JPS58174839A - Method of detecting particular gas - Google Patents
Method of detecting particular gasInfo
- Publication number
- JPS58174839A JPS58174839A JP3620983A JP3620983A JPS58174839A JP S58174839 A JPS58174839 A JP S58174839A JP 3620983 A JP3620983 A JP 3620983A JP 3620983 A JP3620983 A JP 3620983A JP S58174839 A JPS58174839 A JP S58174839A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- metal oxide
- temperature
- heater
- detector element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 6
- 239000004065 semiconductor Substances 0.000 claims abstract description 22
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 19
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 18
- 239000007789 gas Substances 0.000 claims description 76
- 238000001514 detection method Methods 0.000 claims description 38
- 230000002452 interceptive effect Effects 0.000 claims description 17
- 238000007084 catalytic combustion reaction Methods 0.000 claims description 16
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 26
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 12
- 239000001282 iso-butane Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- -1 5n02 Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910001252 Pd alloy Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
- G01N27/122—Circuits particularly adapted therefor, e.g. linearising circuits
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
【発明の詳細な説明】
この発明は、金属酸化物半導体の電気伝導度の変化を利
用したガス検出方法に関し、さらに詳細にはＣＯやメタ
ン等の被検ガスを水素やイソブタン等の妨害ガスと区別
して選択的に検出するよう番こしたガス検出方法に関す
る。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas detection method that utilizes changes in electrical conductivity of metal oxide semiconductors, and more specifically to a method for detecting gases such as CO or methane by interfering with interfering gases such as hydrogen or isobutane. The present invention relates to a gas detection method designed to distinguish and selectively detect gases.
５ｎ０２ 、 ＺｎＯ、Ｎｉ Ｏ等の金属酸化物半導体
の電気伝導度の変化からガスを検出する方法は広く用い
られている。しかしこの方法についての従来の検討は半
導体の電気伝導度の変化に集中し、ガスの接触燃焼によ
る温度変化についてはほとんど研究されていない。例え
ば特開昭４７〜３２８９７号は、金属酸化物半導体の温
度変化からガスを検出しているが、この温度変化は半導
体の電気伝導度の変化を自己発熱の変化による温度変化
としてとらえるもので、接触燃焼によるものではない。A method of detecting gas from changes in electrical conductivity of metal oxide semiconductors such as 5n02, ZnO, NiO, etc. is widely used. However, conventional studies on this method have focused on changes in the electrical conductivity of semiconductors, and there has been little research on changes in temperature due to catalytic combustion of gases. For example, JP-A-47-32897 detects gas from temperature changes in metal oxide semiconductors, but this temperature change is interpreted as a change in the electrical conductivity of the semiconductor due to a change in self-heating. This is not due to catalytic combustion.
この発明は、ガス検出素子での接触燃焼による温度変化
を利用して、ＣＯやメタン等のガスへの選択性を得るこ
とを目的とする。This invention aims to obtain selectivity to gases such as CO and methane by utilizing temperature changes caused by catalytic combustion in a gas detection element.
この発明の特定ガス検出方法は、金属酸化物半導体の電
気伝導度の変化から各種ガスを非選択的に検出し、ガス
により接触燃焼速度が異なることに着目して、妨害ガス
の接触燃焼をこよる温度上昇をヒータ兼用の測温抵抗体
によって検出して妨害カスの影響を除き、特定のガスの
みを検出するようにしたものである。The specific gas detection method of the present invention non-selectively detects various gases based on changes in the electrical conductivity of metal oxide semiconductors, and focuses on the fact that catalytic combustion speeds differ depending on the gas, thereby detecting catalytic combustion of interfering gases. This system detects the temperature rise caused by this using a resistance temperature detector that also serves as a heater, eliminates the influence of interfering scum, and detects only a specific gas.
第１図（ａ）のガス検出素子（２ａ）は、５ｎ０２．Ｚ
ｎ’０等のガス敏感性金属酸化物半導体（４ａ）にコイ
ル状の電極（６ａ）、 （８ａ）を埋設したものであ
る。The gas detection element (2a) in FIG. 1(a) is 5n02. Z
Coiled electrodes (6a) and (8a) are embedded in a gas-sensitive metal oxide semiconductor (4a) such as n'0.
電極（６ａ ） 、 （８ａ ）はｐｔやＩ−Ｆ！、
等の貴金属、あるいはＩｒ−Ｐｄ合金等で構成し、その
一方あるいは 、双方をヒータ兼用の測温抵抗体とし
て兼用する。Electrodes (6a) and (8a) are PT and I-F! ,
or an Ir-Pd alloy, and one or both of them are used as a temperature sensing resistor that also serves as a heater.
また金属酸化物半導体（４ａ）には、必要に応じて第１
図（ｂ）に、金属酸化物半導体（４ｂ）に埋設した中心
電極（８ｂ）の周囲をコイル状電極（６ｂ）で囲ったガ
ス検出素子（２ｂ）の例を示す。そしてコイル状電極（
６ｂ）をヒータ兼用の測温抵抗体として用いる。In addition, the metal oxide semiconductor (4a) may include a first
Figure (b) shows an example of a gas detection element (2b) in which a center electrode (8b) embedded in a metal oxide semiconductor (4b) is surrounded by a coiled electrode (6b). and a coiled electrode (
6b) is used as a resistance temperature detector that also serves as a heater.
第１図（ｃ）に、アルミナ等の絶縁パイプ（ｌＯ）にヒ
ータ兼用の測温抵抗体（＋２１を収容し、パイプ（ｌＯ
）の表面に一対の電極（６ｃ ） 、 （８ｃ ）と
金属酸化物半導体（４ｃ）を設けたガス検出素子（２Ｃ
）を示す。In Fig. 1(c), a resistance temperature detector (+21) which also serves as a heater is housed in an insulated pipe (lO) made of alumina, etc.
) A gas detection element (2C) with a pair of electrodes (6c), (8c) and a metal oxide semiconductor (4c) provided on the surface of the gas detection element (2C)
) is shown.
なおここで電極（６ｂ）、 （６ｃ）、 （８ｂ）
、 （８ｃ）は第１図（ａ）の場合と同様に、高温で安
定で金属酸化物半導体（４ｂ ） 、 （４ｃ ）に
悪影響を与えない貴金属系のものを用い、金属酸化物半
導体（４ｂ）。Note that here the electrodes (6b), (6c), (8b)
, (8c), as in the case of Fig. 1(a), uses a noble metal-based material that is stable at high temperatures and does not have an adverse effect on the metal oxide semiconductors (4b) and (4c). ).
（４ｃ）としては５ｎ０２やＺｎＯ等のガス敏感性のも
のを用いる。また測温抵抗体にヒータをも兼用させたの
は、測温抵抗体の抵抗値が一般に小さいため発熱体とし
て用いるのが自然であること、および部品点数を小さく
すること、のためである。As (4c), a gas-sensitive material such as 5n02 or ZnO is used. The reason why the resistance temperature detector is also used as a heater is because the resistance value of the resistance temperature detector is generally small, so it is natural to use it as a heating element, and to reduce the number of parts.
「ガス検出素子の特性」
第１図（ａ）のガス検出素子（２ａ）において、Ｓｎ
０２に１ｗｔ％のＰｄを加えた金属酸化物半導体（４ａ
）と白金コイルからなる電極（６ａ）、 （８ａ）を
用いた際の特性を第２図（ａ）、 （ｂ）に示す。第２
図（ａ）はガス中での素子（２ａ）の温度と電気伝導度
の関係を示す。また第２図（ｂ）はガス中での温度と測
温抵抗体兼用電極（６ａ）の抵抗変化率との関係を示す
。"Characteristics of gas detection element" In the gas detection element (2a) in Fig. 1(a), Sn
Metal oxide semiconductor (4a
) and platinum coil electrodes (6a) and (8a) are shown in FIGS. 2(a) and 2(b). Second
Figure (a) shows the relationship between the temperature and electrical conductivity of the element (2a) in gas. Further, FIG. 2(b) shows the relationship between the temperature in the gas and the rate of change in resistance of the electrode (6a) which also serves as a resistance temperature detector.
なお測温抵抗体（６ａ）の温度変化は一般にガス濃度に
比例する。被検ガスを代表するものとして００２００ｐ
ｐｍ（実線ａ−１，ｂ−１）とメタン２０００ｐｐｍ（
実線ａ−３，ｂ−３）を、ＣＯに対する妨害ガスとして
Ｈ２５００ｐｐｍ（破線ａ −２、ｂ−２）を、メタン
に対する妨害ガスとしてイソブタン２０００ｐｐｍ（破
線ａ−４，ｂ−４）を、用いる。Note that the temperature change of the resistance temperature detector (6a) is generally proportional to the gas concentration. 00200p as representative of the test gas
pm (solid lines a-1, b-1) and methane 2000 ppm (
Solid lines a-3, b-3) are used, H2500ppm (dashed lines a-2, b-2) is used as an interfering gas for CO, and isobutane 2000 ppm (dashed lines a-4, b-4) is used as an interfering gas for methane.
ＣＯの検出について検討すると、ＣＯ中での電気伝導度
はＨ２中での値と酷似し、電気伝導度からＣＯを選択的
に検出することは難しい。これに対して金属酸化物半導
体（４ａ）や、電極（６ａ）。When considering the detection of CO, the electrical conductivity in CO is very similar to the value in H2, and it is difficult to selectively detect CO from the electrical conductivity. On the other hand, a metal oxide semiconductor (4a) and an electrode (6a).
（８ａ）での接触酸化による素子（２ａ）の温度変化は
、ＣＯとＨ２とに対して異る挙動を示す。ＣＯへの着火
温度２００°Ｃ弱で、Ｈ２への着火温度（約１００°Ｃ
）よりも高い。２００°Ｃでの測温抵抗体兼用電極（６
ａ）の抵抗変化率は、ＣＣ０２００ｐｐに対して約０２
５％、Ｈ２５００ｐｐｍに対して１．５％以上となり、
Ｈ２に対して大きな抵抗変化率が得られる。Ｈ２の接触
燃焼量がＣＯの接触燃焼量に比べて大きい理由として、
分子量の差による拡散速度の差の寄与が考えられるもの
の、その詳細は不明である。なお特に限定するものでは
ないが、ガス検出素子（２ａ）の加熱温度は、ＣＯ！こ
対しては、１５０〜３５０℃が好ましい。これ以下の温
度ではＨ２への接触酸化が遅いためＨ２とＣＯの区別が
難しく、これ以上の温度ではＣＯへの電気伝導度の変化
が小さくなってしまうからである。The temperature change in element (2a) due to catalytic oxidation in (8a) shows different behavior for CO and H2. The ignition temperature for CO is just under 200°C, and the ignition temperature for H2 (approximately 100°C)
) higher than Electrode that also serves as a resistance temperature detector at 200°C (6
The resistance change rate of a) is about 02 for CC0200pp.
5%, 1.5% or more for H2500ppm,
A large resistance change rate with respect to H2 can be obtained. The reason why the amount of catalytic combustion of H2 is larger than that of CO is because
Although it is thought that the difference in diffusion rate due to the difference in molecular weight contributes, the details are unknown. Although not particularly limited, the heating temperature of the gas detection element (2a) is CO! In contrast, the temperature is preferably 150 to 350°C. This is because at temperatures below this, catalytic oxidation to H2 is slow, making it difficult to distinguish between H2 and CO, and at temperatures above this, the change in electrical conductivity to CO becomes small.
次にメタンをイソブタンと区別して検出する場合につい
て検討する。この場合も電気伝導度の変化から両者を区
別することは難しい。これに対して接触燃焼による温度
変化はメタンとイソブタンとで大きく異なる。メタンの
着火点は５００℃弱と高く、接触燃焼による温度変化も
小さい。これに対してイソブタンの接触燃焼による温度
変化は、３００℃で既に十分大きく、かつどの温度でも
メタンよりも大きい。なおメタン検出の際のガス検出素
子（２ａ）の温度としては、３５０〜５００°Ｃが好ま
しい。より低温ではメタンへの電気伝導度の変化が小さ
く、より高温ではガス検出素子（２ａ）の熱的劣化が著
しいためである。Next, we will consider the case where methane is detected separately from isobutane. In this case as well, it is difficult to distinguish between the two based on changes in electrical conductivity. On the other hand, the temperature change due to catalytic combustion differs greatly between methane and isobutane. The ignition point of methane is high at just under 500°C, and the temperature change due to catalytic combustion is small. On the other hand, the temperature change due to catalytic combustion of isobutane is already sufficiently large at 300° C. and larger than that of methane at any temperature. Note that the temperature of the gas detection element (2a) during methane detection is preferably 350 to 500°C. This is because the change in electrical conductivity to methane is small at lower temperatures, and the thermal deterioration of the gas detection element (2a) is significant at higher temperatures.
第２図（ａ）、 （ｂ）の結果を整理すると以下の様に
なる。The results in Figures 2 (a) and (b) are organized as follows.
■ ガス検出素子（２ａ）の電気伝導度の変化からは、
ガスを選択的に検出することができない。■ From the change in electrical conductivity of the gas detection element (2a),
Gas cannot be selectively detected.
■ 接触燃焼による温度変化は、ＣＯやメタン等のガス
（被検ガス）に対して小さく、Ｈ２やイソブタン等のガ
ス（妨害ガス）に対して大きい。従って素子（２ａ）の
温度変化は妨害ガス濃度を示すものと考えることができ
る。■ The temperature change due to catalytic combustion is small for gases such as CO and methane (test gases), and large for gases such as H2 and isobutane (obstruction gases). Therefore, the temperature change of the element (2a) can be considered to indicate the interfering gas concentration.
■ 電気伝導度による検出結果を温度変化による検出結
果で補償すれば、特定のガスのみを検出することができ
る。■ By compensating the detection results based on electrical conductivity with the detection results based on temperature changes, it is possible to detect only specific gases.
なおここでは、特定の材料・構造のガス検出素子（２ａ
）について特性を説明したが、他のガス検出素子（２ｂ
Ｌ （２ｃ）でもほぼ同様の結果が得られた。またこ
こではＣＯとメタンの２種類のガスを被検ガスとして検
討したが、他のガスであっても接触燃焼による温度変化
が妨害ガスに対して大きく被検ガスに対して小さいもの
であれば、同様に検出し得ることは言うまでもない。Here, a gas detection element (2a) made of a specific material and structure is used.
), but other gas detection elements (2b
Almost similar results were obtained with L (2c). In addition, here we considered two types of gases, CO and methane, as test gases, but even with other gases, if the temperature change due to catalytic combustion is larger than the interfering gas and smaller than the test gas, then , it goes without saying that it can be detected in the same way.
「検出回路例」
被検ガスあるいは妨害ガスの一方のみが存在し、両者の
共存がない場合に用いる検出回路例を第３図に示す。ガ
ス検出素子（２ａ）の両電極に検出用電源（四と負１荷
抵抗（２４）とを直列に接続する。この発明では、ガス
検出素子（２ａ）の温度変化を出力として利用するので
、検出用電源（２′４による自己発熱をできる限り小さ
く、例えば好ましくは２０ｍｗａｔｔ以下で多くとも５
０ｍｗａｔｔ以下に、する。ガス検出素子（２ａ）のヒ
ータ兼用の測温抵抗体（６ａ）に直列に温度検出抵抗（
２６）を接続し、抵抗ｔ２８）、（３ｆ））とともにブ
リッジ回路を構成させ、ヒータ用電源（３２）から電力
を供給する。ここでブリッジ回路を用いるのはヒータ用
電源（３４の電源電圧変動の影響を補償するためである
。また周囲温度の変動等の影響を補償するためには、温
度検出抵抗（淘あるいは抵抗しくへ）の抵抗温度係数及
び放熱係数をガス検出素子（２ａ）のヒータ兼用の測温
抵抗体（６ａ）と一致させれば良い。そのためｌとは、
例えばヒータ兼用の測温抵抗体（６ａ）と抵抗値と抵抗
温度係数が等しいコイルをアルミナやシリカ等の無機耐
火質で放熱係数が等しくなるように覆って抵抗ｉｎ 、
Ｑｌｌｌ）として用いれば良い。"Example of Detection Circuit" FIG. 3 shows an example of a detection circuit used when only one of the test gas or the interfering gas is present and the two do not coexist. A detection power source (4) and a load resistor (24) are connected in series to both electrodes of the gas detection element (2a).In this invention, since the temperature change of the gas detection element (2a) is used as an output, Detection power supply (2'4) Minimize self-heating by as much as possible, for example, preferably 20 mwatt or less and at most 5
Keep it below 0mwatt. A temperature detection resistance (
26) to form a bridge circuit together with resistors t28) and (3f)), and power is supplied from the heater power source (32). The purpose of using a bridge circuit here is to compensate for the influence of power supply voltage fluctuations on the heater power supply (34).Also, in order to compensate for the influence of ambient temperature fluctuations, a temperature detection resistor (selected or ) should match the resistance temperature coefficient and heat radiation coefficient of the temperature measuring resistor (6a) which also serves as a heater of the gas detection element (2a).Therefore, l is
For example, a resistance thermometer (6a) that also serves as a heater and a coil whose resistance value and temperature coefficient of resistance are the same are covered with an inorganic refractory material such as alumina or silica so that the heat dissipation coefficients are equal,
Qllll).
負荷抵抗（２４）への電圧を第１のスイッチング回路（
３４）に入力し、ガスの有無あるいはその濃度を非選択
的に検出し、許容濃度以上のガスがある場合に信号を発
するようにする。ブリッジ回路の出力を増幅器（３６）
により増幅し、第２のスイッチング回路（３８）に入力
する。第２のスイッチング回路（３８）では、接触燃焼
による素子（２ａ）の温度上昇が所定値以下の場合にの
み信号を発するようにする。第１および第２のスイッチ
ング回路＋３４Ｌ （３８）の出力をアンド回路（４０
）に入力し、素子（２ａ）の電気伝導度の変化が所定値
以上で接触燃焼による温度上昇が所定値以下の場合にブ
ザー（４匈を作動させて報知を行う。The voltage to the load resistor (24) is changed to the first switching circuit (
34), the presence or absence of gas or its concentration is detected non-selectively, and a signal is generated when there is a gas exceeding the allowable concentration. Amplify the output of the bridge circuit (36)
The signal is amplified and input to the second switching circuit (38). The second switching circuit (38) is configured to issue a signal only when the temperature rise of the element (2a) due to catalytic combustion is below a predetermined value. The outputs of the first and second switching circuits +34L (38) are connected to the AND circuit (40
), and when the change in electrical conductivity of the element (2a) is above a predetermined value and the temperature rise due to catalytic combustion is below a predetermined value, a buzzer (4 horns) is activated to notify.
なおブザー（４２）に代えてメータ等を用いる場合には
、ヒータ兼用の測温抵抗体（６ａ）の温度変化により作
動するスイッチング回路を介して、負荷抵抗（２４）へ
の出力を、直接または増幅してメータ等に加えるように
すれば良い。In addition, when using a meter etc. in place of the buzzer (42), the output to the load resistor (24) can be directly or All you have to do is amplify it and add it to a meter, etc.
次に被検ガスと妨害ガスの共存が生じ得る場合の検出回
路例について説明する。この場合量も簡単には、第３図
の回路において第２のスイッチング回路（晒のスイッチ
ングレベルを負荷抵抗（２４）への電圧により変化させ
、高濃度のガス中では接触燃焼による温度上昇への許容
幅を大きくしてやれば良い。Next, an example of a detection circuit in a case where the coexistence of the test gas and the interfering gas may occur will be described. In this case, the quantity can be easily explained by changing the switching level of the second switching circuit (blanking) by the voltage applied to the load resistor (24) in the circuit shown in Fig. It would be better to increase the tolerance range.
被検ガスと妨害カスが共存し得る場合のさらに精密な回
路例を第４図に示す。検出用電源（２２）からの電流を
演算増幅器（４４）により取り出し、べき東回路（４６
）によりべき乗する。FIG. 4 shows a more precise example of the circuit in the case where the gas to be detected and the interfering debris can coexist. The current from the detection power supply (22) is taken out by the operational amplifier (44), and the power east circuit (46
).
一般に金属酸化物半導体（４ａ）の電気伝導度はガス濃
度の０．５〜０．９乗に比例するので、べき乗によりガ
ス濃度にほぼ比例した出力を得る。ヒータ兼用の測温抵
抗体（６ａ）の温度変化は妨害ガス濃度に比例する。差
動増幅器（ト）により、べき東回路（４６）の出力から
増幅器（３Ｇ）の出力を除き、被検ガス濃度に比例した
出力を得、これをメーターに加える。Generally, the electrical conductivity of the metal oxide semiconductor (4a) is proportional to the 0.5 to 0.9 power of the gas concentration, so an output approximately proportional to the gas concentration is obtained by exponentiation. The temperature change of the temperature measuring resistor (6a) which also serves as a heater is proportional to the interfering gas concentration. A differential amplifier (G) removes the output of the amplifier (3G) from the output of the power east circuit (46) to obtain an output proportional to the gas concentration to be detected, which is added to the meter.
検出回路の設計にあたって重要なことは、金属酸化物半
導体（４ａ）の電気伝導度は被検ガスと妨害カスの双方
に対応し接触燃焼による温度変化は妨害ガス濃度に比例
することである。温度変化による信号を用いて妨害ガス
の影響を補償する具体的回路は、補償回路についての技
術常識に沿って変形し得るものであり、個別の用途やガ
ス検出素子（２ａ）等の特性に応じて決定すべきもので
ある。What is important in designing the detection circuit is that the electrical conductivity of the metal oxide semiconductor (4a) corresponds to both the test gas and the interfering gas, and the temperature change due to catalytic combustion is proportional to the interfering gas concentration. The specific circuit that compensates for the influence of interfering gas using a signal caused by temperature change can be modified in accordance with common technical knowledge regarding compensation circuits, and may vary depending on the individual application and the characteristics of the gas detection element (2a), etc. The decision should be made based on the
以」二に説明したように、この発明では金属酸化物半導
体の電気伝導度の変化と接触燃焼による温度」二昇との
関係を利用して、ＣＯやメタン等のガスを選択的に検出
することができる。As explained in Section 2 below, in this invention, gases such as CO and methane are selectively detected by utilizing the relationship between changes in electrical conductivity of metal oxide semiconductors and temperature rise due to catalytic combustion. be able to.
第１図（ａ）はガス検出素子の構造例を示す断面図、第
１図（ｂ）は他のガス検出素子の構造例を示す断面図、
第１図（ｃ）は他の構造例を示す切り欠き図である。第
２図（ａ）、 （ｂ）はガス検出素子の特性図、第３図
、第４図は回路図である。
（２ａ ） 、 （２ｂ ） 、 （２ｃ ）
ガス検出素子、（４ａ）、 （４１）Ｌ （４Ｃ）
−金属酸化物半導体、（６ａ）、 （６ｂ）、α埠
・化−夕兼用の測温抵抗体、（３４）・・第１のスイッ
チング回路、（３８）・第２のスイッチング回路、
（４０）・アンド回路。
第１ 図（ａ）
ＣFIG. 1(a) is a sectional view showing a structural example of a gas detection element, FIG. 1(b) is a sectional view showing a structural example of another gas detection element,
FIG. 1(c) is a cutaway diagram showing another structural example. FIGS. 2(a) and 2(b) are characteristic diagrams of the gas detection element, and FIGS. 3 and 4 are circuit diagrams. (2a), (2b), (2c)
Gas detection element, (4a), (41)L (4C)
-Metal oxide semiconductor, (6a), (6b), temperature measuring resistor for both alpha and solar cells, (34)...first switching circuit, (38)-second switching circuit, (40 )・AND circuit. Figure 1 (a) C
Claims (1)
検出する方法において、 妨害ガスの接触燃焼による温度」二昇をヒータ兼用の測
温抵抗体により検出して妨害ガスの影響を除き、特定の
ガスのみを検出するようにしたことを特徴とする特定ガ
ス検出方法。(1) In the method of detecting gases from changes in the electrical conductivity of metal oxide semiconductors, the temperature increase due to catalytic combustion of interfering gases is detected by a resistance temperature detector that also serves as a heater, and the influence of interfering gases is removed. A specific gas detection method characterized by detecting only a specific gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3620983A JPS58174839A (en) | 1983-03-04 | 1983-03-04 | Method of detecting particular gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3620983A JPS58174839A (en) | 1983-03-04 | 1983-03-04 | Method of detecting particular gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58174839A true JPS58174839A (en) | 1983-10-13 |
| JPS6123505B2 JPS6123505B2 (en) | 1986-06-06 |
Family
ID=12463355
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3620983A Granted JPS58174839A (en) | 1983-03-04 | 1983-03-04 | Method of detecting particular gas |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58174839A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60114758A (en) * | 1983-11-28 | 1985-06-21 | Fujikura Ltd | Temperature control method for heated sensor |
| JP2012167954A (en) * | 2011-02-10 | 2012-09-06 | Fuji Electric Co Ltd | Gas detection apparatus |
-
1983
- 1983-03-04 JP JP3620983A patent/JPS58174839A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60114758A (en) * | 1983-11-28 | 1985-06-21 | Fujikura Ltd | Temperature control method for heated sensor |
| JP2012167954A (en) * | 2011-02-10 | 2012-09-06 | Fuji Electric Co Ltd | Gas detection apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6123505B2 (en) | 1986-06-06 |
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