JP3390305B2 - Temperature sensing element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-sensitive element used as a temperature sensor, a radiation sensor, etc., and more particularly to a temperature-sensitive element whose resistance value changes depending on environmental temperature or infrared irradiation.

[0002]

2. Description of the Related Art Conventionally, as described in JP-A-4-348237 and JP-A-3-96824, a temperature sensitive element using a fiber filament containing silicon carbide as a main component is known. ing. Further, as another conventional example, as described in Japanese Patent Application Laid-Open No. 8-166295, one in which a laminated plate of a phenol resin is carbonized at 640 to 750 ° C. and the carbide is used as a temperature sensitive element is disclosed. Are known. These temperature-sensitive elements have semiconductor-like conductivity, and their resistance values change due to changes in the ambient temperature and the irradiation of infrared rays.Therefore, it is necessary to detect the resistance value, actually the voltage value, from the electrodes formed at both ends of the temperature-sensitive element. Therefore, it can be used as a temperature sensor or a radiation sensor.

[0003]

By the way, in normal use of the temperature sensor or the radiation sensor, in order to reduce power consumption and make it difficult to respond to external noise, the actual resistance value of the sensor should be several kΩ to several kΩ. Although it is desired to set it to 100 kΩ, in the case of using the former thermosensitive element consisting of the fiber filament among the above-mentioned conventional examples, the actual resistance value between both electrodes is several kΩ which is a normal use range. In order to make it several to several hundred kΩ, it is necessary to reduce the specific resistance of the fiber filament by the amount that the cross-sectional area of the fiber is small. However, there is a close relationship between the specific resistance of the temperature sensitive element and the temperature dependence (thermistor constant). The higher the specific resistance, the greater the temperature dependence, and the lower the specific resistance, the smaller the temperature dependence. A sensor using a fiber filament having a low resistance has a problem that the sensitivity is lowered, that is, a large output change cannot be obtained with respect to a temperature change.

On the other hand, when the latter thermosensitive element made of a carbide of a phenol laminated plate is used, the cross-sectional area becomes larger than that of the fiber, so that the specific resistance of the material can be increased and the temperature dependence can be increased. However, the size of the carbide of the phenol laminated plate cannot be reduced, especially the size in the thickness direction, and the heat capacity of the temperature sensitive element is increased. Therefore, a sensor using such a temperature sensitive element has a slow response speed. There is a problem of becoming.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to the use of films or aramid resin nonwoven carbonized aramid resin as temperature sensing element. Carbides of such aramid resin show semiconducting conductivity, and
When carbonized in an inert gas atmosphere of 00 to 750 ° C, the specific resistance at room temperature is 1 Ω · cm to 100 MΩ · cm.
It is possible to obtain a temperature sensitive element having a high temperature dependence and a thermistor constant of 100 to 3500K. Therefore, when an electrode is formed on such a temperature sensitive element to form a temperature sensor or a radiation sensor, even if the actual resistance value between both electrodes is set to several kΩ to several hundred kΩ, which is a normal use range, nothing happens. The sensitivity of the sensor can be increased without any problem. Further, non <br/> woven film or aramid resin aramid resin for significantly smaller dimension in the thickness direction by the carbonization process, can achieve small temperature sensitive element heat capacity, to be the response speed of the sensor You can

[0006]

Temperature sensing element of the present invention DETAILED DESCRIPTION OF THE INVENTION, carbides disposed between the electrodes of the aramid resin film or A
It consists of a non-woven fabric of amide resin that has been carbonized, and its specific resistance at room temperature is 1 Ω · cm to 100 MΩ · cm.
The thermistor constant is 100 to 3500K. here,
If the thermistor constant is less than 100K, the change in output with respect to temperature change is too small, making it difficult to use as a sensor. The sensor cannot be used within the range.

At the same time, the aramid resin uses a film or a non-woven fabric, and the non-woven fabric of the aramid film or the aramid resin is crystallographically oriented along its forming surface. The dimensional reduction rate is increased, the temperature sensing element can be made thinner, and the heat capacity can be reduced. further,
Since the cross-sectional area can be made larger than that of the fiber filament, even if the thermistor constant is made large, the actual resistance value between both electrodes can be set to several kΩ to several hundred kΩ which is a normal use range.

The aramid film may be either a meta-aramid or a para-aramid, but a para-aramid film is used because the para-aramid has a larger dimension reduction rate in the thickness direction than the meta-aramid. It is suitable for thinning the temperature sensitive element.

Further, both electrodes may be formed on the same surface of the carbide, but if these electrodes are formed on both front and back surfaces of the carbide, the resistance in the thickness direction of the carbide is detected, and the resistance value is controlled. Made easier with aramid resin
The film or the non-woven fabric of aramid resin has a significantly reduced dimension in the thickness direction due to the carbonization treatment, so that the distance between the electrodes is shortened and a sensor having a lower actual resistance value can be realized.

When the gel-like aramid film is drawn and then carbonized, a temperature-sensitive element formed into a predetermined shape such as a curved surface can be formed. Moreover, since it is possible to mix pigments and dyes into the gel-like aramid film, the temperature-sensitive element can be colored to improve the characteristics of the sensor.

[0011]

EXAMPLES Examples will be described with reference to the drawings.
FIG. 1 is a perspective view of the temperature-sensitive element according to the embodiment as viewed from the front side,
2 is a perspective view of the temperature-sensitive element viewed from the back side, FIG. 3 is an explanatory view showing a manufacturing process of the temperature-sensitive element, FIG. 4 is a sectional view of the temperature-sensitive element, and FIG. FIG. 6 is an equivalent circuit diagram and FIG. 6 is a sectional view of an infrared sensor using the temperature sensitive element.

As shown in FIGS. 1 and 2, the temperature sensitive device 1 has a carbide 2 of aramid resin, and a counter electrode 3 is formed on the entire surface of the carbide 2 almost all over. Carbide 2
Resistivity at room temperature is 1 Ω · cm to 100 MΩ · cm
Then, the thermistor constant is 100 to 3500K (when the thermistor constant B is converted to the activation energy ΔE and expressed, both have a relation of B = 5794 × ΔE, and the activation energy ΔE≈0.017 to 0). 0.6 eV). The counter electrode 3 may be made of any material as long as its specific resistance is sufficiently smaller than that of the carbide 2. For example, a thin film of gold, silver, copper, nickel, aluminum or the like, or a thick film of carbon ink, silver ink, copper ink or the like is preferable. And they are ^10-6
The specific resistance is about 10 ³ Ω · cm. Also, carbide 2
A pair of extraction electrodes 4 are formed on the back surface of the with a predetermined interval, and a terminal 5 is connected to each extraction electrode 4. It is also possible to use the same material as the counter electrode 3 described above as the material of the extraction electrode 4, form these on the back surface of the carbide 2, and then connect the terminal 5 to the extraction electrode 4 using solder or a conductive adhesive. However, the conductive adhesive itself may be used as the extraction electrode 4, and in this case, each terminal 5 is directly attached to the back surface of the carbide 2 using the conductive adhesive (the extraction electrode 4).

A method of manufacturing the temperature sensitive element 1 will be described with reference to FIG. 3. First, as shown in FIG. 3A, a para-type aramid film 6 cut into a circle is prepared. The dimension of this aramid film 6 is, for example, 6 mm in diameter.
And the thickness is 50 μm. Then, as shown in FIG. 3 (b), the aramid film 6 is carbonized at a low temperature such that graphitization does not proceed in an atmosphere of an inert gas such as H ₂ , N ₂ and Ar, specifically, 600 to 750 ° C. When treated, carbide 2 having semiconducting conductivity is obtained. The carbide 2 shrinks by the carbonization treatment, and when the raw material aramid film 6 has the above-mentioned size, the carbide 2 shrinks to a diameter of 5 mm and a thickness of about 36 μm. Then Fig. 3
As shown in (c), a counter electrode 3 and a pair of extraction electrodes 4 arranged at intervals of 0.1 mm or more are formed on the front surface and the back surface of the carbide 2, respectively, and finally as shown in FIG. ,
The manufacture of the temperature sensitive element 1 is completed by attaching the terminals 5 to the respective extraction electrodes 4 on the back surface side of the carbide 2.

As shown in FIGS. 4 and 5, in the temperature-sensitive element 1 constructed as described above, the specific resistance of the carbide 2 is higher than that of the counter electrode 3 and the distance between both extraction electrodes 4 is higher. Since the carbide 2 is thin, the current flows from one of the extraction electrodes 4 in the thickness direction of the carbide 2, passes through the counter electrode 3, and flows to the other extraction electrode 4. Therefore, the resistance between both terminals 5 is almost equal to the resistance in the thickness direction of the carbide 2 connected in series. Here, the distance between the counter electrode 3 and the extraction electrode 4 is determined by the thickness of the carbide 2, and the distance between the electrodes can be shortened to the order of μm, and moreover, the facing area between the counter electrode 3 and the extraction electrode 4 is sufficiently large. Since it can be made wider, the actual resistance value can be set to several kΩ to several hundred kΩ which is a normal use range, although the temperature sensitive element 1 having a high specific resistance is used. Therefore, the thermistor constant is 100 to 3
It is possible to realize the temperature sensitive element 1 having a high temperature of 500 K, in other words, having a large temperature dependency. The aramid resin film or non-woven fabric is generally 200 μm or less in thickness, and is obtained by preparing a gel aramid resin and orienting it in a plane direction or in one direction, and crystallizing it at the same time.
Since the film or nonwoven fabric has a significantly reduced dimension in the thickness direction due to carbonization treatment, the heat capacity of the temperature sensitive element 1 can be suppressed to be small, and the response time until the temperature sensitive element 1 becomes in equilibrium with the ambient temperature is shortened. You can Further, since the reduction in the dimension in the plane direction is small, when applied to an infrared sensor described later, it is possible to secure a light receiving area at the same time, and the response time can be shortened. Furthermore, because the film or nonwoven fabric with crystal orientation is carbonized,
The shape is stable.

Next, an infrared sensor using the temperature sensitive element 1 will be described with reference to FIG. This infrared sensor is roughly composed of an insulating case 7 made of a light-shielding synthetic resin or the like, a window member 8 attached to the upper open end of the insulating case 7, and the temperature sensitive element 1 arranged inside them. Each terminal 5 is led out from the joint surface between the insulating case 7 and the window member 8. The window member 8 is formed of, for example, polyethylene so as to have a lens function for condensing light, but polycarbonate, silicon, germanium, calcium fluoride or the like having high infrared transmittance may be used instead of polyethylene. Further, the temperature sensitive element 1 is arranged so that the counter electrode 3 faces the window member 8, and when infrared rays from the outside penetrate the window member 8 and irradiate the surface of the temperature sensitive element 1, the infrared rays are irradiated by the infrared ray. The resistance value of the temperature sensitive element 1 changes, and the resistance value of the temperature sensitive element 1, that is, the voltage value is actually detected from each terminal 5. In this infrared sensor, the counter electrode 3
Since it functions as a light receiving surface for infrared rays, carbon ink having the highest heat absorption efficiency is preferable as the material of the counter electrode 3 among the various materials described above. On the other hand, regarding the extraction electrode 4 that is not irradiated with infrared rays, considering the connection strength of the terminal 5, among the various materials described above, gold, silver, copper, nickel,
Metallic materials such as aluminum are preferred.

FIG. 7 is a cross-sectional view of the solar radiation sensor according to the embodiment. This solar radiation sensor has an insulating substrate 10 having five terminals 9, a cover 11 attached to the insulating substrate 10, and the inside thereof. And a temperature sensitive element 12 disposed in the. The temperature sensitive element 12 is a carbide 13 of aramid resin.
The carbide 13 consists of four curved arms 13a of the same shape.
Is formed into a dome shape so as to have a specific resistance at room temperature of 1 Ω · cm to 100 MΩ · cm and a thermistor constant of 100 to 3500K. When each terminal 9 is designated by a symbol, the four terminals are connected to the lower end of each curved arm 13a of the carbide 13 and the remaining terminals are connected to the center lower end of the carbide 13 using a conductive adhesive or the like. As shown in the equivalent circuit diagram of FIG. 8, the lengthwise resistances a to d of the bending arm 13a are connected between the central terminal and the four surrounding terminals ~. Also, cover 1
1 is made of a material having a high infrared ray transmissivity similarly to the window member 8 described above. When infrared rays pass through the cover 11 from any direction and irradiate the bending arm 13a of the temperature sensitive element 12,
Only the resistance value of the bending arm 13a irradiated with the infrared rays changes. Therefore, when the infrared rays are applied to the two bending arms 13a corresponding to the resistance a and the resistance c and the values of the resistances a and c decrease, the detection voltage between the terminals and between the terminals changes to the resistance change. Since the value becomes a corresponding value, it is possible to detect the direction in which infrared rays are emitted.

A method of manufacturing the temperature-sensitive element 12 having the above-described structure will be described with reference to FIG. 9. First, as shown in FIG. 9A, a para-type aramid swelling gel film 14 cut into a circle is first prepared. To prepare. Next, as shown in FIG. 9 (b), the aramid swelling gel film 14 is punched to form a cross-shaped portion, and the surrounding annular portion is cut into four equal parts, and then shown in FIG. 9 (c). So that it is drawn into a dome shape. Then, the aramid swelling gel film 14 thus drawn is dried, and then carbonized at 600 to 750 ° C. in an atmosphere of an inert gas such as H ₂ , N ₂ , Ar or the like to obtain a carbide 13 which maintains a dome shape. Is obtained.

In each of the above embodiments, the case where the temperature sensing element of the present invention is applied to a radiation sensor such as an infrared sensor or a solar radiation sensor has been described, but it is also possible to apply it to a temperature sensor. At that time, although the temperature sensitive element configured as in each of the above embodiments can be applied to the temperature sensor, the electrodes 17 are formed on both front and back surfaces of the aramid resin carbide 16 as in the temperature sensitive element 15 shown in FIG. However, the resistance in the thickness direction of the carbide 16 may be taken out from the terminal 18 connected to these electrodes 17. Even in that case, since the resistance in the thickness direction of the aramid film can be utilized, it is possible to provide a temperature sensor having a high response speed, good sensitivity, and at the same time a small actual resistance value, as described above. In this case, since the electrode can be made large and the resistance in the thickness direction becomes the actual resistance, the actual resistance can be further reduced as compared with the above embodiment.

[0019]

The present invention is carried out in the form as described above, and has the following effects.

The carbide disposed between both electrodes is made of a film of aramid resin or a non-woven fabric of aramid resin, and has a specific resistance of 1 Ω · cm at room temperature.
〜100MΩ ・ cm, thermistor constant is 100〜35
When the temperature sensing element of 00K is applied to the temperature sensor and the radiation sensor, the sensitivity of the sensor can be increased without any problem even if the actual resistance value is set to a normal use range of several kΩ to several hundred kΩ. , nonwoven films or aramid resin aramid resin for significantly smaller dimension in the thickness direction by the carbonization process, it is possible to be realized a small temperature sensitive element heat capacity and speed of response of the sensor.

Further, at the same time, the aramid resin uses a film or a non-woven fabric, and the non-woven fabric of the aramid film or the aramid resin is crystallographically oriented along its forming surface. The dimensional reduction rate of the temperature sensing element becomes large, the heat sensing element can be made thin, and the heat capacity can be reduced. Moreover, since the cross sectional area is large, it is possible to provide a temperature sensing element having a large thermistor constant, that is, excellent sensitivity. Even if the actual resistance value between both electrodes is set to several kΩ to several hundred kΩ, which is a normal use range, no problem will occur. In particular, since the para-aramid has a larger dimensional reduction rate in the thickness direction than the meta-aramid, it is preferable to use the para-aramid film in order to reduce the thickness of the temperature-sensitive element.

[0022] In addition, the aramid resin film or A
Since the dimension of the lamido resin nonwoven fabric in the thickness direction is significantly reduced by the carbonization treatment, if electrodes are formed on both the front and back sides of the carbide to detect the resistance in the thickness direction, the distance between the electrodes will become shorter, resulting in a lower actual resistance. A value sensor can be realized.

When the gel-like aramid film is subjected to drawing and then carbonized, a temperature-sensitive element formed into a predetermined shape such as a curved surface can be formed. Moreover, since it is possible to mix pigments and dyes into the gel-like aramid film, the temperature-sensitive element can be colored to improve the characteristics of the sensor.

[Brief description of drawings]

FIG. 1 is a perspective view of a temperature-sensitive element according to an embodiment as viewed from the front side.

FIG. 2 is a perspective view of the temperature-sensitive element viewed from the back side.

FIG. 3 is an explanatory view showing a manufacturing process of the temperature sensitive element.

FIG. 4 is a sectional view of the temperature sensitive element.

FIG. 5 is an equivalent circuit diagram of the temperature sensitive element.

FIG. 6 is a cross-sectional view of an infrared sensor using the temperature sensitive element.

FIG. 7 is a sectional view of the solar radiation sensor according to the embodiment.

8 is an equivalent circuit diagram of a temperature sensitive element used in the solar radiation sensor of FIG.

FIG. 9 is an explanatory diagram showing a manufacturing process of the temperature-sensitive element.

FIG. 10 is a cross-sectional view of a temperature sensitive device according to another embodiment.

[Explanation of symbols]

1,12,15 Temperature sensor 2,13,16 Carbides 3 Counter electrode 4,16 Extraction electrode 5,9,18 terminals 6 Aramid film 7 Insulation case 8 window materials 10 Insulating substrate 11 cover 14 Aramid swelling gel film 17 electrodes

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-4-348237 (JP, A) JP-A-3-96824 (JP, A) JP-A-8-166295 (JP, A) JP-A-8- 31611 (JP, A) JP-A-2-310430 (JP, A) JP-A-60-195014 (JP, A) JP-A-6-20804 (JP, A) JP-A-5-166606 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01K ^7/ 16-7/22 G01J 5/02 H01L 35/00

Claims (4)

(57) [Claims] 1. A consists those carbides disposed between the electrodes has carbonizing the film or aramid resin nonwoven aramid resin, resistivity 1 [Omega · c at that normal temperature
m to 100 MΩ · cm, thermistor constant is 100 to 3
A temperature sensitive element that is 500K. 2. The temperature sensitive device according to claim 1, wherein the carbide is a para-type aramid film. 3. The temperature sensitive device according to claim 1, wherein the electrodes are formed on both front and back surfaces of the carbide. 4. The temperature sensitive device according to claim 1, wherein the carbide is obtained by drawing a gel aramid film into a predetermined shape and then carbonizing the drawn aramid film.