JPH03165292A - Humidity sensor - Google Patents

Abstract

PURPOSE:To rapidly detect the change of temperature and humidity by attaching a plate-like humidity sensing element to a thermistor substrate having a through hole so that it may cover the through hole thereof. CONSTITUTION:As to the thermistor 7 substrate formed as the electrode, an RuO2 electrode is applied on the surface of a porous substrate 5 obtained by baking the RuO2 electrode and put on the through hole of the thermistor 7 substrate, adhered and backed to be integrated. After leads 1-3 are attached to the obtained substrate, the 5% water solution of polyacrylic soda 10, for example, having 2,000-10,000 polymerization degree, which is used as organic high polymer electrolyte, is applied on the surface of a porous body 4. Thus, the humidity and the temperature are accurately detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a humidity sensor used for humidity control in air conditioning equipment, cooking equipment, and the like.

Conventional technology Conventionally, humidity sensors have been disclosed in, for example, published patents (1982).
As described in Publication No. 9056 of 2006), moisture-sensitive materials using sintered bodies of metal oxides such as iron oxide and tin oxide, or metal oxide films, and electrolyte salts such as lithium chloride are used as moisture-sensitive materials. There was something I used. Additionally, there are humidity sensors in which conductive particles or fibers such as carbon are dispersed in a hygroscopic resin or polymer film, or in which an organic polymer electrolyte is coated on a ceramic substrate and a comb-shaped electrode is provided. Ta.

These have generally been discrete components that have lead wires extending from the electrodes of the moisture-sensitive material and are mounted on circuits using these lead wires.

These humidity sensors measure the current flowing between the electrodes because when the moisture-sensitive material absorbs moisture from the atmosphere, the number of movable ions in the moisture-sensitive material increases and the electrical resistance changes. It is used as a humidity detection component in various air conditioning equipment.

Since the humidity characteristics of these humidity sensors change due to changes in ambient temperature, it is necessary to perform temperature correction on the humidity sensor. Therefore, it has been necessary to provide a temperature sensing element such as a thermistor element in the humidity control circuit of various air conditioners and the like to perform temperature correction.

FIG. 4 shows a conventional example.

FIG. 4 is a perspective view showing a conventional humidity sensor. Fourth
In the figure, 6 is an alumina substrate, 3 and 4 are comb-shaped electrodes provided on the surface of the alumina substrate, and 6 is a moisture-sensitive material made of an electrolyte such as a metal oxide or lithium chloride or an organic polymer electrolyte. It is formed in the form of a film on the alumina substrate 6 so as to cover the electrodes.

Problems to be Solved by the Invention In the conventional configuration, a thermistor as a discrete component is used in combination by connecting it to a humidity sensor. If the humidity sensor was far away, the temperature compensation of the humidity sensor could not be performed accurately by the thermistor. On the other hand, if the humidity sensor and thermistor are attached to each other in order to accurately compensate the temperature of the humidity sensor, there is a problem in that the humidity sensing area of the humidity sensor becomes smaller and the sensitivity decreases.

The present invention solves these problems and aims to provide a small, highly reliable, and highly sensitive humidity sensor.

Means for Solving the Problems In order to solve the above-mentioned problems, in the present invention, a plate-shaped moisture sensitive element is bonded to cover the through hole of a thermistor substrate having a through hole.

Function: With this configuration, the temperature of the humidity sensing element is transmitted to the thermistor,
Further, the surface of the humidity sensing element is not covered by the thermistor. Therefore, changes in temperature and humidity can be detected quickly.

EXAMPLE Hereinafter, a humidity sensor according to an example of the present invention will be described with reference to the drawings. 1 and 2 are perspective views of one embodiment of the present invention, and FIG. 2 is a perspective view of the back side of FIG. 1.

In Figures 1 and 2, 4 is a porous body, and in this example, a MgCr204-Tie2 mixture was heated at 1000°.
MgCr204-TiO2 fired with C and with a porosity of 36
A polycrystalline material of the system was used. Reference numeral 6.6 denotes an electrode, which was formed by screen printing Rub2 paste on both sides of the porous body 40 and then baking it at 800'C. still,
The electrode thus formed is porous.

Next, 7 is a thermistor, commercially available MnCO3, Nip
.

After blending 5in2 in a predetermined ratio and mixing in a ball mill, temporary firing was performed. After the preliminary firing, the powder is ground again in a ball mill, and then a plasticizer, binder, and solvent are added to the ground powder to create a slurry.

The prepared slurry is formed into a sheet on a polyethylene film, and punched into a desired size.

Thereafter, it was fired to obtain a thermistor substrate.

A silver electrode paste was screen printed on the obtained substrate, and then baked with aOOoC to obtain an electrode 8.9.

Next, the RuO□ electrode was applied to the surface of the porous substrate 6 on which the RuO□ electrode was baked onto the thermistor substrate on which the electrode was formed, and placed over the through hole of the thermistor substrate, and then bonded and baked to form an integrated structure.

After attaching leads 1, 2.3 to the obtained sample, sodium polyacrylate with a degree of polymerization of 2o○0 to 10,000 was used as an organic polymer electrolyte, and this was made into a 6% aqueous solution to form a porous body. It was applied to the surface of.

Thereafter, it was dried at 160° C. for 1 hour to obtain a product. 1
o is sodium polyacrylate that was applied and dried on the surface of the porous body.

The obtained humidity sensor exhibited the characteristics shown in FIG. The horizontal axis represents the relative humidity of the atmosphere in which the product is placed, and the vertical axis represents the electrical resistance of the porous body 4 holding the sodium polyacrylate.

As can be seen from this figure, the humidity sensor obtained in this example showed a change in electrical resistance of about 6 digits in the relative humidity range of 1 o - to 90 g.

Next, samples were prepared by changing the area of the through hole in the chimp thermistor substrate with respect to the area of the moisture sensing element. The response speed of the humidity sensor was measured for the obtained sample. The measurement method is to use a standard humidity generator to apply moisture from the chip thermistor substrate side of the humidity sensor, and to reach the specified value of 90% for relative humidity desorption and adsorption at relative humidity of 20%RH to 80%RH, respectively. The time was measured.

In addition, each of the samples was dropped from a height of 1 m onto hardwood 30 times with the chip thermistor facing downward, and the adhesion between the chip thermistor substrate and the moisture sensitive element was examined. The results are shown in Table-1.

(Leaving space below) Table 1 As can be seen from the table, if the opening area of the through hole of the chip thermistor is 30 inches or less relative to the area of the moisture sensing element, it is good for the drop test because it has sufficient adhesive strength. Although some of them have poor response speeds and cannot provide stable humidity control, they cannot be used practically.

Moreover, if it is 80% or more, the response speed is very good because the opening area is sufficiently open, but on the other hand, it is very weak in drop tests and cannot be used. In other words, only when the opening area of the through-hole of the chip thermistor is in the range of 304 to ao% of the area of the humidity sensing element, will the humidity response speed be good and the chip thermistor be able to withstand drop tests. This is something that can be done.

In this embodiment, the through hole of the chip thermistor is made into a square shape, but the same effect can be obtained even if the through hole is round, oval, or polygonal.

Effects of the Invention As described above, the present invention can penetrate a plate-shaped moisture-sensitive element. The M1 award of the 16th thermistor on the right was made into an integrated structure by combining the 16th thermistor from the right side, so the response speed for humidity detection is good, and it has sufficient strength even in drop tests, making it highly reliable as a humidity sensor. In addition, since the chip thermistor for temperature compensation and the humidity sensing element are integrated, unlike conventional combinations of discrete components, the mounting can be accurately detected without being subject to variations in humidity and temperature depending on the position. Moreover, since it is an integrated type, it can be made ultra-small compared to the combination of conventional discrete parts, and it is possible to provide a humidity sensor that requires no man-hours and is highly suitable for mass production.

[Brief explanation of the drawing]

Figures 1 and 2 are perspective views of embodiments of the present invention, Figure 3 is a diagram showing the relative humidity-resistance relationship of the humidity sensor obtained by the present invention, and Figure 4 is a perspective view of a conventional humidity sensor. It is a diagram. 1.2.3... Lead wire, 4... Porous ceramic, 6, 6... Electrode, 7...
・Thermistor, 8°9... Electrode. K1 disaster,
11 1st figure 1 fig.

Claims (2)

[Claims] (1) A humidity sensor characterized in that a through hole is provided in a thermistor substrate, and a plate-shaped humidity sensing element is bonded to cover the through hole in the thermistor substrate. (2) In the statement of claim 1, the opening area of the through hole of the thermistor substrate is relative to the area of the moisture sensing element.
A humidity sensor characterized in that the humidity is 30% to 80%.