JP2008064616A - Resistance type humidity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resistance type humidity sensor capable of suppressing decline of detection accuracy caused by penetration of water drops to the inside of the resistance type humidity sensor, therefor loadable even on the outside of a vehicle compartment. <P>SOLUTION: A case 30 is supported by a support member 43 in the state where a case opening part 31 is faced close to the surface of a support substrate 42. A mounting substrate 10 is supported with a pair of electrodes 21, 22 and a humidity-sensitive membrane 23 formed on the mounting substrate 10 faced to the case opening part 31 inside the case 30. The resistance type humidity sensor 1 is installed with the case opening part 31 faced downward in the gravity direction to the humidity-sensitive membrane 23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resistance type humidity sensor in which a moisture sensitive film whose impedance changes according to humidity is interposed between a pair of electrodes.

  Conventionally, for example, a technique described in Patent Document 1 is known as this type of resistance humidity sensor. In this technique, a substrate on which a temperature sensor and a resistance humidity sensor are mounted is disposed in a case having the same external shape as the external shape of the case that houses the internal air sensor. In addition, an aspirator hose for taking in the air in the passenger compartment from the inside air intake port is connected to a case in which both the sensors are disposed. And the temperature sensor and the resistance type humidity sensor are mounted in the vehicle by fitting the case to which the aspirator hose is connected to the inside air sensor mounting portion formed on the instrument panel.

  FIG. 6A shows a plan structure of a general resistance-type humidity sensor employed in such a conventional technique, and FIG. 6B shows a cross-sectional structure thereof. As shown in FIG. 6A, the resistance humidity sensor 100 is in a state where a pair of comb-like electrodes 21 and 22 made of, for example, ruthenium oxide are engaged with each other on the same plane on the substrate 10 made of, for example, alumina. They are spaced apart from each other. Further, as shown in FIGS. 6A and 6B, a moisture sensitive film 23 made of, for example, an amine polymer material is formed so as to cover the pair of electrodes 21 and 22. FIG. 7 shows an equivalent circuit of a resistance humidity sensor. As shown in FIG. 7, the resistance humidity sensor 100 includes an alternating current impedance 23a in which the on resistance of the pair of electrodes 21 and 22 and the impedance of the moisture sensitive film 23 are combined, and a terminal 21a connected to the alternating current impedance 23a, 22a.

FIG. 8 shows the relationship between the relative humidity of the air (atmosphere) surrounding the resistance humidity sensor 100 thus configured and the AC impedance 23a for each air temperature. As shown in FIG. 8, regardless of the temperature of the resistance humidity sensor 100 between 5 ° C. and 35 ° C., the AC impedance 23a decreases as the relative humidity of the atmosphere of the resistance humidity sensor 100 increases. The lower the relative humidity of the air, the larger it becomes. Based on the alternating impedance 23a of the humidity sensitive film 23 that changes in this way, the relative humidity of the atmosphere of the resistance humidity sensor 100 is detected.
JP 2000-351312 A

  By the way, for example, when the fog lamp is automatically turned on and off in accordance with the fog state, it is necessary to detect the fog density outside the vehicle, that is, the humidity outside the vehicle. Therefore, it is conceivable to arrange the resistance humidity sensor 100 at a location where the humidity outside the vehicle can be detected, for example, near a wiper device or a fog lamp.

  However, the resistance-type humidity sensor 100 is originally designed for the purpose of measuring the humidity in the passenger compartment, and is not designed assuming that it is disposed outside the passenger compartment. For this reason, when the resistance humidity sensor 100 is mounted outside the passenger compartment, water drops easily enter the resistance humidity sensor 100. As described above, the resistance humidity sensor 100 includes the moisture sensitive film 23 made of an amine polymer material, and the moisture sensitive film 23 is water-soluble. For this reason, as shown in FIG. 9A, for example, water droplets may enter the resistance humidity sensor 100 during rain or car wash, and the water droplets X may adhere to the upper surface of the moisture sensitive film 23. If so, as shown in FIG. 9B, a part of the moisture sensitive film 23 is dissolved in the water droplet X. Then, as shown in FIG. 9C, the portion dissolved in the water droplet X of the moisture sensitive film 23 flows out of the resistance humidity sensor 100. In such a case, since the volume of the conductor is reduced as compared with the case where the water droplet X does not adhere to the moisture sensitive film 23, the AC impedance 23a of the moisture sensitive film 23 is increased as a whole. Therefore, even if the humidity of the atmosphere of the moisture sensitive film 23 does not actually change and the temperature is the same, the resistance humidity sensor 100 from which a part of the moisture sensitive film 23 has flowed out has an actual relative humidity. Less relative humidity. That is, the relative humidity detection accuracy may be reduced due to the ingress of water droplets into the resistance humidity sensor 100.

  In addition, when mounting the resistance type humidity sensor 100 on the vehicle, the case where it is arranged outside the passenger compartment has been described. The situation described above can occur even when the vehicle is disposed in the vehicle interior, for example, by entering into the case.

  The present invention has been made in view of the above circumstances, and the object thereof is to suppress a decrease in detection accuracy due to the ingress of water droplets into the resistance type humidity sensor. An object of the present invention is to provide a resistance type humidity sensor which can be mounted even if it exists.

  In order to achieve such an object, in the invention described in claim 1, a mounting substrate, a pair of electrodes that are spaced apart from each other on the same plane on the mounting substrate, a pair of electrodes, and a pair of electrodes A moisture-sensitive film that is formed on the mounting substrate so as to cover the impedance, and whose impedance changes according to humidity, and a case opening that is an opening for accommodating the mounting substrate and allowing air to flow inside A resistance-type humidity that includes a case formed on one surface and a support substrate that supports the case in which the mounting substrate is accommodated by a support member, and detects a change in the humidity as a change in the impedance of the moisture-sensitive film. As the sensor, the case is supported by the support member with the case opening facing the surface of the support substrate.

  The resistance humidity sensor is originally for detecting the humidity of the air surrounding the sensor. Therefore, the moisture sensitive film must be in contact with air, and the air must be preferably exchanged with the outside air of the sensor. In other words, the air must be properly distributed inside and outside the sensor. Therefore, a case opening for allowing air to flow in and out of the case is formed in the case that accommodates the pair of electrodes and the moisture sensitive film. However, the case opening not only allows the air to be detected to flow, but also causes water droplets to enter the case.

  In that respect, in the above configuration as a resistance humidity sensor, the case is supported by the support member in a state where the case opening is opposed to the surface of the support substrate. Since air is easier to flow than water droplets, even if the case opening faces the surface of the support substrate in close proximity, the air preferably circulates inside and outside the sensor. However, when the case opening is close to and opposed to the surface of the support substrate, the water droplet is less likely to enter the case due to its viscosity or the like. In this way, it is possible to suppress water droplets from entering the case, that is, water droplets from adhering to the moisture sensitive film. As a result, it is possible to further suppress a decrease in detection accuracy due to the ingress of water droplets into the humidity sensor. In addition, the resistance humidity sensor can be mounted outside the passenger compartment, for example, near a wiper blade or a fog lamp.

  In such a configuration, for example, according to the invention described in claim 2, if a protective film is formed so as to cover the moisture sensitive film, even if a water droplet enters the humidity sensor, Adheres to the protective film, not the moisture sensitive film. As a result, water droplets are prevented from adhering to the moisture sensitive film. That is, it is possible to further suppress a decrease in detection accuracy due to the ingress of water droplets into the humidity sensor. In addition, about such a moisture sensitive film | membrane, it is desirable to form with a cellulose-type liquid agent like the invention of Claim 3, for example.

  Further, in the configuration according to any one of claims 1 to 3, for example, in the invention according to claim 4, the mounting substrate is formed with the pair of electrodes and the moisture sensitive film inside the case. The surface was supported with the case facing the case opening.

  In such a structure as a resistance-type humidity sensor, the moisture-sensitive film comes to be supported by the mounting substrate in a state of facing the case opening, so that water droplets easily adhere to the moisture-sensitive film. Is concerned. However, due to the support mode of the case on the support substrate and the protective film formed so as to cover the moisture sensitive film, water drops may enter the case and the water drops may adhere to the moisture sensitive film. In the first place, such a concern is dispelled because it is restrained. Rather, such a structure is desirable for improving the detection accuracy according to the humidity of the atmosphere because the flowing air can easily touch the moisture sensitive film. In such a structure, for example, as in the invention described in claim 5, the resistance humidity sensor can be installed with the case opening facing downward in the gravitational direction with respect to the moisture sensitive film. More desirable.

  On the other hand, in order to achieve the above object, for example, as in the invention described in claim 6, a mounting substrate, a pair of electrodes that are spaced apart from each other on the same plane on the mounting substrate, A moisture-sensitive film that is formed on the mounting substrate so as to cover between the pair of electrodes, and whose impedance changes according to humidity, and an opening for accommodating the mounting substrate inside and for circulating air therein A case opening formed on one surface, a support substrate for supporting the case in which the mounting substrate is accommodated by a support member, the support substrate and the case are accommodated therein, and A resistance humidity sensor that detects a change in humidity as a change in impedance of the moisture-sensitive film, and a casing in which a casing opening that is an opening for circulating air is formed. Te, to the housing opening, may from the outside of the housing to dispose the louver forming an air passage which is inclined obliquely upward toward the interior.

  Alternatively, in order to achieve the above object, for example, as in the invention according to claim 7, the resistance humidity sensor according to any one of claims 1 to 5 is accommodated inside and air is circulated therein. And a louver that forms an air flow passage that is inclined obliquely upward from the outside to the inside of the housing. It is good to install.

  Alternatively, in order to achieve the above object, for example, as in the invention described in claim 8, the mounting substrate, the pair of electrodes arranged to be opposed to each other on the same plane on the mounting substrate and the pair of electrodes And a moisture-sensitive film that is formed on the mounting substrate so as to cover between the pair of electrodes, and whose impedance changes in accordance with humidity, and an opening for accommodating the mounting substrate inside and for circulating air therein A case opening that is a portion formed on one surface, a support substrate that supports the case in which the mounting substrate is accommodated by a support member, the support substrate and the case are accommodated inside, and an internal A resistance-type humidity that detects a change in humidity as an impedance change in the moisture-sensitive film. As capacitors, in the housing opening, it may be provided a waterproof wall which closes the lower portion of the opening.

  Furthermore, in order to achieve the above object, for example, as in the invention described in claim 9, the resistance humidity sensor according to any one of claims 1 to 5 is accommodated inside, and air is circulated therein. It is preferable to provide a housing in which a housing opening that is an opening for forming the housing is formed, and to provide a waterproof wall that closes a lower portion of the opening in the housing opening.

  As described above, the resistance humidity sensor is for detecting the humidity of the atmosphere of the sensor, and the moisture-sensitive film must be in contact with air, and the air is in contact with the sensor. It must be in good circulation inside and outside. Therefore, the case is formed with a case opening that allows air to flow inside and outside the case, and the case is also formed with a case opening that allows air to flow inside and outside the case. Must have been. However, as described above, the housing opening and the case opening not only allow the air to be detected to flow, but also allow water droplets to enter the housing, and hence water droplets to enter the case. It becomes a factor to do.

  In that respect, in the above configuration as a resistance humidity sensor (the configuration described in claims 6 to 9), the louver or the waterproof wall is disposed in the housing opening. Since air flows more easily than water droplets, even if the louver or wall is disposed in the housing opening, the air is narrowed by a gap between the slats constituting the louver or a waterproof wall. The sensor is preferably distributed inside and outside the sensor. However, when a louver or wall is disposed at the opening of the casing, water drops are less likely to enter the casing due to the slats or waterproof walls that constitute the louver. In this way, it is possible to prevent water droplets from entering the housing. As a result, it is possible to further suppress a decrease in detection accuracy due to the ingress of water droplets into the humidity sensor.

  In such a configuration, the case opening can be formed in a mesh shape, for example, as in the invention described in claim 10. Furthermore, as in the invention described in claim 11, for example, the resistance humidity sensor is disposed outside the vehicle compartment so that the humidity around the vehicle can be detected.

(First embodiment)
Hereinafter, a first embodiment of a resistance humidity sensor according to the present invention will be described with reference to FIGS. As described in detail below, the resistance humidity sensor according to the present embodiment supports the case with a support member in a state where the case opening is close to and opposed to the surface of the support substrate. The mounting substrate is supported in a state where the pair of electrodes and the moisture sensitive film formed on the mounting substrate face the case opening. Further, the resistance humidity sensor is installed with the case opening facing downward in the direction of gravity with respect to the moisture sensitive film. As a result, a decrease in detection accuracy due to the ingress of water droplets into the resistance humidity sensor is suppressed, and this can be mounted even outside the passenger compartment.

  FIG. 1 is a perspective view showing the overall structure of the resistance humidity sensor of the present embodiment, and FIG. 2 is a cross-sectional view showing the internal structure of the same embodiment. The present embodiment will be described with reference to FIGS. 1 and 2 together.

  As shown in FIG. 1, the resistance humidity sensor 1 of the present embodiment accommodates a case 30 that is also formed in a substantially rectangular parallelepiped in a case 40 that is formed in a substantially rectangular parallelepiped made of, for example, ABS resin. Configured. Further, the housing 40 is formed with a housing opening 41 that is an opening for circulating air therein.

  Specifically, as shown in FIG. 2, the resistance humidity sensor 1 is basically arranged separately from each other in a meshed state on a mounting substrate 10 made of alumina, for example, on the same plane on the mounting substrate 10. For example, a pair of comb-like electrodes 21 and 22 made of ruthenium oxide, and a pair of electrodes 21 and 22 and a space between these electrodes are formed on the mounting substrate 10, for example, made of an amine polymer material. The moisture sensitive film 23 and the like are accommodated in the case 30. As for the detection principle of the mounting substrate 10, the pair of electrodes 21 and 22, the moisture sensitive film 23, and the resistance humidity sensor using them, the pair of electrodes 21 and 22 and the moisture sensitive film 23 are on the surface side of the mounting substrate 10. 6 or 6 except for the fact that the structure of the conventional resistance humidity sensor is inverted and supported in the case 30. The configuration and principle are based on a general resistance humidity sensor that is also used in the conventional technology. Since these structures and principles have already been described in the section of the background art, overlapping description is omitted here.

  The case 30 is made of, for example, polypropylene as a forming material thereof, and is formed in a substantially rectangular parallelepiped shape as shown in FIGS. 1 and 2. However, as in the case 40, a case opening 31 is formed on the lower surface of the case 30 in FIG. As shown in FIG. 2, the case opening 31 is provided with a mesh 32 formed of, for example, polyamide. As shown in FIG. 2, the case 30 is supported by a support member 43 with the case opening 31 facing the surface of the support substrate 42 close to the case 30. Although not shown, the support substrate 42 is actually provided with a processing circuit for appropriately processing electrical signals taken out from the pair of electrodes 21 and 22 accommodated in the case 30. The support member 43 is also provided with wiring and the like for electrically connecting the processing circuit and the pair of electrodes 21 and 22 accommodated in the case 30.

  By the way, a humidity sensor is for detecting the humidity of the air (atmosphere) surrounding the sensor. Therefore, the moisture-sensitive film 23 must be in a state where it is always in contact with air, and the air must be preferably exchanged with outside air. That is, the air must be suitably distributed inside and outside the resistance humidity sensor 1. Therefore, a housing opening 41 is formed in the housing 40 and a case opening 31 is formed in the case 30 so that air can flow. However, since the resistance humidity sensor 1 of the present embodiment is disposed outside the passenger compartment, for example, in the vicinity of a vehicle wiper device or a fog lamp, the casing opening 41 and the case opening 31 are not detected. In addition to circulating the air to be circulated, water drops are allowed to enter the resistance humidity sensor 1.

  In addition, when a water droplet permeates into the resistance-type humidity sensor 1 and, further, a water droplet may adhere to the moisture-sensitive film 23, as described in the problem column, the moisture-sensitive film 23 is Since it is water-soluble, a part thereof dissolves in the attached water droplet, and the portion dissolved in the water droplet of the moisture sensitive film 23 flows out of the resistance humidity sensor 1. In such a case, since the volume of the conductor is reduced as compared with the case where water droplets are not attached to the moisture sensitive film 23, the impedance of the moisture sensitive film 23 is increased as a whole. Therefore, in actuality, even if the humidity of the atmosphere of the moisture sensitive film 23 does not change and the temperature is the same, the resistance humidity sensor 1 from which part of the moisture sensitive film 23 has flowed is The relative humidity is smaller than the humidity. That is, there is a possibility that the relative humidity detection accuracy is lowered due to the ingress of water droplets into the resistance type humidity sensor 1.

  Therefore, in the present embodiment, first, as shown in FIG. 2, the case 30 is supported by the support member 43 so that the case opening 31 and the surface of the support substrate 42 face each other with a predetermined distance “h1”, for example. At the same time, the mounting substrate 10 is supported so that the pair of electrodes 21 and 22 and the moisture sensitive film 23 formed on the mounting substrate 10 face the case opening 31 inside the case 30. Further, the resistance humidity sensor 1 is installed with the case opening 31 facing downward in the direction of gravity with respect to the moisture sensitive film 23.

  Here, the predetermined interval “h1” is set to the minimum value among the values satisfying the following conditions. First, the resistance humidity sensor 1 is left for “30 minutes” or more in an atmosphere where the wind speed is “0.6 m / sec”, the temperature is “25 ° C.”, and the relative humidity is “10% RH”. Next, within “5 seconds”, the wind speed and temperature of the atmosphere of the humidity sensor are maintained as they are, and only the relative humidity is changed to “90% RH”. Thus, the predetermined interval is set to the smallest value among the values within which the time until the output of the resistance-type humidity sensor 1 reaches “60% RH” within “30 seconds” after the change of the atmospheric conditions is made. “H1” is set. As described above, since the above condition of “30 seconds” or less is satisfied, it is possible to ensure the air circulation property and, consequently, the responsiveness of the resistance humidity sensor 1. Further, since the predetermined interval “h1” is set to the minimum value among the values satisfying the above condition, it is possible to suppress the water droplets from entering the case 30 through the case opening 31 as much as possible. Will be able to.

  In the resistance-type humidity sensor 1 configured as described above, for example, as indicated by an arrow in FIG. 1, it is assumed that air flows in from the housing opening 41 and water droplets X enter from the housing opening 41. . At this time, air flows into the case 30 through the gap between the case 30 and the support substrate 42 as indicated by arrows A1 to A3 in FIG. In addition, as shown by arrows A4 to A6 in FIG. 2, the gas flows out of the case 30 through the gap between the case 30 and the support substrate 42. That is, air is circulated suitably.

  On the other hand, as shown in FIG. 2, the water droplet X that has entered the housing 40 does not reach the gap between the case 30 and the support substrate 42 and does not enter the case 30. That is, it is suitably suppressed that water drops enter the case 30.

  The first embodiment can also be implemented as the following form, for example.

  As shown in FIG. 3 corresponding to the previous FIG. 2, a protective film 24 is formed on the moisture sensitive film 23 using, for example, a cellulose-based liquid agent so as to cover the surface of the moisture sensitive film 23. Also good. Thereby, even if the water droplet X that has entered the housing through the housing opening 41 enters the inside of the case 30, the water sensitive film 23 is protected by the protective film 24. Direct adhesion is suppressed. That is, since the water drop X is suppressed from adhering to the moisture sensitive film 23, it is possible to suppress a decrease in detection accuracy due to the penetration of the water drop X into the resistance humidity sensor 1a. As a result, the resistance humidity sensor 1a can be mounted even outside the passenger compartment. In addition, the material for forming the protective film 24 is not limited to the cellulosic liquid agent, and is arbitrary.

  In the first embodiment (including the modified example), the resistance humidity sensors 1 and 1a are installed with the case opening 31 facing the moisture sensitive film 23 downward in the gravity direction. Not limited to this.

  In the first embodiment (including the modification), the mounting substrate 10 is supported in the case 30 so that the mounting surface of the mounting substrate 10 faces the case opening 31. It is not limited to this. In addition, in the case 30, the mounting substrate 10 may be supported so that the surface opposite to the mounting surface of the mounting substrate 10 faces the case opening 31. In short, as long as the above-mentioned condition “within 30 seconds” is satisfied, the mounting posture of the mounting board in the case 30 is arbitrary.

(Second Embodiment)
Next, a second embodiment of the resistance humidity sensor according to the present invention will be described with reference to FIGS. 4 (a) and 4 (b). In FIG. 4, the same elements as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and redundant descriptions of these elements are omitted.

  FIG. 4A is a perspective view showing the overall structure of the present embodiment, and FIG. 4B is a cross-sectional view showing the internal structure of the present embodiment. As shown in FIG. 4, in the present embodiment, a louver that forms an air flow passage that is inclined obliquely upward from the outside to the inside of the housing is arranged in the housing opening. As a result, a decrease in detection accuracy due to the ingress of water droplets into the resistance humidity sensor is suppressed, and this can be mounted even outside the passenger compartment.

  As shown in FIG. 4A, the resistance-type humidity sensor 1b of the present embodiment includes a case 30 that is also formed in a substantially rectangular parallelepiped in a housing 40b that is formed in a substantially rectangular parallelepiped made of, for example, ABS resin. (Not shown in FIG. 4A) is accommodated.

  Specifically, as shown in FIG. 4B, the resistance humidity sensor 1b basically has a structure according to the resistance humidity sensor 1a shown in FIG. That is, the case opening 31 is supported by the support member 43 so as to face in the direction opposite to the surface of the support substrate 42, in other words, in the direction of gravity in FIG. 4B. More simply speaking, the structure conforms to the conventional resistance humidity sensor shown in FIG. In addition, in the case 30, the mounting substrate 10 is supported with the pair of electrodes 21 and 22 and the moisture sensitive film 23 formed on the mounting substrate 10 facing the case opening 31. Thus, since the case opening part 31 is formed toward the upper direction of the gravity direction of the case 30, air comes to flow more suitably.

  However, although air flows more suitably, the water droplet X entering from the housing opening 41b is likely to enter the inside of the case 30, and further, the water droplet X that has entered adheres to the moisture sensitive film 23. Is concerned.

  Therefore, in the present embodiment, as shown in FIGS. 4A and 4B, a louver 44 is disposed in a housing opening 41b that is an opening for circulating air inside the housing 40b. ing. Specifically, as shown in FIGS. 4A and 4B, the louver 44 has a plurality (five in the present embodiment) of wing plates 44a. As shown in FIG. 4B, the wing plate 44 a is arranged in the housing opening 41 b from the upper side to the lower side in the direction of gravity substantially parallel to the support substrate 42. However, although it is substantially parallel to the support substrate 42, the slat 44a is slightly inclined toward the diagonally upper side in the casing 40b and the diagonally lower side outside the casing 40b. As a result, the water droplet X hardly enters from the housing opening 41b into the housing 40b, and even if the water droplet X enters from the housing opening 41b into the housing 40b, the water droplet X shown in FIG. As shown, it only slightly enters the vicinity of the housing opening 41b. Therefore, even when the structure conforms to the conventional resistance humidity sensor, the water droplet X is sufficiently suppressed from adhering to the moisture sensitive film 23. In addition, it is possible to suppress a decrease in detection accuracy due to the penetration of the water droplet X into the resistance humidity sensor 1b, and the resistance humidity sensor 1b is mounted even outside the passenger compartment. Will be able to. The resistance humidity sensor 1b of the present embodiment also satisfies the condition of “30 seconds” or less described in the description of the first embodiment.

  In the resistance humidity sensor 1b configured as described above, for example, as indicated by an arrow in FIG. 4A, air flows in from the housing opening 41b and water drops X enter from the housing opening 41b. Suppose that At this time, the air flows into the housing 40b via the louver 44 as indicated by arrows C1 to C3 in FIG. 4A, for example. The air flows into the case 30 from above through the case opening 31 as indicated by arrows C4 and C5 in FIG. 4B, for example. Further, the air flows out upward in the case 30 through the case opening 31 as indicated by arrows C6 and C7 in FIG. That is, air is circulated suitably.

  On the other hand, the water droplet X hardly penetrates into the housing 40b. Even if the water droplet X enters the housing 40b from the housing opening 41b, as shown in FIG. 4B, as described above, it only slightly enters the vicinity of the housing opening 41b. It is.

(Third embodiment)
Next, a third embodiment of the resistance humidity sensor according to the present invention will be described with reference to FIGS. 5A and 5B, focusing on differences from the second embodiment. To do. 5 (a) and 5 (b), the same elements as those shown in FIGS. 1 to 4 are denoted by the same reference numerals, and the same elements are duplicated. I will omit the explanation.

  FIG. 5A is a perspective view showing the overall structure of the present embodiment, and FIG. 5B is a cross-sectional view showing the internal structure of the present embodiment. As shown in FIGS. 5A and 5B, the resistance humidity sensor of the present embodiment also basically has a structure according to the second embodiment. However, as will be described in detail below, in the present embodiment, a waterproof wall that closes the lower part of the casing opening in the direction of gravity is disposed in the casing opening. As a result, a decrease in detection accuracy due to the ingress of water droplets into the resistance humidity sensor is suppressed, and this can be mounted even outside the passenger compartment.

  As shown in FIGS. 5A and 5B, a waterproof wall 45 is disposed in a housing opening 41c, which is an opening for allowing air to flow inside the housing 40c. Specifically, as shown in FIG. 5B, the waterproof wall 45 has a predetermined height “h2” in the vicinity of the casing opening 41c and upward in the gravity direction with reference to the lower surface of the inner wall of the casing 40c. Is formed. Here, the predetermined height “h2” is set to the maximum value among the values satisfying the condition of “30 seconds” described in the first embodiment. That is, first, the resistance type humidity sensor 1 is left for “30 minutes” or more in an atmosphere where the wind speed is “0.6 m / sec”, the temperature is “25 ° C.”, and the relative humidity is “10% RH”. . Next, within “5 seconds”, the wind speed and temperature of the atmosphere of the humidity sensor are maintained as they are, and only the relative humidity is changed to “90% RH”. In this way, the predetermined value is set to the largest value among the values in which the time until the output of the resistance type humidity sensor 1c reaches “60% RH” within “30 seconds” after the change of the atmospheric condition is made. “H2” is set. As a result, the water droplet X hardly enters the housing 40c from the housing opening 41c, and even if the water droplet X enters the housing 40c from the housing opening 41c, the water droplet X shown in FIG. As shown, it only slightly enters the vicinity of the housing opening 41c.

  In the resistance humidity sensor 1c configured as described above, for example, as indicated by an arrow in FIG. 5A, air flows in from the housing opening 41c and water droplets X enter from the housing opening 41c. Suppose that At this time, the air flows into the inside of the housing 40c from the housing opening 41c whose opening area is narrowed by the waterproof wall 45 as indicated by arrows D1 and D2 in FIG. The air flows into the case 30 from above through the case opening 31 as indicated by arrows D3 and D4 in FIG. 5B, for example. Further, the air flows out upward inside the case 30 through the case opening 31 as indicated by arrows D5 and D6 in FIG. 5B. That is, air is circulated suitably.

  On the other hand, the water droplet X hardly penetrates into the housing 40c. Even if the water droplet X enters the housing 40c from the housing opening 41c, as shown in FIG. 5B, as described above, it only slightly enters the vicinity of the housing opening 41c. It is.

(Other embodiments)
The resistance-type humidity sensor according to the present invention is not limited to the structure exemplified in each of the above-described embodiments, and can be implemented as, for example, the following embodiment in which the embodiment is appropriately changed.

  In the second or third embodiment, as shown in FIG. 4 (b) or FIG. 5 (b), a resistance type having a structure according to the conventional resistance type humidity sensor shown in FIG. Although the humidity sensor is housed inside the housing 40b or 40c, the resistance humidity sensor housed inside is not limited to this structure. In addition, the resistance-type humidity sensor having the structure shown in FIG. 3 as the first embodiment shown in FIG. 2 or its modification may be housed inside the housing 40b or 40c.

  In each of the above-described embodiments (including modifications), the case opening 31 is provided with the mesh 32. However, the material of the mesh 32 is not limited to polyamide, and the material is arbitrary. In short, the case opening 31 may be formed in a mesh shape. Moreover, it is good also as a structure which omitted arrangement | positioning of such a mesh 32, and forming the case opening part 31 in mesh shape itself.

  In the above embodiments (including modifications), the resistance humidity sensors 1 to 1c are mounted in the vicinity of the wiper blade and the fog lamp of the vehicle, but the mounting position is not limited to this. It can be installed in either the vehicle interior or the vehicle interior. Moreover, it is not restricted to a vehicle. In addition, its application range is wide, such as trains and airplanes, and it is effective when mounted on various mobile objects.

The perspective view which shows the whole structure about 1st Embodiment of the resistance-type humidity sensor concerning this invention. Sectional drawing which shows the cross-section of the said 1st Embodiment. Sectional drawing which shows the cross-section of the modification of the said 1st Embodiment. (A) is a perspective view which shows the whole structure about 2nd Embodiment of the resistance-type humidity sensor concerning this invention. (B) is sectional drawing which shows the cross-sectional structure. (A) is a perspective view which shows the whole structure about 3rd Embodiment of the resistance-type humidity sensor concerning this invention. (B) is sectional drawing which shows the cross-sectional structure. (A) is a top view which shows the planar structure about a general resistance-type humidity sensor. (B) is sectional drawing which shows the cross-sectional structure. The equivalent circuit diagram of a general resistance type humidity sensor. The graph which shows the relationship between the relative humidity of the air surrounding the said resistance-type humidity sensor, and the alternating current impedance of a moisture sensitive film according to air temperature, respectively. (A) is a schematic diagram which shows the state in which the water droplet adhered to the moisture sensitive film. (B) is a schematic diagram showing a state in which a moisture-sensitive film is dissolved in attached water droplets. (C) is a schematic diagram which shows the state after the outflow of the dissolved moisture sensitive film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c, 100 ... Resistance humidity sensor, 10 ... Mounting board, 21, 22 ... Electrode, 21a, 22a ... Terminal, 23 ... Humidity sensitive film, 23a ... AC impedance, 24 ... Protective film, 30 ... Case, 31 ... Case opening, 32 ... Mesh, 40, 40b, 40c ... Housing, 41, 41b, 41c ... Housing opening, 42 ... Support substrate, 43 ... Support member, 44 ... Louver, 44a ... Blade 45 ... Waterproof wall.

Claims (11)

A mounting board;
A pair of electrodes disposed opposite to each other in the same plane on the mounting substrate;
A moisture sensitive film formed on the mounting substrate so as to cover between the pair of electrodes and the pair of electrodes, and the impedance changes according to humidity;
A case in which the mounting substrate is housed inside, and a case opening which is an opening for circulating air inside is formed on one surface;
A support substrate that supports the case in which the mounting substrate is accommodated by a support member;
A resistance humidity sensor that detects a change in humidity as a change in impedance of the moisture sensitive film,
The resistance humidity sensor according to claim 1, wherein the case is supported by the support member with the case opening facing the surface of the support substrate.   The resistance humidity sensor according to claim 1, wherein a protective film is formed so as to cover the moisture sensitive film.   The resistance humidity sensor according to claim 2, wherein the protective film is formed of a cellulose-based liquid agent.   The said mounting substrate is supported in the said case in the state in which the surface in which the said pair of electrode and the said moisture sensitive film were formed faced the said case opening part inside the said case. Resistance humidity sensor.   The resistance humidity sensor according to claim 4, wherein the resistance humidity sensor is installed in a state where the case opening faces downward in the direction of gravity with respect to the moisture sensitive film. A mounting board;
A pair of electrodes disposed opposite to each other in the same plane on the mounting substrate;
A moisture sensitive film formed on the mounting substrate so as to cover between the pair of electrodes and the pair of electrodes, and the impedance changes according to humidity;
A case in which the mounting substrate is housed inside, and a case opening which is an opening for circulating air inside is formed on one surface;
A support substrate for supporting the case containing the mounting substrate by a support member;
A housing in which a housing opening that is an opening through which the support substrate and the case are housed and in which air is circulated is formed.
A resistance humidity sensor that detects a change in humidity as a change in impedance of the moisture sensitive film,
The resistance humidity sensor according to claim 1, wherein a louver that forms an air flow passage that is inclined obliquely upward from the outside to the inside of the housing is disposed in the housing opening. The resistance humidity sensor according to any one of claims 1 to 5 is housed inside, and a housing having a housing opening that is an opening for circulating air therein is provided.
The resistance humidity sensor according to claim 1, wherein a louver that forms an air flow passage that is inclined obliquely upward from the outside to the inside of the housing is disposed in the housing opening. A mounting board;
A pair of electrodes disposed opposite to each other in the same plane on the mounting substrate;
A moisture sensitive film formed on the mounting substrate so as to cover between the pair of electrodes and the pair of electrodes, and the impedance changes according to humidity;
A case in which the mounting substrate is housed inside, and a case opening which is an opening for circulating air inside is formed on one surface;
A support substrate for supporting the case containing the mounting substrate by a support member;
A housing in which a housing opening that is an opening through which the support substrate and the case are housed and in which air is circulated is formed.
A resistance humidity sensor that detects a change in humidity as a change in impedance of the moisture sensitive film,
A resistance humidity sensor, wherein a waterproof wall that closes a lower portion of the opening is disposed in the housing opening. The resistance humidity sensor according to any one of claims 1 to 5 is housed inside, and a housing having a housing opening that is an opening for circulating air therein is provided.
A resistance humidity sensor, wherein a waterproof wall that closes a lower portion of the opening is disposed in the housing opening.   The resistance-type humidity sensor according to any one of claims 1 to 9, wherein the case opening is formed in a mesh shape.   The resistance humidity sensor according to any one of claims 1 to 10, wherein the resistance humidity sensor is disposed outside a passenger compartment in a vehicle and detects humidity around the vehicle.

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