JP2019135457A - Temperature sensor - Google Patents

Abstract

To provide a temperature sensor which is excellent in moisture resistance and a responsibility and capable of suppressing wiring corrosion.SOLUTION: A temperature sensor comprises: an insulating base material 2; a thin film thermistor part 3 formed of a thermistor material on the insulating base material; a pair of counter electrodes 4A and 4B formed to face each other on upper and lower surfaces of the thin film thermistor part; and a floating electrode 5 facing the pair of counter electrodes and formed in the inside of the thin film thermistor part without connecting the pair of counter electrode. The thin film thermistor part is constituted of a plurality of laminated unit thermistor layers, and the floating electrode is formed between laminated unit thermistor layers.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a temperature sensor suitable for measuring the temperature of a fixing roller of an in-vehicle device or a copying machine and having excellent moisture resistance and responsiveness.

  In general, a fixing roller (heating roller) used in an image forming apparatus such as an in-vehicle device or a copying machine is provided with a temperature sensor in contact with the fixing roller (heating roller). As such a temperature sensor, for example, Patent Document 1 proposes a temperature sensor for a fixing device in which a glass-sealed thermistor element is placed on a thin glass plate and sandwiched between upper and lower insulating sheets. In this fixing device temperature sensor, a polyimide resin or a fluororesin is employed as an insulating sheet.

  In recent years, a temperature sensor in which a thin film thermistor is formed on an insulating film has been developed as a film-type temperature sensor that is excellent in flexibility and can be thinned as a whole. For example, Patent Document 2 discloses a temperature sensor including a pair of lead frames, a sensor unit connected to the pair of lead frames, and an insulating holding unit fixed to the pair of lead frames to hold the lead frame. Has been proposed.

  In this temperature sensor, the sensor unit has an insulating film, a thin film thermistor portion patterned with the thermistor material on the surface of the insulating film, and a plurality of comb portions above and below the thin film thermistor portion. A pair of comb electrodes patterned to face each other, and a pair of pattern electrodes connected to the pair of comb electrodes and patterned on the surface of the insulating film. A thin film thermistor portion is extended and bonded to the surface of the film, and is connected to a pair of pattern electrodes.

JP 2010-277054 A JP 2014-52228 A

The following problems remain in the conventional technology.
In order to prevent changes in characteristics (changes in electrical characteristics, etc.) caused by exposure to a hot and humid external environment when measuring the temperature of in-vehicle devices and when measuring the temperature by pressing a temperature sensor against a fixing roller, etc. In addition, conventionally, the surface on the thermal element side is covered with an insulating sheet such as polyimide resin or fluororesin. However, in order to ensure sufficient moisture resistance, a thick insulating sheet must be used, and the heat capacity increases, so the thermal conductivity from the fixing roller to the thermal element decreases, and the responsiveness is sacrificed. There was an inconvenience. That is, an organic polymer such as polyimide resin or fluororesin that constitutes the insulating sheet does not have a sufficiently low water vapor transmission coefficient, so that it can be used as an insulating sheet at least several tens of times to withstand long-term use in a high temperature and high humidity external environment. A thickness of μm was required. In addition, there is a disadvantage that wiring corrosion may occur because of a large potential difference between the pair of counter electrodes and the pair of pattern wirings.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a temperature sensor that is excellent in moisture resistance and responsiveness and can suppress wiring corrosion.

  The present invention employs the following configuration in order to solve the above problems. That is, the temperature sensor according to the first aspect of the present invention is formed to face each other on an insulating base material, a thin film thermistor portion formed of the thermistor material on the insulating base material, and above and below the thin film thermistor portion. A pair of counter electrodes, and a floating electrode formed in the thin film thermistor portion so as to face the pair of counter electrodes and not connected to the pair of counter electrodes.

  The temperature sensor of the present invention includes a floating electrode that is formed in the thin film thermistor portion so as to face the pair of counter electrodes and is not connected to the pair of counter electrodes. The electrode corrosion due to the moisture resistant load can be suppressed. Therefore, thermistor characteristics can be prevented from deteriorating even when used for a long time in a high-temperature and high-humidity environment, and it is not necessary to make the insulation sheet thicker than necessary. Can be suppressed. Further, by providing the floating electrode between a pair of upper and lower counter electrodes, a stacked structure is connected in series, and the area can be reduced.

A temperature sensor according to a second invention is the temperature sensor according to the first invention, wherein the thin film thermistor portion is composed of a plurality of unit thermistor layers stacked, and the floating electrode is formed between the stacked unit thermistor layers. It is characterized by being.
That is, in this temperature sensor, the thin film thermistor portion is composed of a plurality of stacked unit thermistor layers, and the floating electrode is formed between the stacked unit thermistor layers. By increasing the number, the number of floating electrodes arranged between the pair of counter electrodes also increases, and the potential difference between the pair of counter electrodes can be divided according to the number of floating electrodes.

A temperature sensor according to a third invention is characterized in that, in the second invention, an interlayer insulating layer is formed between the stacked unit thermistor layers and outside the floating electrode.
That is, in this temperature sensor, since the interlayer insulating layer is formed between the stacked unit thermistor layers and outside the floating electrode, the unit thermistor layers stacked outside the floating electrode are in contact with each other. The bypass current flowing up and down can be prevented by the interlayer insulating layer.

A temperature sensor according to a fourth invention is the temperature sensor according to any one of the first to third inventions, wherein the counter electrode has a plurality of comb portions and a base end connection portion to which base ends of the plurality of comb portions are connected. The pair of counter electrodes are arranged with the comb portions facing each other up and down, and the floating electrodes are respectively disposed between the comb portions facing vertically and extend along the facing comb portions. It is characterized by.
That is, in this temperature sensor, a pair of counter electrodes are arranged with their comb portions facing each other up and down, and the floating electrodes are arranged between the comb portions facing each other vertically and extend along the facing comb portions. Therefore, it is possible to easily adjust the resistance value by cutting some of the comb portions with a laser trim or the like.

The temperature sensor according to a fifth aspect of the present invention is the temperature sensor according to the fourth aspect, wherein the pair of counter electrodes project the comb portions toward each other in the same direction.
That is, in this temperature sensor, since the pair of counter electrodes project each other's comb portions in the same direction, the length of the comb portions can be reduced by cutting the comb portions facing each other vertically with a laser trim or the like. The resistance value can be changed and finer resistance value adjustment can be performed.

A temperature sensor according to a sixth invention is the temperature sensor according to the fourth or fifth invention, wherein the thin film thermistor portion is divided between the comb portions adjacent in the planar direction on the insulating substrate. It is characterized by comprising.
That is, in this temperature sensor, since the thin film thermistor part is composed of a plurality of divided thermistor parts divided between the comb parts adjacent in the planar direction on the insulating base material, the crack is one of the divided thermistor parts. Even if it occurs, the other divided thermistors are not affected.
In addition, when the insulating base material is an insulating film, it is possible to suppress the influence of the bending on the thin film thermistor portion by bending at a portion where there is no thin film thermistor portion between adjacent divided thermistor portions, and it has high bendability. A flexible film type sensor can be obtained.

The present invention has the following effects.
That is, according to the temperature sensor of the present invention, the floating sensor is provided in the thin film thermistor portion so as to face the pair of counter electrodes and is not connected to the pair of counter electrodes. The potential difference is divided by the floating electrode, so that electrode corrosion due to moisture resistance load can be suppressed, and a thin insulating sheet can be adopted, so that a decrease in temperature detection response speed can be suppressed.
Therefore, the temperature sensor of the present invention is suitable as a temperature measuring sensor for fixing rollers of in-vehicle devices and copying machines that require high moisture resistance and responsiveness.

It is a top view which shows 1st Embodiment of the temperature sensor which concerns on this invention. It is the sectional view on the AA line of FIG. 1, (a), and BB sectional drawing (b). It is CC sectional view taken on the line of FIG. It is a top view which shows 2nd Embodiment of the temperature sensor which concerns on this invention. It is the DD sectional view taken on the line (a) of FIG. 4, and the EE sectional view (b). It is a top view which shows 3rd Embodiment of the temperature sensor which concerns on this invention. It is a top view which shows 4th Embodiment of the temperature sensor which concerns on this invention. It is the FF sectional view taken on the line of FIG.

  Hereinafter, a first embodiment of a temperature sensor according to the present invention will be described with reference to FIGS. 1 to 3. Note that in some of the drawings used for the following description, the scale is appropriately changed as necessary to make each part recognizable or easily recognizable.

  As shown in FIGS. 1 to 3, the temperature sensor 1 of the present embodiment includes an insulating base 2, a thin film thermistor portion 3 formed of the thermistor material on the insulating base 2, and a thin film thermistor portion 3. A pair of counter electrodes 4A and 4B formed to face each other on the top and bottom, and a pair of counter electrodes 4A and 4B, which are formed in the thin film thermistor portion 3 and connected to the pair of counter electrodes 4A and 4B. And no floating electrode 5.

The thin film thermistor section 3 is composed of a plurality of stacked unit thermistor layers 3a.
The floating electrode 5 is formed between the stacked unit thermistor layers 3a.
In this embodiment, the thin film thermistor section 3 is configured by laminating three unit thermistor layers 3a, and two floating electrodes 5 are provided sandwiched between the unit thermistor layers 3a in the thickness direction.

As described above, in the present embodiment, the unit thermistor layers 3a and the floating electrodes 5 are alternately stacked, and are disposed between the pair of upper and lower counter electrodes 4A and 4B and connected in series.
Note that the unit thermistor layers 3 a of the present embodiment are directly stacked on and in contact with each other outside the floating electrode 5.

The pair of counter electrodes 4A and 4B includes a plurality of comb portions 4a and a base end connection portion 4b to which the base ends of the plurality of comb portions 4a are connected. That is, the pair of counter electrodes 4A and 4B is formed in a comb-shaped pattern.
The pair of counter electrodes 4A and 4B are arranged with the comb portions 4a facing each other up and down.
The floating electrodes 5 are respectively disposed between the comb portions 4a opposed to each other in the vertical direction, and extend along the opposed comb portions 4a. That is, as shown in FIG. 3, each floating electrode 5 extends in a strip shape or a rectangular shape along the comb portion 4a.

In the present embodiment, the comb portions 4a of the pair of counter electrodes 4A and 4B protrude in opposite directions, and the pair of counter electrodes 4A and 4B have four comb portions 4a extending in parallel with each other.
The thin film thermistor part 3 is composed of a plurality of divided thermistor parts 13 divided between the comb parts 4 a adjacent to each other in the planar direction on the insulating substrate 2.
That is, each divided thermistor portion 13 extends in a strip shape or a rectangular shape along the comb portion 4a. In the present embodiment, the thin film thermistor portion 3 is composed of four divided thermistor portions 13 arranged in parallel to each other.
In addition, the base end connection part 4b of the counter electrode 4B formed on the thin film thermistor part 3 is bridged over the four divided thermistor parts 13.

At both ends of the pair of counter electrodes 4A and 4B, connection terminal portions 4c which are wide pad portions for external connection are provided.
Note that an insulating protective film that covers the pair of counter electrodes 4A and 4B and the thin film thermistor portion 3 excluding the connection terminal portion 4c may be formed on the insulating substrate 2. This protective film is an insulating resin film or the like, and for example, a polyimide film can be adopted.

The insulating substrate 2 is, for example, a rectangular insulating film.
This insulating substrate 2 is formed in a band shape with, for example, a polyimide resin sheet having a thickness of 7.5 to 125 μm. In addition, the insulating substrate 2 can be made of PET: polyethylene terephthalate, PEN: polyethylene naphthalate, etc., but for measuring the temperature of the fixing roller, a polyimide film is desirable because the maximum use temperature is as high as 230 ° C. .

The thin film thermistor portion 3 is made of, for example, a TiAlN thermistor material. In particular, the thin film thermistor portion 3 is a metal represented by the general formula: Ti _x Al _y N _z (0.70 ≦ y / (x + y) ≦ 0.95, 0.4 ≦ z ≦ 0.5, x + y + z = 1). It consists of nitride and its crystal structure is a hexagonal wurtzite single phase.
The thin film thermistor section 3 and the counter electrodes 4A and 4B are shown hatched in FIG.
The counter electrodes 4A and 4B have a Cr or NiCr bonding layer with a thickness of 5 to 100 nm and an electrode layer formed with a noble metal such as Au on the bonding layer with a thickness of 50 to 1000 nm.

  In the temperature sensor 1 of the present embodiment, the resistance value can be adjusted by performing laser trimming in the middle of the base end connection portion 4b, for example, at a portion indicated by a symbol T in FIG. That is, by cutting the proximal end connection part 4b in the middle, the comb part 4a ahead of the cut part is cut off, and the resistance value can be adjusted.

  As described above, the temperature sensor 1 of the present embodiment includes the floating electrode 5 that is formed in the thin film thermistor portion 3 so as to face the pair of counter electrodes 4A and 4B and is not connected to the pair of counter electrodes 4A and 4B. Since the potential difference between the pair of counter electrodes 4A and 4B is divided by the floating electrode 5, electrode corrosion due to moisture resistance load can be suppressed. Therefore, thermistor characteristics can be prevented from deteriorating even when used for a long time in a high-temperature and high-humidity environment, and it is not necessary to make the insulation sheet thicker than necessary. Can be suppressed. In addition, by providing the floating electrode 5 between the pair of upper and lower counter electrodes 4A and 4B, the stacked structure is connected in series, and the area can be reduced.

  Further, since the thin film thermistor section 3 is composed of a plurality of unit thermistor layers 3a and the floating electrode 5 is formed between the laminated unit thermistor layers 3a, the number of unit thermistor layers 3a can be increased. By increasing the number, the number of floating electrodes 5 arranged between the pair of counter electrodes 4A and 4B increases, and the applied voltage can be divided according to the number of floating electrodes 5.

  The pair of counter electrodes 4A and 4B are arranged with the comb portions 4a facing each other up and down, and the floating electrodes 5 are respectively disposed between the comb portions 4a facing up and down, and extend along the facing comb portions 4a. Therefore, the resistance value can be easily adjusted by cutting some of the comb portions 4a with a laser trim or the like.

Moreover, since the thin film thermistor part 3 is comprised by the some division | segmentation thermistor part 13 divided | segmented between the comb parts 4a adjacent to the planar direction on the insulating base material 2, a crack is one of the division | segmentation thermistor parts 13. Even if it occurs, the other divided thermistor portions 13 are not affected.
Furthermore, when the insulating base material 2 is an insulating film, the influence on the thin film thermistor portion 3 due to bending can be suppressed by bending at a portion where the thin film thermistor portion 3 between the adjacent divided thermistor portions 13 is not present. A flexible film type sensor having bendability can be obtained.

  Next, second to fourth embodiments of the temperature sensor according to the present invention will be described below with reference to FIGS. In the following description of each embodiment, the same constituent elements described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The difference between the second embodiment and the first embodiment is that in the first embodiment, the pair of counter electrodes 4A and 4B project the comb portion 4a in opposite directions, whereas the temperature of the second embodiment is different. In the sensor 21, as shown in FIG. 4, a pair of counter electrodes 4A and 24B is the point which makes the mutual comb part 4a protrude toward the same direction.
That is, in the second embodiment, the base end connection portions 4b of the pair of counter electrodes 4A and 24B are both arranged on the right side in FIG. 4 of the thin film thermistor portion 3, and the comb portions 4a are on the left side in FIG. Protrusively toward.

In the second embodiment, laser trimming is performed in the middle of the comb portion 4a, for example, a portion T in FIG. 4, so that the comb portion 4a is cut in the middle, the protrusion length is shortened, and the resistance value can be adjusted.
As described above, in the temperature sensor 21 of the second embodiment, the pair of counter electrodes 4A and 24B project the mutual comb portions 4a in the same direction. By cutting by this, the length of the comb part 4a can be changed, and finer resistance value adjustment can be performed.

Next, the difference between the third embodiment and the first embodiment is that, in the first embodiment, the pair of counter electrodes 4A and 4B each have four elongated comb portions 4a, whereas the second embodiment is different from the second embodiment. In the temperature sensor 31 of the embodiment, as shown in FIG. 6, the pair of counter electrodes 34 </ b> A and 34 </ b> B has two elongated comb portions 4 a and one wide extending portion 34 a.
That is, in the second embodiment, the two elongated comb portions 4a are for adjusting the resistance value, but the other portions do not need to be thin comb portions, and are wide extending portions 34a wider than the comb portions 4a. .

The wide extending portion 34a extends in parallel to the comb portion 4a from the base end connecting portion 4b. Moreover, the wide extending part 34a is connected to the base end connection part 4b.
The wide extending portions 34 a of the pair of counter electrodes 34 </ b> A and 34 </ b> B are disposed to face each other above and below the thin film thermistor portion 33.
Further, the divided thermistor portion 33a disposed between the pair of wide extending portions 34a is formed wide corresponding to the wide extending portion 34a.

  Next, the difference between the fourth embodiment and the first embodiment is that, in the first embodiment, the stacked unit thermistor layers 3 a are in contact with each other outside the floating electrode 5, whereas the fourth embodiment is different from the fourth embodiment. In the temperature sensor 41 of the embodiment, as shown in FIGS. 7 and 8, an interlayer insulating layer 46 is formed between the stacked unit thermistor layers 3 a and outside the floating electrode 5, and each unit thermistor layer 3 a This is that they are insulated from each other outside the floating electrode 5.

In the fourth embodiment, the interlayer insulating layer 46 is formed in a rectangular frame shape so as to cover the outer peripheral edge of the unit thermistor layer 3 a from the outer peripheral portion of the floating electrode 5. That is, the outer periphery of the interlayer insulating layer 46 is formed larger than the unit thermistor layer 3a. Accordingly, the floating electrode 5 is in direct contact with the unit thermistor layer 3 a inside the rectangular frame-shaped interlayer insulating layer 46, and the upper and lower unit thermistor layers 3 a are insulated by the interlayer insulating layer 46 outside the floating electrode 5. Has been.
The interlayer insulating layer 46, for example, formed of SiO _2.

  As described above, in the temperature sensor 41 of the fourth embodiment, the interlayer insulating layer 46 is formed between the stacked unit thermistor layers 3 a and outside the floating electrode 5. Therefore, the temperature sensor 41 is stacked outside the floating electrode 5. In addition, when the unit thermistor layers 3 a are in contact with each other, the bypass current flowing up and down can be prevented by the interlayer insulating layer 46.

The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, as described above, the counter electrode having a comb portion is preferable when the resistance value adjustment is performed, but when the resistance value adjustment is not performed, it is not necessary to have the comb portion, and a pair of wide opposing surfaces facing each other vertically. It does not matter as an electrode.

1, 21, 31, 41 ... temperature sensor, 2 ... insulating substrate, 3, 33 ... thin film thermistor,
3a: Unit thermistor layer, 4A, 4B, 24B, 34A, 34B ... Counter electrode, 4a ... Comb portion, 4b ... Base end connection portion, 5 ... Floating electrode, 13, 33a ... Divided thermistor portion, 46 ... Interlayer insulating layer

Claims (6)

An insulating substrate;
A thin film thermistor portion formed of a thermistor material on the insulating substrate;
A pair of counter electrodes formed opposite to each other above and below the thin film thermistor portion;
A temperature sensor comprising: a floating electrode formed in the thin film thermistor portion so as to face the pair of counter electrodes and not connected to the pair of counter electrodes. The temperature sensor according to claim 1,
The thin film thermistor portion is composed of a plurality of unit thermistor layers stacked,
The temperature sensor, wherein the floating electrode is formed between the stacked unit thermistor layers. The temperature sensor according to claim 2,
A temperature sensor, wherein an interlayer insulating layer is formed between the laminated unit thermistor layers and outside the floating electrode. The temperature sensor according to any one of claims 1 to 3,
The counter electrode has a plurality of comb portions and a base end connection portion to which base ends of the plurality of comb portions are connected,
The pair of counter electrodes are arranged with the comb portions facing each other up and down,
The temperature sensor according to claim 1, wherein the floating electrodes are respectively arranged between the comb portions facing vertically and extending along the facing comb portions. The temperature sensor according to claim 4,
The temperature sensor, wherein the pair of counter electrodes project the comb portions toward each other in the same direction. The temperature sensor according to claim 4 or 5,
The temperature sensor, wherein the thin film thermistor part is constituted by a plurality of divided thermistor parts divided between the comb parts adjacent in the planar direction on the insulating substrate.

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