JPS6046457A - Humidity detector - Google Patents

Abstract

PURPOSE:To prevent dew condensation at a humidity sensing agent and electrodes by raising the temperature of a substrate when the humidity is larger than a specific value. CONSTITUTION:The humidity sensing agent 3 manufactured by polymerizing methacryl amide propyl trimethyl ammonium chloride as a cation conducting agent monomer and vinyl acetate is applied between gold-made comb-shaped electrodes 2 and 2 printed on the surface of an alumina substrate 1, and a heating body 4 for prevention against dew condensation which consists of an electric heater is embedded in the reverse surface of the alumina substrate 1. When the relative humidity rises above 90%, the heating body 1 is powered on to heat the substrate 1, and this heat conduction makes the humidity sensing agent 3 and electrodes 2 and 2 warm enough to prevent dew condensation, reducing the influence of the dew condensation.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a humidity detector that detects humidity in an air conditioned room as a control signal for an air conditioner.

(b) Conventional Humidity Sensors Some use metal oxides as moisture-sensing agents, while others use organic polymers. Even if a humidity sensor using a metal oxide has dew condensation, it can be restored to the original humidity characteristics of the humidity-sensitive resistor by, for example, 1000 or more heating cleaning operations.

However, in humidity sensors that use organic polymers, the moisture-sensitive agent is water-soluble, so when condensation occurs, the moisture-sensitive agent dissolves and separates from the substrate surface, changing the humidity characteristics (humidity-sensing resistance (shifting toward larger values) has a drawback. Moreover,
Even if the above-mentioned normal heating cleaning is attempted in a dew-condensed state, the polymer moisture sensitive agent is susceptible to high heat, so there is a risk that it will deteriorate and the humidity characteristics will change significantly.

(c) Purpose of the invention The present invention protects an organic polymer moisture sensitive agent from dew condensation,
In addition, the present invention provides a humidity detector in which errors in humidity characteristics are suppressed to a slight extent.

B) Structure of the Invention The present invention provides a heating element for preventing dew condensation, which generates heat to slightly increase the temperature of the substrate when the humidity exceeds a predetermined value, on a substrate coated with an organic polymer moisture sensitive agent between electrodes. A humidity detection element is constructed by providing the following.

With this configuration, when a high humidity (relative humidity of 90% or more) K is reached just before dew condensation occurs on the electrodes and moisture sensitive material, the substrate is heated with a heating element to raise the temperature of the electrodes to slightly higher than the ambient temperature in the air-conditioned room. The temperature is maintained to prevent dew condensation on the electrodes, and the detachment of the polymeric desensitizer is also suppressed, thereby minimizing errors in humidity characteristics.

(e) Examples Organic polymer materials generally used as moisture sensitive agents include anionic polymer materials whose mobile ions are sodium ions, potassium ions, and hydrogen ions, and anionic polymer materials whose mobile ions are chlorine ions, bromide ions, etc. 9. A cationic polymer material that is a halogen ion, a moisture-absorbing polymer such as polyvinyl alcohol, and a metal salt such as lithium chloride added.9.
There is.

Hereinafter, as an example of the present invention, a case where a cationic polymer material is used as a moisture sensitive agent will be described.

Figure 1 (A) is a front view of the humidity detector, and Figure 1 (B) is a rear view of the same detector. A moisture sensitive agent (3) prepared by polymerizing methacrylamide propyltrimethylammonium chloride, which is a cationic conductive agent monomer, and vinyl acetate at a molar ratio of 1=2 (mole ratio) is coated on the back surface of the alumina substrate (1). A heating element (4) for preventing dew condensation consisting of a general electric heater is buried.

(5) (5) is a detection lead wire derived from the electrodes (2) (2) and used to measure the resistance between the electrodes, (6) (6)
is a power supply lead wire that supplies a voltage of 5V to the heating element (4) of 2200 when the relative humidity in the air conditioned room becomes 90% or more, and stops supplying the voltage when it drops below 90%.

Thus, the humidity detector constructed as described above is finally used after being immersed in a silicone film, dried, and covered with a silicone thin film.

The humidity-resistance characteristics of the same atmosphere were measured using the humidity detector of the present invention completed in this way and a conventional humidity detector without a heating element (4), and the results are shown in Figs. The following characteristics were obtained.

That is, the humidity detector of the present invention and the conventional humidity detector were each left for 30 days on the water surface of a sealed container with water stored at the bottom as a measuring device, and an AC voltage of I KHz 4.5 V was connected to the detection lead wire (
5) In addition to (5), humidity-resistance characteristics were measured,
As shown in FIG. 2, in the humidity detector according to the present invention, when the relative humidity reaches 90% or more, the heating element (4) K is energized to heat the substrate (1), and the humidity sensitive agent (3) is ) and electrodes (2) + 2) to a degree that does not condense, (a
) initial characteristics, compared with (b) characteristics after 14 days,
(c) It was found that the characteristics after 30 days shifted slightly toward lower resistance values, but remained very close to the initial characteristics, proving that the influence of dew condensation was small.

In contrast, with conventional humidity detectors, as shown in Figure 3, K (a) initial characteristics, (b) characteristics after 14 days, and (c) characteristics after 30 days have higher resistance values. It was confirmed that there was a large deviation in the direction and a large error occurred due to the influence of dew condensation.

According to BJ] K, when the humidity exceeds a predetermined value, the temperature of the substrate is slightly raised by a heating element to prevent condensation on the moisture sensitive agent and electrodes, so that condensation does not occur. In addition, the moisture sensitive agent does not deteriorate due to a slight temperature rise, and errors in humidity characteristics can be suppressed to a small level.

In addition, the heating element only needs to be provided on the substrate, and the amount of current applied to the heating element is also small, so the cost can be reduced, which is advantageous in practical terms.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention; FIG. 1A is a front view of the humidity detector, FIG. 2B is a rear view of the humidity detector, and FIG. Humidity-Resistance Characteristic Diagram FIG. 3 is a relative humidity-resistance characteristic diagram obtained by a conventional humidity detector. (1)...Substrate, (2)...Electrode, (3)...
- Moisture sensitive agent, (4)...Heating element. Applicant Sanyo Electric Co., Ltd. and one other representative Patent attorney Shizuo Sano Figure 1 (a) (ri) Figure 2 - 袷xT三田岨%ノ

Claims (1)

[Claims] (1) A humidity detector comprising a substrate coated with an organic polymer moisture sensitive agent between electrodes, and a heating element for preventing dew condensation that generates heat to warm the substrate when the humidity exceeds a predetermined value.