JP2013200193A - Moisture detection device, electrical conductivity detection device, sensor network system, program, method of detecting moisture, and method of detecting electrical conductivity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for accurately and inexpensively detecting moisture content and electrical conductivity of soil.SOLUTION: A sensor 6 includes; a pair of electrodes 68, 69 to be put into contact with culture soil having water-insoluble solute dispersed in water contained therein; a signal generator unit 70 which feeds an AC input electrical signal to the electrode 69; an absolute value detection circuit 73 and a phase detection circuit 74, which measure impedance between the electrode pair 68, 69 based on the input electrical signal and an output electrical signal from the electrode 68; and a CPU 60 which determines resistance and electrostatic capacitance between the electrode pair 68, 69 based on the impedance, and determines moisture content of the culture soil 8 and electrical conductivity of the culture soil 8 (between the electrode pair 68, 69) on the basis of the resistance and electrostatic capacitance.

Description

  The present invention mainly relates to a technique for accurately and inexpensively detecting soil moisture content and electrical conductivity. Furthermore, it is related with the technique which controls automatically the watering and topdressing with respect to culture media, such as a field.

  Conventionally, a sensor for detecting the amount of water and nutrient concentration in a field culture medium has been proposed.

JP-A-10-014402 JP 2004-077412 A

  However, with a sensor that detects electrical conductivity, measurement is difficult unless the amount of moisture in the soil is large. For example, the technique described in Patent Document 1 requires a mechanism for supplying moisture from the sensor when measuring. There was a problem of becoming.

  In addition, the electrical resistance method and the dielectric constant method have been proposed as methods for electrically measuring the moisture content in the soil. However, while the electrical resistance method is inexpensive, it is easily affected by salt concentration and temperature. There is a problem that accurate measurement cannot be performed. On the other hand, the dielectric constant method has a problem that the influence of the salinity concentration is suppressed to some extent, but since the high frequency is used, the detection device itself has a relatively expensive configuration.

  This invention is made | formed in view of the said subject, and mainly aims at providing the technique which detects the moisture content and electrical conductivity of soil correctly and cheaply.

  In order to solve the above problems, the invention of claim 1 is directed to a pair of electrodes that are in contact with a measurement target system in which water-insoluble solutes are dispersed in water and one of the electrodes is supplied with AC input electricity. Impedance measurement for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on a signal generating means for applying a signal, and the input electrical signal and an output electrical signal from the other of the electrodes And a resistance value between the pair of electrodes and a capacitance between the pair of electrodes based on at least one of an absolute value or a phase difference of impedance measured by the impedance measuring unit, and Water content specifying means for determining the water content in the measurement target system based on the resistance value and the capacitance is provided.

からなる連立方程式を解く。 Further, the invention of claim 2 is the moisture detecting device according to the invention of claim 1, wherein the moisture amount specifying means includes:

Solves simultaneous equations consisting of

  The invention according to claim 3 is the moisture detection apparatus according to claim 1 or 2, further comprising a resistor disposed between one of the electrodes and the signal generating means, and the impedance measurement. The means detects the absolute value by resistance partial pressure.

  According to a fourth aspect of the present invention, there is provided the moisture detecting device according to the third aspect of the invention, wherein the signal generating means includes a first input electric signal having a first frequency and a second frequency having a second frequency as the input electric signal. A two-input electric signal is applied, and the first frequency and the second frequency are both frequencies equal to or higher than the first reference frequency, and the first reference frequency is about 10 kHz.

  Further, the invention of claim 5 is the moisture detecting device according to the invention of claim 4, wherein the first frequency is less than a second reference frequency, and the second frequency is greater than or equal to the second reference frequency. The second reference frequency is several hundred kHz.

  The invention according to claim 6 is the moisture detecting device according to claim 1 or 2, further comprising a resistor disposed between one of the electrodes and the signal generating means, and the impedance measurement. The means detects the phase difference by resistance voltage division.

  The invention according to claim 7 is the moisture detecting apparatus according to the invention of claim 6, wherein the signal generating means includes a first input electrical signal having a first frequency and a second frequency having a second frequency as the input electrical signal. A two-input electric signal is applied, and the first frequency and the second frequency are both frequencies equal to or higher than the first reference frequency, and the first reference frequency is about 10 kHz.

  The invention according to claim 8 is the moisture detecting device according to claim 1 or 2, further comprising a resistor disposed between one of the electrodes and the signal generating means, and the impedance measurement. The means detects the absolute value and the phase difference by resistance voltage division.

  The invention according to claim 9 is the moisture detecting device according to the invention of claim 8, wherein the input electrical signal includes a first input electrical signal of a first frequency, and the first frequency is a first reference. The first reference frequency is about 10 kHz.

  The invention of claim 10 is the moisture detecting device according to the invention of claim 9, wherein the input electrical signal includes a second input electrical signal of a second frequency, and the first frequency is a second reference. Less than the frequency, the second frequency is greater than or equal to the second reference frequency, the second reference frequency is several hundred kHz, and the impedance measuring means is responsive to an output electrical signal for the first input electrical signal The absolute value of the impedance between the pair of electrodes is measured, and the phase difference between the pair of electrodes is measured according to the output electrical signal with respect to the second input electrical signal.

  An eleventh aspect of the present invention is the moisture detection apparatus according to any one of the first to tenth aspects, wherein the signal generating means uses a rectangular wave electric signal as the input electric signal.

  The invention of claim 12 is the moisture detecting device according to any one of claims 1 to 11, further comprising temperature detecting means for detecting an ambient temperature, wherein the moisture content specifying means is the temperature detecting means. The resistance value and / or the capacitance is corrected according to the detection result by the detection means.

  The invention according to claim 13 is a signal generation for applying an alternating input electric signal to one of the pair of electrodes in contact with a measurement target system in which a solute insoluble in water is dispersed in water. An impedance measuring means for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes, and the impedance measurement A resistance value between the pair of electrodes and a capacitance between the pair of electrodes are obtained based on at least one of an absolute value or a phase difference of impedance measured by the means; And an electrical conductivity specifying means for obtaining electrical conductivity between the pair of electrodes based on the capacitance.

からなる連立方程式を解く。 The invention of claim 14 is the electrical conductivity detecting device according to the invention of claim 13, wherein the electrical conductivity specifying means comprises:

Solves simultaneous equations consisting of

を解く。 The invention of claim 15 is the electrical conductivity detecting device according to the invention of claim 14, wherein the electrical conductivity specifying means comprises:

Solve.

  The invention of claim 16 is the electrical conductivity detecting device according to the invention of claim 15, wherein the electrical conductivity specifying means obtains the amount of water in the measurement target system and calculates the electrical conductivity. Correct with the amount of moisture.

  The invention of claim 17 is the electrical conductivity detection device according to any of claims 13 to 16, further comprising a resistor disposed between one of the electrodes and the signal generating means. The impedance measuring means detects the absolute value by resistance partial pressure.

  An eighteenth aspect of the present invention is the electrical conductivity detecting device according to the seventeenth aspect of the present invention, wherein the signal generating means includes a first input electric signal having a first frequency and a second frequency as the input electric signal. The first frequency and the second frequency are both equal to or higher than the first reference frequency, and the first reference frequency is about 10 kHz.

  The invention according to claim 19 is the electrical conductivity detecting device according to the invention according to claim 18, wherein the first frequency is less than a second reference frequency, and the second frequency is the second reference frequency. Thus, the second reference frequency is several hundred kHz.

  The twentieth aspect of the present invention is the electrical conductivity detection device according to any one of the thirteenth to sixteenth aspects of the present invention, further comprising a resistor disposed between one of the electrodes and the signal generating means. The impedance measuring means detects the phase difference by resistance voltage division.

  The invention according to claim 21 is the electrical conductivity detecting device according to claim 20, wherein the signal generating means uses the first input electrical signal of the first frequency and the second frequency as the input electrical signal. The first frequency and the second frequency are both equal to or higher than the first reference frequency, and the first reference frequency is about 10 kHz.

  The invention of claim 22 is the electrical conductivity detection device according to any of claims 13 to 16, further comprising a resistor disposed between one of the electrodes and the signal generating means. The impedance measuring means detects the absolute value and the phase difference by resistance voltage division.

  The invention of claim 23 is the electrical conductivity detecting device according to the invention of claim 22, wherein the input electrical signal includes a first input electrical signal of a first frequency, and the first frequency is The frequency is equal to or higher than one reference frequency, and the first reference frequency is about 10 kHz.

  The invention of claim 24 is the electrical conductivity detection device according to claim 23, wherein the input electrical signal includes a second input electrical signal having a second frequency, and the first frequency is Less than 2 reference frequencies, the second frequency is greater than or equal to the second reference frequency, the second reference frequency is several hundred kHz, and the impedance measuring means outputs an output electrical signal with respect to the first input electrical signal And measuring the absolute value of the impedance between the pair of electrodes and measuring the phase difference between the pair of electrodes according to the output electrical signal with respect to the second input electrical signal.

  The invention of claim 25 is the electrical conductivity detecting device according to any one of claims 13 to 24, wherein the signal generating means uses a rectangular wave electric signal as the input electric signal.

  The invention of claim 26 is the electrical conductivity detector according to any one of claims 13 to 25, further comprising temperature detecting means for detecting the ambient temperature, wherein the electrical conductivity specifying means comprises: The resistance value and / or the capacitance is corrected according to the detection result by the temperature detecting means.

  According to a twenty-seventh aspect of the present invention, there is provided a water supply device for supplying water to a measurement target system, a control device for controlling the supply of water by the water supply device, and a moisture detection capable of data communication with the control device via a network. The water detection device applies a pair of electrodes in contact with a measurement target system in which a solute insoluble in water is dispersed in water and an AC input electric signal to one of the electrodes. Signal generating means; and impedance measuring means for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electric signal and an output electric signal from the other of the electrodes. , Based on at least one of the absolute value or the phase difference of the impedance measured by the impedance measuring means, The controller further includes a moisture amount specifying unit that calculates a capacitance between the pair of electrodes and calculates a moisture amount in the measurement target system based on the resistance value and the capacitance. The said water supply apparatus is controlled according to the detection result by a detection apparatus.

  The invention of claim 28 provides a nutrient solution supply device for supplying a nutrient solution to a measurement target system, a control device for controlling supply of nutrient solution by the nutrient solution supply device, and data via the control device and a network. An electrical conductivity detection device capable of communication, the electrical conductivity detection device comprising a pair of electrodes in contact with a measurement target system in which a solute insoluble in water is dispersed in water, and the electrode At least one of an absolute value or a phase difference of impedance between the pair of electrodes based on signal generating means for applying an alternating input electric signal to one side, and the input electric signal and an output electric signal from the other of the electrodes Impedance measuring means for measuring one, based on at least one of the absolute value or phase difference of the impedance measured by the impedance measuring means, Electrical conductivity specifying means for obtaining a resistance value between a pair of electrodes and a capacitance between the pair of electrodes and obtaining an electrical conductivity between the pair of electrodes based on the resistance value and the capacitance The control device controls the nutrient solution supply device according to a detection result by the electrical conductivity detection device.

  The invention according to claim 29 is a computer-readable program, and the execution of the program by the computer makes the computer a measurement target system in which solutes insoluble in water are dispersed in water. A pair of electrodes in contact with each other, a signal generating means for applying an alternating input electric signal to one of the electrodes, and an impedance between the pair of electrodes based on the input electric signal and an output electric signal from the other of the electrodes An impedance measuring means for measuring at least one of an absolute value or a phase difference of the resistor, and a resistance between the pair of electrodes based on at least one of the absolute value or the phase difference of the impedance measured by the impedance measuring means A value and a capacitance between the pair of electrodes, and the resistance value and the capacitance Based on, to function as a moisture detecting device and a water content specifying means for determining the water content in the measurement target system.

  The invention according to claim 30 is a computer-readable program, and the execution of the program by the computer makes the computer a measurement target system in which solutes insoluble in water are dispersed in water. A pair of electrodes in contact with each other, a signal generating means for applying an alternating input electric signal to one of the electrodes, and an impedance between the pair of electrodes based on the input electric signal and an output electric signal from the other of the electrodes An impedance measuring means for measuring at least one of an absolute value or a phase difference of the resistor, and a resistance between the pair of electrodes based on at least one of the absolute value or the phase difference of the impedance measured by the impedance measuring means A value and a capacitance between the pair of electrodes, and the resistance value and the capacitance Based on, to function as an electrical conductivity detector having electric conductivity specifying means for determining the electrical conductivity between the pair of electrodes.

  Further, the invention of claim 31 is a step of bringing a pair of electrodes into contact with a measurement target system in which a solute insoluble in water is dispersed in water, and applying an alternating input electric signal to one of the electrodes. Measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes, and the measured impedance The resistance value between the pair of electrodes and the capacitance between the pair of electrodes are obtained based on at least one of the absolute value or the phase difference of the two, and based on the resistance value and the capacitance, And determining the amount of water in the measurement target system.

  Further, the invention of claim 32 is a step of bringing a pair of electrodes into contact with a measurement target system in which a solute insoluble in water is dispersed in water, and applying an alternating input electric signal to one of the electrodes. Measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes, and the measured impedance The resistance value between the pair of electrodes and the capacitance between the pair of electrodes are obtained based on at least one of the absolute value or the phase difference of the two, and based on the resistance value and the capacitance, And obtaining a conductivity between the pair of electrodes.

  The invention according to any one of claims 1 to 12 and claims 27, 29, and 31 is based on an input electrical signal and an output electrical signal from the other of the electrodes. Measure at least one, determine the resistance value between the pair of electrodes and the capacitance between the pair of electrodes based on at least one of the absolute value or phase difference of the measured impedance, By obtaining the water content in the measurement target system based on the capacitance, the water content can be detected at a low cost with little influence of the salinity concentration.

  In the inventions according to claims 13 to 26 and claims 28, 30, and 32, the absolute value of the impedance or the phase difference between the pair of electrodes is based on the input electrical signal and the output electrical signal from the other electrode. Measure at least one of them, determine the resistance value between the pair of electrodes and the capacitance between the pair of electrodes based on at least one of the absolute value or phase difference of the measured impedance, and the resistance value By calculating the electrical conductivity between the pair of electrodes based on the capacitance and the capacitance, the electrical conductivity can be detected while being kept in contact with the measurement target system even in a low moisture content environment.

It is a figure showing a sensor network system concerning the present invention. It is a figure which shows the sensor which concerns on this invention. It is a figure which shows the equivalent circuit of the culture soil which is a measuring object system. It is a flowchart which shows the moisture detection method and electrical conductivity detection method which concern on this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.

<1. Embodiment>
FIG. 1 is a diagram showing a sensor network system 1 according to the present invention. The sensor network system 1 includes a control device 2, a water supply device 3, a nutrient solution supply device 4, and a base station 5 that are connected to a network 9. In addition, the sensor network system 1 includes a plurality of sensors 6 that are installed so as to be partially embedded in the culture soil 8 that is a measurement target system.

  The culture soil 8 constitutes a field for growing plants such as vegetables. Generally, a soil component (solid component) that is a water-insoluble solute in the water component (liquid component) as a solvent. And an air component (gas component) are mixed. The network 9 is assumed to be a LAN (Local Area Network), but the Internet or a public network may be adopted.

  Although not shown in detail, the control device 2 is a device having a configuration and functions as a general computer, and is connected to the network 9 in a state where data communication is possible.

  The control device 2 receives information (sensing data: details will be described later) detected by the sensor 6 via the base station 5 and the network 9. That is, the control device 2 has a function of collecting sensing data.

  The control device 2 has a function of analyzing the collected sensing data and determining the state of the culture soil 8. In particular, the control device 2 determines whether or not the moisture content and the fertilizer (nutrient) concentration of the culture soil 8 are appropriate amounts for the plant being grown. Such a determination can be made based on the breeding recipe information that is created and stored in advance (for example, information in which an appropriate value is recorded according to the type of plant being grown and the growing situation).

  Furthermore, the control device 2 controls the water supply device 3 and the nutrient solution supply device 4 according to the state of the culture soil 8.

  The water supply device 3 can perform data communication with the control device 2 via the network 9. The water supply device 3 has a function of supplying moisture toward the culture soil 8 in response to a control signal from the control device 2. Therefore, if the control device 2 determines that the amount of moisture contained in the culture soil 8 is insufficient, if the control signal for starting water supply is transmitted to the water supply device 3, the culture soil is supplied from the water supply device 3. Moisture is supplied toward 8.

  The nutrient solution supply device 4 is capable of data communication with the control device 2 via the network 9. The nutrient solution supply device 4 has a function of supplying a nutrient solution in which plant nutrients (fertilizer) are dissolved toward the culture soil 8 in accordance with a control signal from the control device 2. Therefore, if the control device 2 determines that the nutrient contained in the culture soil 8 is insufficient, if the control signal for starting the supply of the nutrient solution is transmitted to the nutrient solution supply device 4, the nutrient solution The nutrient solution is supplied from the supply device 4 toward the culture soil 8.

  The base station 5 is a so-called base station for wireless communication, and provides a function of connecting a sensor 6 described later to the network 9.

  It is preferable that a plurality of sensors 6 are installed evenly on the culture soil 8 at a certain interval.

  FIG. 2 is a diagram showing a sensor 6 according to the present invention. The sensor 6 includes a CPU 60, a ROM 61, a RAM 62, an operation button 63, and an LED 64.

  The CPU 60 operates according to the program 7 stored in the ROM 61, thereby calculating various data and controlling each component included in the sensor 6. Thus, the sensor 6 has a function as a general computer that executes the program 7. Details of functions realized by the CPU 60 will be described later.

  The ROM 61 is a read-only storage device, and mainly stores the program 7 as described above.

  The memory 62 is, for example, a storage device such as a RAM or a nonvolatile NAND memory used as a temporary working area of the CPU 60, and a storage device capable of not only reading information by the CPU 60 but also writing information by the CPU 60. Is a general term. The memory 62 is used to store various data created in the sensor 6, and particularly stores temperature information 620, moisture information 621, and electrical conductivity information 622.

  The operation button 63 is hardware operated by the user, and is used to input information (instruction information) necessary for the sensor 6. Examples of the operation button 63 include a power button, a pairing button, and an initialization button.

  The LED 64 has a function of blinking (or lighting) in accordance with a control signal from the CPU 60 and notifying the user of the state of the sensor 6.

  The sensor 6 transmits a radio wave toward the base station 5, receives an radio wave transmitted from the base station 5, converts an analog signal from the antenna 65 into a digital signal, and outputs from the CPU 60. And an RF circuit 66 for converting a digital signal into an analog signal. By providing these configurations, the sensor 6 can perform wireless data communication with the base station 5.

  The sensor 6 further includes a thermometer 67, a pair of electrodes 68 and 69, a signal generator 70, a first resistor 71, a second resistor 72, an absolute value detection circuit 73, and a phase detection circuit 74. .

  The thermometer 67 has a function of detecting the temperature around the sensor 6. The ambient temperature as a detection result of the thermometer 67 is transmitted to the CPU 60 and stored in the memory 62 as temperature information 620.

  The pair of electrodes 68 and 69 are columnar structures protruding below the sensor 6, and are embedded in the culture soil 8 so as to be in contact with the culture soil 8 when the sensor 6 is installed. In addition, the shape of a pair of electrodes 68 and 69 is not limited to the example shown here, What is necessary is just to contact the culture soil 8 which is a measuring object system at a certain amount of intervals.

  The signal generation unit 70 includes a first signal generation circuit 75 and a second signal generation circuit 76.

The first signal generation circuit 75 is a circuit that generates a rectangular-wave AC electrical signal, and applies a first input electrical signal having a first frequency to the electrode 69 (one of the pair of electrodes 68 and 69). Hereinafter, the first frequency is referred to as “f ₁ ”. 0
The second signal generation circuit 76 is a circuit that generates a rectangular-wave AC electrical signal, and applies a second input electrical signal having a second frequency to the electrode 69 (one of the pair of electrodes 68 and 69). Hereinafter, the second frequency is referred to as “f ₂ ”.

  As described above, the sensor 6 in the present embodiment can be realized by using only a so-called microcomputer IO by using a rectangular wave electric signal, and the cost can be reduced as compared with the case of using a sine wave electric signal. Can be reduced.

  The first resistor 71 is disposed between the signal generation unit 70 (first signal generation circuit 75) and the electrode 69 (one of the pair of electrodes 68 and 69).

  The second resistor 72 is disposed between the signal generation unit 70 (second signal generation circuit 76) and the electrode 69.

The absolute value detection circuit 73 is a circuit that measures the absolute value of impedance between the electrodes 68 and 69 (culture soil 8) (hereinafter referred to as | Z |) by an electric resistance method. The absolute value detection circuit 73 obtains the absolute value | Z | by measuring the resistance partial pressure. The absolute value detection circuit 73 in the present embodiment is based on the first input electrical signal input from the first signal generation circuit 75 side and the output electrical signal corresponding to the first input electrical signal, and the absolute value | Z | Ask for. The absolute value detection circuit 73 transmits the measured absolute value | Z | to the CPU 60. In the present embodiment, as a method for obtaining the absolute value | Z |, the method of measuring the resistance partial pressure has been described as an example. However, the present invention is not limited to this, and the phase detection circuit 74 includes the electrodes 68 and 69. Similar to the absolute value detection circuit 73, the phase difference φ between the two pieces (cultured soil 8) is obtained by resistance partial pressure. The phase detection circuit 74 in the present embodiment obtains the phase difference φ based on the second input electrical signal input from the second signal generation circuit 76 side and the output electrical signal corresponding to the second input electrical signal.

  In this way, the phase detection circuit 74 detects the phase difference φ by resistance voltage division, so that the circuit configuration can be made almost the same as the configuration for detecting the absolute value | Z |. Sharing becomes easy.

  Further, the second input electric signal having a rectangular wave is also used for the phase detection circuit 74. When such a rectangular wave is used, the phase difference changes linearly with respect to the case where a sine wave is used. That is, since the change is linear, it is possible to return to a state equivalent to the case where a sine wave is used in the calculation described later.

  The phase detection circuit 74 transmits the measured phase difference φ to the CPU 60 in the same manner as the absolute value detection circuit 73. In the present embodiment, the technique for measuring the resistance partial pressure is described as an example of the technique for obtaining the phase difference φ. However, the present invention is not limited to this.

  Next, based on the absolute value | Z | transmitted from the absolute value detection circuit 73 and the phase difference φ transmitted from the phase detection circuit 74, the CPU 60 determines the moisture content of the culture soil 8 (hereinafter referred to as θ). )) And the electrical conductivity (salt concentration when the water content θ is 100%, hereinafter referred to as σ) will be described. The electrical conductivity σ is an index of the salt concentration of the soil, and in the agricultural field, it is a measure of the amount of fertilizer in the soil.

FIG. 3 is a diagram showing an equivalent circuit of the culture soil 8 which is a measurement target system. When the culture soil 8 is electrically measured, a capacitive component 80 is formed between the electrodes 68 and 69 and the culture soil 8. The culture soil 8 can be represented by a capacity component 81 and a resistance component 82. Hereinafter, the capacitance of the capacitance component 80 is referred to as “C _S ”, the capacitance of the capacitance component 81 is referred to as “C”, and the resistance value of the resistance component 82 is referred to as R.

The resistance value R varies depending on the salinity concentration (that is, electric conductivity σ) and the water content θ, and the capacitance C varies only with the water content θ if the salinity concentration is low. On the other hand, the capacitance C _S does not depend on the salinity concentration or the water content θ and is mainly determined by the material of the electrodes 68 and 69 of the sensor 6. That is, the relationship between these values can be expressed by Equation 1 and Equation 2 shown below.

To be precise, F ₂ (σ) in Equation 1 is a function of the water content θ and is F ₂ (σ (θ)). However, here, it is represented once by Equation 1 and will be described in detail later.

  Therefore, in order to obtain the moisture amount θ and the electrical conductivity σ, the resistance value R and the capacitance C may be obtained. The resistance value R and capacitance C are the phase difference between the absolute value | Z | of the impedance of the culture soil 8 (between the electrodes 68 and 69) and the voltage and current in the culture soil 8 (between the electrodes 68 and 69). By φ, it is expressed by the following equations 3 and 4.

Since the above Equation 3 and Equation 4 all have three variables C _S , C, and R, the resistance value R and the capacitance C can be obtained by solving the three simultaneous equations.

  There are three methods for solving the three simultaneous equations as follows. The first is a method in which input electric signals having three different frequencies are applied, an absolute value | Z | is measured for each case, and three simultaneous equations are calculated based on Equation 3. The second is a method in which input electric signals having three different frequencies are applied, the phase difference φ is measured in each case, and three simultaneous equations are calculated based on Equation 4. The third is to measure by applying an input electric signal of two different frequencies for either one of the absolute value | Z | or the phase difference φ, and apply an input electric signal of one frequency for the other. Thus, three simultaneous equations are set up and calculated based on Equations 3 and 4.

According to these methods, C _S , C, and R can be separated, and the resistance value R and the capacitance C can be obtained. However, these methods have a problem that the amount of calculation increases because three simultaneous equations are solved.

Therefore, first, a method for obtaining the resistance value R and the capacitance C by solving the two simultaneous equations while reducing the influence of the capacitance component 80 (C _S ) is proposed.

The capacitance C _S of the capacitance component 80 mainly depends on the material of the electrodes 68 and 69 to be configured, and is usually a relatively large value of about several uF. Therefore, when an input electric signal having a frequency of 10 [kHz] or more (preferably several tens [kHz] or more) is used, the capacitance C _S has a much larger influence than the resistance value R and the capacitance C. Get smaller. In the present embodiment, 10 [kHz] is referred to as a first reference frequency, and hereinafter referred to as “f _α ”. The optimum value of the first reference frequency f _α varies depending on the material of the electrodes 68 and 69. Therefore, the first reference frequency f _α may be determined according to the electrodes 68 and 69.

From the above, by using an input electric signal having a frequency equal to or higher than f _α , Equation 3 and Equation 4 can be approximated as follows.

  Since both of the above formulas 5 and 6 have two variables C and R, the resistance value R and the capacitance C can be obtained by solving the two simultaneous equations. That is, the amount of calculation can be suppressed as compared with the case where Equation 3 and Equation 4 are solved.

  There are three methods for obtaining the resistance value R and the capacitance C by solving two simultaneous equations using Equations 5 and 6, as follows.

First, two different frequencies f ₁ and f ₂ satisfying f _α ≦ f ₁ and f ₂ are determined. First, the first signal generation circuit 75 applies the first input electric signal having the first frequency f ₁ . Then, the absolute value detection circuit 73 measures the absolute value | Z |. Next, the first signal generation circuit 75 switches the frequency, applies the second input electric signal of the second frequency f ₂ , and the absolute value detection circuit 73 measures the absolute value | Z |. Then, based on the absolute value | Z | measured using two different frequencies f ₁ and f ₂ that are greater than or equal to f _α and Equation 5, two simultaneous equations are set up and calculated (hereinafter referred to as “first calculation”). This is referred to as “method”.

Second, two different frequencies f ₁ and f ₂ satisfying f _α ≦ f ₁ and f ₂ are determined. First, the second signal generation circuit 76 applies the first input electric signal having the first frequency f ₁ . Then, the phase detection circuit 74 measures the phase difference φ. Then, the second signal generation circuit 76 switches the frequency, applies the second input electric signal having the second frequency f ₂ , and the phase detection circuit 74 measures the phase difference φ. A method of calculating two simultaneous equations based on the phase difference φ measured using two different frequencies f ₁ and f ₂ that are greater than or equal to f _α and Equation 6 (hereinafter referred to as “second calculation method”). .)

Third, the frequency f ₁ satisfying f _α ≦ f ₁ is determined, the first signal generation circuit 75 applies the first input electric signal having the first frequency f ₁ , and the absolute value detection circuit 73 outputs the absolute value. | Z | is measured. On the other hand, the second signal generation circuit 76 applies the first input electric signal having the first frequency f ₁ , and the phase detection circuit 74 measures the phase difference φ. A method of calculating two simultaneous equations based on the absolute value | Z | and the phase difference φ measured using the same frequency f ₁ and the equations 5 and 6 (hereinafter referred to as “third calculation method”). .)

  In the sensor 6 in the present embodiment, the circuit for measuring the absolute value | Z | and the circuit for measuring the phase difference φ are both configured to measure the respective values using resistance voltage division. Therefore, the electrodes 68 and 69 can be shared, and the absolute value | Z | and the phase difference φ can be measured under the same conditions.

  The sensor 6 in the present embodiment is configured to employ any of the first calculation method, the second calculation method, and the third calculation method. However, for example, the first calculation method may be employed and the phase detection circuit 74 or the like may not be provided. Conversely, the second calculation method may be adopted so that the absolute value detection circuit 73 or the like is not provided. Alternatively, a circuit having no frequency switching function may be employed as the first signal generation circuit 75 and the second signal generation circuit 76 by employing a third calculation method capable of fixing the frequency.

  Next, a method is proposed in which the influence of the capacitance component 81 (C) is reduced in Equation 5 above, and the amount of computation is further suppressed than the method of solving the two simultaneous equations.

The capacitance C of the capacitance component 81 mainly depends on the shape of the electrodes 68 and 69 to be configured, and is usually a relatively small value of about several pF. Therefore, when an input electric signal having a frequency of several hundreds [kHz] or less is used, the capacitance C has a much smaller influence than the resistance value R. In the present embodiment, several hundreds [kHz] is referred to as a second reference frequency, and hereinafter referred to as “f _β ”. The value of the second reference frequency f _beta, the optimum value varies depending on the shape of the electrodes 68 and 69. Thus, it may be determined second reference frequency f _beta depending on the electrode 68 and 69.

That is, by using an input electrical signal having a frequency not less than f _α and less than f _β , Equation 5 can be approximated as follows.

Equation 7 is an equation using only R as a variable. Therefore, by using an input electric signal at a frequency below f _beta above f _alpha, can electrostatic capacitance C _S, small influence of C, obtaining the resistance value R.

  As methods for obtaining the resistance value R and the capacitance C using Equation 7, two methods are proposed as follows.

First, a frequency f ₁ satisfying f _α ≦ f ₁ <f _β and a frequency f ₂ satisfying f _β ≦ f ₂ are determined. First, the first signal generation circuit 75 sets the first frequency f ₁ at the first frequency f ₁ . A one-input electric signal is applied, the absolute value detection circuit 73 measures the absolute value | Z |, and the resistance value R is obtained by Equation 7. Next, the first signal generation circuit 75 switches the frequency, applies the second input electric signal of the second frequency f ₂ , and the absolute value detection circuit 73 measures the absolute value | Z |. Then, a method of calculating the capacitance C by substituting the already-obtained resistance value R and the absolute value | Z | measured using the second input electric signal into Equation 5 (hereinafter referred to as “fourth calculation”). This is referred to as a “method”.

Second, a frequency f ₁ satisfying f _α ≦ f ₁ <f _β and a frequency f ₂ satisfying f _β ≦ f ₂ are determined. First, the first signal generation circuit 75 sets the first frequency f ₁ at the first frequency f ₁ . A one-input electric signal is applied, the absolute value detection circuit 73 measures the absolute value | Z |, and the resistance value R is obtained by Equation 7. In parallel with this, the second signal generation circuit 76 applies the second input electric signal having the second frequency f ₂ , and the phase detection circuit 74 measures the phase difference φ. A method of calculating the capacitance C by substituting the obtained resistance value R and the phase difference φ measured using the second input electric signal into Equation 6 (hereinafter referred to as “fifth calculation method”) ).

  Since neither the fourth calculation method nor the fifth calculation method needs to solve simultaneous equations, the amount of calculation is further suppressed as compared with the first to third calculation methods.

In addition, although the sensor 6 in this Embodiment is equipped with the structure which can employ | adopt both the 4th calculation method and the 5th calculation method, below, it demonstrates as what employ | adopts a 5th calculation method. In other words, the function F ₈ (C, R) in Expression 6 and the function F ₉ (R) in Expression 7 are obtained and stored in the memory 62 of the sensor 6 through experiments or the like. In addition, since the fifth calculation method is employed, circuits having no function of changing the frequency can be employed as the first signal generation circuit 75 and the second signal generation circuit 76.

In the present embodiment, a frequency of about 10 [kHz] to several tens [kHz] is used as the frequency f ₁ . Further, the frequency f ₂ (the frequency of the second input electric signal for measuring the phase difference) is preferably a frequency such that R = 1 / (ω × C). A frequency of about [MHz] is used (where ω = 2πf ₂ ). That is, a suitable frequency f ₂ is determined by predicting the resistance value R and the capacitance value C to some extent.

  As described above, the CPU 60 determines the resistance value R between the pair of electrodes 68 and 69 and the pair of electrodes 68 and 69 based on the input electrical signal and the output electrical signal from the electrode 68 (the other of the electrodes 68 and 69). The capacitance C is obtained.

  The sensor 6 (CPU 60) in the present embodiment also has a function of correcting the temperature of the obtained resistance value R and capacitance C based on the detection result (temperature information 620) of the thermometer 67.

The memory 62 of the sensor 6 stores information obtained by experiments in advance on how the capacitance of the capacitance component 81 and the resistance value of the resistance component 82 change according to temperature. After obtaining the resistance value R and the capacitance C by the fifth calculation method, the CPU 60 corrects the resistance value R and the capacitance C while referring to the information based on the temperature information 620. Hereinafter, the value corrected by the temperature of the resistance value R is referred to as “R ₀ ”, and the value corrected by the temperature of the capacitance C is referred to as “C ₀ ”.

When the capacitance C ₀ of the capacitance component 81 and the resistance value R ₀ of the resistance component 82 are obtained, the electrical conductivity σ and the water content θ are obtained by solving the simultaneous equations of Equations 1 and 2.

  Of course, the simultaneous equations may be solved, but the sensor 6 in the present embodiment employs a method of further reducing the amount of calculation.

First, using the fact that F ₁ (θ) in Equation 1 and F ₃ (θ) in Equation 2 have the same characteristics, Equation 1 and Equation 2 are integrated to obtain Equation 8.

  In Expression 8, the influence of the moisture amount θ is cancelled.

When the electrical conductivity σ is low (for example, several hundred mS / m or less. This is the range for normal culture soil 8), F ₄ (σ) is constant (a constant A. A is an experiment or the like). Therefore, Equation 2 can be approximated to Equation 9 and Equation 8 can be approximated to Equation 10.

Therefore, if the function F ₃ (θ) and the constant A are obtained in advance by experiment, the moisture amount θ (moisture information 621) can be obtained by substituting C ₀ obtained by the fifth calculation method and temperature correction into Equation 9. . Further, if the function F ₂ (σ) and the constant A are obtained in advance by experiment, the electric conductivity σ is obtained by substituting R ₀ and C ₀ obtained by the fifth calculation method and temperature correction into the expression 10. Can do.

Strictly speaking, in the function F ₂ (σ), the electrical conductivity σ is affected by the moisture amount θ. Therefore, considering this, Equation 1 becomes Equation 11.

  That is, when the influence of the moisture amount θ is taken into consideration, Expression 10 becomes Expression 12.

The electrical conductivity obtained by substituting R ₀ and C ₀ obtained by the fifth calculation method and temperature correction into Equation 12 is σ (θ).

  The CPU 60 in the present embodiment corrects σ (θ) by the water content θ obtained from Equation 9, and obtains electrical conductivity σ (electrical conductivity information 622). Thereby, since it can correct | amend in consideration of the influence of moisture content (theta), the precision of electrical conductivity (sigma) improves. The aforementioned sensing data (sensing data of the sensor 6) is data including moisture information 621 and electrical conductivity information 622.

  The CPU 60 further controls the RF circuit 66 so that the created moisture information 621 and electrical conductivity information 622 are transmitted to the control device 2 at an appropriate timing.

  The above is description of the structure and function of the sensor network system 1 in this Embodiment.

  Next, a method for obtaining the water content θ and the electrical conductivity σ using the sensor 6 will be described.

  FIG. 4 is a flowchart showing a moisture detection method and an electrical conductivity detection method according to the present invention. By the time each process shown in FIG. 4 is started, it is assumed that the sensor 6 is properly installed on the culture soil 8, the power is turned on, and a predetermined initialization process is completed.

  When the process shown in FIG. 4 is started, the sensor 6 (CPU 60) enters a standby state while monitoring whether or not the measurement timing is reached (step S1). In the sensor network system 1, it is assumed that the measurement timing is detected based on schedule information transmitted from the control device 2 in advance in the initialization process and a timer (not shown) included in the sensor 6. However, the schedule information may not be transmitted from the control device 2 but may be stored in the memory 62 as a part of the program 7. Further, the control device 2 may notify the sensor 6 of the measurement timing by a transmission request or the like.

  When the measurement timing is detected, the sensor 6 determines Yes in step S1, and measures the absolute value | Z | of the impedance of the culture soil 8 (step S2).

In step S <b> 2, first, the CPU 60 notifies the signal generator 70 that the measurement of the absolute value | Z | is started. In response to this, the signal generation unit 70 controls the first signal generation circuit 75 to generate an input electrical signal. As a result, the first signal generation circuit 75 generates a first input electric signal having the first frequency f ₁ (f _α ≦ f ₁ <f _β ) and applies it to the electrode 69. Then, the absolute value detection circuit 73 measures the absolute value | Z | based on the first input electric signal and the output electric signal from the electrode 68 and transmits the absolute value | Z |

  When the absolute value | Z | is measured, the sensor 6 measures the phase difference φ due to the culture soil 8 (step S3).

In step S <b> 3, first, the CPU 60 notifies the signal generator 70 that the measurement of the phase difference φ is started. In response to this, the signal generator 70 controls the second signal generator circuit 76 so as to generate an input electrical signal. As a result, the second signal generation circuit 76 generates a second input electrical signal having the second frequency f ₂ (f _β ≦ f ₂ ) and applies it to the electrode 69. Then, the phase detection circuit 74 measures the phase difference φ based on the second input electric signal and the output electric signal from the electrode 68 and transmits the phase difference φ to the CPU 60.

  When the phase difference φ is measured, the CPU 60 refers to the value of the thermometer 67 to measure the temperature in the culture soil 8 (step S4).

  Next, the CPU 60 obtains the resistance value R by substituting the measured absolute value | Z | into Equation 7 (step S5).

  When the resistance value R is obtained, the CPU 60 obtains the capacitance C by substituting the obtained resistance value R and the measured phase difference φ into Equation 6 (step S6).

When the resistance value R and the capacitance C are obtained, the CPU 60 performs temperature correction based on the temperature information 620 to obtain the resistance value R ₀ and the capacitance C ₀ (step S7).

Next, the CPU 60 obtains the moisture amount θ by substituting the capacitance C ₀ obtained in Step S7 into Equation 9, and creates moisture information 621 (Step S8). In this way, the sensor 6 detects the water content θ of the culture soil 8. That is, the sensor 6 has a function as a moisture detection device.

Further, the CPU 60 obtains the electrical conductivity σ (θ) by substituting the resistance value R ₀ and the capacitance C ₀ obtained in Step S7 into Equation 12 (Step S9).

  Further, the CPU 60 corrects the electrical conductivity σ (θ) obtained in step S9 based on the water content θ obtained in step S8, and creates electrical conductivity information 622 (step S10). In this way, the electrical conductivity σ of the culture soil 8 is detected by the sensor 6. That is, the sensor 6 has a function as an electric conductivity detection device.

  When the moisture information 621 and the electrical conductivity information 622 are created, the sensor 6 transmits these pieces of information to the control device 2 (step S11).

  When the moisture information 621 and the electrical conductivity information 622 are transmitted to the control device 2, the sensor 6 is in a standby state again until the measurement timing comes.

  As described above, the sensor 6 according to the present embodiment includes the pair of electrodes 68 and 69 that are in contact with the culture soil 8 in which a solute that is insoluble in water is dispersed in the water, and an AC input electric current to the electrode 69. A signal generator 70 for applying a signal, an absolute value detection circuit 73 and a phase detection circuit 74 for measuring the impedance between the pair of electrodes 68 and 69 based on an input electrical signal and an output electrical signal from the electrode 68; A resistance value between the pair of electrodes 68 and 69 and a capacitance between the pair of electrodes 68 and 69 are obtained based on the impedance, and a moisture content in the culture soil 8 is obtained based on the resistance value and the capacitance. In addition, a CPU 60 for obtaining the electrical conductivity of the culture soil 8 (between the pair of electrodes 68 and 69) is provided. As a result, a moisture detection device that is less affected by the salt concentration can be realized at low cost. In addition, it is possible to realize an electrical conductivity detection device that measures electrical conductivity even in an environment with a small amount of water (for example, a state where it is still installed in the culture soil 8).

The signal generating unit 70 also applies a first signal generating circuit 75 that applies a first input electric signal having a first frequency f _{1 as} an input electric signal, and a second input electric signal that applies a second frequency f ₂ . The first frequency f ₁ and the second frequency f ₂ are both equal to or higher than the first reference frequency f _α , and the first reference frequency f _α is about 10 [kHz]. As a result, the influence of the capacitance C _S between the electrodes 68 and 69 and the culture soil 8 can be reduced, and the first to third calculation methods can be adopted, so that the calculation is simplified.

The first frequency f ₁ is less than the second reference frequency f _β , the second frequency f ₂ is greater than or equal to the second reference frequency f _β , and the second reference frequency f _β is several hundreds [kHz]. Thus, the fourth calculation method and the fifth calculation method can be adopted, and it is not necessary to solve the simultaneous equations, thereby simplifying the calculation.

  In addition, the phase detection circuit 74 that detects the phase difference φ between the pair of electrodes 68 and 69 is configured to measure the phase difference φ by using a resistance voltage division, thereby detecting the absolute value | Z |. These circuits and the electrodes 68 and 69 can be shared.

  Moreover, the CPU 60 can correct the influence of the moisture content by obtaining the moisture content θ in the culture soil 8 and correcting the electrical conductivity σ once obtained by the moisture content θ, thereby improving the accuracy.

  Further, the signal generation unit 70 can reduce the cost by using a rectangular wave electric signal as an input electric signal as compared with the case of using a sine wave electric signal.

  The CPU 60 includes a thermometer 67 that detects the ambient temperature, and the CPU 60 can eliminate the influence of temperature by correcting the resistance value and / or capacitance according to the detection result of the thermometer 67. Will improve.

<2. Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made.

  For example, each process shown in FIG. 4 is merely an example, and the present invention is not limited to this. Therefore, if the same effect is acquired, the content and order of each process shown in FIG. 4 may be changed suitably. For example, after the absolute value | Z | is obtained in step S2, step S5 may be executed immediately to obtain the resistance value R. Or the temperature measurement by step S4 may be performed immediately before the temperature correction by step S7.

  Moreover, in the said embodiment, although the plant was demonstrated as an example to be grown with the culture soil 8, it is not limited to a plant. For example, it may be a bacterium that grows in a special environment. Moreover, it is not always necessary for the purpose of training. That is, the present invention can be widely applied for the purpose of detecting the state of the measurement target system.

  Moreover, although the culture soil 8 containing a soil component was demonstrated to the example as a measuring object system, the system which hardly contains an individual component and a gas component like hydroponics may become a measuring object system. In that case, the sensor 6 is preferably configured to float on the aqueous solution.

  The sensor network system 1 may have a function of adjusting the temperature. For example, the sensor network system 1 may include a heating device, and the control device 2 may control the heating device according to the value of the thermometer of the sensor 6.

  The sensor network system 1 employs a detection device having a function of measuring the absolute value | Z | and the phase difference φ, and sensing data (absolute value | Z | Based on the phase difference φ), the water content θ and the electrical conductivity σ may be specified by calculation. That is, the detection device does not have to calculate the water content θ and the electrical conductivity σ.

DESCRIPTION OF SYMBOLS 1 Sensor network system 2 Control apparatus 3 Water supply apparatus 4 Nutrient solution supply apparatus 5 Base station 6 Sensor 60 CPU
61 ROM
62 Memory 620 Temperature information 621 Moisture information 622 Electrical conductivity information 63 Operation buttons 64 LED
65 Antenna 66 RF Circuit 67 Thermometer 68, 69 Electrode 7 Program 70 Signal Generator 71 First Resistor 72 Second Resistor 73 Absolute Value Detection Circuit 74 Phase Detection Circuit 75 First Signal Generation Circuit 76 Second Signal Generation Circuit 8 Culture soil 9 network

Claims (32)

A pair of electrodes in contact with a measurement target system in which a solute that is insoluble in water is dispersed in water;
Signal generating means for applying an alternating input electric signal to one of the electrodes;
Impedance measuring means for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes;
Based on at least one of the absolute value or phase difference of the impedance measured by the impedance measuring means, the resistance value between the pair of electrodes and the capacitance between the pair of electrodes are obtained, and the resistance value and A moisture content specifying means for obtaining a moisture content in the measurement target system based on the capacitance;
A moisture detection device comprising: The moisture detection apparatus according to claim 1,
The moisture content specifying means includes:

Moisture detection device that solves simultaneous equations consisting of The moisture detection apparatus according to claim 1 or 2,
A resistor disposed between one of the electrodes and the signal generating means;
The said impedance measurement means is a moisture detection apparatus which detects the said absolute value by resistance partial pressure. The moisture detection apparatus according to claim 3,
The signal generating means includes
As the input electrical signal, a first input electrical signal having a first frequency and a second input electrical signal having a second frequency are applied,
The first frequency and the second frequency are both frequencies equal to or higher than a first reference frequency,
The moisture detection apparatus, wherein the first reference frequency is about 10 kHz. It is a moisture detection apparatus of Claim 4, Comprising:
The first frequency is less than a second reference frequency;
The second frequency is greater than or equal to the second reference frequency;
The moisture detection apparatus, wherein the second reference frequency is several hundred kHz. The moisture detection apparatus according to claim 1 or 2,
A resistor disposed between one of the electrodes and the signal generating means;
The impedance measuring means is a moisture detecting device that detects the phase difference by resistance partial pressure. The moisture detection apparatus according to claim 6,
The signal generating means includes
As the input electrical signal, a first input electrical signal having a first frequency and a second input electrical signal having a second frequency are applied,
The first frequency and the second frequency are both frequencies equal to or higher than a first reference frequency,
The moisture detection apparatus, wherein the first reference frequency is about 10 kHz. The moisture detection apparatus according to claim 1 or 2,
A resistor disposed between one of the electrodes and the signal generating means;
The said impedance measurement means is a moisture detection apparatus which detects the said absolute value and the said phase difference by resistance partial pressure. The moisture detection apparatus according to claim 8,
The input electrical signal includes a first input electrical signal of a first frequency;
The first frequency is a frequency equal to or higher than a first reference frequency;
The moisture detection apparatus, wherein the first reference frequency is about 10 kHz. The moisture detection device according to claim 9,
The input electrical signal includes a second input electrical signal of a second frequency;
The first frequency is less than a second reference frequency;
The second frequency is greater than or equal to the second reference frequency;
The second reference frequency is several hundred kHz;
The impedance measuring means measures the absolute value of the impedance between the pair of electrodes according to the output electrical signal with respect to the first input electrical signal, and the pair of pairs according to the output electrical signal with respect to the second input electrical signal. A moisture detector that measures the phase difference between electrodes. The moisture detection device according to any one of claims 1 to 10,
The said signal generation means is a moisture detection apparatus which uses the electric signal of a rectangular wave as the said input electric signal. The moisture detection device according to any one of claims 1 to 11,
A temperature detecting means for detecting the ambient temperature;
The moisture amount specifying unit corrects the resistance value and / or the capacitance according to a detection result by the temperature detection unit. A pair of electrodes in contact with a measurement target system in which a solute that is insoluble in water is dispersed in water;
Signal generating means for applying an alternating input electric signal to one of the electrodes;
Impedance measuring means for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes;
Based on at least one of the absolute value or phase difference of the impedance measured by the impedance measuring means, the resistance value between the pair of electrodes and the capacitance between the pair of electrodes are obtained, and the resistance value and Based on the capacitance, an electrical conductivity specifying means for obtaining electrical conductivity between the pair of electrodes,
An electrical conductivity detection device comprising: The electrical conductivity detection device according to claim 13,
The electrical conductivity specifying means includes

An electrical conductivity detector that solves simultaneous equations. The electrical conductivity detection device according to claim 14,
The electrical conductivity specifying means includes

Electric conductivity detector that solves the problem. The electrical conductivity detection device according to claim 15,
The electrical conductivity specifying means includes
An electrical conductivity detection device that obtains a moisture content in the measurement target system and corrects the electrical conductivity with the moisture content. The electrical conductivity detection device according to any one of claims 13 to 16,
A resistor disposed between one of the electrodes and the signal generating means;
The impedance measurement means is an electrical conductivity detection device that detects the absolute value by resistance partial pressure. The electrical conductivity detection device according to claim 17,
The signal generating means includes
As the input electrical signal, a first input electrical signal having a first frequency and a second input electrical signal having a second frequency are applied,
The first frequency and the second frequency are both frequencies equal to or higher than a first reference frequency,
The electrical conductivity detecting device, wherein the first reference frequency is about 10 kHz. The electrical conductivity detection device according to claim 18,
The first frequency is less than a second reference frequency;
The second frequency is greater than or equal to the second reference frequency;
The electrical conductivity detecting device, wherein the second reference frequency is several hundred kHz. The electrical conductivity detection device according to any one of claims 13 to 16,
A resistor disposed between one of the electrodes and the signal generating means;
The impedance measurement means is an electrical conductivity detection device that detects the phase difference by resistance partial pressure. The electrical conductivity detection device according to claim 20,
The signal generating means includes
As the input electrical signal, a first input electrical signal having a first frequency and a second input electrical signal having a second frequency are applied,
The first frequency and the second frequency are both frequencies equal to or higher than a first reference frequency,
The electrical conductivity detecting device, wherein the first reference frequency is about 10 kHz. The electrical conductivity detection device according to any one of claims 13 to 16,
A resistor disposed between one of the electrodes and the signal generating means;
The impedance measurement means is an electrical conductivity detection device that detects the absolute value and the phase difference by resistance partial pressure. The electrical conductivity detection device according to claim 22,
The input electrical signal includes a first input electrical signal of a first frequency;
The first frequency is a frequency equal to or higher than a first reference frequency;
The electrical conductivity detecting device, wherein the first reference frequency is about 10 kHz. The electrical conductivity detection device according to claim 23,
The input electrical signal includes a second input electrical signal of a second frequency;
The first frequency is less than a second reference frequency;
The second frequency is greater than or equal to the second reference frequency;
The second reference frequency is several hundred kHz;
The impedance measuring means measures the absolute value of the impedance between the pair of electrodes according to the output electrical signal with respect to the first input electrical signal, and the pair of pairs according to the output electrical signal with respect to the second input electrical signal. An electrical conductivity detector that measures the phase difference between electrodes. The electrical conductivity detection device according to any one of claims 13 to 24,
The signal generating means is an electrical conductivity detecting device using a rectangular wave electric signal as the input electric signal. The electrical conductivity detection device according to any one of claims 13 to 25,
Equipped with a temperature detection means for detecting the ambient temperature,
The electrical conductivity specifying unit corrects the resistance value and / or the capacitance according to a detection result by the temperature detection unit. A water supply device for supplying water to the measurement target system;
A control device for controlling the supply of water by the water supply device;
A moisture detection device capable of data communication with the control device via a network;
With
The moisture detector is
A pair of electrodes in contact with a measurement target system in which a solute that is insoluble in water is dispersed in water;
Signal generating means for applying an alternating input electric signal to one of the electrodes;
Impedance measuring means for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes;
With
Based on at least one of the absolute value or phase difference of the impedance measured by the impedance measuring means, the resistance value between the pair of electrodes and the capacitance between the pair of electrodes are obtained, and the resistance value and A water content specifying means for determining a water content in the measurement target system based on the capacitance;
The said control apparatus is a sensor network system which controls the said water supply apparatus according to the detection result by the said moisture detection apparatus. A nutrient solution supply device for supplying nutrient solution to the measurement target system;
A control device for controlling the supply of nutrient solution by the nutrient solution supply device;
An electrical conductivity detector capable of data communication with the control device via a network;
With
The electrical conductivity detector is
A pair of electrodes in contact with a measurement target system in which a solute that is insoluble in water is dispersed in water;
Signal generating means for applying an alternating input electric signal to one of the electrodes;
Impedance measuring means for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes;
With
Based on at least one of the absolute value or phase difference of the impedance measured by the impedance measuring means, the resistance value between the pair of electrodes and the capacitance between the pair of electrodes are obtained, and the resistance value and Further comprising electrical conductivity specifying means for determining electrical conductivity between the pair of electrodes based on the capacitance;
The said control apparatus is a sensor network system which controls the said nutrient solution supply apparatus according to the detection result by the said electrical conductivity detection apparatus. A computer-readable program, wherein execution of the program by the computer causes the computer to
A pair of electrodes in contact with a measurement target system in which a solute that is insoluble in water is dispersed in water;
Signal generating means for applying an alternating input electric signal to one of the electrodes;
Impedance measuring means for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes;
Based on at least one of the absolute value or phase difference of the impedance measured by the impedance measuring means, the resistance value between the pair of electrodes and the capacitance between the pair of electrodes are obtained, and the resistance value and A moisture content specifying means for obtaining a moisture content in the measurement target system based on the capacitance;
A program for functioning as a moisture detection device. A computer-readable program, wherein execution of the program by the computer causes the computer to
A pair of electrodes in contact with a measurement target system in which a solute that is insoluble in water is dispersed in water;
Signal generating means for applying an alternating input electric signal to one of the electrodes;
Impedance measuring means for measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes;
Based on at least one of the absolute value or phase difference of the impedance measured by the impedance measuring means, the resistance value between the pair of electrodes and the capacitance between the pair of electrodes are obtained, and the resistance value and Based on the capacitance, an electrical conductivity specifying means for obtaining electrical conductivity between the pair of electrodes,
A program for functioning as an electrical conductivity detection device. Contacting a pair of electrodes with a measurement target system in which a solute insoluble in water is dispersed in water; and
Applying an alternating input electrical signal to one of the electrodes;
Measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes;
Based on at least one of the measured absolute value or phase difference of the impedance, a resistance value between the pair of electrodes and a capacitance between the pair of electrodes are obtained, and the resistance value and the capacitance And determining the amount of water in the measurement target system based on
A method for detecting moisture. Contacting a pair of electrodes with a measurement target system in which a solute insoluble in water is dispersed in water; and
Applying an alternating input electrical signal to one of the electrodes;
Measuring at least one of an absolute value or a phase difference between the pair of electrodes based on the input electrical signal and an output electrical signal from the other of the electrodes;
Based on at least one of the measured absolute value or phase difference of the impedance, a resistance value between the pair of electrodes and a capacitance between the pair of electrodes are obtained, and the resistance value and the capacitance And determining the electrical conductivity between the pair of electrodes based on
A method for detecting electrical conductivity.

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