JP2021110665A - Water content measuring device - Google Patents

Abstract

To provide a water content measuring device in which an electrode is used and measurement accuracy of water content of a portion to be measured is improved.SOLUTION: Disclosed is a water content measuring device 1 which includes: one or more electrodes 2, 4 extending in the longitudinal direction L and embedded in a matric M; electric signal applying means 12 for applying an electric signal to the electrode; measuring means R, 12 for measuring the electric response generated by the electric signal via the electrode; and water content determining means 12 for determining the water content in the matrix based on the measurement result of the measuring means. Sensitivity of a high sensitivity part A1 on the tip side facing the matrix among the electrodes is higher than that of the rear end part A2 from the rear end of the high sensitivity part to the rear end of the electrode.SELECTED DRAWING: Figure 6

Description

The present invention relates to a water content measuring device for measuring the water content in a matrix such as soil.

As a device for measuring the water content of soil in agriculture, gardening, kitchen gardens, etc., various techniques are known in which an electric signal is applied to an electrode inserted into the soil and the water content of the soil around the electrode is measured from the electrical response. ing. Here, the relationship between the electrical response and the amount of water is obtained in advance.
These techniques include a capacitance method, a dielectric constant method, and an electric resistance method.

In the capacitance method (capacitance type), the relative permittivity of water is several tens of times the relative permittivity of soil, and the relative permittivity is proportional to the capacitance, so there is a relationship between the amount of water and the capacitance. Take advantage of being. Then, the soil containing water is regarded as an equivalent circuit of a dielectric (capacitor), and the capacitance is measured to obtain the amount of water. Specifically, for example, a voltage is applied between two or three electrodes, the soil between the electrodes is regarded as a capacitor, an RC equivalent circuit in parallel or in series with a resistor in the device is formed, and impedance measurement or a capacitor is used. Measure the capacitance from the charging time of.
In addition, an alternating current is passed between the electrodes to form an oscillation circuit in which the capacitance of the electrodes becomes part of the detection circuit, and the oscillation frequency changes due to changes in the capacitance of the electrodes due to changes in the amount of water in the soil. There is also a technique for measuring capacitance by changing.

The permittivity method also utilizes the fact that the relative permittivity of water and soil is different, and there are FDR (Frequency Domain Reflectometry) method, ADR (Amplitude-Domain Reflectometry) method, and TDR (Time Domain Reflectometry) method.
In the FDR method, there is one electrode (probe) that serves as a sensor, and electromagnetic waves of a wide range of frequencies are passed from the oscillator through the electrodes, and the dielectric constant is measured by measuring the reflected waves at the upper and lower ends of the electrodes.
In the ADR method, usually 2 to 4 parallel electrodes are used, and an electromagnetic wave having a constant frequency is passed through the electrodes from an oscillator, and the impedance when the electromagnetic wave passes through the electrodes in the soil and reciprocates is measured.
The TDR method usually uses two or three parallel electrodes, electromagnetic waves of a constant frequency are passed through the electrodes from the oscillator, and the dielectric constant is measured by measuring the propagation time (velocity) of the electromagnetic waves reciprocating between the electrodes in the soil. do.

On the other hand, the electric resistance method utilizes the fact that the electric resistances of water and soil are different, and measures the resistance between two or four electrodes in the soil. Specifically, for example, the electric resistance of the soil between the electrodes is set as one side of the resistance bridge circuit, and the current flowing according to the electric resistance is measured to obtain the electric resistance.
Among these, the electric resistance method, the capacitance method and the ADR method are simple as devices, and the FDR method and the TDR method have high measurement accuracy.

Then, as a simple device of the capacitance method, a pulse voltage is applied between a plurality of electrodes inserted into the soil to form an RC equivalent circuit between a capacitor composed of the soil and a resistor in the device, and a resistance portion is formed. A technique for measuring the capacitance of the soil between the electrodes from the voltage of the above has been proposed (Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-059176

By the way, as a method of applying an electric signal to an electrode inserted into the soil and measuring the amount of water from the electric response, taking the capacitance method as an example, as shown in FIG. 12, a pair of electrodes 100 and 102 are matrixed. It is inserted into (soil) M, and the electrical response according to the capacitance between the pair of electrodes 100 and 102 is measured. Then, as the water content of the soil M, there is a desire to measure the value of the internal F, which has a large effect on the growth of the roots of the plant, rather than the surface S, which is immediately infiltrated with water.
However, in the actual measurement, the electrical response corresponding to the average value of the capacitance of the total length D2 from the front end to the rear end in the longitudinal direction of the electrodes 100 and 102 is measured, and the length D1 corresponding to the internal F is measured. It is difficult to accurately measure the electrical response (and thus the amount of water) according to the capacitance of the part.

The present invention has been made to solve the above-mentioned problems, and provides a water content measuring device having improved measurement accuracy of the water content of a portion to be measured in a device using an electrode. The purpose.

In order to solve the above problems, the water content measuring device of the present invention comprises one or more electrodes extending in the longitudinal direction and embedded in a matrix, an electric signal applying means for applying an electric signal to the electrodes, and the electric signal. A water content measuring device comprising a measuring means for measuring the generated electrical response via the electrode and a water content determining means for determining the water content in the matrix based on the measurement result of the measuring means. Of the electrodes, the sensitivity of the high-sensitivity portion on the tip side facing the matrix is higher than the sensitivity of the rear end portion from the rear end of the high-sensitivity portion to the rear end of the electrode.

According to this water content measuring device, in the longitudinal direction of the electrode, not the average value of the physical characteristics of the matrix such as soil in the range of the total length of the electrode, but the electrical electrical according to the average value of the physical properties of the matrix in a specific range. The response can be measured. That is, it is possible to avoid measuring the electrical response according to the average value of the physical properties of the matrix such as soil in the range of the total length of the electrode including the part other than the measurement target, and to improve the water content of the measurement target part. It can be reflected to improve the measurement accuracy.

In the water content measuring device of the present invention, the electric signal may be a microwave, a voltage, or a current, and the electric response may be a current or a voltage.
According to this water content measuring device, measurement can be easily performed according to various measuring methods currently being developed.

In the water content measuring device of the present invention, the electrode has a conductive main body portion and an insulating portion that covers the main body portion, and the thickness or material of the insulating portion at the high sensitivity portion and the rear end portion. However, the capacitance of the high-sensitivity portion may be lower than the capacitance of the rear end portion.
According to this water content measuring device, the sensitivity of the electrode can be easily adjusted by changing the thickness or material of the insulating portion while keeping the size and material of the main body of the electrode constant.

In the water content measuring device of the present invention, the high-sensitivity portion may extend to the leading edge of the electrode.
According to this water content measuring device, the accuracy of measuring the water content can be further improved by installing the cutting edge of the electrode at a portion to be measured.

In the water content measuring device of the present invention, a low-sensitivity portion having a lower sensitivity than the high-sensitivity portion may be interposed on the tip side of the high-sensitivity portion.
According to this water content measuring device, when a part that is not to be measured is arranged on the tip side of the part to be measured, it is not necessary to measure by installing a low-sensitivity part in the part that is not to be measured. It is possible to avoid measuring the part, and it is possible to improve the measurement accuracy by better reflecting the water content of the part to be measured.

In the water content measuring device of the present invention, there are two or more electrodes, and a holding member for keeping the distance between the electrodes constant is further provided, and the holding members are fixed to the rear ends of the two or more electrodes. It may have been done.
According to this water content measuring device, the influence of the holding member on the measurement can be reduced and the measurement accuracy can be improved as compared with the case where the holding member is fixed to the highly sensitive portion.

In the water content measuring device of the present invention, there are two or more electrodes, the electric signal is a DC voltage or current, and the electrical response is the capacitance of a capacitor formed by the matrix between the electrodes. The water content determining means may determine the water content in the matrix by the capacitance method based on the electrical response.
According to this water content measuring device, the present invention can be applied to a capacitance method in which the device is simple.

In the water content measuring device of the present invention, the electric signal applying means applies a predetermined pulse to the electrode, and the measuring means detects a voltage generated by a resistance at a predetermined place generated by the pulse. The water content determining means may determine the water content in the matrix based on the voltage detected by the measuring means.
According to this water content measuring device, the device becomes simpler.

According to the present invention, it is possible to obtain a water content measuring device using an electrode and having improved measurement accuracy of the water content of a portion to be measured.

It is a schematic diagram of the water content measuring apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structure of the water content measuring apparatus. It is a circuit diagram which shows the equivalent circuit of the water content measuring apparatus. It is a figure which shows the method of determining the water content. It is a figure which shows the relationship between the water content of the soil, the capacitance and the electric current of the capacitor composed of soil. It is sectional drawing which shows the detailed structure of an electrode. It is sectional drawing which shows the deformation example of an electrode. It is a circuit diagram which shows another measuring circuit when the capacitance method is used as the measuring method of the water content. It is a figure which shows the method of determining the water content by the circuit of FIG. It is a figure which shows the equivalent circuit including the soil and the insulation part. It is a figure which shows the formula which expresses the relationship between the measured capacitance and the capacitance of the soil and the insulating part in the equivalent circuit of FIG. It is a figure which shows the method of measuring the water content using the conventional electrode.

Hereinafter, the water content measuring device according to the embodiment of the present invention will be described with reference to FIGS. 1 to 6.
FIG. 1 is a schematic diagram of a water content measuring device 1 according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the water content measuring device 1, and FIG. 3 is a circuit diagram showing an equivalent circuit of the water content measuring device 1. FIG. 4 is a diagram showing a method for determining the water content, FIG. 5 is a diagram showing the relationship between the water content of the soil M and the capacitance and the current i of the capacitor C composed of the soil M, and FIG. 6 is a diagram showing the relationship between the electrode 2 and the current i. It is sectional drawing which shows the detailed structure of 4.

As shown in FIG. 1, the water content measuring device 1 is connected to one or more (two in this example) electrodes 2 and 4 extending in the longitudinal direction L to serve as sensors, and to the rear ends of the electrodes 2 and 4. Insulation (for example, made of resin) that keeps the distance between the resin housing 10, the resistors R and the CPU (Central Processing Unit) 12 arranged in the housing 10, the resistors R, and the electrodes 2 and 4 constant. It has a holding member 6.
The water content measuring device 1 is a handy type, and the water content can be measured by holding the housing 10 and piercing the electrodes 2 and 4 on the lower surface side into the soil M.
Each of the electrodes 2 and 4 has a conductive main body 2a and 4a made of, for example, a brass round bar, and insulating portions 2b and 4b that cover the main bodies 2a and 4a, respectively. For the insulating portions 2b and 4b, for example, a heat-shrinkable polyolefin tube can be used.

Here, in each of the insulating portions 2b and 4b, the thickness of the region (high-sensitivity portion) A1 from the most advanced end to the substantially central portion in the longitudinal direction L is different from the rear end of the region A1 to the rear ends of the electrodes 2 and 4 ( It is thinner than the thickness of the region (rear end portion) A2 up to the connection portion with the housing 10.
Therefore, in each of the electrodes 2 and 4, the sensitivity of the high-sensitivity portion A1 is higher than that of the rear end portion A2. The reason for this will be described later.

Next, the internal configuration of the water content measuring device 1 will be described with reference to FIG.
As described above, the present invention is characterized in that the sensitivity of the high-sensitivity portion A1 of each of the electrodes 2 and 4 is higher than the sensitivity of the rear end portion A2, and the configuration of the water content measuring device 1 itself is Although not particularly limited, as an example of the configuration, an apparatus similar to that of Patent Document 1 is used. The names and the like in the apparatus of FIG. 2 also partially follow the description of Patent Document 1.

As shown in FIG. 2, the CPU 12 has a terminal GPIO, a terminal ADC, a terminal Vcc, and a terminal GND as input / output terminals. Then, the CPU 12 is based on a pulse generation function for generating a pulse (electric signal) having a predetermined pulse width, a voltage detection function for detecting the voltage of the resistor R generated by the pulse, and a maximum value of the detected voltage. It has a water content determination function to determine the water content of the soil.
The terminal GPIO outputs the above pulse. An analog signal indicating the voltage of the resistor R is input to the terminal ADC, and A / D conversion is performed inside the CPU 12. A power supply voltage is input to the terminal Vcc, and the value of the power supply voltage (Vcc) is the pulse height. The terminal GND is grounded to ground.

Then, one electrode 2 is connected to the terminal GPIO via the capacitance Cx, the other electrode 4 is connected to one end of the resistor R via the capacitance Cy, and the other end of the resistor R is grounded.
A terminal ADC is connected to the one end of the resistor R so that the voltage of the resistor R is input to the terminal ADC.
Further, the tip sides of the electrodes 2 and 4 are embedded in the soil (matrix) M.

According to the circuit configuration of FIG. 2, a pulse P is output from the terminal GPIO to the electrode 2 via the capacitance Cx, and the soil M between the electrodes 2 and 4 acts as a dielectric (capacitor) C between the electrodes 2 and 4. A current i flows, and this current i flows through the capacitance Cy and the resistor R to reach GND.
Then, the voltage E (= i × R) when the current i flows through the resistor R is monitored by the terminal ADC.

As in Patent Document 1, the capacitances Cx and Cp are not essential for measuring the amount of water, but cut a direct current such as a direct current static electricity generated in the soil. By setting the capacitances of the capacitances Cx and Cp to a value relatively sufficiently large (for example, 10 times or more) as compared with the capacitance of the capacitor C of the soil M, the water content of the soil M changes. The change in capacitance at the time of this is clearly shown, and the decrease in measurement accuracy is suppressed.

The CPU 12 corresponds to the "electric signal applying means, measuring means, and water content determining means" in the claims. Further, the resistor R corresponds to the "measuring means" in the claims.

Next, the internal configuration of the water content measuring device 1 will be described with reference to FIG.
When the above-mentioned pulse voltage is applied between the two electrodes 2 and 4, the soil M acts as a capacitor C. At this time, as shown in FIG. 3, the equivalent circuit of the water content measuring device 1 is an RC series equivalent circuit.
Here, Equation 1:
Capacitance of capacitor C (represented by the same C) = Q / V ∝ε (where Q is electric charge, V is electric potential, ε is permittivity)
The capacitance is proportional to the permittivity ε of soil M. That is, as shown in FIG. 5, when the water content of the soil M changes, the permittivity ε changes and the capacitance also changes.

Further, when a DC voltage is applied to the capacitor, the current i flowing into the capacitor is given by Equation 2.
: I = C (dV / dt) (where t is time)
It is known that the current i = 0 when the DC voltage V does not change with time.

On the other hand, in the present embodiment, a pulse (voltage) P is supplied instead of a DC voltage having a constant magnitude. Therefore, as shown in FIG. 4, in a short period immediately after the pulse P is applied, the voltage V gradually rises and dV / dt also has a value exceeding 0, so that the current i> 0. Therefore, by setting the pulse width W to a short period in which the voltage V rises, the current i flows through the capacitor C in the soil.
Then, as shown in Equation 2, since the current i changes according to the capacitance in this short period, when the water content of the soil M changes, the current i also changes as shown in FIG.

Therefore, the CPU 12 can determine the water content of the soil based on the magnitude of the current i in the capacitor C of the soil M when the pulse P is generated.
Here, as a method for easily detecting the current i, the same current i also flows through the resistor R connected in series with the capacitor C. Therefore, by measuring the voltage E across the resistor R, i = E / R. The current i can be obtained.
Further, the current i is not constant and changes with time even while the pulse P is applied, and the voltage value E of the resistor R also changes with time. Therefore, in the present embodiment, as shown in FIG. 4, the water content of the soil is determined based on the maximum value E-Max of the values of the voltages E across the resistor R when the pulse P is generated.
In addition, the correspondence relationship between the known water content of the soil and the maximum value E-Max of the voltage E is measured in advance, a relational expression and a map of both are created, and the soil to be actually measured is referred to by reference to these. The water content of the above may be obtained by the CPU 12.

Next, electrodes 2 and 4, which are characteristic portions of the present invention, will be described with reference to FIG.
As described above, in the present embodiment, the sensitivity of the high-sensitivity portion A1 is higher than that of the rear end portion A2 in each of the electrodes 2 and 4.
As a result, as shown in FIG. 6, when it is desired to measure the value of the internal F, which has more roots of the plant and has a greater influence on the growth, than the surface S, which is immediately infiltrated with water, as the water content of the soil M. , The high-sensitivity portions A1 of each of the electrodes 2 and 4 having higher sensitivity can be arranged so as to overlap the length D1 corresponding to the internal F in the length direction L.
As a result, among the soil M, in the longitudinal direction L of the electrodes 2 and 4, the average value of the capacitance of the soil M in the range of the total length of the electrodes is not, but the average value of the capacitance of the soil M in the inner F which is a specific range. The voltage can be measured according to the value. That is, it is possible to avoid measuring the voltage corresponding to the average value of the capacitance in the range of the total length of the electrode including the portion other than the internal F to be measured, and to improve the water content of the internal F to be measured. It can be reflected to improve the measurement accuracy.

Here, the sensitivity can be obtained as shown in FIGS. 10 and 11.
That is, as shown in the equivalent circuit of FIG. 10, the electrostatic capacitance C _T, which is measured by the water content measurement apparatus 1, a capacitor consisting of soil M is the capacitance C _wat, the capacitance C _a dielectric It is considered to be the combined capacitance of a capacitor in which a capacitor composed of parts 2b and 4b is connected in series.
Then, as represented by the equation in Figure 11, the reciprocal of the electrostatic capacitance _{C T} is the reciprocal of the capacitance _{C wat,} is calculated from the sum of the reciprocal of the capacitance _{C a,,} sensitivity _{= C wat} / the _{C T.}

Then, from FIG. 11, the insulating portion 2b, as _the capacitance C _a and 4b is large, relative to a measurement capacitance C _T, the ratio of the capacitance C _wat soil M to be obtained becomes large , The above-mentioned sensitivity is also increased.
Here, the insulating portion 2b, the thinner the thickness of 4b, _the capacitance _{C a} is increased. Further, the insulating portion 2b, 4b are at the same thickness, the higher the dielectric constant is large, _the capacitance C _a is increased. Further, the insulating portion 2b, 4b is the same material and thickness, the larger the body portion 2a of the inner, outer surface area of 4a (= the radius), _the capacitance C _a is increased.
Therefore, the sensitivity can be increased by these methods.

Incidentally, the capacitance C _S in FIG. 10 is a capacitance generated when the moisture layer is present on the surface of the soil M, which due to the capacitor also be connected in series to the equation of FIG. 11. However, in FIG. 11, _CS is ignored.
Further, in the capacitance C _{wat of the soil M in FIG. 10, the capacitance C w1} due to the gravel characteristics of _{the soil M and the capacitance C w2} due to the characteristics of the ionic conductor of the soil M are arranged in parallel. It is considered to be connected.

As an electrode for detecting (sensing) the moisture content of the soil M, it may be considered that the rear end portion A2 should be eliminated and only the high-sensitivity portion A1 should be used as the electrode.
However, even if only the high-sensitivity portion A1 is used as an electrode and the rear end thereof is used as a conducting wire for transmitting a sensor signal to the measurement circuit, the conducting wire also becomes an electrode (sensor) for detecting the moisture content of the soil M.
Therefore, if it is a part that detects the water content of the soil M, it is regarded as an "electrode".

Further, in the present embodiment, the holding member 6 for maintaining the measurement accuracy by keeping the distance between the two (or more) electrodes 2 and 4 constant is fixed to the rear end portion A2.
As a result, the influence of the holding member 6 on the measurement can be reduced and the measurement accuracy can be improved as compared with the case where the holding member 6 is fixed to the highly sensitive portion A1.

FIG. 7 shows a modified example of the electrodes 20 and 40 in the water content measuring device according to the embodiment of the present invention.
A low-sensitivity portion A3 having a lower sensitivity than the high-sensitivity portion A1 is interposed at the cutting edge of the electrodes 20 and 40.
In this way, for example, in the cultivation of potted plants, when the gravel layer T for drainage is arranged below the inner F to be measured, the low-sensitivity portion A3 is provided on the gravel layer T to obtain the gravel layer T. Can be avoided, and the water content of the internal F to be measured can be better reflected to improve the measurement accuracy.

8 and 9 show another measurement circuit when the capacitance method is used as the method for measuring the amount of water. This example is described in Japanese Patent No. 5688731 and will be described according to the description.
As shown in FIG. 8, in this example as well, the equivalent circuit of the water content measuring device is an RC series equivalent circuit, but one end of the capacitor C of the soil M is grounded to GND and the other end of the capacitor C is connected to the resistor R. ing. Needless to say, a pair of electrodes 2 and 4 (not shown) are arranged at both ends of the capacitor C.
Then, a pulse P (pulse voltage or pulse current) is supplied from the other end of the resistor R as in the case of FIG. At this time, electric charge is stored in the capacitor C, and a potential difference is generated between both terminals of the capacitor C. As a result, as shown in FIG. 9, the voltage E of the connection terminal between the capacitor C and the resistor R rises with time, and finally becomes the voltage Vcc.

Assuming that the time until the voltage E becomes the predetermined voltage Elef is t, there is an equation 3: between the time t and the capacitor C (capacitance C).
t = C × R × ln {Vcc / (Vcc-Eref)}
And Equation 4:
C = t / [R × ln {Vcc / (Vcc-Eref)}]
Relationship is established.
Therefore, if (Vcc-Eref) and R are constant, the capacitance C of the capacitor C can be obtained from t.

It goes without saying that the present invention is not limited to the above-described embodiments, but extends to various modifications and equivalents included in the idea and scope of the present invention.
The principle of measuring the amount of water and the measuring circuit are not limited to the above. In the case of the capacitance method, any electrical response due to the capacitance of the capacitor formed by the soil M between the pair of electrodes may be detected by the electrodes. Further, as described above, the present invention can also be applied to the dielectric constant method (for example, FDR method, ADR) method, TDR method) and the electrical resistance method.
Furthermore, as long as an electrode extending in the longitudinal direction is used and the electrical response generated by applying an electric signal to the electrode is measured through the electrode, the measurement method not described in the present specification and the measurement method developed in the future are also applicable. The invention can be applied.

The configuration of the water content measuring device and the electrodes are not limited. For example, as long as the electrode is a material having good conductivity, metal, conductive carbon and the like are exemplified, but the electrode is not particularly limited. The shape of the electrode is also exemplified by, for example, a round bar, a prism, a flat plate, a tubular shape, or the like, but is not particularly limited.

The matrix in which the electrodes are embedded and the water content is to be measured may be any one that can contain water, and is not limited to soil, and examples thereof include sponges and water-absorbent resins, but the matrix is not particularly limited.
The fields to which the present invention can be applied include, but are not limited to, not only cultivation in agriculture, horticulture, and vegetable gardens, but also foods such as rice, water content of wood, sabo, and disaster prevention fields such as water stoppage.

1 Moisture content measuring device 2, 4, 20, 40 Electrodes 2a, 4a Main body 2b, 4b Insulation 6 Holding member 12 CPU (electric signal applying means, measuring means, water content determining means)
C Capacitor L Longitudinal M Matrix (soil)
R resistance (measuring means)
A1 High-sensitivity part A2 Rear end part A3 Low-sensitivity part

Claims (8)

With one or more electrodes extending longitudinally and embedded in the matrix,
An electric signal applying means for applying an electric signal to the electrode, and
A measuring means for measuring the electrical response generated by the electrical signal via the electrode, and a measuring means.
A water content determining means for determining the water content in the matrix based on the measurement result of the measuring means, and
It is a water content measuring device equipped with
A water content measuring device in which the sensitivity of the high-sensitivity portion of the electrode on the distal end side facing the matrix is higher than the sensitivity of the rear end portion from the rear end of the high-sensitivity portion to the rear end of the electrode. The electrical signal is a microwave, voltage, or current.
The water content measuring device according to claim 1, wherein the electrical response is an electric current or a voltage. The electrode has a conductive main body portion and an insulating portion that covers the main body portion.
The water content measuring device according to claim 1 or 2, wherein the thickness or material of the insulating portion between the high-sensitivity portion and the rear end portion is different, and the capacitance of the high-sensitivity portion is lower than the capacitance of the rear end portion. .. The water content measuring device according to any one of claims 1 to 3, wherein the high-sensitivity unit extends to the most advanced end of the electrode. The water content measuring device according to any one of claims 1 to 3, wherein a low-sensitivity portion having a lower sensitivity than the high-sensitivity portion is interposed on the tip side of the high-sensitivity portion. There are two or more electrodes.
Further having a holding member for keeping the distance between the electrodes constant,
The water content measuring device according to any one of claims 1 to 5, wherein the holding member is fixed to each of the rear ends of the two or more electrodes. There are two or more electrodes.
The electrical signal is a DC voltage or current
The electrical response is caused by the capacitance of the capacitor formed by the matrix between the electrodes.
The water content measuring device according to any one of claims 1 to 6, wherein the water content determining means determines the water content in the matrix by the capacitance method based on the electrical response. The electric signal applying means applies a predetermined pulse to the electrode, and the electric signal applying means applies a predetermined pulse to the electrode.
The measuring means detects a voltage generated with respect to a resistance at a predetermined location generated by the pulse.
The water content measuring device according to claim 7, wherein the water content determining means determines the water content in the matrix based on the voltage detected by the measuring means.

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