JPH08122285A - Water sensor and water amount detection method - Google Patents

Abstract

PURPOSE: To perform detection with precision by providing a detection section in which a heat sensing element and a heater are arranged and fixed on a member having heat transfer property and a thermal insulation means which prevents diffusion of heat in the detection section. CONSTITUTION: A disc-like metal member 2 has heat transfer property of metals such as aluminum, copper, etc., and cavities 3, 3' are provided in the member 2. A temperature sensing element 5 is inserted in the cavity 3, and a heater 4 is inserted in the cavity 3'. Lead wires 4', 5' for pulling out outward are provided in the heater 4 and the element 5. Resistance value of the element 5 immediately before a switch is turned on is read, and then the switch is set to the ON condition to turn on the power supply and apply a certain voltage to the heater 4. Resistance value of the element after the heater 4 is heated and a certain period of time elapses is read to measure resistance-temperature characteristics of the element 5. The relationship between the change of temperature and water content rate is obtained in advance, and temperature after a certain period of time elapses is measured to obtain water content rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to wood particles called sawdust or whole chips used in food waste treatment equipment of bio method, or water retention material or powder such as rock wool used in facility gardening. The present invention relates to a moisture sensor for detecting the amount of moisture such as water and a method for detecting the amount of moisture.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting moisture in a substance, an infrared absorption method, a microwave method and an electric resistance method are known. Briefly explaining these moisture detection methods, an infrared moisture sensor using an infrared absorption method measures the amount of moisture in the detected body by irradiating the detected body with infrared rays and measuring the intensity of the reflected light. To do. The microwave method is a method of measuring the water content in a substance by utilizing the attenuation of the microwave by the water content in the substance. Furthermore, the electric resistance method is mainly used in agriculture, horticulture, civil engineering, etc. as a method for electrically detecting the water content in the soil, and a water content meter using this method is usually two at regular intervals. This is a method of burying the porous inorganic material in which the metal wire is embedded in the soil to measure the electric resistance.

[0003]

However, the conventional moisture sensor has the following drawbacks. The moisture detection by the infrared absorption method and the microwave method as described above has a disadvantage that the structure is complicated and the shape is large. Further, since these are precision instruments, they are expensive, and because of their large structure, they are not suitable for moving and using. In addition, the electric resistance type moisture sensor is generally used for measuring moisture in the soil such as civil engineering, and since the electrode is directly inserted into the object to be measured, it is vulnerable to environmental conditions. However, there are drawbacks such as its troublesome handling. Therefore, the conventional moisture sensor is used for industrial or research purposes different from the one for consumer use, and is not preferable as a versatile moisture sensor.

The present invention has been made in view of the above problems, and is compact and stable to environmental conditions.
An object of the present invention is to provide a moisture sensor having excellent detection accuracy and good reproducibility. Another object of the present invention is to provide a water content detection method which has excellent detection accuracy and good reproducibility.

[0005]

In order to achieve the above object, the first moisture sensor of the present invention is a detection unit in which a heat sensitive element and at least one heater are arranged and fixed to a member having thermal conductivity. And a heat insulating means for preventing the heat dissipation of the detection part. A second moisture sensor of the present invention includes a detection unit in which a heat-sensitive element and at least one heater are arranged and fixed in a cavity provided in a metal member having thermal conductivity, and a heat insulation member supporting the detection unit. And a storage container for accommodating the detection unit supported by the heat insulating member and for mounting the detection unit on a detection object. According to a third moisture sensor of the present invention, a detection unit in which a heat-sensitive element and at least one heater are arranged and fixed on a metal plate having thermal conductivity, a heat insulating member supporting the detection unit, and the heat insulating member are used. It is characterized in that it comprises a storage container for accommodating the supported detection unit and for mounting it on the detection object. In the second and third moisture sensors, an air heat insulating layer formed by a cavity or an opening is provided in at least a part of the heat insulating member provided on the back side of the detection surface of the detection unit.

In the second and third moisture sensors, the heat insulating member is made of foamed resin, and a suitable material for the heat insulating member is made of any one of silicon resin, urethane resin and styrene resin. Is. In the third moisture sensor described above, the detection unit is formed by fixing at least one heater and a heat sensitive element on a metal plate with an adhesive. In the above third moisture sensor, a printed wiring board in which a detection portion is patterned on a metal plate via an insulating layer,
A heater or a resistor and a heat-sensitive element made of chip parts are mounted on the printed wiring board. Third above
In the moisture sensor, the detection unit is a printed wiring board having a pattern formed on a metal plate via an insulating layer, and a resistor and a heat sensitive element formed on the printed wiring board in a thick film or a thin film. In the second and third moisture sensors, it is preferable that the container is a metallic infrared reflecting material or resin. In the above moisture sensor, an infrared reflecting member is provided on the inner wall surface of the cavity or opening formed in the heat insulating member. In the above moisture sensor, an infrared reflecting member is provided on at least one of the inner surface of the storage container and the back surface of the detection unit. A metal film or a metal plate is preferable as the infrared reflecting member used in the moisture sensor. Further, the water content detection method of the present invention, the detection unit of the moisture sensor is contacted or embedded in the object to be detected, the heater of the detection unit is heated, and before the heating of the detection unit by the heat-sensitive element of the detection unit. Detects the difference between the temperature and the temperature after heating for a certain time,
The amount of water in the object to be detected is detected by the temperature difference.

[0007]

According to the moisture sensor of the present invention, the heater provided in the cavity provided in the metal member having thermal conductivity which constitutes the detection unit is heated for a certain period of time, and the detection unit is detected according to the amount of water in the object to be detected. Since the degree of heat diffusion (heat conductivity and specific heat) from the surface of the to-be-detected body differs, a temperature difference occurs before and after the heater is heated. By detecting this temperature difference with a heat-sensitive element provided in the detection unit, the amount of water in the object to be detected is detected. The moisture sensor of the present invention is one in which a heater and a heat sensitive element are formed on a thin metal plate in order to reduce the heat capacity of the detection portion, and the moisture amount of the detection object is detected by the same principle as described above. Good detection accuracy and thermal response. The moisture sensor of the present invention forms an air heat insulating layer by forming a cavity in the heat insulating member on the back surface side of the detecting unit in order to minimize heat dissipation to the heat insulating member supporting the detecting unit. This improves the detection accuracy.

The moisture sensor of the present invention is provided with an infrared reflecting member in order to prevent heat radiation from the detecting portion, and the storage container is formed of an infrared reflecting material, or the heat insulating member or the back surface of the detecting portion or the storage container. An infrared reflecting material is formed on the inner surface, the heat insulating member and the back surface of the detection unit, and the back surface of the detection unit and the inner surface of the storage container. Further, the water content detection method of the present invention heats the heater of the detection part, detects the difference between the temperature before heating and the temperature after heating for a certain time by the heat sensitive element, and the water content of the detected object is detected by the temperature difference. Is to detect.

[0009]

Embodiments of the moisture sensor according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the moisture sensor of the present invention, FIG. 2 (a) is a perspective view showing its detecting portion, and FIG. 2 (b) is its sectional view. FIG. 3 is an exploded perspective view of FIG. A cross-sectional view taken along the line XY in FIG. 1 is shown in FIG. In FIG. 1, 1 is a detection part of a moisture sensor, 7 is a heat insulating member, and 8 is a storage container. The heat insulating member 7 is stored in the storage container 8,
The detection unit 1 is fitted in the concave portion of the heat insulating member 7, and the storage container 8 is formed with a flange provided with a mounting hole 8a. The detection unit 1 will be described based on FIGS. 2A and 2B. Reference numeral 2 denotes a disk-shaped metal member having heat conductivity such as aluminum or copper. The metal member 2 is provided with cavities 3 and 3 ′ which are bored, and the thermosensitive element 5 is inserted into the cavity 3. A heater 4 is inserted in each of the cavities 3 '.
The heater 4 and the heat sensitive element 5 are hermetically fixed by an adhesive 6 such as a resin having heat resistance. As the heater 4, a heating element such as a resistor is used. A thermistor element is used as the heat sensitive element 5. The heater 4 and the heat sensitive element 5 are provided with lead wires 4'and 5'for external drawing.

Next, referring to the exploded view of FIG. 3, the moisture sensor of FIG. 1 will be described. The storage container 8 is provided with a flange having a mounting hole 8a, and the lead wires 4'and 5'are drawn out. The flange is provided with a concave fitting portion 8b. A heat insulating member 7, which is a foamed resin (sponge) such as a silicone resin or a urethane resin, is stored in the storage portion of the storage container 8.
The heat insulating member 7 blocks radiant heat and radiant heat from the detection unit 1, and covers the portion of the detection unit 1 other than the contact surface with the object to be detected. The heat insulating member 7 has lead wires 4 ',
A cutout portion 7a is provided in the pulled-out portion of 5 ', and the detection portion 1 is fitted in the storage portion of the heat insulating member 7 to form a moisture sensor.

Next, the usage state of the moisture sensor according to the present invention will be described with reference to FIG. The same figure (a),
(B) is a partially cutaway sectional view showing a state in which the moisture sensor is attached to the garbage processing machine. FIG. 1A shows a usage state in which the detection unit 1 of the moisture sensor is in direct contact with the processing material 9 such as raw dust and sawdust. An opening 11 having a size such that the detection surface of the detection unit 1 is exposed to the inside of the container 10 is formed in the container 10 into which the processing material 9 is put, and the detection surface of the detection unit 1 is exposed through the opening 11. It is exposed in the container 10 and is in contact with the processing material 9. The moisture sensor is a storage container 8
The bolt 20 is inserted into the mounting hole of the flange of the
It is fixed at 0. By making the detection unit 1 project into the container 10 to the extent of the thickness of the container 10, the contact with the processing material 9 becomes good.

Further, FIG. 1B shows a usage state in which the moisture sensor is directly attached to the container 10. The detection unit 1 is mounted in direct contact with the container 10. In this case, the change in heat transmitted to the container 10 is detected. As is clear from this usage state, since heat is transferred through the container 10, accurate temperature detection cannot be performed unless the detection surface of the detection unit 1 and the wall surface of the container 10 are in close contact with each other. Therefore, the heat from the processing material 9 can be efficiently detected by interposing a material whose contact surface has good thermal conductivity and flexibility, such as a silicone resin adhesive, grease, a thin resin sheet, or silicone oil. .

Next, a method of detecting the amount of water by the water sensor of the present invention will be described with reference to FIG. The operating principle of this water content detection method will be briefly described. The principle of this moisture sensor is to detect the difference in thermal response characteristic due to the difference in thermal conductivity and the specific heat due to the amount of moisture contained in the treatment material 9, and to detect the amount of moisture or the moisture content by detecting the rising temperature or temperature difference by the heat sensitive element. To do. For example, when explained based on the water content of sawdust, dried sawdust has a thermal conductivity substantially equal to that of air, and a water content of 100% is substantially equal to the thermal conductivity of water. Further, the specific heat of the treated material 9 also changes depending on the water content. The detection part of the moisture sensor of the present invention is heated by a heater, and the difference in the thermal response characteristics due to the change in the amount of heat radiated from the detection surface of the detection part due to the amount of water in the processing material is detected.
The water content of the treatment material can be measured relatively easily by detecting with the heat sensitive element 5. It is preferable that the material of the container 10 is such that the heat from the detection unit 1 is effectively transmitted to the processing material 9 and the heat dissipation from the periphery of the detection unit 1 to the container itself is as small as possible. That is, in the case of resin or metal, stainless steel is most suitable.

Next, a method for measuring the water content will be described with reference to FIG.
The detection circuit will be described with reference to FIG. Figure 5 shows water content (water content)
Is a detection circuit for detecting. Reference numeral 1 denotes a detection unit, which is provided with a heater 4 and a heat sensitive element 5, the electrode of the heater 4 is connected to a constant voltage source E via a switch S, and the heat sensitive element 5 is connected to a resistance measuring instrument M. In this detection circuit, one heater 4 is provided, but even if two heaters are provided, they may be connected in parallel. First, the resistance value of the thermosensitive element 5 immediately before the switch S is turned on is read, and then the switch S is turned on to turn on the power to apply a constant voltage to the heater 4 to heat the heater 4 to a constant value. After the lapse of time, the resistance value of the thermosensitive element 5 is read and the temperature is measured. That is, the temperature change can be known from the measured resistance value by measuring the resistance-temperature characteristic of the heat sensitive element 5 of the moisture sensor in advance. If the same measurement is performed on the treated materials having different water contents, the relationship between the temperature change and the water content after a certain period of time can be found. Therefore, if the relationship between the temperature change and the water content is clear in advance, the water content can be easily known from the temperature by measuring the temperature after a certain period of time.

FIG. 6 shows the results of measuring the temperature after a certain time has elapsed after heating the processing materials having different water contents by the detection circuit. The horizontal axis shows the heating time by the heater 4, and the vertical axis shows the temperature rise. The water content of the treated material is 0% in (a) of FIG. 6, and the water content of 30 is (b).
%, (C) are when the water content is 60%. As the water content of the treatment material increases, the temperature rise after a certain period of time decreases, and it can be seen that the difference in the water content of the treatment material causes a difference in the temperature rise after a certain period of time. That is, it can be understood from this experiment that the amount of water can be detected by measuring the difference in temperature rise after a certain period of time.

FIG. 7 shows a case where sawdust is used as a treating material.
6 is a graph showing a relationship between a temperature difference and a water content when a temperature of a heat sensitive element is measured by applying a power of about 1 W to a resistor as a heater 4. The horizontal axis of the graph of FIG. 7 represents the water content, and the vertical axis represents the temperature difference between the temperature before the switch S is turned on and 5 minutes after the switch S is turned on. Further, in this experiment, a comparison is made between the case where the infrared ray reflecting member is provided and the case where the infrared ray reflecting member is not provided in order to prevent the radiant heat of the detecting portion of the moisture sensor. As is clear from this graph, it is shown that the temperature difference varies depending on the water content.
It is shown that the water content of the treated material can be detected from the temperature difference, and that the detection sensitivity of the temperature is better when the infrared reflecting member is provided in the detecting portion of the moisture sensor. This is because the radiation heat of the detection unit can be reduced by providing the infrared reflecting member.

Next, another embodiment of the moisture sensor according to the present invention will be described with reference to the sectional views of FIGS. These examples are based on the above experimental results and are improved. These cross-sectional views are cross-sectional views of another embodiment shown in the portion corresponding to the line XY in the embodiment of FIG. FIG. 8A is a cross-sectional view of the embodiment of FIG. 1, in which the heat insulating member 7 on the back surface (heat insulating member side) of the detection unit 1 is a cushioning member that elastically presses the detection unit 1 to the detected body. It is for thermal insulation that plays a role and prevents heat from being dissipated from the back surface of the detection unit 1 to the storage container 8. In this embodiment, since the heat insulating member 7 and the entire back surface of the detection unit 1 are in contact with each other, when the detection unit 1 is heated, the heat to the heat insulating member 7 is dissipated at the same time as the heat is dissipated to the processing material such as raw dust. There is also some radiation. Dissipation of heat to the heat insulating member 7 causes a detection error. The heat dissipation affects the detection accuracy of the moisture sensor.

The embodiment shown in FIGS. 8 (b) and 8 (c) is shown in FIG.
This is an embodiment in which the detection accuracy is higher than that of the embodiment (a). FIG. 8B shows that the heat insulating member 7 is provided with an opening 11 made of a cavity to form an air heat insulating layer to prevent heat dissipation. In the embodiment of FIG. 8C, the heat insulating member 7 is provided with the concave cavity 12. The heat insulation member 7 of the detection unit 1 is formed by the air heat insulation layer formed by the opening 11 and the concave cavity 12.
The heat dissipation to the air is eliminated, and the detection accuracy is improved as compared with the moisture sensor of the embodiment of FIG. The embodiment of FIG. 8 (d) is
The detection unit 1 does not use a heat insulating member made of foaming resin (sponge) or the like, and the detection unit 1 is provided with a heat insulating layer 14 made of an air layer to thermally insulate the storage container 8 and the detection unit 1.
A support protrusion 8c projects inside the storage container 8, and a screw 15 is passed through the support protrusion 8c and screwed into the detection unit 1 to fix the detection unit 1 in the storage container 8. 8 (b),
In the examples of (c) and (d), the opening 11 and the concave cavity 1 are provided.
2 or even if the heat insulating layer 14 is provided only by the air layer, the detection accuracy is improved as compared with the embodiment of FIG. 8A, but the radiation heat from the back surface of the detection unit 1 dissipates the heat in the storage container 8. Yes, it becomes a factor that reduces the detection accuracy. Of course, if the storage container 8 is made of metal, it has the effect of reflecting infrared rays and the detection accuracy is improved.

The embodiments of FIGS. 9 to 11 will be described assuming that the factor of deterioration of the detection accuracy due to the heat dissipation of the detector 1 in the embodiments of FIGS. 8 (b), 8 (c) and 8 (d) is eliminated. . In these examples, an infrared reflecting member is provided in order to prevent the radiant heat of the detection unit 1. The embodiment of FIG. 9 (a) is
The storage container 8 is made of, for example, resin, and in this case, the infrared reflecting member 13 may be formed on the inner surface of the storage container 8. Of course, the infrared reflecting member 13 may be formed on the outer peripheral surface of the heat insulating member 7. In the embodiment of FIG. 9B, the heat insulating member 7 is provided with the opening 11, and the infrared reflecting member 13 is formed on the inner wall surface of the opening 11 and the inner surface of the storage container 8 exposed from the opening 11. . The embodiment shown in FIG. 9C is
The heat insulating member 7 is provided with a concave hollow portion 12, and the infrared reflecting member 13 is formed on the inner wall surface of the concave hollow portion 12. In the embodiment of FIG. 9D, the heat insulating layer 14 is formed only by the air layer, and the infrared reflecting member 1 is formed on the inner wall surface of the storage container 8.
3 is formed. When the storage container 8 is thus made of resin, the infrared reflection member 13 is an essential requirement for improving the detection accuracy in order to prevent the heat of the detection unit 1 from being dissipated. In the embodiment of FIG. 9, when the storage container 8 is made of resin, the heat dissipation of the detection unit 1 is somewhat eliminated, and the detection accuracy is improved.

In the embodiment shown in FIGS. 8 and 9, the metal member 2 of the detector 1 is formed by die casting, cutting or the like, and the surface thereof has various finished states. The variation causes a difference in heat dissipation from the back surface of the detection unit to the heat insulating member or the storage container due to radiation, which results in variation in detection accuracy. 10A to 10D show the detection unit 1 shown in FIG. 8 in order to eliminate the variation in the detection accuracy.
The infrared reflection member 13 'is formed on the back surface of the
The description of the configuration of each embodiment will be omitted. Next, FIG.
Examples of (a) to (d) will be described. These embodiments are a combination of the embodiment of FIG. 9 and the embodiment of FIG. In the embodiment of FIGS. 11 (a) to 11 (d),
The back surface of the detection unit 2 is covered with an infrared reflecting member 13 ', and in the embodiment of FIG. 11 (a), the infrared reflecting member 13 is further formed on the inner surface of the storage container 8 or the outer peripheral surface of the heat insulating member 7. There is. In the embodiment of FIG. 11B, an infrared reflecting member 13 is further formed on the inner wall surface of the opening 11 and the inner surface of the storage container 8 exposed from the opening 11. Figure 11
In the example of (c), the infrared reflecting member 13 is further provided on the inner wall surface of the concave cavity 12. Figure 11
In (d), the entire inner wall surface of the heat insulating layer 14 including only the air layer is covered with the infrared reflecting member 13.

In the above-described embodiment, as shown in FIG. 8A, the heat insulating member 7 is in contact with the front surface of the detecting portion 1 and the heat is dissipated through the heat insulating member 7, which deteriorates the detection accuracy. ) To (d), by providing an air insulation layer of air, heat dissipation is somewhat eliminated, and detection accuracy is improved. Further, as shown in FIGS. 9B and 9C, the detection accuracy can be improved by forming the infrared reflecting member 13 on the inner wall surface of the opening 11 or the concave cavity 12. FIG. 8 (a)
9 (a) when the storage container 8 of FIG.
The infrared reflecting member 1 is provided on the inner surface of the storage container 8 as in the above embodiment.
By forming 3, the detection accuracy can be improved. By using the infrared reflecting member 13, the detection accuracy can be improved as compared with the respective embodiments of FIG. 9 corresponding to the respective embodiments of FIG. In addition, the infrared reflecting member 13 of each embodiment shown in FIG.
Need not be formed if the storage container 8 is metal. In addition, by providing a wide space as shown in FIG. 8D, it is possible to form an adiabatic layer by air, but as shown in FIGS. 10D and 11D, the infrared reflection film 13, The detection accuracy can be improved by providing 13 '. Further, since the heat radiation due to the radiant heat of the detection unit 1 can be reduced as compared with the respective embodiments of FIGS. 8 to 10 corresponding to the embodiments of FIGS. 11A to 11D,
The detection accuracy can be improved.

Next, another embodiment of the moisture sensor according to the present invention will be described with reference to FIGS. FIG.
2 to 16 show a heater 4 and a heat sensitive element 5 on a thin metal plate 19.
Shows a fixed detection part, and if this detection part is applied to the above-mentioned embodiment, the detection accuracy and the response characteristic can be improved as compared with the above-mentioned embodiment. The embodiment of FIG. 12 illustrates only the detection unit, FIG. 12 (a) is a plan view thereof, and FIG. 12 (b) is a sectional view thereof. In FIGS. 3A and 3B, a heater 4 and a heat sensitive element 5 are coated with a resin 15 or the like on a thin metal plate 21 having a good thermal conductivity such as aluminum. The heat sensitive element 5 is arranged between the heaters 4. Next, another embodiment of the detection unit will be described with reference to FIGS. FIG.
13A is a plan view thereof, and FIG. 13B is a sectional view thereof. In FIGS. 1A and 1B, an insulating film 22 is formed on a metal plate 21, 5 is a heat sensitive element, 17 is a heater composed of thin film resistors arranged in a circumferential shape, Is evenly transmitted, which contributes to improvement in detection accuracy. 14
14A is a plan view thereof, and FIG. 14B is a sectional view thereof. In FIGS. 3A and 3B, an insulating layer 22 is attached to a metal plate 21, and a chip-shaped resistor 4'is arranged on the insulating layer 22 in the same circumferential shape. Reference numeral 18 is a thick film or thin film heat-sensitive element formed on the comb-shaped electrodes. In addition, FIG.
As shown in FIGS. 16 (a) and 16 (b) and FIGS. 16 (a) and 16 (b), the heat sensitive portion and the heater may be replaced with each other.

Further, in the above-mentioned embodiment, the storage container holding the detection portion and the heat insulating material is fixed with screws. For example, the detection portion is screwed directly to the metal container storing the processing material such as sawdust. A storage container is not necessarily required if the container is attached by the method described above. Further, when the metal container itself for containing the treatment material is covered with a heat insulating member or the like, the detection unit is inserted between the metal container and the heat insulating member and fixed to the metal container, whereby the moisture sensor sufficiently functions. Also,
The air heat insulating layer may prevent the heat of the detection unit from being dissipated, or the infrared reflecting member may be covered. That is, it is also possible to use the detection unit in which the heater and the heat sensitive element are arranged as the moisture sensor.

[0024]

As described above, the moisture sensor of the present invention is
A thermosensitive element and a heater are placed and fixed in a cavity formed in a metal part having thermal conductivity that constitutes the detection unit, and the detection unit radiates heat from the surface of the detection unit to the detection target according to the moisture content of the detection target. The temperature sensor causes a temperature difference before and after heating the heater due to different degrees of heat conductivity (heat conductivity), and the moisture sensor is based on a moisture amount detecting method for detecting the moisture amount by detecting the temperature difference. Therefore, the structure of the moisture sensor is simple, and the amount of moisture can be detected by detecting the difference in temperature rise before and after heating, so the attached circuit can be simplified and miniaturized, making the moisture sensor versatile. Can be given. Further, in the moisture sensor of the present invention, the detection accuracy can be further improved by providing a cavity, an infrared reflection member, or a combination thereof on the back surface side of the detection unit in order to prevent heat dissipation. Further, since the moisture sensor of the present invention can detect the amount of moisture even when mounted on the outside of the container in which the treatment material (object to be detected) is stored, there is a problem such as corrosion of the metal member of the moisture sensor due to the treatment member or heat sensitivity. It is also highly reliable because it can solve problems such as characteristic deterioration of elements and resistors due to moisture.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a moisture sensor according to the present invention.

2 (a) is a perspective view of the detection unit of FIG. 1, and FIG. 2 (b) is a sectional view thereof.

FIG. 3 is an exploded perspective view of FIG.

4A and 4B are cross-sectional views showing a usage state of the moisture sensor.

FIG. 5 is a detection circuit of a moisture sensor.

FIG. 6 is a diagram showing a relationship between a water content, a temperature rise, and time.

FIG. 7 is a diagram showing characteristics of water content and temperature difference between the moisture sensor with and without the infrared reflecting member.

8A to 8D are cross-sectional views showing another embodiment of the moisture sensor according to the present invention.

9A to 9D are sectional views showing another embodiment of the moisture sensor according to the present invention.

10A to 10D are cross-sectional views showing another embodiment of the moisture sensor according to the present invention.

11A to 11D are sectional views showing another embodiment of the moisture sensor according to the present invention.

FIG. 12 (a) is a plan view showing a detection unit according to another embodiment of the moisture sensor of the present invention, and FIG. 12 (b) is a sectional view thereof.

13A is a plan view showing a detection unit according to another embodiment of the moisture sensor of the present invention, and FIG. 13B is a sectional view thereof.

FIG. 14 (a) is a plan view showing a detection unit according to another embodiment of the moisture sensor of the present invention, and FIG. 14 (b) is a sectional view thereof.

15A is a plan view showing a detection unit according to another embodiment of the moisture sensor of the present invention, and FIG. 15B is a sectional view thereof.

16 (a) is a plan view showing a detecting portion according to another embodiment of the moisture sensor of the present invention, and FIG. 16 (b) is a sectional view thereof.

[Explanation of symbols]

 1 Detection Part 2 Metal Member 3, 3'Cavity 4,17 Heater 4 ', 5'Lead Wire 5 Thermosensitive Element 6 Adhesive 7 Heat Insulation Member 7a Cutout 8 Storage Container 8b Recessed Fitting 8c Supporting Protrusion 11 Opening 12 Recessed Cavity 13,13 'Infrared reflecting member 14 Heat insulating layer 15 Screw 16 Resin 18 Thick or thin film heat sensitive body 19,21 Metal plate 22 Insulating layer

Claims (15)

[Claims] 1. A moisture sensor, comprising: a heat-sensitive element and a detection unit, in which a heat-sensitive element and at least one heater are fixed to a member having heat conductivity, and a heat insulating unit for preventing heat dissipation of the detection unit. . 2. A detection unit, in which a heat-sensitive element and at least one heater are arranged and fixed in a cavity provided in a metal member having thermal conductivity, and a heat insulation member supporting the detection unit.
A moisture sensor, comprising: a storage container for accommodating the detection part supported by the heat insulating member and for attaching the detection part. 3. A detection unit in which a heat-sensitive element and at least one heater are arranged and fixed on a metal plate having thermal conductivity, a heat insulating member supporting the detection unit, and the detection unit supported by the heat insulating member. And a storage container attached to the object to be detected. 4. The moisture sensor according to claim 2, wherein at least a part of the heat insulating member provided on the back side of the detection surface of the detection unit is provided with an air heat insulating layer having a cavity or an opening. 5. The moisture sensor according to claim 2, wherein the heat insulating member is made of foamed resin. 6. The moisture sensor according to claim 2, 3, 4 or 5, wherein the heat insulating member is made of any one of silicone resin, urethane resin and styrene resin. 7. The moisture sensor according to claim 3, comprising at least one heater and a thermosensitive element fixed on the metal plate by an adhesive agent. 8. A printed wiring board having a pattern formed on the metal plate via an insulating layer, and a heater or a resistor and a heat sensitive element made of chip parts are mounted on the printed wiring board. The moisture sensor according to claim 3. 9. A printed wiring board formed by patterning an insulating layer on the metal plate, and a resistor and a heat sensitive element formed on the printed wiring board as a thick film or a thin film. The moisture sensor described. 10. The moisture sensor according to claim 2, wherein the storage container is formed of a metallic infrared reflecting material. 11. The moisture sensor according to claim 2, wherein the storage container is made of resin. 12. The moisture sensor according to claim 2, wherein an infrared reflecting member is provided on the inner wall surface of the cavity or opening formed in the heat insulating member. 13. The moisture sensor according to claim 2, wherein an infrared reflection member is provided on at least one surface of the inner surface of the storage container and the back surface of the detection unit. 14. The moisture sensor according to claim 12, wherein the infrared reflecting member is a metal film or a metal plate. 15. A detection part of a moisture sensor is contacted with or embedded in a body to be detected, a heater of the detection part is heated, and the temperature of the detection part is heated by a heat-sensitive element of the detection part before heating for a predetermined time. A method for detecting the amount of water, comprising detecting the difference in temperature between the two and detecting the amount of water in the object to be detected by the temperature difference.