JPS61128147A - Apparatus for detecting moisture of soil - Google Patents

Abstract

PURPOSE:To obtain a soil moisture detection apparatus for stably detecting the moisture of soil with good accuracy over a long period of time, by forming at least at outer enclosure for enclosing a humidity-sensitive element from a partition wall impervious to water but pervious to steam. CONSTITUTION:An outer enclosure 2 receiving a humidity-sensitive element 1 such as a ZnCr2O4-LiZnVO4 ceramic humidity sensor is constituted by using a polyethylene plate and holes 3 are provided to said enclosure 2 while a polymer membrane 4 impervious to water but only pervious to steam is mounted to each hole 3 as a partition wall. The lead wire 5 of the outer enclosure 2 is connected to the element 1. By this method, the moisture of soil is stably detected without receiving the effect of various ions or conductive substances contained in the moisture of soil.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a soil moisture detection device capable of detecting moisture in soil.

[Technical background of the invention and its problems]

Detecting moisture in soil is extremely important, especially in plant cultivation. In order to maintain the moisture in the soil in an optimal state, it is essential to measure the moisture or humidity in the soil, and various methods related to this have been proposed in the past.

The amount of moisture in the collected clay is determined by calculating the difference between the measured weight and the measured weight. Although it is possible to accurately determine the amount of water in the soil using this method, it is difficult to continuously detect the amount of water, and the cultivation bed may be damaged in order to collect soil samples. There are some shortcomings such as:

Furthermore, a method is known in which a moisture detection electrode or a humidity detection element is directly buried in cultivation soil to electrically detect moisture in the soil. These methods have the advantage that the amount of water in the soil can be easily detected at all times, and that control such as appropriate water supply to the soil can be easily carried out based on the detection results. By the way, as is well known, soil, especially water in cultivation soil, contains extremely large amounts of various ions and conductive substances.

When water containing a large amount of various ions or conductive substances adheres to the humidity detection element, the measured electrical resistance value changes significantly. Moreover, when the concentration of various ions changes between the detection electrodes, the electrical resistance value also changes significantly.

In this way, there is a drawback that the accuracy of moisture detection is significantly impaired. This method had the disadvantage that it caused a drooping change and lowered the accuracy of moisture detection.

[Purpose of the invention]

An object of the present invention is to provide a soil moisture detection device that can stably and accurately detect moisture in soil over a long period of time.

[Summary of the invention]

The present invention comprises a humidity sensing element capable of electrically detecting humidity in the atmosphere and an envelope surrounding the element, and at least a part of the envelope does not allow water to pass through, but allows only water vapor to pass through. This is a soil moisture detection device consisting of a partition wall that has the property of In this type of soil moisture detection device, water containing ions or conductive substances does not come into direct contact with the humidity detection element even if the device is buried in the soil, so it can be used stably and accurately for a long period of time. Moisture in the soil can be detected.

Furthermore, a soil moisture detection device with a double envelope structure is suitable for VC especially when buried between highly fluid soils. This is because partition walls that allow only water vapor to pass through are usually made of a thin polymer membrane, and if stress is applied to this membrane due to soil movement, the polymer membrane may be damaged.

Furthermore, if it is necessary to detect the temperature in the soil together with the moisture, a device that also includes a humidity detection element in the envelope can be used.

Any partition wall may be used as long as it allows only water vapor to pass through.

For example, porous fluororesin membranes, polyethylene resin membranes,
Examples include polymer membranes such as polypropylene resin membranes and noricone resin membranes. The size of the hole is usually about 0.5 μm or less.

[Embodiments of the invention]

Next, embodiments of the present invention will be described. Figure 1 shows the device H of the present invention.
FIG.

ZnCr2 has excellent long-term stability as a moisture sensing element (1)
An O4-LiZnVO4 ceramic humidity sensor was used.

The envelope (2) was constructed using a polyethylene plate that does not allow easy passage of both water and water vapor. This envelope (2) has a diameter ICrrL as shown in Figures 1 and 2.
A υ1 molecular membrane (4) (for example, Ibo ψ 2.000 made by Asahi Kasei, etc.) that has the property of not allowing water to pass through but only water vapor is provided at the hole (3). I fell in love with him and decided to use him as a bulkhead. A rough polyethylene envelope (
2) is equipped with a lead wire (5) in advance,
The leads of the moisture sensing element (11) were connected inside the envelope (2) so that the detection signal could be taken out to the outside of the envelope.Water could also penetrate inside where the lead wires were passed. The soil moisture detection element obtained in this way was buried in cutting soil and water containing ions was sprinkled on it, but no abnormal resistance change occurred and the ions were removed. It was confirmed that the contained water did not adhere to the moisture sensing element.

In addition, even when water was sprinkled extensively at Yang Geum, the detection signal did not fluctuate, and it was confirmed that water did not penetrate into the inside of the envelope.

As the double-structured envelope, the outer envelope (2r) shown as a perspective view in FIG. 2 was used, and the apparatus shown in FIG. ) has a diameter Q
, 5 mtx holes (6) were provided. (7) is outside
It is a connection terminal. A device with this structure was buried in rough soil and sprinkled with a large amount of water, but no abnormalities occurred in the detection signal, confirming that no damage to the polymer membrane occurred.

〔Effect of the invention〕

As described above, the soil moisture detection device according to the present invention can stably detect moisture without being affected by various ions or 49L substances contained in soil moisture.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the device of the present invention. FIG. 2 is a perspective view showing the device of the present invention. Agent: Patent Attorney Noriyuki Chika (1 other person)

Claims (1)

[Claims] 1. A device comprising a humidity sensing element capable of electrically detecting humidity and an envelope surrounding the humidity sensing element, at least a part of which does not allow water to pass through; A soil moisture detection device comprising a partition wall that allows only water vapor to pass through. 2. The soil moisture detection device according to claim 1, wherein the envelope has a double structure, and the outer envelope is provided with a plurality of fine holes.