JP2021119743A - Led illuminating device for plant cultivation and method for illuminating the led - Google Patents

Abstract

To provide an LED illumination technology for plant cultivation, allowing easy optimization of an emission spectrum to efficiently enhance the growth effect.SOLUTION: An LED illuminating device 10 is provided with: white LEDs 11 having an emission spectrum in which the wavelength range is continuous from at least 450 nm to 700 nm; monochrome LEDs 12 having at least one peak in the emission spectrum; and a circuit board on which the plurality of white LEDs 11 are arranged, and the monochrome LEDs 12 are uniformly arranged in the group of white LEDs 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lighting technique for plant cultivation using an LED (light emitting diode) as a light source.

In lighting equipment installed in plant factories, it is being considered to replace the light source from the fluorescent lamp, which has been the mainstream until now, with an LED. The reason is that if the LED is replaced, the disadvantages of the fluorescent lamp, that is, the large power consumption and heat generation and the short life are eliminated, and the production cost in the plant factory can be expected to be improved.

The commercialization of LED lighting equipment for plant cultivation began with a combination of two types of light sources: a blue LED that emits a single color at a wavelength of around 450 nm and a red LED that emits a single color at a wavelength of around 620 nm. After that, a light source having a white LED that emits light in a continuous wavelength range from 400 nm to 700 nm appeared. At the time of filing, a white LED having a lower color temperature and a higher color rendering index than the conventional white LED and emitting light in a continuous wide band from a wavelength of 400 nm to 780 nm has been attracting attention as a light source for plant cultivation. ..

Japanese Unexamined Patent Publication No. 2016-202072 Japanese Unexamined Patent Publication No. 2016-007185

As a result of using fluorescent lamps as a light source for a long period of time, the results of cultivated plants by plant factories have reached a certain level of satisfaction. However, as a result of replacing the light source with an LED, there have been reports of cases in which satisfaction with the results of cultivated plants is reduced.

Specifically, in the cultivation of leafy vegetables such as lettuce, it has been evaluated that the LED light source has achieved practical results, but is inferior to the results of the fluorescent light source. Further, in the cultivation of fruit vegetables such as strawberries and tomatoes, satisfactory results have not been obtained with the LED light source regarding the coloring of fruits, which is not pointed out by the fluorescent light source.

The reason for this is that when comparing the emission spectra of the light source, the R / B ratio (red / blue ratio) and the R / FR ratio (red / far red ratio) of the LED and the fluorescent lamp are significantly different from each other. Is mentioned. Therefore, if the R / B ratio and the R / FR ratio of the light source are optimized, it can be expected that the cultivation and cultivation effect of the plant will be further improved.

By the way, if a light source is composed of only white LEDs and an attempt is made to optimize the emission spectrum thereof, a phosphor that is easily deteriorated is used, and the optimized emission spectrum may change inappropriately over time. It becomes an issue. Further, a white LED having a low color temperature and a high color performance, which is in increasing demand as a light source for plant cultivation, has a problem of low luminous efficiency as compared with a white LED for general lighting and a monochromatic LED.

The present invention has been made in consideration of such circumstances, and in order to efficiently improve the growing effect, it is intended to provide an LED lighting technique for plant cultivation that can easily optimize the emission spectrum. The purpose.

In the LED lighting device for plant cultivation according to the present invention, a white LED having a continuous emission spectrum with a wavelength range of at least 450 nm to 700 nm, a monochromatic LED having at least one peak in the emission spectrum, and a plurality of the white LEDs are used. In addition to being arranged, it is characterized by including a circuit board for uniformly arranging the monochromatic LEDs in the group of white LEDs.

INDUSTRIAL APPLICABILITY The present invention provides an LED lighting technique for plant cultivation in which the emission spectrum can be easily optimized in order to efficiently improve the growing effect.

(A) An overall circuit diagram showing an LED lighting device for plant cultivation according to the first embodiment of the present invention, and (B) a partial circuit diagram showing an LED lighting device of another example. (A) A graph in which the emission spectra of a single white LED and a red LED, which are applied to the LED lighting device for plant cultivation according to the second embodiment, are superimposed, and (B) the emission spectra of the white LED and the red LED are synthesized. Graph. (A) A graph in which the emission spectra of a single unit of white LED, red LED and far-red LED, which are applied to the LED lighting device for plant cultivation according to the third embodiment, are overlaid, (B) white LED, red LED and The graph which combined the emission spectrum of the far-red LED. (A) A graph in which the emission spectra of a single white LED and an ultraviolet LED, which are applied to the LED lighting device for plant cultivation according to the fourth embodiment, are overlaid, and (B) the emission spectra of the white LED and the ultraviolet LED are synthesized. Graph. (A) A graph in which the emission spectra of white LEDs, red LEDs, and ultraviolet LEDs, which are applied to the LED lighting device for plant cultivation according to the fifth embodiment, are overlaid, and (B) white LEDs, red LEDs, and ultraviolet rays. The graph which combined the emission spectrum of LED. (A) A graph in which the emission spectra of white LEDs, red LEDs, far-red LEDs, and ultraviolet LEDs, which are applied to the LED lighting device for plant cultivation according to the sixth embodiment, are overlaid, (B) white LEDs, The graph which combined the emission spectrum of a red LED, a far red LED and an ultraviolet LED. A table showing the effect of the LED lighting method for plant cultivation according to each embodiment.

(First Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1A is a circuit diagram showing an LED lighting device 10A for plant cultivation according to the first embodiment of the present invention, and FIG. 1B is a partial circuit diagram showing an LED lighting device 10B of another example. be.

As shown in FIG. 1A, the LED lighting device 10A includes a white LED 11 having a continuous emission spectrum having a wavelength range of at least 450 nm to 700 nm, a monochromatic LED 12 having at least one peak in the emission spectrum, and a plurality of white LEDs. A circuit board (not shown) for arranging the LEDs 11 and uniformly arranging the monochromatic LEDs 12 in the group of the white LEDs 11 is provided.

As the white LED 11, one for general lighting having excellent luminous efficiency is used. As mentioned above, for the purpose of improving the growing effect, a white LED for plant cultivation that emits light with a lower color temperature and higher color rendering than this white LED for general lighting (color rendering value Ra = around 90, color temperature around 3000K). ) Is commercially available. However, this white LED for plant cultivation does not need to be positively adopted because the luminous efficiency of the chip is low and the amount of light is small.

Examples of the monochromatic LED 12 include a red LED 12a, a far-red LED 12b, and an ultraviolet LED 12c, which will be described later, but are not particularly limited. One type of these monochromatic LEDs 12 may be arranged, or two or more types may be arranged in combination.

As shown in FIG. 1 (B), in the LED lighting device 10B, the circuit board (not shown) is provided with a switch 16 for individually turning on / off the energization of at least one monochromatic LED 12.

In the LED lighting device 10B of FIG. 1B, the white LED 11 and the monochromatic LED 12 are connected in series with each other and are connected to the constant current circuit 15a. Then, in the LED lighting device 10A of FIG. 1A, a group of white LEDs 11 and monochromatic LEDs 12 connected in series to each other are further connected to each other in parallel (three rows in the drawing) and connected to the constant current circuit 15a. Has been done.

Here, the arrangement of the white LED 11 and the monochromatic LED 12 in the LED lighting device 10 is arranged so that one of them is not unevenly distributed as a whole so that the respective light emission is uniformly mixed with respect to the irradiation surface. In the example of FIG. 1A, one monochromatic LED 12 is regularly arranged every two white LEDs 11, but it is not particularly necessary to give regularity to this arrangement. Further, in FIG. 1A, each of the three illustrated columns has the same sequence, but may have different sequences.

The LED lighting device 10 accommodates a circuit board on which a white LED 11 and a single color LED 12 are mounted in a transparent cylinder, and by aligning the shape and length of the base, it is structurally compatible with a conventional straight tube fluorescent lamp. be able to. Further, the LED lighting device 10 is structurally compatible with the conventional incandescent light bulb by accommodating the circuit board on which the white LED 11 and the monochromatic LED 12 are mounted in a transparent hemisphere and matching the shape and size of the base. Can be held. For compatibility with incandescent light bulbs, the white LED 11 and the monochromatic LED 12 are arranged in a plane on a circular circuit board.

When the switch 16 is connected in parallel to the monochromatic LED 12 to be turned on / off as shown in FIG. 1B, the monochromatic LED 12 lights up when the switch 16 is open and monochromatic when the switch 16 is closed. The LED 12 goes out.

The switch 16 does not have to be provided for all the monochromatic LEDs 12, and may be provided according to the adjustment allowance of the monochromatic light to be combined with the light emission of the white LED 11. Specifically, the switch 16 short-circuits or conducts each other on a circuit board (not shown) by inserting or removing a conductor into a printed pattern of wiring that is not electrically connected. , Jumper, etc. Alternatively, the switch 16 may be a mechanical type that reversibly turns ON / OFF.

In this way, by configuring the LED lighting device 10 with the white LED 11 and the monochromatic LED 12, the R / B ratio (red / blue ratio) and the R / FR ratio (red / blue ratio) of the emission spectrum can be adjusted by adjusting the arrangement number ratio of these. The red / far-red ratio) can be optimized, and the effect of cultivating and growing plants can be improved.

Further, by providing the switch 16, the number of monochromatic LEDs 12 to be lit can be easily changed without changing the wiring pattern of the circuit board (not shown), and the R / B ratio and R / of the emission spectrum can be changed. The FR ratio and the like can be optimized. This means that if the optimum conditions such as R / B ratio and R / FR ratio differ depending on the type of cultivated plant and the growing stage, the optimum conditions can be set only by setting the switch 16 without significantly changing the product design specifications. Can be set. Alternatively, the distribution of the emission spectrum can be easily changed even in an experiment for searching for the optimum conditions of the cultivated plant.

The LED lighting method for plant cultivation according to the first embodiment is not limited to using the LED lighting device 10 described above. That is, a monochromatic LED is uniformly arranged in a group of white LEDs in which a plurality of LEDs are arranged, a continuous emission spectrum having a wavelength range of at least 450 nm to 700 nm is emitted from the white LED, and at least one peak is emitted from the monochromatic LED. Is carried out by causing the light emission spectrum to emit light.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 2A is a graph in which the emission spectra of the white LED 11 and the red LED 12a (monochromatic LED 12), which are applied to the LED lighting device 10 for plant cultivation according to the second embodiment, are overlaid. B) is a graph in which the emission spectra of the white LED 11 and the red LED 12a are combined. It should be noted that, in FIG. 2, the matters related to FIG. 1 are indicated by the same reference numerals, and duplicate description will be omitted.

For the circuit board of the LED lighting device 10 according to the second embodiment, a chip having a color rendering index Ra = 80 for general lighting and a color temperature of 5000 K is selected as the white LED 11, and the monochromatic LED 12 is centered in the wavelength range of 600 nm to 700 nm. A red LED 12a chip having a peak wavelength of 660 nm is selected.

Then, in the synthetic emission spectrum shown in FIG. 2B, the peak top derived from the red LED 12a existing in the red wavelength range of 600 nm to 700 nm and the peak top derived from the white LED 11 existing in the blue wavelength range of 415 nm to 500 nm. The number of lights of the red LED 12a is adjusted so that the R / B ratio of the above approaches 2.5.

The column of Example 2 in the table of FIG. 7 shows the effect of the LED lighting method for plant cultivation according to the second embodiment. As Comparative Example 1, the cultivation evaluation carried out on lettuce, tomato seedlings, and strawberries using a 40-inch fluorescent lamp was expressed with a reference value of 100 points.

Lettuce was used for leaf lettuce, tomatoes were used for tomato root seedlings, and growth was judged by comprehensively judging the volume, plant width, leaf size, color, etc. by visual inspection. Then, leaf lettuce was judged 20 days after planting, and tomato self-rooted seedlings were judged 19 days after sowing. In addition, for 6 strains of "Tochiotome" for strawberries, the petiole length, the number of fruits, the fruit weight, etc. were comprehensively judged as the factors for judging the growth, and the judgment was made one month after planting.

As a result, the evaluation of the second embodiment (Example 2) was 120 points for lettuce, 40 points for tomato, and 120 points for strawberry.

(Third Embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. 1 and 3. FIG. 3A superimposes the emission spectra of the white LED11, the red LED12a (monochromatic LED12), and the far-red LED12b (monochromatic LED12) applied to the LED lighting device for plant cultivation according to the third embodiment. FIG. 3B is a graph in which the emission spectra of the white LED 11, the red LED 12a, and the far-red LED 12b are combined. It should be noted that, in FIG. 3, the matters related to FIGS. 1 and 2 are indicated by the same reference numerals, and redundant description will be omitted.

The circuit board of the LED lighting device 10 according to the third embodiment includes a white LED 11, a red LED 12a as the monochromatic LED 12, and a far-red LED 12b having a peak of 735 nm in the center wavelength in the wavelength range of 700 nm to 800 nm as the monochromatic LED 12. Is placed.

Then, in the synthetic emission spectrum shown in FIG. 3 (B), the R / B ratio (= 2.5) is 700 nm to 800 nm with the peak top derived from the red LED 12a while maintaining the state of FIG. 2 (B). The number of lights of the far-red LED 12b is adjusted so that the R / FR ratio with the peak top derived from the far-red LED 12b existing in the far-red wavelength range approaches 5.

The column of Example 3 in the table of FIG. 7 shows the effect of the LED lighting method for plant cultivation according to the third embodiment. As a result, the evaluation of the third embodiment (Example 3) was 150 points for lettuce, 50 points for tomato, and 130 points for strawberry.

(Fourth Embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIGS. 1 and 4. FIG. 4A is a graph in which the emission spectra of the white LED 11 and the ultraviolet LED 12c (monochromatic LED 12), which are applied to the LED lighting device 10 for plant cultivation according to the fourth embodiment, are overlaid. B) is a graph in which the emission spectra of the white LED 11 and the ultraviolet LED 12c are combined. It should be noted that, in FIG. 4, the matters related to FIGS. 1 to 3 are indicated by the same reference numerals, and redundant description will be omitted.

On the circuit board of the LED lighting device 10 according to the fourth embodiment, a white LED 11 and an ultraviolet LED 12c having a peak with a central wavelength of 395 nm in the wavelength range of 350 nm to 425 nm as a monochromatic LED 12 are arranged.

Then, in the synthetic emission spectrum shown in FIG. 4B, UVA / of the peak top derived from the ultraviolet LED 12c in the ultraviolet wavelength range of 350 nm to 425 nm and the peak top derived from the white LED 11 existing in the blue wavelength range of 415 nm to 500 nm. The number of lights of the ultraviolet LED 12c is adjusted so that the B ratio approaches 1.

The column of Example 4 in the table of FIG. 7 shows the effect of the LED lighting method for plant cultivation according to the fourth embodiment. As a result, the evaluation of the fourth embodiment (Example 4) was 100 points for lettuce, 100 points for tomato seedlings, and 150 points for strawberries.

(Fifth Embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIGS. 1 and 5. FIG. 5A is an overlay of the emission spectra of the white LED 11, the red LED 12a (monochromatic LED 12), and the ultraviolet LED 12c (monochromatic LED 12) applied to the LED lighting device 10 for plant cultivation according to the fifth embodiment. FIG. 5B is a graph in which the emission spectra of the white LED 11, the red LED 12a, and the ultraviolet LED 12c are combined. It should be noted that, in FIG. 5, the matters related to FIGS. 1 to 4 are indicated by the same reference numerals, and redundant description will be omitted.

A white LED 11 and a red LED 12a and an ultraviolet LED 12c as monochromatic LEDs 12 are arranged on the circuit board of the LED lighting device 10 according to the fifth embodiment.

Then, in the synthetic emission spectrum shown in FIG. 5 (B), the R / B ratio (= 2.5) is in the same state as in FIG. 2 (B), and the UVA / B ratio (= 1) is in FIG. 4 (B). The number of lights of the red LED 12a and the ultraviolet LED 12c is adjusted so as to be in the same state as above.

The column of Example 5 in the table of FIG. 7 shows the effect of the LED lighting method for plant cultivation according to the fifth embodiment. As a result, the evaluation of the fifth embodiment (Example 5) was 120 points for lettuce, 110 points for tomato seedlings, and 170 points for strawberries.

(Sixth Embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIGS. 1 and 6. FIG. 6A shows white LED11, red LED12a (monochromatic LED12), far-red LED12b (monochromatic LED12), and ultraviolet LED12c (monochromatic LED12) applied to the LED lighting device 10 for plant cultivation according to the sixth embodiment. FIG. 6B is a graph in which the emission spectra of a single unit are overlaid, and FIG. 6B is a graph in which the emission spectra of the white LED 11, the red LED 12a, the far-red LED 12b, and the ultraviolet LED 12c are combined. It should be noted that, in FIG. 6, the matters related to FIGS. 1 to 5 are indicated by the same reference numerals, and redundant description will be omitted.

A white LED 11 and a red LED 12a, a far-red LED 12b, and an ultraviolet LED 12c as monochromatic LEDs 12 are arranged on the circuit board of the LED lighting device 10 according to the sixth embodiment.

Then, in the synthetic emission spectrum shown in FIG. 6 (B), the R / B ratio (= 2.5) is in the same state as in FIG. 2 (B), and the R / FR ratio (= 5) is in FIG. 3 (B). The number of lights of the red LED 12a, the far-red LED 12b, and the ultraviolet LED 12c is adjusted so that the UVA / B ratio (= 1) is the same as that in FIG. 4B.

The column of Example 6 in the table of FIG. 7 shows the effect of the LED lighting method for plant cultivation according to the sixth embodiment. As a result, the evaluation of the sixth embodiment (Example 6) was 150 points for lettuce, 130 points for tomato seedlings, and 200 points for strawberries.

As described above, the effectiveness of the effect on leafy vegetables such as lettuce and fruit vegetables such as tomato and strawberry was confirmed by using the LED lighting device for plant cultivation according to each embodiment. In addition, we have confirmed the effectiveness of the effects of chrysanthemums, perilla, and platycodon grandiflorum for electric lighting cultivation.

10 (10A, 10B) ... LED lighting device, 11 ... white LED, 12 ... monochromatic LED, 12a ... red LED, 12b ... far red LED, 12c ... ultraviolet LED, 15a ... constant current circuit, 15b ... constant voltage circuit, 16 …switch.

Claims (8)

A white LED with a continuous emission spectrum with a wavelength range of at least 450 nm to 700 nm,
A monochromatic LED with at least one peak in the emission spectrum,
An LED lighting device for plant cultivation, characterized in that a plurality of the white LEDs are arranged and a circuit board for uniformly arranging the monochromatic LEDs in the group of the white LEDs is provided. In the LED lighting device for plant cultivation according to claim 1.
The monochromatic LED is an LED lighting device for plant cultivation, which is a red LED having the peak in the wavelength range of 600 nm to 700 nm. In the LED lighting device for plant cultivation according to claim 2.
An LED lighting device for plant cultivation, wherein a far-red LED having the peak in the wavelength range of 700 nm to 800 nm is further provided as the monochromatic LED. In the LED lighting device for plant cultivation according to claim 1.
The monochromatic LED is an LED lighting device for plant cultivation, which is an ultraviolet LED having the peak in the wavelength range of 350 nm to 425 nm. In the LED lighting device for plant cultivation according to claim 2.
An LED lighting device for plant cultivation, wherein an ultraviolet LED having the peak in a wavelength range of 350 nm to 425 nm is further provided as the monochromatic LED. In the LED lighting device for plant cultivation according to claim 3.
An LED lighting device for plant cultivation, wherein an ultraviolet LED having the peak in a wavelength range of 350 nm to 425 nm is further provided as the monochromatic LED. The LED lighting device for plant cultivation according to any one of claims 1 to 6.
An LED lighting device for plant cultivation, wherein the circuit board is provided with a switch for individually turning on / off the energization of at least one of the monochromatic LEDs. A step of emitting a white LED having a continuous emission spectrum with a wavelength range of at least 450 nm to 700 nm,
Including a step of emitting a monochromatic LED having at least one peak in the emission spectrum.
An LED lighting method for plant cultivation, wherein the monochromatic LEDs are uniformly arranged in a group of white LEDs in which a plurality of LEDs are arranged.

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