determines that the sensor output value detected by the sensor output detecting unit 13 is equal to the first threshold value S.
If it is equal to or greater than a second predetermined threshold value SH2 smaller than H1, the identification target gas is determined to be a gas (such as CO or methane) generated during a non-fire.

The CPU 11 has an LED 21a which is turned on to identify a gas such as acetic acid generated in the event of a fire.
And an LED 21b which is lit to identify a gas such as carbon monoxide or methane at the time of non-fire. The speaker 19 notifies by sound that the gas is a fire gas or a non-fire gas. Speaker 19, LED 21
a, the LED 21b constitutes a notification unit.

Next, prior to the description of the operation of the gas detection device of the embodiment configured as described above, the reason why the gas detection device of the embodiment adopts the pulse driving method as shown in FIG. 3 will be described. This will be described with reference to FIGS.

First, the gas generated when the timber was smoked, that is, various gases generated at the time of fire of the timber was analyzed. FIG. 4 shows the results of gas analysis when the timber is smoked. Inorganic gas was measured by gas chromatography, and low-boiling compounds and high-boiling compounds were measured by gas chromatography and mass spectrometry. The quantitative analysis of formaldehyde and acetaldehyde is measured by liquid chromatography, and the quantitative analysis of acetic acid and formic acid is
It was measured by an ion chromatography method.

As can be seen from FIG. 4, carbon monoxide (gas concentration of 1120 ppm) and acetic acid (gas concentration of 840 pp) are the main components of various gases generated at the time of a timber fire.
m) was detected.

Next, various gas sensitivity characteristics of the gas sensor 1 when the gas sensor 1 of the embodiment is operated by the pulse driving method as shown in FIG. 3 and the off time is changed are shown in FIG.
9 to FIG.

FIG. 5 shows the CO concentration versus sensor output characteristics according to the ON / OFF cycle of the gas sensor. FIG. 6 shows the methane concentration versus sensor output characteristics according to the ON / OFF cycle of the gas sensor. FIG. 7 shows a hydrogen concentration versus sensor output characteristic according to the ON / OFF cycle of the gas sensor. FIG. 8 shows the isobutane concentration versus sensor output characteristics according to the ON / OFF cycle of the gas sensor.
FIG. 9 shows the acetic acid concentration versus the sensor output characteristics according to the ON / OFF cycle of the gas sensor.

In the examples shown in FIGS. 5 to 9, the sensor output with respect to the gas concentration when the on-time is constant for 100 msec except for continuous energization and the off-time is 1, 5, 10, and 30 seconds. Is represented. The sensor output (mV) shown here is obtained by amplifying the sensor output obtained from the sensor element by 50 times.

As shown in FIGS. 5 to 8, for general gas species such as CO, methane, hydrogen and isobutane, the sensitivity basically decreases as the off-time becomes longer. on the other hand,
As shown in FIG. 9, in the case of acetic acid gas, as the off-time becomes longer, the sensitivity particularly at a low concentration sharply increases.

This is because acetic acid has a high adsorptivity, and the acetic acid adsorbed on the surface of the catalyst layer 45 when turned off instantaneously burns and reacts when turned on. It is considered that the longer the off-time, the more the amount of acetic acid adsorbed increases, giving an effect of amplifying the sensitivity. In addition, it can be seen from the fact that, in the case of CO, which has a relatively high adsorptivity even in gas, the on / off driving shows a somewhat higher sensitivity than the continuous energization.

For this reason, the acetic acid generated at the time of fire can be detected without being affected by other gases such as CO and methane by setting the off time to 5 seconds or more, for example, in a pulse drive system as shown in FIG. Then, a fire can be determined.

Next, the operation of the gas detecting apparatus of the embodiment configured as described above, that is, the gas detecting method will be described with reference to the timing chart shown in FIG. 3 and the flowchart shown in FIG.

First, a first threshold value and a second threshold value smaller than the first threshold value are set (step S10).
1) Next, the heater drive circuit 5 generates a pulse drive signal as shown in FIG. 3 (step S103), and this pulse drive signal is applied to the heater 2 in the bridge circuit 6.

That is, the heater 2 is controlled by the pulse drive signal.
Is turned on / off, and as shown in FIG. 3, the gas sensor 1 is turned off at a low temperature (RT.degree.
Only for a period of time), and the temperature becomes high by ON drive (400 ° C. is maintained for only 100 ms) (step S105).

Next, the sensor output detector 13 detects the gas detection point DP during the period when the sensor temperature reaches 400 ° C.
At (black circles in FIG. 3), a sensor output value is detected from the sensor element 3 of the gas sensor 1, and the detected sensor output value is converted to an analog / digital converter (A / D) (not shown).
A / D conversion is performed to obtain a voltage value V (step S107).

Next, the gas discriminating unit 15 determines whether or not the obtained voltage value V is equal to or higher than the first threshold value (step S109), and the voltage value V is equal to or higher than the first threshold value. In this case, the identification target gas is determined to be a gas such as acetic acid generated at the time of fire (step S111).

In this case, since the LED 21a is turned on by the fire alarm signal from the CPU 11 to give a fire alarm (step S113), it is possible to easily identify that the gas to be identified is a gas such as acetic acid generated at the time of fire. it can. Further, the speaker 19 can notify that the gas to be identified is a gas at the time of fire.

On the other hand, if the obtained voltage value V is less than the first threshold value in step S109, it is determined whether or not the obtained voltage value V is not less than the second threshold value ( If the voltage value V is equal to or greater than the second threshold value (step S115), the gas identification unit 15 determines that the identification target gas is a gas generated during a non-fire (step S117).

In this case, since the LED 21b is turned on by the alarm signal from the CPU 11, it is possible to easily identify that the gas to be identified is a gas such as carbon monoxide or methane generated during a non-fire. Further, the speaker 19 can notify that the gas to be identified is a non-fire gas.

As described above, according to the gas detection device of the first embodiment, the pulse drive signal whose off time is set to be sufficiently longer than the on time is applied to the heater 2 to turn on / off the gas sensor 1. When the pulse is driven off, if the off time of the pulse drive signal is sufficiently long, the sensor sensitivity when the concentration of the gas generated at the time of fire is low rapidly increases. For this reason, the detected sensor output value also increases, and based on the sensor output value, gas components generated at the time of fire and other gases such as carbon monoxide generated at the time of incomplete combustion and methane generated at the time of leakage of city gas. Can be easily distinguished, whereby a fire can be detected without being affected by gases such as carbon monoxide and methane.

Further, the fact is described to the speaker 19 and the LED 21.
Since the notification is made by a and 21b, the type of gas can be easily identified, and safety can be improved.

Further, since one gas sensor 1 can easily distinguish a gas such as acetic acid gas generated at the time of a wood fire from other gases such as carbon monoxide gas and methane, the fire sensor and the like can be used. There ’s no need to
An inexpensive gas detection device can be provided.

(Second Embodiment) Next, a gas detector according to a second embodiment will be described. A feature of the gas detection device according to the second embodiment is that a micro gas sensor is used as a gas sensor. The other configuration of the gas detection device other than the gas sensor is the same as the configuration shown in FIG.

FIG. 11 is a detailed structural view of a gas sensor in the gas detector according to the second embodiment. FIG.
FIG. 11A is a sectional view of the gas sensor 1, and FIG. 11B is a top view of the gas sensor. The gas sensor 1 includes a microsensor, a heater 2 made of platinum (Pt) for heating a catalyst, a sensor element 3 for detecting various gases, and a comparison element 4.
, And the sensor element 3 and the comparison element 4 detect gas.

A substrate 33 made of silicon single crystal is provided on the sensor pedestal 31, and a diaphragm 35 is formed on the substrate 33. This diaphragm 35
Is formed by anisotropically etching the substrate 33.

Each of the sensor element 3 and the comparison element 4 is provided on a substrate 33, and in contact with the diaphragm 35, an oxide film 37 made of a SiO ₂ film and an Si ₃ N ₄ film laminated on the diaphragm 35. 39 are stacked.

Each of the sensor element 3 and the comparison element 4 has a heater 2. The heater 2 of the sensor element 3 is connected to the electrodes 41a and 41b.
Each of the electrodes 41a to 41d is connected to the electrodes 41c and 41d.
41d is fixed by wire bonding of gold (gold wire 43).

The sensor element 3 includes a heater 2 and a palladium (Pd) layer 5-5 wt% laminated on the heater 2.
And a catalyst layer 45 using the carried γ-alumina as a catalyst. The comparison element 4 includes the heater 2 and a catalyst layer (not shown) laminated on the heater 2 and using γ-alumina or α-alumina as a catalyst. The heater 2 promotes gas combustion, and the catalyst layer 45
Generates heat in accordance with the amount of heat generated by the heater 2 and acts as a catalyst for gas combustion.

Even if the microsensor having the above configuration is used,
The same effects as those of the gas detection device according to the first embodiment can be obtained.

The present invention is not limited to the gas detector of the above-described embodiment. In the embodiment,
Although the ON time is fixed at 100 ms, the ON time may be, for example, 1 second, and the OFF time may be, for example, 30 seconds.

[0065]

According to the gas detecting apparatus of the first aspect and the gas detecting method of the fifth aspect of the present invention, a pulse drive signal in which the off time is set to be sufficiently longer than the on time is applied to the heater. When the gas sensor is turned on and off, if the off time of the pulse drive signal is sufficiently long, the sensor sensitivity at the time of low concentration of gas generated at the time of fire increases sharply. For this reason, the detected sensor output value also increases,
Based on the sensor output value, gas components generated at the time of fire and other gases such as methane generated at the time of leakage of city gas and carbon monoxide generated at the time of incomplete combustion can be easily distinguished. A fire can be detected without being affected by gases such as carbon monoxide and methane.

The gas detector according to the second aspect of the present invention, the sixth aspect of the present invention.
According to the gas detection method of the present invention, when the sensor output value is equal to or larger than the predetermined first threshold value, it is possible to determine that the gas is a gas generated at the time of fire.

The gas detector according to the third aspect of the present invention, the seventh aspect of the present invention.
According to the gas detection method of the invention, when the sensor output value is equal to or more than the second threshold value smaller than the first threshold value,
The gas can be determined as a gas generated at the time of non-fire.

The gas detector according to the invention of claim 4 and claim 8.
According to the gas detection method of the present invention, since the identification result of the type of gas is reported, the type of generated gas can be easily identified, thereby improving safety.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a gas detection device according to a first embodiment of the present invention.

FIG. 2 is a detailed structural diagram of a gas sensor in the gas detection device according to the first embodiment.

FIG. 3 is a timing chart of a temperature of a gas sensor in the gas detection device according to the first embodiment.

FIG. 4 is a diagram showing a gas analysis result when wood is smoked.

FIG. 5 is a diagram showing a CO concentration vs. sensor output characteristic according to an ON / OFF cycle of a gas sensor.

FIG. 6 is a diagram showing methane concentration versus sensor output characteristics according to the on / off cycle of the gas sensor.

FIG. 7 is a diagram showing a hydrogen concentration versus sensor output characteristic according to an on / off cycle of a gas sensor.

FIG. 8 is a graph showing isobutane concentration versus sensor output characteristics according to the ON / OFF cycle of the gas sensor.

FIG. 9 is a diagram showing acetic acid concentration versus sensor output characteristics according to the ON / OFF cycle of the gas sensor.

FIG. 10 is a flowchart illustrating a gas detection method realized by the gas detection device according to the first embodiment.

FIG. 11 is a detailed structural diagram of a gas sensor in the gas detection device according to the second embodiment.

FIG. 12 is a view showing gas sensitivity characteristics of a conventional semiconductor gas sensor using a catalyst.

FIG. 13 is a timing chart of a temperature of a gas sensor in a conventional gas detection device.

FIG. 14 is a configuration block diagram of a conventional gas leak detection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Gas sensor 2 Heater 3 Sensor element 4 Comparison element 5 Heater drive circuit 6 Bridge circuit 7 Power supply circuit 8 Timer drive circuit 11 CPU 13 Sensor output detection part 15 Gas identification part 19 Speaker 21a, 21b LED 31 Sensor pedestal 33 Substrate 35 Diaphragm 37 Oxidation Film 39 Si ₃ N ₄ film 41 Electrode 43 Gold wire 45 Catalyst layer 47 Wire mesh 51 Catalyst DP Gas detection point

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G046 AA11 AA19 BA01 BA04 BB02 BE02 BF05 BH06 BJ10 DA05 DB05 DC12 DC14 DC16 DC17 DC18 2G060 AA01 AB08 AB17 AE19 AF04 AG01 BA03 BB02 BB09 BB15 BD06 5C085 AA02 CA16 CA17 DA07 DA11 DA16 EA11 EA27 EA31 EA38 EA55

Claims (8)

[Claims] 1. A gas sensor provided with a heater and a sensor element for detecting gas, and a pulse drive signal in which an off time is set to be sufficiently longer than an on time, and the pulse drive signal is applied to the heater. Pulse driving means for turning on / off the gas sensor; sensor output detecting means for detecting a sensor output value from the sensor element during the on-driving period of the gas sensor; A gas identification unit that identifies a type of the gas based on a sensor output value. 2. The apparatus according to claim 1, wherein said gas discriminating means determines that said gas is a gas generated at the time of a fire when said sensor output value is equal to or greater than a predetermined first threshold value. 2. The gas detection device according to 1. 3. When the sensor output value is equal to or greater than a second threshold value smaller than the first threshold value, the gas identification unit determines that the gas is a gas generated during a non-fire. The gas detection device according to claim 2, wherein: 4. The gas detecting device according to claim 1, further comprising a notifying unit for notifying the identification result of the type of the gas identified by said gas identifying unit. 5. A pulse for generating a pulse drive signal in which the off time is set to be sufficiently longer than the on time and applying the pulse drive signal to a heater provided in the gas sensor to drive the gas sensor on / off. A driving step; a sensor output detecting step of detecting a sensor output value from a sensor element provided in the gas sensor during the ON driving period of the gas sensor; and a gas for identifying a type of the gas based on the detected sensor output value. A gas detection method, comprising: an identification step. 6. The gas identifying step determines that the gas is a gas generated at the time of a fire when the sensor output value is equal to or greater than a predetermined first threshold value. 6. The gas detection method according to 5. 7. The gas identifying step determines that the gas is a non-fire gas when the sensor output value is equal to or greater than a second threshold value smaller than the first threshold value. The gas detection method according to claim 6, wherein: 8. The gas detecting method according to claim 5, further comprising a notifying step of notifying the identification result of the gas type identified in the gas identifying step.