JP2001281182A - Humidity detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a humidity detector provided with countermeasures taken against dew formation and to provide a device capable of outputting humidity information depending on the measured temperature of a measured atmosphere. SOLUTION: A humidity reflecting information detecting part 2 has a dew point sensor 4 (or an absolute humidity sensor) and is equipped with a heater 5 as a heating means for heating the detecting part 2 in order to prevent dew formation on the detecting part 2. A temperature sensor 8 is provided for measuring the temperature of the measured atmosphere in a position separate from the detecting part 2 heated by the heater 5 as the heating means. Humidity information such as relative humidity information changing dependently on the temperature of the atmosphere is produced and outputted based on temperature information measured by the sensor 8 and on information on the dew point produced by the detecting part 2. Since the dew point and absolute humidity do not depend on the temperature of the atmosphere, their values are not varied by the heating. This can provide stable measured values and provide accurate humidity information based on the values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidity detecting device for detecting humidity in an atmosphere, and more particularly to a humidity detecting device capable of measuring a high-humidity atmosphere where dew condensation easily occurs.

[0002]

2. Description of the Related Art When measuring humidity in an atmosphere of high humidity, the detecting unit is liable to dew condensation, and once the humidity sensor is dewed, it takes a long time to recover and measurement cannot be performed. Conventionally, as a countermeasure, by heating the surroundings of the humidity sensor, raising the temperature to prevent dew condensation, and installing temperature sensors at two locations around the detection unit and in the atmosphere to measure the temperature before and after the rise, respectively, There has been proposed a method of calculating a relative humidity in an atmosphere by correcting a detected value of a relative humidity after a temperature rise to a temperature before a rise by a calculation. (See, for example, Japanese Patent Publication No. 6-67979 and Japanese Patent Application Laid-Open No. 7-244008)

[0003]

In the prior art, in order to accurately measure the humidity, it is necessary to accurately measure the temperature of the humidity sensor that has risen due to heating. To do this, a temperature sensor must be placed very close to the humidity sensor and the temperature must be measured accurately. This is a major obstacle to reducing the size and cost of the detection unit. Further, an extra circuit for measuring the temperature is required.

[0004] It is an object of the present invention to provide a humidity detecting device in which dew condensation prevention measures are taken, and a device capable of outputting humidity information depending on a measured temperature of an atmosphere to be measured.

[0005]

Means for Solving the Problems and Action / Effects In order to solve the above problems, a humidity detecting device of the present invention comprises:
A humidity reflection information detecting unit for detecting information reflecting the humidity of the atmosphere to be measured (hereinafter referred to as humidity reflection information) has at least one of a dew point sensor and an absolute humidity sensor. A heating means for heating the reflection information detecting section is provided.

In the case of humidity measurement in a high-humidity environment, the measured value may not accurately indicate the actual humidity value of the atmosphere to be measured due to dew condensation occurring in the detection unit and the like. In particular, when the relative humidity is close to 100% (for example, 90% or more), dew condensation is likely to occur due to the influence of temperature fluctuation, and when the surface temperature of the device constituting the detection unit is low. In this case, even when the measured atmosphere does not reach the dew condensation, the temperature of the measured atmosphere drops near the surface of the detection unit and dew forms. By heating the humidity reflection information detection unit as in the present invention, such dew condensation is prevented, and the measurement target atmosphere is in a state in which water vapor is sufficiently mixed (that is, the amount of water vapor in the measurement target atmosphere is reduced due to dew condensation). Stable state). In addition, since the dew point and the absolute humidity do not depend on the temperature of the atmosphere to be measured, there is no numerical change due to heating, and a stable value can be measured. Based on this, accurate humidity information of the atmosphere can be obtained.

Specifically, the humidity detecting device of the present invention includes a temperature sensor for measuring the temperature of the atmosphere to be measured at a position different from the humidity reflection information detecting section heated by the heating means. Based on the measurement information and the information on the dew point and / or the absolute humidity of the humidity reflection information detecting section, the information processing apparatus can be configured to include a calculating section that calculates and outputs humidity information that changes depending on the temperature of the detected atmosphere.

For example, when measuring relative humidity in a high-humidity environment, the above-mentioned publication uses a relative humidity sensor and a temperature sensor disposed at a position different from the relative humidity sensor. In the relative humidity sensor, dew condensation is prevented by heating means such as a heater, but the relative humidity of the atmosphere to be measured is measured in a heated state, and correction is made based on the ambient temperature measured by the temperature sensor.

However, when such a method is used, the detected temperature value varies even if the temperature in the atmosphere is constant if the holding temperature of the relative humidity sensor is not stable. For example, if the holding temperature of the detection unit of the relative humidity sensor fluctuates due to uneven heating of the heater or disturbance applied to the atmosphere, the output of the temperature detection unit receives a large change, and as a result, the correction by the temperature sensor is performed. This also causes an error in the measured value of the relative humidity. In particular, in a situation where the ambient temperature is rapidly changing, the error is further increased due to the difference in the responsiveness between the relative humidity sensor and the temperature sensor.

In the present invention, even if the heating temperature of the humidity reflection information detecting section slightly fluctuates, information relating to the dew point or absolute humidity, which is humidity information independent of temperature, is measured. Not receive. Therefore, based on the temperature information measured at a position different from the detection unit, it is possible to stably and accurately measure humidity information that changes depending on the temperature, for example, relative humidity, enthalpy, mixing ratio, discomfort index, and the like.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to embodiments shown in the drawings. FIG. 1 is a configuration diagram of a humidity detector using a dew point sensor according to the present invention. A humidity reflection information detection unit 2 (hereinafter simply referred to as detection unit 2) for detecting information (hereinafter, referred to as humidity reflection information) that reflects the humidity of the atmosphere to be measured has a dew point sensor 4 to prevent dew condensation. For this purpose, a heater 5 is provided as a heating means for heating the humidity reflection information detecting section 2. The heater 5
A heater power supply 12 for supplying electric power to the heater 5 is provided.

Also, at a position different from the humidity reflection information detecting section 2 heated by the heater 5 as a heating means,
A temperature sensor for measuring the temperature of the atmosphere to be measured, which changes depending on the temperature of the atmosphere to be detected based on temperature measurement information from the temperature sensor and information on the dew point of the humidity reflection information detection unit; An arithmetic circuit 9 as an arithmetic unit for arithmetically outputting the humidity information is provided. Then, the humidity reflection information detection unit 2 is heated to measure the dew point in a state where dew condensation is prevented, and humidity information (hereinafter, referred to as temperature dependent humidity) depending on the temperature based on the measured dew point and the temperature measured by a temperature sensor provided at another position. For example, relative humidity information is output. The output of the temperature-dependent information means not only that a numerical value (for example, a relative humidity value) is visually displayed, but also that the signal relating to the temperature-dependent humidity information, for example, an electrical signal, an optical signal, or a mechanical signal. Outputting various signals such as signals (for example, outputting to a separate device or the like as a signal transmission target) is also included as a concept.

In the case of humidity measurement in a high-humidity environment, the measured value may not accurately indicate the actual humidity value of the atmosphere to be measured due to dew condensation occurring in the detection unit and the like. In particular, when the relative humidity is close to 100% (for example, 90% or more), dew condensation is likely to occur due to the influence of the temperature fluctuation. When the surface temperature or the like is low, even if the measured atmosphere does not reach the dew condensation, the temperature of the measured atmosphere drops near the surface of the detection unit and dew forms. When the dew condensation occurs, the amount of water vapor mixed into the atmosphere to be measured decreases, and the information by the humidity reflection information detecting unit such as the dew point sensor does not accurately reflect the humidity information in the actual atmosphere to be measured.

[0014] Further, once dew condensation occurs, a considerable amount of time is required until the dew condensation is removed, resulting in a delay in sensing. By heating the humidity reflection information detection unit as in the present invention, such dew condensation is prevented, and the measurement target atmosphere is in a state in which water vapor is sufficiently mixed (that is, the amount of water vapor in the measurement target atmosphere is reduced due to dew condensation). Stable state). In particular, if the humidity reflection information detection unit is set to a value sufficiently higher than the temperature value that can be taken by the atmosphere to be measured, dew condensation does not occur even if the temperature fluctuates slightly, and highly accurate measurement can be performed. Further, since the dew point and the absolute humidity do not depend on the temperature of the atmosphere to be measured, there is no numerical change due to heating, stable measurement can be performed, and accurate humidity information of the atmosphere can be known based on the measurements.

As the dew point sensor 4, various known dew point sensors can be used. For example, the position where dew can be formed
Method of automatic optical measurement with a constant line, method of detecting dew by changing the resonance frequency of the quartz oscillator, dew point sensor using the electronic cooling method, raising the temperature of the object coated with LiCl, the vapor pressure of the saturated aqueous solution of LiCl Various dew point sensors can be used, such as a method in which the dew point is a temperature at which the temperature becomes equal to the surrounding vapor pressure.

FIG. 2 shows an example of a heating method in the dew point sensor 4. In FIG. 2A, as an example of a dew point sensor, light (for example, laser light) is applied to the mirror body 26, and reflected light from the mirror body 26 is detected to detect a change in reflected light to detect a dew condensation state. 1 shows a sensor (so-called optical dew point sensor) that measures the temperature at the time of detection as a dew point. The dew point sensor 4 is provided with a light illuminating portion 24a for illuminating light and a mirror 26 for reflecting the illuminated light, and is reflected by a light receiving portion 24b for receiving light reflected from the mirror 26. Is detected. The reflector 26 is cooled by cooling means (for example, a known electronic cooling mechanism applying the Peltier effect or the like),
The surface temperature is changed, and the surface temperature is measured by a separately provided temperature sensor.

In the present invention, a heater 5 as a heating element can be arranged around the dew point sensor 4 as schematically shown in the side view of FIG. By providing the heater 5 so as to heat the entire dew point sensor 4, the dew point sensor 4 is in a state where the dew point is higher than the dew point of the atmosphere to be measured (preferably, no dew condensation occurs even when the temperature of the atmosphere to be measured fluctuates). Temperature, that is, a state sufficiently higher than the dew point temperature of the atmosphere to be measured) to prevent dew condensation. (When the dew point sensor 4 adopts a unit configuration like the optical dew point sensor of FIG. 2A, the entire unit can be heated.) As an example of the arrangement of the heater 5 as a heating unit, It is desirable to arrange so as to surround the dew point sensor 4 as schematically shown in the plan sectional view of FIG. By doing so, the bias of heating in the dew point sensor 4 does not occur, and the whole can be heated evenly.

As shown in FIG. 3, the humidity reflection information detecting section 2 is provided with an absolute humidity sensor 32, and detects temperature-dependent humidity information based on measurement information on absolute humidity and information on temperature by the temperature sensor 8. It may be obtained. The conversion to temperature-dependent humidity information using these parameters (absolute humidity information and temperature information) will be described later. By arranging the heater 5 as a heating element around the absolute humidity sensor 32, it is possible to obtain the same effect as that of the dew point sensor (dew condensation preventing effect and the like). FIG.
In the example shown in (a), an absolute humidity sensor 32 is provided inside a cylindrical heater 5 (for example, a heater 5 having a heating wire 34a). Is always in a heated state. The atmosphere to be measured is taken in from the opening of the hole 33 formed in the heater itself, and can pass through the vicinity of the absolute humidity sensor 32 and flow to another opening (not shown).

As a result, the absolute humidity sensor 32 prevents condensation even in a high-humidity environment, stably maintains the mixed state of water vapor in the atmosphere to be measured, and provides extremely accurate humidity measurement even in a high-humidity environment. Becomes possible. As the absolute humidity sensor to be used, various types that can be estimated by those skilled in the art, such as an absolute humidity sensor using heat conduction, can be used.

As shown in a modified example in FIG. 3B, a humidity reflection information detecting unit (for example, FIG. 3B)
At least a portion (preferably, surrounding the humidity reflection information detection unit) around the absolute humidity sensor 32). In the configuration of FIG. 3B, a heater 5 (for example, a bar-shaped or plate-shaped heater) is provided near the absolute humidity sensor 32, and the periphery thereof is covered with a filter 35. As the filter 35, for example, a filter formed of a porous resin formed product made of a fluorine-based resin such as polytetrafluoroethylene can be used. As a commercially available product of such a porous resin formed product, for example, a Fluoropore membrane filter manufactured by Sumitomo Electric Industries, Ltd. can be used.

As the porous resin formed article made of a fluorine-based resin, for example, an unsintered molded article of polytetrafluoroethylene (hereinafter, referred to as PTFE) is formed by heating a green body at a heating temperature lower than the melting point of PTFE in one or more axes. The porous fiber structure obtained by stretching the film has excellent barrier properties against water droplets, oil, dust, and other substances related to dirt. The filter 35 has the effect of suppressing forced convection and the like in the atmosphere to be measured, that is, the effect of preventing the influence of wind generated on the absolute humidity sensor, and the atmosphere to be measured passes through the filter 35 while the mixed state of water vapor is maintained. Becomes

As shown in FIG. 3C, the filter is covered with the above-mentioned filter 35 so as to surround the absolute humidity sensor 32, and the unit is constituted by the filter 35 and the absolute humidity sensor 32 (preferably the unit). A heater 5 as a heating means may be arranged so as to surround the whole. By doing so, the filter 35 can be heated from the outside, and dew condensation on the outer surface and the like of the filter 35 can also be prevented. 3B and 3C, that is, inside the filter 35 and around the filter 35 (preferably surrounding the filter 35).
In both cases, the heater 5 may be provided.

When using either the dew point sensor or the absolute humidity sensor as described above, the temperature sensor 8 is provided at a position different from the humidity reflection information detecting section. Further, the temperature sensor 8 measures the temperature of the atmosphere to be measured which is not affected by heating by the heater 5 in the environment to be measured (that is, the temperature of the atmosphere to be measured before heating by the heater). Therefore, the atmosphere to be measured is not heated by the heater 5. Note that the type of the temperature sensor may be a known one, for example, a resistance temperature detector, a thermocouple, a thermistor, a transistor thermometer, a crystal thermometer, and various other types that can be estimated by those skilled in the art.

FIG. 4 is a block diagram showing an example of the electrical configuration of the present invention, and shows an example of a method of processing information obtained by the humidity reflection information detection unit and the temperature sensor. Regardless of whether a dew point sensor or an absolute humidity sensor is used as the humidity reflection information detection unit, the humidity reflection information obtained by the detection unit 2 is detected by a detection circuit (for example, the dew point detection circuit 6 in the case of the dew point sensor 4). ).

For example, the detection voltage from the dew point sensor 4 is linearized by a dew point detection circuit 6 (for example, a circuit having a known linearization circuit using an operational amplifier or the like) and converted into an electric signal proportional to the dew point. Similarly, the detection voltage from the temperature sensor 8 can also be linearized by the temperature detection circuit 10, and these are converted into temperature-dependent humidity information by a calculation method described later.

The electric signals linearized by the dew point detecting circuit 6 and the temperature detecting circuit 10 are input to an arithmetic circuit 9 which is a circuit for converting into humidity information depending on the temperature, respectively. Dependent humidity information (for example, relative humidity information shown in the present embodiment) is calculated and output. Note that the relative humidity can be calculated using a known calculation formula if the dew point (or the absolute humidity) and the measured atmosphere temperature are determined.

FIG. 4 is a block diagram showing an example of the circuit configuration of the arithmetic circuit 9. That is, the arithmetic circuit can be configured to include a microcomputer, and the relative humidity value can be obtained by referring to a table provided in the microcomputer based on the dew point and the temperature. More specifically, based on the dew point information (or absolute humidity information) and temperature information linearized by the dew point detection circuit 6 and the temperature detection circuit 10 using the above-described method and the like, a table as shown in FIG. With reference to (table storing relative humidity information in a form corresponding to dew point information and temperature information), the corresponding relative humidity information is read. For example, as shown in FIG. 5, electrical information from each sensor, for example, linearized voltage information is converted into dew point information (for example, dew point value) and temperature information (for example, temperature value) using a table, respectively. The relative humidity can be calculated based on the converted dew point and temperature. Converts the linearized voltage value V _d to the measured dew point values T _d based on the information obtained by the dew point sensor 4 in the table of FIG. 5 (Table 49c), similarly the voltage based on the temperature sensor 8 It converts the value _{V r} to the measured ambient temperature value _{T r} (table 49d), their dew point values _{V d} and the temperature values T
Based on _r , the relative humidity R can be determined by the table 49b (also referred to as the temperature / dew point-relative humidity conversion table 49b or simply the relative humidity conversion table 49b) shown in FIG. It should be noted that it is also possible to adopt a table configuration in which the relative humidity is directly obtained based on the voltage values V _d and V _r without being once converted into the dew point value and the temperature value. Further, the table 49b in the present embodiment can be constituted by data using a known formula for calculating the relative humidity based on the dew point or the absolute humidity and the temperature of the atmosphere to be measured. Further, the above-mentioned tables 49b to 49d are stored in the ROM 45,
Reference can be made as appropriate in accordance with the control command from 43.

The read relative humidity information is output via the I / O port 46 in FIG. The output signal value may be output as a digital signal or may be output as an analog signal via the D / A converter 47. It can be adapted to the use form of the output transmission target. For example, the relative humidity information as the calculation result may be output to various display devices such as a liquid crystal display as a temperature-dependent humidity value display means and a 7-segment LED. The data generation based on the electrical information from the sensors 4 and 8 and other input / output from the microcomputer can be executed by the CPU 43 based on the control program 49a. For storing various measured value data or calculated value data in each process, the work area 48a or the calculated value storage area 48 in the RAM 44 is used.
b etc. can be used.

A circuit configuration using an analog circuit as shown in FIG. 7 may be used. That is, the detection voltage values detected by the dew point temperature sensor 4 and the temperature sensor 8 are respectively converted into the linearization circuits 52 via the voltage followers 50a and 50b.
Linearized by a and 52b, respectively. When the dew point is determined, the information on the water vapor pressure of the measured atmosphere at the time of the measurement can be linearized by the linearization circuit 52a.
On the other hand, based on the temperature measured by the temperature sensor 8, the information on the saturated water vapor pressure at the measured temperature is linearized by the linearization circuit 52b. These linearized information, that is, the linearized information on the measured water vapor pressure and the linearized information on the saturated water vapor at the measurement temperature are logarithmized by logarithmic circuits 54a and 54b (for example, log amplifiers), and are differentially amplified by a differential amplifier 56. By obtaining the difference, each logarithmic information can be subtracted. The division information is taken out by an antilogarithmic circuit 58 (for example, Antilog amplifier or the like), and the water vapor pressure value in the measurement atmosphere is divided by the saturated water vapor pressure value at the measurement temperature of the measurement atmosphere to obtain the relative humidity. Can be. The arithmetic circuit 9 that enables such a division operation may be configured as a unit by the division circuit IC.

Note that a similar circuit configuration (ie, a configuration using a microcomputer shown in FIG. 4, a configuration using an analog circuit shown in FIG. 7, etc.) is adopted even when an absolute humidity sensor is used instead of the above-described dew point sensor. be able to. In this case, humidity information depending on the temperature, for example, relative humidity information is generated by the absolute humidity information by the absolute humidity sensor and the temperature information by the temperature sensor. For example, the conversion table shown in FIG. 6 may be an absolute humidity / temperature-relative humidity conversion table.

In addition to the relative humidity, enthalpy, mixture ratio, discomfort index and the like can be output as the output of the temperature-dependent humidity information. In addition, since parameters for determining these values are two elements of temperature and dew point (or absolute humidity), if these are known, they can be calculated using a known formula. In the present embodiment, the arithmetic circuit 9 has a built-in arithmetic circuit for relative humidity.
If this arithmetic circuit is changed to one corresponding to each temperature-dependent humidity information, each value can be output. For example, temperature / dew point-relative humidity conversion table
If an enthalpy conversion table is used, an enthalpy value can be easily output. It should be noted that the present invention is not limited to this, and any value may be used as long as it is temperature-dependent humidity information that can be determined by two factors of temperature and dew point (or absolute humidity) (for example,
Mixing ratio, discomfort index, etc.).

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a humidity detection device of the present invention.

FIG. 2 is an explanatory diagram showing a configuration example of a dew point sensor and an arrangement example of a heating element.

FIG. 3 is an explanatory diagram showing a configuration example using an absolute humidity sensor.

FIG. 4 is a block diagram showing an example of an electrical configuration of the humidity detection device shown in FIG.

FIG. 5 is a diagram showing an example of a data conversion table.

FIG. 6 is a diagram illustrating an example of a dew point / temperature-relative humidity conversion table.

FIG. 7 is a block diagram showing a modification of FIG. 4;

[Explanation of symbols]

 2 Humidity reflection information detection unit 4 Dew point sensor 5 Heater (heating element) 6 Dew point detection circuit 8 Temperature sensor 10 Temperature detection circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideaki Yagi 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Inside Japan Specialty Ceramics Co., Ltd. (72) Inventor Takahito Kojima 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Inside (72) Inventor Yuji Tsubota 1-3-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo Tokyo Electric Power Company (72) Inventor Masahiko Kumagai 1-3-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo Tokyo Electric Power Company (72) Inventor Tadahiko Ichimoto 2-12-36-104, Shirokanedai, Minato-ku, Tokyo (72) Inventor Hiroshi Yamada 2-5-1-12 Kyobashi, Chuo-ku, Tokyo Inside Toyo Thermal Industry Co., Ltd. (72) Inventor Hiroshi Murakami 2-5-12 Kyobashi, Chuo-ku, Tokyo F-term (reference) 2G040 AA04 AB03 BA12 BA23 CA02 CA12 CA23 DA02 DA03 DA12 EA02 EB02 EC09 GA05 GA07 HA11 HA16 ZA06

Claims (4)

[Claims] 1. A humidity reflection information detecting unit for detecting information reflecting the humidity of an atmosphere to be measured (hereinafter referred to as humidity reflection information) has at least one of a dew point sensor and an absolute humidity sensor to prevent dew condensation. A humidity detecting device for heating the humidity reflection information detecting section. 2. The heating device according to claim 2, wherein the dew point sensor and / or
The humidity detecting device according to claim 1, further comprising a heating element disposed around the absolute humidity sensor. 3. A temperature sensor for measuring a temperature of the atmosphere to be measured at a position different from the humidity reflection information detecting section heated by the heating means, wherein the temperature measurement information by the temperature sensor and the humidity reflection information are provided. The humidity detection device according to claim 1, further comprising a calculation unit that calculates and outputs humidity information that changes depending on the temperature of the detected atmosphere, based on information on the dew point and / or absolute humidity of the information detection unit. . 4. The humidity according to claim 3, wherein the arithmetic unit calculates and outputs information on at least one of a relative humidity, an enthalpy, a mixture ratio, and a discomfort index as the humidity information that changes depending on the temperature. Detection device.