JP2003262608A - Gas concentration detecting apparatus and gas sensor element used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power-thrifty gas concentration detecting apparatus superior in detection accuracy capable of detecting the concentration of gas in a short time. <P>SOLUTION: The gas concentration detecting apparatus is provided with the gas sensor element 9 with both a heating element 10 and a gas sensing part 11, an electric power pulse supply means 12 for intermittently supplying pulse power for the heating element 10 at intervals (A), a sensor output detecting means 13 for detecting the sensor output from the gas sensing part 11, an electric power pulse elapsed time measuring means 15 for measuring an elapsed time from the start of the supply of pulse power, and an electric power supply means 16 adapting to the initial period of drive for supplying the pulse power at short intervals (B) in the case that the elapsed time is shorter than a predetermined time (I). Since the pulse power is supplied for the heating element 10 at the short intervals (B) to accelerate an aging process of the gas sensing part 11 when the gas sensor element 9 is started and the pulse power is supplied at the long intervals (A) after the lapse of the predeterminated time (I), it is possible to achieve the power-thrifty gas concentration detecting apparatus stabled in a short time with high detection accuracy. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas concentration detecting device for detecting the concentration of carbon monoxide or hydrocarbons in the atmosphere, and particularly to a power saving type gas concentration detecting device and a gas sensor element having excellent detection accuracy. Is provided.

[0002]

2. Description of the Related Art A conventional gas concentration detecting device sensitive to carbon monoxide and the like and a gas sensor used therefor are disclosed in Patent No. 27.
No. 91473. The configuration of this gas concentration detecting device is as shown in FIG. 12A, the gas sensor 1 has at least a heater 2 and a gas sensitive film 3, and the heater 2 has a pulse generating means for intermittently applying a power pulse. 4 is electrically connected, and the gas sensitive film 3 is electrically connected to a peak hold circuit 5 for detecting the sensor output. The gas concentration detection device reduces the size of the gas sensor 1 as much as possible in order to realize power saving.
Electric power is applied to the built-in heater 2 in a short time to raise the temperature of the gas sensitive section 3 to an operating temperature of 400 ° C. in a short time.
Then, the gas sensitive unit 3 is intermittently warmed up to the operating temperature by repeating the cycle of applying the electric power for a short time at the determined intervals, and the gas concentration is detected.

FIG. 12B is a cross-sectional view of this gas sensor. A glass heat insulating layer 7 is formed on the surface of a non-glass substrate 6 made of alumina or the like, and a film heater 2 made of ruthenium oxide or the like is formed on the glass heat insulating layer 7. After that, the overcoat glass 8 is further laminated, and the gas sensitive film 3 of tin oxide or the like is sequentially laminated thereon. Japanese Patent Fair 7-99361
Japanese Patent Publication No. 7-10286 and Japanese Utility Model Publication No. 7-10286 also describe a gas sensor having a structure in which a heater film made of ruthenium oxide or platinum and a gas sensitive portion made of tin oxide are provided on one surface of a heat-resistant insulating substrate made of alumina or the like. ing.

On the other hand, Sensors and Actuators B65 (2
000) 190-192 regarding the tin oxide-based gas sensor, a metal silicon substrate wafer (hereinafter,
Silicon wafer) and the film thickness of 4 from the bottom.
It is described that an insulating micro thin film made of 70 nm silicon oxide and 150 nm silicon nitride is formed, and a heater made of titanium metal having a thickness of 30 nm and platinum having a thickness of 240 nm is stacked on the insulating thin film in that order from the bottom. Has been done. further,
Gakki society journal E. Vol. 118, No. 12. 1998 version 6
On page 02, the document “Integrated Gas Concentration Detector Made on Silicon Substrate” is introduced. In this gas sensor, an insulating micro thin film made of silicon oxide is formed on the surface of a silicon wafer by thermal oxidation, and a heater film made of platinum and tungsten, an insulating thin film in which silicon oxide and alumina are laminated, tin oxide and iron oxide are formed on the insulating micro thin film. Further, the gas sensitive thin film of tungsten oxide is laminated in order from the bottom.
The heater film made of platinum and tungsten has chromium formed on the upper and lower sides thereof to improve durability.

[0005]

The conventional gas concentration detecting device detects the gas concentration by intermittently warming the gas sensitive portion to the operating temperature by repeating the cycle of applying electric power to the heater in a short time. . However, if the heater operation is stopped for a long time and then restarted, various gases adsorbed during the heater operation stop are not easily desorbed in the gas sensitive part such as tin oxide, so the sensor output It took a long time to stabilize, and there was a problem that the detection accuracy was poor for a while after the restart.

The present invention solves the above-mentioned conventional problems,
An object of the present invention is to provide a small-sized energy-saving type gas concentration detection device in which the sensor output is stable in a short time and the detection accuracy is excellent by using a simple control technique.

Further, the conventional heater incorporated in the gas sensor applies a large amount of electric power in a short time to heat up to the operating temperature of the gas sensitive portion in a short time, so that it deteriorates when used for a long time and a predetermined amount is generated. Cannot raise to operating temperature. for that reason,
There was a problem that detection accuracy was poor because a stable sensor output could not be obtained.

The present invention solves the above-mentioned conventional problems,
An object of the present invention is to provide a small power-saving type gas sensor element that can raise the temperature to a predetermined operating temperature by using a heater film with excellent durability and reliability, which provides stable sensor output and excellent detection accuracy. It is what

[0009]

In order to solve the above-mentioned problems, a gas concentration detecting device of the present invention has a gas sensor element having at least a heating element and a gas sensing section, and a pulse power to the heating element at intervals (A). Power pulse supply means for intermittent supply, sensor output detection means for detecting the sensor output from the gas sensing unit, power pulse elapsed time measurement means for measuring the elapsed time from the start of pulse power supply, and measured progress It is assumed that at least the drive initial corresponding power supply means for performing control to supply the pulse power at a short interval (B) when the time is less than the predetermined time (I).

When the gas sensor element is restarted, the drive initial corresponding power supply means operates to instruct the power pulse supply means to supply pulse power to the heating element at a short interval (B). The aging process is accelerated. Then, when a predetermined time (I) at which the sensor output stabilizes is reached, the drive initial corresponding power supply means is stopped, and the power pulse supply means supplies pulse power to the heating element at a normal interval (A). By the pulse power supply at this short interval (B), stabilization of the gas sensor element is accelerated, and a gas concentration detection device with high detection accuracy can be obtained in a short time. Also, since the electric power is supplied to the heating element in pulses,
It is a power-saving type gas concentration detection device.

In order to solve the above-mentioned problems, the gas sensor element of the present invention comprises at least a thin film of a heating element, a heat-resistant insulating thin film, and a gas sensing part, which are sequentially stacked from the bottom on the upper surface of an insulating heat-resistant substrate. In addition to the configuration provided, the heating element,
A heater main thin film containing platinum as a main component and 0.1
It is assumed that it is composed of a metal heater auxiliary fine thin film containing as a main component at least one material selected from titanium, zirconium, or chromium and arranged with a film thickness not more than twice.

Since it is a heating element composed of two layers of a platinum heater main thin film and a metal heater auxiliary thin film of titanium, zirconium, chromium or the like disposed below the platinum heater thin film, durability and reliability are improved. It becomes an excellent heating element and can always raise the temperature to a predetermined operating temperature. Therefore, a small power-saving type gas sensor element that can obtain a stable sensor output for a long period of time and is excellent in detection accuracy can be obtained forever.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention can be implemented in the modes described in each claim.

According to a first aspect of the present invention, there is provided a gas sensor element having at least a heating element and a gas sensing section, power pulse supply means for intermittently supplying power to the heating element at intervals (A), and the power pulse supply. At least a controller for controlling the interval of the power pulse emitted by the means, and a sensor output detection means for detecting the sensor output from the gas sensing unit, the controller, the elapsed time from the pulse supply start of the power pulse supply means At least a power pulse elapsed time measuring unit for measuring and a drive initial corresponding power supplying unit for controlling a power pulse interval to be short at the initial stage of driving are provided, and the drive initial corresponding power supplying unit is the power pulse elapsed time measuring unit. When the elapsed time measured at is less than the predetermined time (I), the pulse power of the power pulse supply means is shorter than the interval (A). The gas concentration detection device controls the supply at a certain interval (B).

When the gas sensor element is restarted, the drive initial corresponding power supply means operates to instruct the power pulse supply means to supply the pulsed power to the heating element at a short interval (B). The aging process is accelerated. Then, when a predetermined time (I) at which the sensor output stabilizes is reached, the drive initial corresponding power supply means stops, and the power pulse supply means supplies pulse power to the heating element at the normal interval (A). According to the present invention, the stabilization of the gas sensor element is accelerated by the above, and thus a gas concentration detection device with high detection accuracy can be obtained in a short time. Further, since the electric power is supplied to the heat generating element in pulses, the gas concentration detecting device is of a power saving type.

According to a second aspect of the present invention, in particular, the controller according to the first aspect includes a sensor output abnormality determining means for determining whether or not there is an abnormality in the sensor output, and an abnormality for controlling the power pulse interval to be short when the sensor output is abnormal. The power supply means for time correspondence is further provided, and the power supply means for abnormal time is
When the elapsed time measured by the power pulse elapsed time measuring means is the predetermined time (I) or more and less than the predetermined time (II) and the sensor output abnormality determining means determines that the sensor output is abnormal, the power pulse supplying means The control is such that the pulse power is supplied at an interval (C) shorter than the interval (A).

If the sensor output is judged to be abnormal when the elapsed time from the start of pulse supply is equal to or longer than the predetermined time (I), the gas sensor element is not sufficiently aged for some reason and the sensor output is stable. It means not doing. According to the present invention, in this case, the power supply means for dealing with an abnormality supplies pulse power to the heating element at short intervals (C), so that the aging process is accelerated. As a result, according to the present invention, since the gas sensor element constituting the present invention is stabilized in a short time by these, a gas concentration detecting device with higher detection accuracy can be obtained in a short time.

According to a third aspect of the present invention, in particular, the controller according to the first aspect is provided with an emergency pulse supply means, and when the elapsed time measured by the power pulse elapsed time measuring means reaches a predetermined time (II). When the sensor output abnormality determining means determines that the sensor output is abnormal, the electric power pulse supplying means restarts the heating element at the interval (B).

It is determined that the sensor output is abnormal when the elapsed time from the start of pulse supply is the predetermined time (II),
It means that the sensor output is not stable for some reason. In the present invention, in this case, the emergency pulse supply means issues a control command to cause the power pulse supply means to restart the heating element, so that the gas sensor element is subjected to the aging process again and the sensor output is stabilized again. Will be tried. As a result, a gas concentration detection device with higher detection accuracy can be obtained.

According to the invention described in claim 4, in particular, when the emergency pulse supply means according to claim 3 is activated a plurality of times, an alarm is issued.

The fact that the emergency pulse supply means operates a plurality of times means that the gas sensor element has deteriorated for some reason. The present invention issues an alarm in this case, so
Deterioration of the gas sensor element is found, and a gas concentration detecting device with higher detection accuracy can be obtained.

According to a fifth aspect of the present invention, in particular, the gas detection time pulse supply means further provided in the controller according to the first aspect is that the elapsed time measured by the power pulse elapsed time measuring means is a predetermined time (II) or more. When the sensor output abnormality determination means determines that the sensor output is abnormal within the predetermined threshold output, the power pulse supply means is controlled to supply the pulse power at an interval (D) shorter than the interval (A). It was configured.

If the sensor output abnormality determining means determines that the sensor output is abnormal within the threshold output when the elapsed time is equal to or longer than the predetermined time (II), it means that a high concentration gas is present. According to the present invention, in this case, the gas supply pulse supplying means supplies the pulse power to the heating element at short intervals (D), so that the behavior of the gas concentration which changes moment by moment can be detected with high accuracy, and the detection accuracy is higher. A gas concentration detector is obtained.

According to a sixth aspect of the present invention, in the gas detection time pulse supply means according to the fifth aspect, the sensor output abnormality determining means is provided when the elapsed time measured by the power pulse elapsed time measuring means is a predetermined time (II) or more. When it is determined that the sensor output exceeds the predetermined threshold output, the power pulse supply means restarts the heating element at the interval (B).

If the sensor output exceeds the threshold output when the elapsed time is equal to or longer than the predetermined time (II), it means that the gas sensor element is not stabilized for some reason. In the present invention, in this case, the power pulse supply means restarts the heating element at the interval (B), the aging process of the gas sensor element is performed again, and the stabilization of the sensor output is retried. As a result, a gas concentration detection device with higher detection accuracy can be obtained.

According to a seventh aspect of the present invention, there is provided at least a heat-generating thin film, a heat-insulating thin film, and a gas sensing part, which are laminated in this order from the bottom on the upper surface of the insulating heat-resistant substrate.
The heating element has a heater main thin film containing platinum as a main component and a film thickness not exceeding 0.1 times the film thickness of the heater main thin film. The gas sensor element is composed of a metal heater auxiliary thin film containing at least one material selected from titanium, zirconium, and chromium as a main component.

The metal heater auxiliary thin film of titanium, zirconium or chromium is a material having excellent bonding properties and malleability, and if it is arranged below the heater main thin film, the film thickness will not exceed 0.1 times the film thickness of the heater main thin film. A heat generating element having malleability can be obtained by being well bonded to platinum which is the main film of the heater. When a large amount of power is applied for a short time to save power, the heating element rises in temperature to the operating temperature in a short time and thermally expands, and the temperature of the insulating heat-resistant substrate and heat-resistant insulating thin film placed above and below it also rises at the same time. However, the laminated heating element satisfactorily follows the thermal expansion, does not cause peeling, and exhibits excellent durability reliability without resistance change. In addition, the gas sensing portion laminated on the upper part of the heat-transmitting thin film effectively transmits the heat generated by the heating element through the thin film of the heat-resistant insulating thin film, and becomes in an operating state in a short time so that the gas concentration can be detected. Therefore, a small power-saving type gas sensor element that can obtain a stable sensor output for a long period of time and is excellent in detection accuracy can be obtained forever.

The invention according to claim 8 is that the insulating heat-resistant substrate according to claim 7 is a glass material having a transition temperature of at least 650 ° C. or higher. Since it is an insulating heat-resistant substrate made of a glass material having a very small thermal conductivity, the heat generated by the heating element is transferred only slightly to the insulating heat-resistant substrate, and most of it is transferred to the gas sensing unit. Therefore, the operating temperature can be reached with a smaller amount of power consumption, and a gas concentration detection device with a further reduced power consumption can be realized. Further, as a result of this, since the heating element consumes less power, the applied voltage / current value is also reduced, and excellent durability characteristics can be obtained. Moreover, since the insulating heat-resistant substrate is a glass material having a very strong property against compressive stress, it can well follow the thermal expansion caused by heat generation,
Due to these synergistic effects, the heating element can obtain more excellent durability characteristics.

On the other hand, the heating element has the property of obtaining good bondability and malleability when fired at 600 ° C. or higher. Since the insulating heat-resistant substrate of the present invention is a glass material having a transition temperature (a temperature at which a sudden volume change occurs) of 650 ° C. or higher, the heating element may be fired so as not to exceed the transition temperature of the glass material. it can. Therefore, the insulating heat-resistant substrate does not undergo a rapid volume change (transition), and accordingly, the heating element is well bonded to the insulating heat-resistant substrate, and further excellent durability characteristics can be obtained.

According to the invention of claim 9, the insulating heat-resistant substrate according to claim 7 is a quartz glass containing a hydroxyl group in an amount not exceeding 0.20 wt%. Since it is an insulating heat-resistant substrate made of quartz glass with a very low thermal conductivity, most of the heat generated by the heating element is transferred to the insulating heat-resistant substrate, and most of it is transferred to the gas sensing unit, up to the operating temperature. It is possible to achieve a gas concentration detection device that can be reached with an extremely small amount of power and that has an extremely reduced power consumption.

Moreover, since the coefficient of thermal expansion of quartz glass is very small, the thermal expansion of the insulating heat-resistant substrate is small, but the heating element is well adhered to the insulating heat-resistant substrate to obtain excellent durability characteristics. Further, the hydroxyl group contained in the quartz glass is adjusted to 0.
Since the content is less than 20 wt%, the metal heater auxiliary thin film of titanium, zirconium, or chrome is better adhered to the insulating heat-resistant substrate made of quartz glass, and more excellent durability characteristics are obtained. Furthermore, since quartz glass has a very excellent heat resistance with a transition temperature of 1075 ° C, when it is used as an insulating heat resistant substrate,
The heating element, the heat-resistant insulating thin film, and the gas sensing part can be formed by a simple manufacturing method because restrictions on the firing temperature are reduced.

According to a tenth aspect of the invention, the insulating heat-resistant substrate according to the seventh aspect has a center line surface roughness of 0.05 to 1.
It was assumed to be μm. Center line surface roughness is 0.05-1 μm
In the case of the insulating heat-resistant substrate, since the heating element can be more favorably bonded and can follow the thermal expansion satisfactorily, peeling does not occur and more excellent durability characteristics can be obtained.

The invention according to claim 11 is that the heat-resistant insulating thin film according to claim 7 is a glass material having a transition temperature of at least 650 ° C. or higher. When the heat-resistant insulating thin film is made of a glass material having a property of being extremely strong against compressive stress, it can follow the thermal expansion due to heat generation well, so that a heating element with more excellent durability characteristics can be obtained. On the other hand, the heating element has the property of obtaining good bondability and malleability when fired at 600 ° C. or higher. Since the heat-resistant insulating thin film of the present invention is a glass material having a transition temperature (a temperature at which a sudden volume change occurs) of 650 ° C. or higher, the heating element can be fired so as not to exceed the transition temperature of the glass material. it can. As a result, the heat-resistant insulating thin film does not undergo a rapid volume change (transition), and accordingly, the heating element is well adhered to the heat-resistant insulating thin film, and more excellent durability characteristics can be obtained.

According to the invention of claim 12, the heat-resistant insulating thin film of claim 7 is made of quartz glass. Quartz glass has a property of being well bonded to the platinum heater main thin film, and therefore, when it is disposed on the heating element side as a heat-resistant insulating thin film, it is well bonded to the heating element. Further, since it has a very strong property against compressive stress and has a very small coefficient of thermal expansion, it can follow the thermal expansion due to heat generation well, and the heating element can obtain more excellent durability characteristics.

According to a thirteenth aspect of the present invention, in the gas sensing section according to the seventh aspect, the oxygen ion conductive solid electrolyte thin film and the breathable first electrode thin film arranged on the oxygen ion conductive solid electrolyte thin film are provided. And at least a second electrode thin film, and the oxygen ion conductive solid electrolyte thin film is a material having a thermal conductivity of 1 to 7 W / mK. The oxygen ion conductive solid electrolyte thin film functions as a good heat dissipation thin film when its thermal conductivity is 1 to 7 W / mK. Therefore, the local temperature rise of the heating element is suppressed and more excellent durability characteristics are obtained.

According to a fourteenth aspect of the present invention, the first electrode film according to the thirteenth aspect is an electrode film having excellent oxidation catalyst properties, and the second electrode film is inferior to the first electrode film in oxidation catalyst properties. And Since the first electrode film is an electrode film having an excellent oxidation catalyst property and the second electrode film is inferior to the first electrode film in an oxidation catalyst property, both electrode films work as good heat dissipation thin films. Therefore, the local temperature rise of the heating element is suppressed and more excellent durability characteristics are obtained.

[0037]

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

(Embodiment 1) FIG. 1 is a configuration diagram of a gas concentration detecting device according to an embodiment of the present invention and a flow chart showing a processing flow. FIG. 1 (a) is a configuration diagram and FIG. 2 (b) is a configuration diagram. It is a flow chart which shows a flow of processing.

First, the structure will be described with reference to FIG. The gas sensor element 9 includes a heating element 10 and a gas sensing unit 11.
It is a configuration including at least. A power pulse supply means 12 is electrically connected to the heating element 10, and pulse power is intermittently supplied at intervals (A) by the power pulse supply means 12, so that the heating element 10 is intermittent. Repeat the cycle of increasing temperature. On the other hand, the gas sensing unit 11 is electrically connected to a sensor output detection means 13 that detects the sensor output. On the other hand, the power pulse supply means 1
In the case of No. 2, the interval of the power pulse generated by the controller 14 is controlled. Its controller 1
4 is a power pulse elapsed time measuring means 15 for measuring the elapsed time from the start of pulse supply of the power pulse supplying means 12.
When the elapsed time measured by the power pulse elapsed time measuring means 15 is less than the predetermined time (I), the pulse power of the power pulse supplying means 12 is controlled to be supplied at an interval (B) shorter than the interval (A). This is a configuration including at least the drive initial corresponding power supply means 16.

Next, a flow chart showing the flow of processing will be described with reference to FIG. When the process flow is started by the start of the start switch, the power pulse elapsed time measuring means 15 is activated to measure the elapsed time from the start of pulse supply. At the same time, the drive initial correspondence power supply means 16 is activated to issue a control command for intermittently supplying pulse power to the power pulse supply means 12 at intervals (B).
The drive initial corresponding power supply means 16 repeats this processing flow until the elapsed time reaches the predetermined time (I), and intermittently supplies the pulse power to the heating element 10 at intervals (B). Then, when the predetermined time (I) is reached, the drive initial correspondence power supply means 16 stops the control command to supply the pulse power at the interval (B), and the power pulse supply means 12 causes the heating element 10 to operate.
Then, pulse power is intermittently supplied at intervals (A).

A gas concentration detector of this example was prototyped and its effect was confirmed. The structure of the gas sensor element used for effect determination is shown in FIG. The gas sensor element 9 includes a thin film of the heating element 10, a heat-resistant insulating thin film 18, and a gas sensing unit 11 which are sequentially stacked on the upper surface of the insulating heat-resistant substrate 17 from the bottom.
And a film.

The insulating heat-resistant substrate 17 is a quartz glass plate having a size of 2 mm square and a thickness of 0.3 mm. As for the physical properties, the thermal expansion coefficient is 0.5 × 10 ⁻⁶ (1 / deg), the thermal conductivity is 1.7 W / mK, the transition temperature is 1075 ° C., and the softening point is 158.
It is 0 ° C. The composition of quartz glass is 99.
It contains less than 0.01% of hydroxyl groups at 99%, and has a center line surface roughness of 0.05 to 0.2 μm after polishing the surface. Note that this material was used hereafter unless otherwise specified.

The heating element 10 includes a metal heater auxiliary thin film 19 arranged on the lower portion and a heater main thin film 20 arranged on the upper portion thereof.
It is composed of a laminated film of. Metal heater auxiliary thin film 19
Is chromium having a film thickness of about 0.005 μm formed by the sputtering method, and its thermal expansion coefficient is 6.2 × 10 ⁻⁶ (1
/ deg). The heater main thin film 20 is formed by forming a platinum resistance film having a film thickness of about 0.5 μm by a sputtering method, and has a thermal expansion coefficient of 9 × 10 ⁻⁶ (1 / deg) and a thermal conductivity of 69. It is 5 W / mK.

The heat-resistant insulating thin film 18 has a film thickness of 2 μm and is made of quartz glass by a sputtering method.
Is stacked on top of. As for the physical properties, the coefficient of thermal expansion is 0.5 × 10 ⁻⁶ (1 / deg) and the thermal conductivity is 1.7 W / mK. The heat-resistant insulating thin film 18 of quartz glass is laminated on the heating element 10 by the sputtering method, and then 1000 ° C. in the atmosphere.
It was baked for 1 hour.

The gas sensing unit 11 includes the oxygen ion conductive solid electrolyte thin film 21, the breathable first electrode thin film 22 and the second electrode thin film 23 formed on the same surface of the solid electrolyte thin film 21, and the first electrode thin film 22. Laminated porous porous oxidation catalyst film 24
Composed of. Oxygen ion conductive solid electrolyte thin film 21
Is yttrium oxide 8 mol% and zirconium oxide 92
It is a stabilized zirconia body that is a solid solution of mol%, and has a film thickness of about 2 μm formed by a sputtering method and is laminated on the heat resistant insulating thin film 18. As for the physical properties, the thermal expansion coefficient is 10 × 10 ⁻⁶ (1 / deg) and the thermal conductivity is 5 W / mK. The first electrode thin film 22 and the second electrode thin film 23 are air-permeable porous thin films of platinum formed by sputtering platinum, and have a film thickness of about 0.5 μm on the same upper surface of the oxygen ion conductive solid electrolyte thin film 21. Is formed by. Oxidation catalyst film 24
Is a breathable porous film in which a platinum catalyst is carried on the surface of an alumina-silica adhesive, and is laminated on the first electrode thin film 22 to a thickness of about 20 μm.

Finally, the first electrode thin film 2 of the gas sensing section 11
After the platinum lead wires are connected to both ends of the second and second electrode thin films 23 and the heating element 10, they are housed in a mounting case to complete the gas sensor element 9. The heating element 10 is electrically connected to the power pulse supply means 12 through the connected platinum lead wire, is heated by the application of a voltage and current, and is heated by the heating element 10 to be emitted from the gas sensing section 11. The sensor output is measured by the sensor output detecting means 13.

The gas sensing portion 11 having the above structure is called a solid electrolyte type, and the mechanism of detecting the carbon monoxide gas will be described. First, the gas sensor element 11 includes the heating element 10
Heat to 400 ° C. On the surface of the oxidation catalyst film 24, carbon monoxide gas reacts with oxygen gas due to its catalytic action to become carbon dioxide gas and is consumed and disappears, but the oxygen concentration remains almost atmospheric because it is overwhelmingly high. The first electrode thin film 22 is reached. On the other hand, on the surface of the other second electrode thin film 23, the carbon monoxide gas and the oxygen gas react with each other by the catalytic action to become carbon dioxide gas, and the oxygen gas concentration on the surface decreases. Therefore, focusing on the oxygen concentration, the concentration on the first electrode thin film 22 side becomes higher than that on the second electrode thin film 23, and the second electrode thin film 23 side from the first electrode thin film 22 side.
The oxygen gas moves toward the inside of the oxygen ion conductive solid electrolyte thin film 21 as oxygen ions, and an electromotive force is generated by this oxygen transfer. This electromotive force is the sensor output, and a value approximately proportional to the logarithmic value of the carbon monoxide gas concentration is obtained.

The effect of this example was judged. The effect is
Applying a DC voltage current to heat the heating element 10 at an operating temperature of 400 ° C.
Elapsed time after measuring the transient change of the sensor output obtained from the gas sensing unit 11 when the pulse power supply is continuously turned off It was carried out according to the size of (stability time). The results are shown in (Table 1).

In this embodiment, 15 minutes from the start,
Pulses are supplied at 5 second intervals, and after 15 minutes, pulses are supplied at 30 second intervals. This is the predetermined time (I)
Is 15 minutes, the interval (B) is 5 seconds, and the interval (A) is 30 seconds.

In the conventional example, pulses are always supplied at intervals of 30 seconds from the start.

It can be seen that in this embodiment, the sensor output is stable in 10 minutes and is shorter than 120 minutes in the conventional method.

[0052]

[Table 1]

Next, the material composition of the heating element 10 and the gas sensing portion 11 used in the gas sensor element 9 of the present invention was examined.

The heating element 10 contains a small amount of rhodium, palladium or the like mixed in an amount of 20% by weight or less and the balance of platinum (80% by weight or more), a platinum-based metal, a metal oxide containing ruthenium oxide as a main component, and zirconium oxide. A metal oxide as a main component, an inorganic material containing molybdenum silicide as a main component, a nickel-chromium alloy containing 10 to 25% of chromium and most of the balance nickel, and containing 10 to 30% of chromium as necessary. There is a case where 1 to 8% of aluminum is added, and a heat-generating material such as an iron-chromium alloy in which most of the balance is iron is effective.

Then, further below the heat generating material,
When the heating element 10 has a laminated structure in which a metal heater auxiliary thin film containing at least one material of titanium, zirconium, or chromium whose thickness is reduced is used as a main component,
The resistance change rate was reduced to 1 / (100 to 500) as compared with a heating element having a single structure of only a heating material, and excellent durability was exhibited. Of these exothermic materials, platinum and platinum-based metals have the most excellent durability in the laminated combination in which the metal heater auxiliary thin film is laid under them, and are most suitable for pulse current application. .

As the gas sensing portion 11, a metal oxide semiconductor film of tin oxide, iron oxide, tungsten oxide or the like, or a solid electrolyte type gas sensing portion is effective. When the gas sensing unit 11 is a solid electrolyte type, the oxygen ion conductive solid electrolyte thin film is
Sputtered films, deposited films, and sol-gel films of various zirconia-based oxygen ion conductive solid electrolytes and ceria-based oxygen ion conductive solid electrolytes represented by partially stabilized zirconia bodies of 3 mol% yttrium oxide and 97 mol% zirconium oxide are effective. Is.

The first electrode thin film and the second electrode thin film used for this
As the electrode thin film, a breathable printed film, a sputtered film, or a deposited film of a noble metal such as platinum or gold or an oxygen ion conductive metal oxide having a perovskite structure is effective. on the other hand,
As the oxidation catalyst film laminated on the first electrode thin film, a gas permeable porous film in which an inorganic adhesive such as crystallized glass is mixed with a noble metal such as platinum or a metal oxide is effective. Further, the first electrode film is an electrode film having an excellent oxidation catalyst property, and the second electrode film is an electrode film having an oxidation catalyst property inferior to the first electrode film.
A solid electrolyte type gas sensing unit without using an oxidation catalyst film was also effective.

As the insulating heat-resistant substrate 17, a glass material, a heat-resistant substrate having a crystallized glass film arranged on the surface, or a ceramic plate made of alumina, silicon nitride or the like was effective. Among the insulating heat resistant substrates 17, the glass member had the smallest power consumption during pulsed current application, and the heat resistant substrate having the crystallized glass film on the surface and the ceramic plate had the highest values in this order. This has a correlation with the thermal conductivity of the material of the insulating heat-resistant substrate 17, and the insulating heat-resistant substrate 17 is less likely to be heated by a glass material having a smaller thermal conductivity, so that the power consumption is small and the ceramic plate having a large thermal conductivity is used. Since the insulating heat resistant substrate 17 is heated more, the power consumption tends to be larger. Among the glass materials, quartz glass has excellent heat resistance, and because it has the smallest thermal conductivity and coefficient of thermal expansion, it consumes the least amount of electricity and is therefore most suitable as the insulating heat-resistant substrate 17 for pulse energization. there were.

A heating element 1 in which the above-mentioned metal heater auxiliary thin film and a platinum-based metal are further laminated on top of quartz glass
0 was excellent in resistance stability and showed the most excellent durability.

The heat-resistant insulating thin film 18 is a printed film of ceramics such as alumina or silicon nitride and glass, a sputtered film,
Evaporated film and sol-gel film are effective.

(Embodiment 2) FIG. 3 is a configuration diagram of a gas concentration detection device according to a second embodiment of the present invention and a flow chart showing the flow of processing. FIG. 3 (a) is a configuration diagram and FIG. b)
Is a flow chart showing the flow of processing.

In the configuration diagram of FIG. 3A, FIG.
The difference is that the controller 14 has a sensor output abnormality determining means 25 for determining whether or not there is an abnormality in the sensor output, and the elapsed time measured by the power pulse elapsed time measuring means is a predetermined time (I) or more and a predetermined time (II). When the sensor output abnormality determining means 25 determines that the sensor output is abnormal, the pulse power of the power pulse supplying means 12 is controlled at an interval (C) shorter than the interval (A). And means 26.

The flowchart of FIG. 3B is the same as that of FIG.
The processing flow from (b) is received. When a predetermined time (I) has passed, the sensor output is detected, and if the sensor output is normal, the pulse power is intermittently supplied at intervals (A), but if the sensor output is abnormal, the power supply means 26 for abnormal time intervals provides the pulse power. In (C), a control command to be intermittently supplied is issued.
This processing flow is repeated until the predetermined time (II) is reached.

Whether or not the sensor output is abnormal was determined as follows. The sensor output has a property of showing a stable output value after a predetermined time (I) has elapsed. Therefore, the stable output value obtained when exposed to the general atmosphere containing no carbon monoxide is measured in advance and stored in the output abnormality determining means 25. This stable output value has an allowable range in consideration of variations, and is stored as an upper limit stable output value and a lower limit output value. Then, the sensor output was measured at the time when the predetermined time (I) had passed, and the presence or absence of abnormality was determined by comparing the obtained sensor output value with the previously stored stable output value. That is, when the obtained sensor output value and the stable output value stored in advance match in consideration of variations, it is determined to be normal, and when they differ even in consideration of variation, it is determined to be abnormal.

The fact that the sensor output is judged to be abnormal when the elapsed time from the start of pulse supply is more than the predetermined time (I) and less than (II) means that the gas sensor element is not sufficiently aged for some reason. , It means that the sensor output is not stable. In the present invention, in this case, since the power supply means 26 for dealing with an abnormality supplies the pulse power to the heating element 10 at short intervals (C), the aging process is accelerated. As a result, the gas sensor element 9 is stabilized in a short time, and a gas concentration detection device with higher detection accuracy can be obtained in a short time.

(Embodiment 3) FIG. 4 is a configuration diagram of a gas concentration detecting device according to a third embodiment of the present invention and a flow chart showing the flow of processing. FIG. 4 (a) is a configuration diagram and FIG. b)
Is a flow chart showing the flow of processing.

The configuration of FIG. 4 differs from that of FIG. 3 in that the controller 14 is further provided with an emergency pulse supply means 27. When the sensor output abnormality determining means 25 determines that the sensor output is abnormal when the elapsed time measured by the power pulse elapsed time measuring means 15 reaches the predetermined time (II), the emergency pulse supplying means 27 The power pulse supply means 12 is adapted to restart the heating element 10 at the interval (B).

The flowchart of FIG. 4B is the same as that of FIG.
The processing flow from (b) is received. When the predetermined time (II) is reached, if the sensor output is abnormal, the pulse is restarted at the interval (B), and if the sensor output is normal, the pulse power at the interval (A) is further continuously supplied. The method for determining whether or not the sensor output is abnormal is the same as described above.

The fact that the sensor output is judged to be abnormal when the elapsed time from the start of pulse supply is the predetermined time (II) means that the sensor output is not stable for some reason. In this case, the emergency pulse supply means 27
Since the power pulse supply means 12 issues a control command to restart the heating element 10, the gas sensor element 9 is again subjected to the aging process, and the stabilization of the sensor output is tried again. As a result, a gas concentration detection device with higher detection accuracy can be obtained.

(Embodiment 4) FIG. 5 is a configuration diagram of a gas concentration detecting device according to a fourth embodiment of the present invention and a flow chart showing the flow of processing. FIG. 5 (a) is a configuration diagram and FIG. b)
Is a flow chart showing the flow of processing.

The configuration of FIG. 5 differs from that of FIG. 4 in that an alarm 28 is issued when the emergency pulse supply means 27 operates a plurality of times.

The flowchart of FIG. 5 (b) is shown in FIG.
The processing flow from (b) is received. When the sensor output is abnormal when the predetermined time (II) is reached, the pulse is restarted at the interval (B). When the pulse restart is performed a plurality of times, the alarm 28 is issued.

The fact that the emergency pulse supply means 27 operates a plurality of times means that the gas sensor element 9 has deteriorated for some reason. In this case, the alarm 28 is issued,
The deterioration of the gas sensor element 9 can be seen, and a gas concentration detection device with higher detection accuracy can be obtained.

(Embodiment 5) FIG. 6 is a configuration diagram of a gas concentration detecting device according to a fifth embodiment of the present invention and a flow chart showing the flow of processing. FIG. 6 (a) is a configuration diagram and FIG. b)
Is a flow chart showing the flow of processing.

The configuration of FIG. 6 differs from that of FIG. 4 in that the controller 11 is provided with a gas detection time pulse supply means 29.
Is a point that is further equipped. Gas supply pulse supply means 2
9 is the power pulse when the elapsed time measured by the power pulse elapsed time measuring means 15 exceeds the predetermined time (II) and the sensor output abnormality determining means 25 determines that the sensor output is abnormal within the threshold value. The supply means 12 is configured to control the supply of pulse power at short intervals (D).

The flow chart of FIG. 6B is shown in FIG.
The processing flow from (b) is received. When the predetermined time (II) is exceeded, it is determined whether or not the sensor output is within the threshold output, and if the sensor output is within the threshold output and the sensor output is abnormal, the pulse power is intermittent at intervals (D). Is supplied in a regular manner. On the other hand, if the sensor output is within the threshold output and it is determined that the sensor output is normal, the pulse power in the interval (A) is further continuously supplied. This cycle is repeated so that the increase in gas concentration can be determined exactly.

The judgment as to whether or not the sensor output is within the threshold output is made as follows. The sensor output becomes a stable output value after a lapse of a predetermined time (II), and when the carbon monoxide concentration increases, the sensor output shows a corresponding change. Therefore, the concentration of carbon monoxide, which is generally considered to be dangerous, is considered to be, for example, 500 ppm, and this carbon monoxide is 500 ppm.
The sensor output when exposed to mixed air and the sensor output when exposed to general air that does not contain carbon monoxide at all are measured in advance. The upper limit output value and the lower limit output value in each atmosphere are treated as threshold output and stored in the output abnormality determining means 25.

Then, the sensor output measured at the time when the predetermined time (II) has passed is compared with the threshold output stored in advance, and it is determined whether or not it is within the threshold output. If the obtained sensor output value is within the threshold output value stored in advance, it means that the concentration of carbon monoxide in the atmosphere is 0 ppm or more and 50
It is considered to be within any concentration of 0 ppm or less.

On the other hand, the fact that the obtained sensor output value is other than the threshold value output stored in advance means that the concentration of carbon monoxide in the atmosphere is 500 ppm or more. However, it does not increase rapidly to this concentration. It is practically unthinkable, and the concentration should increase after passing through the intermediate concentration of 50 ppm, for example. Therefore, it is conceivable that the gas sensor element did not stabilize for some reason in this situation that is difficult to judge.

The judgment as to whether the sensor output is normal or abnormal was made as follows. The carbon monoxide concentration, which is generally considered to require attention, is considered to be, for example, 50 ppm, and the sensor output when exposed to the atmosphere containing this carbon monoxide of 50 ppm is measured in advance. The sensor output value in the 50 ppm atmosphere is handled as a caution output and stored in the output abnormality judging means 25. Then, the sensor output measured when the predetermined time (II) has passed is compared with the pre-stored caution output, and it is determined whether or not the output is within the caution output. If the obtained sensor output value is within the caution output stored in advance, it means that the concentration of carbon monoxide in the atmosphere is 5 ppm or more.
Since it means that the concentration is within 0 ppm or less, it is judged to be normal.

On the other hand, if the obtained sensor output value is other than the caution output stored in advance, it means that the concentration of carbon monoxide in the atmosphere is 50 ppm or more, and therefore it is determined to be abnormal.

When the elapsed time is equal to or longer than the predetermined time (II), the sensor output abnormality determining means determines that the sensor output is abnormal within the threshold output, as described above. Means that gas is present. In this case, since the pulse supply means at the time of gas detection supplies pulse power to the heating element at short intervals (D), it is possible to accurately detect the behavior of the gas concentration that changes moment by moment, and the gas concentration detection device with higher detection accuracy. Is obtained.

(Sixth Embodiment) A gas concentration detecting apparatus according to a sixth embodiment is shown in the block diagram of FIG. 6 (a) and in the flow chart of its processing in FIG. 6 (b). The difference from the fifth embodiment is that when the elapsed time measured by the power pulse elapsed time measuring means 15 is a predetermined time (II) or more, the sensor output abnormality determining means 25 exceeds a predetermined threshold output and abnormally outputs the sensor output. If it is determined that the power pulse supply means 12
The point is that the heating element 10 is restarted at the interval (B).

As described in the fifth embodiment, the fact that the obtained sensor output value is other than the threshold output stored in advance means that the carbon monoxide concentration in the atmosphere is 500 ppm or more. . However, it is practically unthinkable that the concentration rapidly increases to this concentration, and the concentration should definitely increase after passing through an intermediate concentration of 50 ppm, for example.

However, in this case, the above-mentioned fifth
The abnormality should be judged in the embodiment, and this situation which is difficult to judge is considered that the gas sensor element was not stabilized for some reason. It should be noted that if the obtained sensor output value is other than the threshold output stored in advance, it is assumed that the concentration of carbon monoxide in the atmosphere is minus several hundred ppm, but this assumption that is difficult to judge is It is considered that the gas sensor element did not stabilize due to the cause.

When the elapsed time is equal to or longer than the predetermined time (II), the sensor output abnormality determining means exceeds the threshold output and determines that the sensor output is abnormal for some reason.
This means that the gas sensor element was not stabilized. In this case, the power pulse supply means restarts the heating element, and the aging process of the gas sensor element is performed again,
Attempt to stabilize the sensor output again. As a result, a gas concentration detection device with higher detection accuracy can be obtained.

(Example 7) From Example 7, the structure and material of the gas sensor element were examined. The composition is
This is as described in FIG. 2 above.

Example 7 is the result of examining the material of the heating element 10.

The examination was carried out by using an insulating heat-resistant substrate 17 made of quartz glass, and heating elements 1 of different constitutions and materials on the upper surface thereof.
After forming 0, a heat-resistant insulating thin film 18 made of quartz glass is further laminated thereon, and finally, the solid-electrolyte type gas sensing portion 11 of the first embodiment is laminated to form the gas sensor element 9.

The heating element 10 of Example 1 has a film thickness of 0.5 μm.
A heater main thin film 20 made of platinum of m and a metal heater auxiliary thin film 19 made of titanium having a film thickness of 0.005 μm, which is arranged under the heater main thin film.

The heating element 10 of the second embodiment has a film thickness of 0.5 μm.
The heater main thin film 20 is made of platinum of m, and the metal heater auxiliary thin film 19 of zirconium having a thickness of 0.005 μm is disposed below the heater main thin film.

The heating element of the third embodiment comprises a heater main thin film 20 made of platinum having a film thickness of 0.5 μm, and a metal heater auxiliary fine layer made of chromium having a film thickness of 0.005 μm arranged under the heater main thin film. It is composed of a thin film 19.

The heating element of the conventional example is only the heater main thin film made of platinum and having a film thickness of 0.5 μm.

The examination results of various heating elements are shown in (Table 2). The rate of resistance change of the heating element 10 is ON-OF after the DC voltage and current are applied to the terminals of the mounting case to raise the heating element 10 to an operating temperature of 400 ° C. in 10 milliseconds and then the power is turned off.
It is the rate of change in resistance when the F test is performed 100,000 times.

[0095]

[Table 2]

In Examples 1 to 3, the platinum heater main thin film and at least one material selected from titanium, zirconium, or chromium, which is thinner than the platinum thin film and is disposed below the platinum thin film, are the main components. It can be seen that the heating element is composed of a metal heater auxiliary thin film and has excellent durability. This excellent durability is due to the following reasons.
Platinum is a material having excellent malleability and heat resistance, and titanium, zirconium, and chromium are materials having excellent bondability and good malleability. When they are laminated, they are well bonded to each other to obtain a heat generating element having malleability, and they are also well bonded to an insulating heat resistant substrate or a heat resistant insulating thin film. When energized, the heating element heats up to the operating temperature in a short time and thermally expands, and the insulating heat-resistant substrate and heat-resistant insulating thin film arranged above and below it also heat up at the same time and thermally expand. This is because the heat-generating body formed as a laminated film satisfactorily follows the thermal expansion of the substrate and the heat-resistant insulating thin film and does not cause peeling or disconnection.

Further, in Examples 1 to 3, since the heat generated by the heating element is effectively transmitted through the thin film of the heat-resistant insulating thin film to the upper gas sensing portion, a pulse of 10 milliseconds is used. When energized, the device was activated and the carbon monoxide gas concentration could be detected, and the amount of power was 18 mW seconds.

The material of the heater main thin film was examined. For the heater main thin film, a platinum-based metal in which 80% by weight or more of platinum and 20% by weight or less of a small amount of rhodium or palladium were mixed was effective.

Next, the optimum film thickness for obtaining the heating element 10 having excellent durability was examined. The film thickness of the metal heater auxiliary fine thin film made of titanium, zirconium, or chromium is optimally 0.03 to 0.002 μm, and particularly optimally 0.02 to 0.003 μm. The reason is that when the thickness of the metal heater auxiliary thin film is large, the brittle characteristics of the metal heater auxiliary thin film are exerted in many cases, resulting in brittle bonding, and a highly malleable heating element cannot be obtained. This is because if the film thickness is thin, bonding cannot be performed and a malleable heating element cannot be obtained. On the other hand, the proper thickness of the platinum heater main thin film is 0.3 to 1.0 μm, and especially 0.4 to 0.4 μm.
˜0.7 μm was optimal. The reason is that if the thickness of the heater main thin film is too large, the resistance becomes too small, which makes it difficult to control the temperature rise and a new problem that the lead wire generates heat. A new problem arises in that if the thickness is thin, heat will be generated partially and disconnection will occur. From the relationship of these film thicknesses, it is appropriate that the thickness of the metal heater auxiliary thin film is 0.1 times or less as large as the film thickness of the heater main thin film, particularly 0.004 to 0.0
It turns out that 5 times is optimal.

Further, optimum firing conditions for obtaining the heating element 10 having excellent durability were examined. The examination was performed using an insulating heat-resistant substrate 17 made of quartz glass. First, a metal heater auxiliary thin film 19 made of titanium, zirconium, or chromium and a heater main thin film 20 made of platinum were sequentially laminated on the upper portion thereof to form the heating element 10.
On top of that, a heat-resistant insulating thin film 1 made of quartz glass
1 was laminated, and the durability of the heater was evaluated for samples fired at different firing temperatures. As a result, it was found that the heating element has a small resistance change rate when fired at 600 ° C. or higher and has excellent durability characteristics. This is because by firing at 600 ° C. or higher, a heat generating element having malleability can be obtained by being well bonded to the insulating heat resistant substrate or the heat resistant insulating thin film. Especially 700 ~
Baking at 1050 ° C. provided a heating element with the highest durability. On the other hand, if the firing temperature is lower than 600 ° C., for example, 550 ° C., it is difficult to obtain a heat generating element having malleability because it does not bond well to the insulating heat resistant substrate or the heat resistant insulating thin film, and the resistance change rate is slightly increased.

The optimum firing temperature of the heating element 10 is 600.
The result of not less than 0 ° C. is a result obtained from the physical properties of titanium and zirconium or chromium used as the auxiliary thin film for the metal heater, and the value does not change significantly as long as this material is used. In order to achieve the optimum firing temperature of 600 ° C. or higher for the heating element that achieves this excellent durability, the insulating heat-resistant substrate 17, the heat-resistant insulating thin film 18, and the gas sensing unit 11 that form the gas sensor element 9 are used.
Is required to have heat resistance sufficiently higher than the lower limit of the optimum firing temperature of 600 ° C, and as a result of studying the lower limit of the heatproof temperature, the optimum lower limit of firing temperature of 600 ° C is at least 50 ° C.
It has been found that heat resistance of at least 650 ° C., which is a high temperature, is required.

For comparison, an insulating heat-resistant substrate in which an insulating thin film made of silicon oxide and silicon nitride is formed on the surface of a silicon wafer is used, and titanium and platinum are laminated on the upper part in order from the lower part. When a gas sensor element having a heating element of the mold was prototyped and the above-mentioned ON-OFF test was conducted, the conventional heating element was broken after 10,000 times.
This is because this silicon wafer-based substrate has a heat resistance of about 300 to 400 ° C. at the most, and the application of heat at 600 ° C. during the sensor production remarkably generated a new oxide having poor adhesion on the surface. The reason is that the heating element was peeled off and disconnected during the pulse energization. From this point of view, after that, it was considered that the material forming the gas sensor element needs to have a heat resistance of at least 650 ° C.

The insulating heat resistant substrate 17 was examined. As a result, a crystallized glass plate having a physical property of a thermal expansion coefficient of 6.8 × 10 ⁻⁶ deg ⁻¹ at a transition temperature of 720 ° C., a softening temperature of 900 ° C., and a crystallized glass film (thickness 70 μm) made of an alumina heat-resistant material. Even when a ceramic substrate such as a substrate laminated on the plate or a cordierite substrate was used, similar excellent heater durability characteristics were obtained. In addition, as the heat-resistant insulating thin film 18,
Even when ceramics such as alumina and silicon nitride and various glasses were used, similar excellent heater durability characteristics were obtained.

(Example 8) In Example 8, the physical properties of the glass used for the insulating heat-resistant substrate 17 were examined. Since the glass substrate is an insulating heat-resistant substrate with a very low thermal conductivity, only a small amount of heat generated by the heating element is transferred to the insulating heat-resistant substrate, and most of it is transferred to the gas sensing unit. There is an advantage that the gas sensor element 11 that can reach the temperature of 400 ° C. with a small amount of electric power and that has a reduced power consumption can be realized.
However, glass has the property that when the temperature rises, when it expands at a constant rate according to its coefficient of thermal expansion, its volume expands rapidly at a certain temperature. The temperature at which this volume expands rapidly is called the transition temperature, and there is a concern that the heating element 10 or the like laminated on the upper part may be damaged by this volume expansion, so the effect of this transition temperature was examined.

A study was conducted by using an insulating heat-resistant substrate 17 having different transition materials and different transition temperatures, and a metal heater auxiliary thin film 19 made of chromium and a heater main thin film 20 made of platinum were sequentially provided on the insulating heat-resistant substrate 17. A heat-generating body 10 is formed by stacking layers, a heat-resistant insulating thin film 18 made of quartz glass is further stacked, and finally, the solid electrolyte type gas sensing unit 11 is stacked.
The gas sensor element 9 was used.

FIG. 7 shows the change characteristics of the resistance of the heating element measured by changing the transition temperature by changing the material of the glass, and shows the correlation characteristics of the transition temperature of the glass and the resistance changing rate of the heating element. The resistance change rate of the heating element 10 is determined by applying a direct current voltage and current to the terminals of the mounting case to keep the heating element 10 at an operating temperature of 400 ° C.
Up in 10 milliseconds and then turn off the power ON-O
It is the rate of change in resistance when the FF test is performed 100,000 times.

The insulating heat-resistant substrate of Example 1 was made of quartz glass and had a transition temperature of 1075 ° C. and a thermal expansion coefficient of 0.5.
× 10 ^-6 (1 / deg).

The insulating heat-resistant substrate of Example 2 was 96%.
It is a silicate glass and has a transition temperature of 890 ° C. and a thermal expansion coefficient of 0.8 × 10 ⁻⁶ (1 / deg).

The insulating heat-resistant substrate of Example 3 was borosilicate alumina glass and had a transition temperature of 850 ° C. and a thermal expansion coefficient of 1.3 × 10 ⁻⁶ (1 / deg).

The insulating heat resistant substrate No. 4 of this example is a crystallized glass, the transition temperature is 750 ° C., and the thermal expansion coefficient is 9.4.
It is (1 / deg) in × 10 ⁻⁶ .

The insulating heat-resistant substrate of Example 5 was aluminosilicate glass and had a transition temperature of 650 ° C. and a thermal expansion coefficient of 4.2 × 10 ⁻⁶ (1 / deg).

The insulating heat resistant substrate of the comparative example is soda lime glass, the transition temperature is 620 ° C., and the thermal expansion coefficient is 5.2 ×.
It is (1 / deg) at 10 ⁻⁶ .

As can be seen from FIG. 7, the resistance change rate of the heating element is 65 when the transition temperature of the glass material used for the insulating heat-resistant substrate is 65.
It can be seen that the temperature changes at 0 ° C. Since the insulating heat-resistant substrate of the present invention is a glass material whose transition temperature exceeds 650 ° C., even if the heating element is fired at the optimum lower limit firing temperature of 600 ° C. Bonding gives excellent durability characteristics.

Further, since it is an insulating heat resistant substrate made of a glass material having a very low thermal conductivity, the heat generated by the heating element is transferred only slightly to the insulating heat resistant substrate, and most of it is transferred to the gas sensing unit. To be done. Therefore, the operating temperature can be reached with a small amount of power, and a gas concentration detection device with further reduced power consumption can be realized. Further, as a result of this, since the heating element consumes less power, the value of applied voltage and current becomes smaller, and the effect of further excellent durability characteristics is obtained.

On the other hand, when a glass material having a transition temperature of 620 ° C. is used as the insulating heat-resistant substrate, the heating element is well bonded to the insulating heat-resistant substrate even if the heating element is fired at the optimum lower firing temperature of 600 ° C. A slight decrease in durability is observed. This is because the glass material transition temperature of 620 ° C. is close to the heating element firing temperature of 600 ° C., and the glass material transition (a sudden volume change) hinders the adhesion of the heating element. is there.

The same effect can be obtained by using, as the heating element 10, a structure in which a platinum-based heater main thin film and a metal heater auxiliary fine thin film of titanium, zirconium, or chrome at least disposed under the platinum-based heater thin film are stacked. It was

(Example 9) From the results of Example 8 described above,
It can be seen that when quartz glass is used as the insulating heat resistant substrate, it has excellent durability characteristics. Therefore, in Example 9, the composition of the quartz glass used for the insulating heat-resistant substrate was examined. Quartz glass is a glass whose main component is silicic acid (SiO ₂ ), but contains a small amount of hydroxyl groups (referred to as OH groups). Therefore, we analyzed the effect of insulating heat-resistant substrates made of quartz glass with different hydroxyl group contents.

The examination was performed by using an insulating heat-resistant substrate 17 made of quartz glass having different hydroxyl group contents, and sequentially laminating a metal heater auxiliary thin film 19 made of chromium and a heater main thin film 20 made of platinum on the upper surface of the substrate. Then, the heat-generating body 10 was formed, and the heat-resistant insulating thin film 18 made of quartz glass was further laminated and fired. Finally, the gas sensor element 9 in which the solid electrolyte type gas sensing unit 11 was laminated was used.

The insulating heat-resistant substrate of 1 of this example is 0.0
Quartz glass containing 1 wt% of hydroxyl group, and its safe use temperature is 1050 ° C.

The insulating heat-resistant substrate of Example 2 was 0.0.
Quartz glass containing 4 wt% of hydroxyl groups, and its safe use temperature is 1000 ° C.

The insulating heat-resistant substrate of Example 3 was 0.1.
Quartz glass containing 2 wt% of hydroxyl group, and its safe use temperature is 950 ° C.

The insulating heat-resistant substrate of Example 4 was 0.2.
Quartz glass containing 0 wt% of hydroxyl group, and its safe use temperature is 900 ° C.

The insulating heat-resistant substrate of Comparative Example 2 has 0.25 w.
Quartz glass containing t% of hydroxyl groups, and its safe use temperature is 800 ° C.

FIG. 8 is a graph showing the correlation characteristics between the hydroxyl group content of quartz glass and the resistance change rate, in which the resistance change rate of the heating element is measured by changing the hydroxyl group content of the quartz glass. Regarding the resistance change rate of the heating element, a DC voltage / current was applied to the terminals of the mounting case to allow the heating element to reach an operating temperature of 400 ° C. in 10 milliseconds, and then the power was turned off and an ON-OFF test was performed 100,000 times. This is the rate of change in resistance at that time.

It can be seen that the resistance change rate of the heater changes when the hydroxyl group contained in the quartz glass is 0.20 wt%. The product of the present invention has 0.20 hydroxyl groups contained in quartz glass.
Since it is less than wt%, the chromium metal heater auxiliary thin film adheres well to the quartz glass, and more excellent durability characteristics can be obtained. In addition, since quartz glass, which has a very small coefficient of thermal expansion, is used as the insulating heat-resistant substrate, the thermal expansion of the insulating heat-resistant substrate due to the heat generation of the heating element is reduced, and the heating element is also insulated It adheres to the substrate even better and provides excellent durability characteristics. Furthermore, since it is an insulating heat-resistant substrate made of quartz glass having a very small thermal conductivity, the heat generated by the heating element is transferred only slightly to the insulating heat-resistant substrate, and most of it is transferred to the gas sensing unit. Therefore, the operating temperature can be reached with a small amount of power, and a gas concentration detection device with further reduced power consumption can be realized.

Further, since the heating element consumes less power, the value of applied voltage and current becomes smaller, which brings about an effect that more excellent durability characteristics can be obtained. In addition to this, when the hydroxyl group contained in the quartz glass is 0.20 wt% or less, high temperature treatment can be applied to the formation of the heat resistant insulating thin film to be laminated thereon, and the heat resistant insulating thin film with few defects can be formed. Is generated, and excellent insulation characteristics can be secured. Therefore, the oxygen ion conductive solid electrolyte thin film is less affected by the heating element and exhibits good oxygen ion conductivity at an appropriate operating temperature of 400 ° C. Due to this effect, the gas sensing unit consisting of the oxygen ion conductive solid electrolyte thin film, the electrode film and the oxidation catalyst film is heated in a short time by the heating element placed underneath to become the operating state, and warming up in an extremely short time. There is also an advantage.

On the other hand, the hydroxyl group contained in quartz glass is 0.2
If it exceeds 0 wt%, it is difficult to adhere the chromium metal heater auxiliary thin film to the quartz glass, and it is observed that the durability is lowered to some extent.

The same effect can be obtained by using, as the heating element 10, a structure in which a platinum heater main thin film 20 and a metal heater auxiliary fine thin film 19 of titanium, zirconium, or chrome, which is disposed at the bottom thereof, are laminated. Was obtained.

Example 10 In Example 10, the center line surface roughness of the insulating heat resistant substrate 17 was examined. The examination is
On the upper side of the insulating heat-resistant substrate 17 made of quartz glass with the center line surface roughness changed, a metal heater auxiliary thin film 1 made of chromium is formed.
9 and a heater main thin film 20 made of platinum are sequentially laminated to form a heating element 10, a heat-resistant insulating thin film 18 made of quartz glass is further laminated and fired, and finally, the solid electrolyte type gas sensing unit described above. The gas sensor element 9 in which 11 is laminated is used.

An ON-OFF energization test was conducted on the gas sensor element using the insulating heat resistant substrate 17 with the center line surface roughness varied, and the rate of resistance change of the heating element was measured. FIG. 9 is a characteristic diagram in which the correlation characteristics of the center line surface roughness and the resistance change rate are arranged. The resistance change rate of the heating element is ON-OF in which the DC voltage and current are applied to the terminals of the mounting case to make the heating element 10 reach the operating temperature of 400 ° C. in 10 milliseconds, and then the power is turned off.
It is the rate of change in resistance when the F test is performed 100,000 times.

As can be seen from FIG. 9, the rate of resistance change greatly changes when the center line surface roughness is 0.05 μm or 1 μm. Since the center line surface roughness of the product of the present invention is 0.05 to 1 μm, the heating element is well adhered to the insulating heat-resistant substrate by firing and excellent durability characteristics are obtained.

On the other hand, when the insulating heat-resistant substrate having a center line surface roughness of less than 0.05 μm or more than 1 μm is used, the heating element does not adhere well to the insulative heat-resistant substrate even if it is fired, and the durability is somewhat deteriorated. To be observed.

The above results indicate that the insulating heat-resistant substrate 17 is a crystallized glass plate having physical properties such as a transition temperature of 720 ° C., a softening temperature of 900 ° C. and a thermal expansion coefficient of 6.8 × 10 ⁻⁶ deg ^−1. The same was true when using a ceramic substrate such as a substrate in which a crystallized glass film (film thickness 70 μm) was laminated on an alumina heat-resistant plate, or a cordierite substrate. The same effect was obtained when ceramics such as alumina and silicon nitride and various glasses were used as the heat-resistant insulating thin film 18. Further, the same effect can be obtained by using, as the heating element 10, a structure in which a platinum heater main thin film and a metal heater auxiliary fine thin film of titanium, zirconium, or chrome, which is at least disposed under the platinum main thin film, are laminated.

(Embodiment 11) In Embodiment 11, a material forming the heat resistant insulating thin film 18 was examined.

When glass is used as the heat-resistant insulating thin film 18, even if the heating element 10 generates heat and thermally expands, it engages with the property of the glass that is extremely strong against the compressive stress, and follows the thermal expansion well. A heating element 10 that does not break and has excellent durability characteristics
May be realized. However, glass has the property that when the temperature rises, when it expands at a constant rate according to its coefficient of thermal expansion, its volume expands rapidly at a certain temperature. The temperature at which this volume expands rapidly is called the transition temperature, and there is a concern that this rapid volume expansion may damage the heating element 10 or the like stacked on top of it.
The effect of this transition temperature was examined.

In the examination, a metal heater auxiliary fine thin film 19 made of chromium and a platinum heater main thin film 20 were sequentially formed on the insulating heat resistant substrate 17 made of quartz glass by a sputtering method.
The gas sensor element 9 is formed by stacking 6 μm to form the heating element 10, and further stacking the heat-resistant insulating thin film 18 made of glass having a different transition temperature by about 2 μm, and finally forming the solid electrolyte type gas sensing unit 11 and stacking the same. went.

FIG. 10 is a graph showing the correlation characteristics between the transition temperature and the resistance change rate, in which the transition temperature is changed by changing the glass material and the resistance change rate is measured. Regarding the resistance change rate of the heating element, a DC voltage / current was applied to the terminals of the mounting case to raise the heating element to an operating temperature of 400 ° C. in 10 milliseconds, and then the power was turned off and an ON-OFF test was conducted 100,000 times. This is the rate of change in resistance at that time.

The heat-resistant insulating thin film of Example 1 was made of quartz glass and had a transition temperature of 1075 ° C. and a thermal expansion coefficient of 0.5.
× 10 ^-6 (1 / deg).

The heat resistant insulating thin film of Example 2 was 96%.
It is a silicate glass and has a transition temperature of 890 ° C. and a thermal expansion coefficient of 0.8 × 10 ⁻⁶ (1 / deg).

The heat-resistant insulating thin film of Example 3 was borosilicate alumina glass, and had a transition temperature of 850 ° C. and a thermal expansion coefficient of 1.3 × 10 ⁻⁶ (1 / deg).

The heat-resistant insulating thin film of Example 4 was aluminosilicate glass and had a transition temperature of 750 ° C. and a thermal expansion coefficient of 4.4 × 10 ⁻⁶ (1 / deg).

The heat-resistant insulating thin film of Example 5 was aluminosilicate glass, had a transition temperature of 650 ° C. and a coefficient of thermal expansion of 4.2 × 10 ⁻⁶ (1 / deg).

The heat-resistant insulating thin film of the comparative example is soda-lime glass, the transition temperature is 620 ° C., and the thermal expansion coefficient is 5.2 ×.
It is (1 / deg) at 10 ⁻⁶ .

As can be seen from FIG. 10, the resistance change rate of the heating element is 6 when the transition temperature of the glass material used for the heat-resistant insulating thin film is 6
It can be seen that the temperature changes at 50 ° C. Since the heat-resistant insulating thin film of the present invention is a glass material whose transition temperature exceeds 650 ° C., even if the heating element is fired at the optimum firing temperature of 600 ° C., the heating element adheres well to the heat-resistant insulating thin film. And excellent durability characteristics are obtained.

On the other hand, when a glass material having a transition temperature of 620 ° C. is used as the heat-resistant insulating thin film, the optimum firing temperature is 60
Even if the heating element is fired at 0 ° C., the heating element does not adhere well to the heat-resistant insulating thin film, and some decrease in durability is observed. This is because the transition temperature 620 ° C. of the glass material is the firing temperature 6 of the heating element.
This is because the temperature is close to 00 ° C. and the transition of the glass material (a sudden volume change occurs) hinders the adhesion of the heating element.

The above results show that the insulating heat-resistant substrate 17 has a transition temperature of 720 ° C., a softening temperature of 900 ° C. and a thermal expansion coefficient of 6.8 × 10 ⁻⁶ deg ^−1. The same was true when using a ceramic substrate such as a substrate in which a crystallized glass film (film thickness 70 μm) was laminated on an alumina heat-resistant plate, or a cordierite substrate. The same effect was obtained when ceramics such as alumina and silicon nitride and various glasses were used as the heat-resistant insulating thin film 18. Further, the same effect can be obtained by using, as the heating element 10, a structure in which a platinum heater main thin film and a metal heater auxiliary fine thin film of at least titanium, zirconium, or chrome disposed at the lower portion thereof are laminated.

Example 12 In Example 12, the material of the heat resistant insulating thin film 18 was examined in more detail.

The examination is the same as in the above-mentioned Example 11,
The results are shown in (Table 3).

The heat-resistant insulating thin film of the first invention is a quartz glass film having a thickness of 2.0 μm.

The heat resistant insulating thin film of Comparative Example 1 is a laminated film in which a quartz glass film having a thickness of 1.5 μm is formed on the heating element side and an alumina film having a thickness of 0.5 μm is laminated on the quartz glass film.

The heat-resistant insulating thin film of Comparative Example 2 is a laminated film in which an alumina film having a thickness of 0.5 μm is formed on the heating element side and a quartz glass film having a thickness of 1.5 μm is laminated on the alumina film.

[0152]

[Table 3]

This example is a heat-resistant insulating thin film using quartz glass, and its rate of change in resistance is smaller than that of the other materials as shown in (Table 3), and it has excellent durability characteristics. This is because the heater main thin film is well adhered to the insulating heat-resistant substrate made of quartz glass to obtain excellent durability characteristics.

The above results show that the insulating heat-resistant substrate 17 has a transition temperature of 720 ° C., a softening temperature of 900 ° C., and a thermal expansion coefficient of 6.8 × 10 ⁻⁶ deg ^−1. The same was true when using a ceramic substrate such as a substrate in which a crystallized glass film (film thickness 70 μm) was laminated on an alumina heat-resistant plate, or a cordierite substrate. The same effect was obtained when ceramics such as alumina and silicon nitride and various glasses were used as the heat-resistant insulating thin film 18. Further, the same effect can be obtained by using, as the heating element 10, a structure in which a platinum heater main thin film and a metal heater auxiliary fine thin film of titanium, zirconium, or chrome, which is at least disposed under the platinum main thin film, are laminated.

Example 13 In Example 13, the thermal conductivity of the oxygen ion conductive solid electrolyte thin film 21 was examined when a solid electrolyte type gas sensing section was used as the gas sensing section 11.

The examination is made by sequentially stacking a metallic heater auxiliary thin film 19 made of chromium and a platinum heater main thin film 20 on the insulating heat-resistant substrate 17 made of quartz glass to form the heating element 10, which is made of quartz glass. After the heat-resistant insulating thin film 18 was further laminated and fired, finally, a gas sensor element in which a solid electrolyte type gas sensing unit 11 described later was laminated was used.

The solid electrolyte type gas sensing portion 11 includes an oxygen ion conductive solid electrolyte thin film 21, and breathable first electrode thin film 22 and second electrode thin film 23 formed on the same surface thereof.
The following two material configurations are provided at least.

The material constitution (I) is as follows. The first electrode thin film 22 and the second electrode thin film 23 are breathable thin films (film thickness 0.6 μm) formed by sputtering platinum.
Thermal expansion coefficient is 9 × 10 ^-6 (1 / deg) and thermal conductivity is 69.
It has a physical property value of 5 W / mK. The oxidation catalyst film 24 is laminated on the first electrode thin film 22, and is a breathable thick film printing type thin film (film thickness 10 μm) in which a platinum catalyst is carried on the surface of silica-alumina-based crystallization glass. The main component is a material having a physical property value of conductivity of 1.0 W / mK.

The material constitution (II) is as follows. The first electrode thin film 22 is made of lanthanum manganese oxide (LaMn).
O ₃₎ as main components breathable thick film printing type thin (thickness 1
0 μm), and this metal oxide is a perovskite type having oxygen ion conductivity and electronic conductivity. The second electrode thin film 23 is a breathable sputtered thin film (having a thickness of 0.6 μm) containing gold as a main component. The oxidation catalyst film was not laminated.

The oxygen ion conductive solid electrolyte thin film of Comparative Example 1 is yttrium-based partially stabilized zirconia with cerium added, and since the crystal grain size is refined to nano-order, its thermal conductivity is 0.8 W / mK, The composition is a solid solution of 96 mol% ZrO _2, 3 mol% Y ₂ O ₃ and 1 mol% CeO ₂ .

The oxygen ion conductive solid electrolyte thin film of Example 1 of the present invention is scandium-added ceria-based zirconia, and since the crystal grain size is miniaturized to nano-order, its thermal conductivity is 1.0 W / mK, composition. Is ZrO ₂ 90 mol% and C
It is a solid solution of 10 mol% of eO _{2 and} 10 mol% of Sc ₂ O ₃ .

The oxygen ion conductive solid electrolyte thin film of Example 2 was yttrium-based partially stabilized zirconia and had a thermal conductivity of 3.0 W / mK and its composition was ZrO _2.
It is a solid solution of 97 mol% and Y ₂ O ₃ 3 mol%.

The oxygen-ion conductive solid electrolyte thin film of Example 3 was yttrium-stabilized zirconia and had a thermal conductivity of 5.0 W / mK, and its composition was ZrO ₂ 92 mol% and Y ₂ O _3. It is a solid solution of 8 mol%.

The oxygen ion conductive solid electrolyte thin film of Example 4 was a ceria-based material doped with yttria and had a thermal conductivity of 6.5 W / mK, and its composition was (CeO 2).
_{2) 1-0 .7} (YO _1.5) is _0.3.

The oxygen ion conductive solid electrolyte thin film of Example 5 was a samarium-doped ceria-based material and had a thermal conductivity of 7.0 W / mK and a composition (CeO ₂ ).
_0.8 (SmO _1.5 ) _0.2 .

The insulating heat-resistant substrate of Comparative Example 2 was yttrium-based bismuth oxide, which had a thermal conductivity of 10 W / mK and a solid solution of 96 mol% Bi ₂ O ₃ and 4 mol% Y ₂ O _3. .

A gas sensor element using an oxygen ion conductive solid electrolyte thin film having different thermal conductivity was subjected to an ON-OFF energization test, and the resistance change rate of the heating element was measured. FIG. 11 shows
It is a characteristic view which arranged the correlation characteristic of thermal conductivity and resistance change rate of the oxygen ion conductive solid electrolyte thin film. For the resistance change rate of the heating element, a DC voltage / current is applied to the terminals of the mounting case to heat the heating element 10 up to an operating temperature of 400 ° C. in 10 milliseconds, and then the power is turned off. It is the rate of change in resistance when the test is performed.

As can be seen from FIG. 11, the rate of resistance change greatly changes when the thermal conductivity of the oxygen ion conductive solid electrolyte thin film is less than 1 W / mK and exceeds 7 W / mK. Since the product of the present invention has a thermal conductivity of 1 to 7 W / mK, the oxygen ion conductive solid electrolyte thin film radiates heat well, and the temperature rise of the heating element is suppressed, and excellent durability characteristics are obtained.

On the other hand, when the thermal conductivity is less than 1 W / mK, heat radiation from the oxygen ion conductive solid electrolyte thin film is poor,
It was observed that the temperature of the heating element increased and the durability was somewhat lowered. Also, when the thermal conductivity exceeds 7 W / mK, the heat dissipation from the oxygen ion conductive solid electrolyte thin film is good, so a large current flows to keep the temperature of the heating element, and some decrease in durability is observed. It was

The above results show that the insulating heat-resistant substrate 17 has a transition temperature of 720 ° C., a softening temperature of 900 ° C., and a thermal expansion coefficient of 6.8 × 10 ⁻⁶ deg ^−1. The same was true when using a ceramic substrate such as a substrate in which a crystallized glass film (film thickness 70 μm) was laminated on an alumina heat-resistant plate, or a cordierite substrate. The same effect was obtained when ceramics such as alumina and silicon nitride and various glasses were used as the heat-resistant insulating thin film 18. Further, the same effect can be obtained by using, as the heating element 10, a structure in which a platinum heater main thin film and a metal heater auxiliary fine thin film of titanium, zirconium, or chrome, which is at least disposed under the platinum main thin film, are laminated.

(Example 14) In Example 14, the chemical properties of the electrode film in the solid electrolyte type gas sensing section used as the gas sensing section 11 were examined.

The content of the examination is the same as that of the above-mentioned Example 13, except that the transient change of the sensor output when the solid electrolyte type gas sensing portion having two different types of electrode thin films is pulsed is measured. . The material constitution (I) is that both the first electrode thin film 22 and the second electrode thin film 23 are platinum sputtered thin films, and the platinum catalyst-supported silica-alumina-based crystallization glass oxidation catalyst film 24 is replaced by the first electrode thin film 22. Stacked on top. In the material configuration (II), the first electrode thin film 22 is a thick film printing type thin film of lanthanum manganese oxide (LaMnO ₃ ) and the second electrode thin film 23 is a gold sputtered thin film.

The material structure (II) had a smaller transient change in the sensor output when a pulse current was applied than the material structure (I), and had excellent durability and reliability. Also,
As can be seen from FIG. 11, the material composition (II) had a smaller resistance change rate than the material composition (I).

[0174]

In order to solve the above-mentioned problems, the gas concentration detecting device of the present invention intermittently supplies pulse power to the heating element and a gas sensor element having at least a gas sensing portion at intervals (A). Power pulse supply means, sensor output detection means for detecting the sensor output from the gas sensing unit, power pulse elapsed time measurement means for measuring the elapsed time from the start of pulsed power supply, and the measured elapsed time for a predetermined time Drive initial corresponding power supply means for performing control to supply pulse power at a short interval (B) when less than (I),
At least have it.

When the gas sensor element is restarted, the drive initial corresponding power supply means operates to instruct the power pulse supply means to supply the pulse power to the heating element at a short interval (B). The aging process is accelerated. Then, when a predetermined time (I) at which the sensor output stabilizes is reached, the drive initial corresponding power supply means stops, and the power pulse supply means supplies pulse power to the heating element at the normal interval (A).

As a result, the stabilization of the gas sensor element is accelerated, so that a gas concentration detecting device with high detection accuracy can be obtained in a short time. Further, since the electric power is supplied to the heat generating element in pulses, the gas concentration detecting device is of a power saving type.

The heating element of the gas sensor element used in the gas concentration detecting device of the present invention is composed of a heater main thin film containing platinum as a main component and titanium or a titanium thin film arranged under the heater main thin film with a thickness of 0.1 times or less. It is composed of a metal heater auxiliary fine thin film whose main component is at least one material selected from zirconium or chromium.

Since it is a heating element composed of two layers of a platinum heater main thin film and a metal heater auxiliary thin film of titanium, zirconium, chromium or the like disposed below the platinum heater thin film, durability reliability is improved. It becomes an excellent heating element and can always raise the temperature to a predetermined operating temperature. Therefore, a small power-saving type gas sensor element that can obtain a stable sensor output for a long period of time and is excellent in detection accuracy can be obtained forever.

[Brief description of drawings]

FIG. 1 is a flow chart showing a configuration diagram and a processing flow of a gas concentration detection device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a gas sensor element used in the gas concentration detecting device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a gas concentration detecting device according to a second embodiment of the present invention and a flowchart showing a processing flow.

FIG. 4 is a configuration diagram of a gas concentration detecting device according to a third embodiment of the present invention and a flowchart showing a processing flow.

FIG. 5 is a configuration diagram of a gas concentration detecting device according to a fourth embodiment of the present invention and a flowchart showing a processing flow.

FIG. 6 is a configuration diagram of a gas concentration detecting device according to a fifth embodiment of the present invention and a flowchart showing a processing flow.

FIG. 7 is an effect characteristic diagram of the gas sensor element of the present invention (correlation between the transition temperature of the glass material used for the insulating heat-resistant substrate and the resistance change rate of the heating element).

FIG. 8 is a graph showing the effect characteristics of the gas sensor element of the present invention (correlation between hydroxyl group content in quartz glass and resistance change rate of heating element).

FIG. 9 is a graph showing the effect characteristics of the gas sensor element of the present invention (correlation between center line surface roughness of insulating heat-resistant substrate and resistance change rate of heating element).

FIG. 10 is an effect characteristic diagram of the gas sensor element of the present invention (correlation between the transition temperature of the glass material used for the heat-resistant insulating thin film and the resistance change rate of the heating element).

FIG. 11 is an effect characteristic diagram of the gas sensor element of the present invention (correlation between thermal conductivity of oxygen ion conductive solid electrolyte thin film and resistance change rate of heating element).

FIG. 12 is a configuration diagram of a conventional gas concentration detector and a gas sensor element used for the same.

[Explanation of symbols]

9 Gas sensor element 10 heating element 11 Gas sensing unit 12 Power pulse supply means 13 Sensor output detection means 14 Controller 15 Power pulse elapsed time measuring means 16 Power supply means for initial drive 17 Insulating heat resistant substrate 18 Heat-resistant insulating thin film 19 Metal heater auxiliary thin film 20 Heater main thin film 21 Oxygen ion conductive solid electrolyte thin film 22 First electrode thin film 23 Second electrode thin film 24 Oxidation catalyst membrane

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuhiko Uno             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Takashi Niwa             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Takahiro Umeda             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2G004 BB04 BC02 BE12 BE22 BF07                       BH08 BJ02 BJ03 BJ09 BJ10                       BL08 BL14 BL19 BM04 BM07                       BM09

Claims (14)

[Claims] 1. A gas sensor element having at least a heating element and a gas sensing section, a power pulse supplying means for intermittently supplying pulsed power to the heating element at intervals (A), and a power pulse generated by the power pulse supplying means. And a sensor output detection means for detecting a sensor output from the gas sensing unit, wherein the controller measures the elapsed time from the start of pulse supply by the power pulse supply means. It comprises at least a time measuring means and a drive initial corresponding power supply means for controlling the interval of the power pulse to be short at the initial stage of driving, and the drive initial corresponding power supply means is the progress measured by the power pulse elapsed time measuring means. When the time is less than the predetermined time (I), the pulse power of the power pulse supply means is set at an interval (B) shorter than the interval (A). A gas concentration measuring apparatus which performs control of the sheet. 2. The controller further comprises a sensor output abnormality determining means for determining whether or not there is an abnormality in the sensor output, and an abnormality response power supply means for controlling the power pulse interval to be short when the sensor output has an abnormality. The abnormal power supply means determines that the sensor output abnormality determination means determines that the sensor output is abnormal because the elapsed time measured by the power pulse elapsed time measurement means is equal to or longer than the predetermined time (I) and less than the predetermined time (II). 2. The gas concentration detecting device according to claim 1, wherein the pulse power of the power pulse supplying means is controlled to be supplied at an interval (C) shorter than the interval (A). 3. The emergency pulse supply means further provided in the controller, wherein the sensor output abnormality determination means abnormally detects the sensor output when the elapsed time measured by the power pulse elapsed time measurement means reaches a predetermined time (II). If you judge that
The gas concentration detector according to claim 1, wherein the heating element is restarted at the interval (B) in the power pulse supply means. 4. The gas concentration detection device according to claim 3, wherein an alarm is issued when the emergency pulse supply means operates a plurality of times. 5. The gas detection time pulse supply means further provided in the controller has a threshold value predetermined by the sensor output abnormality determination means when the elapsed time measured by the power pulse elapsed time measurement means is a predetermined time (II) or more. 2. The gas concentration detecting device according to claim 1, wherein when the sensor output is determined to be abnormal within the output, control is performed to supply pulse power to the power pulse supply means at an interval (D) shorter than the interval (A). 6. The gas detection time pulse supply means, when the elapsed time measured by the power pulse elapsed time measurement means is a predetermined time (II) or more, the sensor output abnormality determination means exceeds the sensor output above a predetermined threshold output. If you decide that
The gas concentration detecting device according to claim 5, wherein the heating element is restarted at the interval (B) in the power pulse supply means. 7. A heat-insulating thin film, a heat-insulating thin film, and a gas sensing part, which are laminated in this order from the bottom on an upper surface of an insulating heat-resistant substrate, and the heat-generating body contains platinum as a main component. Of the heater main thin film and the heater main thin film of 0.
A gas sensor element having a film thickness that does not exceed 1 time, and a metal heater auxiliary thin film mainly composed of at least one material selected from titanium, zirconium, and chromium disposed below the film sensor element. 8. The gas sensor element according to claim 7, wherein the insulating heat-resistant substrate is a glass material having a transition temperature of at least 650 ° C. or higher. 9. The insulating heat-resistant substrate has a hydroxyl group of 0.20 w.
The gas sensor element according to claim 7, wherein the gas sensor element is silica glass containing not more than t%. 10. The gas sensor element according to claim 7, wherein the insulating heat-resistant substrate has a center line surface roughness of 0.05 to 1 μm. 11. The heat resistant insulating thin film is a glass material having a transition temperature of at least 650 ° C. or higher.
The gas sensor element described. 12. The gas sensor element according to claim 7, wherein the heat-resistant insulating thin film is quartz glass. 13. The gas sensing unit includes at least an oxygen ion conductive solid electrolyte membrane, and a gas permeable first electrode film and a second electrode film disposed above the oxygen ion conductive solid electrolyte thin film, The gas sensor element according to claim 7, wherein the ion conductive solid electrolyte membrane is a material having a thermal conductivity of 1 to 7 W / mK. 14. The gas sensor element according to claim 13, wherein the first electrode film is an electrode film having an excellent oxidation catalyst property, and the second electrode film is an electrode film having an oxidation catalyst property inferior to the first electrode film.