Apparatus for Aeroponics and Method for Aeroponics using the same

Abstract

The present invention relates to a spray-type hydroponic cultivation device and a spray-type hydroponic cultivation method using the same, wherein the ratio of floating nutrient solution particles occupying a cultivation space for hydroponic cultivation is measured by a sensor unit provided in the cultivation space, and the spraying of the nutrient solution is controlled so that the measured particle ratio is within a preset range, wherein the spraying of the nutrient solution proceeds in the cultivation space and the amount of decrease in the measured particle ratio is derived in a time interval from the start of spraying to the point where the measured particle ratio is at its lowest, and the second nutrient solution spraying step is performed after the first nutrient solution spraying step, wherein the start of spraying is set based on the amount of decrease in the derived particle ratio and the spraying of the nutrient solution is initiated at the set start of spraying, and the spraying of the nutrient solution is stopped after the end of the first nutrient solution spraying step and before the start of the second nutrient solution spraying step.

Description

Technology Field

[0001] The present invention relates to a spray-type hydroponic cultivation device and a spray-type hydroponic cultivation method using the same. Background Technology

[0002] Hydroponics, or nutrient solution cultivation, is a method of growing crops in a soilless environment without using soil, by supporting and fixing the plants in place through various means and using a nutrient solution in which essential elements necessary for crop growth are dissolved at appropriate concentrations according to their absorption rates.

[0003] Hydroponic cultivation is broadly divided into water culture and medium culture based on the cultivation method. Among these, water culture refers to growing crops in a nutrient solution without a solid medium to support the roots, and is further classified into deep flow technique (DFT) and aeroponics.

[0004] In deep water hydroponics, crop roots are supplied with nutrients while constantly submerged in the nutrient solution; however, this inhibits root respiration, causing the root portions to rot and resulting in extremely poor crop growth.

[0005] To solve these problems of deep water hydroponics, a method was applied in spray hydroponics to spray particulate nutrient solution using a spray nozzle toward the roots of crops suspended in the air.

[0006] Spray hydroponics, or aeroponic cultivation, is a cultivation method in which nutrient solution is intermittently sprayed onto plant roots while the roots are exposed to the air. In spray hydroponics, sufficient oxygen is supplied to the roots because the nutrient solution is sprayed intermittently within a light-blocked bed. Since oxygen deficiency does not occur, plant growth is faster compared to other hydroponic cultivation methods.

[0007] Spray hydroponics can maximize the development of the rhizosphere, which acts as the digestive organ of plants. By maximizing the development of the rhizosphere, it facilitates the formation of the taproot, lateral roots branching out from it, and root hairs composed of single cells. This allows for the maximization of nutrient absorption rates by cultivated crops and reduces unnecessary consumption of water and nutrients. Furthermore, by controlling the spraying cycle, it is possible to artificially manage drought stress in crops, thereby increasing the yield of active ingredients in functional crops.

[0008] However, aerobic hydroponics utilizes a high-pressure spraying method to produce optimal spray particles. Consequently, initial facility costs are high, and it is difficult to maintain the temperature necessary for growth because the roots are constantly exposed to the air.

[0009] Furthermore, in spray hydroponics, root growth must be optimized so that crops effectively absorb nutrient solution and sufficiently accumulate active ingredients. To achieve this, the spraying must be controlled to maintain a constant ratio of suspended nutrient particles within the hydroponic space, but such control is very difficult.

[0010] Furthermore, in aeroponic hydroponics, control of the nutrient solution spraying cycle (duration and interval) is necessary to maximize root zone development. An excessively long duration results in the plant roots becoming submerged in the nutrient solution, causing water droplets to form on the roots. Consequently, this eliminates the differentiation from other hydroponic techniques that rely on submersion cultivation and prevents the development of root hairs.

[0011] An excessively long interval causes plant roots to dry out excessively, leading to damage to root cells; since damaged root cells are difficult to regenerate, this results in a decline in productivity.

[0012] In addition, in aerobic hydroponics, the nozzles that spray the nutrient solution are prone to clogging as the nutrient solution components stick to them, so a lot of effort is required for maintenance. Prior art literature

[0013] Registered Patent Publication No. 10-2416018 Registered Patent Publication No. 10-2320847 The problem to be solved

[0014] The present invention aims to provide, through one embodiment, a spray-type hydroponic cultivation device in which nutrient solution particles floating within a hydroponic cultivation space are maintained at a constant ratio through spray control, and a spray-type hydroponic cultivation method using the same.

[0015] In addition, through one embodiment, the present invention aims to provide a spray-type hydroponic cultivation device capable of detecting abnormalities in a spray nozzle in a simple manner, and a spray-type hydroponic cultivation method using the same. means of solving the problem

[0016] To solve the above-mentioned problem, the present invention provides a spray-type hydroponic cultivation method in which a nutrient solution is repeatedly sprayed into a cultivation space for hydroponic cultivation, the ratio of floating nutrient solution particles occupying the cultivation space is measured, and the spraying of the nutrient solution is controlled so that the measured particle ratio is within a preset upper and lower limit range. In this method, while the spraying of the nutrient solution into the cultivation space is in progress, a change in the measured particle ratio is derived in a time interval from the start of spraying until the point at which the measured particle ratio becomes the lowest, and a next spraying start time is set based on the derived change in particle ratio, or while the spraying of the nutrient solution into the cultivation space is stopped, a change in the measured particle ratio is derived in a time interval from the stop of spraying until the point at which the measured particle ratio becomes the highest, and a next spraying stop time is set based on the derived change in particle ratio.

[0017] It may include: a first nutrient solution spraying step in which nutrient solution spraying is performed in the cultivation space and a decrease in the measured particle ratio is derived during a time interval from the spraying start time to the point in time when the measured particle ratio becomes the lowest; and a second nutrient solution spraying step performed after the first nutrient solution spraying step, wherein a spraying start time is set based on the derived decrease in the particle ratio and nutrient solution spraying is initiated at the set spraying start time.

[0018] The second nutrient solution spraying step can set the spraying start time as the point in time when the measured particle ratio reaches the value obtained by adding the reduction amount of the derived particle ratio to the lower limit.

[0019] The spray pressure of the first nutrient solution spraying step and the spray pressure of the second nutrient solution spraying step may be the same.

[0020] It may include: a first spraying interruption step in which the spraying of the nutrient solution in the cultivation space is stopped, and the increase in the measured particle ratio is derived during the time interval from the point of spraying interruption to the point in time when the measured particle ratio reaches its maximum; and a second spraying interruption step performed after the first spraying interruption step, in which the spraying interruption point is set based on the derived increase in the particle ratio, and the spraying of the nutrient solution is stopped at the set spraying interruption point.

[0021] The second spray interruption step above may set the spray start time as the point in time when the measured particle ratio reaches the value obtained by subtracting the increase in the derived particle ratio from the upper limit.

[0022] In addition, the present invention relates to a spray-type hydroponic cultivation method in which a nutrient solution is sprayed into a cultivation space for hydroponic cultivation, a particle ratio in which floating nutrient solution particles occupy the cultivation space is measured, and the spraying of the nutrient solution is controlled so that the measured particle ratio is within a preset upper and lower limit range, wherein the nutrient solution is sprayed into the cultivation space and a decrease amount of the measured particle ratio is derived in a time interval from the start of the spraying to the point where the measured particle ratio becomes the lowest; a first spraying interruption step in which, after the first nutrient solution spraying step, the spraying of the nutrient solution into the cultivation space is stopped and an increase amount of the measured particle ratio is derived in a time interval from the stop of the spraying to the point where the measured particle ratio becomes the highest; and a second nutrient solution spraying step in which, after the first spraying interruption step, the start of the spraying is set based on the derived decrease amount of the particle ratio and the spraying of the nutrient solution is started at the set start of the spraying. The above-mentioned problem is solved by providing a spray-type hydroponic cultivation method comprising: a first spray interruption step, a second spray interruption step in which a spray interruption time is set based on the increase in the derived particle ratio after the first spray interruption step, and the nutrient solution spray is stopped at the set spray interruption time. Effects of the invention

[0023] As described above, the embodiments of the present invention have the following effects.

[0024] First, according to one embodiment of the present invention, the effect of maintaining a constant ratio of nutrient solution particles floating in a hydroponic cultivation space through spray control is provided.

[0025] Second, according to one embodiment of the present invention, the effect of detecting whether there is an abnormality in the spray nozzle in a simple way is provided. Brief explanation of the drawing

[0026] FIG. 1 is a conceptual diagram schematically illustrating a spray-type hydroponic cultivation device according to one embodiment of the present invention. FIG. 2 is a plan view showing a cultivation housing to explain a sensor unit for measuring the particle ratio of floating nutrient solution particles occupying the cultivation space in the cultivation space illustrated in FIG. 1. Figure 3 is a block diagram showing the configuration for performing a spray hydroponic cultivation method. Figures 4 and 5 are graphs showing a spray hydroponic cultivation method. Specific details for implementing the invention

[0027] The embodiments described below are presented as examples to aid in understanding the invention, and it should be understood that the invention may be implemented with various modifications different from the embodiments described herein. However, in describing the invention, detailed descriptions and specific illustrations of related known functions or components are omitted if it is determined that such detailed descriptions or specific illustrations might unnecessarily obscure the essence of the invention. Furthermore, the attached drawings are not drawn to actual scale to aid in understanding the invention, and the dimensions of some components may be exaggerated.

[0028] The first and second terms used in this application may be used to describe various components, but the components should not be limited by the terms. The terms are used solely for the purpose of distinguishing one component from another.

[0029] Furthermore, the terms used in this application are used merely to describe specific embodiments and are not intended to limit the scope of the rights. The singular expression includes the plural expression unless the context clearly indicates otherwise. Terms such as “comprising,” “consisting of,” or “consisting of” in this application are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0030] Hereinafter, a spray-type hydroponic cultivation device (1) according to one embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a conceptual diagram schematically showing a spray-type hydroponic cultivation device (1) according to one embodiment of the present invention.

[0031] Referring to FIG. 1, a spray-type hydroponic cultivation device (1) according to one embodiment of the present invention includes a nutrient tank (10) for storing a nutrient solution, a pump (20) for moving the nutrient solution, a high-pressure tank (30) for storing the nutrient solution moved from the pump (20) in a high-pressure state, an opening / closing valve (40) that can be opened and closed to intermittently supply the nutrient solution stored in the high-pressure tank (30) to a spray nozzle (50), a hydroponic cultivation unit (100) equipped with a spray nozzle (50), and a nutrient solution circulation channel (60) formed so that the nutrient solution circulates through each of the above-described components.

[0032] The nutrient tank (10) is formed to store nutrient solution. The stored nutrient solution includes newly supplied nutrient solution and nutrient solution recovered from the hydroponic cultivation unit (100).

[0033] The pump (20) delivers the nutrient solution introduced from the nutrient solution tank (10) to the high-pressure tank (30) at high pressure. The pump (20) may operate intermittently or at a constant frequency, or continuously. As described below, the pump (20) generates a pressure that allows the spray nozzle (50) to spray nutrient solution particles (P) of approximately 50 microns in size on average.

[0034] The high-pressure tank (30) stores the nutrient solution in a high-pressure state. The high-pressure tank (30) stores a significant amount of the nutrient solution in advance at high pressure. Accordingly, the high-pressure tank (30) can supply the high-pressure nutrient solution to the spray nozzle (50) at a specific time with almost no time delay, so that the nutrient solution is sprayed at high pressure through the spray nozzle (50).

[0035] When using only the pump (20) without the high-pressure tank (30), it takes a relatively long time to supply the nutrient solution to the spray nozzle (50) at the required high pressure.

[0036] The opening / closing valve (40) is provided between the high-pressure tank (30) and the spray nozzle (50), and supplies nutrient solution from the high-pressure tank (30) to the spray nozzle (50) by opening, and stops the supply of nutrient solution from the high-pressure tank (30) to the spray nozzle (50) by closing. The opening / closing valve (40) includes a solenoid valve.

[0037] The hydroponic cultivation unit (100) includes a cultivation housing (110) in which a space is formed inside, a spray nozzle (50) formed to spray a nutrient solution, a first sensor unit (140) for measuring the particle ratio of the nutrient solution, a second sensor unit (150) for measuring the growth degree of a crop (C), and a nutrient solution recovery guide (120) for guiding the nutrient solution so that the supplied nutrient solution is recovered.

[0038] The cultivation housing (110) forms the exterior of the hydroponic cultivation unit (100) and can be formed from various materials such as synthetic resin and metal. The cultivation housing (110) can maintain an internal space that is blocked from external light.

[0039] The cultivation housing (110) may be formed as a single unit including an upper portion and a lower portion located below the upper portion, or it may be separated into a body with a cover and an open top. A cultivation port (130), such as a through hole, is formed in the upper portion or the cover so that a crop (C) can be placed therein. The crop (C) located in the cultivation port (130) has leaves located on the outside and a root zone located inside the cultivation housing (110).

[0040] A spray nozzle (50) is provided on the upper part of the cultivation housing (110) and formed to spray nutrient solution into the internal space of the cultivation housing (110). The spray nozzle (50) can rotate by a predetermined angle and may be provided in multiple numbers so that the sprayed nutrient solution particles (P) are distributed as uniformly as possible within the internal space.

[0041] The spray nozzle (50) has an orifice formed so that nutrient solution particles (P) with an average diameter of 50 microns (approximately between 10 and 80 microns), which are known to be most effective for spray water, are maintained at an appropriate density. Here, microns are also referred to as micrometers (micrometer (UK), micrometer (US)), and the unit is μm.

[0042] The first sensor unit (140) measures the particle ratio of the nutrient solution, and a detailed explanation will be provided later.

[0043] The second sensor unit (150) may be a vision sensor, and, for example, can photograph a crop (C) to measure the degree of growth of the crop (C).

[0044] The nutrient solution recovery guide (120) is provided at the bottom of the cultivation housing (110) and is provided with a downward slope so that nutrient solution particles (P) supplied from the spray nozzle (50) settle and flow downward due to their own weight to be discharged to the outside. If the nutrient solution recovery guide (120) consists of a pair, it may be provided with a downward slope facing each other. The nutrient solution collected through the nutrient solution recovery guide (120) is discharged to the outside through an opening formed at the bottom of the cultivation housing (110).

[0045] The nutrient solution circulation path (60) includes a nutrient solution supply path (61) and a nutrient solution recovery path (62).

[0046] The nutrient supply path (61) is a path that sequentially connects the nutrient tank (10), pump (20), high-pressure tank (30), and spray nozzle (50), and is formed so that the nutrient solution moves from the nutrient tank (10) through the pump (20) and high-pressure tank (30) to the spray nozzle (50).

[0047] The nutrient solution recovery channel (62) is a channel that connects the bottom of the cultivation housing (110) and the nutrient solution tank (10) so that the nutrient solution moves from the opening at the bottom of the cultivation housing (110) to the nutrient solution tank (10).

[0048] Hereinafter, the first sensor unit (140) will be described with reference to FIG. 2. FIG. 2 is a plan view showing a cultivation housing (110) to explain the sensor unit for measuring the particle ratio of floating nutrient solution particles (P) in the cultivation space (110a) shown in FIG. 1 that occupy the cultivation space (110a).

[0049] The first sensor unit (140) measures the ratio of nutrient solution particles (P) floating inside the cultivation space (110a) to the cultivation space (110a) as the nutrient solution is sprayed into the cultivation space (110a) through the spray nozzle (50).

[0050] The first sensor unit (140) includes a first transmitter (141) and a first receiver (142). The first transmitter (141) is formed to irradiate light rays, such as far-infrared rays, into the cultivation space (110a). The light rays irradiated by the first transmitter (141) are received by the first receiver (142).

[0051] The first receiver (142) can detect the area formed by the light rays that reach the first receiver (142) among the light rays irradiated from the first transmitter (141) and the remaining area where the light rays do not reach, and transmit information regarding this to the control unit (200) described later. The remaining area where the light rays do not reach is formed because some of the light rays irradiated from the first transmitter (141) are interfered with by floating nutrient solution particles (P) and do not reach the first receiver (142). Using the above information, the density of particles, i.e., the particle ratio, of the nutrient solution particles (P) floating in the cultivation space (110a) occupying the cultivation space (110a) is measured.

[0052] The first transmitting unit (141) and the first receiving unit (142) may each be provided on the inner sides of the mutually facing sides of the cultivation housing (110) as shown in FIG. 2.

[0053] The first sensor unit (140) may further include a second transmitter (143) and a second receiver (144). The light ray irradiated by the second transmitter (143) may intersect with the light ray irradiated by the first transmitter (141). To this end, the second transmitter (143) and the second receiver (144) may be provided on the inner sides of the front and rear of the cultivation housing (110), respectively.

[0054] Hereinafter, a configuration for performing a spray-type hydroponic cultivation method according to one embodiment of the present invention will be described with reference to FIG. 3. FIG. 3 is a block diagram showing a configuration for performing a spray-type hydroponic cultivation method.

[0055] Referring to FIG. 3, a configuration for performing a spray-type hydroponic cultivation method according to one embodiment of the present invention includes a control unit (200), a first sensor unit (140), a second sensor unit (150), a temperature control unit (160), and an opening / closing valve (40).

[0056] The control unit (200) receives signals from the first sensor unit (140) and the second sensor unit (150) and transmits control signals to the temperature control unit (160) and the opening / closing valve (40). The temperature control unit (160) and the opening / closing valve (40) that receive the control signals operate according to the content of the control signals.

[0057] The description of the first sensor unit (140), the second sensor unit (150), and the opening / closing valve (40) is omitted as previously described, and the temperature control unit (160) is described.

[0058] The temperature control unit (160) performs the function of controlling the temperature of the nutrient solution, etc., to maintain the freshness of the nutrient solution or to facilitate the growth of the crop (C). The temperature control unit (160) is provided at a point where temperature control is required, such as a nutrient solution tank (10), a high-pressure tank (30), and a cultivation housing (110).

[0059] Hereinafter, a spray-type hydroponic cultivation method according to one embodiment of the present invention will be described with reference to FIGS. 4 and FIGS. 5. FIGS. 4 and FIGS. 5 are graphs illustrating a spray-type hydroponic cultivation method.

[0060] Referring to FIGS. 4 and 5, a spray hydroponic cultivation method according to one embodiment of the present invention is a method in which a nutrient solution is sprayed intermittently and repeatedly into a cultivation space (110a) for hydroponic cultivation, and the ratio of floating nutrient solution particles (P) occupying the cultivation space (110a) is continuously measured in real time, and the spraying of the nutrient solution is controlled so that the measured particle ratio is within a preset upper limit (d8, d7') and lower limit (d1, d2') range.

[0061] The particle ratio, i.e., particle density, of the nutrient solution particles (P) floating in the cultivation space (110a) must be within an appropriate range. In the following description, the particle ratio may be expressed as particle density.

[0062] When the density of the floating particles is within the appropriate range of the upper limit (d8, d7') and lower limit (d1, d2'), the floating nutrient particles (P) of appropriate size can continuously supply an appropriate amount of water and nutrients without completely settling the plant root hairs within the root zone.

[0063] When the spraying of the nutrient solution begins and continues without interruption, the duration of the spraying becomes excessively long, causing the particle density to exceed the upper limit (d8, d7'). Consequently, the plant roots become submerged in the nutrient solution, water droplets form on the roots, and thus the distinction from other hydroponic cultivation techniques that use submersion disappears, and the development of root hairs does not occur.

[0064] During the interval in which the spraying of the nutrient solution is stopped and the stopped state is maintained, the particle density of the fine nutrient solution particles (P) that were previously sprayed and are suspended gradually decreases as they fall by gravity in the cultivation space (110a) for a certain period of time, are absorbed into the root zone of the plant, or are transpired into the air due to the difference in air pressure. If the interval becomes excessively long, the particle density becomes lower than the lower limit (d1, d2'). Consequently, the roots of the plant become excessively dry, causing damage to the root cells, and the damaged root cells are difficult to regenerate, which leads to a decrease in productivity.

[0065] Therefore, for root hairs to develop well without damaging root cells, the particle density must be within an appropriate range, and to achieve this, the spraying cycle of the nutrient solution must be properly set.

[0066] To set such a spraying cycle, the spraying cycle was previously adjusted using relative humidity as an indicator. However, relative humidity is merely a measurement of water vapor, and nutrient solution cannot effectively be delivered to the root zone of the crop (C) in a gaseous state as water vapor. Therefore, relative humidity is not a meaningful indicator for determining the nutrient solution spraying cycle.

[0067] In a spray-type hydroponic cultivation method according to one embodiment of the present invention, a spraying period in which the nutrient solution is sprayed and a resting period in which the nutrient solution is not sprayed occur alternately. That is, spraying and the cessation of spraying are performed sequentially alternately.

[0068] In addition, certain data obtained during an arbitrary spraying period is used to set the starting point of the spraying period immediately following the aforementioned arbitrary spraying period.

[0069] Similarly, specific data obtained during an arbitrary rest period is used to set the starting point of the rest period immediately following the aforementioned arbitrary rest period. The change amount, decrease amount, increase amount, etc. described below represent absolute values.

[0070] Specifically, in a spray-type hydroponic cultivation method according to one embodiment of the present invention, while nutrient solution spraying is performed in a cultivation space (110a), a change in particle density is derived in a time interval from the start of spraying to the point where the particle ratio becomes the lowest. Based on the derived change in particle density, the next spraying start time is set.

[0071] Alternatively, in a spray-type hydroponic cultivation method according to one embodiment of the present invention, while the spraying of nutrient solution in the cultivation space (110a) is stopped, a change in particle density is derived in the time interval from the point of spraying cessation to the point where the particle ratio reaches its maximum, and the next spraying cessation point can be set based on the derived change in particle density.

[0072] Referring to FIG. 4, when a spray hydroponic cultivation method according to one embodiment of the present invention is disclosed, a first nutrient solution spraying step (S1) is performed after a preliminary step (P) corresponding to a resting period. The first nutrient solution spraying step (S1) is a step in which a nutrient solution is sprayed in a cultivation space (110a).

[0073] The preliminary stage (P) is a stage performed during a rest period in which the nutrient solution spraying is stopped and the particle density generated by the previous spraying gradually decreases. It is similar to the first spraying suspension stage (S2) or the second spraying suspension stage (S4) described later. The preliminary stage (P) ends at the first time point (t1).

[0074] The first nutrient solution spraying step (S1) is performed during the spraying period. The first nutrient solution spraying step (S1) starts at the first time point (t1), passes through the second time point (t2), and ends at the third time point (t3).

[0075] In the first nutrient solution spraying step (S1), the opening / closing valve (40) is opened at a first time point (t1) when the particle density reaches a preset first starting value (d4), and accordingly, the nutrient solution spraying is initiated through the spray nozzle (50).

[0076] When nutrient solution spraying is initiated in the first nutrient solution spraying step (S1), the particle density within the cultivation space (110a) is not measured to increase immediately due to the size of the cultivation space (110a), spraying pressure, the number and location of spray nozzles, plant transpiration rate, etc.

[0077] When the nutrient solution spraying begins in the first nutrient solution spraying step (S1), the particle density decreases while forming a constant slope from the first time point (t1).

[0078] Therefore, the first starting value (d4) is set to a value greater than the lower limit (d1) by taking into account the temporary decrease in particle density.

[0079] In the first nutrient solution spraying stage (S1), the nutrient solution spraying continues, and the particle density no longer decreases and begins to rise from the second time point (t2) when the particle density reaches the first minimum value (d3).

[0080] At this time, the amount of particle density decrease between the first starting value (d4) and the first minimum value (d3) and the amount of time increase between the first time point (t1) and the second time point (t2) are derived by the control unit (200).

[0081] In this case, the first minimum value (d3) may be greater than the lower limit value (d1) as shown in FIG. 4.

[0082] In the first nutrient solution spraying stage (S1), the particle density increases with a constant slope from the second time point (t2) to the third time point (t3). The third time point (t3) is the time when the particle density reaches a preset first intermediate value (d5).

[0083] The slope indicating an increase in particle density in the first nutrient solution spraying stage (S1) varies depending on the type of plant, the degree of growth, the condition of the nozzle, etc. As the plant grows, that is, as the volume of the roots increases, the extra space in the cultivation space (110a) decreases and the slope becomes steeper, and as the nozzle clogging condition becomes more severe, the spray volume decreases and the slope becomes gentler.

[0084] Therefore, the degree of plant growth or the clogging state of the nozzle can be predicted based on the magnitude of the slope indicating an increase in particle density in the first nutrient solution spraying stage (S1).

[0085] When the particle density reaches a preset first interruption value (d5), the first nutrient solution spraying step (S1) is terminated. Subsequently, a first spraying interruption step (S2) is performed in which the spraying of the nutrient solution in the cultivation space (110a) is stopped. The first spraying interruption step (S2) is performed during a rest period.

[0086] The first spray interruption stage (S2) starts at the third time point (t3), passes through the fourth time point (t4), and ends at the fifth time point (t5).

[0087] In the first spray interruption stage (S2), the opening / closing valve (40) is closed at the third point in time (t3) when the particle density reaches a preset first interruption value (d5), and the spraying of the nutrient solution is stopped.

[0088] When the nutrient solution spraying is stopped in the first spraying interruption step (S2), the particle density within the cultivation space (110a) is not measured to decrease immediately due to the size of the cultivation space (110a), the spraying pressure, the number and location of the spray nozzles, and the amount absorbed by the plants and transpired.

[0089] When the nutrient solution spraying is stopped at the first spraying interruption stage (S2), the particle density increases with a constant slope from the third time point (t3).

[0090] Therefore, the first interruption value (d5) is set to a value smaller than the upper limit (d8) by taking into account the temporary increase in particle density.

[0091] In the first spray interruption stage (S2), spray interruption continues, and the particle density no longer increases, but begins to decrease at the fourth time point (t4), which is the point in time when the particle density reaches the first maximum value (d6).

[0092] At this time, the increase in particle density between the first maximum value (d6) and the first intermediate value (d5) and the increase in time between the third time point (t3) and the fourth time point (t4) are calculated by the control unit (200).

[0093] In this case, the first maximum value (d6) may be smaller than the upper limit (d8) as shown in FIG. 4.

[0094] In the first spray interruption stage (S2), the particle density decreases from the fourth time point (t4) to the fifth time point (t5) while forming a constant slope. The fifth time point (t5) is the time when the particle density reaches the second starting value (d2).

[0095] The slope indicating a decrease in particle density in the first spraying interruption stage (S2) varies depending on the type of plant or the degree of growth. As the plant grows, that is, as the volume of the roots increases, the extra space in the cultivation space (110a) decreases and the slope shows a specific value.

[0096] Therefore, the degree of plant growth can be predicted based on the magnitude of the slope indicating a decrease in particle density in the first spray interruption stage (S2).

[0097] When the particle density reaches the second starting value (d2), the first spraying interruption step (S2) is terminated, and subsequently, a second nutrient solution spraying step (S3) is performed in which nutrient solution spraying is initiated and maintained in the cultivation space (110a). The second nutrient solution spraying step (S3) is performed during the spraying period.

[0098] In the second nutrient solution spraying step (S3), it starts at the 5th time point (t5), passes through the 6th time point (t6), and ends at the 7th time point (t7).

[0099] In the second nutrient solution spraying step (S3), the shut-off valve (40) is opened at the fifth time point (t5) when the particle density reaches the second starting value (d2), and the nutrient solution spraying is initiated through the spray nozzle (50). The second starting value (d2) is the value obtained by adding the particle density reduction amount derived in the first nutrient solution spraying step (S1) to the lower limit value (d1).

[0100] When the nutrient solution spraying is initiated in the second nutrient solution spraying step (S3), the particle density within the cultivation space (110a) is not measured to rise immediately due to the size of the cultivation space (110a), the spraying pressure, the number and location of the spray nozzles, and the amount of plant transpiration, just as in the first nutrient solution spraying step (S1).

[0101] When the nutrient solution spraying begins in the second nutrient solution spraying step (S3), the particle density decreases with a constant slope starting from the fifth time point (t5).

[0102] In the second nutrient solution spraying stage (S3), the nutrient solution spraying continues, and the particle density no longer decreases, but begins to rise at the sixth time point (t6), which is the point in time when the particle density reaches the second minimum value (d1).

[0103] At this time, the second minimum value (d1) measured approaches the lower limit (d1), and accordingly, the plant roots becoming excessively dry and causing damage to the root cells can be prevented more effectively.

[0104] Meanwhile, the amount of decrease in particle density between the second starting value (d2) and the second minimum value (d1) and the amount of increase in time between the fifth time point (t5) and the sixth time point (t6) can be derived by the control unit (200). The derived amount of decrease in particle density and the amount of increase in time can be utilized in the third nutrient solution spraying step (not shown) that is additionally performed thereafter.

[0105] Accordingly, it is possible to prevent the particle density from deviating significantly from the lower limit (d1) due to environmental changes such as day and night and the growth of crops (C).

[0106] In the second nutrient solution spraying stage (S3), the particle density increases with a constant slope from the sixth time point (t6) to the seventh time point (t7). The seventh time point (t7) is the time when the particle density reaches the second intermediate value (d7).

[0107] As in the first nutrient solution spraying step (S1), the increasing slope of the second nutrient solution spraying step (S3) provides information about the degree of plant growth or the clogging state of the nozzle according to its magnitude.

[0108] When the particle density reaches the second interruption value (d7), the second nutrient solution spraying step (S3) is terminated, and subsequently, the second spraying interruption step (S4) is performed in which the spraying of the nutrient solution in the cultivation space (110a) is stopped. The first spraying interruption step (S2) is performed during the rest period.

[0109] The second spray interruption stage (S4) starts at time 7 (t7) and goes through time 8 (t8).

[0110] In the second spray interruption stage (S4), the opening / closing valve (40) is closed at the 7th time point (t7) when the particle density reaches the second interruption value (d7), and the spraying of the nutrient solution is stopped. The second interruption value (d7) is the value obtained by subtracting the increase in particle density derived in the first spray interruption stage (S2) from the upper limit value (d8).

[0111] When the nutrient solution spraying is stopped in the second spraying interruption stage (S4), the particle density in the cultivation space (110a) is not measured to decrease immediately, just as in the first spraying interruption stage (S2).

[0112] When the nutrient solution spraying is stopped at the second spraying interruption stage (S4), the particle density increases with a constant slope from the seventh time point (t7).

[0113] In the second spray interruption stage (S4), spray interruption continues, and the particle density no longer increases, and begins to decrease at the eighth time point (t8) when the particle density reaches the second maximum value (d8).

[0114] At this time, the second maximum value (d8) measured approaches the upper limit (d8), and accordingly, droplets of nutrient solution form on the plant roots, and as a result, the plant roots can be prevented from settling in the nutrient solution.

[0115] The particle density increase between the second peak (d8) and the second interruption (d7) and the time increase between the seventh time point (t7) and the eighth time point (t8) are calculated by the control unit (200). The derived particle density increase and time increase can be utilized in a third spray interruption step (not shown) that is subsequently performed.

[0116] Accordingly, it is possible to prevent the particle density from deviating significantly from the upper limit (d8) due to environmental changes such as day and night and the growth of crops (C).

[0117] In the second spray interruption stage (S4), the particle density decreases with a constant slope from the eighth time point (t8).

[0118] The slope indicating a decrease in particle density in the second spraying interruption stage (S4) varies depending on the type of plant or the degree of growth. As the plant grows, that is, as the volume of the roots increases, the extra space in the cultivation space (110a) decreases and the slope shows a specific value.

[0119] Therefore, the degree of plant growth can be predicted based on the magnitude of the slope indicating a decrease in particle density in the second spray interruption stage (S4).

[0120] FIG. 5 illustrates a case in which, in a spray-type hydroponic cultivation method according to one embodiment of the present invention, the first starting value (d3') is set slightly smaller than the first starting value (d4) described in FIG. 4, and the first intermediate value (d6') is set slightly larger than the first intermediate value (d5) described in FIG. 4.

[0121] In this case, as illustrated in FIG. 5, the first minimum value (d1') may be smaller than the lower limit value (d2') due to the first starting value (d3') being set smaller, and the first maximum value (d8') may be larger than the upper limit value (d7') due to the first middle value (d6') being set larger.

[0122] Referring to FIG. 5, a spray hydroponic cultivation method according to one embodiment of the present invention includes a preliminary step (P'), a second nutrient solution spraying step (S3'), a first spraying interruption step (S2'), a second nutrient solution spraying step (S3'), and a second spraying interruption step (S4').

[0123] Each step corresponds to the preliminary step (P), the first nutrient solution spraying step (S1'), the first spraying interruption step (S2), the second nutrient solution spraying step (S3), and the second spraying interruption step (S4) described in FIG. 4, and the technical principles applied are the same.

[0124] The first nutrient solution spraying step (S1) begins after the preliminary step (P').

[0125] The first nutrient solution spraying step (S1') begins at a first time point (t1') when the particle density reaches a preset first starting value (d3'). Nutrient solution spraying begins simultaneously with the start of the first nutrient solution spraying step (S1'). The particle density decreases momentarily and then increases along a constant slope from a second time point (t2') when it reaches a first minimum value (d1') that is smaller than the lower limit (d2').

[0126] The first spray interruption stage (S2') begins at the third time point (t3') when the particle density reaches the first interruption value (d6'). The particle density increases momentarily and then decreases along a constant slope from the fourth time point (t4') when it reaches the first peak value (d8'), which is greater than the upper limit (d7').

[0127] The second nutrient solution spraying stage (S3') begins at the fifth time point (t5'), when the particle density reaches the second starting value (d4'). Nutrient solution spraying begins simultaneously with the start of the second nutrient solution spraying stage (S3'). The second starting value (d4') is the value obtained by adding the amount of particle density reduction from the first starting value (d3') to the first minimum value (d1') to the lower limit value (d2'). The particle density decreases momentarily and then increases along a constant slope from the sixth time point (t6'), when it reaches the second minimum value (d2'), which is nearly identical to the lower limit value (d2').

[0128] The second spray interruption stage (S4') begins at the seventh time point (t7') when the particle density reaches the second interruption value (d6'). The second interruption value (d6') is the value obtained by subtracting the increase in particle density from the first interruption value (d6') to the first peak value (d8') from the upper limit value (d7'). The particle density increases instantaneously and then decreases along a constant slope from the eighth time point (t8') when it reaches the second peak value (d7'), which is almost identical to the upper limit value (d7').

[0129] As described above, although the present invention has been explained by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0130] 1: Spray hydroponic system 10: Nutrient tank 20: Pump 30: High-pressure tank 40: Shut-off valve 100: Hydroponics Department 140: First sensor unit 150: Second sensor unit 160: Temperature control unit 200: Control unit

Claims

Claim 1 A spray-type hydroponic cultivation method in which the ratio of floating nutrient solution particles occupying a cultivation space for hydroponic cultivation is measured by a sensor unit provided in the cultivation space, and the spraying of the nutrient solution is controlled so that the measured particle ratio is within a preset range, comprising: a first nutrient solution spraying step in which the spraying of the nutrient solution proceeds in the cultivation space and the amount of decrease in the measured particle ratio is derived in a time interval from the start of spraying to the time when the measured particle ratio becomes the lowest; and a second nutrient solution spraying step performed after the first nutrient solution spraying step, wherein the start of spraying is set based on the amount of decrease in the derived particle ratio and the spraying of the nutrient solution is initiated at the set start of spraying; wherein the spraying of the nutrient solution is stopped after the end of the first nutrient solution spraying step and before the start of the second nutrient solution spraying step. Claim 2 A spray-type hydroponic cultivation method according to claim 1, wherein the second nutrient solution spraying step is characterized by setting the spraying start time as the point in time when the measured particle ratio reaches the value obtained by adding the reduction amount of the derived particle ratio to the lower limit of the preset range. Claim 3 A spray-type hydroponic cultivation method according to claim 1, characterized in that the spray pressure of the first nutrient solution spraying step and the spray pressure of the second nutrient solution spraying step are mutually identical. Claim 4 A spray-type hydroponic cultivation method according to claim 1, further comprising: a first spray interruption step performed after the end of the first nutrient solution spraying step and before the start of the second nutrient solution spraying step, wherein the spraying of the nutrient solution in the cultivation space is stopped and the increase in the measured particle ratio is derived in a time interval from the point of spray interruption to the point where the measured particle ratio reaches its maximum; and a second spray interruption step performed after the second nutrient solution spraying step, wherein the spray interruption point is set based on the derived increase in the particle ratio, and the spraying of the nutrient solution is stopped at the set spray interruption point. Claim 5 A spray-type hydroponic cultivation method according to claim 4, wherein the second spray interruption step sets the spray start time as the point in time when the measured particle ratio reaches a value obtained by subtracting the increase in the derived particle ratio from the upper limit of the preset range.

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