JPS5814040A - Humidity detector - Google Patents

Abstract

PURPOSE:To prevent deterioration in adsorption of moisture due to contaminated materials in the air, by finding humidity in the air from measurement of termperature of air before and after passage of a cooler. CONSTITUTION:An electronic cooling (heating) element, consisting of P type and N type semiconductors 12 and 13 and electrodes 14-16 connected to opposite ends of each of the two semiconductors, thermal conduction plates 18, 19, firmaly adhering to their respective electrodes and constituting a wall surface at the inside of a container and a part of the wall surface of the container, are installed at the inside of a container 11 isolated from the air, and perforations 20 and 21 for the air current at the inside and the outside of the container 11 are formed therein. Thermometers 22 and 23 are mounted at the inside and the outside of the container 11, and each output is supplied to a computer 24 to compute a temperature difference. The computing output and an output of an element 17 are applied to a computer 28 to find an absolute humidity value to display it in an indicator 29.

Description

[Detailed description of the invention] The present invention relates to a humidity detector that measures atmospheric humidity.

Conventional humidity detectors are used by being exposed to air containing various components such as water vapor. Some substances adhere to the surface of the constituent materials and reduce the functionality of the humidity sensor. Humidity is also related to the temperature of water vapor in the air and varies over a wide range. In a type of sensor that detects a change in the electrical properties of a material due to moisture adsorption, if, for example, an oil component is adsorbed onto the surface of the detector as described above, this will affect the moisture adsorption and reduce the detection ability.

If the detector is regenerated by heating cleaning when contaminated with contaminants, it cannot detect humidity during heating cleaning, making continuous detection impossible and limiting the number of places where it can be used. In addition, since the temperature of the device is high (400 to 5,000 ℃), the places where it can be used are further limited.

The present invention was made to eliminate the above-mentioned drawbacks, and its purpose is to capture atmospheric humidity in the form of a load on a cooling (heating) device with a constant capacity, and to prevent dew condensation from forming inside the detector. The purpose of this invention is to provide a humidity sensor which is determined by measuring the air temperature before and after passing through the cooler, and which does not suffer from functional deterioration (deterioration of moisture adsorption caused by pollutants in the atmosphere).

As such a cooler (heater), an electronic cooler (heater) that utilizes the Peltier effect is suitable.

That is, 1 the present invention provides a small chamber separated from the outside air so that the atmosphere can circulate, a cooler or a heater with a constant capacity for cooling or heating the atmosphere within the nuclear chamber within a temperature range that does not cause condensation, and a The present invention relates to a humidity sensor characterized by comprising a thermometer placed in the room, and a temperature needle placed outside the small room.

Hereinafter, the present invention will be described with reference to an embodiment. In FIG. 1, a P-type semiconductor 12 and an N-type semiconductor 13 are connected to both ends of each of the P-type semiconductor 12 and N-type semiconductor 13 inside a container 11 separated from the outside air. Electronic cooling consisting of electrodes 14.15°16 (
a heating) element 17, and heat conductive plates 18 and 19 fixed to the electrodes and forming a wall inside the container and a part of the wall of the container.

A part of the container has a communication hole 2 for circulating the inside and outside atmosphere.
0.21 is set. Moreover, inside and outside of the container 11,
Thermometers 22 and 23 are provided, and the outputs of these temperature needles are supplied to a calculator 24.

DC current is supplied from the power supply 27 to the input terminals 25 and 26 of the electronic cooling (heating) element 17 to cool (cool) the element.
heating).

When the air inside the container is cooled or heated with the above structure, the air flows through natural convection, or when a certain amount of air is circulated, a temperature difference occurs between the thermometers 22 and 23 inside and outside the container.
The difference is calculated by the calculator 24.

Now, considering the change in the state of the container due to cooling (heating) within the container 11, the enthalpy h per liter of dry air is given by one equation.

h-0,24t+(597,3+0.441t)X...
・・・・・・・・・・・・(11t: Temperature and enthalpy).

As a result of the above equation, the enthalpy change, -h, is given by the electronic cooling (heating) element 17 with constant capacity, and tl-t
Since l is obtained from the output of the calculator 24 which is the calculated value of the thermometers 22 and 23, by calculating these values with the calculator 28, the value of absolute humidity can be read with the indicator 29.

FIG. 2 is a perspective view showing the internal structure of the container of the detector shown in FIG.
Electrodes 33, 34 provided in contact with these heat conductive plates
．． 35, and P-type semiconductors 36, 37, connected to these.
N-type semiconductor 38.

The heat conductive plate 3 is electrically connected in series and led out to the outside through input terminals 39 and 40.
A thermometer 41 is disposed close to the container 1, and a thermometer 42 is disposed separately outside the container.

As explained above, according to the present invention, (1) Humidity is considered as a load on the electronic cooler (heater) and is determined by the temperature of the air passing through the cooler (heater). Compared to devices that detect changes in performance, there is less decline in humidity detection ability due to atmospheric pollutants (oil, smoke, etc.).

(2) Compared to the type that uses electricity to add heating cleaning to prevent deterioration of detection ability due to adhesion of contaminants, the operating voltage is lower (several V) and the temperature difference is only around the IC.
Humidity can be measured safely and continuously.

(3) Since there is no need to create pores in the element for moisture adsorption, there are advantages such as ease of manufacturing without the need to specify the dimensional accuracy of the pores.

[Brief explanation of the drawing]

The drawings show an embodiment of the humidity sensor of the present invention, and FIG. 1 is an overall configuration diagram, and FIG. 2 is a perspective view of other essential parts.

Claims (1)

[Scope of Claims] A small chamber separated from the outside air so that air can circulate therein, and a cooler or heater with a constant capacity for cooling or heating the atmosphere within the small chamber within a temperature range that does not cause condensation. A humidity detector comprising a thermometer placed inside the small room and a thermometer placed outside the small room.