Plant cultivation device and plant cultivation method

Abstract

This plant cultivation device comprises: at least one cultivation space in which a ground part of at least one plant is grown; at least one artificial light source that is disposed in the vicinity of the cultivation space and emits artificial light for growing plants; a heat shield partition wall that is formed from a light-transmissive material and is interposed between the cultivation space and the artificial light source; and a movement control device that moves the artificial light source relative to the cultivation space. The movement control device creates a state in which the plant in the cultivation space is irradiated with the artificial light output from the artificial light source, and a state in which the plant in the cultivation space is not irradiated with the artificial light output from the artificial light source.

Description

Plant growing device and plant growing method

[0001] The present invention relates to a plant growing device and a plant growing method for growing plants using artificial light.

[0002] Plant factories have been considered as a measure to increase agricultural production and realize stable harvests. In plant factories, the intensity of light irradiated on crops from an artificial light source for photosynthesis, the temperature, humidity, and carbon dioxide (CO ) in the plant growing space are controlled. ２ It is possible to control various parameters, such as the concentration of nitrogen, wind speed, and other environmental conditions, as well as fertilizer components for plant growth. This makes it possible to produce crops year-round, dramatically increasing crop productivity.

[0003] Patent Document 1 discloses a plant growing device that includes a light source that emits light downward and a light-transmitting heat insulating section that separates the space on the light source side from the space on the aboveground side. The heat insulating section prevents the heat emitted by the light source from directly reaching the plants.

[0004] International Publication No. 2017 / 047024

[0005] Plants grow during the day through photosynthesis, but also at night. Continuous exposure to light can reduce photosynthetic function and inhibit growth. Furthermore, continuous exposure to light can prevent some plants from flowering. In a plant growing device, it is preferable to provide periods of light exposure to promote photosynthesis, while providing periods of no light exposure to guide plant growth appropriately. It is also preferable that the plants are not overheated by the light provided.

[0006] Therefore, the present invention provides a plant growing device and a plant growing method that can set periods when plants are irradiated with artificial light and periods when they are not, thereby preventing the plants from overheating.

[0007] One aspect of the present invention provides a plant growing device comprising: at least one growing space in which the above-ground portion of at least one plant is grown; at least one artificial light source disposed near the growing space and emitting artificial light for growing the plant; a heat-shielding partition wall made of a light-transmitting material and interposed between the growing space and the artificial light source; and a movement control device that moves the artificial light source relative to the growing space so as to create a state in which the plant in the growing space is irradiated with the artificial light output from the artificial light source and a state in which the plant in the growing space is not irradiated with the artificial light output from the artificial light source.

[0008] Another aspect of the present invention provides a plant cultivation method for cultivating a plant using the plant cultivation device described above, the plant cultivation method comprising: the movement control device moving the artificial light source relative to the cultivation space to create a state in which the plant in the cultivation space is illuminated with artificial light output from the artificial light source and a state in which the plant in the cultivation space is not illuminated with artificial light output from the artificial light source.

[0009] According to an aspect of the present invention, the heat-shielding partition wall thermally separates the growing space from the artificial light source and makes it less susceptible to the heat. In other words, the heat-shielding partition wall prevents the growing space from overheating. Therefore, the energy required to control the air temperature in the growing space can be reduced, and the growing space can be easily controlled to an environment suitable for the plants being grown. Furthermore, by moving the artificial light source relative to the growing space using a movement control device, it is possible to create periods in which the plants in the growing space are illuminated by artificial light (periods corresponding to daytime) and periods in which they are not illuminated (periods corresponding to nighttime).

[0010] 1 is a front cross-sectional view showing a schematic configuration example of a plant growing device according to a first embodiment of the present invention. FIG. 1 is a front view of a light source panel of the plant growing device of FIG. 1. FIG. 2 is a longitudinal cross-sectional view of a light source panel according to a modified example. FIG. 1 is a plan cross-sectional view of the plant growing device of FIG. 1. FIG. 5 is a plan cross-sectional view of the plant growing device of FIG. 5 in which a pair of light source panels have been moved. FIG. 6 is a plan cross-sectional view of a plant growing device according to a modified example in which a plurality of growing spaces have been moved. FIG. 7 is a plan cross-sectional view of a plant growing device according to a modified example of the first embodiment. FIG. 8 is a plan cross-sectional view of the plant growing device of FIG. 8 in which a pair of light source panels and a pair of heat-shielding partition walls have been moved. FIG. 9 is a plan cross-sectional view of a plant growing device according to another modified example of the first embodiment. FIG. 10 is a plan cross-sectional view of the plant growing device of FIG. 10 in which a pair of light source panels have been moved. FIG. 11 is a plan cross-sectional view of a plant growing device according to another modified example of the first embodiment. FIG. 12 is a plan cross-sectional view of a plant growing device according to yet another modified example of the first embodiment. FIG. 13 is a plan cross-sectional view of the plant growing device of FIG. 13 in which a pair of light source panels have been moved. FIG. 14 is a plan cross-sectional view of the plant growing device of FIG. 13 in which two pairs of light source panels have been moved. FIG. 15 is a plan cross-sectional view of a plant growing device according to yet another modified example of the first embodiment. FIG. 16 is a plan cross-sectional view of the plant growing device of FIG. 16 in which a pair of light source panels have been moved. 16 in which two pairs of light source panels have been moved. FIG. 17 is a front cross-sectional view showing a schematic configuration example of a plant growing device according to a second embodiment of the present invention. FIG. 18 is a side cross-sectional view of the plant growing device of FIG. 19. FIG. 19 is a front cross-sectional view showing a schematic configuration example of a plant growing device according to a third embodiment of the present invention. FIG. 21 is a plan cross-sectional view of the plant growing device of FIG. 22 in which a pair of light source panels have been moved. FIG. 22 is a plan cross-sectional view of a plant growing device according to a modified example in which a plurality of growing spaces have been moved. FIG. 23 is a plan cross-sectional view of a plant growing device according to a modified example of the third embodiment. FIG. 24 is a plan cross-sectional view of the plant growing device of FIG. 25 in which a pair of light source panels have been moved. FIG. 24 is a plan cross-sectional view of a plant growing device according to another modified example of the third embodiment. FIG. 25 is a plan cross-sectional view of a plant growing device according to yet another modified example of the third embodiment. FIG. 26 is a plan cross-sectional view of the plant growing device of FIG. 28 in which a pair of light source panels have been moved. FIG. 26 is a plan cross-sectional view of the plant growing device of FIG. 28 in which two pairs of light source panels have been moved. FIG. 26 is a plan cross-sectional view of a plant growing device according to yet another modified example of the third embodiment.FIG. 32 is a plan cross-sectional view of the plant growing device of FIG. 31 with two pairs of light source panels moved. FIG. 33 is a front cross-sectional view showing a schematic configuration example of a plant growing device according to a fourth embodiment of the present invention. FIG. 34 is a side cross-sectional view of the plant growing device of FIG. 34. FIG. 35 is a plan view of a plant growing device according to a fifth embodiment of the present invention. FIG. 36 is a front cross-sectional view of the plant growing device of FIG. 36. FIG. 37 is an exploded cross-sectional view of the plant growing device of FIG. 36. FIG. 37 is a front cross-sectional view of the plant growing device of FIG. 36 immediately after assembly. FIG. 38 is a front cross-sectional view of the plant growing device of FIG. 36 disassembled for removing a plant at a grown stage. FIG. 39 is a front cross-sectional view showing air flow in the plant growing device of FIG. 36.

[0011] Various embodiments of the present invention will now be described with reference to the accompanying drawings, in which the drawings are not necessarily to scale and some features may be exaggerated or omitted.

[0012] As shown in Figure 1, the plant cultivation device 1 according to the first embodiment has a cultivation device 2 for cultivating a large number of plants. The plant cultivation device 1 is arranged in a plant factory. The plants 3 cultivated in the plant cultivation device 1 are, for example, agricultural crops such as beans, but may also be other plants that perform photosynthesis. The plant cultivation device 1 according to the first embodiment is preferably used for plants that, as they grow, have long trunks and many leaves that overlap vertically. The large number of plants 3 are arranged in a direction perpendicular to the plane of the paper in Figure 1 (see Figures 5 and 6).

[0013] The cultivation device 2 has an upper part 2A and a lower part 2B arranged below the upper part 2A. A lower housing 2C is provided in the lower part 2B. The lower housing 2C has a peripheral wall and a bottom wall that define a lower space 2D, and its top is open. At least one liquid fertilizer tank 4 is arranged inside the lower housing 2C. When multiple liquid fertilizer tanks 4 are provided, the liquid fertilizer tanks 4 are lined up in the direction perpendicular to the plane of the paper in Fig. 1 (see liquid fertilizer tanks 4A and 4B in Figs. 10 and 11).

[0014] The roots (including the main root and lateral roots) of the plants 3 are placed inside the liquid fertilizer tank 4, where the roots grow. The liquid fertilizer tank 4 is a container that contains a nutrient solution 41 (also called liquid fertilizer or liquid fertilizer) that contains fertilizer to be applied to the roots of the plants 3.

[0015] A plant support panel 5 is attached to the top of the liquid fertilizer tank 4. The trunks of multiple plants 3 pass through the plant support panel 5, and the plant support panel 5 supports these plants 3. The plant support panel 5 may be breathable. For example, the plant support panel 5 may be porous, or may have a large number of through-holes.

[0016] The plant growing device 1 further includes a nutrient solution supply system 10. The nutrient solution supply system 10 is connected to the liquid fertilizer tank 4 via a liquid fertilizer pipeline 11, and the nutrient solution supply system 10 supplies nutrient solution 41 to the liquid fertilizer tank 4.

[0017] Two growing spaces 6A, 6B are arranged in the upper part 2A. The growing spaces 6A, 6B are spaces above the liquid fertilizer tank 4. The growing spaces 6A, 6B are arranged close to each other in the direction perpendicular to the plane of FIG. 1 (see FIGS. 5 and 6). In each of the growing spaces 6A, 6B, the above-ground portion (i.e., stems and leaves) of at least one plant 3 grows (is cultivated). In this embodiment, the above-ground portions of multiple plants 3 grow in each of the growing spaces 6A, 6B.

[0018] Additionally, a pair of light source units 7 are disposed in the upper portion 2A. The growth spaces 6A, 6B are interposed between these light source units 7. In other words, each light source unit 7 is disposed near one of the growth spaces 6A, 6B. Each light source unit 7 has a light source panel (artificial light source) 7a and a transparent heat-shielding case 7b surrounding the light source panel 7a. The pair of light source panels 7a are oriented vertically, arranged parallel to each other, and facing each other. The pair of heat-shielding cases 7b surrounding the light source panels 7a are also oriented vertically, arranged parallel to each other.

[0019] Each light source panel 7a emits artificial light L for growing the plants 3. The light source units 7 are arranged on both sides of the growth spaces 6A, 6B, and the light source panels 7a supply artificial light L from the sides to the plants 3 in the growth spaces 6A, 6B. Therefore, the artificial light L can be applied as evenly as possible to both the upper and lower leaves of the plants 3 in the growth stage when the stems are long and the plants have many leaves overlapping in the vertical direction.

[0020] In this embodiment, a pair of light source units 7 are arranged on both sides of the growing spaces 6A, 6B, but one light source unit 7 may be arranged on one side of the growing spaces 6A, 6B. The pair of light source panels 7a are arranged so as to be shared by the plurality of growing spaces 6A, 6B and supply artificial light L to the growing spaces 6A, 6B. However, the growing spaces 6A, 6B use these light source panels 7a in a time-division manner (i.e., at different periods).

[0021] Each heat-shielding case 7b is formed from a light-transmitting material, such as glass or a transparent resin. Examples of usable transparent resins include, but are not limited to, acrylic, polyethylene terephthalate, polycarbonate, and polyvinyl chloride. Each heat-shielding case 7b has a heat-shielding partition wall 7c interposed between the growth spaces 6A, 6B and the light source panel 7a. The heat-shielding partition wall 7c is formed flat, and the heat-shielding partition walls 7c of a pair of heat-shielding cases 7b are arranged parallel to each other. As shown in FIGS. 5 and 6 , each heat-shielding case 7b has a length equal to or greater than the total length of the multiple growth spaces 6A, 6B. Each heat-shielding case 7b is disposed near the multiple growth spaces 6A, 6B and extends along the multiple growth spaces 6A, 6B. Each heat-shielding partition wall 7c also has a length equal to or greater than the total length of the multiple growth spaces 6A, 6B. Each heat-shielding partition wall 7c is disposed near the multiple growth spaces 6A, 6B and extends along the multiple growth spaces 6A, 6B. Each heat-shielding case 7b suppresses or inhibits heat radiation and heat conduction from the light source panel 7a, which is a heat source, to prevent overheating of the growing spaces 6A and 6B. In this embodiment, each heat-shielding case 7b surrounds the entire light source panel 7a. However, the heat-shielding case 7b does not necessarily have to surround the entire light source panel 7a. For example, the upper and lower walls of the heat-shielding case 7b may be omitted, or the outer wall opposite the heat-shielding partition wall 7c may be omitted. Furthermore, the heat-shielding case 7b does not have to be transparent except for the heat-shielding partition wall 7c, which is interposed between the light source panel 7a and the growing spaces 6A and 6B and allows artificial light L to enter the growing spaces 6A and 6B.

[0022] To prevent overheating of each heat-shielding case 7b and the light source panels 7a therein, a blower (not shown) may be used to generate airflow within each heat-shielding case 7b, thereby cooling the heat-shielding case 7b with air. Instead of or in addition to the blower, a refrigerant pipe or refrigerant chamber (not shown) may be disposed near each heat-shielding case 7b (e.g., in contact with each heat-shielding case 7b) to lower the temperature of each heat-shielding case 7b. The refrigerant may be, for example, a gas such as air or a hydrofluorocarbon, or a liquid such as water or ammonia. The refrigerant pipe or refrigerant chamber is preferably provided on the side of the heat-shielding case 7b opposite the heat-shielding partition wall 7c. Fins (not shown) may be provided on the wall of each heat-shielding case 7b opposite the heat-shielding partition wall 7c to improve cooling efficiency. The interior of each heat-shielding case 7b may be evacuated to efficiently suppress heat conduction from the light source panels 7a. In this case, the refrigerant pipe or refrigerant chamber and / or fins are preferably provided.

[0023] The distance Z between the pair of light source units 7 (i.e., the distance between the heat-shielding partition walls 7c of the pair of heat-shielding cases 7b) is set to a size that allows artificial light L to be applied substantially uniformly and sufficiently to each leaf of the plant 3 that has grown to a certain extent. However, it is preferable that the distance Z between the light source units 7 is set so as to restrict excessive lateral growth of the plant 3. That is, it is preferable that the position of the heat-shielding partition walls 7c relative to the plant 3 is determined (the heat-shielding partition walls 7c are arranged relative to the growth spaces 6A and 6B) so that the heat-shielding partition walls 7c restrict the growth of the leaves of the plant 3 cultivated inside the growth spaces 6A and 6B in a direction toward the light source panel 7a. Specifically, it is preferable that the horizontal distance from the base of the plant 3 to the heat-shielding case 7b be set shorter than the maximum horizontal distance from the base of the plant 3 that is predicted to be reached by the tip of a leaf that has grown to its maximum extent if the heat-shielding case 7b were not present. In this case, the heat-shielding partition wall 7c restricts excessive growth of the leaves of the plant 3, so that the plant 3 can be grown in a small space (small width).

[0024] The plant growing device 1 further includes an air conditioning system 12, a light emission control device 18, an environmental control device 20, and a movement control device 30. The air conditioning system 12 adjusts the environment of the cultivation device 2 in which the plants are grown to a temperature, humidity, and carbon dioxide (CO ) suitable for plant growth. ２ ) concentration. The air conditioning system 12 is connected to the lower housing 2C via an air pipe 14 and communicates with a lower space 2D inside the lower housing 2C. The air conditioning system 12 also communicates with the growing spaces 6A and 6B via an air pipe 16. The air conditioning system 12 supplies the conditioned air to the cultivation apparatus 2 via the air pipe 14 or 16 and takes in air from the interior of the cultivation apparatus 2 via the air pipe 16 or 14. There are multiple ventilation gaps 40 between the lower housing 2C of the lower part 2B of the cultivation apparatus 2 and the liquid fertilizer tank 4. The air conditioned by the air conditioning system 12 can flow through these ventilation gaps 40 from the upper part 2A (growing spaces 6A and 6B) of the cultivation apparatus 2 to the lower part 2B (lower space 2D) or from the lower part 2B to the upper part 2A.

[0025] The light-emitting control device 18 controls the light emission of the light source panel 7a of the light source unit 7. For example, the light-emitting control device 18 turns the light source panel 7a on and off. The environmental control device 20 is a computer processor. The environmental control device 20 controls the internal environment of the cultivation apparatus 2. As described below, the environmental control device 20 issues commands to the nutrient solution supply system 10 and the air conditioning system 12 to alternately control the cultivation spaces 6A, 6B between an environment that promotes plant photosynthesis and an environment that suppresses photosynthesis. The movement control device 30 is also a computer processor. The movement control device 30 may be a processor separate from the environmental control device 20 or may be the same processor as the environmental control device 20. As described below, the movement control device 30 controls a movement mechanism (not shown) to move the light source panel 7a relative to the cultivation spaces 6A, 6B. The cultivation apparatus 2 has a movement mechanism that moves the light source panel 7a relative to the cultivation spaces 6A, 6B. The movement mechanism may be, for example, a wheel driven by a motor, a belt conveyor mechanism, a caterpillar mechanism, or a rack and pinion mechanism.

[0026] As shown in FIG. 2 , the light source panel 7a has a height X that is greater than the upper limit of the growth height of the plants 3 and a width Y that allows artificial light L to be applied uniformly and sufficiently to multiple plants 3 planted at intervals. The light source of the light source panel 7a may be, for example, multiple organic light-emitting diode (OLED) elements. However, in this embodiment, multiple light-emitting diode (LED) chips that generate less heat are used. As shown in FIGS. 2 and 3 , the light source panel 7a includes a flat substrate 32 as a support and multiple LED chips 33 arranged on the substrate 32. These LED chips 33 are of the same type and emit white visible light. Therefore, when the same current and voltage are applied, these LED chips 33 emit artificial light L with the same photon flux density. The LED chips 33 are arranged regularly (specifically, in a matrix) at equal intervals vertically and horizontally. However, LED chips 33 that emit red wavelength light more strongly than other wavelengths and LED chips 33 that emit blue wavelength light more strongly than other wavelengths may also be arranged on the substrate 32. Additionally, LED chips 33 that emit green wavelength light more strongly than light of other wavelengths may be arranged on the substrate 32. The LED chips 33 are mounted in a light-emitting region of the light source panel 7a, which has a height X1 and a width Y1.

[0027] The substrate 32 is provided with wiring (not shown) for lighting the LED chips 33. A light-emitting control device 18 (see FIG. 1) for controlling the light emission of the LED chips 33 is provided outside the light source panel 7a, and the wiring is electrically connected to the light-emitting control device 18. To increase the efficiency of utilization of the artificial light L within the cultivation spaces 6A and 6B, the surface of the substrate 32 facing the LED chips 33 preferably has high light reflectivity. The substrate 32 is preferably formed from a light-reflecting material (e.g., a metal with a smooth surface). The surface of the substrate 32 facing the LED chips 33 may be coated with a light-reflective paint. The light source panel 7a shown in FIGS. 2 and 3 is merely an example. The size, number, and spacing of the LED chips 33 are not limited to those shown. In this embodiment, the substrate 32 of the light source panel 7a is a flat plate, but as shown in FIG. 4, the substrate 32 may also be a corrugated plate. FIG. 4 is a longitudinal cross-sectional view of the light source panel 7a viewed similarly to FIG. 3.

[0028] In this embodiment, the artificial light source is a light source panel 7a having a plurality of low-heat-generating LED chips 33. However, the artificial light source may be at least one fluorescent lamp, at least one cold cathode fluorescent tube, or other light sources.

[0029] As shown in the plan cross-sectional views of Figures 5 and 6, the liquid fertilizer tank 4 is a long container, and a plurality of plants 3 are lined up along the longitudinal direction of the liquid fertilizer tank 4. The light source unit 7 and the growing spaces 6A, 6B extend along the longitudinal direction of the liquid fertilizer tank 4. In this embodiment, as shown in Figures 5 and 6, the heat-shielding case 7b of each light source unit 7 has a length equal to or greater than the combined length of the growing spaces 6A, 6B. Therefore, in this embodiment, the growing spaces 6A, 6B are spaces arranged above the single liquid fertilizer tank 4 and the single lower housing 2C, and are spaces interposed between the pair of light source units 7.

[0030] A light-shielding wall 50 is interposed between the growing spaces 6A and 6B. In other words, the light-shielding wall 50 divides the growing spaces 6A and 6B. In this embodiment, the pair of heat-shielding cases 7b and the light-shielding wall 50 define the growing spaces 6A and 6B. To increase the efficiency of using the artificial light L in the growing spaces 6A and 6B, it is preferable that both surfaces of the light-shielding wall 50 have a high light reflectivity. It is preferable that the light-shielding wall 50 is formed from a light-reflecting material (for example, a metal with smooth surfaces). Both surfaces of the light-shielding wall 50 may be coated with a light-reflective paint.

[0031] In this embodiment, the lower housing 2C, the liquid fertilizer tank 4, and the heat-shielding case 7b are fixed. The growing spaces 6A and 6B above the liquid fertilizer tank 4 are stationary (i.e., fixed) in fixed positions. As described above, the movement control device 30 controls a movement mechanism (not shown) to move the light source panel 7a relative to the growing spaces 6A and 6B. The movement control device 30 reciprocates the light source panel 7a of each light source unit 7 along the longitudinal direction of the liquid fertilizer tank 4 (the longitudinal direction of the growing spaces 6A and 6B). In other words, while the heat-shielding case 7b is stationary relative to the growing spaces 6A and 6B, the movement control device 30 moves the light source panel 7a inside the heat-shielding case 7b. The movement control device 30 synchronously moves the light source panels 7a of a pair of light source units 7.

[0032] FIG. 5 shows a state in which a pair of light source panels 7a are positioned on the cultivation space 6A side and irradiate artificial light onto the plant 3 in the cultivation space 6A. In this state, artificial light is not irradiated onto the plant 3 in the cultivation space 6B. In other words, the cultivation space 6A is in a daytime state, and the cultivation space 6B is in a nighttime state. The light-shielding wall 50 prevents artificial light from traveling from the cultivation space 6A to the cultivation space 6B. Therefore, a state in which the plant in the cultivation space 6A is irradiated with artificial light output from the light source panel 7a and a state in which the plant in the cultivation space 6B is not irradiated with artificial light output from the light source panel 7a are simultaneously created. On the other hand, FIG. 6 shows a state in which a pair of light source panels 7a are positioned on the cultivation space 6B side and irradiate artificial light onto the plant 3 in the cultivation space 6B. In this state, artificial light is not irradiated onto the plant 3 in the cultivation space 6A. In other words, the cultivation space 6B is in a daytime state, and the cultivation space 6A is in a nighttime state. The light-shielding wall 50 prevents artificial light from traveling from the cultivation space 6B to the cultivation space 6A. Therefore, a state in which the plants inside the cultivation space 6B are illuminated with artificial light output from the light source panel 7a and a state in which the plants inside the cultivation space 6A are not illuminated with artificial light output from the light source panel 7a are simultaneously created.

[0033] The movement control device 30 may, for example, move the light source panel 7a from the vicinity of one of the growing spaces 6A, 6B to the vicinity of the other in a 12-hour cycle. In this case, in each of the growing spaces 6A, 6B, 12 hours of the day are daylight and the other 12 hours are night. However, the movement control device 30 may move the light source panel 7a from one of the growing spaces 6A, 6B to the other in other cycles. For example, the light source panel 7a may be moved from one of the growing spaces 6A, 6B to the other in a 6-hour cycle, a 4-hour cycle, or a 3-hour cycle. In any case, in each of the growing spaces 6A, 6B, a total of 12 hours of the day are daylight and a total of 12 hours are night.

[0034] According to this embodiment, the heat-shielding case 7b thermally isolates the growing spaces 6A, 6B from the light source panel 7a, making them less susceptible to the heat. In other words, the heat-shielding case 7b prevents the growing spaces 6A, 6B from overheating. This reduces the energy required by the air-conditioning system 12 to control the air temperature in the growing spaces 6A, 6B, making it easier to maintain the growing spaces 6A, 6B in an environment suitable for the plants being grown.

[0035] Furthermore, by moving the light source panel 7a relative to the growing spaces 6A and 6B using the movement control device 30, it is possible to simultaneously create a state in which plants in one of the growing spaces 6A and 6B are illuminated with artificial light (a state corresponding to daytime) and a state in which plants in the other of the growing spaces 6A and 6B are not illuminated (a state corresponding to nighttime). It is also possible to alternate between growing spaces illuminated with artificial light and those not illuminated with artificial light. That is, by sharing the light source panel 7a between multiple growing spaces 6A and 6B and using the light source panel 7a in a time-division manner (i.e., at different periods), it is possible to simultaneously place one of the growing spaces 6A and 6B in an environment illuminated with artificial light and the other of the growing spaces 6A and 6B in an environment not illuminated with artificial light. By switching between growing spaces illuminated with artificial light and those not illuminated with artificial light, it is possible to alternate between periods in which plants in each growing space are illuminated with artificial light and periods in which they are not illuminated with artificial light. Because multiple growing spaces 6A and 6B share the light source panel 7a, the number of light source panels 7a does not need to correspond to the number of growing spaces 6A and 6B. In this embodiment, the light source units 7 are arranged on both sides of the two growing spaces 6A, 6B, and each light source unit 7 has a single light source panel 7a. It is not necessary for each light source unit 7 to have two light source panels 7a corresponding to the two growing spaces 6A, 6B. This prevents an increase in the number of light source panels 7a.

[0036] Furthermore, because the light source panel 7a is used by the multiple cultivation spaces 6A, 6B in a time-sharing manner, the light source panel 7a can be continuously driven. This reduces the number of times the light source panel 7a is turned on and off, shortening the period during which the light source panel 7a is not in use. Furthermore, when the artificial light source is a fluorescent lamp or a cold cathode fluorescent tube, this reduces malfunctions caused by on-off switching and saves power consumption. However, the light source panel 7a does not need to be driven continuously. Many types of plants flower by sensing changes in photoperiod. Therefore, even when the light source panel 7a is moved from the vicinity of one of the cultivation spaces 6A, 6B to the vicinity of the other in a 12-hour cycle, for example, an off period during which the light source panel 7a does not emit light may be provided to accommodate the change in photoperiod.

[0037] The movement control device 30 moves the light source panel 7a in the heat-shielding case 7b along the longitudinal direction of the fixed growing spaces 6A, 6B, without moving the heat-shielding case 7b. However, as shown in a modified example in FIG. 7 , the movement control device 30 may move the heat-shielding case 7b along the longitudinal direction of the growing spaces 6A, 6B together with the growing spaces 6A, 6B, without moving the light source panel 7a. In this modified example, the state shown in FIG. 5 , in which the light source panel 7a is located on the growing space 6A side, can be transitioned to the state shown in FIG. 7 , in which the light source panel 7a is located on the growing space 6B side and artificial light is irradiated onto the plants 3 in the growing space 6B. The state shown in FIG. 7 is equivalent to the state shown in FIG. 6 , in which the growing space 6B is in a daytime state and the growing space 6A is in a nighttime state. In this modified example, the liquid fertilizer pipe 11 and the air pipes 14, 16 are preferably extendable and bendable. In either case, the movement control device 30 moves the light source panel 7a relative to the growing spaces 6A, 6B while the heat-shielding case 7b remains stationary relative to the growing spaces 6A, 6B. In this embodiment, the heat-shielding case 7b has a length equal to or greater than the combined length of the growing spaces 6A, 6B. Therefore, the heat-shielding case 7b does not collide with or slide against the plants 3 inside the growing spaces 6A, 6B, and does not cause damage to the plants 3 due to impact or friction. Furthermore, as described above, if the position of the heat-shielding partition 7c relative to the plants 3 is determined so that the heat-shielding partition 7c restricts the lateral growth of the leaves of the plants 3 cultivated inside the growing spaces 6A, 6B, the plants 3 can be grown in a small space (small width).

[0038] 8 and 9 are plan cross-sectional views of a plant growing device 1A according to another modification of the first embodiment. In this modification, the movement control device 30 moves a pair of light source panels 7a and a pair of heat-shielding cases 7b together along the longitudinal direction of the fixed growing spaces 6A, 6B. In each light source unit 7, the heat-shielding case 7b is shorter than the heat-shielding case 7b shown in FIGS. 5 to 7, and the light source panel 7a is fixed within the heat-shielding case 7b. The movement control device 30 synchronously moves the pair of light source units 7, each including a light source panel 7a and a heat-shielding case 7b.

[0039] FIG. 8 shows a state in which a pair of light source panels 7a are positioned on the cultivation space 6A side and irradiate artificial light onto the plant 3 in the cultivation space 6A. In this state, artificial light is not irradiated onto the plant 3 in the cultivation space 6B. In other words, the cultivation space 6A is in a daytime state, and the cultivation space 6B is in a nighttime state. The shading wall 50 prevents artificial light from traveling from the cultivation space 6A to the cultivation space 6B. Therefore, a state in which the plant in the cultivation space 6A is irradiated with artificial light output from the light source panel 7a and a state in which the plant in the cultivation space 6B is not irradiated with artificial light output from the light source panel 7a are simultaneously created. On the other hand, FIG. 9 shows a state in which a pair of light source panels 7a are positioned on the cultivation space 6B side and irradiate artificial light onto the plant 3 in the cultivation space 6B. In this state, artificial light is not irradiated onto the plant 3 in the cultivation space 6A. In other words, the cultivation space 6B is in a daytime state, and the cultivation space 6A is in a nighttime state. The shading wall 50 prevents artificial light from traveling from the cultivation space 6B to the cultivation space 6A. Therefore, a state in which the plants inside the cultivation space 6B are illuminated with artificial light output from the light source panel 7a and a state in which the plants inside the cultivation space 6A are not illuminated with artificial light output from the light source panel 7a are simultaneously created.

[0040] Although not shown, the movement control device 30 may move the growing spaces 6A, 6B along the longitudinal direction of the growing spaces 6A, 6B without moving the light source panel 7a and the heat shield case 7b.

[0041] Similarly to the above, the movement control device 30 may move the light source panel 7a from the vicinity of one of the growing spaces 6A, 6B to the vicinity of the other, for example, in a 12-hour cycle. However, the movement control device 30 may move the light source panel 7a from one of the growing spaces 6A, 6B to the other in a different cycle. Since the multiple growing spaces 6A, 6B use the light source panel 7a in a time-sharing manner, the light source panel 7a can be continuously driven. Therefore, the number of times the light source panel 7a is switched on and off can be reduced. However, an off period during which the light source panel 7a does not emit light may be provided to change the photoperiod.

[0042] 8 and 9, the heat-shielding case 7b does not need to have a length equivalent to the total length of the plurality of growing spaces 6A, 6B. Therefore, the heat-shielding case 7b can be made smaller. Furthermore, since the heat-shielding case 7b and the light source panel 7a are moved together, the structure of the movement mechanism can be simplified if the heat-shielding case 7b is configured to surround the light source panel 7a.

[0043] In the first embodiment and the above-described modified examples, multiple growing spaces 6A, 6B are provided above a single liquid fertilizer tank 4 and a single lower housing 2C. However, as in the modified plant growing device 1B shown in FIGS. 10 and 11 , multiple growing spaces 6A, 6B may be provided above multiple liquid fertilizer tanks 4A, 4B, respectively. The liquid fertilizer tanks 4A, 4B are arranged inside separate lower housings 2C (i.e., separate lower spaces 2D) arranged adjacent to each other. In this case, the plant growing device 1B includes a combination of a growing space 6A where the above-ground parts of the plants grow and a liquid fertilizer tank 4A directly below it where the roots of the plants 3 grow, and a growing space 6B and a liquid fertilizer tank 4B directly below it. The combination of the growing space 6A and the liquid fertilizer tank 4A and the combination of the growing space 6B and the liquid fertilizer tank 4B are isolated from each other and can be considered independent cultivation units. Therefore, the environmental control device 20 (see FIG. 1 ) can easily place the combination of the growing space 6A and the liquid fertilizer tank 4A and the combination of the growing space 6B and the liquid fertilizer tank 4B in different environments.

[0044] In Fig. 10, a pair of light source panels 7a are positioned on the growing space 6A side, the growing space 6A is in a daytime state, and the growing space 6B is in a nighttime state. In Fig. 11, a pair of light source panels 7a are positioned on the growing space 6B side, the growing space 6B is in a daytime state, and the growing space 6A is in a nighttime state.

[0045] The environmental control device 20 controls the growth space 6A or 6B, to which the light source panel 7a irradiates visible light, to an environment that promotes photosynthesis of the plants 3, and controls the growth space 6A or 6B, to which the light source panel 7a does not irradiate visible light, to an environment that suppresses photosynthesis of the plants 3. That is, during a period when artificial light is supplied from the light source panel 7a to the growth space 6A shown in FIG. 10 and artificial light is not supplied to the growth space 6B, the combination of the growth space 6A and the liquid fertilizer tank 4A is controlled to an environment that promotes photosynthesis of the plants 3. At the same time, the combination of the growth space 6B and the liquid fertilizer tank 4B is controlled to an environment that suppresses photosynthesis of the plants 3. Conversely, during a period when artificial light is supplied from the light source panel 7a to the growth space 6B shown in FIG. 11 and artificial light is not supplied to the growth space 6A, the combination of the growth space 6B and the liquid fertilizer tank 4B is controlled to an environment that promotes photosynthesis of the plants 3. At the same time, the combination of the growth space 6A and the liquid fertilizer tank 4A is controlled to an environment that suppresses photosynthesis of the plants 3. In other words, photosynthesis is promoted in the cultivation space 6A or 6B corresponding to the daytime and the liquid fertilizer tank 4A or 4B corresponding to that cultivation space, while photosynthesis is suppressed in the cultivation space 6A or 6B corresponding to the nighttime and the liquid fertilizer tank 4A or 4B corresponding to that cultivation space.

[0046] Specifically, the environmental control device 20 performs at least one of the following examples of environmental control. In one example of environmental control, the environmental control device 20 controls the air conditioning system 12 to increase the temperature of the cultivation space 6A or 6B corresponding to the daytime and the liquid fertilizer tank 4A or 4B corresponding to that cultivation space. At the same time, the environmental control device 20 controls the air conditioning system 12 to decrease the temperature of the cultivation space 6A or 6B corresponding to the nighttime and the liquid fertilizer tank 4A or 4B corresponding to that cultivation space. This reduces the operating cost of the cultivation unit corresponding to the nighttime. It also suppresses the metabolism of the plants 3 in the cultivation unit corresponding to the nighttime. In another example of environmental control, the environmental control device 20 controls the air conditioning system 12 to decrease the CO in the air in the cultivation space 6A or 6B corresponding to the daytime. ２ The concentration of CO in the air in the growth space 6A or 6B corresponding to nighttime is increased. ２ Therefore, the operating cost of the cultivation unit during the night can be reduced.

[0047] In another example of environmental control, the environmental control device 20 may control the air conditioning system 12 to appropriately control the humidity in the cultivation space 6A or 6B corresponding to the daytime, but may not control the humidity in the cultivation space 6A or 6B corresponding to the nighttime. When the humidity is high, a lot of water vapor passes through the stomata of the leaves of the plants, and the plants can absorb CO ２ When water droplets get on the leaves, the stomata close and the plant cannot absorb CO ２ In addition, high humidity reduces transpiration from the stomata of the leaves, inhibiting plant growth. On the other hand, if humidity is too low, plants' photosynthetic ability decreases due to drought stress, so there is an optimum range for daytime humidity. When the external environment of the cultivation device 2 is highly humid, humidity control only needs to be performed in the cultivation unit corresponding to the daytime, thereby reducing the operating costs of the cultivation unit corresponding to the nighttime.

[0048] In another example of environmental control, the environmental control device 20 controls the nutrient solution supply system 10 to increase the amount of top dressing (specifically, the concentration of fertilizer) supplied to the liquid fertilizer tank 4A or 4B corresponding to the cultivation space 6A or 6B corresponding to the daytime. At the same time, the environmental control device 20 controls the nutrient solution supply system 10 to decrease the amount of top dressing supplied to the liquid fertilizer tank 4A or 4B corresponding to the cultivation space 6A or 6B corresponding to the nighttime. This reduces the operating costs of the cultivation unit corresponding to the nighttime.

[0049] The environmental control has been described in relation to the modified example shown in Figures 10 and 11, which has liquid fertilizer tanks 4A and 4B dedicated to the cultivation spaces 6A and 6B, respectively. However, the above-mentioned environmental control (control using the air conditioning system 12), excluding the control of the amount of top dressing, may also be implemented in the embodiment and modified example in which a single liquid fertilizer tank 4 is shared by the cultivation spaces 6A and 6B. In this case, it is preferable that air circulation between the upper part 2A (cultivation spaces 6A and 6B) and the lower part 2B (lower space 2D) of the cultivation device 2 is blocked. For example, it is preferable that the ventilation gap 40 (see Figure 1) is not present. This makes it difficult for the air inside the cultivation spaces 6A and 6B to mix. The environmental control device 20 uses the air conditioning system 12 to individually control the temperature and CO2 of the cultivation spaces 6A and 6B. ２ The concentration and / or humidity can be controlled.

[0050] In the first embodiment and the above-described modified examples, each light source unit 7 has a single light source panel 7a. However, each light source unit 7 may have multiple light source panels 7a. For example, in a modified plant cultivation device 1C shown in FIG. 12, each light source unit 7 has two light source panels 7a enclosed in a single elongated heat-shielding case 7b. The light source panels 7a are aligned along the longitudinal direction of the cultivation spaces 6A, 6B. The upper portion 2A of the cultivation device 2 has four cultivation spaces 6A, 6B aligned along one direction. Specifically, the cultivation device 2 has two cultivation spaces 6A and two cultivation spaces 6B aligned alternately. The spacing between two light source panels 7a corresponds to the spacing between two cultivation spaces with the same reference numeral. Four liquid fertilizer tanks 4A, 4B corresponding to the four cultivation spaces 6A, 6B are arranged in the lower housing 2C of the cultivation device 2. The four liquid fertilizer tanks 4A, 4B are arranged adjacent to each other inside separate lower housings 2C (i.e., separate lower spaces 2D).

[0051] The movement control device 30 synchronously moves the four light source panels 7a. Alternatively, the movement control device 30 may move the heat shield case 7b along the longitudinal direction of the growth spaces 6A, 6B together with the growth spaces 6A, 6B and the liquid fertilizer tanks 4A, 4B without moving the light source panels 7a. In either case, as shown in FIG. 12 , a state in which the plants in the two growth spaces 6A are irradiated with artificial light output from the two pairs of light source panels 7a and a state in which the plants in the two growth spaces 6B are not irradiated with artificial light output from the light source panels 7a are simultaneously created. Although not shown, relative movement of the light source panels 7a and the growth spaces 6A, 6B simultaneously creates a state in which the plants in the two growth spaces 6B are irradiated with artificial light output from the two pairs of light source panels 7a and a state in which the plants in the two growth spaces 6A are not irradiated with artificial light output from the light source panels 7a.

[0052] 13 to 15 are plan cross-sectional views of a plant growing device 1D according to yet another modification of the first embodiment. In the plant growing device 1D, the upper portion 2A of the cultivation device 2 has three growing spaces 6A, 6B, and 6C arranged adjacent to one another along one direction. Three liquid fertilizer tanks 4A, 4B, and 4C corresponding to the three growing spaces 6A, 6B, and 6C are arranged in the lower housing 2C of the cultivation device 2. The liquid fertilizer tanks 4A, 4B, and 4C are arranged inside separate lower housings 2C arranged adjacent to one another (i.e., separate lower spaces 2D). Each light source unit 7 has two light source panels (a first light source panel 71 and a second light source panel 72) enclosed in a single, elongated heat-shielding case 7b. The first light source panel 71 and the second light source panel 72 are arranged along the longitudinal direction of the growing spaces 6A, 6B, and 6C, but are arranged on different planes. The surface on which the first light source panel 71 is arranged is parallel to the surface on which the second light source panel 72 is arranged. Therefore, as shown in Figures 13 to 15, the first light source panel 71 and the second light source panel 72 can move along the longitudinal direction of the cultivation spaces 6A, 6B, and 6C without colliding with each other. As will be described later, the first light source panel 71 and the second light source panel 72 emit artificial light L having different wavelength spectra.

[0053] The first light source panel 71 and the second light source panel 72 are arranged so as to be shared by the three cultivation spaces 6A, 6B, and 6C. The movement control device 30 moves the first light source panel 71 and the second light source panel 72 relative to the cultivation spaces 6A, 6B, and 6C. For example, the movement control device 30 synchronously moves the first light source panel 71 of the two light source units 7 and also synchronously moves the second light source panel 72. As a result, the movement control device 30 simultaneously creates a state in which the plants 3 in one of the cultivation spaces 6A, 6B, and 6C are irradiated with the artificial light L output from the first light source panel 71, a state in which the plants 3 in another of the cultivation spaces 6A, 6B, and 6C are irradiated with the artificial light L output from the second light source panel 72, and a state in which the plants 3 in yet another of the cultivation spaces 6A, 6B, and 6C are not irradiated with the artificial light L.

[0054] In this modification, three cultivation spaces 6A, 6B, and 6C share the first light source panel 71 and the second light source panel 72, and use the first light source panel 71 and the second light source panel 72 in a time-division manner. This makes it possible to simultaneously place one of the cultivation spaces 6A, 6B, and 6C in an environment irradiated with artificial light L from the first light source panel 71, another of the cultivation spaces 6A, 6B, and 6C in an environment irradiated with artificial light L from the second light source panel 72 having a different wavelength spectrum, and still another of the cultivation spaces 6A, 6B, and 6C in an environment not irradiated with artificial light L.

[0055] Furthermore, by sharing the first light source panel 71 and the second light source panel 72 among the three cultivation spaces 6A, 6B, and 6C and using the first light source panel 71 and the second light source panel 72 in a time-division manner, it is possible to switch between cultivation spaces illuminated with artificial light from the first light source panel 71, cultivation spaces illuminated with artificial light from the second light source panel 72, and cultivation spaces not illuminated with artificial light. Therefore, for plants in each cultivation space, it is possible to provide a period illuminated with artificial light from the first light source panel 71, a period illuminated with artificial light from the second light source panel 72 having a different wavelength spectrum, and a period not illuminated with artificial light.

[0056] Fig. 13 shows a state in which the plant 3 in the cultivation space 6A is irradiated with artificial light L output from the first light source panel 71, a state in which the plant 3 in the cultivation space 6B is irradiated with artificial light L output from the second light source panel 72, and a state in which the plant 3 in the cultivation space 6C is not irradiated with artificial light L. Fig. 14 shows a state in which the plant 3 in the cultivation space 6A is not irradiated with artificial light L, a state in which the plant 3 in the cultivation space 6B is irradiated with artificial light L output from the second light source panel 72, and a state in which the plant 3 in the cultivation space 6C is irradiated with artificial light L output from the first light source panel 71. Fig. 15 shows a state in which the plant 3 in the cultivation space 6A is irradiated with artificial light L output from the second light source panel 72, a state in which the plant 3 in the cultivation space 6B is irradiated with artificial light L output from the first light source panel 71, and a state in which the plant 3 in the cultivation space 6C is not irradiated with artificial light L. 13 to 15 are examples of how to use the plant growing device 1D, and other arrangements of the two pairs of light source panels 71, 72 relative to the three growing spaces 6A, 6B, 6C are also possible.

[0057] The first light source panel 71 and the second light source panel 72 emit artificial light L having different wavelength spectra. Specifically, the first light source panel 71 emits visible light, and the second light source panel 72 emits at least ultraviolet light. That is, the first light source panel 71 may be the same as the light source panel 7a described above, and the second light source panel 72 may emit only ultraviolet light, particularly UV-A with a wavelength of 315 to 400 nm, or may emit both visible light and UV-A. When a light source panel using LED chips 33 as shown in Figures 2 to 4 is used for the second light source panel 72, all of the LED chips 33 may emit UV-A. Alternatively, some LED chips 33 may emit visible light, and some other LED chips 33 may emit UV-A. The material and thickness of the heat-shielding case 7b are preferably designed to have high transmittance not only for visible light but also for UV-A. Even when an artificial light source other than an LED panel is used, each light source unit 7 is provided with a first artificial light source that emits visible light and a second artificial light source that emits at least ultraviolet light.

[0058] Plants receive visible light and grow through photosynthesis. Visible light is essential for plant growth through photosynthesis. However, when plants receive UV-A, which has a wavelength of 315 to 400 nm, it can promote flower bud formation and produce beneficial substances. Examples of beneficial substances include antioxidants, which are produced by plants exposed to UV rays as a defense against UV radiation. For example, legumes exposed to UV rays produce large amounts of isoflavones, while lettuce, cabbage, broccoli, and other vegetables exposed to UV rays produce large amounts of anthocyanins. However, if a plant contains too many antioxidants, the taste and aroma of the plant can be impaired. Furthermore, if a plant expends too much energy producing antioxidants, growth through photosynthesis may be insufficient. The three cultivation spaces 6A, 6B, and 6C share a first light source panel 71 that emits visible light and a second light source panel 72 that emits at least ultraviolet light in a time-sharing manner, and by appropriately setting the period of UV-A irradiation to the plants 3 in the cultivation spaces 6A, 6B, and 6C, the plants in each cultivation space can properly carry out photosynthesis and properly produce useful substances.

[0059] 16 to 18 are plan cross-sectional views of a plant growing device 1E according to yet another modification of the first embodiment. In the plant growing device 1E, the upper portion 2A of the cultivation device 2 has two growing spaces 6A, 6B arranged adjacent to each other along one direction. Two liquid fertilizer tanks 4A, 4B corresponding to the two growing spaces 6A, 6B are arranged in the lower housing 2C of the cultivation device 2. The liquid fertilizer tanks 4A, 4B are arranged inside separate lower housings 2C arranged adjacent to each other (i.e., separate lower spaces 2D). Each light source unit 7 has two light source panels (a first light source panel 73 and a second light source panel 74) enclosed in a single, elongated heat-shielding case 7b. The first light source panel 73 and the second light source panel 74 are arranged along the longitudinal direction of the growing spaces 6A, 6B but on different planes. The plane on which the first light source panel 73 is arranged is parallel to the plane on which the second light source panel 74 is arranged. Therefore, as shown in Figures 16 to 18, the first light source panel 73 and the second light source panel 74 can move along the longitudinal direction of the growing spaces 6A and 6B without colliding with each other.

[0060] In the plant growing device 1E, either the first light source panel 73 or the second light source panel 74 is used depending on the growth stage of the plant 3. Each heat shielding case 7b has a length greater than the lengths of the three growing spaces. One end of each heat shielding case 7b (the right end in the figure) is used as a standby position 7d for the light source panel 73 or 74 that is not used to supply artificial light to the growing spaces 6A, 6B.

[0061] The first light source panel 73 and the second light source panel 74 emit visible light having different wavelength spectra. Specifically, the first light source panel 73 emits visible light, and the second light source panel 74 emits visible light with fewer blue wavelength components than the visible light emitted by the first light source panel 73. For example, the first light source panel 73 may include LED chips 33 that emit red wavelength light more strongly than light of other wavelengths, and LED chips 33 that emit blue wavelength light more strongly than light of other wavelengths. In this case, the second light source panel 74 may include only LED chips 33 that emit red wavelength light more strongly than light of other wavelengths. Even when an artificial light source other than an LED panel is used, each light source unit 7 is provided with a first artificial light source that emits visible light and a second artificial light source that emits visible light with fewer blue wavelength components than the visible light emitted by the first artificial light source.

[0062] The two cultivation spaces 6A, 6B share the first light source panel 73 and the second light source panel 74, and by using the first light source panel 73 and the second light source panel 74 in a time-division manner, it is possible to change the cultivation space between one illuminated with artificial light from the first light source panel 73, one illuminated with artificial light from the second light source panel 74, and one not illuminated with artificial light. Therefore, for plants in each cultivation space, it is possible to provide a period illuminated with artificial light from the first light source panel 73, a period illuminated with artificial light from the second light source panel 74 having a different wavelength spectrum, and a period not illuminated with artificial light.

[0063] The movement control device 30 creates a first stage in which the second light source panel 74 stops at a standby position 7d where the second light source panel 74 cannot supply artificial light to either of the growing spaces 6A, 6B, and moves the first light source panel 73 relative to the growing spaces 6A, 6B. The movement control device 30 also creates a second stage in which the first light source panel 73 stops at the standby position 7d where the first light source panel 73 cannot supply artificial light to either of the growing spaces 6A, 6B, and moves the second light source panel 74 to the growing spaces 6A, 6B.

[0064] 16 and 17 show a first stage in which the second light source panel 74 is stopped at the standby position 7d and the first light source panel 73 is moved relative to the growing spaces 6A and 6B. In FIG. 16, the growing space 6A is set to a daytime state by the first light source panel 73, and the growing space 6B is set to a nighttime state. In FIG. 17, the growing space 6B is set to a daytime state by the first light source panel 73, and the growing space 6A is set to a nighttime state. In FIG. 18, the first light source panel 73 is stopped at the standby position 7d and the second light source panel 74 is moved relative to the growing spaces 6A and 6B. In FIG. 18, the growing space 6A is set to a daytime state by the second light source panel 74, and the growing space 6B is set to a nighttime state. Although not shown, when the second light source panel 74 moves relative to the growing spaces 6A and 6B, the growing space 6B is set to a daytime state by the second light source panel 74, and the growing space 6A is set to a nighttime state. The light source panel 73 or 74 stopped at the standby position 7d may be turned off by the light emission control device 18.

[0065] Three types of plant photoreceptors are known: phytochrome, cryptochrome, and phototropin. Phytochrome primarily responds to red and far-red light to photosynthesize, while cryptochrome and phototropin primarily respond to blue light. Once a plant reaches a fully grown stage, it no longer requires lush foliage, slowing the rate of photosynthesis and reducing the amount of light required for growth. Therefore, from an economic perspective, it is preferable to change the plant's growth environment to one that suppresses plant photosynthesis. Light source devices (e.g., LED chips 33) that emit short-wavelength (e.g., blue) artificial light consume high amounts of power, while light source devices that emit long-wavelength (e.g., red) artificial light consume low amounts of power. This is because, for the same number of photons, short-wavelength light has a high energy content and long-wavelength light has a low energy content. By sharing the first light source panel 73 and the second light source panel 74, which emit visible light with different wavelength spectra, between the two growth spaces 6A and 6B in a time-sharing manner, it is possible to easily create an environment in each growth space suitable for the growth stage. That is, before the plants have fully grown, the first light source panel 73, which emits visible light with a wide wavelength range, can be moved relative to the growth spaces 6A and 6B to switch between daytime and nighttime in the growth spaces 6A and 6B. On the other hand, after the plants have fully grown, the second light source panel 74, which emits artificial light with a small blue wavelength range, can be moved relative to the growth spaces 6A and 6B to switch between daytime and nighttime in the growth spaces 6A and 6B. This allows the use of light source panels appropriate for the growth stage of the plants. Before the plants have fully grown, the second light source panel 74 may be turned off, and after the plants have fully grown, the first light source panel 73 may be turned off. However, because the switching between daytime and nighttime in each growth space is achieved by the relative movement of one of the light source panels, the number of times the light source panels 73 and 74 need to be turned on and off can be reduced.

[0066] Because multiple growing spaces 6A, 6B share the first light source panel 73 and the second light source panel 74, the number of first light source panels 73 does not need to correspond to the number of growing spaces 6A, 6B. The number of second light source panels 74 also does not need to correspond to the number of growing spaces 6A, 6B. Although light source units 7 are disposed on both sides of the two growing spaces 6A, 6B, each light source unit 7 has a single first light source panel 73 and a single second light source panel 74. Each light source unit 7 does not need to have two first light source panels 73 corresponding to the two growing spaces 6A, 6B, and does not need to have two second light source panels 74. Therefore, an increase in the number of light source panels 7a can be prevented.

[0067] In any of the above-described modified examples, the environmental control device 20 may control the growth space where the artificial light source irradiates visible light (corresponding to daytime) to an environment that promotes plant photosynthesis. Also, the environmental control device 20 may control the growth space where the artificial light source does not irradiate visible light (corresponding to nighttime) to an environment that suppresses plant photosynthesis.

[0068] 16 to 18 , in the plant growing device 1E according to the modified example, the environmental control device 20 may control both of the growing spaces 6A and 6B to an environment that promotes plant photosynthesis during the first stage when the movement control device 30 moves the first light source panel 73 relative to the growing spaces 6A and 6B. The environmental control device 20 may control both of the growing spaces 6A and 6B to an environment that suppresses plant photosynthesis during the second stage when the movement control device 30 moves the second light source panel 74 relative to the growing spaces 6A and 6B. In this case, during the first stage, which corresponds to a stage before plants have fully grown and in which the first light source panel 73, which emits visible light with a wide wavelength range, switches the growing spaces 6A and 6B between daytime and nighttime, the growing spaces 6A and 6B are controlled to an environment that promotes plant photosynthesis. On the other hand, in the second stage, which corresponds to the stage when the plants are fully grown, the second light source panel 74, which emits artificial light with a small blue wavelength component, switches the growth spaces 6A, 6B between daytime and nighttime, and the growth spaces 6A, 6B are controlled to an environment that suppresses plant photosynthesis. As described above, an environment that suppresses plant photosynthesis typically requires low operating costs, so the operating costs for the stage when the plants are fully grown can be reduced. In the first and second stages, the environmental control device 20 may control the growth space 6A or 6B that receives visible light to an environment that more promotes photosynthesis than the growth space 6B or 6A that does not receive visible light.

[0069] Figures 19 and 20 show a plant cultivation device 81 according to a second embodiment of the present invention. In Figures 19 and 20, the same reference numerals are used to indicate components common to the first embodiment, and these components will not be described in detail. The plant cultivation device 81 includes a cultivation device 82 for cultivating multiple plants. The cultivation device 82 includes an upper portion 82A and a lower portion 82B disposed below the upper portion 82A. The lower portion 82B is provided with a lower housing 82C. The lower housing 82C has peripheral and bottom walls defining a lower space 82D, and its top is open. A single liquid fertilizer tank 4 or multiple liquid fertilizer tanks 4A and 4B are disposed inside the lower housing 82C. In the plant cultivation device 81, a single light source unit 77 is disposed above the adjacently arranged cultivation spaces 6A and 6B. In other words, the light source unit 77 is disposed near the cultivation spaces 6A and 6B.

[0070] The light source unit 77 includes a light source panel (artificial light source) 77a and a transparent heat-shielding case 77b that surrounds the light source panel 77a. The light source panel 77a is oriented horizontally, and the heat-shielding case 77b that surrounds the light source panel 77a is also oriented horizontally.

[0071] The light source panel 77a emits artificial light L for growing the plants 3. Because the light source unit 77 is disposed above the growth spaces 6A, 6B, the light source panel 77a supplies the artificial light L from above to the plants 3 in the growth spaces 6A, 6B. The plant growing device 81, which irradiates the artificial light L from above downward, is suitable for applying the artificial light L to plants 3 at a growth stage in which the leaves spread widely in the horizontal or diagonal directions compared to their height. The light source panel 77a is disposed so as to be shared by the plurality of growth spaces 6A, 6B, and supplies the artificial light L to the growth spaces 6A, 6B. However, the growth spaces 6A, 6B use these light source panels 77a in a time-division manner (i.e., at different periods).

[0072] Like the heat-shielding case 7b described above, the heat-shielding case 77b is formed of a light-transmitting material, such as glass or transparent resin. The heat-shielding case 77b has a heat-shielding partition 77c interposed between the growth spaces 6A, 6B and the light source panel 77a. The heat-shielding partition 77c is formed flat and oriented horizontally. As shown in FIG. 20 , the heat-shielding case 77b has a length equal to or greater than the total length of the multiple growth spaces 6A, 6B. The heat-shielding case 77b is disposed near the multiple growth spaces 6A, 6B and extends along the multiple growth spaces 6A, 6B. The heat-shielding partition 77c also has a length equal to or greater than the total length of the multiple growth spaces 6A, 6B. The heat-shielding partition 77c is also disposed near the multiple growth spaces 6A, 6B and extends along the multiple growth spaces 6A, 6B. The heat-shielding case 77b suppresses or inhibits heat radiation and heat conduction from the light source panel 77a, which is a heat source, to prevent overheating of the growing spaces 6A and 6B. In this embodiment, the heat-shielding case 77b surrounds the entire light source panel 77a. However, the heat-shielding case 77b does not necessarily have to surround the entire light source panel 77a. For example, the top wall and side walls of the heat-shielding case 77b may be omitted. Furthermore, the portions of the heat-shielding case 77b other than the heat-shielding partition wall 77c between the light source panel 77a and the growing spaces 6A and 6B do not have to be transparent.

[0073] As in the first embodiment, in order to prevent overheating of the heat shielding case 77b and the light source panel 77a, any of a blower (not shown), a refrigerant pipe or a refrigerant chamber (not shown), and fins (not shown) may be provided. In order to efficiently suppress heat conduction from the light source panel 77a, the inside of the heat shielding case 77b may be evacuated.

[0074] The height H from the plant support panel 5 to the heat-shielding partition 77c of the light source unit 77 is set to a size that allows artificial light L to be applied substantially evenly and sufficiently to each leaf of the plant 3 that has grown to a certain extent. However, the height H of the heat-shielding partition 77c of the light source unit 77 is preferably set to restrict excessive vertical elongation of the plant 3. That is, it is preferable that the height of the heat-shielding partition 77c relative to the plant 3 is determined (the heat-shielding partition 77c is disposed relative to the plant support panel 5) so that the heat-shielding partition 77c restricts elongation of the leaves of the plant 3 cultivated inside the growth spaces 6A, 6B in a direction toward the light source panel 77a. Specifically, it is preferable that the height H of the heat-shielding partition 77c of the heat-shielding case 77b is set to be smaller than the maximum height that the upper ends of the leaves of the plant 3 are expected to reach as they grow, assuming that the heat-shielding case 77b is not present. In this case, the heat-shielding partition 77c restricts excessive growth of the leaves of the plant 3, so that the plant 3 can be grown in a small space (small height).

[0075] In this embodiment, the heat shield case 77b of the light source unit 77 has a length equal to or greater than the total length of the growing spaces 6A and 6B. The growing spaces 6A and 6B are spaces above the liquid fertilizer tanks 4A and 4B, respectively.

[0076] The movement control device 30 controls a movement mechanism (not shown) to move the light source panel 77a of the light source unit 77 relative to the growing spaces 6A and 6B. The light source panel 77a is arranged so as to be shared by both growing spaces 6A and 6B. The movement control device 30 moves at least one of the growing spaces 6A and 6B and the light source panel 77a so as to simultaneously create a state in which the plants 3 in one of the growing spaces 6A and 6B are irradiated with artificial light L output from the light source panel 77a and a state in which the plants 3 in the other of the growing spaces 6A and 6B are not irradiated with artificial light L. Furthermore, the system can switch between growing spaces irradiated with artificial light and those not irradiated with artificial light. By sharing the light source panel 77a between the two growing spaces 6A and 6B and using the light source panel 77a in a time-division manner, it is possible to simultaneously place one of the growing spaces 6A and 6B in an environment irradiated with artificial light L from the light source panel 77a and place the other of the growing spaces 6A and 6B in an environment not irradiated with artificial light L. 20 shows a state in which the plants 3 in the cultivation space 6A are irradiated with artificial light L output from the light source panel 77a, while the plants 3 in the cultivation space 6B are not irradiated with artificial light L. Although not shown, it is also possible to conversely irradiate the plants 3 in the cultivation space 6B with artificial light L output from the light source panel 77a, while the plants 3 in the cultivation space 6A are not irradiated with artificial light L. In this way, it is possible to alternate between periods in which artificial light is irradiated and periods in which it is not irradiated to the plants in each cultivation space.

[0077] The movement control device 30 may move the light source panel 77a from the vicinity of one of the growing spaces 6A, 6B to the vicinity of the other in a 12-hour cycle, for example. In this case, in each of the growing spaces 6A, 6B, 12 hours of the day are daylight and the other 12 hours are night. However, the movement control device 30 may move the light source panel 77a from one of the growing spaces 6A, 6B to the other in other cycles. For example, even if the light source panel 77a is moved from one of the growing spaces 6A, 6B to the other in a 6-hour cycle or a 4-hour cycle, each of the growing spaces 6A, 6B will have a total of 12 hours of daylight and 12 hours of night in one day.

[0078] According to this embodiment, the heat-shielding case 77b thermally isolates the growing spaces 6A, 6B from the light source panel 77a, making them less susceptible to the heat. In other words, the heat-shielding case 77b prevents the growing spaces 6A, 6B from overheating. This reduces the energy required by the air-conditioning system 12 to control the air temperature in the growing spaces 6A, 6B, making it easier to maintain the growing spaces 6A, 6B in an environment suitable for the plants being grown.

[0079] Furthermore, by moving the light source panel 77a relative to the growing spaces 6A and 6B using the movement control device 30, it is possible to simultaneously create a state in which plants in one of the growing spaces 6A and 6B are illuminated with artificial light (a state corresponding to daytime) and a state in which plants in the other of the growing spaces 6A and 6B are not illuminated (a state corresponding to nighttime). That is, by sharing the light source panel 77a among multiple growing spaces 6A and 6B and using the light source panel 77a in a time-division manner (i.e., at different periods), it is possible to simultaneously place one of the growing spaces 6A and 6B in an artificial light-illuminated environment and the other of the growing spaces 6A and 6B in an artificial light-illuminated environment. The number of light source panels 77a does not need to correspond to the number of growing spaces 6A and 6B. In this embodiment, a single light source panel 77a can be used to simultaneously create a daytime state in one of the growing spaces 6A and 6B and a nighttime state in the other of the growing spaces 6A and 6B. This prevents the need for an increase in the number of light source panels 77a.

[0080] Furthermore, because the light source panel 77a is used by the multiple growing spaces 6A, 6B in a time-sharing manner, the light source panel 77a can be continuously driven. This reduces the number of times the light source panel 77a is turned on and off, shortening the period of non-use of the light source panel 77a. Furthermore, when the artificial light source is a fluorescent lamp or a cold cathode fluorescent tube, this reduces malfunctions caused by on-off switching and saves power consumption. However, the light source panel 77a does not need to be driven continuously. Many types of plants flower by sensing changes in photoperiod. Therefore, even when the light source panel 77a is moved from the vicinity of one of the growing spaces 6A, 6B to the vicinity of the other in a 12-hour cycle, for example, a period during which the light source panel 77a does not emit light may be provided.

[0081] The movement control device 30 moves the light source panel 77a in the heat-shielding case 77b along the longitudinal direction of the fixed growing spaces 6A, 6B without moving the heat-shielding case 77b. However, the movement control device 30 may also move the heat-shielding case 77b along the longitudinal direction of the growing spaces 6A, 6B together with the growing spaces 6A, 6B without moving the light source panel 77a. In either case, the movement control device 30 moves the light source panel 77a relative to the growing spaces 6A, 6B while the heat-shielding case 77b remains stationary relative to the growing spaces 6A, 6B. In this embodiment, the heat-shielding case 77b has a length equal to or greater than the combined length of the growing spaces 6A, 6B. Therefore, the heat-shielding case 77b does not collide with or slide against the plants 3 inside the growing spaces 6A, 6B, preventing damage to the plants 3 due to impact or friction. As described above, it is preferable that the position of the heat-shielding partition 77c relative to the plant 3 or the plant support panel 5 is determined so that the heat-shielding partition 77c restricts the growth of the leaves of the plant 3 cultivated inside the cultivation spaces 6A, 6B in a direction toward the light source panel 77a. In this case, the plant 3 can be grown in a small space (small height). The above-described variations of the first embodiment may also be applied to this embodiment.

[0082] As shown in Figure 21, a plant growing device 101 according to the third embodiment has a cultivation device 102 for growing a large number of plants. The plant growing device 101 is arranged in a plant factory. The plants 3 grown in the plant growing device 101 are, for example, agricultural crops such as beans, but may also be other plants that perform photosynthesis. The plant growing device 101 according to the third embodiment is preferably used for plants that grow long trunks and have many leaves that overlap vertically as they grow. The large number of plants 3 are arranged in a direction perpendicular to the plane of the paper in Figure 21 (see Figures 22 and 23).

[0083] The cultivation device 102 has an upper portion 102A and a lower portion 102B disposed below the upper portion 102A. A plurality of liquid fertilizer tanks 4A, 4B are disposed in the lower portion 102B. The plurality of liquid fertilizer tanks 4A, 4B are arranged in a direction perpendicular to the plane of the page in FIG. 21 (see FIGS. 22 and 23). Roots (including main roots and lateral roots) of plants 3 are disposed inside each of the liquid fertilizer tanks 4A, 4B, and the roots grow therein. The liquid fertilizer tanks 4A, 4B are containers that contain a nutrient solution 41 containing fertilizer to be applied to the roots of the plants 3.

[0084] A plant support panel 5 is attached to the top of each of the liquid fertilizer tanks 4A, 4B. The trunks of multiple plants 3 pass through the plant support panel 5, and the plant support panel 5 supports these plants 3. The plant support panel 5 may be breathable. For example, the plant support panel 5 may be porous, or may have a large number of through-holes.

[0085] The plant growing device 101 further includes a nutrient solution supply system 10. The nutrient solution supply system 10 is connected to the liquid fertilizer tanks 4A, 4B via a liquid fertilizer pipeline 11, and the nutrient solution supply system 10 supplies nutrient solution 41 to the liquid fertilizer tanks 4A, 4B.

[0086] The cultivation device 102 further has a housing 60. The housing 60 extends vertically from the lower part 102B to the upper part 102A of the cultivation device 102. In this embodiment, a plurality of housings 60 are provided, and the plurality of housings 60 are arranged in the direction perpendicular to the plane of the paper in FIG. 21 (see FIGS. 22 and 23). A lower space 102D in which a liquid fertilizer tank 4A or 4B is disposed is provided below each housing 60. The liquid fertilizer tanks 4A and 4B are disposed inside these housings 60, respectively.

[0087] Two growing spaces 8A and 8B are arranged in the upper portion 102A of the cultivation device 102. The growing spaces 8A and 8B are spaces above the liquid fertilizer tanks 4A and 4B, respectively, and are spaces inside the housing 60. The growing spaces 8A and 8B are arranged close to each other in the direction perpendicular to the plane of the paper in FIG. 21 (see FIGS. 22 and 23). In this embodiment, the above-ground portions (i.e., stems and leaves) of multiple plants 3 grow (are cultivated) in each of the growing spaces 8A and 8B. However, the above-ground portion of only one plant 3 may grow in each of the growing spaces 8A and 8B. The two housings 60 define the closed growing spaces 8A and 8B, respectively.

[0088] A pair of light source panels (artificial light sources) 7a are arranged on the upper portion 102A of the cultivation device 102. The growth spaces 8A and 8B are interposed between these light source panels 7a. In other words, each light source panel 7a is arranged near and outside the two housings 60 corresponding to the growth spaces 8A and 8B, respectively. The pair of light source panels 7a are oriented vertically, arranged parallel to each other, and facing each other.

[0089] Each light source panel 7a emits artificial light L for growing the plants 3. The light source panels 7a are arranged on both sides of the growth spaces 8A, 8B, and supply the artificial light L from the sides to the plants 3 in the growth spaces 8A, 8B. Therefore, the artificial light L can be applied as evenly as possible to both the upper and lower leaves of the plants 3 in the growth stage when the stems are long and the plants have many leaves overlapping in the vertical direction.

[0090] In this embodiment, a pair of light source panels 7a are arranged on both sides of the growing spaces 8A, 8B, but one light source panel 7a may be arranged on one side of the growing spaces 8A, 8B. The pair of light source panels 7a are arranged so as to be shared by the plurality of growing spaces 8A, 8B and supply artificial light L to the growing spaces 8A, 8B. However, the growing spaces 8A, 8B use these light source panels 7a in a time-division manner (i.e., at different periods).

[0091] Each housing 60 defining the growth space 8A or 8B is formed from a light-transmitting material, such as glass or a transparent resin. Examples of usable transparent resins include, but are not limited to, acrylic, polyethylene terephthalate, polycarbonate, and polyvinyl chloride. Each housing 60 has a heat-shielding partition 60a interposed between the growth space 8A or 8B and the light source panel 7a. The heat-shielding partition 60a is formed flat, and the heat-shielding partitions 60a of a pair of housings 60 are arranged parallel to each other. Each housing 60 suppresses or inhibits heat radiation and heat conduction from the light source panel 7a, which is a heat source, to prevent overheating of the growth space 8A or 8B. In this embodiment, each housing 60 entirely surrounds the growth space 8A or 8B. However, each housing 60 does not necessarily have to entirely surround the growth space 8A or 8B. For example, the upper and lower walls of each housing 60 may be omitted, or the upper and lower walls may not be transparent. The portion of each housing 60 that is present in the lower portion 102B and surrounds the liquid fertilizer tank 4A or 4B does not have to be transparent either.

[0092] To prevent overheating of each light source panel 7a, a blower (not shown) may be used to generate airflow around each light source panel 7a, thereby cooling each light source panel 7a with air. Instead of or in addition to the blower, a refrigerant pipe or refrigerant chamber (not shown) may be disposed near each light source panel 7a (e.g., in contact with each light source panel 7a) to lower the temperature of each light source panel 7a. The refrigerant may be, for example, a gas such as air or hydrofluorocarbon, or a liquid such as water or ammonia. The refrigerant pipe or refrigerant chamber is preferably disposed on the side opposite the light-emitting surface of each light source panel 7a. Fins (not shown) may be provided on the wall opposite the light-emitting surface of each light source panel 7a to improve cooling efficiency.

[0093] The spacing between the pair of heat-shielding partition walls 60a of the casing 60 in FIG. 21 is set to a size that allows artificial light L to be applied substantially evenly and sufficiently to each leaf of the plant 3 that has grown to a certain extent. However, it is preferable that the spacing between the heat-shielding partition walls 60a be set so as to restrict excessive lateral growth of the plant 3. That is, it is preferable that the position of the heat-shielding partition wall 60a relative to the plant 3 be determined so that the heat-shielding partition wall 60a restricts the growth of the leaves of the plant 3 cultivated inside the growing spaces 8A and 8B toward the light source panel 7a. Specifically, it is preferable that the horizontal distance from the base of the plant 3 to the heat-shielding partition wall 60a be set shorter than the maximum horizontal distance from the base of the plant 3 that is predicted to be reached by the tip of a leaf that has grown to its maximum length if the casing 60 were not present. In this case, the heat-shielding partition wall 60a restricts excessive leaf growth of the plant 3, allowing the plant 3 to be grown in a small space (small width).

[0094] The plant growing device 101 further includes an air conditioning system 12, a light emission control device 18, an environmental control device 20, and a movement control device 30. The air conditioning system 12 adjusts the environment of the cultivation device 102 in which the plants are grown to the temperature, humidity, and carbon dioxide (CO ) levels suitable for plant growth. ２ ) concentration. The air conditioning system 12 is connected to the housing 60 via an air duct 14 and communicates with a lower space 102D inside the housing 60. The air conditioning system 12 is also connected to the housing 60 via an air duct 16 and communicates with the growing spaces 8A and 8B inside the housing 60. The air conditioning system 12 supplies the conditioned air to the cultivation device 102 via the air duct 14 or 16 and takes in air from the inside of the cultivation device 102 via the air duct 16 or 14. A plurality of ventilation gaps 40 are provided between the housing 60 and the liquid fertilizer tank 4A or 4B in the lower part 102B of the cultivation device 102. The air conditioned by the air conditioning system 12 can flow through these ventilation gaps 40 from the upper part 102A (growing spaces 8A and 8B) of the cultivation device 102 to the lower part 102B (lower space 102D) or from the lower part 102B to the upper part 102A.

[0095] The light-emitting control device 18 controls the light emission of the light source panel 7a. For example, the light-emitting control device 18 turns the light source panel 7a on and off. The environmental control device 20 is a computer processor. The environmental control device 20 controls the environment inside the cultivation device 102. As described below, the environmental control device 20 issues commands to the nutrient solution supply system 10 and the air conditioning system 12 to alternately control the growth spaces 8A, 8B between an environment that promotes plant photosynthesis and an environment that suppresses photosynthesis. The movement control device 30 is also a computer processor. The movement control device 30 may be a processor separate from the environmental control device 20 or may be the same processor as the environmental control device 20. As described below, the movement control device 30 controls a movement mechanism (not shown) to move the light source panel 7a relative to the housing 60 (i.e., to move the light source panel 7a relative to the growth spaces 8A, 8B). The cultivation device 102 has a movement mechanism that moves the light source panel 7a relative to the growth spaces 8A, 8B. The movement mechanism may be, for example, a wheel driven by a motor, a belt conveyor mechanism, a caterpillar mechanism, or a rack and pinion mechanism.

[0096] The light source panel 7a may be the same as that described above with reference to Figures 2 to 4. In this embodiment, the light source panel 7a has a plurality of LED chips 33 that generate little heat as the artificial light source. However, the artificial light source may also be at least one fluorescent lamp, at least one cold cathode fluorescent tube, or other light source.

[0097] As shown in the plan cross-sectional views of Figures 22 and 23, the liquid fertilizer tanks 4A, 4B are long containers, and multiple plants 3 are lined up along the longitudinal direction of each liquid fertilizer tank. The light source panel 7a and the growing spaces 8A, 8B extend along the longitudinal direction of the liquid fertilizer tanks 4A, 4B. In this embodiment, as shown in Figures 22 and 23, each light source panel 7a is moved between facing the growing space 8A and facing the growing space 8B. The stroke of the movement of the light source panel 7a is set so that it can face multiple growing spaces 8A, 8B.

[0098] A light-shielding wall 50 is interposed between the housings 60 (60A, 60B) surrounding the cultivation spaces 8A, 8B, respectively. To increase the efficiency of use of artificial light L in the cultivation spaces 8A, 8B, it is preferable that both surfaces of the light-shielding wall 50 have high light reflectivity. It is preferable that the light-shielding wall 50 is formed from a light-reflecting material (for example, a metal with smooth surfaces). Both surfaces of the light-shielding wall 50 may be coated with a light-reflecting paint.

[0099] In this embodiment, the housing 60, the liquid fertilizer tanks 4A and 4B, and the growing spaces 8A and 8B are fixed. The growing spaces 8A and 8B above the liquid fertilizer tank 4 are stationary (i.e., fixed) in fixed positions. As described above, the movement control device 30 controls a movement mechanism (not shown) to move the light source panel 7a relative to the housing 60 and thus the growing spaces 8A and 8B. The movement control device 30 moves each light source panel 7a back and forth along the longitudinal direction of the housing 60 (60A, 60B) (the longitudinal direction of the growing spaces 8A and 8B). In other words, the movement control device 30 moves the light source panel 7a while the growing spaces 8A and 8B are stationary. The movement control device 30 moves the pair of light source panels 7a synchronously.

[0100] FIG. 22 shows a state in which a pair of light source panels 7a are positioned on the cultivation space 8A side and irradiate artificial light onto the plant 3 in the cultivation space 8A. In this state, artificial light is not irradiated onto the plant 3 in the cultivation space 8B. In other words, the cultivation space 8A is in a daytime state, and the cultivation space 8B is in a nighttime state. The light-shielding wall 50 prevents artificial light from traveling from the cultivation space 8A to the cultivation space 8B. Therefore, a state in which the plant in the cultivation space 8A is irradiated with artificial light output from the light source panel 7a and a state in which the plant in the cultivation space 8B is not irradiated with artificial light output from the light source panel 7a are simultaneously created. On the other hand, FIG. 23 shows a state in which a pair of light source panels 7a are positioned on the cultivation space 8B side and irradiate artificial light onto the plant 3 in the cultivation space 8B. In this state, artificial light is not irradiated onto the plant 3 in the cultivation space 8A. In other words, the cultivation space 8B is in a daytime state, and the cultivation space 8A is in a nighttime state. The light-shielding wall 50 prevents the artificial light from traveling from the cultivation space 8B to the cultivation space 8A. Therefore, a state in which the plants in the cultivation space 8B are irradiated with the artificial light output from the light source panel 7a and a state in which the plants in the cultivation space 8A are not irradiated with the artificial light output from the light source panel 7a are simultaneously created.

[0101] The movement control device 30 may, for example, move the light source panel 7a from near one of the growing spaces 8A, 8B to near the other in a 12-hour cycle. In this case, in each of the growing spaces 8A, 8B, 12 hours of the day are daylight and the other 12 hours are night. However, the movement control device 30 may move the light source panel 7a from one of the growing spaces 8A, 8B to the other in other cycles. For example, the light source panel 7a may be moved from one of the growing spaces 8A, 8B to the other in a 6-hour, 4-hour, or 3-hour cycle. In either case, in each of the growing spaces 8A, 8B, a total of 12 hours of daylight and 12 hours of night are present. In this way, by the movement control device 30 moving the light source panel 7a relative to the housing 60, it is possible to alternately create periods in which the plants in the growing space 8A are illuminated with artificial light (periods corresponding to daylight) and periods in which they are not illuminated (periods corresponding to night). In addition, it is possible to alternately create periods in which the plants in the cultivation space 8B are irradiated with artificial light (periods corresponding to daytime) and periods in which they are not irradiated (periods corresponding to nighttime).

[0102] According to this embodiment, the housing 60 (60A, 60B) thermally isolates the growing spaces 8A, 8B from the light source panel 7a, making them less susceptible to the heat. That is, the housing 60 prevents the growing spaces 8A, 8B from overheating. This reduces the energy required by the air conditioning system 12 to control the air temperature in the growing spaces 8A, 8B, and makes it easier to control the growing spaces 8A, 8B to an environment suitable for the plants being grown.

[0103] Furthermore, by moving the light source panel 7a relative to the growing spaces 8A and 8B, the movement control device 30 can simultaneously create a state in which plants in one of the growing spaces 8A and 8B are illuminated with artificial light (a state corresponding to daytime) and a state in which plants in the other of the growing spaces 8A and 8B are not illuminated (a state corresponding to nighttime). The movement control device 30 also moves the light source panel 7a relative to the multiple growing spaces 8A and 8B so that the artificial light output from the light source panel 7a is supplied to different growing spaces 8A and 8B at different periods. This allows the growing spaces illuminated with artificial light and the growing spaces not illuminated with artificial light to be switched. That is, by sharing the light source panel 7a among the multiple growing spaces 8A and 8B and using the light source panel 7a in a time-division manner (i.e., at different periods), it is possible to simultaneously place one of the growing spaces 8A and 8B in an environment illuminated with artificial light and the other of the growing spaces 8A and 8B in an environment not illuminated with artificial light. By switching between the cultivation spaces illuminated with artificial light and those not illuminated with artificial light, it is possible to alternate periods in which the plants in each cultivation space are illuminated with artificial light and periods in which they are not illuminated with artificial light. Since multiple cultivation spaces 8A, 8B share the light source panel 7a, the number of light source panels 7a does not need to correspond to the number of cultivation spaces 8A, 8B. In this embodiment, the light source panels 7a are disposed on both sides of the two cultivation spaces 8A, 8B, so there is no need to provide two light source panels 7a corresponding to the two cultivation spaces 8A, 8B. This prevents an increase in the number of light source panels 7a.

[0104] Furthermore, because the light source panel 7a is used by the multiple cultivation spaces 8A and 8B in a time-sharing manner, the light source panel 7a can be continuously driven. This reduces the number of times the light source panel 7a is turned on and off, shortening the period during which the light source panel 7a is not in use. Furthermore, when the artificial light source is a fluorescent lamp or a cold cathode fluorescent tube, this reduces malfunctions caused by on-off switching and saves power consumption. However, the light source panel 7a does not need to be driven continuously. Many types of plants flower by sensing changes in photoperiod. Therefore, even when the light source panel 7a is moved from the vicinity of one of the cultivation spaces 8A and 8B to the vicinity of the other in a 12-hour cycle, for example, an off period during which the light source panel 7a does not emit light may be provided to accommodate the change in photoperiod.

[0105] The movement control device 30 moves the light source panel 7a along the longitudinal direction of the fixed growth spaces 8A, 8B relative to the growth spaces 8A, 8B. However, as shown in a modified example in FIG. 24 , the movement control device 30 may move the housing 60 (60A, 60B) enclosing the liquid fertilizer tanks 4A, 4B together with the growth spaces 8A, 8B along the longitudinal direction of the growth spaces 8A, 8B without moving the light source panel 7a. In this modified example, the state shown in FIG. 22 , in which the light source panel 7a is positioned on the growth space 8A side, can be transitioned to the state shown in FIG. 24 , in which the light source panel 7a is positioned on the growth space 8B side and artificial light is irradiated onto the plants 3 in the growth space 8B. The state shown in FIG. 24 is equivalent to the state shown in FIG. 23 , in which the growth space 8B is in a daytime state and the growth space 8A is in a nighttime state. In this modified example, the liquid fertilizer pipe 11 and the air pipes 14, 16 are preferably extendable and bendable. In either case, the movement control device 30 moves the light source panel 7 a relative to the housing 60 .

[0106] In this embodiment, one housing 60 (60A) encloses the liquid fertilizer tank 4A and the growing space 8A, and another housing 60 (60B) encloses the liquid fertilizer tank 4B and the growing space 8B. The environments within these housings 60 are isolated from each other and can be considered as independent cultivation units. Therefore, the environmental control device 20 (see FIG. 21) can easily place the combination of the growing space 8A and the liquid fertilizer tank 4A and the combination of the growing space 8B and the liquid fertilizer tank 4B in different environments.

[0107] The environmental control device 20 controls the growth space 8A or 8B, to which the light source panel 7a irradiates visible light, to an environment that promotes photosynthesis of the plants 3, and controls the growth space 8A or 8B, to which the light source panel 7a does not irradiate visible light, to an environment that suppresses photosynthesis of the plants 3. That is, during a period when artificial light is supplied from the light source panel 7a to the growth space 8A shown in FIG. 22 and artificial light is not supplied to the growth space 8B, the combination of the growth space 8A and the liquid fertilizer tank 4A is controlled to an environment that promotes photosynthesis of the plants 3. At the same time, the combination of the growth space 8B and the liquid fertilizer tank 4B is controlled to an environment that suppresses photosynthesis of the plants 3. Conversely, during a period when artificial light is supplied from the light source panel 7a to the growth space 8B shown in FIG. 23 or 24 and artificial light is not supplied to the growth space 8A, the combination of the growth space 8B and the liquid fertilizer tank 4B is controlled to an environment that promotes photosynthesis of the plants 3. At the same time, the combination of the growth space 8A and the liquid fertilizer tank 4A is controlled to an environment that suppresses photosynthesis of the plants 3. In other words, photosynthesis is promoted in the cultivation space 8A or 8B corresponding to the daytime and the liquid fertilizer tank 4A or 4B corresponding to that cultivation space, while photosynthesis is suppressed in the cultivation space 8A or 8B corresponding to the nighttime and the liquid fertilizer tank 4A or 4B corresponding to that cultivation space.

[0108] Specifically, the environmental control device 20 performs at least one of the following examples of environmental control. In one example of environmental control, the environmental control device 20 controls the air conditioning system 12 to increase the temperature of the cultivation space 8A or 8B corresponding to the daytime and the liquid fertilizer tank 4A or 4B corresponding to that cultivation space. At the same time, the environmental control device 20 controls the air conditioning system 12 to decrease the temperature of the cultivation space 8A or 8B corresponding to the nighttime and the liquid fertilizer tank 4A or 4B corresponding to that cultivation space. This reduces the operating cost of the cultivation unit corresponding to the nighttime. It also suppresses the metabolism of the plants 3 in the cultivation unit corresponding to the nighttime. In another example of environmental control, the environmental control device 20 controls the air conditioning system 12 to decrease the CO in the air in the cultivation space 8A or 8B corresponding to the daytime. ２ The concentration of CO in the air in the growth space 8A or 8B corresponding to nighttime is increased. ２Therefore, the operating cost of the cultivation unit during the night can be reduced.

[0109] In another example of environmental control, the environmental control device 20 may control the air conditioning system 12 to appropriately control the humidity in the cultivation space 8A or 8B corresponding to the daytime, but may not control the humidity in the cultivation space 8A or 8B corresponding to the nighttime. When the humidity is high, a lot of water vapor passes through the stomata of the leaves of the plants, and the plants can absorb CO ２ When water droplets get on the leaves, the stomata close and the plant cannot absorb CO ２ In addition, high humidity reduces transpiration from the stomata of the leaves, inhibiting plant growth. On the other hand, if humidity is too low, plants' photosynthetic ability decreases due to drought stress, so there is an optimum range for daytime humidity. When the external environment of the cultivation device 102 is highly humid, humidity control only needs to be performed in the cultivation unit corresponding to the daytime, thereby reducing the operating costs of the cultivation unit corresponding to the nighttime.

[0110] In another example of environmental control, the environmental control device 20 controls the nutrient solution supply system 10 to increase the amount of top dressing (specifically, the concentration of fertilizer) supplied to the liquid fertilizer tank 4A or 4B corresponding to the cultivation space 8A or 8B corresponding to the daytime. At the same time, the environmental control device 20 controls the nutrient solution supply system 10 to decrease the amount of top dressing supplied to the liquid fertilizer tank 4A or 4B corresponding to the cultivation space 8A or 8B corresponding to the nighttime. This reduces the operating costs of the cultivation unit corresponding to the nighttime.

[0111] 25 and 26 are plan cross-sectional views of a plant growing device 101A according to another modification of the third embodiment. In this modification, the cultivation device 102 includes only a single housing 60 enclosing the liquid fertilizer tank 4A and the growing space 8A. However, the horizontal length of the cultivation device 102 in the figure is the same as that of the cultivation device 102 of the third embodiment, and the cultivation device 102 is provided with a light-shielding wall 50. In this plant growing device 101A, the movement control device 30 moves the light source panel 7a relative to the housing 60 to create a period in which the plants in the growing space 8A are irradiated with artificial light output from the light source panel 7a (the state shown in FIG. 25 ) and a period in which the plants in the growing space 8A are not irradiated with artificial light output from the light source panel 7a (the state shown in FIG. 26 ). In this plant growing device 101A, one end of the cultivation device 102 (the right end in the figure) is used as a standby position 102F for the light source panel 7a. The standby position 102F is a position where the light source panel 7a cannot supply artificial light to the cultivation space 8A. During the nighttime period in the cultivation space 8A shown in Figure 26, the movement control device 30 stops the light source panel 7a at the standby position 102F.

[0112] In this modification, the above-ground portions of a plurality of plants 3 grow (are cultivated) in the cultivation space 8A. However, the above-ground portion of only one plant 3 may grow in the cultivation space 8A.

[0113] In the third embodiment and the above-described modified examples, the cultivation device 102 has a pair of light source panels 7a. However, the cultivation device 102 may have multiple pairs of light source panels 7a. For example, in a modified plant cultivation device 101B shown in FIG. 27 , the cultivation device 102 has two pairs of light source panels 7a. The pairs of light source panels 7a are aligned along the longitudinal direction of the cultivation spaces 8A and 8B. The upper portion 102A of the cultivation device 102 has four cultivation spaces 8A and 8B aligned along one direction. Specifically, the cultivation device 102 has two cultivation spaces 8A and two cultivation spaces 8B aligned alternately. The spacing between the two pairs of light source panels 7a corresponds to the spacing between the two cultivation spaces with the same reference numeral. The lower portion 102B of the cultivation device 102 has four liquid fertilizer tanks 4A and 4B corresponding to the four cultivation spaces 8A and 8B. Each housing 60 surrounds the liquid fertilizer tank 4A or 4B and the cultivation space 8A or 8B.

[0114] The movement control device 30 synchronously moves the four light source panels 7a. Alternatively, the movement control device 30 may move the four housings 60 along the longitudinal direction of the cultivation spaces 8A, 8B without moving the light source panels 7a. In either case, as shown in FIG. 27 , a state in which the plants in the two cultivation spaces 8A are illuminated with artificial light output from the two pairs of light source panels 7a and a state in which the plants in the two cultivation spaces 8B are not illuminated with artificial light output from the light source panels 7a are simultaneously created. Although not shown, relative movement of the light source panels 7a and the housings 60 simultaneously creates a state in which the plants in the two cultivation spaces 8B are illuminated with artificial light output from the two pairs of light source panels 7a and a state in which the plants in the two cultivation spaces 8A are not illuminated with artificial light output from the light source panels 7a.

[0115] 28 to 30 are plan cross-sectional views of a plant growing device 101C according to yet another modification of the third embodiment. In the plant growing device 101C, an upper portion 102A of a cultivation device 102 has three growing spaces 8A, 8B, and 8C arranged adjacent to one another along one direction. Three liquid fertilizer tanks 4A, 4B, and 4C corresponding to the three growing spaces 8A, 8B, and 8C are arranged in a lower portion 102B of the cultivation device 102. The liquid fertilizer tanks 4A, 4B, and 4C and the growing spaces 8A, 8B, and 8C are respectively arranged inside separate housings 60 arranged adjacent to one another. The cultivation device 102 has two pairs of light source panels (a pair of first light source panels 71a and a pair of second light source panels 72a). The first light source panels 71a and the second light source panels 72a are arranged along the longitudinal direction of the growing spaces 8A, 8B, and 8C, but are arranged on different planes. The surface on which the first light source panel 71a is arranged is parallel to the surface on which the second light source panel 72a is arranged. Therefore, as shown in Figures 28 to 30, the first light source panel 71a and the second light source panel 72a can move along the longitudinal direction of the cultivation spaces 8A, 8B, and 8C without colliding with each other. As will be described later, the first light source panel 71a and the second light source panel 72a emit artificial light L having different wavelength spectra.

[0116] The first light source panel 71a and the second light source panel 72a are arranged so as to be shared by the three cultivation spaces 8A, 8B, and 8C. The movement control device 30 moves the first light source panel 71a and the second light source panel 72a relative to the cultivation spaces 8A, 8B, and 8C. For example, the movement control device 30 synchronously moves the pair of first light source panels 71a and the pair of second light source panels 72a. As a result, the movement control device 30 simultaneously creates a state in which the plants 3 in one of the cultivation spaces 8A, 8B, and 8C are irradiated with the artificial light L output from the first light source panel 71a, a state in which the plants 3 in another of the cultivation spaces 8A, 8B, and 8C are irradiated with the artificial light L output from the second light source panel 72a, and a state in which the plants 3 in yet another of the cultivation spaces 8A, 8B, and 8C are not irradiated with the artificial light L.

[0117] In this modification, three growing spaces 8A, 8B, and 8C share the first light source panel 71a and the second light source panel 72a and use the first light source panel 71a and the second light source panel 72a in a time-division manner. This allows one of the growing spaces 8A, 8B, and 8C to be placed in an environment irradiated with artificial light L from the first light source panel 71a, another of the growing spaces 8A, 8B, and 8C to be placed in an environment irradiated with artificial light L from the second light source panel 72a having a different wavelength spectrum, and still another of the growing spaces 8A, 8B, and 8C to be placed in an environment not irradiated with artificial light L, all at the same time.

[0118] Furthermore, the three cultivation spaces 8A, 8B, and 8C share the first light source panel 71a and the second light source panel 72a, and by using the first light source panel 71a and the second light source panel 72a in a time-division manner, it is possible to switch between cultivation spaces illuminated with artificial light from the first light source panel 71a, cultivation spaces illuminated with artificial light from the second light source panel 72a, and cultivation spaces not illuminated with artificial light. Therefore, for plants in each cultivation space, it is possible to provide a period illuminated with artificial light from the first light source panel 71a, a period illuminated with artificial light from the second light source panel 72a having a different wavelength spectrum, and a period not illuminated with artificial light.

[0119] Figure 28 shows a state in which the plant 3 in the cultivation space 8A is irradiated with artificial light L output from the first light source panel 71a, a state in which the plant 3 in the cultivation space 8B is irradiated with artificial light L output from the second light source panel 72a, and a state in which the plant 3 in the cultivation space 8C is not irradiated with artificial light L. Figure 29 shows a state in which the plant 3 in the cultivation space 8A is not irradiated with artificial light L, a state in which the plant 3 in the cultivation space 8B is irradiated with artificial light L output from the second light source panel 72a, and a state in which the plant 3 in the cultivation space 8C is irradiated with artificial light L output from the first light source panel 71a. Figure 30 shows a state in which the plant 3 in the cultivation space 8A is irradiated with artificial light L output from the second light source panel 72a, a state in which the plant 3 in the cultivation space 8B is irradiated with artificial light L output from the first light source panel 71a, and a state in which the plant 3 in the cultivation space 8C is not irradiated with artificial light L. 28 to 30 are examples of how to use the plant growing device 101C, and other arrangements of the two pairs of light source panels 71a, 72a relative to the three growing spaces 8A, 8B, 8C are also possible.

[0120] The first light source panel 71a and the second light source panel 72a emit artificial light L having different wavelength spectra. Specifically, the first light source panel 71a emits visible light, and the second light source panel 72a emits at least ultraviolet light. That is, the first light source panel 71a may be the same as the above-described light source panel 7a, and the second light source panel 72a may emit only ultraviolet light, particularly UV-A with a wavelength of 315 to 400 nm, or may emit both visible light and UV-A. When the light source panel using the LED chips 33 shown in Figures 2 to 4 is used for the second light source panel 72a, all of the LED chips 33 may emit UV-A. Alternatively, some LED chips 33 may emit visible light, and some other LED chips 33 may emit UV-A. The material and thickness of the housing 60 are preferably designed to have high transmittance not only for visible light but also for UV-A. Even when an artificial light source other than an LED panel is used, the cultivation device 102 is provided with a first artificial light source that emits visible light and a second artificial light source that emits at least ultraviolet light.

[0121] Plants receive visible light and grow through photosynthesis. Visible light is essential for plant growth through photosynthesis. However, when plants receive UV-A, which has a wavelength of 315 to 400 nm, it can promote flower bud formation and produce beneficial substances. Examples of beneficial substances include antioxidants, which are produced by plants exposed to UV rays as a defense against UV radiation. For example, legumes exposed to UV rays produce large amounts of isoflavones, while lettuce, cabbage, broccoli, and other vegetables exposed to UV rays produce large amounts of anthocyanins. However, if a plant contains too many antioxidants, the taste and aroma of the plant can be impaired. Furthermore, if a plant expends too much energy producing antioxidants, growth through photosynthesis may be insufficient. The three cultivation spaces 8A, 8B, and 8C share a first light source panel 71a that emits visible light and a second light source panel 72a that emits at least ultraviolet light in a time-division manner, and by appropriately setting the period of UV-A irradiation to the plants 3 in the cultivation spaces 8A, 8B, and 8C, the plants in each cultivation space can properly perform photosynthesis and properly produce useful substances.

[0122] 31 to 33 are plan cross-sectional views of a plant cultivation device 101D according to yet another modification of the third embodiment. In the plant cultivation device 101D, an upper portion 102A of a cultivation device 102 has two cultivation spaces 8A, 8B arranged adjacent to each other along one direction. Two liquid fertilizer tanks 4A, 4B corresponding to the two cultivation spaces 8A, 8B are arranged in a lower portion 102B of the cultivation device 102. The combination of the cultivation space 8A and the liquid fertilizer tank 4A, and the combination of the cultivation space 8B and the liquid fertilizer tank 4B are arranged inside separate housings 60 arranged adjacent to each other. The cultivation device 102 has two pairs of light source panels (a pair of first light source panels 73a and a pair of second light source panels 74a). The first light source panel 73a and the second light source panel 74a are arranged along the longitudinal direction of the cultivation spaces 8A, 8B, but are arranged on different planes. The surface on which the first light source panel 73a is arranged is parallel to the surface on which the second light source panel 74a is arranged, so that the first light source panel 73a and the second light source panel 74a can move along the longitudinal direction of the growing spaces 8A and 8B without colliding with each other, as shown in Figures 31 to 33 .

[0123] In the plant cultivation device 101D, the first light source panel 73a or the second light source panel 74a is used depending on the growth stage of the plant 3. The horizontal length of the cultivation device 102 in the drawing is the same as the length of the cultivation device 102 in Figures 28 to 30 and is greater than the length of the three cultivation spaces. One end of the cultivation device 102 (the right end in the drawing) is used as a standby position 102F for the light source panel 73a or 74a that is not used to supply artificial light to the cultivation spaces 8A and 8B.

[0124] The first light source panel 73a and the second light source panel 74a emit visible light having different wavelength spectra. Specifically, the first light source panel 73a emits visible light, and the second light source panel 74a emits visible light with fewer blue wavelength components than the visible light emitted by the first light source panel 73a. For example, the first light source panel 73a may include an LED chip 33 that emits red wavelength light more strongly than light of other wavelengths, and an LED chip 33 that emits blue wavelength light more strongly than light of other wavelengths. In this case, the second light source panel 74a may include only an LED chip 33 that emits red wavelength light more strongly than light of other wavelengths. Even when an artificial light source other than an LED panel is used, the cultivation device 102 is provided with a first artificial light source that emits visible light and a second artificial light source that emits visible light with fewer blue wavelength components than the visible light emitted by the first artificial light source.

[0125] The two growing spaces 8A, 8B share the first light source panel 73a and the second light source panel 74a, and by using the first light source panel 73a and the second light source panel 74a in a time-division manner, it is possible to change the growing space to be illuminated with artificial light from the first light source panel 73a, the growing space to be illuminated with artificial light from the second light source panel 74a, and the growing space not illuminated with artificial light. Therefore, for plants in each growing space, it is possible to provide a period in which they are illuminated with artificial light from the first light source panel 73a, a period in which they are illuminated with artificial light from the second light source panel 74a having a different wavelength spectrum, and a period in which they are not illuminated with artificial light.

[0126] The movement control device 30 creates a first stage in which the second light source panel 74a is stopped at a standby position 102F where the second light source panel 74a cannot supply artificial light to either of the cultivation spaces 8A, 8B, and the first light source panel 73a is moved relatively to either of the cultivation spaces 8A, 8B. The movement control device 30 also creates a second stage in which the first light source panel 73a is stopped at a standby position 102F where the first light source panel 73a cannot supply artificial light to either of the cultivation spaces 8A, 8B, and the second light source panel 74a is moved to either of the cultivation spaces 8A, 8B.

[0127] 31 and 32 show a first stage in which the second light source panel 74a is stopped at the standby position 102F and the first light source panel 73a is moved relative to the growing spaces 8A and 8B. In FIG. 31, the growing space 8A is set to a daytime state by the first light source panel 73a, and the growing space 8B is set to a nighttime state. In FIG. 32, the growing space 8B is set to a daytime state by the first light source panel 73a, and the growing space 8A is set to a nighttime state. In FIG. 33, the first light source panel 73a is stopped at the standby position 102F and the second light source panel 74a is moved relative to the growing spaces 8A and 8B. In FIG. 33, the growing space 8A is set to a daytime state by the second light source panel 74a, and the growing space 8B is set to a nighttime state. Although not shown, when the second light source panel 74a moves relatively, the second light source panel 74a sets the cultivation space 8B to a daytime state and the cultivation space 8A to a nighttime state. The light source panel 73a or 74a stopped at the standby position 102F may be turned off by the light emission control device 18.

[0128] As described above, it is economically preferable to change the plant growth environment to one that suppresses plant photosynthesis. Light source devices (e.g., LED chips 33) that emit short-wavelength (e.g., blue) artificial light consume high power, while light source devices that emit long-wavelength (e.g., red) artificial light consume low power. This is because, for the same number of photons, short-wavelength light has a high energy content, while long-wavelength light has a low energy content. By sharing the first light source panel 73a and the second light source panel 74a, which emit visible light with different wavelength spectra, among the three growth spaces 8A and 8B in a time-sharing manner, it is possible to easily create an environment in each growth space suitable for the growth stage. That is, before the plants have fully grown, the first light source panel 73a, which emits visible light with a wide wavelength range, can be moved relative to the growth spaces 8A and 8B to switch between daytime and nighttime operation in the growth spaces 8A and 8B. On the other hand, when the plants have grown sufficiently, the second light source panel 74a, which emits artificial light with a small blue wavelength component, can be moved relatively to the growth spaces 8A and 8B to switch between daytime and nighttime in the growth spaces 8A and 8B. This allows the use of light source panels appropriate for the growth stage of the plants. Before the plants have grown sufficiently, the second light source panel 74a may be turned off, and after the plants have grown sufficiently, the first light source panel 73a may be turned off. However, because the switching between daytime and nighttime in each growth space is achieved by the relative movement of one of the light source panels, the number of times the light source panels 73a and 74a are turned on and off can be reduced.

[0129] Because multiple growing spaces 8A, 8B share the first light source panel 73a and the second light source panel 74a, the number of first light source panels 73a does not need to correspond to the number of growing spaces 8A, 8B. The number of second light source panels 74a also does not need to correspond to the number of growing spaces 8A, 8B. Although a pair of first light source panels 73a and a pair of second light source panels 74a are arranged on both sides of the two growing spaces 8A, 8B, it is not necessary to provide two first light source panels 73a corresponding to the two growing spaces 8A, 8B, and it is also not necessary to provide two second light source panels 74a. Therefore, an increase in the number of light source panels can be prevented.

[0130] In any of the above-described modified examples, the environmental control device 20 may control the growth space where the artificial light source irradiates visible light (corresponding to daytime) to an environment that promotes plant photosynthesis. Also, the environmental control device 20 may control the growth space where the artificial light source does not irradiate visible light (corresponding to nighttime) to an environment that suppresses plant photosynthesis.

[0131] 31 to 33 , in a plant growing device 101D according to a modified example, the environmental control device 20 may control both of the growing spaces 8A and 8B to an environment that promotes plant photosynthesis during a first stage in which the movement control device 30 moves the first light source panel 73a relative to the growing spaces 8A and 8B. The environmental control device 20 may control both of the growing spaces 8A and 8B to an environment that suppresses plant photosynthesis during a second stage in which the movement control device 30 moves the second light source panel 74a relative to the growing spaces 8A and 8B. In this case, during the first stage, which corresponds to a stage before plants have fully grown and in which the first light source panel 73a, which emits visible light with a wide wavelength range, switches the growing spaces 8A and 8B between daytime and nighttime, the growing spaces 8A and 8B are controlled to an environment that promotes plant photosynthesis. On the other hand, in the second stage, which corresponds to the stage when the plants are fully grown, the second light source panel 74a, which emits artificial light with a small blue wavelength component, switches the growth spaces 8A, 8B between daytime and nighttime, and the growth spaces 8A, 8B are controlled to an environment that suppresses plant photosynthesis. As described above, an environment that suppresses plant photosynthesis typically requires low operating costs, so the operating costs for the stage when the plants are fully grown can be reduced. In the first and second stages, the environmental control device 20 may control the growth space 8A or 8B that receives visible light to an environment that more promotes photosynthesis than the growth space 8B or 8A that does not receive visible light.

[0132] Figures 34 and 35 show a plant growing device 111 according to a fourth embodiment of the present invention. In Figures 34 and 35, the same reference numerals are used to indicate components common to the third embodiment, and these components will not be described in detail. The plant growing device 111 has a cultivation device 112 for growing multiple plants. The cultivation device 112 has an upper portion 112A and a lower portion 112B disposed below the upper portion 112A. In the plant growing device 111, a single light source panel (artificial light source) 77 is disposed above the growing spaces 8A and 8B arranged adjacent to each other. In other words, the light source panel 77a is disposed near and outside the two housings 60 corresponding to the growing spaces 8A and 8B, respectively.

[0133] Two liquid fertilizer tanks 4A, 4B corresponding to the two growing spaces 8A, 8B are arranged in the lower part 112B of the cultivation device 112. The combination of the growing space 8A and the liquid fertilizer tank 4A, and the combination of the growing space 8B and the liquid fertilizer tank 4B are arranged inside separate housings 60 lined up adjacent to each other. A lower space 112D in which the liquid fertilizer tank 4A or 4B is arranged is provided in the lower part of each housing 60. In this embodiment, the above-ground portions (i.e., stems and leaves) of multiple plants 3 grow (are cultivated) in each of the growing spaces 8A, 8B. However, the above-ground portion of only one plant 3 may grow in each of the growing spaces 8A, 8B.

[0134] As in the third embodiment, each housing 60 defines a closed growth space 8A or 8B. The housing 60 is made of a light-transmitting material, such as glass or transparent resin. Each housing 60 has an upper wall (heat-shielding partition wall) 60b interposed between the growth space 8A or 8B and the light source panel 77a. The upper wall 60b is flat and disposed horizontally so as to be parallel to the light source panel 77a.

[0135] The light source panel 77a emits artificial light L for growing the plants 3. The light source panel 77a is disposed above the growth spaces 8A, 8B, and supplies the artificial light L from above to the plants 3 in the growth spaces 8A, 8B. The plant growth device 111, which irradiates the artificial light L from above downward in this manner, is suitable for applying the artificial light L to plants 3 at a growth stage in which the plants have leaves that spread widely in the horizontal or diagonal directions compared to their height. The light source panel 77a is disposed so as to be shared by the plurality of growth spaces 8A, 8B, and supplies the artificial light L to the growth spaces 8A, 8B. However, the growth spaces 8A, 8B use these light source panels 77a in a time-division manner (i.e., at different periods).

[0136] The housing 60, particularly the upper wall 60b, suppresses or inhibits heat radiation and heat conduction from the light source panel 77a, which is a heat source, to prevent overheating of the growing spaces 8A and 8B. In this embodiment, each housing 60 surrounds the entire growing space 8A or 8B. However, each housing 60 does not necessarily have to surround the entire growing space 8A or 8B. For example, the end walls of each housing 60 may be omitted, and the side walls do not have to be transparent. The portion of each housing 60 that is present in the lower part 112B and surrounds the liquid fertilizer tank 4A or 4B does not have to be transparent either.

[0137] As in the third embodiment, in order to prevent overheating of each light source panel 77a, any one of a blower (not shown), a refrigerant pipe or refrigerant chamber (not shown), and fins (not shown) may be provided.

[0138] The height from the plant support panel 5 to the upper wall 60b of the housing 60 is set to a size that allows artificial light L to be applied substantially evenly and sufficiently to each leaf of the plant 3 that has grown to a certain extent. However, the height of the upper wall 60b is preferably set to restrict excessive vertical growth of the plant 3. That is, the height of the upper wall 60b relative to the plant 3 is preferably determined so that the upper wall 60b restricts the growth of the leaves of the plant 3 cultivated within the growing spaces 8A and 8B toward the light source panel 77a. Specifically, the height of the upper wall 60b is preferably set to be smaller than the maximum height that the upper ends of the leaves of the plant 3 are expected to reach if the housing 60 is not present and the leaves grow to their maximum extent. In this case, the upper wall 60b restricts excessive leaf growth of the plant 3, allowing the plant 3 to be grown in a small space (small height).

[0139] The movement control device 30 controls a movement mechanism (not shown) to move the light source panel 77a relative to the housing 60 (i.e., to move the light source panel 77a relative to the growing spaces 8A and 8B). The light source panel 77a is arranged so as to be shared by both the growing spaces 8A and 8B. The movement control device 30 moves the light source panel 77a relative to the housing 60 and the growing spaces 8A and 8B so as to alternately create periods in which the plants 3 in one of the growing spaces 8A and 8B are irradiated with artificial light L output from the light source panel 77a and periods in which the plants 3 in the other of the growing spaces 8A and 8B are not irradiated with artificial light L. In addition, the growing spaces irradiated with artificial light and those not irradiated with artificial light can be alternated. By sharing the light source panel 77a between the two cultivation spaces 8A and 8B and using the light source panel 77a in a time-division manner, it is possible to simultaneously place one of the cultivation spaces 8A and 8B in an environment irradiated with artificial light L from the light source panel 77a and place the other of the cultivation spaces 8A and 8B in an environment not irradiated with artificial light L. Figure 35 shows a state in which the plant 3 in the cultivation space 8A is irradiated with artificial light L output from the light source panel 77a, while the plant 3 in the cultivation space 8B is not irradiated with artificial light L. Although not shown, it is also possible to conversely irradiate the plant 3 in the cultivation space 8B with artificial light L output from the light source panel 77a, while not irradiating the plant 3 in the cultivation space 8A with artificial light L. In this way, periods in which artificial light is irradiated and periods in which it is not irradiated can be alternated for the plants in each cultivation space.

[0140] The movement control device 30 may move the light source panel 77a from the vicinity of one of the growing spaces 8A, 8B to the vicinity of the other in a 12-hour cycle, for example. In this case, in each of the growing spaces 8A, 8B, 12 hours of the day are daylight and the other 12 hours are night. However, the movement control device 30 may move the light source panel 77a from one of the growing spaces 8A, 8B to the other in other cycles. For example, even if the light source panel 77a is moved from one of the growing spaces 8A, 8B to the other in a 6-hour cycle, a 4-hour cycle, or a 3-hour cycle, each of the growing spaces 8A, 8B will have a total of 12 hours of daylight and a total of 12 hours of night.

[0141] According to this embodiment, the housing 60 thermally isolates the growing spaces 8A, 8B from the light source panel 77a, making them less susceptible to the heat. That is, the housing 60 prevents the growing spaces 8A, 8B from overheating. This reduces the energy required by the air conditioning system 12 to control the air temperature in the growing spaces 8A, 8B, and makes it easier to control the growing spaces 8A, 8B to an environment suitable for the plants being grown.

[0142] Furthermore, by moving the light source panel 77a relative to the growing spaces 8A and 8B using the movement control device 30, it is possible to simultaneously create a state in which plants in one of the growing spaces 8A and 8B are illuminated with artificial light (a state corresponding to daytime) and a state in which plants in the other of the growing spaces 8A and 8B are not illuminated (a state corresponding to nighttime). That is, by sharing the light source panel 77a among multiple growing spaces 8A and 8B and using the light source panel 77a in a time-division manner (i.e., at different periods), it is possible to simultaneously place one of the growing spaces 8A and 8B in an artificial light-illuminated environment and the other of the growing spaces 8A and 8B in an artificial light-unilluminated environment. Furthermore, by switching between the growing spaces illuminated with artificial light and the growing spaces not illuminated with artificial light, it is possible to alternate periods in which plants in each growing space are illuminated with artificial light and periods in which they are not illuminated with artificial light. The number of light source panels 77a does not need to correspond to the number of growing spaces 8A and 8B. In this embodiment, a single light source panel 77a can be used to simultaneously realize a daytime state in one of the two growing spaces 8A, 8B and a nighttime state in the other of the growing spaces 8A, 8B, thereby preventing an increase in the number of light source panels 77a.

[0143] Furthermore, because the light source panel 77a is used by the multiple growing spaces 8A and 8B in a time-sharing manner, the light source panel 77a can be continuously driven. This reduces the number of times the light source panel 77a is turned on and off, thereby shortening the period of non-use of the light source panel 77a. Furthermore, if the artificial light source is a fluorescent lamp or a cold cathode fluorescent tube, this reduces malfunctions caused by on-off switching and saves power consumption. However, the light source panel 77a does not need to be driven continuously. Many types of plants flower by sensing changes in photoperiod. Therefore, even if the light source panel 77a is moved from the vicinity of one of the growing spaces 8A and 8B to the vicinity of the other in a 12-hour cycle, for example, an off period during which the light source panel 77a does not emit light may be set to accommodate the change in photoperiod.

[0144] The movement control device 30 moves the light source panel 77a relative to the fixed growing spaces 8A, 8B along the longitudinal direction of the growing spaces 8A, 8B. However, the movement control device 30 may move the housing 60 that surrounds the growing spaces 8A, 8B and the liquid fertilizer tanks 4A, 4B along the longitudinal direction of the growing spaces 8A, 8B without moving the light source panel 77a. In either case, the movement control device 30 moves the light source panel 77a relative to the housing 60. The above-described variations on the third embodiment may be applied to this embodiment.

[0145] Next, a plant cultivation device according to a fifth embodiment of the present invention will be described with reference to Figures 36 to 41. In Figures 36 to 41, the same reference numerals are used to indicate components common to the third embodiment, and these components will not be described in detail. As shown in Figure 36, the plant cultivation device 200 according to the fifth embodiment has multiple cultivation units 202A and 202B. The cultivation units 202A and 202B are arranged alternately. Each of the cultivation units 202A and 202B has a housing unit 61, a plant support panel 5, and a liquid fertilizer tank unit 90. As shown in Figures 36 and 37, the plant cultivation device 200 has a light source support unit 80, multiple housing units 61, plant support panels 5, multiple liquid fertilizer tank units 90, and a lower housing 95. In Figure 36, the light source support unit 80 is shown in phantom lines, and the outline of the light source support unit 80 coincides with the lower housing 95.

[0146] The light source support unit 80 is arranged so as to be shared by the multiple cultivation units 202A, 202B and covers the multiple housing units 61 in the cultivation units 202A, 202B. The lower housing 95 is also arranged so as to be shared by the multiple cultivation units 202A, 202B and covers the multiple liquid fertilizer tank units 90 in the cultivation units 202A, 202B. A lower space 102D is provided inside the lower housing 95, in which multiple liquid fertilizer tank units 90 are arranged. The multiple housing units 61 and the multiple liquid fertilizer tank units 90 are aligned in the vertical direction relative to the plane of FIG. 37 . A plant support panel 5 is provided in each of the multiple cultivation units 202A, 202B and aligned in the vertical direction relative to the plane of FIG. 37 . The plant support panel 5 is interposed between one liquid fertilizer tank unit 90 and one housing unit 61 and extends horizontally. The plant support panel 5 is not shown in FIG. 36 .

[0147] See the exploded cross-sectional view of Figure 38. The light source support unit 80 is made of a rigid material and has a top wall 81, side walls 82, partition walls 83, and end walls 84. The side walls 82 are arranged parallel to each other on both sides of the light source support unit 80, extend in the vertical direction, and are connected to the top wall 81. The partition wall 83 is arranged parallel to the side wall 82, extend in the vertical direction, and is connected to the top wall 81. The end wall 84 is arranged perpendicular to the side wall 82 and the partition wall 83, extend in the vertical direction, and is connected to the top wall 81. A space 85 is provided between the side wall 82 and the partition wall 83, and a space 85 is also provided between the pair of partition walls 83.

[0148] A pair of light source panels 7a are arranged in each space 85. One light source panel 7a is supported on the inner surface of the side wall 82, and a light source panel 7a is supported on each of both surfaces of the partition wall 83. The light source panel 7a is movable in the direction perpendicular to the paper surface of Figures 37 and 38 (the vertical direction in Figure 36) by a movement mechanism (not shown). In this embodiment, the light source panel 7a is supported by the side wall 82 and the partition wall 83. However, the light source panel 7a may also be movably supported on the lower surface of the upper wall 81, i.e., on the ceiling surface 86 of each space 85.

[0149] Each housing unit 61 includes a plurality of housings 61A, each corresponding to the housing 60 of the third and fourth embodiments. Each housing 61A is formed from a light-transmitting material, such as glass or transparent resin. A growing space 62 is defined within each housing 61A. The above-ground portions of multiple plants 3 grow (are cultivated) in each growing space 62. However, the above-ground portion of only one plant 3 may grow in each growing space 62. Each housing 61A includes a pair of side walls 63, a top wall 65, and an end wall 66, which define the growing space 62. The side walls 63 are arranged parallel to each other, extend vertically, and are connected to the top wall 65. The end wall 66 is arranged perpendicular to the side walls 63, extend vertically, and are connected to the top wall 65. The lower ends of adjacent housings 61A are connected by a horizontal connecting wall 67.

[0150] The trunks of multiple plants 3 pass through each plant support panel 5, and each plant support panel 5 supports these plants 3.

[0151] The liquid fertilizer tank unit 90 has a plurality of liquid fertilizer tanks 91 and pipes 92 connecting these liquid fertilizer tanks 91. Liquid fertilizer can circulate between the plurality of liquid fertilizer tanks 91 through the pipes 92. The roots of one plant 3 are placed inside each liquid fertilizer tank 91, and the roots grow therein.

[0152] The plant growing device 200 is assembled from the disassembled state shown in Figure 38 as shown in Figure 39. During assembly, seedlings of plants 3 are inserted into the holes in the plant support panels 5, and the roots of the seedlings of plants 3 are placed in the liquid fertilizer tanks 91 of the liquid fertilizer tank units 90. The liquid fertilizer tank units 90 are placed in the lower space 102D inside the lower housing 95. During assembly, the above-ground portions of the seedlings of plants 3 are placed in the growing spaces 62 inside each housing 61A of the housing unit 61. Each housing 61A is placed in the space 85 of the light source support unit 80, and light source panels 7a are placed on both sides of each housing 61A.

[0153] After the stage shown in Figure 39, the plant 3 is grown in the plant growing device 200. As shown in Figure 37, once the plant 3 has grown, the light source support unit 80 is removed. Then, as shown in Figure 40, the housing unit 61 is moved upward. This makes it possible to harvest.

[0154] As shown in FIG. 36 , the plant growing device 200 has a nutrient solution supply system 10 , an air conditioning system 12 , a light emission control device 18 and a movement control device 30 .

[0155] In Figure 36, the open arrows indicate the flow of liquid fertilizer supplied from the nutrient solution supply system 10 and collected back into the nutrient solution supply system 10. The liquid fertilizer first flows from the nutrient solution supply system 10 into the liquid fertilizer tank unit 90 of the cultivation unit 202A, which is closest to the nutrient solution supply system 10. In the liquid fertilizer tank units 90, the liquid fertilizer tanks 91 are connected by pipes 92, so that the liquid fertilizer is distributed throughout all of the liquid fertilizer tanks 91. In the cultivation unit 202A, the liquid fertilizer flows from left to right in Figure 36. Next, the liquid fertilizer flows from the liquid fertilizer tank unit 90 of the cultivation unit 202A into the liquid fertilizer tank unit 90 of the adjacent cultivation unit 202B. Here too, the liquid fertilizer is distributed throughout all of the liquid fertilizer tanks 91. In the cultivation unit 202B, the liquid fertilizer flows from right to left in Figure 36. Next, the liquid fertilizer flows from the liquid fertilizer tank unit 90 of the cultivation unit 202B into the liquid fertilizer tank unit 90 of the adjacent cultivation unit 202A. Here too, the liquid fertilizer is distributed throughout all of the liquid fertilizer tanks 91. In the cultivation unit 202A, the liquid fertilizer flows from left to right in FIG. 36 .

[0156] Next, the liquid fertilizer flows from the liquid fertilizer tank unit 90 of the cultivation unit 202A into the liquid fertilizer tank unit 90 of the cultivation unit 202B, which is the farthest from the liquid fertilizer tank unit 90. Here too, the liquid fertilizer is distributed throughout all of the liquid fertilizer tanks 91. In the cultivation unit 202B, the liquid fertilizer flows from right to left in Figure 36. Finally, the liquid fertilizer is collected into the nutrient solution supply system 10 from the liquid fertilizer tank unit 90 of the cultivation unit 202B, which is the farthest from the liquid fertilizer tank unit 90. In this way, the liquid fertilizer flows through the liquid fertilizer tanks 91 in all of the cultivation units 202A and 202B.

[0157] As described above, the liquid fertilizer tanks 91 are connected to each liquid fertilizer tank unit 90 by pipes 92, so that liquid fertilizer is distributed throughout all of the liquid fertilizer tanks 91. Therefore, each liquid fertilizer tank unit 90 can be considered as a single liquid fertilizer tank that contains liquid fertilizer and in which the roots of multiple plants 3 are placed. The nutrient solution supply system (liquid fertilizer control system) 10 controls at least one of the concentration and temperature of the liquid fertilizer inside the liquid fertilizer tank unit 90. The liquid fertilizer tank unit 90 is shared by multiple cultivation spaces 62 that correspond to multiple housings 61A, respectively. Therefore, control of the liquid fertilizer can be simplified compared to when a liquid fertilizer tank is provided for each of the multiple cultivation spaces 62 and the concentration or temperature of the liquid fertilizer inside these liquid fertilizer tanks is controlled.

[0158] 36 and 37 , the black arrows indicate the flow of air supplied from and collected by the air conditioning system 12. The air first flows from the air conditioning system 12 into the lower space 102D of the lower housing 95. The plant support panel 5 is breathable, and there are gaps around the liquid fertilizer tank 91 that allow ventilation. Therefore, as shown in FIG. 41 , air can flow from the lower space 102D into the growing spaces 62 inside each housing 61A and can also flow from the growing spaces 62 inside each housing 61A into the lower space 102D. The air that has circulated through the multiple growing spaces 62 in this way is collected by the air conditioning system 12.

[0159] The light emission control device 18 controls the light emission of the light source panel 7a. For example, the light emission control device 18 turns the light source panel 7a on and off.

[0160] The movement control device 30 controls a movement mechanism (not shown) to synchronously move the plurality of light source panels 7a back and forth in the vertical direction of FIG. 36 . As shown in FIG. 36 , the period when the light source panel 7a stops at the cultivation unit 202A and illuminates the growing space 62 inside the housing 61A in the cultivation unit 202A is a daytime period for the plants 3 in these growing spaces 62. This period is a nighttime period for the plants 3 in these growing spaces 62 because the growing space inside the housing 61A in the cultivation unit 202B is not illuminated. Although not shown, the period when the moved light source panel 7a stops at the cultivation unit 202B and illuminates the growing space 62 inside the housing 61A in the cultivation unit 202B is a daytime period for the plants 3 in these growing spaces 62. This period is a nighttime period for the plants 3 in these growing spaces 62 because the growing space inside the housing 61A in the cultivation unit 202A is not illuminated.

[0161] In this way, it is possible to create periods when the plants in each growing space 62 are irradiated with artificial light (periods corresponding to daytime) and periods when they are not irradiated with artificial light (periods corresponding to nighttime). In addition, by sharing the light source panel 7a among the multiple growing spaces 62 of the cultivation units 202A and 202B and using the light source panel 7a in a time-division manner (i.e., at different periods), it is possible to simultaneously place the growing space 62 of the cultivation unit 202A or 202B in an environment irradiated with artificial light and the growing space 62 of the cultivation unit 202B or 202A in an environment not irradiated with artificial light.

[0162] In this embodiment, the air conditioning system 12 circulates air through all of the growing spaces 62 of the cultivation units 202A and 202B, and the nutrient solution supply system 10 circulates liquid fertilizer through all of the liquid fertilizer tanks 91 of the cultivation units 202A and 202B. However, the air conditioning system 12 may separately control the air conditioning of the growing spaces 62 of the cultivation units 202A and 202B. Furthermore, the nutrient solution supply system 10 may separately control the liquid fertilizer concentration in the liquid fertilizer tank unit 90 of the cultivation unit 202A and the liquid fertilizer concentration in the liquid fertilizer tank unit 90 of the cultivation unit 202B. In this case, the environmental control can be adapted to the daytime and nighttime conditions described above. Furthermore, the environmental control can also be adapted to the growth stage of the plants 3 described above.

[0163] Although the present invention has been shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that changes may be made in form and detail without departing from the scope of the invention as set forth in the appended claims. Such changes, modifications and alterations are intended to be included within the scope of the invention.

[0164] The movement control device 30 and the environmental control device 20 are not limited to computer processors. Instead of a processor, all or part of them may be executed by hardware, or may be executed by a programmable logic device such as an FPGA (Field Programmable Gate Array) or a DSP (Digital Signal Processor).

[0165] The above embodiments and modifications may be combined as long as they are not inconsistent.

[0166] Aspects of the present invention are also described in the following numbered clauses: Clause 1. A plant growing device for growing plants, comprising: at least one growing space in which an above-ground portion of at least one plant is grown; at least one artificial light source disposed near the growing space and emitting artificial light for growing the plant; a heat-shielding partition wall formed from a light-transmitting material and interposed between the growing space and the artificial light source; and a movement control device that moves the artificial light source relative to the growing space so as to create a state in which the plant in the growing space is irradiated with the artificial light output from the artificial light source and a state in which the plant in the growing space is not irradiated with the artificial light output from the artificial light source.

[0167] Clause 2. The plant growing device of Clause 1, comprising a plurality of the growing spaces arranged adjacent to each other, with the above-ground portion of at least one plant being grown in each of the growing spaces, the artificial light source being arranged so as to be shared by the plurality of growing spaces, and the movement control device simultaneously creating a state in which a plant in one of the growing spaces is irradiated with artificial light output from the artificial light source and a state in which a plant in another of the growing spaces is not irradiated with artificial light output from the artificial light source, and moving the artificial light source relative to the plurality of growing spaces so as to alternate between growing spaces in which plants are irradiated with the artificial light and those in which plants are not irradiated. By moving the artificial light source relative to the plurality of growing spaces, it is possible to simultaneously achieve a state in which plants in one growing space are irradiated with artificial light (a state corresponding to daytime) and a state in which plants in other growing spaces are not irradiated (a state corresponding to nighttime). In addition, it is possible to alternate between growing spaces irradiated with artificial light and those not irradiated with artificial light. That is, by having multiple growth spaces share at least one artificial light source and using the artificial light source in a time-sharing manner (i.e., at different periods), it is possible to simultaneously place one growth space in an artificially lit environment and another growth space in an artificially lit environment. By switching between growth spaces lit with artificial light and those not lit with artificial light, it is possible to provide periods in which plants in each growth space are lit with artificial light and periods in which they are not. By having multiple growth spaces share at least one artificial light source, the number of artificial light sources does not need to correspond to the number of growth spaces. This prevents an increase in the number of artificial light sources. Furthermore, since multiple growth spaces use the artificial light source in a time-sharing manner, the artificial light source can be continuously operated. This reduces the number of times the artificial light source is turned on and off, shortening the period of non-use. Depending on the type of light source, this can reduce malfunctions caused by on-off switching and save power consumption.

[0168] Clause 3. The plant cultivation device according to Clause 2, wherein the heat-insulating partition wall has a length equal to or greater than the total length of the plurality of cultivation spaces, is disposed near the plurality of cultivation spaces, and extends along the plurality of cultivation spaces, and the movement control device moves the artificial light source relative to the cultivation spaces while the heat-insulating partition wall is stationary relative to the plurality of cultivation spaces. In this case, the heat-insulating partition wall has a length equal to or greater than the total length of the plurality of cultivation spaces and is stationary relative to the cultivation spaces. Therefore, even if the artificial light source moves relative to the cultivation spaces, the heat-insulating partition wall will not collide with or slide against the plants inside the cultivation spaces, and no damage will be caused to the plants due to impact or friction.

[0169] Clause 4. The plant cultivation device according to Clause 3, wherein the heat-shielding partition is positioned to restrict the growth of above-ground parts of plants cultivated inside the cultivation space in a direction toward the artificial light source. In this case, the heat-shielding partition is stationary relative to the cultivation space and does not collide with or slide against the plants inside the cultivation space, preventing damage to the plants due to impact or friction. Furthermore, because the heat-shielding partition restricts excessive growth of above-ground parts of plants (stems and / or leaves), plants can be cultivated in a small space.

[0170] Clause 5. The plant growing device according to Clause 3 or 4, further comprising a heat-shielding case surrounding the artificial light source, the heat-shielding case having a length equal to or greater than the total length of the plurality of growing spaces, being disposed in the vicinity of the plurality of growing spaces, extending along the plurality of growing spaces, and having the heat-shielding partition walls. In this case, the heat-shielding partition walls of the heat-shielding case surrounding the artificial light source reliably prevent the growing spaces from overheating.

[0171] Clause 6. The plant growing device according to Clause 1 or 2, wherein the movement control device moves the artificial light source and the heat-insulating partition together relative to the growing space. In this case, the heat-insulating partition does not need to have a length equivalent to the total length of the plurality of growing spaces. Furthermore, if the heat-insulating partition is configured to surround the artificial light source, the structure of the movement mechanism may be simple.

[0172] Clause 7. The plant cultivation device of Clause 1, comprising at least one housing formed from a light-transmitting material, defining the at least one cultivation space and enclosing the at least one cultivation space, wherein the at least one artificial light source is disposed outside the housing, and the housing has the heat-insulating partition. In this case, the artificial light source is disposed outside the housing having the heat-insulating partition, and the cultivation space within the housing is reliably thermally separated from the artificial light source by the heat-insulating partition. The heat-insulating partition provided on the housing is stationary relative to the cultivation space inside the housing and does not collide with or slide against the plants inside the cultivation space, thereby preventing damage to the plants due to impact or friction.

[0173] Clause 8. The plant growing device according to Clause 7, wherein the movement control device moves the artificial light source.

[0174] Clause 9. The plant growing device according to Clause 7, wherein the movement control device moves the housing.

[0175] Clause 10. The plant growing device according to any one of Clauses 7 to 9, wherein the heat-shielding partition wall of the housing is positioned to restrict the growth of above-ground parts of plants grown inside the growing space in a direction toward the artificial light source. In this case, the heat-shielding partition wall restricts excessive growth of above-ground parts of plants (stems and / or leaves), allowing plants to be grown in a small space.

[0176] Clause 11. The plant growing device according to any one of Clauses 7 to 10, comprising a plurality of housings arranged adjacent to each other, each defining a plurality of growing spaces and enclosing the plurality of growing spaces; the artificial light source is arranged so as to be shared by the plurality of growing spaces corresponding to the plurality of housings; and the movement control device moves the artificial light source relative to the plurality of growing spaces so that artificial light output from the artificial light source is supplied to different growing spaces at different periods. In this case, the plurality of growing spaces share at least one artificial light source, and by using the artificial light source in a time-sharing manner (i.e., at different periods), it is possible to simultaneously place one growing space in an environment illuminated by artificial light and another growing space in an environment not illuminated by artificial light. Furthermore, by switching between the growing spaces illuminated by artificial light and the growing spaces not illuminated by artificial light, it is possible to provide periods in which plants in each growing space are illuminated by artificial light and periods in which they are not illuminated by artificial light. By sharing at least one artificial light source among the plurality of growing spaces, the number of artificial light sources does not need to correspond to the number of growing spaces. For example, one artificial light source can be used to simultaneously realize a daytime state in one cultivation space and a nighttime state in another cultivation space. This prevents an increase in the number of artificial light sources. Furthermore, since multiple cultivation spaces use the artificial light source in a time-sharing manner, the artificial light source can be continuously operated. This reduces the number of times the artificial light source is turned on and off, shortening the period during which the artificial light source is not in use. Depending on the type of light source, this can reduce malfunctions caused by on-off switching and save power consumption.

[0177] Clause 12. The plant cultivation device according to Clause 11, comprising: a liquid fertilizer tank that stores liquid fertilizer and in which roots of a plurality of plants are placed; and a liquid fertilizer control system that controls at least one of the concentration and temperature of the liquid fertilizer in the liquid fertilizer tank, wherein the liquid fertilizer tank and the liquid fertilizer control system are used in common for the plurality of cultivation spaces corresponding to the plurality of casings, respectively. In this case, by using the liquid fertilizer tank and the liquid fertilizer control system in common for the plurality of cultivation spaces, control of the liquid fertilizer can be simplified.

[0178] Clause 13. The plant cultivation device according to any one of Clauses 2 to 5, 11 and 12, wherein the at least one artificial light source comprises a first artificial light source and a second artificial light source, the first artificial light source and the second artificial light source emitting artificial light having different wavelength spectra from each other, the first artificial light source and the second artificial light source being arranged to be shared by the plurality of cultivation spaces, and the movement control device moves the first artificial light source and the second artificial light source relative to the plurality of cultivation spaces so as to create, for plants in each cultivation space, a period in which they are irradiated with the artificial light output from the first artificial light source, a period in which they are irradiated with the artificial light output from the second artificial light source, and a period in which they are not irradiated with artificial light. In this case, by sharing the first artificial light source and the second artificial light source among multiple cultivation spaces and using the first artificial light source and the second artificial light source in a time-division manner, it is possible to provide, for each cultivation space, a period in which it is irradiated with artificial light from the first artificial light source, a period in which it is irradiated with artificial light from the second artificial light source having a different wavelength spectrum, and a period in which it is not irradiated with artificial light. Furthermore, it is possible to change the cultivation space irradiated with artificial light from the first artificial light source, the cultivation space irradiated with artificial light from the second artificial light source, and the cultivation space not irradiated with artificial light.

[0179] Clause 14. The plant cultivation device according to Clause 13, wherein the first artificial light source emits visible light, and the second artificial light source emits at least ultraviolet light. Visible light is essential for plant growth through photosynthesis. However, exposure of plants to UV-A, which has a wavelength of 315 to 400 nm, can promote flower bud formation and produce beneficial substances (e.g., antioxidants). By sharing a first artificial light source emitting visible light and a second artificial light source emitting at least ultraviolet light among multiple cultivation spaces in a time-sharing manner and appropriately setting the duration of ultraviolet irradiation of plants in each cultivation space, plants in each cultivation space can properly perform photosynthesis and properly produce beneficial substances. Here, the second artificial light source may emit not only ultraviolet light but also visible light.

[0180] Clause 15. The plant cultivation device according to any one of clauses 2 to 5 and 11 to 14, further comprising an environmental control device that controls the cultivation space, to which the artificial light source irradiates visible light, to an environment that promotes plant photosynthesis, and that controls the cultivation space, to which the artificial light source does not irradiate visible light, to an environment that suppresses plant photosynthesis. In this case, during the period corresponding to daytime when the cultivation space receives visible light, the cultivation space is controlled to an environment that promotes plant photosynthesis. On the other hand, during the period corresponding to nighttime when the cultivation space does not receive visible light, the cultivation space is controlled to an environment that suppresses plant photosynthesis. Typically, an environment that suppresses plant photosynthesis requires lower operating costs, so nighttime operating costs can be reduced.

[0181] Clause 16. The plant growing device according to Clause 13, wherein the first artificial light source emits visible light, and the second artificial light source emits visible light having fewer blue wavelength components than the visible light emitted by the first artificial light source, and the movement control device creates a first step of stopping the second artificial light source at a standby position where the second artificial light source cannot supply artificial light to any of the plurality of growing spaces and moving the first artificial light source relative to the plurality of growing spaces, and a second step of stopping the first artificial light source at the standby position where the first artificial light source cannot supply artificial light to any of the plurality of growing spaces and moving the second artificial light source relative to the plurality of growing spaces. When a plant has grown sufficiently, it no longer needs to grow branches and leaves, and the rate of photosynthesis slows, thereby reducing the amount of light required for growth. Therefore, from an economic perspective, it is preferable to change the plant growing environment to one that suppresses plant photosynthesis. Light source devices emitting short-wavelength (e.g., blue wavelength) artificial light consume large amounts of power, while light source devices emitting long-wavelength (e.g., red wavelength) artificial light consume small amounts of power. Therefore, before the plants have fully grown, it is preferable to relatively move a first artificial light source emitting visible light with a wide wavelength component among the multiple growth spaces to switch between daytime and nighttime in each growth space (a first stage). After the plants have fully grown, it is preferable to relatively move a second artificial light source emitting artificial light with a small blue wavelength component among the multiple growth spaces to switch between daytime and nighttime in each growth space (a second stage). This allows the use of light sources appropriate for the growth stage of the plants. Before the plants have fully grown, the second artificial light source may be turned off, and after the plants have fully grown, the first artificial light source may be turned off. However, since the switching between daytime and nighttime in each growth space is achieved by relatively moving one of the artificial light sources, the number of times the artificial light sources are turned on and off can be reduced.

[0182] Clause 17. The plant cultivation device according to Clause 16, further comprising an environmental control device that, in the first stage, controls the multiple cultivation spaces to an environment that promotes plant photosynthesis, and that, in the second stage, controls the multiple cultivation spaces to an environment that suppresses plant photosynthesis. In this case, in the first stage, which corresponds to a stage before plants have fully grown, and in which a first artificial light source emitting visible light with a wide wavelength component switches the multiple cultivation spaces between daytime and nighttime, the cultivation spaces are controlled to an environment that promotes plant photosynthesis. On the other hand, in the second stage, which corresponds to a stage after plants have fully grown, and in which a second artificial light source emitting artificial light with a small blue wavelength component switches the multiple cultivation spaces between daytime and nighttime, the cultivation spaces are controlled to an environment that suppresses plant photosynthesis. Typically, an environment that suppresses plant photosynthesis requires low operating costs, so operating costs can be reduced at the stage after plants have fully grown.

[0183] Clause 18. The plant cultivation device according to Clause 17, wherein the environmental control device controls the cultivation space receiving visible light to an environment that promotes photosynthesis more than a cultivation space not receiving visible light during the first and second stages. In this case, in both the first and second stages, the cultivation space is controlled to an environment that promotes plant photosynthesis during the period corresponding to daytime. On the other hand, the cultivation space is controlled to an environment that suppresses plant photosynthesis during the period corresponding to nighttime. Typically, an environment that suppresses plant photosynthesis requires lower operating costs, so nighttime operating costs can be reduced.

[0184] Clause 19. The plant cultivation device according to any one of Clauses 1 to 18, wherein the artificial light source irradiates the plant in the cultivation space with artificial light from the side. In this case, since the artificial light source irradiates the plant with artificial light from the side, it is possible to apply artificial light as evenly as possible to both the upper and lower leaves of a plant in a growth stage having many leaves stacked vertically.

[0185] Clause 20. A plant growing method for growing a plant using the plant growing device according to Clause 1, comprising: the movement control device moving the artificial light source relative to the cultivation space to create a state in which the plant in the cultivation space is irradiated with artificial light output from the artificial light source and a state in which the plant in the cultivation space is not irradiated with artificial light output from the artificial light source.

[0186] Clause 21. A plant growing method for growing a plant using the plant growing device according to Clause 2, comprising: the movement control device moves the artificial light source relatively to the plurality of growth spaces to simultaneously create a state in which a plant in one of the growth spaces is irradiated with artificial light output from the artificial light source and a state in which a plant in another of the growth spaces is not irradiated with artificial light output from the artificial light source; and the movement control device moves the artificial light source relatively to the plurality of growth spaces to switch between a growth space in which a plant is irradiated with the artificial light and a growth space in which a plant is not irradiated with the artificial light.

[0187] Clause 22. A plant cultivation method for cultivating a plant using the plant cultivation device according to Clause 7, comprising: moving the housing and the artificial light source relatively to each other to create a period during which the plants in the cultivation space are irradiated with the artificial light output from the artificial light source; and moving the housing and the artificial light source relatively to each other to create a period during which the plants in the cultivation space are not irradiated with the artificial light output from the artificial light source.

[0188] L...artificial light, 1, 1A, 1B, 1C, 1D, 1E, 81, 101, 101A, 101B, 101C, 101D, 111, 200...plant cultivation device, 2, 82, 102, 112...cultivation device, 3...plant, 4, 4A, 4B, 4C...liquid fertilizer tank, 6A, 6B, 6C, 8A, 8B, 8C...cultivation space, 7, 77...light source unit, 7a, 77a...light source panel (artificial light source), 7b, 77b...heat-shielding case, 7c, 77c...heat-shielding partition wall, 10...nutrient solution supply system (liquid fertilizer control system), 20...environmental control device, 30...movement control device, 60...casing, 60a...heat-shielding partition wall, 60b...upper wall (heat-shielding partition wall), 61...casing unit, 61A...casing, 62...cultivation space, 71, 73, 71a, 73a...first light source panels; 72, 74, 72a, 74a...second light source panels; 90...liquid fertilizer tank unit (liquid fertilizer tank); 202A, 202B...cultivation units

Claims

1. A plant growing device for growing plants, comprising: at least one growing space in which the above-ground portion of at least one plant is grown; at least one artificial light source arranged in the vicinity of the growing space and emitting artificial light for growing the plant; a heat-shielding partition wall made of a light-transmitting material and interposed between the growing space and the artificial light source; and a movement control device that moves the artificial light source relative to the growing space so as to create a state in which the plant in the growing space is irradiated with the artificial light output from the artificial light source and a state in which the plant in the growing space is not irradiated with the artificial light output from the artificial light source.

2. A plant cultivation device as claimed in claim 1, comprising a plurality of cultivation spaces arranged adjacent to each other, with the above-ground portion of at least one plant being cultivated in each cultivation space, the artificial light source being arranged so as to be shared by the plurality of cultivation spaces, and the movement control device simultaneously creating a state in which a plant in one of the cultivation spaces is irradiated with artificial light output from the artificial light source and a state in which a plant in another of the cultivation spaces is not irradiated with artificial light output from the artificial light source, and moving the artificial light source relative to the plurality of cultivation spaces so as to alternate between the cultivation spaces in which the plant is irradiated with the artificial light and the cultivation spaces in which it is not irradiated.

3. The plant cultivation device described in claim 2, wherein the heat-insulating partition has a length equal to or greater than the total length of the multiple cultivation spaces, is positioned in the vicinity of the multiple cultivation spaces, and extends along the multiple cultivation spaces, and the movement control device moves the artificial light source relative to the multiple cultivation spaces while the heat-insulating partition is stationary relative to the multiple cultivation spaces.

4. The plant growing device according to claim 3, wherein the heat insulating partition is positioned at a position that restricts the growth of the above-ground part of the plant grown inside the growing space in a direction toward the artificial light source.

5. A plant cultivation device as described in claim 3 or 4, comprising a heat-shielding case surrounding the artificial light source, the heat-shielding case having a length equal to or greater than the total length of the plurality of cultivation spaces, being positioned in the vicinity of the plurality of cultivation spaces, extending along the plurality of cultivation spaces, and having the heat-shielding partitions.

6. The plant growing device according to claim 1 or 2, wherein the movement control device moves the artificial light source and the heat insulating partition together relative to the growing space.

7. The plant growing device of claim 1, comprising at least one housing formed from a light-transmitting material, defining said at least one growing space and enclosing said at least one growing space, said at least one artificial light source being disposed outside said housing, and said housing having said heat-shielding partition wall.

8. The plant growing device according to claim 7, wherein the movement control device moves the artificial light source.

9. The plant growing device according to claim 7, wherein the movement control device moves the housing.

10. A plant cultivation device as claimed in any one of claims 7 to 9, wherein the heat-shielding partition of the housing is positioned in a position that restricts the growth of the above-ground part of a plant cultivated inside the cultivation space in a direction toward the artificial light source.

11. A plant cultivation device as described in any one of claims 7 to 10, comprising a plurality of housings arranged in close proximity to each other, each defining a plurality of cultivation spaces and enclosing each of the plurality of cultivation spaces, the artificial light source being arranged so as to be used in common by the plurality of cultivation spaces corresponding to the plurality of housings, and the movement control device moving the artificial light source relative to the plurality of cultivation spaces so that artificial light output from the artificial light source is supplied to different cultivation spaces at different periods.

12. A plant cultivation device as described in claim 11, comprising: a liquid fertilizer tank for storing liquid fertilizer and in which the roots of a plurality of plants are placed; and a liquid fertilizer control system for controlling at least one of the concentration and temperature of the liquid fertilizer in the liquid fertilizer tank, wherein the liquid fertilizer tank and the liquid fertilizer control system are commonly used for the plurality of cultivation spaces corresponding to the plurality of housings, respectively.

13. The plant cultivation device according to any one of claims 2 to 5, 11 and 12, wherein the at least one artificial light source comprises a first artificial light source and a second artificial light source, the first artificial light source and the second artificial light source emitting artificial light having different wavelength spectra from each other, the first artificial light source and the second artificial light source are arranged so as to be used in common to the multiple cultivation spaces, and the movement control device moves the first artificial light source and the second artificial light source relative to the multiple cultivation spaces so as to create, for plants within each cultivation space, a period during which they are irradiated with the artificial light output from the first artificial light source, a period during which they are irradiated with the artificial light output from the second artificial light source, and a period during which they are not irradiated with artificial light.

14. The plant growing device according to claim 13, wherein the first artificial light source emits visible light and the second artificial light source emits at least ultraviolet light.

15. A plant cultivation device as claimed in any one of claims 2 to 5 and 11 to 14, further comprising an environmental control device that controls the cultivation space into which the artificial light source irradiates visible light to an environment that promotes plant photosynthesis, and controls the cultivation space into which the artificial light source does not irradiate visible light to an environment that suppresses plant photosynthesis.

16. The plant cultivation device according to claim 13, wherein the first artificial light source emits visible light, and the second artificial light source emits visible light having fewer blue wavelength components than the visible light emitted by the first artificial light source, and the movement control device creates a first step of stopping the second artificial light source at a standby position where the second artificial light source cannot supply artificial light to any of the multiple cultivation spaces and moving the first artificial light source relatively to the multiple cultivation spaces, and a second step of stopping the first artificial light source at a standby position where the first artificial light source cannot supply artificial light to any of the multiple cultivation spaces and moving the second artificial light source relatively to the multiple cultivation spaces.

17. The plant cultivation device as described in claim 16, further comprising an environmental control device that, in the first stage, controls the multiple cultivation spaces to an environment that promotes plant photosynthesis, and, in the second stage, controls the multiple cultivation spaces to an environment that suppresses plant photosynthesis.

18. The plant cultivation device according to claim 17, wherein the environmental control device controls the cultivation space receiving visible light in the first stage and the second stage to an environment that promotes photosynthesis more than a cultivation space not receiving visible light.

19. The plant growing device according to any one of claims 1 to 18, wherein the artificial light source irradiates the plant in the growing space with artificial light from a side.

20. A plant cultivation method for cultivating a plant using the plant cultivation device according to claim 1, comprising: the movement control device moving the artificial light source relative to the cultivation space to create a state in which the plant in the cultivation space is illuminated with artificial light output from the artificial light source, and a state in which the plant in the cultivation space is not illuminated with artificial light output from the artificial light source.

21. A plant cultivation method for cultivating a plant using the plant cultivation device of claim 2, comprising: the movement control device moves the artificial light source relative to the multiple cultivation spaces, thereby simultaneously creating a state in which a plant in one of the cultivation spaces is irradiated with artificial light output from the artificial light source and a state in which a plant in another of the cultivation spaces is not irradiated with artificial light output from the artificial light source; and the movement control device moves the artificial light source relative to the multiple cultivation spaces, thereby switching between a cultivation space in which a plant is irradiated with the artificial light and a cultivation space in which a plant is not irradiated.

22. A plant cultivation method for cultivating a plant using the plant cultivation device according to claim 7, comprising: moving the housing and the artificial light source relatively to each other to create a period during which the plant in the cultivation space is irradiated with the artificial light output from the artificial light source; and moving the housing and the artificial light source relatively to each other to create a period during which the plant in the cultivation space is not irradiated with the artificial light output from the artificial light source.

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