JPH08228598A - Growing of plant - Google Patents

Abstract

PURPOSE: To provide a method for growing plants capable of efficiently growing the plants, prolonging the life time of a light source and facilitating the inexpensive maintenance of the light-source unit. CONSTITUTION: In this plant-growing method in which plants are grown by illumination of light from an artificial light source, the light source unit is a unit of dielectric barrier discharge lamps 12, 13, 14 each comprising a discharging vessel filled with a gas forming an excimer by the dielectric barrier discharge, an electrode for effecting the dielectric barrier discharge using the gas as a discharging gas, at least one dielectric barrier discharge lamp having a fluorescent substance converting the ultraviolet excimer beams generated by the barrier discharge to the light of longer wavelength and at least one alternating current electric source for conducting the dielectric barrier discharge. In this case, the fluorescent substance is desired to have an afterglow time shorter than 0.2x the cycle of the alternating electric source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to improvement of a plant growth method for irradiating lettuce and the like to grow a plant.

[0002]

2. Description of the Related Art As a technique related to the present invention, for example, the Illuminating Engineering Society, Vol.
In page 591 of the issue, the effect of lighting on the growth of plants is described under the title "Lighting in a plant factory". In addition, it is described that continuous lighting is not always necessary for the growth of plants, and intermittent lighting in which a lamp is operated by repeating lighting and extinction is sufficient.

Further, there is Japanese Patent Laid-Open Publication No. 2-7353, in which a discharge container is filled with a discharge gas for forming excimer molecules, and a dielectric barrier discharge (also known as ozonizer discharge or silent discharge. Published by The Institute of Electrical Engineers of Japan). A lamp that causes excimer molecules to be formed by the revised new edition "Discharge Handbook", June 1st, 1st edition, 7th edition, page 263), and excites the phosphor with ultraviolet rays emitted from the excimer molecules.
That is, it describes a fluorescent lamp device using a dielectric barrier discharge, the discharge container is a hollow cylindrical shape,
At least a part of the discharge container also serves as a dielectric of the dielectric barrier discharge, the dielectric is light transmissive, and a dielectric barrier discharge fluorescent material in which at least a part of the dielectric is provided with a fluorescent material. A lamp device is described.

An outline of a general dielectric barrier discharge will be described below with reference to FIG. 4, which is a schematic view of a cylindrical dielectric barrier discharge fluorescent lamp. The discharge vessel 1 is made of glass, which is a dielectric, and has an inner tube 2 and an outer tube 3 arranged coaxially to form a hollow cylinder. Phosphors 10 and 11 are provided on the inner surfaces of the inner tube 2 and the outer tube 3. Further, an inner electrode 4 for dielectric barrier discharge, which also serves as a light reflection plate, is provided on the outer surface of the inner tube 2, and a light-transmitting outer electrode 5 is provided on the outer surface of the outer tube 3. A discharge space 8 is formed between the inner surface of the outer tube 3 facing the electrode 5 and the inner surface of the inner tube 2 facing the electrode 4. In addition, a getter chamber 7 for housing the getter 6 is provided at one end of the discharge container 1.
The getter 6 is an impure gas (for example, H ₂ O) in the discharge space 8.
Etc.) to stabilize the discharge.

The discharge space 8 is filled with a discharge gas for forming excimer molecules by a dielectric barrier discharge, and a voltage is applied to the electrodes 4 and 5 by an AC power source 9 to discharge the discharge space 8.
Dielectric barrier discharge is stably generated in the and the excimer light is emitted. Then, the excimer light excites the phosphors 11 and 10 provided on the inner surfaces of the inner tube 2 and the outer tube 3,
Visible light is emitted from the phosphor.

By the way, in a normal glow discharge or arc discharge generated by an arc discharge lamp or the like having a medium pressure or high pressure of several tens of torr or more, there is only one discharge plasma in the discharge space, and one discharge plasma exists on the electrode surface. Electrode bright spots occur. That is, even if the area of the electrode is increased, there is only one portion that substantially functions as the electrode, and only one discharge plasma exists. On the other hand, as described in the above discharge handbook, in the dielectric barrier discharge, the dielectric is inserted in the discharge path. This dielectric prevents the discharge plasma from converging in a single line, and
A micro discharge plasma (hereinafter referred to as a micro plasma) having a very small plasma diameter and a very short discharge duration (for example, tens of ns) because it has the function of preventing the discharge from continuing. Are uniformly present in the discharge space.

Further, the dielectric barrier discharge does not occur at all phases of the power supply voltage, but only at a specific phase of the applied voltage. That is, there is a phase in which the discharge is completely at rest. That is, even if a sinusoidal voltage is applied, intermittent light emission is automatically obtained. This phenomenon is also a feature greatly different from the discharge of the conventional discharge lamp. Further, as described above, the cylindrical dielectric barrier discharge lamp is uniformly coated with multiple microplasma,
Since there are a large number of them, it is possible to connect a plurality of cylindrical dielectric barrier discharge lamps in parallel and to uniformly light them with a single power supply. This is not possible with conventional discharge lamps.

[0008]

However, the conventional method for growing plants by intermittent illumination using a light source has the following problems.

(1) Regarding a system using a shutter as means for performing intermittent illumination. The growth efficiency cannot be improved because the light cannot be used while the shutter is closed.

(2) Method of blinking high pressure arc discharge lamp. High pressure sodium lamps, metal halide lamps and high pressure mercury lamps, which have been conventionally used for plant growth, are flashed, but the plasma of these lamps is a local thermal equilibrium plasma, that is, discharge gas, vapor, and ion. The temperature of is almost equal to the temperature of electron, which is several thousand degrees. Therefore, even if the injection and interruption of the electric input to the lamp are repeated, the emitted light cannot follow the electric input, resulting in a delay of several μs to several hundreds of μs, and the growth efficiency cannot always be improved. .

Further, the high-pressure arc discharge lamp has a problem that the spectrum of light output changes depending on the repetition period of injection and interruption of electric input to the lamp and the amount of electric power injection. It is difficult to change the cycle of injection and interruption of the electric input to the lamp and the amount of electric power injection depending on the situation. Further, the above high-pressure arc discharge lamp has a pair of metal electrodes in the discharge space, but since these electrodes are significantly consumed at the start of lighting the lamp, injection and interruption of electric input to the lamp are repeated. The disadvantage of this is that the life of the lamp is significantly shortened and therefore the growing costs are high.

(3) About the method of blinking the fluorescent lamp. The fluorescent lamp has a wavelength of 254 nm, which is the resonance line of mercury atoms.
It is a lamp of the method that converts the ultraviolet rays of the above into visible light using a phosphor.
The absorption by mercury atoms is extremely high. Therefore, even if the injection and interruption of the electric input to the lamp is repeated,
The emitted light cannot follow the electric input and causes a delay of several tens of μs, which cannot necessarily improve the growth efficiency.

Further, since the electrodes of the fluorescent lamp are significantly consumed at the start of lighting of the lamp, repeated injection and interruption of the electric input to the lamp shortens the life of the lamp remarkably.
Therefore, there is a drawback that the growth cost becomes expensive.
Further, since the fluorescent lamp cannot be turned on with a large amount of electric power, a large number of lamps are required to illuminate a large area, which causes a drawback that maintenance costs such as replacement of the lamp become large.

Further, as is common to all the above-mentioned conventional lamps, it is not possible to uniformly light a plurality of lamps in parallel with one power source, so one power source is required for one lamp. become. Therefore, in order to intermittently illuminate a plant to be grown using a plurality of lamps, it is necessary to match the lighting and extinguishing phases of a plurality of power sources. This has the disadvantage of being extremely difficult and an expensive power supply.

That is, as long as the conventional light source device is used, an inexpensive plant growing method has not always been obtained in terms of growth efficiency, light source life and maintenance of the light source device. The present invention has been made based on the above circumstances,
An object of the invention is to provide a plant growing method which has high growth efficiency, has a long life of a light source, is easy to maintain the light source device, and is inexpensive.

[0016]

In order to solve the above-mentioned problems, the invention of claim 1 of the present invention provides a plant growing method for growing a plant by irradiating a growing plant with light from an artificial light source device. The light source device includes a discharge container filled with a gas that forms an excimer by a dielectric barrier discharge, an electrode for performing a dielectric barrier discharge using the gas as a discharge gas, and an electrode generated by the dielectric barrier discharge. Dielectric barrier comprising at least one dielectric barrier discharge lamp having a phosphor for converting the ultraviolet excimer light into long-wavelength light, and at least one AC power supply device for performing the dielectric barrier discharge. In this case, a discharge lamp device is used, in which the afterglow time of the phosphor is set to 0.2 times or less the cycle of the AC power supply.

According to a second aspect of the present invention, in a plant growing method for irradiating a growing plant with light from an artificial light source device to grow a plant, the light source device is an excimer by dielectric barrier discharge. A discharge vessel filled with a gas that forms a gas, an electrode for performing a dielectric barrier discharge using the gas as a discharge gas, and an ultraviolet excimer light generated by the dielectric barrier discharge is converted into long-wavelength light. At least one dielectric barrier discharge lamp having a phosphor;
A dielectric barrier discharge lamp device comprising at least one AC power supply device for performing the dielectric barrier discharge, wherein the dielectric barrier discharge lamp is operated by repeating lighting and extinguishing, and An apparatus in which the extinguishing time per repetition is set to be twice or more the afterglow time of the phosphor is used.

According to a third aspect of the present invention, in the first or second aspect of the invention, a device is used in which a plurality of the dielectric barrier discharge lamps are connected in parallel to the AC power source. .

[0019]

According to the first aspect of the present invention, in the method for growing a plant in which light from an artificial light source device is irradiated to a growing plant to grow a plant, the light source device is an excimer by dielectric barrier discharge. A discharge vessel filled with a gas that forms a gas, an electrode for performing a dielectric barrier discharge using the gas as a discharge gas, and an ultraviolet excimer light generated by the dielectric barrier discharge is converted into long-wavelength light. Since the dielectric barrier discharge lamp device comprises at least one dielectric barrier discharge lamp having a phosphor and at least one AC power supply device for performing the dielectric barrier discharge, the discharge is performed at the applied voltage. Since there is a period in which the discharge occurs only in a specific phase and the discharge is stopped, and the afterglow time of the phosphor is set to 0.2 times or less of the cycle of the AC power source, the Discharge When stopped, so that the phase of light emission is not generated also emission of the phosphor rapidly decays phosphor is present. As a result, intermittent lighting is possible without providing a special device. The afterglow time in the present invention is the time from when the excitation light is blocked until the fluorescence decays to 10% of the value when the excitation light is irradiated.

Further, since the excimer light by the dielectric barrier discharge is used for exciting the phosphor, the spectrum distribution of the excimer light does not change depending on the discharge power density, and as a result, the input power to the lamp is reduced. By changing it, the light output can be changed without changing the spectral distribution of the light output.

According to a second aspect of the present invention, in a plant growing method for growing a plant by irradiating a growing plant with light from an artificial light source device, the light source device uses an excimer by dielectric barrier discharge. A discharge vessel filled with a gas that forms a gas, an electrode for performing a dielectric barrier discharge using the gas as a discharge gas, and an ultraviolet excimer light generated by the dielectric barrier discharge is converted into long-wavelength light. At least one dielectric barrier discharge lamp having a phosphor;
A dielectric barrier discharge lamp device comprising at least one AC power supply device for performing the dielectric barrier discharge, in which case the dielectric barrier discharge lamp is operated by repeating lighting and extinguishing, and Since the extinguishing time per repetition was set to be twice the afterglow time of the phosphor,
The growth efficiency can be optimized because the period during which the phosphor does not emit light can be surely present and the ratio of the lighting time to the extinction time can be arbitrarily adjusted. It should be noted that the growth efficiency does not become sufficiently large when the lighting time per repetition is 1 ms or more.

The present inventors have also found that the life of the dielectric barrier discharge lamp is not shortened even if the dielectric barrier discharge lamp is repeatedly turned on and off. That is, even if the intermittent illumination as described above is performed, since the dielectric barrier discharge lamp is used, a long-life illumination device can be obtained.

In the invention of claim 3 of the present invention, in the invention of claim 1 and the invention of claim 2, since a plurality of the dielectric barrier discharge lamps are connected in parallel to the AC power source, the plurality of the dielectric barrier discharge lamps are connected in parallel. The light emitted from the dielectric barrier discharge lamp becomes light in which the phases of light emission and extinction coincide with each other. Therefore, by irradiating a plant with the device, plant growth can be performed with high efficiency. In addition, with this device, it is possible to grow a plant planted in a large area with high efficiency.

[0024]

EXAMPLE FIG. 1 shows a schematic diagram of a plant growing method which is a first example of the present invention, and FIG. 2 shows a schematic diagram of a dielectric barrier discharge lamp used in the first example. In FIG.
The discharge vessel 1 is made of soda-lime glass with a total length of about 600 mm, and has an outer tube 20 having an outer diameter of 20 mm and a wall thickness of 1 mm, and an inner tube 21 having an inner diameter of about 2 mm and a wall thickness of 1 mm which are coaxially arranged to form a hollow cylindrical discharge. The space 8 is formed. The outer tube 3 also serves as a dielectric for dielectric barrier discharge and a light extraction window member, and an electrode 5 made of a conductive net that transmits light is provided on the outer surface of the outer tube 3. One end 22 of the inner pipe 21 is closed and the other end is welded to the outer pipe 3 at an end 23. A rod-shaped inner electrode 20 is provided in the inner tube 21. Reference numeral 24 is a seal-off portion of the exhaust pipe. Phosphors 10 and 11 are provided on the inner surfaces of the outer tube 3 and the inner tube 21, respectively. This phosphor, Y ₂ afterglow time 0.08Myuesu, emission center wavelength of 410nm
SiO ₅ : Ce. The discharge space 8 of the discharge container was filled with 250 torr (25 ° C. standard) xenon gas as a discharge gas.

The above-mentioned dielectric barrier discharge lamp 12, 1
3, 14 were connected in parallel, and were connected to a power supply 9 that generates a voltage of approximately 20 kHz and a sinusoidal voltage, and the dielectric barrier discharge lamp was lit with an input power per square centimeter of 0.25 watts. . As a result, the phosphors 10 and 11 were excited by the xenon excimer light having the maximum value at the wavelength of 172 nm and the half width of about 14 nm, and fluorescence was emitted. The fluorescence was generated in every half cycle of the voltage of the power source 9, that is, every 25 μs, the time of light emission was about 15 μs, and the period without light emission was about 15 μs.
Further, the fluorescent light is emitted from the dielectric barrier discharge lamps 12, 1
Since the same phase occurs in 3 and 14, the growing plant 15 on the growing bed 16 is intermittently illuminated. As a result, highly efficient growth is possible.

In the second embodiment of the present invention, the dielectric barrier discharge lamp in the first embodiment is replaced with the dielectric barrier discharge lamp shown in FIG. First
3 is different from the dielectric barrier discharge lamp of FIG. 3 in that (1) the inner electrode 20 is in contact with the discharge gas, and (2) both ends 100 and 101 of the inner electrode 20 are in contact with each other. Airtightly attached to both ends 26, 25 of the outer tube 3, (3) a getter 27 made of an alloy of titanium and zirconium is provided in a part of the electrode 20, and (4) the total length of the lamp is 1200 mm. Is to be.

In this embodiment, since there is only one dielectric, it is possible to light at a low power supply voltage, and therefore, there is an advantage that the power supply becomes inexpensive. Further, since the getter 27 is provided, the influence of the impure gas generated during lighting is eliminated,
Stable lighting is possible for a long time. Further, since both ends 100 and 101 of the inner electrode are fixed, there is an advantage that the mechanical strength of the lamp is increased.

A schematic diagram of a plant growing method according to a third embodiment of the present invention will be described with reference to FIG. The difference from the dielectric barrier discharge lamp device in the second embodiment is that (1) a blinker 17, which is a device for intermittently applying a voltage to the dielectric barrier discharge lamp, is added to the power supply 9. ,
(2) The phosphor has an emission center wavelength of 453 nm and an afterglow time of 60 μs (SrCaBaMg) ₅ (PO ₄ ).
_{This is a} mixture of ₃ Cl: Eu and Y ₂ O ₃ : Eu having an emission center wavelength of 611 nm and an afterglow time of about 1 ms. The time for applying a voltage to the dielectric barrier discharge lamp, that is, the lighting time of the lamp is 2 ms, and the extinguishing time of the lamp is set to 8 ms which is more than twice the 1 ms which is the afterglow time of the phosphor, and repeatedly lit. , Intermittent lighting was performed. As a result, highly efficient growth became possible.

In the above-mentioned embodiments, the metal mesh is used as the light transmissive electrode, but a transparent electrode such as indium oxide may be used. Further, the shape of the dielectric barrier discharge lamp is a coaxial cylinder type, but it is obvious that it may be any shape such as a flat plate type.

[0030]

As described above, the following effects can be obtained in the present invention. According to a first aspect of the present invention, in a plant growing method for irradiating a growing plant with light from an artificial light source device to grow a plant, the light source device forms excimers by dielectric barrier discharge. A discharge container filled with a gas, an electrode for performing a dielectric barrier discharge using the gas as a discharge gas, and a phosphor that converts ultraviolet excimer light generated by the dielectric barrier discharge into long-wavelength light. A dielectric barrier discharge lamp device comprising at least one dielectric barrier discharge lamp having: and at least one AC power supply device for performing the dielectric barrier discharge, and an afterglow time of the phosphor. Was set to 0.2 times the cycle of the AC power source or less and the plant growth method using the dielectric barrier discharge lamp device was adopted, the growth efficiency is high, and the maintenance of the light source device is easy and inexpensive. It is possible to provide a plant growth method.

According to a second aspect of the present invention, in a plant growing method for growing a plant by irradiating a growing plant with light from an artificial light source device, the light source device uses an excimer by dielectric barrier discharge. A discharge vessel filled with a gas that forms a gas, an electrode for performing a dielectric barrier discharge using the gas as a discharge gas, and an ultraviolet excimer light generated by the dielectric barrier discharge is converted into long-wavelength light. At least one dielectric barrier discharge lamp having a phosphor;
A dielectric barrier discharge lamp device comprising at least one AC power supply device for performing the dielectric barrier discharge, wherein the dielectric barrier discharge lamp is operated by repeating lighting and extinguishing, and the repeating In addition to the effect of the invention of claim 1, a long lifespan is provided because the method of growing a plant using the dielectric barrier discharge lamp device is one in which the extinguishing time per time is at least twice as long as the afterglow time of the phosphor. There is an advantage that the above device can be obtained.

In the invention of claim 3 of the present invention, in the invention of claim 1 and the invention of claim 2, a plurality of the dielectric barrier discharge lamps are connected in parallel to the AC power source. In addition to the advantages of the invention of claim 2 and the invention of claim 2, there is an advantage that a large area of plant can be illuminated.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example of a plant growth method of the present invention.

FIG. 2 is an explanatory diagram of an example of a dielectric barrier discharge lamp used in the present invention.

FIG. 3 is an explanatory view of another embodiment of the dielectric barrier discharge lamp used in the present invention.

FIG. 4 is an explanatory diagram of a dielectric barrier discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge container 2,21 Inner tube 3 Outer tube 4,20 Inner electrode 5 Light transmissive electrode 6,27 Getter 8 Discharge space 9 Power supply 10,11 Phosphor 12,13,14 Dielectric barrier discharge lamp 15 Growing plant 16 Growth floor 17 blinkers

Claims (3)

[Claims] 1. A plant growing method for irradiating a growing plant with light from an artificial light source device to grow a plant, wherein the light source device is a discharge filled with a gas that forms an excimer by a dielectric barrier discharge. A dielectric barrier discharge having a container, an electrode for performing a dielectric barrier discharge using the gas as a discharge gas, and a phosphor for converting ultraviolet excimer light generated by the dielectric barrier discharge into long-wavelength light. A dielectric barrier discharge lamp device comprising a lamp and an AC power supply device for performing the dielectric barrier discharge, wherein the afterglow time of the phosphor is specified to be 0.2 times or less the cycle of the AC power supply. A method of growing a plant, characterized in that the dielectric barrier discharge lamp device is used. 2. A plant growing method for irradiating a growing plant with light from an artificial light source device to grow a plant, wherein the light source device is a discharge filled with a gas forming an excimer by a dielectric barrier discharge. A dielectric barrier discharge having a container, an electrode for performing a dielectric barrier discharge using the gas as a discharge gas, and a phosphor for converting ultraviolet excimer light generated by the dielectric barrier discharge into long-wavelength light. A dielectric barrier discharge lamp device comprising a lamp and an AC power supply device for performing the dielectric barrier discharge, wherein the dielectric barrier discharge lamp is operated by repeating lighting and extinguishing.
Further, the method for growing plants, wherein the dielectric barrier discharge lamp device is used in which the extinction time per repetition is defined to be at least twice the afterglow time of the phosphor. 3. The plant growing method according to claim 1, wherein a plurality of the dielectric barrier discharge lamps are connected in parallel to the AC power supply.