JP2001194247A - Thermistor temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermistor temperature sensor the output voltage of which is highly linear over a wide temperature range and which can detect temperature with high accuracy. SOLUTION: The thermistor temperature sensor is constituted in such a way that a first thin film fixed resistor 31 is connected in series between input and output electrodes 51 and 53 on an insulating substrate 11 and, at the same time, a first thin film thermistor 12 is connected between the input and output electrodes 51 and 53 and a ground electrode 52. In addition, a second thin film thermistor 13 is directly connected to a second thin film fixed resistor 32 between the first thin film fixed resistor 31 and first thin film thermistor 12 and the ground electrode 52 on the substrate 11. Each connection is made by using a conductive pattern 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor temperature sensor used for information equipment, communication equipment, home electric appliances, household equipment, automobile equipment and the like.

[0002]

2. Description of the Related Art In recent years, information equipment, communication equipment, home electric appliances,
There is an increasing demand for detecting the temperature characteristic of an electronic component having a temperature characteristic or a temperature around an electronic component by using a thermistor temperature sensor in a home appliance, an automobile device, or the like to compensate for the temperature characteristic.

As a circuit for performing temperature detection by a thermistor temperature sensor, it is known that a circuit as shown in FIG. 2 has excellent linearity of the output voltage of the thermistor temperature sensor over a wide temperature range.

That is, the thermistor 12 is connected to the resistors 31 and 32.
13 are connected in series.

[0005]

When the thermistors are individually mounted on electronic components or electronic equipment, for example, to realize the circuit configuration shown in FIG. 2, a temperature difference is likely to occur between the thermistors, and an error occurs in temperature detection. There is a problem that.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thermistor temperature sensor which prevents a temperature difference from occurring in a thermistor to be used, has excellent linearity of output voltage over a wide temperature range, and can perform temperature detection with high accuracy. It is intended for.

[0007]

To achieve this object, a thermistor temperature sensor according to the present invention comprises: a pair of input and output electrodes; a first resistor connected in series between the input and output electrodes; A first thin-film thermistor connected in parallel between the input and output electrodes; a second resistor connected in parallel between the first resistor and the first thin-film thermistor; And a second thin-film thermistor connected in series to at least the first and second thin-film thermistors. The first and second thin-film thermistors are formed on the same insulating substrate. This makes it possible to perform temperature detection with high accuracy.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a pair of input and output electrodes, a first resistor connected in series between the input and output electrodes, and the input and output electrodes. A first thin-film thermistor connected in parallel between the first resistor and a second resistor connected in parallel between the first resistor and the first thin-film thermistor; and a second resistor connected in series to the second resistor. A thermistor temperature sensor comprising: a second thin-film thermistor; and a ground electrode connected to the first and second thin-film thermistors, wherein at least the first and second thin-film thermistors are formed on the same insulating substrate. This prevents a temperature difference from occurring between the first and second thin film thermistors and enables highly accurate temperature detection.

According to a second aspect of the present invention, the (n + 1) th
(Where n is an integer of 2 or more) and the (n +
An (n + 1) th thin film thermistor connected in series to the resistor of (1), and connected in parallel with the nth resistor and the nth thin film thermistor between the first resistor and the ground electrode; and 2. The thermistor temperature sensor according to claim 1, wherein said nth and (n + 1) th thin film thermistors are formed on the same insulating substrate, and have a linear output voltage over a wider temperature range.

According to a third aspect of the present invention, there is provided a thermistor temperature sensor according to the first aspect, wherein the first to n-th resistors are also formed on an insulating substrate, and the size can be reduced.

According to a fourth aspect of the present invention, the resistance value of the n-th thin film thermistor is 1.5 times or more the resistance value of the (n-1) th thin film thermistor. Thermistor temperature sensor, and it is possible to improve the linearity of the output voltage over a wider temperature range.

According to a fifth aspect of the present invention, at least one of the first to n-th thin film thermistors has a pair of comb-shaped electrodes formed on the surface of the thermistor layer. At least one resistance adjusting electrode is formed so as to be electrically connected, and between the comb-shaped electrode and the resistance adjusting electrode, and when a plurality of the resistance adjusting electrodes are provided, the resistance adjusting electrode is provided. 2. The thermistor temperature according to claim 1, further comprising a slit provided for insulating the electrodes, wherein the resistance adjusting electrode is removed to change a resistance value of the thin film thermistor by a predetermined ratio. The sensor is a sensor that can adjust the resistance value of the thin film thermistor to a desired value, so that the temperature detection accuracy can be further improved.

According to a sixth aspect of the present invention, when a plurality of resistance value adjusting electrodes are formed, the resistance value of the thin film thermistor is set to two.
6. The thermistor temperature sensor according to claim 5, wherein the resistance value of the thin-film thermistor is changed with high accuracy by ^m % [m: 0 (positive integer of (the number of resistance adjustment electrodes−1)). Since the adjustment can be performed, the accuracy of the temperature detection is further improved.

According to a seventh aspect of the present invention, at least the first
2. The thermistor temperature sensor according to claim 1, wherein the surface of the nth thin-film thermistor is covered with an insulating protective film, which protects against external moisture and the like, can suppress a change with time, and can stably detect temperature for a long time. Accuracy can be maintained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a top view of a thermistor temperature sensor according to a first embodiment of the present invention.

In FIG. 1, reference numeral 11 denotes an insulating substrate, and 12 denotes a first substrate.
The thin-film thermistor 13 is a second thin-film thermistor, in which a pair of comb electrodes 22 and 23 are formed on the surface of a thermistor layer 21 formed on the insulating substrate 11. 31 is a first thin film fixed resistor, 32 is a second thin film fixed resistor, 41 is a conductive pattern, 51 is an input electrode, 52 is a ground electrode, and 53 is an output electrode.

The first thin-film fixed resistor 31 is connected in series between the input and output electrodes 51 and 53, and the first thin-film thermistor 12 is connected between the input and output electrodes 51 and 53 and the ground electrode 52. I have. The second thin-film fixed resistor 32 and the second thin-film thermistor 13 connected in series are connected between the first thin-film fixed resistor 31 and the first thin-film thermistor 12 and between the ground electrode 52. Further, each connection is made by the conductive pattern 41.

FIG. 2 is an equivalent circuit diagram of the thermistor temperature sensor according to the first embodiment.

This thermistor temperature sensor is obtained by the following method.

First, Mn, Co, Ni, Fe, Al is coated on the entire surface of an insulating substrate 11 made of alumina or aluminum nitride.
After forming at least two types of composite oxides on a target by high frequency sputtering, the first thin film thermistor 12 and the first thin film thermistor 12 are placed at predetermined positions on the insulating substrate 11 using a photolithography process such as reactive ion etching or wet etching. Second thin film thermistor 13
Is formed. Note that the sputtering is performed by heating the insulating substrate 11 to 200 to 400 ° C. in order to improve the adhesion between the insulating substrate 11 and the thermistor layer 21. O ₂ is introduced into Ar as a sputtering gas at a flow rate of about 5% at a gas pressure of 0.2 to 5.0 Pa. The thermistor layer 21 has a thickness of 0.2 to
It is in the range of 3.0 μm.

Next, at a temperature (600 to 600) at which the thermistor layer 21 formed on the insulating substrate 11 has a desired crystal structure.
Heat treatment is performed at 1000 ° C.) to crystallize the thermistor layer 21. Thereafter, a thin film of about 0.1 μm in thickness made of Pt, Au, or the like is formed on the entire upper surface of the insulating substrate 11 by sputtering. This sputtering is performed at a temperature of 100 to 300 ° C. for the insulating substrate 11, Ar as a sputtering gas, and a gas pressure of 0.2 to 5.0 Pa. Next, a pair of comb electrodes 22 and 23 are respectively formed on the thermistor layer 21 by using a photolithography process such as reactive ion etching, wet etching, and lift-off, and the input electrode 51, the ground electrode 52, the output electrode 53, and the like. The conductive pattern 41 is formed.

Finally, after a resistive thin film made of an alloy mainly composed of Ni—Cr or RuO ₂ is formed on the insulating substrate 11 by vapor deposition or sputtering, a photolithography process such as reactive ion etching or wet etching is performed. The first thin film fixed resistor 31 and the second thin film fixed resistor 3
3 to obtain the thermistor temperature sensor according to the first embodiment.

In the thermistor temperature sensor according to the first embodiment, the first and second thin-film thermistors 12 and 13 are formed on a single insulating substrate 11 having excellent thermal conductivity.
The first and second thin film thermistors 12 and 13 do not have a temperature difference between the first and second thin film thermistors 12 and 13.
By correcting the linearity of the output voltage in the above, the linearity of the output voltage is excellent over a wide temperature range (for example, −20 to 80 ° C .: 100 ° C. or higher), and highly accurate temperature detection is possible.

(Embodiment 2) FIG. 3 is a top view of a first thin-film thermistor 12 used in a thermistor temperature sensor according to Embodiment 2 of the present invention, and FIG. 4 is a sectional view taken along a line AB in FIG.
The first thin-film thermistor 12 and the second thin-film thermistor 13 are basically formed in the same configuration. Therefore, in the second embodiment, the first thin-film thermistor 12 will be described. Portions other than the first thin-film thermistor 12 and the second thin-film thermistor 13 have the same configuration as the thermistor temperature sensor described in the first embodiment, and a description thereof will be omitted.

In FIG. 3, 21 is a thermistor layer formed on the insulating substrate 11, 22 and 23 are comb electrodes, 231,
232, 233, and 234 are resistance value adjusting electrodes;
242, 243, 244 are insulating slits, and 25 is a trimming groove.

A method of forming the first thin-film thermistor 12 (the second thin-film thermistor 13 is also formed in the same configuration at the same time) will be described below.

First, the thermistor layer 21 is formed at a predetermined position on the insulating substrate 11 by using a photolithography process as in the first embodiment, and the insulating slit 2 is formed.
41, 242, 243 and 244 are formed.

Next, a temperature (600 to 600) at which the thermistor layer 21 formed on the insulating substrate 11 has a desired crystal structure.
After performing a heat treatment at 1000 ° C. to crystallize the thermistor layer 21, the first embodiment is applied to the entire upper surface of the insulating substrate 11.
In the same manner as described above, a thin film having a thickness of about 0.1 μm made of Pt, Au or the like is formed by sputtering.

Next, as in the first embodiment, the comb-shaped electrodes 22 and 23 are formed by using a photolithography process, and the resistance adjusting electrodes 231, 232, 233 are formed.
234 are formed to obtain the first thin film thermistor 12. At this time, the input electrode 51, the ground electrode 52, the output electrode 53, and the conductive pattern 41 are also formed.

Thereafter, a first thin-film fixed resistor 31 and a second thin-film fixed resistor 33 are formed on the insulating substrate 11 in the same manner as in the first embodiment, and a thermistor temperature sensor according to the second embodiment is obtained.

The resistance adjusting electrodes 231, 232, 2
33, 234, when removed, the resistance change rate of the first thin film thermistor 12 is 2 ^{m -1} % (m: 1 to the number of the resistance adjusting electrodes 231, 232, 333, 234).
In this second embodiment, four resistance adjusting electrodes 231, 232, 333,
234 are removed, the first thin film thermistor 1
2 is 1%, 2%, 4%, 8% compared to the initial value
It is formed to change.

Further, the comb-shaped electrode 23 and the resistance adjusting electrode 2
31, resistance value adjusting electrodes 231 and 232, 232 and 23
3, an insulating slit 24 formed between 233 and 234
1, 242, 243 and 244 are comb-shaped electrodes 23 and resistance adjusting electrodes 231; resistance adjusting electrodes 231 and 232;
232 and 233, and electrical insulation between 233 and 234. These facts can be applied to the second thin film thermistor 13 having the same configuration as the first thin film thermistor 12.

In the thermistor temperature sensor of the second embodiment formed as described above, the resistance values of the first thin-film thermistor 12 and the second thin-film thermistor 13 are measured, and according to the ratio of deviation from the target resistance value. And the resistance adjusting electrodes 231, 232, 233, 234 to be removed are selected. Here, for example, a case where the resistance adjusting electrode 232 is selected will be described. As shown in FIGS. 3 and 4, a part of the resistance adjusting electrode 232 including the lower thermistor layer 21 is removed by a laser or the like, and the insulating slits 242 and 243 adjacent to each other are connected by the trimming groove 25 and the comb is formed. The mold electrode 23 is insulated from the resistance adjusting electrode 232.

As described above, the resistance value adjusting electrodes 231, 232, and 23 are removed in accordance with the ratio of deviation from the target resistance value.
3, and at least one is selected, and the insulating slits 241, 242, 243, and 244 adjacent to each other are removed including the thermistor layer 21 so as to be connected with the trimming groove 25 and insulated from the comb-shaped electrode 23. . Therefore, since the resistance value can be adjusted with high accuracy from 1% to 15% in increments of 1% as compared with the initial value, a thin film thermistor having high resistance value accuracy can be obtained. Therefore, the linearity of the output voltage of the thermistor temperature sensor can be further improved, and as a result, the temperature detection accuracy can be improved.

In the second embodiment, four resistance value adjusting electrodes 231, 232, 233, and 234 are formed. However, any number may be formed. Therefore, when the number of the resistance adjusting electrodes is set to m (m is an integer of 1 or more) and selectively removed, the resistance change rate of the thin film thermistor is compared with the initial value, and the resistance of the thin film thermistor 12 is 2
It is possible to digitally adjust from ⁰ % = 1% to 2 ^m-1 % in 1% steps.

In the second embodiment, the resistance adjusting electrodes 231, 232, 233, 234 are provided so that the resistance of the first thin film thermistor 12 can be adjusted in steps of 1%.
Was formed in order to cope with a case where the tolerance of the first thin film thermistor 12 with respect to the required resistance value was ± 1%. Therefore, for example, the tolerance with the required resistance value is ± 3.
In the case of%, the resistance value adjusting electrode may be formed so that the resistance value of the thin film thermistor changes in steps of 3% or less.

Further, when the insulating slit is provided, it is necessary to ensure the insulation between the resistance adjusting electrodes and between the resistance adjusting electrodes and the comb-shaped electrodes.
This is because, if these electrical insulations cannot be secured, it is difficult to digitally adjust the resistance value due to the interaction between the electrodes.

Further, the resistance of the thin film thermistor increases when the resistance adjusting electrode is removed. Therefore, if the comb-shaped electrode and the resistance adjusting electrode are formed so that the resistance of the thin film thermistor becomes the target resistance from the beginning,
When the initial resistance value of the thin film thermistor is high, the resistance value cannot be adjusted. Therefore, by forming the comb-shaped electrode and the electrode for adjusting the resistance value so that the resistance value of the thin film thermistor is lower than the target resistance value, it is possible to prevent the occurrence of a case where the resistance value cannot be adjusted.

(Embodiment 3) FIG. 5 is a top view of a thermistor temperature sensor according to Embodiment 3 of the present invention.

In this thermistor temperature sensor, the surface of the thermistor temperature sensor shown in the first or second embodiment is covered with an insulating protective film 61. Since it is the same as the thermistor temperature sensor shown in the first embodiment or the second embodiment, the same elements are denoted by the same reference numerals and description thereof is omitted.

The thermistor temperature sensor according to the third embodiment is obtained by the following method.

First, the thermistor temperature sensor shown in the first or second embodiment is formed.

Next, as shown in FIG. 5, the surface of the insulating substrate 11 is printed with glass or polyimide resin, epoxy resin, phenol resin, or the like so that the input electrode 51, the ground electrode 52, and the output electrode 53 are exposed. Is performed to form the insulating protective film 61.

The thermistor temperature sensor of the third embodiment formed as described above includes the first and second thin film thermistors 12 and 13 and the first and second thin film fixed resistors 31 and 21.
Can be protected from external heat, moisture, and the like, and the aging of the resistance values of the first and second thin-film thermistors 12, 13 and the first and second thin-film fixed resistors 31, 32 can be suppressed.
It is possible to maintain stable temperature detection accuracy for a long time.

Hereinafter, the points of the present invention will be described.

(1) As shown in FIG. 6, the thermistor temperature sensor of the present invention is superior in the linearity of the output voltage between -40 ° C. and 125 ° C. as compared with the conventional case where the thermistors are individually connected. Accurate temperature detection is possible.

(2) In the first to third embodiments, two thin-film thermistors and two thin-film fixed resistors are used. However, by using three or more thin-film thermistors and three or more thin-film fixed resistors each in the same number, a wider temperature range can be obtained. Thus, it is possible to obtain the linearity of the output voltage of the thermistor temperature sensor. In this case, it is desirable that all the thin film thermistors are formed on the same insulating substrate.

The (n + 1) th (where n is an integer not less than 2) thin film resistor and an (n + 1) th thin film thermistor connected in series to the (n + 1) th thin film resistor are provided as a first thin film thermistor.
Between the thin film resistor 31 and the ground electrode 52 in parallel with the nth thin film resistor and the nth thin film thermistor.

(3) As described in the first to third embodiments, by forming not only the thin-film thermistor but also the thin-film fixed resistor on the same insulating substrate, the size of the thermistor temperature sensor can be reduced.

(4) The resistance value of the second thin film thermistor 13 is 1.5 times or more the resistance value of the first thin film thermistor 12.
By preferably setting the ratio to 5 to 20, the linearity of the output voltage can be improved over a wider temperature range.

That is, when forming n thin film thermistors, the resistance value of the n th thin film thermistor is 1.5 times or more the resistance value of the (n-1) th thin film thermistor.

(5) When a plurality of thin-film thermistors and thin-film fixed resistors are formed on the same insulating substrate, the thin-film thermistors are formed adjacent to each other and arranged as close as possible to a non-measurement object. It is desirable to prevent the occurrence of.

(6) In the first to third embodiments, the electrodes of the first and second thin film thermistors 12 and 13 are comb-shaped electrodes 2
However, the shape of the electrode is not limited to this, and can be freely set so as to have a desired resistance value. Also, the composition and thickness of the thermistor layer 21 can be freely set similarly.

[0055]

As described above, according to the present invention, a wide temperature range (1
It is possible to provide a thermistor temperature sensor that is excellent in linearity of the output voltage over the temperature range of 00 ° C. or higher and that can detect the temperature with high accuracy.

[Brief description of the drawings]

FIG. 1 is a top view of a thermistor temperature sensor according to Embodiment 1 of the present invention.

FIG. 2 is an equivalent circuit diagram of a thermistor temperature sensor according to the first to third embodiments of the present invention.

FIG. 3 is a top view of a first thin film thermistor of the thermistor temperature sensor according to the second embodiment of the present invention.

FIG. 4 is a sectional view taken along a line AB in FIG. 4;

FIG. 5 is a top view of a thermistor temperature sensor according to Embodiment 3 of the present invention.

FIG. 6 is a temperature-output voltage characteristic curve diagram of the thermistor temperature sensor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Insulating substrate 12 1st thin film thermistor 13 2nd thin film thermistor 21 Thermistor layer 22 Comb electrode 23 Comb electrode 25 Trimming groove 31 First thin film fixed resistor 32 Second thin film fixed resistor 41 Conductive pattern 51 Input electrode 52 Ground electrode 53 Output electrode 231 Resistance adjusting electrode 232 Resistance adjusting electrode 233 Resistance adjusting electrode 234 Resistance adjusting electrode 241 Insulating slit 242 Insulating slit 243 Insulating slit 244 Insulating slit

Claims (7)

[Claims] A pair of input and output electrodes; a first resistor connected in series between the input and output electrodes; a first thin-film thermistor connected in parallel between the input and output electrodes; A second resistor connected in parallel between a first resistor and the first thin-film thermistor, a second thin-film thermistor connected in series to the second resistor, and the first and second thin-film thermistors; A thermistor temperature sensor comprising a ground electrode connected to a thin-film thermistor, wherein at least the first and second thin-film thermistors are formed on the same insulating substrate. 2. A first resistor comprising an (n + 1) th resistor (where n is an integer of 2 or more) and an (n + 1) th thin film thermistor connected in series to the (n + 1) th resistor. The n-th resistor and the n-th thin-film thermistor are connected in parallel between ground electrodes, and the n-th and (n + 1) -th thin-film thermistors are formed on the same insulating substrate. Thermistor temperature sensor. 3. The thermistor temperature sensor according to claim 1, wherein the first to n-th resistors are also formed on an insulating substrate. 4. The thermistor temperature sensor according to claim 1, wherein the resistance value of the nth thin film thermistor is 1.5 times or more the resistance value of the (n−1) th thin film thermistor. 5. At least one of the first to n-th thin film thermistors has a pair of comb electrodes formed on the surface of a thermistor layer, and at least one of the first to n-th thin film thermistors is electrically connected to the comb electrodes. In order to form one resistance adjustment electrode, and also to insulate between the comb-shaped electrode and the resistance adjustment electrode and between the resistance adjustment electrodes when a plurality of the resistance adjustment electrodes are provided. The thermistor temperature sensor according to claim 1, further comprising a slit provided, wherein the resistance adjusting electrode is removed to change a resistance value of the thin film thermistor by a predetermined ratio. 6. When forming a plurality of resistance value adjusting electrodes, the resistance value of the thin film thermistor is changed by 2 ^m % [m: 0 (positive integer of (the number of resistance value adjusting electrodes−1))]. 6. The thermistor temperature sensor according to claim 5, wherein: 7. The thermistor temperature sensor according to claim 1, wherein at least the surfaces of the first to n-th thin film thermistors are covered with an insulating protective film.