JP6799822B2 - Plant cultivation equipment and method - Google Patents

Description

The present invention relates to a plant cultivation apparatus and method for sterilizing and purifying a culture solution in hydroponics by applying a high electric field.

Plant cultivation by hydroponics has become an important technology for solving food problems these days. Plant growth by hydroponics can be controlled in a controlled space such as a factory, but in order to spread it, it is essential to reduce the cost of growing plants by reducing operating running costs such as equipment depreciation costs. It becomes. Further, in hydroponics, although it is a controlled space, the culture solution is often circulated and used, and a sterilizer is often introduced in order to suppress the outbreak of harmful bacteria or blue-green algae.
As a sterilizing device in hydroponics, a device in which an electrode is installed in a culture solution and a high electric field pulse is applied to sterilize is known (see Patent Document 1). FIG. 6 is a diagram showing the configuration of a conventional plant cultivation apparatus. FIG. 6 has a cultivation tank 1 for hydroponically cultivating a plant 3, a sterilization tank 6 for receiving a culture solution 2 in the cultivation tank 1 and allowing the plant 3 to be returned to the cultivation tank 1, and a pipe 4. .. In the sterilization tank 6, a high-voltage pulse power supply device 5 and a pair of electrodes 7 arranged to face each other are connected, a voltage is applied to the pair of electrodes 7, and an electric field is applied to the culture solution 2 between the pair of electrodes 7. Sterilize.

JP-A-63-56227

However, in the apparatus described in Patent Document 1, since the sterilization tank 6 is provided separately from the cultivation tank 1 for cultivating the plant 3, the equipment becomes large and the equipment cost increases, resulting in an increase in the plant growth cost. Connect. Further, by providing the sterilization tank 6 separately from the cultivation tank 1, if harmful bacteria are generated or mixed in the pipe 4 between the sterilization tank 6 and the cultivation tank 1 and the cultivation tank 1 itself, the sterilization is performed. The challenge is that the plants get sick and the financial loss is high because they cannot.
Further, when an electrode 7 is installed in the cultivation tank 1 to sterilize, a high electric field is applied to sterilize the roots. Therefore, if a high electric field is erroneously applied to the roots of the plant 3, the roots are damaged. The problem is to hinder the growth of plants.
Therefore, an object of the present invention is to solve the above-mentioned problems, and by enabling sterilization in a cultivation tank, it is possible to reduce the size of equipment, protect plants from diseases, and stably produce plants. The purpose is to provide plant cultivation equipment and methods.

According to the plant cultivation apparatus according to one aspect of the present invention, in order to achieve the above object.
A cultivation tank for hydroponically cultivating plants and
Electrodes divided into a plurality of electrodes and arranged to face each other in the cultivation tank,
A power supply that applies a voltage between the electrodes arranged so as to face each other,
A current measuring device for measuring the current value between the electrodes arranged opposite to each other is provided.
The presence or absence of the roots of the plant is determined from the current value measured by the current measuring device between the electrodes to which the voltage is applied from the power source, and it is determined that the roots of the plant do not exist and are arranged facing each other. A voltage application control unit for applying a sterilization voltage from the power source is further provided between the electrodes.
According to the plant cultivation method according to another aspect of the present invention, in order to achieve the above object.
In the plant cultivation method of hydroponically cultivating plants in the cultivation tank,
A voltage for detecting the presence or absence of roots is applied from a power source to the electrodes divided into a plurality of electrodes in the cultivation tank and arranged opposite to each other.
The voltage application control unit determines the presence or absence of plant roots based on the current value between the electrodes to which the voltage is applied.
In the voltage application control unit, it is determined by the voltage application control unit that the root of the plant is present at the end of the electrode determined by the voltage application control unit and that the root of the plant is not present, and the voltage application control unit is used for sterilization. For sterilization, select the facing electrodes in which the roots of the plant do not exist and the distance from the end of the electrode to which the voltage is applied is 2.5 times or more the distance between the facing electrodes. Apply voltage.

According to the plant cultivation apparatus and method according to the above aspect of the present invention, sterilization is possible in the cultivation tank, so that the sterilization tank becomes unnecessary, and the equipment can be miniaturized and the equipment cost can be reduced. Furthermore, since the plants are sterilized in the cultivation tank, the plants can be protected from diseases and stable production can be achieved.

Block diagram of plant cultivation apparatus in embodiment of this invention A flowchart showing the operation of the plant cultivation apparatus according to the embodiment of the present invention. Diagram of electrode configuration when the electrodes of the plant cultivation device according to the embodiment of the present invention are uniformly divided. Diagram of electrode configuration when the electrodes of the plant cultivation device according to the embodiment of the present invention are unevenly divided. The figure which shows the example of the current waveform when the state of the root is measured by the electric current by the plant cultivation apparatus in embodiment of this invention. The figure which shows the structure of the conventional plant cultivation apparatus

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment)
FIG. 1 is a configuration diagram of a plant cultivation device according to an embodiment of the present invention, and the configuration of the plant cultivation device will be described below.
The plant cultivation device includes at least a cultivation tank 103, a pair of electrodes 105, a power supply 104, a current measuring device 108, and a voltage application control unit 109.

In the cultivation tank 103, the plant 101 is arranged and the plant 101 is hydroponically cultivated.

The electrodes 105 are divided into a plurality of electrodes 105 and arranged to face each other in the cultivation tank 103. For example, one set is composed of a pair of electrodes 105 arranged opposite to each other, a plurality of sets of electrodes 105 are arranged in parallel, and the plant 101 is arranged so as to sandwich the plant 101 between at least one set of electrodes 105.

The power supply 104 can independently apply a voltage between the electrodes 105.
The current measuring device 108 can measure the current value between the electrodes 105.
The voltage application control unit 109 determines the presence or absence of the root 101a of the plant 101 based on the current value measured by the current measuring device 108 between the electrodes 105 to which the voltage is applied from the power supply 104, and the root 101a of the plant 101 does not exist. A voltage for sterilization can be applied from the power supply 104 to the electrodes 105 which are determined to be facing each other and are arranged to face each other.

In FIG. 1, the root 101a of the plant 101 exists in the cultivation tank 103 containing the culture solution 102, and the voltage required for sterilization is applied to the pair of electrodes 105 arranged opposite to each other in the culture solution 102 by the power supply 104. Can be applied to apply an electric field required for sterilization between the pair of electrodes 105 facing each other. As a specific example, a plurality of sets of rectangular plate-shaped electrodes 105 are arranged upright in, for example, a rectangular parallelepiped box-shaped cultivation tank 103 facing each other, and in the plate surface direction (for example, along the short side). It is divided and arranged by an insulator 106, and is insulated from each other with each set of electrodes 105. In FIG. 1, a pair of plate-shaped members in which electrodes 105 and insulators 106 are alternately arranged are arranged so as to sandwich the root 101a of the plant 101.

At this time, the electrode 105 has an electrode width (short side) of the electrode 105 in order to effectively apply an electric field to, for example, a rectangular body-shaped electric field application area 110 formed between the electrode 105 and the electrode 105 facing the electrode 105. The shorter of L1 and the electrode height L2, that is, the distance L3 between the electrodes with the opposing electrode 105 is set to 5 times or less with respect to the length L1 of the short side of the electrode 105. When the distance L3 between the electrodes is extremely small compared to the length L1 of the short side of the electrode 105, the electric field between the electrodes 105 can be regarded as uniform. However, if the distance L3 between the electrodes is too large as compared with the length L1 of the short side of the electrode 105, the electric field becomes non-uniform. In general, for the electrostatic field, the distribution of the electric field strength can be obtained by using Poisson's equation, and as a preferable condition that a uniform electric field can be applied, the electrode facing the length L1 of the short side of the electrode 105 The distance L3 between the electrodes with 105 is set to 5 times or less.

Here, examples of the voltage for detecting the presence or absence of roots include 20V, 60V, and 150V. The higher the voltage value, the higher the root detection accuracy. Therefore, 150V is preferable. Further, the bals width when applying the voltage for detecting the presence or absence of roots is preferably about 1 μsec, which does not cause electrolysis of water.

Further, the electric field required for sterilization can be exemplified to be 10 kV / cm or more.

Further, the electrode switching device 107 is composed of a plurality of switches 107a. Each switch 107a of the electrode switching device 107 can open and close an electric circuit between the divided electrode 105 and the plurality of power supplies 104. By operating the electrode switching device 107, the electric field is closed only for the pair of switches 107a to which the pair of electrodes 105 facing each other and the power supply 104 are connected, and all the electric fields of the switches 107a of the other electrode switching device 107 are opened. Therefore, the electric field can be applied by applying the voltage for detecting the presence or absence of roots only to the electric field application area 110 formed between the pair of electrodes 105. By switching the electrode switching device 107, the electric field application area 110 can be switched. Further, the current measuring device 108 can measure the current value flowing through the electric field application area 110 between the pair of electrodes 105. Based on the measurement result of the current value by the current measuring device 108, the voltage application control unit 109 determined whether or not the root 101a of the plant 101 was present in the electric field application area 110, and the voltage application control unit 109 determined that there was no root 101a. In this case, the voltage application control unit 109 can control the power supply 104 to apply a voltage for sterilization to the pair of electrodes 105. As described above, these controls are performed by the voltage application control unit 109 connected to the power supply 104 and the current measuring device 108. Further, when an electric field required for sterilization is applied to the pair of electrodes 105, strictly speaking, a high electric field is formed outside the electric field application area 110 formed between the pair of electrodes 105. When this high electric field is applied to the root 101a of the plant 101, the growth of the plant 101 is inhibited. In order to solve this problem, an electrode 105 that is not affected by the electric field is selected from the position of the root 101a of the plant 101, and an electric field for sterilization is applied to the selected electrode 105. The electric field strength distribution can be calculated by the Poisson's equation, and the preferred condition is that the distance between the electrodes is at least 2.5 times the distance L3 so that the electric field is not affected. That is, the distance between the end of the electrode 105 in which the root 101a of the plant 101 is present and the end of the electrode 105 in which the root 101a of the plant 101 is not present and the voltage for sterilization is applied is the distance L3 between the electrodes 105 arranged opposite to each other. An electrode 105 in which the root 101a of the plant 101 does not exist is selected as an electrode for applying a voltage for sterilization so that a state separated by 2.5 times or more is established. The selection of the electrode 105 is performed by the voltage application control unit 109. The opening / closing control of the electrode switching device 107 is also performed by the voltage application control unit 109.

Next, the operation of the plant cultivation apparatus of FIG. 1 will be described with reference to the flowchart of FIG. In FIG. 2, the operation of detecting the presence or absence of the root 101a of the plant 101 between the electrodes 105 and applying a voltage to the electrode 105 in which the root 101a does not exist will be described.

First, in step S101, the voltage application control unit 109 is used to control the electrode switching device 107, and the electrodes 105 that are divided into a plurality of electrodes and are arranged to face each other are connected to the power supply 104.

Next, in step S102, the power supply 104 is controlled, and a voltage for detecting the presence or absence of roots is applied to a set of electrodes 105 arranged to face each other.

Next, in step S103, the current measuring device 108 measures the current between the pair of electrodes 105 to which the voltage for detecting the presence or absence of roots is applied in step S102.

Next, in step S104, the plant 101 between the set of electrodes 105 to which the voltage application control unit 109 applies a voltage for detecting the presence or absence of roots based on the current value measured by the current measuring device 108. The existence status of the root 101a is determined. The method of determination will be described later with reference to FIG. For the electrode 105 determined that the root 101a of the plant 101 does not exist, it is selected from the position of the root 101a of the plant 101 whether or not the set of electrodes 105 is not affected by the electric field. Specifically, the distance between the end of the electrode 105 in which the root 101a of the plant 101 is present and the end of the electrode 105 in which the root 101a of the plant 101 is not present and the voltage for sterilization is applied is set so as to face the electrodes 105. An electrode 105 in which the root 101a of the plant 101 does not exist, such that a state separated by 2.5 times or more the distance L3 is established, is selected as an electrode for applying a voltage for sterilization. This can be selected by the voltage application control unit 109 if the arrangement configuration state between the electrodes and the position of the set of electrodes 105 to be processed in steps S101 to S104 are known in advance.

Next, in step S105, the voltage application control unit 109 applies an electric field for sterilization to the selected electrode 105 by the power supply 104. It is preferable to monitor the amount of bacteria or blue-green algae for a certain period of time within a range in which the temperature of the culture solution does not rise, return to step S101 until the amount reaches a certain amount, and perform the same treatment on another set of electrodes 105. ..

At this time, the processing time from the application of the voltage waveform for root presence detection in step S102 to the application of the voltage waveform for sterilization in step S105 in the voltage application control unit 109 depends on the flow velocity of the culture solution 102. To decide. This is because when the treatment time is too long even though the flow rate of the culture solution 102 is high, the existence status of the root 101a at the time of step S102 and the existence status of the root 101a at the time of step S105 are different, and the root of the plant 101 There is a problem that an electric field for sterilization is erroneously applied to 101a.

As an example of determining the processing time, when water is supplied to the cultivation tank 103 having a cross-sectional area of 200 cubic centimeters at 8 liters per minute, the flow velocity is 6.7 microseconds per millisecond, so steps S102 to S105 are 1 mm. If processed in seconds, the effect of the movement of the root 101a due to the water flow can be ignored.

Further, the voltage waveform in step S102 may be a DC constant voltage or a pulse waveform. Further, the voltage waveform in step S105 may be a DC constant voltage or a pulse waveform. Further, it is preferable that the voltage application in step S102 or step S105 has a waveform that does not cause electrolysis of the culture solution 102 because the composition of the culture solution 102 is not changed. Specifically, if 1.23 V, which is the theoretical limit voltage for electrolysis of water, is not substantially applied, or if it has a short pulse waveform, electrolysis of water does not occur.

In the above flow, the current value of the electrodes 105 is measured one by one, and it is determined whether or not to sterilize, and the sterilization operation is performed. However, the present invention is not limited to such an example. .. For example, as described later, current value measurement of a plurality of sets of electrodes 105 is allowed as long as the processing time from applying the voltage waveform for root presence detection in step S102 to applying the voltage waveform for sterilization in step S105 allows. Is also included, which determines whether or not to sterilize each group, and performs a sterilization operation for each group.

Next, in the plant cultivation apparatus of FIG. 1, an electrode configuration diagram when the electrode 105 is uniformly divided is shown in FIG.
If it cannot be assumed that the root 101a of the plant 101 is present in advance, or if the existence probability of the root 101a in each of the divided electrodes 105 is unknown, the electrode 105 may be uniformly divided.

Next, in the plant cultivation apparatus of FIG. 1, an electrode configuration diagram when the electrode 105 is non-uniformly divided is shown in FIG.
If it can be assumed that the root 101a of the plant 101 is present in advance, or if the existence probability of the root 101a in each of the divided electrodes 105 is expected to be biased, the electrode 105 may be divided non-uniformly. For example, in a place where it is assumed that the root 101a of the plant 101 is likely to be present when the first electric field is applied, the plant 101 is divided so as to have the size of the area where the root 101a is present, such as the first electrode 105a. Further, the area where the existence probability of the root 101a is expected to increase due to the growth process of the plant 101 is divided into small areas like the second electrode 105b. On the contrary, even if the plant 101 grows, the area where the existence probability of the root 101a is assumed to be low is the end of the third electrode 105c and the existence probability of the root 101a, as in the third electrode 105c. The distance from the end of the high electrode 105a or the end of the electrode 105b is divided so as to be separated by a length (L4) of 2.5 times or more the distance between the electrodes L3. That is, if the electrode 105 is non-uniformly divided into an area where the existence probability of the root 101a is large and an area where the existence probability of the root 101a is small, the plant cultivation apparatus can be operated efficiently.

Next, in FIG. 5, in the plant cultivation apparatus according to the embodiment of the present invention, when the same voltage waveform 111 is applied to each of the two sets of electrodes 105, the current of the set of electrodes 105 in which the root 101a does not exist in the electric field application area 110. An example of the waveform 112a and the current waveform 112b of the set of electrodes 105 in which the root 101a is present is shown. In FIG. 5A, the current waveform 112a is in a state where the root 101a does not exist. In FIG. 5B, the current waveform 112b is in the state where the root 101a is present. Comparing the current waveform 112a in the absence of the root 101a and the current waveform 112b in the presence of the root 101a, the current waveform 112b in the presence of the root 101a has a higher current value than the current waveform 112a in which the root 101a does not exist. It can be seen that the presence or absence of the root 101a can be detected. Based on this, the voltage application control unit 109 determines the presence or absence of the root 101a of the plant 101.

According to the apparatus described above, a voltage for detecting the presence or absence of roots is applied from the power supply 104 to the electrodes 105 which are divided into a plurality of electrodes 105 and arranged so as to face each other. The voltage application control unit 109 determines the presence or absence of the root 101a of the plant 101, and the voltage application control unit 109 can apply a sterilizing voltage from the power supply 104 to the electrode 105 determined that the root 101a of the plant 101 does not exist. it can. As a result, the electric field can be applied only to the area where the root 101a does not exist, and the cultivation tank 103 can be sterilized. Therefore, the sterilization tank becomes unnecessary, and it is possible to reduce the size of the equipment and the equipment cost. Further, since the electrodes 105 can be divided and switched to apply a voltage, the current flowing through the pair of electrodes 105 can be reduced. As a result, the power supply 104 can be miniaturized, and the equipment cost can be further reduced.

In addition, by appropriately combining any embodiment or modification of the various embodiments or modifications, the effects of each can be achieved. Further, it is possible to combine the embodiments or the embodiments, or the embodiments and the embodiments, and also to combine the features in the different embodiments or the embodiments.

According to the plant cultivation apparatus and method according to the above aspect of the present invention, since sterilization is possible in the cultivation tank, the sterilization tank becomes unnecessary, and the equipment can be miniaturized and the equipment cost can be reduced. Further, according to the plant cultivation apparatus and method, since the plant is sterilized in the cultivation tank, the sterilization treatment can be effectively performed, and the plant can be protected from diseases and stably produced. Further, according to the plant cultivation apparatus and method, since the electrodes can be divided and switched to apply a voltage, the current flowing through the pair of electrodes can be reduced. As a result, the power supply can be miniaturized, and the equipment cost can be further reduced. Further, according to the plant cultivation apparatus and method, since the electric current can be reduced, safety measures are facilitated, and the introduction of sterilization technology by applying a voltage in hydroponics is accelerated.

101 Plant 101a Plant root 102 Culture solution 103 Cultivation tank 104 Power supply 105 Electrode 105a First electrode 105b Second electrode 105c Third electrode 106 Insulator 107 Electrode switching device 107a Switch 108 Current measuring device 109 Voltage application control unit 110 Electric field application area L1 Electrode width L2 Electrode height L3 Electrode distance L4 Length 2.5 times or more of electrode distance 111 Voltage waveform 112a, 112b Current waveform

Claims (4)

A cultivation tank for hydroponically cultivating plants and
Electrodes divided into a plurality of electrodes and arranged to face each other in the cultivation tank,
A power supply that applies a voltage between the electrodes arranged so as to face each other,
A current measuring device for measuring the current value between the electrodes arranged opposite to each other is provided.
The presence or absence of the root of the plant is determined from the current value measured by the current measuring device between the electrodes to which the voltage is applied from the power source, and it is determined that the root of the plant does not exist and is arranged so as to face each other. A plant cultivation apparatus further comprising a voltage application control unit for applying a voltage for sterilization from the power source between the electrodes. The first aspect of claim 1, wherein each of the plurality of electrodes divided and arranged to face each other has a rectangular plate shape, and is arranged to face each other at a distance of 5 times or less the short side of each rectangular plate-shaped electrode. Plant cultivation equipment. The distance between the end of the electrode in which the root of the plant is present and the end of the electrode in which the root of the plant is not present and an electrode for which a sterilizing voltage is applied is 2.5 times the distance between the electrodes arranged opposite to each other. The plant cultivation apparatus according to claim 1, which is separated from the above. In the plant cultivation method of hydroponically cultivating plants in the cultivation tank,
A voltage for detecting the presence or absence of roots is applied from a power source to the electrodes divided into a plurality of electrodes in the cultivation tank and arranged opposite to each other.
The voltage application control unit determines the presence or absence of plant roots based on the current value between the electrodes to which the voltage is applied.
In the voltage application control unit, it is determined by the voltage application control unit that the root of the plant is present at the end of the electrode determined by the voltage application control unit and that the root of the plant is not present, and the voltage application control unit is used for sterilization. For sterilization, select the facing electrodes in which the roots of the plant do not exist and the distance from the end of the electrode to which the voltage is applied is 2.5 times or more the distance between the facing electrodes. A plant cultivation method in which a voltage is applied.

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