JPS5856301A - Moisture sensitive element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention provides a moisture sensitive element, 1m! More specifically, the present invention relates to a humidity sensing element having an electrical resistance value that is extremely easy to use in a wide range of humidity. The so-called humidity sensors that measure and detect the humidity in the atmosphere have been developed in recent years by using the hair fij meter (% as). It has been done. This type of humidity sensor is attracting attention because it is easy to control humidity and is easy to handle. Among them, a method that is inexpensive and directly electrically detects humidity in a wide humidity range consists of 812, which physically adsorbs moisture in the atmosphere onto the surface of a humidity sensing element, thereby increasing the resistance value or Nine moisture-sensitive elements are known that utilize the change in capacitance.9
Sintered bodies of metal oxides and polymers are commonly used as moisture-sensitive elements. By the way, whether the moisture sensing element is made of a sintered metal oxide or a polymer, it has a resistance value that is relatively easy to use in a high humidity region, and a simple circuit can be used. This makes it possible to detect and control humidity relatively accurately. However, in the low humidity region (20 to 3011.F (below)), where the resistance value of the humidity sensing element is extremely high, exceeding IOMQ, a normal electrical detection circuit cannot accurately detect humidity. This had the disadvantage that the circuit was extremely expensive.

An object of the present invention is to improve the above-mentioned drawbacks and to provide a humidity sensing element having an electrical resistance value that is extremely easy to use in a ToL wide range of humidity. That is, the sintered body as a moisture-sensitive element consists of 30 to 78 mol of zinc oxide, 20 to 55 mol of chromium oxide, 42 to 15 mol of LiZnVO as essential components, and the average of the sintered body particles constituting the sintered body. This is a moisture sensitive element characterized by a particle size of 1.0 to 4.0 μmKTo.

The humidity sensing element according to the present invention has an electrical resistance value of about 50KQ, which is more than two orders of magnitude lower than that of a conventional humidity sensor, at a low temperature of 2-5 DEG C. and a temperature of 2 to 5 degrees H. Further 25°090 S
At high humidity of R, H, it shows a value of about 3 KQ, and it was confirmed that it shows a resistance value that is extremely easy to use over a wide range of humidity. The reason for this is that if the amount of LiZnVO4 is increased by 15 ml, the shape of the moisture-sensitive element will be distorted during sintering, making it unsuitable for practical use. On the other hand, LiZnV
When O4 is less than 2 molts, the resistance value at low humidity becomes high. 9 ZnO is more than 78 moles or %Cr20B is 2
When the amount is less than 0 mol, the sintered particle size becomes large and non-uniform, the change in moisture sensitivity characteristics is small, and the overall resistance value becomes high, making it easy to detect resistance in practical use. It disappears. When the amount of ZnO is less than 30 mol, or the amount of Cr is 30 g more than S5 mol, the resistance value in the low humidity region increases, and the resistance cannot be easily detected in practical use. t
Even with the same composition, the moisture sensitivity characteristics change depending on the sintering temperature.
The resistance value that is easy to use in a wide range of humidity is achieved when the average particle size of the sintered particles constituting the humidity sensitive element is 1.0 to 4.
．． It was confirmed that a value of 0 μm is preferable.

It should be noted that when the average particle diameter was reduced to less than 1.0 μm, the resistance value in the low humidity 1f region sharply increased, and when it exceeded 40 μm, the resistance value rapidly increased in the entire humidity region and a slight decrease was observed.

Example 1 will be described in detail below.

First, fine powders of zinc oxide, chromium oxide, vanadium oxide, and lithium carbonate were used as starting materials9.

The raw material powders of ZnO, Cr2O3, and LiZnVO4 were weighed so that the amounts were 45 mol, 45 mol%, and 100 mol L, respectively. After this, these J powders were mixed for 24 hours in a bot mill, and then dried at 120°C for 12 hours.Then, this mixed powder was mixed at 900°C for 2 hours.
Sintering was carried out for a period of time, and further pulverization was carried out 24 hours a day in a pot mill.9 After this, drying was carried out at 120°C for 12 hours to prepare a raw material powder.

Next, double portions of polyvinyl alcohol as a binder were slowly added to the nine-adjusted powder thus obtained, and granulation was performed using a Laikai machine, followed by pressure molding. Pressure molding is 500kg/cd
The molded body had a diameter of f3ws.

It was made into a disk shape with a thickness of about 4 m. The thus obtained molded body was sintered at a temperature of 1300'O for 2 hours, and both main surfaces of the obtained sintered body were polished with No. 2,000 white arundum, and a moisture-sensitive molded body with a diameter of 501 mm and a thickness of 3 mm was polished. I got the elementary body ill.

Next, a ruthenium oxide paste was applied to both surfaces of this moisture-sensitive element body by screen printing, and the humidity-sensitive element was baked at 700'O, and the electrode +21 Fi diameter was 5 ml. A perspective view of the nine moisture-sensitive elements thus obtained is shown in FIG.

Next, the feeling of being attended to and the humidity characteristics of the i-element were measured. As shown in FIG. 2, the moisture sensing element according to the present invention has a
It was found that it has a resistance value that is extremely easy to use in a wide range of humidity, such as 530 KQ at 10 cm and 3.2 KQ at 904 Relative Humidity at an ambient ambient temperature of 0. The average particle size of the particles formed with the moisture-sensitive element obtained at this time was examined using a scanning electron microscope and found to be approximately 2.0 μin. Other Examples and Comparative Examples were prepared in almost the same manner as in Example 1, with different composition ratios.

At this time, the composition, moisture sensitivity characteristics (1 at ambient temperature of 25°C)
The table shows the average particle size of the particles with a resistance value of 0 mm, Hl, and 90 mm R, H, and a humidity-sensitive element of tl[L.

As shown in the table above, the humidity sensing element according to the present invention has a resistance value that is extremely useful in a wide range of humidity, and it is complicated and expensive to perform humidity measurement and control using the humidity sensing element according to the present invention. It is not necessary to use a special circuit, and the effect can be said to be extremely significant.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a humidity sensing element according to the present invention, and FIG. 2 is a curve diagram showing humidity characteristics of the humidity sensing element according to the present invention. Agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 12

Claims (1)

[Claims] A pair of electrodes, and between the electrodes (the sintered body provided and constituting the moisture sensitive element contains 30 to 70 mol of zinc oxide as an essential component),
Chromium oxide 20-55 moles, LiZnVO42-15
The average particle diameter of the sintered body particles constituting the sintered body is 1.0 to 4. Moisture sensing element that waits for OJlm.