JPH02147916A - Heat generating structure of sensor - Google Patents

Abstract

PURPOSE:To improve the response to a change in an ambient temperature by providing a detection means to detect a change in heating value at a center part of a heat generating film body formed on a substrate or providing a heating means to heat near an rim of the heat generating body formed on the substrate. CONSTITUTION:When a change in heating value is detected only with a central heat generating film body 6b at the center part of a heat generating film body 6, a ratio of a heat generating part increases with respect to a part thermally diffusing to alloy a change in heating value only by a part with better property of following a temperature change. Hence, abetter responsiveness is achieved to a change in an ambient temperature. When a heating is made near an end rim of the heat generating body 6 with a heater, a ratio of a heal generating part increases with respect to a part thermally diffusing even at the end rim thereof 6. Thus, the same heat generating conditions are achieved with the center part of the heat generating film body 6 thereby improving a responsiveness to a change in ambient temperature for the heat generating film body 6 as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a heater section of a sensor that detects various physical phenomena 1 based on changes in the amount of heat generated.

[Prior Art] Conventionally, in the case of a heat generating part structure of such a sensor, for example, a flow rate measurement sensor disposed in a fluid passage, the present applicant has developed a temperature compensation structure on a substrate in order to make it suitable for mass production. An application was filed (Japanese Patent Application No. 63-49269) in which a resistor and a resistance heating element were formed, that is, as shown in FIG.
2 is formed into a thin film pattern, and the flow rate of the fluid is determined from the supplied power value when the temperature difference between the two is controlled to be constant. The resistance heating element 52 is used to measure the flow rate of the fluid based on the power supply that determines the amount of heat supplied by the heating element based on the principle that the larger the flow rate, the more heat is removed.The temperature compensation RFI resistor 53 is This is to compensate for the fact that the heat generation rate of the resistance heating element 52 changes depending on the fluid temperature.

Incidentally, in order to reduce the heat capacity of the resistance heating element 52 and to insulate the resistance heating element 52 and the temperature compensation resistor 53 from each other, an elongated heat insulation hole 54 is provided between the two. Further, for the resistance heating element 52, a conductive pattern 55
Power is supplied through the device, which generates heat.

[Problems to be Solved by the Invention] By the way, the temperature distribution of the resistance heating element 52 is
The temperature is not uniform throughout, and as shown in Figure 1B, the temperature is lower at the edges. This is because the area of the sensor substrate 51 and the like where heat is diffused is wider at the edges than at the center, and the amount of heat removed is correspondingly greater. In other words, the ratio of the heat generating part to the part where heat diffuses, that is, the ratio of the area of the sensor board 51 to the vicinity of the resistance heating element 52 per unit area becomes larger at the edge, and the heat capacity becomes larger. It takes time for the temperature change in the heat diffusion part to be transmitted to the heat generating part, and the response when the flow rate changes suddenly and the temperature changes becomes very poor at the edges.

In order to improve this response, it is conceivable to make the part of the sensor board 51 where the resistance heating element 52 is provided thinner or thinner, but this would reduce the mechanical strength of the sensor itself. It's been a long time since I've been in the middle of a long time.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a structure of a heat generating part on a substrate that has good responsiveness to temperature changes.

Means for Solving the Problem] In order to achieve the above object, the present invention includes a configuration in which a detection means for detecting a change in the amount of heat generated in the central portion of the heat generating film formed on the base is provided; Alternatively, a heating means is provided for heating the vicinity of the edge of the heat-generating film formed on the base.

[Function] With the above detection means, changes in the amount of heat generated can be detected only in the central part of the heat generating film body, which has a large ratio of the heat generating part to the part where heat diffuses and has good followability to temperature changes, and can detect changes in the surrounding temperature. Improves responsiveness to In addition, by using the heating means, the amount of heat generated near the edge of the heat generating film is increased, and the ratio of the heat generating portion to the portion where heat is diffused is increased, so that the heat generating portion near the edge of the heat generating film is also increased. The same heat generation as the central part can be used to improve responsiveness.

[First Embodiment] Hereinafter, a first embodiment embodying the present invention will be described with reference to the drawings.

FIG. 2 is a diagram showing the manufacturing process of a thermal flow sensor,
The sensor substrate 1 is a rectangular plate with a length and width of several centimeters, and is made of ceramic such as alumina or zirconia. A long and narrow heat insulating hole 2 is formed by punching and pressing (FIG. 2 (1)).

Between this heat insulating hole 2 and the edge of the sensor substrate, two strips of platinum base plate are printed to form a short circuit line 3.4. One short-circuit line 3 extends from near the center of the heat insulating hole 2 toward a corner of the sensor substrate 1, and is bent at a substantially right angle slightly inside the corner. Another short line 4
also extends from near the center of the heat insulating hole 2 in the opposite direction to the short circuit line 3, and curves near the end of the heat insulating hole 2 (
Figure 2 (2)).

After the sensor substrate 1 on which the short circuit line 3.4 is formed is fired, each end 3a, 3b, 4 of the short circuit line 3.4 is heated.
An underglaze 5 made of glass is laminated and printed except for the areas a and 4b and fired (FIG. 2(3)).

Between the ends 3b and 4a of the short-circuit line 3.4 on the underglaze 5 and on each outer side, an organic platinum paste is printed and fired in a thin strip along the short-circuit line 3.4, and a platinum heat-generating film 6 is formed. It is formed. Of this heat generating film body 6, the central part is the central heat generating film body 6b, the side parts are the end heat generating film bodies 6a,
I'll call it 6C. These heating film bodies 6a, 6b, 6
C is connected to the ends 3b, 4a of the shorting line 3.4. This heating film body 6 serves as a resistance heating element in the flow i measurement sensor. Further, along the long side of the sensor substrate 1 opposite to the heat insulating hole 2, organic platinum paste is also printed and fired in a long and thin state inverted and bent at two places to form a platinum temperature compensation resistor 7. . The thickness of the heat generating film body 6 and the temperature compensating resistor 7 is desirably several tenths of a micron, but is not limited to this.
is insulated from the heat generating film body 6 by the heat insulating hole 2,
The heat insulating holes 2 also serve to reduce the heat capacity near the heating membrane 6 (FIG. 2 (4)).

Silver-palladium or silver-platinum is printed and fired in the shaded areas of FIG. 2(5) on the heating film body 6 and temperature compensation resistor 7 thus formed, thereby forming the conductive film body 8.

This conductive film body 8 is connected to the outer ends of the end heating film bodies 6a, 6b, the ends 3a, 4b of the short circuit line 31.4, and both ends of the temperature compensation resistor 7. and central heating membrane body 6
b and the temperature compensation resistor 7 are connected via the short line 3. The thickness of the conductive film body 8 is preferably several tens of microns, but is not limited to this (Fig. 2 (5)).
.

The heating film body 6 and the temperature compensation resistor 7 have a higher resistance value because they are thinner and have a smaller cross-sectional area than the conductive lIi body 8.

On the sensor substrate 1 including the heat generating film 6, temperature compensation resistor 7, and conductive film 8, a glass paste is printed and fired, and an overglaze 14 is coated. This overglaze 14 includes a heating film body 6 and a temperature compensation resistor 7.
, is an overcoat film that protects the conductive film body 8 from dust, and preferably has a thickness of ten or more microns, but is not limited to this, and may be made of a material other than glass.

FIG. 1A shows a cross section of the heat generating film bodies 6a, 6b, and 6C, and the generated power is transmitted through the conductive film body 8.
, 6b, and 6C, but changes in the amount of heat generated are detected only at the central heating membrane 6b through the short circuit line 3.4.

Normally, the ratio of the heat generating part to the heat dissipating part,
In other words, the ratio of the area of the sensor substrate 1 to the heat-generating film 6 per unit area at the edge of the heat-generating lIi body 6 becomes large, and the heat capacity also increases, and it takes a long time for the temperature change in the heat diffusion part to be transmitted to the heat-generating part. This means that the response when the flow rate changes suddenly and the temperature changes becomes extremely poor. This is because, as shown in FIG. 1B, the temperature distribution of the heat generating film 6 is not uniform throughout the heat generating film 6, and the temperature is lower at the edges. In contrast,
As in the present application, the central heat generating film body 6b in the central part of the heat generating film body 6
If you detect changes in the amount of heat generated only by detecting changes in the amount of heat generated, the ratio of the part that generates heat to the part where heat is diffused is large, and changes in the amount of heat generated can be detected only in parts that have good followability to temperature changes, which increases responsiveness to changes in ambient temperature. gets better.

Since FIG. 3A shows the entire circuit of the sensor, circuit elements other than the above-mentioned heat generating film bodies 6a, 6b, 6c and temperature compensation resistor 7 are provided on the hybrid IC or circuit board connected to the sensor board 1. It is being

PNP type transistor 1 for glass DC current a9
The emitter of transistor 10 is connected to the emitter of transistor 10, and the heat generating film bodies 6a, 6b, 6C and resistor RO are connected in series to the collector of transistor 10, and the other end of resistor RO is grounded. A temperature compensating resistor 7, resistors R2, R1, and R3 are connected in parallel to the central heat generating film 6b, end heat generating film 6c, and resistor RO, and resistors R4, R3 are connected to the end heat generating film 6c and resistor RO in parallel.
5 are connected in parallel.The potential between the central heat generating film body 6b and the end heat generating film #, 6C is input to one terminal of the operational amplifier 11, and the potential between the resistors R1 and R2 is input to one terminal of the operational amplifier 11. input to the child terminal,
A voltage proportional to the difference between both potentials is output. The output voltage of the operational amplifier 11 is applied to the base of the transistor 10 after the differential voltage with respect to the positive DC current a9 is divided by resistors R6 and R7.

Further, the potential between the resistors R4 and R5 is inputted to a child terminal of one operational amplifier 12, and the end heating film body 6
The potential between C and the resistor RO is input to one terminal of the operational amplifier 12 via the resistor R8, and the potential between the operational amplifier 12
The output is fed back to one terminal via a resistor R9. By appropriately selecting the amplification factor of the operational amplifier 12 and the values of the resistors R3, R4, R5, R8, and R9 around the operational amplifier 12, the voltage applied to the end heating film 6C can be adjusted to
c can be directly generated in the resistor R3.

As a result, the same voltage Vc is applied to the bridge circuit composed of the central heating film 6b, the end heating film 6c, the resistor RO, the temperature compensation resistor 7, and the resistors R, 2, R1, and R3. The end heating film body 6C and the resistor R3 can be excluded, and the operational amplifier 12, the resistors R4, R5, R8,
R9 can be omitted, and the circuit of FIG. 3A can be replaced with an equivalent circuit as shown in FIG. 3B, which includes the central heating membrane 6b, temperature compensation resistor 7, resistor R2, resistor R,
A Wheatstone bridge can be constructed with the resistor R1.

In this way, it is possible to exclude the end heat generating film members 6a and 6C, which have poor followability to ambient temperature changes, from the hobby 1 Heston bridge that detects the amount of heat generated by the heat generating film member 6. It is possible to perform detection with good responsiveness.

Next, we will discuss the operation of the sensor with the above configuration.
When the flow rate flowing over the central heating membrane 6b increases, the amount of heat absorbed by the fluid increases relative to the amount of heat generated from the heating membrane 6, including the central heating membrane 6b, and the temperature of the central heating membrane 6b decreases. As a result, the resistance value of the central heat generating film body 6b becomes low.Then, in FIG. 3B, the central heat generating film body 6b and the resistance RO
The potential at point b between resistor R2 and resistor R decreases, the output level of operational amplifier 11 decreases, and the potential of the base of transistor 10 decreases. As a result, the conduction current of the PNP type transistor 10 increases, and the amount of heat generated by the heat generating film body 6 including the central heat generating film body 6b increases. An increase in the conduction current of the transistor 10 causes an increase in the flow rate to be detected.

Further, when the flow rate flowing through the sensor F decreases, an operation completely opposite to the above-mentioned operation is performed, and the heat generation amount of the heat generating film body 6 including the central heat generating film body 6b decreases, and the transistor 10
The conduction current of the current i decreases, and a decrease in the current i is detected.

Regarding the temperature compensation resistor 7, the resistance value of the temperature compensation resistor 7 changes due to the temperature change of the fluid itself flowing over the sensor, and the voltage applied to the central heating element 6b is compensated, so that the correction is performed. For example, when the temperature of the fluid rises, the resistance value of the central heat generating film 6b becomes slightly larger, and the voltage applied to the central heat generating film 6b increases.As a result, the potential at point a decreases and the operational amplifier 11's power increases. becomes smaller, but the resistance value of the temperature compensation resistor 7 also increases, and the voltage applied to the temperature compensation resistor 7 also increases.As a result, the point potential decreases and the power of the operational amplifier 11 also decreases, so the output of the operational amplifier 11 becomes If the temperature of the fluid decreases, the conduction current of the transistor 10 will not change, and if the temperature of the fluid decreases, the operation exactly opposite to that described above will occur;
The output of transistor 1 does not change, and the conduction current of transistor 10 also does not change.

Note that the operational amplifier 12 may be omitted by connecting two resistors, the temperature m-compensating resistor 7 and the resistor R2, in parallel to the central heating film body 61) to form a Wheatstone bridge.

[Second Embodiment] FIG. 5 is a diagram showing the manufacturing process of a second embodiment of a thermal flow sensor, in which the sensor substrate 1 is a rectangular plate with a length and width of several centimeters, and is made of material. A material made of ceramic such as alumina young 1 and zirconia is used, and a long and narrow heat insulating hole 2 is punched along the long side of the sensor substrate 1 from slightly inside one corner and formed by pressing (see Fig. 5).
1)>.

A strip of platinum paste is printed between the heat insulating hole 2 and the edge of the sensor substrate 1, forming heating pads 21, 21 and conductive lines 22. The heating heater 21 is bent into an extremely thin zigzag shape, and conductive lines 22
is formed almost straight with a wide width, and two heaters 21, 21 are connected between the 63 conductive lines 22 (FIG. 5 (2)).

After the sensor substrate 1 on which the heating heater 21 and the conductive lines 22 are formed is fired, an underglaze 5 made of glass is laminated and printed on the area except around the outer ends 22a and 22b of the conductive lines 22 at both ends. and fired (Fig. 5 (
3>).

An organic platinum base 1- is printed and fired on the underglaze 5 of the middle conductive line 22'' of the three conductive lines 22..., and a heat-generating film is formed to form a platinum heat-generating film body 6. The size of the body 6 is approximately the same width and length as the conductive line 22 in the middle. The heating film body 6 becomes a resistance heating element in the flow measurement sensor.

Further, along the long side of the sensor substrate 1 opposite to the heat insulating hole 2, the organic platinum base 1~ is also printed and fired in a long and narrow state and inverted and bent at two places, thereby forming the platinum temperature compensation resistor 7. Ru. The thickness of the heat generating film body 6 and temperature compensation resistor 7 is desirably several tenths of a micron, but is not limited to this.The temperature compensation resistor 7 is insulated from the heat generating film body 6 by the heat insulating hole 2, This heat insulating hole 2 is a heat generating film body 6
It also serves to lower the heat capacity in the vicinity (Figure 5 (4))
.

Silver-palladium or silver-platinum is printed and fired in the shaded area in FIG. 5(5) on the heating film body 6 and temperature compensation resistor 7 thus formed, thereby forming the conductive film body 8.

The conductive film body 8 is connected to both ends of the end heating film body 6, to the outer ends 22a and 22b of the conductive line 22, and to both ends of the temperature compensation resistor 7. The heater 21, the heat generating film 6, and the temperature compensating resistor 7 are connected via the conductive film 8. The thickness of the conductive film body 8 is preferably several tens of microns, but is not limited to this (see Fig. 5).
)).

The heating film body 6 and the temperature compensation resistor 7 have a higher resistance value because they are thinner and have a smaller cross-sectional area than the conductive film body 8.

Glass paste is printed and baked on the sensor substrate 1 including the heat generating film 6, the temperature compensation resistor 7, and the conductive film 8, and an overglaze 14 is coated thereon. This overglaze 14 includes a heating film body 6 and a temperature compensation resistor 7.
This is an overcoat film that protects the conductive film body 8 from dust, and the thickness is desirably several microns, but is not limited to this, and the material may be other than glass.

FIG. 4A shows a cross section of the heat generating film body 6 and the heating heater 21. The heating heater 2m21 is located on the outside of both longitudinal ends of the heat generating film body 6, and near the edge of the heat generating film body 6. It is designed to heat up.

Normally, the ratio of the heat generating part to the heat dissipating part,
In other words, the ratio of the area of the sensor substrate 1 to the heat generating film 6 per unit area becomes larger at the edge of the heat generating film 6, and the heat capacity also increases, and it takes longer for the temperature change in the heat diffusion part to be transmitted to the heat generating part. This means that the response when the flow rate changes suddenly and the temperature changes becomes extremely poor.

This is because, as shown in FIG. 4B (1), the temperature distribution of the heat generating film 6 is not uniform throughout the heat generating film 6, and the temperature is lower at the edges.

On the other hand, if the vicinity of the edge of the heat-generating film body 6 is heated by the heater 21.21 as in the present application, the ratio of the heat-generating portion to the portion where heat is diffused also increases even at the edge of the heat-generating film body 6. As shown in FIG. 4B (2), the same heating conditions as the central portion of the heat generating film body 6 can be achieved, and the responsiveness of the heat generating film body 6 as a whole to ambient temperature changes is improved.

FIG. 6 shows the overall circuit of the sensor, and circuit elements other than the above-mentioned heat generating film 6, temperature compensation resistor 7, and heater 21 are installed on a hybrid IC or circuit board connected to the sensor board 1. It is being

PNP type transistor 1 for positive DC power supply 9
The emitter of transistor 10 is connected to the emitter of transistor 10, and the heat generating film 6 and resistor R511 are connected in series to the collector of transistor 10, and the other end of resistor R11 is grounded. For this heating film body 6 and resistor R11, temperature compensation resistor 7, resistor R12,
R13 are connected in parallel, and a Wheatstone bridge is constituted by the heating film 6, the resistor R11, the temperature compensation resistor 7, the resistor R12, and the resistor R13.

The potential at point a between the heat generating film 6 and the resistor R11 is input to one terminal of the operational amplifier 13, and the resistor R12 and R,1
The potential at point b between 3 and 3 is input to the child terminal of the operational amplifier 11, and a voltage proportional to the difference between the two potentials is output. The output voltage of the operational amplifier 13 is applied to the base of the transistor 10 after the differential voltage with respect to the positive DC power supply 9 is divided by resistors R14, R, and 15.

The heater 21.21 includes the heating film body 6, the resistor R
11. It is connected in parallel to a Wheatstone bridge composed of a temperature compensation resistor 7, a resistor R12, and a resistor R13.

Next, the operation of the sensor configured as described above will be described.

Now, when the flow rate flowing over the sensor increases, the heat generating film body 6
The amount of heat absorbed by the fluid increases relative to the amount of heat generated by the fluid, the temperature of the heat generating film 6 decreases, and the resistance value of the heat generating film 6 decreases. Then, in FIG. 6, the heating film body 6 and the resistor R
11 increases, the potential at point a between resistor R12 and resistor R
13, the output level of the operational amplifier 11 decreases, and the potential of the base of the transistor 10 decreases, the conductivity of the PNP transistor 10 improves, and the output level of the operational amplifier 11 decreases. The conduction resistance becomes smaller, the voltage applied to the Wheatstone bridge and the heat generating film body 6 therein increases, and the amount of heat generated by the heat generating film body 6 increases. This decrease in conduction resistance of transistor 10 allows an increase in flow rate to be detected.

At this time, the voltage applied to the heater 21.21 also increases, and the amount of heat generated by the heater 21.21 also increases, so that the end portion of the heat generating film 6 is heated up in accordance with the increase in the amount of heat generated by the heat generating film 6. The balance between the heat generation conditions at the central portion of the heat generation film body 6 and the heat generation conditions at the end portions of the heat generation film body 6 is maintained.

Furthermore, when the flow rate flowing over the sensor decreases, the operation completely opposite to the above-mentioned operation is performed, the amount of heat generated by the heat generating film 6 decreases, the conduction resistance of the transistor 10 increases, and a decrease in the flow rate is detected. It turns out.

Regarding the temperature compensation resistor 7, the resistance value of the temperature compensation resistor 7 changes due to the temperature change of the fluid itself flowing over the sensor, and the voltage applied to the central heat generating film body 6b is compensated, so that the correction is performed. For example, when the temperature of the fluid rises, the resistance value of the heat generating film 6 becomes a little larger, and the voltage applied to the heat generating film 6 increases.As a result, the potential at point a decreases, and the single power of the operational amplifier 13 decreases. However, the resistance value of the temperature compensation resistor 7 also increases, and the voltage applied to the temperature compensation resistor 7 also increases.As a result, the potential at the point decreases and the power of the operational amplifier 13 also decreases, so the output of the operational amplifier 13 does not change. First, the conduction current of the transistor 10 does not change. Also, when the temperature of the fluid decreases, the operation that is completely opposite to the above operation is performed, and similarly, the output of the operational amplifier 13 does not change, and the conduction current of the transistor 10 also changes. do not.

FIG. 7 shows a modification of the second embodiment, in which heaters 21, 21 and conductive lines 22 are provided on the back side of the sensor substrate 1. In this example, the heat generated from the heaters 21 and 21 is applied to the ends of the heat-generating film body 6 through the sensor substrate 1, and the heat-generating conditions at the ends of the heat-generating film body 6 are the heat-generating conditions at the center of the heat-generating film body 6. It can be made in the same manner, and the heat generating film body 6 as a whole has better responsiveness to changes in ambient temperature.

Furthermore, the heat generating film body 6 and the heaters 21.21 are provided at the same position with the sensor substrate 1 in between, and the conditions for dissipating the generated heat are the same. There is no need for adjustment between the two according to the amount of heat generated by the heater 21, for example, adjustment of the value of the resistor connected to the heater 21.21.

FIG. 8 also shows a modification of the second embodiment, in which the heating film 6, the resistor R11, the temperature compensation resistor 7 and the resistor R
12, a heating element 21.2 is connected between the Wheatstone bridge composed of resistors R and 13 and the transistor 10.
1 and a heating heater 21.21 connected in series to a Wheatstone bridge. In this example as well, when the flow of indigo flowing over the sensor increases, the temperature of the heat generating film 6 decreases, the resistance value of the heat generating film 6 decreases, and the potential at point a between the heat generating film 6 and the resistor R11 increases. increases, the difference between the potential at point b between the resistors R12 and R13 decreases, the output level of the operational amplifier 13 decreases, the potential at the base of the transistor 10 decreases, and the conduction current of the PNP transistor 10 decreases. As a result, the amount of heat generated by the heat generating film body 6 increases. An increase in the flow rate is detected due to an increase in the conduction current of the transistor 10.

At this time, the current flowing through the heater 21.21 increases, and the amount of heat generated by the heater 21.21 also increases, so that the end portion of the heat generating film 6 is heated up in accordance with the increase in the amount of heat generated by the heat generating film 6. As a result, a balance between the heat generation conditions at the center of the heat generation film 6 and the heat generation conditions at the ends of the heat generation film 6 is maintained.

Furthermore, when the flow rate flowing over the sensor decreases, the operation that is completely opposite to the above-mentioned operation is performed, the amount of heat generated by the heat generating film 6 decreases, the conduction current of the transistor 10 decreases, and a decrease in the flow rate is detected. It turns out.

The present invention is not limited to the above embodiments, and can be modified in various ways without departing from the spirit of the present invention.For example, the heat generating film body 6
The material, size, thickness, shape, etc. of the heat generating film body 6 may be other than those mentioned above as long as it can detect the amount of heat generated at the center of the heat generating film body 6 or heat the vicinity of the edges of the heat generating film body 6. The short circuit line 3.4 may be provided in any position, such as on the back side of the sensor board 1, and the heating element 21 may be placed astride the edge of the heating film 6 or inside the edge. The heat-generating film body 6 may be manufactured by vapor deposition and etching techniques, and the heat-generating film body 6 may be manufactured by vapor deposition and etching techniques. The amount may be detected, and the present invention is also applicable to temperature measurement sensors other than flow rate measurement sensors.

[Effects of the Invention] As detailed above, according to the present invention, since the change in the amount of heat generated in the central portion of the heat generating film formed on the base is detected, Changes in the amount of heat generated can be detected only in the central portion of the heat-generating film body, which has a large proportion of heat-generating portions and has good followability to temperature changes, resulting in improved responsiveness to changes in ambient temperature.

In addition, since the area near the edge of the heat-generating film formed on the base is heated, the amount of heat generated near the edge of the heat-generating film is increased, and the ratio of the heat-generating part to the part where heat is diffused is reduced. By increasing the size, the heat generation conditions near the edges of the heat-generating film body are the same as those in the center of the heat-generating film body, resulting in effects such as improved responsiveness.

[Brief explanation of the drawing]

1 to 8 show embodiments of the present invention.
The figure is a diagram showing the cross section of the heat generating part and its temperature distribution in the first embodiment, FIG. 2 is a diagram showing the manufacturing process of the sensor in the first embodiment, and FIG. 3 is a diagram showing the sensor manufacturing process in the first embodiment. FIG. 4 is a diagram showing the cross section of the heat generating part and its temperature distribution in the second embodiment, and FIG. 5 is a diagram showing the manufacturing process of the sensor in the second embodiment. FIG. 6 is an overall circuit diagram of the sensor in the second embodiment, FIGS. 7 and 8 are diagrams showing other embodiments, and FIG. 9 is a diagram showing a conventional example. . DESCRIPTION OF SYMBOLS 1... Sensor board, 2... Heat insulation hole, 3.4... Short circuit line, 5... Underglaze, 6... Heat generating film body, 6b... Central heat generating film body, 6a, 6C ... End heating film body, 7... Temperature compensation resistor, 8... Conductive film body, 9
...DC power supply, 10...Transistor, 11.12
．． 13... operational amplifier, 14... overglaze, 21... heating, heater, 22-... conductive line, 3
a, 3b, 4a, 4b, 22a, 22b--end. Patent applicant: NGK Spark Plug Co., Ltd. Representative: Patent attorney Makoto Wakahara - Figure 1A Figure 1B Figure 2 Figure 4A Figure 4B Figure 5 Figure 3B (m) Figure 7

Claims (1)

[Scope of Claims] 1. A sensor that detects various physical quantities based on changes in calorific value, comprising: a heat-generating film body formed on a base that emits heat; and a power supply means for supplying heat-generating power to the heat-generating film body. The heat generating part structure of a sensor according to claim 1, further comprising: a detection means for detecting a change in the amount of heat generated in a central portion of the heat generating film body. 2. The heat generating part structure of a sensor, wherein the detection means is a means that incorporates only the central portion of the heat generating film body into the structure and does not incorporate the end portions of the heat generating film body into the structure. 3. A sensor that detects various physical quantities based on changes in calorific value, comprising: a heat-generating film body formed on a base that emits heat; a power supply means for supplying heat-generating power to the heat-generating film body; and the heat-generating film body. A heating section structure of a sensor, comprising a heating means for heating near an edge of the sensor. 4. The heat generating part structure of a sensor according to claim 3, wherein the heating means is a means for changing the amount of heating according to a change in the physical quantity.