JPH0434357A - Humidity sensor - Google Patents

Abstract

PURPOSE:To obtain a humidity sensor capable of measuring humidity with high accuracy by utilizing a hydrogen ion conductor. CONSTITUTION:Electrodes 21, 22 are provided to one surface of a hydrogen ion conductor 1 and, in a rate limiting means 4, a porous layer 42 is provided to the electrode 21 through an inorg. layer 41 so as not to directly cover the electrode 21 with the vitreous substance of the porous layer 42 and an airtight layer 43 is further provided to the side surface thereof. Voltage is applied across both electrodes 21, 22 from a power supply 5 and the value of the current flowing between both electrodes is measured by a current measuring means 6. A heater 8 is provided to the other surface of the hydrogen ion conductor 1 through an insulating layer 7. The conductivity of a hydrogen ion is enhances at the time of measurement by the heater 8 and the rate of steam H2O of the outside is limited by the rate limiting means 4. The current value I to applied voltage V increases by the concn. of H2O and there is constant relation between humidity at constant voltage Vc and the limit current value I1 at that time and humidity can be measured from the current value I1.

Description

[Detailed Description of the Invention]: Industrial Application Field] The present invention relates to a humidity sensor using a hydrogen ion conductor.

[Prior Art] In addition to humidity sensors that utilize changes in resistance or capacitance of metal oxides, polymers such as -7M, there are also humidity sensors as proposed by the applicant in Japanese Patent Laid-Open No. 63-26568, etc. Some use solid electrolytes such as stabilized zirconia that are permeable to oxygen ions.

[22 Inventions or Problems to be Solved] This limiting current type humidity sensor using a solid electrolyte measures oxygen concentration at the same time, so a separation means such as using multiple voltages is required, which inevitably leads to errors. There was an opening point that was likely to cause problems.

In view of the above points, an object of the present invention is to provide a humidity sensor that can determine the humidity side with high accuracy using a hydrogen ion conductor.

Means for Solving 1 Problem] This invention provides a hydrogen ion conductor with a pair of electrodes, provides a rate controlling means on one of the pair of electrodes, and when a voltage is applied between the two electrodes, the voltage between the electrodes increases. This is a humidity sensor that measures humidity from the value of flowing current.

[Embodiment] FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention.

In the figure, 1 is a hydrogen ion conductor, Na20-Ca
It is composed of PH responsive glass such as O-3iO□, Liz 0-Lax03 SiO2, and others. A pair of t-poles 21 and 22 are provided on one side of the hydrogen ion conductor 1, and a water vapor rate-limiting means 4 such as a porous layer made of inorganic powder and glass is provided on one of the electrodes 21. .

In this example, an inorganic layer 4 is provided on the pole 21 as the rate controlling means 4.
1, a porous layer 42 is provided so that the glassy material of the porous layer 42 does not directly cover the electrode 21, and an airtight layer 43 is provided on the side surface.

Then, a voltage is applied to the picture electrodes 21 and 22 by the power supply 5, and the current value flowing between the two electrodes is measured by the current measuring means 6. Further, a heater 8 is provided on the other side of the hydrogen ion conductor 1 via an insulating layer 7, and a current is supplied to this heater 8 from a power source 9 to heat it.

When measuring, a current is applied to the heater 8 from a power source 9 to heat it and increase the conductivity of hydrogen ions.

Water vapor H20 in the outside air is rate-controlled by the rate-limiting means 4, reaches the electrode 21, moves through the hydrogen ion conductor 1, and becomes t[i2t
The following reaction occurs with the electrode 22 serving as an anode and the electrode 22 as a cathode.

Anode H2O-2H+÷1/202+2 eCathode 2H"+2e-H2 In other words, the hydrogen ions H" generated by the reaction are
If the bombing ability of the hydrogen ion conductor 1 is sufficiently increased, the external water vapor H20 will be rate-controlled by the rate-limiting means 4 and will exhibit a limiting current characteristic, as shown in FIG. , the t current value I with respect to the applied voltage V shows urine field current characteristics with a flat part, increases with the concentration of H2O, and changes depending on the humidity (amount of H2O) at a constant voltage Vc and the limiting current value 1. As shown in FIG. 7, there is a certain relationship between the ia flow value 11 and the humidity can be measured.

2 to 5 each show another embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same components.

In FIG. 2, a perforated cap 40 is used as the rate controlling means.

In FIG. 3, electrodes 2 are placed on both sides of the substrate of the hydrogen ion conductor 1.
1.22, and one of them @[! 21 is provided with a rate controlling means 4 similar to that shown in FIG.

In FIG. 4, electrodes 21.2 are placed on both sides of the hydrogen ion conductor 1.
2, a perforated cap 40 is provided on the electrode 21, and a heater 8 is provided on this perforated cap 40.

In FIG. 5, a porous substrate 3 is used as a rate-determining means, a first electrode 21 is provided on one side of the porous substrate 3, and a hydrogen ion conductor layer 10 such as a thin film is attached to the first electrode 21. Further, a second electric field fi: 22 is provided on this hydrogen ion conductor layer 10.

In any case of these figures 2 to 5, both poles are 21
−． Humidity is determined from the current value flowing through both 'X% opening when a voltage is applied between 22 and 22.

1. Effects of the invention As stated above, the present invention uses a hydrogen ion conductor to measure humidity, so it is small, has little influence from atmospheric gases such as oxygen, and can measure humidity with high accuracy. Can take measurements.

[Brief explanation of the drawing]

1, 2, 3, 4, and 5 are configuration explanatory diagrams showing one embodiment of the present invention, and FIGS. 6 and 7 are characteristic diagrams. 1.1o... Hydrogen ion conductor, 21.22... Electrode, 3... Porous substrate, 4... Rate controlling means, 5...
power supply, 6... current measuring means, 7... insulating layer, 8...
・Heater, 9...Power supply

Claims (1)

[Claims] 1. A hydrogen ion conductor that transmits hydrogen ions, a pair of electrodes provided on the hydrogen ion conductor, and a water vapor rate-limiting means provided on one of the pair of electrodes. A humidity sensor that measures humidity from the value of the current flowing between the electrodes when a voltage is applied between the two electrodes. 2. Providing a first electrode on the porous substrate as a rate-determining means,
This first electrode is provided with a hydrogen ion conductor layer, this hydrogen ion conductor layer is provided with a second electrode, and when a voltage is applied between both electrodes, a humidity sensor measures humidity from the value of the current flowing between the electrodes. . 3. The humidity sensor according to claim 1 or 2, wherein the hydrogen ion conductor or the rate controlling means is provided with a heater.