JPH0998665A - Plant cultivation equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plant cultivation apparatus capable of reducing electric power cost such as illumination cost and refrigeration cost, having excellent growing performance and useful for a vegetable cultivation factory, etc., by using a light source composed of a panel of a photosemiconductor unit furnished with a forced cooling apparatus with a heating and refrigerating medium and placing the light source close to a vegetable cultivation plane. SOLUTION: A panel-formed light source 2 composed of a photosemiconductor unit such as light-emitting diode and furnished with a forced cooling apparatus with a heating and refrigerating medium is placed close to a vegetable cultivation plane. The panel-formed photosemiconductor unit light source 2 is placed in superposed state and the vegetable cultivation apparatus is preferably covered almost completely with a light-reflecting material such as a white board or an aluminum plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plant cultivation apparatus using artificial light as a light source such as a plant factory, a vegetable factory, and a seedling raising apparatus, which is equipped with a cooling device using a coolant such as water, and which emits light such as a light emitting diode and a semiconductor laser. The present invention relates to a multi-stage plant cultivation apparatus for cultivating a cultivated plant by illuminating it closely by using a panel-shaped lighting unit having a semiconductor as a light source and stacking it and a plant cultivation board in a compact manner.

[0002]

2. Description of the Related Art As long as a plant is cultivated under natural conditions where daily fluctuations are large, fluctuations in yield and harvest time due to environmental fluctuations cannot be avoided. The magnitude of such uncertainties in the production process has been an obstacle to improving the planning of agricultural production and modernizing the working environment. In recent years, as an agricultural environment that is not affected by such changes in natural conditions,
Plant factories and vegetable factories that systematically produce crops and seedlings by controlling all conditions that affect plant growth such as light, temperature, humidity, carbon dioxide concentration, illuminance, hydroponic solution concentration, and pH in the cultivation environment. Practical application of seedling raising equipment is desired.
There are two types of plant cultivation devices such as plant factories, vegetable factories, and seedling raising devices (hereinafter referred to as plant cultivation devices) that use both fully artificial light and solar light, but both require electricity costs such as lighting and cooling costs. However, it has not been put to practical use yet. In these plant cultivation devices, the entire system is often operated in a closed system, and reduction of heat removal cost to prevent temperature rise in the system due to lighting is an urgent task for commercialization of the plant cultivation device along with lighting power cost. Has become.

[0003]

In the lighting method using a metal halide lamp, a high-pressure sodium lamp, a white fluorescent lamp, or the like, which has been conventionally used as a light source, the lighting power and the air conditioning power cost are high, and the vegetables, seedlings, etc. produced are large. It was difficult to put this plant into practical use because it had to be expensive.
Therefore, it is necessary to reduce the power cost of the entire system including the power costs for these lights and air conditioning.

[0004]

Optical semiconductors such as light emitting diodes are not only efficient as plant illumination light sources in that they can freely select only light having a wavelength required for plants, It is very advantageous as a light source for plant cultivation because it does not contain infrared rays and heat rays contained in a large amount. That is, in the conventional light source, direct illumination from the vicinity of the cultivated plant is impossible in order to avoid obstacles such as leaf burning due to heat rays (an expensive and large space heat ray removing device is required),
It was a disadvantage in terms of light utilization efficiency. However, by using an optical semiconductor, it is possible to use infrared rays and light rays that do not include heat rays at all, and it becomes possible to perform near-field irradiation from the immediate vicinity of the plant, and it is possible for the plant to receive the light of the light source very efficiently. became.

Further, it has been found that the temperature control of the entire cultivation system can be carried out at a very low cost by efficiently cooling the light emitting element of the optical semiconductor with a thermal refrigerant such as water. Even if it is an optical semiconductor with high luminous efficiency, not all the input electric power is converted into light. However, the energy that is not converted to light is not emitted as a heat ray like other light sources, but is emitted as a temperature rise of the optical semiconductor element itself. Therefore, the optical semiconductor element is installed directly on a substrate with good thermal conductivity such as aluminum or ceramics, and the substrate is cooled by using cold refrigerant such as cold water, cold air, CFC substitute gas, or other gas-based refrigerant. Efficiently removes the heat generated from the system to control the temperature of the entire system accurately
It has been found that it can be realized at a low power cost of 3 or less.

In addition, by using this cooling method, the optical semiconductor element can be continuously made to emit light at an appropriate temperature, and as a result, the maximum light output per element can be doubled under the normal use condition. It has been found that the life of the device can be remarkably extended by raising the temperature as described above.

Up until now, there have been reports showing the possibility of using optical semiconductors as a light source for plant cultivation (Hort Science, Vo.
l.26 (2), 203-205, (1991) and Japanese Patent Application No. 3-98526), in the same usage as the general light source reported in these, as a light source for plant cultivation of optical semiconductors, It was impossible to achieve remarkable power saving and compactness without making full use of its features. When an optical semiconductor such as a light emitting diode (LED) is used as a light source for plant cultivation, a plant cultivation device using the present technology, that is, an optical semiconductor lighting panel is cooled by a forced cooling method using a heat refrigerant, and is used. It is possible to significantly reduce power consumption, downsize the device, and reduce the price of the device only after using the multi-stage plant cultivation system of the method of irradiating the plant with near light. It is indispensable for constructing a low-cost and practical plant production system in production equipment and the like.

Next, the outline of the apparatus will be described. led
Regarding the light irradiation panel of, for example, a board (1) made of a material having a high thermal conductivity such as aluminum or ceramic and a copper foil or a silver foil (8) laminated on the board is used, and the wiring is wired according to a normal printed wiring. The LED chip (2) may be connected to the LED chip and sealed in a lens shape with a resin (4) such as an epoxy resin. On the back side of the board, a heat refrigerant such as water is allowed to flow to forcefully cool the heat of the chip, or fins with a large surface area are installed on the back side of the board to improve the heat dissipation rate. It can also be cooled by passing cold air. It is also possible to cool using a gas refrigerant that uses heat of vaporization. At this time, a pressure is applied to the portion where the coolant is injected to the back surface of the light emitting source, so that the entire light emitting panel device has a pressure resistant structure as necessary. Since the mounting surface of the LED chip faces the plant cultivation board, it is preferable that the mounting surface is made of resin or a glass plate (3) for waterproof and moistureproof treatment. As the thermal refrigerant, an aqueous system having a high specific heat and capable of being used at normal pressure is preferable, and it is preferable to use a refrigerant of 30 ° or less. Additives such as anticoagulants and rust preventives can be added depending on the operating temperature and the material of the panel. When it is structurally difficult to flow cold water or gas cooling to which a negative pressure is applied to the back surface of the substrate, the back surface of the panel can be cooled more easily by passing cold air. In the case of the method using cold air, the necessity of having airtightness and pressure resistance is smaller than that in the case of using cold water or cooling gas, but in order to increase the cooling efficiency, the flow rate of cold air can be increased or as described above. It is necessary to install a fin structure or the like on the back surface of the substrate to improve heat dissipation. It is desirable to provide a flow path for hot refrigerant in the panel so that the refrigerant such as cold water or cold air flows evenly through the panel and uniformly cools the entire panel. Regarding the power source of the LED, it is possible to control the light output according to the growth of the plant to be cultivated and, if necessary, it is possible to introduce a management computer for controlling the output according to various cultivation environment conditions. When the light wavelengths used are two or more, the output adjustment must be controlled independently. The panel-shaped light source of the present invention is particularly suitable as a light source for a multi-stage plant device.

Although various systems can be used for the plant culture device, in order to carry out planned and uniform cultivation, the cultivation method using the hydroponic method is more advantageous than the cultivation using the soil. is there. Above all, compared to the submersion method in which the hydroponic solution is stored in the aquarium to immerse the roots, the NFT method, the submerged solution exchange method, and the like, the respiration activity of the roots is increased, and there is no need for a large-scale aquarium facility. Therefore, it is desirable to use a spray hydroponic method that is compact in terms of equipment and advantageous in terms of strength.

Regarding the layout of the entire apparatus, it is better to alternately install the cultivation boards and the LED panels than to stack the plant cultivation boards and the LED light irradiation panels vertically so that the hydroponic solution is sprayed more uniformly. It is also advantageous in securing the structural strength of the entire device. Since the LED radiates almost no heat rays between the plant cultivation board and the LED panel, it is possible to perform close-up lighting as close as possible to the plant body, and the device can be made compact. Specifically, depending on the size of the plant to be cultivated, the distance between the unit and the plant cultivation surface is preferably 50 cm or less, more preferably 30 cm or less. For example, lettuce and saladana are about 20 cm. Further, since there is no heat radiation from the LED panel, it is possible to close the device almost completely and confine the light from the light emitting panel into the device. By using a light-reflecting material such as a white board, a highly reflective stainless steel plate, or an aluminum plate to close the device, the ratio of the light emitted from the LED panel leaking to the outside or being absorbed by the wall surface is extremely reduced. It can be reduced. In that case, the light reflectance of the reflective material used is preferably 70% or more, and in order to increase the effective light amount in plant growth, the light reflectance is 90%.
% Or more is preferable. By using such a cultivation device, the irradiation light is confined in the device, and the light utilization efficiency of the cultivation plant can be dramatically improved.

As described above, when covering substantially the entire surface of the device with the light-reflecting material, it is not always necessary to maintain airtightness. or,
To supply CO ₂ and air conditioning required for photosynthesis,
An opening may be provided in a part thereof so as to communicate with the outside. Such an opening is preferably 10% or less of the light reflective area. It is desirable that the cultivation board can be slid in and out of the device for planting and harvesting seedlings. Specific experimental examples of the content of the present invention are shown below, but the content of the present invention is not limited to the following examples.

[0012]

[Example] 300 DDH type ultra-high brightness LED chips (2) (peak wavelength 660 nm) were installed on a ceramic plate (1) of 20 cm x 50 cm and thickness of 7 mm as shown in FIG. Water-cooled LE with a hollow on the back side of the plate to allow cooling water to flow
A D panel was produced. The LED chip was directly mounted on the ceramic surface with the wiring pattern shown in FIG. 2, the chip portion was lens-shaped sealed with epoxy resin (4), and covered with a glass plate (3) (FIG. 3). Cooling water was circulated in the cavity of the ceramic plate at a flow rate of 1.2 liters / minute to prevent the temperature from rising due to chip heat generation.

By changing the temperature of the cooling water from 5 ° C to 40 ° C,
The light output (measured at a position 40 cm away from the center of the panel) when the forward current (IF) of the LED was changed from 15 to 105 mA was measured. The results are shown in FIG. By cooling the chip through a ceramic board, we succeeded in increasing the maximum output of the LED more than twice as much as when the chip was not cooled. In addition, when the cooling water is not supplied, the LED chip deteriorates rapidly when the IF of 50 mA or more is supplied.
By flowing the cooling water, it was possible to prevent the deterioration of the chip due to the large current drive.

(Cultivation Example 1) The water-cooled LED produced above
Panel (5) (partly LED on both sides of ceramic board
A plant cultivation board having 40 chips mounted chips (5 '), standing an LED panel by the method shown in FIG. 5, and having a vertical spray hydroponic device (10) between the light emitting surfaces of the LEDs. It was installed so that (6) was sandwiched. The distance between the cultivation board and the LED light emitting surface was set to 20 cm, the periphery of the device was not covered, and the cultivation device was opened to the outside to cultivate leaf lettuce. The environment for cultivating leaf lettuce was maintained at about 25 ° C. by circulating cooling water at 20 ° C. to each panel from the cooling water inlet (7) at 1.2 liter / min. Table 1 shows the results of cultivating leaf lettuce (variety: Red Fire) for 30 days under continuous lighting for 24 hours.

[0015]

[Table 1] Table 1 Growth of leaf lettuce on water-cooled LED panel ─────────────────────────────── Measurement item ── ───────────────────────────── LED forward current (IF) 50 mA Photosynthetic effective photon flux density 162 μmol / m ² / s (Measured on the cultivation board) Lettuce leaf surface temperature 25 ℃ Lettuce strain number 360 strains Lettuce aboveground fresh weight 52.7 ± 3.2 g / strain Lettuce plant height 30.8 ± 5.8 cm Root dry weight 219 ± 59 mg / Stock ─────────────────────────────── The cultivation room was cultivated in an open system without a reflector.

The same cultivation was attempted by using eight fluorescent lamps of 40 W per one cultivation board instead of the LED, but leaf burns and shoots of buds were burned, and growth failure was generally caused. Oops.

(Cultivation example 2) The water-cooled LED panel (5) produced above (40 panels (5 '), some of which have LED chips mounted on both sides of a ceramic board, are used by the method shown in FIG. The LED panel was erected, and the plant cultivation board (6) having the vertical spray hydroponic device (10) was installed between the light emitting surface of the LED and the light emitting surface.White around the space between the cultivation board and the LED panel. Closed with an acrylic plate (reflectance 90%) (omitted in Fig. 5.) Cultivation of leaf lettuce by circulating cooling water of 20 ° C to each panel from the cooling water inlet (7) at 1.2 liter / min. The environment was maintained at about 25 ° C. Leaf lettuce (cultivar: Red Fire) was cultivated for 30 days under continuous lighting for 24 hours, and the results are shown in Table 2. LED input power, cooling power, and plant weight of the harvest were cooled. Water cooled with a cool circulator As a result, the electric power required for temperature control by the LED water cooling panel is about 1% compared to the case of cooling the entire experimental equipment with an air conditioner. The total power consumption including lighting power consumption was reduced by about 30%, and power consumption was reduced by about 30% .In addition, when the LED panel was not cooled by circulating water, the temperature of the LED chip increased. Growth of leaf lettuce strains was found to be poor due to insufficient output due to a similar experiment. was gotten.

[0018]

[Table 2] * 1) Cooling the circulating cooling water with a cool circulator (Yamato Scientific "BC55") * 2) Air-conditioning the cultivation equipment with an air conditioner (Mitsubishi Heavy Industries "SRK1853JNDH" type)

(Cultivation example 3) Using a device similar to the above-mentioned cultivation example 2, the distance between the plant cultivation board and the LED panel is 20 cm.
Leaf lettuce (variety:
The growth of red fire was compared. The LED panel was cooled using cooling water at 20 ° C., and the plant height and fresh weight of the above-ground part after 30 days of cultivation are shown in Table 2. As a result, when the panel distance was 20 cm, compared with the panel distance of 60 cm, the above-ground weight was approximately doubled, and no leaf burn phenomenon was observed at the leaf tips that were in contact with the LED panel. From the above results, it is desirable that the distance between the LED panel and the plant cultivation board be designed as close as possible in accordance with the size of the plant body, and the plant growth promoting effect by such near irradiation is very remarkable. It turned out to be.

[0020]

[Table 3]

(Cultivation Example 4) Using the same device as above,
The distance between the plant cultivation board and the LED panel is 20 cm,
What was closed with a white acrylic board, what was closed with an aluminum glossy board, what was closed with a gray acrylic board,
Cultivated in a state where the irradiation light leaks to the outside without closing (in order to prevent temperature rise in the cultivation room in cultivation using ordinary light sources such as fluorescent lamps and incandescent lamps, it is necessary to Cultivation was compared under four conditions (cultivation is basic). LE
The D panel was cooled with water at 20 ° C.

First, before the cultivation was started, the amount of light on the cultivation board was compared under the above four conditions. The results are shown in FIG. By closing the cultivation room with a material with good reflectance,
The photosynthetic effective photon flux density on the cultivation board increased dramatically. Next, the forward current of the LED was kept at 50 mA, and cultivation of lettuce was tried under each cultivation condition. Table 4 shows the results of cultivating leaf lettuce (variety red fire) for 30 days under 24-hour illumination. The growth of leaf lettuce was increased about 2.1 times by closing the cultivation room with a board having a good light reflectance. Moreover, the temperature rise in the cultivation room closed during cultivation was not observed.

[0023]

[Table 4] Table 4 Changes in the growth of leaf lettuce due to the wall material in the cultivation room ───────────────────────────────── ─── Reflectivity Type of wall material Plant height (cm) Fresh weight above ground (g / share) ───────────────────────────── ─────── 90% white acrylic plate 21.5 ± 3.8 112.7 ± 6.9 85% aluminum gloss plate 22.9 ± 4.2 109.7 ± 7.8 70% gray acrylic plate 24.9 ± 4.8 77.7 ± 5.5 Non-closed (open system) 30.8 ± 5.8 52.7 ± 3.2 ────────────────── ─────────────────── (Cultivation days 30 days average ± standard deviation)

[0024]

[Effects of the Invention] Optical semiconductor elements such as LEDs are directly installed on a substrate having good thermal conductivity such as ceramics, and the base is cooled with water to efficiently remove heat generated from the elements.
It has been found that the temperature control of the entire system can be realized accurately and at a low power cost of 1/3 or less compared to the conventional light source. In addition, by using this cooling method, the optical semiconductor element can be continuously made to emit light at an appropriate temperature, and as a result, the maximum light output per element can be increased to more than twice the normal operating conditions. It was also found that the life of the device can be remarkably extended.

Further, the plant cultivating apparatus having such a structure is capable of illuminating a plant closely, and by stacking the cultivating units, it is possible to make the apparatus as a whole compact. Further, it is also possible to cover the cultivation room with a material having high reflectance by utilizing the fact that there is no heat radiation from the optical semiconductor element. These unique structures bring about a significant increase in the effective amount of light in the cultivation room, contribute to the improvement of the light utilization efficiency of the cultivated plant, good and efficient growth, and the reduction of the cultivation running cost. It contributes to efficient growth and temperature control of equipment, and saves electricity costs. Due to the above effects, plant factories that have been difficult to disseminate due to high running power costs,
It has become possible to greatly reduce the running costs of vegetable factories and seedling production equipment, and to provide plant cultivation equipment suitable for practical use.

[Brief description of drawings]

FIG. 1 is an example of a light irradiation panel of the present invention

FIG. 2 is a wiring example of a light irradiation panel of the present invention.

FIG. 3 is a partial view showing an example of a light irradiation panel of the present invention.

FIG. 4 is a graph showing the effect of cooling water of the present invention.

FIG. 5 shows an example of the plant cultivation device of the present invention.

FIG. 6 is a graph showing changes in the amount of light on the cultivation board by the wall material of the cultivation room of the present invention.

[Explanation of symbols]

 1 substrate 2 LED chip 3 glass plate 4 epoxy resin 5 panel 6 plant cultivation board 7 cooling water inlet 8 silver foil 9 gold wire bonding 10 vertical spray hydroponic device

Claims (3)

[Claims] 1. A plant cultivation device in which a light source composed of a panel-shaped optical semiconductor unit equipped with a forced cooling device using a heat refrigerant is installed close to a plant cultivation surface. 2. A multistage plant cultivating apparatus comprising the panel-shaped optical semiconductor unit light sources according to claim 1 which are stacked and installed. 3. The plant cultivation device according to claim 1, wherein substantially the entire surface is covered with a light-reflecting material.